JP3061882B2 - Control device for air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner having an inverter device for controlling the number of revolutions of a compressor.

[0002]

2. Description of the Related Art In recent years, a large number of air conditioner control devices for controlling the capacity by increasing or decreasing the number of revolutions of a compressor using an inverter circuit for varying the frequency of a power supply have been used. As a conventional technique, for example, Japanese Patent Application Laid-Open No. 58-153
No. 589.

Hereinafter, a control device of the above-described air conditioner will be described with reference to the drawings. FIG. 4 is a schematic configuration diagram of a control device of a conventional air conditioner, FIG. 5 is a flowchart for explaining the operation when the power is turned on, and FIG. 6 is a time chart for explaining the operation.

In FIG. 4, reference numeral 1 denotes a three-phase commercial AC power supply;
Reference numeral 2 denotes an electromagnetic contactor having three contacts, and 3 denotes a converter circuit for converting AC power to DC power. One end of the electromagnetic contactor 2 is connected to the commercial AC power supply 1 and the other end is connected to the AC input of the converter circuit 3. Connected to the unit.

[0005] 4 is an inrush current limiting resistor, 5 is a main current relay, 6 is a capacitor for smoothing the DC power output from the converter circuit 3, and an inrush current limiting resistor 4 is connected in parallel with the main current relay 5 and has one end. The other end is connected to the positive electrode side of the converter circuit 3 and the other end is connected to the positive electrode side of the capacitor 6. The negative side of the capacitor 6 is connected to the negative side of the converter circuit. Reference numeral 7 denotes an inverter circuit which inputs the DC power smoothed by the capacitor 6, converts the DC power into three-phase AC power, and outputs the AC power to the compressor 8.

Reference numeral 9 denotes an operation command input unit for determining operation / stop of the compressor 8, reference numeral 10 denotes inverter control means, reference numeral 11 denotes voltage detection means for detecting a voltage across the capacitor 6, and inverter control means 10 denotes an operation command input unit. 9 and a signal from the voltage detecting means 11 are input.

[0007] Reference numeral 12 denotes a relay driving means which receives a signal from the inverter control means 10 and outputs a signal to the electromagnetic contactor 2 and the main current relay 5. An inverter base drive circuit 13 receives a signal from the inverter control means 10 and outputs the signal to the inverter circuit 7. Reference numeral 14 denotes a base drive power supply that supplies a voltage to the inverter base drive circuit 13.

The operation of the conventional air conditioner control device configured as described above will be described below with reference to FIGS. 5 and 6. FIG.

In FIG. 5, in step a, the commercial AC power source 1
Is input. Next, in step b, a signal S1 is output from the operation command input unit 9 to the inverter control means 10, and if "operation", the process proceeds to step c, otherwise, step b is repeated.

Next, at step c, the inverter control means 1
The signal S2 is output to the relay driving means 12 from 0, and the signal S3 is output to the electromagnetic contactor 2 from the relay driving means 12 to turn on the electromagnetic contactor 2. When the electromagnetic contactor 2 is turned on, the capacitor 6 is charged via the converter circuit 3 and the rush current limiting resistor 4.

Next, at step d, the charged voltage of the capacitor 6 is detected by the voltage detecting means 11 and a signal S4 is outputted to the inverter control means 10. If the charged voltage is equal to or more than the specified voltage, go to step e. Repeats step d.

Next, in step e, a signal S2 is output from the inverter control means 10 to the relay drive means 12, and
Further, the signal S5 is transmitted from the relay driving means 12 to the main current relay 5
To turn on the main current relay 5 and turn on the inverter circuit 7
Supply DC power to

Next, at step f, a signal S6 (actually, a waveform signal of the inverter) is sent from the inverter control means 10.
To the inverter base drive circuit 13 and further drive the inverter circuit 7 to supply AC power of a predetermined frequency to the compressor 8 (step g). At this time, the power supply voltage supplied to the inverter base drive circuit 13 is supplied via the base drive power supply 14 at the same time when the electromagnetic contactor 2 in step c is turned on.

The time chart of FIG. 6 shows the temporal change of the above-described operation. At the same time as the operation command input is activated, the electromagnetic contactor 2 is turned on, the charging of the capacitor 6 is started, and the voltage gradually increases. The main current relay 5 is turned on at the same time as the charging voltage of the capacitor 6 reaches the specified voltage after a lapse of time t after the start of operation, and the compressor 8 starts operating.

[0015]

However, in the above-described conventional configuration, after the charging of the capacitor 6 is completed, the main current relay 5 keeps the contact always on while the compressor 8 is operating. In addition, since it is necessary to secure a current value to be supplied to the compressor 8 as its contact capacity, it is necessary to use a contact having a large contact current capacity. , Which also increases costs. Further, a large amount of electric power is required to drive the main current relay 5, and there is a problem that a power supply for supplying a voltage to the relay becomes large.

The present invention has been made in view of the above problems, and provides a control device for an air conditioner that reduces the size and cost of a device for charging a capacitor 6 and does not generate wasteful power consumption. is there.

[0017]

SUMMARY OF THE INVENTION In order to solve the above problems, a control device for an air conditioner according to the present invention comprises a relay which is turned on / off by an external signal instead of a conventional rush current limiting resistor and a main current relay. A relay makes the pair of inputs and outputs of the electromagnetic contactor conductive and connects the other input of the electromagnetic contactor and the positive output of the converter circuit from the current limiting resistor and the other input of the electromagnetic contactor to the positive output of the converter circuit. There is provided an inrush current limiting circuit that conducts through a diode whose forward direction is the direction toward the forward direction.

A differentiating means for differentiating the output of the voltage detecting means is provided. The relay driving means outputs a signal to the electromagnetic contactor and the rush current limiting circuit to open and close the electromagnetic contactor and turn on / off the relay of the rush current limiting circuit. And the inverter control means causes the relay drive means to output a signal for turning on the relay when the operation command input unit receives an operation signal.

Further, the inverter control means controls the relay driving means to output a signal for turning off the relay and to output a signal for closing the electromagnetic contactor when the value obtained by the differentiation of the differentiating means becomes equal to or less than a predetermined value. Output
Further, a signal for driving the inverter circuit is output to the inverter base drive circuit.

[0020]

According to the present invention, the rush current limiting circuit is operated only when the capacitor is being charged, and the rush current limiting circuit can be turned off during the operation of the compressor after the charging, so that wasteful power is generated. That is, the power supply circuit can be downsized. Furthermore, since the contact capacity of the relay of the inrush current limiting circuit only needs to be able to guarantee the inrush current (limited by the current limiting resistor) to the capacitor, a small contact capacity is sufficient, and the device can be reduced in size and cost. .

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a control device of an air conditioner according to an embodiment of the present invention. The same components as those of the related art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a configuration of a control device of an air conditioner according to an embodiment of the present invention. In FIG. 1, 1
Reference numeral 5 denotes a differentiating means for differentiating the output of the voltage detecting means 11.

Reference numeral 16 denotes an inrush current limiting circuit, which includes two contacts 1
It comprises a current limiting relay 17 having 7a, 17b, a current limiting resistor 18, and a diode 19. One end of the current limiting resistor 18 is connected to the R phase of the commercial AC power supply 1 and the other end is connected to the anode terminal of the diode 19. Diode 1
The cathode terminal 9 is connected to the normally open terminal of the contact 17a. The common terminal of the contact 17a is connected to the positive electrode of the capacitor 6. The common terminal of the contact 17b is connected to the S-phase of the commercial AC power supply 1, and the normally open terminal of the contact 17b is connected to the S-phase input of the converter circuit 3. Reference numeral 20 denotes a relay driving unit that outputs a signal to the electromagnetic contactor 2 and the rush current limiting circuit. An inverter control unit 21 controls the relay drive unit 20 and outputs a signal to the inverter base drive circuit 13. The inverter control unit 21 receives signals from the operation command input unit 9 and the differentiating unit 15.

The operation of the air conditioner control device configured as described above will be described with reference to FIGS. 2, 3 and 7. FIG.

FIG. 2 is a flowchart for explaining the operation of the present invention, FIG. 3 is a time chart for explaining the operation of the present invention,
FIG. 7 is a diagram showing a voltage drop of a charging voltage during charging according to the present invention.

In FIG. 2, in step 1, the commercial AC power source 1
Is input. Next, in step 2, a signal S8 is output from the operation command input unit 9 to the inverter control means 21. If "operation", the process proceeds to step 3, otherwise, step 2 is repeated. Next, in step 3, the signal S9 is output from the inverter control means 21 to the relay driving means 20, and the signal S10 is further transmitted from the relay driving means 20 to the current limiting relay 1.
7 to turn on the contacts 17b and 17c. Contact 17
When b and 17c are turned on, the capacitor 6 is charged via the current limiting resistor 18, the current limiting relay 17, and the diode 19. Next, in step 4, the charging voltage of the capacitor 6 is detected by the voltage detecting means 11, and the signal S11 differentiated by the differentiating means 15 is output to the inverter control means 21. If the signal S11 is equal to or less than the specified value, step 5 Otherwise, repeat step 3.

Next, at step 5, a signal S9 is output from the inverter control means 21 to the relay drive means 20, and
Further, the signal S10 is output from the relay driving means 20 to the current limiting relay 17, and the contact 17a is switched to the contact 17b.
The contact 17c is turned off. Next, in step 6, the signal S12 is output from the relay driving means 20 to the electromagnetic contactor 2, and the electromagnetic contactor 2 is turned on. At this time, the contact 17a is connected to the base drive power supply 14, and the inverter base drive circuit 13 can obtain the power supply voltage generated by the base drive power supply 14, and supplies DC power to the inverter circuit 7.

Next, in step 7, a signal S13 (actually, a waveform signal of the inverter) is output from the inverter control means 21 to the inverter base drive circuit 13, and the inverter circuit 7 is further driven to compress AC power of a predetermined frequency. To the machine 8 (step 8).

The time chart of FIG. 3 shows a temporal change of the above-mentioned operation. At the same time as the operation command input is activated, the current limiting relay 17 is turned on and the capacitor 6 is turned on.
Is started and gradually rises, and at the same time as the time change rate of the charging voltage of the capacitor 6 (output of the differentiating means 15) becomes equal to or less than a specified value after a lapse of time t after the start of operation, the current limiting relay 17 is turned off. , Turn on the electromagnetic contactor 2,
The operation of the compressor 8 is started.

FIG. 7 shows the input voltage on the horizontal axis and the charging voltage of the capacitor 6 on the vertical axis. In FIG. 7, the current limiting relay 1
7, the charging voltage when ON is indicated by a dashed line, and the charging voltage when the electromagnetic contactor 2 is ON is indicated by a solid line (ΔV indicates a voltage drop). When the current limiting relay 17 is ON, the capacitor 6 is charged via the current limiting resistor 18.
The voltage drop occurring at 8 causes a reduction in the charging voltage. Therefore, in order to determine the completion of the charging of the capacitor 6, the time change of the charging voltage is detected by using the differentiating means 15.

As described above, according to the present embodiment, the R phase of the commercial AC power supply 1, the current limiting resistor 18, the current limiting relay 17
By providing a contact 17a, a diode 19, a positive electrode of the condenser 6, a contact 17b of the S-current limiting relay 17 of the commercial AC power supply 1, and an inrush current limiting circuit 16 constituting an S-phase input portion of the converter circuit 3. , Condenser 6
Since the current limiting relay 17 is turned on only when charging, the current capacity of the contact only needs to be the current at the time of charging.

Therefore, the entire inrush current limiting circuit 16 can be reduced in size. During operation, the current limiting relay 17
Can be turned off, the power supply of the control circuit can be reduced in size, and unnecessary power consumption can be suppressed. Further, since the detection of the completion of charging is performed not based on the absolute value of the charging voltage but on the rate of change thereof, the inrush current limiting resistor 1 during charging is not detected.
8, the end of the charging can be detected ideally without being affected by the voltage drop or the input voltage fluctuation.

Although the inrush current limiting circuit 16 is provided between the R and S phases, it may be provided between the S and T phases and between the T and R phases.

[0034]

As described above, according to the present invention, instead of the conventional inrush current limiting resistor and main current relay, a relay which is turned on / off by an external signal is provided, and a pair of input and output of the electromagnetic contactor is provided by the relay. And conducts the other input of the electromagnetic contactor and the positive output of the converter circuit through a current limiting resistor and a diode whose forward direction is from the other input of the electromagnetic contactor to the positive output of the converter circuit. An inrush current limiting circuit is provided.

Further, differentiating means for differentiating the output of the voltage detecting means is provided, and a relay driving means outputs a signal to the electromagnetic contactor and the rush current limiting circuit to open / close the electromagnetic contactor and turn on / off the relay of the rush current limiting circuit. And the inverter control means causes the relay drive means to output a signal for turning on the relay when the operation command input unit receives an operation signal.

Further, the inverter control means controls the relay drive means to output a signal for turning off the relay and a signal for closing the electromagnetic contactor when the value obtained by the differentiation of the differentiating means falls below a predetermined value. Output
Further, a signal for driving the inverter circuit is output to the inverter base drive circuit.

By configuring the control device of the air conditioner as described above, the inrush current limiting circuit is operated only when charging the capacitor, and the inrush current limiting circuit can be turned off during compressor operation after charging is completed. Therefore, no wasteful power is generated, and the contact capacity only needs to be able to guarantee the rush current (limited by the current limiting resistor) to the capacitor.
The cost can be reduced.

Further, by providing the differentiating means, the completion of charging is detected not by the absolute value of the charging voltage but by the rate of change of the charging voltage. , And can reliably detect the end of charging.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a control device of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the control device for the air conditioner in the embodiment.

FIG. 3 is a time chart for explaining the operation of the control device for the air conditioner in the embodiment.

FIG. 4 is a schematic configuration diagram of a conventional control device for an air conditioner.

FIG. 5 is a flowchart for explaining the operation of a conventional air conditioner control device.

FIG. 6 is a time chart for explaining the operation of a conventional air conditioner control device.

FIG. 7 is a correlation diagram between an input voltage and a charging current.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial AC power supply 2 Magnetic contactor 3 Converter circuit 6 Capacitor 7 Inverter circuit 9 Operation command input part 11 Voltage detection means 13 Inverter base drive circuit 15 Differentiating means 16 Inrush current limiting circuit 17 Current limiting relay 18 Current limiting resistor 19 Diode 20 Relay Drive means 21 Inverter control means

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI H02M 7/32 H02M 7/32 (72) Inventor Yasunori Nishio (56) References JP-A-4-183276 (JP, A) JP-A-4-161097 (JP, A) JP-A-62-230773 (JP, A) JP-A-62-234867 (JP, A) Open Sho 64-81663 (JP, A) Open Sho 61-165093 (JP, U) Open Sho 61-77698 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7 / 48 H02M 1/16 H02M 7/06 H02M 7/32

Claims (1)

(57) [Claims] 1. A converter circuit for converting AC power to DC power, an electromagnetic contactor for opening and closing the converter circuit and a commercial AC power supply with an external signal, and smoothing DC power converted by the converter circuit. A capacitor, an inverter circuit that inputs the DC power smoothed by the capacitor, converts the DC power into three-phase AC power, and controls the compressor, and a relay that is turned on and off by a signal from the outside, and the relay has the electromagnetic contactor. And the other input of the electromagnetic contactor and the positive output of the converter circuit are directed from the current limiting resistor and the other input of the electromagnetic contactor to the positive output of the converter circuit. A rush current limiting circuit that conducts through a diode having a forward direction, an operation command input unit that determines operation / stop of the compressor, Voltage detecting means for detecting the voltage of the capacitor, differentiating means for differentiating the output of the voltage detecting means, an inverter base drive circuit for driving the inverter circuit, and outputting signals to the electromagnetic contactor and the inrush current limiting circuit. Relay driving means, and an inverter control means for controlling the relay driving means and outputting a signal to the inverter base drive circuit,
The inverter control means causes the relay drive means to output a signal for turning on the relay when the operation command input section outputs a signal for operation, and a value obtained by differentiation of the differentiation means is equal to or less than a predetermined specified value. And when the relay drive means outputs a signal to turn off the relay and outputs a signal to close the electromagnetic contactor, and further outputs a signal to drive the inverter circuit to the inverter base drive circuit. Characteristic air conditioner control device.