CN102170258A - Open loop servo control method based on permanent magnet inductor stepping motor - Google Patents

Abstract

The invention discloses an open loop servo control method based on a permanent magnet inductor stepping motor, belongs to the field of motor control and aims to solve the problem that a conventional servo system cannot meet the requirements of civilian automatic control occasions. The open loop servo control method provided by the invention comprises control over position information output by a motor and the control over speed information. In the control over the speed information output by the motor, open loop speed servo control over the motor is realized by changing the electrification frequency f of a stator winding of a permanent magnet inductor stepping motor. The control over the position information output by the motor comprises the following steps of: obtaining an electrical angle alpha of a phase current by using a formula according to a rotor mechanical angle Thetar required to be obtained, then sending multi-phase symmetric sine AC current into the stator winding of the motor, and controlling the electrical angle of the phase current sent into the stator winding to be alpha, thereby realizing the open loop speed servo control over the motor.

Description

Open loop method of servo-controlling based on the permanent magnet induction stepping motor

Technical field

The present invention relates to a kind of open loop location/velocity servo system, belong to Motor Control Field based on the permanent magnet induction stepping motor.

Background technology

In a lot of civilian automatic control occasions, need servo drive system to drive load and finish certain Position Control or speed control.Compare with the industrial SERVO CONTROL that precision prescribed is very high, this class SERVO CONTROL has following characteristics:

1, required precision is not high.As position control accuracy only is that velocity control accuracy is a few percent somewhat;

2, the space is very little or require cost very low, is unwell to assembling precision positions transducer such as code-disc, resolver etc.;

3, possess the shutdown lock function, the steady-state process in no power or control procedure needs system to have certain locking moment, keeps rotor-position constant.

According to these characteristics, existing servo-control system all is difficult to meet the demands, or is not possess the shutdown lock function, can only rely on to add mechanical device; Be to be designed to very accurate very high-grade positional servosystem low load with strong power.

Summary of the invention

The present invention seeks to provides a kind of open loop method of servo-controlling based on the permanent magnet induction stepping motor in order to solve the problem that existing servo system can't satisfy civilian automatic control occasion.

Open loop method of servo-controlling based on the permanent magnet induction stepping motor of the present invention comprises the positional information of motor output controlled with velocity information and controls.

The method that the velocity information of motor output is controlled: the velocity information of motor output is with the rotating speed Ω of motor output shaft _rCharacterize, concrete control method is:

According to the speed Ω that will obtain _r, by following formula:

${\mathrm{\Ω}}_r=\frac{2\mathrm{\π}}{Z_r}f,$

Obtain the energising frequency f of permanent magnet induction stepping motor stator winding, in the formula, Z _rBe the rotor number of teeth of permanent magnet induction stepping motor, then, feed heterogeneous symmetrical alternating current in the stator winding of motor, the frequency of described alternating current is f.

The present invention can realize the open loop speed servo control to motor by the energising frequency f that changes permanent magnet induction stepping motor stator winding.

The method that the positional information of motor output is controlled: the positional information of motor output is with rotor mechanical angle θ _rCharacterize, concrete control method is:

The rotor mechanical angle θ of Huo Deing as required _r, by formula Obtain the electrical degree α of phase current, then, in the stator winding of motor, feed heterogeneous symmetrical sine alternating current, and the electrical degree of the phase current that feeds in the control stator winding is α, promptly realize open loop speed servo control motor.

The electrical degree of the phase current that feeds in the control stator winding is that the method for α is: the electrical degree α of phase current is α=N360 °+Z by formula _rΔ θ _rFeed,

In the formula, Z _rBe the rotor number of teeth of motor,

N represents rotor mechanical angle θ _rIn contain synchronizing elongation θ _bNumber,

Δ θ _rBe rotor mechanical angle θ _rDivided by synchronizing elongation θ _bRemainder, Δ θ _r=θ _rMod θ _b

Advantage of the present invention: driving element of the present invention adopts the permanent magnet induction stepping motor;

By simulation control rather than digit pulse, the permanent magnet induction stepping motor is moved in the low speed synchromotor mode;

Control system of the present invention runs on open loop control mode, without any need for position or velocity transducer.

The stator winding of permanent magnet induction stepping motor need be designed to heterogeneous symmetrical alternating current winding, passes to heterogeneous symmetrical alternating current simultaneously.Common, can be designed to two symmetrical, three symmetrical two kinds of structures.

Method of the present invention by the current characteristic (frequency, phase place size etc.) of control stator winding, just can realize Position Control or speed control that general precision requires in open loop control mode, and simple in structure, control is convenient.

Description of drawings

Fig. 1 is the corresponding relation schematic diagram of rotor mechanical position and winding current phase angle.

Embodiment

Embodiment one: the described open loop method of servo-controlling based on the permanent magnet induction stepping motor of present embodiment, this method are that the velocity information of motor output is controlled, the velocity information rotating speed Ω of motor output shaft of motor output _rCharacterize, concrete control method is:

According to the speed Ω that will obtain _r, by following formula:

${\mathrm{\Ω}}_r=\frac{2\mathrm{\π}}{Z_r}f,$

Obtain the energising frequency f of permanent magnet induction stepping motor stator winding, in the formula, Z _rBe the rotor number of teeth of permanent magnet induction stepping motor, then, feed heterogeneous symmetrical alternating current in the stator winding of motor, the frequency of described alternating current is f.

The present invention can realize the open loop speed servo control to motor by the energising frequency f that changes permanent magnet induction stepping motor stator winding.

The stator winding of permanent magnet induction stepping motor is designed to heterogeneous symmetric winding, and when in winding, passing to the heterogeneous symmetrical current of analog form by current control mode.With the three-phase is example, then has:

I in the formula is the amplitude of phase current, and α is the electrical degree of phase current, is reference mutually with A.

According to the Electrical Motor theory, in the air gap of motor, must produce the rotation magnetomotive force, last composite magnetic power f1 can be expressed as:

In the formula

Be phase winding first-harmonic magnetomotive force amplitude, θ is the space electrical degree of launching along the motor stator circumference.

Should synthesize magnetomotive force in the space Sine distribution, its amplitude is put corresponding α-θ=0 point.According to the magnetoresistive characteristic of magneto, if load torque is no more than the maximum static torque of magneto, then the maximum point of air-gap permeance must be followed stator and rotated magnetomotive amplitude point on the rotor, and the electrical degree of rotor correspondence is inevitable also to be θ.The mechanical angle of rotor then is:

${\mathrm{\θ}}_r=\frac{1}{Z_r}\mathrm{\θ}=\frac{1}{Z_r}\mathrm{\α}---\left(3\right)$

Z in the formula _rThe rotor number of teeth for the permanent magnet induction stepping motor.

The permanent magnet induction stepping motor runs on the constant magnetism low-speed synchronous motor state, and the maximum static torque of motor is:

T _m＝k _TI (4)

K in the formula _TTorque coefficient for the permanent magnet induction stepping motor.

When system moved, the loading moment of system can produce an error angle θ on rotor ₀, loading moment is big more, and error angle is big more.When loading moment is lower than the maximum static torque of motor, system just can stable operation in required SERVO CONTROL state.

Operation principle when the operating state of this servo system is open loop speed servo state is:

When passing to the sinusoidal symmetrical current of certain frequency continuously in the stator winding, i.e. α=ω t=2 π ft, then rotor can be stablized and follows the rotation of stator composite magnetic power, and its rotating speed is:

${\mathrm{\Ω}}_r=\frac{d{\mathrm{\θ}}_r}{\mathrm{dt}}=\frac{2\mathrm{\π}}{Z_r}f---\left(5\right)$

F in the formula is the energising frequency of permanent magnet induction stepping motor stator winding.

According to formula (5), when passing to the sinusoidal symmetrical current of certain frequency in the stator winding continuously, just can carry out the open loop speed control by control energising frequency.

Embodiment two: present embodiment is described below in conjunction with Fig. 1, the described open loop method of servo-controlling of present embodiment based on the permanent magnet induction stepping motor, this method is that the positional information of motor output is controlled, the positional information of motor output rotor mechanical angle θ _rCharacterize, concrete control method is:

The rotor mechanical angle θ of Huo Deing as required _r, by formula

Obtain the electrical degree α of phase current, then, in the stator winding of motor, feed heterogeneous symmetrical sine alternating current, and the electrical degree of the phase current that feeds in the control stator winding is α, promptly realize open loop speed servo control motor.

The electrical degree of the phase current that control feeds in the stator winding is that the method for α is: the electrical degree α of phase current α=N360 °+Z by formula wherein _rΔ θ _rFeed,

In the formula, Z _rBe the rotor number of teeth of motor,

N represents rotor mechanical angle θ _rIn contain synchronizing elongation θ _bNumber,

Δ θ _rBe rotor mechanical angle θ _rDivided by synchronizing elongation θ _bRemainder, Δ θ _r=θ _rMod θ _b

Operation principle when the operating state of this servo system is open loop position servo state is:

According to formula (3), under open loop control mode, the mechanical location θ of rotor _rBe exactly the function of the electrical degree α of stator winding phase current, the two is an one-to-one relationship.360 ° of the every variation of α electric cycles, θ _rA step angle θ just passes by _b(360 °/Z _r).The absolute zero position of supposing this servo system is arranged on α ₀=0 place is according to the corresponding relation among Fig. 1, with any one mechanical location θ _rFor:

According to formula (3) as can be known:

α＝Z _rθ _r＝N·360°+Z _r·Δθ _r (7)

N in the formula is θ _rIn the synchronizing elongation number that comprises.

According to formula (7), pass to the phase angle that sinusoidal symmetrical current is also controlled winding current as required in the stator winding continuously, just can carry out the open loop Position Control.

Providing a concrete example below is illustrated:

The position that setting will be controlled motor output arrives 256 ° 31 ', i.e. θ _r=256 ° 31 ', the technological means that present embodiment provides is can go into by control that the phase angle of electric current reaches this purpose in the stator winding.At first according to the rotor tooth number Z of motor _rCalculate synchronizing elongation θ _b, calculate N and represent rotor mechanical angle θ _rIn contain synchronizing elongation θ _bNumber, its remainder is Δ θ _r, then allow the phase angle that feeds electric current in the stator winding be shown in the formula (7), then rotor mechanical angle θ _rPreposition with regard to arrival: 256 ° 31 ', the position open loop control that realizes easily.

Claims (3)

1. based on the open loop method of servo-controlling of permanent magnet induction stepping motor, it is characterized in that this method is that the velocity information of motor output is controlled, the velocity information rotating speed Ω of motor output shaft of motor output _rCharacterize, concrete control method is:

According to the speed Ω that will obtain _r, by following formula:

${\mathrm{\Ω}}_r=\frac{2\mathrm{\π}}{Z_r}f,$

Obtain the energising frequency f of permanent magnet induction stepping motor stator winding, in the formula, Z _rBe the rotor number of teeth of permanent magnet induction stepping motor, then, feed heterogeneous symmetrical alternating current in the stator winding of motor, the frequency of described alternating current is f.

2. based on the open loop method of servo-controlling of permanent magnet induction stepping motor, it is characterized in that this method is that the positional information of motor output is controlled, the positional information of motor output rotor mechanical angle θ _rCharacterize, concrete control method is:

The rotor mechanical angle θ of Huo Deing as required _r, by formula

Obtain the electrical degree α of phase current, then, in the stator winding of motor, feed heterogeneous symmetrical sine alternating current, and the electrical degree of the phase current that feeds in the control stator winding is α, promptly realize open loop speed servo control motor.

3. the open loop method of servo-controlling based on the permanent magnet induction stepping motor according to claim 2 is characterized in that,

The electrical degree of the phase current that feeds in the control stator winding is that the method for α is: the electrical degree α of phase current is α=N360 °+Z by formula _rΔ θ _rFeed,

In the formula, Z _rBe the rotor number of teeth of motor,

N represents rotor mechanical angle θ _rIn contain synchronizing elongation θ _bNumber,

Δ θ _rBe rotor mechanical angle θ _rDivided by synchronizing elongation θ _bRemainder, Δ θ _r=θ _rMod θ _b

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