Compensating the influence of the stator resistor and inverter nonlinearities in signal-injection based sensorless strategies

Among the sensorless position estimation methods in electrical machines drives, the injection of voltage test pulses is a promising strategy. Several papers are studying and applying this strategy, in particular for permanent magnet synchronous machine (PMSM) at low speed or standstill. Recently, an adaptive test pulses sequence reducing the current distortions has been proposed. However, the test pulses can be influenced by the voltage drops such as across stator resistor and semiconductor switches. By neglecting these voltage drops, the distortion in the current samples can not be fully reduced. In this paper, we improve the adaptive test pulses strategy by estimating and compensating the resistive drops. We also discuss the impact of the inverter nonlinearities. Finally, we present experimental results on a PMSM.