Research On Brushless Doubly-fed Hybrid Poles Permanent Magnet Motor And Its Speed Regulating System

Brushless Doubly-fed Hybrid Poles Permanent Magnet Motor is a new type of Hybrid Excitation permanent magnet machine. Its control winding can regulate dual directional magnetic field, namely strengthening and weakening magnetic field. This great capability in regulating main magnetic field guarantees the wide speed range of the machine. The vector control strategy and excitation regulating capability of this novel machine are studied in detail. The speed regulating system that is use for a model machine manufactured by research group is designed and the relative experiments are also made in the paper.Based on the detailed introduction of structure, principles and magnetic characteristics of the machine, its mathematical model in the d-q synchronous reference frame is built in this paper. The vector control analysis about this machine is made by using the d-q model, and the vector control strategy which is suitable for this kind of machine are presented:vector control under conditions that direct axis current of power winding is equal to 0, vector control under conditions that power factor of power winding is equal to 1, and vector control based on stator magnetic field. All these vector control strategies are elaborated in the paper. The research results show that the machine which adopts the above-mentioned vector control methods has the better control performance of regulating speed and torque than general PMSM.The paper carries on the finite element analysis of the Brushless Doubly-fed Hybrid Poles Permanent Magnet Motor at its motoring state by making use of the electric-magnetic field calculating programs. The analysis results show that:When the machine runs as a motor, and whether the machine runs with load or not, its capability of excitation regulating can not meet the demand of performance. There are two reasons for this phenomenon:the width of stator magnet yoke is so small that the magnetic circuit is easily saturated, and the reactance of quadrature-axis is so large that stator voltage is increased. A new motor is designed by taking these two factors into consideration, and it has excellent performance of the field-weaking capability as well as of speed range.The governing system of the existing machine is designed based on the vector control method under the condition that direct axis current of power winding is equal to 0. DSP-TMS320LF2407 is used as the processor to realize all-digital processing of vector control method in this system. Finally, the experiment platform is built and the relative experiments about governing system are also made in the research. Experiment results demonstrate that the designed system is effective.