CN201188124Y - Non-induction type phase-exchanging signal detector for brushless DC motor - Google Patents

Abstract

The utility model relates to a non-inductive phase-change signal detector for a brushless direct-current motor, which comprises three voltage-dividing circuits (1), three constant zero phase shift filtering circuits (2) and three line voltage comparators (3). The input terminal of each voltage-dividing circuit is respectively connected with a triple-phase line of a motor, the output terminal of each voltage-dividing circuit is connected with one constant zero phase shift filtering circuit in parallel and connected with the positive input terminal of the respective line voltage comparator, and the output terminal of each line voltage comparator outputs a phase change signal used for controlling an IC. The non-inductive phase-change signal detector adopts the constant zero phase shift filtering circuits and the line voltage comparators which are not changed along with the change of the rotating speed of the motor, a virtual neutral point is not required to be constructed, a speed estimator and a phase-shift calibration device are not required, the accurate phase change signal can be output within the entire range of high rotating speed ratio, the phase change signal is completely consistent with the phase change signal output by a Hall sensor, and the IC is not required to be controlled at high speed, the low-cost IC matched with the Hall sensor can be directly used. The non-inductive phase-change signal detector has the advantages that the circuit structure is simple, the cost is low, the non-inductive phase-change signal detector can replace the Hall senor to be widely applied to brushless direct current motors used for household appliances, computer peripheral equipment, electric motor cars, and the like.

Description

The non-induction type commutation signal of brshless DC motor detecting device

Technical field

The utility model belongs to electric motors, the non-induction type commutation signal of specifically a kind of brshless DC motor detecting device.

Background technology

At present the detection method of brshless DC motor commutation signal mainly contains two kinds of induction type and non-induction types.Wherein, induction type is by coming the position of detection rotor in operation process at three Hall elements of installation on the brushless motor stator, convert the position signalling of rotor magnetic steel magnetic pole to electric signal, IC provides correct commutation signal for control, conducting and shutoff with the power device of control inverter, make the electric current commutation in the armature winding, form step-type rotating magnetic field in the space, drive rotor and continuously rotate along with the variation of rotor-position.The deficiency of this method is: because of adopting three external Hall elements that unit price is higher, increased motor volume, and can not adapt to rugged surroundings such as high temperature, high humidity, vitiated air, in case particularly Hall element damages, need to change whole stator, maintenance cost is higher.The method that another kind of non-induction type generally uses is a back-emf zero crossing detection method (referring to Fig. 1).Concrete detection method is: behind 90 ° of phase-shift filterings of brshless DC motor three phase terminals voltage difference dividing potential drop, obtain the three-phase commutation signal with the dummy neutral voltage ratio.The deficiency of this method is: the phase shift angle that three phase terminals voltage passes through behind 90 ° of phase-shift filterings is also non-constant at 90 °, but change along with the variation of motor speed, make the phase place of commutation signal also in continuous variation, cause commutation inaccurate, commutation meeting failure when serious, this method only can be applied on the brshless DC motor of slow-speed of revolution ratio or fixed rotating speed, when needs are applied on the brshless DC motor of high rotating ratio, must adopt velocity estimator that phase shift angle is proofreaied and correct in the control IC, to guarantee 90 ° constant phase shift, though this method can be avoided the inaccurate problem of commutation, but detection algorithm is very complicated, take the overlong time of control IC, must adopt High-speed Control IC, can not directly use the cheap control IC that matches with Hall element, give the production procedure of former employing induction type, operational method, system design brings huge change, the upgrading risk is too high, and cost increases a lot.

Summary of the invention

The utility model purpose is: at the shortcoming of above prior art existence, it is simple to propose a kind of circuit, with low cost, permanent zero phase-shift filtering, need not to make up dummy neutral, need not velocity estimator and phase shift correction, in the scope of whole high rotating ratio, can both keep exporting accurate commutation signal, the commutation signal of this commutation signal and Hall element output is in full accord, need not High-speed Control IC, can directly use the non-induction type commutation signal detecting device of the cheap control IC that matches with Hall element.

The scheme that its technical matters that solves the utility model adopts is: comprise three bleeder circuits (1), three permanent zero phase-shift filtering circuits (2) and three line voltage comparators (3).It is characterized in that three bleeder circuits (1) are respectively by two resistance R 1, R2 series connection, the end of its R1 is connected with the three phase electric machine line of brshless DC motor respectively as input end, R2 ground connection, the tie point between R1, the R2 is connected with the positive input terminal of homologous lines voltage comparator respectively as output terminal; Three permanent zero phase-shift filtering circuits (2) are respectively by two resistance R 3, R4, and two capacitor C 1, C2 and integrated transporting dischargings constitute.Capacitor C 1 also is connected in bleeder circuit R2, one end of capacitor C 2 is connected with the positive input terminal of amplifier and is connected with an end of capacitor C 1, the other end of capacitor C 2 is connected with the output terminal of amplifier, one end of resistance R 3 is connected with the output terminal of amplifier, the other end is connected with the negative input end of amplifier, one end of resistance R 4 is connected with the negative input end of amplifier, other end ground connection; The positive input terminal of three line voltage comparators (3) is connected with the output terminal of corresponding bleeder circuit respectively, and negative input end is connected with the output terminal of adjacent bleeder circuit respectively, and the output of each line voltage comparator is respectively as the commutation signal of motor.

The utility model is compared with background technology, owing to adopted the permanent zero phase-shift filtering circuit that does not change with motor speed, need not phase shift correction, and being two-way, the voltage of delivering to the comparer positive and negative terminal do not have the terminal voltage of phase shift, need not to make up dummy neutral, what comparer detected is the zero crossing of line voltage, this zero crossing is the commutation point of corresponding motor just in time, therefore, the commutation signal of the commutation signal of output and Hall element output is in full accord, in the scope of the high rotating ratio of brushless electric machine, need not High-speed Control IC, can directly use the cheap control IC that matches with Hall element, circuit structure is simple, with low cost, alternative Hall element is widely used in household electrical appliances, on the brshless DC motor such as computer peripheral equipment and electric vehicle, farthest guarantee the stability of former employing induction type production procedure and evaded the risk that enterprise's secondary research and development are produced, and increased the mode switch function of brshless DC motor induction/non-induction control strategy, kept the inheritability and the compatibility of system.

Description of drawings

Fig. 1 is the back-emf zero crossing detection method functional-block diagram of background technology.

Fig. 2 is circuit theory diagrams of the present utility model.

Fig. 3 is the oscillogram of Va, Vb among the utility model Fig. 2, Vc, Vao, Vbo, Vco voltage signal and commutation signal H1, H2, H3.

Embodiment

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

As shown in Figure 2, the utility model comprises three bleeder circuits (1), three permanent zero phase-shift filtering circuits (2) and three line voltage comparators (3).Wherein each bleeder circuit is in series by two resistance R 1, R2, and its R1 is connected with the three phase electric machine line of brshless DC motor respectively, R2 ground connection, and the tie point between R1, the R2 is as output terminal difference and connection permanent zero phase-shift filtering circuit separately; Each permanent zero phase-shift filtering circuit is respectively by two resistance R 3, R4, and two capacitor C 1, C2 and integrated transporting dischargings constitute.Capacitor C 1 also is connected in bleeder circuit R2, one end of capacitor C 2 is connected with the positive input terminal of amplifier and is connected with an end of capacitor C 1, the other end of capacitor C 2 is connected with the output terminal of amplifier, one end of resistance R 3 is connected with the output terminal of amplifier, the other end is connected with the negative input end of amplifier, one end of resistance R 4 is connected with the negative input end of amplifier, other end ground connection; The positive input terminal of each line voltage comparator is connected with the output terminal of corresponding bleeder circuit respectively, and negative input end is connected with the output terminal of adjacent bleeder circuit respectively, and the output signal of each line voltage comparator is respectively as the commutation signal of motor.

As shown in Figure 3, the course of work of the present utility model is:

The motor three phase terminals voltage Va, Vb, the Vc that contain a large amount of PWM modulating waves obtain level and smooth terminal voltage Vao, Vbo, the Vco that amplitude reduces behind three bleeder circuits and permanent zero phase-shift filtering circuit, the phase shift angle φ of each phase terminal voltage is before and after the filtering:

$\mathrm{\φ}=\arctan \frac{\mathrm{\ωR}1R2(C1-R3/R4C2)}{R1+R2}$

ω is the angular velocity of motor operation in the formula.

As long as design $C1=\frac{R3}{R4}\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y20082000990700062.png"\; state="\{\{state\}\}">C</figure-callout>}2,$ Just can be so that the phase shift angle perseverance before and after the filtering is zero, guarantee can not follow the variation of motor speed before and after the zero crossing filtering of terminal voltage and move, need not phase shift correction.

After the permanent zero phase-shift terminal voltage of adjacent two-phase is delivered to comparer, the comparer comparison be two phase terminal voltages, it is exactly in fact the zero crossing of detection line voltage, this zero crossing is the commutation point of corresponding motor just in time, therefore, the commutation signal of the commutation signal of comparer output and Hall element output is in full accord.

Claims (5)

1, the non-induction type commutation signal of brshless DC motor detecting device is characterized in that, this detecting device comprises three bleeder circuits (1), three permanent zero phase-shift filtering circuits (2) and three line voltage comparators (3).

2, the non-induction type commutation signal of brshless DC motor according to claim 1 detecting device, it is characterized in that, each bleeder circuit comprises two resistance R 1, R2 series connection, the end of its R1 is connected with the three phase electric machine line of brshless DC motor respectively as input end, R2 ground connection, the tie point between R1, the R2 is connected with the positive input terminal of relevant voltage comparer respectively as output terminal.

3, the non-induction type commutation signal of brshless DC motor according to claim 1 and 2 detecting device, it is characterized in that, each permanent zero phase-shift filtering circuit comprises two resistance R 3, R4, two capacitor C 1, C2 and an integrated transporting discharging, capacitor C 1 also is connected in bleeder circuit R2, one end of capacitor C 2 is connected with the positive input terminal of amplifier and is connected with an end of capacitor C 1, the other end of capacitor C 2 is connected with the output terminal of amplifier, one end of resistance R 3 is connected with the output terminal of amplifier, the other end is connected with the negative input end of amplifier, one end of resistance R 4 is connected with the negative input end of amplifier, other end ground connection.

4, according to claim 1 or the non-induction type commutation signal of 3 described brshless DC motors detecting device, it is characterized in that, in each permanent zero phase-shift filtering circuit $C1=\frac{R3}{R4}C2.$

5, according to claim 1 or the non-induction type commutation signal of 2 or 3 described brshless DC motors detecting device, it is characterized in that, the positive input terminal of each line voltage comparator is connected with the output terminal of corresponding bleeder circuit respectively, and negative input end is connected with the output terminal of adjacent bleeder circuit respectively, and the output of comparer is respectively as the commutation signal of motor.

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