Power converter and refrigeration cycle system equipped therewith

Abstract

This power conversion device comprises: an electric power conversion circuit that converts electric power which is input from a power supply via a power supply line into electric power which is supplied to a load; and an active noise cancellation circuit that outputs, to the power supply line, a cancellation current which reduces noise flowing from the electric power conversion circuit to the power supply line. The active noise cancellation circuit has a protection part that reduces the cancellation current upon a rise in temperature.

Description

Technical Field

[0005] ,

[0001] The present disclosure relates to a power conversion device supplied with power from a power source and a refrigeration cycle device including the same.

Background Art

[0002] Conventionally, noise has flowed out to a power line from an inverter that drives a compressor provided in an air conditioner. In order to suppress the noise, a noise filter composed of passive elements has been used. However, when the noise filter is composed only of passive elements, the frequency band of the noise that can be suppressed is limited. To address this problem, a power conversion device has been proposed that detects a common mode noise current flowing through a power line to which alternating current is supplied and suppresses the common mode noise current using an active element (see, for example, Patent Document 1).

[0003] The power conversion device disclosed in Patent Document 1 includes a suppression unit that functions as an active conductive noise suppression circuit. The suppression unit includes a first coil unit that detects a common mode noise current, a second coil unit that causes a current for suppressing the common mode noise current to flow through the power line, and a current supply unit that is provided between the first coil unit and the second coil unit and functions as a current source for the current supplied to the second coil unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The current supply unit disclosed in Patent Document 1 includes an amplification circuit composed of relatively low-durability components such as operational amplifiers or transistors. Therefore, if an excessive current flows from the first coil unit into the amplification circuit, the amplification circuit attempts to amplify the input current, causing the operational amplifier or transistor to overheat and potentially destroy it. For example, if an excessive current is input to the amplification circuit due to a lightning surge, the amplification action will cause the temperature of the operational amplifier or transistor to rise, potentially destroying the amplification circuit due to the heat.

[0006] This disclosure was made to solve the above-mentioned problems and provides a power converter and a refrigeration cycle device equipped therewith that prevent the noise suppression circuit from being destroyed even when an excessive current is detected. [Means for solving the problem]

[0007] The power conversion device according to this disclosure comprises a power conversion circuit that converts power input from a power source via a power line into power supplied to a load, and an active noise cancellation circuit that outputs a cancellation current to the power line to reduce noise flowing out from the power conversion circuit to the power line, wherein the active noise cancellation circuit An input circuit including a detection passive element which is a passive element that detects the noise flowing in the power line; an output circuit including an injection passive element which is a passive element that injects the cancellation current into the power line; and an amplification circuit that generates the cancellation current corresponding to the noise detected by the input circuit and outputs the generated cancellation current to the power line via the output circuit. A protective unit that reduces the cancellation current when the temperature rises. and, to have The protective unit is one or both of the detection passive element and the injection passive element, and the protective unit has a positive temperature characteristic in which the impedance increases as the temperature rises. It is what it is.

[0008] The refrigeration cycle device according to this disclosure comprises a refrigerant circuit including a compressor, and the power conversion device described above which supplies power to the compressor to drive the motor of the compressor. [Effects of the Invention]

[0009] According to this disclosure, the active noise cancellation circuit is provided with a protection unit that reduces the cancellation current when the temperature rises. Therefore, even if an excessive current flows into the active noise cancellation circuit, the increase in the cancellation current is suppressed, and the temperature of the active noise cancellation circuit is suppressed. As a result, it is possible to prevent the active noise cancellation circuit from being destroyed by heat. [Brief explanation of the drawing]

[0010] [Figure 1] This is a refrigerant circuit diagram showing one example configuration of a refrigeration cycle system equipped with a power conversion device according to Embodiment 1. [Figure 2] This is a circuit diagram showing one example configuration of a power conversion device according to Embodiment 1. [Figure 3] Figure 2 is a circuit diagram showing one example configuration of a power conversion circuit. [Figure 4] Figure 2 is a circuit diagram showing one example configuration of the ANC. [Figure 5] This is a circuit diagram showing the configuration of the ANC in a power converter according to Modification Example 1. [Figure 6] This is a circuit diagram showing the configuration of the ANC in the power converter according to the modified example 2. [Figure 7] This is a circuit diagram showing the configuration of the ANC in the power converter according to the modified example 3. [Figure 8] Figure 7 is a circuit diagram showing one example configuration of the TSD circuit. [Figure 9] This is a circuit diagram showing the configuration of the ANC in the power converter according to the modified example 4. [Modes for carrying out the invention]

[0011] Embodiments of the power converter of this disclosure will be described with reference to the drawings. The power converter of this disclosure is not limited by the embodiments described below. In the embodiments described below, electrical connections will be simply referred to as "connections".

[0012] Embodiment 1. The configuration of a refrigeration cycle system equipped with a power converter according to Embodiment 1 will be described. In Embodiment 1, the description will be given as an air conditioning system, but the refrigeration cycle system is not limited to an air conditioning system. Figure 1 is a refrigerant circuit diagram showing an example configuration of a refrigeration cycle system equipped with a power converter according to Embodiment 1.

[0013] The refrigeration cycle device 10 comprises a heat source side unit 20 and a load side unit 30. The heat source side unit 20 includes a compressor 21, a four-way valve 22, a heat source side heat exchanger 23, an expansion valve 24, an outdoor fan 25, and a controller 26. The compressor 21 is equipped with the power converter 1 of this embodiment 1. The power converter 1 supplies power to the compressor 21 to drive the motor (not shown) of the compressor 21. The load side unit 30 includes a load side heat exchanger 31 and an indoor fan 32. The load side unit 30 is equipped with a room temperature sensor 33 that detects the temperature of the air in the room, which is the space to be air-conditioned by the load side unit 30.

[0014] The compressor 21, the heat source side heat exchanger 23, the expansion valve 24, and the load side heat exchanger 31 are connected by refrigerant piping 34, forming a refrigerant circuit 35 through which the refrigerant circulates. The power converter 1, the four-way valve 22, the expansion valve 24, the outdoor fan 25, the indoor fan 32, and the room temperature sensor 33 are each connected to the controller 26 via signal lines (not shown). The room temperature sensor 33 detects the room temperature at regular intervals and transmits the detected room temperature information to the controller 26.

[0015] The compressor 21 sucks in the refrigerant, compresses the sucked-in refrigerant, and discharges a high-temperature and high-pressure refrigerant. The compressor 21 is an inverter compressor that can change its capacity by controlling the operating frequency. The four-way valve 22 switches the flow direction of the refrigerant circulating in the refrigerant circuit 35 according to the operating mode of the refrigeration cycle device 10. The operating modes are, for example, heating operation, cooling operation, and defrosting operation. When the operating mode of the refrigeration cycle device ¹⁰ is cooling operation, the inside of the four-way valve 22 shown in FIG. 1 becomes the flow path shown by the solid line. When the operating mode of the refrigeration cycle device 10 is heating operation, the inside of the four-way valve 22 shown in FIG. 2 becomes the flow path shown by the broken line.

[0016] The outdoor fan 25 sucks in the outside air and sends the sucked-in outside air to the heat source side heat exchanger 23. The heat source side heat exchanger 23 is a heat exchanger that exchanges heat between the outside air and the refrigerant. The expansion valve 24 reduces the pressure of the refrigerant to expand it. The expansion valve 24 is, for example, an electronic expansion valve. The indoor fan 32 sucks in air from the room and sends the sucked-in air to the load side heat exchanger 31. The load side heat exchanger 31 is a heat exchanger that exchanges heat between the indoor air and the refrigerant. The heat source side heat exchanger 23 and the load side heat exchanger 31 are, for example, fin-and-tube type heat exchangers having heat transfer tubes (not shown) and a plurality of heat radiating fins (not shown).

[0017] The controller 26 is, for example, a microcomputer. The controller 26 controls the operation of the refrigeration cycle device 10. Specifically, the controller 26 controls the four-way valve 22 according to the operating mode set by the user of the refrigeration cycle device 10. The controller 26 controls the operating frequency of the compressor 21, the opening degree of the expansion valve 24, and the rotational speed of the outdoor fan 25 so that the detected value of the room temperature sensor 33 matches the preset set temperature. The controller 26 controls the rotational speed of the indoor fan 32 according to the air volume set by the user.

[0018] Figure 2 is a circuit diagram showing an example configuration of a power conversion device according to Embodiment 1. The power conversion device 1 of this Embodiment 1 includes a power conversion circuit 2 that converts power input from a power source 9 via a power line 15 into power supplied to a load 4, and an active noise cancellation circuit 3. Hereinafter, the active noise cancellation circuit will be referred to as ANC (Active Noise Canceller). In this Embodiment 1, the load 4 is an electric motor that drives the compressor 21 shown in Figure 1. The load 4 is an electric motor having a rotor (not shown) and a stator (not shown), with the stator having a U-phase winding Ur, a V-phase winding Vr, and a W-phase winding Wr.

[0019] Figure 3 is a circuit diagram showing one example configuration of the power conversion circuit shown in Figure 2. The power conversion circuit 2 includes a rectifier circuit 16, a smoothing circuit 17, and an inverter circuit 18. The inverter circuit 18 is connected to the load 4 via a power line 47. The rectifier circuit 16 is a circuit that converts the AC voltage supplied from the power source 9 via the power line 15 into a DC voltage. The rectifier circuit 16 has six reverse current prevention elements 41. The reverse current prevention elements 41 are diode elements that rectify the direction of current flow in one direction. The smoothing circuit 17 includes a reactor 42 that smooths the current output from the rectifier circuit 16 and a smoothing capacitor 43 that smooths the voltage output from the rectifier circuit 16. The smoothing circuit 17 outputs a stable DC power supply voltage to the inverter circuit 18.

[0020] The inverter circuit 18 has six switching elements 45a to 45f and six freewheeling diodes 46a to 46f, each connected in parallel to one of the switching elements. Switching elements 45a and 45b are connected to the U-phase winding Ur of the load 4 via a power line 47. Switching elements 45c and 45d are connected to the V-phase winding Vr of the load 4 via a power line 47. Switching elements 45e and 45f are connected to the W-phase winding Wr of the load 4 via a power line 47. The gate electrodes of the switching elements 45a to 45f are connected to the controller 26 via a signal line (not shown). The switching of each of the switching elements 45a to 45f between on and off states is controlled by the controller 26. By controlling the on and off states of the switching elements, the controller 26 controls the path of the current flowing from the power conversion circuit 2 to the load 4.

[0021] Switching elements 45a to 45f are semiconductor devices such as IGBTs (Insulated Gate Bipolar Transistors), MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), or HEMTs (High Electron Mobility Transistors).

[0022] Next, the configuration of the ANC3 shown in Figure 2 will be described. Figure 4 is a circuit diagram showing one example configuration of the ANC shown in Figure 2. As shown in Figure 2, the ANC3 is provided on the power line 15 between the power conversion circuit 2 and the power supply 9. As shown in Figures 2 and 4, the ANC3 has an input circuit 5, an output circuit 6, an amplification circuit 7, and a protection unit 8.

[0023] ANC3 outputs a cancellation current to the power line 15 to reduce noise flowing from the power conversion circuit 2 to the power line 15. The input circuit 5 has a detection passive element 11, which is a passive element that detects noise flowing in the power line 15. The output circuit 6 has an injection passive element 12, which is a passive element that injects cancellation current into the power line 15. The protection unit 8 has an input protection element 13 connected between the input circuit 5 and the amplification circuit 7, and an output protection element 14 connected between the output circuit 6 and the amplification circuit 7.

[0024] The input protection element 13 and the output protection element 14 play a role in reducing the cancellation current output from the amplifier circuit 7 when their own temperature rises. In the configuration example shown in Figure 4, the input protection element 13 and the output protection element 14 are, for example, PTC (Positive Temperature Coefficient) thermistors. A PTC thermistor is a resistive element whose resistance increases as the temperature rises. The input protection element 13 and the output protection element 14 have a positive temperature characteristic in which their impedance increases as the temperature rises.

[0025] The temperature characteristics of the input protection element 13 and the output protection element 14 should preferably be such that, if the impedance at 20°C is Z1, the impedance at 80°C is at least twice the impedance Z1. This is because it is assumed that the temperature at which an abnormality occurs in the ANC is 80°C, and therefore it is desirable that the protection unit 8 has temperature characteristics such that the resistance value at 80°C is sufficiently high. If the input protection element 13 and the output protection element 14 are PTC thermistors, the temperature characteristics of each element are, for example, 300 Ω / °C at 20°C and 1000 Ω / °C at 80°C.

[0026] The amplification circuit 7 generates a cancellation current corresponding to the noise detected by the input circuit 5, and outputs the generated cancellation current to the power line 15 via the output circuit 6. As shown in Figure 4, the amplification circuit 7 includes an amplifier 50 that inverts and amplifies the signal input from the input circuit 5, a resistor 51 provided at one of the two input terminals of the amplifier 50, and a resistor 52 provided in the negative feedback connection wiring.

[0027] Next, the operation of the power conversion device 1 of this embodiment 1 will be explained with reference to Figure 2. When noise generated from the power conversion circuit 2 flows into the power line 15, the noise is detected by the detection passive element 11 provided in the input circuit 5. The noise detected by the detection passive element 11 is input to the amplification circuit 7 via the input protection element 13. When the amplification circuit 7 receives noise from the input protection element 13, it generates a cancellation current to reduce the noise. The amplification circuit 7 then outputs the generated cancellation current to the power line 15 via the output protection element 14 and the injection passive element 12. By injecting the cancellation current into the power line 15, the current caused by the noise flowing through the power line 15 is reduced.

[0028] Now, let's consider the case where an excessive current flows through the power line 15 due to phenomena such as lightning surges. When an excessive current flows through the power line 15, the temperature of the input protection element 13 rises via the detection passive element 11, and the impedance of the input protection element 13 increases. As the input impedance of the amplifier circuit 7 increases, the increase in the cancellation current output from the amplifier circuit 7 is suppressed, and the temperature rise of the amplifier circuit 7 can be suppressed. It is also possible that when an excessive current flows through the power line 15, the temperature of the output protection element 14 rises via the injection passive element 12. In this case, the impedance of the output protection element 14 increases. As the output impedance of the amplifier circuit 7 increases, the increase in the cancellation current output from the amplifier circuit 7 is suppressed, and the temperature rise of the amplifier circuit 7 can be suppressed. In this way, even if an excessive current flows through the power line 15, the temperature rise of the amplifier circuit 7 is suppressed, and it is possible to prevent the amplifier circuit 7 from being destroyed by overheating.

[0029] In this embodiment 1, the case where both the input protection element 13 and the output protection element 14 are provided in the protection unit 8 was described, but it is sufficient if at least one of the input protection element 13 and the output protection element 14 is provided.

[0030] Furthermore, while the configuration examples shown in Figures 2 and 4 illustrate the case where the detection passive element 11 and the injection passive element 12 are coils, the elements are not limited to coils. The detection passive element 11 is an element that detects noise flowing in the power line 15, and the injection passive element 12 can be any element that can inject a cancellation current to reduce noise into the power line 15. For example, one or both of the detection passive element 11 and the injection passive element 12 may be capacitors.

[0031] Furthermore, the ANC3 in the power converter 1 of this embodiment 1 is not limited to the configuration shown in Figures 2 and 4. Modifications 1 to 4 of the ANC3 are described below. In modifications 1 to 4, the same reference numerals are used for the same components as those described with reference to Figures 1 to 4, and their detailed descriptions are omitted.

[0032] (Variation 1) Figure 5 is a circuit diagram showing the configuration of the ANC in a power converter according to Modification 1. As shown in Figure 5, in the ANC 3a, the protection unit 8a has an input protection element 13a and an output protection element 14a. The input protection element 13a and the output protection element 14a are coils whose magnetic permeability increases as the temperature rises. Figure 5 shows the configuration when the input protection element 13a and the output protection element 14a are provided in the ANC 3a, but it is sufficient if at least one of the input protection element 13a and the output protection element 14a is provided.

[0033] If the inductance of the coil is L[H] and the permeability is μ, then the inductance L is proportional to the permeability μ. The impedance of the coil is proportional to the inductance L. Therefore, the impedance of the input protection element 13a and the output protection element 14a increases as the temperature rises. In this modified example 1, if the input protection element 13a is provided on the ANC3a, when an excessive current flows through the power line 15, the temperature of the input protection element 13a rises via the detection passive element 11, and the impedance of the input protection element 13a increases. By increasing the input impedance of the amplifier circuit 7, the increase in the cancellation current output from the amplifier circuit 7 is suppressed, and the temperature rise of the amplifier circuit 7 can be suppressed. In this modified example 1, if the output protection element 14a is provided on the ANC3a, when the temperature of the output protection element 14a rises, the impedance of the output protection element 14a increases. By increasing the output impedance of the amplifier circuit 7, the increase in the cancellation current output from the amplifier circuit 7 is suppressed, and the temperature rise of the amplifier circuit 7 can be suppressed.

[0034] (Modification 2) Figure 6 is a circuit diagram showing the configuration of the ANC in a power converter according to Modification 2. As shown in Figure 6, in the ANC 3b, the protection unit 8b has an input protection element 13b and an output protection element 14b. The input protection element 13b and the output protection element 14b are capacitors whose dielectric constant decreases as the temperature rises. Figure 6 shows the configuration when the input protection element 13b and the output protection element 14b are provided in the ANC 3b, but it is sufficient if at least one of the input protection element 13b and the output protection element 14b is provided.

[0035] If the capacitance of a capacitor is C[F] and its dielectric constant is ε, then the capacitance C is proportional to the dielectric constant ε. The impedance of a capacitor is inversely proportional to the capacitance C. Therefore, as the temperature rises, the impedance of the input protection element 13b and the output protection element 14b increases. In this modified example 2, if the input protection element 13b is provided on the ANC3b, when an excessive current flows through the power line 15, the temperature of the input protection element 13b rises via the detection passive element 11, and the impedance of the input protection element 13b increases. As the input impedance of the amplifier circuit 7 increases, the increase in the cancellation current output from the amplifier circuit 7 is suppressed, and the temperature rise of the amplifier circuit 7 can be suppressed. In this modified example 2, if the output protection element 14b is provided on the ANC3b, as the temperature of the output protection element 14b rises, the impedance of the output protection element 14b increases. As the output impedance of the amplifier circuit 7 increases, the increase in the cancellation current output from the amplifier circuit 7 is suppressed, and the temperature rise of the amplifier circuit 7 can be suppressed.

[0036] (Variation 3) Figure 7 is a circuit diagram showing the configuration of the ANC in the power converter according to Modification 3. In this Modification 3, the ANC3c has a configuration in which a thermal shutdown (TSD) circuit 60, which functions as a protection unit 8, is provided in the amplification circuit 7a. The TSD circuit 60 is a circuit that supplies the operating voltage Vd to the amplifier 50. Figure 8 is a circuit diagram showing one example configuration of the TSD circuit shown in Figure 7.

[0037] As shown in Figure 8, the TSD circuit 60 includes a bipolar transistor 61 and resistors 62-64. The bipolar transistor 61 is a transistor in which the voltage Vbe between the base electrode and the emitter electrode exhibits a negative temperature characteristic. The bipolar transistor 61 remains in the off state when the temperature of the amplifier circuit 7a is below a predetermined threshold temperature Tth, and switches from the off state to the on state when the temperature of the amplifier circuit 7a is greater than the threshold temperature Tth. The threshold temperature Tth is, for example, 100°C.

[0038] Resistor elements 62 and 63 divide the power supply voltage Vcc and apply a constant base voltage Vb to the base electrode of the bipolar transistor 61. If the resistance value of resistor element 62 is R1 and the resistance value of resistor element 63 is R2, the base voltage Vb is expressed as Vb = Vcc × {R1 / (R1+R2)}. Resistor element 64 plays the role of dropping the power supply voltage Vcc to the operating voltage Vd.

[0039] Let's briefly explain the operation of the TSD circuit 60. When the temperature of the amplifier circuit 7a is below the threshold temperature Tth, the bipolar transistor 61 remains in the off state, and the operating voltage Vd is applied to the amplifier 50. On the other hand, when the temperature of the amplifier circuit 7a rises and exceeds the threshold temperature Tth, the bipolar transistor 61 switches from the off state to the on state, and the operating voltage Vd is no longer applied to the amplifier 50. As a result, the operation of the amplifier 50 stops. In this modified example 3, the explanation was given in the case where the TSD circuit 60 stops supplying the operating voltage Vd to the amplifier 50 when the temperature of the amplifier circuit 7a exceeds the threshold temperature Tth, but the TSD circuit 60 may also have a function to reduce the amplification factor of the amplifier 50.

[0040] In this modified example 3, if the temperature of the amplifier 50 rises due to an excessive current flowing through the power line 15, the temperature rise of the amplification circuit 7 can be suppressed. Furthermore, in this modified example 3, there is no need to provide a protection unit 8 between the input circuit 5 and the output circuit 6 and the amplification circuit 7.

[0041] (Modification 4) In this modified example 4, one or both of the detection passive element 11 and the injection passive element 12 function as elements that determine the noise cancellation performance. Figure 9 is a circuit diagram showing the configuration of the ANC in the power converter according to modified example 4. In the ANC3d shown in Figure 9, the detection passive elements 11a and 12a are elements that have a positive temperature characteristic in which the impedance increases as the temperature rises.

[0042] The passive detection element 11a is, for example, one of the input protection elements 13, 13a, and 13b. The passive injection element 12a is, for example, one of the output protection elements 14, 14a, and 14b. In the configuration example shown in Figure 9, if the passive detection element 11a is provided in the input circuit 5, the passive injection element 12 may be provided in the output circuit 6 instead of the passive injection element 12a. Also, in the configuration example shown in Figure 9, if the passive injection element 12a is provided in the output circuit 6, the passive detection element 11 may be provided in the input circuit 5 instead of the passive detection element 11a. In this modified example 4, since one or both of the passive detection element 11a and the passive injection element 12a serve as the protection unit 8, there is no need to provide a separate protection unit 8 in addition to the input circuit 5 and the output circuit 6.

[0043] The power converter 1 of this embodiment 1 includes a power conversion circuit 2 that converts power input from a power source 9 via a power line 15 into power supplied to a load 4, and an ANC 3 that outputs a cancellation current to the power line 15 to reduce noise flowing from the power conversion circuit 2 to the power line 15. The ANC 3 has a protection unit 8 that reduces the cancellation current when the temperature rises.

[0044] According to this embodiment 1, the ANC3 is provided with a protection unit 8 that reduces the cancellation current when the temperature rises. Therefore, even if an excessive current flows into the ANC3 due to phenomena such as lightning surges, the increase in the cancellation current is suppressed, and the rise in the temperature of the ANC3 is suppressed. As a result, it is possible to prevent the ANC3 from being destroyed by heat. Conventionally, there is a problem that the output setting of the amplification circuit changes due to changes such as an increase in the resistance value of the detection passive element. To address this problem, this embodiment 1 can suppress changes in the cancellation current by changing the gain of the amplification circuit 7 in consideration of changes such as an increase in the resistance value of the detection passive element 11.

[0045] For example, if an input protection element 13 is provided on the input side of the amplification circuit 7, and the input protection element 13 is a PTC thermistor, then if an excessive current flows through the input protection element 13 and it overheats, the impedance of the input protection element 13 increases. As the input impedance of the amplification circuit 7 increases, the current amplified by the amplification circuit 7 decreases, and the cancellation current injected into the power line 15 decreases. In this way, the cancellation current decreases when the temperature of the ANC3 rises, preventing the temperature of the ANC3 from rising excessively.

[0046] In this embodiment 1, the power converter 1 was described as being installed in a refrigeration cycle device 10, but the device on which the power converter 1 is installed is not limited to a refrigeration cycle device. Also, in this description, the load 4 connected to the power converter 1 was described as being the motor of the compressor 21, but the load 4 connected to the power converter 1 is not limited to the motor of the compressor.

[0047] Furthermore, while the protection unit 8 shown in Figure 4, protection unit 8a shown in Figure 5, and protection unit 8b shown in Figure 6 are shown as cases where the input protection element and output protection element are of the same type of passive element, these passive elements may be of different types. For example, in the protection unit 8 shown in Figure 4, output protection element 14a or 14b may be provided instead of output protection element 14. [Explanation of Symbols]

[0048] 1 Power converter, 2 Power conversion circuit, 3, 3a~3d Active noise cancellation circuit (ANC), 4 Load, 5 Input circuit, 6 Output circuit, 7, 7a Amplification circuit, 8, 8a, 8b Protection unit, 9 Power supply, 10 Refrigeration cycle device, 11, 11a Detection passive element, 12, 12a Injection passive element, 13, 13a, 13b Input protection element, 14, 14a, 14b Output protection element, 15 Power line, 16 Rectifier circuit, 17 Smoothing circuit, 18 Inverter circuit, 20 Heat source side unit, 21 Compressor, 22 Four-way valve, 23 Heat source side heat exchanger, 24 Expansion valve, 25 Outdoor fan, 26 Controller, 30 Load side unit, 31 Load side heat exchanger, 32 Indoor fan, 33 Room temperature sensor, 34 Refrigerant piping, 35 Refrigerant circuit, 41 Reverse current prevention element, 42 reactor, 43 smoothing capacitor, 45a~45f switching element, 46a~46f freewheeling diode, 47 power line, 50 amplifier, 51, 52 resistive elements, 60 thermal shutdown (TSD) circuit, 61 bipolar transistor, 62~64 resistive elements, Ur, Vr, Wr windings.

Claims

1. A power conversion circuit that converts power input from a power source via a power line into power supplied to a load, An active noise cancellation circuit that outputs a cancellation current to the power line to reduce noise flowing from the power conversion circuit to the power line, It has, The active noise cancellation circuit described above is An input circuit including a detection passive element which is a passive element that detects the noise flowing in the power line, An output circuit including an injection passive element which is a passive element that injects the cancellation current into the power line, An amplification circuit that generates the cancellation current corresponding to the noise detected by the input circuit and outputs the generated cancellation current to the power line via the output circuit, It has a protection unit that reduces the cancellation current when the temperature rises, The protective unit is one or both of the detection passive element and the injection passive element. The protective part has a positive temperature characteristic in which the impedance increases as the temperature rises. Power converter.

2. The aforementioned protective unit has an impedance at 80°C that is at least twice as large as the impedance at 20°C. The power conversion device according to claim 1.

3. The protective component is a thermistor whose resistance increases as the temperature rises. The power conversion device according to claim 1 or 2.

4. The protective part is a coil whose magnetic permeability increases as the temperature rises. The power conversion device according to claim 1 or 2.

5. The protective unit is a capacitor whose dielectric constant decreases as the temperature rises. The power conversion device according to claim 1 or 2.

6. A refrigerant circuit including a compressor, A power conversion device according to claim 1 or 2, which supplies power to the compressor to drive the motor of the compressor, A refrigeration cycle device equipped with a refrigeration cycle system.

Images