JP2008306838A - Brushless DC motor driving device and ventilation blower equipped with the same - Google Patents

Abstract

In a brushless DC motor driving device used in a ventilation blower equipped with a sirocco fan, an excessive amount of air flow is suppressed against static pressure fluctuations such as pressure loss, and a desired air volume is efficiently obtained with low noise. It is an object of the present invention to provide a low-cost brushless DC motor driving device that can easily change characteristics and a ventilation blower equipped with the brushless DC motor driving device.
A brushless DC motor 2 converts a current flowing through a drive coil 7 into an analog value by a peak hold circuit 11 and inputs the analog value to a voltage indicating means 12 to drive by adding a predetermined amplification factor and an offset value. Since an instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the control means 9 is generated, the desired air volume is efficiently controlled with low noise by suppressing excessive air volume against static pressure fluctuations such as pressure loss. Can be obtained.
[Selection] Figure 2

Description

  The present invention relates to a brushless DC motor driving device for driving a fan such as a blower, a humidifier, a dehumidifier, a refrigerating device, an air conditioner, etc. is there.

  In recent years, there has been a strong demand for low-price, high-efficiency, and low-noise performance in fan-driven motors mounted on electrical equipment such as ventilators, and it is difficult to achieve significant increases in efficiency with induction motors. The number of brushless DC motors using permanent magnets is increasing. In addition, since a brushless DC motor is mounted, there are an increasing number of devices that variably control the air volume of a ventilation device or the like.

  Conventionally, this kind of brushless DC motor driving device has a configuration disclosed in Patent Document 1.

  Hereinafter, the brushless DC motor driving device will be described with reference to FIG.

As shown in the figure, a rectifying unit 101 that rectifies a commercial AC power source, two-phase drive coils 102 and 103 of a DC motor, and a smoothing capacitor 105 is arranged between the control unit 104 and the rectifying unit 101, and the motor The rectifying unit includes switching elements 106 and 107 that allow current to flow through the driving coils 102 and 103 only in one direction, and a control unit 104 that controls the energization of the motor driving coils 102 and 103 including the switching elements 106 and 107. A two-phase circuit in which the high-voltage DC power rectified by 101 and smoothed by the smoothing capacitor 105 is directly supplied to the motor drive coils 102 and 103, and the rectified and smoothed high-voltage DC power is stepped down and supplied to the control unit 104. The configuration is a half-wave drive system.
JP 2000-41395 A

  According to the ventilating blower equipped with such a conventional electric motor, when installed in a centrifugal ventilation fan such as a sirocco fan, the air flow of the device changes due to the pressure loss, and if the pressure loss becomes small, the air flow becomes excessive and the power consumption There are problems such as increasing noise and giving the user a feeling of cold wind (cold draft), and it is possible to obtain the desired air volume efficiently with low noise by suppressing excessive air volume against static pressure fluctuations such as pressure loss. Is required. Also, in order to obtain the output characteristics of the motor according to the equipment to be installed, change the winding specifications of the motor and the characteristics of the magnet of the rotor, change the parts of the control unit, or another control circuit or setting Generally, there is a method to change the characteristics of the motor according to the instruction signal output from the control circuit or setting means. However, since the change is not easy, the number of models cannot be increased and standardization is not possible. There is a problem that it cannot be done, and it is required to improve these.

  The present invention solves such a conventional problem, suppresses excessive air flow against static pressure fluctuations such as pressure loss, and can obtain a desired air flow efficiently with low noise. An object of the present invention is to provide a low-cost brushless DC motor driving device that can be easily changed and a ventilation blower equipped with the brushless DC motor driving device.

  In addition, most ventilation fans are installed in places that cannot be easily touched by the user (for example, the ceiling), and the motor breaks down and locks when there is an abnormality due to foreign matter or aging. There were problems such as heat generation, and the health of the user, which was difficult for the user to recognize and left the contaminated air unvented.

  The present invention solves such a conventional problem, and is equipped with a brushless DC motor driving device that can ensure safety even if the motor fails or locks after installation and can notify the user of the abnormality. The object is to provide a ventilation fan.

  In addition, the space where the ventilation blower is installed has been reduced in space year by year, and miniaturization of equipment and space saving are required. Furthermore, it is often installed in a sanitary zone, and safety against dust and humidity is also required.

  The present invention solves such a conventional problem, and a brushless DC motor in which an outer shell and constituent elements are integrated with a mold resin which also serves as an insulation to improve heat dissipation, and is small, low cost and high in safety. An object is to provide a drive device and a ventilation blower equipped with the drive device.

  In order to achieve the above object, a brushless DC motor driving apparatus according to the present invention includes a magnetic pole position detecting means for detecting a magnetic pole position of a magnet rotor of a brushless DC motor, an inverter circuit bridge-connected with a plurality of switching elements, and an AC Voltage conversion means for rectifying and smoothing the power supply to a DC power supply, and the voltage generated by the voltage conversion means based on the signal from the magnetic pole position detection means to the brushless DC motor via the inverter circuit in a predetermined direction and order. Drive control means for sequentially energizing PWM, a current detection circuit for converting a current value flowing through the brushless DC motor through the inverter circuit into a current value proportional voltage signal, and a peak value of the voltage signal output from the current detection circuit The peak hold circuit to hold, and the value depending on the value peak-held by the peak hold circuit Voltage instruction means for outputting an instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means is provided, and the voltage instruction means converts the signal of the peak hold circuit at a predetermined amplification factor. Then, the brushless DC motor driving device is characterized in that it generates an instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means.

  By this means, the ON duty value or the OFF duty value of the PWM energization signal is controlled according to the output of the brushless DC motor, that is, the current value. A desired air volume can be obtained efficiently with noise.

  In another means, the voltage instruction means converts the signal of the peak hold circuit into a predetermined gain and offset, and controls the ON duty value or the OFF duty value of the PWM energization signal of the drive control means. 2. The brushless DC motor driving apparatus according to claim 1, wherein the instruction signal is generated.

  By this means, the ON duty value or the OFF duty value of the PWM energization signal is controlled according to the output of the brushless DC motor, that is, the current value. A desired air volume can be obtained efficiently with noise.

  The other means is the brushless DC motor driving apparatus according to claim 2, characterized in that the voltage instruction means comprises an adjusting means for varying the amplification factor and the offset.

  By this means, the ON duty value or OFF duty value of the PWM energization signal can be controlled and arbitrarily adjusted according to the output of the brushless DC motor, that is, the current value, so that the characteristics can be easily changed, and the pressure loss can be reduced at low cost. It is possible to obtain a desired air volume efficiently with low noise by suppressing excessive air volume against static pressure fluctuations.

  The other means is the brushless DC motor driving apparatus according to claim 3, wherein the adjusting means is a resistor such as a variable resistor.

  By this means, the ON duty value or OFF duty value of the PWM energization signal is controlled according to the output of the brushless DC motor, that is, the current value, and can be arbitrarily adjusted by the resistance, so that the characteristics can be easily changed, at low cost, It is possible to obtain a desired air volume efficiently with low noise by suppressing an excessive air volume against a static pressure fluctuation such as pressure loss.

  Another means is that the voltage instruction means controls the ON duty value or the OFF duty value of the PWM energization signal of the drive control means when the signal of the peak hold circuit exceeds a predetermined value. 5. The brushless DC motor driving apparatus according to claim 1, wherein the signal is limited.

  By this means, when the output of the brushless DC motor, that is, the current value exceeds a predetermined value, the ON duty of the PWM energization signal is limited to limit the output of the DC motor. However, safety can be ensured.

  Another means is that the voltage instruction means controls the ON duty value or the OFF duty value of the PWM energization signal of the drive control means when the signal of the peak hold circuit exceeds a predetermined value. The brushless DC motor driving device according to any one of claims 1 to 5, wherein a signal is set to zero and the brushless DC motor is stopped.

  By this means, when the output of the brushless DC motor, that is, the current value exceeds a predetermined value, the ON duty of the PWM energization signal is set to zero to stop the DC motor and output an abnormal signal. Even if it breaks down or locks, safety can be ensured.

  Another means is that the voltage instruction means controls the ON duty value or the OFF duty value of the PWM energization signal of the drive control means when the signal of the peak hold circuit exceeds a predetermined value. 7. The brushless DC motor driving apparatus according to claim 6, wherein a signal is set to zero, the brushless DC motor is stopped, and an abnormal signal is output.

  By this means, when the output of the brushless DC motor, that is, the current value exceeds a predetermined value, the ON duty of the PWM energization signal is set to zero to stop the DC motor and output an abnormal signal. Even if the device breaks down or locks, safety can be ensured and the user can be notified of the abnormality.

  Further, the other means outputs the PWM energization signal of the drive control means so that the current flowing through the brushless DC motor has a substantially sine wave shape. This is a DC motor driving device.

  By this means, the characteristics can be easily changed, and the desired air volume can be obtained efficiently with low noise by suppressing the excessive air volume against static pressure fluctuations such as pressure loss at low cost. Even if it breaks down or locks, safety can be ensured and the user can be notified of the abnormality.

  The other means includes at least the magnetic pole position detecting means and the inverter circuit of a brushless DC motor driving device built in the brushless DC motor. This is a brushless DC motor driving device.

  By this means, the outer shell and the components are integrated, so that the size and cost can be reduced.

  The other means is the brushless DC motor driving device according to claim 9, wherein the brushless DC motor driving device is integrated with the brushless DC motor with a mold resin also serving as insulation. .

  By this means, since the outer shell and the constituent elements are integrated with a mold resin that also serves as an insulation, heat dissipation of power components such as an inverter circuit can be improved, and safety can be improved in a small size and at low cost.

  Another means is a ventilation blower including a brushless DC motor driving device, a brushless DC motor, a fan, and a casing.

  By this means, the characteristics can be easily changed, and the desired air volume can be obtained efficiently with low noise by suppressing the excessive air volume against static pressure fluctuations such as pressure loss at low cost. Even if it breaks down or locks, safety can be ensured, a user can be notified of an abnormality, and a ventilation blower equipped with a brushless DC motor drive device that is small, low cost, and high in safety can be obtained.

  Another means is that the ventilation fan is a ventilation fan provided with a centrifugal fan.

  By this means, the characteristics can be easily changed, and the desired air volume can be obtained efficiently with low noise by suppressing the excessive air volume against static pressure fluctuations such as pressure loss at low cost. Even if it breaks down or locks, safety can be ensured, a user can be notified of an abnormality, and a ventilation blower equipped with a brushless DC motor drive device that is small, low cost, and high in safety can be obtained.

  According to the present invention, a low-cost brushless DC motor that can suppress the excessive air volume against static pressure fluctuations such as pressure loss, can efficiently obtain a desired air volume with low noise, and can easily change characteristics. A drive device and a ventilation blower equipped with the drive device can be provided.

  In addition, it is possible to provide a brushless DC motor driving device that can ensure safety even if the electric motor fails or locks after installation and can notify the user of an abnormality, and a ventilation blower equipped with the brushless DC motor driving device.

  Further, it is possible to provide a brushless DC motor driving device with improved heat dissipation, small size, low cost and increased safety, and a ventilation blower equipped with the brushless DC motor driving device.

  According to a first aspect of the present invention, a magnetic pole position detecting means for detecting a magnetic pole position of a magnet rotor of a brushless DC motor, an inverter circuit bridge-connected by a plurality of switching elements, and an AC power supply rectified to a DC power supply Voltage conversion means for smoothing, and drive control for sequentially energizing the brushless DC motor in a predetermined direction and order via the inverter circuit with the voltage generated by the voltage conversion means based on the signal of the magnetic pole position detection means Means, a current detection circuit for converting a current value flowing through the brushless DC motor through the inverter circuit into a current value proportional voltage signal, and a peak hold circuit for holding a peak value of the voltage signal output from the current detection circuit; , O of the PWM energization signal of the drive control means according to the value peak-held by the peak hold circuit Voltage indicating means for outputting an instruction signal for controlling the duty value or the OFF duty value is provided, the voltage indicating means converts the signal of the peak hold circuit into a signal with a predetermined amplification factor, and PWM energization of the drive control means The brushless DC motor driving device is characterized by generating an instruction signal for controlling the ON duty value or the OFF duty value of the signal. The PWM energization signal is turned on according to the output of the brushless DC motor, that is, the current value. Since the duty value or the OFF duty value is controlled, it has an effect that the desired air volume can be obtained efficiently with low noise by suppressing excessive air volume against static pressure fluctuations such as pressure loss.

  The voltage instruction means converts the signal of the peak hold circuit into a predetermined amplification factor and offset, and generates an instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means. The brushless DC motor driving device according to claim 1, wherein the ON duty value or the OFF duty value of the PWM energization signal is controlled according to the output of the brushless DC motor, that is, the current value. It has the effect of suppressing the excessive air volume against static pressure fluctuations such as pressure loss and obtaining a desired air volume efficiently with low noise.

  3. The brushless DC motor driving apparatus according to claim 2, wherein the voltage indicating means includes an adjusting means for changing an amplification factor and an offset. Since the ON duty value or OFF duty value of the PWM energization signal can be controlled and adjusted arbitrarily according to the characteristics, the characteristics can be easily changed, and the excessive air flow is suppressed at low cost against static pressure fluctuations such as pressure loss. Thus, the desired air volume can be obtained efficiently with low noise.

  4. The brushless DC motor driving apparatus according to claim 3, wherein the adjusting means is a resistor such as a variable resistor, and PWM energization is performed according to an output of the brushless DC motor, that is, a current value. Since the ON duty value or OFF duty value of the signal can be controlled and adjusted arbitrarily, the characteristics can be easily changed, and at low cost, excessive air flow is suppressed against static pressure fluctuations such as pressure loss, and low noise is achieved. It has the effect that a desired air volume can be obtained efficiently.

  The voltage instruction means limits the instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means when the signal of the peak hold circuit exceeds a predetermined value. 5. A brushless DC motor driving device according to claim 1, wherein when the output of the brushless DC motor, that is, the current value exceeds a predetermined value, a PWM energization signal is provided. Since the output of the DC motor is limited by limiting the ON duty of the motor, it has the effect that safety can be ensured even if the motor fails after installation.

  Further, the voltage instruction means sets the instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means to zero when the signal of the peak hold circuit exceeds a predetermined value. 6. The brushless DC motor driving device according to claim 1, wherein the brushless DC motor is stopped, and the output of the brushless DC motor, that is, the current value is predetermined. If the value exceeds the value, the ON duty of the PWM energization signal is set to zero and the DC motor is stopped and an abnormal signal is output. Therefore, safety can be ensured even if the motor fails or locks after installation. .

  Further, the voltage instruction means sets the instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means to zero when the signal of the peak hold circuit exceeds a predetermined value. 7. The brushless DC motor driving device according to claim 6, wherein the brushless DC motor is stopped and an abnormal signal is output, and safety is ensured even if the electric motor fails or locks after installation. It has the effect of being able to.

  8. The brushless DC motor driving apparatus according to claim 1, wherein the PWM energization signal of the drive control means is output so that a current flowing through the brushless DC motor is substantially sinusoidal. By outputting so that the current flowing through the brushless DC motor is substantially sinusoidal, it can be driven silently.

  9. The brushless DC motor drive according to claim 1, wherein at least the magnetic pole position detecting means and the inverter circuit of the brushless DC motor driving device are built in the brushless DC motor. This is a device, and the outer shell and components are integrated with a mold resin that also serves as an insulation. Therefore, the heat dissipation of power components such as inverter circuits can be improved, and the safety can be improved at a small size and low cost. Have

  10. The brushless DC motor driving device according to claim 9, wherein the brushless DC motor driving device is integrated with the brushless DC motor with a molding resin that also serves as an insulation, and is also incorporated. By integrating and integrating the brushless DC motor with the mold resin, both insulation and heat dissipation can be achieved and downsizing can be achieved.

  The brushless DC motor driving device according to any one of claims 1 to 10, a brushless DC motor, a fan, and a casing are provided, the fan is provided in the casing, and the motor is driven by the brushless DC motor driving device. The fan is operated to drive the fan to ventilate or ventilate the ventilation fan, and can ventilate or blow air efficiently.

  In addition, the fan is a centrifugal fan, and is a ventilating air blower according to claim 11, which can efficiently ventilate or blow air.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is an external view of the structure of a ventilation fan using the brushless DC motor of the present invention.

  1A is a side view of the structural external view of the ventilation blower, FIG. 1B is a bottom view of the structural external view of the ventilation blower, and FIG. 1C is a structural external view of the ventilation blower. FIG.

  The brushless DC motor 2 is attached to the casing 1 and the blower fan 3 is attached to the rotating shaft of the brushless DC motor 2. The ventilation blower is attached to the ceiling, and the drive device is connected to the brushless DC motor 2. The ventilation fan 3 is rotated to intake or exhaust indoor air to ventilate the room.

  FIG. 2 is a diagram illustrating an example of an electric circuit of the brushless DC motor driving device of the present invention. The magnet rotor 4 of the brushless DC motor 2 is a rotor in which a plurality of pairs of N poles and S poles are arranged, and the magnetic flux density of each pole is magnetized in a sine wave shape. The magnetic pole position detection means 5 is a Hall IC that converts the change of the magnet rotor 4 from the N pole to the S pole or from the S pole to the N pole into an electrical H or L signal. A power switching element constituting the inverter circuit 6 is bridge-connected by a transistor, a MOSFET (Metal Oxide Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), or the like, and is connected to the stator driving coil 7 of the brushless DC motor 2. ing.

  The voltage conversion means 8 is composed of a diode bridge for full-wave or half-wave rectification of the AC power supply and a capacitor for smoothing the rectified pulsating voltage and a converter for generating the power supply voltage of the drive control means 9. ing. The drive control means 9 is a general-purpose monolithic IC, microcomputer, PLD (programmable logic device) or DSP (digital signal processor), and a sinusoidal drive coil 7 is applied to the drive coil 7 between the two phases according to the output signal of the magnetic pole position detection means 5. A two-phase modulation method that generates and outputs a PWM energization signal that is an average voltage is employed.

  By generating and outputting a PWM energization signal having a substantially sinusoidal average voltage, the current flowing through the brushless DC motor becomes substantially sinusoidal. The current detection circuit 10 converts a current flowing through the drive coil 7 through the inverter circuit 6 into a voltage with a low resistance.

  The peak hold circuit 11 is a well-known circuit composed of a capacitor, an operational amplifier, etc., and holds the peak level of the PWM pulse voltage of the current detection circuit 10 and converts the pulse voltage into an analog value. FIG. 3 shows an example of the voltage instruction means 12, which is composed of a well-known circuit composed of an operational amplifier or the like, a combination of an in-phase amplifier circuit 13 and an adder circuit 14. ) And converted and output to the drive control means 9. Here, the adjusting means for determining the amplification factor and the voltage (offset) to be added is composed of variable resistors 15 and 16. The limit circuit 17 is an element such as a Zener diode that limits a signal output from the peak hold circuit 11 to a predetermined value or more, and the abnormality detection circuit 18 is configured by a switch element such as a comparator or a transistor. When the signal output from the hold circuit 11 exceeds a predetermined value, that is, the threshold value, the output of the voltage indicating means 12 is set to zero and an abnormal signal is output.

  In the above configuration, the drive control means 9 controls the brushless DC motor 2 to flow through the drive coil 7 in a predetermined order via the inverter circuit 6 based on the signal from the magnetic pole position detection means 5. For example, if the current is 120 degrees, the three Hall ICs are Hu, Hv, Hw, the phases of the drive coil 7 are U, V, W, and (Hu, Hv, Hw) = (H, H, L). When (U, V, W) = (OFF, L, H), (Hu, Hv, Hw) = (L, H, L), (U, V, W) = (H, L, OFF) ), (Hu, Hv, Hw) = (L, H, H), the power of the inverter circuit 6 in a predetermined direction and place as in (U, V, W) = (H, OFF, L) Turn the switching element ON / OFF. Here, for example, the H signal of the drive coil 7 is PWM energization. The current flowing through the drive coil 7 is input to the current detection circuit 10 via the inverter circuit 6, converted into a voltage corresponding to the current value, and input to the peak hold circuit 11.

  The peak hold circuit 11 holds the peak level of the PWM pulse voltage, for example, about 0.5 V, converts it to an analog value, and inputs it to the voltage instruction means 12. The signal input to the voltage instruction means 12 is converted into a predetermined amplification factor, for example, four times by the in-phase amplifier circuit 13, and a predetermined offset value, for example, 1V is added by the adder circuit 14 to drive control means. An instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal 9 is generated. For example, if the instruction signal is 3V and the duty is 5% and 100% duty, the ON duty is 60%.

  4 shows the relationship between the current detection circuit 10, the peak hold circuit 11 and the voltage indicating means 12, and FIG. 5 shows the relationship between the signal of the voltage indicating means 12 and the PWM energization signal of the drive control means 9. is there. In the case of the two-phase modulation method, the ON duty value or the OFF duty value of the PWM energization signal is determined by the modulation rate of the modulation wave, and therefore shows the relationship between the signal of the voltage indicating means 12 and the modulation rate. Here, for example, if the output of the voltage indicating means 12 that maximizes the modulation wave is 5V, the modulation rate is 100% at 5V.

  The brushless DC motor driving apparatus configured as described above controls the ON duty value or the OFF duty value of the PWM energization signal in accordance with the output of the brushless DC motor 2, that is, the current value. On the other hand, it is possible to suppress the excessive air volume and to obtain a desired air volume efficiently with low noise.

  FIG. 6 is a structural diagram of the brushless DC motor 2. Since the variable resistors 15 and 16 of the adjusting means are exposed, the amplification factor and the offset value can be changed. For example, if the resistance value of the variable resistor 15 is increased, the amplification factor is increased. Since the male set value can be changed by changing the resistance ratio, the characteristics of the brushless DC motor 2 can be easily changed.

  In addition, the magnetic pole position detection means 5 and the inverter circuit 6 are integrated with the brushless DC motor 2 by a mold resin 19 that also serves as an insulation, so that the heat dissipation of the power components can be improved, and it is small, low cost and safe. Can increase the sex. Examples of the mold resin 19 include thermoplastic resins such as unsaturated polyester.

  FIG. 7 shows the relationship between the signals of the current detection circuit 10, the peak hold circuit 11, and the voltage instruction means 12 (the limit circuit 17 and the abnormality detection circuit 18).

  The brushless DC motor driving apparatus configured as described above has an ON duty value or an OFF duty value of the PWM energization signal generated according to the output of the brushless DC motor 2, that is, the current value, for example, a predetermined value 1, for example, Limiting at 0.5V, setting the output of the voltage indicating means 12 to zero at a correction value of 2, for example 0.8V, stopping the PWM energization signal and outputting an abnormal signal, so it is safe even if the motor fails or locks after installation Sex can be secured.

  In the present embodiment, the voltage instruction means is constituted by a circuit, but it may be included in the drive control means as a microcomputer, and there is no difference in its operation and effect.

  Further, although the adjusting means has been described with a variable resistor, it may be configured with a printing resistor capable of laser trimming, and there is no difference in its operational effect.

  Moreover, although the abnormality detection circuit is configured to output a signal, it may be an LED or a buzzer, and there is no difference in the operation effect.

  The brushless DC motor driving device of the present invention is a ventilation air blower equipped with a brushless DC motor that can easily change the characteristics, can obtain a desired air volume efficiently with low noise, and is small, low cost, and high in safety. Since it can be provided, it can be applied to other household electric appliances such as refrigerators, dehumidifiers, and air conditioners.

FIG. 1 is a structural external view of a ventilation blower using the brushless DC motor according to the first embodiment of the present invention ((a) a side view of the structural external view of the ventilation blower, and (b) a structural external view of the ventilation blower). Bottom view, (c) Same as above, Front view of structural external view of ventilation blower) The figure which shows an example of the electric circuit of a brushless DC motor drive device The figure which shows an example of the voltage instruction | indication means of a brushless DC motor drive device The figure for demonstrating the relationship between the electric current detection circuit of a brushless DC motor drive device, a peak hold circuit, and a voltage instruction | indication means. The figure for demonstrating the relationship between the signal of the voltage instruction | indication means of a brushless DC motor drive device, and the PWM energization signal of a drive control means. Structure of brushless DC motor The figure for demonstrating the relationship of the signal of a current detection circuit, a peak hold circuit, and a voltage instruction | indication means similarly. The figure which shows the electric circuit of the conventional brushless DC motor drive device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Brushless DC motor 3 Blower fan 4 Magnet rotor 5 Magnetic pole position detection means 6 Inverter circuit 7 Drive coil 8 Voltage conversion means 9 Drive control means 10 Current detection circuit 11 Peak hold circuit 12 Voltage instruction means 13 In-phase amplification circuit 14 Addition Circuit 15 Variable resistor 16 Variable resistor 17 Limit circuit 18 Abnormality detection circuit 19 Mold resin

Claims (12)

Magnetic pole position detecting means for detecting the magnetic pole position of the magnet rotor of the brushless DC motor, inverter circuit bridge-connected by a plurality of switching elements, voltage converting means for rectifying and smoothing AC power to DC power, and magnetic pole position detection Drive control means for sequentially energizing the brushless DC motor with a voltage generated by the voltage conversion means on the basis of the signal of the means in a predetermined direction and order via the inverter circuit, and brushless DC via the inverter circuit. A current detection circuit that converts a current value flowing through the motor into a current value proportional voltage signal, a peak hold circuit that holds a peak value of the voltage signal output from the current detection circuit, and a value that is peak-held by the peak hold circuit Depending on the ON duty value or OFF duty of the PWM energization signal of the drive control means. Voltage instruction means for outputting an instruction signal for controlling the tee value, the voltage instruction means converting the signal of the peak hold circuit into a signal with a predetermined amplification factor, and the duty ratio of the PWM energization signal of the drive control means A brushless DC motor driving device that generates an instruction signal for controlling a value or an OFF duty value. The voltage instruction means converts the signal of the peak hold circuit with a predetermined amplification factor and offset, and generates an instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means. The brushless DC motor driving device according to claim 1. 3. The brushless DC motor driving apparatus according to claim 2, wherein the voltage instruction means includes adjustment means for changing an amplification factor and an offset. 4. The brushless DC motor driving apparatus according to claim 3, wherein the adjusting means is a resistor such as a variable resistor. The voltage instruction means limits the instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means when the signal of the peak hold circuit exceeds a predetermined value. The brushless DC motor drive device according to any one of claims 1 to 4. When the signal of the peak hold circuit exceeds a predetermined value, the voltage instruction means sets the instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means to zero, and The brushless DC motor driving device according to any one of claims 1 to 5, wherein the brushless DC motor is stopped. When the signal of the peak hold circuit exceeds a predetermined value, the voltage instruction means sets the instruction signal for controlling the ON duty value or the OFF duty value of the PWM energization signal of the drive control means to zero, and 7. The brushless DC motor driving apparatus according to claim 6, wherein the brushless DC motor is stopped and an abnormal signal is output. The brushless DC motor driving apparatus according to any one of claims 1 to 7, wherein the PWM energization signal of the drive control means is output so that a current flowing through the brushless DC motor is substantially sinusoidal. 9. The brushless DC motor driving apparatus according to claim 1, wherein at least the magnetic pole position detecting means and the inverter circuit of the brushless DC motor driving apparatus are built in the brushless DC motor. 10. The brushless DC motor driving apparatus according to claim 9, wherein the brushless DC motor driving apparatus is integrated with the brushless DC motor by using a mold resin that also serves as an insulation. A brushless DC motor driving device according to any one of claims 1 to 10, a brushless DC motor, a fan, and a casing, the fan being provided in the casing, the motor being driven by the brushless DC motor driving device, A ventilation blower that ventilates or blows air by operating the fan by driving a motor. The ventilation fan according to claim 11, wherein the fan is a centrifugal fan.

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