JP4462015B2 - Air conditioner - Google Patents

Description

  The present invention relates to a detection method for a disconnection failure of one reactor in an air conditioner having reactors connected in parallel.

  As a conventional air conditioner, there is one as shown in FIG. 2 (see, for example, Patent Document 1).

  In FIG. 2, a DC output terminal of the bridge rectifier circuit 5 is connected to a bridge rectifier circuit 5 formed of four diodes via a reactor 1 and a reactor 2 having the same rated inductance connected in parallel from an AC power source 3. A smoothing capacitor 6 and an inverter circuit 10 are connected to each other. Reference numeral 4 denotes an AC detection means using CT, which detects an input current to the bridge rectifier circuit 5. 7 is storage means for storing a predetermined overcurrent detection set value, 8 is comparison means for comparing the detection result by the AC detection means 4 with the overcurrent detection set value and the low current set value stored in the storage means 7, The comparison result is input to the load control means 9 that controls the inverter circuit 10.

  When the comparison unit 8 detects that the detection result by the AC detection unit 4 exceeds the overcurrent set value stored in the storage unit 7, the load control unit 9 stops the inverter circuit 10, thereby Prevent input overcurrent to the device.

Further, when the detection result by the AC detection means 4 is lower than the low current set value stored in the storage means 7 by the comparison means 8, it is determined that the AC detection means 4 is abnormal, and the load control means 9 is similarly connected to the inverter. The circuit 10 is stopped.
JP 2001-204173 A

  However, in the above-described conventional configuration, when one of the reactors connected in parallel is opened due to disconnection or the like, an alternating current is generated even though all the current flows through the other connected reactor. The detection result of the detection means 4 is not affected. For this reason, when the current flows up to the overcurrent set value stored in the storage means 7, the amount of heat generated in the reactor is quadrupled because it is proportional to the square of the current, and in order to prevent this abnormal heat generation, the diameter of the reactor is increased. The problem that enormous enlargement etc. becomes necessary arises.

  In order to prevent this, as shown in FIG. 3, it is conceivable that the currents flowing through the reactor 1 and the reactor 2 are detected by the alternating current detection means 4a and 4b and input to the comparison means 8, respectively. In this case, even if either the reactor 1 or the reactor 2 is opened by setting the overcurrent set value stored in the storage means 7 to half the output overcurrent set value of the AC power supply 3. It becomes possible to prevent abnormal heat generation in the reactor.

  In this case, however, two AC current detection means are required, resulting in an increase in cost, and the overcurrent set value stored in the storage means 7 is different between the case where the reactor is configured in parallel connection and the case where the reactor is not connected in parallel. Another problem is that sharing becomes difficult.

The present invention solves the above-described conventional problems, and prevents abnormal heat generation of the other reactor when one of the reactors connected in parallel is opened with a simple configuration, and An object of the present invention is to provide an air conditioner that makes it easy to share equipment when not configured in parallel connection.

  In order to solve the above-described conventional problems, the air conditioner of the present invention detects an alternating current by inserting a CT into a bridge rectifier circuit, and causes the alternating currents flowing through the two reactors to cancel each other. It is intended to pass CT.

  As a result, the alternating currents that normally flow through the reactor are in a direction that cancels each other out with respect to the CT, so that the detection result of the alternating current by the CT is not affected during normal times, and either one of the reactors is open. In this case, since the current flowing through the reactor is superimposed on the input current of the bridge rectifier circuit with respect to CT, the output result of the alternating current will be affected. It is possible to prevent abnormal heat generation due to current concentration in the. Moreover, since the detection result of the alternating current in the normal state is the same as the detection result of the alternating current in the conventional configuration, it is possible to easily share the equipment when the reactor is connected in parallel or not. become.

  The air-conditioning apparatus of the present invention can prevent abnormal heat generation by using AC current detection means by CT when one of the reactors connected in parallel is opened, and does not connect reactors in parallel Can be easily shared.

  The present invention detects only the input AC current to the bridge rectifier circuit in the normal state by inputting each of the currents of the reactors connected in parallel to the CT that detects the AC input current to the bridge rectifier circuit in a direction that cancels each other. When either one of the reactors is disconnected, the current flowing through the reactor affects the CT detection result, so that the same detection result as the input AC current detection result in the conventional configuration is obtained. In addition, abnormal heat generation due to current concentration when the reactor is disconnected can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a configuration diagram of an air conditioner of the present invention. In FIG. 1, the same components as those in FIG.

  A circuit through which an input current I to the bridge rectifier circuit 5 flows is input to the CT of the AC detection means 4. Similarly, the current I1 flowing through the reactor 1 and the current I2 flowing through the reactor 2 are input to the CT in opposite directions so that they cancel each other.

  In normal times, since the reactor 1 and the reactor 2 have substantially the same reactance value, I1 = I2 and cancel each other out with respect to the CT of the AC detection means 4, so that the output of the AC detection means 4 is only the input current I. .

On the other hand, when the reactor 1 is in an open state due to disconnection or the like, the current I2 flowing through the reactor 2 is equal to the input current I. Therefore, the output result of the AC detection means 4 is equal to twice the input current I. Here, when the current flows up to the overcurrent set value stored in the storage means 7, the maximum current flowing through the reactor I2 is half of the overcurrent set value, and thus the same as when the reactor 1 is not disconnected. Thus, abnormal heat generation due to current concentration in the reactor 2 can be prevented.

  Similarly, when the reactor 2 is opened, the current flowing through the reactor 1 is equal to the input current I, but the input current I and the current I1 flowing through the reactor 1 are opposite to the CT of the AC detection means 4. Since the direction is input, the output result of the AC detecting means 4 is always zero. Therefore, since the detection result of the AC detection means 4 is lower than the low current set value stored in the storage means 7, it is determined that the AC detection means 4 is abnormal, and the inverter circuit 10 is stopped. Alternatively, the operation may be continued within a range in which the reactor 2 is not overheated by reducing the output without immediately stopping.

  As described above, in the present embodiment, when the current of the reactor 1 and the reactor 2 is input to the CT of the AC detection unit 4 in a direction that cancels each other, even when one of the reactors is disconnected, Abnormal heat generation due to current concentration can be prevented, and the same overcurrent setting value and low current setting value can be used as before, making it easy to share with devices that do not have a reactor connected in parallel. be able to.

  As described above, the power supply apparatus according to the present invention can prevent abnormal heat generation due to current concentration in the other reactor when one of the reactors connected in parallel is disconnected. It can be applied to an outdoor unit of an air conditioner used in parallel connection.

Configuration diagram of the air conditioner of the present invention Configuration diagram of conventional air conditioner Other configuration diagram of conventional air conditioner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Reactor 3 AC power supply 4 AC detection means 5 Bridge rectifier circuit 6 Smoothing capacitor 7 Storage means 8 Comparison means 9 Load control means 10 Inverter circuit 11 Compressor I Input current of bridge rectifier circuit 5 I1 Current flowing through reactor 1 I2 Reactor Current flowing through 2

Claims (1)

A first reactor and a second reactor having the same rated inductance are connected in parallel and provided between an AC power source and a bridge rectifier circuit, and an inverter circuit is configured at the DC output terminal of the bridge rectifier circuit. Load control means for controlling the inverter circuit; AC current detection means for detecting an AC current flowing through the AC power supply by CT; and storage means for storing a predetermined overcurrent set value and a predetermined low current set value. And a comparison means for comparing the detection result by the AC current detection means with the overcurrent set value or the low current set value stored in the storage means, and the CT is inputted with a total input current from the AC power supply. In addition, the current flowing through the first reactor is input in phase with the input current, the current flowing through the second reactor is input in reverse phase with the input current, When the inverter circuit is a comparison result by the comparison means during operation are matched, the air conditioning apparatus and performs control to stop the inverter circuit by the load control means.

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