Heat exchange system and power conversion device

Abstract

The purpose of the present invention is to provide a heat exchange system capable of reducing cost when replacing a board of a power conversion device.　This heat exchange system according to the present disclosure comprises: a water heat exchanger; a water circulation pump; a power conversion device that is electrically connected to the water circulation pump; a water use device; and a water pipe that connects each device. The power conversion device comprises: a main board having an AC voltage supply unit in which an AC voltage is inputted from an AC power supply, and when the water circulation pump is an AC drive water circulation pump, supplies the AC voltage to the AC drive water circulation pump, and a control unit that, when the water circulation pump is a DC drive water circulation pump, determines a DC voltage command value to be input to the DC drive water circulation pump; and a relay board that is a different board separated from the main board, and has a DC voltage conversion unit that converts the AC voltage into a DC voltage, a voltage adjustment unit that adjusts the voltage so that the value of the DC voltage matches the DC voltage command value, and a DC voltage supply unit that supplies the adjusted DC voltage to the DC drive water circulation pump.

Description

Heat exchange system and power conversion device

[0001] The present disclosure relates to a heat exchange system and a power conversion device.

[0002] Conventionally, an operation control method has been proposed for controlling an electrical device by connecting a power conversion device to the electrical device. The invention described in Patent Document 1 connects a switching power supply having a diode bridge and an electrolytic capacitor to an AC power source, and then connects the switching power supply to a water circulation pump driven by a DC voltage. According to the invention described in Patent Document 1, the water circulation pump driven by a DC voltage can be driven by the voltage input from the AC power source.

[0003] JP 2009-134564 A

[0004] Since the switching power supply corresponding to the power conversion device in Patent Document 1 is formed on a single printed circuit board, if a part of the switching circuit fails, the entire printed circuit board must be replaced. Therefore, the invention described in Patent Document 1 has a problem in that the cost of replacing the board of the power conversion device is high.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to reduce the cost involved in replacing a board in a power conversion device.

[0006] In order to solve the above problems, the heat exchange system of the present disclosure includes a water heat exchanger that changes the temperature of water, a water circulation pump that sends water to the water heat exchanger, a power conversion device electrically connected to the water circulation pump, a water utilization device that utilizes the water flowing out of the water heat exchanger, and water piping that connects the water circulation pump, the water heat exchanger, and the water utilization device to form a water circuit, and the power conversion device receives AC voltage from an AC power source and, if the water circulation pump is an AC-driven water circulation pump that is driven by AC voltage, supplies the AC voltage to the AC-driven water circulation pump. The water circulation pump is provided with: a main board having an AC voltage supply unit that supplies AC voltage to the water circulation pump and a control unit that determines a DC voltage command value to be input to the DC-driven water circulation pump if the water circulation pump is a DC-driven water circulation pump that uses a DC voltage as a power source; and a relay board that is separate from the main board and has a DC voltage conversion unit that converts AC voltage to DC voltage, a voltage adjustment unit that adjusts the voltage so that the value of the DC voltage converted by the DC voltage conversion unit matches the DC voltage command value, and a DC voltage supply unit that supplies the DC voltage adjusted by the voltage adjustment unit to the DC-driven water circulation pump.

[0007] The power conversion device of the present disclosure also includes a main board having an AC voltage supply unit that receives an AC voltage output from an AC power source and supplies the AC voltage to AC-driven equipment that uses the AC voltage as a power source, and a control unit that determines a DC voltage command value to be input to the controlled equipment when the controlled equipment is a DC-driven equipment that uses a DC voltage as a power source, and an intermediate board that is separate from the main board and has a DC voltage conversion unit that converts the AC voltage into a DC voltage, a voltage adjustment unit that adjusts the voltage so that the value of the DC voltage converted by the DC voltage conversion unit matches the DC voltage command value, and a DC voltage supply unit that supplies the DC voltage adjusted by the voltage adjustment unit to the DC-driven equipment.

[0008] The heat exchange system and power conversion device of the present disclosure have the advantage of being able to reduce the cost involved in replacing a substrate in the power conversion device.

[0009] 1 is a circuit diagram illustrating an overview of a heat pump system according to a first embodiment of the present disclosure. FIG. 2 is a block diagram illustrating a configuration of a power conversion device of the heat pump system according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating an example of a PWM signal generated by a control unit 312 in a power conversion device 30 of a heat pump system 100 according to the first embodiment of the present disclosure. FIG. 4 is a block diagram illustrating a configuration of a water circulation pump and a power conversion device in a case where the water circulation pump is an AC-driven device in the heat pump system according to the first embodiment of the present disclosure. FIG. 5 is a block diagram illustrating a configuration of a water circulation pump and a power conversion device in a case where the water circulation pump is a DC-driven device in the heat pump system according to the first embodiment of the present disclosure. FIG. 6 is a block diagram illustrating a functional configuration of a control unit of the heat pump system according to the first embodiment of the present disclosure. FIG. 7 is a block diagram illustrating a hardware configuration of a control unit of the heat pump system according to the first embodiment of the present disclosure. FIG. 8 is a circuit diagram illustrating an overview of a heat pump system according to a second embodiment of the present disclosure. FIG. 9 is a block diagram illustrating a configuration of a water circulation pump and a power conversion device in a case where the water circulation pump is a DC-driven device in the heat pump system according to the second embodiment of the present disclosure. FIG. 10 is a block diagram illustrating a functional configuration of a control unit of the heat pump system according to the second embodiment of the present disclosure.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the following embodiments, and modifications or omissions may be made without departing from the spirit of the present disclosure.

[0011] First Embodiment. Figure 1 is a circuit diagram showing an overview of a heat pump system 100 according to a first embodiment of the present disclosure. The overview of the heat pump system 100 will be described using Figure 1. In Figure 1, the flow of refrigerant in the refrigerant circuit 10 during cooling operation is indicated by dashed arrows, and the flow of refrigerant during heating operation is indicated by dashed arrows. Also in Figure 1, the flow of water in the water circuit 20 is indicated by solid arrows.

[0012] As shown in FIG. 1 , the heat pump system 100 includes a refrigerant circuit 10 through which a refrigerant circulates and a water circuit 20 through which water circulates. The heat pump system 100 also includes a power conversion device 30. The power conversion device 30 is connected to an AC power supply 29. The heat pump system 100 performs heating and cooling operations. Note that the heating operation includes not only the heating used in air conditioners but also hot water supply, which adds heat to water to produce hot water. The cooling operation includes not only the cooling used in air conditioners but also removing heat from water to produce cold water, and refrigeration.

[0013] The refrigerant circuit 10 is formed by connecting a compressor 11 , an air heat exchanger 12 , a blower 13 , a pressure reducing device 14 , and a water heat exchanger 15 by refrigerant piping 16 .

[0014] The compressor 11 compresses and discharges the refrigerant that has flowed in by rotating a drive shaft of a motor built into the compressor 11. The air heat exchanger 12 exchanges heat between air and the refrigerant. The blower 13 blows air to the air heat exchanger 12. The pressure reducing device 14 is a device that reduces the pressure of the refrigerant, and is specifically an expansion valve. The water heat exchanger 15 exchanges heat between the refrigerant and water, which is the object of heat exchange.

[0015] The water circuit 20 includes a first water circuit 21 and a second water circuit 22. The first water circuit 21 is formed by connecting the water heat exchanger 15, a tank 23, a valve 24, and a water circulation pump 25 via water piping 26. The second water circuit 22 is formed by connecting the water heat exchanger 15, a water-using device 27, the valve 24, and the water circulation pump 25 via water piping 26. After flowing out of the water heat exchanger 15, the water circulating through the water piping 26 is branched into the first water circuit 21 and the second water circuit 22.

[0016] The first water circuit 21 is a circuit for circulating water from a tank 23 to the water circuit 20. The tank 23 stores water. The valve 24 controls the flow rate and direction of water flowing through a water pipe 26.

[0017] The water circulation pump 25 circulates water through the water circuit 20. The water circulation pump 25 uses a voltage input from the power conversion device 30 to rotate the drive shaft of a motor built into the water circulation pump 25, thereby circulating the water.

[0018] The second water circuit 22 is a circuit for supplying water to a water-using device 27. The water-using device 27 is a device that uses the water that has undergone heat exchange in the water heat exchanger 15. The water-using device 27 is, for example, an air conditioner, a water heater, or a refrigerator.

[0019] Next, the operation of the heat pump system 100 during cooling operation will be described using Figure 1. The gas-phase refrigerant, which has reached high temperature and pressure in the compressor 11, is discharged from the compressor 11 and exchanges heat with air in the air heat exchanger 12, which functions as a condenser, to become a liquid refrigerant. The liquid refrigerant flowing out of the air heat exchanger 12 is depressurized in the pressure reducing device 14 to become a two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flowing out of the pressure reducing device 14 is heated by heat exchange with water in the water heat exchanger 15, which functions as an evaporator. As the refrigerant absorbs heat, the water circulating through the water circuit 20 is cooled and used for cooling or refrigeration. The two-phase gas-liquid refrigerant flowing out of the water heat exchanger 15 flows into the compressor 11.

[0020] Next, the operation of the heat pump system 100 during heating operation will be described using Figure 1. The gas-phase refrigerant, which has been heated to a high temperature and pressure by the compressor 11, is discharged from the compressor 11 and exchanges heat with water in the water heat exchanger 15, which functions as a condenser, to become liquid refrigerant. At this time, the refrigerant releases heat, heating the water circulating through the water circuit 20 and using it for heating or hot water supply. The liquid refrigerant flowing out of the water heat exchanger 15 is depressurized by the pressure reducing device 14 to become a two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flowing out of the pressure reducing device 14 is heat exchanged with air in the air heat exchanger 12, which functions as an evaporator, and is heated. The two-phase gas-liquid refrigerant flowing out of the air heat exchanger 12 flows into the compressor 11.

[0021] FIG. 2 is a block diagram showing the configuration of the power conversion device 30 of the heat pump system 100 according to the first embodiment of the present disclosure. FIG. 3 is a diagram showing an example of a PWM signal generated by the control unit 312 in the power conversion device 30 of the heat pump system 100 according to the first embodiment of the present disclosure. FIG. 4 is a block diagram showing the configuration of the water circulation pump 25 and the power conversion device 30 when the water circulation pump 25 of the heat pump system 100 according to the first embodiment of the present disclosure is an AC-driven device. FIG. 5 is a block diagram showing the configuration of the water circulation pump 25 and the power conversion device 30 when the water circulation pump 25 of the heat pump system 100 according to the first embodiment of the present disclosure is a DC-driven device. The configuration of the power conversion device 30 will be described using FIGS. 2 to 5 .

[0022] Note that AC-driven equipment is equipment that uses AC voltage as its power source. DC-driven equipment is equipment that uses DC voltage as its power source. For the sake of explanation, if the water circulation pump 25 is an AC-driven equipment, it will be referred to as an AC-driven water circulation pump 250, and if the water circulation pump 25 is a DC-driven equipment, it will be referred to as a DC-driven water circulation pump 251.

[0023] In general, AC-driven water circulation pump 250 has higher capacity and a higher flow rate than DC-driven water circulation pump 251. Therefore, AC-driven water circulation pump 250 is used when a high flow rate is required for water-using equipment 27 of heat pump system 100. However, because AC-driven water circulation pump 250 is more expensive than DC-driven water circulation pump 251, costs can be reduced by using DC-driven water circulation pump 251 when a high flow rate is not required for water-using equipment 27 of heat pump system 100.

[0024] 2, the power conversion device 30 includes a main board 31 and a relay board 32. The relay board 32 is configured as a separate board from the main board 31, and includes a DC voltage conversion unit 322. The main board 31 and the relay board 32 are, for example, printed circuit boards.

[0025] The main board 31 is connected to the AC power supply 29 and receives the AC voltage output from the AC power supply 29. The main board 31 also has a filter circuit 310, a relay 311, a control unit 312, a connector 313, and a connector 314.

[0026] The filter circuit 310 is a circuit for removing noise contained in the AC voltage input from the AC power supply 29. More specifically, the filter circuit 310 is composed of an inductor. The relay 311 switches between connection and disconnection between the main board 31 and the AC power supply 29.

[0027] The control unit 312 generates a PWM (Pulse Width Modulation) signal from a predetermined DC voltage command value. The DC voltage command value is a command voltage value output by the control unit 312 to the DC-driven water circulation pump 251, and is a command voltage for driving the DC-driven water circulation pump 251.

[0028] When the DC voltage command value increases, the rotation speed of the drive shaft of the water circulation pump 25 increases. When the DC voltage command value decreases, the rotation speed of the drive shaft of the water circulation pump 25 decreases.

[0029] As shown in Figure 3, a PWM signal is a digital signal that is composed of a pulse train in which a pulse on time (T1) and a pulse off time (T2) are repeated at a fixed cycle (T). The duty ratio is a value that indicates the proportion of the on time of the pulses of a periodic signal. The duty ratio D of a PWM signal is expressed by the following equation 1.

[0030]

[0031] The control unit 312 also generates a PWM signal from the DC voltage command value. That is, the control unit 312 generates a PWM signal for adjusting the voltage so that the value of the DC voltage input to the DC-driven water circulation pump 251 coincides with the DC voltage command value. Furthermore, when the power conversion device 30 and the AC-driven water circulation pump 250 are electrically connected, the control unit 312 does not control the AC-driven water circulation pump 250. That is, in this case, the control unit 312 does not generate a DC voltage command value or a PW signal. The configuration of the control unit 312 will be described later.

[0032] 5 , the connector 313 is electrically connected to the connector 320 by a first electrical connection portion 360. The electrical connection by the first electrical connection portion 360 allows the AC voltage that has passed through the filter circuit 310 and the relay 311 to be input to the relay board 32.

[0033] First electrical connection portion 360 is, for example, a conductor, and is configured so that both ends of the conductor can be electrically connected and disconnected. More specifically, main board 31 and relay board 32 are electrically connected by connecting the conductor between connector 313 and connector 320. Furthermore, main board 31 and relay board 32 are electrically disconnected by disconnecting the conductor between connector 313 and connector 320.

[0034] 4 , when the water circulation pump 25 is an AC-driven water circulation pump 250, the main board 31 and the water circulation pump 25 are electrically connected by a second electrical connection 361. The second electrical connection 361 is, for example, a conductor, and is configured to allow electrical connection and disconnection. More specifically, the main board 31 and the AC-driven water circulation pump 250 are electrically connected by connecting a conductor between the connector 313 and the AC-driven water circulation pump 250. Furthermore, the main board 31 and the water circulation pump 25 are electrically disconnected by disconnecting the conductor between the connector 313 and the AC-driven water circulation pump 250. In other words, the connector 313 corresponds to an AC voltage supply unit that supplies AC voltage to the AC-driven water circulation pump 250.

[0035] The connector 314 has three contacts, one of which is grounded, and supplies the PWM signal output from the control unit 312 to the relay board 32.

[0036] The relay board 32 includes a connector 320 , a filter circuit 321 , a DC voltage conversion unit 322 , a power supply circuit 323 , a connector 324 , a photocoupler 325 , a voltage division unit 327 , and a connector 328 .

[0037] Connector 320 has two contacts. Connector 320 is electrically connected to connector 313, and receives AC voltage from main board 31. Filter circuit 321 is a circuit for removing noise contained in the AC voltage input from main board 31. More specifically, filter circuit 321 is made up of an inductor.

[0038] The DC voltage conversion unit 322 converts the AC voltage that has passed through the filter circuit 321 into a DC voltage. The DC voltage conversion unit 322 includes a diode bridge 35 and a bus electrolytic capacitor 36. The diode bridge 35 converts the AC voltage into a pulsating current. The bus electrolytic capacitor 36 smoothes the pulsating current converted by the diode bridge 35.

[0039] The power supply circuit 323 steps down the DC voltage converted by the DC voltage converter 322 and inputs the stepped-down DC current to its input terminals. More specifically, the power supply circuit 323 inputs a first DC voltage V1 to its terminal a. The power supply circuit 323 also inputs a second DC voltage V2 to its terminal b.

[0040] The connector 324 has three contacts. The connector 324 is electrically connected to the connector 314, and receives the PWM signal generated by the control unit 312 from the main board 31.

[0041] The photocoupler 325 transmits the PWM signal generated by the control unit 312 to the relay board 32 in an electrically insulated state.

[0042] The voltage dividing unit 327 divides the first DC voltage V1. The voltage dividing unit 327 has a voltage dividing resistor 330 and an electrolytic capacitor 331. The voltage dividing resistor 330 has a first voltage dividing resistor 330a and a second voltage dividing resistor 330b. The first voltage dividing resistor 330a and the second voltage dividing resistor 330b are fixed resistors with constant resistance values.

[0043] The first voltage-dividing resistor 330a and the second voltage-dividing resistor 330b are connected in series. When the resistance value of the first voltage-dividing resistor 330a is Ra, the resistance value of the second voltage-dividing resistor 330b is Rb, and the duty ratio of the PWM signal transmitted by the photocoupler 325 is D, the third DC voltage V3 input to the terminals d and e is expressed by the following equation 2.

[0044]

[0045] The electrolytic capacitor 331 smoothes the third DC voltage V3.

[0046] That is, the first DC voltage V1 is adjusted to the value of the third DC voltage V3 by the photocoupler 325 and the voltage dividing unit 327. The photocoupler 325 and the voltage dividing unit 327 correspond to the voltage adjusting unit.

[0047] The connector 328 has four contacts. The second DC voltage V2 and the third DC voltage V3 are input to the connector 328 from the relay board 32. As shown in FIG. 5 , the connector 328 is electrically connected to the DC-driven water circulation pump 251 via a third electrical connection 362. This electrical connection via the third electrical connection 362 allows the second DC voltage V2 and the third DC voltage V3 to be output to the DC-driven water circulation pump 251. The third electrical connection 362 is, for example, a conductor. The relay board 32 and the water circulation pump 25 are electrically disconnected by disconnecting the conductor between the connector 328 and the water circulation pump 25. In other words, the connector 328 corresponds to a DC voltage supply unit that supplies a DC voltage to the DC-driven water circulation pump 251.

[0048] The value of the fourth DC voltage V4, which is the voltage for driving the DC-driven water circulation pump 251, is the value obtained by subtracting the third DC voltage V3 from the second DC voltage V2. Therefore, the fourth DC voltage V4 can be expressed by the following equation (3).

[0049]

[0050] When the relationship of Equation 2 is substituted into Equation 3, the relationship of Equation 4 is established.

[0051]

[0052] According to the relational expression (4), the duty ratio D of the PWM signal is decreased in order to increase the command voltage value of the DC-driven water circulation pump 251. On the other hand, the duty ratio D of the PWM signal is increased in order to decrease the command voltage value of the DC-driven water circulation pump 251.

[0053] In the heat pump system 100 according to the first embodiment, the main board 31 having the control unit 312 and the relay board 32 having the DC voltage conversion unit 322 are configured on separate boards. With this configuration, the heat pump system 100 according to the first embodiment can reduce the cost of replacing the board of the power conversion device 30.

[0054] Furthermore, in the power conversion device 30 of the heat pump system 100 in the first embodiment, the main board 31 having the control unit 312 and the relay board 32 having the DC voltage conversion unit 322 are configured on separate boards, so that it is possible to connect the AC-driven water circulation pump 250 to the power conversion device 30 as shown in Fig. 4, and it is also possible to connect the DC-driven water circulation pump 251 to the power conversion device 30 as shown in Fig. 5. In other words, the main board 31, which was previously only capable of driving the AC-driven water circulation pump 250, can also drive the DC-driven water circulation pump 251 via the relay board 32.

[0055] Furthermore, in heat pump system 100, when AC-driven water circulation pump 250 and DC-driven water circulation pump 251 are interchanged, only the connection between first electrical connection 360 and second electrical connection 361 needs to be changed. With this configuration, heat pump system 100 in embodiment 1 has the advantage of being able to easily interchange AC-driven water circulation pump 250 and DC-driven water circulation pump 251. Also, with this configuration, AC-driven water circulation pump 250 and DC-driven water circulation pump 251 can be selectively used in consideration of the flow rate required for water-using equipment 27.

[0056] The water circulation pump 25 is used to circulate water in the water circuit 20 of the heat pump system 100. Therefore, there is a possibility that the efficiency or performance of the water circulation pump 25 will decrease due to overheating in the water circuit 20. Therefore, it is particularly required that the water circulation pump 25 of the heat pump system 100 be used by switching between the AC-driven water circulation pump 250 and the DC-driven water circulation pump 251 depending on the driving status of the water circulation pump 25.

[0057] Fig. 6 is a block diagram showing the functional configuration of the control unit 312 of the heat pump system 100 according to the first embodiment of the present disclosure. Fig. 7 is a block diagram showing the hardware configuration of the control unit 312 of the heat pump system 100 according to the first embodiment of the present disclosure. The configuration of the control unit 312 will be described using Figs. 6 and 7 .

[0058] As shown in FIG. 6, the control unit 312 includes a storage unit 37 , a duty ratio determination unit 38 , and a signal generation unit 39 .

[0059] The storage unit 37 stores a DC voltage command value for the DC-driven water circulation pump 251 .

[0060] The duty ratio determination unit 38 determines the duty ratio D of the PWM signal from the DC voltage command value stored in the storage unit 37 .

[0061] The signal generating unit 39 generates a PWM signal so that the value of the fourth DC voltage V4 becomes equal to the DC voltage command value. The PWM signal generated by the signal generating unit 39 is output to the connector 314.

[0062] As shown in FIG. 7, the hardware configuration of the control unit 312 includes a processor 370 , a memory 371 , and a storage 372 .

[0063] The processor 370 executes a program stored in the memory 371. Specifically, the processor 370 generates a PWM signal so that the value of the fourth DC voltage V4 becomes the value of the DC command voltage. The processor 370 is, for example, a CPU (Central Processing Unit).

[0064] The memory 371 stores programs executed by the processor 370. The memory 371 is also used as a work area for the processor 370. The memory 371 is, for example, a volatile memory such as a random access memory (RAM), a non-volatile memory such as a read-only memory (ROM), or both a volatile memory and a non-volatile memory. The duty ratio determination unit 38 and the signal generation unit 39 are realized by the processor 370 and the memory 371.

[0065] The storage 372 stores the DC voltage command value. The storage unit 37 is realized by storing information in the storage 372.

[0066] As described above, the heat exchange system (corresponding to the heat pump system 100) according to the first embodiment includes the water heat exchanger 15 that changes the temperature of water, the water circulation pump 25 that sends water to the water heat exchanger 15, the power conversion device 30 that is electrically connected to the water circulation pump 25, the water usage equipment 27 that uses the water that flows out of the water heat exchanger 15, and the water piping 26 that connects the water circulation pump 25, the water heat exchanger 15, and the water usage equipment 27 to form the water circuit 20. The power conversion device 30 receives an AC voltage from an AC power source 29, and when the water circulation pump 25 is an AC-driven water circulation pump 250 that is driven by an AC voltage, the power conversion device 30 is connected to an AC power source 29 that supplies AC voltage to the AC-driven water circulation pump 250. The heat exchange system according to the first embodiment includes a main board 31 having a supply unit (corresponding to connector 313) and a control unit 312 that determines a DC voltage command value to be input to DC-driven water circulation pump 251 when water circulation pump 25 is a DC-driven water circulation pump 251 driven by a DC voltage, and a relay board 32 that is a separate board from main board 31 and has a DC voltage conversion unit 322 that converts AC voltage to DC voltage, a voltage adjustment unit (corresponding to photocoupler 325 and voltage divider 327) that adjusts the voltage so that the value of the DC voltage converted by DC voltage conversion unit 322 matches the DC voltage command value, and a DC voltage supply unit (corresponding to connector 328) that supplies the DC voltage adjusted by the voltage adjustment unit to DC-driven water circulation pump 251. With this configuration, the heat exchange system according to the first embodiment has the effect of reducing the cost of replacing the boards in power conversion device 30.

[0067] Moreover, the power conversion device 30 according to the first embodiment includes a main board 31 having an AC voltage supply unit (corresponding to a connector 313) that receives an AC voltage output from an AC power source 29 and supplies the AC voltage to AC-driven equipment that uses the AC voltage as a drive source, and a control unit 312 that determines a DC voltage command value to be input to the controlled equipment when the controlled equipment, which is the equipment to be controlled, is a DC-driven equipment that uses a DC voltage as a drive source; and a relay board 32 that is a separate board separate from the main board 31 and has a DC voltage conversion unit 322 that converts the AC voltage into a DC voltage, a voltage adjustment unit (corresponding to a photocoupler 325 and a voltage divider 327) that adjusts the voltage so that the value of the DC voltage converted by the DC voltage conversion unit 322 matches the DC voltage command value, and a DC voltage supply unit (corresponding to a connector 328) that supplies the DC voltage adjusted by the voltage adjustment unit to the DC-driven equipment. With this configuration, the power conversion device 30 according to the first embodiment has the advantage of being able to reduce the cost required to replace the board of the power conversion device 30 .

[0068] Furthermore, in the heat exchange system according to the first embodiment (corresponding to the heat pump system 100), the main board 31 further includes a filter circuit 310 for removing noise from the AC voltage as an additional component. This additional component allows the heat exchange system according to the first embodiment to effectively remove noise contained in the AC voltage.

[0069] Furthermore, in the heat exchange system according to the first embodiment (corresponding to the heat pump system 100), the main board 31 further includes, as an additional component, a relay 311 that switches between connection and disconnection with the AC power supply 29. With this additional component, the heat exchange system according to the first embodiment has the advantage of being able to control the power supply.

[0070] Furthermore, the heat exchange system (corresponding to heat pump system 100) according to embodiment 1 has an additional configuration in which, when water circulation pump 25 is DC-driven water circulation pump 251, DC voltage conversion unit 322 is electrically connected to an AC voltage supply unit (corresponding to connector 313) and receives AC voltage from the AC voltage supply unit. This additional configuration enables the heat exchange system according to embodiment 1 to achieve a stable electrical connection between main board 31 and relay board 32. Furthermore, when main board 31 includes filter circuit 310, AC voltage from which noise has been removed is input to relay board 32. Furthermore, when main board 31 includes relay 311, AC voltage with controlled power supply is input to relay board 32.

[0071] Furthermore, in the heat exchange system according to the first embodiment (corresponding to the heat pump system 100), as an additional configuration, the voltage adjustment unit (corresponding to the photocoupler 325 and the voltage divider 327) has two or more voltage dividing resistors 330 (first voltage dividing resistor 330a, second voltage dividing resistor 330b) that divide the DC voltage. With this additional configuration, the heat exchange system according to the first embodiment exhibits the effect of being able to adjust the value of the DC voltage input to the DC-driven water circulation pump 251.

[0072] The heat exchange system according to the first embodiment (corresponding to the heat pump system 100) further includes, as additional components, a compressor 11 that compresses and discharges the refrigerant, an air heat exchanger 12 that exchanges heat between the refrigerant and air, a pressure reducing device 14 that reduces the pressure of the refrigerant, and refrigerant piping 16 that connects the compressor 11, the air heat exchanger 12, the pressure reducing device 14, and a water heat exchanger 15 to form a refrigerant circuit 10. The water heat exchanger 15 changes the temperature of the water by exchanging heat between the water and the refrigerant. This additional configuration allows the heat exchange system according to the first embodiment to achieve the effect of efficient heat exchange.

[0073] Furthermore, in the power conversion device 30 according to the first embodiment, the main board 31 further includes, as an additional configuration, a filter circuit 310 for removing noise from the AC voltage. With this additional configuration, the power conversion device 30 according to the first embodiment has the effect of being able to effectively remove noise contained in the AC voltage.

[0074] Furthermore, in the power conversion device 30 according to the first embodiment, as an additional configuration, the main board 31 further includes a relay 311 that switches between connection and disconnection with the AC power supply 29. With this additional configuration, the power conversion device 30 according to the first embodiment has the effect of being able to control the supply of power.

[0075] Furthermore, as an additional configuration, power conversion device 30 according to embodiment 1 has DC voltage conversion unit 322 electrically connected to an AC voltage supply unit (corresponding to connector 313) when water circulation pump 25 is DC-driven water circulation pump 251, and AC voltage is input from the AC voltage supply unit. This additional configuration enables power conversion device 30 according to embodiment 1 to achieve a stable electrical connection between main board 31 and relay board 32. Furthermore, when main board 31 includes filter circuit 310, AC voltage from which noise has been removed is input to relay board 32. Furthermore, when main board 31 includes relay 311, AC voltage from which power supply is controlled is input to relay board 32.

[0076] Furthermore, in the power conversion device 30 according to the first embodiment, as an additional configuration, the voltage adjustment unit (corresponding to the photocoupler 325 and the voltage divider 327) has two or more voltage dividing resistors 330 (first voltage dividing resistor 330a, second voltage dividing resistor 330b) that divide the DC voltage. With this additional configuration, the power conversion device 30 according to the first embodiment has the effect of being able to adjust the value of the DC voltage input to the DC-driven water circulation pump 251.

[0077] Embodiment 2 A heat pump system 200 according to embodiment 2 will be described. In embodiment 2, the same components as those in embodiment 1 of the present disclosure are designated by the same reference numerals, and descriptions of the same or corresponding parts will be omitted.

[0078] FIG. 8 is a circuit diagram illustrating an overview of a heat pump system 200 according to a second embodiment of the present disclosure. As shown in FIG. 8 , the heat pump system 200 according to the second embodiment differs from the heat pump system 100 according to the first embodiment in the configuration of the power conversion device 40. More specifically, the power conversion device 40 includes a photocoupler 426. The heat pump system 200 also includes a rotational speed detection unit 41. The configuration of the heat pump system 200, excluding the power conversion device 40 and the rotational speed detection unit 41, is the same as that of the heat pump system 100.

[0079] 9 is a block diagram showing the configuration of water circulation pump 25 and power conversion device 40 when water circulation pump 25 is a DC-driven device in heat pump system 200 according to embodiment 2 of the present disclosure. The configurations of rotation speed detection unit 41 and power conversion device 40 will be described with reference to FIG.

[0080] 9 , when the water circulation pump 25 is a DC-driven water circulation pump 251, the rotation speed detection unit 41 detects the rotation speed of the drive shaft of the DC-driven water circulation pump 251. The rotation speed detection unit 41 is, for example, a rotation speed sensor. A signal indicating the rotation speed detected by the rotation speed detection unit 41 is input to the relay board 58 via the third electrical connection unit 363.

[0081] In comparison with power conversion device 30, power conversion device 40 includes a photocoupler 426 on relay board 58. Furthermore, power conversion device 40 differs in the voltage input to power supply circuit 333 of relay board 58, the content of the signal transmitted by connector 338 of relay board 58, the content of the signal transmitted by connector 344 of relay board 58, the content of the signal transmitted by connector 354 of main board 57, and the content of control performed by control unit 412 of main board 57.

[0082] The power supply circuit 333, like the power supply circuit 323, inputs the first to third DC voltages V1 to V3 to the corresponding terminals. The power supply circuit 333 also inputs a fifth DC voltage V5 to a terminal f. The fifth DC voltage V5 is a voltage source connected to the photocoupler 426.

[0083] Connector 338 has five contacts. Similar to connector 328 of relay board 32, second DC voltage V2 and third DC voltage V3 are input to connector 338, and connector 338 is electrically connected to DC-driven water circulation pump 251 by third electrical connection part 362. The rotational speed of the drive shaft of DC-driven water circulation pump 251 detected by rotational speed detection part 41 is input to photocoupler 426 via connector 338 as a rotational speed signal.

[0084] A rotation speed signal indicating the rotation speed of the drive shaft of DC-driven water circulation pump 251 is input to photocoupler 426 from rotation speed detection unit 41 via connector 338. Photocoupler 426 also outputs the input rotation speed signal indicating the rotation speed of the drive shaft of DC-driven water circulation pump 251 to control unit 412 via connectors 344 and 354 in an electrically insulated state.

[0085] Fig. 10 is a block diagram showing the functional configuration of the control unit 412 of the heat pump system 200 according to the second embodiment of the present disclosure. The functional configuration of the control unit 412 will be described using Fig. 10. The hardware configuration of the control unit 412 is similar to that of the control unit 312 of the power conversion device 30 described in the first embodiment, and therefore description thereof will be omitted.

[0086] As shown in FIG. 10, the control unit 412 differs from the control unit 312 in the contents stored in the storage unit 47 and the processing contents performed by the duty ratio determination unit 48 .

[0087] The storage unit 47 stores DC voltage command values, similar to the storage unit 37. The storage unit 47 also stores a target rotation speed of the drive shaft of the DC-driven water circulation pump 251. The target rotation speed is a target rotation speed when driving the drive shaft of the DC-driven water circulation pump 251.

[0088] The duty ratio determiner 48 determines the duty ratio of the PWM signal from the DC voltage command value and the target rotation speed stored in the memory 47. When driving the DC-driven water circulation pump 251, the duty ratio determiner 48 performs the same processing as the duty ratio determiner 38. Furthermore, while the DC-driven water circulation pump 251 is operating, the duty ratio determiner 48 determines the duty ratio of the PWM signal at regular intervals from the rotation speed of the DC-driven water circulation pump 251 detected by the rotation speed detector 41. More specifically, when the rotation speed detected by the rotation speed detector 41 is slower than the target rotation speed, the duty ratio determiner 48 decreases the duty ratio of the PWM signal. Furthermore, when the rotation speed detected by the rotation speed detector 41 is faster than the target rotation speed, the duty ratio determiner 48 increases the duty ratio of the PWM signal.

[0089] With this configuration, heat pump system 200 according to the second embodiment changes the value of the voltage input to DC-driven water circulation pump 251 in accordance with the rotational speed of the drive shaft of DC-driven water circulation pump 251. Therefore, heat pump system 200 has the advantage of being able to perform highly accurate control. Heat pump system 200 also has the advantage of being able to perform control that takes into account differences in the rotational speed of the drive shaft due to the ambient environment of DC-driven water circulation pump 251 or individual differences.

[0090] As described above, the heat exchange system (corresponding to the heat pump system 200) according to the second embodiment, like the first embodiment, includes the water heat exchanger 15 that changes the temperature of water, the water circulation pump 25 that sends water to the water heat exchanger 15, the power conversion device 40 that is electrically connected to the water circulation pump 25, the water usage equipment 27 that uses the water that flows out of the water heat exchanger 15, and the water piping 26 that connects the water circulation pump 25, the water heat exchanger 15, and the water usage equipment 27 to form the water circuit 20. The power conversion device 40 receives an AC voltage from an AC power source 29, and supplies the AC voltage to the AC-driven water circulation pump 250 when the water circulation pump 25 is an AC-driven water circulation pump 250 that is driven by the AC voltage. and a relay board 58, which is a separate board separate from the main board 57, having a DC voltage converter 322 that converts AC voltage to DC voltage, a voltage adjuster (corresponding to a photocoupler 325 and a voltage divider 327) that adjusts the voltage so that the value of the DC voltage converted by the DC voltage converter 322 coincides with the DC voltage command value, and a DC voltage supply unit (corresponding to a connector 338) that supplies the DC voltage adjusted by the voltage adjuster to the DC-driven water circulation pump 251. With this configuration, the heat exchange system according to the second embodiment has the effect of reducing the cost of replacing the boards of the power conversion device 40, similar to the effect described in the first embodiment.

[0091] Similarly to the first embodiment, the power conversion device 40 according to the second embodiment includes a main board 57 having an AC voltage supply unit (corresponding to the connector 313) that receives the AC voltage output from the AC power source 29 and supplies the AC voltage to AC-driven equipment that uses the AC voltage as a power source, and a control unit 412 that determines a DC voltage command value to be input to the controlled equipment when the controlled-target equipment, which is the equipment to be controlled, is a DC-driven equipment that uses a DC voltage as a power source, and a relay board 32 that is a separate board separate from the main board 57 and has a DC voltage conversion unit 322 that converts the AC voltage into a DC voltage, a voltage adjustment unit (corresponding to the photocoupler 325 and the voltage divider 327) that adjusts the voltage so that the value of the DC voltage converted by the DC voltage conversion unit 322 matches the DC voltage command value, and a DC voltage supply unit (corresponding to the connector 338) that supplies the DC voltage adjusted by the voltage adjustment unit to the DC-driven equipment. With this configuration, the power conversion device 40 according to the second embodiment has the same effect as that described in the first embodiment, that is, it is possible to reduce the cost of replacing the boards of the power conversion device 40.

[0092] Furthermore, the heat exchange system according to the second embodiment (corresponding to the heat pump system 200) further includes, as an additional component, a rotation speed detection unit 41 that detects the rotation speed of the water circulation pump 25 when the water circulation pump 25 is a DC-driven water circulation pump 251, and the control unit 412 increases the DC voltage command value when the rotation speed detected by the rotation speed detection unit 41 is slower than a predetermined target rotation speed, and decreases the DC voltage command value when the rotation speed detected by the rotation speed detection unit 41 is faster than the target rotation speed. With this additional component, the heat exchange system according to the second embodiment has the advantage of being able to perform control that takes into account differences in rotation speed due to the ambient environment or individual differences of the DC-driven water circulation pump 251.

[0093] Furthermore, as an additional configuration, power conversion device 40 according to the second embodiment has control unit 412 that, when water circulation pump 25 is DC-driven water circulation pump 251, increases the DC voltage command value when the rotation speed detected by rotation speed detection unit 41, which detects the rotation speed of water circulation pump 25, is slower than a predetermined target rotation speed, and decreases the DC voltage command value when the rotation speed detected by the rotation speed detection unit is faster than the target rotation speed. This additional configuration enables power conversion device 40 according to the second embodiment to achieve the effect of being able to perform control that takes into account differences in rotation speed due to the ambient environment or individual differences of DC-driven water circulation pump 251.

[0094] Although the heat pump system 200 of the second embodiment is configured to determine the duty ratio of the PWM signal according to the rotational speed of the drive shaft of the DC-driven water circulation pump 251 detected by the rotational speed detection unit 41, this is not limiting. Any configuration may be used as long as the duty ratio of the PWM signal is determined based on a drive status detection unit that detects the drive status of the DC-driven water circulation pump 251, regardless of the rotational speed of the drive shaft of the DC-driven water circulation pump 251. Specifically, the drive status detection unit is a water temperature sensor, a temperature sensor, or a humidity sensor. For example, the water temperature sensor detects the water temperature in the water circuit 20, and if the water temperature detected by the water temperature sensor is lower than a predetermined set water temperature, the DC voltage command value is increased. Furthermore, if the water temperature detected by the water temperature sensor is higher than the set water temperature, the DC voltage command value is decreased.

[0095] Third Embodiment A heat pump system 300 according to a third embodiment will be described. Fig. 11 is a circuit diagram showing an overview of a heat pump system according to a third embodiment of the present disclosure. As shown in Fig. 11, the heat pump system 300 according to the third embodiment differs from the heat pump system 100 according to the first embodiment in the configuration of the power conversion device 50. The configuration of the heat pump system 300, excluding the power conversion device 50, is the same as that of the heat pump system 100, and therefore description thereof will be omitted.

[0096] 12 is a block diagram showing the configuration of a power conversion device 50 of a heat pump system 300 according to the third embodiment of the present disclosure. The configuration of the power conversion device 50 will be described with reference to FIG.

[0097] 12 , the voltage dividing unit 337 on the relay board 52 of the power conversion device 50 has a voltage dividing resistor 340 and an electrolytic capacitor 331, similar to the voltage dividing unit 327. The voltage dividing resistor 340 also has a first voltage dividing resistor 340 a and a second voltage dividing resistor 340 b. The first voltage dividing resistor 340 a and the second voltage dividing resistor 340 b are variable resistors whose resistance values ​​are variable.

[0098] As shown in Equation 4, the fourth DC voltage V4, which is the voltage that drives the DC-driven water circulation pump 251, varies depending on the value of the first voltage-dividing resistor 340a or the value of the second voltage-dividing resistor 340b. More specifically, increasing the resistance value of the first voltage-dividing resistor 340a or decreasing the resistance value of the second voltage-dividing resistor 340b increases the value of the fourth DC voltage V4. Also, decreasing the value of the first voltage-dividing resistor or increasing the value of the second voltage-dividing resistor decreases the value of the fourth DC voltage V4.

[0099] The heat pump system 300 has the advantage that the user can adjust the rotation speed of the drive shaft of the DC-driven water circulation pump 251 by using variable resistors for the first voltage dividing resistor 340a and the second voltage dividing resistor 340b.

[0100] As described above, the heat exchange system (corresponding to the heat pump system 300) according to the third embodiment, like the first embodiment, includes the water heat exchanger 15 that changes the temperature of water, the water circulation pump 25 that sends water to the water heat exchanger 15, the power conversion device 40 that is electrically connected to the water circulation pump 25, the water usage equipment 27 that uses the water that flows out of the water heat exchanger 15, and the water piping 26 that connects the water circulation pump 25, the water heat exchanger 15, and the water usage equipment 27 to form the water circuit 20. The power conversion device 50 receives an AC voltage from an AC power source 29, and supplies the AC voltage to the AC-driven water circulation pump 250 when the water circulation pump 25 is an AC-driven water circulation pump 250 that is driven by the AC voltage. and a control unit 312 that determines a DC voltage command value to be input to the DC-driven water circulation pump 251 when the water circulation pump 25 is a DC-driven water circulation pump 251 driven by a DC voltage, and a relay board 52 that is a separate board from the main board 31 and that has a DC voltage converter 322 that converts AC voltage to DC voltage, a voltage adjuster (corresponding to a photocoupler 325 and a voltage divider 337) that adjusts the voltage so that the value of the DC voltage converted by the DC voltage converter 322 matches the DC voltage command value, and a DC voltage supply unit (corresponding to a connector 328) that supplies the DC voltage adjusted by the voltage adjuster to the DC-driven water circulation pump 251. With this configuration, the heat exchange system according to the third embodiment achieves the effect of reducing the cost of replacing the boards of the power conversion device 50, similar to the effect described in the first embodiment.

[0101] Similarly to the first embodiment, the power conversion device 50 according to the third embodiment includes a main board 31 having an AC voltage supply unit (corresponding to the connector 313) that receives the AC voltage output from the AC power supply 29 and supplies the AC voltage to AC-driven equipment that uses the AC voltage as a power source, and a control unit 312 that determines a DC voltage command value to be input to the controlled equipment when the controlled-target equipment, which is the equipment to be controlled, is a DC-driven equipment that uses a DC voltage as a power source; and a relay board 52 that is a separate board separate from the main board 31 and has a DC voltage conversion unit 322 that converts the AC voltage into a DC voltage, a voltage adjustment unit (corresponding to the photocoupler 325 and the voltage divider 337) that adjusts the voltage so that the value of the DC voltage converted by the DC voltage conversion unit 322 matches the DC voltage command value, and a DC voltage supply unit (corresponding to the connector 328) that supplies the DC voltage adjusted by the voltage adjustment unit to the DC-driven equipment. With this configuration, the power conversion device 50 according to the third embodiment has the same effect as that described in the first embodiment, that is, it is possible to reduce the cost of replacing the boards of the power conversion device 50.

[0102] Furthermore, the heat exchange system (corresponding to heat pump system 300) according to the third embodiment has an additional configuration in which the voltage dividing resistors (corresponding to first voltage dividing resistor 340a and second voltage dividing resistor 340b) are variable resistors whose resistance values ​​can be adjusted. This additional configuration allows the heat exchange system according to the third embodiment to have the effect of allowing the user to adjust the rotation speed of the drive shaft of DC-driven water circulation pump 251.

[0103] Furthermore, in the power conversion device 50 according to the third embodiment, as an additional configuration, the voltage dividing resistors (corresponding to the first voltage dividing resistor 340 a and the second voltage dividing resistor 340 b) are variable resistors whose resistance values ​​can be adjusted. With this additional configuration, the power conversion device 50 according to the third embodiment exhibits the effect that the user can adjust the rotation speed of the drive shaft of the DC-driven water circulation pump 251.

[0104] In the heat pump system 300 according to the third embodiment, both the first voltage dividing resistor 340a and the second voltage dividing resistor 340b are variable resistors, but this is not limited to this. One of the first voltage dividing resistor 340a and the second voltage dividing resistor 340b may be a variable resistor and the other a fixed resistor. If the voltage dividing resistors are configured as one or more variable resistors, the user can adjust the rotation speed of the drive shaft of the DC-driven water circulation pump 251.

[0105] Alternatively, the target rotation speeds may be stored in a plurality of storage units, and the user may select a desired rotation speed from among the plurality of target rotation speeds.

[0106] Furthermore, in the heat pump systems according to the first to third embodiments, the value of the fourth DC voltage V4 input to the DC-driven water circulation pump 251 decreases when the duty ratio of the PWM signal is increased, but this is not limiting. The value of the fourth DC voltage V4 may also increase when the duty ratio of the PWM signal is increased.

[0107] Furthermore, the number of poles of the connector in the heat pump systems according to embodiments 1 to 3 is determined depending on the application. For example, by setting the number of poles of connector 313 to four, main board 31 can be electrically connected to relay board 32 and also electrically connected to AC-driven water circulation pump 250. Therefore, in this case, the power conversion device can drive both AC-driven water circulation pump 251 and DC-driven water circulation pump 251.

[0108] Furthermore, in the heat pump systems according to the first to third embodiments, the control unit is realized by a single device and is configured to be provided on the main board 31, but this is not limited thereto. Only a portion of the control unit, for example, the configuration corresponding to the memory unit, may be provided on the main board, and the configuration corresponding to the duty ratio determination unit and the signal generation unit may be provided on the relay board, with each configured to be able to communicate with each other. Even in such a configuration, because a portion of the control unit is provided on the main board, the cost of replacing the board of the power conversion device 30 can be reduced compared to when the power conversion device is configured on a single printed circuit board.

[0109] Furthermore, in the heat pump systems according to the first to third embodiments, the power supply circuit is configured to input a plurality of different voltage values ​​to corresponding terminals, but this is not limited thereto. The power supply circuit may also be configured to step down the voltage to a certain value and input the same voltage value to all terminals. In this case, the input voltage is divided using voltage dividing resistors or the like to adjust it to the required voltage for each terminal.

[0110] In addition, in the heat pump systems according to the first to third embodiments, the voltage dividing unit has two voltage dividing resistors, but this is not limiting. The voltage dividing unit may be composed of three or more voltage dividing resistors.

[0111] Furthermore, although the heat pump systems according to the first to third embodiments are configured to be capable of both cooling and heating operations, this is not limiting. The heat pump system may be configured to perform only cooling operation or only heating operation. Furthermore, the heat pump system may have a four-way valve and be configured to be able to switch between cooling operation and heating operation.

[0112] Furthermore, in the heat pump systems according to the first to third embodiments, the heat pump system is provided with one water circulation pump 25, but this is not limiting, and the heat pump system may be configured to include multiple water circulation pumps 25. Furthermore, the water circulation pump 25 may be provided in any location as long as it is provided in the water circuit 20.

[0113] Furthermore, while the power conversion devices according to the first to third embodiments are intended to control the water circulation pump 25 in a heat pump system, the present invention is not limited to this. The power conversion device may also be configured to control a water circulation pump in a heat exchange system that transfers thermal energy between water and a refrigerant to perform heat exchange. For example, the power conversion device may be configured to control a water circulation pump in a gas-powered water heater.

[0114] The power conversion devices according to the first to third embodiments can also be used for controlled devices other than water circulation pumps. That is, the power conversion device can be connected to AC-driven devices other than heat pumps that use AC voltage as their drive source to drive the AC-driven devices. Also, the power conversion device can be connected to DC-driven devices other than heat pumps that use DC voltage as their drive source to drive the DC-driven devices.

[0115] Furthermore, in the power conversion devices according to the first to third embodiments, electrical connections are made by conductors, but this is not limiting. For example, wireless power supply may be used.

[0116] Furthermore, although the power conversion devices according to the first to third embodiments use photocouplers for signal transmission, this is not limiting. For example, instead of photocouplers, solid-state relays, optocouplers, or magnet couplers may be used.

[0117] The configurations described in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known technologies. Furthermore, parts of the configurations may be omitted or modified without departing from the scope of the present disclosure.

[0118] REFRIGERATED SYMBOLS 10 REFRIGERATED CIRCUIT, 11 COMPRESSOR, 12 AIR HEAT EXCHANGER, 13 BLOWER, 14 DECOMPRESSION DEVICE, 15 WATER HEAT EXCHANGER, 16 REFRIGERATED PIPE, 20 WATER CIRCUIT, 21 FIRST WATER CIRCUIT, 22 SECOND WATER CIRCUIT, 23 TANK, 24 VALVE, 25 WATER CIRCULATION PUMP, 26 WATER PIPE, 27 WATER USING EQUIPMENT, 29 AC POWER SUPPLY, 30 POWER CONVERSION DEVICE, 31 MAIN BOARD, 32 RELAY BOARD, 35 DIODE BRIDGE, 36 BUS ELECTROLYTIC CAPACITOR, 37 MEMORY UNIT, 38 DUTY RATIO DETERMINATION UNIT, 39 SIGNAL GENERATION UNIT, 40 POWER CONVERSION DEVICE, 41 ROTATIONAL SPEED DETECTION UNIT, 47 MEMORY UNIT, 48 DUTY RATIO DETERMINATION UNIT, 50 POWER CONVERSION DEVICE, 52 RELAY BOARD, 57 MAIN BOARD, 58 RELAY BOARD, 100 HEAT PUMP SYSTEM, 200 HEAT PUMP SYSTEM, 250 AC DRIVEN WATER CIRCULATION PUMP, 251 DC-driven water circulation pump, 300 heat pump system, 310 filter circuit, 311 relay, 312 control unit, 313 connector, 314 connector, 320 connector, 321 filter circuit, 322 DC voltage conversion unit, 323 power supply circuit, 324 connector, 325 photocoupler, 327 voltage divider unit, 328 connector, 330 voltage divider resistor, 330a first voltage divider resistor, 330b second voltage divider resistor, 331 electrolytic capacitor, 333 power supply circuit, 334 connector, 337 voltage divider unit, 338 connector, 340 voltage divider resistor, 340a first voltage divider resistor, 340b second voltage divider resistor, 344 connector, 354 connector, 360 first electrical connection unit, 361 second electrical connection unit, 362 third electrical connection unit, 363 third electrical connection unit, 370 processor, 371 Memory, 372 storage, 412 control unit, 426 photocoupler.

Claims

1. A water heat exchanger that changes the temperature of water, a water circulation pump that sends the water to the water heat exchanger, a power conversion device that is electrically connected to the water circulation pump, a water-using device that uses the water that flows out of the water heat exchanger, and water piping that connects the water circulation pump, the water heat exchanger, and the water-using device to form a water circuit, The power conversion device comprises a main board that receives an AC voltage from an AC power source and has an AC voltage supply unit that supplies the AC voltage to the AC-driven water circulation pump if the water circulation pump is an AC-driven water circulation pump driven by an AC voltage, and a control unit that determines a DC voltage command value to be input to the DC-driven water circulation pump if the water circulation pump is a DC-driven water circulation pump driven by a DC voltage; and an intermediate board that is separate from the main board and has a DC voltage conversion unit that converts the AC voltage to a DC voltage, a voltage adjustment unit that adjusts the voltage so that the value of the DC voltage converted by the DC voltage conversion unit matches the DC voltage command value, and a DC voltage supply unit that supplies the DC voltage adjusted by the voltage adjustment unit to the DC-driven water circulation pump.

2. The heat exchange system according to claim 1, wherein the main board further comprises a filter circuit for removing noise from the AC voltage.

3. The heat exchange system according to claim 1 or 2, wherein the main board further comprises a relay for switching between connection and disconnection with the AC power supply.

4. A heat exchange system according to claim 2 or 3, wherein the DC voltage conversion unit is electrically connected to the AC voltage supply unit when the water circulation pump is a DC-driven water circulation pump, and the AC voltage is input from the AC voltage supply unit.

5. A heat exchange system according to any one of claims 1 to 4, wherein the voltage adjustment unit has two or more voltage dividing resistors that divide the DC voltage.

6. The heat exchange system according to claim 5, wherein the voltage dividing resistor is a variable resistor whose resistance value can be adjusted.

7. A heat exchange system as claimed in any one of claims 1 to 6, further comprising a rotation speed detection unit that detects the rotation speed of the water circulation pump when the water circulation pump is the DC-driven water circulation pump, wherein the control unit increases the DC voltage command value when the rotation speed detected by the rotation speed detection unit is slower than a predetermined target rotation speed, and decreases the DC voltage command value when the rotation speed detected by the rotation speed detection unit is faster than the target rotation speed.

8. A heat exchange system according to any one of claims 1 to 7, further comprising: a compressor that compresses and discharges a refrigerant; an air heat exchanger that exchanges heat between the refrigerant and air; a pressure reducing device that reduces the pressure of the refrigerant; and refrigerant piping that connects the compressor, the air heat exchanger, the pressure reducing device, and the water heat exchanger to form a refrigerant circuit, wherein the water heat exchanger changes the temperature of the water by exchanging heat between the water and the refrigerant.

9. A power conversion device comprising: a main board having an AC voltage supply unit that receives an AC voltage output from an AC power source and supplies the AC voltage to AC-driven equipment that uses the AC voltage as a power source, and a control unit that determines a DC voltage command value to be input to a controlled device when the controlled device is a DC-driven device that uses a DC voltage as a power source; and an intermediate board that is separate from the main board and has a DC voltage conversion unit that converts the AC voltage to a DC voltage, a voltage adjustment unit that adjusts the DC voltage so that the value of the DC voltage converted by the DC voltage conversion unit matches the DC voltage command value, and a DC voltage supply unit that supplies the DC voltage adjusted by the voltage adjustment unit to the DC-driven device.

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