A New Standstill Position Detection Technique for Nonsalient Permanent-Magnet Synchronous Motors Using the Magnetic Anisotropy Method

This paper describes a new method to estimate the standstill position of permanent-magnet synchronous motors (PMSMs). The method is based on the anisotropic properties of permanent magnets and is therefore referred to as a magnetic anisotropy method (MAM). It differs significantly from all standard standstill position detection methods previously presented in the literature. It is totally independent of saliency and saturation effects and can therefore be used in many types of PMSMs where the standard methods would fail. The paper fully explains the experimental results and briefly analyzes the physical phenomena behind the method

A new standstill position detection technique for non-salient PMSM's using the Magnetic Anisotropy Method (MAM)

Miroslav Markovic, Yves Perriard, Jan Persson

This paper describes a new method to estimate the standstill position of Permanent Magnet Synchronous Motors (PMSM). The method is based on the anisotropic properties of permanent magnets and is therefore referred to as Magnetic Anisotropy Method (MAM). The MAM method differs significantly from all standard standstill position detection methods previously presented in the literature. The proposed method is totally independent of saliency and saturation effects and can therefore be used in many types of PMSM where the standard methods would fail. The experimental results are fully explained and a brief analysis of the physical phenomena behind the method is also presented.

IEEE2005

Innovative standstill position detection combined with sensorless control of synchronous motors

Jan Persson

Sensorless control of PMSM's (Permanent Magnet Synchronous Motors) has occupied scientists for a long time. The result of this research is becoming widely accepted by the industry due to its low cost and reliability. However, the majority of today's motor drives are still equipped with some kind of position sensor. The reason is that sensorless control still have several limitations and is usually more complex than a traditional motor control. A new method to estimate the standstill position of PMSM's is presented. The method is based on the anisotropic properties of permanent magnets and is therefore referred to as MAM (Magnetic Anisotropy Method). The proposed method is independent of any ferromagnetic material and can therefore be used in many types of ironless PMSM's where standard methods fail. The MAM method is tested on a linear ironless motor, and measurement results from a "stripped" rotative motor without any supporting ferromagnetic material are also presented. Furthermore, it is shown in this thesis how Extended Kalman filters can be used to estimate the rotor position, and especially how the robustness and dynamic response of the overall control algorithm can be improved by using identification experiments and optimization algorithms. Some basic modelling of PMSM's are also presented. The modelling process is focused on techniques which are suitable for observers such as Extended Kalman filters. To show the versatility of the method, experimental results from two different motor types are presented. The first is a linear ironless motor while the second is a Hybrid Stepper Motor (HSM). Amongst other things it will be shown how the HSM can be transformed into a highly dynamic brushless DC motor without the drawbacks that is usually associated with HSM's. The linear ironless motor is used to demonstrate that it is possible to achieve good and robust position control without using a direct position sensor. Many different simulation and experimental results are presented for both the HSM and the linear ironless motor. The experiments are deliberately chosen to show both steady-state and dynamic operation of the proposed algorithm. The robustness of the overall algorithm is also analysed, considering unknown external load torque and motor parameters.

EPFL2005

Sensorless position estimation of linear voice-coil transducers

Christian Blanc, Yves Perriard, Jan Persson

In this paper, a method for sensorless position estimation of linear transducers at standstill is suggested. The method makes use of current pulses, which is a common sensorless starting technique for 3-phase synchronous motors. Most transducers possess however only one phase. In order to find a unique solution, the proposed method differs in some important aspects from the methods used in 3-phase systems. A general discussion of different inductance phenomena is presented. A combination of these phenomena makes it possible to find a unique position. The proposed method is verified using a linear voice-coil transducer with permanent magnets, which is taken from a hard-disk drive. The experimental results are presented and discussed.

2001

Innovative standstill position detection combined with sensorless control of synchronous motors

Jan Persson

EPFL2005