why the electric car? - bradley

Renee Kohl Peter Burrmann

Matthew Daly

Advisors: Dr. Woonki Na Dr. Brian Huggins

1

Why the electric car?

Reduce our foreign oil dependence Reduce carbon emissions

2

Outline Functional Description Progression of Project

Implementation/Construction Testing

Results

3

Project Summary Convert 120 volt AC grid power to the required 51.8[V]

DC value to efficiently charge an electric vehicle battery

Discharge battery via Bi-directional converter into a variable load

120VAC

Diode RectifierAC/DC

Boost ConverterDC/DC

PFC

Bidirectional Converter

DC/DC

51.8VBatteryDSP

PWM

PWM

Load

Discharging or charging? Charging

Discharging

4

Project Goals Create a PHEV charging system capable of outputting

up to 1k[W] of power for the operation of a variable load.

Implement a control system using a DSP for the purpose of driving MOSFET gates

Efficiently Charge a Li-Ion battery using our power electronics system

5

Diode Rectifier

120VAC

Diode Rectifier

Boost Converter

Bidirectional Converter

51.8VBatteryDSP

PWM

PWM

Load

Discharging or charging? Charging

Discharging

6

Functional Description Diode Rectifier

Rectifies 120[Vrms] AC grid power

Precedes Power Factor Correction

7

Functional Description Diode Rectifier

8

Power Factor Correction

120VAC

Diode Rectifier

Boost Converter

PFC

Bidirectional Converter

51.8VBatteryDSP

PWM

PWM

Load

Discharging or charging? Charging

Discharging

9

Power Factor Correction Power Factor

Dimensionless number from 0-1 Ratio of real to apparent power 1 is in unity (ideal)

Passive power factor correction- Capacitor, Inductor Active power factor correction- Boost Converter

10

Implementation Diode Rectifier / Power Factor Correction

11

Bi-Directional Converter

120VAC

Diode Rectifier

Boost Converter

Bidirectional Converter

51.8VBatteryDSP

PWM

PWM

Load

Discharging or charging? Charging

Discharging

12

Functional Description Bi-directional Converter To be used in place of the individual Buck and Boost

converters’ architecture Requires more detailed control system

13

Implementation Bi-Directional Converter

14

Functional Description Buck Converter

Drops input voltage based on MOSFET Duty cycle

Half of the Bi-directional Converter Stage 1

Stage 2 15

Functional Description Boost Converter

Boosts input voltage based on MOSFET duty cycle

Part of Power Factor Correction

Half of Bi-directional Converter

Stage 1

Stage 2 16

Implementation PFC and Bi-Directional Converter

17

Functional Description Interfacing & Protection Circuitry

To be used to sense voltage levels from various locations of the PHEV system, while providing isolation between the DSP and high voltage levels

18

Functional Description Gate Driver Receives PWM input from DSP

to control switching of MOSFETs Provides enough power to drive

the converter’s MOSFETs

19

Functional Description Gate Driver

Bootstrap Capacitor Qg = Gate Charge f = Frequency of Operation Iqbs(max) = Maximum Vbs Quiescent Current Qls = Level Shift Charge (5nC) Icbs(leak) = Leakage Current Vcc = Logic Section Voltage Source Vf = Forward Voltage Drop Across Bootstrap Diode VLS = Voltage Drop Across Low- Side FET Vmin = Minimum Voltage Between Vb and Vs

g

gg

s

gg

IVR

TQI

=

=

20

120VAC

Diode Rectifier

Boost Converter

PFC

Bidirectional Converter

51.8VBatteryDSP

PWM

PWM

Load

Discharging or charging? Charging

Discharging

Battery

21

Functional Description Battery

Working Voltage=51.8[V] 14 Cell Polymer Li-Ion Capacity = 10Ah (518Wh) 40[A] Continuous

Discharge Rate

22

Functional Description Battery

23

Implementation Charging Method Stage 1: Charge Rate: 0.8C

Constant Current Method Stage 2: 58.8[V]

Constant Voltage Method Terminate at 3% Rated Current

No Trickle Charge Reduces battery life

24

Implementation Battery Resistance

Internal Resistance varies with State of Charge

Actively Measure State of Charge

Coulomb Counting Requires Current Shunt

25

RC Battery Model Allows for Matlab simulation Resistance values are functions of SOC, T, and

charge/discharge

Implementation Measuring Battery Resistance

26

Implementation Measuring Battery Resistance

IVV

IVVR 23terminaloc −

=−

= Internal Resistance seen

from pulse discharge Rint = 108m[Ω]

Vr 56.530

R 10.910

V1 57.850

V2 57.160

V3 57.720

I 5.181

Rint 0.108

27

Implementation Measuring Battery Resistance

28

Bi-Directional Converter

120VAC

Diode Rectifier

Boost Converter

Bidirectional Converter

51.8VBatteryDSP

PWM

PWM

Load

Discharging or charging? Charging

Discharging

29

Schematics Buck Converter

30

Calculating gains

Fc=500Hz 15dB

-150°

31

Psim output voltage

32

Buck Converter PI Control

6.12

voltage divider

limit duty cycleinverter

C281x

PWM

W1

PWM

0.1

Kp

.00073

Gain4

F2812 eZdsp1

K Ts

z-1Discrete-Time

Integrator

100

Constant2

10

Constant

C281x

ADC

A

ADC1

33

PI Control

34

Schematics Boost Converter

35

Boost Converter PI Control

6.12

voltage divider

limit duty cycleinverter

C281x

PWM

W1

PWM

0.1

Kp

.00073

Gain4

F2812 eZdsp1

K Ts

z-1Discrete-Time

Integrator

100

Constant2

10

Constant

C281x

ADC

A

ADC1

36

PI Control

37

Power Factor Correction

120VAC

Diode Rectifier

Boost Converter

PFC

Bidirectional Converter

51.8VBatteryDSP

PWM

PWM

Load

Discharging or charging? Charging

Discharging

38

Power Factor Correction How it works:

39

Schematics Power Factor Correction

40

PFC Testing

Channel 1: output of current sensing circuitry and op amp input to the dsp

Channel 2: output of current probe

Open loop control, 50% duty cycle

80mV out of the op amp can be converted by multiplying by the 1.25 voltage divider, then multiply by 50/4 for the current sensor, and divide by 5 to factor in the 5 loops around the current sensor gives you 250mV which the current probe is showing.

41

PFC Testing

Because the current being measured by the DSP is a rectified sign wave with an amplitude of approximately 80mV, I simulated this in Simulink as the reference current to match.

42

PFC Testing

1: output of current sensing circuit opamp into DSP

2: current probe measuring current through inductor

1: constantly adjusting pwm

43

PFC PI Control

2

voltage divider3

6.7

voltage divider1

-K-

voltage divider

limit duty cycle

inverter

In1 Out1

iir filter2

In1 Out1

iir filter1

Product

C281x

PWM

W1

PWM

-K-

Kp2

-K-

Kp1

.00073

Gain4

.00073

Gain2

.00073

Gain1

F2812 eZdsp1

K Ts

z-1

Discrete-Time

Integrator2

K Ts

z-1

Discrete-Time

Integrator1

double

Data Type Conversion3

uint16

Data Type Conversion2

double

Data Type Conversion1

double

Data Type Conversion

100

Constant2

15

Constant1

C281x

ADC

A4

A3

A5

ADC1

44

PFC PI Control Circuit in discontinuous

mode

45

Completed Work Designed full scale system Controls functioning

Full scale boost converter Full scale buck converter Small scale PFC

46

Future Use system to charge battery Acquire detailed parameters for battery Discharge battery through inverter to run a variable

load Implement regenerative braking Utilize ultra-capacitors for regenerative braking energy

storage

47

Questions?

48

Converter Equations Capacitor and Inductor Calculation Equations for PFC and Bi-Directional Converter

Voltage Divider Boost Converter

Buck Converter

49

Controller Equations

50

MOSFET vs. IGBT

51