Analysis and design of a sine wave filter for GaN-based low-voltage variable frequency drives

Abstract

Gallium nitride (GaN) devices have been widely adopted to achieve high efficiency and high power density as alternative solutions to silicon devices. When the GaN power devices are used for variable frequency drive (VFD) systems, the high dv/dt pulses at the motor terminal, which induce shaft voltage and common mode current, should be carefully considered to ensure system reliability. Although the high dv/dt issues can be mitigated with a dv/dt filter method, it leads to performance degradation depending on cable length. Meanwhile, a matrix converter also becomes a next-generation power converter for the VFDs which has a regeneration capability and unity power factor. Thus, this paper discusses the GaN-based matrix converter for the VFD as a study case considering the motor terminal voltage quality and the common mode current. Also, a sine wave filter is adopted to cope with the terminal voltage quality irrespective of cable length. The optimized design procedure of the sine filter considers practical issues. Experimental results are presented to suggest a suitable solution for the GaN-based VFDs in accordance with the cable length.