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SPEED CONTROL OF INDUCTION MOTOR USING PULSE WIDTH

MODULATED INVERTERPRESENTED BY: GUIDED BY: Atul Kumar 0701105183 Dr. Gayadhar Panda Deepak Kumar Sahoo 0821105003 Balaji Biswanath Panda 0701105111 Rajendra Narayan Senapati 0701105115

ELECTRICAL ENGINEERING DEPARTMENT

INDIRA GANDHI INSTITUTE OF TECHNOLOGY Sarang-759146, Dhenkanal, Orissa

OUTLINE INTRODUCTION

PULSE WIDTH MODUTION IN INVERTER TYPES OF MULTIPLE PULSE MODULATION SINUSOIDAL PULSE WIDTH MODULATION MATLAB SIMULATION FOR SINGLE PHASE PWM

INVERTER PLOT FOR CURRENT Vs TIME AND VOLTAGE Vs TIME SPWM FOR 3 PHASE VSI(voltage source inverter) MATLAB SIMULATION FOR THREE PHASE PWM

INVERTER PLOT FOR V_inverter Vs TIME AND V_ab load Vs TIME CONCLUSION

INTRODUCTION What is PWM ? Increasing trends of SWPWM Problem faced by power electronics

design engineers and it’s solution Objective

PULSE WIDTH MODUTION IN INVERTER

Techniques are: Single Pulse Modulation Triangular carrier signal is compared with the

rectangular reference signal to generate the positive and negative pulses required for Inverter output voltage.

gating angles Multiple Pulse Modulation Generation of multiple pulses of uniform widths Two types depending on the width of the

output pulses a) Uniform pulse-width-modulation techniqueb) Nonuniform pulse-width-modulation technique

Fig. : Uniform pulse-width-modulation technique (UPWM)

UNIFORM PULSE WIDTH MODULATION

Pulse width is uniform Effective output voltage of the inverter

is determined by

depends on number of pulses per half cycle (p)

Modified form

SINUSOIDAL PULSE WIDTH MODULATOIN For realizing SPWM, a high frequency triangular

carrier wave vc andvΔ is compared with a sinusoidal reference wave of the desired frequency

carrier and reference waves are mixed in a comparator

Modulation index

Normalized carrier frequency

Contd………….. For small values of mf (mf < 21), the carrier

signal vΔ and the modulating signal vc should be synchronized to each other

For large values of mf (mf > 21), the sub harmonics are negligible

In the over modulation region (ma > 1) some intersections between the carrier and the modulating signal are missed

Fig. : The half-bridge VSI. Ideal waveforms for the SPWM (ma =0.8, mf =9)(a)carrier and modulating signals; (b) switch S+ state; (c) switch S- state; (d) ac output voltage; (e) ac output voltage spectrum; (f) ac output current; (g) dc current; (h) dc current spectrum; (i) switch S+ current; (j) diode D+ current

Fig.: The full-bridge VSI. Ideal waveforms for SPWM (ma = 0.8, mf = 0. 8): (a) carrier and modulating signals; (b) switch S1+ state; (c) switch S2+ state; (d) ac output voltage; (e) ac output voltage spectrum; (f) ac output current; (g) dc current; (h) dc current spectrum; (i) switch S1+ current; (j) diode D1+ current.

Matlab simulation for single phase pwm inverter

current

time

time

voltage

SPWM FOR 3 PHASE VSI(voltage source inverter)

Extension of the one introduced for single-phase VSI

Normalized carrier frequency mf should be an odd multiple of 3

For nearly sinusoidal ac load current, the harmonics in the dc link current are at frequencies given by

Over modulation

Fig: The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf = 0.9): (a) carrier and modulating signals; (b) switch S1 state; (c) switch S3 state; (d) ac output voltage; (e) ac output voltage spectrum; (f) ac output current; (g) dc current; (h) dc current spectrum; (i) switch S1 current; (j) diode D1 current.

Matlab Simulations of three phase PWM inverter

V_inverter

time

time

V_ab load

CONCLUSION

Sine wave modulation technique has become the most popular and important PWM technique for Three Phase Voltage Source Inverters for the control of

AC Induction motor Brushless DC motor Switched Reluctance motor Permanent Magnet Synchronous motor

Technique described here has a clear advantage over the other traditional PWM techniques in terms of heating the motor.

In the future we are going to control the speed of ac drive.

THANKS TO YOU

FOR YOUR PATIENCE HEARING