Sensorless accurate commutation method and device of brushless DC motor

Abstract

The invention discloses a sensorless accurate commutation method and device of a brushless DC motor. The sensorless accurate commutation method comprises the steps of respectively connecting an A-phase voltage line, a B-phase voltage line and a C-phase voltage line of the brushless DC motor to corresponding voltage acquisition devices, triggering commutation service interrupt by jump edges of induction voltage waveforms of three phases A, B and C; entering commutation service interrupt if the jump edges are descending edges, and changing states of corresponding MOS tubes and IGBTs to achieve commutation after delaying by 30 electrical angels; performing triggering by ascending edges if the jump edges are ascending edges, starting to count in a circulation way from 0, entering commutation service interrupt when a counting value is 2, changing the states of the corresponding MOS tubes and IGBTs to achieve commutation after delaying by 30 electrical angels, and resetting the counter. Thecommutation method has the advantages of high interrupt service trigger and good reliability, a commutation misjudgment accident of the brushless DC motor is prevented under the interference of a demagnetization accident, and the commutation moment is scientifically and simply judged.

Description

technical field [0001] The invention relates to the technical field of brushless direct current motors, in particular to a method and device for accurate phase commutation of brushless direct current motors without sensors. Background technique [0002] In the square wave control strategy of the brushless DC motor, two phases of the motor are turned on and one phase is turned off at each moment. In the actual commutation process, there is inductive energy storage on the switched-off phase to generate freewheeling, so that a completely opposite electromotive force is generated on the winding of this phase. After the inductive energy storage of this phase is consumed, the phase The electromotive force on the circuit is completely only generated by the winding cutting the magnetic force line. Since the energy storage of the inductor is consumed quickly, the port voltage of the turned-off phase will generate a voltage pulse before the jump edge, and this voltage pulse is easily ...

AI Technical Summary

Problems solved by technology

In the actual commutation process, there is inductive energy storage on the switched-off phase to generate freewheeling, so that a completely opposite electromotive force is generated on the winding of this phase. After the inductive energy storage of this phase is consumed, the phase The electromotive force on the circuit is completely only generated by the winding cutting the magnetic force line. Since the energy storage of the inductor is consumed quickly, the port voltage of the turned-off phase will generate a voltage pulse before the jump edge, and this voltage pulse is easily misjudged by the microcontroller as commutation signal, resulting in early commutation, which greatly reduces the operating efficiency and control performance of the system

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