JP2660006B2 - Rotor angle detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a rotor angle detection method, and in particular, controls an AC servomotor by generating a current command according to a rotor angle.
The present invention relates to a method for detecting a rotor angle of an AC servomotor control device.

In the control of <art> AC servo motor, for example a synchronous motor, while generating the torque command T _C according to the velocity error,
It detects in real time where the rotor is located within the electrical angle of 360 °, and outputs a three-phase signal si according to the rotor angle θ.
nθ, sin (θ-120 °), generates a sin (θ-240 °), U is multiplied by a three-phase signal to the torque command T _C, V, generates a current command W-phase, the electric current command A pulse obtained by PWM modulation drives a transistor inverter to rotate a synchronous motor.

For this reason, in the AC servomotor control, it is necessary to accurately detect the rotation angle at which the rotor is located. Conventionally, a pulse coder is provided with a means for generating an absolute code and a means for generating an incremental pulse,
Counting means (rotor phase detection counter) is provided which counts the incremental pulse and resets each time the absolute code reaches a predetermined value, and detects the rotation angle θ of the rotor based on the count value of the rotor phase detection counter. ing.

Incidentally, if the counter reset point of the pulse coder deviates from the zero-degree position of the rotor angle, accurate rotor angle detection cannot be performed. Therefore, conventionally, U, V, W
The rotor is fixed by passing a DC current corresponding to the rotor angle of zero degree to the phase, and then the pulse coder is adjusted in the rotation direction, and the pulse coder is connected to the AC servomotor at the rotation position where the count value of the rotor phase detection counter becomes 0. I try to assemble it.

<Problems to be solved by the invention> However, in this way, the power line of the AC servomotor is connected to the DC power supply, and the mounting phase of the pulsecoder and the AC servomotor is determined while monitoring the current phase detection counter of the pulsecoder. However, there is a problem that a considerable amount of time is required in a manufacturing process. In particular, in the case of DD robots (direct drive robots), the pulse coder is directly attached to the arm because the motor is a built-in type (built-in type), and phase adjustment of the pulse coder is performed during the robot assembly process, which is a very troublesome work. Becomes

In view of the above, an object of the present invention is to provide a rotor angle detecting method in which the pulse coder may be attached to any position of the rotor, in other words, there is no need to align the phase of the pulse coder counter reset point with the zero-degree position of the rotor phase during assembly. It is to be.

<Means for Solving the Problems> FIG. 1 is a block diagram of an apparatus for realizing the rotor angle detecting method of the present invention.

1 is a pulse coder, 1a is a rotation code plate, 1d is a rotor phase detection counter, 2 is a rotor, 3a is an offset storage register, 3b is a subtraction unit, 3c is a digital servo control unit, ASC is an absolute code, and ICC is an incremental code. is there.

<Operation> Absolute code on rotation code plate 1a of pulse coder 1
ASC and an incremental code ICC are provided, and a counter 1d that counts an incremental pulse generated based on the incremental code ICC and is reset every time the absolute code becomes a predetermined value is provided, and after the pulse coder 1 is assembled to the rotor 2, Apply current to the U, V, and W phases of the motor according to the zero degree of the rotor angle, store the contents of the counter 1d as the offset value θ _OFS in the offset storage register 3a when the rotor stops rotating, and subtract it when controlling the AC motor. offset value from the count value theta _R of the counter 1d in parts 3b theta
_OFS is subtracted, and the subtraction result θ is input to the digital servo controller 3c as a rotor angle to execute digital servo control.

<Embodiment> FIG. 1 is a block diagram of an apparatus for realizing a rotor angle detecting method according to the present invention.

Reference numeral 1 denotes a pulse coder which includes a 4-bit absolute code code ASC, a rotary code plate 1a having an incremental code ICC formed at a fine pitch, first and second pickups 1b and 1c, and a rotor phase detection counter 1d. Have. An electrical angle of 0 ° to 360 ° is represented by a 4-bit absolute code ASC (0000 to 1111) of the rotation code plate 1a, and more specifically, it appears by counting incremental pulses S _IN generated based on an incremental code. Is done.

The first pickup 1b detects the absolute code ASC, and when the detected absolute code reaches a predetermined value (for example, the fourth bit changes from high level to low level, and the remaining first to third bits are all when) generates a reset pulse P _R of low level, the second pick 1c is an incremental pulse S _iN occurs by detecting the incremental code ICC, rotor phase detection counter 1d counts the incremental pulses S _iN, reset It is reset by the pulse P _R.

Reference numeral 2 denotes a rotor to which a pulse coder is attached, and reference numeral 3 denotes an AC servomotor control device that digitally controls an AC servomotor, and includes an offset storage register 3a, a subtraction unit 3b, a digital servo control unit 3c, and the like.

In the offset storage register 3a, the count value of the rotor phase detection counter 1d when the pulse coder 1 is assembled to the rotor 2 is stored as an offset value. That is, after the pulse coder 1 is fixed to the rotor 2, a current I _U = I according to the zero degree of the rotor angle is applied to each of the U, V, and W phase coils of the motor.
(A), I _V = I _W = −I / 2 (A) is applied, and the count value of the rotor phase detection counter 1d when the rotor stops is read as the offset value θ _OFS and the offset storage register 3 is read.
Store in a.

During the subtraction portion 3b actual AC servo motor control, an offset value theta from the count value theta _R of the rotor phase detection counter 1d
_The value θ obtained by subtracting _OFS is output as the rotor angle.

The digital servo controller 3c has a configuration as shown in FIG. 11 is movement command M _CMD and position feedback
Calculator for calculating a P difference _A (position error) E _R, 12 is the position error
The E _r is a position gain setting unit for generating a K _P multiplied by the command speed V _CMD. 13 is a speed control unit, a calculating unit 13a for calculating the speed deviation E _V is the difference of the speed command V _CMD and the speed feedback V _A, the speed deviation E _V and K _V multiplied to generate a torque command T _C It has a gain setting unit 13b. Numeral 14 denotes a multiplication unit which receives the rotor angle θ and the torque command T _C , and I _U = T _C · sin (θ + 90 °) (1) I _V = T _C · sin (θ-30 °) (2) I outputs _{W = T C · sin (θ} -150 °) to (3) U, V, as a current command I _C of W-phase. Reference numeral 15 denotes a constant current command generator, which stores a current I _U = I (I) corresponding to the zero degree of the rotor angle in the U, V, and W phases when the offset value θ _{OFS is} stored in the offset storage register 3a (see FIG. 1). A), I _V = I _W = −I / 2 (A) (4) is applied as the current command I _C ′. Expression (4) is expressed by (1)
~ (3) θ = 0 ° in the equation is obtained as T _C = I.

16 is a synthesizing unit (I _C and I _C ′ do not occur simultaneously), 17 is a motor unit, _Kt is a motor torque constant, J
Is motor inertia.

 Hereinafter, the overall operation of FIGS. 1 and 2 will be described.

After assembling the pulse coder 1 to the rotor 2,
Before digitally controlling the AC servomotor, the digital servo controller 3c generates a constant current command generator 15 (see FIG. 2).
A DC current (see equation (4)) corresponding to the rotor angle of zero is applied to the U, V, and W phases of the motor.

Note that the rotor is manually rotated before the DC current is applied, so that the first
At least one generates a reset pulse P _R from pickup 1b, thereby keep reset once the count value of the rotor phase detection counter 1d.

When the rotor 2 is rotated by the application of the DC current, an incremental pulse is output from the second pickup 1c according to the rotation.
_SIN occurs and is counted by the counter 1d according to the rotation direction.

When the rotor 2 stops at the zero-degree position or stops for a predetermined time after the DC current is applied, the count value of the rotor phase detection counter 1d at that time is stored in the offset storage register 3a as the offset value θ _OFS .

When the storage of the offset value θ _OFS is completed,
Digital servo control becomes possible and digital servo controller
Servo control is performed by 3c. In this case, the subtraction unit 3b subtracts the offset value θ _OFS from the count value θ _R of the rotor phase detection counter 1d, inputs the subtraction result θ as a rotor angle to the digital servo control unit 3c, and the digital servo control unit 3c The digital servo control of the synchronous motor is executed based on the rotor angle θ.

<Effect of the Invention> As described above, according to the present invention, after assembling the pulse coder to the rotor, a current corresponding to the zero degree of the rotor angle is applied to the U, V, and W phases of the motor. The content is stored as an offset value, and the value obtained by subtracting the offset value from the count value of the rotor angle counting means at the time of digital servo control of the AC motor is configured as the rotor angle, so that the pulse coder can be attached to any position of the rotor. In other words, in other words, there is no need to align the phase of the counter reset point of the pulse coder with the zero-degree position of the rotor phase during assembly.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus for realizing a rotor angle detecting method according to the present invention, and FIG. 2 is a block diagram of a digital servo control unit according to the present invention. 1 pulse coder 1a rotary code plate ASC absolute code ICC incremental code 1d rotor phase detection counter 2 rotor 3a offset storage register 3b subtraction unit 3c …… Digital servo controller

Claims (1)

(57) [Claims] 1. A rotor angle detecting method for an AC servo motor control device for controlling an AC servo motor by generating a current command according to a rotor angle detected by using a pulse coder, comprising: means for generating an absolute code in the pulse coder; A means for generating incremental pulses is provided, and a counting means for counting the incremental pulses and resetting each time the absolute code reaches a predetermined value is provided.After assembling the pulse coder to the rotor, the U, V, W phases of the motor are provided. A current corresponding to the zero degree of the rotor angle is applied, the content of the counting means is stored as an offset value when the rotation of the rotor is stopped, and the value obtained by subtracting the offset value from the counting value of the counting means at the time of controlling the AC servomotor is used as the rotor value. A method for detecting a rotor angle, wherein the method is an angle.