JPH0345181A - Control of driving of variable air gap motor - Google Patents

Abstract

PURPOSE:To reduce torque ripple by a method wherein a sine wave is deviated by the optimum exciting phase angle based on an air gap position signal to obtain the maximum exciting point. CONSTITUTION:A speed command for a variable air gap motor is added to an output of a speed detector PE for a variable air gap motor, which is converted by a F/V converter, at an adding point A and is amplified by a PI amplifier, then, is outputted into a control circuit CNT as a torque command Ifr. The control circuit CNT effects the optimum control of the exciting phase angle of a sine wave by the signal of a position detector PS from a motor M. The control circuit CNT obtains an air gap signal employing the detector PS and changes the air gap position signal into a sine wave driving current phase command. Upon changing, the control circuit CNT obtains the sine wave, deviated by an angle equal to the exciting phase angle, based on respective signals of the detector PS.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling the drive of a variable gap motor that allows maximum control of motor torque and reduces torque ripple.

B. Summary of the invention In a variable air gap motor that magnetically attracts the rotor to the stator, the torque ripple is reduced by shifting the sine wave by the optimum excitation phase angle based on the air gap position signal to obtain the strongest excitation point. A reduced high torque variable gap motor drive is possible.

C9 Prior Art The inventor of the present application has developed a variable gap motor (the origin of this name will be described later) that can obtain low speed and high torque output. The principle of the variable gap motor will now be explained with reference to FIG. As shown in the figure, a conical rotor cone 2 made of a ferromagnetic material is disposed in a fixed conical stator cone 1, and the top of the rotor cone 20 is rotatably and swingably supported. Further, coils C1 to C6, which serve as electromagnets, are arranged around the stator cone l.

The coil to be excited is Cl-4C2→C3→C4-C3-C
When the rotor cone 2 is sequentially shifted while cycling from 6 to C1, the rotor cone 2 is attracted by the energized coil and moves along the inner circumferential surface of the stator cone 1. In other words, the rotor cone 2 moves its contact position in the direction of arrow 1 in the figure, and
Rotate in the direction. The rotation speed of the rotor cone 2 is much smaller than the contact movement speed, and this rotation speed becomes smaller as the difference between the apex angle α of the stator cone 1 and the apex angle β of the rotor cone 2 becomes smaller. By extracting the rotation of the rotor cone 2 as an external output, a motor with low speed and high torque motor output can be realized. In this motor, as the rotor cone 2 moves, the gap between the stator cone 1 and the rotor cone 2 changes, so this type of motor is called a variable gap motor.

A conventional example of a variable gap motor that rotates based on the above-mentioned principle will be explained with reference to FIG. 10.

As shown in the figure, the shaft 10 is supported by a frame 12 via a radial support 11, and the shaft 10 is equipped with two rotor cones 14f via special bearings (detailed structure will be described later) 13. It is being This rotor cone 14 is provided with a core 14m for facilitating the passage of magnetic flux. The special bearing 13 allows the rotor cone 14 to swing in the axial direction, but has the function of rotating the rotor cone 14 together with the shaft 10 in the circumferential direction. The stator 15 is fixed to the frame 12 and located between the two rotor cones 14. A plurality of coils (electromagnets) are arranged in the stator 15 along the circumferential direction. Further, rotor cones 14 are provided at both ends of the stator 15.
A stator cone 16 for the transfer of workers is fixed.

The special wheel support 13 is shown in an exploded view in FIG.
As shown in the cross-sectional view in the figure, the main components are an inner cylinder 13m, an outer cylinder 13b, and a sphere 13c. On the outer peripheral surface of the inner cylinder 13a and the inner peripheral surface of the outer cylinder 13b,
A plurality of hemispherical recesses 13d are formed in the circumferential direction in alignment, and the sphere 13c is inserted into the hemispherical recesses 13d. Then, the inner cylinder 13a is connected to the shaft 1.
0, and the outer circle fi13b is fixed to the rotor cone 14.
Fixed. In this way, the rotation of the rotor cone 14 is transmitted to the shaft 10, and the rotor cone 14 can swing in the axial direction.

In the variable air gap motor having the above configuration, when the excitation of the coils of the stator 15 is sequentially shifted in the circumferential direction, the rotor cone 14 is attracted to the excited coils, and the rotor cone 14 is attracted to the excitation coils.
4 rotates while contacting the stator cone 16. The rotation of the rotor cone 14 is transmitted to the shaft 10, and the shaft rotation becomes an external output.

D. Problems to be Solved by the Invention In the variable gap motor described above, when driving the rotor, it is necessary to detect the minimum gap position of the rotor with respect to the stator. Even if this minimum air gap position is detected and the magnetic pole at that position is excited, the desired torque of the rotor cannot be obtained.

In other words, by changing the phase angle between the minimum air gap position and the strongest excitation position, the generated torque changes, and by setting this phase angle to an appropriate constant value, the highest torque can be obtained. Become.

In this way, it is necessary to obtain torque by providing a phase angle between the minimum gap position and the strongest excitation position.

On the other hand, the stator winding is excited by a rectangular wave current 1ζ obtained based on the minimum air gap position signal. For example, in the above-mentioned 6 poles, excitation is performed by a 120° rectangular wave excitation current. .

However, in the control of a variable air gap motor using a 120° square wave current, the air gap changes continuously due to the movement of the contact position of the trochanter, but due to the constant value of the square wave current, the output torque cannot be excited. A torque ripple of 6 times the current frequency occurs. This torque ripple causes a problem that stable output torque cannot be obtained.

Accordingly, the present invention provides a drive control method for a variable air gap motor, which is capable of obtaining a constant excitation phase angle in order to obtain high torque, and at the same time suppressing torque ripple.

E.

The present invention, which achieves the above-mentioned object, is based on the fact that the strongest excitation point in the sine wave, which is the excited mia flow, is shifted by the optimum excitation phase angle, based on the minimum value of the air gap position signal. shall be.

F.

Torque ripple is suppressed by the sine wave drive, and high rotor torque can be obtained by selecting the optimum excitation phase angle.

Here, the principle of drive control will be described with reference to FIGS. 6 to 8. FIG. 6 shows a plane of a six-pole motor, and three Wi poles are assigned to each of the N and S poles, for example, coil C1
is energized, and the coils C6 and C2 are also energized,
Magnetic flux passes through the magnetic pole (61, (2)) with respect to the magnetic flux (fi tl). In this case, as shown in Figure 6, with the rotor being attracted by the magnetic pole (4), the magnetic flux passes along the counterclockwise direction. Suction state (
If the contact state) is moved, the at poles (2), (4) are moved around the magnetic pole (3) with the energization of the coil C3 as the center.
is excited by a half-sine wave. That is, the excitation is sequentially shifted in a counterclockwise direction. FIG. 8 shows the energized state of the coil at each magnetic pole.

FIG. 7 shows a circuit for energizing the coils C1 to C6, which uses so-called power transistors.
Six quadrant chip circuits are provided, and only a half-sine wave is passed through the coils C1 to C6. Here, ``(f1)'' refers to the current detected by the current detector, and is the same as Io shown in I□~! in FIG.

G.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to FIGS. 1-5. FIG. 1 is an overall configuration diagram applied to speed control, and shows a speed control circuit using a variable gap motor.

In other words, the speed command to the variable gap motor and the F/V of the speed detection # (pulse encoder) PE to the variable gap motor.
The converted output and are added at the summing point A, and PI
Post-amplification torque command (amplitude command) I7. as control circuit C
Output to NT. In this control circuit CNT, motor M
The excitation phase angle of the sine wave is controlled to the maximum by the signal from the position detector PS. Here, the position detector P
S may be formed by applying a high frequency to the capacitor to change its impedance by opening the window, or by attaching a piezoelectric element to the contact surface of the rotor.

Among these, the fril+ control circuit CNT has the configuration shown in FIG. r,, I,, The sine wave drive current phase command consisting of IC is rewritten.

In this modification, the fourth
Each signal GC of the detector ps as shown in the time chart shown in the figure.
A sine wave shifted by the excitation phase angle is obtained based on GC1 to GC6.

To briefly explain the principle underlying the transducer T shown in Fig. 3,
By detecting the air gap length between the stator and rotor with a detector and creating an excitation current command using this signal, it becomes possible to control the excitation phase angle δ to an arbitrary value.

Here, the gap length l is expressed by the following equation, where φ is the phase angle.

1=A−Bcaoφ(A)B, A, and B are constants)φ=ω[
where ω is the excitation angular frequency.

As a result, the following equation is obtained.

-A ~φ=2φ=chtz-' (!・-A)B
B That is, the phase angle φ takes a cosine change.

Here, the relationship between the phase angle δ formed between the strongest excitation position of the magnetic pole and the minimum air gap position and the output torque is shown in FIG. 5 as an example.

Therefore, if the excitation phase angle δ is always controlled to be constant at the maximum torque point, the maximum output torque of the motor can be extracted.

As a result of (B), optimal control of δ can be achieved by determining the phase angle φ using the detector and exciting the coil at a phase that is advanced by the excitation phase angle δ.

The converter T generates a sinusoidal excitation current I, , from the detected position signal.
Although the coil C1 will be explained in Fig. 3, the detection signal GCI is converted to A/
D conversion is performed to obtain a digital quantity l. In this case, φ may be calculated using the above equation 11, but here, the relationship between the odor and φ is stored in advance in the ROM as table data. For this reason, 4. Once we know, we can find the phase angle φ'.

Since ROM can only determine the phase from O to π,
By differentiating 1 and inputting it to the comparator CP, expressing the slope as a sign of 1 or -1, and inputting it to the multiplier X, it is possible to obtain the phase angle φ from O to 2π.

This is the addition of 10 points! & Appropriate excitation phase angle command δ1
, calculate the phase θ of the excitation current, and use θ from the ROM table as shown in Figure 4! , = (6) θ, Ib-
(6) (θ-120”).

I e== C60(θ+120@) is obtained. That is, in FIG. 4, for example, the air gap position signal l of the coil C1 is detected, (g) φ is determined in step 19, and the current 1 is determined by shifting the excitation phase angle δ. I and Ie are calculated by shifting 120''.

According to this method, δ1 can be set arbitrarily and can be changed during operation, so that automatic tuning to the optimum excitation phase angle is possible.

Now, the output signal I, , 11 from the converter T shown in FIG.
Ic enters the multiplier X, and the torque (amplitude) command ■(r
The amplitude is changed by the current rectifier WREC and separated into a current 'jrP IF5, for example. And this current! 11 to If8 are input to each current 1ti control circuit having a PI open-circuit comparator CP and a two-quadrant chisel circuit, and control the excitation current to obtain the optimum excitation phase angle.

If the phase angle δ1 shown in FIG. 3 is set to a constant value, the output torque can be controlled only by the amplitude lfr of the excitation current, and the speed can be controlled with a circuit configuration similar to that of a DC machine.

■.

As described in detail, according to the present invention, the excitation phase angle can be set at an optimal value, allowing stable operation at the maximum torque point, and because the excitation is performed by a half-sine wave, it is possible to can reduce torque ripple.

[Brief explanation of drawings]

Figure 1 is an overall configuration diagram for speed control, Figure 2 is a control circuit configuration diagram for one embodiment, and Figure 3 is the converter T shown in Figure 2.
Figure 4 is a time chart for conversion ILT, Figure 5 is a characteristic diagram of excitation phase angle and torque, Figures 6 to 8 are diagrams explaining the principle of driving, Figure 9 Figures 1 to 12 are explanatory diagrams of the principle of the variable gap motor. In the figure, CNT is a control circuit, ps is a position detection gain, GCI to GC6 are air gap position detection signals, 1, I, Ie are exciting current phase commands, I, I to
■F6 is an exciting current. Patent applicant Meidensha Co., Ltd. Agent

Claims (1)

[Claims] A detector detects the air gap position signal of the rotor with respect to the stator, and when exciting each magnetic pole of the stator with a sine wave current,
A drive control method for a variable air gap motor, characterized in that the air gap position signal is shifted by an optimum excitation phase angle as a reference to obtain the strongest excitation point.