Counter-potential zero-crossing detection circuit and counter-potential zero-crossing detection method for brushless direct-current motor

Abstract

The invention discloses a counter-potential zero-crossing detection circuit and a counter-potential zero-crossing detection method for a brushless direct-current motor, wherein in the counter-potential zero-crossing detection circuit for the brushless direct-current motor, a three-phase winding of the brushless direct-current motor is connected with a direct-current power supply via a bridge-type inverter, and the bridge-type inverter is formed by connecting six power switch tubes; the counter-potential zero-crossing detection circuit is characterized by comprising three detection modules used for detecting the counter-potential zero crossing of a phase A, a phase B and a phase C, and provided with the same structure; and each detection module comprises a comparator, and two electronic switch voltage-dividing module provided with the same structure and same circuit parameters. Via the counter-potential zero-crossing detection circuit and the counter-potential zero-crossing detection method disclosed by the invention, the danger that a counter-potential amplitude value is greater than the power supply voltage value of the detection circuit in case of high speed can be avoided. Simultaneously, as a mode that low-speed-area counter-potential sampling and high-speed-area counter-potential sampling are switched by controlling the signal duty ratio is adopted, the counter-potential zero-crossing detection effect in a low-speed area can be effectively improved. Experimental results indicate that the counter-potential zero-crossing detection circuit and the counter-potential zero-crossing detection method for the brushless direct-current motor can ensure the working of the motor within a relatively wide rotational speed range.

Description

technical field [0001] The invention belongs to the field of mechanical engineering, and relates to a detection circuit and a detection method for a counter electromotive force zero-crossing of a brushless DC motor. Background technique [0002] Brushless DC motor has the characteristics of small size, light weight, high efficiency, and low loss. It has not only been widely used in industrial applications such as aviation, aerospace, machinery, and automobiles, but also widely used in civilian fields such as air conditioners, refrigerators, and electric bicycles. . Usually, brushless DC motors generally use position sensors to determine the position of the motor rotor, but the installation of position sensors increases system cost, increases system complexity, and reduces system reliability and anti-interference capabilities. Therefore, position sensorless brushless DC motor control technology It has become a hot spot in the field of motor control research. At present, the...

AI Technical Summary

Problems solved by technology

The back EMF zero-crossing detection method does not require the actual neutral point signal, and it is simple to implement, but because the back EMF amplitude is very small at low speeds, and the signal is obtained after the resistance is divided, compared with the virtual neutral point voltage The voltage amplitude is lower, causing the back-EMF zero-crossing circuit to not work effectively during motor start-up or low speed

However, when the motor is running at high speed, the high back EMF will seriously affect the normal operation of the back EMF zero-crossing detection circuit, or even damage the zero-crossing detection circuit, so that the normal operation of the motor at high speed cannot be guaranteed.

Therefore, the speed regulation range of the position sensorless brushless DC motor based on the back EMF has certain limitations

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