A harmonic elimination technique for voltage source inverter using embedded controller

Abstract

This paper presents the generation of the least distorted single phase variable voltage output of a half-bridge voltage source inverter (VSI) by appropriate pulse width modulation (PWM) technique. The necessary PWM control signal for the power converter is generated by embedded PIC microcontroller (PIC 18F67K22). The constant PWM and the sinusoidal PWM (SPWM) signals of variable duty cycles are produced and applied separately to the power electronics inverter. Their relative performances are compared experimentally in terms of the quality of output voltage waveform. The PWM signal for VSI includes suitable dead time at the rising edge of pulses responsible to turn on the complementary switch. The dead time is provided to avoid simultaneous conduction of both switches in the same leg. The assembly language program has been written for concerned microcontroller supplying required PWM signal. The concept is validated by both MATLAB-SIMULINK based simulation and hardware experimental set-up consisting of single phase VSI and embedded PIC18F67K22 microcontroller. The experimental results show that AC output voltage of the VSI is prone to lesser distortion due to harmonic elimination in the case of SPWM compared to the conventional constant PWM methodology.