CN104038129A - Control method for multi-stator arc-shaped motor of large telescope - Google Patents

Abstract

The invention relates to a control method for a multi-stator arc-shaped motor of a large telescope. The control method mainly comprises the following steps that firstly, detent force of the arc-shaped motor is measured, and the magnitudes of the detent force at different positions are obtained; secondly, Fourier nonlinear regression analysis is conducted on obtained position-following detent force change information, and a position-following detent force magnitude change expression of the motor is obtained; thirdly, CLARKE conversion and PARK conversion are conducted on collected three-phase current to obtain direct-axis current id and quadrature-axis current iq; fourthly, a detent force expression obtained through fitting is divided by the moment coefficient of the motor to obtain a position-following compensation current expression; fifthly, in a quadrature-axis current ring, theoretical reference current I*qv is subtracted by compensation current Iqr to obtain actual quadrature-axis reference current I*q. According to the a control method for the multi-stator arc-shaped motor of the large telescope, torque fluctuation, caused by the end effect, of the arc-shaped motor can be eliminated to a large extent, and the requirement for low-speed high-precision rotation of the motor is met.

Description

Multi-stator arc motor control method for large telescope

Technical field

The invention belongs to Electromechanical Control field, particularly a kind of Multi-stator arc motor control method that compensates to reduce large telescope by reluctance force.

Background technology

Along with scientific and technical development, the size of modern photoelectric detection equipment is increasing, as the astronomical telescope size of foreign latest type has reached 30m-50m.Drive system in the past can not meet the needed moment of inertia of these photoelectric detection equipments and mechanical stiffness.If according to traditional telescope design, more than the torque motor diameter of the direct driving that need to adopt will reach 10m.This will bring very large trouble to processing, the transportation of motor.For this problem, a kind ofly adopt novel Multi-stator arc motor drive mode to obtain application.This kind of motor is comprised of polylith arc stator, between every stator and mover, is all equivalent to a unit motor, and whole motor can be regarded the large motor consisting of Duo Tai unit motor as.This kind of motor and telescope form the design of electromechanical integration, can form the annexation that rigidity is very strong, can greatly improve telescopical dynamic response time.In addition when a stator breaks down, can remove at any time maintenance, not affect whole motor and normally work.But there is the problem that torque fluctuations is larger in this kind of motor.If the torque fluctuations that motor produces is larger, will be unfavorable for that telescope realizes precision tracking.The reason that torque fluctuations causes has a variety of, and wherein topmost reason is exactly that this kind of motor exists larger Bian Duanli and teeth groove power, and the two can be referred to as the reluctance force of motor.

Generally by the method that the structure of motor is optimized, can reduce the reluctance force of motor, but the method repeatability is low, and cost is high, the cycle is long.Therefore the reluctance force that how to adopt control method to suppress motor just seems extremely important.

Arc-shaped motor, from nature, belongs to permagnetic synchronous motor.The more ripe vector control method of the general employing of control of permagnetic synchronous motor.The method is decomposed into by motor stator current phasor the current component (torque component or quadrature axis component) that produces the current component (excitation component or direct axis component) in magnetic field and produce torque and is controlled respectively, thereby can obtain comparatively ideal linear current-moment relation.

Summary of the invention

The object of the invention is to exist for Multi-stator arc motor the problem of larger torque fluctuations, a kind of method that compensates to reduce the fluctuation of large telescope Multi-stator arc motor torque by reluctance force is provided.

For reaching described object, the invention provides a kind of Multi-stator arc motor control method that compensates to reduce large telescope by reluctance force comprises the following steps: by the quadrature axis electric current loop at Multi-stator arc electric machine control system, add offset current to reduce the torque fluctuations of Multi-stator arc motor, guarantee whole Multi-stator arc motor low speed, steadily, precision rotation, mainly the comprising the following steps of its control method:

Step S1: adopt electronic dynamometer to measure the reluctance force at Multi-stator arc motor diverse location place, obtain the magnetic resistance moment size at diverse location place Multi-stator arc motor;

Step S2: the reluctance force obtaining is carried out to Fourier series matching with change in location information, build the reluctance force size of motor with the expression formula of Multi-stator arc motor position of rotation variation;

Step S3: the electric current of Multi-stator arc motor three phase windings that collect with current sensor carries out CLARKE and PARK vector, obtains direct-axis current i _dwith quadrature axis current i _q;

Step S4: the reluctance force relational expression that matching is obtained, divided by Multi-stator arc motor torque coefficient, builds the expression formula that offset current changes with Multi-stator arc motor position of rotation;

Step S5: in quadrature axis electric current loop, by theoretical Multi-stator arc motor quadrature axis electric current loop reference current I ^* _qvdeduct Multi-stator arc motor compensating electric current I _qrobtain actual quadrature axis reference current I ^* _q.

Beneficial effect of the present invention: the inventive method adds the mode of offset current to reduce the reluctance force of motor by the electric current loop in control system, thereby reduces the torque fluctuations of motor, reaches the object that improves servo system tracking accuracy.Control method of the present invention can be eliminated arc-shaped motor to a great extent due to the torque fluctuations that limit end effect causes, and meets the rotation of motor low-speed highly precise.

Accompanying drawing explanation

Fig. 1 is the overall structure figure of Multi-stator arc motor of the present invention;

Fig. 2 is moment test philosophy figure of the present invention;

Fig. 3 is in moment test process of the present invention, force diagram when rotor is rotated counterclockwise;

Fig. 4 is in moment test process of the present invention, force diagram when rotor turns clockwise;

Fig. 5 is the Multi-stator arc motor control method flow chart for large telescope of the present invention.

Embodiment

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.

Multiple stators motor actual output torque mainly comprises two parts, electromagnetic torque and disturbance torque.Disturbance torque herein mainly refers to the magnetic resistance moment of motor self.Suppose not contain in motor winding high order harmonic component and motor air gap magnetic close in sinusoidal wave situation, the electromagnetic torque of motor output is constant.The magnetic resistance moment of motor is relevant with self structure form, is generally the function of cyclic swing.While adopting vector control, between the electromagnetic torque of motor and quadrature axis electric current, be linear relationship.Because magnetic resistance moment is the periodic function of motor position of rotation, so the output torque of motor will do periodic fluctuation along with position of rotation, will destroy like this Steady speed and the position tracking characteristics of motor.Reluctance force amplitude is larger, and the torque fluctuations of motor is more obvious, and the Steady speed of motor and position tracking characteristics are also poorer.The present invention is by measuring the reluctance force of Multi-stator arc motor, be compensated electric current with change in location information after, in the desired reference electric current I of electric current loop ^* _qvin deduct offset current I corresponding to current position reluctance force _qr, just can make the electromagnetic torque of motor output and magnetic resistance moment by waiting large reverse rule to change, thereby the whole moment that Multi-stator arc motor is exported is constant, makes Multi-stator arc motor servo system reach the object of even running.

The overall structure figure of Multi-stator arc motor as shown in Figure 1, different from traditional servomotor, Multi-stator arc motor for large telescope servo system is spliced by a lot of module unit motor A, B, C, D, the stator that this motor polylith is identical and a public rotor form, and every stator and rotor are equal to a unit motor.This kind of motor can meet the size requirements of large telescope, simultaneously convenient processing and installation again.But this kind of motor be because iron core along the circumferential direction cut-offs, and have teeth groove on iron core, when between rotor and stator during relative motion, can produce periodic limit end power and teeth groove power, the two is referred to as the reluctance force of motor.When telescope moves, reluctance force meeting makes the output torque of motor produce obvious torque fluctuations, and torque fluctuations can make servo system produce velocity perturbation, and then has influence on telescopical tracking accuracy.

A kind of method that compensates to reduce the fluctuation of large telescope motor torque by reluctance force mainly comprises: the reluctance force T that measures motor by electronic dynamometer _cafter change information with position, in the desired reference electric current I of electric current loop ^* _qvin deduct offset current I corresponding to current position reluctance force _qr, just can make the electromagnetic torque of motor output and magnetic resistance moment by waiting large reverse rule to change, thereby make the whole moment of motor output, be constant, make motor servo system reach low speed, steadily, the object moved of high accuracy.

Moment test philosophy figure of the present invention, comprises standard electromotor, dynamometer, test prototype as shown in Figure 2, wherein: described standard electromotor is that low torque fluctuations motor contains stator, wire spool, rotor; Described test prototype contains test stator, test wire spool, testing rotor; Test prototype is Multi-stator arc motor, and the magnetic resistance moment measurement of Multi-stator arc motor comprises following rapid:

Step S11: use a low torque fluctuations motor as the standard electromotor driving, standard electromotor drives test prototype to do uniform rotation.One side mounting pouring weight of test prototype, can guarantee that the rotor of test prototype can not produce because of the variation of reluctance force play along the circumferential direction like this;

Step S12: in the cold situation of test prototype, standard electromotor drives the testing rotor of test prototype to be uniform speed rotation by wire spool.By the coaxial mounted position transducer of test prototype, obtain test prototype current location, by being connected to the electronic dynamometer of surveying between style machine and pouring weight, obtain surveying the real-time pulling force data T of style machine and pouring weight simultaneously _l1, by usb data line, upload to industrial computer;

Step S13: according to the opposite spin of step S12 standard electromotor, obtain surveying style machine and pouring weight pulling force data T _l2;

When the rotor of Multi-stator arc motor rotates and reverse, force analysis figure as shown in Figure 3 and Figure 4.T in figure _l1the drag torque being subject to while being rotated counterclockwise for standard electromotor, T _l2the drag torque being subject to while turning clockwise for standard electromotor, T _gfor the loading moment that pouring weight produces, T _cfor the magnetic resistance moment of test prototype, T _ffor moment of friction.

Step 14: when test prototype rotates repeatedly, according to the real-time pulling force data T of test prototype and pouring weight _l1with pulling force data T _l2the magnetic resistance moment that can obtain test prototype and be Multi-stator arc motor is:

$T_c=\frac{1}{2}(T_{L1}+T_{L2})-T_g.$

For the Multi-stator arc motor control method flow chart of large telescope, particularly its control step mainly comprises following as shown in Figure 5:

Step S1: adopt electronic dynamometer to measure the reluctance force of arc-shaped motor, obtain the reluctance force size at diverse location place, its concrete measuring process as shown in Figure 2.

Step S2: the reluctance force obtaining is carried out to Fourier series matching with change in location information, obtain the expression formula changing with the position of rotation of Multi-stator arc motor in the reluctance force size of diverse location place Multi-stator arc motor:

$T_c\left(\mathrm{\φ}\right)=\underset{1}{\overset{n}{\mathrm{\Σ}}}{T}_{\mathrm{cn}}\cos \left(\frac{2\mathrm{n\π\φ}}{\mathrm{\τ}}\right)+T_{\mathrm{sn}}\sin \left(\frac{2\mathrm{n\π\φ}}{\mathrm{\τ}}\right)$

T wherein _cthe magnetic resistance moment size of Multi-stator arc motor, T _cnreluctance force harmonic wave cosine term coefficient, T _snbe reluctance force harmonic sine string item coefficient, n is harmonic order, and φ is the mechanical angle of arc-shaped motor, and τ is the pole span of spliced servomotor;

Fourier seriess more than general employing 5 rank is carried out matching to reluctance force, can reduce like this error between measured value and regression analysis value.

Step S3: with current sensor, the electric current of the Multi-stator arc motor A, the B that collect, C tri-phase windings is carried out to CLARKE and the conversion of PARK vector, obtain direct-axis current I _dwith quadrature axis electric current I _q;

First through using current sensor sampling to obtain A phase winding and B phase winding current i in Multi-stator arc motor three phase windings _a, i _b, through CLARKE, change the quadrature axis current i that obtains the Multi-stator arc motor under rest frame _αand i _β:

$\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

By i _a+ i _b+ i _c=0 can obtain

$\left\{\begin{array}{c}{i}_{\mathrm{\α}}=i_a\\ i_{\mathrm{\β}}=(2i_b+i_a)/\sqrt{3}\end{array}\right.$

I wherein _cfor C phase winding electric current;

Secondly through PARK, convert the quadrature axis current i under rest frame _αand i _βbe changed to the direct-axis current i of Multi-stator arc motor under rotating coordinate system _dwith quadrature axis current i _q:

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]$

Wherein θ is the electrical degree of Multi-stator arc motor, and the relation that it and use location transducer obtain the current mechanical angle Φ of Multi-stator arc motor is θ=2P Φ, and P is the number of pole-pairs of Multi-stator arc motor.

Step S4: the reluctance force expression formula that matching is obtained constructs divided by the torque coefficient of Multi-stator arc motor the expression formula that offset current changes with Multi-stator arc motor position of rotation:

I _qr＝T _c(φ)/K _t

K _tfor motor torque coefficient;

Step S5: in quadrature axis electric current loop, by theoretical Multi-stator arc motor quadrature axis electric current loop reference current I ^* _qvdeduct Multi-stator arc motor compensating electric current I _qrobtain actual quadrature axis reference current I ^* _q.Utilize Multi-stator arc motor speed closed loop PI computing to obtain theoretical Multi-stator arc motor quadrature axis electric current loop reference current I ^* _qv.

The above; be only the embodiment in the present invention, but protection scope of the present invention is not limited to this, any people who is familiar with this technology is in the disclosed technical scope of the present invention; can understand conversion or the replacement expected, all should be encompassed in of the present invention comprise scope within.

Claims (8)

1. the Multi-stator arc motor control method for large telescope, it is characterized in that comprising: by the quadrature axis electric current loop at Multi-stator arc electric machine control system, add offset current to reduce the torque fluctuations of Multi-stator arc motor, guarantee whole Multi-stator arc motor low speed, steadily, precision rotation, mainly the comprising the following steps of its control method:

Step S1: adopt electronic dynamometer to measure the reluctance force at Multi-stator arc motor diverse location place, obtain the magnetic resistance moment size at diverse location place Multi-stator arc motor;

Step S2: the reluctance force obtaining is carried out to Fourier series matching with change in location information, build the reluctance force size of motor with the expression formula of Multi-stator arc motor position of rotation variation;

Step S3: with current sensor, the electric current of Multi-stator arc motor three phase windings that collect is carried out to CLARKE and PARK vector, obtain direct-axis current i _dwith quadrature axis current i _q;

Step S4: the reluctance force relational expression that matching is obtained, divided by Multi-stator arc motor torque coefficient, builds the expression formula that offset current changes with Multi-stator arc motor position of rotation;

Step S5: in quadrature axis electric current loop, by theoretical Multi-stator arc motor quadrature axis electric current loop reference current I ^* _qvdeduct Multi-stator arc motor compensating electric current I _qrobtain actual quadrature axis reference current I ^* _q.

2. Multi-stator arc motor control method according to claim 1, is characterized in that, the magnetic resistance moment measurement of Multi-stator arc motor comprises the following steps:

Step 11: utilize the low torque fluctuations driven by motor Multi-stator arc motor of a station symbol standard to do uniform rotation; At a side mounting pouring weight of Multi-stator arc motor, for guaranteeing that the rotor of Multi-stator arc motor can not produce because of the variation of reluctance force play along the circumferential direction;

Step 12: in the cold situation of Multi-stator arc motor, standard electromotor drives Multi-stator arc rotor to be uniform speed rotation by wire spool; The position transducer of installing by Multi-stator arc motor coaxle obtains Multi-stator arc motor current location, simultaneously by being connected to the electronic dynamometer between Multi-stator arc motor and pouring weight, obtains the real-time pulling force data T of Multi-stator arc motor and pouring weight _l1, by usb data line, upload to industrial computer;

Step 13: by the opposite spin of low torque fluctuations motor, obtain Multi-stator arc motor and pouring weight pulling force data T _l2;

Step 14: according to the real-time pulling force data T of Multi-stator arc motor and pouring weight _l1with pulling force data T _l2obtain the magnetic resistance moment T of Multi-stator arc motor _cbe expressed as follows:

$T_c=\frac{1}{2}(T_{L1}+T_{L2})-T_g$

T in formula _gloading moment for pouring weight generation.

3. Multi-stator arc motor control method according to claim 1, is characterized in that, adopts Fourier seriess more than 5 rank to carry out nonlinear regression analysis to reluctance force, makes like this regression analysis value and the error between actual measured value that obtain less.

4. Multi-stator arc motor control method according to claim 1, is characterized in that, uses current sensor to gather the current i in A, B two phase windings in Multi-stator arc motor three phase windings _a, i _b.

5. Multi-stator arc motor control method according to claim 1, is characterized in that, use location transducer obtains the current mechanical angle Φ of Multi-stator arc motor, and calculates current electrical degree according to formula θ=2P Φ; Wherein θ is the electrical degree of Multi-stator arc motor, and P is the number of pole-pairs of Multi-stator arc motor.

6. Multi-stator arc motor control method according to claim 1, is characterized in that, utilizes Multi-stator arc motor speed closed loop PI computing to obtain theoretical Multi-stator arc motor quadrature axis electric current loop reference current I ^* _qv.

7. Multi-stator arc motor control method according to claim 1, is characterized in that, described reluctance force is with the variation T of the position of rotation of Multi-stator arc motor _c(φ) expression formula is as follows:

$T_c\left(\mathrm{\φ}\right)=\underset{1}{\overset{n}{\mathrm{\Σ}}}{T}_{\mathrm{cn}}\cos \left(\frac{2\mathrm{n\π\φ}}{\mathrm{\τ}}\right)+T_{\mathrm{sn}}\sin \left(\frac{2\mathrm{n\π\φ}}{\mathrm{\τ}}\right)$

T wherein _cthe magnetic resistance moment size of Multi-stator arc motor, T _cnreluctance force harmonic wave cosine term coefficient, T _snbe reluctance force harmonic sine string item coefficient, n is harmonic order, and φ is the mechanical angle of arc-shaped motor, and τ is the pole span of spliced servomotor.

8. Multi-stator arc motor control method according to claim 7, is characterized in that, described offset current I _qrexpression formula with the variation of Multi-stator arc motor position is as follows: I _qr=T _c(φ)/K _t, K _tfor motor torque coefficient.