Research On Permanent Magnet Synchronous Motor Drive System With Long Cable

The difference between a motor drive system with a long cable and a conventional motor drive system is that the inverter and the motor in the motor drive system with long cable are connected by long cable rather than directly connected.In some industrial applications,such as oil drilling,steel rolling plant,marine survey and so on,there is a long motor cable between the inverter and motor,which makes the motor drive system with long cable is widely used in these industries.However,due to the presence of long cables in the motor drive system with long cable,the position signal of the motor can not be obtained directly through the position sensor on the one hand.On the other hand,it is difficult to identify the motor position signal by the voltage and current of the motor.Meanwhile,due to the existence of long cable,the high change rate of the inverter output voltage may cause overvoltage at the terminal of motor according to the long transmission line theory.Overvoltage will lead to the failure of the motor and cable insulation.This main work which completed for the study of the permanent magnet synchronous motor(PMSM)drive system with long cable divides into four parts as follows:Firstly,the mathematical model of PMSM is introduced.The CPS-SPWM technology of cascade multi-level inverter and its selection of phase shift angle are analyzed.The vector control algorithm is described and the PMSM drive control system model with long cable is established.Secondly,the method of detecting the position signal of the motor in the motor drive system with long cable is introduced.The transmission mode of the position signal,power carrier communication technology,is introduced.Aiming at the delay in the transmission of the position signal,a method of compensating the position signal is proposed and verified by the simulation experiment.Then,the mathematical model of “inverter-long cable-motor” is established,and the cause of overvoltage phenomenon is analyzed by the long transmission line theory.In this paper,the method of overvoltage suppression is introduced.Aiming at the possible problem of resistive heat dissipation and energy dissipation of passive damping filter,an LCL active damping algorithm for motor vector control is proposed.Finally,the hardware circuit design and control system programming of the motor drive system with long cable based on the cascaded five-level inverter is completed.Experiments on the experimental system of PMSM drive system with long cable are carried out to verify the feasibility of the proposed motor drive system with long cable.