Sensorless Control Of The Brushless Synchronous Machine In The Whole Start Process

Variable Frequency(VF) AC power system has been the most attractive candidate in the large civilaircraft power system, and the integrated starter/generator which is the important character in VF ACpower system based on the brushless synchronous motor(BSSM) is also highly appreciated. TheBSSM using the vector control strategy for engine cranking need to get the accurate position signal,however, the traditional mechanical position sensor with several drawbacks is not suitable of theproposed machine used in the starting system. Therefore, the sensorless control method has been theimportant trend in the starting control field of the BSSM.The difficulty of the sensorless control technology is focus on the rotor position detection at zeroand low speed period. Since the high frequency signal injection method may cause the error of thepole location estimation at the zero speed, and correction method should be added to the proposedsensorless control method. Due to the special construction of BSSM, the conventional initial rotorposition detection method is not suitable for BSSM. Therefore, a novel method which combines thehigh frequency rotating voltage injection with the induced electromotive force polarity judgment isproposed to detect the initial rotor position in this thesis. And, the high frequency rotating voltageinjection method is also used at the zero and low speed period for the rotor position detection, and therotor position estimation method based on back-emf is used at high speed period. Hence, the hybridsensorless control strategy from low speed to high speed was devised in order to achieve thesensorless starting of BSSM in the whole start process.The thesis firstly introduces the structure and mathematical models of BSSM, then, the sensorlessstarting control method including initial rotor position detection method based on the inducedelectromotive force polarity judgment, rotor position detection at low and high speed period is givenin detail, and switching control method from low speed to high speed is also proposed. Simulationmodel of the sensorless starting control system is built for verifying the validity of the proposedcontrol strategy by Matlab. Finally, the prototype platform of the sensorless starting control system isdesigned based on the DSP and CPLD. The position detection precision of the proposed sensorlesscontrol method has been confirmed by the experiment results, and the BSSM could start upsuccessfully.