JPS5970195A - Output torque controller for synchronous motor - Google Patents

Abstract

PURPOSE:To effectively utilize a servo system by switching the control of an output torque in response to an external signal in the rotations of both positive and negative directions of a rotor. CONSTITUTION:A speed function generator 3 and a position function generator 7 is composed of an RAM having the first pattern as positive direction torque control function and the second pattern as negative direction torque control function. An external converter 7 outputs a signal of logic ''1'' or ''0'', the speed function generator 3 and the position function generator output the first or second pattern in response to the signal of the converter, thereby switching the rotating direction of a rotor. The output torque depends merely on the current, becomes similar to the output torque of a DC motor depending upon no rotating angle, and a 3-phase synchronous motor is used as a servo motor.

Description

[Detailed description of the invention] The present invention relates to an output torque control device for a synchronous motor.

An object of the present invention is to make it possible to reverse the relationship by an external signal when there is a function between a certain fixed rotational direction command of a synchronous motor and an actual motor rotational direction.

The gist of the present invention to achieve the above object is to detect the rotor position of a synchronous motor, generate a function for forming a command current based on this, and generate a command current based on this function and a speed command signal. In a servo system of a synchronous motor that controls a small output torque by forming a function generator, a function generator that generates the above function is provided with a first function that controls a positive direction torque,
Output torque of a synchronous motor, characterized in that it is provided with a second pattern for controlling turn, negative direction torque, and means for outputting either the first arm turn or the second pattern in response to an external signal. Located in the control unit.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an output torque control device for a synchronous motor according to an embodiment of the present invention. In the same figure, l
is a three-phase winding of a three-phase synchronous motor, 2 is a pulse encoder fixed to the rotating shaft of the synchronous motor, and 3 is a rotor encoder based on the pulse indicating the rotor angle θ obtained from the output of the rotorless encoder 2. a speed function generator that generates a voltage proportional to the actual speed of the rotor; 4 a speed command circuit that generates a voltage corresponding to the desired rotor speed; 5 a combination of the output voltage of the speed function generator 3 and the speed command circuit 4; an adder for obtaining a difference from the output voltage; 6 a compensation circuit for amplifying the output of the adder 5 and compensating for frequency characteristics to obtain a command torque signal as an output;
7 indicates the rotor angle θ obtained from the output of the elbow encoder 2.
The function generators -8, 9, and 10 respectively generate the position of the phase (θ - 迭π), respectively, by multiplying the output of the compensation circuit 6 by a multiplier that obtains the command currents IOR, IO2 and IOT;
11.12゜13 is an adder for obtaining the difference between the command current and the current actually flowing through the three-phase winding, 14, 15.16
are compensation circuits that amplify the outputs of the adders 11, 12, and 13 and compensate for irregular frequency characteristics, respectively.

The velocity function generator 3 and the position function generator 7 are each
It is constituted by a ROM having a first pattern which is a function for positive direction torque control and a second /'P turn which is a function for negative direction torque control.

The external switching circuit 7 outputs a logic ``1'' or ``0#'' signal, and in response to this signal, the velocity function generator 3 and the position function generator output the first pattern or the second pattern. , thereby switching the direction of rotation of the rotor.

FIG. 2 is a diagram showing a rotor of a three-phase synchronous motor. In the figure, the rotor 20 has rotated by θ from the reference position.

Control of output torque in forward rotation is performed as follows. A logic "1" signal from the external switching circuit 17 is applied to the velocity function generator 3 and the position function generator 7.

, the pulse encoder 2 detects the rotation angle θ of the rotor 2°, and transmits the 9 pulse train corresponding to the angle θ to the speed function generator 3.
and is given to the position function generator 7. The speed function generator 3 calculates the rotational speed in the positive direction based on the Ukehatake/Motherus sequence, and outputs a voltage Va proportional to the rotational speed. The speed command circuit 4 outputs a voltage Vc proportional to the command speed.

The adder 5 performs all calculations on Vc-Va and inputs the result to the compensation circuit 6. The compensation circuit 6 generates a command torque Tc such that the Vc - VaO value becomes zero, and multipliers 8, 9° and 1
Enter 0. The command torque Tc is proportional to the command current Ic that should flow through the three-phase winding 1.

The position function generator 7 receives/IP pulse sequence (C based + sin (θ−迭π)) and multipliers 8, 9. and 10
give each. Multiplier 819. and 10 calculate the product of the command torque Tc and the above function, and output command currents IOR+IO8 and IOT to be supplied to the phases R, S, and T of the three-phase winding 1, respectively. Adder 11.12. and 13 are the command current l01t, respectively.
- Find the difference between Ios and IOT and the currents IFL, Is, and IT actually flowing through each phase of the three-phase winding 1, that is, 0 -IR, Ios - Is, and 10T-IT, and calculate these differences. are respectively connected to compensation circuits 14, 15 . and 16. Compensation circuits 14, 15. and 16 supply current to each phase of the three-phase winding 1 such that the above-mentioned current difference becomes zero. Vc = Va, IoFL-IR, Ic5
=Is.

If the current flowing through the three-phase winding 1 when α=I=r is expressed as =
I sin (θ - Sπ), the output torque T becomes -"KI, and the output torque depends only on the electric current, and is similar to the output torque of a DC motor, which depends on the rotation angle θ.
It can be seen that this three-phase synchronous motor can be used as a servo motor.

In controlling the output torque in negative rotation, the speed function generator 3 outputs a voltage of -Va, and the position function generator 7 outputs a voltage of -Va in response to a logic 0' signal from the external switching circuit 17. sin θ, −sin (θ − cloudy π)
, = sin (θ−π) is output. Therefore, the output torque T is 2 T = KI (-sin θ) sin θ + KI (-sin (
θ−π)) gin(θ−100π) 1KI (−5in (
Once θ-”K)) 5in(θ-Aπ)3=KI, the rotation direction is switched to the negative direction.

As is clear from the above description, according to the present invention, it is possible to switch output torque control in accordance with an external signal for both positive and negative rotations of the rotor of a synchronous motor, making it possible to synchronously Effectively used in servo systems using electric motors.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an output torque control device for a synchronous motor according to an embodiment of the present invention, and FIG. 2 is a diagram showing a rotor of a three-phase synchronous motor. 1...Three-phase winding, 2...Pulse encoder, 3...
- Speed function generator, 4... Speed command circuit, 7... Position function generator, 17... External switching circuit.

Claims (1)

[Claims] 1. Equipped with a pulse encoder that detects the rotor position of the synchronous motor, and a function generator that generates a function for forming a command current based on the detected rotor position, and a function generator that generates a function for forming a command current based on the function and a speed command signal. In a servo system for a synchronous motor that controls output torque by forming a command current, the function generator has a first pattern that is a function for positive direction torque control, and a first pattern that is a function for negative direction torque control. a certain second pattern, and the first /4 depending on an external signal.
An output torque control device for a synchronous motor, comprising means for outputting either the turn or the second pattern.