Research On Interior Permanent Magnet Synchronous Motor Sensorless Hybrid Control

The precise measurement of rotor position is critical for the normal startup and speed adjustment of permanent magnet synchronous motor(PMSM). Generally, the PMSM rotor position is detected by position sensors such as photoelectric encoder, magnetic encoder or rotating transformer. The position sensors ensure PMSM to startup and run reliably, but they have such shortcomings as high cost, occupying additional space, needing cable connection and corresponding circuit, low reliability. So, the PMSM applications are limited.To overcome the problems existing in postion sensors, there is a practical and objective need to develop the position sensorless method for PMSM control. At present, the PMSM position sensorless technologies are in primary research and development stage and only parts of them have come into production. There are still many theoretical and practical problems existing in position sensorless technologies before they are widely used. Furthermore, there is no a mature method which can realize PMSM full speed range sensorless control. In this background, this paper selected interior permanent magnet synchronous motor(IPMSM) as object, launched IPMSM position sensorless control research and did some exploration work in this area.The main contents and contributions of this paper are as the followings:(1) After analyzing the PMSM physical model, this paper derived the coordinate transformation principle and the IPMSM mathematical model, analyzed the IMPSM vector control system, discussed the maximum torque per ampere(MTPA) control, 0sdi= control, unit power factor control, flux field weakening control and maximum power output control methods deeply. The paper analyzed the 2-level inverter’s topology and working principle and investigated the SVPWM in details, derived the composing process of reference voltage and gave out the driving PWM wavrform of sector 1. This paper built the simulation model of IMPSM vector control and verified this simulation model is effecitve.(2) Based on model reference adaptive system(MRAS), this paper designed the IPMSM position estimation system for middle and high speed range. The paper selected IPMSM itself which doesn’t have the parameters to be estimated as reference model and selected mathematical model which has the parameters to be estimated as adjustable model. These two models have the same physical outputs and there is a deviation between these two models ouputs. This paper designed a proper adaptive algorithm by using the deviation of the two models outputs to control the adjustable model and let the adjustable model output to follow the reference model output. When the two models ouputs are same, the estimated position was obtained. This paper applied Popov superstability theory and proved in details the position estimation algorithm based on MRAS is stable. This paper built simulation model and verified the designed method is effective.(3) Based on high frequency rotating voltage injection method, this paper designed the IPMSM position estimation system for zero and low speed range. The high frequency rotating voltage was added into the basic frequency voltage vector, then these two vectors are injected into IPMSM together and the combined mathematical model was proposed. The basic mathematical model was separated from the combined mathematical model and used for vector control, and the high frequency mathematical model was separated and used for IPMSM rotor position estimation. The high frequency current corresponding is derived in details. One novel method for the high frequency current extraction and position estimation was proposed in this paper. This method first extracts the high frequency current response from the total current signals, then extracts the negative high frequency current from the whole high frequency current response and estimates the IPMSM rotor position information from it. This paper also discussed the IPMSM initial rotor position identification and derived the identification method. The paper designed proper low pass filter(LPF) and band pass filter(BPF), derived their mathematical model and transfer functions in detailes and analyzed their stabilities. This paper built simulation model, did a lot of debugging and verified the proposed methods’ effectiveness and feasibility.(4) Because the position estimation systems of zero & low speed and middle & high speed can’t realize the IPMSM full speed range sensorless operation independently, this paper proposed a hybrid control method which integrated high frequency rotating voltage injection method with MRAS method to realize the IPMSM full speed range sensorless control. In the speed transition region, there is a speed falling. The paper proposed a method which used variable weights weighted control and solved the problem, then realized smooth speed transition from low value range to high value range. This paper built simulation model and verified the proposed method effectiveness and feasibility.(5) Designed the hardware and software system, built the IPMSM position sensorless hybrid control platform, did a lot of hardware and software debugging and realized the sensorless hybrid control system running successfully, then gave out the experimental waveforms. This paper designed a stable, reliable and high efficiency switching power supply to provide DC voltage for the hardware and software system. The experimental results verified the switching power supply design is effective.