JP2889590B2 - Rotation speed control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motor rotation speed control device, and more particularly, to a rotation speed control for simply controlling the rotation speed of a servomotor using a phase locked loop (PLL). Related to the device.

(Prior art)

2. Description of the Related Art A conventional motor rotational speed control device is, for example, as shown in FIG. That is, a reference signal oscillator 201 that determines the rotation speed of the motor 200, an encoder 202 that is connected to the rotation shaft of the motor 200 and generates a rotation signal having a frequency proportional to the rotation of the motor 200, and compares the reference signal and the rotation signal. And a phase comparator 203 for outputting a phase difference signal based thereon, a low-pass filter 204 for averaging the phase difference signal and converting it to a DC signal, and amplifying the DC signal output from the low-pass filter 204. It comprises a power amplifier circuit 205 for processing and a drive circuit 206 for controlling the motor 200. In the configuration as described above, the operation is based on the reference signal output from the reference signal oscillator 201,
A rotation signal based on the rotation speed of the motor 200 output from the encoder 202 is input to the phase comparator 203, and an error in the rotation speed of the motor 200 is detected as a phase difference signal and output to the low-pass filter 204. This phase difference signal is averaged by the low-pass filter 204 and converted into a DC signal. In this method, the converted DC signal is input to the power amplification circuit 205, and the current supply time to the motor 200 is controlled via the drive circuit 206. In addition, there is a method of controlling by combining a phase difference signal and a speed difference signal as disclosed in the specification (Application Publication No. 62-27807) already filed.

However, in the motor rotation speed control means as described above, the drive circuit 206 of the motor 200 requires a DC power which is stabilized to some extent. There is a problem that the size becomes considerably large and the circuit configuration becomes complicated.

〔Purpose〕

The present invention has been made in view of the above, and an object thereof is to simplify a circuit configuration necessary for control processing in a motor rotation speed control device,
An object of the present invention is to provide a rotation speed control device capable of promoting downsizing of the rotation speed control device.

〔Constitution〕

In order to achieve the above object, the present invention provides a motor that controls a rotation speed by an applied voltage, an encoder that generates a rotation signal having a frequency proportional to the rotation of the motor,
Reference signal generating means for regulating the rotation speed of the motor,
Phase comparing means for outputting a phase difference signal based on the phase difference between the rotation signal and the reference signal, a low-pass filter for averaging the phase difference signal, and a switching power supply for controlling a pulse width of a terminal voltage of the motor Wherein the switching power supply is connected to the constant-voltage element for ensuring a constant voltage at the reference voltage input terminal, and the control voltage of the constant-voltage element. A photocoupler whose light emission amount is controlled, and pulse width control means for controlling an ON time of a switching element based on a change in the light amount of the photocoupler and controlling an applied voltage to the motor; The phase difference signal averaged by the pass filter is directly connected to the reference voltage input terminal of the constant voltage element, and the constant voltage element The current is controlled to make it constant, the light amount of the photocoupler is controlled by the current control, and the pulse width control means controls the opening and closing of the switching element based on the light amount to control the output voltage to the motor. It is characterized by the following.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of a rotation speed control device according to the present invention. That is, a constant-voltage element 100 configured by a shunt-type regulator element and controlling the current flowing from the cathode to the anode so that the voltage of the reference voltage input terminal is kept constant (for example, there is a μPC1093 manufactured by NEC Corporation). A photocoupler 101 which is connected to the constant voltage element 100 and is an insulated signal transmission means for controlling the amount of light emission by a control current of the constant voltage element 100; Resistors 102 and 103 installed so as to be applied to the reference voltage input terminal side, a phototransistor 104 for changing the ON current of the transistor on the light receiving side from the photocoupler 101, and a phototransistor 1
Switching element 105 based on the change in ON current due to 04
And a pulse width control circuit 107 (for example, there is a μPC1094 manufactured by NEC Corporation) that controls the ON time of the motor 109 and controls the voltage applied to the motor 109. This circuit is, as described above, an insulated signal transmission means (photocoupler) from the output side.
Thus, the output voltage is controlled to be constant. Further, a motor 109 to be controlled is connected to the voltage stabilizing circuit. Also, an encoder 110 connected to a rotating shaft (not shown) of the motor 109 for outputting a rotation signal having a frequency proportional to the rotation speed of the motor 100, and a reference for generating a reference signal for determining the rotation speed of the motor 109 A signal oscillator 111, a phase comparator 112 for comparing the phase of the rotation signal from the encoder 110 with the phase of the reference signal from the reference signal oscillator 111, and averaging the phase comparison signal output from the phase comparator 112; A low-pass filter 113 for converting to a DC signal is provided, and an output from the low-pass filter 113 is connected to a reference voltage input terminal of the constant voltage element 100 via a resistor 114.

 The operation of the above configuration will be described.

An encoder 110 connected to the rotation axis of the motor 109 inputs a rotation signal having a frequency proportional to the rotation speed of the motor 109 to the phase comparator 112, while the reference signal output from the reference signal oscillator 111 is also subjected to phase comparison. Input to the container 112. Therefore, the phase comparator 112 compares the phases of the input rotation signal and the reference signal, and detects an error in the rotation speed as a phase difference signal. For example, in the phase comparison in the phase comparator 112, when the rotation signal is delayed with respect to the reference signal,
The output becomes H level (5V), and conversely, when the rotation signal is advanced with respect to the reference signal, it becomes L level (0V).
When the phases of the reference signal and the rotation signal match, the circuit is in an insulated state. The output of the phase comparator 112 is output to the low-pass filter 113, and the phase difference signal is averaged and converted to a DC signal. However, here the low-pass filter 11
Since 3 uses an inverting amplifier, the output voltage is inversely proportional to the input voltage. Furthermore, the converted DC signal is
Connected to the reference voltage input terminal side of the constant voltage element 100 via 114. The constant voltage element 100 controls the current flowing from the cathode to the anode to keep the voltage of the input DC signal constant. As a result, the light emission amount of the connected photocoupler 101 can be controlled by the control current of the constant voltage element 100, and the ON current of the transistor on the light receiving side is changed. Thus, the pulse width control circuit 107 controls the opening and closing of the switching element 105. Therefore, the output voltage to the motor 109 can be controlled. Further, since the resistors 102 and 103 apply a voltage proportional to the output voltage to the reference voltage input terminal of the constant voltage element 100, the output determined by the voltage dividing ratio of the resistors 102 and 103 and the reference voltage VR of the constant voltage element 100 by the feedback control loop described above. Voltage can be obtained. Thus, a feedback control loop for controlling the rotation speed of the motor 109 is formed in the circuit, and the rotation speed of the motor 109 is stabilized at a speed proportional to the reference signal output from the reference oscillator 111.

Further, at the time of starting the motor 109, the rotation signal from the connected encoder 110 may have a significantly lower frequency than the reference signal from the reference oscillator 111. Since the output voltage does not exceed the output voltage regulated by the voltage dividing ratio of the resistors 102, 103 and 114, it is possible to control the disturbance of the rotation speed at the time of starting due to the application of an excessive voltage to the circuit.

As described above, the present invention provides a phase locked
The phase difference signal of the loop (PLL) is output to the pulse width control loop to which the switching element 105 is connected.
Is to control the rotation speed.

〔The invention's effect〕

As described above, according to the rotation speed control device of the present invention, a motor that controls a rotation speed by an applied voltage, an encoder that generates a rotation signal having a frequency proportional to the rotation of the motor, and a rotation speed of the motor Reference signal generating means for regulating the, and a phase comparison means for outputting a phase difference signal based on the phase difference between the rotation signal and the reference signal,
In a rotation speed control device comprising: a low-pass filter for averaging the phase difference signal; and a switching power supply for controlling a pulse width of a terminal voltage of the motor, the switching power supply keeps a voltage of a reference voltage input terminal constant. A photovoltaic device connected to the photovoltaic device, the amount of light emission of which is controlled by a control current of the photovoltaic device, and the ON time of the switching device based on a change in the light amount of the photocoupler. Pulse width control means for controlling an applied voltage to the motor, and a phase difference signal averaged by the low-pass filter is directly connected to a reference voltage input terminal of the constant voltage element. , The constant voltage element controls a current to keep the voltage of the input signal constant, and controls the light amount of the photocoupler by the current control, Since the pulse width control means controls the opening and closing of the switching element based on the amount of light to control the output voltage to the motor, it is possible to simplify the circuit configuration required for control processing in the motor rotation speed control device. This makes it possible to promote downsizing of the rotation speed control device.

[Brief description of the drawings]

FIG. 1 is a combination diagram of a circuit diagram and a block diagram showing an embodiment of the configuration of the present invention, and FIG. 2 is a block diagram of a conventional motor rotation speed control device. EXPLANATION OF SYMBOLS 100: constant voltage element, 101: photocoupler 102, 103, 114 ... resistor 105: switching element 107: pulse width control circuit 109: motor, 110: encoder 111: reference oscillator, 112: phase Comparator 113 …… Low-pass filter

Claims (1)

(57) [Claims] A motor for controlling a rotation speed by an applied voltage; an encoder for generating a rotation signal having a frequency proportional to the rotation of the motor; a reference signal generating means for regulating the rotation speed of the motor; A phase comparison unit that outputs a phase difference signal based on a phase difference between the signal and the reference signal; a low-pass filter that averages the phase difference signal; a switching power supply that controls a pulse width of a terminal voltage of the motor; The switching power supply, comprising: a constant voltage element for ensuring a constant voltage of a reference voltage input terminal; and a constant current element connected to the constant voltage element, and the light emission amount is controlled by a control current of the constant voltage element. A photocoupler controlled by the control unit, and controls an ON time of a switching element based on a change in the amount of light of the photocoupler. And a pulse width control means for controlling, wherein the phase difference signal averaged by the low-pass filter is directly connected to a reference voltage input terminal of the constant voltage element, and the constant voltage element receives the input signal. Control the current in order to make the voltage constant, and control the light amount of the photocoupler by the current control. Based on the light amount, the pulse width control means controls opening and closing of the switching element to output voltage to the motor. A rotation speed control device characterized by controlling the rotation speed.