JP4480325B2 - Single-phase motor drive circuit and single-phase motor drive method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving circuit for a single phase motor and a driving method of the single phase motor.
[0002]
[Prior art]
For example, in the motor driving system disclosed in Japanese Utility Model Publication No. 3-74199 (Patent Document 1), a thermistor has a variable speed function, and the comparator is based on a sawtooth voltage generated in response to a phase switching signal. An "H" pulse signal (control signal) for driving is output. This drive system has a variable speed function using a thermistor, and a detected temperature voltage based on the detected temperature of the thermistor is input to the comparator as a comparison input for the sawtooth voltage. That is, during the period when the sawtooth voltage is larger than the detected temperature voltage, the comparator outputs a pulse signal of “H”.
[0003]
This detected temperature voltage fluctuates within a certain range in accordance with a change in temperature detected by the thermistor. Therefore, the width of the “H” pulse signal output from the comparator is widened according to a change in the temperature detected by the thermistor. That is, the number of rotations of the motor can be made variable according to a change in the detected temperature of the thermistor.
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 3-74199
[0005]
[Problems to be solved by the invention]
By the way, the change amount of the detection voltage input to the comparator is small with respect to the change of the detection temperature of the thermistor. In other words, if the power source of the detected temperature voltage having a small change amount varies, the pulse signal of the comparator is accurately determined with respect to the change in the detected temperature of the thermistor. As a result, the rotational speed of the motor is inevitably unstable.
[0006]
[Means for Solving the Problems]
In the main invention according to the present invention, Single-phase motor drive circuit The detected temperature voltage that changes based on the temperature detected by the temperature detecting element is compared with the rotational speed setting voltage for setting a predetermined rotational speed of the single-phase motor, Either the detected temperature voltage or the rotation speed setting voltage so that the single-phase motor rotates at a higher rotation speed Is a duty setting voltage, and a sawtooth voltage with a predetermined period And the comparison result of the duty setting voltage A comparator that outputs a control signal for driving the single-phase motor; a detection temperature voltage generation circuit that generates the detection temperature voltage; and a rotation speed setting voltage generation circuit that generates the rotation speed setting voltage. Get .
Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
===== Summary of Disclosure =====
At least the following is revealed.
In the single-phase motor drive circuit according to the present embodiment, the detected temperature voltage that changes based on the temperature detected by the temperature detection element is compared with the rotational speed setting voltage for setting a predetermined rotational speed of the single-phase motor. Then, the smaller one of the detected temperature voltage and the rotation speed setting voltage is set as the duty setting voltage, and the control for driving the single-phase motor in a period in which the sawtooth voltage having a predetermined period is larger than the duty setting voltage. A comparator that outputs a signal; a detection temperature voltage generation circuit that generates the detection temperature voltage; and a rotation speed setting voltage generation circuit that generates the rotation speed setting voltage, the detection temperature voltage generation circuit and the rotation speed setting voltage The generation circuit generates the detected temperature voltage and the rotation speed setting voltage from a common power source.
[0008]
According to this configuration, both the rotation speed setting voltage and the detected temperature voltage compared by the comparator are generated by the common power source. Therefore, even if the voltage of the power supply varies, the comparator can stably output a control signal for driving the single-phase motor without being affected by the fluctuation. Therefore, it is possible to perform stable variable speed control according to the ambient temperature for the single-phase motor.
[0009]
The rotation speed setting voltage generation circuit includes a first rotation speed setting voltage generation circuit that generates a first rotation speed setting voltage, and a second rotation speed setting voltage generation that generates a second rotation speed setting voltage. And the first rotation speed setting voltage is a preset fixed setting voltage, and the second rotation speed setting voltage is a setting voltage that can be changed as appropriate. When the rotation speed setting voltage is smaller than the first rotation speed setting voltage, the second rotation speed setting voltage may be used as the rotation speed setting voltage.
[0010]
Further, the detected temperature voltage generation circuit, the first rotation speed setting voltage generation circuit, and the second rotation speed setting voltage generation circuit each have a voltage dividing resistor, and the detection temperature voltage, the first rotation speed setting voltage generation circuit, The rotation speed setting voltage and the second rotation speed setting voltage may be voltage division values generated by the voltage dividing resistor from the common power source.
[0011]
According to this configuration, each detected temperature voltage, the first rotation speed setting voltage, and the second rotation speed setting voltage are generated from a common power source with the ratio of each voltage dividing resistor. For this reason, even if the voltage of the common power supply varies, the output of the comparator to which each detected temperature voltage, the first rotation speed setting voltage, and the second rotation speed setting voltage are input is not affected. Therefore, even if the common power supply varies, the comparator can stably output a control signal for driving the single-phase motor.
[0012]
The circuit may further include a circuit that generates the sawtooth voltage and a control circuit that generates a drive signal based on the control signal and outputs the drive signal to the single-phase motor.
[0013]
Further, the circuit for generating the sawtooth voltage may be generated from the common power source.
[0014]
According to this configuration, the sawtooth voltage input to the comparator is generated from a common power source. Therefore, even if the common power supply varies, the comparator can stably output a control signal for driving the single-phase motor.
[0015]
Furthermore, at least the comparator and the control circuit may be constituted by an integrated circuit.
[0016]
The voltage dividing resistor that generates the second rotation speed setting voltage, which is a setting voltage that can be changed as appropriate, may be external to the integrated circuit.
[0017]
In the driving method of the single phase motor according to the present embodiment, the detected temperature voltage that changes based on the temperature detected by the temperature detecting element is compared with the rotational speed setting voltage for setting the predetermined rotational speed of the single phase motor. Then, the smaller one of the detected temperature voltage and the rotation speed setting voltage is set as the duty setting voltage, and the control for driving the single-phase motor in a period in which the sawtooth voltage having a predetermined period is larger than the duty setting voltage. A signal is output, and the detected temperature voltage and the minimum speed setting voltage are generated from a common power source.
[0018]
The first rotation speed setting voltage is a preset fixed setting voltage, the second rotation speed setting voltage is a setting voltage that can be changed as appropriate, and the second rotation speed setting voltage is When the rotation speed is smaller than the first rotation speed setting voltage, the second rotation speed setting voltage may be used as the rotation speed setting voltage.
[0019]
=== Overall Configuration of Single-Phase Motor Drive Device ===
The overall configuration of the single-phase motor drive circuit according to the present embodiment will be described with reference to the circuit block diagram of FIG. In the present embodiment, the single-phase motor driving circuit is basically composed of an integrated circuit, and components externally attached to the integrated circuit will be described later.
[0020]
As shown in FIG. 1, the NPN bipolar transistors 102 and 104 supply drive currents in the right direction (direction a) of the external single-phase coil 106 when the drive signals A and D are supplied. . Therefore, the collector-emitter path of the bipolar transistor 102, the single-phase coil 106, and the collector-emitter path of the bipolar transistor 104 are connected in series between the power supply VCC and the ground VSS. Similarly, the NPN bipolar transistors 108 and 110 supply a drive current in the left direction (b direction) of the single-phase coil 106 when the drive signals C and B are supplied. Therefore, the collector-emitter path of bipolar transistor 108, single-phase coil 106, and collector-emitter path of bipolar transistor 110 are connected in series between power supply VCC and ground VSS.
[0021]
Then, the bipolar transistors 102 and 104 and the bipolar transistors 108 and 110 are complementarily turned on and off, and the direction of the driving current of the single-phase coil 106 is appropriately changed, whereby the single-phase motor rotates. The regenerative diode 112 regenerates the drive current when the direction of the drive current of the single-phase coil 106 changes from the a direction to the b direction, and is connected in parallel to the collector-emitter path of the bipolar transistor 110. Similarly, the regenerative diode 114 regenerates the drive current when the direction of the drive current of the single-phase coil 106 changes from the b direction to the a direction, and is connected in parallel to the collector-emitter path of the bipolar transistor 104. .
[0022]
As described above, when the bipolar transistors 102 and 104 and the bipolar transistors 108 and 110 are complementarily turned on and off to rotate the single-phase motor, the driving duty of the rotation is determined according to the control signal output from the driving duty determination comparator CMP. Is done. That is, the drive duty determination comparator CMP includes a detected temperature voltage VTH, an internally set minimum speed voltage (first rotation speed setting voltage) VIN, an externally set minimum speed voltage (second rotation speed setting voltage) RMI, and 25 kHz. A triangular wave signal (saw-tooth voltage) PWM is input. Based on these inputs, the comparator CMP outputs a control signal. That is, when the bipolar transistors 102 and 104 and the bipolar transistors 108 and 110 are driven on and off, PWM (Pulse Width Modulation) control is performed.
[0023]
Therefore, as shown in FIG. 1, during the period in which the drive current is passed through the single-phase coil 106 in the direction of arrow a, the bipolar transistor 104 is always kept on, while the bipolar transistor 102 is turned on / off with a fundamental frequency of 25 kHz. On the other hand, during the period in which the drive current is passed through the single-phase coil 106 in the direction of the arrow b, the bipolar transistor 110 is always kept on, while the bipolar transistor 108 is turned on / off with a fundamental frequency of 25 kHz.
[0024]
In this embodiment, the control signal from the drive duty determination comparator CMP is the internal set minimum speed voltage VIN, the external set minimum speed voltage RMI, and the detected temperature voltage VTH with respect to the triangular wave signal PWM having a fundamental frequency of 25 kHz. Determined according to changes in The on / off operation of the bipolar transistors 102 and 104 and the bipolar transistors 108 and 110 is changed by the determined pulse signal, and the driving duty of the single-phase motor is controlled.
[0025]
The hall element 116 is fixed at a predetermined position facing the rotor-side magnet of the single-phase motor and is biased with a constant voltage. The Hall element 116 outputs a sine wave signal according to the rotational position of the single-phase motor, that is, according to the change in the magnetic poles on the opposite rotor side.
[0026]
The comparison circuit 118 has a hysteresis characteristic for preventing chattering, and converts the sine wave signal from the Hall element 116 into a rectangular wave signal. The rectangular wave signal is a commutation signal that is a basis for switching the driving current of the single-phase coil 106 in either the a direction or the b direction.
[0027]
The internally set minimum speed voltage VIN is a constant reference voltage that determines the minimum drive duty for setting the minimum rotation speed of the single-phase motor at a low temperature. This internally set minimum speed voltage VIN is a fixed set voltage preset in the integrated circuit constituting the single-phase motor drive circuit. As shown in FIG. 1, the internally set minimum speed voltage VIN is generated by an internally set minimum speed voltage generation circuit (first rotation speed setting voltage generation circuit) 200A. This internally set minimum speed voltage generating circuit 200A is configured by connecting voltage dividing resistors R21a and R22a in series between a power supply VCC and a ground VSS.
[0028]
This power supply VCC is the same as the power supply for generating the externally set minimum speed voltage RMI and the detected temperature voltage VTH.
An internally set minimum speed voltage VIN is obtained as a divided value from a connection point between the voltage dividing resistor R21a and the voltage dividing resistor R22a.
[0029]
The externally set minimum speed voltage RMI is a constant reference voltage that determines the minimum drive duty for setting the minimum rotation speed of the single-phase motor at a low temperature. This externally set minimum speed voltage RMI is a constant voltage generated by the externally set minimum speed voltage generation circuit (second rotational speed setting voltage generation circuit) 200B. The externally set minimum speed voltage generation circuit 200B is configured by connecting external voltage dividing resistors R21b and R22b in series between a power supply VCC and a ground VSS. The externally set minimum speed voltage RMI can be appropriately changed by setting the external voltage dividing resistors R21b and R22b.
[0030]
This power supply VCC is common to the power supply for generating the internally set minimum speed voltage VIN and the detected temperature voltage VTH.
An externally set minimum speed voltage RMI is obtained as a divided value from the connection point between the voltage dividing resistor R21b and the voltage dividing resistor R22b.
[0031]
The externally set minimum speed voltage RMI is set lower than the internally set minimum speed voltage VIN. As will be described later, when the externally set minimum speed voltage RMI is set by the external voltage dividing resistors R21b and R22b, the comparator CMP is subjected to a differential operation performed with a triangular wave signal (sawtooth voltage) PWM. The externally set minimum speed voltage RMI which is lower than the internally set minimum speed voltage VIN is preferentially selected.
[0032]
Alternatively, when the voltage dividing resistors R21b and R22b are not externally attached and the externally set minimum speed voltage RMI is not set, the external terminal RMI shown in FIG. 1 is externally provided with a detection voltage VTH by the thermistor (temperature detection element) Rs. Connect to terminal VTH. As a result, the externally set minimum speed voltage RMI becomes the same value as the detection voltage VTH, and only the internally set minimum speed voltage VIN remains as the reference voltage for setting the minimum rotation speed of the single-phase motor at low temperatures. It becomes. In addition, by connecting the external terminal RMI to the external terminal VTH, it is possible to prevent an inappropriate voltage from being generated at the external terminal RMI and the comparator CMP from malfunctioning.
[0033]
The detected temperature voltage VTH is generated by the detected temperature voltage generation circuit 300. The detection temperature voltage generation circuit 300 is configured by connecting an external thermistor (temperature detection element) Rs and a resistor R3 in series between a power supply VCC and a ground VSS.
This power supply VCC is the same as the power supply for generating the externally set minimum speed voltage RMI and the internally set minimum speed voltage VIN.
The thermistor Rs is attached to the fan housing in order to detect the ambient temperature of the fan driven by the single-phase motor. A detection temperature voltage VTH reflecting the ambient temperature of the fan is generated at a connection point between the thermistor Rs and the resistor R3. The thermistor Rs has a negative temperature coefficient, and the detected temperature voltage VTH decreases as the temperature inside the housing increases.
[0034]
The detected temperature voltage VTH, the internally set minimum speed voltage VIN, the externally set minimum speed voltage RMI, and the triangular wave signal (sawtooth voltage) PWM described above are input to the comparator CMP. The comparator CMP is composed of a 4-differential (4-input) comparator. The PWM generation circuit outputs a triangular wave signal PWM as a PWM control signal in order to control the rotation speed of the single-phase motor.
[0035]
With such a configuration, each detected temperature voltage voltage VTH, internally set minimum speed voltage VIN, and externally set voltage are divided by a voltage dividing ratio of each voltage dividing resistor R21a, R22a, R21b, R22b, Rs and resistor R3 from a common power supply VCC. A lowest speed voltage RMI is generated. For this reason, even if the common power supply VCC varies, the output of the comparator CMP is not affected. Therefore, even if the common power supply VCC varies, the comparator CMP can accurately output a control signal for driving the single-phase motor. Further, even if the characteristics of the elements constituting the single-phase motor drive circuit vary, the influence can be prevented as much as possible.
[0036]
As a specific configuration example of the driving duty determination comparator CMP, as shown in the circuit diagram of FIG. 2, a constant current source, four PNP-type bipolar transistors Tr10, Tr20a, Tr20b, Tr30, and one NPN-type bipolar are provided. A transistor Tr40, a bias resistor R10, and a resistor R20 are included. The emitters of the three bipolar transistors Tr10, Tr20a, Tr20b, Tr30 are connected to a constant current source. The collectors of the three bipolar transistors Tr10, Tr20a, Tr20b are grounded. A bias resistor R10 is connected between the base and emitter of the bipolar transistor Tr40, and the connection point between the emitter and the bias resistor R10 is grounded. The collector of the bipolar transistor Tr30 is connected to the base of the bipolar transistor Tr40. A power supply VCC is connected to the collector of the bipolar transistor Tr40 via a resistor R20.
[0037]
In the comparator CMP having such a configuration, the detected temperature voltage VTH is applied to the base of the bipolar transistor Tr10. Further, the internally set minimum speed voltage VIN is applied to the base of the bipolar transistor Tr20a. Further, the externally set lowest speed voltage voltage RMI is applied to the base of the bipolar transistor Tr20b. Note that the lower one of the base voltages of the bipolar transistor Tr20a or the bipolar transistor Tr20b is to be compared with the triangular wave PWM. A triangular wave signal PWM is applied to the base of the bipolar transistor Tr30. Therefore, the output signal of the comparator CMP appears as a drive duty control signal at the collector of the bipolar transistor Tr40.
[0038]
Based on the outputs of the comparator CMP and the comparison circuit 118, the control circuit 132 performs signal processing. As a result, as described above, the control circuit 132 outputs the drive signals A, B, C, and D for complementarily turning on and off the bipolar transistors 102 and 104 and the bipolar transistors 108 and 110.
[0039]
=== Operation of single-phase motor drive circuit ===
A characteristic operation of the single-phase motor drive circuit according to the present embodiment will be described with reference to the circuit diagram of FIG. 2 and the waveform diagram of FIG. First, the control principle of the drive duty will be described with reference to the waveform diagram of FIG. The waveform diagram of FIG. 3 is a conceptual diagram for explaining the operation in an easy-to-understand manner.
[0040]
In the minimum speed setting rotation period T1 in FIG. 3, for example, the drive duty determination comparator CMP is the most at the start of the single-phase motor to be driven so that the single-phase motor rotates at the minimum rotation speed for low temperatures. A control signal with a narrow pulse width is output.
[0041]
That is, in the minimum speed setting rotation period T1 in FIG. 3, the detected temperature voltage VTH gradually decreases as the temperature increases due to the rotation of the single-phase motor, but the internally set minimum speed voltage VIN until the cross point α is reached. And larger than the externally set minimum speed voltage RMI.
[0042]
At this time, as described above, when the voltage dividing resistors R21b and R22b of FIG. 1 are not externally attached and the externally set minimum speed voltage RMI is not set, the drive duty determining comparator CMP is substantially set internally. The minimum speed voltage VIN is compared with the detected temperature voltage VTH. As a result of this comparison, the smaller internal setting minimum speed voltage VIN is set as the duty setting voltage. Then, as shown in the output waveform diagram of the comparator CMP in FIG. 3, the comparator CMP outputs a control signal of “H” only when the triangular wave signal PWM is larger than the duty setting voltage. The waveform of this control signal is represented by a solid line indicated by VIN.
[0043]
On the other hand, when the voltage dividing resistors R21b and R22b shown in FIG. 1 are externally connected and the externally set minimum speed voltage RMI is set, the drive duty determining comparator CMP has the internal set minimum speed voltage VIN and the externally set minimum speed voltage. RMI and detected temperature voltage VTH are compared. As a result of this comparison, the smallest externally set minimum speed voltage RMI is set as the duty set voltage. Then, as shown in the output waveform diagram of the comparator CMP in FIG. 3, the comparator CMP outputs a control signal of “H” only when the triangular wave signal PWM is larger than the duty setting voltage. The waveform of this control signal is represented by a broken line indicated by RMI. The minimum speed setting rotation period T1 during which this control signal is output extends to the cross point β where the externally set minimum speed voltage RMI and the detected temperature voltage VTH intersect.
[0044]
The detected temperature voltage VTH gradually decreases as the temperature increases due to the rotation of the single-phase motor. As a result, the detected temperature voltage VTH passes the cross point α (cross point β when the externally set minimum speed voltage RMI is set) in FIG. 3 and the internally set minimum speed voltage VIN (or the externally set minimum speed). When the voltage becomes lower than the voltage RMI (period T2 in FIG. 3, PWM control variable speed region), the comparator CMP switches the duty setting voltage to the detected temperature voltage VTH. As a result, the drive duty determining comparator CMP outputs a control signal only during a period when the triangular wave signal PWM is larger than the detected temperature voltage VTH. That is, the single-phase motor rotates with a driving duty corresponding to the detected temperature VTH of the thermistor Rs.
[0045]
When the temperature rises due to the rotation of the single-phase motor and the detected temperature VTH of the thermistor Rs becomes high (period T3 in FIG. 3, full speed region), the control signal output by the comparator CMP is fully driven with a duty of 100%.
[0046]
Next, the operation of the circuit element that realizes the drive duty control principle described so far will be described. As shown in FIG. 2, the internal set minimum speed voltage VIN (or externally set minimum speed voltage RMI) is smaller than the detected temperature voltage VTH in the period T1 (or up to the cross point β) in FIG.
[0047]
Therefore, when the externally set minimum speed voltage RMI is set, when the externally set minimum speed voltage RMI is lower than the triangular wave signal PWM, the bipolar transistor Tr20b is turned on while the detected temperature voltage VTH is applied to the base. Both the bipolar transistor Tr10 and the bipolar transistor Tr20a to be maintained maintain an off state. Then, the bipolar transistor Tr30 to which the triangular wave signal PWM is applied to the base is turned off while the triangular wave signal PWM is larger than the externally set lowest speed voltage RMI, while the triangular wave signal PWM is smaller than the externally set lowest speed voltage RMI. Turn on inside. As a result, the bipolar transistor Tr40 in which the output of the comparator CMP appears at the collector outputs a “H” signal during the period in which the triangular wave signal PWM is greater than the externally set minimum speed voltage RMI, while the triangular wave signal PWM is at the externally set minimum speed. An “L” signal is output during a period smaller than the voltage RMI.
[0048]
On the other hand, when the externally set minimum speed voltage RMI is not set, when the internally set minimum speed voltage VIN is lower than the triangular wave signal PWM, the bipolar transistor Tr20a is turned on, while both the bipolar transistor Tr10 and the bipolar transistor Tr20b are turned off. Maintain the state. Then, the bipolar transistor Tr30 to which the triangular wave signal PWM is applied to the base is turned off while the triangular wave signal PWM is larger than the internally set minimum speed voltage VIN, while the triangular wave signal PWM is smaller than the internally set minimum speed voltage VIN. Turn on inside. As a result, the bipolar transistor Tr40 in which the output of the comparator CMP appears at the collector outputs an “H” signal during a period when the triangular wave signal PWM is greater than the internally set minimum speed voltage VIN, while the triangular wave signal PWM is at the internally set minimum speed. An “L” signal is output during a period smaller than the voltage VIN.
[0049]
Then, as shown in periods T2 and T3 in FIG. 3, the detected temperature voltage VTH is based on the internally set minimum speed voltage VIN (or the externally set minimum speed voltage RMI when the externally set minimum speed voltage RMI is set). When it becomes smaller, when the detected temperature voltage VTH is lower than the triangular wave signal PWM, the bipolar transistor Tr10 is turned on, while both the bipolar transistors Tr20a and Tr20b are turned off. Then, the bipolar transistor Tr30 is turned off while the triangular wave signal PWM is larger than the detected temperature voltage VTH, while it is turned on while the triangular wave signal PWM is smaller than the detected temperature voltage VTH. As a result, the bipolar transistor Tr40 in which the output of the comparator CMP appears at the collector outputs an “H” signal during the period when the triangular wave signal PWM is larger than the detected temperature voltage VTH, while the triangular wave signal PWM is smaller than the detected temperature voltage VTH. During this period, an “L” signal is output. Therefore, the comparator CMP outputs a pulse signal corresponding to the detected temperature voltage VTH of the thermistor Rs.
[0050]
As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.
[0051]
For example, if the triangular wave signal supplied from the PWM generation circuit to the comparator CMP is also generated from the common power supply VCC that generates the detected temperature voltage VTH, the internally set minimum speed voltage VIN, and the externally set minimum speed voltage RMI, Even if VCC varies, the rotational speed of the single-phase motor can be stabilized.
[0052]
That is, as shown in FIG. 1, the PWM generation circuit is constituted by a well-known circuit, but the power supply is a common power supply VCC. A connection point between the voltage dividing resistor R0 and the voltage dividing resistor R1 is connected to the inverting input terminal (−) of the comparator CMP1. The voltage dividing resistor R0, the voltage dividing resistor R1, and the voltage dividing resistor R2 are connected in series between the common power supply VCC and the ground. The collector of the transistor Tr1 is connected to the connection point between the voltage dividing resistor R1 and the voltage dividing resistor R2. The emitter of this transistor Tr1 is grounded. A triangular wave signal (PWM signal) output from the comparator CMP1 is applied to the base of the transistor Tr1. On the other hand, the other end of the capacitor C0 whose one end is grounded is connected to the non-inverting input terminal (+) of the comparator CMP1, and is connected to the connection point between the switch SW1 and the switch SW2. These switches SW1 and SW2, and the upper-stage constant current source and the lower-stage constant current source are connected in series between a common power supply VCC and the ground as shown in FIG.
[0053]
In such a configuration, the transistor Tr1 is turned on / off according to the level of the triangular wave signal output from the comparator CMP1. As a result, the reference voltage applied to the inverting input terminal (−) of the comparator CMP1 of the PWM generation circuit is switched to V1 or V2. These reference voltages V1 or V2 are generated by voltage dividing resistors R0, R1, and R2 connected to a common power supply VCC.
[0054]
Therefore, since the triangular wave signal (PWM signal) is generated from the common power supply VCC, the four-input comparator CMP suppresses variations in the control signal for driving the single-phase motor and stably outputs the control signal. be able to.
[0055]
Further, the comparator CMP1 of the PWM generation circuit has hysteresis. Therefore, the comparator CMP1 can output a stable triangular wave signal without being affected by noise or the like. Therefore, the 4-input comparator CMP can further stabilize the control signal for driving the single-phase motor.
[0056]
【The invention's effect】
Both the rotation speed setting voltage and the detected temperature voltage compared by the comparator are generated by a common power source. Therefore, even if the voltage of the power supply varies, the comparator can stably output a control signal for driving the single-phase motor without being affected by the fluctuation. Therefore, it is possible to perform stable variable speed control according to the ambient temperature for the single-phase motor. Further, even if the characteristics of the elements constituting the single-phase motor drive circuit vary, the influence can be prevented as much as possible.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a single-phase motor and a driving device thereof according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing a specific configuration example of a four-input comparator according to an embodiment of the present invention.
FIG. 3 is a waveform diagram showing main signals in a drive circuit for a single-phase motor according to an embodiment of the present invention.
[Explanation of symbols]
106 Single-phase coil
116 Hall element
122 Rotation stop detection circuit
132 Control circuit
200A internal setting minimum speed voltage generation circuit (first rotation speed setting voltage generation circuit)
200B External setting minimum speed voltage generation circuit (second rotation speed setting voltage generation circuit)
300 Detection temperature voltage generation circuit
Comparator for CMP drive duty determination (4-input, 4-differential)
Rs thermistor (voltage dividing resistor)
R3, R21a, R22a, R21b, R22b Voltage dividing resistor
Common power supply for VCC
VTH detection temperature
VIN Internally set minimum speed voltage (first rotation speed setting voltage)
RMI external setting minimum speed voltage (second rotation speed setting voltage)

Claims (5)

The detected temperature voltage that changes based on the temperature detected by the temperature detecting element is compared with the rotation speed setting voltage for setting a predetermined rotation speed of the single-phase motor, and the single-phase motor rotates at a higher rotation speed. As described above, either one of the detected temperature voltage and the rotation speed setting voltage is set as a duty setting voltage, and the single-phase motor is driven based on a comparison result between the sawtooth voltage having a predetermined cycle and the duty setting voltage. A comparator that outputs a control signal of
A detection temperature voltage generation circuit for generating the detection temperature voltage;
A rotation speed setting voltage generation circuit for generating the rotation speed setting voltage , and
The detected temperature voltage generation circuit includes:
Generating the detected temperature voltage that decreases with increasing temperature;
The comparator is
The detected temperature voltage and the rotation speed setting voltage are compared, and the smaller one of the detected temperature voltage and the rotation speed setting voltage is set as the duty setting voltage, and a sawtooth voltage having a predetermined period is greater than the duty setting voltage. Outputting a control signal for driving the single-phase motor in a large period of time,
The rotation speed setting voltage generation circuit includes a first rotation speed setting voltage generation circuit that generates a first rotation speed setting voltage, and a second rotation speed setting voltage generation circuit that generates a second rotation speed setting voltage. Further comprising
The first rotation speed setting voltage is a fixed setting voltage set in advance,
The second rotation speed setting voltage is a setting voltage that can be changed as appropriate,
When the second rotation speed setting voltage is smaller than the first rotation speed setting voltage, the second rotation speed setting voltage is used as the rotation speed setting voltage.   The detected temperature voltage generation circuit, the first rotation speed setting voltage generation circuit, and the second rotation speed setting voltage generation circuit each have a voltage dividing resistor,
  The detected temperature voltage, the first rotation speed setting voltage, and the second rotation speed setting voltage are divided voltage values respectively generated by a voltage dividing resistor from a common power source. 1. A drive circuit for a single-phase motor according to 1.   3. The circuit according to claim 1, further comprising: a circuit that generates the sawtooth voltage; and a control circuit that generates a drive signal based on the control signal and outputs the drive signal to the single-phase motor. Single-phase motor drive circuit.   The single-phase motor drive circuit according to claim 2, wherein the sawtooth voltage is input to the comparator, and the sawtooth voltage is generated from the common power source.   The detected temperature voltage that decreases as the temperature detected by the temperature detecting element decreases and the rotation speed setting voltage for setting a predetermined rotation speed of the single-phase motor are compared, and the detected temperature voltage and the rotation speed setting are compared. A smaller one of the voltages is set as a duty setting voltage, and a control signal for driving the single-phase motor is output in a period in which a sawtooth voltage having a predetermined period is larger than the duty setting voltage,
  The first rotation speed setting voltage is a preset fixed setting voltage, and the second rotation speed setting voltage is a setting voltage that can be changed as appropriate.
  When the second rotation speed setting voltage is smaller than the first rotation speed setting voltage, the second rotation speed setting voltage is used as the rotation speed setting voltage. Driving method.

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