JPH06233589A - Revolution control system of air conditioner - Google Patents

Abstract

PURPOSE:To prevent an excessive temperature rise of a compressor or an electronic part and increase the capacity of air conditioning by detecting the temperature of a protected part, and changing the level of overload limit. CONSTITUTION:This is so made as to operate an overload limit function by attaching a means 7 for detecting the temperature of an electronic circuit part to an inverter controller 6, and detecting the temperature rise of the electronic part. Hereby, the faults by the property deterioration or thermal breakage of an electronic part is reduced, and also by the increase of operation range, the improvement of overload resistance and the improvement of air conditioning capacity are materialized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed control type air conditioner, and more particularly to preventing an excessive temperature rise of a compressor and electronic circuit parts during an overload operation state, and otherwise. The present invention relates to a rotation speed control type air conditioner suitable for fully exhibiting cooling and heating capacity.

[0002]

2. Description of the Related Art Conventionally, an overload limiting function in a rotation speed control type air conditioner is described in JP-B-60-16199. That is, an inverter control method is disclosed in which a target value of the voltage or frequency of the inverter is determined by using a current detector that detects the output current of the DC power supply and a pulse width modulation signal.

[0003]

In the above prior art, since the overload limit level is set under the operating condition where the temperature rise of the protected parts is maximum, the overload limiting function operates under normal operating conditions. There is a drawback that it is easy to do, and there is a problem that the driving ability is not fully exhibited. The present invention has been made in order to solve the above-mentioned problems of the prior art, and protects circuit components during an overload by detecting the temperature rise of protected components and changing the overload limit level. Under normal operating conditions, it is an object of the present invention to provide a rotation speed control type air conditioner which can prevent unnecessary operation of the overload limiting function and can sufficiently exert cooling and heating capacity.

[0004]

In order to achieve the above object, the structure of a rotation speed control type air conditioner according to the present invention is such that the rotation speed of a compressor is variable by an inverter and an overload limiting circuit is provided. In a rotation speed control type air conditioner that reduces the rotation speed of the compressor when the input current of the compressor exceeds the limit value, the temperature during overload operation is allowed in the circuit components that make up the inverter. Provide temperature detection means for parts that have no allowance for temperature so that the overload limit level can be lowered when it is likely to exceed the allowable temperature and can be changed high when there is enough allowance for the allowable temperature. The control circuit is configured.

[0005]

In general, the overload limit level is set so that the temperature of the circuit components during the overload operation does not exceed the allowable temperature. Therefore, if the temperature of the circuit component detected by the temperature detecting means provided in the circuit component has a sufficient margin with respect to the allowable temperature, the overload limit level is changed to a higher value. On the contrary, when the operating state changes from the normal operating state to the overload state and the temperature rise of the circuit components has no margin with respect to the allowable temperature, the overload limit level is changed to a low level.

Therefore, according to the rotation speed control type air conditioner of the present invention, it is possible to protect against the temperature rise of the circuit parts during the overload operation, the operation range is widened during the normal operation, and the cooling and heating capacity is improved. Can be realized.

[0007]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of a rotation speed control type air conditioner according to an embodiment of the present invention, and FIG. 2 is a derating of temperature and overload limit level of electronic circuit parts according to an embodiment of the invention. 4 is a diagram showing the relationship between the number of revolutions of the compressor motor and the overload limit level, and FIG. 4 is a flowchart showing the operation of the present invention.

In FIG. 1, 1 is a DC power source, 2 is a DC voltage detecting means, 3 is a DC current detecting means, 4 is an inverter drive section, 5 is a compressor motor, 6 is an inverter control section, and 7 is an electronic circuit component. It is a temperature detecting means.

FIG. 2 shows the temperature T of the electronic circuit component on the horizontal axis and the direct current Idc on the vertical axis, and shows the relationship between the temperature of the electronic circuit component and the derating of the overload limit level.

In FIG. 3, the horizontal axis represents the rotation speed N of the compressor motor,
The vertical axis represents the DC current Idc, and the overload limit level for each rotation speed is shown. Among these, the external determination value limits the input current of the entire air conditioner and is constant because it is determined by the capacity of the breaker. Also, the internal judgment value is, when the load of the air conditioner increases and becomes overloaded,
Compressor motor 5 to protect the compressor and electronic circuit components
For reducing the load by lowering the number of rotations of the power supply, and the limit level changes under the influence of the DC power supply voltage Vdc. That is, when Vdc increases from the state of b shown in the figure, the direct current decreases and the limit level changes in the direction of C, and conversely, when Vdc decreases, the direct current increases and the limit level changes in the direction of a. To do.

Next, the operation of the control circuit will be described.

Normally, the internal judgment value of the overload limit level changes under the influence of the DC power supply voltage Vdc. Therefore,
When the DC power supply voltage is extremely reduced and the overload operation is continued without considering the temperature detection means 7 of the electronic circuit component, the DC current Idc is rapidly increased, so that the temperature of the electronic circuit component is significantly increased. As a result, the service life of the parts is shortened, or in the worst case, the parts are destroyed by heat and cause a failure. For this reason, in actual products, the overload limit level is set to a level at which there is no problem even under the above-mentioned worst conditions, and as a result, the overload limit function is set during normal operation. It becomes easy to operate, and once it operates, there are many cases where it continues to operate in a state where it cannot be released easily.

When the present invention is applied to an actual product, the temperature detecting means 7 of the electronic circuit component may be attached to the component having the highest temperature rise, and the detected temperature may be different from the judgment value obtained in FIG. The final judgment value is obtained by multiplying the derating α based on the predetermined derating characteristic shown in FIG. This operation is shown as a flowchart in FIG.

[0015]

As described above, according to the present invention, even under operating conditions such that the DC power supply voltage is extremely lowered and the overload operation is continued, the characteristics of the electronic component are deteriorated due to the temperature rise and heat is not generated. Can be protected from destruction while at the same time
Conventionally, the problems that the overload limiting function is easy to operate during normal operation and the problem that it continues to operate in a state where it cannot be canceled once it has been solved have been solved, the operating range is widened, and air conditioning The ability can be improved. In particular, among the various performances of the air conditioner, there is a great improvement effect on the cooling and heating start-up performances among the manufacturers, which can be said to be very advantageous for improving the performance of the air conditioner.

[Brief description of drawings]

FIG. 1 is a schematic view of a rotation speed control type air conditioner according to the present invention.

FIG. 2 is a diagram showing a relationship between a temperature of an electronic circuit component and an overload limit level according to the present invention.

FIG. 3 is a diagram showing a relationship between a rotation speed of a compressor motor and an overload limit level.

FIG. 4 is a flowchart showing the operation of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2 ... DC voltage detection means, 3 ... DC current detection means, 4 ... Inverter drive part, 5 ... Compressor motor, 6
... inverter control section, 7 ... temperature detecting means for electronic circuit parts.

Claims (2)

[Claims] 1. A rotation speed control type air conditioner having an overload limiting function for protecting a compressor and electronic circuit parts when in an overload operation state, by detecting the temperature of parts to be protected and overloading. A rotation speed control type air conditioner characterized by changing a limit level. 2. The rotation speed control type air conditioner according to claim 1, wherein setting and changing of the overload limit level is processed by software in a microcomputer.