Improved MRAS-based Speed Sensorless Control of PMSM Considering Inverter Nonlinearity

Abstract:
This article analyzes the shortcomings of the speed sensorless control strategy based on traditional MRAS methods. It does not take into account the voltage difference caused by the nonlinear characteristics of the inverter and the current difference caused by sampling time delay. This leads to errors in speed and angle estimation. To address this issue, this article analyzes the sources of nonlinear voltage errors in inverters, derives voltage compensation formulas, and applies them to the MRAS model. In addition, to address the issue of sampling delay, this paper proposes an improved MRAS structure that ensures consistent sampling time for voltage and current. Moreover, voltage feedforward is added in the speed estimation process to compensate for the impact of sampling current lag. This article measured some nonlinear parameters of the inverter through experiments, and finally verified the feasibility of this method through simulation.