Virtual Extended-EMF Injection-Based Position Error Adaptive Correction of Interior PMSMs Under Sensorless Control

To eliminate the influence of parameter mismatches and inverter nonlinearity on fundamental model-based sensorless control, a novel virtual extended-EMF (VEEMF) injection-based position error adaptive correction method is proposed for interior permanent magnet synchronous machines (PMSMs) in this article. Specifically, when square wave VEEMF is injected into the position observer, it is found that the position error caused by parameter mismatches and inverter nonlinearity maintains constant and is only related to the ratio of q- and d-axes voltage fluctuations. As a result, the position estimation error can be corrected by adaptively minimizing the ratio of q- and d-axes voltage fluctuations. Therefore, the proposed position error correction method is independent of unknown parameters, i.e., the total position errors caused by different factors can be collectively corrected. Experimental results verify the effectiveness of the proposed method.