Investigation of Various Position Estimation Accuracy Issues in Pulse-Injection-based Sensorless Drives

For low speed sensorless drives of Surface mounted Permanent Magnet Synchronous Machine (SPMSM), pulse vectors are often injected into the drive to estimate the rotor position. There are many factors that could affect the accuracy of the estimated position such as inverter voltage error, cross-saturation effects and the presence of the speed dependent back electromotive force (EMF). This paper analyzes and evaluates the position estimation error caused by aforementioned factors with experimental results. Detailed quantitative results are given. Meanwhile the interaction between these factors is briefly studied.