A Simplified Space Vector PWM Algorithm for Four-Switch Three-phase Inverters

Four-switch three-phase (FSTP) inverters are attractive in many applications due to their low cost and high reliability. The paper proposed a simplified Space Vector PWM (SVPWM) algorithm for FSTP inverters. The method applies the modulation of the space vectors twice and generates unified control formulas across the four regions in a fundamental period. It simplifies the understanding and analysis of FSTP inverters and makes the duty ratio calculation and switching sequence selection much easier. The effectiveness of the proposed method is demonstrated by the studies of an FSTP inverter using MATLAB Simulink and Simscape. It has been shown that FSTP inverters are the most efficient and less unbalanced when working with a large modulation ratio around the full-load condition. FSTP inverters can be more efficient than six-switch three-phase (SSTP) inverters when operating at the same input/output voltage ratio with SSTP inverters. Combining with the low-cost feature (due to fewer switches and interface circuits), FSTP inverters are good options for solar panel and electric vehicle applications.