Control device and air conditioning device

Abstract

The invention provides a control device and an air-conditioning device, which can suppress current concentration and prolong the service life of a capacitor. A control device for controlling a power plant includes: a first conversion unit for converting a voltage from an AC power source into a DC power source; the smoothing unit is used for smoothing the converted voltage; and the second conversion unit is used for converting the smoothed voltage into alternating current and applying the alternating current to power equipment. The smoothing unit has three or more capacitors connected in series and a balancing resistor connected in parallel with the capacitors. The first conversion unit, the second conversion unit, and the capacitors are mounted on a substrate, the balance resistor is externally connected to the substrate using a terminal, and the number of capacitors connected in series is increased so that the temperature difference between the capacitors does not increase. The number of capacitors of a second rated voltage is larger than the number of capacitors of the first rated voltage, the second rated voltage being smaller than the number of capacitors of the first rated voltage being as large as possible that satisfy the withstand voltage and being designed so as to reduce the number of the capacitors of the first rated voltage.

Description

Technical Field

[0001] The invention relates to a control device for controlling power equipment and an air conditioning device. Background Art

[0002] The air conditioner has a compressor motor for driving a compressor and a fan motor for driving a fan as power equipment. A control device for controlling these motors includes: a converter circuit for converting a voltage from an AC power supply into a DC; a smoothing circuit for smoothing the converted voltage; and an inverter circuit for converting the smoothed voltage into a desired AC and applying it to each motor.

[0003] The capacitor constituting the smoothing circuit needs to use a capacitor with a rated voltage corresponding to the specifications of the AC power supply. In the case where it is difficult to meet the withstand voltage with one capacitor, a method of connecting two capacitors in series is known (for example, refer to Patent Document 1). In addition, when the capacitor is mounted on a substrate, there is an upper limit to the electrostatic capacitance of each capacitor, so the required electrostatic capacitance is achieved by connecting multiple capacitors in parallel.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2011-223785 Summary of the invention

[0005] The rated voltage and impedance of a capacitor are in a trade-off relationship. The higher the rated voltage of a capacitor, the greater the impedance tends to be. Capacitors have the following characteristics: the lower the temperature, the greater the impedance, and the higher the rate of increase. Therefore, when multiple capacitors are used at low temperatures, the impedance difference between the capacitors becomes larger, resulting in a phenomenon in which current is concentrated on a specific capacitor. As a result, there is a problem that the capacitor where the current is concentrated generates heat, and the life is shortened due to the heat.

[0006] In view of the above-mentioned problems, the present invention provides a control device for controlling a power device, the control device comprising: a first conversion unit, which converts the voltage from an AC power supply into a DC; a smoothing unit, which smoothes the converted voltage; and a second conversion unit, which converts the smoothed voltage into an AC and applies it to the power device, the smoothing unit having: more than three capacitors connected in series; and a balancing resistor connected in parallel with the capacitor.

[0007] According to the present invention, the current concentration phenomenon can be suppressed and the life of the capacitor can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a diagram showing a configuration example of an air conditioning device.

[0009] Figure 2 This is a diagram for explaining a refrigerant circuit of an air-conditioning device.

[0010] Figure 3 It is a diagram showing a first configuration example of a control unit that controls a power plant.

[0011] Figure 4 This is a diagram comparing a conventional smoothing circuit and a smoothing circuit included in the control device of the present embodiment.

[0012] Figure 5 This is a diagram showing an example of the temperature characteristics of the induction tangent of an aluminum electrolytic capacitor.

[0013] Figure 6 It is a graph showing the change in the temperature inside the capacitor at each position.

[0014] Figure 7 It is a graph showing the change in the internal temperature of the capacitor at each position under each ambient temperature.

[0015] Figure 8 It is a diagram showing a second configuration example of a control unit that controls a power plant. DETAILED DESCRIPTION

[0016] Figure 1 1 is a diagram showing a configuration example of an air conditioning device. The air conditioning device 10 includes an indoor unit 11 installed in a space to be air-conditioned (indoors), an outdoor unit 12 installed outdoors, and a remote controller 13 operated by a user. The air conditioning device 10 performs air conditioning by circulating a refrigerant as a heat medium between the indoor unit 11 and the outdoor unit 12 and performing heat exchange with the indoor air. Therefore, the indoor unit 11 and the outdoor unit 12 are connected by two refrigerant pipes 14 and 15 for circulating the refrigerant.

[0017] The indoor unit 11 and the outdoor unit 12 may each be composed of two or more units, and two or more indoor units 11 may be connected to one outdoor unit 12. As the refrigerant, hydrofluorocarbon (HFC) and hydrofluoroolefin (HFO) can be used. As the type of HFC, R410A, R32, etc. can be cited. As the type of HFO, R1234yf, etc. can be cited.

[0018] The indoor unit 11 communicates wirelessly with the remote controller 13 using infrared rays or the like, and receives various signals such as operation instructions, stop instructions, instructions for changing the set temperature, instructions for changing the operation mode, etc. The indoor unit 11 is connected to the outdoor unit 12 via a communication line, and cooperates with the outdoor unit 12 to perform indoor air conditioning.

[0019] The indoor unit 11 receives an operation command from the remote controller 13 and starts up, and instructs the outdoor unit 12 to start up. After starting up, the outdoor unit 12 adjusts the rotation speed of the compressor, the opening of the expansion valve, etc., and controls the circulation amount of the refrigerant, etc., so that the indoor temperature reaches the set temperature.

[0020] Reference Figure 2 , the refrigerant circuit of the air-conditioning device 10 is briefly described. Figure 2 The arrows shown indicate the flow of the refrigerant during cooling operation, and the description will focus on the operation during cooling operation. In addition, during heating operation, the flow direction of the refrigerant is opposite.

[0021] The indoor unit 11 includes an indoor heat exchanger 20, an indoor fan 21, and an indoor fan motor 22 as a power device. The indoor fan 21 is driven by the indoor fan motor 22 to take in indoor air and send it to the indoor heat exchanger 20. The indoor heat exchanger 20 is configured to have a heat transfer pipe for refrigerant to flow therein, and the air sent in contacts with the surface of the heat transfer pipe to perform heat exchange. The air that has undergone heat exchange through the indoor heat exchanger 20 is discharged to the room.

[0022] In addition, the indoor unit 11 may include various sensors for measuring the indoor temperature, an expansion valve, and the like.

[0023] The outdoor unit 12 includes a compressor 30, an accumulator 31, a four-way valve 32, an expansion valve 33, an outdoor heat exchanger 34, an outdoor fan 35, and an outdoor fan motor 36 as a power device. The compressor 30 is driven by a compressor motor as a power device, compresses a low-pressure gas refrigerant, and discharges it as a high-pressure gas refrigerant. The accumulator 31 is a container for storing liquid reflux during transition, and adjusts the refrigerant to an appropriate dryness. Dryness is the proportion of steam in wet steam that represents a mixed state of steam and fine droplets.

[0024] The four-way valve 32 is a valve that switches the flow path of the refrigerant according to the operating state (operating mode) of the air conditioning device 10. The operating modes are cooling mode, heating mode, air supply mode, etc. The expansion valve 33 is a valve that reduces the pressure of the high-pressure refrigerant and expands it. The outdoor fan 35 is driven by the outdoor fan motor 36, sucks in outdoor air, and sends it to the outdoor heat exchanger 34. Similar to the indoor heat exchanger 20, the outdoor heat exchanger 34 is configured to have a heat transfer pipe for the refrigerant to circulate inside, and the air sent in contacts with the surface of the heat transfer pipe to exchange heat. The air that has undergone heat exchange through the outdoor heat exchanger 34 is discharged to the outside.

[0025] The outdoor unit 12 is further provided with a control device 37. The control device 37 is connected to the compressor 30, the four-way valve 32, the expansion valve 33, the indoor fan motor 22, and the outdoor fan motor 36, and controls them. Specifically, the control device 37 controls the rotation speed of the compressor motor, the opening degree of the expansion valve 33, the rotation speed of the indoor fan motor 22 and the outdoor fan motor 36, and the like. In order to control these, various sensors are also installed in the outdoor unit 12. The control device 37 performs these controls based on the information detected by the various sensors.

[0026] In cooling operation, the indoor heat exchanger 20 is used as an evaporator and the outdoor heat exchanger 34 is used as a condenser. Therefore, as shown by arrows, the control device 37 circulates the refrigerant sealed in the system in the order of the compressor 30, the outdoor heat exchanger 34, the expansion valve 33, the indoor heat exchanger 20, the four-way valve 32, the accumulator 31, and the compressor 30.

[0027] The compressor 30 compresses the refrigerant (refrigerant gas) in a low-temperature and low-pressure gas state and discharges it as a high-temperature and high-pressure refrigerant gas. The outdoor heat exchanger 34 exchanges heat with the outdoor air to cool the refrigerant gas and condense it. The expansion valve 33 decompresses the refrigerant and gasifies a part of it. Therefore, the refrigerant is supplied to the indoor unit 11 in a gas-liquid mixed state. The opening of the expansion valve 33 is adjusted by the control device 37 to obtain an appropriate amount of liquid.

[0028] The indoor heat exchanger 20 exchanges heat with the indoor air, and the condensed liquid refrigerant is completely vaporized and returned as refrigerant gas to the outdoor unit 12. The refrigerant gas returned from the indoor heat exchanger 20 is sent to the accumulator 31 through the four-way valve 32 and returns to the compressor 30.

[0029] The control device 37 is installed in the outdoor unit 12, but is not limited thereto, and may be installed in the indoor unit 11, or may be installed in other central control panels, etc. In addition, the device on which the control device 37 is installed is not limited to the air conditioning device 10, and may be a cooler, a refrigerator, etc.

[0030] Figure 3 1 is a diagram showing a first configuration example of a control unit 40 for controlling a power device provided in a control device 37. Although the control unit 40 for controlling the power device is described as being included in the control device 37 for controlling the air conditioner 10, the present invention is not limited thereto and may be configured as a device separate from the control device 37.

[0031] The AC power source is a three-phase AC power source in which the voltage phases are shifted by 120 degrees. The three-phase AC power source has three power lines, each of which is marked as an R phase, an S phase, and a T phase. The control unit 40 includes a noise filter 41 and an inverter device 42.

[0032] The noise filter 41 removes noise intruding from the power line of the AC power source to prevent malfunction of the power equipment, and prevents noise generated by the control unit 40 from leaking to the power line to prevent adverse effects on other equipment.

[0033] The inverter device 42 includes a converter circuit 43 as a first conversion unit, a smoothing circuit 44 as a smoothing unit, and an inverter circuit 45 as a second conversion unit.

[0034] The converter circuit 43 is a circuit that converts the voltage from the AC power supply into a DC power supply, and includes a diode module 50, a surge current protection resistor 51, and a power relay 52. ​​The diode module 50 is a rectifier circuit that converts the voltage from the AC power supply into a DC power supply. The surge current protection resistor 51 is a resistor that limits the temporary large current that flows when the power supply is turned on. The power relay 52 is a relay that detects changes in the voltage of the power supply, etc., and cuts off as needed to prevent malfunctions, failures, etc.

[0035] The smoothing circuit 44 is a circuit for smoothing the voltage converted by the converter circuit 43, and includes a DC reactor (DCL) 60, a plurality of capacitors 61, and a plurality of balancing resistors 62. The DC reactor 60 blocks higher harmonics having frequency components that are several times the fundamental wave of the AC power supply. The DC reactor 60 is not a component mounted on the substrate, but an external component connected using a connecting component such as a terminal.

[0036] Regarding the plurality of capacitors 61, the number thereof is the number of capacitors connected in series to meet the withstand voltage according to the specifications of the AC power supply. For example, when a capacitor alone is difficult to meet its withstand voltage, a capacitor formed by connecting two capacitors in series is used. In addition, when mounting the capacitor on a substrate, there is an upper limit to the electrostatic capacitance of each capacitor, so a plurality of capacitors are connected in parallel to achieve the required electrostatic capacitance.

[0037] exist Figure 3 In the example shown, two capacitors may be connected in series as the number that satisfies the withstand voltage, but three capacitors are connected in series for the following reasons. In addition, power needs to be supplied to the three motors of the compressor motor, the indoor fan motor 22, and the outdoor fan motor 36. In order to achieve the required electrostatic capacity, three groups of three capacitors connected in series are used, and the three groups of capacitors are connected in parallel.

[0038] The capacitor 61 is charged until the voltage exceeds a certain value, and is discharged when the voltage is lower than a certain value, thereby smoothing the voltage. When two or more capacitors 61 are connected in series, the voltage applied to each capacitor connected in series becomes unbalanced. If the voltage applied to each capacitor becomes unbalanced, overcurrent may be applied to some capacitors. Therefore, in order to make the voltage applied to all capacitors 61 constant, the balancing resistor 62 is connected in parallel with each capacitor 61.

[0039] exist Figure 3 In the example shown, three sets of three capacitors connected in series are used (in Figure 3 The three capacitors 61 are connected in parallel. The balancing resistor 62 is connected to the three capacitors (in Figure 3That is, the three capacitors arranged horizontally exist in three sections, namely, the upper section, the middle section, and the lower section, and one balancing resistor 62 is connected to each section. The three balancing resistors 62 are connected to each other, and three of them are connected in series.

[0040] The inverter circuit 45 is a circuit that converts the smoothed voltage into an alternating current and applies it to each motor, and includes a power module 70. The power module 70 includes a plurality of transistors, and switches on and off to convert the voltage from a direct current to an alternating current, and applies an alternating current voltage to each motor. The power module 70 changes the duty ratio, which is a value obtained by dividing the on time by the period, and converts it into an alternating current voltage of a predetermined frequency.

[0041] Here, refer to Figure 4 , a conventional smoothing circuit is compared with the smoothing circuit 44 included in the control device 37 of the present embodiment. Figure 4 (a) shows a conventional smoothing circuit 80. Figure 4 (b) shows the smoothing circuit 44 provided in the control device 37 of this embodiment. Since there is an upper limit to the electrostatic capacitance of each of the smoothing circuit 80 and the smoothing circuit 44 when mounted on a substrate, a circuit in which three sets of capacitors connected in series are connected in parallel is used to realize the required electrostatic capacitance.

[0042] In the conventional smoothing circuit 80 , two capacitors 81 are connected in series, whereas in the smoothing circuit 44 included in the control device 37 of the present embodiment, three capacitors 61 are connected in series.

[0043] Aluminum electrolytic capacitors are used as the type of capacitors mounted on the substrate. Aluminum electrolytic capacitors are low-cost and large-capacity capacitors, and have a structure in which a dielectric is sandwiched between electrodes, and the dielectric is made of aluminum oxide.

[0044] like Figure 4 As shown in the "Existing" column of (c), for example, when the specification of the AC power supply is 575V and the power supply voltage range is ±10%, the peak value of the DC voltage is 575×1.1×√2=894V. In a single capacitor with a rated voltage of 550V, the withstand voltage is insufficient, so two 550V capacitors can be connected in series to make the withstand voltage 1100V.

[0045] Usually, in order to meet the withstand voltage requirement, the design uses capacitors with the largest possible rated voltage and reduces their number. This is because when the number of capacitors increases, the substrate area needs to be increased, and the installation man-hours also increase. Therefore, in the past, two capacitors with a rated voltage of 550V were connected in series to a DC voltage of 894V to set it to 1100V, which is higher than 894V.

[0046] Here, as an element indicating the performance of a capacitor, induction tangent (tan δ) is known. Induction tangent is obtained by dividing the resistance component value by the impedance value of the capacitance component, and therefore depends on impedance.

[0047] Figure 5 This is a graph showing an example of the temperature characteristics of the induction tangent of an aluminum electrolytic capacitor. As the temperature of the aluminum electrolytic capacitor decreases, the value of tanδ increases, and the impedance increases. The rate of increase in impedance depends on the slope of the temperature characteristics of tanδ, and increases as the temperature decreases.

[0048] Here, it is assumed that the capacitors connected in parallel (in Figure 3 A temperature difference is generated between the capacitors (capacitors arranged horizontally in the middle). The impedance of the capacitor in the high temperature state becomes lower than that of other capacitors. That is, the impedance of the capacitor in the high temperature state becomes relatively low. Current tends to flow in places with low impedance, so it will flow in large quantities to the capacitor in its high temperature state. The current flowing in large quantities to the capacitor becomes the current (load current) that applies a load to the capacitor, causing self-heating of the capacitor. If a temperature difference is further generated between the self-heating capacitors, the self-heating of the capacitor is promoted, and eventually the current is concentrated on the capacitor, deteriorating the life. In the case of mounting the capacitor on a substrate, it is not possible to replace only the capacitor with deteriorated life, so it must be replaced together with the substrate, and the life of the substrate is also shortened.

[0049] Impedance and rated voltage are in a trade-off relationship, with the higher the rated voltage, the greater the impedance tends to be. In addition, the higher the rated voltage, the greater the rate of increase in impedance. Therefore, if a temperature difference occurs between capacitors connected in parallel, the higher the rated voltage, the greater the rate of increase, so the impedance decreases significantly, which easily causes current concentration.

[0050] In fact, five smoothing circuits were used, each of which was formed by connecting two capacitors 81 in series, as in the conventional smoothing circuit 80. These were connected in parallel and a temperature rise test was performed under low temperature conditions. The results are shown in FIG. Figure 6 . Figure 6 (a) is a graph showing the relationship between the elapsed time (seconds) and the internal temperature of the capacitor (°C). Figure 6 (b) shows the expression Figure 6 (a) Diagram of the position of the capacitors on each line.

[0051] according to Figure 6 The results shown in (a) show that the internal temperature of the capacitors of EC6 and EC9 gradually increased after 2000 seconds from the start of the test. On the other hand, it was confirmed that the internal temperature of capacitors other than EC6 and EC9 tended to decrease, and the temperature difference with EC6 and EC9, which had increased in temperature, increased. This shows that load concentration occurred in EC6 and EC9.

[0052] Figure 7 This is a graph showing the relationship between the elapsed time (seconds) and the internal temperature of the capacitor (°C), with the ambient temperature changed in the middle. From the start of the test to about 1300 seconds, the ambient temperature was set to -10°C, from about 1300 seconds to about 3700 seconds, the ambient temperature was set to -15°C, and after about 3700 seconds, the ambient temperature was set to -20°C. When the ambient temperature was -10°C, there was almost no temperature difference between the internal temperatures of the capacitors, but as the temperature became low, such as -15°C and -20°C, the temperature difference expanded. Therefore, it can be seen that the lower the ambient temperature, the greater the temperature difference, and the more likely it is to cause current concentration.

[0053] If only two capacitors are connected in series, the rated voltage of each capacitor is large, and the impedance change rate (increase rate) is large. Therefore, if a temperature difference occurs between the capacitors, the impedance of the capacitor in the high temperature state tends to become lower, and if the temperature difference increases, it tends to cause current concentration.

[0054] Therefore, if the rated voltage of the capacitor is reduced, even if a temperature difference occurs between the capacitors, the impedance of the capacitor in the high temperature state is less likely to decrease due to the small rate of change of impedance, and it is conceivable that the current concentration phenomenon is less likely to occur.

[0055] Therefore, if Figure 4 As shown in "New" in (c), for a DC voltage of 894 V, although there is a capacitor with a rated voltage of 550 V, the rated voltage is lowered and a capacitor with a rated voltage of 350 V is used. At this time, in order to meet the withstand voltage, three capacitors with a rated voltage of 350 V are used and connected in series.

[0056] In addition, the rated voltage of the capacitor uses a voltage less than 350V, and in order to meet the withstand voltage, more than 4 capacitors can be connected in series. However, if the number of capacitors connected in series is increased, the number of parallel connections will increase each time (for example, 3 in the case of 3 columns of parallel connection), so if this number is increased, the substrate area becomes larger and the installation time also increases, which may lead to an increase in cost. Therefore, considering the substrate area, installation time, etc., it is preferred that the number of capacitors connected in series is an appropriate number.

[0057] The AC power supply has a maximum rating of 700 V or less, so three capacitors are preferably an appropriate number to be connected in series.

[0058] As described above, by increasing the number of capacitors connected in series from 2 to 3 and lowering the rated voltage of each capacitor, it is possible to prevent current from concentrating on a specific capacitor under low temperature conditions, thereby preventing heat generation and the resulting deterioration in life.

[0059] In addition, if Figure 3As shown in FIG. 1 , when capacitors are connected in series, a balancing resistor 62 is connected in parallel to each capacitor in order to make the applied voltage of each capacitor equal. Since the balancing resistor 62 is directly connected to the DC power supply, current always flows through it, generating heat.

[0060] When the ratio of the difference in applied voltage between capacitors is defined as the degree of imbalance, if the rated voltage of the capacitor is lowered, the allowable degree of imbalance becomes smaller. In order to reduce the degree of imbalance, the value of the balancing resistor 62 needs to be reduced.

[0061] When the value of the balancing resistor 62 is reduced, the current value of the current that always flows increases, and the heat generation increases. In order to mount the balancing resistor 62 on the substrate, the heat generation must be suppressed below the allowable temperature of the substrate. In order to disperse the heat generation, a plurality of balancing resistors 62 may be required.

[0062] By making the balancing resistor 62 an external component, the temperature can be allowed to expand, and there is no need to provide multiple balancing resistors 62, so that the number of balancing resistors can be reduced. In addition, if the balancing resistor 62 is made an external component, the installation man-hour increases, but when the reduction of component cost and substrate area is given priority, it is preferable to make the balancing resistor 62 an external component and connect it externally.

[0063] Figure 8 2 is a diagram showing a second configuration example of a control unit for controlling a power plant included in the control device 37. Figure 3 The same components as those of the control unit shown in the figure have been described above, and therefore their description is omitted here.

[0064] exist Figure 8 In the example shown, the balancing resistor 62 is an external component. For example, the following structure can be adopted: a flat terminal (tab terminal) is installed on the balancing resistor 62, and the tab terminal is connected by inserting it into a connector (socket) having a fitting portion connected to the wire extending from the substrate. As a result, the balancing resistor 62 is not installed on the substrate, so the substrate area can be reduced. In addition, since the balancing resistor 62 is configured separately from the substrate, even if the balancing resistor 62 generates heat, it does not need to be suppressed to below the allowable temperature of the substrate, and the number of balancing resistors 62 does not need to be increased.

[0065] Furthermore, the method of connecting the balancing resistor 62 to the substrate is not limited to the method of connecting by inserting the connector terminal and the socket, and may also be a method of connecting a ring-shaped terminal (round terminal) having a circular hole in the center to a terminal (screw terminal) having a threaded hole for screwing with a screw, etc. Furthermore, these are just examples, and other connection methods are of course possible.

[0066] When the balancing resistor 62 is an external component, if the connection to the balancing resistor 62 is made by mistake, an overvoltage is applied to the capacitor 61 at the same time as the power supply is input, and the capacitor 61 may be damaged. Therefore, by making the shapes and sizes of the terminals of the connection substrate and the balancing resistor 62 different, it is possible to prevent the wrong wiring from being physically connected, thereby preventing the wrong wiring.

[0067] Although it is also possible to prevent miswiring by changing the mark or color on the terminal to distinguish them, the wrong terminal may be connected among terminals of the same shape and size, which may cause the above-mentioned damage problem. On the other hand, by changing the shape, size, or both of the terminals, only the correct wiring can be used for physical connection, so miswiring can be reliably prevented.

[0068] So far, the control device and the air-conditioning device of the present invention have been described in detail using the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments and can be changed within the scope that can be thought of by technical personnel in this field, such as other embodiments, additions, changes, deletions, etc. In any mode, as long as the function and effect of the present invention are achieved, it is included in the scope of the present invention.

[0069] Therefore, it is also possible to provide an outdoor unit of an air conditioner including the control device, an indoor unit of an air conditioner including the control device, etc. In addition, the control device can also be applied to devices other than air conditioners as long as it is a device having a power device such as a motor.

[0070] Explanation of symbols

[0071] 10…Air conditioning unit

[0072] 11…Indoor unit

[0073] 12…Outdoor unit

[0074] 13…Remote Control

[0075] 14, 15…Refrigerant piping

[0076] 20…Indoor heat exchanger

[0077] 21…Indoor fan

[0078] 22…Indoor fan motor

[0079] 30…Compressor

[0080] 31…Liquid reservoir

[0081] 32…Four-way valve

[0082] 33…Expansion valve

[0083] 34…Outdoor heat exchanger

[0084] 35…Outdoor fan

[0085] 36…Outdoor fan motor

[0086] 37…Control device

[0087] 40…Control Department

[0088] 41…Noise filter

[0089] 42…Inverter device

[0090] 43…Converter circuit

[0091] 44, 80…Smoothing circuit

[0092] 45…Inverter circuit

[0093] 50...Diode module

[0094] 51…Surge current protection resistor

[0095] 52…Power relay

[0096] 60…DC reactor

[0097] 61, 81…Capacitor

[0098] 62…Balancing resistor

[0099] 70…Power module.

Claims

1. A control device for controlling a power device, characterized in that: The control device comprises: A first conversion unit, which converts the voltage from the AC power source into a DC; a smoothing unit, which smoothes the converted voltage; and a second conversion unit, which converts the smoothed voltage into an alternating current and applies it to the power device, The smoothing unit includes: three or more capacitors connected in series and a balancing resistor connected in parallel with the capacitors. The first conversion unit, the second conversion unit and the capacitor are mounted on a substrate, and the balancing resistor is externally connected to the substrate using a terminal. Regarding the number of the capacitors connected in series, capacitors with a second rated voltage that is smaller than the number of capacitors with a first rated voltage that is as large as possible that meets the withstand voltage are used so as not to increase the temperature difference between the capacitors, and the number is set to be greater than the number of capacitors with the first rated voltage.

2. The control device according to claim 1, characterized in that: The balancing resistors connected in parallel to the three or more capacitors connected in series may have different shapes or sizes, or both, of the terminals for connection to the substrate.

3. An air conditioning device, comprising a power device and a control device for controlling the power device, characterized in that: The control device comprises: A first conversion unit, which converts the voltage from the AC power source into a DC; a smoothing unit, which smoothes the converted voltage; and a second conversion unit, which converts the smoothed voltage into an alternating current and applies it to the power device, The smoothing unit includes: three or more capacitors connected in series and a balancing resistor connected in parallel with the capacitors. The first conversion unit, the second conversion unit and the capacitor are mounted on a substrate, and the balancing resistor is externally connected to the substrate using a terminal. Regarding the number of the capacitors connected in series, capacitors with a second rated voltage that is smaller than the number of capacitors with a first rated voltage that is as large as possible that meets the withstand voltage are used so as not to increase the temperature difference between the capacitors, and the number is set to be greater than the number of capacitors with the first rated voltage.

4. The air conditioning device according to claim 3, characterized in that: The balancing resistors connected in parallel to the three or more capacitors connected in series may have different shapes or sizes, or both, of the terminals for connection to the substrate.

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