New PWM inverter modelling method applied to the design of a current controller for three-phase high performance PM synchronous actuator

Control systems of PWM inverter fed PM synchronous motor usually include analog current loops which control the motor currents according to reference values generated by a main controller. For high speed actuators such loops must have a high open loop gain up to relatively high frequencies. If, in order to limit commutation losses, the inverter PWM frequency cannot be increased; accordingly, the current loop gain may not be negligible at half of the modulation frequency. The stability analysis of these loops requires then an adequate modelling of the PWM inverter. The authors have recently presented such a model for a single phase system. The paper extends this model to three phase systems and presents its application to the synthesis of the current loops of a high speed motor designed for aeronautics applications (in the frame of an EEC Brite Euram program). Experiments show accurate current control even for extreme acceleration condition (0 to 13000 RPM in 30 ms)