Impacts of Cross-Saturation on Sensorless Control of Synchronous Machines using Alternating Signal Injection

Abstract:
Signal injection is a well-known technique to identify the actual rotor position of an AC machine in lowspeed and standstill using the saliency of the machine. It enables a field-oriented control without a position sensor. This paper discusses the disturbing influence of magnetic cross-saturation on the estimated rotor position of an interior permanent magnet synchronous machine and presents two possibilities to compensate the errors caused by this influence. Simulation models are used to demonstrate and analyze the position deviation caused by the saturation effects and to evaluate the effectiveness of the proposed compensation methods. Several measurements on a machine testbench validate the simulation results.