JP2007247982A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress heat generation by appropriately controlling charge/discharge current of a condenser and preventing deterioration in a service life of the condenser. <P>SOLUTION: This air conditioner is equipped with a temperature detecting means 19, a memory means 17, and a comparison means 18. When the ambient temperature of the condenser 100 exceeds a predetermined temperature, by controlling a drive signal width of a bidirectional switch 9, the charge/discharge current of the condenser can be suppressed, and the deterioration in the service life of the condenser can be suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an air conditioner using a rectification method using a bridge rectifier circuit and a power factor correction circuit using a reactor.

  As a power supply device mounted on a conventional air conditioner, there is a combination of a reactor, a bidirectional switch, and a capacitor in a bridge rectifier circuit (see, for example, Patent Document 1). FIG. 3 shows a conventional power supply device described in Patent Document 1. In FIG.

  In FIG. 3, four diodes 2 to 5 form a bridge rectifier circuit 6. A smoothing capacitor 7 is connected between the positive DC output terminal 6 c and the negative DC output terminal 6 d of the bridge rectifier circuit 6 to form a full-wave rectifier circuit, and DC power is supplied to the load 11. A reactor 8 is provided between the AC power source 1 and the AC input terminal 6a of the bridge rectifier circuit 6, and a bidirectional switch is provided between the other AC input terminal 6b and the DC output terminal 6d of the bridge rectifier circuit 6. A capacitor 10 is connected via 9.

  Further, based on the signal from the zero cross detection means 12 for detecting the zero cross point of the voltage of the AC power supply 1, a drive signal is generated by the bidirectional switch drive signal generation means 13, and the bidirectional switch drive means 14 generates the drive switch. 9 is driven.

  In the power supply device configured as described above, the bidirectional switch 9 performs a closing operation for a predetermined time from the zero cross point of the AC power supply 1, and the DC terminal voltage of the smoothing capacitor 7 sets the voltage value of the AC power supply 1. During a period exceeding the voltage, a boosting operation for boosting the DC terminal voltage of the smoothing capacitor 7 is performed by charging and discharging the capacitor 10.

Here, a current accompanying charging / discharging flows through the capacitor 10 as shown in FIG. 2, and the current value is determined by the values of the reactor 8 and the capacitor 10 and the closing operation time of the bidirectional switch 9.
JP 2002-223571 A

  However, in the above conventional configuration, since there is no means for limiting the current flowing to the capacitor, when the charge / discharge current to the capacitor increases, the capacitor generates heat, and when the ambient temperature of the capacitor is high, the life of the capacitor decreases. was there.

  The air conditioner of the present invention solves the conventional problems as described above, and aims to suppress heat generation by appropriately limiting the charge / discharge current of the capacitor and to prevent a decrease in the life of the capacitor. .

  In order to solve the above-described conventional problems, an air conditioner of the present invention includes a temperature detection unit that detects an ambient temperature around a capacitor, and a signal width suppression unit that suppresses a drive signal width of a bidirectional switch. When the ambient atmosphere temperature exceeds a predetermined temperature, the drive signal width of the bidirectional switch is suppressed so as not to exceed a certain value.

With this configuration, the charge / discharge current flowing to the capacitor is limited by the ambient temperature of the capacitor, so when the ambient temperature is high, the heat generated by the charge / discharge current is limited to a certain value or less, and the life of the capacitor is reduced. Is possible.

  Further, if an outside air temperature detecting means for detecting the outdoor temperature of the air conditioner is used as the temperature detecting means, it is not necessary to newly provide a means for detecting the ambient temperature of the capacitor, and the cost of the equipment can be reduced. .

  The air conditioner of the present invention can prevent the lifetime of the capacitor from being reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 shows an embodiment of the configuration of an air conditioner according to the present invention, and FIG. 2 shows a conceptual diagram of the operation of the air conditioner according to the present invention as a time chart. In FIG. 1, the same components as those in FIG.

  In FIG. 1, an inverter circuit 15 is connected to the DC output terminal of the smoothing capacitor 7, and the output of the inverter circuit 15 is connected to the compressor 16.

  In FIG. 1, the temperature detection means 19 detects the ambient temperature of the capacitor 10. On the other hand, a predetermined temperature T is stored in the storage unit 17 and is compared with the temperature detected by the temperature detection unit 19 by the comparison unit 18. The signal width suppression means 15 limits the drive signal of the bidirectional switch 9 generated by the bidirectional switch drive signal generation means 13 to the first time t1 and the second time t2, and Output. Here, the signal width suppression unit 15 limits the first time t1 when the comparison result by the comparison unit 18 indicates that the ambient temperature of the capacitor 10 is equal to or lower than the temperature T stored in the storage unit 17. When the temperature T is exceeded, the second time t2 is limited. The second time t2 is set to be less than the first time t1.

  The charging / discharging current flowing through the capacitor 10 is determined by the voltage of the AC power source 1, the inductance of the reactor 8, the capacitance of the capacitor 10, and the closing operation time of the bidirectional switch 9. Therefore, by limiting the drive signal width of the bidirectional switch 9 as described above, the current I1 is limited at the second time t2 when limited at the first time t1, as shown in FIG. In this case, the current I2 becomes the maximum of the current flowing through the capacitor 10, respectively.

  As a result, when the ambient temperature of the capacitor 10 is high, the charge / discharge current flowing through the capacitor 10 is suppressed, and it is possible to suppress a decrease in life due to heat generation.

  Further, in the air conditioner provided with an outside air temperature detecting means (not shown) for detecting the outdoor temperature of the air conditioner, a temperature detecting means is newly provided by using the outside air temperature detecting means as the temperature detecting means 19. Therefore, the same effect can be obtained, and the cost of the device can be reduced.

  In the present embodiment, the temperature stored in the storage means is one, and the time for limiting the drive signal of the bidirectional switch 9 is only the first time and the second time. However, the same effect can be obtained if the temperature detection means is provided and the drive signal width of the bidirectional switch 9 is limited at a predetermined temperature.

  As described above, according to the air conditioner of the present invention, it is possible to suppress the charge / discharge current to an appropriate value regardless of the influence of the ambient temperature of the capacitor, and it is possible to suppress a decrease in the life of the capacitor.

Configuration diagram of the air conditioner of the present invention Time chart explaining the operation of the air conditioner of the present invention Configuration diagram of conventional power supply

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2, 3, 4, 5 Diode 6 Bridge rectifier circuit 6a, 6b AC input terminal 6c of bridge rectifier circuit, 6d DC input terminal of bridge rectifier circuit 7 Smoothing capacitor 8 Reactor 9 Bidirectional switch 10 Capacitor 11 Signal width suppression Means 12 Zero cross detection means 13 Bidirectional switch drive signal generation means 14 Bidirectional switch drive means 15 Inverter circuit 16 Compressor 17 Storage means 18 Comparison means 19 Temperature detection means

Claims (2)

A rectifier circuit for full-wave rectification of AC from an AC power source, a smoothing capacitor and an inverter circuit connected to a DC output terminal of the rectifier circuit, and an AC input terminal of the AC power source and the bridge rectifier circuit. A reactor, a capacitor connected via a bidirectional switch between an AC input terminal and a DC output terminal of the bridge rectifier circuit, zero-cross detection means for detecting a zero point of the voltage of the AC power supply, and the zero-cross Bidirectional switch drive signal generating means for generating a drive signal for the bidirectional switch based on the output of the detecting means; and bidirectional switch drive means for driving the bidirectional switch based on the signal of the bidirectional switch drive signal generating means; Temperature detecting means for detecting the ambient temperature of the capacitor, and signal width suppressing means for suppressing the drive signal width of the bidirectional switch And an air conditioner that suppresses the drive signal width of the bidirectional switch for a predetermined time by the signal width suppression means when the temperature detected by the temperature detection means exceeds a predetermined temperature. . The air conditioner according to claim 1, wherein an outside air temperature detecting means for detecting an outdoor air temperature is used as the temperature detecting means.

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