Control device for brushless direct current motor sensorless and method thereof

Abstract

The invention relates to a control device for a brushless direct current motor sensorless based on 12-beat control and a method thereof. The device comprises a direct current power supply, a three-phase inverter, a brushless direct current motor, a drive circuit of a power device of the three-phase inverter, a microcontroller and a rotor position detection circuit, wherein the direct current powersupply is connected with the brushless direct current motor through the three-phase inverter; after the rotor position detection circuit is connected with the brushless direct current motor for detecting, an output signal is directly connected with an analog-to-digital conversion input pin of the microcontroller; and six-path output of the microcontroller is connected to the three-phase inverterthrough the drive circuit of the power device of the three-phase inverter. The method detects terminal voltage of an inactive phase winding in a two-pipe conducting region at PWM conducted moment by an analog-to-digital conversion unit embedded in an XC866 singlechip, and acquires back electromotive force zero crossing as accordance of 12-beat phase conversion, thereby reducing the requirement ofthe adopted control device of the brushless direct current motor sensorless on a peripheral circuit, and achieving the aims of not only effectively inhibiting electromagnetic torque pulsation, but also reducing the system cost.

Description

Technical field: [0001] The invention relates to a position sensorless control device and method for a brushless direct current motor, in particular to a position sensorless control device and method for a brushless direct current motor with low cost and capable of effectively suppressing electromagnetic torque ripple. Background technique: [0002] At present, the conventional method used to control the brushless DC motor is the 120° conduction type three-phase six-state square wave drive method. This method usually uses 3 Hall elements as position sensors, and performs 6 commutation steps within 360° electrical angle. The algorithm is simple, and the drive control circuit is also relatively simple, so the cost is low and it is suitable for many large-scale applications. However, the outstanding disadvantage of this method is that the winding current contains rich harmonics, which makes the electromagnetic torque ripple large, resulting in poor running stability of the moto...

AI Technical Summary

Problems solved by technology

But the traditional sine wave current driving method, such as three-phase current tracking method, i d , i q Type vector control method, etc. In addition to the complex control algorithm, expensive position sensors such as photoelectric encoders are also required to obtain continuous rotor position signals, which increases the size and cost of the system. For consumer products such as home appliances, the cost is one very important constraints

Therefore, the defect of the traditional brushless DC motor control method is that the convenient and low-cost 120° conduction square wave driving method cannot be applied to high-performance occasions, while the sine wave current driving method suitable for high-performance occasions is not suitable. The cost is too high, so it is of great theoretical and practical significance to find a brushless DC motor control scheme that can effectively suppress the electromagnetic torque ripple and reduce the cost

This 12-beat control method can effectively reduce torque ripple, and the control algorithm is also very simple, but usually requires a Hall position sensor to obtain 12 rotor position signals, which increases the size and cost of the system

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