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
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