The operation of a brushless permanent-magnet machine requires rotor-position information, which is used to control the frequency and phase angle of the machine's winding currents. Sensorless techniques for estimating rotor position from measurements of voltage and current have been the subject of intensive research. This paper reviews the state of the art in these sensorless techniques, which are broadly classified into three types: motional electromotive force, inductance, and flux linkage.

Review of position-sensorless operation of brushless permanent-magnet machines

An online parameter identification method and sensorless control using identified parameters were realized in surface and interior permanent-magnet synchronous motors (SPMSMs and IPMSMs, respectively). As this method does not use rotor position or velocity to identify motor parameters, the identified parameters are not affected by position estimation error under sensorless control. The proposed method can be applied to all kinds of synchronous motors. The effectiveness of the proposed method was verified by experiments in both SPMSMs and IPMSMs.

Sensorless control of permanent-magnet synchronous motors using online parameter identification based on system identification theory

Owing to the competitive advantages of cost reduction, system downsizing, and reliability enhancement, position sensorless control methods for permanent magnet synchronous machine drives have drawn increasing attention from academia to industrial applications. In this article, a survey of the major sensorless control techniques for a wide speed range from low to high speeds is presented. The different high frequency signal injection schemes, fundamental pulsewidth modulation excitation methods, and model-based sensorless control are displayed and compared, which is able to facilitate the sensorless control implementation.

Position Sensorless Permanent Magnet Synchronous Machine Drives—A Review

Sensorless control of a permanent-magnet synchronous machine at low and zero speed is based on the injection of an oscillating high-frequency carrier signal. A particular demodulation technique serves to eliminate the estimation error introduced by pulsewidth modulation delay and the nonlinear characteristics of the inverter. Before the drive is started, the initial rotor position and the magnet polarity are detected. The initialization is performed by injecting an AC carrier and two short current pulses in a sequence.

Acquisition of Position Error and Magnet Polarity for Sensorless Control of PM Synchronous Machines

In this paper, a new approach to sensorless speed control and initial rotor position estimation for interior permanent magnet synchronous motor (IPMSM) drive is presented. In rotating condition, speed and rotor position estimation of IPMSM drive are obtained through an extended Kalman filter (EKF) algorithm simply by measurement of the stator line voltages and currents. The main difficulty in developing an EKF for IPMSM is the complexity of the dynamic model expressed in the stationary coordinate system. This model is more complex than that of the surface PMSM, because of the asymmetry of the magnetic circuit. The starting procedure is a problem under sensorless drives, because no information is available before starting. The initial rotor position is estimated by a suitable sequence of voltage pulses intermittently applied to the stator windings at standstill and the measurement of the peak current values of the current leads to the rotor position. Magnetic saturation effect on the saliency is used to distinguish the north magnetic pole from the south. To illustrate our work, we present experimental results for an IPMSM obtained on a floating point digital signal processor (DSP) TMS320C31/40 MHz based control system.

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Implementation and experimental investigation of sensorless speed control with initial rotor position estimation for interior permanent magnet synchronous motor drive

This paper presents a method of estimating the initial rotor position of a surface permanent-magnet synchronous motor without a position sensor. The estimation is performed by using the nonlinear magnetization characteristics of the stator core caused by the magnet of the rotor. This method is based on the principle that the d-axis current value for the voltage vector applied to the motor under some conditions increases as the voltage vector generated from the inverter approaches the N pole of the rotor. During the estimation process, the rotor is practically at standstill. The experimental results show that the average of the estimation error is /spl plusmn/3.8 electrical degrees.

Sensorless initial rotor position estimation of surface permanent-magnet synchronous motor

This paper describes an initial rotor position estimation of surface permanent magnet synchronous motor without sensor. The estimation is performed by using the nonlinear magnetization characteristics of the stator core caused by the magnet of the rotor. The validity of the proposed estimation method is verified by the experiment.

I. Miki

Papers

Sensorless initial rotor position estimation of surface permanent-magnet synchronous motor

Sensorless initial rotor position estimation of surface permanent magnet synchronous motor