Blower

Abstract

This invention provides a technology that can suppress overvoltage in a blower. [Solution] In the blower 1, the rectifier circuit 10 rectifies the input AC voltage using full-wave rectification or voltage doubling rectification. The blower unit 14 has a motor 16 for blowing air. The drive unit 12 drives the blower unit 14 based on the voltage rectified by the rectifier circuit 10. The control unit 22 sets the rectification operation of the rectifier circuit 10 to full-wave rectification or voltage doubling rectification according to the voltage rectified by the rectifier circuit 10. When the overvoltage detection unit 24 detects that the voltage rectified by the rectifier circuit 10 is an overvoltage, it switches the rectification operation of the rectifier circuit 10 to full-wave rectification.

Description

Technical Field

[0001] The present disclosure relates to a blower device.

Background Art

[0002] An air conditioner includes, for example, a rectifier circuit connected to an AC power supply, an inverter, and a motor of a blower fan (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There are known blower devices such as air conditioners that can operate when connected to any of two types of AC power supplies with different AC voltages. The inventors of the present invention have recognized that in a configuration corresponding to two types of AC power supplies by switching full-wave rectification and voltage-doubling rectification according to the AC voltage, an overvoltage may occur due to a malfunction or the like.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a technique capable of suppressing overvoltage in a blower device.

Means for Solving the Problems

[0006] To solve the above problems, a blower according to one embodiment of the present disclosure includes: a rectifier circuit that full-wave rectifies or voltage-doubles an input AC voltage; a blower unit having a motor for blowing air; a drive unit that drives the blower unit based on the voltage rectified by the rectifier circuit; a control unit that sets the rectification operation of the rectifier circuit to full-wave rectification or voltage-doubles rectification according to the voltage rectified by the rectifier circuit; and an overvoltage detection unit that, when it detects that the voltage rectified by the rectifier circuit is an overvoltage, switches the rectification operation of the rectifier circuit to full-wave rectification.

[0007] Furthermore, any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid as aspects of this disclosure. [Effects of the Invention]

[0008] According to this disclosure, overvoltage can be suppressed in a blower. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram schematically showing the configuration of the blower device according to the embodiment. [Figure 2] Figure 1 is a circuit diagram of the switch circuit. [Figure 3] Figure 1 is a circuit diagram of the overvoltage detection unit. [Modes for carrying out the invention]

[0010] The embodiments for implementing this disclosure will be described below with reference to the attached drawings. In the embodiments and modifications, the same or equivalent components and members will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. In addition, the dimensions of the members in each drawing will be enlarged or reduced as appropriate for ease of understanding. Furthermore, some members that are not important for explaining the embodiments will be omitted from the drawings.

[0011] Figure 1 is a block diagram schematically showing the configuration of the blower device 1 in the embodiment. The blower device 1 is an air conditioning device capable of blowing air, such as an air conditioner, a heat exchange ventilation device, a ventilation device that ventilates without heat exchange, or an air purifier, and can also be called an air conditioning device. Below, an example of the blower device 1 being a heat exchange ventilation device will be described. A heat exchange ventilation device can be installed, for example, in the ceiling space, inside the side walls, or under the floor of a building, and is a ventilation device that supplies and exhausts air to and from indoor spaces. A heat exchange ventilation device has the function of exchanging heat during supply and exhaust.

[0012] A heat exchange ventilation system ventilates by exchanging heat between an exhaust flow, which is air exhausted from a designated indoor space to the outside, and a supply flow, which is air supplied from the outside to a designated indoor space. For example, in the Japanese summer, a heat exchange ventilation system ventilates while simultaneously transferring heat from the supply flow to the exhaust flow, suppressing the unwanted inflow of heat. Similarly, in the Japanese winter, a heat exchange ventilation system ventilates while simultaneously transferring heat from the exhaust flow to the supply flow, suppressing the unwanted outflow of heat. A heat exchange element is used for the heat exchange between the exhaust flow and the supply flow.

[0013] A heat exchange ventilation system comprises an exhaust fan for generating exhaust airflow and a supply fan for generating supply airflow. When performing heat exchange ventilation, the exhaust fan and the supply fan are operated.

[0014] The blower 1 comprises a rectifier circuit 10, a drive unit 12, a blower unit 14, a first voltage divider circuit 20, a control unit 22, and an overvoltage detection unit 24.

[0015] The blower 1 is connected to an AC power supply 50, and the blower unit 14 is driven based on the AC power supplied from the AC power supply 50. When the blower 1 is used in Japan, the AC power supply 50 is, for example, a commercial AC power supply of either 100V or 200V. The blower 1 can operate regardless of whether the AC power supply 50 is of the 100V or 200V AC system. The two voltages of the AC power supply 50 may differ depending on the country in which the blower 1 is used. The following assumes use in Japan.

[0016] The blower unit 14 corresponds to an exhaust blower. Although not shown in the figures, another blower unit 14 corresponding to an intake blower is also provided. The blower unit 14 has a fan (not shown) and a motor 16 for rotating the fan to blow air. Since various known configurations can be used for the blower unit 14, further detailed explanation is omitted.

[0017] The rectifier circuit 10 converts the AC voltage input from the AC power supply 50 into a DC voltage VDC1. The rectifier circuit 10 performs full-wave rectification or voltage doubler rectification on the input AC voltage, smooths the rectified voltage, and outputs the DC voltage VDC1. The rectification operation of the rectifier circuit 10 can be switched between full-wave rectification and voltage doubler rectification.

[0018] The rectifier circuit 10 includes four diodes D1 to D4, two capacitors C1 and C2, and a switch circuit 26.

[0019] The four rectifier diodes D1 to D4 are connected in a bridge configuration. One end of the AC power supply 50 is connected to the connection node between diode D4 and diode D1. The other end of the AC power supply 50 is connected to the connection node N1 between diode D2 and diode D3. The connection node between diode D2 and diode D4 is grounded. A DC voltage VDC1 is output from the connection node between diode D1 and diode D3.

[0020] Two capacitors C1 and C2 are connected in series between the connection node of diodes D1 and D3 and ground.

[0021] A switch circuit 26 is connected between the connection node N2 of the capacitor C1 and the capacitor C2 and the connection node N1. The switch circuit 26 can be switched to conduct or not conduct between the connection node N1 and the connection node N2 according to the control signal S1 supplied from the control unit 22 and the control signal S2 supplied from the overvoltage detection unit 24.

[0022] When the connection between the connection node N1 and the connection node N2 is non-conductive, the rectifier circuit 10 performs full-wave rectification. When the connection between the connection node N1 and the connection node N2 is conductive, the rectifier circuit 10 performs voltage-doubling rectification.

[0023] Figure 2 is a circuit diagram of the switch circuit 26 in Figure 1. As shown in Figure 2, the switch circuit 26 has, for example, a relay 30, a low-side switch element SW1, and a high-side switch element SW2.

[0024] The switch element SW2 has one end to which a predetermined fixed voltage VDC2 is supplied and the other end connected to one control terminal of the relay 30. The switch element SW2 can be switched to conduct or not conduct according to the control signal S2. For example, the switch element SW2 conducts when the control signal S2 is at a high level and becomes non-conductive when the control signal S2 is at a low level.

[0025] The switch element SW1 has one end connected to the other control terminal of the relay 30 and the other end grounded. The switch element SW1 can be switched to conduct or not conduct according to the control signal S1. For example, the switch element SW1 conducts when the control signal S1 is at a high level and becomes non-conductive when the control signal S1 is at a low level.

[0026] The switch included in the relay 30 is connected between the connection node N1 and the connection node N2 in Figure 1. When the switch element SW1 and the switch element SW2 conduct, a current flows between one control terminal and the other control terminal of the relay 30, the switch included in the relay 30 conducts, and the rectifier circuit 10 performs voltage-doubling rectification.

[0027] If at least one of the switch elements SW1 and SW2 is non-conductive, no current flows between one control terminal and the other control terminal of the relay 30, the switch included in the relay 30 is non-conductive, and the rectifier circuit 10 performs full-wave rectification.

[0028] Returning to Figure 1, the drive unit 12 drives the blower unit 14 based on the DC voltage VDC1 rectified and smoothed by the rectifier circuit 10. The drive unit 12 has, for example, a three-phase inverter that converts the DC voltage VDC1 into a three-phase AC voltage and supplies the converted three-phase AC voltage to the motor 16 of the blower unit 14. The drive unit 12 has a plurality of switching elements (not shown), and drives the motor 16 by the switching operation of these switching elements. The drive unit 12 and the motor 16 can also be collectively called a DC motor. Since known configurations can be used for the drive unit 12 and the motor 16, further detailed explanations are omitted.

[0029] The first voltage divider circuit 20 divides the DC voltage VDC1 and outputs the first divided voltage V1 to the control unit 22 and the overvoltage detection unit 24. The first voltage divider circuit 20 includes two resistors R1 and R2 connected in series, and outputs the first divided voltage V1 from the connection node of resistors R1 and R2.

[0030] The control unit 22 is composed of, for example, a microcontroller. The control unit 22 sets the rectification operation of the rectifier circuit 10 to full-wave rectification or voltage doubler rectification according to the first voltage divider voltage V1. The control unit 22 starts up when the power to the blower 1 is turned on and outputs a low-level control signal S1 to the rectifier circuit 10, thereby setting the rectification operation of the rectifier circuit 10 to full-wave rectification. Subsequently, the control unit 22 performs A / D conversion on the first voltage divider voltage V1, compares the first voltage divider voltage V1 with a predetermined threshold value based on the data after A / D conversion, and sets the rectification operation of the rectifier circuit 10.

[0031] When the first divided voltage V1 is lower than the threshold, the control unit 22 outputs a high-level control signal S1 to the rectifier circuit 10, thereby setting the rectification operation of the rectifier circuit 10 to voltage doubling rectification. In this case, it corresponds to a 100V AC system. As a result, the DC voltage VDC1 becomes approximately 280V.

[0032] When the first divided voltage V1 is above a threshold, the control unit 22 outputs a low-level control signal S1 to the rectifier circuit 10, thereby setting the rectification operation of the rectifier circuit 10 to full-wave rectification. In this case, it corresponds to a 200V AC system. As a result, the DC voltage VDC1 becomes approximately 280V. In other words, whether it is a 100V AC system or a 200V AC system, an equivalent DC voltage VDC1 can be obtained, and the motor 16 can be driven.

[0033] The values ​​of resistors R1 and R2, as well as the threshold values, can be appropriately determined through experimentation or simulation so as to distinguish between 100V AC systems and 200V AC systems.

[0034] The configuration of the control unit 22 can be realized through the collaboration of hardware and software resources, or solely through hardware resources. Hardware resources can include analog elements, microcomputers, DSPs, ROMs, RAMs, ASICs, FPGAs, and other LSIs. Software resources can include programs such as firmware.

[0035] In this case, with a 200V AC system and the rectifier circuit 10 performing full-wave rectification, if the control unit 22 malfunctions due to noise or other factors and switches to voltage doubling rectification, a high DC voltage VDC1 exceeding 500V will be generated, potentially causing damage to the circuit board and components, smoke, and fire.

[0036] Furthermore, in a 100V AC system where the rectifier circuit 10 is performing voltage doubling rectification, if a fault such as a neutral wire loss occurs in the AC power supply 50, the AC voltage of the AC power supply 50 may change from 100V to a higher voltage such as 180V. In this case as well, a high DC voltage VDC1 exceeding 500V will be generated.

[0037] To address these situations, a configuration in which the control unit 22 detects when the DC voltage VDC1 is an overvoltage is conceivable. However, as mentioned above, the control unit 22 performs A / D conversion on the first voltage divider V1 and compares the data based on the A / D conversion, so it takes a relatively long time from the time an overvoltage occurs until it can be detected. Therefore, there is a possibility that damage to the circuit board or components may occur before the overvoltage is detected.

[0038] Therefore, in this embodiment, an overvoltage detection unit 24 is provided that compares voltages using an analog circuit to detect and suppress overvoltages. By comparing voltages using an analog circuit, overvoltages can be detected in a shorter time than with the control unit 22 which requires A / D conversion.

[0039] The overvoltage detection unit 24 detects that the DC voltage VDC1 is overvoltage when the first divided voltage V1 exceeds a predetermined overvoltage threshold. The overvoltage threshold may be, for example, the value of the first divided voltage V1 when the DC voltage VDC1 is approximately 380V. The overvoltage threshold can be appropriately determined by experiment or simulation to ensure proper detection of overvoltage.

[0040] When the overvoltage detection unit 24 detects that the DC voltage VDC1 is overvoltage, it outputs a low-level control signal S2 to the rectifier circuit 10, thereby switching the rectification operation of the rectifier circuit 10 to full-wave rectification. The low-level control signal S2 causes the switch element SW2 of the switch circuit 26 to become non-conductive, so the relay 30 can be controlled to become non-conductive even if the switch element SW1 is conducting, regardless of the operation of the control unit 22. This suppresses overvoltage and enhances safety.

[0041] For example, in a 200V AC system, if the rectifier circuit 10 is performing full-wave rectification and is switched to voltage doubler rectification due to a malfunction of the control unit 22, a DC voltage VDC1 exceeding 500V will be generated. In this case, the overvoltage detection unit 24 detects the occurrence of an overvoltage and switches the rectification operation of the rectifier circuit 10 to full-wave rectification. As a result, the DC voltage VDC1 drops to approximately 280V.

[0042] Furthermore, in a 100V AC system, when the rectifier circuit 10 is performing voltage doubling rectification, if the AC voltage changes to 180V due to a fault in the AC power supply 50, a DC voltage VDC1 exceeding 500V is generated. Therefore, the overvoltage detection unit 24 detects the occurrence of an overvoltage and switches the rectification operation of the rectifier circuit 10 to full-wave rectification. As a result, the DC voltage VDC1 drops to approximately 250V.

[0043] The overvoltage detection unit 24 does not detect an overvoltage if the first voltage divider V1 is below the overvoltage threshold. If the overvoltage detection unit 24 does not detect an overvoltage, it maintains a high-level control signal S2 and does not switch the rectification operation of the rectifier circuit 10.

[0044] Once the overvoltage detection unit 24 detects an overvoltage, it maintains the overvoltage detection state and continues to output a low-level control signal S2, thereby keeping the rectifier circuit 10 in full-wave rectification mode. This prevents repeated switching between full-wave rectification and voltage doubler rectification.

[0045] When the overvoltage detection unit 24 detects an overvoltage, it notifies the control unit 22 of the occurrence of the overvoltage by outputting a high-level notification signal S3. This allows the control unit 22 to perform the necessary control in response to the notification. If the overvoltage detection unit 24 does not detect an overvoltage, it keeps the notification signal S3 at a low level and does not notify the control unit 22.

[0046] When the control unit 22 receives notification from the overvoltage detection unit 24, it instructs the drive unit 12 to stop driving the blower unit 14, resets the control unit 22, and restarts it. After restarting, the control unit 22 outputs a release signal RST to release the hold operation of the overvoltage detection unit 24, thereby releasing the hold operation of the overvoltage detection unit 24 when an overvoltage is detected, and resets the rectification operation of the rectifier circuit 10 according to the DC voltage VDC1 rectified by the rectifier circuit 10. As a result, the operation of the blower 1 can be resumed after an overvoltage is detected.

[0047] Figure 3 is a circuit diagram of the overvoltage detection unit 24 shown in Figure 1. As shown in Figure 3, the overvoltage detection unit 24 includes, for example, a second voltage divider circuit 40, a comparator 42, an inverting buffer 44, a resistor R5, and a diode D5.

[0048] The second voltage divider circuit 40 divides a predetermined fixed voltage VDC3 and outputs a second divided voltage V2. The second voltage divider circuit 40 includes two resistors R3 and R4 connected in series, and outputs the second divided voltage V2 from the connection node of resistors R3 and R4. The second divided voltage V2 corresponds to the overvoltage threshold described above. The values ​​of resistors R3 and R4 can be appropriately determined in accordance with the overvoltage threshold.

[0049] The comparator 42 is a comparator and has a first input terminal to which the first divided voltage V1 from the first voltage divider circuit 20 is supplied, a second input terminal to which the second divided voltage V2 from the second voltage divider circuit 40 is supplied, and an output terminal to which a control signal S2 is output to switch the rectification operation of the rectifier circuit 10. The first input terminal is an inverting input terminal, and the second input terminal is a non-inverting input terminal. Resistor R5 is connected between the second input terminal and the output terminal of the comparator 42.

[0050] If no overvoltage occurs and the first voltage division voltage V1 is less than or equal to the second voltage division voltage V2, the comparator 42 outputs a high-level control signal S2.

[0051] On the other hand, if an overvoltage occurs and the first divided voltage V1 is higher than the second divided voltage V2, the comparator 42 outputs a low-level control signal S2. Due to the resistor R5, the second divided voltage V2 when the control signal S2 is low is lower, for example, to about 1 / 4 to 1 / 5 of the second divided voltage V2 when the control signal S2 is high. The value of the resistor R5 can be determined appropriately by experiment or simulation. The overvoltage detection unit 24 can also be called a comparator with hysteresis. Therefore, as described above, once the overvoltage detection unit 24 detects an overvoltage, it maintains the state in which an overvoltage has been detected and continues to output a low-level control signal S2.

[0052] The rectifier element diode D5 includes an anode to which a release signal RST is supplied from the control unit 22, and a cathode connected to the second input terminal of the comparator 42. When a high-level release signal RST is supplied for a predetermined time or longer, the comparator 42 outputs a high-level control signal S2, the second voltage divider V2 increases, and the overvoltage detection unit 24 is reset. This allows the holding operation of the overvoltage detection unit 24 to be released with a simple circuit configuration.

[0053] The inverting buffer 44 inverts the logic of the control signal S2 and outputs the resulting notification signal S3.

[0054] An amplifier may be used instead of the comparator 42. The configuration when an amplifier is used will be described below. The configuration of the overvoltage detection unit 24 other than the amplifier may be as previously described. The amplifier has a first input terminal to which the first divided voltage V1 is supplied from the first voltage divider circuit 20, a second input terminal to which the second divided voltage V2 is supplied from the second voltage divider circuit 40, and an output terminal to which a control signal S2 is output to switch the rectification operation of the rectifier circuit 10. The first input terminal is an inverting input terminal, and the second input terminal is a non-inverting input terminal. Resistor R5 is connected between the second input terminal and the output terminal of the amplifier.

[0055] If no overvoltage occurs and the first voltage divider V1 is less than or equal to the second voltage divider V2, the amplifier outputs a high-level control signal S2.

[0056] On the other hand, if an overvoltage occurs and the first divided voltage V1 is higher than the second divided voltage V2, the amplifier outputs a low-level control signal S2. Due to the resistor R5, the second divided voltage V2 when the control signal S2 is low is lower, for example, to about 1 / 4 to 1 / 5 of the second divided voltage V2 when the control signal S2 is high. The value of the resistor R5 can be determined appropriately by experiment or simulation. The overvoltage detection unit 24 can also be called a comparator with hysteresis. Therefore, as described above, once the overvoltage detection unit 24 detects an overvoltage, it maintains the overvoltage detection state and continues to output a low-level control signal S2.

[0057] The rectifier element diode D5 includes an anode to which a release signal RST is supplied from the control unit 22, and a cathode connected to the second input terminal of the amplifier. When a high-level release signal RST is supplied for a predetermined time or longer, the amplifier outputs a high-level control signal S2, the second voltage divider V2 increases, and the overvoltage detection unit 24 is reset.

[0058] According to this embodiment, when the DC voltage VDC1 rectified and smoothed by the rectifier circuit 10 is detected to be an overvoltage, the overvoltage detection unit 24 switches the rectification operation of the rectifier circuit 10 to full-wave rectification, thereby suppressing the overvoltage, preventing damage to the circuit board, and enhancing safety.

[0059] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processing processes, and that such modifications are also within the scope of the present disclosure.

[0060] One aspect of this disclosure is as follows:

[0061] [Item 1] A rectifier circuit that performs full-wave rectification or voltage doubling rectification on the input AC voltage, A blower unit having a motor for blowing air, A drive unit that drives the blower based on the voltage rectified by the rectifier circuit, A control unit that sets the rectification operation of the rectifier circuit to full-wave rectification or voltage doubler rectification according to the voltage rectified by the rectifier circuit, An overvoltage detection unit, which detects that the voltage rectified by the rectifier circuit is an overvoltage, switches the rectification operation of the rectifier circuit to full-wave rectification, A blower equipped with a ventilation device.

[0062] [Item 2] The blower according to item 1, wherein the overvoltage detection unit, once it detects an overvoltage, maintains the rectification operation of the rectifier circuit in full-wave rectification mode.

[0063] [Item 3] The blower according to item 1 or 2, wherein the overvoltage detection unit notifies the control unit when it detects an overvoltage.

[0064] [Item 4] The blower according to item 3, wherein when the control unit receives notification from the overvoltage detection unit, it causes the drive unit to stop driving the blower unit, releases the holding operation of the overvoltage detection unit, and resets the rectification operation of the rectifier circuit according to the voltage rectified by the rectifier circuit.

[0065] [Item 5] The circuit further comprises a first voltage divider circuit that divides the voltage rectified by the rectifier circuit and outputs a first divided voltage, The overvoltage detection unit is, A second voltage divider circuit divides a predetermined fixed voltage and outputs a second divided voltage, An amplifier or comparator having a first input terminal to which the first voltage divider is supplied, a second input terminal to which the second voltage divider is supplied, and an output terminal that outputs a control signal to switch the rectification operation of the rectifier circuit, A resistor connected between the aforementioned second input terminal and the aforementioned output terminal, A blower as described in item 4, having the following features.

[0066] [Item 6] The control unit is capable of supplying a release signal to the overvoltage detection unit for releasing the holding operation of the overvoltage detection unit. The overvoltage detection unit is, The blower according to item 5, having a rectifier element including an anode to which the release signal is supplied and a cathode connected to the second input terminal.

[0067] [Item 7] The blower according to item 5 or 6, wherein the control unit performs A / D conversion on the first voltage divider and sets the rectification operation of the rectifier circuit based on the data after A / D conversion. [Industrial applicability]

[0068] This disclosure can be used in blower devices. [Explanation of Symbols]

[0069] 1... Blower, 10... Rectifier circuit, 12... Drive unit, 14... Blower unit, 16... Motor, 20... First voltage divider circuit, 22... Control unit, 24... Overvoltage detection unit, 26... Switch circuit, 30... Relay, 40... Second voltage divider circuit, 42... Comparator, 44... Inverting buffer, C1, C2... Capacitors, D1, D2, D3, D4, D5... Diodes, R1, R2, R3, R4, R5... Resistors, SW1, SW2... Switching elements.

Claims

1. A rectifier circuit that performs full-wave rectification or voltage doubling rectification on the input AC voltage, A blower unit having a motor for blowing air, A drive unit that drives the blower based on the voltage rectified by the rectifier circuit, A control unit that sets the rectification operation of the rectifier circuit to full-wave rectification or voltage doubler rectification according to the voltage rectified by the rectifier circuit, An overvoltage detection unit, which detects that the voltage rectified by the rectifier circuit is an overvoltage, switches the rectification operation of the rectifier circuit to full-wave rectification, A blower equipped with a ventilation device.

2. The blower according to claim 1, wherein the overvoltage detection unit, once it detects an overvoltage, maintains the rectification operation of the rectifier circuit in full-wave rectification mode.

3. The blower according to claim 1 or 2, wherein the overvoltage detection unit notifies the control unit when it detects an overvoltage.

4. The blower according to claim 3, wherein when the control unit receives notification from the overvoltage detection unit, it causes the drive unit to stop driving the blower unit, releases the holding operation of the overvoltage detection unit, and resets the rectification operation of the rectifier circuit according to the voltage rectified by the rectifier circuit.

5. The circuit further comprises a first voltage divider circuit that divides the voltage rectified by the rectifier circuit and outputs a first divided voltage, The overvoltage detection unit is, A second voltage divider circuit divides a predetermined fixed voltage and outputs a second voltage divider, An amplifier or comparator having a first input terminal to which the first voltage divider is supplied, a second input terminal to which the second voltage divider is supplied, and an output terminal that outputs a control signal to switch the rectification operation of the rectifier circuit, A resistor connected between the second input terminal and the output terminal, The blower according to claim 4, having the following features.

6. The control unit is capable of supplying a release signal to the overvoltage detection unit for releasing the holding operation of the overvoltage detection unit. The overvoltage detection unit is, The blower according to claim 5, further comprising a rectifier element including an anode to which the release signal is supplied and a cathode connected to the second input terminal.

7. The blower according to claim 5, wherein the control unit performs A / D conversion on the first voltage divider and sets the rectification operation of the rectifier circuit based on the data after A / D conversion.

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