Investigation Of Sensorless Control For PMSM Based On The Concept Of Power Electronic System Integration

Power electronic system integration has been attracting very attention in the power electronic field with two senses. The one is the power electronic sub-system integration, the other is the practical power electronic applied system integration. As a kind of integrated power electronic applied system, the integrated power electronic drive system with high performance not only needs integrated power electronic modules, but also needs a sensor-integrated module which is capable of detecting motor voltages and currents, rotor position and speed, fluxes and torque. The rotor position/speed sensing in the whole speed region is the most difficult task in the sensor module. Thus, sensorless control techniques and sensor-integrated module were investigated in this dissertation from the viewpoint of power electronic system integration.Firstly, three kind of high frequency signal injection methods, i.e. rotating high frequency voltage signal injection, rotating high frequency current signal injection and fluctuating high frequency voltage signal injection, were discussed in detail. The basic principles of rotor position self-sensing system using these high frequency signal injection methods were presented. Comparative study of simulation shows that the rotating high frequency current signal injection needs a special current regulator and has limited dynamic response, so it is less used;the fluctuating high frequency voltage signal injection method possesses simpler scheme configuration and better speed-adjustable performance both in static and dynamic, but the scheme is difficult to be regulated;the rotating high frequency voltage signal injection method is more complicated ,but is easier to be implemented, so it is used more widely. The high frequency signal injection method is not sensitive to parameter variations and has good tracking accuracy in the low speed region including zero-speed, so it is suitable for low speed operation.Secondly, based on the detailed discussion of the rotor position self-sensing method using the model reference adaptive system, a hybrid rotor position self-sensing approach was investigated in this dissertation by combining the high frequency signal injection method and Model Reference Adaptive System(MRAS) method. The hybrid method is capable of precisely estimating the rotor position and speed at the low speed with high frequency voltage signal injection and possessing fast dynamic response at the high speed with model reference adaptive system. Therefore the proposed method is suitable for the sensorless vector control of a PM synchronous motor in a wide speed range, including zero-speed.Thirdly, the concept of the sensor-integrated module was presented for the first time. The hardware structure and inside functions of the conceptive sensor module were designed. By detecting motor voltages and currents and using some signal processing techniques to estimate rotor position/speed, flux and torque, the sensor-integrated modulecan estimate all feedback quantities needed by closed-loop control to implement high accuracy and high performance position and speed control. The conceptive sensor module can be combined with other integrated power electronic modules to form an applied high performance power electronic drive system conveniently ,compactly and extendably.Finally, based on the conceptive sensor-integrated module, a sensorless vector control experiment system for an inset-type PM synchronous motor was developed. Three kind of sensorless control schemes respectively based on high frequency voltage signal injection, model reference adaptive system and the hybrid method were investigated. The experimental results indicates that the hybrid rotor position self-sensing approach merges the advantages of both methods and possesses acceptable static and dynamic performance in the whole speed region.