Development of Space V ector Pulse W idth M …...Development of Space V ector Pulse W idth M odulation Algorithm for V oltage Source Inverter U sing dsPIC C ontroller 30F4011 S. Allira

Development of Space Vector Pulse Width Modulation Algorithm for Voltage Source Inverter

Using dsPIC Controller 30F4011

S. Allirani1 and V. B. Thurai Raaj2

1Department of EEE, Sri Ramakrishna Engineering

College,Coimbatore - 641022, Tamilnadu, India.

[email protected]

2Department of EEE, Madanapalle Institute of Technology and

Science Madanapalle - 641022, AndraPradash, India.

[email protected]

Abstract

The Main focus of this paper is to design and develop a highly effective Space Vector Modulation (SVM) algorithmic rule by using dsPIC Microcontroller. SVM methodology is reduces the harmonic distortion and it terrifically path to implement a control circuitry for a drive. This Practice has found its applications recently in voltage source inverters, AC/DC converters, resonant converter, multilevel converters, matrix converters etc. This paper discusses the implementation of this SVM technique using low cost, versatile dsPIC controller 30F4011 for VSI along with experimental results.

Keywords Sinusoidal Pulse Width Modulation, Space vector modulation, Voltage source inverter, dsPIC controller.

1. INTRODUCTION

Initially, sinusoidal PWM was a one of the most familiar technique for AC

drives control applications [9]. In this method a triangular wave acts as a carrier

signal, sine wave act as a reference signal the points of intersection determine the

switching instants of the power devices constituting the inverter. This method was

found to suffer from the following disadvantages:

1. It is not able to make full use of DC bus voltage of the inverter and

2. This method produces relatively high harmonic distortion in the inverter

outputs.

In comparison, Space Vector PWM (SVPWM) is a sophisticated/multifaceted

technique capable of generating higher sine wave voltage from the inverter for given

DC bus voltage.

International Journal of Pure and Applied MathematicsVolume 114 No. 9 2017, 257-269ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu

257

SVM offers several additional advantages like, less harmonic distortion when

compared to SPWM. Reduced switching losses, which will become significant for

inverters of high power rating. This technique is extendable to multilevel inverters

by the addition of switching states. It is compatible for digital implementation

In papers [1] and [2], the basic principle of SVM was presented and realized in

MATLAB/ Simulink environment. In paper [3], a new SVM technique was used to

control PWM rectifier to achieve unity power factor and for reducing the harmonic

currents of non linear loads. The proposed control technique has the advantage of

reducing switching frequency and losses by applying the zero voltage vectors [3]. The

control structure was developed and implemented on a DSP controller,

TMS320LF2407.

In paper [4], space-vector based Pulse Width Modulation (PWM) strategy was

discussed highlighting selective harmonic elimination. In paper [5], SVM was shown

to reduce the inverter losses. Several modulation techniques such as Sinus PWM

(SPWM), Square Wave PWM, Carrier Based PWM and Space Vector PWM

(SVPWM) techniques were implemented using dsPIC30F2010 controller (a DSP

controller developed for motor control applications) in paper [6] and it was shown

experimentally, SVPWM produce minimum current harmonics. SVM technique for

multilevel inverter was discussed in [7]. Simulation results of SVM controlled IM for

both open loop and closed loop conditions are given in paper [8], [10].

This paper proposes a simple and compact controller, dsPIC30F4011, suitable for IM

drive. The voltage source inverter is designed and implemented using power

MOSFETs with sophisticated driver IC IR240. The SVPWM algorithm is

implemented in dsPIC controller 30F4011 which is featured with specific motor

control PWM module.

The paper is organized as follows: Section II describes SVM algorithm and section III

presents digital signal controller dsPIC30F4011. Section IV discusses the

experimental setup and results. The paper is concluded in section V.

2. SPACE VECTOR PULSE WIDTH

MODULATION

Induction motors have many advantages like simple construction, reliability,

ruggedness and low cost. Initially DC drives are popular in the field of adjustable

speed drives due to their better dynamic performance and simple control techniques.

International Journal of Pure and Applied Mathematics Special Issue

258

Fig. 1. VSI fed Induction Motor Drive

After the arrival of powerful switching components and efficient control

techniques, IM drives have gained popularity. Mostly, in IM drives, IM is fed by

voltage source inverter controlled by SVM technique.

Fig.1 shows VSI fed IM drive controlled with SVM technique. A VSI consists of

six power switches in three arms. Each arms have two switches one at top another at

lower, the top side switches are S1, S3 & S5 lower side switches are S4, S6 & S2 to

drive three phase IM.

Fig.2. Eight switching state topologies of three phase inverter.


259

Fig.3. Voltage vectors and sectors

The on and off states of upper arm switches S1, S3, S5 can be used to

determine the output voltage. The relationship between the switching variable

corresponding to upper arm switches [a b c]t as in fig. 2 and the line to line voltage

vector [Vab Vbc Vca]t is given by equation [1]

Table I Sector selection table

Voltage

Vectors

Switching

Vectors

Line to neutral

Voltage Line to Line Voltage

a b c Van Vbn Vcn Vab Vbc Vca

V0 0 0 0 0 0 0 0 0 0

V1 1 0 0 2/3Vdc -1/3

Vdc

-1/3

Vdc Vdc 0 - Vdc

V2 1 1 0 1/3

Vdc

1/3

Vdc

-2/3

Vdc 0 Vdc - Vdc

V3 0 1 0 -1/3

Vdc

2/3

Vdc

-1/3

Vdc - Vdc Vdc 0

V4 0 1 1 -2/3

Vdc 1/3Vdc

1/3

Vdc - Vdc 0 Vdc

V5 0 0 1 -1/3

Vdc

-1/3

Vdc

2/3

Vdc 0 - Vdc Vdc

V6 1 0 1 1/3

Vdc

-2/3

Vdc

1/3

Vdc Vdc - Vdc 0

V7 1 1 1 0 0 0 0 0 0


260

[

] = [

] [ ] [1]

Similarly, the relationship between switching variable [a b c]t and

phase voltages can be expressed as in equation [2]

[

] =

[

] [ ] [2]

These line to line voltages and line to neutral voltages in terms of

DC link voltage Vdc are given in Table I.

To implement the SVPWM, the voltage equations in the abc reference

frame can be transformed into stationary dq reference frame as in equation [3]

[

] =

[

] [

] [3]

(

) [4]

‖ ‖ √

[5]

The conduction time for the upper and lower arms are calculated by

using the adjoining voltage space vectors and two null vectors. Assume the

reference voltage space vector Vref is located in sector 1 as shown in fig. 4.

Then the switching time duration at sector 1 is calculated as in equations (6) &

(7)

Fig.4. Expanded view of sector 1

∫ ∫ ∫ ∫

[6]

[7]


261

Similarly for the remaining five sectors the equations for switching time

calculations are given in table II. Fig.5 presents the switching patterns of S1, S3,

and S5 in sector 1. The reference voltage space vector Vref is assumed to be

located 7at null vector V0 (000) at T0 time and then switched to first space vector

V1 (100). It is held at V1 for time T1, then the reference voltage vector switched to

V2 (110) and remains there for T2 time. Finally, the reference voltage vector

moved to V7 (111).

Table II Equations for switching time

At this time all upper arms are turned on and all lower arms are turned off.

Fig.5. Switching state timing diagram


262

3. dsPIC CONTROLLER The dsPIC30F motor control family is specifically designed to control the motor.

dsPICs are processing the data at much higher rate than the normal PIC

controllers. It has motor control pulse width modulation (MCPWM) module and

high speed analog to digital converters. The MCPWM modulator has eight output

pins and six PWM generators. The DSP engine of dsPIC30F4011 supports the

necessary mathematical operations. It has 10 bit, 1 MSPS analog to digital

converter. Fig.6 shows schmatic diagram of dsPIC30F4011 controller [11].

Fig.6. Schmatic of dsPIC 30F4011 controller

The controller is inbuilt with DSP Engine which is featured with [11]

Dual data fetch

Accumulator write –back for DSP operations

Modulo and Bit-Reversed Addressing modes

Two, 40-bit wide accumulators with optional saturation logic

All DSP instructions are single cycle

17-bit × 17-bit single-cycle hardware fractional/integer multiplier

The controller has specific Motor Control PWM Module whose features are [11]

6 PWM output channels

Complementary or independent output modes

Edge and center aligned modes

3 duty cycle generators

Dedicated time base


263

Programmable output polarity

Dead-time control for Complementary mode

Manual output control

Trigger for A/D conversions

4. EXPERIMENTAL SET UP AND

RESULTS The block diagram of experimental set up of the proposed digital signal controller

based IM drive is shown in fig.7. The IM is fed by MOSFET based VSI. The switching

pulses for inverter switches are generated using digital signal controller

dsPIC30F4011.

Fig.7. Block diagram of dsPIC controller based IM drive

Fig. 8 (a) dsPIC Controller section

Fig. 8 (b) Inverter Section


264

The PWM pulses are given to MOSFETs through MOFET driver IC IR240. The duty

cycle is controlled using dsPIC controller. Fig. 8(a) and 8(b) show the photographs of

controller section and three phase inverter section, respectively.

4.1. Results and Discussions Fig. 9 shows switching pulses obtained in SVM based inverter with dc link voltage of

400 V, fundamental frequency of 50 Hz and PWM carrier frequency of 20 kHz.

Fig. 9(a) MOSFET driver output signal Fig. 9(b) Gate pulses generated for Phase

A (S1 &S4)

Fig. 9(c) Gate pulses generated for

Phase B (S5 & S6)

Fig. 9(d) Gate pulses generated for

Phase C (S3 & S2)

Fig. 9(a) shows the MOSFET driver output signal of 12V, raised from 5V. As

the magnitude of 5V generated by controller is not sufficient to drive the MOSFET in

VSI, the sophisticated MOSFET driver IC IRF240 is used to increase the voltage

level from 5V to 12V. Fig. 9(b) to Fig. 9(d) show the gate pulses applied to each of the

three arms of three phase bridge inverter.


265

Fig. 9 (e) Switching pulses for

the switches (S1 & S3)

Fig. 9(f) Switching pulses for the

switches

(S3 & S5)

Fig. 9(g) Switching pulses for the

switches (S5 & S1)

Fig. 9 (h) Dead time between upper

and lower switches of same leg

Fig. 9(i) PWM carrier frequency of

20 kHz

Fig. 9(j) Inverter output voltage

(Phase voltage)


266

The gate pulses of switches in conduction are shown in figs 9(e) to 9(g). Fig.

9(h) shows that there is sufficient time delay between off time and on time of the

switches on the same leg in order to avoid dead short of the source. Fig. 9(i) shows

the PWM carrier signal of frequency 20 kHz generated using dsPIC controller and

fig. 9(j) represents the output phase voltage of VSI.

5. CONCLUSION This paper presented a design and implementation of the space vector

modulation algorithm for calculating switching times in three phase voltage source

inverter. This SVM algorithm was implemented using a dsPIC controller

dsPIC30F4011. The voltage source inverter was implemented using MOSFET

IRF840 which is fed by sophisticated MOSFET driver IC IR240. The experimental

results proved that this compact and efficient algorithm allowing high switching

rates with relatively low cost dsPIC controllers.

References [1]. Baohua Lang, Miao, Weiguo Liu, Guangzhao Luo, “ Simulation and

experiment study of space vector pulse width modulation”, the ninth

International Conference on Electronic Measurement and Instruments, ICEMI

2009.

[2]. Alexandru Savulescu, “The analysis and the simulation of the SVM generator

used for the control of the electric drives with asynchronous motors”, Sixth

International Conference on Electromechanical and Power Systems, October 4-

6, 2007, Moldova.

[3]. Belhadji, L. Aliouane, K., Ghannam, T. Kheloni, A. “A new space vector

current control of the three phase PWM rectifier”, POWERENG 2007, Portugal,

April 12-14, 2007, pp.60-65.

[4]. Sidney R.Bowes, Sukhminder Singh Grewal, “Novel space vector based

harmonic elimination inverter control” IEEE Transactions on Industrial

Applications, Vol.36, No.2, March/April 2000.

[5]. Andrew Trentin, Peride Zanchetta, Patrick wheeler, “New investigations on

space vector modulation technique for voltage source inverter in AC drive”,

IEEE, 2006, pp.1627 – 1632.

[6]. Mehmet Yumurtaci, Seydi Vakkas Ustan, Secil Varbak Nasa, Hasan Cimen,

“Comparison of output current harmonics of voltage source inverter used

different PWM control techniques”, WSEAS Transactions on power system, pp.

695 – 704.


267

[7]. Wenxi Yao, Haibing Hu, Zhengyu Lu, “Comparisons of space vector

modulation and carrier based modulation of multilevel inverter”, IEEE

Transactions on Power Electronics, Vol.23. No.1, January 2008, pp. 45 – 51.

[8]. Linga Swamy, R. Satish Kumar, P. “Speed control of space vector modulated

inverter driven induction motor”, International multi conference of Engineers

and computer Scientists, 2008, Vol.II, IMECS 2008,19-21 March, Hong Kong.

[9]. Bose B. K., Modern Power Electronics and AC Drives, Englewood Cliffs, NJ:

Prentice - Hall, 2001.

[10]. Allirani, S., Jagannathan, V., “High Performance Direct Torque Control of

Induction Motor Drives Using Space Vector Modulation”, International Journal of

Computer Science Issues (IJCSI), Vol.7, Issue.6, pp.178-186, November 2010.

[11]. www.microchip.com, „dsPIC 30F4011/4012 – Data sheet‟, Microchip

Technology, 2005.


268

269

270

Documents

Development of Space V ector Pulse W idth M …...Development of Space V ector Pulse W idth M odulation Algorithm for V oltage Source Inverter U sing dsPIC C ontroller 30F4011 S. Allira