Torque Equalization Control Of Double Motor Gear Synchronous Drive System

The dual-motor gear synchronous drive system can increase the output torque on the basis of reducing the volume of the system, which is widely used in the industrial field of high power and low speed. However, the gear drive shaft is rigid, and the two motors are forced to synchronizeand the output torque is coupled with each other. Because of the difference of the rigidity of the motor shaft, the difference of the lubrication of gears and the unknown deviation of the gear mesh, the load distribution is easily caused.In this paper, Double permanent magnet synchronous motorGear drived system as the research object,the transmission parts of the system are made of steel cylindrical spur gear, the two motors are connected with a small gear and the load is connected with the large gear. When the stiffness of the gear on the two motors is not uniform, the stress of the two small gears is different, and the load of the distribution is not uniform. Because the speed of this system is constant, so the dynamic response time, the speed of the external loop will make the motor’s electromagnetic torque to balance the load torque, So that the output torque is not balanced.In view of the problem that the output torque is not balanced in the dual motor drive system, this paper considers the definition and the influence factors of the spur gear, and analyzes the control principle and the existing problems of the traditional PI parallel control strategy. The analysis shows that the dual motor gear synchronous drive system with dual PI parallel control strategy can guarantee the synchronization of the system with a certain degree, but when the gear stiffness is not uniform, the output torque of the system is unbalanced. In this paper, a torque balancing control strategy based on cross coupling theory is proposed, the two motor torque controllerhave been as a whole, on the basis of cross feedback to the reference torque of each motor to compensate, by setting the coupling synchronization coefficient can control the output torque balance. Deduced torque balancing control system closed-loop transfer function, the Hurwitz stability criterion, the stability of the system is analyzed. At the same time, the evaluation factors of the torque ripple amplitude are defined, and the influence of the coupling coefficient on the performance of the system and the fluctuation range of the torque are analyzed in detail, Select the optimal coupling coefficient in the last.The hardware experimental platform of the system simulation model and the dual permanent magnet synchronous motor drive system have been builted. The results show that the torque balance control strategy can reduce the torque error and guarantee the speed of the system and reduced the overload risk of single motor.