Locked-rotor processing method and device for position-sensorless DC brushless motor

Abstract

The invention provides a locked-rotor processing method and device for a brushless DC motor without a position sensor, and the method comprises the steps: carrying out the integration of a preset rotor rotating speed threshold value in a period of time when the brushless DC motor just carries out the locked-rotor, and obtaining the position of a rotor; and controlling the voltage vector of the stator coil according to the rotor position through a magnetic field steering control algorithm. Since the rotor speed threshold is a constant, the rotor position obtained by integration of the thresholdis a constant-speed rotation angle, and the stator coil generates a constant-speed rotation magnetic field. Although the rotor stops rotating and is unknown in position during locked-rotor, a sectionof angle always can provide driving torque for the rotor under the action of the magnetic field rotating at the constant speed, the rotor is subjected to periodic impact of the driving torque when locked-rotor happens to the DC brushless motor, and the rotor restarts to rotate when locked-rotor resistance torque is smaller than the driving torque, so the external force interference resistance ofthe brushless DC motor without the position sensor is enhanced.

Description

technical field [0001] The invention relates to the technical field of electric pumps, and more specifically, to a method and device for dealing with a stall of a position sensorless DC brushless motor. Background technique [0002] In existing new energy vehicles, because there is no engine, power cannot be taken from the engine crankshaft, and the water pump and oil pump in the vehicle are gradually changed from mechanical pumps to electric pumps. Due to cost considerations, the power source of the pump body of these electric pumps usually adopts a brushless DC motor without a position sensor. In the current position sensorless brushless DC motor control scheme, since there is no physical position sensor, it is necessary to estimate the rotor position of the motor through an algorithm. [0003] At present, the most widely used method for estimating the rotor position of a brushless DC motor is to estimate the rotor speed of a brushless DC motor through an established moto...

AI Technical Summary

Problems solved by technology

However, since the back electromotive force is proportional to the rotor speed of the motor, the back electromotive force is relatively small when the rotor speed is reduced to a low value due to a stall of the brushless DC motor; and when the back electromotive force is small, the acquisition error of the back electromotive force Larger, resulting in a larger error in the estimation of the rotor speed, and a larger error in the obtained rotor position

[0004] When the rotor position cannot be obtained, the field-oriented control algorithm cannot apply a magnetic field in the correct direction according to the current rotor position, and thus cannot generate a large driving torque. The position sensor brushless DC motor also provides a large torque, resulting in a weak resistance to external force interference of the position sensorless DC brushless motor

In the pump motor system, since there may be impurities and foreign objects in the water or oil circuit of the pump, when these foreign objects block the rotor and cause the brushless DC motor to stall, the pump body will often fail to operate normally and the pump body will be lost. Function

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