No abstract

No abstract

No abstract

This paper proposes an online compensation strategy for the unwanted disturbance voltage resulting from the zerocurrent clamping effect for high-frequency-signal-injection-based sensorless control schemes. We derive an analytical model that reveals intrinsic characteristics of the zero clamping effect for highfrequency signal injection. The model in this form is subsequently incorporated into the development of a specialized offline commissioning test to find motor inductances and a voltage distortion factor. From the sensitivity analysis of the effect on magnetic saturation, we confirm that the compensation error due to saturation has little negative impact on the proposed compensation method. The compensation result leads to an accurate position estimate in the zero-current clamping region. The proposed scheme does not rely on a complicated lookup table. Experiments demonstrate the superiority of the proposed method in suppressing the voltage distortions caused by the zero-current clamping effect.Index Terms-Analytical model, offline commissioning test, online compensation strategy for the unwanted disturbance voltage, zero-current clamping effect for high-frequency-signalinjection-based sensorless control.

In this paper, we propose an injection-based axis switching (IAS) sensorless control scheme using a pulsating highfrequency (HF) signal to minimize position detection error and velocity estimation ripple resulting from the zero-currentclamping (ZCC) effect for surface-mounted permanent-magnet motors. When a pulsating carrier-signal voltage is injected in an estimated synchronous frame, the envelope of the resulting HF current measured in the stationary reference frame follows an amplitude-modulated pattern. Using this information, the IAS technique allows one to avoid multiple zero crossings of HF currents by adjusting the current phase angle according to the load condition. At no-load condition, the pulsating voltage is injected only on the d-axis, while the d-axis current is controlled to a certain nonzero value. Under a load condition, the injection voltage is switched to the q-axis, while the d-axis current drops back to zero. Thus, the proposed sensorless control enforces a much better estimation performance in a region of ZCC without a predefined offline commissioning test than the standard pulsating injection scheme. Experiments illustrate the effectiveness of the proposed method in suppressing the estimation error caused by the ZCC disturbance and in extending the system bandwidth.Index Terms-Estimated position error and velocity ripple, injection-based axis switching (IAS) sensorless control, pulsating high-frequency (HF) signal injection, zero-current-clamping (ZCC) effect.