Standstill Determination of PM Flux Linkage Based on Minimum Saliency Tracking for PM-SyR Machines

Permanent Magnet assisted Synchronous Reluctance (PM-SyR) motors often present relevant magnetic saturation, especially if overload capabilities want to be exploited. The knowledge of current-to-flux relationship is mandatory for proper motor control, and it becomes even more critical in case of sensorless applications. Reliable self-commissioning tests have been recently developed for Synchronous Reluctance (SyR) motors without producing any rotor movements. This procedure can be extended to PM-SyR motors, but, being at standstill, it does not retrieve the flux contribution related to the PMs. This paper integrates the identification of the flux characteristic including a novel test for estimating the PM flux, obtaining the complete magnetic characteristic of PM-SyR motors. The global identification session is performed at standstill and without a position transducer, while the load can either be connected or not. These conditions are considered the most demanding for selfcommissioning tests. The machine is first excited with a proper sequence of bipolar high voltage pulses to determine its current dependent flux component. Then, the PM flux linkage is retrieved at standstill by evaluating the local saliency along the negative q axis. The proposed method was experimentally verified on a 10 kW PM-SyR motor prototype, with an estimation error of 0.42%.