Power supply unit and washing machine

Abstract

The goal is to miniaturize the circuit while suppressing harmonic components contained in the power supply current. [Solution] The power supply device 200 includes a rectifier circuit 210 that rectifies the power supply voltage V0 from the AC power supply 600. The rectifier circuit 210 includes a rectifier section 211 connected to the AC power supply 600, a smoothing section 213 which includes a first smoothing capacitor 41 and a second smoothing capacitor 42 and smooths the power supply voltage V0 rectified by the rectifier section 211, and a resonant circuit 212 connected between the rectifier section 211 and the smoothing section 213 and having a resonant frequency determined based on the frequency of the harmonic components contained in the power supply current I0.

Description

Technical Field

[0001] The present disclosure relates to a power supply device for an electrical device.

Background Art

[0002] Techniques for suppressing harmonic components included in an alternating current supplied from an alternating current power supply are known. For example, Patent Document 1 discloses a harmonic current adjustment device including first and second power conversion devices electrically connected to an alternating current power supply via a first electric wire. This harmonic current adjustment device detects a first harmonic current of a predetermined order included in a first current flowing between the first power conversion device and the alternating current power supply, detects a second harmonic current of a predetermined order included in a second current flowing between the second power conversion device and the alternating current power supply, obtains an absolute value of a vector sum of the detected first harmonic current and the detected second harmonic current, and controls a phase adjuster so that the absolute value of the vector sum becomes minimum.

[0003] Patent Document 2 discloses a direct current power supply device including a first rectifying circuit that rectifies an alternating current voltage from an alternating current power supply to charge a smoothing capacitor, a second rectifying circuit that rectifies the alternating current voltage, and a boosting bias circuit connected between the second rectifying circuit and the smoothing capacitor. This direct current power supply device suppresses harmonic components of a power supply current by flowing a sinusoidal bias current in addition to a pulsed current that charges the smoothing capacitor to an alternating current power supply terminal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, while the prior art described in Patent Documents 1 and 2 both attempts to suppress harmonic components contained in the power supply current, further improvements are needed from the standpoint of miniaturizing the circuit.

[0006] This disclosure was made to solve these problems and aims to provide a technology that can suppress harmonic components contained in the power supply current while miniaturizing the circuit. [Means for solving the problem]

[0007] A power supply device in one aspect of the present disclosure is a power supply device for an electrical device, comprising a rectifier circuit for rectifying a power supply voltage from an AC power source, the rectifier circuit comprising a rectifier section connected to the AC power source, a smoothing section including a first smoothing capacitor and a second smoothing capacitor for smoothing the power supply voltage rectified by the rectifier section, and a resonant circuit connected between the rectifier section and the smoothing section, having a resonant frequency determined based on the frequency of harmonic components contained in the power supply current. [Effects of the Invention]

[0008] This configuration allows for miniaturization of the circuit while suppressing harmonic components contained in the power supply current. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view of the washing machine in this embodiment. [Figure 2] This is a circuit diagram of the power supply unit for the washing machine in this embodiment. [Figure 3] This is a waveform diagram of the power supply voltage, power supply current, and harmonic components of the power supply current when the resonant frequency is 250 Hz and the power supply voltage is 50 Hz. [Figure 4] This is a waveform diagram of the power supply voltage, power supply current, and harmonic components of the power supply current when the resonant frequency is 275 Hz and the power supply voltage is 50 Hz. [Figure 5]This is a waveform diagram of the power supply voltage, power supply current, and harmonic components of the power supply current when the resonant frequency is 300 Hz and the power supply voltage is 50 Hz. [Figure 6] This is a waveform diagram of the power supply voltage, power supply current, and harmonic components of the power supply current when the resonant frequency is 250 Hz and the power supply voltage is 60 Hz. [Figure 7] This is a waveform diagram of the power supply voltage, power supply current, and harmonic components of the power supply current when the resonant frequency is 275 Hz and the power supply voltage is 60 Hz. [Figure 8] This is a waveform diagram of the power supply voltage, power supply current, and harmonic components of the power supply current when the resonant frequency is 300 Hz and the power supply voltage is 60 Hz. [Figure 9] This figure shows the waveforms of the harmonic components when the power supply voltage frequency is 50Hz, and the resonant frequencies f0 = 150Hz, 165Hz, and 180Hz. [Figure 10] This figure shows the waveform of the harmonic components when the power supply voltage frequency is 60Hz and the resonant frequencies f0 are set to 150Hz, 165Hz, and 180Hz. [Figure 11] This is a circuit diagram of the power supply unit in modified example 1. [Modes for carrying out the invention]

[0010] (Knowledge forming the basis of this disclosure) Electrical appliances such as washing machines use power supply units that include a rectifier circuit and smoothing capacitor that convert the AC power supply voltage to a DC voltage, and an inverter circuit that converts the DC voltage from the smoothing capacitor back to an AC voltage and supplies it to an AC load. Such power supply units have the problem of excessive harmonic components in the power supply current flowing between the AC power supply and the rectifier circuit. Excessive harmonic components degrade the quality of the grid power supply. Therefore, such power supply units have limits set for each of the multiple harmonic components according to standards (standards of the Japan Electronics and Information Technology Industries Association). Accordingly, power supply units are required to be designed so that each harmonic component contained in the power supply current is below its respective limit.

[0011] If a reactor is provided between the rectifier circuit and the AC power supply, the reactor functions like a low-pass filter and can reduce harmonic components. However, since this reactor is large in size, the circuit scale increases. Therefore, the development of a power supply circuit that does not include a reactor has been under consideration.

[0012] The power conversion device of Patent Document 1 monitors the power supply current, detects a plurality of harmonic components, and has a configuration that varies the phase and voltage of the AC power supply so that the detected harmonic components are adjusted. Thus, although the power conversion device of Patent Document 1 does not have a reactor, a device for adjusting harmonic components is added, resulting in an increase in circuit scale. Specifically, since the power conversion device of Patent Document 1 requires an arithmetic unit for obtaining the vector sum, the circuit scale becomes large. Furthermore, since the power conversion device of Patent Document 1 adjusts harmonic components by the arithmetic operation of the arithmetic unit, its basic technical idea is different from the present disclosure.

[0013] The DC power supply device of Patent Document 2 does not have a reactor, but a boost bias circuit for flowing a sine-shaped bias current is added, resulting in an increase in circuit scale.

[0014] Therefore, the inventor has obtained the knowledge that by using a resonance circuit, the harmonic components included in the power supply current can be suppressed without using a reactor due to the function of the band-pass filter of the resonance circuit, and has arrived at the present disclosure.

[0015] Hereinafter, embodiments of the washing machine will be described in detail with reference to the drawings. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters or duplicate descriptions of substantially the same configuration may be omitted. This is to avoid making the following description overly redundant and to facilitate the understanding of those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0016] (Embodiment) FIG. 1 is a schematic cross-sectional view of the washing machine 100 according to the present embodiment. This washing machine 100 washes and dries items to be processed such as clothes.

[0017] [Overall Structure of Washing Machine] The washing machine 100 includes a housing 110 and a door portion 111. The housing 110 has an inlet through which items to be processed are inserted. The housing 110 has a door portion 111 for opening and closing the inlet. The housing 110 houses internal devices for executing a washing mode, a rinsing mode, a dehydration mode, and a drying mode. In the drying mode, there is a timing when the compressor, the fan 152, and the main motor 124 are all driven, and the power tends to be maximized, and the generation of harmonic components becomes an issue.

[0018] The housing 110 includes a water tank 114 and a rotary drum 115. The rotary drum 115 is provided with a large number of small holes 117 formed in the peripheral wall. The rotary drum 115 houses the items to be processed inserted through the inlet. The water tank 114 stores water in the washing mode and the rinsing mode. The water tank 114 is elastically supported by a suspension mechanism 118 fixed to the bottom wall of the housing 110.

[0019] An inlet port 120 is provided at the upper part of the peripheral wall of the water tank 114. The inlet port 120 supplies water to the water tank 114 in the washing mode and the rinsing mode. A drain port 121 is provided at the lower part of the peripheral wall of the water tank 114. The drain port 121 drains the water used for washing and rinsing.

[0020] An exhaust port 122 is formed at the upper part of the peripheral wall of the water tank 114. The exhaust port 122 exhausts the air for drying the items to be processed from the water tank 114 in the drying mode. An air supply port 123 is formed in the rear end wall of the water tank 114. The air supply port 123 allows the air exhausted from the exhaust port 122 to flow into the processing chamber 112 in the drying mode.

[0021] A main motor 124 for rotationally driving the rotary drum 115 is attached to the outer surface of the rear end wall of the water tank 114.

[0022] A water supply unit 125 is provided above the water tank 114. The water supply unit 125 supplies water to the processing chamber 112. The upstream end of the water supply unit 125 is exposed on the outer surface of the housing 110 and is connected to a hose (not shown) extending from a water tap.

[0023] A drainage path 129 is provided on the underside of the tank 114. The drainage path 129 drains the water from the tank 114.

[0024] A circulating air passage 131 is provided on the outside of the water tank 114. The circulating air passage 131 is connected between the air intake 123 and the exhaust 122. A fan 152 is positioned inside the circulating air passage 131. The fan 152 draws air from the processing chamber 112 through the exhaust 122 and returns the drawn-out air to the processing chamber 112 through the air intake 123.

[0025] A dehumidifying unit 156 and an adsorbent material 139 are arranged within the circulating air passage 131. The dehumidifying unit 156 and the adsorbent material 139 remove moisture from the air flowing through the circulating air passage 131.

[0026] A heating unit 153 is located downstream of the dehumidifying unit 156. The dehumidifying unit 156 and the heating unit 153 constitute a heat pump device. The dehumidifying unit 156 includes an expansion valve for expanding the refrigerant and fins that are cooled by the expanded refrigerant. The heating unit 153 includes a compressor for compressing the refrigerant and fins that are heated by the compressed refrigerant.

[0027] [Circuit Configuration] Figure 2 is a circuit diagram of the power supply unit 200 of the washing machine 100 in this embodiment. The power supply unit 200 includes a rectifier circuit 210, a smoothing circuit 220, and an inverter circuit 230.

[0028] The rectifier circuit 210 rectifies the power supply voltage V0 from the AC power supply 600. The AC power supply 600 is a grid power supply.

[0029] The smoothing circuit 220 includes a smoothing capacitor 43. The smoothing capacitor 43 further smooths the power supply voltage V0 rectified by the smoothing unit 213 to generate a DC voltage V1.

[0030] The inverter circuit 230 consists of a three-phase inverter and drives the motor 500 under the control of the control circuit 400.

[0031] The rectifier circuit 210 includes a rectifier section 211, a resonant circuit 212, and a smoothing section 213.

[0032] The rectifier unit 211 is connected to the AC power supply 600. The rectifier unit 211 consists of a full-wave rectifier circuit in which four diodes 11, 12, 13, and 14 are connected in a full bridge configuration. Specifically, the connection point of diodes 11 and 12 is connected to the AC power supply 600 via a second power input terminal 62. The connection point of diodes 13 and 14 is connected to the AC power supply 600 via a first power input terminal 61.

[0033] The resonant circuit 212 is connected between the rectifier 211 and the smoothing 213. The resonant circuit 212 includes a resonant coil 31 and a resonant capacitor 32. The resonant coil 31 and the resonant capacitor 32 are connected in parallel. The first end of the resonant circuit 212 is connected to the AC power supply 600 via the first power input terminal 61. The second end of the resonant circuit 212 is connected to connection point 65. Connection point 65 is the connection point between the first smoothing capacitor 41 and the second smoothing capacitor 42.

[0034] The resonant circuit 212 has a resonant frequency f0 determined based on the frequencies of the harmonic components contained in the power supply current I0. More specifically, the resonant frequency f0 may be an intermediate frequency between the frequency f1 of the kth harmonic component of the power supply current having a first frequency (e.g., 50 Hz) and the frequency f2 of the kth harmonic component of the power supply current having a second frequency (e.g., 60 Hz). The intermediate frequency may be the average of frequencies f1 and f2, or a frequency within a predetermined range centered on the average value.

[0035] Alternatively, the resonant frequency f0 may be the frequency of the k-th harmonic component of the power supply current I0. An example of k is a natural number or an odd number such as 3, 5, or 7.

[0036] The smoothing section 213 includes a first smoothing capacitor 41 and a second smoothing capacitor 42, and smooths the voltage from the resonant circuit 212. The first smoothing capacitor 41 and the second smoothing capacitor 42 are made of, for example, electrolytic capacitors.

[0037] In the first smoothing capacitor 41, the end opposite to the connection point 65 is connected to the first rectifier output terminal 63. In the second smoothing capacitor 42, the end opposite to the connection point 65 is connected to the second rectifier output terminal 64.

[0038] The smoothing capacitor 43 is connected between the first rectified output terminal 63 and the second rectified output terminal 64. The smoothing capacitor 43 is made of, for example, an electrolytic capacitor. The smoothing capacitor 43 smooths the voltage output from the smoothing unit 213. As a result, a DC voltage V1 is generated across the smoothing capacitor 43.

[0039] The inverter circuit 230 includes six switching elements 51 to 56. The connection point of switching element 51 and switching element 52 is connected to the motor 500 via a first AC output terminal 71. The connection point of switching element 53 and switching element 54 is connected to the motor 500 via a second AC output terminal 72. The connection point of switching element 55 and switching element 56 is connected to the motor 500 via a third AC output terminal 73. The collectors of switching elements 51, 53, and 55 are connected to a first rectifier output terminal 63. The emitters of switching elements 52, 54, and 56 are connected to a second rectifier output terminal 64. Switching elements 51 and 52 constitute a U-phase leg, switching elements 53 and 54 constitute a V-phase leg, and switching elements 55 and 56 constitute a W-phase leg.

[0040] The switching elements 51 to 56 are composed of, for example, IGBTs (Insulated Gate Bipolar Transistors). However, this is just one example, and the switching elements 51 to 56 may also be composed of MOSFETs (metal-oxide-semiconductor field-effect transistors). Each of the switching elements 51 to 56 is connected to a reverse-flow diode. Reverse direction means the opposite direction to the forward direction, where the forward direction is defined as the direction in which current flows from the collector to the emitter.

[0041] The control circuit 400 is composed of, for example, a microcontroller. The control circuit 400 generates gate signals UH, UL, VH, VL, WH, and WL so that the rotational speed of the motor 500 reaches a target value, and inputs the generated gate signals UH, UL, VH, VL, WH, and WL to the gates of the switching elements 51 to 56, respectively. In this way, the control circuit 400 controls the inverter circuit 230 using PWM (Pulse Width Modulation). The gate signals UH, UL, VH, VW, WH, and WL are PWM signals.

[0042] Motor 500 is a three-phase motor. Motor 500 is a fan motor that drives the main motor 124, fan 152, or heat pump motor that drives the compressor of the heating unit 153, etc.

[0043] [Operation] Figure 3 shows the waveforms of the power supply voltage V0, power supply current I0, and the harmonic components of the power supply current I0 when the resonant frequency f0 is 250 Hz and the power supply voltage V0 is 50 Hz. The power supply current I0 flows when the smoothing capacitor 43 is charged. When the polarity of the power supply voltage V0 is positive, the power supply current I0 has a positive polarity, and when the polarity of the power supply voltage V0 is negative, the power supply current has a negative polarity. The resonant frequency f0 = 250 Hz is five times the frequency of the power supply voltage V0. Therefore, the resonant frequency f0 has the frequency of the fifth harmonic component of the power supply current I0. Consequently, the impedance of the resonant circuit 212 is high at the frequency of the fifth harmonic component. As a result, the resonant circuit 212 can suppress the fifth harmonic component to almost zero, as shown in the lower harmonic component waveform diagram.

[0044] Figure 4 shows the waveforms of the power supply voltage V0, power supply current I0, and the harmonic components of the power supply voltage V0 when the resonant frequency f0 is 275 Hz and the power supply voltage V0 is 50 Hz. The resonant frequency f0 = 275 Hz is the average value of f1 (= 250 Hz), which is five times the frequency of the 50 Hz power supply voltage V0, and f2 (= 300 Hz), which is five times the frequency of the 60 Hz power supply voltage V0. Therefore, the resonant circuit 212 can suppress both the fifth harmonic component of the 50 Hz power supply voltage V0 and the fifth harmonic component of the 60 Hz power supply voltage V0. In the example of the harmonic component waveforms in the lower panel, the fifth harmonic component of the 50 Hz power supply current I0 is suppressed.

[0045] Figure 5 shows the waveforms of the power supply voltage V0, power supply current I0, and the harmonic components of the power supply current I0 when the resonant frequency f0 is 300 Hz and the power supply voltage V0 is 50 Hz. The resonant frequency f0 = 300 Hz is five times the frequency of the 60 Hz power supply voltage V0 (= 300 Hz), and not five times the frequency of the 50 Hz power supply voltage V0. Therefore, as shown in the lower harmonic component waveform diagram, the resonant circuit 212 is unable to suppress the fifth harmonic component of the 50 Hz power supply current I0.

[0046] Based on the above, when the power supply voltage V0 is 50Hz, the resonant circuit 212 can suppress the fifth harmonic component to almost zero by setting the resonant frequency f0 to 250Hz. When the power supply voltage V0 is 50Hz, the resonant circuit 212 cannot suppress the fifth harmonic component even when the resonant frequency f0 is set to 300Hz. On the other hand, when the resonant frequency f0 is set to 275Hz, the fifth harmonic component can be suppressed when the power supply voltage is 50Hz and when the power supply voltage is 60Hz.

[0047] Figure 6 shows the waveforms of the power supply voltage V0, power supply current I0, and the harmonic components of the power supply voltage V0 when the resonant frequency f0 is 250 Hz and the power supply voltage V0 is 60 Hz. The resonant frequency f0 = 250 Hz is five times the frequency of the power supply voltage V0 at 50 Hz (= 250 Hz), and not five times the frequency of the power supply voltage V0 at 60 Hz. Therefore, as shown in the lower harmonic component waveform, the resonant circuit 212 is unable to suppress the fifth harmonic component of the 60 Hz power supply current I0.

[0048] Figure 7 shows the waveforms of the power supply voltage V0, power supply current I0, and the harmonic components of the power supply voltage V0 when the resonant frequency f0 is 275 Hz and the power supply voltage V0 is 60 Hz. The resonant frequency f0 = 275 Hz is the average of the frequency f1 (= 250 Hz), which is five times the power supply voltage V0 at 50 Hz, and the frequency f2 (= 300 Hz), which is five times the power supply voltage V0 at 60 Hz. Therefore, the resonant circuit 212 can suppress both the fifth harmonic component of the power supply voltage V0 at 50 Hz and the fifth harmonic component of the power supply voltage V0 at 60 Hz. In the example of the harmonic component waveforms in the lower panel, the fifth harmonic component of the power supply current I0 at 60 Hz is suppressed.

[0049] Figure 8 shows the waveforms of the power supply voltage V0, power supply current I0, and the harmonic components of the power supply current I0 when the resonant frequency f0 is 300 Hz and the power supply voltage V0 is 60 Hz. The resonant frequency f0 = 300 Hz is five times the frequency of the power supply voltage V0 at 60 Hz. Therefore, as shown in the lower harmonic component waveform diagram, the resonant circuit 212 can suppress the fifth harmonic component of the 60 Hz power supply current I0 to almost zero.

[0050] Figure 9 shows the waveforms 801, 802, and 803 of the harmonic components when the power supply voltage V0 frequency is 50 Hz and the resonant frequencies f0 = 150 Hz, 165 Hz, and 180 Hz.

[0051] The resonant frequency f0 = 150Hz is three times the frequency of the 50Hz power supply voltage V0. Therefore, as shown in waveform 801, the third harmonic component is suppressed to almost zero. The resonant frequency f0 = 165Hz is the average of the third harmonic frequency f1 (=150Hz) of the 50Hz power supply voltage V0 and the third harmonic frequency f2 (=180Hz) of the 60Hz power supply voltage V0. Therefore, as shown in waveform 802, the third harmonic component of the 50Hz power supply current I0 is suppressed. The resonant frequency f0 = 180Hz is not three times the frequency of the 50Hz power supply voltage V0 (=150Hz). Therefore, as shown in waveform 803, the third harmonic component of the 50Hz power supply voltage V0 is not suppressed.

[0052] Figure 10 shows the waveforms 801, 802, and 803 of the harmonic components when the power supply voltage V0 frequency is 60 Hz and the resonant frequencies f0 = 150 Hz, 165 Hz, and 180 Hz.

[0053] Referring to Figure 10, the resonant frequency f0 = 180 Hz is three times the frequency of the 60 Hz power supply voltage V0. Therefore, as shown in waveform 803, the third harmonic component of the 60 Hz power supply current I0 is suppressed to almost zero. The resonant frequency f0 = 165 Hz is the average of the third harmonic frequency f1 (= 150 Hz) of the 50 Hz power supply voltage V0 and the third harmonic frequency f2 (= 180 Hz) of the 60 Hz power supply voltage V0. Therefore, as shown in waveform 802, the third harmonic component of the 60 Hz power supply current I0 is suppressed. The resonant frequency f0 = 150 Hz is not three times the frequency of the power supply voltage V0, which is 60 Hz (= 180 Hz). Therefore, as shown in waveform 801, the third harmonic component is not suppressed.

[0054] [Effects, etc.] The resonant circuit 212 increases impedance in the frequency band centered around the resonant frequency f0, thus functioning as a bandpass filter to suppress AC current in this frequency band. The power supply unit 200 has a resonant circuit 212 connected between the rectifier unit 211 and the smoothing unit 213. This resonant circuit 212 has a resonant frequency f0 determined based on the frequency of the harmonic components contained in the power supply current I0. Therefore, the power supply unit 200 can suppress the harmonic components contained in the power supply current I0 without using a reactor. As a result, the power supply unit 200 can suppress harmonic components while miniaturizing the circuit.

[0055] The power supply unit 200 has a resonant frequency f0 that is midway between the frequency of the kth harmonic component of a power supply current I0 with a first frequency and the frequency of the kth harmonic component of a power supply current with a second frequency. Therefore, the kth harmonic component can be suppressed regardless of whether the grid power supply is of the first or second frequency.

[0056] Since the power supply unit 200 has a resonant frequency that corresponds to the frequency of the k-th harmonic component of the power supply current, it can suppress the k-th harmonic component.

[0057] Since the resonant circuit 212 of the power supply unit 200 is composed of an LC circuit, the resonant circuit can be easily constructed using widely available LC circuits.

[0058] The following modifications may be adopted for this disclosure.

[0059] (Variation 1) Figure 11 is a circuit diagram of the power supply unit 200A in Modification 1. Components identical to those in the power supply unit 200 in Modification 1 are denoted by the same reference numerals and their descriptions are omitted. The power supply unit 200A has a rectifier section 211A composed of a half-wave rectifier circuit. The rectifier section 211A includes diodes 11 and 12 connected in a half-bridge configuration. The first end of the resonant circuit 212 is connected to 600 via the first power supply input terminal 61.

[0060] According to the power supply unit 200A, even if the rectifier section 211A is configured as a half-wave rectifier circuit, harmonic components can be suppressed.

[0061] (Modification 2) The electrical appliance is not limited to the washing machine 100; it may be any other electrical appliance. Other examples of electrical appliances include dishwashers, air conditioners, and refrigerators.

[0062] (Variation 3) The power supply unit 200 may be provided with multiple resonant circuits 212 with different resonant frequencies. For example, the power supply unit 200 may include a resonant circuit 212 whose resonant frequency is the frequency of the k-th harmonic component and a resonant circuit 212 whose resonant frequency is the frequency of the (k+1)th harmonic component. Alternatively, the power supply unit 200 may include a resonant circuit 212 whose resonant frequency is the average value of the frequency of the k-th harmonic component of the first frequency and the frequency of the k-th harmonic component of the second frequency, and a resonant circuit 212 whose resonant frequency is the average value of the frequency of the (k+1)th harmonic component of the first frequency and the frequency of the (k+1)th harmonic component of the second frequency.

[0063] (Technology 1) A power supply device in one aspect of the present disclosure is a power supply device for an electrical device, comprising a rectifier circuit for rectifying a power supply voltage from an AC power source, the rectifier circuit comprising a rectifier section connected to the AC power source, a smoothing section including a first smoothing capacitor and a second smoothing capacitor for smoothing the power supply voltage rectified by the rectifier section, and a resonant circuit connected between the rectifier section and the smoothing section, having a resonant frequency determined based on the frequency of harmonic components contained in the power supply current.

[0064] A resonant circuit increases impedance in the frequency band centered around its resonant frequency, thus functioning as a bandpass filter to suppress AC current in this frequency band. This power supply unit has a resonant circuit connected between the rectifier and smoothing sections. This resonant circuit has a resonant frequency determined based on the frequencies of harmonic components contained in the power supply current. Therefore, this power supply unit can suppress harmonic components contained in the power supply current without using a reactor. As a result, this power supply unit can suppress harmonic components while miniaturizing the circuit.

[0065] Although this power supply unit incorporates a resonant circuit instead of a reactor, the reactor, which is used to reduce harmonic components, is significantly larger than the resonant circuit. Therefore, this power supply unit can be made significantly smaller in circuit size compared to a power supply unit with a reactor.

[0066] Furthermore, the calculator used in Patent Document 1 for adjusting harmonic components has a more complex circuit configuration compared to a resonant circuit, increasing the circuit size and cost. The boost bias circuit shown in Patent Document 2 has a DC bias power supply for supplying a DC voltage lower than the maximum charging voltage of the smoothing capacitor, and an impedance including inductance and resistance connected in series with the DC bias power supply, thus increasing the circuit size compared to a resonant circuit.

[0067] (Technology 2) In the power supply device described in Technical 1, the resonant frequency may be an intermediate frequency between the frequency of the k-th harmonic component of the power supply current having a first frequency and the frequency of the k-th harmonic component of the power supply current having a second frequency.

[0068] This power supply unit has a resonant frequency that is midway between the frequency of the kth harmonic component of a power supply current with a first frequency and the frequency of the kth harmonic component of a power supply current with a second frequency. Therefore, it can suppress the kth harmonic component regardless of whether the grid power supply is of the first or second frequency.

[0069] (Technology 3) In the power supply device described in Technology 1 or 2, the resonant frequency may be the frequency of the k-th harmonic component of the power supply current.

[0070] This power supply unit has a resonant frequency that corresponds to the frequency of the k-th harmonic component of the power supply current, and therefore can suppress the k-th harmonic component.

[0071] (Technology 4) In the power supply device described in any one of Technical 1 to 3, the resonant circuit may be an LC circuit.

[0072] Since this power supply unit has a resonant circuit composed of an LC circuit, the resonant circuit can be easily constructed using widely available LC circuits.

[0073] (Technology 5) A washing machine in another aspect of this disclosure comprises a power supply device as described in any one of the technologies 1 to 4. [Industrial applicability]

[0074] This disclosure can suppress harmonic components and is therefore applicable to electrical equipment connected to grid power. [Explanation of symbols]

[0075] 11-14: Diode 31: Resonant coil 32: Resonant Capacitor 41: First smoothing capacitor 42: Second smoothing capacitor 43: Smoothing Capacitor 51-56: Switching elements 61: First power input terminal 62: Second power input terminal 63: 1st rectifier output end 64:Second rectifier output end 65: Connection point 100: Washing machine 200, 200A: Power supply 210: Rectifier circuit 211, 211A: Rectifier 212: Resonant circuit 213: Smooth section 220: Smoothing circuit 230: Inverter Circuit 400: Control circuit 600: AC power supply

Claims

1. A power supply unit for electrical equipment, It is equipped with a rectifier circuit that rectifies the power supply voltage from the AC power supply, The rectifier circuit described above is A rectifier connected to the aforementioned AC power supply, A smoothing unit including a first smoothing capacitor and a second smoothing capacitor, which smooths the power supply voltage rectified by the rectifier unit, The system comprises a resonant circuit connected between the rectifier and the smoothing section, having a resonant frequency determined based on the frequency of harmonic components contained in the power supply current, power supply.

2. The aforementioned resonant frequency is the frequency midway between the frequency of the k-th harmonic component of the power supply current having a first frequency and the frequency of the k-th harmonic component of the power supply current having a second frequency. The power supply device according to claim 1.

3. The aforementioned resonant frequency has the frequency of the k-th harmonic component of the power supply current. The power supply device according to claim 1.

4. The aforementioned resonant circuit is an LC circuit. A power supply device according to any one of claims 1 to 3.

5. A washing machine comprising a power supply device according to any one of claims 1 to 3.

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