Over-Modulation Operation of Multiple-Channel Indirect Matrix Converter System

Abstract

Indirect Matrix Converter (IMC) possesses the advantages of high power density, good performance of input and output waveforms, bidirectional power flow, etc. Besides these superiorities, more degrees of freedom are offered by multiple-channel IMC compared with single-channel IMC. The application of IMC fed three-phase permanent magnetic synchronous motor (PMSM) has been widely studied, which takes great advantages of the converter's small volume and high reliability. However, few researches have been focused on the multiple-channel IMC fed multiphase PMSM. Furthermore, the maximum voltage transfer ratio (VTR) of traditional modulation strategy for IMC is 0.866 when space vector modulation is applied within linear modulation region, which limits the application of IMC especially for condition of low input voltage. The purpose of this paper is to propose the over-modulation strategy for increasing the voltage transfer ratio of multiple-channel IMC. The key point is to change the weighting factor of the hexagon vectors and basic vectors to synthesize the reference current and voltage. On the other hand, the existence of the LC filter at the grid side results in LC resonance which will do harm to power grid. To suppress the LC resonance on grid side, the active damping control method has been proposed on grid side with over-modulation on machine side. For introduction of active damping, the power balance of the drive system is elaborated, which means the input power, the virtual bus power and the output power should be consistent with each other. Both simulation and experiment are presented to verify the feasibility of the proposed strategy.