JP2002272154A - Motor operation controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor operation controller which can control the operation of a motor at a low cost. SOLUTION: This motor operation controller has a voltage phase detecting circuit 1 which detects a phase of a voltage applied to a motor M, a current detection circuit 2 which detects the phase of a current applied to the motor M, a phase detecting circuit 3 which outputs digital signal obtained by converting into a pulse width a phase difference between the voltage phase detected by the voltage phase detection circuit 1 and the current phase detected by the current detection circuit 2, an integration circuit 4 which converts the digital signal outputted by the phase detection circuit 3 into an analog signal, and a motor control circuit 8 which generates a drive signal for the motor M by a comparator-Schmidt circuit 7 based on the analog signal converted by the integrating circuit 4, and starts/stops the motor M based on the drive signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor operation control device, and more particularly to a motor operation control for judging a motor load based on a phase difference between a voltage phase and a current phase of the motor and controlling the operation of the motor. Equipment related.

[0002]

2. Description of the Related Art Conventionally, in the case of an electric device using a motor, for example, an air pump for feeding air to a mat of an air bed, it is necessary to control the operation of the air pump in order to keep the air pressure of the mat of the air bed constant. ,
In order to control the operation of the air pump, the internal pressure of the mat is constantly monitored by a pressure sensor, and the operation of the air pump is controlled by turning on / off a switch circuit such as an SSR (solid state relay) based on a detection signal of the pressure sensor. Then, the softness of the mat was automatically adjusted by adjusting the air blowing amount (air blowing time).

[0003]

However, the above control method is an excellent control method in that it is designed based on the basic concept of control. However, in order to perform the control, a pressure sensor or SSR is required. Although required, the use of these components has been problematic in reducing manufacturing costs.

[0004] It is an object of the present invention to solve the above problems and to provide a motor operation control device capable of controlling the operation of the motor at low cost.

[0005]

In order to solve the above-mentioned problems, a motor operation control device according to the present invention includes a voltage phase detection circuit for detecting a voltage phase of a voltage applied to a motor, and a current flowing through the motor. A current detection circuit that detects a current phase of the current phase, a phase detection circuit that outputs a digital signal obtained by converting a phase difference between the voltage phase detected by the voltage phase detection circuit and the current phase detected by the current detection circuit into a pulse width. An integration circuit that converts a digital signal output from the phase detection circuit into an analog signal; and a comparator / Schmitt circuit that generates a motor drive signal based on the analog signal converted by the integration circuit, based on the drive signal. And a control circuit for starting / stopping the motor.

The phase detection circuit may be constituted by a reset set flip-flop circuit, in which a voltage phase waveform signal is input to a set input and a current waveform signal is input to a reset input.

It is preferable that a timer circuit is provided between the integration circuit and the comparator / Schmitt circuit so that the time from when the motor stops to when it restarts can be set.

Further, the threshold voltage of the comparator / Schmitt circuit may be configured to be changeable so that the start / stop timing of the motor can be changed.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a motor operation control device according to the present invention.

FIG. 1 is a block diagram of a motor operation control device. A case where the operation control device controls a motor M which operates an air pump for supplying air to a mat of an air bed will be described. The operation control device is a motor M
Activate the air pump to send air into the mat of the air bed, and when the power factor of the motor (the phase difference between the voltage phase and the current phase) increases, the air pressure in the mat increases and the motor load increases. The operation of the motor is stopped upon judging that the mat is sufficiently filled with air, the motor is restarted after a predetermined time has elapsed, and the power factor of the motor is monitored again.

In FIG. 1, reference numeral 1 denotes a voltage waveform detection circuit, and this voltage waveform detection circuit 1 may be constituted by a photocoupler. The current flowing through the LED of the photocoupler is output by a phototransistor as a voltage waveform signal Vs. It is intended to be taken out.

As shown in FIG. 2A, a voltage waveform signal Vs which is an output signal of the voltage waveform detection circuit 1 has a predetermined period (10 ms when a commercial power supply uses a bidirectional LED in 50 cycles). Cycle).

Reference numeral 2 denotes a current waveform detection circuit, and the current waveform detection circuit 2 may be constituted by a photocoupler. A bridge diode of full-wave rectification is connected in series to the motor circuit in order to flow current to the LED of this photocoupler, and a forward drop voltage is used. By using a bridge diode of full-wave rectification, , A forward drop voltage of about 1.4 volts can be obtained, and a current can be applied to the LED of the photocoupler at that voltage. However, when the circuit is used for a large power consumption, a current sensor or the like is used. do it. Then, an output is taken out as a current waveform signal Vr by a phototransistor using the current flowing through the photocoupler.

The current waveform signal Vr output from the current waveform detection circuit 2 has a phase lag with respect to the voltage waveform signal Vs when the load is small, as shown in FIG. If the load is small and the load is large, the voltage waveform signal V
The delay of the phase with respect to s increases, and the signal is output.

Reference numeral 3 denotes a phase detection circuit, and this phase detection circuit 3 may be constituted by a reset / set flip-flop of a set priority. Voltage waveform signal Vs applied to set input
By inputting the current waveform signal Vr to the reset input, the phase delay is converted into a pulse width as shown in FIG. 2C and output, and the phase delay is small. If the phase delay is large, the pulse width can be reduced, and if the phase delay is large, the pulse width can be increased.

As shown in FIGS. 3 (a) and 3 (b), the output of the phase detection circuit 3 is converted by a integrating circuit 4 into an analog signal so that the change in pulse width can be output. What is necessary is just to improve the stability of the output.

Reference numeral 6 denotes a timer circuit (automatic restart circuit). The timer circuit 6 may be constituted by a time constant circuit comprising a resistor R and a capacitor so that the timer circuit 6 restarts at a preset time. What is necessary is just to set the value of a resistance and a capacitor.

The output of the timer circuit 6 is connected to a comparator / Schmitt circuit 7. As shown in FIG. 3B, the output of the comparator-Schmitt circuit 7 is turned off when the threshold voltage becomes High-level voltage Vh, as shown in FIG.
, And the threshold voltage is a low-level voltage Vl
When the output voltage of the timer circuit 6 becomes low after a predetermined time has elapsed from the start of discharge, the operation is performed.
When the level reaches the threshold voltage Vl, the output of the comparator / Schmitt circuit 7 is turned on, and the motor is restarted by controlling the motor control circuit 8 described later (see FIG. 3C).

When the restart is performed, the pump is operated, the power factor detection circuit detects a change in phase, the output voltage of the comparison circuit of the comparator is increased, and the operation of the pump is stopped, and a Schmitt circuit is provided. To prevent the pump from flapping.

Reference numeral 8 denotes a motor control circuit, which may be constituted by a bidirectional thyristor. The motor control circuit is controlled by the output of the comparator / Schmitt circuit 7 to turn on / off the pump.
OFF is controlled (Fig. 3
(D)).

Next, the operation of the control device will be described.

When the power switch is turned on, a pulse signal is formed in the phase detection circuit 3 by the voltage phase signal Vs of the voltage waveform detection circuit 1 and the current phase signal Vr of the current waveform detection circuit 2, so that the voltage of the integration circuit rises. When the input voltage of the comparator / Schmitt circuit 7 becomes the low-level threshold voltage Vl, the output of the comparator 7 becomes O
N is reached, the motor control circuit 8 is turned on, current flows through the motor M, and the pump operates.

In a state where air is not in the mat of the air bed, the load on the pump is small, so the phase difference between the voltage waveform and the current waveform is small, and the output signal of the phase detection circuit 3 has a small pulse width. The voltage converted into an analog signal by the circuit 4 does not rise to the high-level threshold voltage Vh, and the output of the comparator / Schmitt circuit 7 does not turn off.

As the air in the mat of the air bed is filled with air, the air pressure in the mat increases, and the load on the pump gradually increases, so that the phase difference between the voltage phase and the current phase gradually increases. Since the pulse width of the pulse output from the phase detection circuit 3 gradually increases, the output voltage of the integration circuit 4 increases, the input voltage of the comparator-Schmitt circuit increases, and the high-level threshold voltage Vh
, The output of the comparator / Schmitt circuit 7 is turned off, the motor control circuit 8 is turned off, and no current flows to the motor M, so that the pump stops.

When the motor M stops, the voltage charged in the capacitor of the timer circuit 6 gradually discharges through the resistor, and the input voltage of the comparator-Schmitt circuit 7 gradually decreases, and when a set time elapses, the low-level threshold voltage is reached. Since the voltage becomes Vl, the output of the comparator 7 is turned on, the motor control circuit 8 is turned on, a current flows through the motor M, and the pump operates again.

When the threshold voltage of the comparator / Schmitt circuit 7 is changed, the start / stop of the motor can be controlled in accordance with the load state of the pump, so that the internal pressure of the air mat can be adjusted.
The softness of the air mat can be freely adjusted.

If the air pressure of the mat is high, the load on the pump is large, so that the phase difference between the voltage phase and the current phase is large.
If the pulse width of the output pulse of the phase detection circuit 3 is large, the voltage of the integration circuit 4 immediately rises, and the output of the comparator 7 is turned off, so that the pump is stopped in a short time and the air pressure of the mat decreases. Since the load on the pump is small, the phase difference between the voltage phase and the current phase is small, and the phase detection circuit 3
Since the pulse width of the output pulse is small, the voltage of the integrator circuit 4 does not immediately rise, and the output of the comparator 7 is maintained in the ON state. The pump will run until the pressure rises.

As described above, the phase difference between the voltage phase of the voltage applied to the motor M and the current phase of the current flowing through the motor M is converted into a pulse width, and the converted digital signal is converted into an analog signal by an integration circuit. After the conversion, the rise of the voltage of the analog signal is monitored by the comparator, and the motor control circuit 8 of the motor M is controlled based on the monitored result, so that general circuit components can be used without using a CPU or a control program. Thus, the control device can be constructed, and the cost of the control device can be reduced.

The time until the pump restarts can be freely set by changing the time constant of the timer circuit 6. Therefore, when it is necessary to constantly monitor the pump, the time constant is reduced and an interval is set. When monitoring is sufficient, the time constant may be increased. Therefore, the time constant may be set according to the electric device to be controlled, and a control device having a high degree of freedom can be realized.

[0030]

According to the first aspect of the present invention, the phase difference between the voltage phase of the voltage applied to the motor and the current phase of the current flowing through the motor is converted into a pulse width, and the converted digital signal is integrated by the integration circuit. The analog signal is converted into an analog signal, and the increase in the voltage of the analog signal is monitored by a comparator. The start / stop of the motor is controlled based on the monitored result, so that general circuit components can be used without using a CPU or a control program. A control device can be constructed, and the cost of the control device can be reduced.

According to the second aspect of the present invention, the delay of the phase of the current phase signal with respect to the voltage phase signal can be easily converted to a pulse signal.

According to the third aspect of the present invention, the restart time of the motor can be set in accordance with the operation mode of the device to be driven by the motor. Useless operation can be suppressed.

According to the invention of claim 4, the comparator
Since the threshold voltage of the Schmitt circuit is configured to be changeable, the softness of the air mat can be adjusted.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device according to the present invention.

FIGS. 2A, 2B, and 2C are time chart diagrams illustrating output waveforms of a phase detection circuit.

FIGS. 3A, 3B, 3C, and 3D are time charts for explaining an operation state of a pump based on an output of a phase detection circuit;

[Explanation of symbols]

 Reference Signs List 1 voltage phase detection circuit 2 current phase detection circuit 3 phase detection circuit 4 integration circuit 6 timer circuit 7 comparator / Schmitt circuit 8 motor control circuit M motor

Claims (4)

[Claims] 1. A voltage phase detection circuit for detecting a voltage phase of a voltage applied to a motor, a current detection circuit for detecting a current phase of a current flowing through the motor, and a voltage phase detected by the voltage phase detection circuit. A phase detection circuit that outputs a digital signal obtained by converting a phase difference from a current phase detected by the current detection circuit into a pulse width, an integration circuit that converts a digital signal output from the phase detection circuit into an analog signal, Based on the analog signal converted by the circuit,
A motor control circuit that generates a motor drive signal with a Schmitt circuit and starts / stops the motor based on the drive signal. 2. The motor operation control device according to claim 1, wherein said phase detection circuit is constituted by a reset set flip-flop circuit. 3. The motor operation control device according to claim 1, wherein a timer circuit is provided between the integration circuit and the comparator / Schmitt circuit. 4. The motor operation control device according to claim 1, wherein a threshold voltage of said comparator / Schmitt circuit is changeable.