development and implementation of embedded dsp...

International Journal of Current Engineering and Technology E-ISSN 2277 – 4106, P-ISSN 2347 – 5161 ©2016 INPRESSCO®, All Rights Reserved Available at http://inpressco.com/category/ijcet

Research Article

1805| International Journal of Current Engineering and Technology, Vol.6, No.5 (Oct 2016)

Development and Implementation of Embedded DSP Controllers for Cascaded H-Bridge Multilevel Inverter based Drive

D.P.Maheshwari#* and A.S.Pandya!

#Vishwakarma Government Engineering College, Chandkheda, Ahmedabad, India !AVPT, Rajkot, India

Accepted 10 Oct 2016, Available online 15 Oct 2016, Vol.6, No.5 (Oct 2016)

Abstract Paper discusses about the design and implementation of a DSP based Induction motor drive using Hybrid Multilevel Inverter configuration focusing mainly on total harmonic distortion (THD). The purpose of the circuits presented here is to minimize the reverse voltage stress that affects the power switches and decrease the harmonic distortion of the voltage applied to the load. Paper discusses DSP based scheme for 5 levels HMLI . Keywords: HMLI-Hybrid Mulilevel Inverter 1. Introduction

1 This paper presents four different sequential switchihybrid-modulation strategies and cascaded multilevel inverters. With hybrid modulation techniques we can use less no of switches as compared to cascaded multilevel inverter so switching losses are reduced.

(a)

Fig.1 Block diagram: DSP Based Drive using HMLI

Fig 1 shows hardware setup for a DSP 28335 based drive using HMLI (K. A. Corzine, 2004), (M.D. Manjrekar and T.A. Lipo, 1998) the DC generator with load panel is used to load the IM which is controlled by a DSP 28335 based controller and a three phase HMLI stack. PC is used to select the control technique for the HMLI by the user. *Corresponding author D.P.Maheshwari is a Research scholar at Kadi University, India and Dr. A.S.Pandya is working as Principal

(b)

Fig.1 System Setup: DSP Based Drive using HMLI Based on the load feedback signals are generated through sensor interface are applied to DSP board. DSP 28335 based on the control selected method, computes firing angles and generates control signals for the HMLI which are applied to inverter through isolator. The inverter output is used to control speed of the drive. Emulator is used for hardware testing of the DSP signals. Full H-bridge (T. A. Lipo and M. D. Manjrekar,1999) is connected in series with half bridge. MOSFETS are used as a switch, output voltage is addition of H-bridge and half bridge output as shown in fig 2. The angles are found by resultant theory method for particular switching time. Elimination for third harmonics the relations are: (1) (2)

D.P.Maheshwari et al Development and Implementation of Embedded DSP Controllers for Cascaded H-Bridge Multilevel Inverter based Drive


Where, m is the Modulation Index.

Fig.2 Five level output voltage for HMLI 2. Power Circuit The power circuit(H. Liu, L. M. Tolbert, B. Ozpineci, Z. Du, 2008) Fig 3 blocks consist of one isolated power supply H- bridge, half bridge and R load. The H- bridge inverter consist of four power MOSFETs. These switches are made on and off at desired instant as per requirement of output frequency and voltage. The upper switches from positive group and lower switches from negative group. The half bridge inverter consists of two power MOSFETs. These switches are made on and off at desire instant as per requirement of output frequency and voltage. The upper switch from positive group and lower switch from negative group. Resistive load is considered as a load to the output of the inverter which is connected in series.

Fig 3-a: Circuit configuration of the proposed hybrid multilevel inverter

Fig.3-b: Front Panel Diagram :HMLI Stack

3. Control Circuit In this Section chapter discusses various simulation models and responses for single phase hybrid multilevel inverter, employing PWM method (B. P. McGrath, D. G. Holmes, M. Manjrekar, et al,2000) and Hybrid modulation technique (B. P. McGrath and D. G. Holmes,2002) . The simulation and FFT analysis for PWMwith optimal angle control method is carried out for different modulation index at different angles. 3.1 PWM with optimal angle control method

Fig.4 Simulation model for optimal angle control method

The result is shown for modulation index is 0.9. The angles are 33 and 86.4 . Its FFT analysis is shown below. The THD Total harmonic distortion (THD) is 43.06%.

Output Wave Form FFT Analysis

Fig.5 PWM method with m=0.9

Output FFT Analysis

Fig.6 PWM method, m= 1.0

Q1

IRF840

Q2

IRF840

Q3

IRF840

Q4

IRF840

R13.6

C1100uF-POL

5

R23.6

R33.6

R43.6

C2100uF-POL

C3100uF-POL

C4100uF-POL

R55.1k

6

Q5

IRF840

Q6

IRF840

R63.6

R73.6

C5100uF-POL

C6100uF-POL

8

V1220 V

V2220 V

V3220 V

9

1

10

0

4



Output FFT Analysis

Fig.7 PWM method, m= 1.52

3.2 Hybrid Modulation Technique 3.2.1 Simulation model of gate pulses for Hybrid Technique

Fig.8 Simulation model: Gate pulse

Fig.9 Control signals: Hybrid modulation technique

Fig.10 Gating signals: Hybrid modulation Technique

4. CCS link for Software Upload The Code Composer Studio (Code Composer Studio- User manual) does not accept continuous signals. It

only works for discrete signals. So, it is required to convert the continuous simulation into discrete simulation.

Fig.11 CCS Link for PWM with optimal angle control method

4.1 Discrete Simulation: Hybrid Modulation Technique The main characteristic of these modulations are the reduction of switching losses with good harmonic performance, balanced power loss dissipation among the devices with in a cell, and among the series-connected cells. Here we are doing a discrete simulation and generate signal for all six Gate of single phases.

Fig.12 Discrete Simulation: Hybrid Modulation Technique

Fig.13 Result for Discrete Hybrid Modulation Technique



4.2 Hybrid method MSPWM and its base modulator design are implemented on a TMS320F28335 digital signal processor (DSP). Complex programmable logic device realizes hybrid-modulation algorithm with base pulse width modulation (PWM) circulation, and is integrated with DSP for sequential switching hybrid PWM generation. Here we are ccs studio 3.3. Matlab to CCS to DSP RTDX and XDS 510PP. Exhange real-time data between MATLAB and a running DSP via RTDX without halting the DSP program.

Fig.14 CCS Link for Hybrid Modulation Technique 5. Hardware Design: Power Circuit, Driver, Interfacing Circuit This section describes design of control circuit which consists of (Mathworks Manual), (Texas Instruments CCS Link for MATLAB) DSP Controller kit – TMS320X28335, Code Composer Studio 3.3,Emulator – XDS510PP for generating gate pulse and driver circuit. It is necessary to provide isolation between power circuit and control circuit for safety purpose. Optocoupler is used for isolation. MCT6 optocoupler is used as an isolator. DSP kit output voltage (3.3V) and current (5.45 mA), while forward voltage of MCT6 = 1.5 and R = 330Ω.

Fig.15 Isolation circuit

The IR2110 is high voltage, high speed driver for power MOSFET with independent high and low side referenced

output channels. With the help of application note value of floating capacitor, fast switching diode and pull up resistor are computed. Inverter configuration uses one H- Bridge and a half

bridge connected in series. Both circuits need their

separate supply, floating and isolated. H Bridge has

only one supply but the half bridge has two separate

supply. IRF840 MOSFETs (voltage rating is 500V and

current rating is 8Amp_ are selected Due to on- state

and switching loss heat is generated within the power

device. Appropriate heat sink used 2 Amp current

carrying capacity for cooling purpose of MOSFET.A

snubber circuit consist of series combination of

resistor(3.7 Ω) and capacitor (100 μF)is connected

across the MOSFETs.[ RC-time constant (37 nSec)].

Fig.16 Power Circuit

6. Hardware Testing and Wave-Form

DSP Controller kit–TMS320X28335 (Texas

Instruments CCS Link for MATLAB) is used for the

control signal and these control signals are given to the

MOSFETs of the power circuit. Experiment has been

carried out to check the results with R and R-L load.

DSP Kit with emulator Power Module

Fig.17 Test setup: R & R-L load

U1A

MCT6

2

1

8

7

U1B

MCT6

2

1

8

7

R2

330

2

R1

330

1

cathodcathod

3

+15 Volt

R3

1.0k

R4

1.0k

6

7

To driver

To driver

From DSP kit G1

From DSP kit G2

R5

1.0k

0

R6

1.0k

0

5

4

U1A

MCT6

2

1

8

7

U1B

MCT6

2

1

8

7

R2

330

2

R1

330

1

3 R3

1.0k

R4

1.0k

R5

1.0k

0

R6

1.0k

0

5

4

+15 Volt

6

+15 Volt

C11.0uFC310uF

11

D1BY228

0

U2

NET_14

IR2110

R7

10k

10

R8

10k

8

13

Q1

IRF840

12

Q2

IRF840

14

U3A

MCT6

2

1

8

7

U3B

MCT6

2

1

8

7

R9

330

R10

330

R11

1.0k

R12

1.0k

R13

1.0k

R14

1.0k

+15 Volt +15 Volt

C21.0uFC410uF

D2BY228

U4

NET_14

IR2110

R15

10k

R16

10k

Q3

IRF840

Q4

IRF840

41

40

3739

38

0

36

34

3331

32

0

030

29

28

U5A

MCT6

2

1

8

7

U5B

MCT6

2

1

8

7

R17

330

R18

330

R19

1.0k

R20

1.0k

R21

1.0k

R22

1.0k

+15 Volt +15 Volt

C51.0uFC610uF

D3BY228

U6

NET_14

IR2110

R23

10k

R24

10k

Q5

IRF840

Q6

IRF840

56

55

5254

53

0

51

49

4846

47

0

045

44

43

17

0

0

C71.0uF

9

18

0

C81.0uF

C91.0uF

35

0

50

0

g1

g1g1

g1g1

g1

g1

g1

g2

g2g2

g2

G1

U7

NET_16

MC4050B

20

+5 volt

21

22

23 24

25

26

G2

G3

G4

G5

G6

0

0

0

0

g3

g3

g3

g3

+220 volt

V1220 V

7

V2220 V

0

42

0

To load

16

d1

d2

d3

d4

d5

d6



THD: Phase voltage & Phase Current

THD : Line to Line Voltage

Fig.18: Test Results with Motor Drive

Fig 18 represents waveforms including phase voltage, phase current and Line-to-Line voltages for the test setup of Fig 17.

Fig 19: System Setup: Drive with DSP, Inverter and Load panel

THD: Phase voltage & Phase Current

THD : Line to Line Voltage

Fig 20: Test Results with Motor Drive

Fig 20 represents waveforms including phase voltage, phase current and Line-to-Line voltages for the test setup of Fig 19.

Conclusion The control signals for power circuit of the 5-level three-phase HMLI are generated by DSP 28335 controller using digital techniques for ma = 0.8. The prototype is tested with R and R-L load and used for motor drive. Results of the test are presented in Table-1. It shows that the output line-line and phase voltages has 5 levels that its THD voltage is between 15.6% and 16.7%, the output waveform of phase current is close to sinusoidal that its THD current is between 3.2% and 4.2%.

Table:1 Result of THD on R,R-L load and Induction Motor

Type of Load

Phase Voltage (RMS)

Phase Current (RMS)

THD ( %) Phase Curre

nt

Line to Line Voltage

R Load

225 360 mA 5.2 17.4%,

16.6%, and 18%.

R-L Load ( 150 ;

0.125 H) 195 708 mA 4.5

17.9%, 17.4%, and

18.3%. Induction

Motor Drive

206 volts 786 mA 4.2 16.2%,15.6%

and 16.7%

References K. A. Corzine (Feb. 24, 2004), Cascaded multi-level H-bridge

drive, U.S. Patent 6 697 271. M.D. Manjrekar and T.A. Lipo (Feb. 1998), A Hybrid

Multilevel Inverter Topology or Drive Applications, IEEE APEC, Anaheim, California, pp. 523-529.

T. A. Lipo and M. D. Manjrekar (Aug. 19, 1999), Hybrid topology for multilevel power conversion, Patent W.O. 99/41 828.

H. Liu, L. M. Tolbert, B. Ozpineci, Z. Du (2008), Comparison of Fundamental Frequency and PWM Methods Applied on a Hybrid Cascaded Multilevel Inverter, IEEE Industrial Electronics Society Annual Conference, Orlando, Florida, November 10-13, pp. 3233-3237

M. D. Manjrekar, P. Steimer and T. A. Lipo (May/June 2000), Hybrid Multilevel Power Conversion System: A Competitive Solution for High Power Applications, IEEE Trans. On Industry Applications, Vol. 36, No. 3, pp.834-841.

B. P. McGrath, D. G. Holmes, M. Manjrekar, et al. (2000) An improved modulation strategy for a Hybrid multilevel inverter, Records of IEEE-IAS Annual Meeting, pp. 2086-2093.

B. P. McGrath and D. G. Holmes (Aug. 2002), Multicarrier PWM strategies for multilevel inverters, IEEE Trans. Ind. Electron., Vol. 49, No.4, pp. 858–867

H. Abu-Rub, J. Holtz, J. Rodriguez, and G. Baoming (Aug. 2010), Medium-voltage multilevel converters: State of the art, challenges, and requirements in industrial applications, IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2581–2596.

Mathworks Inc., MATLAB/SIIMULINK : User Manual Getting Started

Texas Instruments: Code Composer Studio- User manual Texas Instruments CCS Link for MATLA

POWER MODULE



Biography Prof.D.P.Maheshwari is associate professor in electrical engineering department at Vishwkarma Government Engineering College, Chandkheda. He received his BE and ME degree from Saurastra University and Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal respectively. He has over 15 years of teaching experience. His areas of interest are Power Electronics and Drives.

Prof. Dr. A.S.Pandya is Principal at AVPTI, Rajkot. He received his Ph.D from M.S.University, Vadodara. He has more than 25 year’s academic experience. His areas of interest are Power Electronics and Power System. He has received two international and three national awards. He has published 30 plus Research paper in International Journals and conference. He is awarded by Prominent Rashtriya Vidhya Sarswati Purshkar from Delhi and Asia Pacific Achievement Award at Taskent, Russia.

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