JP2013062957A - Power-supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-supply device that allows achieving a further reduction in size and cost of a capacitor by further reducing capacitance of the capacitor.SOLUTION: A power-supply device 1 includes: a DC power-supply section that has a rectifier circuit 12 and a smoothing capacitor 13, generates DC power from AC power supplied from an AC power supply 40, and supplies the DC power to a fan motor 20; voltage detection means 14 that detects a DC voltage applied to the fan motor 20; control means 11 that takes in the DC voltage detected by the voltage detection means 14 and performs driving control of the fan motor 20; a switching power supply 15 that is connected in parallel to an output side of the rectifier circuit 12 and supplies DC power to the control means 11 and an external load 30; and open and close means 16 that starts or stops the supply of driving power from the switching power supply 15 to the external load 30 by being opened and closed by the control means 11.

Description

  The present invention relates to a power supply device, and more particularly, to a power supply device that supplies power to a motor.

  Conventionally, in a power supply device that is mounted on various electric devices and supplies driving power to various devices such as motors and display means provided in the electric devices and control means that controls the operation of the electric devices, an AC power source such as a commercial power source is used. Various measures have been proposed in preparation for the occurrence of an instantaneous power supply interruption (hereinafter referred to as an instantaneous interruption).

  For example, Patent Document 1 is a power supply device that supplies driving power to a DC brushless motor provided in an electrical device, detects a DC voltage for driving a DC brushless motor, and the detected DC voltage is a predetermined value (hereinafter, referred to as a DC brushless motor). It has been proposed that it is determined that a momentary interruption has occurred when the voltage is equal to or less than a predetermined voltage, and the power supply to various devices other than the control means is stopped. In this power supply apparatus, by suppressing the decrease in the charging voltage of the capacitor provided in the power supply apparatus as much as possible, the direct current voltage supplied to the control means is reduced due to a momentary interruption, thereby delaying the resetting of the control means as much as possible. Yes.

JP 2006-296154 A (pages 4-5, FIG. 1)

  In the instantaneous interruption detection method in the power supply device described in Patent Document 1, the instantaneous interruption can be detected earlier as the predetermined voltage for detecting the instantaneous interruption is closer to the DC voltage for driving the DC brushless motor. If the instantaneous interruption can be detected quickly, the power supply to various devices can be cut off quickly, so that the power consumption of various devices can be reduced early after the occurrence of the instantaneous interruption, and the decrease in the charging voltage of the capacitor is delayed. be able to. As a result, the capacitance of the capacitor can be reduced, and the size and cost of the capacitor can be reduced.

  On the other hand, a ripple voltage corresponding to the rotational speed of the DC brushless motor is superimposed on the detected DC voltage for driving the DC brushless motor. The amplitude of the ripple voltage varies according to the rotational speed of the DC brushless motor. Generally, the higher the rotational speed of the DC brushless motor, the larger the amplitude of the ripple voltage.

  From the above points, when detecting a momentary interruption of the AC power supply, the predetermined voltage is the ripple voltage at the maximum rotation speed of the DC brushless motor so that the lower limit value of the ripple voltage is detected and it is not erroneously determined as a momentary interruption. In consideration of the amplitude, it is necessary to make the value lower than the lower limit value of the ripple voltage at this time, and there is a limit in reducing the capacitance of the capacitor due to this. That is, there is a problem that it is difficult to further reduce the size and cost of the capacitor.

  An object of the present invention is to solve the above-described problems and to provide a power supply device that can further reduce the size and cost of the capacitor by further reducing the capacitance of the capacitor.

  The present invention solves the above-described problem, and a power supply apparatus according to the present invention includes a rectifier circuit and a capacitor, converts a DC power supplied from an AC power source into a DC power, and supplies the DC power to an electric motor. And a voltage detection means for detecting the DC voltage across the capacitor, and a control means for controlling the rotation of the motor, the control means storing in advance a predetermined voltage corresponding to the rotation speed of the motor If the DC voltage taken in from the voltage detection means is equal to or lower than a predetermined voltage corresponding to the number of rotations of the motor, it is determined that the power supply from the AC power source is cut off. The power supply device includes a power supply unit connected in parallel to the output side of the rectifier circuit and supplying DC power to the control unit and the external load, and open / close controlled by the control unit, so that the power supply unit is connected to the external load. And an opening / closing means for supplying or stopping the supply of DC power, and when the control means determines that the power supply from the AC power supply has been cut off, the opening / closing means is opened to supply the DC power from the power supply unit to the external load. Is to stop.

  The power supply device of the present invention includes a plurality of predetermined voltages when determining the interruption of the power supply from the AC power supply. In the electric motor, a regenerative current corresponding to the number of revolutions is generated, and the regenerative current generated increases as the number of revolutions increases. In the present invention, focusing on the fact that the capacitor is charged by the regenerative current generated by the electric motor, a predetermined voltage that is a threshold for detecting a power failure is determined according to the number of revolutions. If the DC voltage taken in from the voltage detection means is equal to or lower than a predetermined voltage determined for each number of rotations of the motor, the control means determines that a momentary interruption has occurred in the AC power supply and transfers the power supply unit to the external load. Since the supply of DC power is stopped, the resetting of the control means due to the drop in the DC voltage supplied to the control means can be delayed as much as possible and the capacitance of the capacitor can be reduced.

It is a block diagram explaining the electrical structure of the power supply device which is an Example of this invention. It is a figure explaining the predetermined voltage of the instantaneous interruption detection in the Example of this invention, (A) is the case where the rotation speed of a fan motor is low, (B) When the rotation speed of a fan motor is high, (C) is a fan It shows the difference depending on the motor speed. It is a power failure judgment voltage table memorize | stored in the control means in the Example of this invention. It is a flowchart explaining the process in the control means which concerns on the Example of this invention.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an embodiment, a power supply device provided in a deodorizer, which is a power supply device that supplies power to a plurality of electric devices such as a fan motor that rotates a blower fan of a deodorizer, an ion generation device, an ultraviolet irradiation device, etc. An example will be described.
The present invention is not limited to the following embodiments, and various modifications can be made without departing from the spirit of the present invention.

  As shown in FIG. 1, a power supply device 1 of the present invention includes a rectifier circuit 12, a capacitor 13, a voltage detection means 14, a switching power supply 15 as power supply means, a switch 16 as opening and closing means, and control means. 11.

  The rectifier circuit 12 has an AC power supply 40 connected to the input end and a drive circuit 21 connected to the output end. The rectifier circuit 12 is a circuit that rectifies an AC voltage supplied from the AC power supply 40 to obtain a pulsating voltage, and is mainly composed of a bridge diode. The drive circuit 21 is a circuit that drives a fan motor 20 (for example, a direct current brushless motor with a blower fan (not shown) attached to the output shaft) according to an instruction from the control unit 11. .

  The capacitor 13 is connected in parallel to the output end of the rectifier circuit 12 and the input end of the drive circuit 21 by connecting both ends to two connection lines connecting the rectifier circuit 12 and the drive circuit 21. The capacitor 13 smoothes the pulsating voltage rectified by the rectifier circuit 12.

  The voltage detection means 14 is formed by, for example, two or more resistance elements connected in series, and both ends are connected to two connection lines that connect the rectifier circuit 12 and the drive circuit 21, whereby a rectifier circuit is formed. 12 are connected in parallel to the output terminals of the drive circuit 21 and the input terminal of the drive circuit 21. The voltage detection means 14 divides the DC voltage across the capacitor 13 with a resistance element and outputs the divided value to the control means 11.

  The switching power supply 15 is connected in parallel to the rectifier circuit 12 by connecting both ends of the switching power supply 15 to two connection lines that connect the AC power supply 40 and the input terminal of the rectifier circuit 12. A load 30 that is an external load is connected to the output terminal of the switching power supply 15 via the control means 11 and the switch 16. The switching power supply 15 includes a switching element such as a MOS-FET, a transformer, a diode, and the like, and its operation is controlled by the control means 11. The switching power supply 15 receives an AC voltage from the AC power supply 40, converts it into a predetermined DC voltage, and supplies it to the control means 11 and the load 30 connected to the output terminal.

The switch 16 opens and closes when power is supplied to or cut off from a drive coil (not shown). One end of the switch 16 is connected to the output end of the switching power supply 15 and the other end is connected to the load 30. Supply / stop of DC voltage from the switching power supply 15 to the load 30 is performed by opening and closing the switch 16.
The load 30 is a plurality of electric devices other than the fan motor 20 provided in the deodorizer, such as an ion generation device, an ultraviolet irradiation device, a display device that displays a driving state and a setting state to the user, and the like. .

  The control unit 11 includes a storage unit configured by a ROM, a RAM, and the like, and controls the power supply device 1 in response to driving information instructed by the user and detection information input from various sensors (not shown). Specifically, the control unit 11 controls the switching power supply 15 as described above, and controls the drive circuit 21 according to the DC voltage taken from the voltage detection unit 14. Further, the control means 11 controls opening / closing of the switch 16 to control the supply / stop of supply of the DC voltage from the switching power supply 15 to the load 30. Further, although detailed description is omitted, the control means 11 performs control related to the operation of the deodorizer, for example, ion generation, corresponding to the operation information instructed by the user and the detection information input from various sensors (not shown). Controls the operation of the device and the ultraviolet irradiation device.

In the present embodiment, the control unit 11 is described as performing control related to the operation of the deodorizer as described above, in addition to control related to the power supply device 1, but the present invention is not limited to this. Control means for performing control related to the operation of the deodorizer may be provided separately from the control means for controlling. Further, a control unit that is provided outside the power supply device 1 and performs control related to the operation of the deodorizer may also control the power supply device 1.
Further, the switching power supply 15 is used as the power supply means. However, the present invention is not limited to this. For example, the voltage may be increased or decreased to a desired voltage using a transformer and supplied to the control means 11 or the load 30. Good.

  Next, using FIG. 1 to FIG. 3, the principle and operation when determining the interruption of the power supply from the AC power supply 40 in the power supply device 1 of the present embodiment will be described. FIG. 2 shows a temporal change in the detection voltage Vm detected by the voltage detection means 14 when the power supply from the AC power supply 40 is momentarily cut off (a momentary interruption occurs). 2A to 2C, Vr1 and Vr2 are ripple voltages superimposed on the detection voltage Vm due to the rotation of the fan motor 20, and Vr1 <Vr2. Vs, Vs1, and Vs2 are power failure determination voltages that are threshold voltages for the control means 11 to detect the occurrence of a momentary interruption, and Vs1 and Vs2 are values determined corresponding to the above-described Vr1 and Vr2. (Vs1> Vs2). Ve is a value of a detection voltage Vm (hereinafter referred to as a reset voltage) in which the voltage supplied from the switching power supply 15 to the control unit 11 is lower than the drive voltage of the control unit 11, and the detection voltage Vm is equal to or less than the reset voltage Ve. Then, the control means 11 is stopped (reset). In the following description, when a general power failure determination voltage is described, it is simply described as Vs.

  When an instantaneous interruption occurs, the charging voltage of the capacitor 13 decreases with time by being supplied to the fan motor 20 and the switching power supply 15. Therefore, the voltage across the capacitor 13, that is, the detection voltage Vm, which is the charging voltage of the capacitor 13, corresponds to the capacitance of the capacitor 13 and the resistance of the load 30, as shown by the line 43 a and the broken line 44 a in FIG. It decreases according to the time constant. As described above, when the detection voltage Vm becomes equal to or lower than the reset voltage Ve, the direct current voltage supplied to the control means 11 via the switching power supply 15 is also reduced, and the control means 11 is reset.

  When the control means 11 is reset, when the power supply from the AC power supply 40 is restored at the point 42a and a DC voltage is applied to the control means 11 again, the operating conditions of the deodorizer set before the occurrence of the instantaneous interruption In addition, since all the setting conditions of the power supply device 1 are reset to the initial setting state, the user needs to set the driving conditions again. In order to prevent this, the voltage supply to the control means 11 during the occurrence of a momentary interruption is prevented from being interrupted as much as possible, that is, by increasing the capacity of the capacitor 13 and increasing the amount of charge, the discharge time from the capacitor 13 is increased. Since it is necessary to make the detection voltage Vm lower than the reset voltage Ve as long as possible, it is necessary to increase the capacity of the capacitor 13 and increase the cost.

  Therefore, as explained in the background art, if the control means 11 detects the occurrence of a momentary interruption, the detection voltage Vm is reset by slowing down the detection voltage Vm as much as possible by stopping the voltage supply to the load 30. It is conceivable to delay the reset of the control means 11 by extending the supply time of the DC voltage to the control means 11 so as not to become the voltage Ve or lower. For example, as shown in FIG. 2 (A), when the detection voltage Vm detected by the voltage detection means 14 is equal to or lower than a predetermined power failure determination voltage Vs1 (point 41a or lower in FIG. 2 (A)), the control means 11 It is determined that a disconnection has occurred. The control means 11 that has detected the instantaneous interruption stops the supply of the DC voltage to the load 30 by opening the switch 16 (the state indicated by the broken line in FIG. 1).

  If the supply of the DC voltage to the load 30 is stopped in this way, the charging voltage of the capacitor 13 is used only by the control means 11, and as shown by the line 45a in FIG. Compared with the case where the supply is not stopped (broken line 44a), the decrease in the detection voltage Vm is delayed. By delaying the decrease in the detection voltage Vm, the detection voltage Vm can be prevented from being equal to or lower than the reset voltage Ve until the power supply from the AC power supply 40 is restored at the point 42a, and the supply of the DC voltage to the control means 11 is not interrupted. Therefore, it is possible to prevent the reset of the control means 11 caused by the occurrence of instantaneous interruption as much as possible without increasing the capacity of the capacitor 13.

  In the method described above, in order to delay the discharge time of the charging voltage of the capacitor 13, that is, the decrease time of the detection voltage Vm, the control means 11 detects the occurrence of the instantaneous interruption as soon as possible, and the DC voltage to the load 30 is reduced. It is desirable to stop the supply as soon as possible. And in order to detect the occurrence of instantaneous interruption as soon as possible, it is necessary to set the power failure determination voltage Vs as high as possible. However, as shown in FIGS. 2A and 2B, since the ripple voltage is superimposed on the detection voltage Vm, if the power failure determination voltage Vs is set high, the ripple will be explained as described below. When the voltage is large, when the control unit 11 takes in the detection voltage Vm from the voltage detection unit 14, there is a possibility that it is erroneously determined that an instantaneous interruption has occurred.

  In general, the amplitude of the ripple voltage increases as the rotational speed of the fan motor 20 increases. FIG. 2A shows a case where the rotational speed of the fan motor 20 is low (for example, 400 rpm), and the amplitude of the ripple voltage Vr1 is small. On the other hand, FIG. 2B shows a case where the rotational speed of the fan motor 20 is high (for example, 1750 rpm), and the amplitude of the ripple voltage Vr2 is larger than the ripple voltage Vr1 shown in FIG.

  Therefore, when the ripple voltage Vr2 having the amplitude shown in FIG. 2B is superimposed on the detection voltage Vm, if the power failure determination voltage Vs is set to Vs1, the lower end value of the ripple voltage Vr2 may be lower than the power failure determination voltage Vs1. Therefore, there is a possibility that the control unit 11 that takes in the lower limit value of the ripple voltage Vr2 detected by the voltage detection unit 14 may erroneously determine that an instantaneous interruption has occurred. In order to prevent this erroneous determination, it is necessary to set the power failure determination voltage Vs to a certain value or less, specifically, the power failure determination voltage Vs2 in consideration of the amplitude of the ripple voltage Vr2 corresponding to the high rotational speed of the fan motor 20. is there. However, if the power failure judgment voltage is set to Vs2, when the rotation speed of the fan motor 20 is low, the detection voltage Vm becomes equal to or lower than the reset voltage Ve before the control means 11 detects an instantaneous interruption, and the control means 11 is reset. There was a risk of being. In order to prevent this, the capacity of the capacitor 13 needs to be set so that the detection voltage Vm does not become equal to or lower than the reset voltage Ve, and there is a limit to reducing the capacity of the capacitor 13.

  Therefore, in the power supply device 1 of the present invention, when a momentary interruption occurs and the fan motor 20 is stopped, the capacitor 13 is charged by the regenerative current generated in the fan motor 20 and having a magnitude due to the rotation speed of the fan motor 20. The power failure determination voltage Vs corresponding to the rotational speed of the fan motor 20 is set using this, and the occurrence of an instantaneous interruption is detected by using this.

  First, the influence of the difference in the regenerative current depending on the rotation speed of the fan motor 20 on the detection voltage Vm will be described. FIG. 2C shows the difference in the decrease time of the detection voltage Vm due to the difference in the rotation speed R of the fan motor 20 immediately before the occurrence of the instantaneous interruption. Generally, in an electric motor such as a DC brushless motor, the higher the number of revolutions immediately before stopping, the greater the regenerative current that is generated. Accordingly, the detection voltage Vm becomes equal to or lower than the power failure determination voltage Vs when an instantaneous interruption occurs, and the rate of decrease in the detection voltage Vm after the control unit 11 stops supplying the DC voltage to the load 30 is the rotational speed R of the fan motor 20. The higher the value, the slower.

  For example, when R = 400 rpm, since the regenerative current generated by the fan motor 20 is small, the detection voltage Vm becomes zero at the point 46a when the power failure continues. When R = 820 rpm, since the regenerative current generated by the fan motor 20 is larger than when R = 400 rpm, the point 46b at which the detection voltage Vm becomes zero is shifted to the right as compared with the point 46a. The decreasing speed of the voltage Vm is slow. When R = 1750 rpm, since the regenerative current generated by the fan motor 20 is larger than when R = 400 rpm or 820 rpm, the point 46c at which the detection voltage Vm becomes zero shifts further to the right than the point 46b. As a result, the rate of decrease in the detection voltage Vm is further reduced.

  From the above, when the rotational speed R of the fan motor 20 immediately before the momentary interruption occurs is high, the rate of decrease in the detected voltage Vm is slower than when the rotational speed R is low. The time until the voltage can be supplied and the detection voltage Vm becomes equal to or lower than the reset voltage Ve, that is, the time until the control unit 11 is reset becomes longer. Therefore, when the rotational speed R of the fan motor 20 immediately before the occurrence of the instantaneous interruption is high, the control means 11 is reset even if the timing for detecting the occurrence of the instantaneous interruption is delayed as compared with the case where the rotational speed R is low. There is little possibility.

  In consideration of the above, as shown in FIG. 2A, when the rotation speed R of the fan motor 20 is low (hereinafter, the low rotation speed is referred to as RL) and the ripple voltage Vr1 with a small amplitude is superimposed on the detection voltage Vm Is a power failure judgment voltage Vs1 corresponding to the ripple voltage Vr1, and as shown in FIG. 2B, the rotation speed R of the fan motor 20 is high (hereinafter, the high rotation speed is described as RH), and the amplitude is larger than the ripple voltage Vr1. When the large ripple voltage Vr2 is superimposed on the detection voltage Vm, the power failure determination voltage Vs2 corresponding to the ripple voltage Vr2 is lower than the power failure determination voltage Vs1.

  When the rotational speed of the fan motor 20 is RH, as shown in FIG. 2B, the control means 11 cannot detect the occurrence of instantaneous interruption until the detection voltage Vm taken from the voltage detection means 14 drops to a point 41b. However, when a regenerative current corresponding to the rotational speed RH of the fan motor 20 is supplied to the capacitor 13, as shown by a line 45b in FIG. 2B, the decrease in the detected voltage Vm is caused by the rotational speed of the fan motor 20. Is RL and the ripple voltage Vr1 having a small amplitude is superimposed (a line 45a in FIG. 2A). Then, since the power supply from the AC power supply 40 that has recovered from the instantaneous interruption at the point 42b is resumed before the detection voltage Vm becomes equal to or lower than the reset voltage Ve, the instantaneous power caused by the ripple voltage while preventing the control unit 11 from being reset. It is possible to prevent misjudgment of disconnection.

  On the other hand, when the rotational speed of the fan motor 20 is RL and the amplitude of the ripple voltage Vr is small, the power failure determination voltage Vs is set to Vs1 higher than Vs2, as shown in FIG. Thereby, since the control means 11 can detect a momentary interruption quickly at the point 41a, it can stop the direct-current power supply to the load 30 quickly. Thereby, before the detection voltage Vm falls below a voltage required by the control means 11, the power supply from the AC power supply 40 is restarted at the point 42a, and the control means 11 can be prevented from being reset.

FIG. 3 is a power failure determination voltage table 50 stored in advance in the storage unit of the control unit 11. The power failure determination voltage table 50 is set in advance in consideration of the effect of the regenerative current generated by the fan motor 20 and corresponding to the rotation speed R, and the rotation is determined for each rotation speed of the fan motor 20. The magnitude of the ripple voltage Vr superimposed on the detection voltage Vm at several times and the power failure detection voltage Vs at the number of rotations are determined.
In addition, the rotation speed of the fan motor 20 in a present Example is set to the minimum rotation speed: 400rpm and the maximum rotation speed: 1750rpm. Further, the control means 11 instructs the rotation speed R of the fan motor 20 via the drive circuit 21 and recognizes the indicated rotation speed as the current rotation speed R of the fan motor 20.

  The ripple voltage Vr is measured for each rotation speed of the fan motor 20 by performing a test or the like in advance. The power failure determination voltage Vs is obtained by subtracting the ripple voltage Vr divided by 2 from the detection voltage Vm detected by the voltage detection means 14 when the AC voltage is normally supplied from the AC power supply 40, and then a predetermined voltage. Is subtracted. In creating the power failure judgment voltage table 50 of FIG. 3, the normal detection voltage Vm is 140 V and the predetermined voltage is 5 V. For example, the power failure judgment voltage Vs when R = 400 rpm is (140-3 / 2). −5 = 134V. The reason for determining the power failure determination voltage Vs by further pulling a predetermined voltage (here, 5V) is because variation in detection results due to the influence of external noise in the voltage detection means 14 is taken into consideration.

  Next, processing when the control unit 11 detects that the power supply from the AC power supply 40 has been cut off will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of processing when the control means 11 detects that the power supply from the AC power supply 40 has been cut off, ST represents a step, and the following numbers represent step numbers. Yes. In the flowchart of FIG. 4, processing related to the present invention is mainly described, and description of other processing such as operation control of the deodorizer corresponding to the operating condition instructed by the user is omitted.

  Upon receiving a user's operation start instruction, the control means 11 starts operation of the deodorizer. The control means 11 that has started operation periodically takes in the detection voltage Vm, which is a voltage applied to the fan motor 20 from the voltage detection means 14 (ST1). Further, the control means 11 stores the rotational speed R of the fan motor 20 instructed to the drive circuit 21 (ST2). The detected detection voltage Vm and the rotation speed R of the fan motor 20 are stored in a storage unit (not shown) of the control means 11.

  Next, the control means 11 refers to the stored power failure determination voltage table 50 and extracts the power failure determination voltage Vs corresponding to the fetched rotation speed R of the fan motor 20 (ST3).

  Next, the control means 11 determines whether or not the detected voltage Vm is equal to or less than the extracted power failure determination voltage Vs (ST4). If the detected voltage Vm is equal to or less than the extracted power failure determination voltage Vs (ST4-Yes), the control means 11 opens the switch 16 or maintains the switch 16 open and the DC voltage to the load 30 is maintained. Is stopped (ST7), and the process returns to ST4.

  If the detected voltage Vm is not less than the extracted power failure judgment voltage Vs (ST4-No), the control means 11 judges whether or not the switch 16 is open (ST5). If the switch 16 is not open (ST5-No), the control means 11 returns the process to ST1. If the switch 16 is open (ST5-Yes), the control means 11 closes the switch 16, restarts the supply of the DC voltage to the load 30 (ST6), and returns the process to ST1.

  As described above, according to the power supply device of the present invention, a plurality of predetermined voltages are provided for determining the interruption of the power supply from the AC power supply. In the electric motor, a regenerative current corresponding to the number of revolutions is generated, and the regenerative current generated increases as the number of revolutions increases. In the present invention, focusing on the fact that the capacitor is charged by the regenerative current generated by the electric motor, a predetermined voltage that is a threshold for detecting a power failure is determined according to the number of revolutions. If the DC voltage taken in from the voltage detection means is equal to or lower than a predetermined voltage determined for each number of rotations of the motor, the control means determines that a momentary interruption has occurred in the AC power supply and transfers the power supply unit to the external load. Since the supply of DC power is stopped, the resetting of the control means due to the drop in the DC voltage supplied to the control means can be delayed as much as possible and the capacitance of the capacitor can be reduced.

DESCRIPTION OF SYMBOLS 1 Power supply device 11 Control means 12 Rectifier circuit 13 Capacitor 14 Voltage detection means 15 Switching power supply 16 Switch 20 Fan motor 30 Load 40 AC power supply 50 Power failure judgment voltage table

Claims (4)

A DC power supply unit that includes a rectifier circuit and a capacitor, converts AC power supplied from an AC power source to DC power and supplies the DC motor, a voltage detection unit that detects a DC voltage across the capacitor, and a control unit. A power supply device for controlling the rotation of the electric motor,
The control means stores in advance a predetermined voltage corresponding to the rotation speed of the electric motor, and if the DC voltage taken from the voltage detection means is equal to or lower than the predetermined voltage corresponding to the rotation speed of the electric motor, the AC power supply It is judged that the power supply from is cut off.   The power supply device according to claim 1, wherein the plurality of predetermined voltages are set to decrease as the rotational speed of the electric motor increases.   3. The power supply device according to claim 1, wherein the control unit includes a power failure determination voltage table in which the rotation speed of the electric motor is associated with a plurality of the predetermined voltages. The power supply device is connected in parallel to the output side of the rectifier circuit and supplies DC power to the control means and an external load. The power supply means is controlled to be opened and closed by the control means, so that the power supply means An opening / closing means for supplying or stopping the supply of DC power to the external load;
The control means, when judging that the power supply from the AC power supply is cut off, opens the opening / closing means and stops the supply of DC power from the power supply means to the external load. The power supply device according to claim 1.

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