Research On Sensorless Control Of Ship Propulsive Permanent Magnet Synchronous Motor

With the rapid development of motor control technology, electric propulsion ship becomes more and more widely applied in the field of shipping. Permanent magnet synchronous motor becomes absolute dominant propulsion motor because of its small size, high efficiency and good performance. Therefore, the research of permanent magnet synchronous motor frequency converters is very meaningful for shipping career. PMSM frequency converters were selected as the research object, a method which can achieve sensorless vector control in the full speed range was proposed. Then a practical PMSM frequency converter was built based on DSP28335 in this paper. Later, the proposed scheme was carried out.Firstly, the mathematical model of PMSM in different coordinate systems was derived and the theory of vector control is introduced. The process of vector control based on the strategy of id=0 was analyzed, and the implementation process of the vector control modules in DSP was given in this paper. Secondly, the principle of back-EMF was presented in detail, to solve the shortages of the normal frequency converters with a sensor and reduce the difficulty of normal sensorless angle estimation under the condition of low speed, a scheme which can achieve sensorless PMSM vector control in the full speed range was introduced. Meanwhile, the implementation principles of rotor alignment, open-loop start and state-switch were recommended. Thirdly, Experimental platform hardware was provided and the principle of circuit was referred particularly. Then a practical motor parameter measurement method was given in detail. Finally, the structure and process of experimental platform software and the experimental results of the whole system were illuminated. This paper detailed the implementation process of back emf base on DSP.Experiments show that current, voltage and speed waveform of the system can keep good under various operating conditions. Meanwhile, the results of rotor alignment, open-loop start and back emf estimations are consistent with theoretical analysis. What said above shows the correctness of system designed and the feasibility of proposed strategy are proved.