JPH10174485A - Drive circuit of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce number of parts and simplify the constitution and manufacture process by checking the frequency of the periodical signal from an oscillator at a temperature detecting section which changes corresponding to the resistance value of a temperature detector, according to the rise and fall of the temperature of a motor, thereby judging the temperature of the motor and outputting a temperature detection signal. SOLUTION: The output from an astable oscillating circuit 39, whose periodical oscillation changes corresponding to the change of the resistance value R3 of a thermistor according to the temperature of a motor detected by a temperature detector is a detection signal four of the output from the thermistor. The detection signal foot is inputted into the temperature detector of a frequency distinguished 40. According to the result distinguished for outputting power suitable to the temperature of the motor, the motor is supplied with a drive current, so that it may become the rotational speed corresponding to the temperature that the controller 41 detects. Also, a buzzer and an indicator are driven in accordance with the detection at the controller 41. As a result, the number of parts can be reduced, the constitution can be simplified, the initial dispersion of the driven circuit of the motor can be suppressed, the initial adjustment of the circuit property is made unnecessary, and the manufacture process can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driving circuit, and more particularly, to a motor driving circuit for detecting a motor temperature in a digital manner and rotating the motor at a rotation speed corresponding to the temperature.

[0002]

2. Description of the Related Art Conventionally, as a function of a drive circuit for controlling the rotation speed of a motor, there is a function of rotating the motor at a rotation speed corresponding to its temperature. As an example, when the temperature of the motor increases, the rotation speed is correspondingly increased. In the related art related to the function of controlling the rotation speed of the motor in accordance with the temperature of the motor, a temperature detection element such as a thermistor is provided in the motor, and a temperature signal from the temperature detection element is transmitted to a resistor, a capacitor, a coil, Is provided in a motor drive circuit and is output as a voltage signal.

As a prior art relating to such a temperature detecting function, there is a drive circuit 1 shown in FIG. Drive circuit 1
, An inverter 3 is connected in parallel with the thermistor 2, and an oscillator 4 is commonly connected to the thermistor 2 and the inverter 3. The thermistor 2 and the inverter 3 are connected to a differential amplifier 8 via resistors 5, 6, and 7, respectively. Therefore, when the thermistor 2 detects the ambient temperature and changes its resistance value, the period of the signal input to the differential amplifier 8 changes. The amplitude of this signal is amplified by the differential amplifier 8, and a low-pass filter 9 outputs a voltage signal that changes in accordance with the change in the period.

The voltage signal is compared with predetermined reference voltages Vth1 and Vth2 (for example, Vth1> Vth2) by a voltage comparator 12 having comparators 10 and 11. When the voltage value of the voltage signal is smaller than the reference voltage Vth2, each comparator 1
Reference numerals 0 and 11 output predetermined signals of the same polarity to the control unit 13. At this time, the control unit 13 controls the rotation speed of a motor (not shown) according to the temperature.

[0005]

In the above prior art, the circuit for detecting the temperature of the motor has an analog circuit configuration.
It has the following problems.

It is necessary to use various analog circuit elements, and the number of components increases. In addition, specific variations of each circuit element are integrated, and initial variations in characteristics of a motor drive circuit are large. For this reason, it is necessary to arrange a characteristic variable element such as a variable resistor in the drive circuit to adjust the circuit characteristics, and it takes time and effort to manufacture.

[0007] Various circuit elements used in analog circuits often vary in their characteristics depending on the external temperature, and the operating characteristics of the drive circuit are affected by the external temperature and become unstable. In order to solve this problem, it is necessary to provide a compensating circuit for compensating for the temperature change of the characteristic of the circuit element, and the number of parts increases, and the configuration becomes complicated.

If an attempt is made to control the rotation speed of the motor corresponding to the temperature of the motor by digital control using a microcomputer or the like, a voltage change corresponding to a change in the temperature of the motor is converted into a digital signal by an analog / digital conversion circuit. In this regard, the number of components also increases, and the circuit configuration becomes complicated. In addition, the cost is increased.

The first and second aspects of the present invention have been made to solve the above problems, and an object of the invention is to reduce the number of parts, simplify the configuration, and eliminate the need for initial adjustment during manufacturing. Accordingly, it is an object of the present invention to provide a motor drive circuit that can simplify a manufacturing process and easily perform digital processing.

[0010]

In the motor driving circuit according to the present invention, the temperature of the motor is detected by a temperature detecting element whose resistance changes in accordance with the temperature of the motor. The frequency of the periodic signal output from the oscillating unit changes according to the resistance value of the temperature detecting element that changes according to the motor temperature. The periodic signal from the oscillating unit is input to the temperature detecting unit, which discriminates the frequency of the periodic signal, determines the temperature of the motor, and outputs a temperature detecting signal.

Thus, in the motor driving circuit according to the present invention, the change in the resistance value of the temperature detecting element is converted into the change in the frequency of the periodic signal, and the structure including the oscillation section and the temperature detecting section is provided. A digital circuit configuration can be used. Thus, the oscillating unit, the temperature detecting unit, and the like can be configured by a small number of circuit elements such as a gate circuit, and the number of components is reduced, and the configuration is simplified. For this reason, the initial variation of the motor drive circuit can be suppressed, the initial adjustment of the circuit characteristics becomes unnecessary, and the manufacturing process is simplified.

Since the necessity of using an analog circuit element has been eliminated, a situation in which the operating characteristics of the motor drive circuit are affected by the external temperature is prevented. Further, the temperature change compensating circuit described in the section of the related art becomes unnecessary, and the number of parts is reduced and the configuration is simplified also in this regard.

Further, a variable corresponding to the temperature of the external atmosphere output from the oscillation section is a frequency of a periodic signal, which is more than a conventional voltage change for digital processing such as an analog / digital conversion circuit. No special circuit is required, and digital processing can be easily performed.
Thus, the number of components can be reduced and the circuit configuration can be simplified.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. 1 to 6 show an embodiment of the present invention.

FIG. 1 is a block diagram showing an electric configuration of a motor driving circuit 21 according to one embodiment of the present invention, and FIG. 2 is a block diagram showing an entire electric configuration of the driving circuit 21 of this embodiment. FIG. 3 is a block diagram showing an embodiment of a frequency discriminator provided in the drive circuit 21, and FIG. 4 is a graph showing electric characteristics of the thermistor of the present embodiment.
Is a waveform diagram for explaining the operation of the drive circuit 21, and FIG. 6 is a block diagram showing another configuration example of the frequency discriminator.

Hereinafter, the electrical configuration of the drive circuit 21 will be described with reference to FIG. In the drive circuit 21, the thermistor 28 is connected to a control device 30 composed of a microcomputer or the like, and a motor 33 and a buzzer 34 are connected. The buzzer 34 is sounded by the control device 30 when an abnormal condition occurs, for example, to notify the user of the occurrence of the abnormal condition.

Referring now to FIG. 1, a description will be given of a configuration for controlling the rotation of the motor in the drive circuit 21 of this embodiment at a rotation speed corresponding to the temperature. A capacitor 32 is connected in series with the thermistor 28 having a temperature-resistance value characteristic shown in FIG. 4 and having a resistance value R3 (variable value), and a resistor R1 is connected in parallel to the thermistor 28 and the capacitor 32 at connection points a and b. , And a resistor R2 is connected in series to a connection point b of the thermistor 28. In parallel with the resistors R1 and R2,
Between the connection points a and b, a resistor Rs, inverters 36 and 3
A series circuit consisting of 7 and 38 is connected. A capacitor CT is connected in parallel with the resistor Rs and the inverters 36 and 37.
Are connected at connection points a and c. Thus, the thermistor 28, the resistors R1, R2, Rs, and the inverter 3
6, 37 and 38 and the capacitor CT are connected to the thermistor 28.
An astable multivibrator (hereinafter referred to as an oscillation circuit) 39 whose oscillation cycle changes in response to a change in the resistance value R3 of FIG. The output from the oscillation circuit 39 is output from the thermistor 28.
Is the detection signal fout, which is the output from.

The resistor R1 is for preventing abnormal oscillation of the oscillation circuit 39 when the resistance value of the thermistor 28 decreases, and the resistor R2 is for protecting a digital circuit such as a gate circuit constituting the thermistor 28 and the oscillation circuit 39. The resistor Rs is a current limiting resistor for input protection.

Since the thermistor 28 is incorporated in an oscillation circuit 39 realized by an astable multivibrator, an AC voltage is always applied to the thermistor 28. When a DC voltage is applied to the thermistor 28, if moisture adheres to the thermistor 28, the moisture is electrolyzed, and a decomposed substance adheres to the thermistor 28, thereby lowering detection accuracy. In the drive circuit 21 of the present embodiment, the AC voltage is always applied to the thermistor 28, so that the occurrence of this problem is prevented.

The detection signal fout is transmitted to the controller 30.
The frequency of the detection signal fout is input to the frequency discriminator 40 provided in the control unit 30. According to the result of the discrimination, the control unit 41 provided in the control unit 30 controls the motor 33,
The drive of the buzzer 34 and the display unit 35 is controlled. As will be described later, the frequency discriminator 40 and the control unit 41 can be configured by digital circuits such as a microcomputer and a gate circuit, for example. This frequency discriminator 4
The frequency discrimination of 0 can be realized by counting the number of pulses per unit time of the detection signal fout from the oscillation circuit 39 or by measuring the period per unit number of pulses.

That is, the detection signal fout from the oscillation circuit 39
Is expressed as fout = 1 / (2.2RT · CT) (1) when RT = R1 / R3 + R2 and the threshold voltages VTH1 = VDD / 2 of the inverters 36, 37, and 38. It becomes a function of the resistance R3 of the thermistor 28.
Therefore, if the frequency fout or the period 1 / fout is measured according to the above-mentioned method or the method of the above-described method, the resistance value R3 of the thermistor 28 can be measured, and the temperature of the external atmosphere detected by the thermistor 28 Can be detected.

Referring to FIG. 3, an example of the structure of the frequency discriminator 40 will be described. The frequency discriminator 40 of this configuration example counts the number of pulses of the detection signal fout per predetermined unit time. In this configuration example,
The frequency discriminator 40 performs a counting operation each time the detection signal fout from the oscillation circuit 39 is input.
2, a latch circuit 43 for latching the count value of the counter 42 at a timing described later, and predetermined reference data B and C (B> C), respectively, using the count value latched by the latch circuit 43 as input data A. And a comparator 44 which is compared from a digital circuit to be compared. A periodic signal T having a fixed period T is input to the frequency discriminator 40, the periodic signal T is input as a latch signal to the latch circuit 43, and a signal obtained by delaying the periodic signal T by a delay The signal is input to the counter 42 as a reset signal.

Accordingly, the counter 42 performs the counting operation of the detection signal fout during the fixed period T, and the count value NN = T.fout (2) when the periodic signal T is input is latched. Latched at 43. The latched count value N is input to the control unit 41 as input data A. The control unit 41 supplies a drive current to the motor 33 such that the rotation speed corresponds to the detected temperature, as shown in FIG.

Hereinafter, the operation of the drive circuit 21 according to the present embodiment will be described with reference to FIG. FIG. 5A is a block diagram showing an equivalent electrical configuration in which a main part of the electrical configuration of the drive circuit 21 shown in FIG. 1 is simplified.
(2) to (4) show waveforms at various points in the configuration of FIG. 5 (1). In the block diagram of FIG. 1, the connection point b of the resistor R2 on the opposite side of the thermistor 28 is connected to the output terminal of the inverter 36 having the same polarity as the output terminal of the inverter 38 in FIG. In the block diagram of FIG. 5A, the signal waveform of the potential Va at the connection point a is shown in FIG. 5B, and the signal waveform of the voltage Vd between the terminals of the thermistor 28 is shown in FIG. The signal waveform of the potential Vc at c is shown in FIG.

In the driving circuit 21 of this embodiment, a pulse signal having a constant frequency as shown in FIG. 5B is generated at the connection point a. This pulse signal is integrated by the integrating circuit of the thermistor 28 and the capacitor 32 to form a waveform shown in FIG. 5C, and the frequency also changes according to the resistance of the thermistor 28. Further, the signal having the waveform shown in FIG. 5C is shaped by the inverter 37 to have the waveform shown in FIG. These signals are taken into the control unit 41 shown in FIG. The control unit 41 controls the motor 33 according to the control pattern shown in FIG. That is, control is performed to increase the rotation speed of the motor 28 as the temperature T detected by the thermistor 28 increases.

As described above, in the drive circuit 21 of the present embodiment, a change in the resistance value of the thermistor 28 is converted into a change in the frequency of the periodic signal fout, and the temperature of the motor 33 is detected. Circuit 39 and control device 30
Can be a digital circuit configuration. Thus, the configuration including the oscillation circuit 39 and the control device 30 can be configured with a small number of circuit elements such as a gate circuit, and the number of components is reduced, and the configuration is simplified. For this reason, the initial variation of the drive circuit 21 can be suppressed, the initial adjustment of the circuit characteristics becomes unnecessary, and the manufacturing process is simplified.

Further, in the driving circuit 21 of this embodiment,
Since the necessity of using an analog circuit element has been eliminated as described above, a situation in which the operating characteristics of the drive circuit 21 are affected by the external temperature is prevented. Further, as compared with the configuration using the analog circuit element of the related art, the temperature change compensating circuit becomes unnecessary, and the number of parts is reduced and the configuration is simplified also in this regard.

Further, the output signal fout output from the oscillation circuit 39 is a periodic signal, and the temperature of the motor 33 is detected as a frequency change. Therefore, compared to the operation of detecting the presence or absence of urination based on a voltage change as in the related art, a special circuit for digital processing such as an analog / digital conversion circuit becomes unnecessary, and digital processing can be easily performed. Can be. Thus, the number of components can be reduced and the circuit configuration can be simplified.

FIG. 7 is a block diagram showing another example of the structure of the frequency discriminator 40. Frequency discriminator 40 of the present embodiment
"a" measures the elapsed time of the detection signal fout per a predetermined number of unit pulses. In this configuration example, the frequency discriminator 40a detects the detection signal f from the oscillation circuit 39.
out is counted n times, and a counter 52 that outputs a latch signal from the output terminal CA when the count operation is completed n times, and a latch signal from the counter 52 are input. ′. A clock signal f1 having a frequency f1 much higher than the detection signal fout is input to the frequency discriminator 40a, and the clock signal f1 is input to the counter 56 as a count signal. The latch signal from the counter 52 is supplied to the delay circuit 5
5, the signal is delayed by a predetermined period and input to the counter 56 as a reset signal.

Therefore, the counter 52 outputs the detection signal fout
The counter 56 counts the clock signal f1 over a period in which n is counted. When the counter 52 counts the detection signal fout n times, a latch signal is output from the counter 52, the counter 56 is reset, and the count value of the counter 56 at that time is stored in the latch circuit 53 as the periodic data N '. Latched. This period data N 'is a signal period per n detection signals fout.

Time n / f over n cycles of detection signal fout
out is the time N '/ f1 over the N' period of the clock signal
N / fout = N '/ f1 (3) By transforming this, N' = n.f1 / fout (4) That is, the cycle data N 'is a function of the frequency fout of the detection signal from the oscillation circuit 39. Therefore, by detecting the periodic data N ′, the control device 30
Can determine the degree of the temperature of the external atmosphere detected by the thermistor 28.

By using the frequency discriminator 40a of this embodiment, the same operation as the temperature detection operation of the motor 33 described in the above embodiment can be performed.

The configuration and operation of the above embodiment show one embodiment of the present invention, and do not limit the present invention. The present invention includes a wide variety of modifications without departing from the spirit of the present invention.

[0034]

As described above, in the motor drive circuit according to the first aspect of the present invention, the temperature of the motor is detected by the temperature detecting element whose resistance changes in accordance with the temperature of the motor. The frequency of the periodic signal output from the oscillating unit changes according to the resistance value of the temperature detecting element that changes according to the motor temperature. The periodic signal from the oscillating unit is input to the temperature detecting unit, and the temperature detecting unit discriminates the frequency of the periodic signal,
The motor temperature is determined and a temperature detection signal is output.

Thus, in the motor driving circuit according to the present invention, the change in the resistance value of the temperature detecting element is converted into the change in the frequency of the periodic signal, and the structure including the oscillation section and the temperature detecting section is provided. A digital circuit configuration can be used. Thus, the oscillating unit, the temperature detecting unit, and the like can be configured by a small number of circuit elements such as a gate circuit, and the number of components is reduced, and the configuration is simplified. For this reason, the initial variation of the motor drive circuit can be suppressed, the initial adjustment of the circuit characteristics becomes unnecessary, and the manufacturing process is simplified.

Since the necessity of using an analog circuit element has been eliminated, a situation in which the operating characteristics of the motor drive circuit are affected by the external temperature is prevented. Further, the temperature change compensating circuit described in the section of the related art becomes unnecessary, and the number of parts is reduced and the configuration is simplified also in this regard.

Further, the variable corresponding to the temperature of the external atmosphere output from the oscillating unit is the frequency of the periodic signal, which is smaller than the voltage change of the prior art for digital processing such as an analog / digital conversion circuit. No special circuit is required, and digital processing can be easily performed.
Thus, the number of components can be reduced and the circuit configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a drive circuit 21 according to one embodiment of the present invention.

FIG. 2 is a block diagram illustrating the entire electrical configuration of a drive circuit 21 according to the present embodiment.

FIG. 3 is a block diagram showing one embodiment of a frequency discriminator of the drive circuit 21.

FIG. 4 is a graph showing electric characteristics of the thermistor 28 according to the present embodiment.

FIG. 5 is a diagram illustrating an operation of a drive circuit 21.

FIG. 6 is a diagram illustrating an operation of a control unit 41.

FIG. 7 is a block diagram showing another configuration example of the frequency discriminator.

FIG. 8 is a block diagram illustrating an electrical configuration of a driving circuit 1 according to the related art.

[Explanation of symbols]

 21 Drive circuit 28 Thermistor 33 Motor 32, CT capacitor 36, 37, 38 Inverter 39 Oscillation circuit 40, 40a Frequency discriminator 41 Control unit 42, 52, 56 Counter 43, 53 Latch circuit 44, 54 Comparator 45, 55 Delay circuit f1 clock signal fout detection signal N count value N 'period data R1, R2, Rs resistance

Claims (1)

[Claims] A temperature detecting element whose resistance value changes in accordance with the temperature of the motor; an oscillating section for outputting a periodic signal whose frequency changes in accordance with the resistance value of the temperature detecting element; A temperature detecting unit that discriminates the temperature of the motor by discriminating the frequency of the periodic signal from the motor and outputs a temperature detection signal; and, based on the detection signal from the temperature detecting unit, the rotation of the motor corresponding to the temperature. And a control unit for rotating the motor at a speed.