The Design Of Permanent Brushless DC Motor In Pumping Unit And Torque Ripple Supperession

The electricity consumption of pumping unit is very large, account for 40% of the total consumption in oilfield. The Cyclical Fluctuation of pumping unit's load, caused the the low enfficiency of the whole system and the waste of electic energy. The pumping unit motor conversation has great significance.According to the power consumption of pumping unit mortorm, the electromagnetic scheme design principles of permanent brushless dc motor (PMBLDCM) were proposed in this paper. According to these principles, by the calculation, the electromagnetic scheme design principles of 22kW PMBLDCM was proposed in this thesis.Dynamic simulink was done to this motor with ANSOFT external circuit, anlyse the unloaded back EMF, unloaded air gap fulx density, torque, current, velocity. The mortor current was set at rated current, then add the function type load and simulating the motor.At permanent motor, the intereffect between permanent magnet and grooved armature core will bring the cogging torque inevitably; this cogging torque caused the torque ripple. According to the auxinliary slot method which was used to suppress the cogging torque, studied the infection of the depth of auxiniliary slot, breadth, amount and axis angle to motor cogging torque. The simulation result show that the cogging torque is minimum when the number is two, the bredth is 0.33 tooth bredth, the axis angle is 4°.Connect the next switch tube advance make the winding's current which in weak magnetic region was trancelated to the next winding which in the higer magnetic destiny. This current can bring compensating torque and decrease the torque ripple. By setting up the connect bredth of externa circuit to realize the overlapping commutation. Smulating anlysis show that the commutation torque ripple is minimum when the motor overlapping commutation is 1.5°.