Research On Control Technology Of Permanent Magnet Motor With Dual Contra-rotating Rotors

When the permanent magnet motor with dual contra-rotating rotors is used as a power source for the underwater vehicle or the propeller aircraft,it is necessary to prevent the controlled plant rolling in the actual application due to unbalance loads.So,the synchronous operation of the two rotors is guaranteed for the stable system under all conditions.In the paper,the permanent magnet motor with dual contra-rotating rotors is taken into account as the research object,and the control strategy of the two rotors under unbalanced loads is studied for the purpose of improving the synchronous operation performance of the both rotors under different conditions.The control strategies for the synchronous operation of the both rotors are discussed,including the field oriented control strategy,the sliding mode control strategy,the disturbance observer technology and the combined control technology.The paper mainly analyzes from the following aspects:The structure of the permanent magnet motor with dual contra-rotating rotors and its operation principle are different from those of the traditional permanent magnet synchronous motor.Based on the analysis of operation principle,the mathematical models of the permanent magnet motor with dual contra-rotating rotors are established,including voltage equation,current equation,electromagnetic torque equation and its motion equation.The three kinds of magnetic circuit situation will happen during the motor operation,and the three kinds of magnetic circuit situation are simulated.Then,the equivalent magnetic circuit is modeled for these three situations,which can provide the theoretical basis for the synchronous control of the motor under unbalanced loads condition.Based on master-slave control control,a control method using the magnetic field orientation control strategy is proposed for the synchronous operation of the motor,which can ensure the both rotors rotate synchronously under unbalance loads condition.Based on the mathematical model of the permanent magnet motor with dual contra-rotating rotors,the feasibility of ensuring the dual rotors synchronous rotating control method is analyzed and its solution is proposed.The solution is to select the motor with higher load as the main motor and reorient the rotor magnetic field,whic h can ensure the both rotors rotate synchronously.In order to correctly select the main motor,a method for position detection of the rotor based on the resolvers is proposed.The position detection technology is an effective solution for the control syst em to correctly select the motor with higher load as the master motor.In order to improve the reliability of the motor system,the speed controller is proposed and designed by using the sliding mode control strategy.It is theoretically analyzed that the sliding mode control technology is completely feasible to improve the system reliability.For the purpose of reducing the chattering phenomenon of the controlled system,a boundary layer technique is applied to the exponential approaching law and to improve the approach rate in the speed controller system.The stability analysis of the improved sliding mode control system is carried out.The simulation results show that the permanent magnet motor with dual contra-rotating rotors control system based on sliding mode control technology can not only ensure the synchronous rotation of the both rotors,but also has good dynamic performance and robust performance.The effects and damages of the disturbances on the motor control system which consist of internal disturbance and external disturbance are analyzed.A scheme based on the disturbance observer to estimate the system disturbance is proposed.In order to reduce the influence of the system disturbance,a composite control strategy based on the disturbance observer and speed controller is proposed to control the speed of the motor.The motor system is analyzed by using the Lyapunov stability criterion.The improved speed controller and the disturbance observer are used to control the motor control system.The disturbance factors are feedback as a compensation part and input into the speed controller,which can improve the robust performance of the system.The simulation results shows that the motor system can quickly follow the given speed input and the both rotors can run in a synchronous way under the condition of unbalanced loads.