JP2563592B2 - Thermoelectric device control method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric device which utilizes the Peltier effect and is useful as an air conditioner or a refrigerator cooling device for electrically cooling or heating.

2. Description of the Related Art A thermoelectric device that converts electricity into heat has fins on both sides of a thermoelectric element that exchange heat with air, and cools by passing an electric current.

An electric circuit composed of an N-type semiconductor, a conductor, and a P-type semiconductor is formed on a substrate, and when energized, heat is generated or absorbed by the Peltier effect at the interface between the semiconductor and the conductor.
At this time, the fins that are in thermal contact with the heat generating portion and the fins that are in thermal contact with the heat absorbing portion form a heat pump circuit that pumps heat from one air and discards it to the other air.

However, in the conventional thermoelectric device, the current is set to zero when the cooling load is reduced, and thereafter, when the temperature rise exceeds a certain value, the current is supplied and the cooling is restarted to perform intermittent control.
Therefore, when the current is set to zero, the cooling effect is extremely reduced due to the heat flowing from the heat-generating side corrugated fins to the heat-absorbing side corrugated fins through the thermoelectric circuit, which makes the air conditioning uncomfortable and raises the refrigerator temperature. There were challenges.

Further, since the power was turned off and the frost was melted during frost formation, it took time to restart the operation, and there were problems such as room temperature changes and temperature rises in the refrigerator.

The present invention, in consideration of the above-mentioned problems of the prior art, suppresses the heat flow flowing from the heat generation side to the heat absorption side at the time of cooling load reduction, provides the performance improvement of the device, and defrosts in a short time, changes in room temperature and refrigerator It is an object of the present invention to provide a control method that significantly suppresses the internal temperature rise.

Means for Solving the Problems In order to solve the above problems, in the present invention, in a thermoelectric device utilizing the Peltier effect, the minimum current value, Peltier heat absorption amount equal to the amount of heat flowing from the heat generation side of the thermoelectric device to the heat absorption side. The present invention provides a method for controlling a thermoelectric device having a current value that obtains the following value and a method for controlling a current flowing in the opposite direction during defrosting.

Action The action of the present invention obtained by the above control method is as follows.

1. The cooling characteristics of the thermoelectric element are determined by the balance of Peltier heat absorption, Joule heat generation and internal heat conduction, and vary greatly depending on the value of the applied current. When the current is reduced, the amount of heat absorbed by the Peltier becomes equal to that of the fuel flowing to the heat absorption side due to Joule heat generation and heat conduction. At this time, the temperature of the object to be cooled and the temperature of the thermoelectric element become equal, and the thermoelectric device as a whole exhibits the same effect as the heat insulating wall.

2.The thermoelectric element changes the direction of the flowing current,
The heat generating side and the heat absorbing side can be easily changed. In addition, the rate of temperature change is higher than that of normal heat conduction due to the involvement of electrons. The frost can be instantly melted by changing the direction of the current during defrosting and applying heat during frost formation.

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

FIG. 1 shows the configuration of a thermoelectric device according to an embodiment of the present invention.

First, the configuration will be described. An N-type semiconductor 2, a conductor 3, a P-type semiconductor 4, and a conductor 3 are sequentially formed on one surface of the insulating film substrate 1. The two corrugated fins 5 and 5 ′ are located on both sides of the film substrate 1, and the conductor 3
Every other one, and the conductors 3 that are in thermal contact with each other are installed differently. Arrow 6 indicates the current direction during normal cooling. The current 6 is supplied from the power supply 8 controlled by the current controller 7. The current 6 causes the semiconductor 2,
Heat or heat is absorbed by the Peltier effect at the interface between the conductor 4 and the conductor 3.

At this time, since the N-type semiconductors 2 and the P-type semiconductors 4 are alternately arranged, the conductors 3 alternately serve as heat generating portions or heat absorbing portions, and as described above, every other one of the conductors 3 is in thermal contact with each other. One of the fins 5 is a heat generating fin and the other is a heat absorbing fin. In this embodiment, heat is absorbed from the air above the film 1, and the heat is radiated to the air below the film 1. The corrugated fins 5 ′ are pressed against the conductor 3 via the insulating film substrate 1, but since the substrate 1 is sufficiently thin, the corrugated fin 5 ′ (or the conductor 3) is pressed.
The heat transfer (to) is mostly via the corrugated fins 5 '.

Next, a control method of the thermoelectric device of the above-mentioned embodiment will be described, but it should be noted that this control method is established in a basic thermoelectric device, as is apparent from the following description. The configuration of the above embodiment is not limited at all.

FIG. 2 shows a thermoelectric element having a structure in which a semiconductor is connected at both ends of a conductor, one connection interface of which is a heat generation side interface, and the other connection interface of which is a heat absorption side interface. It shows the cooling characteristics of the thermoelectric element when a constant temperature difference is generated. The cooling characteristics depend on the physical properties and shape of the device, but the tendency is the same, and the characteristics are qualitatively shown here.

The power consumption (Qin) is given by Qin ≈ R · I ² from the resistance of the thermoelectric element and the current (I), and becomes a quadratic function with respect to the current.

On the other hand, the cooling output of the thermoelectric element is determined by the balance of Peltier heat absorption, Joule heat generation, and internal heat conduction.
When the current is I ₀ or less, the amount of heat flowing into the heat absorbing portion due to heat conduction is larger than the amount of Peltier heat absorption, and a cooling output cannot be obtained. Since the Peltier heat absorption increases in proportion to the current, the cooling output increases as the current increases.
If it exceeds Im, the cooling output where Joule heat becomes dominant decreases. During normal cooling, a current of about Im will flow. When the cooling load decreases, the current decreases according to the load. The control according to the present invention is to control the current to flow to I ₀ when the cooling load approaches zero,
As a result, the amount of heat flowing from the heat generating side to the heat absorbing side by heat conduction in the conductor becomes equal to the Peltier heat absorption amount.

That is, even when the cooling load approaches zero, it operates so as to block the heat inflow from the heat generating side to the heat absorbing side. As a result, the temperature of the object to be cooled becomes equal to the temperature of the heat absorption side interface, and the thermoelectric device functions like the heat insulating wall. Moreover,
The power consumption at this time varies depending on the physical property value of the thermoelectric element, but in general, I ₀ is about 10% of Im, and the power consumption is 1% during normal operation, which is very small and can be ignored.

That is, the control method of the present invention can solve the above-mentioned conventional problem at the time of reducing the cooling load with a negligible power consumption.

By this control method, even in the thermoelectric device of FIG.
The heat that has passed through the conductor 3 and flows from the heat generating side to the heat absorbing side can be canceled, and the conventional problem can be solved.

Next, during the cooling operation, when the surface of the corrugated fins 5 becomes zero degrees or less, frost is formed. When the amount of frost increases, the ventilation resistance increases and the efficiency decreases, so it becomes necessary to defrost. In the present invention, the current control unit 7 controls the application of a current that is the reverse of normal. As a result, the corrugated fins 5 that normally serve as heat absorbing parts
Becomes a heat generating part, and the frost melts from the surface of the corrugated fins 5. Since the rate of temperature rise is higher than that of normal heat conduction because electrons are involved, frost is instantly melted.

Further, in this example, the defrosting is described to be performed on the entire surface at once, but it is also easy to perform defrosting. Although the number of corrugated fins 5 and 5'is limited in FIG. 1 to explain the configuration of the thermoelectric device, in general use, a large number of corrugated fins 5 and 5'are arranged. Become. By installing a plurality of power supplies 8 and installing the current paths corresponding to the number in parallel, it is possible to divide and defrost. Thereby, the cooling operation can be performed while defrosting, and the comfort and the temperature rise can be further suppressed.

The control method of the thermoelectric device that performs defrosting by applying a current in the opposite direction to the above, and further, the control method that performs defrosting by dividing is also applicable to the basic thermoelectric device described above. It goes without saying that you can do it.

Advantageous Effects of Invention According to the thermoelectric device control method of the present invention, in a thermoelectric device utilizing the Peltier effect, the minimum electric current value is a thermoelectric value that obtains a Peltier heat absorption amount equal to the amount of heat flowing from the heat generating side to the heat absorbing side of the thermoelectric device. Since the control method of the device, and a control method of flowing a current in the opposite direction at the time of defrosting, the influence of the heat flow flowing in the thermoelectric circuit is suppressed, while improving the performance of the device, defrosting is performed in a short time, It is possible to realize a thermoelectric device that significantly suppresses changes in room temperature and temperature rise in the refrigerator.

[Brief description of drawings]

FIG. 1 is a perspective view of a thermoelectric device of one embodiment using the control method of the present invention, and FIG. 2 is a cooling characteristic diagram of a thermoelectric element. 1 ... Film substrate, 2 ... N-type semiconductor, 3 ... Conductor, 4 ... P-type semiconductor, 5 and 5 '... Corrugated fin.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Koji Nakagiri 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 63-163745 (JP, A) JP 55- 14417 (JP, A)

Claims (2)

(57) [Claims] 1. A method for controlling a thermoelectric device, wherein a minimum current value flowing in the thermoelectric device utilizing the Peltier effect is a current value for obtaining a Peltier heat absorption amount equal to the heat amount flowing from the heat generating side to the heat absorbing side of the thermoelectric device. 2. The method of controlling a thermoelectric device according to claim 1, wherein when defrosting the thermoelectric device having a plurality of heat absorbing side interfaces, a reverse current is applied to a part of the plurality of heat absorbing side interfaces.