Power factor compensation for CSC-fed PMSM drive using d-axis stator current control

In this paper, an input power factor compensation method is proposed for a high-power pulse-width-modulated Current-Source-Converter (CSC)-fed Permanent Magnet Synchronous Motor (PMSM) drive system. The proposed method is based on controlling the d-axis stator current component in the field oriented control scheme of the drive system. The CSC-fed PMSM drive system and its field oriented control scheme are first introduced. Then, the relationships between the machine side, dc-link, and the line side are investigated. Based on the analysis, a new d-axis stator current control scheme that can ensure unity input power factor for the operating speed range is proposed. The main feature of the proposed scheme is to compensate the line-side power factor without the need for modulation index control in either the rectifier or the inverter. Therefore, offline Selective Harmonic Elimination (SHE) modulation schemes can be implemented on both line and machine side converters to minimize the total harmonic distortion. This results in reduced switching frequency and reduced switching losses. Simulation results for a 2.44MW medium-voltage system and experimental results from a low-voltage 6.5kW IPM motor drive are provided to verify the effectiveness of the proposed compensation method.