I-f Control with Zero -axis Current Operation for Surface Mounted Permanent Magnet Synchronous Machine Drives

This paper deals with I-f control of surface mounted permanent magnet synchronous machine (SPMSM) drives. Conventional open-loop I-f control is poorly damped and can only operate stably with positive d-axis current. An I-f control with a new current compensation loop is proposed to achieve stable id=0 operation in this work. The proposed method can be used for startup with a seamless transition to sensorless field-oriented-control (FOC), since id=0 operation is already achieved before switching to FOC. In addition, as the I-f control can now maintain stable id=0 operation against 100% rated load step disturbance from 10% to 100% rated speed, it could be a standalone control scheme for wide-speed-range operations. The proposed method is supported with detailed stability analysis and its performance is verified experimentally on a 2.7-kW SPMSM drive platform.