Method for sensorless detection of initial position of brushless direct current motor

Abstract

The invention discloses a method for sensorless detection of the initial position of a brushless direct current motor. The method for the sensorless detection of the initial position of the brushless direct current motor comprises the steps that positioning is carried out for the first time before the motor is started according to a three-phase six-state pairwise-breakover switch mode, six voltage pulses are applied in the counterclockwise rotation direction, six bus electric current peak values are obtained by sampling direct-current bus peak currents after the six voltage pulses acts for a fixed period of time, the six voltage pulses are divided into three pairs of opposite switch state voltage pulses, three pairs of opposite switch state breakover current difference values are obtained through by infusing the opposite switch state voltage pulses into the corresponding bus electric current peak values and conducting subtraction, then a current threshold delta I of a critical initial position is set according to the current difference values, the position where two pairs of opposite switch state breakover current difference values are lower than the current threshold delta I is a rotor critical initial position, positioning is carried out for the second time when the rotor critical initial position is detected to be a critical position, and the critical initial position is judged by means of vectors of two most-adjacent three-phase six-state ternary-breakover voltages based on the first positioning. The method for the sensorless detection of the initial position of the brushless direct current motor solves the problems that detection can not be achieved accurately when a rotor is located between two 60-degree sectors and is convenient to realize and suitable for low-cost occasions.

Description

technical field [0001] The invention is applied in the field of position sensorless brushless direct current motor control, and in particular relates to a method for detecting the initial position of the brushless direct current motor. Background technique [0002] Brushless DC motor (Brushless DC Motor, BLDCM) has the advantages of simple structure, reliable operation, low mechanical noise and good speed regulation performance, and has been widely used in industrial and commercial fields. The position sensorless control method does not use a position sensor, but uses voltage, current, etc. to indirectly obtain rotor position information. The commonly used methods include back electromotive force method, stator third harmonic detection method, stator inductance method, freewheeling diode current path detection method, Flux linkage estimation method, state observer method, etc. These methods all need to determine the initial position of the rotor. The determination of the ini...

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Problems solved by technology

Generally, the estimation accuracy of the rotor position based on the saturation effect of the stator core is 60 degrees electrical angle, but the estimation of the critical position in the adjacent sector is inaccurate, which restricts the application occasions with high starting torque requirements

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