Three-Phase VSI Optimal Switching Loss Reduction Using Variable Switching Frequency

Loss reduction in converters is one of main targets in power electronics to obtain higher efficiency and lower thermal stress, which can enhance the lifetime of devices. This paper presents a variable switching frequency technique for switching loss reduction in a three-phase voltage source inverter, obtaining similar output current quality as that of a space vector pulse width modulation (SVPWM) algorithm. This type of optimization has not been applied for a three-phase system before. Simulation and experimental results are also shown. The output current ripple rms value of three-phase SVPWM is used as the optimization constraint. Results of the optimization of the switching losses with quality constraints in the switching frequency as the variable are presented for different load angles and compared with classical SVPWM. Experimental results show that this technique can save up to nearly 19% in switching losses with similar total harmonic distortion of the output current, concluding that converter losses are reduced without reducing output current quality.