Design and integration of interphase inductors for interleaved three phase voltage-source-inverters in DC-fed motor drive systems

This paper presents a detail analysis on the design and integration of interphase inductor for interleaved three phase voltage-source-inverters (VSI). The benefits of interleaving on EMI filter weight reduction are presented. Interleaving can cancel certain order of harmonics in the total output current and reduce the size and weight of the EMI filter to meet certain EMI standard. However, it also creates the voltage difference between the two converters that generate circulating current in the system which increase system loss and device stress. In order to limit the circulating current, additional interphase inductors are needed for motor drive system. The penalty of the circulating current and additional interphase inductors are analyzed in detail. Design examples are given for EMI filter and interphase inductor design, which shows that interleaving will increase the total passive weight due to the additional weight of coupled inductors for motor drive systems. In order to reduce the total weight of the passive components of the system, integration design methods for interphase inductor is proposed which indicates that certain value of AC DM inductance can be integrated with interphase inductors with negligible increase on the weight and the maximum integrated inductance is related with interleaving angle. Verifications are carried out through both the simulations and experiments on a 2kW DC-fed motor drive system.