Wide speed range operation of PMSM using an open winding and a dual inverter drive with a floating bridge

A controller is described for a 3-phase PMSM that uses an open winding and a dual inverter drive with a floating bridge. The drive has a voltage boosting function that: extends the high-speed range of the PMSM; operates the main inverter bridge at unity power factor above the base speed; compensates for battery voltage fluctuations. The main features of the controller presented are: (a) coordinated control of the two inverters to supply the motor with the demand voltage and frequency; (b) the floating bridge dc capacitor voltage can be regulated and its output voltage used to boost the machine terminal voltage when required; (c) the motor speed is controlled via torque control is independent of the floating bridge dc voltage control. Simulation results are used to clarify the motor-drive characteristics in the speed range extension region. Experimental results show that a significant speed range extension is achievable even when using a PMSM with a very low inductance.