JP2000217383A - Control circuit for intermittent operation of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a motor from being intermittently stopped by a little temperature change while the rotation control of the motor is maintained. SOLUTION: A thermistor S is provided on the stator side of a motor M to detect a temperature. A comparison unit 11 which compares the detected temperature of the thermistor S with a 1st reference temperature and a 2nd reference temperature higher than the 1st one is provided. The comparison unit 11 outputs off-control signals continuously when the detected temperature is elevated from the 1st reference temperature, and exceeds the 2nd reference temperature and outputs on-control signals continuously when the detected temperature is lowered from the 2nd reference temperature and falls below the 1st reference temperature. A switching unit Q is connected to the comparison unit 11 and the on/off control of the transmission of a rotation control signal Vs to a rotation control unit 7 is carried out in accordance with the on-/off- control signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermittent operation control circuit for a motor, and more particularly to an intermittent operation control circuit for a motor, such as an inverter motor, whose rotation is controlled by a relatively large driving power.

[0002]

2. Description of the Related Art A general motor, for example, a brushless motor M, as shown in FIG.
The rotation is controlled by a rotation control unit 7 including a speed detection unit 5.

[0003] That is, a motor drive current is supplied to a drive coil L of a motor M by a drive unit 3 to drive a rotor (not shown).
And the rotation speed (rotation speed) of the motor M detected by the speed detection unit 5 and a rotation control signal (servo signal) Vs set from outside are compared and subtracted by the subtraction unit 1, and the deviation from the subtraction unit 1 The rotation of the motor M is controlled by the drive unit 3 so as to reduce the rotation speed, and a desired rotation speed is obtained. Symbol P1 in the figure
Is an input terminal of the rotation control unit 7.

Conventionally, in such a motor M, at the time of steady driving or when the inside is overheated due to, for example, an excessive drive current flowing through the drive coil L for some reason,
From the viewpoints of safety and durability, it is necessary to stop the rotation of the motor M.

More specifically, a thermistor S whose resistance value changes due to a change in the ambient temperature is arranged in a drive coil L of a motor M, and a temperature detection voltage that changes due to a change in the resistance value of the thermistor S and a predetermined independent reference When the temperature detection voltage is lower than the reference voltage, the switching unit 9 is switched to shut off the rotation control signal Vs to the rotation control unit 7 so that the temperature detection voltage becomes lower than the reference voltage. When it exceeds, the rotation control signal Vs is supplied, that is, the control is intermittent.

In particular, it is desired to mount such an intermittent operation control circuit in a high-power motor M that is driven to rotate at a relatively high drive voltage (for example, 140 V to 150 V), such as an inverter motor.

[0007]

However, in the above-described intermittent control configuration, the motor M is controlled based on overheat detection.
Stops rotating and the ambient temperature of the thermistor S drops,
When the temperature detection voltage drops below a predetermined reference temperature, a rotation control signal Vs is supplied to the rotation control unit 7, and a drive current is supplied from this rotation control unit 7 to the motor M, which is immediately restarted.

When the ambient temperature of the thermistor S rises due to the restart and exceeds the reference temperature, the rotation control signal Vs is cut off again, and the drive current is no longer supplied from the rotation control unit 7 to the motor M. The rotation is stopped.

That is, even if the ambient temperature of the thermistor S disposed in the motor M rises or falls slightly around the reference temperature, the rotation control signal Vs is intermittent.
The energization of the drive current to the motor M is turned on / off, and the rotation / stop of the motor M is repeated. Therefore, the original rotation control of the motor M tends to be difficult, and there is a problem that the motor M is liable to malfunction or be damaged.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and suppresses the intermittent operation of the motor with respect to a slight temperature change accompanying the rotation operation while securing the original rotation control of the motor. It is another object of the present invention to provide an intermittent operation control circuit capable of preventing damage to the motor.

[0011]

SUMMARY OF THE INVENTION In order to solve such a problem, an intermittent operation control circuit of the present invention controls the starting and stopping of a motor through a rotation control unit that controls the rotation of the motor based on a rotation control signal. A temperature detecting element arranged on the stator side of the motor to detect a temperature of the arrangement environment; a first reference temperature and a second reference temperature higher than the first reference temperature.
Comparison of the reference temperature with the temperature detected by the temperature detection element,
When the detected temperature rises above the first reference temperature and exceeds the second reference temperature, an off-control signal is continuously output, and the detected temperature falls below the second reference temperature and drops to the first reference temperature. A comparison unit that continuously outputs an ON control signal when the rotation control signal is exceeded, and a switching unit that switches OFF or ON the transmission of the rotation control signal to the rotation control unit in accordance with the OFF or ON control signal from the comparison unit. ing.

In the present invention, it is preferable that the temperature detecting element is disposed on a drive coil disposed on the stator side of the motor.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals are given to portions common to the conventional example.

FIG. 1 is a circuit diagram showing an embodiment of an intermittent operation control circuit according to the present invention. In FIG. 1, between a power supply terminal P2 connected to a plus power supply + Vcc1 and a power supply terminal P3 connected to a minus power supply -Vcc1.
A series circuit of the resistor R1 and the thermistor S and a series circuit of the resistor R2 and the resistor R3 are connected in parallel.

The plus-side power supply + Vcc1 and the minus-side power supply -Vcc1 are connected to a stabilizing power supply (not shown), and the resistors R2 and R3 obtain a reference voltage (for example, 0 V) by dividing them as described later. Power supply + Vcc1 or minus power supply -Vc
In some cases, it is connected to another positive or negative power supply larger or smaller than c1.

An inverting input terminal of an operational amplifier OP is connected to a connection point between the resistor R1 and the thermistor S, and the resistors R2 and R
The non-inverting input terminal of the operational amplifier OP is connected to the connection point 3 via the resistor R5.

The voltage V at the connection point between the resistor R1 and the thermistor S
IN corresponds to the temperature detected by the thermistor S, and the thermistor S is disposed in the drive coil L as described later.

The output terminal of the operational amplifier OP is connected to a feedback resistor R4.
, Is connected to the non-inverting input terminal of the same operational amplifier OP, is connected to the base of a transistor Q as a semiconductor switch, and outputs the output voltage V of the operational amplifier OP.
OUT is applied to the base of transistor Q.

The main body of the operational amplifier OP is supplied with, for example, a plus power supply + VOH1 and a minus power supply -VOL which are larger than the above-mentioned plus power supply + Vcc1 and minus power supply -Vcc1 from the above-mentioned stabilizing circuit. ing.

The values of the resistors R4 and R5 depend on the voltage VIN described above.
Is the voltage V corresponding to the stop temperature (the second reference temperature in FIG. 2) at which the motor M is stopped in the rotation control state of the motor M.
In the stopped state of the motor M, the voltage V1 becomes lower than the stop temperature (second reference temperature) and corresponds to the start restart temperature (first reference temperature in the same figure) at which the motor M starts and restarts. The comparison section 11 is formed by these.

The collector of the transistor Q supplies the rotation control signal Vs from the input terminal P5 to the input terminal P1 of the rotation control unit 7.
Is connected via a terminal P4 to the rotation control signal system 13 for transmission to the negative power source -VOL of the operational amplifier OP.
And the intermittent operation control circuit 15 according to the present invention.
Is configured.

The rotation control unit 7 is a conventionally known one.
A subtraction unit 1 connected directly or indirectly to the input terminal P1 for comparing the rotation control signal (servo signal) Vs with the speed (rotation speed) signal and outputting a deviation; A drive unit 3 for driving a motor (not shown) of the motor by supplying a motor drive current and driving the motor so as to reduce the deviation thereof, and detecting and subtracting a speed (rotation speed) of the motor M. 1 is provided with a speed detection unit 5 for outputting a speed (rotational speed) signal to the control unit 1.

In the vicinity of the drive coil L, for example, the drive coil L on the stator side and salient pole teeth (not shown) wound therearound,
Thermistor S is attached by appropriate means,
It is connected so as to be inserted between the resistor R1 of the intermittent operation control circuit 15 and the power supply terminal P3.

For convenience, in FIG. 1, the thermistor S is shown near the intermittent operation control circuit 15 and also near the drive coil L of the rotation control unit 7, but they are all the same.

The motor M is, for example, a known brushless motor, but is not limited to this, and may have any conventionally known configuration similar to the rotation control unit 7.

Next, the operation of the configuration according to the present invention will be described. First, the ambient temperature of the drive coil L of the motor M is shown in FIG.
As described above, the first and second reference temperatures, which are lower, that is, when the motor M is started or when the motor M rotates normally will be described.

In this state, the resistance value of the thermistor S is large, and the voltage VIN at the connection point with the resistor R1 is high. This voltage is applied to the inverting input terminal of the operational amplifier OP, and the voltage of the output terminal is obtained. As shown in FIG. 3, VOUT is a saturated negative potential −VOL, and FIG.
This is applied as an ON control signal to the base of the transistor Q, and is positively fed back to the non-inverting input terminal.

Therefore, the transistor Q is turned off, the transistor Q is disconnected from the rotation control signal system 13, the rotation control signal Vs is transmitted to the rotation control unit 7, and the rotation control is performed according to the rotation control signal level. The unit 7 drives the motor M to rotate.

Next, a description will be given of a state in which the ambient temperature becomes higher than the second reference temperature due to the heat generated by the drive coil L due to the rotational driving of the motor M.

When the ambient temperature rises due to the heat generated by the drive coil L and the resistance value of the thermistor S gradually decreases beyond the first reference temperature as shown in FIG. 2A, the inversion of the operational amplifier OP which is the connection point with the resistance R1 is performed. Although the voltage level VIN at the input terminal decreases, the voltage level V2 at the non-inverting input terminal of the operational amplifier OP is lower, and the output voltage VOUT at the output terminal of the operational amplifier OP continues to be saturated at the minus potential -VOL.

When the ambient temperature rises due to the heat generated by the drive coil L and the detected temperature exceeds the second reference temperature and the resistance value of the thermistor S further decreases as shown in FIG. 2A, the voltage level VIN at the inverting input terminal is reduced. Drops below the voltage level V2 at the non-inverting input terminal, and the output VOUT at the output terminal of the operational amplifier OP is switched to the plus potential + VOH as shown in FIG. 3, which becomes an off control signal as shown in FIG. While the non-inverting input terminal of OP rises to the voltage level V1, the transistor Q is turned on to short-circuit the rotation control signal system 13.

As a result, the signal level of the rotation control signal Vs is greatly reduced to approach the "0" potential, and the rotation control unit 7 stops rotating the motor M.

Here, the voltage level V1 can be expressed by the following equation. V1 = {R5 / (R5 + R4)} VOUT + {R4 / (R5 + R4)} {R3 / (R3 + R2)} Vcc1-(-Vcc1)} = {R5 / (R5 + R4)} (+ VOH) + {R4 / (R5 + R4) ｝ VREF However, VOUT = (+ VOH), VREF = ｛R3 / (R3 + R
2) $ 2Vcc1

Here, if R2 = R3, Vcc1 <<
Since VOH, VREF is so small that it can be ignored.
The voltage level V1 is as follows. V1 = {R5 / (R5 + R4)} (+ VOH)

Next, a state in which the temperature around the drive coil L starts to drop due to the stop of the rotation of the motor M will be described.

When the rotation of the motor M is stopped, the driving coil L
When the ambient temperature starts to decrease, the resistance value of the thermistor S also starts to increase. However, since the voltage level V1 at the non-inverting input terminal of the operational amplifier OP is in a high state, the resistance of the thermistor S increases and the transistor Q is turned on. , The output terminal of the operational amplifier OP is maintained at the positive potential + VOH as shown in FIG. 3, the ON state of the transistor Q is continued, and the motor M is also turned on. The rotation stops.

Then, the ambient temperature of the drive coil L further decreases, the resistance of the thermistor S further increases, and the operational amplifier O
When the voltage level VIN at the inverting input terminal of P becomes higher and exceeds the voltage level V1 at the non-inverting input terminal, the output VOUT at the output terminal of the operational amplifier OP is switched to the negative potential -VOL as shown in FIG. As shown in FIG. 2B, the ON control signal is output, and the voltage level of the non-inverting input terminal of the operational amplifier OP decreases to V2.

This voltage level V2 can be expressed by the following equation, similarly to V1. V2 = ｛R5 / (R5 + R4)｝ VOUT + ｛R4 / (R5 + R4)｝ VREF = ｛R5 / (R5 + R4)｝ (− VOL) + ｛R4 / (R5 + R4)｝ VREF where VOUT = (− VOL)

Again, if R2 = R3, then Vcc1 <
Since <VOL, the voltage level V2 is as follows, similarly to V1. V2 = {R5 / (R5 + R4)} (-VOL)

On the other hand, the transistor Q is turned off to be disconnected from the rotation control signal system 13, and the rotation control unit 7 starts the motor M according to the level of the rotation control signal Vs.

When the ambient temperature starts to rise again due to the heat generated by the driving coil L, the resistance value of the thermistor S also gradually decreases, and the voltage level V at the inverting input terminal of the operational amplifier OP.
Although IN decreases, the voltage level of the non-inverting input terminal has dropped to V2. Therefore, the output terminal of the operational amplifier OP maintains the negative potential -VOL until reaching this voltage level, and thereafter, the above-described operation is repeated.

That is, the comparison section 11 functions as a circuit having a hysteresis (history curve) characteristic or a Schmitt trigger characteristic, and the hysteresis width is the temperature between the first reference temperature and the second reference temperature as shown in FIG. It is represented by a potential difference VTH corresponding to the difference, and VTH can be represented by the following equation. VTH = V1-V2 = {R5 / (R5 + R4)} VOH-(-VOL)}

According to this, assuming that the power supply voltages + VOH and -VOL supplied to the operational amplifier OP are constant,
The potential difference VTH corresponding to the temperature difference between the first and second reference temperatures is determined by the values of the resistors R4 and R5.

As described above, the intermittent operation control circuit 15 of the present invention
Then, a thermistor S that is arranged on the stator-side drive coil L of the motor M and detects the temperature of this arrangement environment, and a first reference temperature and a second reference temperature higher than the first reference temperature and the temperature detected by the thermistor S are used as voltages. When the detected temperature rises and exceeds the first reference temperature and exceeds the second reference temperature, an off control signal is continuously output, and the detected temperature falls and exceeds the second reference temperature. A comparing unit 11 that continuously outputs an on-control signal when the temperature exceeds the first reference temperature; and turning off or on the transmission of the rotation control signal Vs to the rotation control unit 7 by the off or on control signal from the comparing unit 11. The motor M is controlled based on the rotation control signal Vs until the temperature of the drive coil L rises above the first reference temperature and exceeds the second reference temperature. The other hand, when the temperature of the drive coil L rises above a further second reference temperature, the motor M based on the blocking of the rotation control signal Vs is temporarily stop control.

Further, even if the temperature of the drive coil L drops below the second reference temperature due to the stop of the rotation of the motor M, the cutoff state of the rotation control signal Vs is continued until the temperature reaches the first reference temperature lower than this. When the temperature falls below the first reference temperature, the rotation control signal Vs is transmitted to the rotation control unit 7 again, and the motor M is controlled to start.

Therefore, if the temperature of the drive coil L of the motor M once stopped is slightly reduced, the motor M is continuously controlled to stop, while the temperature is lowered to the first reference temperature and the start control is performed. Since the stop control is not performed unless the temperature rises to the second reference temperature higher than the temperature at the time of the stop control, the stop and start of the motor M due to the slight temperature change of the drive coil L is not repeated, and the steady operation of the motor M can be secured and the motor M can be secured. M malfunction or damage can be prevented.

In the above-described present invention, the thermistor S is used as an element for detecting the temperature of the drive coil L. However, the present invention is not limited to this. Any temperature detecting element that is arranged on the stator side of the motor M and converts the temperature of this arrangement environment into an electric signal and detects the electric signal may be used, and the arrangement position is arbitrary.

When a large output motor M, such as an inverter motor, which is driven to rotate with relatively large electric power by a brushless motor, a large drive current flows through the drive coil L disposed on the stator side, so that heat is easily generated. By arranging it in or near the drive coil L, it is possible to prevent erroneous operation and damage of this type of motor, and to enhance durability.

In the present invention, the operational amplifier O
The hysteresis characteristic or the Schmitt trigger characteristic is obtained by using P and the voltage dividing resistors R4 and R5 connected thereto, but any electronic circuit having such a hysteresis characteristic or the Schmitt trigger characteristic can be used other than the operational amplifier OP. It is.

The point is that the first reference temperature and the second reference temperature higher than the first reference temperature are compared with the detected temperature from the thermistor S, and the detected temperature rises above the first reference temperature and the second reference temperature rises. When a comparator is used which continuously outputs an off-control signal when the temperature exceeds the reference temperature, and continuously outputs an on-control signal when the detected temperature falls below the second reference temperature and exceeds the first reference temperature. The object of the present invention can be achieved.

In addition, the setting of the first and second reference temperatures and the potential difference VTH corresponding to the temperature difference between these reference temperatures is also arbitrary. In the configuration of FIG. And the value of the power supply voltage + VOH, -VOL supplied to the operational amplifier OP main body and the resistance R
4, R5 may be appropriately selected.

Further, in the configuration described above, the switching unit
Although the transistor Q, which is a semiconductor switch, is used, in the present invention, it can be formed by a general semiconductor switch, a mechanical relay, or the like.

By the way, in the above-described configuration, if the level of the rotation control signal Vs is externally or internally changed at a stage before the subtraction unit 1 of the rotation control unit 7, the rotation speed of the motor M can be changed. It goes without saying that you can do it.

[0054]

As described above, according to the present invention, the temperature detecting element is arranged on the stator side of the motor to detect the environmental temperature of the arrangement, and the first reference temperature and the second reference temperature higher than this are compared with the first reference temperature. A comparison unit for comparing the detected temperature with the detected temperature is provided. When the detected temperature rises from the first reference temperature and exceeds the second reference temperature, an off-control signal is continuously output. When the temperature falls below the second reference temperature and exceeds the first reference temperature, an ON control signal is continuously output, and based on the OFF or ON control signals from the comparison unit, the switching unit outputs a rotation control signal to the rotation control unit based on the OFF or ON control signal. Since the transmission is turned off or on, the simple circuit configuration allows the motor to operate intermittently with respect to excessive heat generated by the rotation while securing the original rotation control of the motor.
Intermittent operation due to a slight temperature change can be suppressed, and damage to the motor can be prevented. According to the present invention, in a configuration in which the temperature detecting element is arranged on a drive coil arranged on a stator side of a motor, particularly, in a brushless motor that is rotationally driven with relatively large power, the motor generates heat from the drive coil. Can be prevented, and the durability can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of an intermittent operation control circuit according to the present invention, together with a rotation control unit.

FIG. 2 is a diagram illustrating the operation of the intermittent operation control circuit of FIG. 1 together with the temperature detected by a temperature detecting element.

FIG. 3 is a diagram illustrating the operation of the intermittent operation control circuit in FIG. 1;

FIG. 4 is a circuit diagram showing a conventional intermittent operation control circuit together with a rotation control unit.

[Explanation of symbols]

 Reference Signs List 1 subtraction unit 3 drive unit 5 speed detection unit 7 rotation control unit 9 switching unit 11 comparison unit 13 rotation control signal system 15 intermittent operation control circuit L drive coil M motor OP operational amplifier (comparison unit) P1, P2, P3, P4, P5 Terminal Q Transistor (switching unit) R1, R2, R3, R4, R5 Resistance S Thermistor (Temperature detecting element) First reference temperature Second reference temperature

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H530 AA09 CC25 CD02 CD30 CF01 DD03 DD23 5H560 BB04 BB12 DC05 EB01 HA07 JJ02 JJ06 TT05 UA02

Claims (2)

[Claims] 1. An intermittent operation control circuit for a motor that controls the start and stop of the motor via a rotation control unit that controls the rotation of the motor based on a rotation control signal, wherein the intermittent operation control circuit is arranged on a stator side of the motor. A temperature detection element for detecting the temperature of the environment, a first reference temperature and a second reference temperature higher than the first reference temperature and a temperature detected by the temperature detection element, and the detected temperature is set to the first reference temperature. When the detected temperature exceeds the second reference temperature and the detected temperature falls below the second reference temperature and exceeds the first reference temperature, the ON control signal is continuously output. A comparison unit for outputting, and a switching unit for switching off or on the transmission of the rotation control signal to the rotation control unit according to the off or on control signal from the comparison unit. Intermittent operation control circuit of the data. 2. The intermittent operation control circuit for a motor according to claim 1, wherein said temperature detecting element is arranged on a drive coil arranged on a stator side of said motor.