Study On The Drive And Control Technology Of Dual Three-phase Permanent Magnet Synchronous Motor

In some situations which are critical for the demand of power grade, speed adjusting performance and reliability, the traditional three-phase asynchronous motor can not meet the actual demands. However, multi-phase permanent-magnet synchronous motor (PMSM), which has many advantages of high power density, small torque ripple and high reliability, has a braod space for futher development. In this paper, taking the dual three-phase PMSM as the study object, multi-dimensional space vector modulation technique, vector control and direct torque control techniques have been studied, and then go to a study on a new circuit topology of multi-motor driving with a single inveter.Firstly, Vector space decoupling mathematical model of dual three-phase PMSM is established. Since only the α-β reference voltage vector is controlled by using the traditional SVPWM technique, neglecting the x-y reference voltage vector, which results to a big current harmonic production, increasing the copper loss and having a bad influence on control performance. On the basis of the idea of multi-dimensional space vector control, the four biggest vectors SVPWM (FB-SVPWM) technique, and the two biggest and two second biggest vectors SVPWM (TBTSB-SVPWM) technique have been studied in this paper. Both of them can control the α-β reference voltage vector and the x-y reference voltage vector simutaneously. Simulation results show that these two kinds of SVPWM techniques can not only improve the DC-link utilization, but also can eliminate the5th and7th harmonics, making the output voltage a pure sinusoidal waveform.Secondly, multi-motor connected in series driving and control technique of the dual three-phase PMSM has been studied. With a proper phase transformation rule, the stator winding of two motors are connected in series, and they are controlled by a single six-phase voltage source inverter supply. In order to realize independent control, a double-modulator SVPWM technique has been adopted in this paper, which ensures the output phase-voltage only contain two kinds of fundamental components required by two motors, realizing the decoupling control. Simulation results indicate that there is no influence on the other motor’s operation when change the speed or load of any one of the two motors. The theoretical analysis is consistent with simulation results and the correctness and feasibility are verified.