CN205754084U - The position detecting circuit of motor - Google Patents

Abstract

This utility model embodiment discloses the position detecting circuit of a kind of motor.Described circuit includes: operational amplifier and zero-crossing detector, the in-phase input end of described operational amplifier is connected with three-phase driving signal Zhong mono-tunnel of described motor, the reverse input end of described operational amplifier is connected with another road in the three-phase driving signal of described motor, and the outfan of described operational amplifier is connected with the input of described zero-crossing detector.The position detecting circuit of the motor that this utility model embodiment provides and method improve the accuracy of the detection of the current location to motor.

Description

The position detecting circuit of motor

Technical field

This utility model embodiment relates to motor control technology field, particularly relates to the position detecting circuit of a kind of motor.

Background technology

At present have that assembling is simple, application occasion is wide, reliability is high due to position-sensor-free permanent-magnet brushless DC electric machine and the advantage such as low cost, obtained using the most widely.But owing to its application occasion is complex, and program prestart can not directly obtain motor position signal, starts control difficulty higher, tends to situation starting failure occur under various external interference.Such as, in the case of being affected by external force, DC fan prestart is likely to be at forward or counter-rotating state, and its rotating speed also likely to be present larger difference, in this case being accomplished by controller uses appropriate method for detecting position to detect current blower fan status, and the reliable of guarantee blower fan starts.

In order to solve such problem, prior art provides a kind of position and Rotating speed measring method.This detection method controls 6 IGBT of 3 phase brachium pontis by the PWM ripple of processor generation 50% and turns in order, and 3 phase currents produced in 3 phase windings by counter electromotive force of motor are adopted into controller, then draw current zero-crossing point region after the current signal detected being carried out threshold process by software, obtain motor rotor position and rotor speed information further.

In this detection method, counter electromotive force is current generated when IGBT and institute thereof fly-wheel diode inner loop in parallel flowing, owing to the diode of IGBT internal parallel exists fixing conduction voltage drop, when counter electromotive force pressure drop is less than diode turn-on voltage, diode ends, and causes phase current to there is zero current clamping phenomenon when zero crossing.See Fig. 1, at zero crossing, have one section keep initial value trend and the platform 11 that formed.Further, counter electromotive force of motor is the least, rotating speed is the lowest, and this plateau phenomenon is the most obvious, plateau time is the longest.Meanwhile, also will result in electric current near zero crossing position during 6 IGBT order switched conductive and vibration distortion occurs so that zero-crossing examination difficulty increases, and accuracy is poor.And, simultaneously detection one electrical cycle in 3 phase currents 6 at zero crossing, due to only 1/6 cycle between two zero crossings, detection time zone is less, and affected by zero crossing platform and zero crossing threshold interval, motor speed is the highest, and the time zone that can be detected by is the least, trueness error is the biggest, has a strong impact on the current rotating speed of motor and the accuracy of angle calculation.

Utility model content

For above-mentioned technical problem, this utility model embodiment proposes a kind of position detecting circuit and the method for motor, to improve the accuracy that the current location to motor is detected.

This utility model embodiment provides the position detecting circuit of a kind of motor, described circuit includes: operational amplifier and zero-crossing detector, the in-phase input end of described operational amplifier is connected with three-phase driving signal Zhong mono-tunnel of described motor, the inverting input of described operational amplifier is connected with another road in the three-phase driving signal of described motor, and bridging has feedback resistance between the outfan of described operational amplifier and described inverting input, described operational amplifier is for by poor to three-phase driving signal Zhong mono-tunnel of described motor and another road, to obtain reconstruction signal；The outfan of described operational amplifier is connected with the input of described zero-crossing detector, described zero detector for by detect described reconstruction signal phase place, it is determined that described motor when front steering and current location.

The position detecting circuit of the motor that this utility model embodiment provides, utilize the difference signal between any two in the three-phase driving signal of operational amplifier calculating motor, and the reconstruction signal that described difference signal detected as position, again by identify described reconstruction signal phase determination motor when front steering and current location, avoid the zero current clamping phenomenon in existing method for detecting position, improve turning to and the accuracy of position detection of motor.

Accompanying drawing explanation

The detailed description that non-limiting example is made made with reference to the following drawings by reading, other features, objects and advantages of the present utility model will become more apparent upon:

Fig. 1 is the schematic diagram of zero current clamping phenomenon in prior art；

Fig. 2 is the circuit structure block diagram of the position detecting circuit of the motor that this utility model first embodiment provides；

Fig. 3 is the signal waveforms of the reconstruction signal of the position detecting circuit of the motor that this utility model first embodiment provides；

Fig. 4 is the circuit structure diagram of the position detecting circuit of the motor that this utility model the second embodiment provides.

Detailed description of the invention

The utility model is described in further detail with embodiment below in conjunction with the accompanying drawings.It is understood that specific embodiment described herein is only used for explaining this utility model, rather than to restriction of the present utility model.It also should be noted that, for the ease of describing, accompanying drawing illustrate only the part relevant to this utility model rather than full content.

First embodiment

Present embodiments provide a kind of technical scheme of the position detecting circuit of motor.Seeing Fig. 2, in this technical scheme, the position detecting circuit of described motor includes: operational amplifier 21 and zero-crossing detector 22.

In this utility model, described motor refers in particular to permanent-magnet brushless DC electric machine.It is understood that directly driving the signal of described permanent-magnet brushless DC electric machine operating is the three-phase driving signal exported by the inverter of described permanent-magnet brushless DC electric machine.Owing to generally comprising IGBT element in inverter, and the conducting of IGBT element typically requires certain voltage drop.Therefore, each all can there is plateau phenomenon, namely zero crossing clamper phenomenon near zero crossing position in cause in described three-phase driving signal.

In the present embodiment, described three-phase driving signal Zhong mono-road signal is connected with the in-phase input end of described operational amplifier, and another road signal in described three-phase driving signal is connected with the inverting input of described operational amplifier.Concrete, the road signal being connected with described in-phase input end is by the homophase input resistance R being in series with described in-phase input end_i2Access to the in-phase input end of described operational amplifier, and another road signal being connected with described inverting input is by the anti-phase input resistance R being in series with described inverting input_i1Access to the inverting input of described operational amplifier.And, between the outfan of described inverting input and described operational amplifier, also bridging has feedback resistance R_f1.Meanwhile, described normal phase input end is also by earth resistance R_f2Ground connection.

It is assumed that described feedback resistance R_f1Resistance and described earth resistance R_f2Resistance identical, be R_f, and, described homophase input resistance R_i2Resistance and described anti-phase input resistance R_i1Resistance the most identical, be R, the input voltage of the most described operational amplifier, namely reconstruction signal u_oFormula (1) can be passed through represent:

$u_o=\frac{R_F}{IR}\×(u_{i2}-u_{i1})---\left(1\right)$

Wherein, u_i2It is the voltage signal inputted by described in-phase input end, and u_i1It it is the voltage signal inputted by described inverting input.

Owing to all there is the phase contrast of 2 π/3, the voltage signal u the most either inputted by described in-phase input end between phase signals each in described three-phase driving signal and other two phase signals_i2The zero crossing moment, still have the voltage signal u that described inverting input inputs_i1The zero crossing moment, in described reconstruction signal all can not or the zero crossing moment.It is to say, the zero crossing moment of described reconstruction signal both can not be with the voltage signal u inputted by described in-phase input end_i2The zero crossing moment identical, it is also not possible to the voltage signal u having described inverting input to input_i1The zero crossing moment identical.Therefore, reconstruction signal is the most smooth at zero crossing, does not haves plateau phenomenon.So, turning to the detection with position according to what the zero crossing of reconstruction signal carried out motor, its detection accuracy can significantly improve relative to prior art.

Described zero-crossing detector 22 by judging current the turning to and position of described motor to the phase-detection of described reconstruction signal.

Fig. 3 shows original three-phase driving signal Ia, Ib, Ic and the signal waveform of described reconstruction signal Ia-Ib.Seeing Fig. 3, the cycle of described reconstruction signal Ia-Ib is identical with the cycle of described original three-phase driving signal Ia, Ib, Ic, and phase place is compared to minuend signal Ia advanced 1/12 cycle in described three-phase driving signal.Therefore, described zero-crossing detector 22 can judge turning to and position of described motor by detecting continuous two zero crossings of described reconstruction signal.

Preferably, described zero-crossing detector 22 is by detection the moment of two the continuous print zero crossings recording described reconstruction signal, and is calculated the rotating speed of described motor by formula (2):

$n=\frac{60}{2\×(t_2-t_1)}---\left(2\right)$

Wherein, n is the rotating speed of described motor, and its unit is rev/min.t₁For the time of first zero crossing, t in continuous two zero crossings being detected₂For the time of second zero crossing in continuous two zero crossings being detected.t₁And t₂Unit be all the second.

See Fig. 3, for build original two phase signals of described reconstruction signal equal time, the absolute value of the value of described third phase signal should be maximum.Described zero-crossing detector 22 is by judging the phase place of the most described third phase signal, it is possible to determine that turning to of described motor.

Further, since described original three-phase driving signal is relative to T/12,5T/12 and-T/4 after described reconstruction signal difference, therefore, it can the position of rotation that motor described in the phase determination by identifying described reconstruction signal is current.

It should be noted that in the present embodiment, by selecting two phase signals poor from three-phase driving signal, and using the consequential signal of work difference as single reconstruction signal, according to turning to and position of motor described in described single reconstruction signal identification.In actual applications, three-phase reconstruction signal can be obtained by the poorest for described three-phase driving signal, turning to and position according to motor described in described three-phase reconstruction signal identification.

Original three-phase driving signal is reconstructed by the present embodiment by an operational amplifier, overcomes the error of the position detection that the zero crossing of Direct Recognition original driving signal causes, and improves turning to and the accuracy of position detection of motor.

Second embodiment

Present embodiments provide the another kind of technical scheme of the position detecting circuit of motor.In this technical scheme, the position detecting circuit of described motor includes: operational amplification circuit 41 and zero-crossing examination its 42.

Concrete, seeing Fig. 4, described operational amplification circuit 41 includes the first operational amplifier A 1 and the second operational amplifier A 2.The in-phase input end of described first operational amplifier A 1 connects with signal with in described three-phase driving signal, and another phase signals in described three-phase driving signal is connected with the in-phase input end of described second operational amplifier A 2.The outfan of described first operational amplifier A 1 is connected with the inverting input of described second operational amplifier A 2.The inverting input of described first operational amplifier A 1 passes through earth resistance R1 ground connection.Further, between outfan and its inverting input of described first operational amplifier A 1, bridging has the first feedback resistance R_f1.Between outfan and its inverting input of described second operational amplifier A 2, bridging has the second feedback resistance R_f2。

By the process of operational amplification circuit above, its output voltage signal can be given by formula (3):

$u_o=-\frac{R_{f2}}{R_3}(1+\frac{R_{f1}}{R_1})u_{i1}+(1+\frac{R_{f2}}{R_3})u_{i1}---\left(3\right)$

Similarly, since phase signals u inputted by the in-phase input end of described first operational amplifier_i1And another phase signals u by the in-phase input end input of described second operational amplifier_i2There is identical cycle, different phase places, the voltage signal u of described operational amplification circuit input_oThere is not zero crossing clamper phenomenon.

Original three-phase driving signal is reconstructed by the present embodiment by two operational amplifiers, overcomes the error of the position detection that the zero crossing of Direct Recognition original driving signal causes, and improves turning to and the accuracy of position detection of motor.

Each embodiment in this specification all uses the mode gone forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, and the same or analogous part between each embodiment sees mutually.

It is appreciated that when word " includes " and/or " comprising " is used in this specification, represents the existence of described feature, operation, element and/or assembly, but be not excluded for other features one or more, element, assembly and/or the existence of a combination thereof or interpolation.Unless otherwise clear and definite regulation or restriction, term " connect " refer to electrical connection.Concrete, it can be directly electrical connection, it is also possible to be to be connected by the Indirect Electro of other elements.

The foregoing is only preferred embodiment of the present utility model, be not limited to this utility model, to those skilled in the art, this utility model can have various change and change.All any modification, equivalent substitution and improvement etc. made within spirit of the present utility model and principle, within should be included in protection domain of the present utility model.

Claims (4)

1. the position detecting circuit of a motor, it is characterized in that, including: operational amplifier and zero-crossing detector, the in-phase input end of described operational amplifier is connected with three-phase driving signal Zhong mono-tunnel of described motor, the inverting input of described operational amplifier is connected with another road in the three-phase driving signal of described motor, and bridging has feedback resistance between the outfan of described operational amplifier and described inverting input, described operational amplifier is for by poor, to obtain reconstruction signal to three-phase driving signal Zhong mono-tunnel of described motor and another road；The outfan of described operational amplifier is connected with the input of described zero-crossing detector, described zero detector for by detect described reconstruction signal phase place, it is determined that described motor when front steering and current location.

Circuit the most according to claim 1, it is characterised in that described three-phase driving signal Zhong mono-road signal is connected with described in-phase input end by the homophase input resistance connected with described in-phase input end.

Circuit the most according to claim 1, it is characterised in that another road signal in described three-phase driving signal is connected with described inverting input by the anti-phase input resistance connected with described inverting input.

Circuit the most according to claim 1, it is characterised in that described zero-crossing detection circuit calculates the rotating speed of described motor by detecting continuous two zero crossings of the output signal of the outfan of described operational amplifier.