JPH07118931B2 - DC servo motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a DC servo motor used for servo control of a robot device or the like, and more particularly to a DC servo motor capable of accurate speed command and torque command. is there.

[Conventional technology]

 FIG. 3 shows a conventional DC servo motor.

In FIG. 3, reference numeral 1 is a magnet excitation type motor, which has an armature 2 and a permanent magnet 3 for field.
Reference numeral 4 is a PWM driver, which chops a DC voltage V supplied from a primary power source (not shown) which is an unregulated power source, and generates a PWM output whose pulse width changes according to the magnitude of the speed command signal. And supplies it to the armature 2.
Reference numeral 5 is a current sensor, which is inserted in the current return path of the armature 2 and generates a signal for detecting the armature current value. Reference numeral 6 is a pulse generator (PG), which is coupled to the motor 1 and detects its rotation to generate an output signal consisting of pulses. Reference numeral 7 denotes a controller, which receives a torque feedback by an output signal of the current sensor 5 and a position feedback by a pulse signal from the pulse generator 6 and generates a control signal for causing the rotation of the motor 1 to follow an external command. To do. Reference numeral 8 is frequency / voltage (F /
V) converter, which generates an output voltage proportional to the pulse frequency of the pulse generator 6 and performs speed feedback. Reference numeral 9 is a subtractor, which takes the difference between the output signal of the controller 7 and the output signal of the F / V converter 8 to obtain P
Generates a speed command signal for the WM driver 4.

In the DC servo motor shown in FIG. 3, the speed, position,
The torque feedback amounts share the servo loop, and PWM control is performed by switching the force information by torque feedback and the position information by position feedback and setting the parameters in the controller. It is configured. Since various feedback amounts share the servo loop in this manner, the control includes an unstable element.

In addition, the PWM driver that generates the PWM signal for driving the motor is an unstabilized power source whose primary power source is not shown and is in an unstable state, which is also an unstable element of control.

[Problems to be Solved by the Invention]

As described above, the conventional DC servo motor has an unstable element in its control, which causes various problems as follows.

． Of the servo loops for the feedback amount of speed, position, and torque, the position loop and speed loop have
There is a relationship between position and speed that a speed command signal is generated based on the deviation between the position command and the position feedback amount. However, the speed loop and the torque loop add deviation to the speed command signal by the same method, so they influence each other and clearly establish the control algorithm between speed and torque. Can not.

Since the primary power supply for the PWM driver is in an unstable state, fluctuations on the primary power supply side directly affect the motor drive voltage. Therefore, the motor operation with respect to the command fluctuates and is not stable. Further, the absolute maximum power of the motor cannot be obtained due to the fluctuation of the primary power supply.

FIG. 4 shows the torque-speed characteristics of a conventional DC servo motor, and fluctuations on the primary power supply side cause fluctuations in the torque and speed characteristics as shown by hatching. It is shown.

Since the PWM driver controls the duty of the pulse on the assumption that there is a constant primary voltage,
When the primary power supply fluctuates, the voltage applied to the motor is not stable, and thus such fluctuation cannot be avoided.

It should be noted that factors of fluctuations on the primary power supply side include fluctuations in the primary side commercial power supply, fluctuations due to concentration of load, and voltage drops (line drops) in electric wires.

[Object of the Invention]

The present invention is intended to solve such a problem of the prior art, and eliminates such an instability factor in the feedback system of the DC servo motor to eliminate the speed command loop and the torque command loop. The objective is to provide a DC servo motor that enables accurate speed control and torque control without being affected by fluctuations in the primary power supply, etc. There is.

[Means for Solving the Problems]

In the present invention, a motor, a pulse generator that generates a pulse according to the rotation of the motor, and a speed control signal that causes the rotational speed of the motor to follow an external command by feeding back position information by the pulse. The controller has a controller that generates a torque command signal that commands the magnitude of the motor torque.

Further, a frequency / voltage converter for generating a speed voltage signal corresponding to the frequency of the pulse, a subtracter for generating a speed command signal by taking a difference between the speed control signal and the speed voltage signal, and a motor It is equipped with a current sensor that detects current.
Further, the output voltage V that changes following the torque command signal by feeding back the current detection signal
And a PWM driver for generating an output obtained by pulse-width modulating the output voltage V according to a speed command signal and supplying the output to the motor. This aims to achieve the above-mentioned object.

[Action]

A pulse generator 6 is provided for the motor 1 to detect rotation of the motor 1 and generate pulses. Then, the controller 7 generates a speed control signal for making the rotation speed of the motor 1 follow an external command by feeding back the position information by the pulse of the pulse generator 6, and also determines the magnitude of the torque of the motor 1. Generates a torque command signal to command.

Further, a speed voltage signal obtained by converting the pulse frequency of the pulse generator 6 into a voltage is generated, and a subtractor 9 takes the difference between the speed control signal and the speed voltage signal to generate a speed command signal.

On the other hand, by detecting the current of the motor 1 with the current sensor 5 and feeding back this signal, the stabilized power supply 10 generates the output voltage V which changes in accordance with the torque command signal. Then, the PWM driver 4 supplies the output voltage V of the stabilized power supply 10 to the motor 1 which has generated the pulse width modulated output according to the speed command signal.

Therefore, in the DC servo motor of the present invention, since the speed command loop and the torque command loop are separated, it becomes possible to construct a clear algorithm for each and the PWM driver 4 that drives the motor. Since the stabilized power supply 10 is used as the power supply for the above, accurate speed control and torque control can be performed without being affected by fluctuations in the primary power supply.

〔Example〕

FIG. 1 shows an embodiment of the present invention.
The same items as in the figure are indicated by the same numbers. Code 10
Is a stabilized power supply (voltage regulator), the output voltage of which is stabilized against fluctuations of the input power supply, and the output voltage of which can be changed according to a command from the outside.

The DC servomotor of this embodiment includes a motor 1, a pulse generator 6 that generates a pulse in response to the rotation of the motor 1, and position information is fed back by the pulse so that the rotation speed of the motor 1 can be externally controlled. Generates a speed control signal that follows the command, and
Controller 7 for generating a torque command signal for instructing the magnitude of torque, a frequency / voltage converter 8 for generating a speed voltage signal corresponding to the pulse frequency described above, the speed control signal and the speed voltage signal , A subtractor 9 for generating a speed command signal, a current sensor 5 for detecting the current of the motor 1, and an output that changes in response to the torque command signal by feeding back the current detection signal. A stabilized power supply 10 for generating a voltage V, and a PWM driver 4 for generating an output obtained by pulse-width modulating the output voltage V according to the speed command signal and supplying the output to the motor 1 are provided.

The DC servo motor shown in FIG. 1 solves the problems caused by two unstable factors in the control of the conventional DC servo motor: sharing of the servo loop and instability of the primary power source for the PWM driver. ing.

The instability element of the prior art due to the sharing of the servo loop occurs because the speed loop and the torque loop share the speed command signal. In the DC servo motor of the present invention, the torque loop is separated from the speed command signal to
As shown in the figure, an independent servo loop is formed by the torque command signal.

That is, the armature current value detected by the current sensor 5 inserted in the current return path of the armature 2 is fed back to the stabilizing power supply 10 as a torque detection signal.

As a result, the stabilized power supply 10 changes the output voltage V according to the torque command signal output from the controller 7, and accordingly the amplitude of the PWM output generated by the PWM driver 4 according to the command given from the outside to the controller 7. Changes, the control is performed so that the torque of the motor 1 follows the external command.

In the conventional DC servo motor shown in FIG. 3, the speed command signal includes information other than the speed to form a servo loop, whereas in the DC servo motor of the present invention, the speed control factor is fed back. The speed servo loop and the torque servo loop that feeds back the torque control factor are separated, and the respective control algorithms can be clearly constructed.

Further, in the control in the torque loop, the primary power source for the PWM driver 4 is supplied from the stabilized power source 10,
This is done by controlling the output voltage V. Since the power supply itself for driving the motor 1 is controlled in this manner, power control is performed by the torque-speed characteristic.

FIG. 2 shows the torque-speed characteristics of the motor 1 according to the present invention. As shown in the figure, “V ₁ → V ₂ → V ₃ (V ₁ > V ₂ > V ₃ )” of the output voltage from the stabilized power supply 10
The torque-speed characteristic changes with the change of “(T ₁ −n ₁ )
→ (T ₂ −n ₂ ) → (T ₃ −n ₃ ) ”. In this way, the torque can be controlled by the primary power source, and therefore the power is controlled by the torque-speed characteristic. Therefore, according to the present invention, it becomes possible to control the torque limitation according to the command value.

The stabilized power supply 10 does not cause a change in the output voltage even if the input power supply fluctuates. Therefore, by using this as the primary power supply of the PWM driver 4 that drives the motor 12, it is possible to stabilize the motor operation. You can

For these reasons, the DC servomotor of the present invention can easily perform variable control of torque, and is therefore extremely convenient when it is applied to a use requiring a torque limiter, such as a deburring device.

〔The invention's effect〕

As described above, according to the present invention, in the DC servomotor that performs WPM control, the primary power supply that drives the PWM driver is the stabilized power supply, and this stabilized power supply is controlled by torque feedback. It becomes possible to separate the system of the command servo loop and the torque command servo loop, and it becomes possible to clearly construct each control algorithm.

Furthermore, since the primary power supply for driving the servo motor is a stabilized power supply, it is not affected by the input power supply and load fluctuations, and it is possible to perform accurate control for speed commands and torque commands. A motor can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a torque-speed characteristic of a motor in the present invention, FIG. 3 is a diagram showing a conventional DC servomotor, and FIG. 4 is a diagram showing a conventional DC servomotor. It is a figure which shows the torque-speed characteristic of a motor. 1 ... Motor, 4 ... PWM driver, 5 ... Current sensor, 6 ... Pulse generator, 7 ... Controller,
8: Frequency / voltage converter, 9: Subtractor, 10: Stabilized power supply.

Claims (1)

[Claims] 1. A motor and a pulse generator that generates a pulse according to the rotation of the motor, and a speed control signal that causes the rotational speed of the motor to follow an external command by feedback of position information by the pulse. And a controller that generates a torque command signal that commands the magnitude of the torque of the motor, and a frequency / voltage converter that generates a speed voltage signal corresponding to the frequency of the pulse; the speed control signal; A subtractor that generates a speed command signal by taking the difference from the speed voltage signal,
A current source for detecting the current of the motor is provided, and a stabilized power supply that generates an output voltage V that changes by following the torque command signal by feeding back the current detection signal, and the speed command signal A DC servomotor according to claim 1, further comprising: a PWM driver which generates an output obtained by pulse-width modulating the output voltage V and supplies the output to the motor.