Comparison of Three Switching Strategies for Indirect Matrix Converter

The Indirect Matrix Converter (IMC) concept has been gaining recognition as a promising circuit alternative in recent years. An IMC has separate line and load side converters. Each switching period of line side converter is split into two portions. In each portion., the IMC is equivalent to a conventional inverter. Thus, output voltage can be obtained through applying a kind of space vector PWM to the load side converter. Conventional space vector pulsewidth modulation (CSVPWM) employs conventional switching sequence, which divides the zero vector time equally between two zero states in each modulation cycle. If a double edge CSVPWM used in each portion, each switch of the load side converter would have a switching frequency twice the sampling frequency. Therefore, bus-clamping PWM (BCPWM) techniques which use only one zero state in each modulation cycle can be used to reduce the switching frequency. This paper comprises two types of BCPWM techniques and a new special type of switching sequences, termed here as "sawthooth sequences". The proposed technique: 1) reduces the load side converter switching frequency and losses; 2) has good performance in viewpoint of input/output waveform quality 3) has switching losses independent of output power factor. Simulation results are presented to demonstrate the validity of the proposed space vector modulation technique.