JP7065687B2 - Thermoelectric converter - Google Patents

Description

The present invention relates to a thermoelectric conversion device that converts thermal energy into electrical energy.

Conventionally, there is a thermoelectric conversion device that converts thermal energy into electrical energy by using a thermoelectric conversion material that produces a Zeebeck effect. In the thermoelectric conversion device, a high-temperature side thermoelectric power generation element close to the heat source and a low-temperature side thermoelectric power generation element close to the cooling source are stacked and arranged between the heat source and the cooling source for the purpose of obtaining a high power generation output. There is a cascade type thermoelectric converter.

The thermoelectric conversion material constituting the high-temperature side thermoelectric power generation element and the thermoelectric conversion material constituting the low-temperature side thermoelectric power generation element are different. The high-temperature side thermoelectric power generation element is made of a thermoelectric conversion material such as magnesium silicide (MgSi), which can obtain a relatively high power generation output in a high temperature region of, for example, about 300 ° C. to 600 ° C. The low-temperature side thermoelectric power generation element is made of a thermoelectric conversion material such as bismuth tellurium (BiTe), which can obtain a relatively high power generation output in a low temperature region of about 300 ° C. from room temperature, for example. Conventionally, a thermoelectric conversion device including such a high temperature side thermoelectric power generation element and a low temperature side thermoelectric power generation element has been disclosed (see, for example, Non-Patent Document 1).

In the thermoelectric conversion device, if the temperature of the heat source rises more than expected, the temperature of the portion of the thermoelectric power generation element that receives heat from the heat source exceeds the upper limit heat resistant temperature, and the power generation characteristics of the thermoelectric power generation element may deteriorate. In order to prevent the life of the thermoelectric power generation element from being shortened due to such deterioration of power generation characteristics, a technique for increasing the current returned to the thermoelectric power generation element and lowering the temperature of the portion of the thermoelectric power generation element that receives heat from the heat source by the Pelche effect is disclosed. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-188278

H.T.Kaibe, et al, "Development of thermoelectric generating cascade modules using constituting and Bi-Te", 23rd International Conference on Thermoelectrics, Australia, 2004.

In the cascade type thermoelectric conversion device, especially in the low temperature side thermoelectric power generation element, the thermoelectric conversion material such as bismastellu, the electrode material for electrically connecting the thermoelectric conversion materials, and the joint portion between the electrode and the low temperature side thermoelectric power generation element are used. If the temperature rises above a certain level, the power generation characteristics of the low-temperature side thermoelectric power generation element may deteriorate due to deterioration of the materials or mutual diffusion between the materials, or the thermoelectric conversion device may fail due to disconnection or short circuit of the low-temperature side thermoelectric power generation element. ..

As a countermeasure against such a problem, the technique of Patent Document 1 is applied to the cascade type thermoelectric conversion device, and the current control for increasing the feedback current of the low temperature side thermoelectric power generation element is performed to control the high temperature side of the low temperature side thermoelectric power generation element. The temperature can be lowered. However, in this case, the temperature on the low temperature side of the low temperature side thermoelectric power generation element may rise at the same time, and the low temperature side of the low temperature side thermoelectric power generation element may exceed the upper limit heat resistant temperature. The reason why the temperature on the low temperature side of the low temperature side thermoelectric power generation element rises is that the thermal resistance of the thermoelectric converter decreases due to the Pelche effect, and the ratio of the thermal resistance value between the cooling source and the low temperature side of the low temperature side thermoelectric power generation element is This is because it increases with respect to the thermal resistance value between the cooling source and the heat source.

Further, as the thermal resistance of the thermoelectric conversion device decreases, the amount of penetrating heat flowing from the heat source through the thermoelectric conversion device to the cooling source increases, so that the penetrating heat amount exceeds the cooling capacity of the cooling source, and the cooling source causes thermoelectricity. It becomes impossible to suppress the temperature rise of the converter, which leads to the failure of the thermoelectric converter. Specifically, when the low temperature side of the low temperature side thermoelectric power generation element exceeds the upper limit heat resistant temperature, mechanical damage of the thermoelectric conversion material caused by the thermal stress of the cooling source, deterioration of the power generation characteristics of the thermoelectric power generation element, and the like can be mentioned.

Further, when the cooling source is the liquid cooling method adopted in the radiator used in an automobile or the like, the cooling capacity is lowered due to the temperature rise of the radiator liquid and the boiling of the radiator liquid. When the cooling source is a heat pipe, the cooling capacity is reduced due to the dryout of the refrigerant in the heat pipe. These reductions in cooling capacity cause the temperature of the thermoelectric conversion device to rise, leading to failure of the thermoelectric conversion device due to the disruption of the thermal equilibrium of the entire thermoelectric conversion device. When the liquid cooling method used in the radiator is shared with other cooling sources, temperature control that increases the amount of through heat is not desirable because the temperature rise of the radiator liquid reduces the cooling capacity of other cooling sources. In some cases.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a thermoelectric conversion device capable of suppressing deterioration of power generation characteristics and preventing failure.

In order to solve the above problems, the thermoelectric conversion device according to the present invention is laminated between a heat source, a cooling source provided facing the heat source, and the heat source and the cooling source, and has a high temperature provided on the heat source side. Intermediate temperature measurement provided at the boundary between the side thermoelectric power generation element, the low temperature side thermoelectric power generation element provided on the cooling source side, and the high temperature side thermoelectric power generation element and the low temperature side thermoelectric power generation element, and measuring the temperature of the boundary part. It is equipped with a unit, a high temperature side load adjustment circuit that adjusts the power output by the high temperature side thermoelectric power generation element, and a temperature control unit that controls the high temperature side load adjustment circuit based on the temperature measured by the intermediate temperature measurement unit. The control unit controls the high-temperature side load adjustment circuit so that the amount of current returned to the high-temperature side thermoelectric generation element decreases when the temperature measured by the intermediate temperature measurement unit exceeds a predetermined temperature, and is predetermined. The temperature is set to prevent failure due to overheating of the low-temperature side thermoelectric power generation element .

According to the present invention, the thermoelectric conversion device is laminated with a heat source, a cooling source provided facing the heat source, and a high-temperature side thermoelectric power generation element provided between the heat source and the cooling source, and cooling. An intermediate temperature measuring unit provided at the boundary between the low temperature side thermoelectric power generation element provided on the source side, the high temperature side thermoelectric power generation element and the low temperature side thermoelectric power generation element, and measuring the temperature of the boundary part, and the high temperature side thermoelectric power generation. It is equipped with a high temperature side load adjustment circuit that adjusts the power output by the element and a temperature control unit that controls the high temperature side load adjustment circuit based on the temperature measured by the intermediate temperature measurement unit. The temperature control unit measures the intermediate temperature. When the temperature measured by the unit exceeds a predetermined temperature, the high temperature side load adjustment circuit is controlled so that the amount of current returned to the high temperature side thermoelectric generation element decreases, and the predetermined temperature is the low temperature side thermoelectric. Since the temperature is set to prevent failure due to overheating of the power generation element, it is possible to suppress deterioration of power generation characteristics and prevent failure.

It is a schematic diagram which shows an example of the structure of the thermoelectric conversion apparatus according to Embodiment 1 of this invention. It is a schematic diagram which shows an example of the structure of the high temperature side load adjustment circuit by Embodiment 1 of this invention. It is a figure which shows the relationship of the thermal resistance with respect to the feedback current in the high temperature side thermoelectric power generation element by Embodiment 1 of this invention. It is a schematic diagram which shows an example of the structure of the thermoelectric conversion apparatus according to Embodiment 2 of this invention. It is a schematic diagram which shows an example of the structure of the thermoelectric conversion apparatus according to Embodiment 3 of this invention.

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

<Embodiment 1>
<Overall configuration>
FIG. 1 is a schematic diagram showing an example of the configuration of the thermoelectric conversion device 1 according to the first embodiment of the present invention. The thermoelectric conversion device 1 is assumed to be used when the temperature of the heat source 5 is around 600 ° C and the temperature of the cooling source 6 is around 80 ° C.

As shown in FIG. 1, the thermoelectric conversion device 1 is provided on the high temperature side thermoelectric power generation element 2 provided on the heat source 5 side and on the cooling source 6 side in the thermoelectric conversion unit between the heat source 5 and the cooling source 6. It has a structure in which the low-temperature side thermoelectric power generation element 3 is laminated. The high temperature side thermoelectric power generation element 2 is connected to the external load 10 via the high temperature side load adjusting circuit 9. The details of the high temperature side load adjusting circuit 9 will be described later. The low temperature side thermoelectric power generation element 3 is connected to the external load 10.

As the thermoelectric conversion material constituting the high-temperature side thermoelectric power generation element 2, a material having a high dimensionless figure of merit ZT in a temperature region around 600 ° C. is suitable. Materials having a high non-dimensional performance index ZT in the temperature range around 600 ° C. include, for example, a silicide-based material such as magnesium silicide (MgSi), a scutterdite-based material such as cobalt antimony (CoSb), and lead tellurium (PbTe). Examples include system materials. As the thermoelectric conversion material constituting the low-temperature side thermoelectric power generation element 3, a bismuth tellurium-based material having a relatively high dimensionless figure of merit ZT in the temperature range from room temperature to around 200 ° C. is suitable.

Each of the high-temperature side thermoelectric power generation element 2 and the low-temperature side thermoelectric power generation element 3 is a π-type thermoelectric power generation element in which p-type semiconductors and n-type semiconductors made of two types of semiconductor materials having opposite polarities are alternately connected in series by electrodes. It is configured as a power generation element, and the current value and the voltage value of the high temperature side thermoelectric power generation element 2 and the low temperature side thermoelectric power generation element 3 can be appropriately designed. For the electrodes connecting each semiconductor, a metal with high electrical and thermal conductivity such as nickel or copper is used.

The intermediate ceramic substrate 4 is provided between the high temperature side thermoelectric power generation element 2 and the low temperature side thermoelectric power generation element 3. The intermediate ceramic substrate 4 is made of aluminum nitride (AlN) or aluminum oxide (Al ₂ O ₃ ), which has high thermal conductivity and heat resistance, has insulating properties, and has good mechanical properties.

The intermediate temperature measuring unit 7 is composed of a thermocouple or the like, is provided at a boundary portion between the high temperature side thermoelectric power generation element 2 and the low temperature side thermoelectric power generation element 3, and measures the temperature of the boundary portion. In FIG. 1, the intermediate temperature measuring unit 7 is embedded in the intermediate ceramic substrate 4, but is not limited to this. For example, the intermediate temperature measuring unit 7 may be directly attached or adhered to the intermediate ceramic substrate 4. Since the temperature measured by the intermediate temperature measuring unit 7 is about the same as the maximum temperature of the low temperature side thermoelectric power generation element 3, in order to prevent a failure due to overheating of the low temperature side thermoelectric power generation element 3, the high temperature side thermoelectric power generation element 2 is used. It is effective to provide the intermediate temperature measuring unit 7 at the boundary portion with the low temperature side thermoelectric power generation element 3.

The intermediate temperature measuring unit 7 is connected to the temperature control unit 8. The temperature control unit 8 is connected to the high temperature side load adjustment circuit 9, and controls the high temperature side load adjustment circuit 9 based on the temperature measured by the intermediate temperature measurement unit 7. Specifically, when the intermediate temperature measuring unit 7 is a thermocouple, the temperature control unit 8 converts the electromotive force measured by the intermediate temperature measuring unit 7 into a temperature. The temperature control unit 8 adjusts the electrical load of the high temperature side load adjustment circuit 9 so that the temperature measured by the intermediate temperature measurement unit 7 does not exceed a preset temperature, and the feedback current amount of the high temperature side thermoelectric power generation element 2. To control. That is, the high temperature side load adjusting circuit 9 adjusts the electric power output by the high temperature side thermoelectric power generation element 2 according to the control of the temperature control unit 8.

As shown in FIG. 1, the heat source 5 is in contact with the heat receiving surface of the high temperature side thermoelectric power generation element 2, and the cooling source 6 is in contact with the cooling surface of the low temperature side thermoelectric power generation element 3. A temperature difference is given to the conversion unit.

Specifically, the heat source 5 is provided with a fin-type heat exchanger on the heat receiving surface of the high-temperature side thermoelectric power generation element 2, and is discarded from the exhaust gas of the engine, the heat exhaust discharged from the factory equipment, or the boiler. Heat can be transferred to the high-temperature side thermoelectric power generation element 2 by passing a heat fluid having heat energy such as steam that has been generated through the heat exchanger. Further, heat can be transferred to the high temperature side thermoelectric power generation element 2 by attaching or pressing the heat receiving surface of the high temperature side thermoelectric power generation element 2 to a high temperature part of an internal combustion engine such as an industrial heat treatment furnace or an automobile engine. can. At this time, by sandwiching a heat conductive material such as a carbon sheet between the heat source 5 and the heat receiving surface of the high temperature side thermoelectric power generation element 2, the heat conductivity at the contact interface can be improved.

Specifically, the cooling source 6 is a liquid-cooled sheet sink through which radiator liquid or cooling water flows, and receives heat from the cooling surface of the low-temperature side thermoelectric power generation element 3. Further, the cooling source 6 may be a fin-type air-cooled heat exchanger made of aluminum to exchange heat with the temperature of the atmosphere in order to have a simple structure.

<Structure of high temperature side load adjustment circuit 9>
The output power terminals connected to the positive electrode and the negative electrode of the high temperature side thermoelectric power generation element 2 are connected to the input side positive electrode terminal and the input side negative electrode terminal of the high temperature side load adjustment circuit 9, respectively. An external load 10 such as a battery or a motor is connected to the output side of the high temperature side load adjusting circuit 9. The external load 10 operates by using the electric power output from the high temperature side load adjusting circuit 9.

The high temperature side load adjustment circuit 9 can use an inexpensive and simple circuit method such as a linear regulator, but in order to more efficiently use the power generated by the high temperature side thermoelectric power generation element 2, the output power with respect to the input power. It is desirable to use a switching regulator, which is a circuit system with higher energy conversion efficiency. The switching regulator is a DC-DC converter that steps up and down the input DC power and outputs it by controlling the on / off of the built-in switching element. Since the switching regulator can control the load of the high temperature side load adjustment circuit 9 from the input side of the high temperature side thermoelectric power generation element 2 by the step-up / down ratio of the output voltage, the high temperature side thermoelectric power generation element 2 has a wider range than the linear regulator. It is a circuit method that can control the value of the load applied to the high temperature side thermoelectric power generation element 2 and is effective for load control.

FIG. 2 is a schematic diagram showing an example of the configuration of the high temperature side load adjusting circuit 9. In the example of FIG. 2, a buck-boost chopper circuit is shown, but a switching regulator circuit having a different circuit configuration such as SEPIC (Single Ended Primary Inductance Converter) can be used depending on the input / output specifications of the thermoelectric converter 1. ..

As shown in FIG. 2, the high temperature side load adjusting circuit 9 includes capacitors 11 and 17, switching elements 12 and 15, diodes 13 and 16, and an inductor 14. The capacitor 11 is connected in parallel with the input in order to reduce the ripple voltage of the input power waveform. In the switching element 12, the source electrode is connected to the inductor 14, and the drain electrode is connected to the input positive electrode side. In the diode 13, the anode is connected to the GND line and the cathode is connected to the line of the switching element 12 and the inductor 14. In the switching element 15, the drain electrode is connected to the GND line, and the source electrode is connected to the inductor 14 and the diode 16 line. In the diode 16, the anode is connected to the inductor 14, and the cathode is connected to the positive side of the external load 10. The capacitor 17 is connected in parallel with the output in order to reduce the ripple voltage of the output power waveform.

The gate control signal by PWM (Pulse Width Modulation) of the switching elements 12 and 15 is input from the temperature control unit 8. By controlling the duty ratios of the switching elements 12 and 15, the load of the high temperature side thermoelectric power generation element 2 is adjusted. When controlling to increase the load on the output side as seen from the high temperature side thermoelectric power generation element 2, the duty ratio of the switching element 15 is set to 1, and the duty ratio of the switching element 12 is controlled to be small, so that the high temperature side thermoelectric power generation element 2 is used. Decrease the input current value to be input. The output voltage output from the high temperature side load adjustment circuit 9 is smaller than the input voltage input from the high temperature side thermoelectric power generation element 2, and the output current output from the high temperature side load adjustment circuit 9 is the high temperature side thermoelectric power generation element. It becomes larger than the input current input from 2. In this way, when controlling to increase the load on the output side as seen from the high temperature side thermoelectric power generation element 2, the high temperature side load adjusting circuit 9 performs step-down control.

On the other hand, when controlling to reduce the load on the output side as seen from the high temperature side thermoelectric power generation element 2, the duty ratio of the switching element 12 is set to 1, and the duty ratio of the switching element 15 is largely controlled to pass through the switching element 15. The component of the feedback current that returns to the high temperature side thermoelectric power generation element 2 increases. The output voltage output from the high temperature side load adjustment circuit 9 is larger than the input voltage input from the high temperature side thermoelectric power generation element 2, and the output current output from the high temperature side load adjustment circuit 9 is the high temperature side thermoelectric power generation element. It becomes smaller than the input current input from 2. In this way, when controlling to reduce the load on the output side as seen from the high temperature side thermoelectric power generation element 2, the high temperature side load adjusting circuit 9 performs boost control.

By performing the above control using the high temperature side load adjusting circuit 9, the load applied to the high temperature side thermoelectric power generation element 2 can be increased or decreased.

Further, due to the Zeebeck effect, the high temperature side thermoelectric power generation element 2 can obtain the maximum output power at an applied voltage of about ½ of its open circuit voltage. Therefore, the high temperature side load adjusting circuit 9 can control the high temperature side thermoelectric power generation element 2 to output the maximum power by controlling the applied voltage of the high temperature side thermoelectric power generation element 2.

<Effect>
According to the first embodiment, when the load on the output side as seen from the high temperature side thermoelectric power generation element 2 is controlled to be small, the feedback current to the high temperature side thermoelectric power generation element 2 increases, so that the Pelche effect and the Thomson effect are applied. The amount of heat penetrating from the high temperature side to the low temperature side of the high temperature side thermoelectric power generation element 2 increases, and the thermal resistance Rh of the high temperature side thermoelectric power generation element 2 decreases. FIG. 3 is a diagram simplifying the relationship of the thermal resistance Rh with respect to the feedback current in the high temperature side thermoelectric power generation element 2. When the temperature difference between the high temperature and the low temperature is provided in the n-type semiconductor in the high temperature side thermoelectric power generation element 2, the conduction electrons generated on the high temperature side diffuse to the low temperature side, so that the electrons flow. At this time, heat is transported in the direction in which electrons flow due to the Pelche effect and the Thomson effect. Therefore, if the current is increased in the electromotive force direction, that is, the feedback current amount of the high temperature side thermoelectric power generation element 2 is increased, the n-type semiconductor The amount of heat transported from the high temperature side to the low temperature side increases. Further, when the temperature difference between the high temperature and the low temperature is provided in the p-type semiconductor in the high temperature side thermoelectric power generation element 2, the holes generated on the high temperature side diffuse to the low temperature side, so that the holes flow. At this time, since heat is transported in the direction in which the holes flow, if the current is increased in the electromotive force direction, that is, if the feedback current amount of the high temperature side thermoelectric power generation element 2 is increased, the n-type semiconductor is moved from the high temperature side to the low temperature side. Increases the amount of heat transported. Due to such a phenomenon, in the π-type thermoelectric power generation element, the feedback current amount of the high temperature side thermoelectric power generation element 2 is increased in the electromotive force direction, so that the n-type semiconductor and the p-type semiconductor in the high temperature side thermoelectric power generation element 2 have high temperatures. The amount of heat transported from the side to the low temperature side increases, and the thermal resistance Rh of the high temperature side thermoelectric power generation element 2 decreases.

On the other hand, if control is performed to increase the load on the output side as seen from the high temperature side thermoelectric power generation element 2, the amount of feedback current of the high temperature side thermoelectric power generation element 2 decreases. The amount of heat penetrating from the high temperature side to the low temperature side decreases, and the thermal resistance Rh of the high temperature side thermoelectric power generation element 2 increases. In the first embodiment, when the temperature on the low temperature side of the high temperature side thermoelectric power generation element 2 is predicted to exceed or exceed the heat resistance upper limit temperature, the control to increase the load on the output side as seen from the high temperature side thermoelectric power generation element 2. By utilizing the phenomenon that the heat resistance Rh of the high temperature side thermoelectric power generation element 2 increases, the amount of heat penetrating from the heat source 5 to the cooling source 6 is reduced. As a result, the temperature on the high temperature side of the low temperature side thermoelectric power generation element 3 and the temperature on the low temperature side of the high temperature side thermoelectric power generation element 2 can be lowered, and the life of the low temperature side thermoelectric power generation element 3 and the cooling source 6 can be extended. That is, it is possible to suppress deterioration of the power generation characteristics of the thermoelectric conversion device 1 and prevent failure.

Further, since the temperature control method according to the first embodiment is the control using the thermoelectric effect without the mechanical moving part, the control is input at high speed with respect to the temperature of the temperature control unit 8 to be controlled. Therefore, the effect of failure prevention can be enhanced as compared with other mechanical temperature control methods, for example, a method of adjusting the flow rate of the thermal fluid flowing on the high temperature side to control the amount of heat input.

Further, according to the first embodiment, the reliability of the thermoelectric conversion device 1 is ensured by controlling the temperature so that the temperature at the position of the intermediate temperature measuring unit 7 does not exceed the set value. Load control that always outputs the maximum power can be performed.

<Embodiment 2>
FIG. 4 is a schematic diagram showing an example of the configuration of the thermoelectric conversion device 18 according to the second embodiment of the present invention.

As shown in FIG. 4, the thermoelectric conversion device 18 is characterized by including a low temperature side load adjusting circuit 19. Since other configurations are the same as the configurations shown in FIG. 1 described in the first embodiment, detailed description thereof will be omitted here.

In the first embodiment, it has been described that the temperature of the position of the intermediate temperature measuring unit 7 is controlled by adjusting the load of the high temperature side thermoelectric power generation element 2 in the high temperature side load adjusting circuit 9. In the second embodiment, in addition to this, the temperature control of the position of the intermediate temperature measuring unit 7 will be described by adjusting the load of the low temperature side thermoelectric power generation element 3 in the low temperature side load adjusting circuit 19. The configuration of the low temperature side load adjustment circuit 19 may be the same as the configuration of the high temperature side load adjustment circuit 9, and is, for example, the configuration shown in FIG. Hereinafter, the configuration of the low temperature side load adjusting circuit 19 will be described assuming that it is the configuration shown in FIG. Further, the relationship of the thermal resistance Rc with respect to the feedback current in the low temperature side thermoelectric power generation element 3 is the same as in FIG.

By reducing the load on the output side as seen from the low temperature side thermoelectric power generation element 3 by the PWM control of the switching element of the low temperature side load adjustment circuit 19, the thermal resistance value Rc of the low temperature side thermoelectric power generation element 3 becomes small, and the low temperature side thermoelectric power generation The amount of heat transported from the high temperature side to the low temperature side in the power generation element 3 increases. As a result, the temperature at the position of the intermediate temperature measuring unit 7 can be further lowered. By such load control, even if the temperature range of the high temperature side thermoelectric power generation element 2 is further increased, the temperature rise at the position of the intermediate temperature measuring unit 7 can be suppressed.

<Embodiment 3>
FIG. 5 is a schematic diagram showing an example of the configuration of the thermoelectric conversion device 20 according to the third embodiment of the present invention.

As shown in FIG. 5, the thermoelectric conversion device 20 is characterized by including a high temperature side ceramic substrate 21, a low temperature side ceramic substrate 22, a high temperature side temperature measuring unit 23, and a low temperature side temperature measuring unit 24. Since other configurations are the same as the configurations shown in FIG. 4 described in the second embodiment, detailed description thereof will be omitted here.

The high temperature side ceramic substrate 21 is provided between the heat source 5 and the high temperature side thermoelectric power generation element 2. The low temperature side ceramic substrate 22 is provided between the cooling source 6 and the low temperature side thermoelectric power generation element 3.

The high temperature side temperature measuring unit 23 is composed of a thermocouple or the like, and is provided at the boundary portion between the heat source 5 and the high temperature side thermoelectric power generation element 2. The boundary portion, specifically, the high temperature side of the high temperature side thermoelectric power generation element 2. Measure the temperature. The low temperature side temperature measuring unit 24 is composed of a thermocouple or the like, and is provided at the boundary portion between the cooling source 6 and the low temperature side thermoelectric power generation element 3. The boundary portion, specifically, the low temperature side in the low temperature side thermoelectric power generation element 3. Measure the temperature of.

The temperature values measured by each of the high temperature side temperature measuring unit 23 and the low temperature side temperature measuring unit 24 are sent to the temperature control unit 8. The temperature control unit includes the high temperature side load adjustment circuit 9 and the low temperature within a range not exceeding the upper limit heat resistant temperature at each of the position of the intermediate temperature measurement unit 7, the position of the high temperature side temperature measurement unit 23, and the position of the low temperature side temperature measurement unit 24. The load of the side load adjusting circuit 19 is controlled.

For example, in order to lower the temperature at the position of the high temperature side temperature measuring unit 23, the high temperature side load adjusting circuit 9 and the low temperature side load adjustment circuit 9 and the low temperature side so as to reduce the total thermal resistance of the high temperature side thermoelectric power generation element 2 and the low temperature side thermoelectric power generation element 3. Control is performed to reduce the load of at least one of the side load adjusting circuits 19 and increase the feedback current of at least one of the high temperature side thermoelectric power generation element 2 and the low temperature side thermoelectric power generation element 3. When such control is performed, the temperature at the position of the intermediate temperature measuring unit 7 and the position of the low temperature side temperature measuring unit 24 rises. At this time, in order to lower the temperature at the position of the intermediate temperature measuring unit 7, the load of the low temperature side load adjusting circuit 19 is controlled to be reduced, and the thermal resistance of the low temperature side thermoelectric power generation element 3 is lowered. On the other hand, in order to lower the temperature at the position of the low temperature side temperature measuring unit 24, the load of the high temperature side load adjusting circuit 9 is controlled to be reduced, and the thermal resistance of the high temperature side thermoelectric power generation element 2 is lowered.

In this way, the high temperature side load adjustment circuit 9 and the high temperature side load adjustment circuit 9 and the position of the high temperature side load adjustment unit 9 and the position of the intermediate temperature measurement unit 7 and the position of the low temperature side temperature measurement unit 24 do not exceed the upper limit heat resistant temperature. By controlling the load of the low temperature side load adjusting circuit 19 to be increased or decreased, it is possible to prevent the thermoelectric conversion device 20 from failing.

<Embodiment 4>
The fourth embodiment of the present invention is characterized in that the high temperature side load adjusting circuit 9 has a function of generating a voltage having a polarity opposite to the polarity of the electromotive force of the high temperature side thermoelectric power generation element 2. Other configurations include the thermoelectric conversion device 1 shown in FIG. 1 described in the first embodiment, the thermoelectric conversion device 18 shown in FIG. 4 described in the second embodiment, or the thermoelectric conversion device 18 shown in FIG. 5 described in the third embodiment. Since it is the same as the conversion device 20, detailed description thereof will be omitted here.

The high temperature side load adjusting circuit 9 can generate electric power for passing a current in the direction opposite to the feedback current of the high temperature side thermoelectric power generation element 2 to the high temperature side thermoelectric power generation element 2 by controlling the temperature control unit 8. As the voltage source, a storage battery or another generator can be used. At this time, since the heat transport direction by the electrons and holes in the high temperature side thermoelectric power generation element 2 is reversed by the electric power generated by the high temperature side load adjustment circuit 9, the Pelche effect works in the direction opposite to the heat flowing from the heat source 5. As shown in FIG. 3, the thermal resistance of the high temperature side thermoelectric power generation element 2 can be further increased. As a result, the amount of heat flowing from the high temperature side thermoelectric power generation element 2 to the low temperature side thermoelectric power generation element 3 and the cooling source 6 can be further reduced.

A switch (not shown) is provided, and the wiring of the output terminal is reconnected to the opposite polarity in each of the high temperature side load adjustment circuit 9 and the low temperature side load adjustment circuit 19, so that the high temperature side thermoelectric power generation element 2 has the opposite polarity to the power generation. By applying electric power, the thermal resistance of the high temperature side thermoelectric power generation element 2 can be increased without requiring an external power source.

In the present invention, each embodiment can be freely combined, and each embodiment can be appropriately modified or omitted within the scope of the invention.

1 Thermoelectric converter, 2 High temperature side thermoelectric power generation element, 3 Low temperature side thermoelectric power generation element, 4 Intermediate ceramic substrate, 5 Heat source, 6 Cooling source, 7 Intermediate temperature measurement unit, 8 Temperature control unit, 9 High temperature side load adjustment circuit, 10 External load, 11 capacitors, 12 switching elements, 13 diodes, 14 inductors, 15 switching elements, 16 diodes, 17 capacitors, 18 thermoelectric converters, 19 low temperature side load adjustment circuits, 20 thermoelectric converters, 21 high temperature side ceramic substrates, 22 Low temperature side ceramic substrate, 23 high temperature side temperature measurement unit, 24 low temperature side temperature measurement unit.

Claims (5)

With a heat source
A cooling source provided facing the heat source and
A high-temperature side thermoelectric power generation element laminated between the heat source and the cooling source and provided on the heat source side, and a low-temperature side thermoelectric power generation element provided on the cooling source side.
An intermediate temperature measuring unit provided at a boundary portion between the high temperature side thermoelectric power generation element and the low temperature side thermoelectric power generation element and measuring the temperature of the boundary portion,
A high-temperature side load adjustment circuit that adjusts the power output by the high-temperature side thermoelectric power generation element, and
A temperature control unit that controls the high temperature side load adjustment circuit based on the temperature measured by the intermediate temperature measurement unit, and a temperature control unit.
Equipped with
The temperature control unit installs the high temperature side load adjustment circuit so that the amount of current returned to the high temperature side thermoelectric power generation element decreases when the temperature measured by the intermediate temperature measurement unit exceeds a predetermined temperature. Control and
The thermoelectric conversion device, characterized in that the predetermined temperature is a temperature set for preventing failure due to overheating of the low temperature side thermoelectric power generation element . Further provided with a low temperature side load adjusting circuit for adjusting the electric power output by the low temperature side thermoelectric power generation element,
The temperature control unit controls the low temperature side load adjustment circuit based on the temperature measured by the intermediate temperature measurement unit .
The temperature control unit installs the low temperature side load adjusting circuit so that the amount of current returned to the low temperature side thermoelectric power generation element increases when the temperature measured by the intermediate temperature measurement unit exceeds a predetermined temperature. The thermoelectric conversion device according to claim 1, wherein the thermoelectric conversion device is controlled . A high temperature side temperature measuring unit provided at a boundary portion between the heat source and the high temperature side thermoelectric power generation element and measuring the temperature of the boundary portion, and a high temperature side temperature measuring unit.
A low temperature side temperature measuring unit provided at a boundary portion between the cooling source and the low temperature side thermoelectric power generation element and measuring the temperature of the boundary portion,
Further prepare
In the temperature control unit, the temperature measured by the intermediate temperature measuring unit, the temperature measured by the high temperature side temperature measuring unit, and the temperature measured by the low temperature side temperature measuring unit do not exceed the upper limit heat resistant temperature. The thermoelectric conversion device according to claim 2 , wherein the load of the high temperature side load adjusting circuit and the low temperature side load adjusting circuit are controlled to be increased or decreased . One of claims 1 to 3 , wherein the temperature control unit controls the high temperature side load adjusting circuit so as to generate electric power having a polarity opposite to that of the electric power output by the high temperature side thermoelectric power generation element. The thermoelectric conversion device according to item 1. The thermoelectric conversion device according to any one of claims 1 to 4 , wherein the low-temperature side thermoelectric power generation element is made of a bismuth tellurium-based material.

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