Research On Low Cost Motor Drive Control System

In this thesis,two low cost permanent magnet synchronous motor(PMSM)drive systems are studied and analyzed in detail,which are the electrolytic capacitor-less six-switch topology and the novel four-switch topology with its DC-link connected to the motor's neutral point.Firstly,the vector control strategy and the predictive current control strategy are proposed for the electrolytic capacitor-less six-switch topology.The effectiveness of the proposed strategy is verified in simulation.The corresponding software and hardware are designed,and the experimental platform is built.The experimental results are in accordance with the theoretical analysis,which verify the feasibility of the proposed control strategies.Then,the principle,modulation method and control strategy of the novel four-switch topology are studied.A SVPWM modulation method capable of zero sequence voltage suppression is proposed,and the traditional vector control strategy,which includes speed outer loop and current inner loop,is applied to this topology by combining the characteristics of the novel four-switch topology.The mathematical model of permanent magnet synchronous motor with neutral line is derived,and the simulation model of the motor,which is built based on the mathematical model,is used for the control the vector control system of novel four-switch inverter.The results shows that the speed and torque of the motor can track the reference quickly,and the system has good dynamic and static characteristics.A new experimental platform is set up,and the experimental research is done on a permanent magnet synchronous motor with neutral line.The experimental results match the simulation results,which lays the foundation for the wide-spread and application of the novel four-switch topology in the field of electric motor's variable frequency control.