JPH05115197A - Rotary encoder for reluctance motor and driver therefor - Google Patents

Abstract

PURPOSE:To make it possible to detect an exciting position of each phase only through provision of patterns corresponding in number with the phases by detecting the excitation switching position for each phase of a reluctance motor based on a signal detected by a code pattern on a code board. CONSTITUTION:In case of a rotary encoder for reluctance motor having the rotor protrusions of four pole pairs around a circle for three phases of A, B, C, code patterns (a), (b), (c) for A, B, C phases having 140 deg. width are formed on a code boad 1 by equally dividing an electrical angle of 360 deg. by three and then adding electrical angles of 10 deg. in front and rear of thus split electrical angle of 120 deg.. Code pattern (a) for phase A having electrical angle width of 140 deg., from-10 deg. to l30 deg., is formed by adding electrical angles alpha=10 deg. in front and rear of a pattern having width electrical angle from 0 deg. to 120 deg.. Furthermore, a code pattern (b) of 140 deg. width, from electrical angle 110 deg. to 250 deg., is formed for phase B and a code pattern C of 140 deg. width, from electrical angle of 230 deg. to 10 deg., is formed for phase C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder used in a reluctance motor and a drive unit for a reluctance motor using the rotary encoder.

[0002]

2. Description of the Related Art Reluctance motors have advantages over synchronous motors in that they do not use magnets and have a simple structure and can be manufactured at low cost. That is, a reluctance motor is provided with salient poles on the rotor and the stator, excites the stator salient poles by passing a current through the windings wound on the salient poles of the stator, and the magnetic attraction force generated on the salient poles causes the rotor salient poles to be excited. Is a motor that draws in to generate a rotational force. Therefore, the phase of the winding to be energized is determined according to the position of the rotor, that is, the electrical angle of the rotor, regardless of the direction of the current flowing through the stator winding.

If a current is passed through the winding between the position where the stator salient pole and the rotor salient pole start facing each other until the rotor salient pole completely faces each other, torque in the rotor rotating direction is generated. For example, as shown in FIG. 8 (a), the A-phase salient pole 20A of the stator 20 and one salient pole 21a of the rotor 21 start facing each other from the A-phase winding (wound around the salient pole 20A). If an electric current is passed through the winding, the A-phase salient pole 20A of the stator 20 becomes the rotor salient pole 21.
A torque is generated that sucks a and rotates the rotor 21 counterclockwise in FIG. 8 (a). Then, as shown in FIG. 8B, counterclockwise torque is generated by passing a current through the A phase up to a position where the A phase salient pole 20A of the stator 20 and the rotor salient pole 21a completely face each other.

Therefore, as shown in FIG. 8 (a), the rotor position at which the stator salient pole 20A and one salient pole of the rotor 21 start facing each other is set to an electrical angle of 0 degree, and the stator salient pole 20A and the rotor salient pole are completely formed. When the 8th (b) rotor position facing each other is 180 degrees in electrical angle and the rotor position where the next rotor salient pole starts facing the stator salient pole 20A is 360 electrical degrees (see FIG. 8 (a)), Regardless of the rotation direction of the rotor 21, if the reference phase is taken as an example, the reference phase winding (A phase winding if the A phase is the reference phase) is energized as follows. 4 Generates clockwise and counterclockwise torque in the figure.

Counterclockwise torque: energized between 0 ° and 180 ° electrical angle Clockwise torque: energized between 180 ° and 360 ° electrical angle Therefore, depending on the rotational position of the rotor and the torque direction to be generated, the stator winding is energized. The motor can be controlled by controlling the energization. Therefore, it is necessary to detect the rotational position of the motor, but the conventionally used angular position detector (rotary encoder) uses the number of pulses (incremental pulse number) from the reference signal that is output once for one rotation. The rotation angle position of is detected. However, the rotational angle position of the rotor is unknown until the reference signal is generated at the time of start-up. for that reason,
An absolute value code (4-bit gray code) obtained by dividing one electrical cycle into 16 is provided in the position detector, and the read absolute value code is compared with the energized position of each phase to output an energization command. ..

[0006]

In one electric cycle divided into 16, it is not known where the rotor is within the electric angle of 22.5 degrees (= 360 degrees / 16). In this section,
If there is a phase in which the torque reverses, it could reverse at startup. However, if the number of patterns is increased, the number of detection elements and peripheral devices will be increased. The pattern may be formed so that the angular position at which each phase of the reluctance motor should be excited is detected, but even at the same rotational position,
The phases to be excited differ depending on the rotation direction of the rotor and the direction of the generated torque. For example, when the rotor is between 0 ° and 180 ° in the reference phase and the rotation direction is counterclockwise, the reference phase may be excited, but in the case of clockwise rotation. Does not excite this reference phase, but needs to excite other phases. Therefore, if the energization pattern to be used is changed depending on the rotation direction, the number of patterns of (phase number × 2) is required. For example, if the number of phases is three, six patterns are required, and if this code is written on one code plate, the conventional 16 (= 2 ⁴ )
There will be more than the four patterns of division.

Therefore, an object of the present invention is to provide a rotary encoder capable of detecting the position to be excited in each phase of the reluctance motor only by providing patterns for the number of phases, and to drive the reluctance motor using this rotary encoder. To provide a drive device.

[0008]

According to the rotary encoder of the present invention, an electric angle of 360 degrees of the reluctance motor is divided by the number of phases of the motor coil on a code plate, and an additional electric angle is provided on both sides of each divided angle. A code pattern for each phase is added, and the excitation switching position of each phase coil of the reluctance motor is detected based on the signal detected by the code pattern of the code plate. An excitation phase selection circuit for selecting a coil to be excited according to the signal obtained from the rotary encoder and the torque command direction is provided, and the coil of the phase selected by the excitation phase selection circuit is excited to drive the reluctance motor. I chose

[0009]

FIG. 1 is an explanatory view for explaining the principle operation of the present invention.
The number of coil phases of the reluctance motor is n, and A, B, C,
… Suppose there was an X phase. The electrical angle of 360 degrees is divided by the number of phases n of the coil, the electrical angle is divided into n, and the additional electrical α is added to both ends of each divided electrical angle.
b, ... X are provided on the code plate 1, and patterns are provided so that the code patterns of adjacent phases partially overlap each other. The minimum value of this additional electrical angle is a trough of the generated motor torque.
It is decided not to be. And
The detection element of the encoder can detect the code pattern as "1" when the code pattern is detected and "0" when the code pattern is not detected. The code pattern a, b, c, an inverted signal of ... x, ^a -, b
^-, c ^- ... x ^- and then, the torque command in the counterclockwise direction CCW
(When this signal is "1" is the counterclockwise torque command), the clockwise torque command is CW (when this signal is "1" is the counterclockwise torque command),
The excitation of each phase is simply determined by the following logical expression based on the torque command and the code pattern detected from the code plate 1.

[0010] A phase excitation period ^{= CCW * a * x - +} CW * a - * x B -phase excitation period ^{= CCW * b * a - +} CW * b - * a C -phase excitation period ^{= CCW * c * b - +} CW * c ^- * b ...... ...... it should be noted that the "*" is the logical aND, "+" is a logical sum.

FIG. 2 is an explanatory view showing the output torque of each phase when each phase is excited based on the above logical expression. In FIG. 2, (a) shows the counterclockwise torque command CCW = 1. Each phase generated torque state is shown, and FIG. 2B shows the excitation phase at this time. Further, FIG. 2C shows a code pattern detected from the code plate 1. Also, FIG.
(E) shows the torque generated in each phase when the clockwise torque command CW is output, and FIG. 2 (d) shows the excitation phase at this time. The reference phase is the A phase, and a code pattern a is added from a position before the additional electric angle α to the position of (360 / n) + α from the rotor position where the electric angle is 0 as shown in FIG. 7A. The code pattern b is (360 / n)
From the position of −α to the position of (2 × 360 / n) + α, each code pattern is similarly added below, and the code pattern x is α from the position of {360− (360 / n) −α}. It is attached up to the position. As a result, when the counterclockwise torque command CCW is "1", each phase is excited from the above logical expression as shown in FIG. That is, assuming that the detection element for detecting the code pattern is arranged at the position of the electrical angle “0” and the rotor is at the position of the electrical angle α, the A phase is excited and the rotor is rotated counterclockwise (in FIG. 2). (The code pattern on the code plate moves from right to left.)
When the code pattern a is no longer detected and the code pattern b is detected, the B phase is excited and the rotor rotates counterclockwise.

Further, the torque command is a clockwise command CW = 1.
Then, as shown in FIG. 2D, each phase is excited, and the rotor rotates in the clockwise direction. Particularly, in the present invention, since the additional electrical angle α is provided in the code pattern, the generated torque does not become “0” when switching the excitation phase.
For example, when the rotor is stopped at the position of electrical angle “0” at the position of FIG. 8A, if there is no additional electrical angle α and the A-phase, which is the reference phase, is excited at this position, the rotor becomes Cannot be rotated by receiving the same attraction force in the clockwise and counterclockwise directions from the magnetic poles of the excitation phase A (stator salient poles), but since the additional electrical angle α is provided, first the X phase The phase A is excited after being excited and rotated counterclockwise and the electrical angle becomes α, and the salient poles of the rotor are attracted counterclockwise from the magnetic poles of phase A.

[0013]

FIG. 3 shows a code pattern of a code plate according to an embodiment of the present invention. In this embodiment, three phases of A, B and C phases have rotor salient poles of four pole pairs in one circumference. The example of the code plate 1 of the rotary encoder for reluctance motors is shown. An electrical angle of 360 degrees is divided into three parts on the cord plate 1, and an additional electrical angle of 10 degrees is added before and after the division angle of 120 degrees, and
Code patterns a, b, c for A, B, C phases with a width of 40 degrees
The code pattern a for the A phase is formed by adding an additional electrical angle α = 10 degrees back and forth to a pattern having a width of electrical angle 0 to 120 degrees, and from electrical angle −10 degrees (350 degrees) to electrical angle 13 degrees.
A code pattern a having an electrical angle width of 140 degrees up to 0 degrees is created. Further, for the B-phase use, a 140 degree wide code pattern b having an electrical angle of 110 to 250 degrees is formed. Further, for the C phase, a code pattern c having an electrical angle width of 140 degrees from 230 degrees to 10 degrees is created. The code plate 1 is attached to the rotor shaft of the reluctance motor, and the code pattern is read by a detection element (not shown).

FIG. 4 is an explanatory view for explaining each phase excitation method of the present embodiment. Based on the direction of the torque command and the signal detected from the code pattern of the code plate 1, the excitation coil is expressed by the following logical expression. Is selected and the coils of the A, B and C phases are excited.

[0015] A phase excitation period ^{= CCW * a * c - +} CW * a - * c B -phase excitation period ^{= CCW * b * a - +} CW * b - * a C -phase excitation period ^{= CCW * c * b - +} CW * c ^- * b Figure 4 (b) shows the phase torque state when torque command counterclockwise (CCW = 1), 4 (b) shows the phase of the excitation interval, FIG. 4 (c 4) shows the state of the pattern code of the code plate 1, and FIG. 4 (e) shows the state of torque generated in each phase when a clockwise torque command (CW = 1) is given.
FIG. 4D shows the excited state of each phase at this time.

It is assumed that the detection element for detecting the code pattern of the code plate 1 is arranged, for example, at each electric position P of 0 degrees, and a counterclockwise torque command (CCW = 1) is output. And Then, assuming the state shown in FIG. 4, the code patterns a and c are read from the code pattern of the code plate 1 attached to the rotor shaft to be “1”, and the C phase is excited from the above logical expression. It As a result, the code plate 1 attached to the rotor and the rotor shaft rotates counterclockwise CCW (the codes a, b, and c move to the left in FIG. 4), and when the electrical angle rotates 10 degrees, the code pattern c Is detected, the excitation of the C phase is stopped and the A phase is excited from the above logical expression. Figure 8
As can be seen from (a), since the salient rotor poles and the A-phase magnetic poles of the stator slightly overlap each other at the position where the electrical angle is 10 degrees, the inductance is small and the exciting current rapidly rises to rapidly generate torque.

Next, when the rotor further rotates 120 degrees and the code pattern b is detected from the code plate 1 and the code pattern a is no longer detected, the excitation of the A phase is stopped and the B phase of the B phase is detected from the above logical expression. Excitation is started. Since the A-phase magnetic pole and the rotor salient pole overlap each other up to a position at an electrical angle of 130 degrees, the inductance is large, and therefore the exciting current does not suddenly decrease, but the electrical angle 180 shown in FIG.
Since it has not reached the position of the degree, the reverse torque is not generated. Similarly, when the rotor rotates counterclockwise and the code pattern c is detected and the code pattern b is no longer detected, the C phase is excited, and when the rotor further rotates, A
The phases are excited. Thereafter, this operation is repeated and the rotor rotates counterclockwise. If a clockwise torque command (CW = 1) is output,
As shown in (d) and (e), each phase is excited and the rotor rotates clockwise.

FIG. 5 is a development view in which the magnetic poles of the stator and the salient poles of the rotor are developed in order to explain this operation in more detail. In FIG. 5, (a) shows the magnetic poles A, B and C of the stator.
4B is a developed view of FIG. 5B, in which (B) to (E) are diagrams showing the code pattern of the salient poles of the rotor and the code plate.
It is assumed that it is arranged at the position P of degrees. The rotor is shown in Figure 5.
When the counterclockwise torque command (CCW = 1) is output in the state (b) (state where the electrical angle is 10 degrees), the code pattern a is detected, so that the magnetic pole A is excited from the above logical expression. , The rotor salient pole is attracted, the rotor and the code plate 1 rotate counterclockwise, the code pattern moves to the left in FIG. 5, rotates 120 degrees and becomes the state of FIG. 5C, and the code pattern a is detected. When the code pattern b is detected and the code pattern b is detected, the excitation of the A phase is stopped and the B phase is excited. The rotor and the code plate 1 rotate counterclockwise (the code pattern moves to the left in FIG. 5) and further rotate 120 degrees to reach the state shown in FIG. 5D, and the code pattern b is no longer detected and the code pattern c is detected. When is detected, the B phase excitation is stopped, the C phase is excited, and the rotor rotates counterclockwise.
Then, when the code pattern a is detected and the code pattern c is no longer detected in the state of FIG. 5 (e), the excitation of the C phase is stopped and the A phase is excited. After that, this operation is repeated and the rotor rotates counterclockwise.

FIG. 6 shows a clockwise torque command (CW =
1) is an operation explanatory view in the case of being output. For example, when the rotor is in the state shown in FIG. 5B, which is the same as the state shown in FIG.
Since the code pattern a is detected but the code pattern b is not detected, the B phase is excited from the above logical expression, the rotor and the code plate rotate clockwise (the code pattern moves to the right in FIG. 6), and the electrical angle rotates 20 degrees. Then, in the state of FIG. 6C, when the code pattern a is not detected and the code pattern c is detected, the excitation of the B phase is stopped, the A phase is excited, and the rotor is rotated clockwise (see the figure). 6 middle code pattern is rotated to the right) and rotated by 120 degrees.
In the state of (d), the code pattern c is not detected, and when the code pattern b is detected, the C phase is excited,
When the rotor rotates clockwise and rotates 120 degrees, the
Since the state of (e) is entered and the code pattern b is not detected and the code pattern a is detected, the B phase is excited and the rotor rotates 120 degrees, resulting in the state of FIG. 6 (c). Hereinafter, this operation will be repeated.

Although the present embodiment operates as described above, since the additional electrical angle α = 10 degrees is added to the code pattern, the valley of the output torque of the motor becomes "0" when the excitation phase is switched. There is no such thing. For example, the rotor is
1 from the state of (b) clockwise (to the right in FIG. 5)
When the A-phase is excited while moving 0 degrees, the salient poles of the rotor are equidistant to both sides of the A-phase magnetic pole, and both salient poles are attracted with the same force. However, in this embodiment, the C phase is excited and the rotor rotates 10 degrees counterclockwise in this state, as shown in FIG.
Since the A-phase is excited after the above state, the rotor is certainly excited in the counterclockwise direction. in this way,
The additional electrical angle is added within a range where anti-torque is not generated.

FIG. 7 is a block diagram of essential parts of a control unit of a three-phase reluctance motor for carrying out this embodiment. A code plate 1 as shown in FIG. 3 of the rotary encoder of this embodiment is attached to the rotor shaft of the reluctance motor 6, and a pulse coater 5 that generates pulses as the rotor rotates.
Is attached. The light from the light emitting element 2 can be received by the light receiving element 3 through the code plate 1, is received according to the code patterns a, b, c and is amplified by the signal amplifier 4 for the A to B phases. Energization control circuit 13A
13B to 13B. A signal (1 = CCW, inversion signal 1 = CW) from the torque direction determination circuit 12 that determines the command torque direction from the sign of the torque command Tc is also input to the energization control circuits 13A to 13B. Energization control circuit 13A described above ^{CCW * a * c - + CW} * a - * c energization control circuit 13B is ^{CCW * b * a - + CW} * b - * a conduction control circuit 13C is ^{CCW * c * b - + CW} * c ^- * b performs logical operation of the outputs a signal of "1" or "0".

The output of the pulse coder 5 is input to the frequency / voltage converter 14 and converted into a voltage. The speed loop compensating circuit 7 amplifies the difference between the speed command Vc and the voltage corresponding to the actual speed of the variable reluctance motor 6 output from the frequency / voltage converter 14, that is, the speed deviation, and outputs the torque command Tc. , Multiplier (analog switch) 8
A, 8B, and 8C are multiplied by the torque command Tc and the signals output from the A, B, and C phase energization control circuits 13A to 13B, respectively, to obtain phase current commands ir (A), ir (B), and ir (C ) Is output. The current loop compensating circuits 9A, 9B and 9C are configured so that the current commands ir (A), ir (B), ir (C) for each phase and the current detector 11
Corresponding phase current ic detected by A, 11B, 11C
(A), ic (B), ic (C), that is, the current deviation is amplified, and the phase voltage commands er (A), er (B), er (C) are respectively supplied to the power amplifiers 10A, 10B, Output to 10C.

The power amplifiers 10A, 10B and 10C have P
Comprised of WM inverter circuit, etc., phase voltage command er (A)
, Er (B), er (C) are received and phase voltage er '(A), e
r '(B) and er' (C) are applied to each phase of the motor 6,
Is to drive.

G1 (S) is a speed loop compensation circuit 1
G2 (S) is a current loop compensation circuit 9A,
9B and 9C are transfer functions. G3 is the gain of the power amplifiers 10A, 10B, 10C. The control circuit is equivalent to the control circuit of a conventional reluctance motor, but the rotary encoder configured by the code plate 1 or the like described above is used to detect the rotor rotation position, and the energization control is performed by the output of the rotary encoder. Circuit 13A ~
The only difference is that the excitation phase is selected by performing the above-described logical operation in 13C.

That is, the above energization control circuits 13A to 13
The logical operation is performed in C, and only the coil of the phase whose output becomes "1" is energized, and the reluctance motor is drive-controlled as described above.

[0026]

According to the present invention, unlike the conventional method of detecting a fine angle and selecting an excitation phase, the reluctance motor can be accurately operated without a directional error by using only the code pattern of the total number of motors. It is something that can be controlled. Moreover, since the additional electrical angle is added to each code pattern, the generated torque does not become "0" at the time of switching the excitation.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a cord plate of the present invention.

FIG. 2 is an explanatory diagram illustrating output torque of each phase when each phase is excited using the code plate of the present invention.

FIG. 3 is an explanatory diagram of a code plate for a three-phase reluctance motor according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating output torque of each phase when each phase is excited using the code plate of the embodiment.

FIG. 5 is an operation explanatory diagram when the reluctance motor is driven counterclockwise by using the cord plate of the embodiment.

FIG. 6 is an operation explanatory diagram when the reluctance motor is driven in the clockwise direction using the cord plate of the embodiment.

FIG. 7 is a block diagram of a main part of a reluctance motor control device using the code plate of the embodiment.

FIG. 8 is an explanatory diagram illustrating torque generation in a reluctance motor.

[Explanation of symbols]

 1 code board 2 light emitting element 3 light receiving element 4 signal amplifier 5 pulse coder 6 reluctance motor 7 speed loop compensation circuit 8A to 8C multiplier 9A to 9C current loop compensation circuit 10A to 10C power amplifier 11A to 11C current detector 12 torque direction determination circuit 7 pulse coder 13A to 13C energization control circuit a, b, c, ... x code pattern

Claims (2)

[Claims] 1. A rotary encoder that is coupled to a rotor shaft of a reluctance motor and detects a rotation angle of a rotor, the rotary encoder dividing an electrical angle of 360 degrees of the reluctance motor by a number of phases of a motor coil,
It has a code plate provided with a code pattern for each phase to which an additional electrical angle is added on both sides of each divided angle, and based on the signal detected by the code pattern of the code plate, the coil of each phase of the reluctance motor Rotary encoder for reluctance motor that detects excitation switching position 2. A reluctance motor having an excitation phase selection circuit for selecting a coil to be excited according to a signal obtained from the rotary encoder and a torque command direction, and exciting a coil of a phase selected by the excitation phase selection circuit. Drive device for reluctance motor characterized by driving