ISSN: 0975-766X CODEN: IJPTFI Available Online through ... · The conventional converter with a...

Dr. R.Samuel Rajesh Babu* et al. /International Journal of Pharmacy & Technology

IJPT| Sep-2016 | Vol. 8 | Issue No.3 | 16676-16687 6676

ISSN: 0975-766X

CODEN: IJPTFI

Available Online through Research Article

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OPTIMAL OPERATION OF ELECTRIC VECHICLE USING HPMC UNIT WITH PID

CONTROLLER Dr. R.Samuel Rajesh Babu*, Anand.K

Department of EIE, Sathyabama University, Chennai-600 119, India.

Email: [email protected]

Received on 10-08-2016 Accepted on 30-08-2016

Abstract

This proposed work introduces the optimal operation of Electric vechicle using high performance motor control

(HPMC) unit. The HPMC unit plays a major role in Electric vechicle. The DC-DC converter in HPMC unit operates in

both buck and boost mode. It consists of adding a selective switch and two inductors to the existing converter. The

operating principle and the steady state analysis of the proposed converter are discussed. It has been found that the

transient and steady state performance is improved by using PID controller. The Hardware model is constructed in order

to compare with the Matlab model. Moreover, the model has been validated on the actual operation of the converter,

showing that the simulated results in Matlab Simulink are consistent with the experimental ones.

Keywords: DC-DC Converter, High performance motor control (HPMC) unit, Optimal operation, PID Controller, High

output voltage.

I. Introduction

The automobile industry is one of the areas where the high performance motor control (HPMC) unit is extensively used.

With the introduction of hybrid technology, there is an increasing need to high efficiency of electric equipments to

compete with the mechanical engines in the automobile industry. All the automobile manufacturers are investing on the

research and development of efficient and electric equipments including converters, storage batteries etc to make it more

reliable and cost effective. Recently, Hundai Motors have introduced a high-performance motor control unit (HPMC)

unit for an electric vehicle. It employs a DC-DC converter, which has buck and boost operating modes. During the boost

mode, it increases a dc-link voltage of an inverter resulted in reduction of the number of the battery stacks. The buck

mode charges a battery stack when the motor is in regeneration. For both the modes i.e. boost and buck, the DC-DC

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IJPT| Sep-2016 | Vol. 8 | Issue No.3 | 16676-16687 Page 16677

converter works with a single inductor. Under the same load capacity, an optimal inductance value of inductor is equal

for two-way operation. The conventional converter with a single inductor is simple to configure and it is enough to be

modularised. However, when the load capacity at buck and boost mode is different from each other, it is difficult to

design the inductor to satisfy all operating modes with an optimal inductance value. In this case, one mode operates with

an optimal inductor, but another is relatively larger or smaller than the optimal one. However, when the load capacity

for buck or boost mode is different from each other, it is practically not possible to design the inductor to satisfy all the

operating modes. One mode operates with an optimal inductor, but another is relatively larger or smaller than the

optimal one. This implication makes the DC-DC converter used in automobile or in any other applications.

To solve this problem, this paper proposes a DC-DC converter with a selective switch and two inductors for buck and

boost operation. It consists of adding a selective switch and two inductors to a conventional DC-DC converter.

II. Operating Principle of DC-DC Converter in HPMC Unit.

Fig 1 Circuit diagram of DC-DC converter in HPMC Unit.

The operation of the DC-DC converter in HPMC Unit is divided into two modes i.e., buck and boost mode is shown

fig 1. By a selective switch S1, inductor L1 operates in a buck mode, and inductor L2 is designed to operate in a boost

mode. During a buck mode, when switch Q1 works, Q2 is in off-state. During a boost mode, switch Q1 maintains off and

Q2 works. By employing a selective switch, the proposed converter is able to select an optimal inductor for buck or

boost mode. It minimizes the losses by using an inadequate inductor, which in turn improves the system efficiency.

Boost Mode

Fig 2. Boost mode when Q1 is OFF, (a) Q2=ON, (b) Q2=OFF



During the boost mode as shown in fig 2(a), a selective switch connects with an inductor L2 and Q1 is in off-state. When

Q2 turns on as shown in Fig. 2(b), an inductor L2 starts to save energy from a source voltage VLow. When Q2 turns off, an

inductor L2 discharges the energy to output terminal via a body diode of Q1. A relationship between the input voltage

VLow and output voltage VHigh is defined by using a duty-ratio of Q2 [1].

………….(1)

Buck Mode

Fig 3: Buck mode when Q2 is OFF, (a) Q1=ON, (b) Q1=OFF

During buck mode as shown in fig 3, the selective switch connects with an inductor L1 and Q2 turns off. When Q1 turns

on, an inductor L1 starts to save energy from a source voltage VHigh and a capacitor C discharges as shown in Fig.3(a).

When Q1 turns off, the inductor energy continuously transfers to a battery through the body diode of Q2 as shown in

Fig.3(b). A relationship between VLow and VHigh is determined by using a duty-ratio of Q1 as given in[2].

………..(2)

III. Simulation Results

The DC-DC converter in HPMC unit performs both voltage buck and boost operation using selective switch and two

inductors. Two optimized inductors are designed for buck and boost operation at CCM (Current Continuous Conduction

Mode). One inductor is designed as 215mH to optimize in buck mode when load capacity is 125W. And the other has

2mH to optimize in boost mode when load capacity is 500W. The proposed converter is simulated in both open and



closed loop using MATLAB simulink and the results are presented. Scope is connected to display the output voltage.

The following values are found to be near optimum for the design specifications in table 1.

Open Loop System

In open loop system the output can be varied by varying the input and the corresponding output voltage is measured.

The open loop system is simulated in both boost and buck mode.

Boost Mode

Fig 4 Simulated diagram of open loop system in Boost Mode.

Fig 5: Input Current.

Table 1: Simulation Parameters

Parameter Value

Voltage (Boost Mode)

Simulation:

I/P 75V,

O/P 185 V

Voltage (Buck Mode)

Simulation:

I/P 140V,

O/P 80V

Switching Frequency (Fs ) 20 kHz

Output Capacitor (C') 470 μF

Inductor (L1)

(Buck mode) 215 μH

Inductor (L2)

(Boost mode) 2 μH

Load Resistance

(Buck and Boost mode) 40 Ω

Duty ratio 50%



Fig 6: Input Voltage.

Fig 7: Voltage (Drain & Source).

Fig 8: Output Voltage.

During the boost mode, the inductor is designed larger than the optimal inductance value. The inductor currents are

continuous, ripple current is reduced and have fast response characteristic to load variations.

Buck Mode

Fig 9: Simulated diagram of open loop system in Buck Mode.





Fig 12: Voltage (Drain & Source).

Fig 13: Output Current

During the buck mode, the inductor is designed with the same optimal inductance value. The inductor currents are

discontinuous, ripple current is not reduced and have slow response characteristic to load variations.

Closed Loop System

Closed loop DC-DC converter with PID-controller is simulated in both boost and buck mode using MATLAB

simulink. The tuning of controller parameters is done by using Zeigler and Nichols method. Here Kp=100,Ki=200 and

Kd=100.

Fig 14: Simulated diagram of closed loop DC-DC Converter in Boost mode with PID Controller.





Fig 17: Simulated diagram of closed loop DC-DC Converter in Buck mode with PID Controller.



In closed loop system, the DC supply voltage is given to the DC-DC converter. Then output is given to the load. This

output is taken and compared with a reference signal by using a comparator. The reference signal is a previously set



value. The difference between the output signal and the reference signal is the error signal. This is then given as input

for the PID controller. PID controller will control the duty cycle of the switches by using a pulse generator. The use of

PID controller in closed loop system results in high output voltage, very small error signal, settling time is also very

small, high voltage gain and it helps to decrease the noise disturbances.

IV. Experimental Results

Fig 20: Schematic diagram of DC-DC converter in HPMC unit.

The DC-DC converter in HPMC unit is developed and tested in the laboratory. The DC supply is given to the DC-DC

converter with the selective switch and two inductors. To isolate power circuit and control circuit optoisolator is used.

A buffer amplifier is used to transfer the voltage from a high output impedance level to low input impedance level. The

8051 Microcontroller is mainly used to trigger the MOSFET at regular intervals to produce an output. The filter is used

to produce pure DC output to the load.

The following values are found to be a near optimum for the design specifications.

Table 2: Hardware Parameters.

PARAMETER RATING

R 45Ω

L 2µH,215 µH

C 470µF

MOSFET IRF 840

Regulator LM7805,LM7812,

5-24V

Driver IC IR2110,+500V or+600V

Diode IN4007

Crystal Oscillator 230/15 V,500mA,50Hz



Fig 21: Power circuit of DC-DC Converter in HPMC unit.

Fig 22: Experimental Setup of DC-DC Converter in HPMC unit.

Fig 23: Output of DC-DC Converter in Boost mode.

Fig 24: Oscillogram of Triggering Pulse for switching operation.

D6

12

R1

1k

230VAC

C6

10uf

R1

TX3

230VAC

TLP250

LM7812

1

2

3VI

GN

D

VO

D5

12

D6

12

15V

D7

12

C5

1000uf

230VAC

R1

D4

12

TLP250

D8

LED

15V

R1

22

PIC16F877A

8910

14

15161718

19202122

23242526

27282930

1

13

234567

3334353637383940

113212 31

RE0/RD/AN5RE1/WR/AN6RE2/CS/AN7

OSC2/CLKOUT

RC0/T1OSO/T1CKIRC1/T1OSI/CCP2

RC2/CCP1RC3/SCK/SCL

RD0/PSP0RD1/PSP1RD2/PSP2RD3/PSP3

RC4/SDI/SDARC5/SDO

RC6/TX/CKRC7/RX/DT

RD4/PSP4RD5/PSP5RD6/PSP6RD7/PSP7

MCLR/VPP

OSC1/CLKIN

RA0/AN0RA1/AN1RA2/AN2RA3/AN3/VREFRA4/TOCKIRA5/AN4/SS

RBO/INTRB1RB2RB3RB4RB5RB6RB7

VD

DV

DD

VS

S

VS

S

22

D5

12

R1

1k

4MHz

C6

10uf

L2

R3100

D4

12

TX3

L1

LM7805

1

2

3VI

GN

D

VO

R1

1k

C1

U6

74ALS244A1020

1

2

4

68

11

13

18

16

14

12

9

7

GN

DV

CC

1G

1A1

1A2

1A31A42A1

2A2

1Y1

1Y2

1Y3

1Y4

2Y1

2Y2

D7

12

M1

V1

TX3

D5

12

C8

33Pf

D4

12

C6

10uf

C5

1000uf

D8

LED

LM7812

1

2

3VI

GN

D

VO

D7

12

D8

LED

C733Pf

S1

SWITCH

M2

C5

1000uf

15V

D6

12



V. Conclusion

In this paper, the proposed DC-DC converter with two inductors and a selective switch. One of the two inductors is

optimized for a buck mode, and the other is optimized for a boost mode by designing each inductor with an optimal

inductance value. By using a selective switch in the proposed converter, it ensures higher efficiency compared to the

conventional converter with a single inductor. To verify the validity of the proposed approach, the open loop and closed

loop controlled DC-DC converter are modeled and simulated using MATLAB simulink and found that the closed loop

PID-controller gives fast response, very small error signal, settling time is also very small, high voltage gain and it helps

to decrease the noise disturbances. From the experimental results, the optimal inductance ensures high output voltage.

The proposed DC-DC converter employing a selective switch and two inductors can be a promising solution for HPMC

unit.

The Hardware model using a selective switch is implemented and the results are provided. From the model it is evident

that the optimal inductance value selected is used for both buck and boost operation. Hence this DC-DC converter is

used in automobile and industrial applications, to achieve better efficiency and cost effectiveness. The simulation and

hardware results are in line predictions.

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Corresponding Author:

Dr. R.Samuel Rajesh Babu,

Email: [email protected]

mailto:[email protected]

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