Long-distance belt conveyor is driven by a number of AC inverter motor, it is affected by a variety of factors, to cause motor power imbalance phenomenon, resulting in uneven distribution of motor load, serious may burn the motor. Therefore, some measures need to be taken to control the power balance of the conveyor. The motor balance is affected by two kinds of static and dynamic factors, the static factor depends on the original design parameters of the belt conveyor, and the good design can make the static power balance achieve good results. The dynamic factor is the instantaneous unbalanced state in the operation of the conveyor, and the dynamic power imbalance can be responded to in time to achieve good results. The main factors affecting the power balance of belt conveyor are: the drum wrapping angle, the friction factor between the conveyor belt and the drum, the motor characteristic, the transmission ratio and the drum diameter difference, etc., so the conveyor should strictly control the above parameters in the design. The main dynamic factors are: conveyor operation resistance, motor output electromagnetic torque and so on. In the concrete production practice, after the static parameters of the conveyor have been determined, the power balance of the motor can be adjusted by the power supply frequency.
The traditional motor power balance control has two strategies of parallel control and master-slave control. Parallel control is to set an unified parameters for multiple motors, all motors run according to the set parameters, master and slave control is mainly to set the main parameters, and from the machine through the host output tracking, the final implementation of the synchronous operation. Parallel control has the disadvantage of poor anti-jamming, and the synchronous operation of master and slave control is poor.
Based on the power balance method of coupling compensation, the variation of the operating parameters of each motor is collected, and the difference of its operating parameters is analyzed, and the compensation is carried out in a targeted manner. This method also considers the error between the given rotational speed and the actual rotational speed of the single-machine drive system and the synchronization error between the different motors. As long as any motor in the running system changes, feedback will be given to the entire system. For dual-machine drive motor, the synchronization accuracy of the system can be improved by the bidirectional compensation of the controller.

For the dual-machine drive system belt conveyor, the running state of the two motors is obtained by analyzing the rotational speed and current. If the two motors are in the power generation and electric state respectively, the load rate is compared, when the motor in the electric state load is large, it is indicated that the conveyor is the load for the motor, the need to increase traction, through the control system to increase the frequency of the motor in the power generation state, it changed from the power generation state to the electric state. When the motor load in the power generation state is large, it is indicated that at this time the conveyor belt speed is high, driving the motor drilling, so it is necessary to reduce the motor frequency in the electric state, from the electric state to the power generation state, power balance control.