CN201307842Y

CN201307842Y - Opposing electromotive force zero crossing detection circuit of sensorless and brushless DC motor

Info

Publication number: CN201307842Y
Application number: CNU2008203022676U
Authority: CN
Inventors: 刘瑜; 胡丽花; 潘海鹏
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-09-27
Filing date: 2008-09-27
Publication date: 2009-09-09
Anticipated expiration: 2018-09-27

Abstract

The utility model relates to an opposing electromotive force zero crossing detection circuit of sensorless and brushless DC motor, which comprises a singlechip, an opposing electromotive force detection circuit and a driving voltage detection circuit. The opposing electromotive force detection circuit comprises divider resistances, filter capacitors and catching diodes of detection opposing electromotive forces; the driving voltage detection circuit comprises the divider resistances and the filter capacitor; the opposing electromotive force detection circuit adopts unified divider ratio, and the divider ratio is larger than the divider ratio of the driving voltage detection circuit; and when the voltage detected by the opposing electromotive force detection circuit forms a certain proportional relation with the voltage detected by the driving voltage detection circuit, opposing electromotive force zero crossing is determined. The utility model has the advantages that different resistor divider ratios are adopted, the detection precision of opposing electromotive force is improved, the measuring precision of location of an electric motor rotor is enhanced, thus obtaining a better commutation point in time.

Description

A kind of back electromotive force zero-crossing detection circuit that does not have the sensing dc brushless motor

Technical field

The utility model belongs to the no sensing Driving technique of brshless DC motor.

Background technology

The tradition brush direct current motor is because the reason of life-span and noise can not be applied to some special occasions.And the brshless DC motor of employing belt sensor, the problem that can bring manufacturing, difficulty and long-term immersion oil are installed.Therefore the no sensing Driving technique of brshless DC motor has extremely important and uses widely.

The control of the rotating speed of brshless DC motor is by driving voltage is regulated, and comes the power supply of switch motor to realize according to the position of rotor.Because the rotor-position and the back electromotive force of brshless DC motor have definite corresponding relation,, just need not the sensing element of detection rotor position if therefore determine the rotor-position of brshless DC motor by detecting counter electromotive force of motor.But back electromotive force can not directly detect, and can only obtain indirectly by detecting phase voltage.Such as, when A, B switch on mutually, detect the C phase voltage, when the C phase voltage equal driving voltage 1/2 the time, be defined as the zero crossing of back electromotive force.

Under the overwhelming majority situation, driving voltage, phase voltage all greater than the supply power voltage VCC of single-chip microcomputer, detect because must carry out dividing potential drop, make the later magnitude of voltage of dividing potential drop be less than or equal to VCC.When detected phase voltage equal driving voltage 1/2 the time, be defined as the zero crossing of back electromotive force.But after the vast scale dividing potential drop, the accuracy of detection of phase voltage reduces greatly, thereby influences the commutation precision.

Summary of the invention

The present invention seeks to determine motor rotor position, obtain accurate commutation point, thereby realize the no transducer control effect of more stable brshless DC motor in order to improve the back electromotive force zero-crossing accuracy of detection.

The technical scheme that its technical problem that solves the utility model adopts is:

A kind of back electromotive force zero-crossing detection circuit that does not have the sensing dc brushless motor comprises single-chip microcomputer 1, counter electromotive force detection circuit, driving voltage testing circuit.Described counter electromotive force detection circuit, by the resistance R 1, resistance R 4, capacitor C 1 and the diode D1 that detect A phase back electromotive force, detect resistance R 2, resistance R 5, capacitor C 2 and the diode D2 of B phase back electromotive force, the resistance R 3, resistance R 6, capacitor C 3 and the diode D3 that detect B phase back electromotive force form; Described driving voltage testing circuit is made up of resistance R 7, resistance R 8 and capacitor C 4; Described counter electromotive force detection circuit, voltage ratio R4/ (R1+R4)=R5/ (R2+R5)=R6/ (R3+R6); Described driving voltage testing circuit, voltage ratio R8/ (R7+R8) is less than voltage ratio R4/ (R1+R4), R5/ (R2+R5), the R6/ (R3+R6) of electromotive force testing circuit.The magnitude of voltage that detects when described counter electromotive force detection circuit equals the R4 that described drive voltage circuit detects magnitude of voltage * (R7+R8)/(2 * R8 * (R1+R4)), or R5 * (R7+R8)/(2 * R8 * (R2+R5)), or R6 * (R7+R8)/(2 * R8 * (R3+R6)) time, determine back electromotive force zero-crossing.

The beneficial effects of the utility model mainly show: 1, circuit structure is simple, and cost is low; 2, the back electromotive force zero-crossing accuracy of detection effectively improves; 3, software is realized simple.

Description of drawings

Fig. 1 is the schematic diagram of the back electromotive force zero-crossing detection circuit of no sensing dc brushless motor.

Embodiment

Below in conjunction with accompanying drawing the utility model is further described.

With reference to Fig. 1, a kind of back electromotive force zero-crossing detection circuit that does not have the sensing dc brushless motor comprises single-chip microcomputer 1, counter electromotive force detection circuit, driving voltage testing circuit.

Counter electromotive force detection circuit, by the resistance R 1, resistance R 4, capacitor C 1 and the diode D1 that detect A phase back electromotive force, detect resistance R 2, resistance R 5, capacitor C 2 and the diode D2 of B phase back electromotive force, the resistance R 3, resistance R 6, capacitor C 3 and the diode D3 that detect C phase back electromotive force form.The A phase of resistance R 1 one ends link motor M, an end connects resistance R 4, capacitor C 1 and diode D1, and the analog-to-digital conversion port AD0 of connection single-chip microcomputer 1, resistance R 4 and capacitor C 1 other end ground connection, diode D1 meets power supply VCC.The B phase of resistance R 2 one ends link motor M, an end connects resistance R 5, capacitor C 2 and diode D2, and the analog-to-digital conversion port AD1 of connection single-chip microcomputer 1, resistance R 5 and capacitor C 2 other end ground connection, diode D2 meets power supply VCC.The C phase of resistance R 3 one ends link motor M, an end connects resistance R 6, capacitor C 3 and diode D3, and the analog-to-digital conversion port AD2 of connection single-chip microcomputer 1, resistance R 6 and capacitor C 3 other end ground connection, diode D3 meets power supply VCC.

The driving voltage testing circuit is made up of resistance R 7, resistance R 8 and capacitor C 4.Resistance R 7 one termination driving voltage VDC, a terminating resistor R8, capacitor C 4, and the analog-to-digital conversion port AD3 of connection single-chip microcomputer 1; Resistance R 8, capacitor C 4 other end ground connection.

Counter electromotive force detection circuit adopts unified voltage ratio: R4/ (R1+R4)=R5/ (R2+R5)=R6/ (R3+R6); The driving voltage testing circuit, voltage ratio R8/ (R7+R8) is less than voltage ratio R4/ (R1+R4), R5/ (R2+R5), the R6/ (R3+R6) of electromotive force testing circuit;

The back electromotive force zero-crossing detection method of no sensing dc brushless motor: the magnitude of voltage that detects when counter electromotive force detection circuit equals the R4 that drive voltage circuit detects magnitude of voltage * (R7+R8)/(2 * R8 * (R1+R4)), or R5 * (R7+R8)/(2 * R8 * (R2+R5)), or R6 * (R7+R8)/(2 * R8 * (R3+R6)) time, determine back electromotive force zero-crossing, single-chip microcomputer 1 carries out commutation to be handled.

Claims

[claim 1] a kind of back electromotive force zero-crossing detection circuit that does not have the sensing dc brushless motor, comprise single-chip microcomputer (1), counter electromotive force detection circuit, the driving voltage testing circuit, it is characterized in that: described counter electromotive force detection circuit, by the resistance R 1, resistance R 4, capacitor C 1 and the diode D1 that detect A phase back electromotive force, detect resistance R 2, resistance R 5, capacitor C 2 and the diode D2 of B phase back electromotive force, the resistance R 3, resistance R 6, capacitor C 3 and the diode D3 that detect B phase back electromotive force form; Described driving voltage testing circuit is made up of resistance R 7, resistance R 8 and capacitor C 4; Described counter electromotive force detection circuit, voltage ratio R4/ (R1+R4)=R5/ (R2+R5)=R6/ (R3+R6); Described driving voltage testing circuit, voltage ratio R8/ (R7+R8) is less than voltage ratio R4/ (R1+R4), R5/ (R2+R5), the R6/ (R3+R6) of electromotive force testing circuit.
The back electromotive force zero-crossing detection circuit of [claim 2] no sensing dc brushless motor as claimed in claim 1, it is characterized in that: the magnitude of voltage that detects when described counter electromotive force detection circuit equals the R4 that described drive voltage circuit detects magnitude of voltage * (R7+R8)/(2 * R8 * (R1+R4)), or R5 * (R7+R8)/(2 * R8 * (R2+R5)), or R6 * (R7+R8)/(2 * R8 * (R3+R6)) time, determine back electromotive force zero-crossing.