WO2019116509A1

WO2019116509A1 - Air conditioner

Info

Publication number: WO2019116509A1
Application number: PCT/JP2017/044939
Authority: WO
Inventors: 貴寛平田; 宏昭鈴木
Original assignee: 三菱電機株式会社
Priority date: 2017-12-14
Filing date: 2017-12-14
Publication date: 2019-06-20
Also published as: JP6925448B2; JPWO2019116509A1

Abstract

An air conditioner (100) comprising: a converter unit (13), which has a first and a second input terminal (131, 132), the second input terminal being connected to a commercial AC power supply (1), and which converts a first AC voltage input from the first and second input terminals to DC voltage, which is then output; an inrush current limiting circuit (8), which has a plurality of resistors (2, 5) connected between the commercial AC power supply and the first input terminal, and a plurality of relays (4, 7) capable of short-circuiting or opening both ends of the respective resistors; an inverter unit (14), which converts the DC voltage output by the converter unit to a second AC voltage, which is then supplied to a motor (21); a temperature detection unit (9) for detecting the temperature of the resistors; and a microcomputer (50) which, after a signal related to operation of the motor is received and before operating the converter unit and the inverter unit, controls the relays on the basis of a comparison between the temperature and a threshold value.

Description

Air conditioner

The present invention relates to an air conditioner provided with an inrush current limiting circuit.

In an air conditioner, an inrush current limiting circuit composed of an inrush current limiting resistor and a relay has been conventionally used as a circuit for limiting inrush current when power is supplied from a commercial AC power supply.

For example, in Patent Document 1, the inrush current limiting circuit is operated with reliability by opening the relay contact in the standby state of the device, thereby eliminating the problem that the device does not operate due to the failure of the relay. There is. And in patent document 1, relay control is used which eliminates the power loss which generate | occur | produces with the driving current after apparatus operation by short-circuiting a relay contact when predetermined time passes after the electric power supply from commercial alternating current power supply.

In Patent Document 1, the resistance value of the inrush current limiting resistor for limiting the inrush current is set so as to satisfy the pulse limit power without imposing an excessive load on the elements and devices inside the rectifying and smoothing circuit. The resistance is selected so as not to destroy itself and to satisfy the rated power.

JP, 2010-104109, A

However, if the relay control method is adopted such that the relay contact is opened when the device is on standby as described above, the inrush current limiting resistor generates heat if an abnormal voltage is applied to the inrush current limiting circuit. The resistance value of the inrush current limiting resistor may not return to the normal value. In that case, there is a problem that the rush current limiting circuit does not operate normally when starting operation from the standby time, and the air conditioner does not operate and can not be operated.

The present invention has been made in view of the above, and it is an object of the present invention to obtain an air conditioner that can realize stable operation even when the resistance that constitutes the inrush current limiting circuit generates heat.

In order to solve the problems described above and to achieve the object, the present invention has first and second input terminals, and the second input terminal is connected to a commercial AC power supply, and the first and second input terminals are connected. A converter unit for converting a first alternating voltage input from the input terminal of the switch into a direct voltage and outputting the same, a plurality of resistors connected between the commercial alternating current power supply and the first input terminal, and a plurality of resistors And an inverter unit that converts a DC voltage output from the converter unit into a second AC voltage and supplies the second AC voltage to the motor. Furthermore, according to the present invention, the temperature detection unit for detecting the temperature of the resistor, and the temperature and the threshold are compared before the converter unit and the inverter unit are operated after receiving the signal related to the operation of the motor. A control unit is provided to execute control of the relay on the basis of the control unit.

ADVANTAGE OF THE INVENTION The air conditioner concerning this invention has an effect that it becomes possible to implement | achieve a stable driving | operation, even when the resistance which comprises a rush current restriction circuit heat | fever-generates.

Block diagram of an air conditioner provided with an inrush current limiting circuit according to an embodiment of the present invention Flow chart for explaining the operation of the air conditioner according to the embodiment Block diagram showing the configuration of a microcomputer according to the embodiment

Below, the air conditioner concerning embodiment of this invention is demonstrated in detail based on drawing. The present invention is not limited by the embodiment.

Embodiment.
FIG. 1 is a block diagram of an air conditioner 100 provided with an inrush current limiting circuit 8 according to an embodiment of the present invention. The air conditioner 100 includes an inrush current limiting circuit 8 for limiting inrush current, a temperature detection unit 9 for detecting the temperature of the inrush current limiting resistor of the inrush current limiting circuit 8, and a third supplied from the commercial AC power supply 1. 1, converter unit 13 for converting AC power into DC power, inverter unit 14 for converting DC power supplied from converter unit 13 into second AC power and supplying it to motor 21, motor 21, relay coil A drive circuit 15, a microcomputer 50 which is a control unit, and a power supply circuit 22 are provided.

Inrush current limiting circuit 8 includes resistors 2 and 5 connected in series for inrush current limiting, and relays 4 and 7. The resistors 2 and 5 are resistors for limiting the inrush current applied instantaneously at the time of power input from the commercial AC power supply 1. The relay 4 that is the first relay includes a relay contact 30 connected in parallel to the resistor 2 that is the first resistor, and a relay excitation coil 3 that controls the opening and closing of the relay contact 30. Both ends of the relay contact 30 are respectively connected to both ends of the resistor 2. A state in which the relay contact 30 is closed and the both ends of the resistor 2 are shorted is referred to as a closed state of the relay 4, and a state in which the relay contact 30 is opened and both ends of the resistor 2 are open is referred to as an open state of the relay 4. The relay 7 which is a second relay includes a relay contact 60 connected in parallel to the resistor 5 which is a second resistor, and a relay excitation coil 6 which controls the opening and closing of the relay contact 60. Both ends of the relay contact 60 are respectively connected to both ends of the resistor 5. A state in which the relay contact 60 is closed and the both ends of the resistor 5 are shorted is referred to as a closed state of the relay 7, and a state in which the relay contact 60 is opened and both ends of the resistor 5 are open is referred to as an open state of the relay 7. The relay coil drive circuit 15 drives the relay excitation coils 3 and 6 to control the open / close state of the relays 4 and 7. The number of resistors provided in the inrush current limiting circuit 8 is not limited as long as it is plural, and it may not be series connection but may be parallel connection or combination of series connection and parallel connection.

Further, specifically, the temperature detection unit 9 detects the temperatures of the resistor 2 and the resistor 5, respectively.

An example of the resistor 2 and the resistor 5 is a thermistor having a positive temperature coefficient, that is, a positive temperature coefficient (PTC) thermistor. Having a positive temperature coefficient is a resistance change characteristic in which the resistance value increases with an increase in temperature. The PTC thermistor is a thermistor whose resistance value rapidly increases with the rise in temperature when the temperature exceeds the Curie temperature determined for each thermistor, and the current does not flow. At least one of the plurality of resistors provided in the inrush current limiting circuit 8 may be a thermistor having a positive temperature coefficient.

The converter unit 13 includes a first input terminal 131, a second input terminal 132, a first output terminal 133, a second output terminal 134, a booster circuit 10, a diode bridge 11, and a smoothing capacitor 12. The resistor 2 and the resistor 5 are connected between the first input terminal 131 and the commercial AC power supply 1, and the second input terminal 132 is connected to the commercial AC power supply 1. The resistor 2 and the resistor 5 may be connected between the second input terminal 132 and the commercial AC power supply 1, and the first input terminal 131 may be connected to the commercial AC power supply 1. Converter unit 13 converts the first AC voltage supplied from first input terminal 131 and second input terminal 132 into DC voltage and outputs the DC voltage to first output terminal 133 and second output terminal 134. The inverter unit 14 converts the DC voltage output from the first output terminal 133 and the second output terminal 134 of the converter unit 13 into a second AC voltage, and supplies the second AC voltage to the motor 21.

The microcomputer 50 is driven by a dedicated power supply circuit 22. The user can operate a remote controller (hereinafter referred to as a remote control) not shown, and the microcomputer 50 maintains the remote control standby state until a remote control operation from the user is input. The microcomputer 50 includes a relay control unit 16 for controlling the relay coil drive circuit 15, a remote control control unit 17 for receiving a remote control signal which is a signal from a remote control by the user's remote control operation, and a detected temperature detected by the temperature detection unit 9. And a temperature determination unit 18 that executes the temperature determination based on The remote control signal is a signal related to the operation of the motor 21 such as operation start, operation stop, heating start, and cooling start. In the remote control standby state, the microcomputer 50 can receive the remote control signal.

When the power from the commercial AC power supply 1 is supplied at the start of operation of the air conditioner 100, the inrush current limiting circuit 8 limits the current by the resistor corresponding to the relay in the open state. However, since the relays 4 and 7 are open in the stopped state of the air conditioner 100, the resistance value of the resistor 2 may increase due to heat generation when an abnormal voltage is applied, and the current may not flow. In this case, when the air conditioner 100 starts operation from the stop state while the relay 4 is open, no voltage is applied from the inrush current limiting circuit 8 to the circuit at the subsequent stage.

Therefore, in the air conditioner 100 according to the present embodiment, when the remote control signal is input to the remote control control unit 17 by the user's remote control operation, based on the temperature of the resistor 2 detected by the temperature detection unit 9 The temperature determination unit 18 of the microcomputer 50 executes the temperature determination. Then, when the temperature determination unit 18 determines that the temperature of the resistor 2 detected by the temperature detection unit 9 is higher than the first threshold set for the resistor 2, the relay coil drive circuit 15 from the relay control unit 16 A signal instructing to drive the relay excitation coil 3 is output to the relay coil drive circuit 15. The relay coil drive circuit 15 controls the relay 4 to be in a closed state.

That is, when the abnormal voltage is applied while the air conditioner 100 is stopped and the operation is started from the stopped state with the resistor 2 generating heat, the relay 4 is controlled to be closed, so the rush current Since the limiting circuit 8 uses only the resistor 5, the operation of the air conditioner 100 can be started with the inrush current limited.

FIG. 2 is a flowchart for explaining the operation of the air conditioner 100 according to the embodiment. Hereinafter, the operation of the air conditioner 100 will be described with reference to FIG.

First, the microcomputer 50 driven by the dedicated power supply circuit 22 is in the remote control standby state (step S11). The remote control control unit 17 of the microcomputer 50 determines whether or not the remote control signal by the user's remote control operation has been received (step S12). If the remote control signal has not been received (step S12: No), the process returns to step S11.

If the remote control control unit 17 determines that the remote control signal has been received (step S12: Yes), the temperature determination unit 18 determines whether the temperature of the resistor 2 detected by the temperature detection unit 9 is less than or equal to the first threshold. (Step S13). The first threshold value is a value determined by the element temperature characteristic of the resistor 2, the operable temperature data of the resistor 2, the breakdown temperature of the resistor 2, etc. There is.

When it is determined that the temperature of the resistor 2 which is the first resistor is higher than the first threshold (step S13: No), the relay control unit 16 sends a signal to the relay coil drive circuit 15 to perform the first relay. The relay 4 is controlled to be in the closed state (step S14). On the other hand, when the temperature of the resistor 2 is determined to be equal to or lower than the first threshold (step S13: Yes), and after step S14, the received remote control signal instructs "start operation" after step S14. It is determined whether it is a signal (step S15).

If it is determined in step S15 that the received remote control signal is a signal instructing "start of operation" (step S15: Yes), the air conditioner 100 starts operation (step S16). Specifically, the microcomputer 50 operates the converter unit 13 and the inverter unit 14. After step S16, the temperature determination unit 18 determines whether or not both the temperatures of the resistors 2 and 5 which are the first and second resistors detected by the temperature detection unit 9 are less than or equal to the second threshold (see FIG. Step S17). The second threshold is a value determined by the element temperature characteristics of the resistors 2 and 5, the operable temperature data of the resistors 2 and 5, the breakdown temperature of the resistors 2 and 5, etc. It is held in advance by the department. The second threshold may be the same as or different from the first threshold.

On the other hand, if it is determined in step S15 that the received remote control signal is not a signal instructing "start of operation" as in the case of a signal instructing "stop operation" (step S15: No), the relay control unit A signal 16 is sent to the relay coil drive circuit 15 to control the relays 4 and 7, which are the first and second relays, to be open (step S19). After step S19, the air conditioner 100 stops the operation (step S20), and returns to the remote control standby state (step S11).

When it is determined in step S17 that the temperatures of both the resistors 2 and 5 are both equal to or less than the second threshold (step S17: Yes), the relay control unit 16 sends a signal to the relay coil drive circuit 15 to The relays 4 and 7, which are the second relays, are controlled to be closed (step S18). If the relay 4 is already in the closed state via step S14, the relay 7 is further controlled to be in the closed state. After step S18, the process returns to the remote control standby state (step S11).

As described above, when it is determined that the temperature detected by the resistor 2 is higher than the first threshold (step S13: No), the relay 4 is closed (step S14). As a result, since the inrush current limiting circuit 8 uses only the resistor 5, the operation of the air conditioner 100 can be started with the inrush current limited (step S16). Then, after the start of operation of the air conditioner 100, when it is determined that the temperature of both the resistors 2 and 5 is less than or equal to the second threshold (step S17: Yes), the relays 4 and 7 are both closed. It controls so that it becomes (step S18). As a result, power from the commercial AC power supply 1 can be supplied to the converter unit 13 without passing through the resistors 2, 5 which are inrush current limiting resistors, so the air conditioner 100 is operated at maximum efficiency. It will be possible to

On the other hand, when it is determined in step S17 that one of the temperatures of the resistors 2 and 5 is higher than the second threshold (step S17: No), the relay control unit 16 sends a signal to the relay coil drive circuit 15. The relays 4 and 7, which are the first and second relays, are controlled to be in the open state (step S19). After step S19, the air conditioner 100 stops the operation (step S20), and returns to the remote control standby state (step S11).

In step S13, the temperature determination unit 18 determines whether the temperature of the resistor 2 is lower than or equal to the first threshold, but if the temperature of the resistor 5 is larger than the threshold by comparing with the threshold. The relay 7 may be controlled to be closed. The resistor which is determined in step S13 that the temperature is larger than the threshold value and which is the target of the short circuit in step S14 may be selected because the resistance value is larger than that of the other resistor. This is because if the resistance value is larger than that of the other resistor, it is considered that the temperature is likely to rise by energization.

In the above description, it has been described that the user performs the operation through the remote control, but the controller of the air conditioner 100 may be installed in the air conditioner 100 main body. Therefore, the microcomputer 50 may be provided with an operation control unit instead of the remote control unit 17, and the operation control unit may be configured to determine in step S12 whether or not the signal related to the operation of the motor 21 is received. .

As described above, in the air conditioner 100 provided with the inrush current limiting circuit 8, the relay based on the temperature of the resistors 2 and 5 constituting the inrush current limiting circuit 8 when the user operates the remote control Control 4, 7 Thus, even if an abnormal voltage is applied when the air conditioner 100 is stopped, the operation failure at the start of operation caused by the heat generation of the inrush current limiting resistance at the time of the relay contact opening is avoided to prevent the inrush current. It becomes possible to limit the In addition, it is possible to prevent a failure due to element heating during operation, and stable operation can be realized.

FIG. 3 is a block diagram showing the configuration of the microcomputer 50 according to the embodiment. The microcomputer 50 includes a central processing unit (CPU) 51 that executes computations and control, a random access memory (RAM) 52 that the CPU 51 uses for a work area, and a read only memory (ROM) 53 that stores programs and data. It includes an I / O (Input / Output) 54 which is hardware for exchanging signals with the outside, and a peripheral device 55 including an oscillator for generating a clock. The control that the relay control unit 16 of the microcomputer 50, the remote control unit 17 and the temperature determination unit 18 execute according to the flowchart shown in FIG. 2 is realized by the CPU 51 executing a program that is software stored in the ROM 53. . The ROM 53 may be a non-volatile memory such as a rewritable flash memory. Therefore, the storage unit of the microcomputer 50 storing the first and second threshold values is realized by the ROM 53 or the like.

The configuration shown in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and one of the configurations is possible within the scope of the present invention. Parts can be omitted or changed.

DESCRIPTION OF SYMBOLS 1 commercial alternating current power supply, 2,5 resistor, 3,6 relay exciting coil, 4,7 relay, 8 rush current limiting circuit, 9 temperature detection part, 10 boost circuit, 11 diode bridge, 12 smoothing capacitor, 13 converter part 14 inverter unit 15 relay coil drive circuit 16 relay control unit 17 remote control control unit 18 temperature determination unit 21 motor 22 power supply circuit 30 60 relay contact 50 microcomputer 51 CPU 52 RAM 53 ROM, 54 I / O, 55 peripheral devices, 100 air conditioner, 131 first input terminal, 132 second input terminal, 133 first output terminal, 134 second output terminal.

Claims

It has first and second input terminals, and the second input terminal is connected to a commercial AC power supply, and converts the first AC voltage input from the first and second input terminals into DC voltage. A converter unit that converts and outputs,
An inrush current limiting circuit having a plurality of resistors connected between the commercial AC power supply and the first input terminal, and a plurality of relays capable of shorting or opening both ends of each of the plurality of resistors; ,
An inverter unit that converts a DC voltage output from the converter unit into a second AC voltage and supplies the second AC voltage to the motor;
A temperature detection unit that detects the temperature of the resistor;
A control unit that executes control of the relay based on a comparison between the temperature and a threshold after receiving a signal related to the operation of the motor and before operating the converter unit and the inverter unit;
An air conditioner equipped with
The plurality of resistors are a first resistor and a second resistor connected in series,
The control unit is configured to receive the signal, and before the converter unit and the inverter unit are operated, when the temperature of the first resistor is higher than a first threshold value. The air conditioner according to claim 1, wherein the relay is controlled to short-circuit both ends of a resistor.
The air conditioner according to claim 1, wherein at least one of the plurality of resistors is a thermistor having a positive temperature coefficient.