JPS5818046A - Current controlling method for air conditioner - Google Patents

Abstract

PURPOSE:To enable to operate an air conditioner by connecting the same directly to the domestic power source, by detecting the operating current of the air conditioner, and lowering the frequency of current supplied to the compressor when the operating current exceeds a prescribed value, thus controlling the operating current not to exceed the maximum value of a tolerable range. CONSTITUTION:A compressor 12 of an air conditioner is supplied with driving force from an electric power source 13 and produces a frequency instruction signal corresponding to the room temperature detected by a room temperature detecting means 14. The room temperature is controlled by controlling the speed of rotation of the compressor by applying the frequency instruction signal produced by the compressor 12 to a frequency varying means 15 and thereby varying the frequency of current supplied to the compressor 12. Here, in order to prevent increasing of the operating current to a level higher than the rated power source current along with increasing of load, the speed of rotation of the compressor 12 is lowered by detecting the power source current of the means 15, producing a frequency reducing signal from a current detecting means 16 when the power source current of the means 15 has exceeded a prescribed value, and applying the frequency reducing signal to the means 15.

Description

[Detailed description of the invention]

The present invention relates to a current control method for air conditioning equipment, and more particularly to a current control method for air conditioning equipment that controls the operating current of the air conditioning equipment so as not to exceed a maximum allowable range. BACKGROUND ART Conventionally, as a circuit configuration of an air conditioner, there is a circuit configuration as shown in FIG. 1, for example. As shown in this figure, when the air conditioning equipment is of the split type, the evaporator (not shown) and the internal blower l are placed indoors A, the condenser (not shown), the compressor fR2 and the A blower 8 and the like are installed outside B, respectively. In addition, in the diagram @1, 4 is the air conditioning/heating selector switch S.
Four-way valve for switching heating and cooling refrigerant that operates, 6 is installed in the condenser is 9 #! The compression pressure detector opens and closes a switch 6 connected in series to an outdoor blower 8. Further, swl is a switch for the indoor blower, and swe is an operation switch. This type of current control method for air conditioning equipment is such that when the operating current of the air conditioning equipment, which is quick to increase the load, and the condensation pressure detected by the condensation pressure detector 6 installed in the condenser exceed respective predetermined values, condensation occurs. The outdoor blower 8 is stopped by opening a switch 6 connected to the pressure detector 5 to reduce the load and control the operating current so that it does not exceed the maximum allowable range. However, in the above-mentioned empty Wi4 unit, since the condenser and the like are installed outside B, it is affected by the outdoor temperature, etc., and has a negative vif.
The movement is large, especially as shown in Fig. 1. Linear pressure Pc
The operating current I of the air conditioning equipment gradually increases in proportion to the increase in the current value, and may exceed the maximum allowable current value of the air conditioning equipment determined by the rated current of the power cord, plug, etc.
Make sure you have enough power capacity for the plugs. Therefore, if the maximum allowable current value Imal is set to t5m, for example, even if a marketable one such as a 15A outlet is sufficient for normal loads, 20
I am using an A type outlet etc. Most homes are electrically wired with a current capacity of 15A or less, so when installing a 20A air conditioner that uses the current control method described above, it is necessary to install dedicated wiring for the air conditioner. , could not escape the disadvantages and inconveniences. The present invention was made in view of the drawbacks of the prior art as described above, and by limiting the maximum value of the operating current of the air conditioner to a predetermined value, for example, 15 μm, it is possible to It is an object of the present invention to provide a current control method for air conditioning equipment that can be directly connected to the wiring on the 6Ill side of the 15-meter power supply. To achieve this objective, the present invention detects the operating current of the air conditioner, and when the operating current exceeds a predetermined value due to load fluctuations, the current applied to the compressor is adjusted according to the excess current. The frequency is lowered and the rotational speed of the upper compressor is gradually reduced to control the operating current so that it is within the maximum allowable range. Hereinafter, the present invention will be described in detail based on the accompanying drawings. FIG. 8 is a diagram showing the principle of a current control method according to an embodiment of the present invention. The empty TSM device that is the target of this current control method includes, for example, a compressor 12 that compresses and circulates refrigerant into a condenser and an evaporator, and the evaporator is installed indoors and the condenser is installed outdoors. , applied to split-type air conditioning equipment, etc. Here, the compressor 12 includes an electric motor whose speed is controlled by frequency, for example, an induction motor, and the power source 1
3 and is driven. In such air conditioning equipment, the room temperature for guests is adjusted by adjusting the frequency of the power supply applied to the compressor 12 and controlling the rotation speed of the compressor 12. This adjustment of the indoor temperature can be carried out by, for example, detecting the indoor temperature using the temperature detection device 14 and generating a frequency command signal according to the detected temperature.
In addition, the frequency variable device 15 adjusts the frequency of the current applied to the compressor 12 to control the rotation speed of the compressor 12 and adjust the indoor temperature. Such a control method is effective when the outside air temperature is low and the internal temperature is also low.
Even if the air conditioner is operated at high speed, the load is light, so the operating current of the air conditioner is low, so there is no problem. However, if the outside temperature rises significantly during cooling, for example, the condensing pressure increases, and the As shown in Figure 4, the operation [4 hours] also increases and exceeds the current rating (for example, t5m) of the power plug mentioned above. In order to deal with this, the current of the power supply of the frequency/double variable device 15 is detected, and this current is set to a predetermined value (for example, 14
A) When a command signal is applied to the full-circle Hansuncho variable device 15, which reduces the frequency according to the excess current,
In this frequency circuit, the maximum value of the frequency output from the i15 is limited, and the rotation speed of the compressor 12 is gradually reduced to control the operating current so that it does not exceed the maximum allowable range (for example, 15 A). Ru. This current control is performed by, for example, detecting the current of the power source of the frequency variable device 15 using a current detection device 616, and when this current exceeds a predetermined value, the frequency is decreased according to the current. A command signal is applied to the frequency change device 15, and the rotational speed of the engine 12 is decreased through the frequency change device 15. Therefore, according to this control method, the current is continuously limited, so that the current can be controlled within the rated current while maintaining the capacity of the air conditioner. Furthermore, with heat pump type air vents, a larger condensing pressure is required for heating than for cooling, and the maximum allowable current may exceed 1 [(for example, 15 μm), so it is not recommended to install the outlet at a distance of 15 μm. However, if the above-mentioned current control method is adopted, +41i exposure can be achieved. Figure @6 is an explanatory diagram that further embodies the current control method. Now, if the operating current changes parabolically with respect to time as shown in Figure 6 (virtual curve) due to load fluctuations, the current control zone is divided into multiple aK according to the current value.For example, If the maximum allowable current value is 15 µm, the high zone exceeding 15 µm is the A zone, if the control range is to be kept within IA, the zone between t5A and 14 µm is the B zone, and the low zone below 14 µm is the t- It is divided into 8 zones called 0 zones. Here, when the operating electrician enters the A zone without increasing the load, the current detection wave 1

[
6 detects the excess current, and the frequency frequency device +5i
The frequency of the first stream to be applied to the subtraction machine 12 for a predetermined period of time, e.g. every second, is transmitted through a predetermined frequency, for example,
Lower 5 decoys at a time. When the operating electrician is in zone B,
However, when the operating current drops to zone C due to a decrease in the load, the @distribution current detection device [6] detects the shortage of current, and the current is detected via the frequency variable device 15. , the frequency of the current applied to the compressor 12 is increased by a predetermined value, e.g., 5 increments, every predetermined period of time, e.g., every 30 seconds, until it reaches the frequency instructed by the pond control device, e.g., the temperature detection device 14. , through the frequency variable device t5. With this kind of control,
As shown in Figure 6, the operating current is 1
The operating current X does not change between 4A and t5A.
is less than t5A, and the current can be controlled within the rated current while maintaining the capacity of the air conditioner. In FIG. 6, when the operating current is in the process of rising due to an increase in load, when the current value I enters the mu zone, it is lowered by a predetermined frequency (for example, 10 s/s).
If the operating current is in the process of dropping quickly as the load decreases, the lowered frequency remains as the current value moves from the M zone to the B zone, and when the current value decreases to the C zone, the frequency increases. By increasing the value to its original value, the same effect as described above can be expected. Furthermore, the current value I is A
When entering the zone, if the frequency is lowered by a predetermined number with a hysteresis characteristic, and when the current value drops to the 0 zone, the frequency a is increased to its original value with a hysteresis characteristic. , and chattering in the boundary area between zone B and zone C, and smooth current control is possible. @Figure 7 is a circuit diagram for implementing the current control method for the air conditioner. In this figure, the same parts as those used in FIG. 1 showing the conventional example are represented using the same symbols. In this figure, the frequency variable device ts is connected to a power plug 17 via an operation switch svr, and supplies a drive current to the compressor 12. This frequency variable device 15
For example, consists of a full-wave rectifier and an innocent,
After converting the commercial power supply to direct current, a square wave of a constant frequency is output and applied to the compressor 12. The temperature detection device fli14, which adds the indoor temperature control signal to the frequency variable device t5, has operation switches sw and 1r.
It is connected to the power plug 17 via the power supply plug 17 . This temperature detection device 14 detects the room temperature, applies a frequency command signal corresponding to the temperature to the frequency variable device t5, and controls the rotation speed of the compressor 12 via the frequency variable device 15. Therefore, when the air conditioner is under light load, that is, during normal operation,
The rotation speed of the compressor 12 will be controlled by the temperature detection device 14. On the other hand, the frequency variable device 15 is provided with the current detection device fltI6, which applies a frequency command signal for current control. This current detection device 16
consists of a current transformer [6.1] that detects the current applied to the frequency variable device 15, and a frequency control device 16.2 that generates a frequency command signal according to this detected current. , the compressor 12 via the frequency variable device 15
0 rotation speed at-control. Therefore, with such a current control circuit, not only can the same effects as the above-mentioned current control method be easily achieved, but also the maximum allowable current value at the time of overload can be reliably maintained within, for example, 15 μm. Since it can be held down, the current rating margin of the inverter provided in the frequency variable device 15 can be lowered, and the device itself becomes economical. Since the present invention is configured as described above, the current is continuously limited when the air conditioner is overloaded, and the current can be controlled within the rated current, for example, 15 μm, while maintaining the capacity of the air conditioner. Therefore, the marketability of power plugs etc. is 6 t5.
It has the effect of making it more flexible. WII-Explanation of the Drawings The diagram is a circuit diagram of a conventional air conditioner, FIG. 2 is a diagram showing changes in current with respect to condensing pressure, and FIG. 8 is a diagram for explaining a current control method according to an embodiment of the present invention. The principle diagram, FIG. 4, shows the condensation pressure and electric current tILrI1. as a function of time. Shape, 2nd
Figures 1 and 2 are diagrams of current waveforms varying over time, and Figure 7 is a circuit diagram of an air conditioner for implementing the current control method. 2.12...Compressor, 14...Temperature detection device, 15
... Frequency variable device, [6... Current detection device. Applicant's agent Tomo Seikatsu 1 Haruka 2 Suspicion of Closed Case (Pc) - 3rd Prisoner 4 Prisoner's Time

Claims (1)

[Claims]! , the operating current of the air conditioning equipment is detected, and when the operating current exceeds a predetermined value due to load fluctuations, the excess current RKG lowers the frequency of the current applied to the compressor, and reduces the rotation speed of the compressor. A current control method for air conditioning equipment that gradually reduces the operating current so that it does not exceed the maximum allowable range. 2. In the current control method according to claim 1, the current control zone is divided into a plurality of zones according to the current value during operation of the air conditioner, and in the zone where the current value during operation is high due to an increase in load, An air conditioner that reduces the frequency of the current applied to the compressor by a predetermined value at predetermined intervals, does not change the frequency in zones where the current value is intermediate, and increases the frequency to the original value in zones where the current value is low. current control method. 8. In the current control method according to claim 2, when the current value during operation is in the process of rising by half due to an increase in load, a hysteresis characteristic is provided when the current value enters the high zone. If the frequency is lowered by a predetermined number and the current value during operation is in a downward trend that is rapid due to load reduction, the frequency remains at the lower frequency when the current value moves from the high zone to the intermediate zone. A current control method for air conditioning equipment in which the frequency is raised to its original value by providing hysteresis characteristics when the current drops to the low zone.