CN203251268U - Permanent magnet synchronous motor control system based on automatic zero set of encoder - Google Patents

Abstract

The utility model discloses a permanent magnet synchronous motor control system based on automatic zero set of an encoder. The system is characterized by comprising an increment type encoder, a stator current acquisition unit, a zero detection unit, a rotor information calculating unit, a control unit and a modulation unit. The increment type encoder is connected with the zero detection unit and the rotor information calculating unit; the stator current acquisition unit is connected with the zero detection unit and the control unit; the zero detection unit is connected with the rotor information calculating unit, the control unit and the modulation unit; the rotor information calculating unit is connected with the control unit; the control unit is connected with the modulation unit; the increment type encoder is arranged on a main shaft of the motor; the stator current acquisition unit is connected with a three-phase winding of the motor stator; the modulation unit provides PW signals for a motor inverter through a drive circuit.

Description

A kind of control system for permanent-magnet synchronous motor based on encoder automatic zero set

Technical field

The utility model belongs to the electric machines control technology field, is specifically related to a kind of method for controlling permanent magnet synchronous motor based on encoder automatic zero set and system.

Background technology

Along with developing rapidly of science and technology, servo-control system obtains using very widely in many high-tech areas, such as robot control, Digit Control Machine Tool, large scale integrated circuit manufacturing, office automation, flexible manufacturing system, Aero-Space, radar and various military weapon system for tracking etc.Servo system is used permagnetic synchronous motor more in the market, and will realize that the high accuracy control of high-performance permanent magnet synchronous servo system need to obtain rotor-position signal constantly.The main method that existing permanent magnet synchronous servo motor rotor-position detects can be divided into mechanical position sensor and sensorless detection two large classes.Wherein mechanical pick-up device mainly contains resolver method, photoelectric encoder method (absolute type and increment type).Mainly contain the high order harmonic component injection method without sensor method, based on back-emf detection method etc.But these methods respectively have its weak point:

The voltage signal that the output of resolver method is relevant with rotor-position need to carry out demodulation for obtaining rotor-position, and the dedicated decoders of using is expensive; The absolute optical encoder detection method can be exported the multidigit binary system, and the multidigit binary system is corresponding one by one with rotor-position, but photoelectric encoder code-disc road number is limited, and positioning accuracy is received very large impact.The parallel transmission of synchronous signal goes between more, increases the system complex degree, reduces system reliability.

The incremental optical-electricity encoder detection method is the highest method of Vehicles Collected from Market employing rate, and it has the characteristics such as positioning accuracy is high, algorithm application is ripe, and is with low cost.But the method output is not the rotor absolute position signal, therefore needs before use artificial zeroing.The method that at present artificial zeroing is adopted is to apply the specific voltage vector to permagnetic synchronous motor, it is fixed on the fixed position after, repeatedly adjust by observing encoder output U phase signals and Z pulse signal.Not only step is numerous and diverse, needs additional means, simultaneously operating personnel is also had certain specification requirement.Do not apply the specific voltage vector in the situation that know original position of electric motor's rotator in addition, the situation of rotor counter-rotating can occur.This does not allow to occur in a part of permagnetic synchronous motor.

Though the back-emf detection method need not increase extras, its poor robustness, high to the requirement of current detecting equipment accuracy, more fatal is under low speed and zero-speed operation, can't accurately obtain motor rotor position.

Yan Shuai etc. are permanent magnet ac servo system and Advanced Control Strategies research (Harbin Institute of Technology's doctorate paper thereof at title, pp.11-12, in April, 2009) document has been pointed out the application of High Frequency Injection, solved the problem of low speed lower rotor part position probing, but when detection signal, not only require high to hardware device, while many places on signal is processed use band pass filter and synchronizing shaft is high pass filter, can introduce certain time lag and phase place hysteresis, can not finely satisfy high accuracy SVPWM(space vector pulse width modulation) the control requirement, concurrently injected high-frequency signal is in operation and can introduces larger noise.

Summary of the invention

For the existing above-mentioned technical problem of prior art, the utility model provides a kind of method for controlling permanent magnet synchronous motor based on encoder automatic zero set and system, need not to carry out the encoder hand reset, accurately the detection rotor position.

A kind of method for controlling permanent magnet synchronous motor based on encoder automatic zero set comprises the steps:

(1) the threephase stator electric current of collection motor, utilize incremental encoder to obtain rotor-position delta pulse signal and the rotor Z pulse signal of motor, and the threephase stator electric current is carried out the Clarke conversion obtain the component of threephase stator electric current under the alpha-beta rest frame;

(2) carry out the encoder zero testing according to component and described rotor-position delta pulse signal and the rotor Z pulse signal of threephase stator electric current under the alpha-beta rest frame, obtain encoder zero compensation amount;

(3) according to rotor-position delta pulse signal, rotor Z pulse signal and encoder zero compensation amount, calculate rotor position angle and the rotating speed of motor;

(4) for first control cycle, the autonomous α axle component U of formation voltage instruction under the alpha-beta rest frame _{α 1}With beta-axis component U _{β 1}, and then obtain one group of pwm signal so that motor inverter is controlled by the SVPWM technical construction;

For second control cycle, according to the component of threephase stator electric current under the alpha-beta rest frame, extract the just angle measurement of rotor-position of motor; According to the first α axle component U of angle measurement formation voltage instruction under the alpha-beta rest frame of rotor-position _{α 2}With beta-axis component U _{β 2}, and then obtain one group of pwm signal so that motor inverter is controlled by the SVPWM technical construction;

For after other control cycles, according to the rotor position angle of motor and rotating speed by motor control strategy, the α axle component U of formation voltage instruction under the alpha-beta rest frame _αWith beta-axis component U _β, and then obtain one group of pwm signal so that motor inverter is controlled by the SVPWM technical construction.

In the described step (2), carry out by the following method the encoder zero testing:

A1. according to the component of threephase stator electric current under the alpha-beta rest frame, extract the just angle measurement of rotor-position of motor;

A2. the position of magnetic pole identification is carried out in component and the just angle measurement of described rotor-position under the alpha-beta rest frame according to the threephase stator electric current, generates initial position angle of rotor;

A3. pass through the rotor positioning mode according to initial position angle of rotor, determine rotor location voltage vector and the electrical degree under the three phase static coordinate system thereof;

A4. according to rotor-position delta pulse signal, rotor Z pulse signal and the electrical degree of rotor location voltage vector under the three phase static coordinate system, calculate encoder zero compensation amount.

The specific implementation of described steps A 3 rotor positioning modes is as follows: at first, determine motor inverter voltage vector to the motor input under various switch combinations in the three phase static coordinate system; Then, determine the position vector of initial position angle of rotor correspondence in the three phase static coordinate system; At last, getting this position vector is rotor location voltage vector along the immediate voltage vector of coordinate para-electric machine direct rotational direction.

In the described steps A 4, according to following formula calculation code device zero compensation amount:

$N=M+\frac{{\mathrm{\θ}}_{e}Q}{360p}$

Wherein: N is encoder zero compensation amount, θ _eBe the electrical degree of rotor location voltage vector under the three phase static coordinate system, p is the number of pole-pairs of motor, Q is the grid sum of encoder, the pulse tale that M occurs for the time period internal rotor positional increment pulse signal of exporting first rotor Z pulse signal from electric motor starting to encoder.

In the described step (3), calculate rotor position angle and the rotating speed of motor according to following formula:

${\mathrm{\θ}}_r=\frac{360p(X+N)}{Q}$

${\mathrm{\ω}}_r=\frac{d{\mathrm{\θ}}_r}{\mathrm{dt}}$

Wherein: θ _rAnd ω _rBe respectively rotor position angle and rotating speed, t is the time, and p is the number of pole-pairs of motor, and Q is the grid sum of encoder, and X is for exporting arbitrary rotor Z pulse signal to the pulse tale of the time period internal rotor positional increment pulse signal appearance of current time from encoder.

In the described step (4), for first control cycle, the autonomous α axle component U of formation voltage instruction under the alpha-beta rest frame _{α 1}With beta-axis component U _{β 1}U _{α 1}=U _{β 1}=U _mCos ω _hT, U _mAnd ω _hBe respectively default voltage magnitude and electric voltage frequency, t is the time.

In the described step (4), for second control cycle, according to the component of threephase stator electric current under the alpha-beta rest frame, extract the just angle measurement of rotor-position of motor; According to just angle measurement of rotor-position to the d axle component U of voltage instruction under the d-q rotating coordinate system _dWith q axle component U _qCarry out the Park inverse transformation, obtain the α axle component U of voltage instruction under the alpha-beta rest frame _{α 2}With beta-axis component U _{β 2}U _d=U _mCos ω _Ht, U _q=0, U _mAnd ω _hBe respectively default voltage magnitude and electric voltage frequency, t is the time.

Preferably, in the described step (4), for after other control cycles, according to the rotor position angle of motor and rotating speed by Magnetic Field Oriented Control Strategies, the α axle component U of formation voltage instruction under the alpha-beta rest frame _αWith beta-axis component U _βThis control strategy is constant by the excitation component of keeping stator current, the torque component of control electric current, and the linear Torque Control of realization motor has good dynamic, accurate speed control; The optimal control current phasor obtains the maximum moment under the lowest loss, makes permagnetic synchronous motor obtain peak performance in whole speed range.

A kind of control system for permanent-magnet synchronous motor based on encoder automatic zero set comprises:

Incremental encoder is for the rotor-position delta pulse signal and the rotor Z pulse signal that gather motor;

The stator current collecting unit be used for to gather motor threephase stator electric current, and described threephase stator electric current is carried out the Clarke conversion obtains the component of threephase stator electric current under the alpha-beta rest frame;

The zero testing unit, be used for carrying out the encoder zero testing according to component and described rotor-position delta pulse signal and the rotor Z pulse signal of threephase stator electric current under the alpha-beta rest frame, obtain encoder zero compensation amount and initial voltage instruction;

Rotor information calculations unit is used for according to rotor-position delta pulse signal, rotor Z pulse signal and encoder zero compensation amount, calculates rotor position angle and the rotating speed of motor;

Control unit is used for according to component and described rotor position angle and the rotating speed of threephase stator electric current under the alpha-beta rest frame, constructs the control voltage instruction by motor control strategy;

Modulating unit is used for obtaining one group of pwm signal so that motor inverter is controlled according to described initial voltage instruction or control voltage instruction by the SVPWM technical construction.

Wherein, incremental encoder links to each other with rotor information calculations unit with the zero testing unit, the stator current collecting unit links to each other with control unit with the zero testing unit, the zero testing unit links to each other with modulating unit with rotor information calculations unit, control unit, rotor information calculations unit links to each other with control unit, and control unit links to each other with modulating unit; Incremental encoder is located on the electric machine main shaft, and the stator current collecting unit is connected with motor stator three phase windings, and modulating unit provides pwm signal by drive circuit for motor inverter.

Described zero testing unit comprises:

Rotor-position Preliminary detection module is used for according to the component of threephase stator electric current under the alpha-beta rest frame, extracts the just angle measurement of rotor-position of motor;

Initial order generation module is used for autonomous generation initial voltage instruction or just angle measurement generates the initial voltage instruction according to described rotor-position;

The position of magnetic pole recognition module is used for according to the threephase stator electric current component and the just angle measurement of described rotor-position under the alpha-beta rest frame and carries out the position of magnetic pole identification, generates initial position angle of rotor;

The rotor locating module is used for passing through the rotor positioning mode according to initial position angle of rotor, determines rotor location voltage vector and the electrical degree under the three phase static coordinate system thereof;

The zero compensation module is used for calculating encoder zero compensation amount according to rotor-position delta pulse signal, rotor Z pulse signal and the electrical degree of rotor location voltage vector under the three phase static coordinate system.

Wherein, rotor-position Preliminary detection module links to each other with the position of magnetic pole recognition module with stator current collecting unit, initial order generation module, initial order generation module links to each other with modulating unit, the position of magnetic pole recognition module links to each other with the rotor locating module, the rotor locating module links to each other with control unit with the zero compensation module, and the zero compensation module links to each other with rotor information calculations unit with incremental encoder.

The beneficial effects of the utility model are:

(1) the utility model adopts improved high frequency signal injection method detection rotor initial position, and clear and definite rotor initial alignment conveniently applies directional vector, avoids occuring the rotor reversal development;

(2) the utility model rotor locating module is chosen the voltage vector the most close with this position and is applied after obtaining initial position of rotor, to avoid that back and forth oscillatory occurences of rotor occurs when locating;

(3) the utility model carries out the encoder zero compensation automatically, and offset is carried out convenient storage directly call in the future, saves the trouble of artificial zeroing; In case need calibration or rezeroing, only need utilize this device operation once, encoder is accurate zero adjustment again just in the future, and process is easy, and accuracy is high.

(4) the utility model only injects high-frequency voltage signal before the rotor initial alignment, can not bring phase place to lag behind and time lag to system's operation, and the introducing noise more can not be in operation.

Description of drawings

Fig. 1 is the structural representation of the utility model permagnetic synchronous motor and control system thereof.

Fig. 2 is the structural principle schematic diagram of rotor-position Preliminary detection module.

Fig. 3 is the structural principle schematic diagram of position of magnetic pole recognition module.

Fig. 4 is the vector schematic diagram that the rotor locating module carries out the rotor location.

Fig. 5 is the schematic diagram of encoder capable of automatic performing zero compensation.

Embodiment

In order more specifically to describe the utility model, below in conjunction with the drawings and the specific embodiments the technical solution of the utility model and operation principle thereof are elaborated.

The control object of present embodiment is the permagnetic synchronous motor system, and it comprises direct voltage source, three-phase inverter and permagnetic synchronous motor; Powered by direct voltage source, by three-phase inverter, direct current is become alternating current and link to each other with the permanent-magnetic synchronous motor stator input behind the direct voltage source output terminal electric capacity of voltage regulation in parallel.Three-phase inverter is comprised of power switch pipe and fly-wheel diode, and some power switch pipe contains fly-wheel diode, then can omit independently fly-wheel diode and uses built-in fly-wheel diode.

As shown in Figure 1, a kind of control system for permanent-magnet synchronous motor based on encoder automatic zero set comprises: incremental encoder, stator current collecting unit, zero testing unit, rotor information calculations unit, control unit and modulating unit; Wherein:

Incremental encoder is used for gathering the rotor-position delta pulse signal θ of motor _iWith rotor Z pulse signal z, it is installed on the electric machine main shaft; It is the incremental optical-electricity encoder of TS6014N135 that the present embodiment incremental encoder adopts the Japanese river company model of rubbing more.

The stator current collecting unit is used for gathering motor threephase stator current i _a～i _c, and to the threephase stator current i _a～i _cCarry out the Clarke conversion and obtain the component i of threephase stator electric current under the alpha-beta rest frame _α, i _βThe stator current collecting unit is by structures such as Hall current sensors; The transformation matrix of Clarke conversion is as follows:

$T_{\mathrm{abc}/\mathrm{\α\β}}=\sqrt{\frac{3}{2}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& \frac{\sqrt{3}}{2}\end{array}\right]$

The zero testing unit is used for according to the component i of threephase stator electric current under the alpha-beta rest frame _α, i _βAnd rotor-position delta pulse signal θ _iZ carries out the encoder zero testing with rotor Z pulse signal, obtains encoder zero compensation amount N and initial voltage instruction; In the present embodiment, the zero testing unit adopts DSP, is loaded with rotor-position Preliminary detection module, initial order generation module, position of magnetic pole recognition module, rotor locating module and zero compensation module on the DSP; Wherein:

Rotor-position Preliminary detection module is used for according to the component i of threephase stator electric current under the alpha-beta rest frame _α, i _β, the rotor-position that extracts motor is angle measurement θ just ₀, specific implementation as shown in Figure 2;

Stator voltage equation and the magnetic linkage equation of permagnetic synchronous motor under the d'q' coordinate system of any two-phase is respectively:

$\left\{\begin{array}{c}{u}_d^{\′}={\mathrm{Ri}}_d^{\′}+{\mathrm{p\ψ}}_d^{\′}-{\mathrm{\ω}}^{\′}{\mathrm{\ψ}}_q^{\′}\\ u_q^{\′}={\mathrm{Ri}}_q^{\′}+{\mathrm{p\ψ}}_q^{\′}+{\mathrm{\ω}}^{\′}{\mathrm{\ψ}}_d^{\′}\end{array}\right.$

$\left\{\begin{array}{c}{\mathrm{\ψ}}_d^{\′}=[L_{s0}+L_{s2}\cos (2\mathrm{\θ}-{2\mathrm{\θ}}^{\′})]i_d^{\′}+L_{s2}\sin (2\mathrm{\θ}-{2\mathrm{\θ}}^{\′})i_q^{\′}+{\mathrm{\ψ}}_f\cos (\mathrm{\θ}-{\mathrm{\θ}}^{\′})\\ {\mathrm{\ψ}}_q^{\′}=L_{s2}\sin (2\mathrm{\θ}-{2\mathrm{\θ}}^{\′})i_d^{\′}+[L_{s0}-L_{s2}\cos (2\mathrm{\θ}-{2\mathrm{\θ}}^{\′})]i_q^{\′}+{\mathrm{\ψ}}_f\sin (\mathrm{\θ}-{\mathrm{\θ}}^{\′})\end{array}\right.$

In above-mentioned two formulas, u _d', u _q' be the axial voltage of stator dq under any two-phase d'q' coordinate system; Ψ _d', Ψ _q' be dq axle magnetic linkage in the motor under any two-phase d'q' coordinate system; i _d', i _q' be the stator dq shaft current under any two-phase d'q' coordinate system; Ψ _fBe the rotor permanent magnet magnetic linkage; P is differential operator, L _S0Be coefficient of self-inductance mean value, L _S2Be coefficient of self-inductance 2 subharmonic amplitudes, θ ' is the angle between the α axle (being the phase axle of A phase) in d' axle and static two phase coordinate systems; θ is the angle of rotor permanent magnet and α axle, also is the angle of d axle and α axle.When to motor stator α, the β axle injects high-frequency voltage signal u _{α 1}=u _{β 1}=U _mCos ω _hBehind the t, obtain the current i under the stator three phase static coordinate system _a, i _b, after the Clarke conversion, obtain α, the current i under the β two-phase rest frame _α, i _β:

$\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\frac{U_m}{(L_{s0}^2-L_{s2}^2){\mathrm{\ω}}_h}\left[\begin{array}{c}{L}_{s0}-{\sqrt{2}L}_{s2}\cos (2\mathrm{\θ}-\mathrm{\π}/4)\\ L_{s0}-{\sqrt{2}L}_{s2}\sin (2\mathrm{\θ}-\mathrm{\π}/4)\end{array}\right]{\sin \mathrm{\ω}}_{h}t$

With above-mentioned two electric currents respectively with sin ω _hT does product calculation, and with resulting two signals after the computing by after the filter elimination high fdrequency component, obtain two α that the amplitude size is subjected to the rotor-position modulation, the amplitude signal I under the β two-phase rest frame _α, I _β:

$\left[\begin{array}{c}{I}_{\mathrm{\α}}\\ I_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{c}\mathrm{LPF}\left(i_{\mathrm{\α}}\sin {\mathrm{\ω}}_{h}t\right)\\ \mathrm{LPF}\left(i_{\mathrm{\β}}\sin {\mathrm{\ω}}_{h}t\right)\end{array}\right]=\frac{U_m}{2(L_{s0}^2-L_{s2}^2){\mathrm{\ω}}_h}\left[\begin{array}{c}{L}_{s0}-{\sqrt{2}L}_{s2}\cos (2\mathrm{\θ}-\mathrm{\π}/4))\\ L_{s0}-{\sqrt{2}L}_{s2}\sin (2\mathrm{\θ}-\mathrm{\π}/4)\end{array}\right]$

Again above-mentioned amplitude signal is deducted respectively the direct current biasing component

After, and definition $k=\frac{\sqrt{2}{U}_m{L}_{s2}}{2(L_{s0}^2-L_{s2}^2){\mathrm{\ω}}_h},$ Can obtain:

$\left[\begin{array}{c}{I}_{\mathrm{\α\θ}}\\ I_{\mathrm{\β\θ}}\end{array}\right]=k\left[\begin{array}{c}-\cos (2\mathrm{\θ}-\mathrm{\π}/4)\\ -\sin (2\mathrm{\θ}-\mathrm{\π}/4)\end{array}\right]$

At last, obtain I by two current signal amplitudes that will obtain after divided by k _{α θ}/ k, I _{β θ}/ k., under the condition between 0～π, according to the size of above-mentioned two signal values, find the solution the result that inverse function obtains and be preliminary survey rotor-position signal θ at hypothesis electrical degree θ ₀

Initial order generation module is for autonomous generation initial voltage instruction or according to the first angle measurement θ of rotor-position ₀Generate the initial voltage instruction; For first control cycle, the α axle component u of the autonomous formation voltage instruction of initial order generation module under the alpha-beta rest frame _{α 1}With beta-axis component u _{β 1}, u _{α 1}=u _{β 1}=U _mCos ω _hT, U _mAnd ω _hBe respectively default voltage magnitude and electric voltage frequency; For second control cycle, initial order generation module is according to the first angle measurement θ of rotor-position ₀To the d axle component u of voltage instruction under the d-q rotating coordinate system _dWith q axle component u _qCarry out the Park inverse transformation, obtain the α axle component u of voltage instruction under the alpha-beta rest frame _{α 2}With beta-axis component u _{β 2}u _d=U _mCos ω _hT, u _q=0; In the present embodiment, U _m=40V, ω _h=400Hz.

The transformation matrix of Park inverse transformation is as follows:

$T_{\mathrm{dq}/\mathrm{\α\β}}=\left[\begin{array}{cc}\cos {\mathrm{\θ}}_0& -\sin {\mathrm{\θ}}_0\\ \sin {\mathrm{\θ}}_0& \cos {\mathrm{\θ}}_0\end{array}\right]$

The position of magnetic pole recognition module is used for according to the component i of threephase stator electric current under the alpha-beta rest frame _α, i _βAnd the first angle measurement θ of rotor-position ₀Carry out the position of magnetic pole identification, generate initial position angle of rotor θ, specific implementation as shown in Figure 3;

When rotor-position Preliminary detection module is extracted just measured value θ of initial position of rotor ₀After, initial order generation module is according to θ ₀And given appropriate voltage amplitude U _mAnd electric voltage frequency ω _h, only (the A axle rotates θ along positive direction to permagnetic synchronous motor d' axle ₀Rear residing position) injects initial voltage instruction, i.e. u _d'=U _mCos ω _hT, u _qD' shaft current i under the two-phase synchronous rotating frame is detected and be converted in '=0 _d':

$i_d^{\′}=\frac{U_m}{(L_{s0}+L_{s2}){\mathrm{\ω}}_h}\sin {\mathrm{\ω}}_{h}t=I_d^{\′}\sin {\mathrm{\ω}}_{h}t$

Work as ω _hDuring the t=pi/2, u _d' (pi/2)=0, i _d' (pi/2)=U _m/ (L _S0+ L _S2) ω _h=I ₁, record d' shaft current this moment amplitude | I ₁|; Work as ω _hDuring the t=3 pi/2, u _d' (pi/2)=0, i _d' (pi/2)=-U _m/ (L _S0+ L _S2) ω _h=-I ₂, record d' shaft current this moment amplitude | I ₂|.If in the interval that the rotor magnetic pole direction is supposed, work as ω when using look-up table before _hDuring the t=pi/2, the magnetic potential that stator current produces is consistent with d axle positive direction, and magnetic circuit is saturated, stator d axle inductance L _S0+ L _S2Diminish, | I ₁| larger; Work as ω _hDuring the t=3 pi/2, the magnetic potential that stator current produces is opposite with d axle positive direction, and magnetic circuit moves back saturated, L _S0+ L _S2Become large, | I ₂| less, therefore | I ₁| | I ₂|; If the rotor magnetic pole direction not in the hypothesis interval, namely the actual rotor position with the position of preliminary survey position opposite.Work as ω _hDuring the t=pi/2, the magnetic potential that stator current produces is opposite with the d direction of principal axis, and magnetic circuit moves back saturated, stator d axle inductance L _S0+ L _S2Become large, | I ₁| less; Work as ω _hDuring the t=3 pi/2, | I ₂| larger.Therefore have | I ₁|＜| I ₂|.Show that the real positive direction of d axle is opposite with hypothesis, θ ₀Add electrical degree π.

Record respectively ω _hT=pi/2 and ω _hTwo moment of t=3 pi/2 d shaft current, through behind the filter filtering, to two current amplitudes | I ₁|, | I ₂| carry out size relatively, just obtained the identification result θ of rotor magnetic pole position.

The rotor locating module is used for passing through the rotor positioning mode according to initial position angle of rotor θ, determines rotor location voltage vector and the electrical degree θ under the three phase static coordinate system thereof _eThe specific implementation of rotor positioning mode as shown in Figure 4; At first, in the three phase static coordinate system, determine motor inverter voltage vector to the motor input under various switch combinations; Among the figure with three reference axis of the solid line vector representation motor three phase static coordinate system of three letters of ABC, solid line vector representation rotor magnetic pole N utmost point present position (being position vector corresponding to initial position angle of rotor θ) with alphabetical d, the numbered dotted line vector representation of other 12 bands three-phase inverter power switch can be to the voltage vector of permanent-magnetic synchronous motor stator end input lower of different conductings and shutoff combination, the wherein upper pipe conducting of this phase of "+" expression inverter in the subscript of letter, this voltage vector that applies mutually is same with this phase axle positive direction; The lower pipe conducting of this phase of "-" expression inverter in the subscript of letter, this voltage vector that applies mutually is opposite with this phase axle positive direction; Do not have certain mutually letter represent that then this phase does not apply voltage; The voltage vector that finally is applied to stator terminal be applied to each phase voltage vector vector and.After the rotor locating module obtained initial position of rotor θ, getting initial position angle of rotor θ corresponding position vector in the three phase static coordinate system was rotor location voltage vector along the immediate voltage vector of coordinate para-electric machine direct rotational direction.

The zero compensation module is used for according to rotor-position delta pulse signal θ _i, the electrical degree θ of rotor Z pulse signal z and rotor location voltage vector under the three phase static coordinate system _e, calculate encoder zero compensation amount N.Fig. 5 is the schematic diagram that the zero compensation module realizes automatic zero compensation; Under normal circumstances, after manually returning to zero, the grid of Z pulse signal overlaps with rotor d axle on the code-disc, the encoder light-sensitive element, and photoelectric receiving tube overlaps with stator A axle.In service at motor, when the rotor N utmost point turns to and just overlaps with stator A axle, encoder output Z pulse signal.The Z pulse signal that the controller utilization is caught carries out the zero clearing of all countings: being clear and definite absolute position on the one hand, is to eliminate accumulated error on the other hand.And correspond in the present embodiment, as shown in Figure 5, after encoder was installed arbitrarily, fixing light-sensitive element and stator A axle had a fixed angle poor, and Z pulse signal grid also has a fixed angle poor with rotor d axle on the code-disc.D axle position is that controller applies the rotor-position after rotor location voltage vector is finished the rotor location among the figure, this electrical degree can convert by location voltage vector numbering n and obtain, and it is K that definition is changed the corresponding encoder output pulsimeter quantity that changes into this electrical degree, and concrete reduction formula is:

θ _eBe the electrical degree of rotor location voltage vector under the three phase static coordinate system, p is the number of pole-pairs of motor, and Q is the grid sum of encoder; In the present embodiment, p=4, Q=2500.

Z pulse grid and the residing relative position of armature spindle on the Z presentation code device code-disc among Fig. 5.Z' is for when rotor d axle (representing the rotor magnetic pole N utmost point with this) just in time overlaps with stator A axle, and encoder Z pulse grid is being followed rotor and rotated the position that arrives.Encoder carries out automatic zero compensation, namely require to realize carving at this moment output Z pulse signal, and corresponding to the encoder to count value, then to require this moment count value be 0 just.Reach the rotor magnetic pole N utmost point take this and turn to that count value plays the effect of similar encoder output Z pulse as 0 when overlapping with stator A axle.Corresponding compensation numerical value is the corresponding counted number of pulses N of angle between light-sensitive element and Z' among the figure.Be that count value needs to add zero compensation value N on the initial value basis, when rotor magnetic pole overlaps with the A axle, count value reaches lower null value corresponding to count value of conventional artificial zeroing, is equivalent to the Z pulse signal occur this moment, and control unit can carry out zero clearing work at this moment.Concrete methods of realizing is as follows: after finish the rotor location, and the electrical degree θ among Fig. 5 _eKnown, be converted into corresponding counted number of pulses K; Motor is starting operation after the zero clearing of encoder pulse count value, and the zero compensation module records is exported delta pulse signal and the counting that sends between the Z pulse signal in the process from the electric motor starting to the encoder, obtains count value M; Encoder zero compensation value N equals M and adds K:

$N=M+K=M+\frac{{\mathrm{\θ}}_{e}Q}{360p}$

Wherein: the pulse tale that M occurs for the time period internal rotor positional increment pulse signal of exporting first rotor Z pulse signal from electric motor starting to encoder.

Rotor information calculations unit is used for according to rotor-position delta pulse signal θ _i, rotor Z pulse signal and encoder zero compensation amount N, calculate the rotor position angle θ of motor by following formula _rAnd rotational speed omega _r

${\mathrm{\θ}}_r=\frac{360p(X+N)}{Q}$

${\mathrm{\ω}}_r=\frac{{\mathrm{d\θ}}_r}{\mathrm{dt}}$

Wherein: X is for exporting arbitrary rotor Z pulse signal to the pulse tale of the time period internal rotor positional increment pulse signal appearance of current time from encoder.

If the grid of incremental optical-electricity encoder adds up to Q, in frequency division situation not, the controller paired pulses carries out by the counting between-Q/2～Q/2.When capturing the Z pulse signal, counter zero setting begins counting.Its corresponding real rotor-position should be on the present count value X basis adds N, when count value X reaches Q/2-N, jumps to-Q/2-N begins to give counting, count value X equals-during N then the respective rotor magnetic pole N utmost point overlap with stator A axle.

Control unit is used for according to the component i of threephase stator electric current under the alpha-beta rest frame _α, i _βAnd rotor position angle θ _rAnd rotational speed omega _r, (be i by Magnetic Field Oriented Control Strategies _d ^*=0) constructs control voltage instruction u _α～u _βControl unit utilizes θ _rTo current value i under the two-phase rest frame _α, i _βDo the Park conversion, and with the i that obtains _d, i _q, ω _rBe input to adjuster after making comparisons with specified rate.Adjuster is through processing output control voltage signal u _α～u _βTo modulating unit, modulating unit is according to initial voltage instruction or control voltage instruction U _α～U _βProduce the conducting of pwm pulse signal control three-phase inverter power switch or close by the SVPWM technical construction, apply thus the control voltage vector to the motor stator end, the high accuracy that reaches motor is controlled.In the present embodiment, rotor information calculations unit, control unit and modulating unit are all realized by programming under the DSP platform.

Present embodiment realize initial position of rotor detect with the automatic zero compensation of encoder concrete steps as follows:

(1) controller is got and is decided appropriate voltage amplitude U _mAnd electric voltage frequency ω _h, to stator two-phase static coordinate axle α, the β axle injects high-frequency voltage signal, u _{α 1}=u _{β 1}=U _mCos ω _hT.Modulating unit is according to the voltage signal u of initial order generation module output _{α 1}, u _{β 1}, adopt space vector width pulse modulation method output PWM trigger impulse control three-phase inverter output three-phase voltage vector, be input to the motor stator end.

(2) detect motor stator end current i _a～i _c, rotor-position Preliminary detection module is obtained through the i after the Clarke conversion _α, i _β, and carry out current amplitude and obtain and the processing such as angle information demodulation, obtain just measured value θ of initial position of rotor ₀

(3) stop high-frequency voltage signal in the motor implantation step (1).Initial order generation module detects the first measured value θ of the initial position of rotor that obtains according to step (2) ₀And given voltage magnitude U _mAnd electric voltage frequency ω _h, change that only (the A axle rotates θ along positive direction to permagnetic synchronous motor d' axle into ₀Residing position) injects high-frequency voltage signal, i.e. u _d=U _mCos ω _hT, u _q=0.Be input to the u in the SVPWM module _{α 2}, u _{β 2}For utilizing θ ₀To above-mentioned u _d, u _qCarry out Park inverse transformation income value.

(4) detect motor stator end current i _a～i _c, the position of magnetic pole recognition module is obtained through the i after the Clarke conversion _α, i _β, this moment, rotor-position Preliminary detection module was no longer carried out obtaining of current signal.The position of magnetic pole recognition module is with the i that obtains _α, i _βCarry out again obtaining after the Park conversion d shaft current i under the two-phase synchronous rotating frame _dRecord ω _hT=pi/2 and ω _hThe d' shaft current amplitude of inscribing during two of t=3 pi/2s | I ₁| and | I ₂|.By comparing the size of two current amplitudes, rotor magnetic pole position is carried out identification, determine that initial position of rotor θ equals θ ₀Still equal θ ₀+ π.

(5) stop to inject high frequency voltage to motor, i.e. initial order generation module is no longer to the instruction of modulating unit input initial voltage.The rotor locating module utilizes the initial position of rotor signal θ of position of magnetic pole recognition module output to judge between the rotor location, and output should apply the electrical degree θ of rotor location voltage vector _eTo control unit and zero compensation module.

(6) control unit sends signal according to the rotor location voltage signal that the rotor locating module sends to modulating unit, the conducting of output PWM start pulse signal control three-phase inverter power switch pipe is with closed, apply the location voltage vector to the motor stator end, make rotor navigate to ad-hoc location.Location voltage vector application time continues 3～4s, has been fixed on ad-hoc location to guarantee rotor.After location voltage applied enough time, the zero compensation module was forced zero clearing to the count value of encoder pulse count device.

(7) utilize i _d ^*=0 field orientation control theory makes motor start applying under the electromagnetic field vertical with rotor permanent magnet magnetic field, and moves in conjunction with incremental optical-electricity encoder output increment pulse enable signal motor stabilizing.Encoder zero compensation module is counted the delta pulse of output simultaneously, and whether detection has encoder Z pulse signal to send.

(8) when detecting encoder and export first Z pulse signal, control unit is no longer exported control signal, and the motor stator end no longer includes the voltage input.Simultaneously, the counted number of pulses M of this moment under the encoder zero compensation module records, electrical degree in conjunction with rotor location voltage vector can be finished encoder zero-bit auto-compensation, the encoder delta pulse count value that obtains after in conjunction with encoder zero-bit self compensation value N by rotor coherent signal acquiring unit in the future using can obtain with the Z pulse signal and the artificial zeroing of routine under identical position probing result.

Adopt present embodiment to obtain initial position of rotor by twice high frequency signal injection, under non-high accuracy hardware detection condition, utilize software to realize, algorithm is simple; Carry out the rotor location according to the rotor initial bit, do not cause the counter-rotating of rotor and back and forth concussion; Encoder self study process implementation is installed arbitrarily the automatic zero compensation of lower encoder, save numerous and diverse step of artificial zeroing position, increase encoder zero-bit self compensation module on the original system basis, start as required, do not increase system's extras and complexity, improve the stability of a system with maintainable.

Claims (3)

1. the control system for permanent-magnet synchronous motor based on encoder automatic zero set is characterized in that, comprising: incremental encoder, stator current collecting unit, zero testing unit, rotor information calculations unit, control unit and modulating unit; Wherein, incremental encoder links to each other with rotor information calculations unit with the zero testing unit, the stator current collecting unit links to each other with control unit with the zero testing unit, the zero testing unit links to each other with modulating unit with rotor information calculations unit, control unit, rotor information calculations unit links to each other with control unit, and control unit links to each other with modulating unit; Incremental encoder is located on the electric machine main shaft, and the stator current collecting unit is connected with motor stator three phase windings, and modulating unit provides pwm signal by drive circuit for motor inverter.

2. control system for permanent-magnet synchronous motor according to claim 1, it is characterized in that: described zero testing unit comprises: rotor-position Preliminary detection module, initial order generation module, position of magnetic pole recognition module, rotor locating module and zero compensation module; Wherein, rotor-position Preliminary detection module links to each other with the position of magnetic pole recognition module with stator current collecting unit, initial order generation module, initial order generation module links to each other with modulating unit, the position of magnetic pole recognition module links to each other with the rotor locating module, the rotor locating module links to each other with control unit with the zero compensation module, and the zero compensation module links to each other with rotor information calculations unit with incremental encoder.

3. control system for permanent-magnet synchronous motor according to claim 1 and 2 is characterized in that: described zero testing unit employing DSP.

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