Discontinuous Space Vector Pulse Width Modulator for a Two-Phase Three-Leg Inverter Using Analog Circuits

Abstract

This paper proposes a carrier-based Discontinuous Space Vector Pulse Width Modulation Technique (DSVPWM) using analog circuits for a two-phase three-leg Voltage Source Inverter (VSI) providing balanced and unbalanced output phase voltages. The aim of this technique is to reduce the number of commutation in a fundamental period resulting in a reduction in switching loss, electromagnetic interference and stress of devices. The analog circuit implementation of Space Vector Pulse Width Modulation (SVPWM) is based on mathematical expressions. Unlike a digital technique in modulation, a sinusoidally modulating signal is naturally compared with a triangular carrier for the analog technique without sampling. As a consequence the harmonic distortion of the load current is reduced particularly for low switching frequency. Also, with this technique, very high switching frequency is possible due to inherently wide bandwidth characteristics of the circuits. Apart from the hardware implementation, the simulation using MATLAB/Simulink has also been conducted to confirm the validity of the proposed technique. Additionally the proposed analog modulator is applied to a two-phase three-leg VSI for performance testing under various operating conditions in order to evaluate inverter losses associated with both continuous and discontinuous types of SVPWM. The simulation and experimental results illustrate that the discontinuous modulation technique is able to decrease the inverter losses and gives approximately up to 3 percent higher efficiency of the system when compared to the conventional continuous one.