Compensation of Zero-Current Clamping Effects in High-Frequency-Signal-Injection-Based Sensorless PM Motor Drives

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.

Evaluation of methods for the operation of PMSM without position sensor

“…The back emf estimator was applied to the interior permanent magnet synchronous machine (IPMSM) with the concept of the extended back emf in [14]. For the signal injection method, several papers have focused on the effects of machine geometry and inverter nonlinearity, such as [2], [5], [7] and [15]. However, most papers consider the current controller as ideal and do not take effects of position estimation errors on the current controller into account.…”

Precise Torque Control in Flux-Weakening Operation of Surface-Mounted PM Motor with Magnetic Saliencies

“…High-frequency (HF) excitation signals have been proven to be effective in detecting d-and q-axes impedance differences [4][5][6][7][8][9][10][11]. However, this technique is viewed as particularly promising for the impedance detection of the HF signal excitation where a low-magnitude voltage and current are used at low speeds.…”

“…According to the design and/or operating conditions of the SMPM motor, s L ∆ may either be positive [7][8][9][10] or negative [4][5][6]. It is noticed from (2) that the inductance difference can play a significant role in the torque control and must be taken into account especially in a nonzero d-axis current condition.…”

“…It is natural that the torque of a SMPM motor can be controlled directly by controlling the q-axis current. Recently, industrial tests and other studies have shown that the d-and q-axes impedance difference due to magnetic saliencies has been observed to exist even in non-salient SMPM motors [4][5][6][7][8][9][10][11]. This is due to the fact that the stator core along the main flux path is highly saturated.…”

Pulsating Signal Injection-Based Axis Switching Sensorless Control of Surface-Mounted Permanent-Magnet Motors for Minimal Zero-Current Clamping Effects

“…However, the HF signal forces the phase current to have multiple zero-crossings when the fundamental phase current is close to zero. The zero-current-clamping (ZCC) effect that is relevant to multiple zero-crossings causes disturbances that significantly affect the quality of the position estimate [4]- [6]. With the presence of the ZCC effect, the HF signal injection-based sensorless controllers are prone to position error ripples.…”