JP2007101142A - Control device for air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize loss consumed by a resistor while suppressing a higher harmonic current of a small input power circuit with inexpensive constitution. <P>SOLUTION: The outdoor unit side is provided with a load current detecting means 9 detecting the input current of an indoor unit, and an outdoor control part 11 recognizing a load current value detected by the load current detecting means. The indoor unit side is provided with a capacitor input type power circuit for rectifying an input current by a rectifying circuit 2 through the resistor 6, then smoothing it by a smoothing capacitor 3 and outputting it to the load 5 side; a switching means 7 in parallel with the resistor; and an indoor control part 8 driving the switching means. When a load current value detected by the load current detecting means 9 becomes a predetermined value or more, the switching means 7 is put in an open state to reduce reactive power generated in the resistor when the switching means is in a closed state, and a flow period of the input current is amplified by the time constants of the resistor and smoothing capacitor to improve a power factor to thereby suppress the higher harmonic current. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a so-called capacitor input type power supply circuit in which an input current from an AC power supply is rectified by a rectifier circuit such as a diode bridge, smoothed by a smoothing capacitor, and output to a load side such as a DC-DC converter or an inverter. The present invention relates to an air conditioner control device.

As shown in FIG. 4, the conventional invention rectifies the input current from the AC power source 1 through the resistor 6 by the rectifier circuit 2, smoothes it by the smoothing capacitor 3, and outputs it to the load side 5. A switching means 7, a driving means 8 for driving the opening / closing means 7 and a load current detecting means 9 for detecting a load current are provided in parallel with the resistor 6, and the load current detected by the load current detecting means 9 exceeds a predetermined value. Then, by opening the switching means 7, the reactive power consumed by the resistor 6 below a predetermined value is reduced, and the current passing period of the input current is set by the time constant of the resistor 6 and the smoothing capacitor 3. Amplification can improve power factor and suppress harmonic current.
JP-A-2005-204378

  However. In the control apparatus as described above, in the case of a multi-type air conditioner having a plurality of small input power supply circuits, a load current detection means is required for each power supply circuit, leading to an increase in the component area and cost. The present invention solves the above-described conventional problems, and aims to achieve a simpler structure at a lower cost, to reduce reactive power consumed by the resistor as much as possible, and to suppress harmonic current. It is providing the control apparatus which can implement | achieve.

  In order to solve the above-described conventional problems, the present invention provides a multi-type air conditioner including a plurality of indoor units and an outdoor unit, and a load current detection unit that detects an input current of the indoor unit on the outdoor unit side. And an outdoor control unit for recognizing the load current value detected by the load current detecting means, rectifying the input current with a rectifier circuit through a resistor on the indoor unit side, and then smoothing with a smoothing capacitor to the load side A capacitor input type power supply circuit for output, an indoor control unit for driving the switching means and the switching means in parallel with the resistor, and when the load current value detected by the load current detection means exceeds a predetermined value, The opening / closing means is in an open state.

  The control device of the present invention can reduce the loss consumed by the resistor as much as possible while suppressing the harmonic current with a more inexpensive configuration by detecting the load current at one place on the outdoor unit side. I can do it.

A first aspect of the present invention is a multi-type air conditioner composed of a plurality of indoor units and outdoor units, wherein a load current detecting means and a load current detecting means for detecting an input current of the indoor unit on the outdoor unit side Capacitor input type power supply having an outdoor control unit for recognizing the detected load current value, rectifying the input current on the indoor unit side with a rectifier circuit through a resistor, smoothing it with a smoothing capacitor and outputting it to the load side A circuit and an indoor control unit for driving the switching means and the switching means in parallel with the resistor are provided, and the switching means is opened when a load current value detected by the load current detection means exceeds a predetermined value. This reduces the reactive power generated in the resistor when the switching means is closed, and increases the current flow period by the time constant of the resistor and smoothing capacitor to improve the power factor and reduce the harmonic current. Suppression To it can be.

  The second invention uses a current transformer to accurately detect the load current value.

  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 is a circuit diagram showing a configuration of a control device according to the first embodiment of the present invention. In FIG. 1, the same components as those in FIG. The alternating current from the commercial AC power source 1 passes through the load current detection means 9 provided on the outdoor unit side, and is fully waved in the rectifier circuit 2, 2 ′ comprising a diode bridge through the resistors 6, 6 ′ on the indoor unit side. After being rectified, it is smoothed by the smoothing capacitors 3 and 3 'and supplied to the load 5 side. Further, opening / closing means 7, 7 'are provided in parallel with the resistors 6, 6', and indoor unit control units 8, 8 'for driving the opening / closing means 7, 7' are provided. The outdoor unit control unit 10 that recognizes the load current value is provided to the indoor unit control units 8 and 8 'to constantly transmit information.

  About the control apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  In the present invention, when the load current detected by the load current detecting means 9 exceeds a predetermined value (t1), the outdoor unit control unit 10 recognizes the load current value and transmits information to the indoor unit control units 8 and 8 '. Then, a control signal is output from the indoor unit control units 8 and 8 'to open / close the opening and closing means 7 and 7' so that the input current can be transmitted by the time constants of the resistors 6 and 6 'and the smoothing capacitors 3 and 3'. The current period can be increased to improve the power factor and suppress the harmonic current.

  For example, the power supply voltage of the AC power supply 1 in FIG. 1 is 230 V, the capacitance of the smoothing capacitors 3 and 3 ′ is 68 μF, and the resistance values of the resistors 6 and 6 ′ are 1Ω (opening and closing means 7 and 7 ′ Side), 15Ω (resistors 6, 6 ′ side), the ninth harmonic current becomes a graph as shown in FIG. 3 from experimental values. The ninth harmonic tends to amplify the harmonic current from an experimental value to a curve that is close to proportional with a peak in the vicinity of 7 to 8 A, and has the smallest margin with respect to the standard value. From FIG. 3, when the load current reaches a predetermined value (t1), the open / close means 7 and 7 ′ are opened, and the current is passed through the resistors 6 and 6 ′ (15Ω), so that the ninth harmonic current It can be seen that decreases. In addition, in the region below the predetermined value (t1) in FIG. 2, since the input current does not pass through the resistors 6 and 6 ′, there is no loss generated in the resistors 6 and 6 ′, and the reactive power can be reduced. It turns out that it becomes.

  As a method for detecting the load current, for example, a current transformer or the like is used to accurately transmit the current value of the load current to the outdoor side control unit 10 on the secondary side.

  As described above, since the control device according to the present invention can reduce the reactive power consumed by the resistor while suppressing the harmonic current, it can be applied to a fan that requires a small input current circuit.

Electrical circuit diagram in Embodiment 1 of the present invention The graph which shows the helpless power in Embodiment 1 of this invention The graph which shows the 9th harmonic current with respect to the load current and resistance value in Embodiment 1 of this invention Electrical circuit diagram in the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power source 2 (2 ') Rectifier circuit 3 (3') Smoothing capacitor 4 (4 ') Converter 5 (5') Load 6 (6 ') Resistor 7 (7') Opening and closing means 8 (8 ') Indoor unit Control unit 9 Load current detection means 10 Outdoor unit control unit 11 Outdoor control device

Claims (2)

In a multi-type air conditioner composed of a plurality of indoor units and outdoor units, a load current detection unit that detects an input current of the indoor unit on the outdoor unit side and a load current value detected by the load current detection unit An outdoor control unit for recognizing the input, a capacitor input type power supply circuit for rectifying the input current to the indoor unit side through a resistor through a rectifier circuit and then smoothing it with a smoothing capacitor and outputting it to the load side, and the resistor in parallel And an indoor controller for driving the opening / closing means, and the opening / closing means is opened when a load current value detected by the load current detecting means exceeds a predetermined value. Machine control device. 2. The control device for an air conditioner according to claim 1, wherein the load current detection means comprises a current transformer.

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