Power converters, air conditioners, and refrigeration units.

Abstract

DEPCT67 The power converter kit includes: A converter designed to transform AC power fed from a power source. AC power is converted into DC power using a pair of primarily conductive wires; An inverter, which is designed to convert the DC power sent from the converter to... A pair of wires with a second conductor is used to provide AC power; and A capacitor which is connected between the conductive wires of a pair of conductive wires or between... A wire with a conductive second conductor. Where the carrier wave frequency for driving the inverting motor is set to fc, the allowed frequency is... The resonance of an LC filter circuit consisting of one or more reactors and a... The capacitor is set to fLC, and the maximum value of the inverter's output frequency is set to MAX(f0)MAX(f0). It will then be according to MAX(f0)6 times.

Description

Power conversion devices, air conditioners, and refrigeration devices

[0001] The present disclosure relates to a power conversion device, an air conditioner, and a refrigeration device.

[0002] Conventionally, in order to satisfy power supply harmonic standards, a power conversion device is known in which the resonant frequency of an LC filter is set to a frequency band greater than 40 times the power supply frequency, for which no power supply harmonic standards exist (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2005-253282

[0004] However, even if the resonant frequency of the LC filter is set to more than 40 times the power supply frequency, if harmonic components near the resonant frequency appear in the reactor or capacitor, the signal may be excessively amplified in accordance with the frequency characteristics of the LC filter.

[0005] The present disclosure provides a power conversion device capable of suppressing amplification of harmonic components by an LC filter, and an air conditioner equipped with the power conversion device.

[0006] The present disclosure provides a power conversion device including: a converter that converts AC power input from an AC power source via a first pair of wires into DC power; an inverter that converts DC power output from the converter to a second pair of wires into AC power; and a capacitor connected between the first pair of wires or the second pair of wires, wherein the inductance of an inductance component from a point where the power conversion device is connected to the AC power source to the capacitor is L, and the maximum value of the output frequency of the inverter is MAX(f ０ ), the capacitance C of the capacitor is

[0007] To provide a power conversion device that satisfies the above.

[0008] This makes it possible to suppress amplification of harmonic components by the LC filter.

[0009] In the above power conversion device, the carrier frequency for driving the inverter is set to f ｃ When the inductance component and the capacitor are used as the LC filter, the carrier frequency f ｃThe gain at may be 0.1 or less.

[0010] As a result, the carrier frequency f ｃ Since the gain at this frequency is −20 dB (0.1 times) or less, the LC filter can suppress harmonic components in the carrier frequency band.

[0011] In the above power conversion device, 6×the MAX(f ０ ) may have a gain of 5 or less.

[0012] This results in a resonant frequency f ＬＣ Therefore, the effect of suppressing the amplification of harmonic components in the low frequency range by the LC filter is enhanced.

[0013] In the above-described power conversion device, the inductance component may include a reactor inserted in series in one or both of the first pair of wires or in one or both of the second pair of wires, and the capacitor may be connected between the first pair of wires or the second pair of wires between the reactor and the inverter.

[0014] This makes it possible to suppress amplification of harmonic components due to the LC filter formed by the reactor and the capacitor.

[0015] The present disclosure provides a power supply comprising: a converter that converts AC power input from an AC power source via a first pair of wires into DC power; an inverter that converts DC power output from the converter to a second pair of wires into AC power; a reactor inserted in series in one or both of the wires of the first pair of wires or one or both of the wires of the second pair of wires; and a capacitor connected between the reactor and the inverter and between the first pair of wires or the second pair of wires, wherein a carrier frequency for driving the inverter is set to f ｃ The resonant frequency of the LC filter formed by the reactor and the capacitor is f ＬＣ , the maximum value of the output frequency of the inverter is MAX(f ０ ), then MAX(f ０ )teeth,

[0016] To provide a power conversion device that satisfies the above.

[0017] This makes it possible to suppress amplification of harmonic components by the LC filter.

[0018] In the above power conversion device, the carrier frequency f ｃ The gain of the LC filter at may be 0.1 or less.

[0019] This results in a carrier frequency f ｃ Since the gain of the LC filter at this point is −20 dB (0.1 times) or less, the LC filter can suppress harmonic components in the carrier frequency band.

[0020] In the above power conversion device, 6×the MAX(f ０ ) the gain of the LC filter may be 5 or less.

[0021] This results in a resonant frequency f ＬＣ Therefore, the effect of suppressing the amplification of harmonic components in the low frequency range by the LC filter is enhanced.

[0022] In the above power conversion device, the reactor may be a component mounted on a substrate.

[0023] The capacitance C satisfies Equation 2 or MAX(f ０ ) satisfies Equation 1, so that the carrier frequency f ｃ is set to a relatively large value. ｃ The larger the inductance, the smaller the reactor's inductance, making it possible to reduce the reactor's size. A smaller reactor makes it easier to mount the reactor on a circuit board. Therefore, even if the reactor is more likely to generate heat due to the smaller inductance, the temperature rise of the reactor can be suppressed by dissipating the heat to the circuit board.

[0024] In the above power conversion device, the capacitor may be connected between the second pair of wires.

[0025] This makes it possible to suppress amplification of harmonic components by an LC filter including the capacitor connected between the second pair of wires. Also, the capacitor connected between the second pair of wires can absorb surge voltages caused by switching of the inverter.

[0026] In the above power conversion device, the MAX(f ０ ) may be 600 Hz.

[0027] This results in a resonant frequency f ＬＣ Since the frequency of the LC filter is greater than 3.6 kHz (= 6 × 600 Hz), the amplification of harmonic components with frequencies lower than 3.6 kHz by the LC filter can be suppressed. In particular, since 600 Hz is the upper limit of the output frequency under the list regulation, the list regulation can be satisfied.

[0028] In the above power conversion device, the switching element configured in the inverter may be a wide bandgap semiconductor device.

[0029] By applying a wide band gap semiconductor to a switching element, the effect of reducing loss in the switching element is enhanced.

[0030] The present disclosure provides an air conditioner including the above-described power conversion device.

[0031] This makes it possible to realize an air conditioner that can suppress amplification of harmonic components by the LC filter.

[0032] The present disclosure provides a refrigeration device including the above-described power conversion device.

[0033] This makes it possible to realize a refrigeration device that can suppress amplification of harmonic components by the LC filter.

[0034] 12 is a diagram showing a first configuration example of a power conversion device. FIG. 13 is a diagram showing a second configuration example of a power conversion device. FIG. 14 is a diagram showing an example of the transfer characteristics of an LC filter. FIG. 15 is a diagram showing an example of the setting range of the resonant frequency of an LC filter. FIG. 16 is a cross-sectional view partially showing an example configuration of an electrical unit including a power conversion device. FIG. 17 is a diagram showing simulation waveforms of each part according to an embodiment. FIG. 18 is a diagram showing simulation waveforms of each part according to a comparative example. FIG. 19 is a diagram showing the results of frequency analysis of the simulation waveforms of each part according to an embodiment. FIG. 20 is a diagram showing the results of frequency analysis of the simulation waveforms of each part according to a comparative example. FIG. 21 is a diagram showing the conditions used in the simulations of FIGS. 6 to 9. FIG. 22 is a diagram showing the conditions used in the simulations of FIGS. 10 to 13.

[0035] An embodiment will be described below.

[0036] Fig. 1 is a diagram showing a first configuration example of a power conversion device to which the technology of the present disclosure is applied. The power conversion device 1A shown in Fig. 1 includes a converter circuit 2, a DC link unit 3, an inverter circuit 4, and a control unit 5, and converts input AC power supplied from a three-phase AC power source 6 into output AC power of a predetermined voltage and a predetermined frequency, and supplies the output AC power to a motor 7.

[0037] The power conversion device 1A is provided, for example, in an air conditioner 101 that conditions the air in a target space. The device in which the power conversion device 1A is installed is not limited to an air conditioner, and may be other devices that require a power conversion function. The air conditioner 101 is an example of a refrigeration device (refrigeration cycle device) that includes a compressor driven by a motor 7.

[0038] The motor 7 is, for example, a three-phase AC motor. Specific examples of the motor 7 include an electric motor that drives a compressor provided in the refrigerant circuit of the air conditioner 101. The motor 7 is, for example, a concentrated winding motor such as a 4-pole, 6-slot or 6-pole, 9-slot motor. In this motor 7, the harmonic components of the induced voltage tend to include many 5th and 7th order components of the fundamental wave. Higher order (e.g., 6th order) harmonic components caused by this motor voltage distortion (5th and 7th order harmonic components of the fundamental wave) may appear in the input power of the motor 7 and on the input side of the inverter circuit 4. These higher order harmonic components are generated by the power supply current i of the AC power supply 6. ｉｎ , the DC link voltage v in the DC link section 3 ｄｃ , reactor voltage v across reactor 8 Ｌ , the reactor current i flowing through the reactor 8 Ｌ , or the DC current i flowing through the DC link section 3 ｄｃ It may appear in.

[0039] The converter circuit 2 is an example of a converter that converts three-phase AC input from the AC power supply 6 via a plurality of wires 61, 62, and 63 into DC. In the example shown in Fig. 1 , the three-phase AC supplied from the AC power supply 6 is input to an input section of the converter circuit 2 via three wires 61, 62, and 63 (three wire pairs including the wire pair 61, 62, the wire pair 62, 63, and the wire pair 61, 63). At least one wire pair out of the three wire pairs including the wire pair 61, 62, the wire pair 62, 63, and the wire pair 61, 63 is an example of a first wire pair between the AC power supply 6 and the converter circuit 2.

[0040] The converter circuit 2 is connected to an AC power supply 6 and converts the AC output from the AC power supply 6 into DC. The converter circuit 2 is, for example, a diode bridge circuit in which a plurality of diodes (six in this example) are connected in a bridge configuration. These diodes full-wave rectify the AC voltage of the AC power supply 6 and convert it into a DC voltage. The converter circuit 2 may be a voltage conversion circuit of a circuit type other than a diode bridge, as long as it supplies the converted DC power to the inverter circuit 4 via the DC link unit 3.

[0041] The DC link unit 3 includes a capacitor 3a connected between the converter circuit 2 and the inverter circuit 4. The capacitor 3a is connected in parallel to the output of the converter circuit 2, and a DC voltage (DC link voltage v ｄｃ ) is input to the input node of the inverter circuit 4. The capacitor 3a is connected between the pair of wires 31 and 32. Of the pair of wires 31 and 32, the pair of wires 31 is a positive bus bar, and the other pair of wires 32 is a negative bus bar. The pair of wires 31 and 32 is an example of a second pair of wires.

[0042] The DC link unit 3 includes a reactor 8 connected between the converter circuit 2 and the inverter circuit 4. The reactor 8 is inserted in series in a DC bus between the output part of the converter circuit 2 and the input part of the inverter circuit 4. In the example shown in FIG. 1 , the reactor 8 is inserted in series in one wire 31 of a pair of wires 31 and 32 that are a pair of DC buses. The reactor 8 may be inserted in series in the wire 32, or in both of the pair of wires 31 and 32. The reactor 8 may also be inserted in series in all of the wires 61, 62, and 63.

[0043] The wiring 32 refers to a path through which a current flows, and is not limited to a simple conductor. For example, the wiring 32 may be a grounded conductive part or a heat sink for dissipating heat from the inverter circuit 4.

[0044] The inverter circuit 4 is an example of an inverter that converts the DC power output from the converter circuit 2 to the pair of wirings 31 and 32 into AC power.

[0045] The inverter circuit 4 has an input node connected in parallel to the capacitor 3a of the DC link unit 3, and switches the output of the DC link unit 3 to convert it into three-phase AC and supply it to the connected motor 7. In this embodiment, the inverter circuit 4 is configured with a plurality of switching elements 4a connected in a bridge connection. Since the inverter circuit 4 outputs three-phase AC to the motor 7, it has six switching elements. More specifically, the inverter circuit 4 has three switching legs connected in parallel, and each switching leg has two switching elements connected in series. In each switching leg, the midpoint between the upper arm switching element and the lower arm switching element is connected to the coil of each phase of the motor 7. In addition, a freewheeling diode is connected in anti-parallel to each switching element. The inverter circuit 4 converts the DC link voltage v input from the DC link unit 3 into a DC link voltage v , by the on / off operation of these switching elements. ｄｃ is switched to convert it into a three-phase AC voltage and supplied to the motor 7. The control unit 5 controls this on / off operation.

[0046] The switching element 4a is made of silicon carbide (SiC), gallium nitride (GaN), or Ga ２ O ３ Preferably, the switching element is a device containing a wide bandgap semiconductor such as gallium oxide (gallium oxide) or diamond. Applying a wide bandgap semiconductor to the switching element enhances the effect of reducing loss in the switching element. The switching element may be an element containing a semiconductor such as silicon (Si). Similarly, applying an element containing a wide bandgap semiconductor to a diode connected in anti-parallel to the switching element 4a enhances the effect of reducing loss in the diode. The diode may be an element containing a semiconductor such as silicon (Si). Similarly, the switching element may be a unipolar transistor containing a wide bandgap semiconductor. In this case, by using the body diode of the unipolar transistor as a freewheeling diode, it is not necessary to provide a diode connected in anti-parallel.

[0047] The control unit 5 controls the switching (on / off operation) of the inverter circuit 4. The control unit 5 is, for example, a control circuit including a processor such as a CPU (Central Processing Unit) and a memory. The functions of the control unit 5 may be realized by the processor operating according to a program readably stored in the memory. The functions of the control unit 5 may also be realized by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0048] 2 is a diagram showing a second configuration example of a power conversion device to which the technology of the present disclosure is applied. The description of the same configuration as in the first configuration example will be omitted by referencing the above description. The power conversion device 1B shown in FIG. 2 includes a converter circuit 2, a DC link unit 3, an inverter circuit 4, and a control unit 5, and converts input AC power supplied from a single-phase AC power source 6 into output AC power of a predetermined voltage and a predetermined frequency, and supplies the output AC power to a motor 7.

[0049] The converter circuit 2 is an example of a converter that converts single-phase AC input from the AC power supply 6 via a plurality of wires 64, 65 into DC. In the example shown in Fig. 2 , the single-phase AC supplied from the AC power supply 6 is input to the input section of the converter circuit 2 via two wires 64, 65 (one wire pair 64, 65).

[0050] The converter circuit 2 is connected to the AC power supply 6 via a reactor 8 and rectifies (converts) the AC output from the AC power supply 6 into DC. The converter circuit 2 is, for example, a diode bridge circuit in which a plurality of diodes (four in this example) are connected in a bridge configuration. These diodes full-wave rectify the AC voltage of the AC power supply 6 and convert it into a DC voltage. The converter circuit 2 may be a voltage conversion circuit of a circuit type other than a diode bridge, as long as it supplies the converted DC power to the inverter circuit 4 via the DC link unit 3.

[0051] The reactor 8 is connected between the AC power supply 6 and the converter circuit 2, and more specifically, is inserted in series between the AC output side of the AC power supply 6 and the AC input side of the converter circuit 2. In the example shown in Fig. 2 , the reactor 8 is inserted in series in one wire 64 of the wire pair 64, 65. The reactor 8 may be inserted in series in the wire 65, or in both wire pairs 64, 65. The reactor 8 may be inserted in series in one or both of the wire pairs 31, 32.

[0052] 1 and 2, the capacitance value of the capacitor 3a is such that it can hardly smooth the output of the converter circuit 2, while it can suppress the ripple voltage (switching frequency f ｃ Specifically, the capacitor 3a is configured as a small-capacity capacitor (for example, a film capacitor) having a capacitance value (for example, on the order of several tens to several hundreds of μF) that is approximately 0.01 times the capacitance value of a smoothing capacitor (for example, an electrolytic capacitor) used to smooth the output of the converter circuit 2 in a general power conversion device.

[0053] Since the capacitance value of the capacitor 3a is so small, the output of the converter circuit 2 is hardly smoothed in the DC link unit 3, and as a result, the power supply voltage v of the AC power supply 6 ｉｎ The pulsating component corresponding to the frequency of the DC voltage (DC link voltage v ｄｃ ) remains. For example, the DC link voltage v ｄｃ In the case of the three-phase AC power supply 6 of FIG. ｉｎ In the case of the single-phase AC power supply 6 of FIG. 2, the power supply voltage v ｉｎ It has a pulsating component with a frequency twice that of the frequency of the

[0054] In FIGS. 1 and 2, the reactor 8 and the capacitor 3a form an LC filter.

[0055] In the example shown in FIG. 1 , an LC filter is formed by a reactor 8 arranged in series with a wiring 31 and a capacitor 3a connected between the pair of wirings 31 and 32 between the reactor 8 and the inverter circuit 4. Alternatively, an LC filter may be formed by a reactor 8 arranged in series with a wiring 32 and a capacitor 3a connected between the pair of wirings 31 and 32 between the reactor 8 and the inverter circuit 4. Alternatively, an LC filter may be formed by a reactor 8 arranged in series with each of the pairs of wirings 31 and 32 and a capacitor 3a connected between the pair of wirings 31 and 32 between the reactor 8 and the inverter circuit 4. The capacitors forming the LC filter may include three interphase capacitors, including a capacitor between the pair of wirings 61 and 62, a capacitor between the pair of wirings 62 and 63, and a capacitor between the pair of wirings 61 and 63. The reactors forming the LC filter may include a plurality of reactors arranged in series with each of the pairs of wirings 61, 62, and 63. The inductance used to calculate the resonant frequency of the LC filter when reactors are arranged in series with each of the wirings 61, 62, and 63 is 2×L, where L is the inductance of each of the reactors arranged in series with each of the wirings 61, 62, and 63.

[0056] 2 , an LC filter is formed by a reactor 8 arranged in series with a wiring 64 and a capacitor 3a connected between the pair of wirings 31 and 32 between the reactor 8 and the inverter circuit 4. An LC filter may also be formed by a reactor 8 arranged in series with a wiring 65 and a capacitor 3a connected between the pair of wirings 31 and 32 between the reactor 8 and the inverter circuit 4. An LC filter may also be formed by a reactor 8 arranged in series with each of the pairs of wirings 64 and 65 and a capacitor 3a connected between the pair of wirings 31 and 32 between the reactor 8 and the inverter circuit 4. The capacitors forming the LC filter may include a capacitor connected between the pair of wirings 64 and 65 between the reactor 8 and the converter circuit 2. The reactors forming the LC filter may include a reactor arranged in series with at least one of the pairs of wirings 31 and 32.

[0057] 3 is a diagram showing an example of the transfer characteristics of an LC filter. The LC filter has a resonant frequency. If harmonic components near the resonant frequency of the LC filter appear in the reactor 8 or the capacitor 3a, the signal may be excessively amplified according to the frequency characteristics of the LC filter. If the signal is excessively amplified, for example, abnormal heating of the reactor 8 or an excessive DC link voltage v ｄｃ There is a risk of this occurring.

[0058] The harmonic components that appear in the DC link section 3 mainly include: a: n-fold component of the power supply frequency (n is an integer equal to or greater than 1); b: 6-fold component of the output frequency; c: carrier frequency ±(3-fold component of the output frequency).

[0059] 3, harmonic component a is determined by the power supply frequency of the AC power supply 6 and appears in a frequency band of 2 kHz or less. Harmonic component b is determined by the output frequency of the inverter circuit 4 and appears in a frequency band higher than harmonic component a. Harmonic component c is determined by the carrier frequency and output frequency of the inverter circuit 4 and appears in a frequency band higher than harmonic components a and b.

[0060] If such harmonic components a, b, and c appear near the resonant frequency of the LC filter, the signal will be amplified according to the frequency characteristics of the LC filter. Harmonic component b is determined by the output frequency of the inverter circuit 4, and harmonic component c is determined by the carrier frequency and output frequency of the inverter circuit 4. Therefore, if the LC filter is made smaller and its resonant frequency is increased by increasing the carrier frequency, a region will appear in which harmonic components a, b, and c are unlikely to interfere with the LC filter resonance (see Figure 4).

[0061] 4 is a diagram illustrating an example of a setting range of the resonance frequency of the LC filter. In the technique of the present disclosure, the carrier frequency for driving the inverter circuit 4 is set to f ｃ The resonance frequency of the LC filter formed by the reactor 8 and the capacitor 3a is f ＬＣ , the maximum value of the output frequency of the inverter circuit 4 is MAX(f ０ ) In this case, MAX(f ０ )teeth,

[0062] If the above condition is satisfied, the characteristics of the LC filter can be set to a frequency band in which it is difficult to amplify the harmonic components a, b, and c.

[0063] Furthermore, Equation 1 is MAX(f ０ ) and solve it,

[0064]

[0065] is transformed into

[0066] Considering the magnitude relationship between the right-hand sides of Equation 3 and Equation 4,

[0067] That is, in the range in which Equation 5 holds, when Equation 3 holds, Equation 4 always holds.

[0068] Let L be the inductance of the inductance component from the point where the power conversion device 1A or the like is connected to the AC power supply 6 to the capacitor 3a, and C be the capacitance of the capacitor 3a.

[0069] The point at which the power conversion device is connected to the AC power supply 6 is, for example, in the case of Fig. 1 , an AC input terminal of the power conversion device 1A to which a plurality of wires 61, 62, and 63 are connected, and in the case of Fig. 2 , an AC input terminal of the power conversion device 1B to which a plurality of wires 64 and 65 are connected.

[0070] Therefore, when equations 3 and 5 are solved for the inductance L using the relationship in equation 6,

[0071]

[0072] is obtained.

[0073] Equation 7 and Equation 8 can be summarized for C as follows:

[0074] is obtained.

[0075] The lower limit value of C in Equation 9 approaches zero infinitely when the power source impedance on the AC power source 6 side as viewed from the power conversion device is infinite. Since power source impedance differs from country to country, the lower limit value of C in Equation 9 can take any value.

[0076] Therefore, the capacitance C of the capacitor 3a is

[0077] If the above condition is satisfied, the characteristics of the LC filter can be set to a frequency band in which it is difficult to amplify the harmonic components a, b, and c.

[0078] In the prior art, the carrier frequency and the output frequency were not taken into consideration, so there was a possibility that the resonant frequency of the LC filter would be set in a region where the above formula 1 or formula 2 does not hold. In the technology disclosed herein, the resonant frequency of the LC filter is set in a region where the above formula 1 or formula 2 holds, so that the amplification of harmonic components by the LC filter can be suppressed. As a result, abnormal heating of the reactor 8 and excessive DC link voltage v ｄｃ The occurrence of this can be suppressed.

[0079] resonance frequency f ＬＣ is 6 × MAX (f ０ ), the amplification of harmonic components by the LC filter can be suppressed without adding an additional circuit or special control. ＬＣ ga f ｃ -3 × MAX (f ０ ) can prevent the circuit from becoming larger in size due to the addition of a noise filter or the like caused by the higher carrier frequency.

[0080] For example, MAX(f ０ ) is set to 600 Hz. This allows the resonant frequency f ＬＣ Since the frequency of the LC filter is greater than 3.6 kHz (= 6 × 600 Hz), the amplification of harmonic components with frequencies lower than 3.6 kHz by the LC filter can be suppressed. In particular, since 600 Hz is the upper limit of the output frequency under the list regulation, the list regulation can be satisfied.

[0081] For example, the carrier frequency f ｃ The gain of the LC filter at the carrier frequency f is set to 0.1 or less. ｃThe gain of the LC filter at this frequency is -20 dB (0.1 times) or less, so the LC filter can suppress the harmonic components of the carrier frequency band. ｃ The gain of the LC filter at is preferably 0.01 or less (-40 dB or less), and more preferably 0.001 or less (-60 dB or less).

[0082] For example, 6×MAX(f ０ The gain of the LC filter at 6×MAX(f ０ ) the gain of the LC filter is 14 dB (5 times) or less. This means that the resonant frequency f ＬＣ Therefore, the effect of suppressing the amplification of harmonic components in the low frequency range by the LC filter is enhanced.

[0083] Fig. 5 shows a longitudinal cross-sectional view of an electrical unit including a power converter. The electrical unit 10 shown in Fig. 5 includes a box-shaped housing 15 and a power converter 20 housed in the housing 15. The power converter 20 is an example of the above-mentioned power converter 1A or the like.

[0084] As described above, the power conversion device 20 includes components such as the converter circuit 2, the reactor 8, the capacitor 3a, the inverter circuit 4, and the control unit 5. These components in the power conversion device 20 are mounted on a substrate 60. This allows heat from these components, such as the reactor 8, to be dissipated to the substrate 60. The substrate 60 is fixed to the inner surface of the housing 15.

[0085] The substrate 60 is thermally connected to the heat sink 47 via a thermally conductive connecting member 80, thereby allowing the heat of the substrate 60 to be dissipated from the heat sink 47. In the example shown in Fig. 5, a through hole 15d is formed in the housing 15. The substrate 60 is thermally connected to the heat sink 47 provided on the outside of the housing 15 via the connecting member 80 that passes through the through hole 15d.

[0086] Next, the results of comparing the technology of the present disclosure with the technology of Patent Document 1 using the power conversion device 1A configured as shown in Fig. 1 will be described with reference to Fig. 6 to Fig. 13. The technology of the present disclosure shows a case where the resonant frequency of the LC filter is set to satisfy the above formula 1, while the technology of Patent Document 1 shows a case where the resonant frequency of the LC filter is set to be more than 40 times the power supply frequency.

[0087] 6 to 9 show the case where a harmonic component b (a component six times the output frequency) appears. ｉｎ , the reactor current i flowing through the reactor 8 Ｌ , the DC link voltage v in the DC link section 3 ｄｃ , the motor current i flowing through the motor 7 ｍ 6 shows an embodiment to which the technology of the present disclosure is applied, and FIG. 7 shows a comparative example to which the technology of Patent Document 1 is applied. FIGS. 8 and 9 show the waveforms of the power supply current i of the AC power supply 6. ｉｎ , the reactor current i flowing through the reactor 8 Ｌ , the DC link voltage v in the DC link section 3 ｄｃ , the motor current i flowing through the motor 7 ｍ 8 shows the results of frequency analysis of each waveform of Fig. 1 by fast Fourier transform. Fig. 8 shows an embodiment to which the technology of the present disclosure is applied, and Fig. 9 shows a comparative embodiment to which the technology of Patent Document 1 is applied.

[0088] As shown in Fig. 9, in the technology of Patent Document 1, the harmonic component b (six times the output frequency) and the resonant frequency of the LC filter are close to each other, so the resonance of the LC filter is excited by the harmonic component b (six times the output frequency), and the harmonic component near the resonant frequency appears large. On the other hand, as shown in Fig. 8, in the technology of the present disclosure, the harmonic component b (six times the output frequency) is set to be sufficiently smaller than the resonant frequency of the LC filter, so the amplification of the harmonic component b (six times the output frequency) by the LC filter is suppressed. As a result, as shown in Figs. 6 and 7, the technology of the present disclosure has a power supply current i ｉｎ , reactor current i Ｌ and DC link voltage v ｄｃThe conditions for the simulations of FIGS. 6 to 9 are shown in FIG. 14.

[0089] 10 to 13 show the case where a harmonic component c (carrier frequency - (three times the output frequency)) appears. ｉｎ , the reactor current i flowing through the reactor 8 Ｌ , the DC link voltage v in the DC link section 3 ｄｃ , the motor current i flowing through the motor 7 ｍ 10 shows an embodiment to which the technology of the present disclosure is applied, and FIG. 11 shows a comparative example to which the technology of Patent Document 1 is applied. FIGS. 12 and 13 show the waveforms of the power supply current i of the AC power supply 6. ｉｎ , the reactor current i flowing through the reactor 8 Ｌ , the DC link voltage v in the DC link section 3 ｄｃ , the motor current i flowing through the motor 7 ｍ 12 shows an embodiment to which the technology of the present disclosure is applied, and FIG. 13 shows a comparative embodiment to which the technology of Patent Document 1 is applied.

[0090] In the case of FIG. 13, the harmonic component c (carrier frequency - (three times the output frequency)) appears near the resonance frequency of the LC filter. In contrast to this, in the case of FIG. 12, the harmonic component c (carrier frequency - (three times the output frequency)) appears away from the resonance frequency of the LC filter. As shown in FIGS. 12 and 13, the technology of the present disclosure suppresses the peak of the harmonic component c (carrier frequency - (three times the output frequency)) on the low frequency side compared to the technology of Patent Document 1. As a result, as shown in FIGS. 10 and 11, the technology of the present disclosure reduces the power supply current i ｉｎ , reactor current i Ｌ and DC link voltage v ｄｃ The conditions for the simulations of FIGS. 10 to 13 are shown in FIG.

[0091] In the first configuration example, an LC filter is disposed in the DC link unit 3. However, as long as the same function of the LC filter can be realized, the LC filter may be disposed between the AC power supply 6 and the converter circuit 2, or only the reactor constituting the LC filter may be connected between the AC power supply 6 and the converter circuit 2.

[0092] In the second configuration example, the capacitor 3a constituting the LC filter is disposed in the DC link unit 3. However, as long as the same LC filter function can be realized, the capacitor constituting the LC filter may be connected between the AC power supply 6 and the converter circuit 2, or the LC filter may be disposed between the AC power supply 6 and the converter circuit 2. In other words, as long as the capacitor is connected between the reactor constituting the LC filter and the inverter circuit (inverse converter), the LC filter may be disposed anywhere.

[0093] Furthermore, the LC filter may be configured without a reactor, for example, by using a capacitor and an inductance component of a wiring.

[0094] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Various modifications and improvements, such as combinations and substitutions with part or all of other embodiments, are possible.

[0095] This international application claims priority based on Japanese Patent Application No. 2021-061704, filed on March 31, 2021, and the entire contents of Japanese Patent Application No. 2021-061704 are incorporated by reference into this international application.

[0096] REFERENCE SIGNS LIST 1A, 1B Power conversion device 2 Converter circuit 3 DC link section 4 Inverter circuit 4a Switching element 5 Control section 6 AC power supply 7 Motor 8 Reactor 10 Electrical unit 15 Housing 15d Through hole 20 Power conversion device 31, 32 Wiring 47 Heat sink 60 Board 61, 62, 63, 64, 65, 66 Wiring 80 Connection member 101 Air conditioner

Claims

DEPCT671. A power converter assembly consisting of: a converter configured to convert AC power fed from an AC power source via the first conducting pair to DC power; an inverter configured to convert DC power output from the converter via the second conducting pair to AC power; and a capacitor connected between the conducting pairs of the first conducting pair or between the conducting pairs of the second conducting pair, where the inductance of the inductor component from the point where the power converter assembly is connected to the AC power source to the capacitor is given as L and allowing the maximum output frequency of the inverter to be MAX(f0), C, which is the capacitance of the capacitor, then follows (equation)•••Equation22. Power converter assembly according to claim1 where the carrier frequency for driving the inverter is given as fc, the gain of the LC filter circuit consisting of the inductor component and the capacitor at the carrier frequency fC is equal to 0.1 or less.3.

4. A power converter under any of the claims 1 to 3 where the inductor component consists of one or more reactors inserted in series into one or both conducting wires of the first conducting pair or into one or both conducting wires of the second conducting pair, and where a capacitor is connected between the conducting wires of the first conducting pair or between the conducting wires of the second conducting pair, between one or more reactors and an inverter.A power converter assembly consisting of: a converter configured to convert AC power fed from an AC power source via the first conduction pair into DC power; an inverter configured to convert DC power output from the converter via the second conduction pair into AC power; one or more reactors inserted in series in one or both conduction wires of the first conduction pair or one or both conduction wires of the second conduction pair; and a capacitor connected between the conduction wires of the first conduction pair or between the conduction wires of the second conduction pair between one or more reactors and the inverter, whereby the carrier frequency for driving the inverter is given as fC, the resonance frequency of the LC filter circuit consisting of one or more reactors and capacitors is allowed to be fLC, and the maximum value of the inverter's output frequency is allowed to be MAX(f0), MAX(f0) is given by (equation)•••Equation 16.

7. A power converter under claim 5 or 6 where the gain of the LC filter at carrier frequency fc is 0.1 or less.

8. A power converter under claim 4 or 5 where one or more reactors are components mounted on the baseboard.

9. Any one of claims 1 through 8 where a capacitor is connected between the wires.

10. A power converter under any of claims 1 through 9 where MAX(f0) is 600Hz; 11. A power converter under any of claims 1 through 10 where the switching element provided in the inverter is a wide band gap semiconductor device; 12. An air conditioner which includes a power converter under any of claims 1 through 11; 13. A refrigeration unit which includes a power converter under any of claims 1 through 11.

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