JPH061998B2 - Position detection method for pulse motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a position detection method for a pulse motor, and more particularly to a method for detecting an initial position of a magnetic pole of a pulse motor with a simple configuration. Is.

[Prior Art] As a technique for controlling a pulse motor like a DC motor, there is one described in the application specification of Japanese Patent Application No. 60-184778 by the present applicant. According to the present invention, the maximum torque is generated by setting the phase difference between the electrical angle and the mechanical angle to 90 °.

[Problems to be Solved by the Invention] However, in order to know the mechanical angle in the present invention, the absolute position of the magnetic pole must be detected. Therefore, an absolute position detector is required as the magnetic pole detector, and the configuration becomes complicated. There was a problem.

The present invention has been made to eliminate the above-mentioned problems, and a position detection method for a pulse motor that does not require a magnetic pole detector separately by using an incremental position detector having a simple structure also as a magnetic pole detector. The purpose is to realize.

[Means for Solving Problems] According to the present invention, the rotation stop position of the rotor when a constant current is applied to the winding of the pulse motor and the load applied to the pulse motor are set to be the same in the winding. The difference in the rotor rotation stop position when a constant current of a magnitude different from the current is applied is detected by the incremental position detector, and based on this detection signal, the stator and rotor are rotated under a constant load and a constant current. Is a method for detecting the position of a pulse motor in which the deviation angle generated between the magnetic poles is approximately obtained and the initial position of the magnetic pole is obtained using this deviation angle.

[Examples] The present invention will be described below with reference to the drawings.

FIG. 1 is a view showing an example of the main configuration of an apparatus for carrying out the method according to the present invention.

In the figure, 1 is a rotor of a pulse motor, 2 is a position detector, 3
Is a stator of a pulse motor, 4 is a winding, 5 is a processor, and 6 is an excitation means.

The rotor 1 is provided with teeth 11.

The position detector 2 detects the rotational position of the rotor 1, and is, for example, an incremental encoder. In the encoder 2, 21 is a slit plate, which is fixed to the rotor 1 and is provided with slits 22 at a constant pitch. Reference numeral 23 is a photocoupler, which has a slit plate 21 with a plurality of light-emitting elements and light-receiving elements,
The number of 2 and the moving direction are detected. This photo coupler 23
Is fixed in position.

The stator 3 is made of a magnetic material, and teeth 31 are provided at positions facing the teeth 11.

The winding 4 is provided with one phase of 41, for example. When these windings are excited, magnetic flux is generated in the teeth 31 and the stator 3
A suction force is generated between the rotor 1 and the rotor 1. Note that the windings may be provided by a number other than this.

The processor 5 sends a signal to the exciting means 6 based on the signal from the photocoupler 23 to control the excitation of the winding 41.

Next, a method of detecting the initial position of the magnetic pole of the pulse motor using such a device will be described.

First, in the pulse motor shown in FIG. 1, with the load T _L applied, the maximum current I _{M in} one phase of the winding and O in the other phase.
Pour [A].

Next, without changing the load, I _M / 2 is supplied to one phase and O [A] is supplied to the other phase.

In the two cases described above, the deviation angles (hereinafter referred to as deviation angles) generated between the magnetic poles (teeth 11 and 31) of the stator and the rotor at the moment when the intermittent rotation operation of the motor is stopped are θ ₁ and θ, respectively.
_Assuming that ₂ , T _L = K _I I _M sin θ ₁ T _L = K _I (I _M / 2) sin θ ₂ where K _{I is a} constant. The relative relationship of the magnetic poles in these cases is shown in FIGS. 2 and 3. From the equations and equations, sin θ ₁ = (1/2) sin θ ₂ , and sin θ is in a region where θ ₁ and θ ₂ are sufficiently small
With an approximate expression of theta, the θ ₁ = θ _2/2. Therefore, from the formula, the difference Δ in the shift angle is Δ = θ ₂ −θ ₁ = θ ₁ . In the incremental encoder, θ ₁ ,
Although θ ₂ cannot be measured, Δ can be detected from the rotation angle of the rotor, so θ ₁ can be obtained from the equation.

The mechanical angle θ ₁ + θ _E is calculated from the equation (θ _{E is the} deviation angle θ
₁ ), the electrical angle θ _e = 90 ° + θ ₁ that produces the maximum torque is obtained based on the mechanical angle.

In this way, the initial position of the magnetic pole is measured, and thereafter, commutation control to the motor is performed based on the detection signal of the position detector.

The relationship between the load torque T of the motor and the deviation angle θ is graphed as shown in FIG.

Although the first-order approximation is used to solve the equation in the embodiment,
Not limited to this, quadratic approximation, cubic approximation, etc. may be used. Since a pulse motor control device is generally equipped with a microprocessor, it is not a burden to solve the equation.

Further, in the embodiment, the case where the current passed through the coil is doubled as in I _M and I _M / 2 has been described, but the current may be changed to other values.

[Effect] According to the position detecting method of the present invention, the current flowing through the winding is changed to measure the initial position of the magnetic pole using the position detector, so that the magnetic pole detector or the absolute position detector is specially used. Is not necessary, and the configuration is simple with only an incremental position detector.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a main part of an apparatus for carrying out the method according to the present invention, and FIGS. 2 to 4 are explanatory diagrams of the method according to the present invention. 1 ... Rotor, 2 ... Position detector, 3 ... Stator, 4, 4
1, 42 ... Winding, 5 ... Processor, 6 ... Exciting means.

Claims (1)

[Claims] 1. A constant current of a magnitude different from the constant current is applied to the winding in the state where the rotation stop position of the rotor when a constant current is applied to the winding of the pulse motor and the load applied to the pulse motor are the same. The difference in the rotation stop position of the rotor when it flows is detected by an incremental position detector, and the deviation angle between the magnetic poles of the stator and rotor under a constant load and a constant current is approximated based on this detection signal. Position detection method of the pulse motor, which is obtained by using the deviation angle to obtain the initial position of the magnetic pole.