Objectives of Research

Design and Simulation of a DC Electric Vehicle Charging Station Connected to a MVDC InfrastructureGraduate Student Researchers: Adam R. Sparacino and Brandon M. Grainger

Academic Advisor: Dr. Gregory F. Reed

Investigate operation, interaction, and systemintegration of power electronic conversion devices,battery energy storage systems, and DC powersystems.

Evaluate operation of common DC bus electricvehicle charging station (EVCS) employing level 2DC fast chargers powered via MVDC grid.

Benchmark applicability of bidirectional DC-DCconverter as an interface between medium and lowvoltage networks within next generation DC powersystems.

System Operation, Validation, and Transient Behavior

Renewable Generation Modeling Bidirectional DC-DC Converter

Operating Waveforms

(A) Interval 1: 0 < t < DTS

(B) Interval 2: DTS < t < TS / Interval 4: (TS + DTS) < t < 2TS;

(C) Interval 3: TS < t < (TS + DTS)

Current Paths

1.9938 1.994 1.9942 1.9944 1.9946 1.9948 1.995 1.9952 1.9954 1.9956-5

-4

-3

-2

-1

0

1

2

3

4

5

X: 1.994Y: 1.4

Vol

tage

(kV

)

Time (Seconds)

X: 1.994Y: 4.249

EpEs

1.9938 1.994 1.9942 1.9944 1.9946 1.9948 1.995 1.9952 1.9954 1.99560

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

X: 1.994Y: 0.06603

Cur

rent

(kA

)

Time (Seconds)

X: 1.995Y: 0.06687

1.9938 1.994 1.9942 1.9944 1.9946 1.9948 1.995 1.9952 1.9954 1.9956-0.25

-0.2

-0.15

-0.1

-0.05

0 X: 1.994Y: -0.01389

Cur

rent

(kA

)

Time (Seconds)

X: 1.994Y: -0.1947

X: 1.995Y: -0.1956

Transformer Voltage

IHV Input Current

IL Inductor Current

Installed Electric Vehicle Charging Station(C. S. CCJ Digital. (2011). Eaton Research Facility Adds EV Charging Stations)

Medium Voltage DC Concept and Modeled Systems

l

General MVDC Architecture

PSCAD MVDC Implementation PSCAD Electric Vehicle Charging Station Implementation

The emerging applications of DCresources and supply establish thepotential for a paradigm shift in thefuture development of transmissionand distribution systems toward alarger overall DC infrastructure.

The medium-voltage DC (MVDC)concept is ultimately a collectionplatform designed to help integraterenewables, serve emerging DC-based and constant-power loads,interconnect energy storage, andaddress future needs in the generalarea of electric power conversion.

Certain applications require loweroperating voltages and would not beable to directly connect to the mediumvoltage DC architecture. ElectricVehicle charging station infrastructure issuch an example.

To accommodate lower voltageapplications, bidirectional DC/DCconverter research is critical. Thesecomponents will serve as the interfacebetween the medium and low voltagebus bars as depicted in the low voltageDC framework found below.

MVDC Wind Turbine System Experimentally Validated Aerodynamic Model

Permanent Magnet Synchronous Generator

Back-to-Back Neutral Point Clamped Converter Interface

dtdJFTT r

rme

qdqsdsqmem iiLLiPT 22

3qsr

dsdsd iL

dtdiLiRV

mrdsrq

sqsq LiLdtdi

LiRV

Generator Characteristics Controller Responses

LVDC Photovoltaic System

Battery & Battery Charger Modeling

)SOC(EMF Vmin KV

)SOC( Rminint KRR

t

bate dIQ0

)(

max

SOCCQe

Battery Short Circuit Fault Current

Regulated LVDC Bus Voltage

Power Flow During Battery Short Circuit

Component Supplied and Absorbed Power System Operating States

Level 3 DC Fast Charger Simulated using synchronous buck converter

Charges at approximately 50 kW for 15 minutes

EV Battery Simulated using dynamic linear battery model

Dynamics of battery governed by equations below

22 Ah battery pulse charged for approximately 0.55seconds

Synchronous Buck Converter Linear Battery

Linear Battery Equations

Pulsed Charge (Battery 2)Example Pulsed Charge

(Zheng et. al. - Dynamic Model for Characteristics of Li-ion Battery on Electric Vehicle)

Regulated MVDC Bus Voltage

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.2

0.4

0.6

0.8

1

1.2

1.4

Vol

tage

(p.u

.)

Time (s)

Non-InterconnectedInterconnected

Pre-Charge Resitor Turn-OFF

A B

0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.2

0.4

0.6

0.8

1

1.2

Vol

tage

(p.u

.)

Time (s)

Non-InterconnectedInterconnected

D

C

F

EG

H

I

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

-20

0

20

40

60

80

100

Time (s)

Pow

er (k

W)

Bidirectional ConverterPV ArrayBat 1Bat 2

A

B

C

D

E F G

H

I

Stated Process(A) – 0.00 s Wind turbines begin ‘warm-up’(B) – 0.50 s MVDC grid connected to EVCS(C) – 0.61 s PV array ON(D) – 1.00 s PV array OFF(E) – 1.15 s EV bat 1 begins charging(F) – 1.20 s PV array ON(G) – 1.35 s EV bat 2 begins charging(H) – 1.75 s PV array OFF(I) – 1.90 s EV battery 2 stops charging

0.4 0.5 0.6 0.7 0.8 0.9 1-10

0

10

20

30

40

50

60

70

80

90

Time (s)

Pow

er (k

W)

Bidirectional ConverterPV ArrayBat 1Bat 2

0.4 0.5 0.6 0.7 0.8 0.9 1

0

2

4

6

8

10

12

Time (s)

Cur

rent

(kA

)

Synch Buck Iout

Battery CurrentFault Current