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Fabricated Board Setup of DC Motor Drive usingTMS320F28335 eZDSPfor education purpose

Satean Tunyasrirut, and Chakrapong charumit

Department of Instrumentation and Control Engineering, Faculty of Engineering,

Pathumwan Institute of Technology833 Rama 1 Rd.Pathumwan Bangkok 10330Telephone66(0)2-104-9099 Ext.3051

Abstract

This paper presents a fabricated board setup of the DC motor drive using TMS320F28335 eZDSP for educationpurpose with MATLAB/Simulink. This fabricated Board consists of the several peripheral circuits for motor driveapplication such as analog to digital, encoder, digital to analog and PWM input/output interface circuits. Theseinterface circuit can be used for both of DC and AC motor controls. For the control algorithm development, CodeComposer Studio (CCS) can be used together with target support TC2 of TMS320F28335 eZDSP in simulink blocksetwith Real-Time Workshop (RTW) to generate C code targeted to the DSP board. To confirm the performance, this

fabricated board is tested with the permanent magnet DC motor, 250 Watt, 90 Volt. Experimental results demonstratethe speed control design using frequency response method. The correctness of the fabricated board is verified by bothsimulation and experimental results.

1.

Introduction

In recent years, digital signal processing (DSP) hasimportant roles not only in education technology but also inindustry applications. Most of applications of DSP are

automation control systems such as robotic, vehicles and electric

drive technology. For DSP education purpose, TMS320F28335eZDSP is used to develop an algorithm together with thematlab/simulink software for motor drive applications. Benefits

of this propose are rapid prototyping and easy to develop an

algorithm by simulink blockset in target support packagelibraries (TC2). After finish an algorithm development, the real

time workshop converts the simulink model to C code.

Subsequently, the C code is automatically compiled to theassembly language and downloaded into F28335 DSP.Furthermore, register parameters can be changed via the jointtest action group (JTAG) emulator.

This paper focuses on the simple speed control method of

DC motor drive for education purpose using TMS320F28335DSP and empresses the PI controller design. The experimentalresults are discussed in order to verify the correctness of the

proposed system.

2.

TMS320F28335 eZDSP and fabricated board

In this section, TMS320F28335 eZDSP will be brieflyintroduced. The TMS320F28335 consists of a 32-bit CPU and asingle-precision 32-bit floating-point. The 150MHz systemclock is provided by an on-chip oscillator. Fig. 1 shows the

application of TMS320F28335 DSP employed with digital

fabricated board. It consists of PWM interfaces for AC drivesystem, I/O interfaces for DC drive system, digital to analogconverter (DAC), analog to digital converters (ADC) andencoder for the rotor speed detection. The DSP fabricated board

is used for motor drives. Fabricated board has created the

necessary circuits in order to interface between the software andhardware architecture as shown by Fig. 2. Peripheral analogcircuits of the fabricated board have following:

- 8 analog to digital (A/D Chanel A ) 10V

-

4 digital to analog (D/A)-

8 ePWM outputs

- 1 eQEP for speed sensor

- 8 output interfaces

PWM-1A

B

PWM-2A

B

PWM-3A

B

PWM-4A

B

PWM-5A

B

PWM-6A

B

DAC-1Low

pass

filter

DAC-2

DAC-3

DAC-4

Break signal

ADC

12 bit

1

2

3

4

5

6

7

8

eQEPA

B

Index

CPU

32 bit

SCI

TMS320 F28335 DSP

I/0

+5V

Expansion

+5V

GPIO

GPIO

Buffer

circuit

Pull up

Buffer

circuit

Pull up

Fig. 1 the Architecture of fabricated board DSP

Fig. 2 Hardware of DSP fabricatedboard for motor drives

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3.

Simulation and implementation of DC motor

In order to implement the DC motor speed control, thefirst method is finding the equivalent DC motor parametersas shown in Fig. 3. Transfer function of motor calculated

from the mathematical model can be expressed in (Eq. 1).According to (1), this transfer function is reduced as

first order equation due to easy for calculation, and ageneric Bode plot of this open-loop transfer function in

term of its magnitude and phase angle is used to calculatedPI controller as shown in Fig. 4. For a satisfactory dynamicresponse, the phase margin calculation of in this paper is 60degree at zero gain margins, and crossover frequency is 10

rad/sec.

sv

1T

2T4T

3T

aI

si

aV aR

aL

aE

emT

m

LT

aR

aL

aE

+

-

Load

LJ

aI

+

-

aV

B

DC Motor

Fig. 3 DC motor equivalent and AC-DC rectifier circuit

15094606560

2

sssV

ssG

a

m

P

(1)

Fig. 4 open-loop transfer function

Fig. 5 Bode plot of open-loop transfer function

Desired speed Actual speed

Rotor speed = 1000 rpm/Div

Fig.6 Actual and desired speed at 0-3000 rpm

Bode plot of open-loop transfer function is plotted in Fig. 5.Results of PI parameter calculation are kp and ki equal 4.8 and5.52 respectively.

For implementation, algorithm of DC motor drive has

developed by target support TC2 included in Matlab/simulinksoftware as shown in Fig. 7. Speed response of DC motor is

shown on Fig. 6

Fig. 7 Simulink blockset of DC motor drive

Conclusion

This paper has dealt with an implementation of DC motor

drive based on TMS320F28335 DSP employed with analogfabricated board. An algorithm of DC drive is developed bymatlab/simulink software. The simulation and experimental

results of DC drive confirm the effectiveness and correctness ofthe proposed. Furthermore, the proposed method is easy to study

which is suitable for education purpose.

Reference

[1] TMS320F28335, Data manual, Available online at

http://www.ti.com/lit/ds/sprs439m/sprs439m.pdf,2007

[2] N. Mohand Electrical Drives an Integrative Approach,Mnpere Minneapolis, 2001.

[3] Katsuhiko ogata Modern Control Engineering third

edition, Prentice Hall Intcvnaticnal, 1997

http://www.ti.com/lit/ds/sprs439m/sprs439m.pdfhttp://www.ti.com/lit/ds/sprs439m/sprs439m.pdf