Drive circuit, electrical device, and method for adjusting output of drive circuit

Abstract

A drive circuit (100) comprises: a rectification circuit that rectifies a commercial power supply; a voltage measurement unit (6) that measures a bus voltage after rectification by the rectification circuit; a reactor (2) that is provided on the input side or the output side of the rectification circuit and suppresses a harmonic current; an output circuit (7) to which the bus voltage output from the rectification circuit is input; a load output unit (22) that is provided in the output circuit (7) and outputs a current for driving an externally connected load; and a control unit (9) that adjusts, in accordance with the bus voltage measured by the voltage measurement unit (6), the current output from the load output unit (22). The control unit (9) causes the load output unit (22) to stop after the load output unit (22) has outputted the current for a short time after the commercial power supply has been turned on, measures the bus voltage by the voltage measurement unit (6) after a preset first time has elapsed, and adjusts and outputs the current of the load output unit (22) provided in the output circuit (7) on the basis of the measured bus voltage.

Description

Drive circuit, electrical device, and drive circuit output adjustment method

[0001] The present disclosure relates to a drive circuit, an electric device, and a method for adjusting the output of a drive circuit.

[0002] Commercial power supply voltages vary from country to country or region to region, with known 100V systems such as 100V, 110V, and 120V, and 200V systems such as 200V, 220V, 230V, and 240V. Therefore, in order to standardize the drive circuits incorporated into electrical equipment, it is necessary to measure the commercial power supply voltage and optimize operation according to the measurement results.

[0003] In a drive circuit that rectifies commercial power supply voltage and controls it with an inverter, it is possible to adjust the output and precisely control power consumption, so it can handle voltage differences of around 10 V in 100 V or 200 V systems.

[0004] Patent Document 1 discloses an electrical device that can be used with different commercial power supply voltages by rectifying the commercial power supply voltage, measuring the rectified voltage, and controlling it according to the measurement result.

[0005] JP 2016-59387 A

[0006] Generally, devices that rectify commercial power and use the rectified DC voltage to drive a load generate harmonic currents, so a reactor is installed to address this. However, the method disclosed in Patent Document 1 does not take into account the current delay caused by the reactor immediately after the commercial power is turned on, resulting in an overshoot of the rectified voltage, making it impossible to measure the voltage accurately.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a drive circuit that is equipped with a reactor for suppressing harmonic currents and can quickly and accurately measure rectified voltage.

[0008] In order to solve the above-mentioned problems and achieve the object, a drive circuit according to the present disclosure includes a rectifier circuit that rectifies a commercial power source, a voltage measurement unit that measures a bus voltage after rectification by the rectifier circuit, a reactor that is provided on the input or output side of the rectifier circuit and that suppresses harmonic currents, an output circuit to which the bus voltage output from the rectifier circuit is input, a load output unit that is provided in the output circuit and that outputs a current that drives an externally connected load, and a control unit that adjusts the current output from the load output unit in accordance with the bus voltage measured by the voltage measurement unit. After the commercial power source is turned on, the control unit outputs a current from the load output unit for a short period of time and then stops it, measures the bus voltage using the voltage measurement unit after a preset first time has elapsed, and adjusts and outputs the current from the load output unit provided in the output circuit based on the measured bus voltage.

[0009] The drive circuit according to the present disclosure has a reactor for suppressing harmonic currents, and has the effect of being able to quickly and accurately measure the rectified voltage.

[0010] Circuit diagram of a drive circuit according to the first embodiment. Diagram showing an example of a hardware configuration that realizes a processing unit provided in the drive circuit according to the first embodiment. Waveform diagram of a bus voltage after rectification of the drive circuit according to the first embodiment. Flowchart showing the operation up to measuring the input voltage of the drive circuit according to the first embodiment. Structural diagram of an electric vacuum cleaner including the drive circuit according to the first embodiment. Structural diagram of a hand dryer including the drive circuit according to the first embodiment.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drive circuit, an electric device, and a drive circuit output adjustment method according to embodiments will be described in detail below with reference to the accompanying drawings.

[0012] Embodiment 1. Fig. 1 is a circuit diagram of a drive circuit according to embodiment 1. The drive circuit 100 according to embodiment 1 shown in Fig. 1 is composed of a power supply input unit 21, a reactor 2, a diode bridge 3, a capacitor 4, a voltage measurement unit 6, an output circuit 7, and a control unit 9. In embodiment 1, the external load connected to the output circuit 7 is a motor 8, as an example.

[0013] The power supply input unit 21 is connected to an AC power supply 1 , which is a commercial power supply, to supply power to the drive circuit 100 .

[0014] The reactor 2 rectifies the AC power supply 1 and converts it into a DC power supply to suppress harmonic currents generated in a device that drives a motor 8 .

[0015] The diode bridge 3 and capacitor 4 constitute a rectifier circuit that converts AC current input from the AC power supply 1 into DC current. The rectifier circuit rectifies the AC current using the diode bridge 3 and smooths it using the capacitor 4. In the drive circuit 100, the DC current output from the rectifier circuit is output to a bus 5 that connects the rectifier circuit and the output circuit 7, and a DC voltage is applied to the bus 5. For example, when an AC current of 100 V is input from the AC power supply 1, the DC voltage applied to the bus 5 is approximately 141 V. Hereinafter, the voltage applied to the bus 5 will be referred to as the bus voltage. The output circuit 7 includes a load output unit 22 that outputs driving power to the motor 8.

[0016] The voltage measurement unit 6 measures the bus voltage.

[0017] The control unit 9 receives the bus voltage value measured by the voltage measurement unit 6, estimates the input voltage of the AC power supply 1 from the bus voltage value, and varies the current output from the output circuit 7 in accordance with the input voltage of the AC power supply 1 to control the output of the motor 8 to an appropriate output. The control unit 9 includes a processing unit 10 for estimating the input voltage of the AC power supply 1 and controlling the output circuit 7. FIG. 2 is a diagram showing an example of a hardware configuration realizing the processing unit included in the drive circuit according to the first embodiment. The processing unit 10 is realized as a computer system by a processing circuit including a processor 81 that executes various processes, a memory 82 that serves as a main memory, and a storage device 83 that stores information.

[0018] The processor 81 may be a computing device such as an arithmetic unit, a microprocessor, a microcomputer, a central processing unit (CPU), or a digital signal processor (DSP). The memory 82 may be a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM). The storage device 83 stores a program for estimating the input voltage of the AC power supply 1 and controlling the output circuit 7. The processor 81 reads the program stored in the storage device 83 into the memory 82 and executes it. The processor 81 reads the program stored in the storage device 83 into the memory 82 and executes it, thereby realizing the functions of the processing unit 10.

[0019] The processing unit 10 is provided with a voltage estimation unit 11 that estimates the bus voltage from the voltage value measured by the voltage measurement unit 6, storage means 12 that stores input data and preset data, and a load drive signal output unit 13 that controls the output circuit 7. Here, the storage means 12 is a storage device 83 built into the processing unit 10, but an external storage device separate from the processing unit 10 may be provided in the control unit 9.

[0020] The voltage estimator 11 receives the bus voltage value measured by the voltage measurer 6 and estimates the input voltage of the AC power supply 1 from the voltage value input from the voltage measurer 6. Based on the input voltage of the AC power supply 1 estimated by the voltage estimator 11, the load drive signal outputter 13 controls the on / off timing of the transistors constituting the output circuit 7. This makes it possible to adjust the output of the motor 8 connected to the load outputter 22 provided in the output circuit 7.

[0021] Next, the operation of the drive circuit 100 according to the first embodiment will be described. FIG. 3 is a waveform diagram of the bus voltage after rectification by the drive circuit according to the first embodiment. In FIG. 3, the solid line indicates the bus voltage after rectification by the drive circuit 100 according to the first embodiment. Note that FIG. 3 also indicates the bus voltage after rectification by a general drive circuit equipped with a reactor by a dashed line. In a conventional drive circuit equipped with a reactor, a current delay generally occurs when the power is turned on, causing the bus voltage to overshoot as shown by the dashed line in FIG. 3, and the overshoot is resolved at time T2.

[0022] If the voltage is measured while the bus voltage is overshooting, even if, for example, an AC current of 100 V is input from AC power supply 1, the voltage of the AC current input from AC power supply 1 may be erroneously determined to be 110 V or 120 V, and the output of motor 8 may be controlled to a low value.

[0023] Also, because the current consumed when the power is turned on is small, it takes time for the overshoot to resolve naturally. If you wait until the overshoot resolves naturally before measuring the voltage, it will take a long time for the device to become usable after power is turned on.

[0024] In contrast, the drive circuit 100 according to the first embodiment turns on the output from the load output unit 22 for only a short time after power is turned on. When the output of the load output unit 22 is turned on, the charge stored in the capacitor 4 is consumed by the motor 8, and the overshoot is resolved at time T1, which is earlier than time T2. The time for which the output of the load output unit 22 is turned on is the time until the overshoot is resolved, and is set in advance based on the capacitances of the reactor 2 and the capacitor 4 and the impedance of the motor 8, and is stored in the storage means 12 of the processing unit 10.

[0025] As a result, in the drive circuit 100 according to the first embodiment, as shown by the solid line in FIG. 3, after power is turned on, the overshoot is immediately eliminated by temporarily turning on the output of the load output section 22, and the correct voltage can be measured immediately.

[0026] Next, a specific flow of the voltage measurement method for the drive circuit 100 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the operation up to measuring the input voltage of the drive circuit according to the first embodiment. First, after power-on, the output of the load output unit 22 is turned on in step S1, and the process proceeds to step S2.

[0027] In step S2, it is determined whether a preset first time has elapsed. If the first time has elapsed, the process proceeds to step S3. Here, the first time is the time until the overshoot is resolved, and as described above, a value preset based on the capacitances of the reactor 2 and the capacitor 4 and the impedance of the motor 8 is stored in the storage means 12 of the processing unit 10.

[0028] In step S3, the output of the load output unit 22 is turned off, and the process proceeds to step S4.

[0029] In step S4, the bus voltage is measured by the voltage measurement unit 6. At this point, the bus voltage overshoot has been eliminated and the voltage can be measured correctly. Once the bus voltage measurement is complete, the process proceeds to step S5.

[0030] In step S5, the voltage estimation unit 11 estimates the voltage value of the AC power supply 1 based on the voltage value of the bus voltage measured in step S4, and the load drive signal output unit 13 controls the output circuit 7 based on the AC voltage value estimated by the voltage estimation unit 11 so that the output of the motor 8, which is the load connected to the load output unit 22 of the output circuit 7, becomes appropriate, thereby adjusting the load output current.

[0031] As described above, in drive circuit 100 including a rectifier circuit that rectifies AC power supply 1, which is a commercial power supply, reactor 2 for suppressing harmonic current, and voltage measurement unit 6 that measures the rectified voltage, by turning on motor 8 for a short time immediately after power is turned on, it is possible to eliminate overshoot in the rectified voltage and quickly and accurately measure the rectified voltage. Therefore, by using drive circuit 100 according to embodiment 1, it is possible to appropriately control the motor output of motor 8, which is a load, even if the input voltage from AC power supply 1, which is a commercial power supply, changes, and it is possible to obtain an electrical device that operates with the same capacity in response to various commercial power supply voltages.

[0032] Although the first embodiment describes a method of measuring the voltage each time the power is turned on, it is also possible to store the voltage measurement result when the power is first turned on in the storage means 12 provided in the control unit 9, and use the stored measurement result from the next time onwards to control the output circuit 7. By performing such an operation, the time until the device becomes operable can be further reduced.

[0033] Furthermore, in the first embodiment, the reactor 2 is arranged on the AC side, which is the primary side of the diode bridge 3, but the reactor 2 may be arranged on the DC side, which is the secondary side of the diode bridge 3.

[0034] Furthermore, in the first embodiment, the motor 8 is used as an example of a load connected to the output circuit 7 , but the load is not limited to the motor 8 as long as it can be controlled by the output circuit 7 .

[0035] Furthermore, drive circuit 100 shown in the first embodiment can be used with a plurality of commercial power supplies with different voltage values ​​and can be applied to all electrical devices in which it is desired to adjust the load output depending on the difference in the power supply voltage. In particular, it can be effectively applied to a drive circuit for a hand dryer or a vacuum cleaner.

[0036] Fig. 5 is a configuration diagram of a vacuum cleaner including a drive circuit according to embodiment 1. Vacuum cleaner 61 includes drive circuit 100 shown in Fig. 1, electric blower 64 driven by motor 8 shown in Fig. 1, dust collection chamber 65, sensor 68, suction port body 63, extension tube 62, and operation unit 66.

[0037] A user of the vacuum cleaner 61 holds the operating unit 66 and operates the vacuum cleaner 61. The drive circuit 100 of the vacuum cleaner 61 rectifies and converts AC power supplied from the AC power source 1 into DC power to drive the electric blower 64. When the electric blower 64 is driven, dust is sucked in through the suction port body 63, and the sucked dust is collected in the dust collection chamber 65 via the extension tube 62.

[0038] 6 is a configuration diagram of a hand dryer including a drive circuit according to embodiment 1. Hand dryer 90 includes drive circuit 100, casing 91, hand detection sensor 92, water receiving portion 93, drain container 94, cover 96, sensor 97, air intake 98, and electric blower 95. Here, sensor 97 is either a gyro sensor or a human presence sensor. In hand dryer 90, when a hand is inserted into hand insertion portion 99 located above water receiving portion 93, water is blown away by air blown by electric blower 95. The blown-away water is collected in water receiving portion 93 and then stored in drain container 94.

[0039] The configurations shown in the above embodiments are merely examples of the content, and may be combined with other known technologies, and parts of the configurations may be omitted or modified within the scope of the gist.

[0040] REFERENCE SIGNS LIST 1 AC power supply, 2 Reactor, 3 Diode bridge, 4 Capacitor, 5 Bus bar, 6 Voltage measurement unit, 7 Output circuit, 8 Motor, 9 Control unit, 10 Processing unit, 11 Voltage estimation unit, 12 Memory means, 13 Load drive signal output unit, 21 Power supply input unit, 22 Load output unit, 61 Electric vacuum cleaner, 62 Extension tube, 63 Suction port body, 64 Electric blower, 65 Dust collection chamber, 66 Operation unit, 68, 97 Sensor, 81 Processor, 82 Memory, 83 Storage device, 90 Hand dryer, 91 Casing, 92 Hand detection sensor, 93 Water receiving unit, 94 Drain container, 95 Electric blower, 96 Cover, 98 Air intake, 99 Hand insertion unit, 100 Drive circuit.

Claims

1. A drive circuit comprising: a rectifier circuit that rectifies commercial power; a voltage measurement unit that measures the bus voltage after rectification by the rectifier circuit; a reactor that is provided on the input or output side of the rectifier circuit and suppresses harmonic current; an output circuit to which the bus voltage output from the rectifier circuit is input; a load output unit that is provided in the output circuit and outputs a current that drives an externally connected load; and a control unit that adjusts the current output from the load output unit in accordance with the bus voltage measured by the voltage measurement unit, wherein the control unit outputs current from the load output unit for a short period of time after the commercial power is turned on and then stops it, measures the bus voltage with the voltage measurement unit after a preset first time has elapsed, and adjusts and outputs the current of the load output unit provided in the output circuit based on the measured bus voltage.

2. The drive circuit according to claim 1, characterized in that the control unit is provided with a memory means, and the bus voltage measured when commercial power is first turned on is stored in the memory means, and when commercial power is turned on from the next time onwards, the bus voltage stored in the memory means is used to adjust the current output from the load output unit provided in the output circuit.

3. An electrical device incorporating the drive circuit according to claim 1 or 2, characterized in that the electrical device comprises a load connected to the load output section.

4. The electrical device according to claim 3, wherein the load is a DC motor.

5. The electrical device according to claim 4 is a hand dryer or a vacuum cleaner.

6. A drive circuit comprising: a rectifier circuit that rectifies commercial power; a voltage measurement unit that measures the bus voltage after rectification by the rectifier circuit; a reactor that is provided on the input or output side of the rectifier circuit and that suppresses harmonic currents; an output circuit to which the bus voltage output from the rectifier circuit is input; a load output unit that is provided in the output circuit and that outputs a current that drives an externally connected load; and a control unit that adjusts the current output from the load output unit in accordance with the bus voltage measured by the voltage measurement unit, the drive circuit comprising: a step of outputting a current from the load output unit for a short period of time after the commercial power supply is turned on and then stopping it; a step of measuring the bus voltage with the voltage measurement unit after a preset first time has elapsed; and a step of adjusting and outputting the current of the load output unit provided in the output circuit based on the measured bus voltage.

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