JP2019204809A - Thermoelectric conversion device - Google Patents

Abstract

To provide a thermoelectric conversion device capable of preventing failure by suppressing degradation in power generation characteristics.SOLUTION: A thermoelectric conversion device comprises: a heat source 5; a cooling source 6 provided to face the heat source 5; a high-temperature side thermoelectric power generation element 2 provided on the heat source 5 side and a low-temperature side thermoelectric power generation element 3 provided on the cooling source 6 side which are stacked between the heat source 5 and the cooling source 6; an intermediate temperature measurement part 7, provided in a boundary portion between the high-temperature side thermoelectric power generation element 2 and the low-temperature side thermoelectric power generation element 3, which measures the temperature in the boundary portion; a high-temperature side load adjustment circuit 9 which adjusts electric power outputted from the high-temperature side thermoelectric power generation element 2; and a temperature control part 8 which controls the high-temperature side load adjustment circuit 9 on the basis of the temperature measured by the intermediate temperature measurement part 7.SELECTED DRAWING: Figure 1

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 using a thermoelectric conversion material that produces the Seebeck effect. In the thermoelectric converter, for the purpose of obtaining a high power generation output, 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 disposed between the heat source and the cooling source. There is a cascade type thermoelectric converter.

  The thermoelectric conversion material constituting the high temperature side thermoelectric power generation element is different from the thermoelectric conversion material constituting the low temperature side thermoelectric power generation element. The high temperature side thermoelectric power generation element is made of a thermoelectric conversion material such as magnesium silicide (MgSi) that can obtain a relatively high power generation output in a high temperature region of about 300 ° C. to 600 ° C., for example. 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 range from room temperature to about 300 ° C. 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 (for example, see Non-Patent Document 1).

  In the thermoelectric conversion device, when 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 heat resistance temperature, and the power generation characteristics of the thermoelectric power generation element may deteriorate. In order to prevent the shortening of the life of the thermoelectric power generation element due to such deterioration of the power generation characteristics, a technique for increasing the current fed back 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 Peltier effect is disclosed. (For example, refer to Patent Document 1).

Japanese Patent Laying-Open No. 2015-188278

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

  In the cascade type thermoelectric conversion device, particularly in the low temperature side thermoelectric power generation element, the thermoelectric conversion material such as bismuth tellurium, 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: If the temperature exceeds a certain level, the power generation characteristics of the low-temperature side thermoelectric generator may deteriorate due to material deterioration or mutual diffusion between materials, or the thermoelectric conversion device may be damaged due to disconnection or short circuit of the low-temperature side thermoelectric generator. .

  As a countermeasure for such a problem, the technique of Patent Document 1 is applied to a cascade-type thermoelectric conversion device, and current control is performed to increase the feedback current 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 resistance temperature. The reason why the temperature on the low temperature side of the low temperature side thermoelectric generator rises is that the thermal resistance of the thermoelectric converter decreases due to the Peltier effect, and the ratio of the thermal resistance value between the cooling source and the low temperature side of the low temperature side thermoelectric generator is This is because the thermal resistance value between the cooling source and the heat source increases.

  Moreover, since the heat resistance of the thermoelectric conversion device decreases and the amount of through heat flowing from the heat source through the thermoelectric conversion device to the cooling source increases, the amount of through heat exceeds the cooling capacity of the cooling source, and the thermoelectric power is generated by the cooling source. It becomes impossible to suppress the temperature rise of the converter, leading to 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 resistance temperature, mechanical damage of the thermoelectric conversion material caused by the thermal stress of the cooling source, deterioration of power generation characteristics of the thermoelectric power generation element, or the like can be mentioned.

  Furthermore, when the cooling source is a liquid cooling system employed in a 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 by dryout of the refrigerant in the heat pipe. Such a decrease in cooling capacity causes the temperature of the thermoelectric conversion device to rise, leading to failure of the thermoelectric conversion device due to the breakdown of the thermal balance of the entire thermoelectric conversion device. If the liquid cooling method used in the radiator is shared with other cooling sources, the temperature control to increase the heat of penetration is not desirable because the temperature rise of the radiator liquid decreases the cooling capacity of the other cooling source. There is a case.

  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 preventing a failure by suppressing deterioration of power generation characteristics.

  In order to solve the above problems, a thermoelectric conversion device according to the present invention includes a heat source, a cooling source provided opposite to the heat source, and a high temperature layer provided between the heat source and the cooling source and provided on the heat source side. An intermediate temperature measurement that is provided at the boundary portion between the high temperature side thermoelectric power generation element and the low temperature side thermoelectric power generation element provided on the side thermoelectric power generation element and the low temperature side thermoelectric power generation element. A high temperature side load adjustment circuit that adjusts the power output from 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.

  According to the present invention, a thermoelectric conversion device includes a heat source, a cooling source provided opposite to the heat source, a high temperature side thermoelectric power generation element provided between the heat source and the cooling source, and provided on the heat source side, and a cooling device. A low temperature side thermoelectric power generation element provided on the source side, an intermediate temperature measurement 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 a high temperature side thermoelectric power generation Since it includes a high-temperature side load adjustment circuit that adjusts the power output from 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, it suppresses deterioration of power generation characteristics. This makes it possible to prevent breakdown.

It is a schematic diagram which shows an example of a structure of the thermoelectric conversion apparatus by Embodiment 1 of this invention. It is a schematic diagram which shows an example of a 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 a structure of the thermoelectric conversion apparatus by Embodiment 2 of this invention. It is a schematic diagram which shows an example of a structure of the thermoelectric conversion apparatus by 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 illustrating an example of a configuration of a thermoelectric conversion device 1 according to Embodiment 1 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 section between the heat source 5 and the cooling source 6. The low-temperature side thermoelectric generator 3 has a laminated structure. The high temperature side thermoelectric generator 2 is connected to an external load 10 via a high temperature side load adjustment circuit 9. Details of the high temperature side load adjustment circuit 9 will be described later. The low temperature side thermoelectric generator 3 is connected to the external load 10.

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

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

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 ) having high thermal conductivity and heat resistance, insulating properties, and good mechanical properties.

  The intermediate temperature measurement part 7 is comprised with a thermocouple etc., is provided in the boundary part of 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 said boundary part. In FIG. 1, the intermediate temperature measurement unit 7 is embedded in the intermediate ceramic substrate 4, but is not limited thereto. For example, the intermediate temperature measurement unit 7 may be directly attached or bonded 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, It is effective to provide the intermediate temperature measuring unit 7 at the boundary with the low temperature side thermoelectric generator 3.

  The intermediate temperature measurement 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 measurement unit 7 is a thermocouple, the temperature control unit 8 converts the electromotive force measured by the intermediate temperature measurement 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 amount of feedback current of the high temperature side thermoelectric generator 2 To control. That is, the high temperature side load adjustment circuit 9 adjusts the electric power output from the high temperature side thermoelectric generator 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 converter.

  Specifically, the heat source 5 is provided with a fin-type heat exchanger on the heat-receiving surface of the high-temperature side thermoelectric generator 2 and is discarded from the exhaust gas from the engine or the exhaust from the factory or from the boiler. The heat can be transferred to the high temperature side thermoelectric generator 2 by passing the heat fluid having heat energy such as water vapor passed through the heat exchanger. Further, the heat receiving surface of the high temperature side thermoelectric power generation element 2 can be transferred to the high temperature side thermoelectric power generation element 2 by being attached to or pressed against a high temperature part of an industrial heat treatment furnace or an internal combustion engine such as an automobile engine. it can. At this time, by interposing 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 generator 2, the thermal conductivity at the contact interface can be improved.

  Specifically, the cooling source 6 is a liquid-cooled sheet sink in which a radiator liquid or cooling water flows, and receives heat from the cooling surface of the low-temperature side thermoelectric power generation element 3. The cooling source 6 may be an aluminum fin-type air-cooled heat exchanger for exchanging heat with the atmospheric temperature in order to have a simple configuration.

<Configuration 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 generator 2 are connected to the input positive electrode terminal and the input negative electrode terminal of the high temperature side load adjustment circuit 9 respectively. An external load 10 such as a battery or a power machine is connected to the output side of the high temperature side load adjustment circuit 9. The external load 10 operates using the power output from the high temperature side load adjustment circuit 9.

  The high temperature side load adjustment circuit 9 can use an inexpensive and simple circuit system such as a linear regulator, but in order to use the power generated by the high temperature side thermoelectric generator 2 more efficiently, the output power relative to the input power It is desirable to use a switching regulator that is a circuit system with higher energy conversion efficiency. The switching regulator is a DC-DC converter that steps up / down and outputs input DC power by on / off control of a built-in switching element. Since the switching regulator can control the load viewed from the input side of the high temperature side thermoelectric generator element 2 from the input side of the high temperature side load adjustment circuit 9 by the step-up / down ratio of the output voltage, the high temperature side thermoelectric generator element 2 has a wider range than the linear regulator. This is a circuit system that can control the value of the load on the high temperature side thermoelectric generator 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 adjustment circuit 9. In the example of FIG. 2, a step-up / step-down chopper circuit is shown, but a switching regulator circuit having a different circuit configuration such as a SEPIC (Single Ended Primary Inductance Converter) can be used according to the input / output specifications of the thermoelectric converter 1. .

  As shown in FIG. 2, the high-temperature side load adjustment 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 to the input in order to reduce the ripple voltage of the input power waveform. The switching element 12 has a source electrode connected to the inductor 14 and a drain electrode connected to the input positive electrode side. The diode 13 has an anode connected to the GND line and a cathode connected to the line of the switching element 12 and the inductor 14. The switching element 15 has a drain electrode connected to the GND line and a source electrode connected to the inductor 14 and diode 16 lines. The diode 16 has an anode connected to the inductor 14 and a cathode connected to the positive side of the external load 10. The capacitor 17 is connected in parallel to the output in order to reduce the ripple voltage of the output power waveform.

  A gate control signal by PWM (Pulse Width Modulation) of the switching elements 12 and 15 is input from the temperature control unit 8. The load adjustment of the high temperature side thermoelectric generator 2 is performed by controlling the duty ratio of the switching elements 12 and 15. When performing control to increase the load on the output side viewed 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. Decrease the input current value. 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 generation element 2, and the output current output from the high temperature side load adjustment circuit 9 is the high temperature side thermoelectric generation element. 2 is larger than the input current input from 2. As described above, when the control for increasing the load on the output side viewed from the high temperature side thermoelectric generator 2 is performed, the high temperature side load adjustment circuit 9 performs the step-down control.

  On the other hand, when control is performed to reduce the load on the output side as viewed from the high temperature side thermoelectric generator 2, the duty ratio of the switching element 12 is set to 1 and the duty ratio of the switching element 15 is controlled to be large, thereby passing through the switching element 15. Thus, the component of the feedback current that returns to the high temperature side thermoelectric generator 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 generation element 2, and the output current output from the high temperature side load adjustment circuit 9 is the high temperature side thermoelectric generation element. 2 is smaller than the input current input from 2. Thus, when performing control to reduce the load on the output side as viewed from the high temperature side thermoelectric power generation element 2, the high temperature side load adjustment circuit 9 performs boost control.

  By performing the above-described control using the high temperature side load adjustment circuit 9, the load applied to the high temperature side thermoelectric generator 2 can be increased or decreased.

  Further, due to the Seebeck effect, the high-temperature side thermoelectric generator 2 can obtain the maximum output power at an applied voltage in the vicinity of ½ of the open circuit voltage. Therefore, the high temperature side thermoelectric power generation element 2 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 control is performed to reduce the load on the output side viewed from the high temperature side thermoelectric power generation element 2, the feedback current to the high temperature side thermoelectric power generation element 2 increases, and therefore, due to the Peltier effect and the Thomson effect The amount of penetration heat from the high temperature side to the low temperature side in 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 simplified diagram of the relationship of the thermal resistance Rh to the feedback current in the high temperature side thermoelectric generator 2. When a temperature difference between a high temperature and a low temperature is provided in the n-type semiconductor in the high temperature side thermoelectric generator 2, electrons flow by diffusion of conduction electrons generated on the high temperature side to the low temperature side. At this time, since heat is transported in the direction in which electrons flow due to the Peltier effect and the Thomson effect, increasing the current in the electromotive force direction, that is, increasing the feedback current amount of the high-temperature-side thermoelectric power generation element 2, The amount of heat transport from the high temperature side to the low temperature side increases. Further, when a temperature difference between a high temperature and a low temperature is provided in the p-type semiconductor in the high temperature side thermoelectric generator 2, holes flow due to diffusion of holes generated on the high temperature side to the low temperature side. At this time, since heat is transported in the direction in which the holes flow, increasing the current in the electromotive force direction, that is, increasing the feedback current amount of the high-temperature side thermoelectric generator 2 increases the temperature of the n-type semiconductor from the high temperature side to the low temperature side. The amount of heat transport increases. Due to such a phenomenon, in the π-type thermoelectric power generation element, by increasing the feedback current amount of the high temperature side thermoelectric power generation element 2 in the electromotive force direction, the n type semiconductor and the p type semiconductor in the high temperature side thermoelectric power generation element 2 have a high temperature. 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 generator 2 decreases.

  On the other hand, when the control to increase the load on the output side as viewed from the high temperature side thermoelectric power generation element 2 is performed, the amount of feedback current of the high temperature side thermoelectric power generation element 2 decreases, and thus in the high temperature side thermoelectric power generation element 2 due to the Peltier effect and the Thomson effect. The amount of through heat from the high temperature side to the low temperature side decreases, and the thermal resistance Rh of the high temperature side thermoelectric generator 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 resistant upper limit temperature, the control is performed to increase the load on the output side as viewed from the high temperature side thermoelectric power generation element 2. The amount of through heat from the heat source 5 to the cooling source 6 is reduced by utilizing the phenomenon that the thermal resistance Rh of the high temperature side thermoelectric power generation element 2 increases by performing the above. Thereby, the temperature on the high temperature side in the low temperature side thermoelectric power generation element 3 and the temperature on the low temperature side in the high temperature side thermoelectric power generation element 2 can be lowered, and the lifetime of the low temperature side thermoelectric power generation element 3 and the cooling source 6 can be extended. That is, it is possible to prevent the failure by suppressing the deterioration of the power generation characteristics of the thermoelectric conversion device 1.

  Further, since the temperature control method according to the first embodiment is a control using the thermoelectric effect without a mechanical movable part, the control input is performed at a high speed with respect to the temperature of the temperature control part 8 as a control target. Compared with other mechanical temperature control methods, for example, a method of controlling the amount of heat input by adjusting the flow rate of the thermal fluid flowing on the high temperature side, the effect of preventing failure can be enhanced.

  Furthermore, according to the first embodiment, by controlling the temperature so that the temperature at the position of the intermediate temperature measurement unit 7 does not exceed the set value, the reliability of the thermoelectric conversion device 1 is ensured. Load control that always outputs 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 includes a low-temperature side load adjustment circuit 19. The other configuration is the same as the configuration shown in FIG. 1 described in the first embodiment, and detailed description thereof is omitted here.

  In the first embodiment, the temperature control of the position of the intermediate temperature measuring unit 7 has been described by performing the load adjustment of the high temperature side thermoelectric power generation element 2 by the high temperature side load adjustment 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 generator 3 by the low temperature side load adjustment 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, for example, as shown in FIG. In the following description, it is assumed that the configuration of the low temperature side load adjustment circuit 19 is the configuration shown in FIG. Further, the relationship of the thermal resistance Rc to the feedback current in the low temperature side thermoelectric generator 3 is the same as that in FIG.

  By reducing the load on the output side viewed from the low temperature side thermoelectric power generation element 3 by 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 is reduced, and the low temperature side thermoelectric power generation element 3 is reduced. The amount of heat transported from the high temperature side to the low temperature side in the power generation element 3 increases. Thereby, the temperature of the position of the intermediate temperature measurement part 7 can further be reduced. By such load control, even if the temperature range of the high temperature side thermoelectric generator 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 Embodiment 3 of the present invention.

  As shown in FIG. 5, the thermoelectric conversion device 20 includes a high temperature side ceramic substrate 21, a low temperature side ceramic substrate 22, a high temperature side temperature measurement unit 23, and a low temperature side temperature measurement unit 24. The other configuration is the same as the configuration shown in FIG. 4 described in the second embodiment, and detailed description thereof is omitted here.

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

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

  The temperature values measured by the high temperature side temperature measurement unit 23 and the low temperature side temperature measurement 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 that does not exceed the upper 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 adjustment 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 adjustment circuit 9 and the low temperature are adjusted so that the total thermal resistance of the high temperature side thermoelectric power generation element 2 and the low temperature side thermoelectric power generation element 3 decreases. Control is performed to reduce the load of at least one of the side load adjustment circuits 19 and increase the feedback current of at least one of the high temperature side thermoelectric element 2 and the low temperature side thermoelectric element 3. When such control is performed, the temperature at the position of the intermediate temperature measurement unit 7 and the position of the low temperature side temperature measurement unit 24 rises. At this time, in order to lower the temperature at the position of the intermediate temperature measuring unit 7, control is performed to reduce the load of the low temperature side load adjustment circuit 19, and the thermal resistance of the low temperature side thermoelectric generator 3 is lowered. On the other hand, in order to reduce the temperature at the position of the low temperature side temperature measurement unit 24, control is performed to reduce the load of the high temperature side load adjustment circuit 9, and the thermal resistance of the high temperature side thermoelectric generator 2 is reduced.

  Thus, the high temperature side load adjustment circuit 9 and the temperature of the position of the high temperature side temperature measurement unit 23, 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 resistance temperature and By performing control to increase or decrease the load of the low-temperature side load adjustment circuit 19, failure of the thermoelectric conversion device 20 can be prevented.

<Embodiment 4>
Embodiment 4 of the present invention is characterized in that the high temperature side load adjustment 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 are 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 shown in FIG. 5 described in the third embodiment. Since it is the same as that of the converter 20, detailed description is abbreviate | omitted here.

  The high temperature side load adjustment circuit 9 can generate electric power that causes the current flowing in the opposite direction to the feedback current of the high temperature side thermoelectric power generation element 2 to flow through the high temperature side thermoelectric power generation element 2 under the control of the temperature control unit 8. As the voltage source, a storage battery or another generator can be used. At this time, the direction of heat transport by electrons and holes in the high temperature side thermoelectric generator 2 is reversed by the electric power generated by the high temperature side load adjustment circuit 9, so that the Peltier effect works in the opposite direction to the heat flowing from the heat source 5. As shown in FIG. 3, the thermal resistance of the high temperature side thermoelectric generator 2 can be further increased. Thereby, 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.

  In addition, a switch (not shown) is provided, and the wiring of the output terminal is switched to the reverse 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 reverse polarity to the power generation. By applying electric power, the thermal resistance of the high temperature side thermoelectric generator 2 can be increased without requiring an external power source.

  Note that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion device, 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 part, 8 Temperature control part, 9 High temperature side load adjustment circuit, 10 External load, 11 capacitor, 12 switching element, 13 diode, 14 inductor, 15 switching element, 16 diode, 17 capacitor, 18 thermoelectric conversion device, 19 low temperature side load adjustment circuit, 20 thermoelectric conversion device, 21 high temperature side ceramic substrate, 22 Low temperature side ceramic substrate, 23 High temperature side temperature measurement unit, 24 Low temperature side temperature measurement unit.

Claims (7)

A heat source,
A cooling source provided opposite the heat source;
Laminated between the heat source and the cooling source, a high temperature side thermoelectric power generation element provided on the heat source side, and a low temperature side thermoelectric power generation element provided on the cooling source side,
An intermediate temperature measurement unit that is provided at a boundary portion between the high temperature side thermoelectric power generation element and the low temperature side thermoelectric power generation element and measures the temperature of the boundary portion;
A high temperature side load adjustment circuit for adjusting the power output by the high temperature side thermoelectric generator, and
Based on the temperature measured by the intermediate temperature measurement unit, a temperature control unit for controlling the high temperature side load adjustment circuit,
A thermoelectric conversion device.   The temperature control unit sets the high-temperature side load adjustment circuit so that a current amount fed back to the high-temperature side thermoelectric generator decreases 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 low temperature side load adjustment circuit for adjusting the power output by the low temperature side thermoelectric generator,
The thermoelectric conversion device according to claim 1, wherein 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 sets the low-temperature side load adjustment circuit so that an amount of current returning to the low-temperature side thermoelectric generator increases when the temperature measured by the intermediate temperature measurement unit exceeds a predetermined temperature. The thermoelectric conversion device according to claim 3, wherein the thermoelectric conversion device is controlled. A high temperature side temperature measurement unit that is provided at a boundary portion between the heat source and the high temperature side thermoelectric generator, and measures the temperature of the boundary portion;
A low temperature side temperature measurement unit that is provided at a boundary portion between the cooling source and the low temperature side thermoelectric generator, and measures the temperature of the boundary portion;
Further comprising
The temperature control unit, based on the temperature measured by the intermediate temperature measurement unit, the temperature measured by the high temperature side temperature measurement unit, and the temperature measured by the low temperature side temperature measurement unit, the high temperature side load adjustment circuit and the The thermoelectric conversion device according to claim 3 or 4, wherein at least one of the low-temperature side load adjustment circuits is controlled.   The temperature control unit controls the high temperature side load adjustment circuit so as to generate electric power having a polarity opposite to that of the electric power output from the high temperature side thermoelectric power generation element. The thermoelectric conversion apparatus according to Item 1.   The thermoelectric conversion device according to any one of claims 1 to 6, wherein the low temperature side thermoelectric power generation element is made of a bismuth tellurium-based material.

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