CN105207541A - Observation method of quadrature axis inductance of two-phase conduction permanent magnet BLDCM (brushless direct current motor) at low speeds and zero speed - Google Patents

Abstract

The invention relates to an observation method of quadrature axis inductance of a two-phase conduction permanent magnet BLDCM (brushless direct current motor) at low speeds and zero speed. The observation method comprises the following steps: sampling three-phase stator winding phase voltage, filtering the phase voltage through a band-pass filter, and outputting a high-frequency component corresponding to the frequency of an injected high-frequency current; sequentially sending the high-frequency component to a multiplier and a low pass filter, and outputting a direct current component; distributing the direct current component by virtue of three-position switches, wherein the three three-position switches respectively output direct current components Ux1, Ux2 and Ux3; sending the direct current components Ux1 and Ux2 to a subtracter, and outputting Ux1-Ux2; sending the Ux1-Ux2 and the product omega Im of frequency omega and high-frequency current amplitude Im to a divider, and outputting a first part (referring to the description) of quadrature axis inductance; calculating a second part (referring to the description) of quadrature axis inductance according to the Ux1-Ux2, Ux3, frequency omega, high-frequency current amplitude Im and known direct-axis inductance Ld; sending the first part Lq1 and the second part Lq2 of quadrature axis inductance to a adder, and outputting an observed value Lq which is equal to Lq1+Lq2 of quadrature axis inductance. According to the observation method, the problem about accurate observation of quadrature axis inductance during low-speed running of the salient pole type permanent magnet BLDCM runs in a two-stage conduction mode is solved.

Description

Two are conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure

Technical field

The present invention relates to a kind of two to be conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure.

Background technology

Permanent-magnet brushless DC electric machine (BLDCM) adopts two-phase conduction mode, and its control structure is simple.At present two kinds are mainly contained to the research of its control strategy: PWM closed control and direct torque control (DTC).If comprise electromagnetic torque inner ring at PWM closed control, then effectively can improve the dynamic property of this drive system and the stationarity of steady operation; And direct torque control adopts electromagnetic torque closed loop, there is the quick advantage of torque dynamic response.

Compared with traditional sine-wave permanent magnet synchronous motor, permanent-magnet brushless DC electric machine rotor back electromotive force is designed to square wave in theory, so need the d-axis and q-axis inductance parameter of motor when calculating electromagnetic torque.Contain permanent magnet in d-axis direction, permanent magnet permeance is similar to air, so d-axis inductance does not change with the working point change of motor substantially, is constant substantially.So the method for off-line can be adopted to measure d-axis inductance, such as, RLC tester is adopted to measure d-axis inductance value.Quadrature axis saturation effects performance is directly relevant with quadrature axis current size, and namely quadrature axis inductance can change along with the working point change of motor.To accurately calculate electromagnetic torque, in motor course of normal operation, the quadrature axis inductance value with working point change must be measured in real time.

Current measurement quadrature axis inductance mainly contains off-line measurement and online observation two kinds of methods.Wherein during off-line measurement, motor does not work, such as, measure quadrature axis inductance with RLC tester.Obviously, this is a kind of static measurement method, because motor does not work, so the inductance value when quadrature axis inductance value that this kind is measured can not reflect motor real work, and has very large error between actual quadrature axis inductance during machine operation.Online observation method observes quadrature axis inductance when the normal rotating operation of motor.Current online observation method is the first-harmonic model construction based on motor, needs the first-harmonic terminal voltage using motor in measurement.Along with the reduction of rotating speed, first-harmonic terminal voltage also declines.When rotating speed is reduced to the slow-speed of revolution and zero rotating speed, because first-harmonic terminal voltage amplitude is too little, cannot obtain by Measurement accuracy.So current online observation method is inapplicable in the slow-speed of revolution and zero rotating speed Operational Zone.How accurately observe that quadrature axis inductance value becomes motor and accurately to calculate the difficult problem that electromagnetic torque and electromagnetic torque accurately control in this region in the slow-speed of revolution and zero rotary speed area.

Make a general survey of the observation of BLDCM motor quadrature axis inductance or the measuring study present situation of current two-phase conduction mode, motor is in observation or the measuring technique comparative maturity in middle and high rotating speed district, but the observation of low speed and zero rotating speed quadrature axis inductance or a blank, and be a difficult point.

Summary of the invention

In view of this, the object of the present invention is to provide a kind of two to be conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure, under two-phase conduction mode, during low cruise, accurately observe a difficult problem for quadrature axis inductance in order to solve salient pole type permanent-magnet brushless DC electric machine.

For achieving the above object, the present invention adopts following technical scheme: a kind of two are conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure, it is characterized in that comprising the following steps:

Step S1: at threephase stator winding phase voltage u _a, u _b, u _csample, by described threephase stator winding phase voltage u _a, u _b, u _cthe corresponding high fdrequency component u injecting HF current frequency is exported after a band-pass filter _ag, u _bg, u _cg;

Step S2: by described high fdrequency component u _ag, u _bg, u _cggive a multiplier and a low pass filter successively, respectively output DC component LPF (u _agcos ω t), LPF (u _bgcos ω t), LPF (u _cgcos ω t), i.e. U _xa, U _xb, U _xc;

Step S3: by three three-position switches to DC component U _xa, U _xb, U _xcdistribute, described three three-position switches output DC component U respectively _x1, U _x2, U _x3;

Step S4: by DC component U _x1, U _x2give a subtracter, export U _x1-U _x2;

Step S5: by U _x1-U _x2and frequencies omega and high-frequency current amplitude I _mproduct ω I _mgive a divider, export the Part I of quadrature axis inductance

Step S6: according to U _x1-U _x2, U _x3, frequencies omega, high-frequency current amplitude I _mand known d-axis inductance L _d, calculate the Part II of quadrature axis inductance $L_{q2}=\frac{3U_{x3}^2}{{\mathrm{\ωI}}_m(U_{x1}-U_{x2}-{\mathrm{\ωI}}_m{L}_d)};$

Step S7: by the Part I L of quadrature axis inductance _q1with Part II L _q2give an adder, export the measured value L of quadrature axis inductance _q=(L _q1+ L _q2).

Further, in described step S1:

If the conducting of AB phase winding, then

If the conducting of BC phase winding, then

If the conducting of CA phase winding, then

Further, in described step S2:

If the conducting of AB phase winding, then

If the conducting of BC phase winding, then

If the conducting of CA phase winding, then

Further, in described step S3:

If the conducting of AB phase winding, then U _x1=U _xa, U _x2=U _xb, U _x3=U _xc;

If the conducting of BC phase winding, then U _x1=U _xb, U _x2=U _xc, U _x3=U _xa;

If the conducting of CA phase winding, then U _x1=U _xc, U _x2=U _xa, U _x3=U _xb.

Further, also step S0 is comprised before described step S1: in two of conducting is in series winding, inject that a frequency is ω, amplitude is I _mhigh-frequency current I _msin ω t realizes high-frequency current closed-loop control.

Further, the concrete steps of described step S0 are as follows:

Step S01: produce high frequency orthogonal reference signals sin ω t and cos ω t by a high frequency signal generator;

Step S02: according to high frequency sinusoidal signal sin ω t and high-frequency current amplitude I _m, calculate in winding and inject given high-frequency current $i_g^{*}=I_{m}sin\mathrm{\ω}t.$

Further, also comprise after described step S7:

Step S81: by three-phase windings current sampling data i _a, i _b, i _crespectively through exporting the corresponding high fdrequency component i injecting HF current frequency after a band-pass filter _ag, i _bg, i _cg;

Step S82: utilize three-position switch by three-phase high-frequency current i _ag, i _bg, i _cgmiddle conducting phase high-frequency current feedback obtains feedback high-frequency current i _g;

Step S83: give a high-frequency current controller by the error of described given high-frequency current and feedback high-frequency current, described high-frequency current controller exports the conducting series connection winding wire voltage given value controlling high-frequency current

Step S84: by three-phase windings current sampling data i _a, i _b, i _cbe export fundametal compoment i after the band stop filter filtering of ω respectively through a centre frequency _af, i _bf, i _cf;

Step S85: electric current PWM closed-loop control or direct torque control algorithm link are according to the fundametal compoment i of input _af, i _bf, i _cfand the measured value of quadrature axis inductance that step S7 obtains, calculate two of the conducting controlling electromagnetic torque and to be in series the given initial value of stator winding terminal voltage

Step S86: by described voltage given value and voltage given initial value give a stator winding voltage PWM link simultaneously, realize high-frequency current closed-loop control through power switch drived control converters.

The present invention compared with prior art has following beneficial effect:

1, the present invention is based on the high frequency model independent of motor first-harmonic model, achieve motor low speed and the observation of zero rotating speed quadrature axis inductance, effectively improve the accurate observation of motor low speed and zero rotating speed electromagnetic torque, improve load capacity during low speed and the operation of zero rotating speed of drive system;

2, different from existing static test, observe quadrature axis inductance can change with the change of motor quadrature axis saturation of magnetic path in the present invention, implementing rapid scan goes out real electrical machinery quadrature axis inductance value;

3, motor of the present invention still works in two-phase conducting state, reduces drive system overall losses, still maintains the succinct advantage of brshless DC motor two-phase switch control strategy;

4, the present invention is without the need to adding the accurate observation of quadrature axis inductance when any ancillary hardware circuit can realize synchronous motor low speed and zero rotating speed, and drive system hardware cost does not increase.

Accompanying drawing explanation

Fig. 1 is permanent-magnet brushless DC electric machine low speed of the present invention and zero-speed quadrature axis inductance Observation principle block diagram.

Fig. 2 is the observation system hardware structure diagram of one embodiment of the invention.

Embodiment

Below in conjunction with drawings and Examples, the present invention will be further described.

The Observation principle block diagram of the inventive method as shown in Figure 1.To feeding electric motors is any one converters that meets the demands, such as three phase inverter bridge, matrix converter etc.Permanent-magnet brushless DC electric machine three-phase windings current sampling data i _a, i _b, i _cfundametal compoment i is exported after the band stop filter filtering that centre frequency is ω _af, i _bf, i _cf; Electric current PWM closed-loop control or direct torque control algorithm link are according to the current first harmonics component i of input _af, i _bf, i _cfand the quadrature axis inductance value of observation, calculate two being in series the given initial value of stator winding terminal voltage of conducting for controlling torque the present invention is directed to two-phase conduction mode salient pole type permanent-magnet brushless DC electric machine low speed and zero-speed ruuning situation, propose a kind of novel high-frequency pulsating current and inject quadrature axis inductance observation procedure.Be provided with four three-position switch S ₁, S ₂, S ₃, S ₄, 1,2,3 three position conducting of corresponding motor winding AB phase winding, the conducting of BC phase winding, CA phase winding conducting situation respectively of switch.Under motor winding is in a certain conducting situation, three-phase phase voltage u _a, u _b, u _cbe the band pass filter of ω respectively through centre frequency, will wherein corresponding high fdrequency component u _ag, u _bg, u _cgextract; After three road frequency voltage components give three multipliers, low pass filter respectively successively, export the DC component LPF (u after signal receiving _agcos ω t), LPF (u _bgcos ω t), LPF (u _cgcos ω t); By DC component LPF (u later for demodulation _agcos ω t), LPF (u _bgcos ω t), LPF (u _cgcos ω t) give three switch S determined mutually by conducting ₂, S ₃, S ₄, three switch output DC component U successively _x1, U _x2, U _x3; By U _x1, U _x2, U _x3, product term ω I _m(wherein I _mbe respectively with ω and inject high-frequency current amplitude and frequency), product term ω I _ml _dgive quadrature axis inductance L _qcalculate link and export quadrature axis inductance measured value (L _dand L _qbe respectively motor dq axle inductance).Conducting connect two phase winding high-frequency current inject adopt closed-loop controls, three-phase windings current sampling data i _a, i _b, i _chigh fdrequency component i is exported after band-pass filter _ag, i _bg, i _cg; Based on conducting phase situation, utilize switch S ₁by three-phase high-frequency current i _ag, i _bg, i _cgmiddle conducting phase high-frequency current feedback obtains feedback high-frequency current i _g; According to given high-frequency current and feedback high-frequency current, its error gives high-frequency current controller, exports the conducting series connection winding wire voltage given value controlling high-frequency current high frequency voltage is given with conducting series connection winding wire voltage fundamental voltage given give stator winding voltage PWM link simultaneously, then through power switch drived control converters, in figure for series connection two-phase winding wire voltage given value, realize motor torque closed-loop control, in two phase windings are connected in conducting, inject high-frequency current I simultaneously _msin ω t.The quadrature axis inductance measured value replacement needed in electric current PWM control or direct torque control algorithm can be realized the accurate calculating of electromagnetic torque when permanent-magnet brushless DC electric machine low speed and zero-speed operation and accurately control, improve the low speed load capacity of drive system and the stability of low cruise.

Be illustrated in figure 2 the observation system hardware structure diagram of one embodiment of the invention, comprise: rectification circuit, filter capacitor, three-phase inverter, salient pole type permanent-magnet brushless DC electric machine, three-phase windings current collection circuit, three-phase windings phase voltage Acquisition Circuit, three-phase windings phase voltage band pass filter, isolation drive, central controller, man-machine interface.Also suitable DC power supply can be adopted to provide three-phase inverter DC bus-bar voltage.In inverter, power tube adopts IGBT or MOFET, and central controller adopts DSP or single-chip microcomputer.Winding current Acquisition Circuit adopts Hall current sensor to form with the operational amplifier mode of combining, and connects the differential operational amplifier mode of combining and form after also can adopting winding string power resistor.Adopt Hall scheme effectively can realize the electrical isolation of control loop and major loop, adopt winding string power resistor scheme can reduce drive system cost.Winding phase voltage Acquisition Circuit adopts Hall voltage transducer to form with the operational amplifier mode of combining, and also can adopt parallel resistance, connect the voltage follower mode of combining be made up of operational amplifier and form after dividing potential drop.Three-phase windings phase voltage band pass filter can adopt resistance, electric capacity and operational amplifier to build, also can according to winding phase voltage collection value software simulating.Winding current Acquisition Circuit and winding phase voltage Acquisition Circuit export (or three-phase windings phase voltage band pass filter exports), and weak voltage signal delivers to central controller A/D modular converter.Quadrature axis inductance is observed according to the signal obtained and quadrature axis inductance observation procedure of the present invention.

After considering motor salient pole phenomenon, in being in series winding at motor two, injected frequency is the high-frequency signal of ω, and ω > > ω _r, namely in the very low situation of motor speed, motor high-frequency signal voltage equilibrium equation is as follows:

Wherein, ω _rfor the angular rate that actual rotor rotates, θ _rfor rotor position angle, L _d, L _qbe respectively the d-axis and q-axis inductance of motor.

If inject high-frequency current in (a) AB phase winding, and i _ag=-i _bg=I _msin ω t, i _cg=0, then as follows by obtaining corresponding three-phase frequency voltage components in three-phase current expression formula substitution (formula 1):

By frequency voltage components u _ag, u _bg, u _cgmultiplied with high-frequency reference signal cos ω t phase successively:

By u _agcos ω t, u _bgcos ω t, u _cgcos ω t is after 0.1 ω low pass filter filtering respectively through cut-off frequency:

In order to observe quadrature axis inductance, obtain according to (formula 8)-(formula 9):

Due to function cos (2 θ _r+ 150 °) and cos (2 θ _r+ 60 °) orthogonal, so obtain according to (formula 10) ~ (formula 11):

${\left(\frac{1}{\sqrt{3}}\right(U_{xa}-U_{xb})-\frac{1}{2}{\mathrm{\ωI}}_m\frac{1}{\sqrt{3}}(L_d+L_q\left)\right)}^2+U_{xc}^2={\left(\frac{1}{2}{\mathrm{\ωI}}_m\frac{1}{\sqrt{3}}\right(L_d-L_q\left)\right)}^2$ (formula 12)

Quadrature axis inductance is calculated further as follows according to formula 12:

$L_q=\frac{U_{xa}-U_{xb}}{{\mathrm{\ωI}}_m}+\frac{3U_{xc}^2}{{\mathrm{\ωI}}_m(U_{xa}-U_{xb}-{\mathrm{\ωI}}_m{L}_d)}$ (formula 13) is if inject high-frequency current in (b) BC phase winding, and i _bg=-i _cg=I _msin ω t, i _ag=0, then three-phase current is expressed

Formula substitutes in (formula 1) to be similar in (a) derives corresponding three-phase dc component of voltage is as follows:

Be similar in (a) and derive, obtain quadrature axis inductance computing formula according to (formula 14)-(formula 16) as follows:

$L_q=\frac{U_{xb}-U_{xc}}{{\mathrm{\ωI}}_m}+\frac{3U_{xa}^2}{{\mathrm{\ωI}}_m(U_{xb}-U_{xc}-{\mathrm{\ωI}}_m{L}_d)}$ (formula 17)

If inject high-frequency current in (c) CA phase winding, and i _cg=-i _ag=I _msin ω t, i _bg=0, then three-phase current is expressed

Formula substitutes in (formula 1) to be similar in (a) derives corresponding three-phase dc component of voltage is as follows:

Be similar in (a) and derive, obtain quadrature axis inductance computing formula according to (formula 18)-(formula 20) as follows:

$L_q=\frac{U_{xc}-U_{xa}}{{\mathrm{\ωI}}_m}+\frac{3U_{xb}^2}{{\mathrm{\ωI}}_m(U_{xc}-U_{xa}-{\mathrm{\ωI}}_m{L}_d)}$ (formula 21)

The foregoing is only preferred embodiment of the present invention, all equalizations done according to the present patent application the scope of the claims change and modify, and all should belong to covering scope of the present invention.

Claims (7)

1. two to be conducted permanent-magnet brushless DC electric machine low speed and a zero-speed quadrature axis inductance observation procedure, to it is characterized in that comprising the following steps:

Step S1: to threephase stator winding phase voltage u _a, u _b, u _csample, by described threephase stator winding phase voltage u _a, u _b, u _cthe corresponding high fdrequency component u injecting HF current frequency is exported after a band-pass filter _ag, u _bg, u _cg;

Step S2: by described high fdrequency component u _ag, u _bg, u _cggive a multiplier and a low pass filter successively, respectively output DC component LPF (u _agcos ω t), LPF (u _bgcos ω t), LPF (u _cgcos ω t), i.e. U _xa, U _xb, U _xc;

Step S3: by three three-position switches to DC component U _xa, U _xb, U _xcdistribute, described three three-position switches output DC component U respectively _x1, U _x2, U _x3;

Step S4: by DC component U _x1, U _x2give a subtracter, export U _x1-U _x2;

Step S5: by U _x1-U _x2and frequencies omega and high-frequency current amplitude I _mproduct ω I _mgive a divider, export the Part I of quadrature axis inductance

Step S6: according to U _x1-U _x2, U _x3, frequencies omega, high-frequency current amplitude I _mand known d-axis inductance L _d, calculate the Part II of quadrature axis inductance

Step S7: by the Part I L of quadrature axis inductance _q1with Part II L _q2give an adder, export the measured value L of quadrature axis inductance _q=(L _q1+ L _q2).

2. according to claim 1 two to be conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure, to it is characterized in that: in described step S1:

If the conducting of AB phase winding, then

If the conducting of BC phase winding, then

If the conducting of CA phase winding, then

3. according to claim 2 two to be conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure, to it is characterized in that: in described step S2:

If the conducting of AB phase winding, then

If the conducting of BC phase winding, then

If the conducting of CA phase winding, then

4. according to claim 3 two to be conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure, to it is characterized in that: in described step S3:

If the conducting of AB phase winding, then U _x1=U _xa, U _x2=U _xb, U _x3=U _xc;

If the conducting of BC phase winding, then U _x1=U _xb, U _x2=U _xc, U _x3=U _xa;

If the conducting of CA phase winding, then U _x1=U _xc, U _x2=U _xa, U _x3=U _xb.

5. according to claim 1 two to be conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure, to it is characterized in that: before described step S1, also comprise step S0: in two of conducting is in series winding, injects that a frequency is ω, amplitude is I _mhigh-frequency current I _msin ω t realizes high-frequency current closed-loop control.

6. two-phase conducting type permanent-magnet brushless DC electric machine low speed according to claim 5 and zero-speed quadrature axis inductance observation procedure, is characterized in that: the concrete steps of described step S0 are as follows:

Step S01: produce high frequency orthogonal reference signals sin ω t and cos ω t by a high frequency signal generator;

Step S02: according to high frequency sinusoidal signal sin ω t and high-frequency current amplitude I _m, calculate in winding and inject given high-frequency current $i_g^{*}=I_{m}sin\mathrm{\ω}t.$

7. according to claim 6 two to be conducted permanent-magnet brushless DC electric machine low speed and zero-speed quadrature axis inductance observation procedure, to it is characterized in that: also comprise after described step S7:

Step S81: by three-phase windings current sampling data i _a, i _b, i _crespectively through exporting the corresponding high fdrequency component i injecting HF current frequency after a band-pass filter _ag, i _bg, i _cg;

Step S82: utilize three-position switch by three-phase high-frequency current i _ag, i _bg, i _cgmiddle conducting phase high-frequency current feedback obtains feedback high-frequency current i _g;

Step S83: give a high-frequency current controller by the error of described given high-frequency current and feedback high-frequency current, described high-frequency current controller exports the conducting series connection winding wire voltage given value controlling high-frequency current

Step S84: by three-phase windings current sampling data i _a, i _b, i _cbe export fundametal compoment i after the band stop filter filtering of ω respectively through a centre frequency _af, i _bf, i _cf;

Step S85: electric current PWM closed-loop control or direct torque control algorithm link are according to the fundametal compoment i of input _af, i _bf, i _cfand the measured value of quadrature axis inductance that step S7 obtains, calculate the conducting two controlling electromagnetic torque and to be in series the given initial value of stator winding terminal voltage

Step S86: by described voltage given value and voltage given initial value give a stator winding voltage PWM link simultaneously, realize high-frequency current closed-loop control through power switch drived control converters.