Design of SPWM Converter for Improving the Performance of Hybrid Electric Vehicles

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Abstract

The interest has grown in Hybrid Electric Vehicles (HEVs) because of the worries over environmental pollution and fuel consumption. The main components of an HEV are the power converter, electric motor, storage system which may be a battery, ultracapacitor, etc. and the internal combustion engine (ICE). A three phase inverter changes fixed dc voltage into ac voltage whose magnitude and frequency can be obtained as required. Power electronics is an empowering technology which helps in development of such an inverter which can be utilized for many purposes. Adjustable output voltage and frequency can be got from a number of pulse width modulation (PWM) methods. Sinusoidal Pulse Width Modulation (SPWM) is a mostly used method of Pulse Width Modulation. This paper focuses on the development of Sinusoidal pulse width modulation inverter using SPWM technique as SPWM has the advantages of lesser harmonics in the output voltage. The concept of unipolar and bipolar modulation is illustrated. Simulation of SPWM inverter has been presented to analyze the output line voltage, phase voltage and SPWM technique. Simulation of SPWM inverter has been done without and with filter and FFT analysis has been done to find the total harmonic distortion (THD) in the output line voltage. Hardware development of SPWM inverter has been done. dSPACE controller has been used for the generation of the firing pulses. Finally experimental results have been presented which include the waveforms of the firing pulses, output line voltage and output phase voltage.

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Keywords

Hybrid Electric Vehicle, Voltage Source Inverter, Power MOSFET, SPWM, Opto isolator,dSPACE, THD