Analysis of Position Estimation Error in Signal-Injection Sensorless Control Induced by Inverter dv/dt-Based Current Measurement Noise

This article discusses position estimation error in signal-injection sensorless control (SISC) induced by the current measurement noise of closed-loop Hall effect current sensor, when it is installed in an inverter system. For the first step, an equivalent circuit modeling of the current sensor in the inverter system is proposed, which includes the parasitic capacitances between the inverter and sensor. The presented modeling can explain how the high dv/dt of the inverter switching generates the leakage current through the parasitic capacitances, resulting in the measurement noise. The noise is sampled with analog to digital conversion, and it affects the rotor position estimation signal with the SISC algorithm. As a result, it is revealed that considerable position estimation error occurs from the noise. The experimental results are provided to verify the proposed theory and confirm the noise effects on the SISC performance.