JP6837311B2 - Heat pump device - Google Patents

Description

This disclosure relates to heat pump devices such as air conditioners, refrigerators, and water heaters, and is suitably used for heat pump devices that can be operated by, for example, either an AC power source or a DC power source.

Japanese Unexamined Patent Publication No. 2009-216324 (Patent Document 1) discloses a technique for improving the energy saving of an air conditioner. Specifically, in the air conditioner of this document, a winding switching unit for selectively switching the stator winding of the motor for the compressor between Δ connection and Y connection is provided. When operating the compressor at its rated capacity, the winding switching unit selects the delta connection. When operating the compressor at an intermediate capacity that is half the rated capacity, the Y-connection is selected by the winding switching unit.

Japanese Patent Application Laid-Open No. 09-243136 (Patent Document 2) discloses an air conditioner in which a commercial power source and a solar cell are used in combination. Specifically, in the air conditioner of this document, the generated power of the solar cell is supplied to the outdoor unit of the air conditioner via the DC / DC converter. The DC / DC converter is provided with an output power limit value in order to reduce the component cost. When the power consumption of the air conditioner exceeds the output power limit value, the insufficient power is supplied to the air conditioner from the commercial power source.

JP-A-2009-216324 Japanese Unexamined Patent Publication No. 09-2431136

In order to prevent leakage current between the DC power supply and the AC power supply, the inventors of the present application completely switch between the power supply from the DC power supply such as a storage battery and the power supply from the commercial AC power supply to one power supply. We are developing an air conditioner that supplies only the electric power from the generator to the compressor.

In order to drive the compressor at a high operating frequency by supplying power from a DC power supply in such a power switching type air conditioner, it is necessary to supply the voltage boosted by the DC / DC converter to the inverter circuit. Become. The reason for this is that the magnitude of the output voltage of a DC power source such as a storage battery is generally limited.

However, when a DC / DC converter is used, there is a problem that the energy consumption efficiency (COP: Coefficient Of Performance) is kept low due to the conversion loss. This problem is common not only to air conditioners but also to heat pump devices including refrigerators and water heaters.

The technique presented in the present disclosure takes into account the above circumstances and an object of the present invention is to provide a power switching type heat pump device capable of improving energy consumption efficiency.

The heat pump device according to one aspect of this disclosure includes a compressor, a first heat exchanger, an expansion valve, a second heat exchanger, a power supply circuit, a connection switching unit, and a control unit. The compressor compresses the refrigerant. The first heat exchanger condenses the compressed refrigerant. The expansion valve regulates the flow rate of the refrigerant that has passed through the first heat exchanger. The second heat exchanger evaporates the refrigerant that has passed through the expansion valve and returns the evaporated refrigerant to the compressor. The power supply circuit includes a power supply switching unit capable of switching the power supply path so as to drive the motor for the compressor by supplying power from either an AC power supply or a DC power supply. The connection switching unit can switch the connection method of the stator windings SU, SV, and SW of the motor between Y connection and Δ connection. The control unit controls the power supply switching unit and the wiring switching unit. When driving the motor with an AC power supply, the control unit switches the stator windings SU, SV, and SW to Y connection, and when driving the motor with a DC power supply, the stator windings SU, SV, and SW are changed to Δ. It is configured to switch to connection.

In the above configuration, the power supply circuit may further include a rectifier circuit and an inverter circuit. In this case, the rectifier circuit rectifies the AC voltage from the AC power supply. The inverter circuit generates an AC voltage based on the DC voltage from the DC power supply or the voltage rectified by the rectifier circuit, and drives the motor by the generated AC voltage.

In one embodiment, the power supply circuit may further include a DC / DC converter that boosts a DC voltage from a DC power source. In this case, when the power supply switching unit drives the motor by the DC power supply, the power supply switching unit directly supplies the DC voltage from the DC power supply to the inverter circuit and supplies the DC voltage boosted by the DC / DC converter to the inverter circuit. It may be possible to switch between the case where and the case where the operation is performed.

In the above embodiment, when the maximum power to be supplied to the motor is equal to or greater than the threshold value, the control unit supplies the DC voltage boosted by the DC / DC converter to the inverter circuit, and the maximum power to be supplied to the motor is When it is less than the threshold value, it may be configured to directly supply the DC voltage from the DC power supply to the inverter circuit.

In another embodiment, when the motor is driven by a DC power source, the DC voltage from the DC power source may be supplied directly to the inverter circuit without being boosted.

In each of the above configurations, the control unit can be configured to switch the power supply path of the power supply switching unit based on a command from the central management device of the HEMS (Home Energy Management System).

According to the heat pump device of the above aspect, when the motor is driven by the DC power supply, the energy consumption efficiency can be improved by switching the stator windings SU, SV, and SW to the Δ connection.

It is a block diagram which shows the whole structure of an air conditioner. It is a circuit diagram which shows the structure of the connection switching part of FIG. It is a figure for demonstrating the difference of the connection system of the stator winding of a three-phase motor. It is a flowchart which shows an example of the switching procedure of the connection switching part in the air conditioner of FIG. It is a flowchart which shows an example of the switching procedure of the power supply switching part in the air conditioner of FIG. It is a circuit diagram of a step-up chopper as an example of a DC / DC converter. It is a figure which shows the calculation result of the loss under each condition of Table 1. It is a block diagram which shows the structure of the air conditioner of Embodiment 2. It is a flowchart which shows an example of the switching procedure of the connection switching part in the air conditioner of FIG. It is a block diagram which shows the structure of the air conditioner of Embodiment 3. It is a flowchart which shows an example of the switching procedure of the power supply switching part in the air conditioner of FIG.

Hereinafter, each embodiment will be described in detail with reference to the drawings. In some cases, the same or corresponding parts are designated by the same reference numerals and the description thereof may not be repeated.

<Embodiment 1>
[Overall configuration of air conditioner]
FIG. 1 is a block diagram showing an overall configuration of an air conditioner. FIG. 1 shows the overall configuration of the air conditioner 1 as an example of the heat pump device. In the first embodiment, as an example of the heat pump device, a separate type air conditioner including an indoor unit and an outdoor unit will be described as an example, but the technique disclosed in the first embodiment is described in this manner. Not limited. For example, this technology can be applied to an integrated air conditioner that is not divided into an indoor unit and an outdoor unit, and can also be applied to a refrigerator, a freezer, a water heater, and the like.

With reference to FIG. 1, the air conditioner 1 includes a heat pump cycle 10 including a compressor 11 (also referred to as a compressor), a four-way valve 14, an outdoor heat exchanger 12, an expansion valve 15, and an indoor heat exchanger 13. Further, the air conditioner 1 includes a power supply circuit 30 that supplies drive power to a motor (16 in FIG. 1) that is a power source of the compressor 11, a connection switching unit 35, a control unit 36, and an operation unit 22. Be prepared.

In the heat pump cycle 10, the compressor 11 compresses the refrigerant. The four-way valve 14 switches the circulation direction of the refrigerant in the cooling operation and the heating operation. The outdoor heat exchanger 12 exchanges heat between the outdoor air and the refrigerant. The opening degree of the expansion valve 15 is controlled in order to adjust the flow rate of the refrigerant. The indoor heat exchanger 13 exchanges heat between the indoor air and the refrigerant.

The circulation direction of the refrigerant when the four-way valve 14 is switched will be described. In the cooling operation mode, as shown by the broken line arrow in FIG. 1, the compressor 11, the four-way valve 14, the outdoor heat exchanger 12, the expansion valve 15, the indoor heat exchanger 13, the four-way valve 14, and the compressor 11 are in this order. The refrigerant circulates. In this case, the outdoor heat exchanger 12 functions as a condenser for condensing and liquefying the compressed high-temperature refrigerant, and the indoor heat exchanger 13 evaporates the liquefied refrigerant to lower the temperature of the refrigerant. It functions as an evaporator to change it into a gas. On the other hand, in the heating operation mode, as shown by the solid arrow HT in FIG. 1, the compressor 11, the four-way valve 14, the indoor heat exchanger 13, the expansion valve 15, the outdoor heat exchanger 12, the four-way valve 14, and the compressor. The refrigerant circulates in the order of 11. In this case, the outdoor heat exchanger 12 functions as an evaporator, and the indoor heat exchanger 13 functions as a condenser.

The power supply circuit 30 is connected to a DC power supply 21 and a commercial AC power supply 20, and generates three-phase AC voltages V1, V2, V3 by supplying power from one of these power supplies to generate a motor of the compressor 11 (FIG. 1). Supply to 16). More specifically, the power supply circuit 30 includes a power supply switching unit 31, a rectifier circuit 32, a DC / DC (direct current / direct current) converter 33, and an inverter circuit 34.

Although FIG. 1 shows an example in which the storage battery 21A is used as the DC power source 21, another DC power source such as a solar cell may be used instead of the storage battery 21A.

The power supply switching unit 31 can switch the power supply path so as to drive the motor for the compressor 11 by supplying power from one of the AC power supply 20 and the DC power supply 21. By completely switching between the AC power supply 20 and the DC power supply 21 in this way, it is possible to prevent a leakage current between the DC power supply 21 and the AC power supply 20.

In the case of FIG. 1, the power supply switching unit 31 includes switches SW1 and SW2. The switch SW1 is an on / off switch. The switch SW1 supplies the AC voltage from the AC power supply to the rectifier circuit in the on state (that is, the conductive state), and cuts off the supply of the AC voltage from the AC power supply 20 in the off state (non-conducting state). The switch SW2 also serves as an on / off switch and a changeover switch. When the switch SW2 is in the ON state, the switch SW2 can be switched between a case where the DC voltage from the storage battery 21A is supplied to the DC / DC converter 33 and a case where the DC voltage is directly supplied to the inverter circuit 34. The switch SW2 cuts off the supply of DC voltage from the storage battery 21A when it is in the off state.

The rectifier circuit 32 converts the AC voltage supplied from the AC power supply 20 via the switch SW1 into a DC voltage. As the rectifier circuit 32, for example, a diode bridge rectifier circuit is used.

The DC / DC converter 33 boosts the DC voltage supplied from the storage battery 21A via the switch SW2. The type of DC / DC converter 33 is not particularly limited. For example, a non-insulated boost chopper may be used, or an isolated flyback converter or forward converter may be used.

The inverter circuit 34 uses either the voltage rectified by the rectifier circuit 32, the DC voltage directly supplied from the switch SW2, or the DC voltage output from the DC / DC converter 33 as three-phase AC voltages V1, V2. Convert to V3. A three-phase bridge type inverter circuit 34 can be used.

The connection switching unit 35 can switch the connection method of the stator winding of the motor for the compressor 11 between Y connection and Δ connection. Details of the connection switching unit 35 will be described with reference to FIG. Although the compressor 11 and the connection switching unit 35 are shown separately in the functional block diagram of FIG. 1, in practice, the connection switching unit 35 is often built in the compressor 11. The connection switching unit 35 of the present embodiment includes such a case.

The control unit 36 is configured based on a microcomputer including a CPU and a memory. The control unit 36 controls the entire air conditioner 1 based on a user command input from the operation unit 22 provided on the remote controller. Specifically, the control unit 36 controls the operations of the switches SW1 and SW2 of the power supply switching unit 31, the DC / DC converter 33, the inverter circuit 34, and the connection switching unit 35.

[Configuration of connection switching unit]
FIG. 2 is a circuit diagram showing the configuration of the connection switching unit of FIG. FIG. 2 shows a three-phase motor 16, an inverter circuit 34, and a control unit 36, which are power sources for the compressor 11 of FIG. 1, together with a connection switching unit 35.

The three-phase motor 16 is a permanent magnet synchronous motor or a brushless DC motor. In a permanent magnet synchronous motor (brushless DC motor), a permanent magnet is provided on the rotor, and U-phase, V-phase, and W-phase stator windings SU, SV, and SW are provided on the stator. Each end of the stator windings SU, SV, and SW is connected to the output nodes N1, N2, and N3 of the inverter circuit 34, respectively. A DC voltage Vdc is applied between the input nodes N4 and N5 of the inverter circuit 34.

The connection switching unit 35 includes a switch group 35A composed of three switches and a switch group 35B composed of three switches. One end of the three switches constituting the switch group 35A is connected to one end of the stator windings SU, SV, and SW, respectively, and the other end of the three switches is connected to the other end of the stator windings SV, SW, and SU. Each is connected. One end of the three switches constituting the switch group 35B is connected to one end of the stator windings SU, SV, and SW, respectively, and the other end of the three switches is connected to the common node NC. The on and off of the switch groups 35A and 35B are controlled by the control unit 36.

According to the configuration of the connection switching unit 35 described above, if all the switches constituting the switch group 35B are in the conductive state and all the switches constituting the switch group 35A are in the non-conducting state, the stator windings SU and SV , SW connection method is Y connection. On the contrary, if all the switches constituting the switch group 35B are in the non-conducting state and all the switches constituting the switch group 35A are in the conductive state, the connection method of the stator windings SU, SV, and SW becomes Δ connection. Become.

[Differences between Y connection and Δ connection]
FIG. 3 is a diagram for explaining the difference in the connection method of the stator winding of the three-phase motor. FIG. 3 (A) shows a circuit diagram of Y connection, FIG. 3 (B) shows a circuit diagram of Δ connection, and FIG. 3 (C) shows a difference in voltage and current due to the connection method in a table format. The nodes N1, N2, N3 of FIGS. 3A and 3B correspond to the output nodes N1, N2, N3 of the inverter circuit 34 of FIG. 2, respectively.

With reference to FIG. 3, a voltage of the same magnitude E is applied to the stator windings SU, SV, and SW of each phase regardless of the difference in the wiring method, and a current of the same magnitude I flows. It is assumed that there is. Here, the magnitude represents an amplitude value or an effective value.

On the other hand, the voltage between the terminals of the three-phase motor, that is, the voltage applied between the nodes N1, N2, between the nodes N2 and N3, between the nodes N3 and N1, and the current flowing through each node N1, N2, N3. Makes a difference depending on the connection method. In the case of Y connection, the magnitude of the current flowing through each terminal of the three-phase motor is I, whereas the magnitude of the voltage between the terminals is √3 × E. In the case of delta connection, the magnitude of the current flowing through each terminal of the three-phase motor is √3 × I, whereas the magnitude of the voltage between the terminals is E.

Therefore, by changing the Y connection to the Δ connection, the magnitude of the voltage between the terminals becomes 1 / √3, while the magnitude of the current at each terminal becomes √3 times. On the contrary, if the voltage between each terminal, that is, the output voltage of the inverter circuit 34 is kept constant, the magnitude of the voltage applied to each stator winding is multiplied by √3 by changing the Y connection to the Δ connection. The current flowing through the stator winding can be increased by 1 / √3 times.

In the present embodiment, when the compressor 11 is operated by supplying power from the DC power supply 21 by utilizing the above points, the stator windings SU, SV, of the three-phase motor 16 for the compressor 11 are operated. Set the SW connection method to Δ connection. As a result, the voltage applied to each of the stator windings SU, SV, and SW of the three-phase motor 16 can be made high, so that the DC power supply 21 makes three phases up to a higher rotation speed range than in the case of Y connection. The motor 16 can be driven.

[Operation of heat pump device]
Next, the operation of the air conditioner 1 having the above configuration, particularly the switching procedure of the connection switching unit and the power supply switching unit will be specifically described.

FIG. 4 is a flowchart showing an example of a switching procedure of the connection switching unit in the air conditioner of FIG. With reference to FIGS. 1 and 4, first, the operation unit 22 is operated by the user in step S101 to turn on (ON) the power switch (relay) for energizing the outdoor unit of the air conditioner 1. As a result, the operation of the air conditioner 1 is started (step S102).

In the flowchart of FIG. 4, it is assumed that the power switch is turned on in step S101 and the operation of the air conditioner 1 is started in step S102, but the present invention is not limited to this. For example, with the power switch already turned on, the user inputs the set temperature in the room in step S101, inputs the start command of the cooling operation or the heating operation, and in step S102, the control in response to the input is started. May be. More generally, in step S101, some operation command for starting the control procedure after step S103 in FIG. 4 is input, and the operation is started in step S102.

In the next step S103, the control unit 36 receives the operation mode selection input from the user via the operation unit 22. The operation mode includes an AC mode in which the air conditioner 1 is operated by supplying power from the AC power source 20, and a DC mode in which the air conditioner 1 is operated by supplying power from the storage battery 21A. Whether the operation mode is AC mode or DC mode is stored in a register or the like as a flag.

In the next step S104, the control unit 36 confirms whether the flag is set to the AC mode or the DC mode. Here, when the flag is set to the DC mode (NO in step S104), the control unit 36 receives information on the magnitude of the output voltage of the storage battery 21A, and the DC voltage output from the storage battery 21A is equal to or less than the reference voltage. It is determined whether or not there is (step S105). As a result, when the DC voltage output from the storage battery 21A is equal to or lower than the reference voltage (YES in step S105), it is difficult to supply power from the storage battery 21A due to insufficient remaining amount. The mode is reset (step S106). In this case, the process returns to S104.

When the flag is set to the DC mode (NO in step S104) and the remaining amount of the storage battery 21A is sufficient (NO in step S105), the control unit 36 is in the operating state (ON) of the compressor 11. That is, it is determined whether the AC voltages V1, V2, and V3 are supplied from the inverter circuit 34 (step S107). When the compressor 11 is in the operating state (YES in step S107), the control unit 36 turns off the operation of the compressor 11 (step S108).

After that, in step S109, the control unit 36 switches the connection method of the stator windings SU, SV, and SW of the three-phase motor for the compressor 11 to Δ connection. In the next step S110, the control unit 36 starts the operation of the compressor 11 by supplying the AC voltages V1, V2, and V3 from the inverter circuit 34.

On the other hand, when it is confirmed in step S104 that the flag is set to the AC mode (YES in step S104), the control unit 36 first determines whether the compressor 11 is in the operating state (ON). That is, it is determined whether the AC voltages V1, V2, and V3 are supplied from the inverter circuit 34 (step S111). When the compressor 11 is in the operating state (YES in step S107), the control unit 36 turns off the operation of the compressor 11 (step S112).

After that, in step S113, the control unit 36 switches the connection method of the stator windings SU, SV, and SW of the three-phase motor for the compressor 11 to Δ connection. In the next step S114, the control unit 36 starts the operation of the compressor 11 by supplying the AC voltages V1, V2, and V3 from the inverter circuit 34.

While the compressor 11 is operating thereafter, the control unit 36 acquires an operation mode setting state (that is, a flag value) in order to periodically confirm whether or not the operation mode has been changed by the user (step). S115). If the setting state of the operation mode has not been changed (NO in step S116), it is confirmed whether or not the above operation mode has been changed every time the designated time elapses (step S117). On the other hand, when the operation mode is changed (YES in step S116), the control unit 36 repeats the control from the above step S104.

FIG. 5 is a flowchart showing an example of a switching procedure of the power supply switching unit in the air conditioner of FIG.

With reference to FIGS. 1 and 5, in step S200, the control unit 36 confirms whether the flag is set to the DC mode or the AC mode. When the flag is set to the DC mode (YES in step S200), in the next step S201, the control unit 36 determines whether or not the maximum power to be supplied from the power supply circuit 30 to the compressor 11 is equal to or greater than the threshold value. To judge.

In the case of the DC mode, when the compressor 11 needs to be supplied with power equal to or higher than the threshold value (YES in step S201), the control unit 36 turns off the switch SW1 and switches the connection of the switch SW2 to direct current. The power supply 21 is connected to the DC / DC converter 33 (step S203). As a result, the DC voltage boosted by the DC / DC converter 33 is input to the inverter circuit 34.

In the case of the DC mode, when the compressor 11 does not need to be supplied with power equal to or higher than the threshold value (NO in step S201), the control unit 36 turns off the switch SW1 and switches the connection of the switch SW2 to direct current. The power supply 21 is directly connected to the inverter circuit 34. As a result, no loss occurs in the DC / DC converter 33, so that the air conditioner 1 can be operated with lower power consumption.

On the other hand, when the flag is set to the AC mode (NO in step S200), in the next step S202, the control unit 36 turns on the switch SW1 and turns the switch SW2 off. As a result, the AC voltage from the AC power supply 20 is input to the rectifier circuit 32, and the voltage rectified by the rectifier circuit 32 is input to the inverter circuit 34.

[Calculation result of loss in DC / DC converter]
Hereinafter, the result of concretely calculating the loss in the DC / DC converter will be described. In the following loss calculation, when a boost chopper is used as the DC / DC converter and the air conditioner is operated at the rated capacity in the heating operation, when the air conditioner is operated at the rated capacity in the cooling operation, the rated capacity in the heating operation is calculated. A comparison was made when the air conditioner was operated with an intermediate capacity of about half.

FIG. 6 is a circuit diagram of a step-up chopper as an example of a DC / DC converter. With reference to FIG. 6, the DC / DC converter 33 generates a DC voltage Vo by boosting the DC voltage Vi input between the input node N6 and the input node N7, and outputs the generated DC voltage Vo. Output is performed between N8 and the output node N9. Let the output current output from the output node N8 be Io.

Specifically, the DC / DC converter 33 includes an inductor 40, a diode 41, a switching element 42, and a capacitor 43. The inductor 40 and the diode 41 are connected in series between the input node N6 and the output node N8 in this order. The anode of the diode 41 is connected to the inductor 40. The input node N7 on the low potential side and the output node N9 on the low potential side are directly connected by the wiring 45. The switching element 42 is connected between the connection node 49 of the inductor 40 and the diode 41 and the wiring 45. In the example of FIG. 6, an IGBT (Insulated Gate Bipolar Transistor) is used as the switching element 42. The smoothing capacitor 43 is connected between the output node N8 and the output node N9.

A PWM (Pulse Width Modulation) signal having a carrier frequency Fc is input to the gate electrode of the switching element 42. Let the temperature of the switching element 42 and the diode 41 be Ts.

As the switching element 42 and the diode 41, it is assumed that the IGBT and the diode mounted on the power module manufactured by Mitsubishi Electric of the model number PSS20S92E6 are used. Further, it is assumed that the inverter circuit 34 operates at the maximum modulation factor. Therefore, the boost rate (Vo / Vi) of the DC / DC converter 33 is set to the minimum necessary value. The parameters used for the loss calculation are shown in Table 1 below.

FIG. 7 is a diagram showing a calculation result of loss under each condition of Table 1. In FIG. 7, the conduction loss of the diode is shown by DCL, the switching loss of the diode is shown by DSL, the conduction loss of the IGBT is shown by TrCL, and the switching loss of the IGBT is shown by TrSL.

With reference to Table 1 and FIG. 7, in the case of heating operation and rated capacity, when the connection method of the stator windings SU, SV, SW of the motor is changed from Y connection to Δ connection, the DC / DC converter The output voltage Vo of 33 is reduced by 1 / √3 times. As a result, as shown in FIG. 7, it can be seen that the switching loss of the IGBT was reduced by about 4 W. In addition, the IGBT continuity loss was also reduced by about 2 W because the energization rate of the PWM signal was reduced. However, since the output current increased √3 times, the conduction loss of the diode increased by about 2 W. Therefore, in the entire DC / DC converter, the loss is reduced by about 4.5 W by changing the connection method of the stator winding of the motor from Y connection to Δ connection. Similar results have been obtained for cooling operation and rated capacity.

On the other hand, in the case of heating operation and intermediate capacity, when the connection method of the stator winding of the motor is Δ connection, boosting by the DC / DC converter is not necessary. In this case, the DC voltage from the DC power supply 21 of FIG. 1 is directly input to the inverter circuit 34. In Table 1, for convenience, both the input voltage Vi and the output voltage Vo of the DC / DC converter 33 are described as 100 V, but the current does not actually pass through the DC / DC converter 33. Since the DC / DC converter 33 is not operating, the loss is 0 W.

[effect]
The effects of the air conditioner of the first embodiment described above can be summarized as follows. Generally, the upper limit of the output voltage of a DC power supply is limited to a lower value than that of a commercial AC power supply for safety reasons. Therefore, when a DC power supply is used in a conventional air conditioner, there is a problem that the capacity of the compressor is limited. Since there is a limit to boosting even when a DC / DC converter is used, there is a limit to the capacity of the compressor as compared with the case where an AC power supply is used.

On the other hand, in the air conditioner 1 of the present embodiment, when the motor 16 is driven by the DC power supply 21, the stator windings SU, SV, and SW are switched to Δ connection. As a result, the voltage applied to each stator winding of the motor can be increased √3 times without changing the output voltage of the DC / DC converter 33, so that the energy consumption efficiency of the air conditioner 1 can be improved. Can be improved. Further, higher capacity can be realized as compared with the case of Y connection.

Further, when the maximum power to be supplied to the motor 16 is less than the threshold value, for example, when the air conditioner 1 is operated with an intermediate capacity of about half of the rated capacity, the DC voltage from the DC power supply 21 is DC. It bypasses the / DC converter 33 and is directly supplied to the inverter circuit 34. Thereby, the power consumption of the power supply circuit 30 can be further reduced.

<Embodiment 2>
In the second embodiment, a case where the heat pump device operates based on a command from the central management device of the HEMS (Home Energy Management System) will be described. Although the air conditioner will be described as an example of the heat pump device in the second embodiment, the technique disclosed in the second embodiment can also be applied to a refrigerator, a freezer, a water heater, and the like.

[About HEMS]
In HEMS, the central management device is the Internet, a high-performance distribution board called a smart meter, a power supply device such as a solar power generation device and a storage battery, a water heater, and air via a wireless LAN (Local Area Network). Connected to home appliances such as water heaters, refrigerators, and washing machines. The central management device acquires information on the operating state of the power supply device such as the amount of power generated by the photovoltaic power generation device and the remaining amount of the storage battery, and also acquires information on the operating state such as the power consumption of each home appliance device. The central management device manages the operation of each power supply device and each home appliance device so that efficient operation is performed based on this information.

[About the configuration and operation of the air conditioner]
FIG. 8 is a block diagram showing the configuration of the air conditioner according to the second embodiment. The air conditioner 2 of FIG. 8 is different from the air conditioner 1 of FIG. 1 in that the control unit 36 operates based on a command from the central management device 23 of the HEMS. Since the other points of FIG. 8 are the same as those of FIG. 1, the same or corresponding parts are designated by the same reference numerals and the description is not repeated.

FIG. 9 is a flowchart showing an example of a switching procedure of the connection switching unit in the air conditioner of FIG. The flowchart of FIG. 9 is a modification of the flowchart of FIG. 4 in some respects. Hereinafter, the changes will be described with reference to FIGS. 4, 8 and 9.

First, in the flowchart of FIG. 9, steps S103A and S115A are provided in place of steps S103 and S115 of FIG. 4, respectively. In steps S103A and S115A, the control unit 36 acquires information on the operation mode from the central management device 23 of the HEMS, that is, whether the flag setting value is the AC mode or the DC mode.

Further, in the flowchart of FIG. 9, step S105 and step S106 of FIG. 4 are not provided. Since whether or not the remaining amount of the storage battery 21A is sufficient is controlled by the central management device 23 of the HEMS, it is not necessary for the control unit 36 of the air conditioner 2 to make such a determination.

Since the other points of FIG. 9 are the same as those of FIG. 4, the same or corresponding parts are designated by the same reference numerals and the description is not repeated. Further, since the switching procedure of the power supply switching unit 31 described with reference to FIG. 5 is the same in the second embodiment, the description will not be repeated.

[effect]
The air conditioner 2 of the second embodiment can also have the same effect as that of the first embodiment. Further, the air conditioner 2 is efficiently operated based on the command of the central management device 23 according to the power consumption of the air conditioner 2 and the operating state of the DC power source 21 such as the remaining amount of the storage battery 21A or the power generated by the solar cell. You can drive.

<Embodiment 3>
In the third embodiment, a modified example in which the DC / DC converter 33 is not provided in the power supply circuit 30 will be described. For example, in the case of an air conditioner having a relatively small output such as for a bedroom, it is necessary and sufficient to connect the stator winding of the motor for the compressor 11 to Δ connection without boosting by the DC / DC converter 33. You can get the ability. Hereinafter, a specific description will be given with reference to the drawings.

Although the air conditioner will be described as an example of the heat pump device in the third embodiment, the technique disclosed in the third embodiment can also be applied to a refrigerator, a freezer, a water heater, and the like.

[About the configuration and operation of the air conditioner]
FIG. 10 is a block diagram showing the configuration of the air conditioner according to the third embodiment. The power supply circuit 30A of the air conditioner 3 of FIG. 10 is different from the power supply circuit 30 of the air conditioner 1 of FIG. 1 in that it does not include the DC / DC converter 33. In the case of FIG. 10, the switch SW2 is provided in the middle of the wiring connecting the storage battery 21A and the input node of the inverter circuit 34, and functions as an on / off switch. Since the other points of FIG. 10 are the same as those of FIG. 1, the same or corresponding parts are designated by the same reference numerals and the description is not repeated.

FIG. 11 is a flowchart showing an example of a switching procedure of the power supply switching unit in the air conditioner of FIG.

With reference to FIGS. 10 and 11, in step S400, the control unit 36 confirms whether the flag is set to the DC mode or the AC mode. When the flag is set to the DC mode (YES in step S400), in the next step S401, the control unit 36 turns the switch SW1 off and turns the switch SW2 on, thereby direct current. The DC voltage from the power supply 21 is directly input to the inverter circuit 34.

On the other hand, when the flag is set to the AC mode (NO in step S400), in the next step S402, the control unit 36 turns on the switch SW1 and turns the switch SW2 off. As a result, the AC voltage from the AC power supply 20 is input to the rectifier circuit 32, and the voltage rectified by the rectifier circuit 32 is input to the inverter circuit 34.

[effect]
When it is not necessary to operate the compressor with high capacity, the power supply circuit 30 may not be provided with the DC / DC converter 33 as described above. Even if the DC / DC converter 33 is not provided, the operating frequency of the compressor 11 having a required size can be obtained by changing the connection method of the stator windings SU, SV, and SW to Δ connection.

<Additional notes>
A part of the disclosure contents of the above-described first to third embodiments can be summarized as follows.

(1) The heat pump device includes a compressor 11, a first heat exchanger 12; 13, an expansion valve 15, a second heat exchanger 13; 12, a power supply circuit 30, a connection switching unit 35, and the like. It includes a control unit 36. The compressor 11 compresses the refrigerant. The first heat exchangers 12; 13 condense the compressed refrigerant. The expansion valve 15 adjusts the flow rate of the refrigerant that has passed through the first heat exchangers 12; 13. The second heat exchangers 13; 12 evaporate the refrigerant that has passed through the expansion valve 15 and return the evaporated refrigerant to the compressor 11. The power supply circuit 30 includes a power supply switching unit 31 capable of switching the power supply path so as to drive the motor 16 for the compressor 11 by supplying power from one of the AC power supply 20 and the DC power supply 21. The connection switching unit 35 can switch the connection method of the stator windings SU, SV, and SW of the motor 16 between Y connection and Δ connection. The control unit 36 controls the power supply switching unit 31 and the connection switching unit 35. The control unit 36 switches the stator windings SU, SV, and SW to Y connection when the motor 16 is driven by the AC power supply 20, and the stator winding SU, when the motor 16 is driven by the DC power supply 21. It is configured to switch SV and SW to Δ connection.

According to the above heat pump device, when the motor 16 is driven by the DC power supply 21, the stator windings SU, SV, and SW are switched to Δ connection without changing the output voltage of the DC / DC converter 33. , The voltage applied to each stator winding SU, SV, SW of the motor can be increased √3 times. As a result, the energy consumption efficiency of the heat pump device can be improved. In addition, higher capacity can be realized as compared with the case of Y connection.

(2) In the above (1), the power supply circuit 30 further includes a rectifier circuit 32 and an inverter circuit 34. The rectifier circuit 32 rectifies the AC voltage from the AC power supply 20. The inverter circuit 34 generates an AC voltage based on the DC voltage from the DC power supply 21 or the voltage rectified by the rectifier circuit 32, and drives the motor 16 with the generated AC voltage.

By driving the motor with an inverter as described above, the operating frequency of the compressor can be freely changed, so that the compressor can be driven efficiently.

(3) In the above (2), the power supply circuit 30 further includes a DC / DC converter 33 that boosts the DC voltage from the DC power supply 21. When the power supply switching unit 31 drives the motor 16 by the DC power supply 21, the power supply switching unit 31 directly supplies the DC voltage from the DC power supply 21 to the inverter circuit 34, and the power supply switching unit 31 supplies the DC voltage boosted by the DC / DC converter 33 to the inverter. It is possible to switch between the case of supplying to the circuit 34 and the case of supplying the circuit 34.

By bypassing the DC / DC converter 33 and supplying the DC voltage to the inverter circuit 34, the power consumption of the power supply circuit 30 can be further reduced.

(4) In the above (3), when the maximum power to be supplied to the motor 16 is equal to or greater than the threshold value, the control unit 36 supplies the DC voltage boosted by the DC / DC converter 33 to the inverter circuit 34, and the motor 16 When the maximum power to be supplied to the inverter is less than the threshold value, the DC voltage from the DC power supply 21 is directly supplied to the inverter circuit 34.

When the operation with high capacity is not required, the power consumption of the power supply circuit 30 can be further reduced by directly supplying the DC voltage to the inverter circuit 34 without going through the DC / DC converter 33.

(5) In the above (2), when the motor is driven by the DC power supply 21, the DC voltage from the DC power supply 21 is directly supplied to the inverter circuit 34 without being boosted.

When operation with high capacity is not required, the power supply circuit 30 may not be provided with the DC / DC converter 33 as described above.

(6) In the above (1) to (5), the control unit 36 switches the power supply path of the power supply switching unit 31 based on a command from the central management device 23 of the HEMS (Home Energy Management System).

According to this configuration, the heat pump device can be efficiently operated according to the power consumption of the heat pump device and the operating state of the DC power source such as the remaining amount of the storage battery or the generated power of the solar cell.

The embodiments disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present invention is shown by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the claims.

1-3 Air conditioner, 10 heat pump cycle, 11 compressor, 12 outdoor heat exchanger, 13 indoor heat exchanger, 14 four-way valve, 15 expansion valve, 16 motor, 20 AC power supply, 21 DC power supply, 21A storage battery, 22 Operation unit, 23 central control unit, 30, 30A power supply circuit, 31 power supply switching unit, 32 rectifier circuit, 33 DC / DC converter, 34 inverter circuit, 35 connection switching unit, 35A, 35B switch group, 36 control unit, SU, SV, SW stator winding.

Claims (6)

A compressor that compresses the refrigerant and
A first heat exchanger that condenses the compressed refrigerant,
An expansion valve that adjusts the flow rate of the refrigerant that has passed through the first heat exchanger, and
A second heat exchanger that evaporates the refrigerant that has passed through the expansion valve and returns the evaporated refrigerant to the compressor.
A power supply circuit including a power supply switching unit that can switch the power supply path so as to drive the motor for the compressor by supplying power from either an AC power supply or a DC power supply.
A connection switching unit that can switch the connection method of the stator winding of the motor between Y connection and delta connection, and
A control unit that controls the power supply switching unit and the connection switching unit is provided.
The control unit switches the stator winding to Y connection when the motor is driven by the AC power supply, and switches the stator winding to Δ connection when the motor is driven by the DC power supply. A heat pump device that is configured to. The power supply circuit
A rectifier circuit for rectifying the AC voltage from the AC power supply,
The heat pump device according to claim 1, further comprising an inverter circuit that generates an AC voltage based on a DC voltage from the DC power supply or a voltage rectified by the rectifier circuit and drives the motor by the generated AC voltage. .. The power supply circuit further includes a DC / DC converter that boosts a DC voltage from the DC power supply.
When the motor is driven by the DC power supply, the power supply switching unit directly supplies the DC voltage from the DC power supply to the inverter circuit and the DC voltage boosted by the DC / DC converter. The heat pump device according to claim 2, which can be switched between supplying to an inverter circuit and supplying. When the maximum power to be supplied to the motor is equal to or greater than the threshold value, the control unit supplies the DC voltage boosted by the DC / DC converter to the inverter circuit, and the maximum power to be supplied to the motor is the threshold value. The heat pump device according to claim 3, wherein a DC voltage from the DC power supply is directly supplied to the inverter circuit when the voltage is less than. The heat pump device according to claim 2, wherein when the motor is driven by the DC power supply, the DC voltage from the DC power supply is directly supplied to the inverter circuit without being boosted. The heat pump device according to any one of claims 1 to 5, wherein the control unit switches the power supply path of the power supply switching unit based on a command from a central management device of a HEMS (Home Energy Management System).

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