Self identification and compensation of position sensor error in interior permanent magnet synchronous machine (IPMSM) drives

This paper presents a nonintrusive and online method to identify and compensate for position sensor error in IPMSM drives. Each IPM motor has a distinct short-circuit current vs. speed characteristic, which is solely defined by its machine design. By controlling the IPM motor to operate at its steady-state short-circuit current during coasting down, all phases of the IPM motor can be safely short circuited using the inverter without introducing any current transients. Then the d-q axes currents measured by the inverter are compared with the known short-circuit characteristic of the IPM motor. Any discrepancy in q-axis current can be used to identify and quantify the position sensor error.