Novel Single-Stage Current Source Inverter: Extension to Low-Speed Region in Motor Drive Applications

In motor drive applications, single-stage current source inverters (CSIs) can manage only a limited speed range when the output voltage is greater than input voltage, due to the intrinsic boost capability. The classical solution adopted in low-speed region to control the input dc current, consists in the insertion of a prestage power converter. This article proposes a single-stage CSI that replaces the input inductance <inline-formula><tex-math notation="LaTeX">$L_{\text{dc}}$</tex-math></inline-formula> with coupled inductor. In this way, it is possible to add the needed time interval for the discharge of the magnetic energy of primary inductance <inline-formula><tex-math notation="LaTeX">$L_{m}$</tex-math></inline-formula> when the converter works in low-speed region or at standstill, extending the operating region of the converter. This solution allows to increase the efficiency of traditional CSIs for applications when the motor works most of the time in the high-speed region, thanks to the single-stage power conversion. Experimental and simulation results driving a permanent magnet synchronous machine are shown, confirming the validity of the proposed architecture.