Flatness based sensorless control of PMSM using test current signal injection and compensation for differential cross-coupling inductances at standstill and low speed range

Abstract

This paper presents a novel flatness based twodegree-of-freedom (2DoF) sensorless control scheme for PMSM at standstill and for low speed range using test current signal injection in the estimated d-axis of the field oriented dqcoordinate system. Asymmetrical winding and saturation might cause the occurrence of differential cross-coupling inductances and as a result the estimated rotor position deviates from the real value. The differential cross-coupling inductances have to be compensated for to overcome this problem. For that a flatness based dynamic feed-forward control is proposed. The control error due to model uncertainties is minimized using a controller that fulfills the internal model principle. The control signal of the high frequency controller in the q-axis is demodulated and afterwards used as the input signal of a tracking-observer to estimate the rotor position.

HF Test Current Injection-Based Self-Sensing Control of PMSM for Low- and Zero-Speed Range Using Two-Degree-of-Freedom Current Control

“…In contrast to the fundamental reference values, the test current reference trajectory is known beforehand in an analytical way as to (18). Using the concept of differential flatness [25], the test current precontrol can be found in a very elegant way [16]. The HF model (3), which represents the behavior of the machine in case of injecting an HF test signal, is used to derive the test signal precontrol.…”

“…In transient operation, however, interference of fundamental and HF components might occur, which deteriorates self-sensing position estimation. To overcome this limitation, the twodegree-of-freedom current control scheme proposed in [16] is used. The (fundamental frequency) reference response is set by a model-based dynamic feedforward control, which has been 0093-9994 © 2014 IEEE.…”

“…Thus, a high-performance position error signal is provided without the need for additional filtering. The innovation in this paper is that the PI+resonant controller used in [16] is modified that it directly provides a dc error signal without the need for further demodulation and delay compensation (due to the discrete-time implementation of the control algorithm). Moreover, it is analytically shown that, in contrast to voltage injection-based methods, only precise knowledge of the inductance m HF qd (i d , i q , γ) is needed for compensation of secondary saliencies in the case of inductance saliency-based selfsensing control and r HF qd (i d , i q , γ) in the resistance-based case, respectively.…”

“…Moreover, it is analytically shown that, in contrast to voltage injection-based methods, only precise knowledge of the inductance m HF qd (i d , i q , γ) is needed for compensation of secondary saliencies in the case of inductance saliency-based selfsensing control and r HF qd (i d , i q , γ) in the resistance-based case, respectively. In order to further enhance control performance, a flatness-based test signal precontrol, which inherently includes compensation for secondary saliencies, is used, as proposed in [16]. The error signal for self-sensing operation is provided by evaluation of the HF actuating signals of the tracking controller.…”

“…The error signal for self-sensing operation is provided by evaluation of the HF actuating signals of the tracking controller. A speed estimate, by evaluating the back electromotive force (EMF) information of the machine, is used to improve dynamic behavior [16]. The effectiveness of the proposed novel selfsensing control method is validated by test bench measurement results for an interior PMSM (IPMSM), which shows strong saturation effects and higher harmonic saliencies.…”