Energy and Power Engineering, 2013, 5, 1372-1376
doi:10.4236/epe.2013.54B260 Published Online July 2013 (http://www.scirp.org/journal/epe)
Research on the Model of Electric Vehicle Charging Device
Based on PSCAD
Run-rong Fan, Tian-yuan Tan, Yun-peng Gao, Hui Chang
School of Electrical Engineering, Wuhan University, Wuhan, China
Received May, 2013
ABSTRACT
As the energy and environment issues are becoming increasingly prominent, electric vehicles have become the main
new energy vehicles of future development because of their advantage of environmental protection, clean and energy
conservation. Electric vehicle charging station is a very important part of electric vehicle facilities, the development and
popularization of electric vehicles can't do with the construction of the charging station. The chargers in charging sta-
tions are nonlinear equip ment, and th ey will produce harmonic pollution, so it's of practical significance to do a research
on the chargers and their harmonic problems. By using power system simulation software PSCAD as the simulation and
analysis tool, this thesis focuses on electric vehicle charging device modeling and harmonic problem research.
Keywords: Electric Vehicles; Modeling; Harmonic Analysis; PSCAD Simulation
1. Introduction
The car makes a great contribution to the advance of
human civilization [1]. It makes human life more con-
venient and comfortable, but at the same it also brings to
the society inevitable consequences such as the waste of
resources and serious environmental pollution [2, 3]. In
order to reduce its dependence on traditional energy
sources and to protect the natural environment for human
survival, doing researches on new energy has become a
worldwide subject [4, 5]. As a representative of the new
energy vehicles, electric vehicles have obvious advantage
of environmentally-friendly, energy-saving and so on
compared to traditional gasoline cars [6].
The electric vehicle charging system is the basic sup-
porting systems of electric vehicles. [7]The charging
device’s research is of great significance to the promo-
tion and application of the electric car, and to its turning
to industrial production.
This paper is based on the program of electric vehicle
charging device. Six pulse wave uncontrolled rectifica-
tion charger circuit was built in PSCAD so that it can
charge a storage battery. And it also calculated the
Nth-degree harmonics current and the distortion rate of
total current harmonic. It also analyzed the harmonics of
the car charging model. And compared it with the theo-
retical value, which proved correctness of the analysis. In
the end, it gives the prospects of the researches that need
to be done in this field.
2. The Design of Electric Vehicles’ Charging
Device
The charging device system of electric vehicles is actu-
ally a DC power supply. To de sign such a power supply,
the charging models, the methods of charging and many
other factors should to be considered.
2.1. The Charging Model and Charging Method
of the Electric Vehicle
As for the electric vehicle charging programs, there are
three choices: models of conventional charging, fast
charging and mechanical charging [8]. The three charg-
ing modes have their own characteristics and scope of
application. Ac-cording to the characteristics and control
of the operational characteristics of the convention al pure
electric vehicles and the use of conventional battery
management strategy, usually conventional charging and
supplementary charging are taken. The supplementary
charging is still in th e form of the conventional charging,
but the charging time is the hospitality gap. It can be re-
placed by the battery charging if necessary.
There are mainly three conventional charging methods
of the electric cars: constant current charging method,
constant voltage charging method and stage charging
method [9]. Of the three methods,, stage charging meth-
od can avoid large charging current at the beginning
phase of the constant voltage charging, it can also avoid
the phenomenon of overcharge at the later phase of the
constant current charging. Stage charging method is used

R.-R. FAN ET AL. 1373
on the power battery of the charger’s charging methods
and charging control strategy. So this paper takes stage
charging method to charge electric vehicles.
2.2. The Overall Design of the Electric Vehicle’s
Charging Device
The charging device system of electric vehicles is actu-
ally a DC power supply. And the design of the charging
system is in fact the design of a power supply. But the
power supply must be controlled by a certain algorithm
so that the output voltage and current are in line with the
curve of battery charging. The charging power supplies
that commonly used in industrial applications are the
following three types: linear power, SCR power supply
and switching power supply [10]. According to the
working principle and method of the switching power
supply, the block diagram of the charger designed in this
paper is shown in Figure 1.
3. The Modeling of the Charger and its Sim-
ulation Analysis
According to the requirements of the electric vehicle
battery charging and the design requirements of the
charging device, in this paper we build a charging device
circuit in PSCAD, set the parameters of each device in
the circuit and then run the circu it, we obtained a portion
of the output voltage and current waveforms of the power
supply.
3.1. The Design of the Charging Device Circuit
The main circuit diagram of electric vehicle charging
device build in PSCAD is shown in Figure 2. This paper
mainly analyzes the charger’s output voltage and current.
For more convenient analysis, a simple resistive load is
given.
In order to simulate the charging system as real as
possible, we set the sys-tem input 10kv , and transformed
to 380V after △/Y transformer to supply power for the
charging system. The charging system rectifier links use
three-phase controlled rectifier diode, the three-phase
380V AC voltage becomes 514V DC voltage through a
three-phase rectifier bridge rectifier and capacitor fil-
ter ,and turn to high-frequency pulse voltage after H-
bridge inverter, then we get the required adjustable DC
voltage and adjustable DC current after high-frequency
rectifier and filter.
Figure 1. Block diagram of the charger.
A
B
C
RLC
RLC
RLC
TTT
TTT
2000.0 [uF]
A
B
C
A
B
C
380 [V]
#2#1
10.0 [ k V]
1.0 [MVA]
V
A
U1
TT
G1
TT
G2
TT
G2
TT
G1
#2
#3
#1
T T
0. 001 [H]
Uo
Io
2000.0 [uF]
1.0 [ohm ]
1 [mH]
Figure 2 The main circuit of the electric vehicle charging
device.
G1
G2
G1
G2
U1 U1
Ua Ua
Ia Ia
Uo Uo
Io Io
Figure 3. Drive control circuit and waveform analysis cir-
cuit.
The drive control circuit and the waveform analysis
circuit shown in Figure 3.
3.2. Simulation Analysis of the Charging Device
The waveforms of the output voltage and current can be
obtained through the simulation of the entire charging
device circuit, waveform diagram shown in Figure 4 (a)
and the unit is V. waveform diagram shown in Figure 4
(b) and the unit is A.
As can be seen from the output voltage and current
waveform, the charger model designed in this paper can
get a better DC power supply.
4. The Harmonic Analysis of Electric Vehicle
Charging Device Connected to the Grid
High power charger in charging stations is a kind of
highly non-linear electrical equipment. Sinusoidal volt-
age puts pressure on non-linear loads, the fundamental
current will be distorted and harmonic will be generated.
Especially in large charging stations, a large number of
charger works at the same time, harmonic currents gen-
erated will have great impact on power grid and other
electrical equipments. Therefore, in the construction of
charging stations, we need to consider the harmonic
problems.

R.-R. FAN ET AL.
1374
4.1. The Design of the Equivalent Model of the
Charger’s Harmonic Analysis
The working principle of the charging machine is the
input three-phase AC current rectified by rectifying cir-
cuit, after the filter circuit, providing the DC input for
high frequency DC-DC power conversion circuit, the
output of the power conversion circuit after the output
filter circuit to charge rechargeable battery of vehicles,
charger block diagram shown in Figure 5.
At present, as for the charging method and charging
control strategy of the charging machine’s battery, we
usually adopt a typical two-stage method. The first half is
the constant current but with limited pressure, the latter
half is the constant pressure but with limited current.
Usually the conventional charging time of charging
machine is 4-6 hours. In this process, the output voltage
and current is changeable, but in the charging time of a
micro-element, we think the output current and the out-
put voltage of the charging machine is constant, i.e.in a
(a)
(b)
Figure 4 (a) Uo waveform graph; (b) I0 waveform graph.
0
I
0
U
Figure 5. Block diagram of the charg e r.
micro element we can use a non-resistor R to approxi-
mate the input impedance of the high frequency power
conversion circuits, therefore we can use a nonlinear re-
sistance R in the entire process of charging to the equiv-
alent in place of the high-frequency power transform
circuit, the value of R calculated as:
22
11 11
11 oo
UU UU
R2
o
I
PPU
 
 I (1)
In the formula,
1—the input voltage of the high frequency power
conversion circuit;
U
1
I
—the input current of the high-frequency power
conversion circuit;
o—the output voltage of the high-frequency power
conversion circuit;
U
o
I
—the output current of the high-frequency power
conversion circuit;
o—the output power of the high-frequency power
conversion circuit;
P

—The efficiency of power conversion modules.
The power conversion efficiency of the module is
generally more than 95%. In order to analysis the har-
monic, will be set as 95% directly. We use nonlinear
resistor R Instead of the charger power conversion unit
we can get the approximate equivalent model. According
to recorded data of the battery’s charging process, using
the curve fitting method, we can get the output power of
the charging machine:
0.048
omax
o0.021 (t-150)
omax
0.79t,0t 150
te,150 t270
P
PP





（） (2)
For example, the power of charger is 9kw, parameters
of the charger machine as follows, omax = 75V, omax
U
I
= 120A, omaxomax omax
PUI

 = 9kW, the charging time
t = 270 min.
For the 6-pulse uncontrolled rectifier bridge, output on
the DC-side
B
U = 2.34, 2 U = 514.8V. Making use of
the relationship between R and the output power curve of
the charging machine, we can obtain:
2
o
B
U
RP
 
 (3)
In formula (3),

is the charging machines’ effi-
ciency,
B
U is DC voltage of the rectifier bridge, o
substituted into the abov e equation, we can get a formula
about the equivalent impedance of the high frequency
power converter.
tP（）
The calculated R is a continuously changing non-linear
curve. the R-value change small before 150 minutes,
Structures approximate R model in PSCAD shown in
Figure 6, Among A = 1.1988, B = 0.021.
The value of R changing with time is shown in Figure
7.

R.-R. FAN ET AL. 1375
4.2. Harmonic Simulation Analysis
First, we should make three-phase uncontrolled rectifier
bridge; rectifier DC side filters inductor and capacitor in
PSCAD / EMTDC. Meanwhile, in order to analyze the
harmonic, we should also establish a non-controlled rec-
tifier bridge consisting of charging machine simulation
topology; the circuit is shown in Figure 8.
The control loop circuit and waveform display loop
circuit is shown in Figure 9.
Simulation analysis of the circuit to obtain voltage of
the high-voltage input terminal and waveform of the
current. The waveform shown in Figure 10(a) and the
unit is Kv. The wavefo rm shown in Figure 10(b) and the
unit is A.
TIME
R
150
AeBx
Max
D
E
Figure 6. Model diagram of R.
Figure 7. R change with time when charging process.
A
B
C
RLC
RLC
RLC
TTT
TTT
V
A
2000.0 [uF]
1 [ mH]
R
+
A
B
C
A
B
C
380 [V]
#2#1
10.0 [kV]
1. 0 [MVA]
Figure 8. Main circuit of charging simulation topology dia-
gram.
R
TIME AeBx Max
D
E
150
Ua Ua
Ia Ia
Figure 9. Control loop circuit and waveform display loop
circuit.
(a)
(b)
Figure 10. (a) Ua waveform graphs; (b) Ia waveform graphs.
As can be seen from Figure 10, the input terminal
voltage and current generated distortion, In order to get a
further analysis of the nature of the harmonic, we should
analyze its Fourier. The harmonic analysis of the circuit
is shown in Figure 11.
With the analysis of the circuit simulation, we can get
the current total distortion waveform as is shown in Fig-
ure 12; the amplitude of the current total distortion is
6.7%.
The percentage of the each output harmonic wave is
shown in Figure 13.
With the simulation waveforms and the ratio chart, we
can get the higher quality harmonic: (k = 1, 2, 3 ...) har-
monic, and as for the higher harmonic content, the higher
the harmonic frequency, the smaller the amplitude. We
can also conduct harmonic suppression with the installa-
tion of filtering devices and reactive power compensatio n
device.

R.-R. FAN ET AL.
1376
Mag
Ph
dc
(31)
(31)
F F T
F = 50.0 [Hz]
Ia
Harm onic
Distortion
To tal
Indivi dua l
31
31
TH Dn
TH Di
Figure 11. Harmonic analysis circuit.
Figure 12. Current total harmonic distortion waveform
graphs.
Figure 13. Each output harmonic wave propo rtion.
5. Conclusions
The use of electric vehicles’ charging problems must be
first considered, while the development and populariza-
tion of electric vehicles cannot be separated from the
construction of charging stations. In the charging stations,
charging device will produce harmonics and inject har-
monics into the grid. Therefore, before the construction
and functioning of the charging stations, we must study
and solve the electric vehicle’s charging and harmonic
problems.
This paper used appropriate procedures and estab-
lished a simulation model to simulate the charging device
and then analyzed the harmonic impact which is proved
ffective. This paper built a battery model, and re-
searched its charging method. According to the different
waveform of the power supply to charge the battery, we
can use the battery charging model to charge the battery
using the DC current source first and then using the DC
voltage source.
This article analyzed the harmonic generation and im-
pact in theory. It substituted the equivalent input imped-
ance of the charging machine of high frequency DC-DC
power conversion circuit with a nonlinear resistor and
built the model of ch arg ing device, and th en proceed ed to
the harmonic simulation analysis. Compared the har-
monic simulation results with the theoretical analysis of
the value, we can see the 5th,7th,11th,13th,17th,19th and
other harmonic (all odd harmonics) content is higher, and
for higher levels of harmonics, the higher the number, the
smaller the harmonic amplitude. So the result is consis-
tent with the theoretical analysis.
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