Extended MTPA-FW Control Technique for PM Electrical Machines with CSI

This paper presents a new extended constant power region control model for interior permanent magnet synchronous machine (IPMSM) powered by a current source inverter (CSI). The IPMSM constant power region is usually obtained with voltage source inverter (VSI) employing flux weakening (FW) and maximum torque per volt (MTPV) control strategy when the voltage at the motor terminal exceed the available DC BUS voltage. This is due to the fact that VSI essentially operates as a step down converter. Even if these control strategy are well know in literature their implementation is always critical, specially when the MTPV is needed. As CSI is intrinsically a step up converter, it is possible to delay FW operation, provided that the voltage applied to the motor does not exceed the voltage rating of the power devices and the limits for the insulation system. So, in order to obtain a wide constant power region, an extend MTPA-FW is here proposed avoiding the need of MTPV and taking the advantage of the step-up intrinsic capability of the CSI.