Position Sensorless Control Of Permanent Magnet Synchronous Motor Based On High-frequency Signal Injection

Permanent magnet synchronous motor (PMSM) has been widely used in high performance drive applications for its advantages, such as compactness, high efficiency, reliability and suitability to environment. Sensorless control of PMSM has been a hot research topic of motor control technology, which has the advantages of low cost and high reliability. Sensorless control technology has a great significance in some special operation field, such as high speed motor, micro-motor, submarine robotand home appliances. This paper presents the principles and implementations of PMSM sensorless control based on high-frequency Signal injection, especially on the low speed and zero speed sensorlesss control.Firstly, the state of the art review of PMSM sensorless control has been given based on many national and international references. It describes the advantages of sensorless control technology, application in industrial field and development trend. The analysis and comparison between sensorlees methods suitable for zero and low speed and suitable for high speed of PMSM sensorless methods have been introduced.Secondly,based on the mathematical model of high frequency injection for salient pole PMSM, A high frequency signal injection method is used to estimate the rotor position of PMSM. The carrier signal excitations for single saliency and multiple saliencies are analyzed respectively. Saturation effect is considered for the rotor position estimation. The mathematical model including saturation is built for compensating the effect of saturation. At the mean time, the maximum torque per current control is discussed. The comparison between maximum torque per current trajectory with saturation and without saturation is presented.Then, the rotor position estimation method based on Luenberger observer is discussed in detail. The rotor position estimation based on multiple saliencies tracking is presented. The modeling, measurement and analysis of the multiple saliencies are discussed and decoupling observers of multiple saliencies are designed for compensating their effects on position estimation. At the same time, Some improvements have been used to the observer for high performance. The torque command is the feedforward command to the Luenberger observer to obtain zero-phase lag position estimation. An extra integrator is introduced to the observer controller for the load disturbance rejection. Because the fundamental model and other possible error sources are ignored in the high frequency injection method, some possible error sources of rotor position estimation have been analyzed.Next, a method to estimate the initial rotor position and magnet polarity for an interior permanent magnet synchronous machine (IPMSM) based on carrier frequency injection has been presented. The method uses magnetic saturation model based second harmonicsof carrier signal to identify the polarity of magnetic field.Finally, An experiment setup for permanent magnet synchronous motor sensorless control implementation based on high frequency signal injection has been designed. The multiple saliencies tracking method presented in this paper is tested on an IPMSM. The system is a fully digital control system based on DSP. The experiments results show that high frequency injection can estimate the rotor position of PMSM at low speed and zero speed. The position estimation error has been reduced by compensating the effect of the multiple saliencies to the rotor position. This method is insensitive to motor parameters and especially suitable to interior permanent magnet synchronous motor.