Two management strategies to deal with PWM inverter´s control variable saturation

Conventional PM (permanent magnet) synchronous motor drives are supplied by PWM (pulse width modulation) inverters. The limitation of the inverter´s control variables has two important consequences: a reduction of the average torque; and important current and voltage ripples. In this paper, two strategies are proposed to deal with this problem for a two-current loop structure. The first one allows the use of the maximum available voltage without current distortions in case of successive limitations. The second one is an attempt to maintain a set of balanced voltages at the machine terminals to reduce the torque ripples in case of double limitations