Air conditioner

Abstract

To improve the degree of freedom when installing an outdoor machine.SOLUTION: An air conditioner comprises: a compressor motor; an outdoor fan motor; an inverter device including an inverter circuit; an input device provided outside the inverter device in an outdoor machine; a protection control unit for changing a protection current value for a current in the air conditioner in accordance with a user operation on the input device; and a drive control unit for determining whether or not to perform protection control operation for decreasing an output frequency of the inverter circuit on the basis of a DC current of the compressor motor, a DC current or a rotation speed of the outdoor fan motor, and the protection current value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an air conditioner.

Background Art

[0002] In an air conditioner that performs drive control by changing the output frequency of a compressor with an inverter device, protection control is known in which the output frequency of the inverter is decreased when the inverter primary current becomes equal to or greater than a protection current value. Patent Document 1 discloses a technique for inverter primary current protection control that directly detects the instantaneous value of the primary current and limits the operating frequency so as not to exceed a protection current value (set value).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There are cases where existing wiring is used as power wiring, such as when relocating or replacing the outdoor unit of an air conditioner. However, as described above, the protection current value for protecting the air conditioner is uniquely determined, and it is not possible to change the protection current value at the location where the outdoor unit is installed. Therefore, when the allowable current value of the existing wiring is smaller than the protection current value, it is not possible to install the outdoor unit using the existing wiring.

[0005] The present invention has been made in view of such problems, and an object thereof is to improve the degree of freedom when installing an outdoor unit.

Means for Solving the Problems

[0006] The present invention relates to an air conditioner, comprising a compressor motor, an outdoor fan motor, an inverter device including an inverter circuit, an input device provided outside the inverter device in an outdoor unit, a protection control unit that changes a protection current value of an electric current in the air conditioner according to a user operation on the input device, a direct current of the compressor motor, a direct current or a rotation speed of the outdoor fan motor, and a drive control unit that determines whether to perform a protection control operation of reducing an output frequency of the inverter circuit based on the protection current value.

Effect of the Invention

[0007] According to the present invention, the degree of freedom at the time of installing the outdoor unit can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] FIG. 1 is a configuration diagram of an air conditioner 1 according to an embodiment. The air conditioner 1 performs air conditioning by circulating a refrigerant in a refrigeration cycle. As shown in FIG. 1, the air conditioner 1 includes an indoor unit 10 installed indoors (the space to be air-conditioned) and an outdoor unit 20 installed outdoors (outdoor).

[0010] The indoor unit 10 and the outdoor unit 20 are connected by a refrigerant circuit Q. The solid line arrows shown in FIG. 1 indicate the flow of the refrigerant during heating operation. The broken line arrows shown in FIG. 2 indicate the flow of the refrigerant during cooling operation.

[0011] The indoor unit 10 includes an indoor heat exchanger 14, an indoor fan 15, and an indoor fan motor 16. In the indoor heat exchanger 14, heat exchange occurs between the refrigerant flowing through its heat transfer tubes and the indoor air sent in from the indoor fan 15. The indoor heat exchanger 14 operates as a condenser or an evaporator by switching the four-way valve 27 described later. The indoor fan 15 is installed near the indoor heat exchanger 14. The indoor fan 15 sends indoor air into the indoor heat exchanger 14 by driving the indoor fan motor 16.

[0012] The outdoor unit 20 includes a compressor 21, a compressor motor 22, an outdoor heat exchanger 23, an outdoor fan 24, an outdoor fan motor 25, an expansion valve 26, and a four-way valve 27. The compressor 21 compresses the low-temperature and low-pressure gas refrigerant and discharges it as a high-temperature and high-pressure gas refrigerant by driving the compressor motor 22 described later. In the outdoor heat exchanger 23, heat exchange occurs between the refrigerant flowing through its heat transfer tubes and the outside air sent in from the outdoor fan 24. The outdoor heat exchanger 23 operates as a condenser or an evaporator by switching the four-way valve 27.

[0013] As shown in FIG. 1, the outdoor fan 24 is installed near the outdoor heat exchanger 23. The outdoor fan 24 sends outside air into the outdoor heat exchanger 23 by driving the outdoor fan motor 25. The expansion valve 26 has a function of decompressing the refrigerant condensed in the "condenser" (one of the outdoor heat exchanger 23 and the indoor heat exchanger 14). Note that the refrigerant decompressed in the expansion valve 26 is led to the "evaporator" (the other of the outdoor heat exchanger 23 and the indoor heat exchanger 14). The four-way valve 27 is a valve that switches the refrigerant flow path according to the operation mode of the air conditioner 1.

[0014] The outdoor unit 20 further includes an inverter device 200 and an interface 210. The inverter device 200 includes a control unit 201. The control unit 201 includes a CPU and a memory, and controls the inverter circuit and the like, which will be described later. As shown in FIG. 2, the inverter device 200 further includes a converter section 300 and an inverter section 310. The converter section 300 includes a rectifier circuit 301, a smoothing reactor 302, and a smoothing capacitor 303. The converter section 300 converts the AC voltage from the power supply section 40 into a DC voltage and outputs it to the inverter section 310.

[0015] The inverter section 310 includes an inverter circuit 311, a first current sensor 312, and a second current sensor 313. The inverter circuit 311 converts the DC power from the converter section 300 into AC power and outputs it to the compressor motor 22. Also, the DC power output from the inverter circuit 311 is supplied to the outdoor fan motor 25. The first current sensor 312 detects the DC current output from the compressor motor 22. The second current sensor 313 detects the DC current output from the outdoor fan motor 25.

[0016] Returning to FIG. 1, the control unit 201 of the inverter device 200 includes a current estimation unit 202, a protection control unit 203, and a drive control unit 204. The current estimation unit 202 estimates the primary current of the inverter device 200 based on the DC current of the compressor motor 22 and the DC current of the outdoor fan motor 25. Hereinafter, the primary current estimated by the current estimation unit 202 is referred to as the primary current estimated value. Specifically, the current estimation unit 202 converts the DC current of the compressor motor 22 detected by the first current sensor 312 into the primary current. Further, the current estimation unit 202 converts the DC current of the outdoor fan motor 25 detected by the second current sensor 313 into the primary current. It is assumed that a relational expression between the DC current and the primary current is used for the conversion from the DC current to the primary current. As another example, a correspondence table between the DC current and the primary current may be referred to. Also, the current estimation unit 202 may use the rotation speed of the outdoor fan motor 25 instead of the DC current of the outdoor fan motor 25. In this case, the current estimation unit 202 converts the rotation speed of the outdoor fan motor 25 into the primary current. It is assumed that a relational expression between the rotation speed and the primary current is used for the conversion from the rotation speed to the primary current. Here, the actual rotation speed detected from the inverter device 200 or the target rotation speed in control is used as the rotation speed. Then, the current estimation unit 202 obtains the sum of the primary current of the compressor motor 22 and the primary current of the outdoor fan motor 25 as the primary current estimated value D.

[0017] The protection control unit 203 changes the protection current value of the air conditioner 1 according to an input by the installer of the outdoor unit 20 or the like. The drive control unit 204 performs a protection control operation when the primary current estimated value exceeds the protection current value. Here, the protection current value is a current value determined based on the maximum current value in the circuit of the air conditioner 1. When the primary current estimated value exceeds the protection current value, a protection control operation is performed. The protection control operation is a control for reducing the output frequency of the inverter circuit 311.

[0018] FIG. 3 is a diagram showing a configuration example of the interface 210. The interface 210 has three DIP switches (DSW) 211, 212, and 213. The DSWs 211, 212, and 213 are an example of an input device for inputting the allowable current value of the power wiring to which the outdoor unit 20 is connected. Different wire diameters are displayed in association with each of the DSWs 211, 212, and 213. When an installer or the like operates the DSW corresponding to the wire diameter of the power wiring connected to the outdoor unit 20, each DSW is configured so that the allowable current value corresponding to the wire diameter is input.

[0019] The interface 210 is provided, for example, on the control board 220 of the outdoor unit 20. Note that the interface 210 may be installed outside the inverter device 200 in the outdoor unit 20, and its installation location is not limited to the control board 220.

[0020] FIG. 4 is a flowchart showing current control by the inverter device 200. For example, when installing a new outdoor unit as the outdoor unit 20, an installer or the like checks the wire diameter of the power wiring for connecting the new outdoor unit at the site (installation location). Then, the user selects the wire diameter of the power wiring for connecting the new outdoor unit from among the DSWs 211, 212, and 213 of the interface 210. Correspondingly, in step S102, the protection control unit 203 acquires the allowable current value corresponding to the wire diameter.

[0021] Next, in step S104, the protection control unit 203 sets the protection current value based on the allowable current value and the protection current value set in the air conditioner 1. Specifically, when the allowable current value is greater than the protection current value, the protection control unit 203 does not change the protection current value and keeps the already set protection current value. On the other hand, when the allowable current value is smaller than the protection current value, the protection control unit 203 changes the protection current value to a value equal to the allowable current value. As another example, in this case, the protection control unit 203 may change the protection current value to a value smaller than the allowable current value. In this way, the protection control unit 203 sets a value equal to or less than the allowable current value as the protection current value.

[0022] Next, in step S106, when the power is turned on in a remote controller (not shown), the control unit 201 starts energization. Next, in step S108, the current estimation unit 202 calculates a primary current estimated value. Specifically, as described above, the current estimation unit 202 obtains the primary current from each of the DC current of the compressor motor 22 and the DC current of the outdoor fan motor 25, and obtains the sum of these as the primary current estimated value. As described above, the rotation speed may be used instead of the DC current of the outdoor fan motor 25.

[0023] Next, in step S110, the current estimation unit 202 compares the primary current estimated value calculated in step S108 with the protection current value set in step S104. Then, when the primary current estimated value is greater than or equal to the protection current value (YES in step S110), the current estimation unit 202 performs protection control (step S114), and then proceeds to step S116 for subsequent processing. Note that the protection control is a process of reducing the output frequency in the inverter circuit 311. On the other hand, when the primary current estimated value is less than the protection current value (NO in step S110), the current estimation unit 202 performs normal control (step S112), and then proceeds to step S116 for subsequent processing. Note that the normal control is control according to the air conditioning operation set in the air conditioner 1.

[0024] In step S116, the control unit 201 determines whether to continue energization. When the power is turned off in the remote controller, the control unit 201 determines not to continue energization. When the power is not turned off, the control unit 201 determines to continue energization. When the control unit 201 determines to continue energization (YES in step S116), the process proceeds to step S108. Then, the control unit 201 repeats the processes of steps S108 to S116 until the energization ends. Then, when the control unit 201 determines not to continue energization (NO in step S116), the power control ends.

[0025] As described above, when installing the outdoor unit 20 of the air conditioner 1 of the present embodiment, at the installation location, the installer or the like can select the power wiring connected to the outdoor unit 20 at the interface 210, thereby setting a protection current value suitable for the power wiring. Therefore, even when using existing wiring, if the allowable current value of the existing wiring is smaller than the protection current value of the air conditioner 1, the existing wiring can be used. Thus, the air conditioner 1 of the present embodiment can improve the degree of freedom when installing the outdoor unit.

[0026] Furthermore, since the interface 210 is provided on the outdoor unit 20, it is possible to prevent the protection current value from being changed due to a misoperation by the user of the air conditioner 1. Also, as shown in FIG. 2, the allowable current values are displayed in association with the DSWs 211, 212, 213 on the interface 210. Therefore, even when the installer does not know the allowable current value of the power wiring, by selecting the diameter size, the allowable current value corresponding to the diameter size can be input.

[0027] Note that the present invention is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims, such as applying a modification example of one embodiment to another modification example.

[0028] As a first modification example, instead of the diameter size of the power wiring, the allowable current value may be displayed in association with the DSWs 211, 212, 213 of the interface 210.

[0029] Also, as a second modification example, as shown in FIG. 5, the interface 210 may include push switches (PSWs) 241, 242, 243 and a 7-segment (7SEG) display 230 instead of DSWs. For example, when the allowable current value is input at the PSWs 241, 242, 243, the input allowable current value is displayed on the 7SEG display 230.

Explanation of Reference Numerals

[0030] 1 Air conditioner 10 Indoor unit 14 Indoor heat exchanger 15 Indoor fan 16 Indoor fan motor 20 Outdoor unit 21 Compressor 22 Compressor motor 23 Outdoor heat exchanger 24 Outdoor fan 25 Outdoor fan motor 26 Expansion valve 27 Four-way valve 40 Power supply unit 200 Inverter device 201 Control unit 202 Current estimation unit 203 Protection control unit 204 Drive control unit 210 Interface 211, 212, 213 DSW 220 Control board 230 7SEG display 241, 242, 243 PSW 300 Converter section 301 Rectifier circuit 302 Smoothing reactor 303 Smoothing capacitor 310 Inverter section 311 Inverter circuit 312 First current sensor 313 Second current sensor

Claims

1. An air conditioner, including a compressor motor, an outdoor fan motor, an inverter device including an inverter circuit, in an outdoor unit, an input device provided outside the inverter device, a protection control unit that changes a protection current value of an electric current in the air conditioner according to a user operation on the input device, and a drive control unit that determines whether to perform a protection control operation for reducing an output frequency of the inverter circuit based on a direct current of the compressor motor, a direct current or a rotation speed of the outdoor fan motor, and the protection current value. An air conditioner comprising the above.

2. comprising a current estimation unit that estimates a primary current of the inverter device based on a direct current of the compressor motor and a direct current or a rotation speed of the outdoor fan motor, The air conditioner according to claim 1, wherein the drive control unit determines whether to perform the protection control operation based on an estimated value of the primary current and the protection current value.

3. An allowable current value in a power supply wiring connected to the air conditioner is input to the input device, The air conditioner according to claim 1, wherein the protection control unit changes the protection current value to be equal to or less than the allowable current value when the input allowable current value is smaller than the protection current value set in the air conditioner.

4. A plurality of diameter sizes of a power supply wiring connected to the air conditioner are displayed on the input device, and further, an operation unit corresponding to each diameter size is arranged. When the operation unit corresponding to the diameter size is operated, the allowable current value corresponding to the diameter size is input. The air conditioner according to claim 3.

Images