Speed-changing motor controlling circuit of brushless DC

Abstract

The invention is concerned with speed changing controlling circuit of the non-brush direct current motor, it consists of: the power supply, the drive coil that can supply the positive / negative alternative input of the power output direct current, several the first transistors, several the second transistors that connect / break with the first transistors alternatively, the pressure drop element that one end of it electric connects with the drive unit and the other end of it is earthing, and the microprocessor; uses the microprocessor to exam the pressure drop changing of the pressure drop element, and outputs the first and second pulse-width adjusting signal that the level state is opposite, in order to force several the first and the second transistors to be alternative open and close movement, the direct current outputs to the coil continuously from positive direction / negative direction, and achieves better operation and extractive control.

Description

technical field [0001] The invention relates to a variable speed control circuit, in particular to a variable speed control circuit of a brushless direct current motor for precisely adjusting the rotational speed by means of pulse width modulation technology. Background technique [0002] As far as the driving mechanism of the brushless DC fan motor is concerned, when the winding coil of the stator is energized, it cooperates with the Hall IC to judge the magnetic pole position of the permanent magnet rotor, and converts the direction of the current flowing through the winding coil of the stator to generate an alternating magnetic field. , while repelling the permanent magnets the rotor continues to rotate. In addition, pulse width modulation (PWM) is the most common technology for speed control of fan motors. [0003] As shown in Fig. 1, the variable speed circuit design 1 is mainly to use two kinds of pulse width modulation signals A and B to respectively drive the altern...

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Problems solved by technology

[0006] However, since the third and fourth pulse width modulation signals E and F are used to respectively drive the transistor switches 321 and 341 of the first and second control circuits 32 and 34, the first and second transistor switches 31 and 33 and Transistor switches 321 and 341 are susceptible to the back electromotive force interference caused by the instantaneous switching of the current direction and the lack of delayed action. The overall effect is still very doubtful.

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