cad modeling based thermal analysis of 60-kw universal
TRANSCRIPT
CAD Modeling Based Thermal Analysis of 60-kW Universal Battery Supercharger (UBS)
BY
ANIK NIRAJ DESAI
B. E Mechanical Engineering
Gujarat Technological University, 2017
THESIS
Submitted as partial fulfillment of the requirements
For the degree of Master of Science in Mechanical Engineering
In the Graduate College of the
University of Illinois at Chicago, 2019
Chicago, Illinois
Defense Committee:
Sudip K. Mazumder, Chair and Advisor, Electrical and Computer Engineering
Constantine M. Megaridis, Mechanical and Industrial Engineering
Brandon Passmore, Wolfspeed, Cree
ii
Dedicated to my family
iii
ACKNOWLEDGMENTS
I am grateful to my advisor Dr. Sudip K. Mazumder for giving me the opportunity to carry out research in his
laboratory, Laboratory for Energy and Switching-Electronics Systems (LESES) at the University of Illinois at
Chicago. His constant support and guidance helped me tackle all the difficulties in the process with ease. I would like
to thank my committee members Dr. Constantine M. Megaridis and Dr. Brandon Passmore for agreeing to be a part
of my thesis committee and for guiding.
I would especially like to thank my colleagues Dr. Ankit Gupta and Nikhil Kumar for their valuable inputs
throughout the journey. I am also thankful to my other colleagues Debanjan Chatterjee, Sandeep Sankaranarayanan,
Moien Mohamadi and Soumya Padmanabha for their support through thick and thin. I would also like to thank
Jonathan Komperda a faculty member, Chintan Desai and Ajaykrishna Ramasubramanian from Mechanical
Department, UIC for providing me important guidance.
I am thankful to my family, whose love and support helped me to complete this work. Finally, let me express my
deepest gratitude to God for the blessings.
AND
iv
TABLE OF CONTENT
CHAPTER PAGE
1. INTRODUCTION ............................................................................................................................................... 1
1.1 Background ...................................................................................................................... 1
1.2 Literature Review ............................................................................................................. 4
1.3 Thesis Outline and Organization ...................................................................................... 6
2. MODELING ........................................................................................................................................................ 7
2.1 CAD Model for the DC Fast Charger .............................................................................. 7
2.2 Thermal Analysis ........................................................................................................... 13
2.2.1 Model Simplification .............................................................................................. 13
2.2.2 Mesh Convergence.................................................................................................. 16
2.2.3 Model Synthesis for Thermal Model ...................................................................... 19
3. FIN-BASED COLD PLATE DESIGN .............................................................................................................. 28
3.1 CAD Design of Fin-Based Cold-Plate ........................................................................... 28
3.2 Design Modification and Result Discussion .................................................................. 31
CASE 1: Base Fin Structure ................................................................................................. 31
CASE 2: Varying Tube Diameter ......................................................................................... 32
CASE 3: Varying Openings between Tube and Fin Structure ............................................. 33
CASE 4: Inlet and Outlet on Either Side of the Cold-Plate .................................................. 35
CASE 5: Inlet and Outlet on Either Side of the Cold-Plate (Big Opening in M2) ............... 36
CASE 6: Inlet and Outlet on Either Side of the Cold-Plate (More Fin in M2)..................... 37
CONCLUSION ........................................................................................................................................................... 42
FUTURE WORK ........................................................................................................................................................ 43
APPENDIX A: SolidWorks ........................................................................................................................................ 44
APPENDIX B: ANSYS ............................................................................................................................................... 46
REFERENCES ............................................................................................................................................................ 50
VITA ........................................................................................................................................................................... 52
v
LIST OF TABLES
TABLE I: Dimensions for the individual parts used in the final assembly of v1.0 of the 60-kW dc fast charger. 7
TABLE II: Dimensions for the individual parts used in the final assembly of v2.0 of the 60-kW dc fast charger.
.............................................................................................................................................................................. 10
TABLE III: Loss generation for each part of the model. ..................................................................................... 13
TABLE IV: Property of water as a fluent. ........................................................................................................... 20
TABLE V: Boundary condition for fin-based structure. ..................................................................................... 31
TABLE VI: CAD design procedure of SiC Module. ........................................................................................... 44
TABLE VII: CAD design procedure for die placement inside SiC Module. ...................................................... 45
vi
LIST OF FIGURES
Figure 1: Different levels of battery chargers. ........................................................................................................ 1
Figure 2: Number of cycles to failure as a function of junction temperature (ΔTj) with mean temperature (Tm). 2
Figure 3: Liquid cooling system assembly. ............................................................................................................ 4
Figure 4: 3D CAD design for the V1.0 60-kW dc fast charger assembly. ............................................................. 9
Figure 5: Dimension for the V1.0 60-kW dc fast charger assembly. ...................................................................... 9
Figure 6: 3D CAD design for the V2.0 60-kW dc fast charger assembly. ........................................................... 11
Figure 7: Dimension for the V2.0 60-kW dc fast charger assembly. .................................................................... 12
Figure 8: Schematic of a die. ................................................................................................................................ 12
Figure 9: Equally distributed dies inside the module. .......................................................................................... 12
Figure 10: Thermal elements in UBS: cold plate, SiC module, and inductor. ...................................................... 14
Figure 11: Position of ‘U’ tube inside the cold plate. ........................................................................................... 14
Figure 12: Position of double-stacked ‘E’ core inside the inductor. ..................................................................... 15
Figure 13: Mesh points of two different bodies are not matching. ....................................................................... 16
Figure 14: Rebuild mesh with all bodies mesh points are matching. ................................................................... 17
Figure 15: Thermal mesh comparison with the number of elements. ................................................................... 17
Figure 16: Fluent mesh comparison with the number of elements. ...................................................................... 18
Figure 17: Thermal model without fluid. ............................................................................................................. 19
Figure 18: Thermal and fluid coupling phase 1. ................................................................................................... 19
Figure 19: Increase the temperature of fluent due to the heat load. ...................................................................... 20
Figure 20: Thermal model for transferring temperature from fluid to body phase 1. ........................................... 21
Figure 21: 'U' tube's different section views. (3 section (i), 35 sections (ii)). ....................................................... 22
Figure 22: Two way coupled thermal model phase 2. .......................................................................................... 22
Figure 23: Flow rate comparison with varying ΔT for modules’ starting and ending point. ................................ 23
Figure 24: Flow rate comparison with varying ΔT for inductors’ starting and ending point. .............................. 24
Figure 25: Cyclic checking for steady temperature (9 iterations). ........................................................................ 25
vii
LIST OF FIGURES (Continued)
Figure 26: Cold plate's top and bottom surface's steady temperature after the 6th iteration. ................................. 25
Figure 27: Flow rate comparison after iterative checking. (Top: 0.003 kg/s, Bottom: 0.0003 kg/s) .................... 26
Figure 28: Flow chart for the iterative cycle of getting a steady-state temperature. ............................................. 27
Figure 29: Fin based SiC module’s base (i) front view of the SiC module’s base (ii). ........................................ 28
Figure 30: Cold plate with the place for fin-based SiC module's base. ................................................................ 29
Figure 31: Thermal model with fin-based cold plate, SiC module, and inductor. ................................................ 29
Figure 32: Section A-A (i) and section B-B (ii) of Figure 31. .............................................................................. 30
Figure 33: Fluid flowing path: SolidWorks model (i) ANSYS simulation model (ii). ......................................... 30
Figure 34: Thermal result (i) and flow flowing quantity (ii) for basic fin-based structure tube. .......................... 31
Figure 35: Fin-based varying diameter tube (small to big)................................................................................... 32
Figure 36: Thermal result (i) and flow flowing quantity (ii) for varying diameter tube (small to big). ............... 33
Figure 37: Fin-based varying opening tube. ......................................................................................................... 33
Figure 38: Thermal result (i) and flow flowing quantity (ii) for varying openings tube. ..................................... 34
Figure 39: Fin-based tube with inlet and outlet on either side of the cold plate. .................................................. 35
Figure 40: Thermal result (i) and flow flowing quantity (ii) for a tube with inlet and outlet on either side of the
cold plate. ............................................................................................................................................................. 35
Figure 41: Fin-based tube with inlet and outlet on either side of the cold plate (big opening in M2). ................. 36
Figure 42: Thermal result (i) and flow flowing quantity (ii) for a tube with inlet and outlet on either side of the
cold plate (big opening in M2). ............................................................................................................................ 37
Figure 43: Thermal result (i) and flow flowing quantity (ii) for a tube with inlet and outlet on either side of the
cold plate (more fin in M2)................................................................................................................................... 37
Figure 44: Velocity in the middle position of case 4 (i) and case 6 (ii). ............................................................... 38
Figure 45: Different tube's cooling effect. ............................................................................................................ 39
Figure 46: Different tube's pressure drop. ............................................................................................................ 39
Figure 47: Tube's division in 12 equal grid for temperature using 1-norm. ......................................................... 40
viii
LIST OF FIGURES (Continued)
Figure 48: Fluid temperature comparison with variation in module base's temperature for all design cases. ...... 41
Figure 49: Dies steady temperature study. ........................................................................................................... 41
Figure 50: Steady-state thermal tool of ANSYS. ................................................................................................. 46
Figure 51: First half of the ANSYS model, in which data transfer is from the body to fluid. .............................. 47
Figure 52: External data tool of ANSYS. ............................................................................................................. 47
Figure 53: Fluent tool of ANSYS. ........................................................................................................................ 47
Figure 54: ANSYS model. ................................................................................................................................... 49
ix
LIST OF ABBREVIATIONS
AC Alternating Current
ANSYS ANalysis SYStem
CAD Computer-Aided Design
DC Direct Current
EV Electric Vehicle
EVSE Electric Vehicle Supply Equipment
GPM Gallons Per Minute
HCPAB High Current Printed Circuit Board
IBM International Business Machines Corporation
PCB Printed Circuit Board
SiC Silicon Carbide
UBS Universal Battery Supercharger
x
SUMMARY
Power electronics devices when operating at high power sometimes face performance issues due to poor thermal
handling. The main goal of this work is to get an effective design for a cold plate to manage the thermal load for
effective performance. The cold-plate design should be done such a way that it can deliver the required amount of
power, reduces the semiconductor losses and keeps the junction temperature in the acceptable limit. The work started
with designing the CAD model for the 60-kW Universal Battery Supercharger (UBS). Initially, two designs ‘V1.0 and
V2.0’ were made. The first version V1.0 did not match the power density and hence, the final version V2.0 with both
the factor satisfying was made. Hence, thermal analysis was done based on the second version V2.0. The thermal
analysis was done initially using thermal and subsequently, using fluent packages of ANSYS. Once the modeling part
was completed, for localized cooling of SiC module, the fin-based cold-plate design was made. With this fin-based
cold-plate design, initial results were taken and based on the required performance, minor changes in the cold plate
were made. After testing a total of six cold-plate designs with minor changes in it, the one with the most effective
cooling was selected.
1
1. INTRODUCTION
1.1 Background
With rising fuel prices, fuel unavailability, and increasing pollution the electric vehicle (EV) has become a fast-
growing technology which helps in reducing the reliability of liquid fuel-based vehicles. This EV works on the higher
system voltage in comparison to the golf cart or the industrial cart [1]. These EVs are charged through the electric
grid, they are also called electric vehicle supply equipment (EVSE). Based on the maximum amount of power charger
provides to the battery, the EV chargers are divided into three major categories level-1, level-2 and dc fast charger
(level-3) [2]. The comparison of these three levels of chargers is shown in Figure. 1 [3].
Figure 1: Different levels of battery chargers.
Currently used level-1 EV battery chargers are used for providing 120 V AC which is slow and time-consuming.
They take overnight time to get fully charged. To make it more efficient and less time-consuming level-2 chargers
were developed, they are used for providing 240 V (for residential) and 208 V (for commercial). And for the higher
power and more effectiveness DC fast chargers, also known as level-3 chargers, is made which provides 480 V AC
2
input which is even faster than the level-2 battery charger. Cars also require special equipment to get charged with
level 3 chargers. The typical charging time for an EV battery varies between 30 minutes to 20 hours or more depending
on the type of EVSE [2]. To expedite the EV charging time, a 60-kW Universal Battery Supercharger (UBS) is
pursued. This design is planned to meet the 98% efficiency, 150 W/in3 of power density, 5 kW/kg of specific power
and cost of 5 cents/watt in bulk production.
In EV applications, available volume and weight of various components are of the essence. Efforts are made to
shrink the components to make EVs more spacious and lightweight. This requires the manufacturers to move towards
electronics having a higher form factor and lower specific weight. In a battery charger, there are various types of losses
like switching losses, conduction losses, core losses, snubber losses, and damper losses which heats up the charger
[4]. These power losses lead to a temperature rise of the device and that affects the performance, lifetime, etc.
Temperature limit for a device to operate efficiently varies depending on the application, arrangement of the
components on the hardware prototype, operating condition and many more. Figure. 2 shows the impact of temperature
on the power electronics device’s performance [5].
Figure 2: Number of cycles to failure as a function of junction temperature (ΔTj) with mean temperature (Tm).
As shown in Figure. 2 the number of cycles for which a power electronics device can operate decreases as the
junction temperature increases. This increase in temperature of the parts can cause the speedy operation, life of parts
[6], hence, it is required to manage these power losses such that the device’s surface maintains the operating
3
temperature for the efficient performance for the longer duration. This requirement of lower working temperature of
the device surface leads towards the development of effective cooling techniques of the power electronics system.
As the demand of the high-power working capacity of the device is increased, the cooling system also needs to
increase its capacity for heat dissipation [7]. This, in turn, creates a design challenge for finding the most efficient yet
economical methods of removing excess heat for keeping the critical components within the optimum operating
temperature range. When it comes to the cooling system there are two options: natural convective cooling and forced
convective cooling. In both, the cases heat sink take part to build up the more contact surface area [8].
Natural convection is not enough for models operating at high power as it dissipates the high amount of energy
in terms of temperature. Hence, for a high power system, forced convective cooling is required for high efficiency and
higher power density. Forced convective cooling can be done with air or liquid. Heat transfer rate between fluid and
heating element depends on the material of element and the fluid properties like thermal conductivity, viscosity,
density, and velocity.
Because of air’s lower thermal conductivity, thermal specific heat and density, it turns out to be the least efficient
heat transfer medium with low heat transfer coefficient [9]. Moreover, in the air-based forced cooling heat spreader
plays an important role in carrying the heat from heatsink to air-cooled surface. Also, in air-based forced cooling, the
pumping power to cool the high-power electronic system is more compared to the liquid-based cooling. Moreover,
due to the higher specific heat capacity and thermal conductivity of the liquid, it is more efficient compared to air [7].
For heat transfer with liquid cooling can be achieved in two ways: direct contact or indirect with the fluid [9].
When the fluid is not in direct contact of the element, such as a tube, fin, etc. through the cold plate, the common
coolants are water, or a mixture of water and ethylene glycol are used [9]. A typically closed-loop liquid cooling unit
comprises of a heat exchanger, a pump and a heat sink. Hot fluid from cold-plate enters the heat exchanger where it
transfers the heat and gets cold and enter again into the cold-plate through the pump. Basic working diagram of a
closed-loop liquid cooling unit is illustrated in Figure. 3.
4
Figure 3: Liquid cooling system assembly.
1.2 Literature Review
Ilya et al [8] experimented several tube-based designs for testing the influence of several design parameters. In
their study, they tested the system by increased the thickness of plate and tube diameter with reference of default
design. Also, they tested the design by increasing the channel length and inserting a turbulator. From the experimental
results, they observed that at higher pumping power design with the higher diameter shows higher thermal resistance
while the design with higher channel length shows the lower thermal resistance. The author has concluded that it is
better to increase the channel length rather than the tube diameter for achieving lower thermal resistance. Also, design
with turbulator the author was not able to achieve significantly different results.
Webb [11] compared the micro and macro channel cooler with water in laminar flow. Macro-channel was
designed with 4.5 mm width and 10 mm depth while the micro-channel was designed with 0.54 mm fin pitch, 2.1 mm
fin height. Moreover, he studied the one and two pass micro-channel cooler. He found that 1-pass gives lower thermal
resistance and lower pressure drop hence from that 1-pass is selected for the comparison with macro channel cooler.
In the study between micro and macro channel, he observed that the micro-channel provides lower thermal resistance
and pumping power than the macro channel cooler.
Kandlikar and Hayner [10] focused on the types of cold plate design and channel layout for better thermal
performance. For that, they have compared four types of cold plate design formed tube cold plate (FTCP), deep drilled
cold plate (DDCP), machined channel cold plate (MCCP), and pocketed folded- fin cold plate (PFCP). Further, they
5
have discussed liquid types, manufacturing issues, general design approach, etc. From the four cold plates, FTCP is
used for the lower power applications. At the higher power, DDCP and MCCP give better performance. PFCP is used
for better cooling effect for some area, for that fins are implemented in it. For the different types of liquid water and a
mixture of water and ethylene glycol are the commonly used ones. If water is used as coolant then it should be the
plain water and used only in controlled environments because tap water may hold somen active irons or other
impurities, which affects the flow channel. For some testing, it is advisable to use the water and ethylene glycol
mixture as it increases the boiling temperature and reduces the freezing temp. Among the several manufacturing issues,
the common one is when thermocouples are placed on the drilled cold plate. As it is costlier it is not advisable to do
that, but surface mounting thermocouples are used instead. As the general design approach, several factors like flow
rate, wall temperature, pressure drop are the different variables which should be taken into consideration for the design
aspects. Moreover, the type of cooling (uniform cooling or not) the placement of the devices is change or the fluid
inlet and outlet position or their number (multi-inlet/outlet or single) varies accordingly. In case of the multiple channel
design number, length and pitch of the channel depend on the available heat flux. Higher the heat flux, shorter the
pitch, and smaller channel length.
Sukhvinder et al [12] discussed the different types of cooling technologies for managing the heat dissipation and
junction temperature for effective performance with cost, efficiency, and reliability. For that, they have discussed the
forced air cooling, loop thermosiphon air cooling, and liquid cooling. In forced air-based cooling, different designs
were tried like heat sink with copper base, heat sink with heat pipes in an aluminum base and heat sink with increasing
the fin density in the flow direction. The disadvantage of these designs is that it limits the electrical design and
packaging flexibility of the system. Hence to overcome this shortcoming thermosiphon was tried. In the thermosiphon
design, the opposite direction flow of vapor along the wall tube limits the maximum power capacity because of the
liquid entrainment. Hence the loop thermosiphon was used to avoid this. This gives improved thermal performance,
lower pressure drops. The issue with this design is due to the greater number of equipment it is not advisable where
the size and handling factor is counted. That leads them to the liquid-cooled cold-plate design. In the liquid cooling
based cold-plate, the design for a single side as well as the double-sided cooling of the cold-plate was discussed and
suggested to reduce the fin height for more improvement of thermal performance.
All the methods discussed above with regards to cooling power electronics system have their own significance
and importance based on the requirement of the system. Between air and liquid cooling system, it is observed that the
6
liquid-based cooling system gives more efficient result because of their higher conductivity and arrangement of the
electronic components and flow patterns in the cold-plate design. In liquid-based cooling, several types of design like
a tube, fin, channel, etc. are discussed. Tube-based cold plate design is useful for the lower power applications while
for the higher power channel-based designs are used. Moreover, in some application localized cooling effect is
required for individual component along with the overall cooling of the system in such case cold plate with the fin is
more advisable. In this study, the main objective is to cool down the SiC module along with the other components of
the system hence, the fin-based structure of the cold plate is selected. Because of the simplicity, the modeling part is
done with the tube-based cold-plate structure and the finally fin-based structure is tested for localized cooling of the
system.
1.3 Thesis Outline and Organization
In this work, an optimal design of the liquid-based cooling system for a 60-kW level-3 dc fast charger is provided.
First, a CAD model of the 60-kW UBS was designed in SolidWorks. The CAD modelling was followed by the ANSYS
model in which two tools were used: thermal and fluent. For simplicity and better accuracy of the results, model
simplification and mesh convergence were performed on 60-kW UBS model. Later for localized cooling effect new
cold-plate with fin-based structure was modelled and tested with some minor modifications in different six designs as
per the cooling requirement.
In chapter 1, a brief introduction to different types of EV battery chargers is delineated. In this chapter, the need
for thermal analysis for an EV battery charger along with the type of the cooling system for efficient heat transfer is
discussed. Chapter 2 describes how and why design is selected for the 60-kW UBS along with the CAD modeling of
the design. Further, in this chapter, a brief explanation of the procedure on how the ANSYS simulation is modeled is
provided. After the modeling section, in chapter 3, the analysis of six different types of designs is carried out to
determine the cooling performance of the liquid-based cooling system. Finally, the thesis is concluded with the
selection of the optimum design of the liquid-based cooling system.
7
2. MODELING
2.1 CAD Model for the DC Fast Charger
CAD model using SolidWorks was designed for having an estimate on the final dimensions and volume of the
60-kW dc fast charger. For achieving an overall power density of more than 150W/in3 for a 60-kW unit, the goal for
the CAD design was to attain a total volume of fewer than 400 in3. In this report, two designs for the dc fast charger
are proposed for achieving the target volume.
The first step in the design process is to design the individual parts separately. Some of the components used in
the final assembly like magnetic cores, capacitors, SiC modules, and gate drives had fixed dimensions and were
selected from the components available off-shelf. However, few components like the cold plate and PCB had to be
custom designed as per the system requirement. Dimensions of the different components used in V1.0 are provided in
Table 1. A 3D CAD design for the V1.0 dc fast charger assembly is provided in Figure. 4 and various dimensions for
the assembly are outlined in Figure. 5.
TABLE I: Dimensions for the individual parts used in the final assembly of v1.0 of the 60-kW dc fast charger.
Item Dimension Image
PCB
(Custom made)
L=15.62 in, W= 5.91 in,
H= 0.24 in
E-Core
(00X114LE060)
L=4.5 in, W=1.82 in,
H= 1.38 in
8
Bobbin
(00B114LB1)
L=2.47 in, W= 2.97 in,
H= 2.2 in
Cylindrical Capacitor
(ALA7DC821DF400)
H = 1.57 in, D = 1.18 in
AC-Capacitor
(RCER73A104K5B1H0
3B)
L= 0.62 in, W= 0.37 in,
H= 0.12 in
Film Capacitor
(MKP1848C62580JP4)
L= 1.73 in, W= 1.65 in,
H= 0.95 in
Module
(HT-3232-R-VB)
L= 4.33 in, W= 2.56 in,
H= 0.48 in
hPin = 0.2 in
Cold plate
(Custom made)
L= 15.62 in, W= 5.91 in,
H= 0.98 in
Gate Driver
(CGD15HB62LP)
H= 4.33 in, W= 2.56 in,
H= 1.2 in
Hpin holder = 0.19 in
9
Figure 4: 3D CAD design for the V1.0 60-kW dc fast charger assembly.
Figure 5: Dimension for the V1.0 60-kW dc fast charger assembly.
10
Using the dimensions provided in Figure. 5, the final volume for the V1.0 dc fast charger assembly can be
calculated as L x W x H (15.62 x 5.91 x 5.33) = 492.035 in3. This volume is 92 in3 more than the desired volume and
can reduce the system power density to 122 W/in3 which is way less than the required power density.
To achieve the required power density some components were redesigned and replaced. In the V2.0 design of the
dc past charger coupled inductors were redesigned and instead of using a single core for the coupled inductor, two
smaller cores were stacked in parallel. Further, the orientation of SiC Module, E-Core, DC bus capacitors, and the
Gate Driver were changed. Based on the system requirements dimension for the cold plate was managed. Dimensions
for the individual parts that were replaced or redesigned are provided in Table 2. Additionally, a 3D view of final
CAD design for the V2.0 dc fast charger is provided in Figure. 6 with its dimensions outlined in Figure. 7.
TABLE II: Dimensions for the individual parts used in the final assembly of v2.0 of the 60-kW dc fast charger.
Item Dimension Image
Bobbin
(Custom made)
2.47 x 2.2 x 2.3 in3
E-Core
(00X8044E026)
3.15 x 1.76 x 0.78 in3
Cold Plate
(Custom made)
19 x 3.74 x 0.98 in3
11
Figure 6: 3D CAD design for the V2.0 60-kW dc fast charger assembly.
Cylindrical Capacitor
(EKMR3B1VSN102MR50S)
h = 1.96 in, d = 1.18 in
PCB
(Custom made)
19 x 3.74 x 0.24 in3
12
Figure 7: Dimension for the V2.0 60-kW dc fast charger assembly.
After changing the dimensions and orientation of some components as mentioned above in Table 2, the volume
of the V2.0 dc fast charger is L x W x H (19 x 3.74 x 5.54) = 393.672 in3. Adding the bus bars and outer casing to this
design the final volume will be less than 400 in3.
To be more specific about the design of module there are 16 dies inside the module which are the main source of
heat. Based on the available dimensions of the die (L x W x H = 0.29 x 0.17 x 0.08 in3) a cube is made for it as shown
in Figure. 8. These 16 dies are placed in the SiC Module in 2 rows each with 8 dies in it as shown in Figure. 9.
Figure 8: Schematic of a die.
Figure 9: Equally distributed dies inside the module.
13
2.2 Thermal Analysis
In this section, the modeling part of thermal analysis is discussed along with model simplification and mesh
convergence. For thermal modeling two ANSYS tools are selected ANSYS Thermal and ANSYS Fluent.
2.2.1 Model Simplification
TABLE III: Loss generation for each part of the model.
Part Name Generated Loss (W)
PCB (Custom made) 50
E-Core (00X8044E026) 393
DC-Capacitor (EKMR3B1VSN102MR50S) 28.86
AC-Capacitor (RCER73A104K5B1H03B) 9
Film Capacitor (MKP1848C62580JP4) 31.25
Module (HT-3232-R-VB) 950
Gate Driver (CGD15HB62LP) 15
From Table 3 it is seen that every part is not generating a big amount of loss only a few of them are generating
big loss PCB, E-core, DC-Capacitor, Film Capacitor, and module. Among all of them, two are main module and E-
core (generating 950 W 393 W respectively) which are in direct contact with the cold-plate while others are not
connected with cold-plate directly. Loss generated by others can also be dissolved in the air due to their low value.
Hence for the simplification of the problem only module and inductor (double-stacked E-cores) were taken along with
a cold plate for the analysis purpose which is only the heat source in the model as shown in Figure. 10.
14
Figure 10: Thermal elements in UBS: cold plate, SiC module, and inductor.
CAD model selected for thermal analysis has cold-plate, Inductor which contains the two double-stacked ‘E’ core
and Module as shown in Figure. 11 and Figure. 12 respectively. For simplicity, the U shaped tube is taken for
modeling.
Figure 11: Position of ‘U’ tube inside the cold plate.
15
Figure 12: Position of double-stacked ‘E’ core inside the inductor.
There are basically three sources of heat in the model. The heat from each module of 318 W, heat from each
inductor of 131 W and the natural convection which has a convective coefficient of 439 W/m2K and the ambient
temperature of 293 K.
16
2.2.2 Mesh Convergence
It is required to do the mesh convergence study for better accuracy of the result. To begin with, first I checked
whether the mesh points on different parts of the body are matching with each other or not. As shown in Figure. 13
the mesh points of the different body are not matching, which may lead to poor result output due to poor data transfer
from one to the other body of the model.
Figure 13: Mesh points of two different bodies are not matching.
Reason for this to happen is ANSYS was considering each part of the model as a single entity instead of
considering it as a whole. To overcome this problem in the geometry section of the Steady-State Thermal tool except
for the Tube, I took all other parts into a group and named them a Solid part and changed Tube’s property from solid
to fluid. After this, the issue of points matching of mesh is solved as shown in Figure. 14. As shown there each body’s
mesh is matching with their neighbor body’s mesh which will help to get better accuracy for the result. Once the mesh
matching is done, it is required to check the mesh convergence with different size of the mesh. For that, in the Steady-
State Thermal tool, I tried with a coarse, medium and fine mesh of the body. To see its effect on results I have noted
down the temperature of the tube and number of elements of mesh in all 3 cases. As shown in Figure. 15 temperature
difference is negligible (in decimals) hence we can say that the results are not changing with different types of mesh.
17
As there is not a big difference in temperature but there is a big difference for the number of elements between all the
cases. To begin with, the coarse mesh has 37,226 elements, that increases to almost double for the medium mesh to
68,654 elements and for fine mesh, it is 165,221 elements. With a greater number of elements, the computation time
increases hence, to get better results with less computation time it is decided to go with coarse mesh.
Figure 14: Rebuild mesh with all bodies mesh points are matching.
Figure 15: Thermal mesh comparison with the number of elements.
18
These thermal results are then transferred to the fluent section where the fluid is analyzed. Once the fluent part is
done then again, those results are transferred back to the thermal to get the idea of its effect back on the model. Hence
to get better accurate results for the data transfer from fluent to thermal it is important to check the mesh convergence
for the fluent section as well. For that, the mesh size of the tube is reduced until we get a steady temperature for the
plate. Figure. 16 shows the temperature variation for the plate based on the number of elements of the mesh. After one
point at the number of elements 1,648,512 the temperature variation is in decimal points, hence we decided to go
further with the mesh with elements 1,648,512.
Figure 16: Fluent mesh comparison with the number of elements.
19
2.2.3 Model Synthesis for Thermal Model
To begin the analysis, steady-state thermal was selected to have an idea of how it works for the model without
fluid. For that, all the available inputs are applied to the ANSYS. The heat from the SiC module and inductor were
applied as the intermediate heat generation (W/m3) along with the natural convection and the effect on the model is
shown in Figure. 17 where the range of temperature varies from 316.69 K to 380.25 K.
Figure 17: Thermal model without fluid.
By applying the heat inputs in the ANSYS Thermal the plate’s temperature was determined. Now to get the effect
of fluid on the cold-plate ANSYS Thermal and ANSYS Fluent are coupled as shown in Figure. 18.
Figure 18: Thermal and fluid coupling phase 1.
20
Here in Steady-State Thermal (A), the whole body except tube is taken into consideration for study with each
heat inputs while in Fluent (B) the only tube is taken with according fluid parameters. Water with parameters shown
in Table 4 is taken as the fluid.
TABLE IV: Property of water as a fluent.
Property Value with Unit
Density 998.2 kg/m3
Specific Heat (CP) 4.182 kJ/kgK
Thermal Conductivity 0.6 W/mK
Viscosity 0.001003 kg/ms
Inlet Temperature 293 K
Inlet Pressure 101.325 kPa
Data from these two tools are compiled in system coupling and data is transferred from thermal to fluent. So
basically, in this section, the heat generated due to the heat inputs from the module and inductor is transferred to the
fluid and its temperature raises gradually as shown in Figure. 19.
Figure 19: Increase the temperature of fluent due to the heat load.
21
Next target is to transfer this fluid temperature back on to the body parts so that we can observe the cooling effect
of fluid on the model. For that, I took one more Steady-State Thermal tool (shown in Figure. 20) in which I applied
all the same conditions as previous and added one more temperature input at the tube section. For this tried two ways
to implement the temperature of the fluid at the location. One by taking the average temperature for three sections of
the tube and second to reduce the error took more than three sections (35) of the tube and applied average temperature
for those sections as shown in Figure. 21.
Figure 20: Thermal model for transferring temperature from fluid to body phase 1.
22
Figure 21: 'U' tube's different section views. (3 section (i), 35 sections (ii)).
Transferring results in this fashion may lead to human error due to an error in taking the average of the different
sections. For that, there must be a direct way to transfer these results from one to another way (two-way coupling) to
get the cooling effect of the fluid. For that, a model of two way coupling between ANSYS Thermal and ANSYS
Fluent is made for thermal analysis as shown in Figure. 22.
Figure 22: Two way coupled thermal model phase 2.
(i) (ii)
23
In this model like the previous one whole problem is divided into two sections. The upper section of the model
(Section A-D) solves the problem up to the fluid gains the heat while the lower section (Section E-G) shows the effect
of that fluid on the body. As explained earlier in section A (Steady-State Thermal) the whole body without the tube is
solved with all the heat inputs. A results file from that is imported into section B (External Data) and in section C
(Fluent) fluid is implemented. Section B and C are solved in section D (System Coupling). From that, the heated fluid
data is exported with file and that file is imported in section E (External Data). As the heat inputs are still there when
the fluent temperature is transferring to body duplicate of section A is taken for further examination as section F.
These two sections E and F are solved in section G (System Coupling) and the final output shows in the result part of
Steady-State Thermal.
Deciding the flow rate for the coolant is an important part. For that initially few flow rates were checked, in that
as shown in Figure. 23 and 24 temperature difference (ΔT) between the module and inductor’s starting and ending
point are taken as a reference.
Figure 23: Flow rate comparison with varying ΔT for modules’ starting and ending point.
24
Figure 24: Flow rate comparison with varying ΔT for inductors’ starting and ending point.
From both Figure. 23 and 24 it is observed that flow rate 0.3 kg/s and 0.03 kg/s are too fast to absorb heat from
the other components of the model while the flow rates 0.003 kg/s and 0.0003 kg/s follow the temperature profile as
the without a fluid case. Hence based on this it is decided to go further with two flow rates 0.003 kg/s and 0.0003 kg/s.
It is very important to check that with the selected two flow rates, the model we created is giving us steady results
or not. For that, we should check by making the cyclic model. For that, I have taken the last result file of the first cycle
as the input and continued the whole process until I get a steady temperature as shown in Figure. 25. The temperature
of the plate remains steady after the 6th iteration. As shown in Figure. 26 from the 6th iteration plate’s top and bottom
side’s temperature vary in decimals, so we can say that the steady temperature is achieved after the 6th iteration of the
thermal model.
25
Figure 25: Cyclic checking for steady temperature (9 iterations).
Figure 26: Cold plate's top and bottom surface's steady temperature after the 6th iteration.
26
This iterative checking is done with two flow rates 0.003 kg/s and 0.0003 kg/s. For both the cases after 6th iteration
steady temperature starts but as shown in Figure. 27 the temperature of the body is reduced to inlet fluid temperature
in case of 0.003 kg/s flow rate. Hence it is decided that 0.0003 kg/s will be considered as a flow rate for results.
Figure 27: Flow rate comparison after iterative checking. (Top: 0.003 kg/s, Bottom: 0.0003 kg/s)
Based on the Reynold number, type of mesh, grid size and the solution method is selected. In this case, the selected
flow rates give us the Reynold number around 400 which is the Laminar flow hence, SIMPLE as the pressure-velocity
coupling scheme, a second order for pressure while second-order upwind for momentum and energy is selected as a
solution method. This whole iterative process of getting the steady-state temperature works as shown in the flow chart
below.
27
Figure 28: Flow chart for the iterative cycle of getting a steady-state temperature.
28
3. FIN-BASED COLD PLATE DESIGN
Once the modeling part is done it is required to decide the design of the product. Design of the product is based
on the requirement of the result. In this case, our main target is to cool down the SiC Modules’ base for effective
performance. This is the case of localized cooling effective. For the localized cooling fin-based, cold plates are
advisable, in which fins are placed in the local region where cooling is more required.
3.1 CAD Design of Fin-Based Cold-Plate
The reference for the fin structure-based cold plate is taken from the Wieland microcool [13]. Based on the
information available on their website fin-based cold plate is designed and further modifications are done based on
the result improvisation. The main part of the fin-based cold plate is the base where the fins are placed for the localized
cooling. The design of the fin-based SiC module’s base is shown in Figure. 29. The dimensions of the fin structure
are:
a = 76.96 mm d = 3.05 mm
b = 72.90 mm e = 1 mm
c = 4 mm f = 2 mm
Figure 29: Fin based SiC module’s base (i) front view of the SiC module’s base (ii).
This module’s base is going to fit in the cold plate. The location of the fin-based module base is decided based
on the location of SiC Module in the model. The SiC modules are placed such that the fin-based module base covers
29
the dies inside the module. The cold plate with the position of the module’s base is shown in Figure. 30. The whole
assembly with Fin-Based Cold-Plate, SiC Module, and Inductor is shown in Figure. 31, while its two sections A-A
and B-B are shown in Figure. 32.
Figure 30: Cold plate with the place for fin-based SiC module's base.
Figure 31: Thermal model with fin-based cold plate, SiC module, and inductor.
30
Figure 32: Section A-A (i) and section B-B (ii) of Figure 31.
For the simulation perspective, it is required to make the model of the fluid path. This is nothing but the replica
of the fluid flowing area from the cold plate. At the time of the ANSYS simulation, the boundary condition related to
the fluid is given to this part of the final assembly. The structure of this fluid flowing path is shown in Figure. 33.
Figure 33: Fluid flowing path: SolidWorks model (i) ANSYS simulation model (ii).
As shown in Figure. 33 (i) the length of the tube is chosen as 16 inches as per the end of last fin structure position.
This is the basic structure of the fin-based cold-plate design, further modification in this is done based on the result
improvisation.
(i) (ii)
(i) (ii)
31
3.2 Design Modification and Result Discussion
The design is shown in Figure. 31 and Figure. 33 (i) is the base model of the fin-based structure. With water as a
fluid, the initial results are taken on this design which is shown in Figure. 34. The boundary conditions applied to the
simulation is as given below:
TABLE V: Boundary condition for fin-based structure.
Parameter Value
Mass Flow Rate 0.05 GPM (0.00315 kg/s)
Inlet Temperature 293 K
Initial Pressure 101.325 kPa
Inductor Losses 393 W
SiC Module Losses 950 W
Convective Coefficient 439 W/m2 K
CASE 1: Base Fin Structure
Figure 34: Thermal result (i) and flow flowing quantity (ii) for basic fin-based structure tube.
(i) (ii)
32
In Figure. 34 the ANSYS simulated result is shown for the basic fin-based structure. Figure. 34 (i) shows the
thermal analysis while (ii) shows the flow flowing pattern as well as the amount of fluid flowing through each position.
It is seen in Figure. 34 (ii) that as we go further from inlet the fluid is trying to use the shortest path between inlet and
outlet, that is observed in Figure. 34 (i) as well. The cooling effect is reduced from first to the third position due to
less amount of fluid in it. To overcome this, it is required to increase the resistance in the first place, also as the position
is moved further the resistance should be decreased so that fluid can enter equally in all the positions. For that design
with a tube with varying diameter is designed.
CASE 2: Varying Tube Diameter
For increasing the resistance in the first position diameter is changed in this case. To force the fluid to go further
in the middle and last position compare to the first one diameter of the tube is changed. The tube diameter is varying
from small to big as shown in Figure. 35 that will increase the pressure of the fluid as it enters the bigger diameter
area as the force is inversely proportional to cross-sectional area (Pressure = Force/Area).
Figure 35: Fin-based varying diameter tube (small to big).
Thermal analysis is done on this tube with the same boundary condition Table 1 and the same fluid. The results
are shown in Figure. 36 (i) and (ii). Due to increased pressure along the length of the tube from inlet fluid is entering
33
more in the last position while it is quite less in the middle position compare to the previous case. The cooling effect
is shown in Figure. 35 (i) and the flow pattern in (ii). Due to not much effectiveness in this design as well as other
design with varying openings between tube and fin structure is designed.
Figure 36: Thermal result (i) and flow flowing quantity (ii) for varying diameter tube (small to big).
CASE 3: Varying Openings between Tube and Fin Structure
As discussed before in both the cases (1 and 2) the amount of fluid entering in all three positions is not equal. As
a different approach in this case plate is designed such that the opening area between the tube and the fin structure
varies.
Figure 37: Fin-based varying opening tube.
(i) (ii)
34
As shown in Figure. 37 the connecting area is increasing along the length of the tube from the inlet, the opening of
the first position is the smallest while last position’s opening is biggest amongst three of them (a < b < c). Because of
these change in opening fluid should enter less in the first one because of the small opening area and it should increase
as we go further with the big opening area towards the end of the tube. Thermal analysis and the flow pattern for this
case is shown in Figure. 38 (i) and (ii) respectively.
Figure 38: Thermal result (i) and flow flowing quantity (ii) for varying openings tube.
From Figure. 38 it is observed that the flowing pattern is different than the previous case 2 but it follows more of
a first case pattern. If we compare the second position of all the cases than it is seen that this case gives the best
performance, that can be confirmed with the help from (ii) of Figure. 34, 36, & 38, the amount of fluid flowing through
the second position is more, in this case, compare to the previous both cases and that gives more cooling effect as
well. While for the third case there is not much big change in all 3 cases except a bit good performance for the second
case, but still it is not advisable for the effective cooling of the model. After all this testing it is observed cooling with
more effectiveness is not there, by making a change in the resistance for the different positions, fluid is trying to get
the shortest path between the inlet and the outlet. Hence it is required to make a design which gives the longer path
between the inlet and the outlet such that the fluid can enter properly in all the positions and can give the better and
fast cooling effect to the model. That leads us to the change in design with inlet and outlet at the different side of the
cold-plate than the same side.
(i) (ii)
35
CASE 4: Inlet and Outlet on Either Side of the Cold-Plate
To increase the path length between the inlet and outlet location of inlet and outlet is changed to a different
location of the tube rather than the same location. Figure. 39 shows the design of the tube with an inlet and outlet at a
different location.
Figure 39: Fin-based tube with inlet and outlet on either side of the cold plate.
Figure 40: Thermal result (i) and flow flowing quantity (ii) for a tube with inlet and outlet on either side of the cold plate.
(i) (ii)
36
Figure. 40 (i) and (ii) shows the thermal and flow pattern respectively for this case. It is observed that the cooling
effect is improved in the last position. This improvement is the best amongst all the cases studied earlier. Not only for
the last position but also in the second position the improvement is observed compare to all the previous cases. Despite
the improvement in all the position, there is a scope of improvement in the second position. To reduce that heat spot
of the second position shown in Figure. 40 (i) designed is changed.
CASE 5: Inlet and Outlet on Either Side of the Cold-Plate (Big Opening in M2)
We observed in case 3 that by making the opening big the cooling effect in the second position is improved.
Hence for removing the hot spot in the second position the opening for that position is changed and it is bigger than
the rest of the two openings. Figure. 41 shows the structure of this case. In this case, the first and last openings are the
same while the middle one is smaller than those two (a < b).
Figure 41: Fin-based tube with inlet and outlet on either side of the cold plate (big opening in M2).
37
Figure 42: Thermal result (i) and flow flowing quantity (ii) for a tube with inlet and outlet on either side of the cold plate (big opening in M2).
From Figure. 42 it is observed that by making the opening of middle position the fluid is entering more in it and
the cooling effect is improved but still it is required to reduce the hot spot of that middle section. From (ii) of Figure.
40 and 42 it is observed that not like the previous cases that fluid not enough in particular section, here fluid is flowing
through the middle section. Hence to improve the cooling effect we can reduce the velocity of the fluid there such that
it can increase the cooling effect for that area.
CASE 6: Inlet and Outlet on Either Side of the Cold-Plate (More Fin in M2)
To reduce the fluid velocity in some region the area for the fluid to flow should be decreased. To implement that
the fin density in that section is increased by increasing the number of fins from 33 to 40. For that, the pitch is reduced
from 0.8 mm to 0.5 mm. this will allow the fluid to flow slowly compare to previous cases and will improve the
cooling effect for that section.
Figure 43: Thermal result (i) and flow flowing quantity (ii) for a tube with inlet and outlet on either side of the cold plate (more fin in M2).
(i) (ii)
(i) (ii)
38
Figure 44: Velocity in the middle position of case 4 (i) and case 6 (ii).
From Figure. 44 it is observed that by increasing the number of fins in the middle position the fluid velocity is
reduced to 0.0049 m/s from 0.0057 m/s. Effect of this reduced velocity is shown in Figure. 43 (i). Due to this, the
cooling effect is improved and the hot spot in the middle position is reduced. The overall comparison for different
tube’s cooling effect and pressure drop of all the cases is shown in Figure. 45 and 46 respectively.
(i)
(ii)
39
Figure 45: Different tube's cooling effect.
Figure 46: Different tube's pressure drop.
From Figure. 45 we can say that the cooling effect of Case 4, 5 and 6 are almost similar except the middle position.
Cooling effect in the middle position is improved by changing the opening of the middle section and more improved
by increasing the number of fins. As shown in Figure. 46 the pressure drop for all the cases is almost similar except
40
the case 2. In case 2 the pressure is increased after the inlet section due to the increased cross-sectional area of the
tube and on the other side it is reducing towards the outlet of the tube, hence there is a big difference in pressure from
inlet to outlet.
Temperature plot in Figure. 45 is for the SiC Module’s base temperature. For deciding better performing cold-
plate design regarding SiC Module’s thermal relief, the temperature of the fluid. Therefore, temperature plot of all the
six different designs (Figures 34(i), 36(i), 38(i), 40(i), 42(i) and 43(i)) are divided into 12 equal parts as shown in
Figure 47 and 1-norm is calculated for fluid in each position(T1−norm = ∑ Tiai
A
12i=1 ).
Figure 47: Tube's division in 12 equal grid for temperature using 1-norm.
By following that method for each position’s temperature, the result, we obtained are compared with the result
shown in Figure 45. As shown in Figure 48 the position with the higher fluid temperature is giving lower ∆T for each
one of the cases and highest ∆T for lowest fluid temperature. From this comparison, it is seen that in the cases with
inlet and outlet on either side of the cold-plate is giving better performance compared to all previous cases. Fluid
temperature for the first position is almost the same in all cases. But, for the last position case, 6 with inlet and outlet
on either side (more fins in M2) shows the best result while the same trend is followed in middle position with less
effectiveness.
41
Figure 48: Fluid temperature comparison with variation in module base's temperature for all design cases.
To check the improvement from beginning to end iterative testing for case 1 and case 6 is done. In this study, the
steady temperature of all the dies is compared for case 1 and 6 for the same number of iterations and with same
boundary conditions. As shown in Figure. 49 the final case 6 shows a better performance for all dies of each module.
The case 6’s die temperature is steady but after the same number of iterations still, the case 1’s module 2 and module
3’s die temperatures are not steady, this shows that the case 6 gives much better performance.
Figure 49: Dies steady temperature study.
0
2
4
6
8
10
12
14
16
18
20
250
270
290
310
330
350
Base Model Varying Diameter Varying Openings Inlet and Outlet on
Either Side
Inlet and Outlet on
Either Side (Big
Opening in M2)
Inlet and Outlet on
Either Side (More
Fin in M2)
ΔT
Flu
id T
emp
erat
ure
(K
)
Different Cases Comparison
Fluid Temperature M1 Fluid Temperature M2 Fluid Temperature M3 ∆T M1 ∆T M2 ∆T M3
Variation of Base Module Temprature
Compared to Ambient TempratureFluid Temprature for different design in
Kelvin
42
CONCLUSION
Fin-based design modifications were done to improve the overall cooling of the UBS along with efficient heat
extraction from three high-voltage high-current SiC modules. To determine the cooling performance of the liquid-
based cooling system, a total of six designs with variation in fin structure and flow pattern were analyzed.
Variation in designs were done by varying following parameters in base model: (i) variation in the tube diameter,
(ii) variation in the openings between tube and fin area, (iii) variation in the location of the inlet and outlet of the cold
plate, (iv) variation in the size of the opening in middle position with inlet and outlet on either side, and finally (v)
design with more fin density in middle position with inlet and outlet on either side.
These six cold-plate designs were modified to overcome each other’s shortages. The final design (v) gives the
best performance amongst all of them. It overcomes all the shortcomings of the previous models’ design like the
shortest fluid path between inlet and outlet and cooling effect in the middle position. Moreover, it is giving the equal
cooling effect to all the modules and that was tested by the iterative study and those results were compared with the
base model.
43
FUTURE WORK
This work has provided information regarding different designs of the fin-based structure of cold-plate for
localized cooling. There are few areas that can be studied and analyzed for further study,
• Varying the number fin in all three positions
• Different cross-sections of the tube
• Combination of the number of fins and opening between tube and fin area.
44
APPENDIX A: SolidWorks
All the components have different ways to build. Here a couple of them is explained along with the procedure for
assembly of the model.
Sic Module:
TABLE VI: CAD design procedure of SiC Module.
• Draw the 2D drawing of SiC module’s outer
box using rectangle, circle and fillet tools
from the sketch.
• Circles are the place which is made for the
screw area.
• Select the drawing (except the circle part)
and apply the extrude tool from features and
enter the thickness of the module.
• Select the edit sketch option by selecting
and right-clicking on the top surface of the
module.
• In that sketch draw the circles according to
the dimensions and locations and apply the
extrude cut by mentioning the depth of cut.
• This equally distributed holes also can be
done by using the pattern feature (circular or
linear pattern as per the requirement).
45
• For the placement of the dies inside it this
module needs to be hollow.
• For that select the Shell tool from feature
and enter the required wall thickness and
apply. This will make the module hollow
from the solid part.
• With 2D drawing and using the extrude feature die can be made. Now, this die should be placed inside the
module. There is a total of 16 dies inside the module. For that open the new assembly file and insert the module.
TABLE VII: CAD design procedure for die placement inside SiC Module.
• In assembly select the section view of the
module which shows the bottom inside
surface where the dies are going to be
placed.
• Insert the die and select the bottom surface
of die and modules inside bottom surface.
By selecting the mate option die will be
placed on the module’s bottom surface.
• Apply two more mates by selecting the
other surfaces to turn by turn to fix die’s
location. Once the one die is placed use
linear pattern and make 16 dies. At last
close the section view.
Using a similar procedure other parts and the whole assembly can be done.
46
APPENDIX B: ANSYS
Figure 50: Steady-state thermal tool of ANSYS.
1. Select the Material in Engineering Data section.
2. Geometry Section:
2.1. Import the STEP file of CAD design in the Geometry section and press generate.
2.2. Select all the parts except tube and form a new part and press generate.
3. Model Section:
3.1. From the geometry suppress the tube part.
3.2. Mesh the body as per the mesh convergence study.
3.3. Select all the dies (as a whole solid body) of the first module and give the loss value in terms of
internal heat generation (W/volume of all dies). Follow the same procedure for all three modules and all three
integrated magnetics.
3.4. Select the area for convection and apply the convection values.
3.5. Select the flow area inside the plate as a FLUID SOLID INTERACTION and make yes for Export
Result.
3.6. In the solution part, add the type of result you are looking for and press solve. Ex: add temperature
which will show you the temperature profile of the body.
4. Save an entire project (let’s say with name UIC).
➢ Drag and drop the external data tool next to steady-state thermal.
➢ Drag and drop the fluid flow (fluent) tool next to external data and system coupling next to fluent.
47
➢ Connect the setup of external data and fluent with the system coupling.
➢ Connect the geometry section of Steady-State Thermal and Fluid Flow (Fluent).
Figure 51: First half of the ANSYS model, in which data transfer is from the body to fluid.
Figure 52: External data tool of ANSYS.
• Import the result file that saved from the steady-state thermal. Location of the file will be something like this:
Location of your folder where you saved\UIC_files\dp0\SYS\MECH\fsin_1.axdt
Figure 53: Fluent tool of ANSYS.
1. Mesh Section:
1.1. In geometry suppress the part except for tube.
1.2. Select the inlet surface and name it as INLET follow the same procedure for OUTLET. Select and
name ‘SURFACE’ to the surface to which we selected as FLUID SOLID INTERACTION in Model Section
of Steady-State Thermal.
48
1.3. Apply the mesh as per the mesh convergence study and update the section.
2. Setup Section:
2.1. Make the energy section on in Models part.
2.2. Select the types of coolant in Fluid section of Material.
2.3. Select that coolant in Cell Zone Conditions for the tube.
2.4. In Boundary Conditions apply mass flow rate, pressure, direction specification method and
temperature for the inlet. Select outflow for an outlet and for surface, select temperature transfer as via system
coupling.
2.5. Select a suitable method for solution. Initialize the whole body and give the number of iterations in
the run calculation.
• In System Coupling select the ‘Surface’ from Fluent part while ‘File 1’ from External Data and select CREAT
DATA TRANSFER by right click and update the System Coupling.
• Once the simulation is done update the Result Section of fluent to check to fluid condition. Save that result
from FILE>EXPORT>EXPORT EXTERNAL DATA FILE. In that select the location whose result we want
to save. In our case, it is the surface of the tube that we named as ‘surface’ in the mesh section and select
wall adjustable temperature in an additional variable.
• So up to this point, the temperature is transferred from body to fluid part now to transfer it another way round
make a duplicate of Steady-State Thermal by right-clicking on Setup and add External Data on left of the
Copy of Steady-State Thermal while System Coupling on the right of it.
• Connect the setup of external data and fluent with the system coupling.
49
Figure 54: ANSYS model.
• Add the file we saved from the fluent section from Location where your file is
saved\UIC_files\user_files\file_name.
• Update External Data and Copy of Steady-State Thermal.
• In System Coupling select the ‘Fluid Solid Interface’ from Copy of Steady-State Thermal part while ‘File
1’ from External Data and select CREAT DATA TRANSFER by right click and update the System
Coupling.
• Once the simulation is done, we can see the effect of fluid on the body in the result section of Copy of
Steady-State Thermal.
• To make it iterative to check the steady result add the Result toll in between of Copy of Steady-State
Thermal and System Coupling. Connect the Solution of Copy of Steady-State Thermal with the result and
save the result the same way we save in Fluent part. Make this saved file as input for first External Data of
next cycle.
50
REFERENCES
1 http://www.chargingchargers.com/ev-battery-chargers.html
2 https://www.energy.gov/eere/electricvehicles/vehicle-charging
3 https://www.carolinacountry.com/your-energy/energytech/know-charging-options-to-keep-your-ev-
rolling
4 Kumar, Nikhil, Sudip K. Mazumder, and Ankit Gupta. "SiC DC Fast Charger Control for Electric
Vehicles." In 2018 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 599-605. IEEE,
2018.
5 https://docplayer.net/47938483-Mission-profile-on-power-electronics-reliability-importance-analysis-
testing.html
6 S.K.Bhalerao and Dr. S. I. Kolhe,” A review on Transient Heat Flow Analysis of Cold Plate Used in
Electronic Power Cooling Systems”, International Journal of Recent Development in Engineering and
Technology, Volume 5, Issue12, December 2016.
7 Kekre, Pratik. "Multi-variable Design Optimization Of A Contemporary Cold Plate For A Fixed
Pumping Power For Minimizing The Thermal Resistance." (2014).
8 T'Jollyn, Ilya, Bernd Ameel, Steven Devos, Jan Bienstman, Stephan Schlimpert, and Michel De
Paepe. "Experimental study of design parameter influence on the thermal and hydraulic performance
of cold plates." In 2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical
Phenomena in Electronic Systems (ITherm), pp. 551-557. IEEE, 2017.
9 Pesaran, Ahmad A. "Battery thermal management in EV and HEVs: issues and solutions." Battery
Man 43, no. 5 (2001): 34-49.
10 Kandlikar, Satish G., and Clifford N. Hayner. "Liquid-cooled cold plates for industrial high-power
electronic devices—thermal design and manufacturing considerations." Heat transfer engineering 30,
no. 12 (2009): 918-930.
11 Webb, R. L. "High-performance, low-cost liquid micro-channel cooler." THERMES (2007): 155-161.
51
12 Kang, Sukhvinder S. "Advanced cooling for power electronics." In 2012 7th international conference
on integrated power electronics systems (cips), pp. 1-8. IEEE, 2012.
13 https://www.microcooling.com/
52
VITA
Name: Anik Niraj Desai
Education: M.S., Mechanical Engineering,
University of Illinois at Chicago, USA (2017-2019)
B.E., Mechanical Engineering,
Gujarat Technological University, India (2013-2017)
Experience: Research Assistant, ECE, Laboratory for Energy and Switching Electronics System
University of Illinois at Chicago, USA, (Summer-2018 to Summer-2019)
Research Assistant, MIE, Computational Biomechanics Research Laboratory
University of Illinois at Chicago, USA, (Summer-2018)
Teaching Assistant, MIE
University of Illinois at Chicago, USA, (Spring-2018)