JPH04139342A - Control method for air-conditioner - Google Patents

Abstract

PURPOSE:To improve follow-up and stability of current control by a method wherein a reduction value of an operation frequency responding to a change amount of a detecting input current is obtained, and when a detecting current exceeds an operation value of current control, the operation frequency of a compressor is reduced by a given value at every given time until the operation frequency is reduced to a reduction value. CONSTITUTION:By means of a signal for an input current detected by a current detecting device 5, detecting values before and after a lapse of a given time TM1 (one second) are temporarily stored in resistors I1 and I2. When the input current of an air-conditioner is steeply increased and the input current is increased to a value higher than an operation value, a change amount (DELTAI/DELTAt) of the input current is calculated from detecting current values before after a lapse of the given time TM1 (one second), and a given value f1 being a reduction value of an operation frequency responding to a calculating change amount and a given time TM2 responding to the given value f1 are obtained. When an change amount of the input current is high, the reduction value f1 of the operation frequency is increased, a given time is decreased, and a reduction amount of an operation frequency per a unit time is increased to a value higher than 1Hz per one second. This method extremely rapidly reduces the input current and shortens a time in which a current higher than an operation value flows.

Description

Detailed Description of the Invention "Field of Industrial Application" This invention is an air conditioner control method that detects an input current and controls the current so that the detected 1tfX value does not exceed the maximum allowable range of the rated power supply. More specifically, the present invention relates to a control method for an air conditioner that improves followability and stability of current control and improves air conditioning ability.

"Prior Art" Conventionally, in the control method of this type of air conditioner, in order to prevent the input current from the commercial power supply (for example, 100V, 50/607) from exceeding the rated current (for example, 15A), the input current is When the current is detected and the detected current exceeds the current control operating value (for example, 14A), the operating frequency of the compressor is decreased by a predetermined value (for example, 1 cycle) every predetermined time (for example, 1 second). Returned to operating value! ! , f, current control is performed to maintain the operating frequency.

In addition, when the detected current becomes less than the release value (for example, 13Δ), the current control is divided by V, and the first netting machine is returned to normal operation (
7. Ensure that the input battery does not exceed its rating. That is,
Most general household electrical wiring has a usage rating of 15A or less, and air conditioners have a large input current compared to other home appliances.For example, when the outside temperature is very high during cooling, or when heating This is because a large current flows during high loads such as when the outside temperature is very low.To explain in detail the control method of the air conditioner mentioned above with reference to Figures 4 and 5, if the air conditioner is shut down due to some reason. Assuming that the input terminal due to the source rises t2 and exceeds the operating value (for example, 14 A) (as shown at time 1 or 14 in Fig. 4), the current control proceeds from STi to Sr2 in Fig. 5 and activates the current control. . Then, the operating frequency of the compressor is lowered by a predetermined value (for example, 1H2) to prevent the current from increasing.Next, at ST, 3 in Fig. 5, a predetermined time (for example, 1 second) has elapsed. After that, it loops to STI.Thereafter, the tests from STI to Sr1 are repeated until the detected current becomes below the operating value. It will be lowered step by step.
When the detected current becomes 1 J below the operating value when the toothpick shown at point 1 in FIG. If under control, the process proceeds to Sr5, where it is determined whether the detected current is equal to or less than the release value, and if it is greater than the release value, the process proceeds to ST6. 1-2, the operating frequency of the compressor is 5
The frequency is maintained at a lower frequency of 7 Hz. Thereafter, as shown at time 13 in the figure, when the detected current becomes equal to or less than the release value (for example, 13A), Sr5 to Sr in FIG.
1, the current control is canceled, and the compressor is operated normally, that is, at the target operating frequency. By the way, when the detected current returns to the operating value (at time t7 shown in FIG. 4)
Although the flow control described above may be canceled, hysteresis of IA is provided between the operating value and the canceling value to prevent hunting.

In this way, the input terminal is lowered as the operating frequency of the compressor decreases. When the detected current becomes less than the release value (as shown in the fourth t), -
4B is lifted, [Problems to be solved by the invention 1 to 1] In the second paragraph, in the above air conditioner control method, the fourth problem is solved.
As shown from time t1 to time t14 in the figure, when the change in the input current is slow, the detected current exceeds the operating value, and when the multi-distribution current control is activated, the input current immediately drops. , input current is permissible (e.g. 15A)
No clutter.

However, as shown in Figure 4 from point 19 to point 1, the above input i! 'If the change in coolness is steep, not only will it take time (5 seconds in this case) for the input current to return to the operating value, but it will also take longer than the allowable value (rated current 15A), as shown by arrow a in the figure. ) was sometimes exceeded. Therefore, because the peak current is large, the operating value may have to be set considerably lower than the allowable value in order to prevent the input terminal from exceeding the allowable value at its peak. Change the machine. In some cases, the wiring capacity could not be used to its full potential, and the capacity could not be fully utilized.

This invention was made in view of the above problems, and its purpose is to improve followability and stability of current control that controls input current, and to improve air conditioning performance. An object of the present invention is to provide a method for controlling an air conditioner as described above.

[Means for Solving the Problems] In order to achieve the above object, the present invention detects the input current when controlling the inverter of the compressor, and when the detected current exceeds the operating value of the current control, the present invention detects the input current. activating current control to lower the operating frequency of the compressor by a predetermined value, and
In an air conditioner control method that releases current control when the detected current value becomes less than the current control release value,
Calculate the amount of change in the detected input current, obtain a reduction value of the operating frequency corresponding to the calculated amount of change, obtain a predetermined time corresponding to this reduction value, and make the detected current exceed the operating value. The gist of the present invention is to lower the operating frequency by a predetermined value less than or equal to the lower value at predetermined intervals until the lower value is reached.

"Effect" Since the above method is used, the change in the input current is calculated based on the detected current before and after a predetermined time, and the operating frequency is calculated according to the change and the operating frequency is calculated according to the change. A predetermined value may be changed for a predetermined time, depending on the case. Also,
When the detection input current exceeds the current control operating value,
The operating frequency of the compressor is lowered by a predetermined value at each predetermined time period until it reaches a lower value. In other words, if the change in the input current is steep, the operating frequency can be greatly reduced in a short period of time by increasing the reduction value and decreasing the predetermined time, or in some cases by increasing the predetermined value. , the input current can be lowered quickly.

Embodiment J An embodiment of the present invention will be explained below based on FIGS. 1 to 3. In FIG. 1, the air conditioner is connected to a commercial power source (A
ClooV; 50/60H2) AC/DC converter circuit 2 consists of a diode bridge, capacitors, etc. that rectifies the AC voltage of 1 to voltage doubler (approximately 280V), and switches this DC voltage to variable frequency three-phase AC using PWM. A frequency conversion circuit (inverter device) 3 that converts the frequency, a compressor motor 4 that is driven by the converted variable frequency three-phase AC, a current transformer (CT) and current conversion circuit that detects the input current from the commercial power source 1, etc. A current detection circuit 5 consisting of a current detection circuit 5, an indoor temperature detection device 6 consisting of a thermistor etc. that detects the indoor temperature, and an indoor temperature detection device 6 consisting of a thermistor etc. that detects the indoor temperature, and the indoor temperature and the indoor temperature set value (set by a remote control etc.) to operate the compressor at a target operation. A control device (microcomputer) 7 is provided which outputs a switching signal as a frequency and controls the current by varying the operating frequency of the compressor based on the detected current. 7 is equipped with a storage section (for example, registers 1 and rz) that temporarily stores the input current before and after a certain predetermined time, and the change in input current (ΔI/Δt) is calculated based on the contents of registers 3 and I2. ), reads out from the table a reduction value f1 of the operating frequency corresponding to this calculated change, and reads out a predetermined time corresponding to this reduction (+i f I) from the table. The decrease value f,
The predetermined time may be obtained by using the calculated change as a coefficient and multiplying this coefficient by a constant value. Further, when the predetermined value f2 is determined according to the decrease value fI, the predetermined value ft corresponding to the decrease value f1 is read from the table. Note that this process is not necessary when the predetermined value f2 is always constant.

Next, the operation of the control method applied to the air conditioner having the above configuration will be explained with reference to the flowchart of FIG. 2 and the time chart of FIG. 3.

First, it is assumed that the target operating frequency of the compressor is determined based on the indoor temperature setting value, the indoor temperature, etc., and the compressor motor 4 is driven at this target operating frequency. Then, based on the signal of the input current detected by the current detection device 5, the detected current value is temporarily stored in the register I in the control device 7 (ST1).
seconds) have elapsed (ST2), the contents of register I2 are transferred to register 1 (ST3). Next, the detected current value is temporarily stored in register 2 (ST4), that is, the detected current values before and after a predetermined time TMI (1 second) are temporarily stored in registers 1 and 12, respectively. Note that in ST2, the predetermined time T
If MI (1 second) has not elapsed, steps ST3 and ST4 are not performed, and then the detection is performed until the flow value is the operating value (for example, 1
4A) Determine whether or not the above is reached (ST5)
. For some reason, the input current of the air conditioner suddenly increases, and as shown at time t1 in Figure 3,
Assuming that the input terminal exceeds the operating value, ST
Proceed to step 6. Here, in ST3 and ST4, register 11 and T
The change in input current (ΔI/Δt) is calculated from the detected current values before and after the predetermined time TMI (1 second) temporarily stored in step 2 (ST6), and is the reduction value of the operating frequency according to this calculated change. A predetermined value r+ (for example, 5 Hz) and a predetermined time TM2 (for example, 0.2 seconds) corresponding to this predetermined value f are obtained (ST7). Next, the current control is activated and the current operating frequency of the compressor is set to a predetermined value [! (for example, IO7) (Sr1).

Next, when the predetermined time TM2 (0.2 seconds) obtained in Sr1 has passed (Sr1), it is determined whether the total of the reduced operating frequencies has reached the predetermined value f obtained in Sr1. If the predetermined value f1 is not reached, 5 TIO processing is performed starting from Sr1 until the predetermined value fI is reached. In other words, 0.
The operating frequency decreases by 117 every 2 seconds until the total decreases to 5Hz, and 1 second after the current control is activated? This 51 (
z decreases. That is, the processing from Sr1 to 5TIO is executed in a slow manner. When the total decrease reaches the predetermined Mr, 5TI
The process from ST2 to ST2 is repeated until the detected current becomes smaller than the operating value.

When the amount of change in the input terminal is large in this way, the operating frequency reduction factor f1 should be increased, the predetermined time should be made smaller, and the amount of reduction in the operating frequency per unit time should be made larger than the conventional one per second. This allows the input terminal to drop extremely quickly, the peak is small, and the allowable value is never exceeded, and the time it takes to return to the operating value, that is, the time for the current above the operating value to cool down, can be shortened. . That is,
The followability and stability of current control at the input terminal are better than in the past.

Subsequently, when the input current returns to the operating value as shown at time t□ in FIG. 3, the process proceeds from Sr1 to 5TII, and it is determined whether the current control is in operation or not. In this case, since the current control is in operation, the process proceeds to ST12, where it is determined whether the detected input current is below the release value (for example, 13A), and if it is not below the release value, the process proceeds to 5T13, where the compressor is activated. The operating frequency is fixed. Thereafter, the process from Sr1 to S T 13F7) is repeatedly executed until the detected current becomes equal to or less than the release value (time t11 in FIG. 3).

Subsequently, as shown at time t□ in Figure 3, the input current gradually decreases, and when the input current becomes less than the release value, the process advances from 5T12 to 5T14, the current control is released, and the voltage is reduced. *ti is returned to normal operation.

On the other hand, as shown in Figure 3 from time 1 to time t41, does the input current exceed the operating value? Until this happens, if the change in the input terminal is small, in ST7 above, -1 is set to a predetermined value (t!f, (for example, I Hz), which is the reduction value of the operating frequency corresponding to the change), and this A predetermined time TM2 (for example, 1 second) corresponding to a predetermined (direction 1) is obtained. Therefore, Sr1 lowers the operating frequency by a predetermined value f, (constant value 1) 12), and Sr1 reduces the operating frequency for a predetermined time TM2 (1 second).
After 5 TIQ (seconds) has elapsed, the total decreased frequency becomes - the predetermined value f, and the ST2 Herbel occurs. Therefore, as shown at time ts+ in FIG. 3, the input current is immediately returned to the operating value as in the conventional case. At this time, since the change in the input current is small, by lowering IO2 in 1 second, the peak value of the input current or the time during which the current exceeds the operating value does not become a problem.
The input current can be reliably reduced with very stable changes.

FIG. 6 shows a coachyard diagram of another embodiment.

This example is based on Sr1 of the embodiment shown in FIG. The process of Sr1, that is, the process of calculating the current change amount (Δ■/Δt) and obtaining a predetermined value f corresponding to this and a predetermined time TM2 corresponding to this predetermined value fl is performed by Sr4 and ST5. . In other words, Sr.
The detected current before and after the predetermined time TMI of 1 is stored every predetermined time TMI (for example, 1 second) at 1, but at this time, the current change is calculated and the predetermined value f1 and predetermined time TM2 are calculated accordingly. This is an example of obtaining. Further, in this example, the predetermined value f8 is not a constant value but is variable, and is obtained according to the predetermined value f1 at Sr1, similarly to the predetermined time TM2. For example, a predetermined value (art is 1
0h is obtained, and from this, 0.2 seconds may be obtained as the predetermined time TM2, and 21 seconds may be obtained as the predetermined value f2.

In this way, the amount of change in the input current is calculated, a reduction value f1 of the operating frequency corresponding to the calculated amount of change is obtained, a predetermined time TM2 corresponding to this reduction value r1 is obtained, and depending on the case, the reduction value f, When a predetermined value f2 corresponding to is obtained and the input current exceeds the operating value, the current operating frequency of the compressor is decreased by a predetermined value f2 every predetermined time TM2 until the total decrease reaches the decrease value f1. Therefore, when the change in the input current is steep, the reduction value r is increased (and the predetermined time is decreased, and in some cases, the predetermined value f2 is also increased ((f1≧fz)). By increasing the amount of reduction in the operating frequency per unit time, the operating frequency can be lowered in a short time, and the input terminal will drop immediately, so the peak value will also be smaller, and unlike conventional methods, the input current will greatly exceed the operating value, and in some cases does not reach the allowable value, and the time required to return to the operating value can be shortened.

In addition, since the input current is immediately lowered to the operating value and kept below the allowable value, in other words, the peak value of the input current is small, so the operating value is set higher than before (for example, 14
．． 5A), and the capacity of the outlet can be used more fully than before, making it possible to further improve the performance of the air conditioner.

"Effect" As explained above, according to the air conditioner control method of the present invention, the detected input current change (ΔI/Δt)
is calculated, a reduction value of the operating frequency corresponding to the calculated change is obtained, a predetermined value corresponding to this reduction value is obtained, and in some cases, a predetermined time corresponding to this reduction value is obtained. In other words, when the change is large, a large decrease value and a small predetermined time, and in some cases a large predetermined value, are obtained; when the change is small, a small decrease value and a large predetermined time, and in some cases a small predetermined value are obtained. When the detected current exceeds the operating value of current control, the operating frequency of the compressor is lowered by a predetermined value at each predetermined time until the total decrease reaches the lower value. Since the amount of reduction in the operating frequency per unit time can be varied according to the amount of change, the input current immediately returns to the operating value, the peak current value becomes smaller, and the time during which the current flows above the operating value becomes shorter. In other words, it is possible to improve the followability and stability of the current control, and also to set the operating value to a high value, thereby improving the performance of the air conditioner.

Furthermore, when lowering the operating frequency, since the operating frequency is lowered in predetermined time increments until the total decrease reaches the lower value, there is no problem such as vibration of the pressure ms.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the air conditioner control method according to the present invention, FIG. 2 is a flowchart for explaining the operation, FIG. 3 is a time chart for explaining the operation, and FIG. FIG. 4 is a time chart for explaining the operation of the conventional air conditioner control method, FIG. 5 is a flowchart for explaining the operation, and FIG. It is a flowchart figure for demonstrating an effect|action. In the figure, 1 is a commercial power supply, 2 is an AC/DC conversion circuit, 3 is a frequency variable device (inverter section), 4 is a compressor-like motor,
5 is a current detection device, 6 is an indoor temperature detection device, and 7 is a control device (microcomputer). Patent applicant: Fujitsu General Ltd. Figure 3 Figure 4

Claims (3)

[Claims] (1) When controlling the compressor with an inverter, the input current is detected, and when the detected current value exceeds the operating value of the current control, the current control is activated and the operating frequency of the compressor is reduced by a predetermined value. In the control method for an air conditioner that releases the current control when the detected current value becomes equal to or less than the release value of the current control, the amount of change in the detected input current is calculated, and the calculated amount of change is calculated. When the detected current exceeds the operating value of the current control after obtaining a reduction value of the operating frequency according to the reduction value and obtaining a predetermined time corresponding to the reduction value, the operating frequency is reduced to the reduction value every predetermined time. A method for controlling an air conditioner, characterized in that the air conditioner is decreased by the following predetermined values until the total decrease reaches the decrease value. (2) The method for controlling an air conditioner according to claim (1), wherein the larger the calculated change, the larger the reduction value and the smaller the predetermined time. (3) The method for controlling an air conditioner according to claim 1, wherein the predetermined value below the reduction value is a predetermined constant value or a variable value determined according to the reduction value.