WO2022162879A1

WO2022162879A1 - Power converter and air-conditioning device

Info

Publication number: WO2022162879A1
Application number: PCT/JP2021/003281
Authority: WO
Inventors: 正城村松; 俊介久保田
Original assignee: 三菱電機株式会社
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2022-08-04
Also published as: JP7395029B2; JPWO2022162879A1

Abstract

Provided is a power converter (50), wherein a converter circuit (20) converts an alternating current voltage into a direct current voltage, and smoothing capacitors (4, 17) smooth the output of the converter circuit (20). An inverter circuit (30) converts the direct current voltage obtained from the smoothing capacitors (4, 17) into an alternating current voltage for a load (40), and a controller (5) controls an operation of at least the inverter circuit (30). The smoothing capacitor (4) is mounted on a main substrate (12), and the smoothing capacitor (17) is mounted on a capacitor substrate (13). The controller (5) determines whether or not to permit an output of a drive signal for driving the inverter circuit (30) on the basis of a detected value of a physical quantity representing an operating state of the smoothing capacitor (17).

Description

Power converter and air conditioner

The present disclosure relates to power converters and air conditioners having smoothing capacitors.

An air conditioner realizes heat exchange between the outside and the room by circulating the refrigerant between the heat exchangers in the indoor unit and the outdoor unit. Refrigerant is mainly compressed by a compressor mounted on the outdoor unit of the air conditioner. The compressor is driven by an inverter circuit. An inverter circuit is a circuit that converts a DC voltage into an AC voltage. A smoothing capacitor is connected in parallel to the inverter circuit for the purpose of stabilizing the bus voltage, which is the input voltage. A smoothing capacitor is required to have a high withstand voltage and a large capacity. Due to this requirement, electrolytic capacitors are often used as smoothing capacitors.

Electrolytic capacitors are larger in size than other types of capacitors. In addition, as the output power of the inverter circuit increases, a large-capacity electrolytic capacitor is required. When increasing the capacity of a capacitor, it is usually connected in parallel. On the other hand, the size of the printed circuit board on which the power conversion main circuit including the inverter circuit is mounted is subject to the physical size limitation of the housing of the air conditioner. In addition, in order to maximize the number of printed circuit boards, the concept of economic dimensions is constrained. The number of pieces is the number of printed circuit boards that can be obtained from one standard board. Due to these restrictions, when the output power of the inverter circuit increases, a problem may arise that the electrolytic capacitors for stabilizing the bus voltage cannot be mounted on a single substrate. To address this problem, Patent Document 1 below discloses a configuration in which a capacitor is mounted on a second substrate different from the first substrate. That is, in the technique of Patent Document 1, a separate substrate on which the capacitor is mounted is provided in order to deal with the restrictions of the substrate.

JP 2014-138442 A

If the main board on which the power conversion main circuit including the inverter circuit is mounted and the capacitor board on which the capacitor is mounted are separated, there is a risk of incorrect wiring connection between the boards. On the other hand, even if the wiring between the main board and the capacitor board is disconnected, the air conditioner may continue to operate as an air conditioner, although the stability of the operation is impaired. The reason for this is that although the bus voltage input to the inverter circuit is insufficiently smoothed by the capacitor, the inverter circuit is supplied with power necessary for operating the air conditioner.

If the air conditioner is operated with poor wiring connection as described above, there is a risk of various problems such as sudden stoppage of operation, occurrence of failure, and deterioration of product life. This type of defect is a defect that becomes apparent after construction of the air conditioner, and is required to be prevented. It is also conceivable to use a method of monitoring the bus voltage. However, when the air conditioner is operating at a light load, the fluctuation of the bus voltage becomes small, so there is a concern that the operation of the device may be judged to be normal. .

The present disclosure has been made in view of the above, and provides a power conversion device in which smoothing capacitors are mounted on a plurality of boards, and which can prevent problems caused by poor wiring connection between boards. for the purpose.

In order to solve the above-described problems and achieve the purpose, the power converter according to the present disclosure includes a converter circuit, a smoothing capacitor, an inverter circuit, and a controller. A converter circuit converts an AC voltage into a DC voltage. A smoothing capacitor smoothes the output of the converter circuit. The inverter circuit converts the DC voltage obtained from the smoothing capacitor into AC voltage for the load. The control unit controls at least the operation of the inverter circuit. The smoothing capacitor has a first capacitor mounted on a first substrate and a second capacitor mounted on a second substrate different from the first substrate. A detected value of the physical quantity representing the operating state of the second capacitor is input to the control unit, and the control unit determines whether or not to permit the output of the drive signal for driving the inverter circuit based on the detected value of the physical quantity.

According to the power converter according to the present disclosure, in a power converter in which smoothing capacitors are mounted on a plurality of boards, it is possible to prevent problems caused by poor wiring connection between boards.

1 is a diagram showing a configuration example of a power converter according to Embodiment 1; FIG. Flowchart for explanation of erroneous connection detection processing in Embodiment 1 FIG. 4 is a diagram showing an example of a hardware configuration that implements the functions of a control unit according to Embodiment 1; The figure which shows the structural example of the power converter device which concerns on Embodiment 2. Flowchart for explanation of erroneous connection detection processing in the second embodiment A diagram showing a configuration example of an air conditioner according to Embodiment 3

A power converter and an air conditioner according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a power converter 50 according to Embodiment 1. As shown in FIG. The power converter 50 according to Embodiment 1 converts the power supply voltage applied from the AC power supply 1 into an AC voltage having a desired amplitude and frequency, and applies the AC voltage to the load 40 . The load 40 has a motor 7 . An example of the load 40 is an air conditioner, and an example of the motor 7 is a compressor motor or a fan motor mounted on the air conditioner.

In FIG. 1, the components of the power conversion main circuit, which is the main circuit in the power converter 50, are mounted separately on a main board 12 that is a first board and a capacitor board 13 that is a second board. there is Specifically, the main board 12 is mounted with a converter circuit 20 , a smoothing capacitor 4 that is a first capacitor, an inverter circuit 30 , and a control section 5 . A smoothing capacitor 17 that is a second capacitor is mounted on the capacitor substrate 13 . A reference terminal (not shown) of the control unit 5 is connected to the same potential as the negative electrode of the smoothing capacitor 4 .

The smoothing capacitor 17 is provided to increase the capacity of the smoothing capacitor 4 and is electrically connected in parallel with the smoothing capacitor 4 . When the load 40 is an air conditioner, a voltage of several hundred volts is applied to the

smoothing capacitors

4 and 17, so a large-capacity capacitor is required. Therefore, the

smoothing capacitors

4 and 17 are often electrolytic capacitors.

By providing the smoothing capacitor 17, the DC voltage applied to the inverter circuit 30 is stabilized. Further, when the smoothing capacitor 17 is provided, the ripple of the current flowing in and out of the smoothing capacitor 4 is dispersed. Therefore, heat generation of the smoothing capacitor 4 is suppressed as compared with the case where the smoothing capacitor 17 is not provided.

The converter circuit 20 converts the AC voltage applied from the AC power supply 1 into a DC voltage.

Smoothing capacitors

4 and 17 smooth the output of converter circuit 20 . Inverter circuit 30 converts the DC voltage obtained from smoothing

capacitors

4 and 17 into AC voltage to load 40 . The control unit 5 controls operations of the converter circuit 20 and the inverter circuit 30 .

The converter circuit 20 has a rectifier circuit 2 and a booster circuit 3 . The rectifier circuit 2 is configured using a plurality of bridge-connected rectifier diodes 2a. The arrangement and connection of the rectifier diodes 2a in the rectifier circuit 2 are well known, and the description thereof is omitted here. The booster circuit 3 has a function of boosting the rectified voltage output by the rectifier circuit 2 .

The booster circuit 3 has a reactor 8 , a switching element 9 , a gate drive circuit 10 , and a backflow prevention diode 11 . A reference terminal (not shown) of the gate drive circuit 10 is grounded. The switching element 9 and the backflow prevention diode 11 are arranged on the DC bus 22a on the high potential side. The reactor 8 has one end connected to the rectifier circuit 2 and the other end connected to the anode of the backflow prevention diode 11 . The switching element 9 has one end connected to the connection point between the reactor 8 and the backflow prevention diode 11, and the other end connected to the low potential side DC bus 22b. DC bus 22b is grounded.

An example of the switching element 9 is an IGBT (Insulated Gate Bipolar Transistor), and another example of the switching element 9 is a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). When the switching element 9 is an IGBT, one end is the collector and the other end is the emitter. When the switching element 9 is a MOSFET, one end is the drain and the other end is the source.

In the booster circuit 3 , the switching element 9 is controlled to be on or off by the drive signal output from the gate drive circuit 10 . The operation of the gate drive circuit 10 is controlled by the controller 5 . That is, the ON operation or OFF operation of the switching element 9 is controlled based on the control signal output from the control section 5 .

When the switching element 9 is turned on, the rectified voltage is short-circuited via the reactor 8. This operation is called "power supply short-circuit operation". When the switching element 9 is controlled to be off, the rectified voltage is applied to the smoothing

capacitors

4 and 17 via the reactor 8 and the backflow prevention diode 11 . This operation is normal commutation operation. At this time, if energy is accumulated in the reactor 8 , a voltage obtained by adding the rectified voltage and the voltage generated in the reactor 8 is applied to the smoothing

capacitors

4 and 17 .

The booster circuit 3 boosts the rectified voltage by alternately repeating the power supply short-circuit operation and the rectification operation. This operation is called a "boost operation". The boosting operation boosts the voltages of the smoothing

capacitors

4 and 17 to a voltage higher than the power supply voltage, which is the voltage of the AC power supply 1 . Moreover, the boosting operation improves the power factor of the current flowing between AC power supply 1 and converter circuit 20 . On the other hand, when the switching element 9 is always off, the voltage output from the rectifier circuit 2 is output without being boosted. If there is no need to boost the rectified voltage, the booster circuit 3 may be omitted.

The inverter circuit 30 converts the DC voltage obtained from the smoothing

capacitors

4 and 17 into AC voltage for the load 40 and applies it to the motor 7 of the load 40 . The inverter circuit 30 is configured using a plurality of switching elements 6 in which transistor elements and diodes are connected in antiparallel. The illustrated motor 7 is a three-phase motor, and the inverter circuit 30 includes three legs in which the switching elements 6 of the upper and lower arms are connected in series, and the three legs are connected in parallel. Six switching elements 6 forming three legs are often sealed in one package and configured as an IPM (Intelligent Power Module) module, but the present invention is not limited to this. Each of the six switching elements 6 may be an independent discrete component.

When the inverter circuit 30 is an IPM, the driving signal for driving the switching element 6 in the IPM is output from the control section 5. That is, the ON operation or OFF operation of the switching element 6 is controlled by the drive signal output from the controller 5 .

The main board 12 has a first terminal 14a, a second terminal 14b, and a sixth terminal 14c. The capacitor substrate 13 has a third terminal 15a, a fourth terminal 15b, and a fifth terminal 15c. The capacitor board 13 also has

resistors

16a and 16b, which are voltage dividing resistors, connected in series between the third terminal 15a and the fourth terminal 15b.

The first terminal 14a is connected to the same potential as the positive electrode of the smoothing capacitor 4. A second terminal 14 b is connected to the same potential as the negative electrode of the smoothing capacitor 4 . A third terminal 15 a is connected to the same potential as the positive electrode of the smoothing capacitor 17 . The first terminal 14a and the third terminal 15a are connected by a wiring 19a which is a first wiring. A fourth terminal 15 b is connected to the same potential as the negative electrode of the smoothing capacitor 17 . The second terminal 14b and the fourth terminal 15b are connected by a wiring 19b, which is a second wiring. The fifth terminal 15c is connected to the same potential as the connection point between the

resistors

16a and 16b. The sixth terminal 14c and the fifth terminal 15c are connected by a wiring 19c which is a third wiring. A sixth terminal 14 c is connected to the control unit 5 .

Although the number of resistors connected in series between the third terminal 15a and the fourth terminal 15b is two in FIG. 1, the present invention is not limited to this. Any configuration may be used as long as it can obtain a divided voltage of the voltage of the smoothing capacitor 17 . That is, the number of resistors should be plural. When the number of resistors is 3 or more, the resistor located on the high potential side is called a "first resistor" and the resistor located on the low potential side as viewed from the connection point of the resistors for obtaining the divided voltage. is sometimes called a "second resistance".

As described above, in the power converter 50 according to Embodiment 1, the components of the smoothing capacitors for applying a stable DC voltage to the inverter circuit 30 are separately mounted on the main substrate 12 and the capacitor substrate 13. . For this reason, there is a possibility that an error may occur in the connection between the main board 12 and the capacitor board 13 . However, even if there is an error in the connection between the main substrate 12 and the capacitor substrate 13 and the smoothing

capacitors

4 and 17 are not electrically connected in parallel, the circuit configuration for applying the DC voltage to the inverter circuit 30 is It will be established. A case where the power conversion device 50 is used in an air conditioner will be considered below.

When the air conditioner is operated in a state where the connection between the main board 12 and the capacitor board 13 is incorrect, the smaller the capacity of the smoothing capacitor 4 or the larger the current flowing through the motor 7, which is a compressor motor, the more the air conditioner is operated. The voltage fluctuation of the smoothing capacitor 4 increases. However, when the air conditioner is operating at a light load, the voltage fluctuation of the smoothing capacitor 4 becomes small, and it may be determined that the operation of the device is normal, and the motor 7 continues to be driven. If the motor 7 continues to be driven, more ripple current flows through the smoothing capacitor 4 than expected, and the temperature of the smoothing capacitor 4 rises. An electrolytic capacitor, which is often used as the smoothing capacitor 4, is a limited-life component. Electrolytic capacitors are generally said to follow the Arrhenius equation, which states that a temperature rise of 10° C. halves the life of the capacitor. Therefore, if there is an error in the connection between the main substrate 12 and the capacitor substrate 13, there is a concern that the motor 7 cannot be driven normally, and even if the motor 7 can be driven, the life of the product will be significantly deteriorated. For this reason, the power converter 50 according to the first embodiment is provided with a function of detecting erroneous connection between the main board 12 and the capacitor board 13 .

Next, the erroneous connection detection process in Embodiment 1 will be described. FIG. 2 is a flowchart for explaining erroneous connection detection processing according to the first embodiment. The processing in FIG. 2 is performed under the control of the control section 5 .

First, the control unit 5 acquires voltage information of the fifth terminal 15c of the capacitor substrate 13 (step S11).

As described above, the fifth terminal 15c is connected to the connection point between the

resistors

16a and 16b. Here, let the resistance values of the

resistors

16a and 16b be "Ra" and "Rb" respectively, and the voltage across the smoothing capacitor 17 be "Va". At this time, the voltage Vc of the fifth terminal 15c based on the fourth terminal 15b can be expressed by the following equation (1).

　Vc=Va×Rb/(Ra+Rb)...(1)

In Embodiment 1, the voltage Vc of the fifth terminal 15c with respect to the fourth terminal 15b is an example of a physical quantity representing the operating state of the smoothing capacitor 17.

As described above, the sixth terminal 14c is connected to the fifth terminal 15c by wiring, and is also connected to the control section 5. Thereby, the control unit 5 can always acquire the voltage Vc of the fifth terminal 15c, which is the voltage information of the smoothing capacitor 17, via the sixth terminal 14c.

The control unit 5 determines whether the acquired voltage information is within a predetermined range (step S12). If the obtained voltage information is not within the predetermined range (step S12, No), the control unit 5 returns to step S11 and continues the voltage information obtaining process. On the other hand, when the acquired voltage information is within the predetermined range (step S12, Yes), the output of the drive signal to the inverter circuit 30 is permitted (step S13), and the power converter 50 shifts to the normal control mode (step S14). As a result, the drive signal generated inside the control unit 5 is output to the inverter circuit 30, and the inverter circuit 30 starts operating.

When the connection of the wiring 19a connecting the first terminal 14a and the third terminal 15a is defective or disconnected, there is no current path for charging the smoothing capacitor 17, so the smoothing capacitor 17 is not charged. Therefore, the voltage Va across the smoothing capacitor 17 is "0 V", and the voltage Vc at the fifth terminal 15c, which is the voltage information input to the control section 5, is also "0 V". Therefore, the drive signal for driving the inverter circuit 30 is not output from the controller 5 because the acquired voltage information is not within the predetermined range. The same applies when the connection of the wiring 19b connecting the second terminal 14b and the fourth terminal 15b is defective or disconnected.

Further, when the connection of the wiring 19c connecting the sixth terminal 14c and the fifth terminal 15c is defective or disconnected, the smoothing capacitor 17 is charged unless the

wiring

19a and 19b are defectively connected. be done. However, since the voltage information of the smoothing capacitor 17 is not transmitted to the control section 5, the recognition value of the control section 5 becomes "0V". Therefore, since the voltage information recognized by the controller 5 is not within the predetermined range, the drive signal for driving the inverter circuit 30 is not output from the controller 5 .

Although each terminal for connecting the main board 12 and the capacitor board 13 is shown in FIG. 1 as an independent form, it is not limited to this. Each terminal on the same substrate can also be grouped with a connector having multiple poles. At this time, for example, the first terminal 14a, the second terminal 14b, and the sixth terminal 14c may be used as one connector. Alternatively, the first terminal 14a and the second terminal 14b may be combined into one connector, and the sixth terminal 14c may be an independent connector, which may be a total of two connectors. Also, other forms may be used, and the combination is arbitrary.

Also, the smoothing capacitor 17 generally uses an electrolytic capacitor in many cases. Since electrolytic capacitors have polarities, if a reverse polarity voltage is applied to the electrolytic capacitors, the vaporized electrolytic solution may spout out due to rupture or opening of the expansion valve. Therefore, it is desirable to take further measures to prevent erroneous connection of polarity.

First, it is desirable to describe the possibility of the above-mentioned erroneous connection occurring in the connection between boards in the construction procedure manual, etc. By describing it in the construction procedure manual or the like, even if there is a defect in the wiring connection between the main board 12 and the capacitor board 13 at the time of manufacturing the product, it becomes possible to repair it at the time of construction.

Further, for example, it is conceivable to use different wiring colors for the wiring 19a connecting the first terminal 14a and the third terminal 15a and the wiring 19b connecting the second terminal 14b and the fourth terminal 15b. be done. According to this example, it is possible to call attention to the contractor.

In addition, for example, the first terminal 14a and the third terminal 15a are terminals fastened with screws, and the second terminal 14b and the fourth terminal 15b are fitted with male and female connectors. good too. Alternatively, a combination of terminals having different corresponding screw diameters may be used between these terminals, or a structure in which different combinations cannot be physically connected may be used. That is, for the combination of the first terminal 14a and the third terminal 15a and the combination of the second terminal 14b and the fourth terminal 15b, different combinations of these terminals cannot be physically connected. structure. With such a structure, the possibility of erroneous connection occurring can be further reduced.

Also, as described above, the first terminal 14a and the third terminal 15a are connected by the wiring 19a, and the second terminal 14b and the fourth terminal 15b are connected by the wiring 19b. At this time, for example, at least one of the

wirings

19a and 19b is connected to the terminal pair of the first terminal 14a and the third terminal 15a and the terminal pair of the second terminal 14b and the fourth terminal 15b. may be configured so that it cannot be connected to a terminal pair that is not supposed to be connected. Even with this configuration, it is possible to further reduce the possibility of erroneous connection occurring.

Next, a hardware configuration that implements the functions of the control unit 5 in Embodiment 1 will be described. FIG. 3 is a diagram showing an example of a hardware configuration that implements the functions of the control unit 5 according to the first embodiment.

When realizing the function of the control unit 5 in Embodiment 1, as shown in FIG. The configuration may include an interface 204 for performing the determination and a display 205 for displaying the determination result.

The processor 200 may be arithmetic means such as an arithmetic unit, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). The memory 202 includes nonvolatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (registered trademark) (Electrically EPROM), Magnetic discs, flexible discs, optical discs, compact discs, mini discs, and DVDs (Digital Versatile Discs) can be exemplified.

The memory 202 stores a program for executing the functions of the control unit 5 in Embodiment 1 and a judgment value for judging incorrect connection. Processor 200 exchanges necessary information via interface 204, processor 200 executes a program stored in memory 202, and processor 200 refers to the determination value stored in memory 202, thereby correcting the error described above. Perform connection detection processing. Results of operations by processor 200 may be stored in memory 202 . Also, the processing result of the processor 200 can be displayed on the display 205 . Note that the display device 205 may be provided outside the control unit 5 .

A typical example of the display 205 is an LED (Light Emitting Diode) display or a 7-segment display. If the acquired voltage information is not within a predetermined range, the construction contractor is simply and quickly notified of the presence or absence of an abnormality by lighting an LED or displaying an error code on a 7-segment display. can be done. A liquid crystal display or the like may be used in place of these displays or in combination with these displays.

With the mechanism described above, the inverter circuit 30 can be driven only when the main board 12 and the capacitor board 13 are correctly connected by wiring and the smoothing capacitor 17 is charged to the set voltage. As a result, the contractor can recognize poor connection between the main board 12 and the capacitor board 13 when performing a test run.

As described above, in the power converter according to Embodiment 1, the smoothing capacitor has the first and second capacitors, the first capacitor is mounted on the first substrate, and the second capacitor is It is mounted on a second substrate different from the first substrate. The control unit determines whether or not to permit the output of the drive signal for driving the inverter circuit based on the detected value of the physical quantity representing the operating state of the second capacitor. As a result, it is possible to obtain the effect of being able to prevent problems caused by poor wiring connection between substrates. In the first embodiment, the detected value of the physical quantity can be the voltage of the fifth terminal of the capacitor substrate, that is, the divided voltage of the voltage across the second capacitor. Thereby, the detected value of the physical quantity can be obtained easily and reliably.

Further, according to the power conversion device according to Embodiment 1, when the detected value of the physical quantity is not within the predetermined range, information to that effect can be displayed on the display. As a result, it is possible to simply and quickly inform the contractor who installs the product on which the power conversion device according to the first embodiment is installed, whether or not there is an erroneous wiring.

Embodiment 2.
FIG. 4 is a diagram showing a configuration example of a power conversion device 50A according to Embodiment 2. As shown in FIG. In power converter 50A according to Embodiment 2, main board 12 is replaced with main board 12A, and capacitor board 13 is replaced with capacitor board 13A in the configuration of power converter 50 according to Embodiment 1 shown in FIG. , and the controller 5 is replaced with the controller 5A. The sixth terminal 14c is removed from the main board 12A, and the fifth terminal 15c is removed from the capacitor board 13A. Further, the wiring 19c is removed between the main substrate 12A and the capacitor substrate 13A, while the current sensor 18 is provided on the wiring 19a. Other configurations are the same as or equivalent to those of the power conversion device 50 shown in FIG. 1, and the same or equivalent components are denoted by the same reference numerals, and overlapping descriptions are omitted.

In the configuration of FIG. 4, the current sensor 18 detects the current flowing through the wiring 19a, that is, the current flowing between the first terminal 14a and the third terminal 15a. Current information detected by the current sensor 18 is input to the controller 5A. As the current sensor 18, a direct current transformer (DCCT) or an alternating current transformer (ACCT) can be used.

Next, the erroneous connection detection process in Embodiment 2 will be described. FIG. 5 is a flowchart for explaining erroneous connection detection processing according to the second embodiment. The processing in FIG. 5 is performed under the control of the control section 5 .

First, the control unit 5 acquires current information detected by the current sensor 18 (step S21). In Embodiment 2, the current flowing through the wiring 19a is an example of a physical quantity representing the operating state of the smoothing capacitor 17. FIG.

As described above, the detected value of the current sensor 18 is configured to be input to the control section 5. Thereby, the control unit 5 can constantly acquire current information representing the operating state of the smoothing capacitor 17 via the current sensor 18 .

The control unit 5 determines whether the acquired current information is within a predetermined range (step S22). If the acquired current information is not within the predetermined range (step S22, No), the controller 5 returns to step S21 and continues the current information acquisition process. On the other hand, when the acquired current information is within the predetermined range (step S22, Yes), the output of the drive signal to the inverter circuit 30 is permitted (step S23), and the power converter 50 shifts to the normal control mode (step S24). As a result, the drive signal generated inside the control unit 5 is output to the inverter circuit 30, and the inverter circuit 30 starts operating.

When the connection of the wiring 19a connecting the first terminal 14a and the third terminal 15a is defective or disconnected, there is no current path for charging the smoothing capacitor 17, so the smoothing capacitor 17 is not charged. Therefore, no charging current flows through the smoothing capacitor 17, and the detection value of the current sensor 18 input to the control section 5 is "0 A". Therefore, the drive signal for driving the inverter circuit 30 is not output from the controller 5 because the acquired current information is not within the predetermined range. The same applies when the connection of the wiring 19b connecting the second terminal 14b and the fourth terminal 15b is defective or disconnected.

Although the current sensor 18 is configured to detect the current flowing through the wiring 19a in FIG. 4, it is not limited to this. Instead of this configuration, the current sensor 18 may be configured to detect current flowing between the wiring 19b, that is, the second terminal 14b and the fourth terminal 15b.

As described above, in the power converter according to Embodiment 2, the smoothing capacitor has the first and second capacitors, the first capacitor is mounted on the first substrate, and the second capacitor is It is mounted on a second substrate different from the first substrate. The control unit determines whether or not to permit the output of the drive signal for driving the inverter circuit based on the detected value of the physical quantity representing the operating state of the second capacitor. Thereby, the same effects as those of the first embodiment can be obtained. In the second embodiment, the detected value of the physical quantity is the current flowing between the first terminal of the main board and the third terminal of the capacitor board, or the current flowing between the second terminal of the main board and the fourth terminal of the capacitor board. can be a current flowing between the terminals of Thereby, the detected value of the physical quantity can be obtained easily and reliably.

Further, according to the power conversion device according to Embodiment 2, when the detected value of the physical quantity is not within the predetermined range, it is possible to display information to that effect on the display. As a result, it is possible to easily and quickly notify the contractor who installs the product on which the power conversion device according to the second embodiment is installed, whether or not there is an erroneous wiring.

Embodiment 3.
Embodiment 3 describes an example in which the power converter described in

Embodiments

1 and 2 is applied to an air conditioner. FIG. 6 is a diagram showing a configuration example of the air conditioner 100 according to Embodiment 3. As shown in FIG. The air conditioner 100 includes an outdoor unit 67 , an indoor unit 68 and an air conditioning controller 69 . The outdoor unit 67 is connected to the AC power supply 1 . The outdoor unit 67 includes a power conversion device 50 , a compressor 60 , a four-way valve 62 , a heat source side heat exchanger 63 , and a heat source side expansion valve 64 . The indoor unit 68 includes a load side expansion valve 65 and a load side heat exchanger 66 . The compressor 60 includes a compression element 61 driven by the motor 7 . Although FIG. 6 exemplifies the power conversion device 50, it may be replaced with the power conversion device 50A described in the second embodiment.

In the air conditioner 100, the compressor 60, the four-way valve 62, the heat source side heat exchanger 63, the heat source side expansion valve 64, the load side expansion valve 65, the load side heat exchanger 66, the four way valve 62, and the compressor 60 A refrigerant circuit connected in order by a refrigerant pipe 70 is configured. In the air conditioner 100, a refrigeration cycle is established by the refrigerant flowing through the refrigerant circuit. The air conditioner 100 compresses the refrigerant in the refrigeration cycle with the compressor 60 . Although not shown in FIG. 6, an accumulator for storing excess refrigerant may be provided on the suction side of the compressor 60 . In controlling the refrigerant circuit, the air conditioning control unit 69 controls the four-way valve 62 , the heat source side expansion valve 64 and the load side expansion valve 65 . Note that the configuration of the refrigeration cycle shown in FIG. 6 is an example, and the configuration of the refrigeration cycle may not necessarily be the same.

Next, the operation of the air conditioner 100 shown in FIG. 6 will be described using the cooling operation as an example. Although the details of the heating operation are omitted, the heating operation can also be realized by switching the flow path in the four-way valve 62 . During the cooling operation, the four-way valve 62 is set in advance so that the refrigerant discharged from the compressor 60 flows toward the heat source side heat exchanger 63 and the refrigerant discharged from the load side heat exchanger 66 flows toward the compressor 60 . It is assumed that the road is switched.

By driving the motor 7 by the electric power conversion device 50, the compression element 61 connected to the motor 7 compresses the refrigerant into a high-temperature and high-pressure refrigerant. Compressor 60 discharges a high-temperature, high-pressure refrigerant. The high-temperature, high-pressure refrigerant discharged from the compressor 60 passes through the four-way valve 62 and flows into the heat source side heat exchanger 63, where it exchanges heat with the outside air and radiates heat. The refrigerant flowing out of the heat source side heat exchanger 63 is expanded and decompressed in the heat source side expansion valve 64 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant. The refrigerant that has become a low-temperature, low-pressure gas-liquid two-phase refrigerant is expanded and decompressed in the load-side expansion valve 65, flows into the load-side heat exchanger 66, exchanges heat with the air in the air-conditioned space, and evaporates. It flows out from the load-side heat exchanger 66 as a low-pressure refrigerant. The refrigerant that has flowed out of the load-side heat exchanger 66 passes through the four-way valve 62, is sucked into the compressor 60, and is compressed again. The above operations are repeated in the air conditioner 100 .

For the purpose of mainly cooling the inverter circuit 30 of the power converter 50, the main substrate 12 on which the inverter circuit 30 is mounted may be brought into contact with the cooling plate. Furthermore, the cooling plate may be brought into contact with the refrigerant pipe 70 so that the refrigerant flowing through the refrigerant pipe 70 absorbs the heat generated in the inverter circuit 30 . In this way, the temperature rise of the inverter circuit 30 can be efficiently suppressed.

In addition, the air conditioner 100 shown in FIG. 6 is configured such that the heat source side expansion valve 64 is provided in the outdoor unit 67 and the load side expansion valve 65 is provided in the indoor unit 68 . These configurations are for enabling the cooling capacity of the power converter 50 to be controlled independently by the two expansion valves, the heat source side expansion valve 64 and the load side expansion valve 65, respectively. These configurations are suitable for finely controlling the refrigerant, and can efficiently control the refrigerant. Note that the configuration of FIG. 6 is an example, and the configuration does not necessarily have to include two expansion valves.

Embodiment 3 shows an example in which the

power converters

50 and 50A according to

Embodiments

1 and 2 are applied to the air conditioner 100, but the present invention is not limited to this. The

power converters

50 and 50A according to

Embodiments

1 and 2 can be applied not only to the air conditioner 100 but also to equipment having a refrigeration cycle such as a heat pump device and a refrigeration system. In addition, it can be applied to products that do not have a compressor, such as dryers, washing machines, and vacuum cleaners, and can also be applied to fan motors.

As described above, according to the air conditioner according to Embodiment 3, by applying the power converter according to

Embodiments

1 and 2, the capacity of the air conditioner can be increased, and the air conditioning capacity can be increased. It is possible to achieve an air conditioner with a high coefficient and a small loss.

The configurations shown in the above embodiments are only examples, and can be combined with other known techniques, or can be combined with other embodiments, without departing from the scope of the invention. It is also possible to omit or change part of the configuration.

1 AC power supply, 2 rectifier circuit, 2a rectifier diode, 3 booster circuit, 4, 17 smoothing capacitor, 5, 5A control unit, 6, 9 switching element, 7 motor, 8 reactor, 10 gate drive circuit, 11 backflow prevention diode , 12, 12A main board, 13, 13A capacitor board, 14a first terminal, 14b second terminal, 14c sixth terminal, 15a third terminal, 15b fourth terminal, 15c fifth terminal, 16a , 16b resistance, 18 current sensor, 19a, 19b, 19c wiring, 20 converter circuit, 22a, 22b DC bus, 30 inverter circuit, 40 load, 50, 50A power converter, 60 compressor, 61 compression element, 62 four-way valve , 63 heat source side heat exchanger, 64 heat source side expansion valve, 65 load side expansion valve, 66 load side heat exchanger, 67 outdoor unit, 68 indoor unit, 69 air conditioning control unit, 70 refrigerant pipe, 100 air conditioner, 200 Processor, 202 memory, 204 interface, 205 display.

Claims

A converter circuit for converting an AC voltage to a DC voltage, a smoothing capacitor for smoothing the output of the converter circuit, an inverter circuit for converting the DC voltage obtained from the smoothing capacitor to an AC voltage for a load, and at least the inverter circuit. A power conversion device comprising a control unit that controls operation,
The smoothing capacitor has a first capacitor mounted on a first substrate and a second capacitor mounted on a second substrate different from the first substrate,
a detected value of a physical quantity representing the operating state of the second capacitor is input to the control unit;
The power conversion device, wherein the control unit determines whether or not to permit output of a drive signal for driving the inverter circuit based on the detected value of the physical quantity.
The power converter according to claim 1, wherein, when the detected value of the physical quantity is not within a predetermined range, the control unit displays information to that effect on the display.
the first substrate has first, second and sixth terminals;
the second substrate has third, fourth and fifth terminals and a plurality of resistors connected in series between the third terminal and the fourth terminal;
The first terminal is connected to the same potential as the positive electrode of the first capacitor,
the second terminal is connected to the same potential as the negative electrode of the first capacitor;
the third terminal is connected to the same potential as the positive electrode of the second capacitor and is connected to the first terminal by a first wiring;
the fourth terminal is connected to the same potential as the negative electrode of the second capacitor and is connected to the second terminal by a second wiring;
The fifth terminal is connected to the same potential as a connection point between a first resistor and a second resistor among the plurality of resistors, and is connected to the sixth terminal by a third wiring. ,
the detected value of the physical quantity is a voltage detected at the connection point;
The power converter according to claim 1 or 2, wherein the control unit permits the output of the drive signal when the voltage is within a predetermined range.
The first substrate has first and second terminals,
the second substrate has third and fourth terminals;
The first terminal is connected to the same potential as the positive electrode of the first capacitor,
the second terminal is connected to the same potential as the negative electrode of the first capacitor;
the third terminal is connected to the same potential as the positive electrode of the second capacitor and is connected to the first terminal by a first wiring;
the fourth terminal is connected to the same potential as the negative electrode of the second capacitor and is connected to the second terminal by a second wiring;
the detected value of the physical quantity is a current flowing between the first terminal and the third terminal or a current flowing between the second terminal and the fourth terminal;
The power converter according to claim 1 or 2, wherein the control unit permits the output of the drive signal when the current is within a predetermined range.
a terminal pair consisting of the first terminal and the third terminal connected to the first terminal by the first wiring; and the second terminal and the second terminal connected to the second terminal. At least one of the first wiring and the second wiring is configured so as not to be connected to a terminal pair that is not supposed to be connected with respect to the terminal pair formed by the fourth terminal connected by wiring. The power converter according to claim 3 or 4.
For the combination of the first terminal and the third terminal and the combination of the second terminal and the fourth terminal, the first to fourth terminals are physically connected in different combinations. 5. The power conversion device according to claim 3 or 4, wherein the structure is such that it cannot
An air conditioner comprising the power converter according to any one of claims 1 to 6.