JP3649752B2 - Air conditioner - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an air conditioner that drives a compressor by an inverter device.
[0002]
[Prior art]
In a conventional air conditioner, for example, an indoor heat exchanger and an indoor fan are arranged indoors, and an outdoor heat exchanger, a compressor, and an outdoor fan are arranged outdoors.
[0003]
Generally, an inverter device of a conventional air conditioner is configured as shown in FIG. 6 as load reducing means. That is, the arithmetic / control circuit 5 that has received the command signal calculates an appropriate target output frequency, and drives the compressor 3 by the drive circuit 4 and the semiconductor switching element group 2.
[0004]
At this time, the arithmetic / control circuit 5 controls the output frequency of the drive circuit 4 based on the detected current signal Io from the current detector 6 that detects the inverter input current.
[0005]
An example of output frequency control is shown in FIG.
[0006]
In the calculation / control circuit 5, an output frequency stop current level It, an output frequency decrease current level Id, and an output frequency increase stop current level Is are set in advance, and compared with the detected current signal Io at any time during operation of the compressor. It is carried out.
[0007]
When the detected current signal Io is smaller than the output frequency rise stop current level Is (Io <Is), the compressor is operated at the target output frequency.
[0008]
When the detected current signal Io is smaller than the output frequency decreasing current level Id and the detected current signal Io is equal to or higher than the output frequency increasing stop current level Is (Id> Io ≧ Is), the frequency increase from the output frequency at that time is stopped. .
[0009]
When the detected current signal Io is smaller than the output frequency stop current level It and the detected current signal Io is equal to or higher than the output frequency falling current level Id (It> Io ≧ Id), the detected current signal Io is smaller than the output frequency falling current level Id. The output frequency is lowered until (Io <Id).
[0010]
When the detection current signal Io becomes equal to or higher than the output frequency stop current level It (It ≦ Io), the generation of the output frequency is stopped.
[0011]
As described above, by controlling the output frequency, for example, when the outside air temperature rises during cooling and the condensation pressure rises and the load increases, an overcurrent is prevented from flowing through the inverter device and the compressor. To do.
[0012]
[Problems to be solved by the invention]
However, in the above-described conventional technology, when the operation is started when the compressor is in the locked state, as shown in the curve L0, the inverter input current increases rapidly as the output frequency increases, as shown in FIG. The detection current signal Io increases rapidly. This locked state means a state in which the rotor inside the compressor is restricted and cannot rotate.
[0013]
In FIG. 8, when the detection current signal Io becomes It ≦ Io, the generation of the output frequency is stopped. However, the detection current signal Io has an output frequency decreasing current level Id, an output frequency before reaching the output frequency stop current level It. In order to achieve the rising stop current level Is, the output frequency is controlled to be stopped or increased.
[0014]
Therefore, although the compressor is not operating normally, the inverter device continues to output an output frequency at which the detected current signal Io satisfies Id> Io ≧ Is, and the drive current continues to flow through the compressor. There was a problem that the machine overheated abnormally.
[0015]
The present invention has been made in order to solve the above-mentioned problems, and at the time of starting the compressor, in order to detect the abnormality of the compressor quickly and to stop the operation, it is not limited to keep a wasteful current flowing. An object of the present invention is to provide an air conditioner that can prevent abnormal overheating of the compressor and prevent burning of the motor windings in the compressor and damage of other components.
[0016]
[Means for Solving the Problems]
Therefore, in the present invention, the generated stop current level of the output frequency, the falling current level lower than the generated stop current level, and the rising stop current level lower than the falling current level are set, and the inverter frequency is set according to the level of the inverter input current. In an air conditioner equipped with a compressor driven by an inverter device that stops generation, decreases output frequency, or stops increase in output frequency, when the compressor is started, the inverter output frequency An air conditioner characterized in that only the generation stop current level is valid.
[0017]
Further, in the present invention, preferably, the compressor is forcibly raised to a predetermined frequency when the compressor in the inverter device is started.
[0018]
At the time of starting the compressor, only the generation stop current level of the inverter output frequency is made effective and once raised to a predetermined frequency. Alternatively, at the time of starting the compressor, only the current level for stopping the generation of the inverter output frequency provided separately from the generation stop current level of the inverter output frequency is valid for a predetermined time.
[0019]
[Action]
In such an inverter device, it is possible to reliably detect an abnormality in the compressor at the time of starting, and to prevent the compressor from being overheated without continuing to use unnecessary current.
[0020]
【Example】
Hereinafter, preferred embodiments of the air conditioner of the present invention will be described in detail with reference to the accompanying drawings. However, Example 1 and Example 2 described below are preferably applied to the inverter device of FIG.
[0021]
Example 1
FIG. 1 shows the relationship between the output frequency and the detected current value in the preferred embodiment 1 of the air conditioner of the present invention (when the target output frequency is equal to or higher than the predetermined frequency Ft), and FIG. 2 shows the air conditioner of the present invention. The relationship between the output frequency and the detected current value in the preferred embodiment 1 (when the target output frequency is less than the predetermined frequency Ft) is shown.
[0022]
A first embodiment will be described with reference to FIGS. 1 and 4.
[0023]
In FIG. 4, when the operation is started (step S1) and the target output frequency ≧ the predetermined frequency Ft, the output frequency increases from the start of the compressor (step S2) until the output frequency reaches Ft. Only enables the generation stop current level It of the output frequency, and the detection current signal Io is only compared with the generation stop current level It (steps S3 and S4).
[0024]
That is, when the compressor is in the locked state, the inverter input current increases rapidly as the output frequency rises. Therefore, as shown by the curve L1 in FIG. 1, the detection is performed before the output frequency reaches the predetermined frequency Ft. The current signal Io reaches the output frequency generation stop current level It, stops generating the output frequency, and stops the compressor (steps S4 and S14).
[0025]
On the other hand, as shown by the curve L2 in FIG. 1, when the compressor is normal, the detected current signal Io is less than the generation stop current level It even when the output frequency reaches the predetermined frequency Ft (step S3). S5), the operation is continued, and after the output frequency reaches the predetermined frequency Ft, the comparison between the detection current signal Io and both the output frequency lowering current level Id and the output frequency rising stop current level Is is also started. (Steps S6 to S7), the output frequency is controlled so that no overcurrent flows (Steps S10, S11, S12). That is, when the target frequency matches the output frequency, the frequency is held (S8, S12), and when the target frequency does not match the output frequency, the frequency is increased or decreased (steps S9, S10, S11).
[0026]
Unlike FIG. 1, as shown in FIG. 2, when the target output frequency is smaller than the predetermined frequency Ft, the target output frequency is once raised to the predetermined frequency Ft when the compressor is started (steps S2 and S3). .
[0027]
Thus, until the target output frequency reaches the predetermined frequency Ft, only the generation stop current level It of the output frequency is made valid (step S3) and detected in the same manner as in the case of target output frequency ≧ predetermined frequency Ft in FIG. The current signal Io is only compared with the output frequency generation stop current level It (step S4).
[0028]
On the other hand, after the target output frequency reaches Ft in FIG. 2, as shown by the curve L4 in FIG. 2, both the detection current signal Io, the output frequency falling current level Id, and the output frequency rising stop current level Is are both. Is also started, and the output frequency is lowered to the target output frequency.
[0029]
Also in this case, when the compressor is in the locked state, before the output frequency reaches Ft, the detected current signal Io reaches the output frequency generation stop current level It as shown by the curve L3 in FIG. Frequency generation is stopped and the compressor is stopped (steps S4 and S14).
[0030]
Example 2
A second embodiment will be described with reference to FIGS. 3 and 5.
[0031]
Only the generation stop current level Itt of the second output frequency provided separately from the normal inverter output frequency generation stop current level Itt is valid for a certain time T (step P2) from the start of the compressor (step P1). The detected current signal Io is only compared with the generation stop current level Itt of the second output frequency (step P3).
[0032]
After a predetermined time T has elapsed from the start (step P2), the detection current signal Io, the normal inverter output frequency generation stop current level It, the output frequency fall current level Id, and the output frequency rise stop current level Is, (Steps P4, P5, P6), and the output frequency is controlled so that no overcurrent flows (steps P9, P10, P11).
[0033]
Also in this case, as indicated by a curve L5 in FIG. 3, when the compressor is in the locked state, the inverter input current increases rapidly as the output frequency rises, and before the predetermined time T elapses, the detected current signal Io reaches the second output frequency generation stop level Itt, stops generating the output frequency, and stops the compressor (steps P2, P3, and P13).
[0034]
As described above, in the embodiment of the present invention, the load reduction means is used, and the inverter device is configured to stop the generation of the inverter frequency, lower the output frequency, or stop the increase of the output frequency according to the level of the inverter input current. In the air conditioner equipped with the compressor driven by the above, only the generation stop current level of the inverter output frequency is valid when the compressor is started. At the start of the compressor in this inverter device, it is forcibly increased to a predetermined frequency. Alternatively, at the time of starting the compressor, only the generation stop current level of the inverter output frequency provided separately from the current level is valid for a predetermined time.
As described above, according to the present invention, at the time of starting the compressor, in order to quickly detect the abnormality of the compressor and stop the operation, not only the useless current is allowed to flow, Abnormal overheating can be prevented, and burning of the motor windings in the compressor and other parts can be prevented.
[0035]
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between an output frequency and a detected current value in a preferred embodiment 1 of an air conditioner of the present invention (when a target output frequency is equal to or higher than a predetermined frequency Ft).
FIG. 2 is a diagram showing the relationship between the output frequency and the detected current value (when the target output frequency is less than a predetermined frequency Ft) in the preferred embodiment 1 of the air conditioner of the present invention.
FIG. 3 is a diagram showing a relationship between an output frequency and a detected current value in a preferred embodiment 2 of the air conditioner of the present invention.
FIG. 4 is a flowchart showing Example 1;
FIG. 5 is a flowchart showing a second embodiment.
FIG. 6 is a diagram showing a configuration of a general inverter device.
FIG. 7 is a diagram showing an output frequency and a detected current value in a conventional air conditioner.
FIG. 8 shows a conventional output frequency and detected current value when the compressor is in a locked state.
[Explanation of symbols]
3 Compressor 6 Current detector Itt Generation stop current level of second output frequency Ft Predetermined frequency Io Detection current signal Id Output frequency decrease current level Is Output frequency increase stop current level

Claims (2)

The generation stop current level of the output frequency, the falling current level lower than this generation stop current level, and the rising stop current level lower than this decrease current level are set. In an air conditioner equipped with a compressor driven by an inverter device that is adapted to lower the frequency or stop raising the output frequency,
An air conditioner characterized in that only the generation / stop current level of the inverter output frequency is valid when starting the compressor.   The air conditioner according to claim 1, wherein the air conditioner is forcibly raised to a predetermined frequency when the compressor in the inverter device is started.

Images