JPS6326636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable speed control device for a DC motor equipped with a frequency generator.

Conventionally, a variable speed control device using a frequency generator (hereinafter referred to as FG) is configured as shown in FIG. 1 is attached to the controlled DC motor 7
In the FG, the output waveform is shaped via the waveform shaping circuit 2, frequency/voltage converted by the monostable multivibrator 3, mixer 4, and integrator 5, and then sent to the power amplifier 6.
The power is amplified to drive the controlled DC motor 7. In order to stably obtain a large speed change range of 1:10 or more with such a conventional configuration, it is necessary to move the specified time of the monostable multivibrator 3 and the integration time of the integrator 5 in conjunction with the speed setting value. There are many problems with the circuit configuration, accuracy, and stability of the device.

The present invention is an FG that generates signals synchronized with rotation.
a controlled DC motor equipped with a controlled DC motor; a waveform shaping circuit that shapes the signal of the FG into a rectangular wave; an edge detection circuit that detects edges of the rectangular wave of the waveform shaping circuit and outputs a first signal; a delay circuit that delays a first signal of the edge detection circuit and outputs a second signal; and an integrator that integrates the speed setting signal of the controlled DC motor and is reset by the second signal of the delay circuit. and a sample hold circuit that samples and holds the output signal of the integrator using the first signal of the edge detection circuit, and an adder that adds the output signal of the sample hold circuit and the speed setting signal. The output of the device is used as a voltage signal applied to the controlled DC motor, and the speed fluctuation due to load torque and the no-load rotation speed specified by the speed setting signal are separated and added by an adder. Since the applied voltage signal is converted into an applied voltage signal, stable variable speed control can be performed even in a wide range from low speed to high speed simply by changing the speed setting signal.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. Components similar to those in FIG. 1 are given the same reference numerals and their explanations will be omitted.

8 is an edge detection circuit that detects the edge of the output signal of the waveform shaping circuit 2, 9 is a delay circuit that delays the output of the edge detection circuit 8, 10 is a variable DC power supply that serves as a speed setting signal, 11 is an integrator with a reset function, 12 1 is a sample and hold circuit, and 13 is an adder. The output of the FG1 is shaped into a rectangular wave A (see FIG. 3) by a waveform shaping circuit 2, and a signal B is obtained by detecting the rise and fall of the rectangular wave A by an edge detection circuit 8. Next, this signal B is delayed by a time t in a delay circuit 9 to obtain a signal C. Variable DC power supply 1 which becomes a speed setting signal by an integrator 11
A signal D of 0 is integrated and reset with the signal C described above to obtain an integrated output signal E. Signal E is sampled using signal B and held by sample and hold circuit 12 to obtain output signal F. Adder 1
3, signal F and signal D are added and signal G is output. The controlled DC motor 7 is driven by a signal G obtained by amplifying the signal G via a power amplifier 6.

To further explain each part in detail, the waveform shaping circuit 2 includes a comparator 14, a diode 15, and a resistor 16, and the edge detection circuit 8 includes a resistor 17.
and capacitor 18 and Schmitt circuit 19 and Ex-
The delay circuit 9 is connected to the resistor 21 by the OR circuit 20.
The integrator 1 having a reset function is connected to the resistor 24 by the capacitor 22 and the Schmitt circuit 23.
The sample hold circuit 12 is configured by the capacitor 25, analog switch 26, and operational amplifier 27.
is composed of a buffer amplifier 28, an analog switch 29, and a capacitor 30, and the adder 13 is composed of an operational amplifier 31 and resistors 32, 33, and 34, respectively. The power amplifier 6 is constructed of an analog type, a digital type using PWM, etc. depending on the amount of power to be handled.

The main part waveform diagram of FIG. 2 shown in FIG. 3 is a diagram in which the magnitude of signal D, which is the speed setting signal, is gradually increased from point P to point Q, and the signal G corresponding to signal G is It can be seen that when the voltage is applied to the control DC motor 7, the rotational speed increases, and the frequency of the signal A, which is the shaped waveform of FG1, also increases accordingly. Further, normally, the delay time t of the delay circuit 9 is:
It is set as small as possible within a range that does not hinder operation.

Since the no-load rotational speed of the DC motor is almost proportional to the applied voltage, the speed control of the controlled DC motor 7 is performed by dividing the no-load rotational speed and the speed variation due to the load torque into separate signal processing, and then adding them together at the end. 13 to obtain the voltage applied to the controlled DC motor 7. Specifically, when there is no load, the rotation of the controlled DC motor 7 is set to the no-load rotation speed indicated by the signal D. The gain is adjusted by setting the ratio between the resistors 33 and 34 of the adder 13, and the adder 13 adds the signal F corresponding to the speed fluctuation to this to obtain the voltage applied to the controlled DC motor 7. By simply changing the setting signal, the rotational speed of the controlled DC motor 7 can be changed stably over a wide range.

As explained above, according to the present invention, the following effects can be obtained.

Since the no-load rotational speed and the rotational fluctuation are controlled separately, the magnitude of the signal per unit rotational speed for the rotational fluctuation can be particularly large, and stable operation can be expected.

For the same reason, it is possible to stably perform variable speed control over a wide range of 1:10 or more from low speed to high speed.

Voltage or current can be directly handled as a speed setting signal, making it easy to interface when speed setting is performed using signals from other devices.

For this reason, it is easy to configure the circuit with a low voltage power supply, and it is possible to operate with a single 5 volt power supply, the same as a TTL circuit.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional variable speed control device;
The figure is a block diagram of one embodiment of the variable speed control device according to the present invention, and FIG. 3 is a waveform diagram of the main part of FIG. 2. 1... Frequency generator, 2... Waveform shaping circuit, 7
...Controlled DC motor, 8...Edge detection circuit,
9...Delay circuit, 10...Variable DC power supply, 11...
...Integrator, 12...Sample and hold circuit, 13
...Adder, D...Speed setting signal.

Claims (1)

[Claims] 1. A controlled DC motor equipped with a frequency generator that generates a signal synchronized with rotation, a waveform shaping circuit that shapes the signal of the frequency generator into a rectangular wave, and detecting the edges of the rectangular wave of the waveform shaping circuit. First
an edge detection circuit that outputs a signal, a delay circuit that delays a first signal of the edge detection circuit and outputs a second signal, and a delay circuit that integrates a speed setting signal of the controlled DC motor and outputs a second signal. an integrator that is reset by a second signal of the edge detection circuit; and a sample and hold circuit that samples and holds the output signal of the integrator by the first signal of the edge detection circuit.
A variable speed control device comprising: an adder that adds the output signal of the sample and hold circuit and the speed setting signal, the output of the adder being used as a voltage signal applied to the controlled DC motor.