Model Reference Adaptive System Based Adaptive Speed Estimation for Sensorless Vector Control with Initial Rotor Position Estimation for Interior Permanent Magnet Synchronous Motor Drive

Abstract

The rotor position/speed sensor used to control the permanent magnet synchronous motor drive has increased size and cost, decreased reliability, and a need for shaft extension and mounting arrangements. Sensorless control is currently adopted in many industrial applications for reasons of robustness, cost, cabling, and reliability. In order to achieve correct operation from zero speed startup of a sensorless salient-pole permanent-magnet synchronous motor (the interior permanent magnet synchronous motor), the initial rotor position of the motor is required. A model reference adaptive system technique has been used for speed estimation in sensorless speed control of the interior permanent magnet synchronous motor with space vector pulse width modulation. This article presents a new approach to improved initial rotor position detection of an interior permanent magnet synchronous motor. The method uses a suitable sequence of short and long time voltage pulses applied to the stator coil at standstill. Short time voltage pulses are applied to the motor terminals to detect the initial rotor position. Long time voltage pulses are used for detection of the magnet polarity based on the effect of saturation. The measurement of the current peaks values gives information about the initial rotor position. Simulation and experimental results are presented and show the validity of the proposed method, which is capable of reliable initial rotor position detection, including the polarity of the magnet at standstill. The error initial rotor position detection is less than 5 mechanical degrees. Experimental results are presented for an interior permanent magnet synchronous motor obtained on a fixed-point digital signal processor based control system. Experimental results show that the modeled reference adaptive system technique speed estimation provides high-performance sensorless control and initial rotor position estimation algorithms of the interior permanent magnet synchronous motor drive.