Study On Constant Torque Range Extending Speed Control System Of The Open-End Winding PMSM With Y/? Winding Changeover Technique

As a new type of motor,Permanent Magnet Synchronous Motor(PMSM)has been greatly developed and applied because of its simple control,high precision,high reliability,high efficiency,small size and so on.The vector control can realize decoupling control of torque and flux linkage,which is mostly used in the applications of variable frequency speed regulation of high performance.When PMSM uses the vector control,we defined the speed range which is below the motor turning speed as the constant torque area.In this area,the maximum output torque of the motor remains unchanged.But when the speed is above the turning speed,with the limit of the bus voltage,terminal voltage of the motor cannot continue to increase,therefore the maximum output torque of the motor will decline with the increase of the speed.It is difficult to satisfy the driving requirements of large torque output at high speed.Therefore,it is important to study the technology and methods to extending the constant torque range,which is of great significance to improve the power density of the motor and meet the driving requirements in higher-speed operation.In this paper,from two aspects of increasing the motor terminal voltage and reducing the electromotive force(EMF)of the motor,the method and the disadvantages of the existing extended PMSM speed regulation range was presented.In terms of present technology shortcoming,a new method to extending the constant torque range,named Y/? winding changeover technology,was presented and explored.The analysis on the mathematical model of PMSM was presented.The inverter switching states and the basic voltage vector was explored while the stator winding of the machine was under the condition of Y-connected or ?-connected.What's more,the theory that Y/A winding changeover technology can enlarge the motor constant torque area was demonstrated.Moreover the control logic of Y/?transformation was analyzed and embedded into the vector-control system so as to extend the constant torque range of the motor.The simulation model of the control system was established on the Matlab/Simulink,and the simulation results showed that Y/?transformation can extend the constant torque speed range of PMSM.The hardware system of the speed control system with TMS320F2812 as the control core was designed,including the current sampling circuit,voltage sampling circuit,IPM driving and protecting circuit,Y/? transforming circuit etc.Furthermore,C program for the drive system was programmed and debugged.Through the improvement of the system,the problem of the motor transient current was solved.And a smooth transition was realized from Y-connected to ?-connected or vice versa.The constant torque range was extended by the times of(?),significantly improving the motor power density and proving the effectiveness and excellence of new technology.