JP2009195067A - Thermal power generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal power generator that highly accurately controls a current flowing in a thermoelectric module. <P>SOLUTION: The thermal power generator is provided with a DC-DC converter 20, which is provided between a thermoelectric module 4 and a power storage device 7 so as to step up a voltage on the thermoelectric module 4 to a voltage on the power storage device 7, a first current sensor 25A for detecting an input current flowing from the thermoelectric module 4 to the DC-DC converter 20, a second current sensor 25B for detecting an output current flowing from the DC-DC converter 20 to the power storage device 7, and a controller 10 that selects either one of the first current sensor and the second current sensor in accordance with a power generation amount of the thermoelectric module 4 so as to control a current flowing in the thermoelectric module 4 while utilizing a current value detected by the selected current sensor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermoelectric generator that generates electricity using a thermoelectric effect.

  2. Description of the Related Art An automobile exhaust heat power generation apparatus that generates power by generating a temperature difference in a power generation module made of a thermoelectric element material is known. The exhaust heat power generation device for an automobile includes, for example, a power generation module that is attached so that one side surface is in contact with the outer surface of an exhaust pipe that extracts exhaust from an engine, and a cooling that is attached so as to be in contact with the other side surface of the power generation module. Part. And in this electric power generation module, exhaust temperature energy is collect | recovered as electrical energy by producing a temperature difference between the high temperature end which contacts an exhaust pipe, and the low temperature end which contacts a cooling part.

  In recent years, development of technology for improving the recovery efficiency of thermal energy by actively adjusting and controlling the current flowing through the thermoelectric module has been advanced. For example, since there is an optimum current that maximizes the generated power in a thermoelectric module, there is a technique for adjusting and controlling the current that flows through the thermoelectric module so that the optimum current is obtained (see, for example, Patent Document 1).

The power generation device disclosed in Patent Document 1 is an ammeter that measures the value of the current flowing through the thermoelectric module in order to control the current at the time of taking out the electric power from the thermoelectric module so as to be an optimum current at which the maximum electric power can be taken out. Measurement results are used.
Japanese Patent Laying-Open No. 2005-237058

  However, since the current flowing through the thermoelectric module varies greatly depending on the temperature difference, the above-described conventional technique for controlling the power generation state of the thermoelectric module while referring to the output of one ammeter that measures the current value flowing through the thermoelectric module When a thermoelectric module is installed at a location where the temperature difference is large, an ammeter with a wide current value detectable range from a low current to a high current must be used. As a result, the current flowing through the thermoelectric module may not be accurately controlled due to the low resolution of the ammeter.

  Therefore, an object of the present invention is to provide a thermoelectric generator that can accurately control the current flowing through the thermoelectric module.

In order to achieve the above object, a thermoelectric generator according to the present invention comprises:
A DC-DC converter that converts the voltage of the first voltage system to which the thermoelectric module is connected to the voltage of the second voltage system to which the power storage device is connected;
A first current sensor for detecting a current flowing in the first voltage system;
A second current sensor for detecting a current flowing through the second voltage system;
Detection by a current sensor that detects a current flowing in a voltage system having a lower voltage than one of the first current sensor and the second current sensor in a low power generation state where the generated power of the thermoelectric module is low. Based on the value, the current flowing through the thermoelectric module is controlled,
In a high power generation state in which the power generated by the thermoelectric module is higher than that in the low power generation state, a current flowing in a voltage system having a higher voltage than one of the first current sensor and the second current sensor is detected. Control means for controlling a current flowing through the thermoelectric module based on a detected value by a current sensor.

Here, the DC-DC converter is
With a transformer,
First voltage conversion means for converting the voltage of the first voltage system to output to the transformer;
Second voltage conversion means for converting the output voltage of the transformer into a voltage of the second voltage system;
The control means may control a current flowing through the thermoelectric module by controlling voltage conversion of the first voltage conversion means and the second voltage conversion means.

  The thermoelectric module is preferably disposed in an exhaust pipe of a vehicle engine.

  According to the present invention, the current flowing through the thermoelectric module can be accurately controlled.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an arrangement example of thermoelectric modules used in a thermoelectric generator according to an embodiment of the present invention. The thermoelectric module 4 is attached so that one side thereof is in contact with the outside of the exhaust pipe 2 through which exhaust gas from an engine (not shown) is led, and the other side different from the one side is outside the cooling device 5 through which cooling water flows. Installed in contact with. In the case of FIG. 1, five thermoelectric modules 4 a to 4 e are arranged along the outside of the exhaust pipe 2.

  The thermoelectric module 4 is configured by connecting a plurality of thermoelectric elements made of, for example, a Bi—Te based or Si—Ge based semiconductor material. A voltage is generated in the thermoelectric module 4 due to a temperature difference ΔT between the contact surface (high temperature end) of the thermoelectric module 4 with the exhaust pipe 2 and the contact surface (low temperature end) of the thermoelectric module 4 with the cooling device 5. (Seebeck effect), the thermal energy of the exhaust gas flowing through the exhaust pipe 2 can be converted into electric energy and recovered. And each of the thermoelectric modules 4a-4e arrange | positioned along the exhaust pipe 2 converts the thermal energy of the waste gas which flows through the exhaust pipe 2 into electrical energy, and collects it.

  FIG. 2 is a diagram showing the relationship between the thermoelectric generator 100 and the thermoelectric module 4 according to an embodiment of the present invention. The thermoelectric generator 100 includes a controller 10 and a DC-DC converter 20 for collecting waste heat.

  The controller 10 temporarily stores, for example, a control program for executing power generation control that maximizes the generated power and power generation efficiency of the thermoelectric module 4, a ROM that stores the control data, processing data of the control program, and the like. The computer includes a plurality of circuit elements such as a RAM, a CPU for processing a control program, and an input / output interface for exchanging information with the outside. The controller 10 is not limited to one, and may be composed of a plurality of controllers so that control is shared.

  The controller 10 obtains information about the thermal characteristics of the thermoelectric module 4 (for example, Seebeck coefficient, electrical resistance, performance index, etc.) from the outside or has in advance. The controller 10 controls the voltage conversion operation of the DC-DC converter 20 to adjust the current flowing through the thermoelectric module 4 to a predetermined optimum value. The input / output current of the thermoelectric module 4 flows through a plurality of thermoelectric elements therein.

  The controller 10 is a current that flows through the thermoelectric module 4 and is input from the thermoelectric module 4 to the DC-DC converter 20 (in other words, a current drawn from the thermoelectric module 4 or an operating current of the thermoelectric module 4), Information such as an output current Iout that is output from the DC-DC converter 20 and flows to the power storage device 7 (for example, a lead battery, a lithium battery, or a capacitor) is acquired from the current sensor.

  The controller 10 also receives load information such as engine output torque and rotation speed, cooling water temperature of the cooling device 5, exhaust gas flow rate, exhaust gas temperature from other computers such as an engine computer that controls the engine of the vehicle and measurement sensors. Vehicle state information such as vehicle speed may be acquired.

  The controller 10 calculates a target operating current Itgt of the thermoelectric module 4 based on the acquired information, and outputs a voltage conversion operation command signal to the DC-DC converter 20 based on the calculation result.

  On the other hand, the DC-DC converter 20 includes a voltage conversion circuit such as a series regulator or a switching regulator, and is a voltage conversion device that converts a voltage between its input and output. The current Iin drawn from the thermoelectric module 4 is input to the input side of the DC-DC converter 20, and the current Iout that is voltage-converted by the voltage conversion circuit is output from the output side of the DC-DC converter 20. Therefore, by adjusting the current Iin that the DC-DC converter 20 draws from the thermoelectric module 4 according to the command signal of the controller 10 by the voltage conversion operation, it is possible to extract arbitrary power from the output side of the DC-DC converter 20. For example, the controller 10 calculates a target operating current Itgt that maximizes the electric power extracted from the thermoelectric module 4, and the voltage conversion operation of the DC-DC converter 20 is controlled in accordance with a command signal generated based on the calculated value. Thus, the maximum generated power in the thermoelectric module 4 can be supplied to the power storage device 7 from the output side via the DC-DC converter 20.

  FIG. 3 is a relationship diagram between the controller 10 and the DC-DC converter 20. The DC-DC converter 20 supplies the low-voltage side voltage of the low-voltage circuit to which the thermoelectric module 4 is connected (that is, the primary side voltage on the input side of the DC-DC converter 20) according to the command signal from the controller 10. To the high voltage side voltage of the high voltage system circuit (that is, the secondary side voltage on the output side of the DC-DC converter 20).

  The DC-DC converter 20 includes a low voltage side converter 20A, a high voltage side converter 20B, and a transformer 20C.

  The low voltage side converter 20A is a bridge circuit composed of four switching elements 21A, 22A, 23A, and 24A such as FETs and IGBTs, and a current that detects an input current Iin input from the input side of the DC-DC converter 20. A sensor 25A and a voltage sensor 26A that detects an input voltage Vin (corresponding to an output voltage of the thermoelectric module 4) on the input side of the DC-DC converter 20 are provided. The low voltage side converter 20A is provided between the thermoelectric module 4 and the transformer 20C, the input voltage Vin is applied as the input voltage of the low voltage side converter 20A, and the output voltage of the low voltage side converter 20A is the primary winding of the transformer 20C. Applied to line 21C. The low voltage side converter 20A converts direct current into alternating current by a known switching operation of the bridge circuit in accordance with a command signal from the controller 10. That is, the DC input current Iin is converted into an AC current. Note that the current sensor 25 </ b> A and the voltage sensor 26 </ b> A may not be built in the low voltage side converter 20 </ b> A or the DC-DC converter 20.

  The high voltage side converter 20B is a current that detects a bridge circuit composed of four switching elements 21B, 22B, 23B, and 24B such as FETs and IGBTs and an output current Iout that is output from the output side of the DC-DC converter 20. A sensor 25B and a voltage sensor 26B that detects an output voltage Vin (corresponding to an applied voltage of the power storage device 7) on the output side of the DC-DC converter 20 are provided. The high voltage side converter 20B is provided between the transformer 20C and the power storage device 7, and the output voltage of the secondary winding 22C of the transformer 20C is applied as the input voltage of the high voltage side converter 20B. An output voltage is applied to the power storage device 7. The high voltage side converter 20B converts (rectifies) the alternating current boosted by the transformer 20C into a direct current by a known switching operation of the bridge circuit in accordance with a command signal from the controller 10. That is, the output current of the AC transformer 20C is converted into a DC current. The current sensor 25B and the voltage sensor 26B may not be built in the high voltage side converter 20B or the DC-DC converter 20.

  Transformer 20C constitutes primary winding 21C and secondary winding 22C. The primary winding 21C is connected to the bridge circuit of the low voltage side converter 20A, and the secondary winding 22C is connected to the bridge circuit of the high voltage side converter 20B. The transformer 20C boosts the output voltage (AC voltage) of the bridge circuit of the low-voltage side converter 20A in accordance with the winding ratio between the primary winding 21C and the secondary winding 22C, and the boosted voltage is increased to the high-voltage side converter. The output is applied to the input terminal of the 20B bridge circuit.

On the other hand, the controller 10 controls the phase control type DC-DC converter 20. In the DC-DC converter 20 having the configuration of FIG. 3, the output power P and the output current I (effective current i _rms ) output from the output side are:

によって得られる。Ｅ_Ｈは高圧側電圧、Ｅ_Ｌ´は低圧側電圧、Ｔは低圧側駆動信号及び高圧側駆動信号の周期、Ｌはトランス２０Ｃのインダクタンス、Ｔ_Ａは位相差（時間）、δは位相差（角度）を表す。式（１）〜（３）で表される特性を図４に示す。図４は、ＤＣ−ＤＣコンバータ２０の位相差Ｔ_Ａに対する、出力電力Ｐの特性図（ａ）及び出力電流Ｉの特性図（ｂ）である。式（１）から明らかなように出力電力Ｐは位相差Ｔ_Ａ（位相差δ）の二次関数で表されるので、図４に示されるように、位相差Ｔ_Ａ（位相差δ）を増加させることによって出力電力Ｐ（出力電流Ｉ）を増加させることができ、ｄＰ／ｄＴ_Ａ＝０を満たす位相差Ｔ_Ａ（位相差δ）で出力電力Ｐは最大となる。

Obtained by. E _H The high-side voltage, E L _'is low-side voltage, T is the period of the low-voltage-side driving signal and the high-voltage-side driving signal, L is the transformer 20C inductance, T _A is the phase difference (time), [delta] is the phase difference ( Angle). The characteristics represented by the equations (1) to (3) are shown in FIG. 4, with respect to the phase difference _{T A} of the DC-DC converter 20 is a characteristic diagram of the output power P (a) and the characteristic diagram of the output current I (b). Since the output power P as is apparent from equation (1) is expressed by a quadratic function of the phase difference T _{A (phase} difference [delta]), as shown in FIG. 4, the phase difference T _{A (phase} difference [delta]) By increasing it, the output power P (output current I) can be increased, and the output power P becomes maximum at a phase difference T _A (phase difference δ) that satisfies dP / dT _A = 0.

  That is, the controller 10 has a low voltage side drive signal (low voltage side command signal) for driving the bridge circuit of the low voltage side converter 20A and a high voltage side drive signal (high voltage side command signal) for driving the bridge circuit of the high voltage side converter 20B. Output power P output from the output side of the DC-DC converter 20 in accordance with the phase difference between the low voltage side drive signal and the high voltage side drive signal (phase shift of the high voltage side drive signal with respect to the low voltage side drive signal). And the output current I can be adjusted. Note that the low-voltage side drive signal and the high-voltage side drive signal have the same duty ratio (for example, 50%).

  Further, the controller 10 calculates a target operating current Itgt that maximizes the electric power extracted from the thermoelectric module 4.

  FIG. 5 is an example of a calculation process flow of the target operating current Itgt executed by the controller 10. This calculation processing flow starts from S010 every time a switch (such as an ignition switch) for starting / stopping the engine is turned on from off (on every restart).

  The low-voltage side current sensor 25A is set as a default current sensor for detecting a current value used for calculation processing of the target operating current Itgt and a target phase difference δtgt described later (FIG. 6) (S020). Further, the input voltage Vin_ocv is detected by the low voltage side voltage sensor 26A (S030). The input voltage Vin_ocv is an open voltage of the thermoelectric module 4 in a state where the switching elements 21A to 24A are turned off. The initial operating current Iinit is calculated according to the input voltage Vin_ocv detected in S030 and the map of FIG. 7 (S040). FIG. 7 is a map that defines the relationship between the open circuit voltage Vin_ocv and the initial operating current Iinit. The map of FIG. 7 is set in consideration of the characteristics of the thermoelectric module 4 itself, and is built in the memory in advance. The initial operating current Iinit calculated in S040 is set as an initial value to the target operating current Itgt (S050). The processing steps after S060 are executed by timer interruption every time T1, and search for the target operating current Itgt by the hill-climbing method.

  S070 to S090 are used for calculation processing of the target operating current Itgt and the target phase difference δtgt according to the output power P1 which is the product of the target operating current Itgt and the input voltage Vin detected by the low-voltage side voltage sensor 26A. This is a process of switching the use sensor for detecting the current value to either the low voltage side current sensor 25A or the high voltage side current sensor 25B. The accuracy of control can be improved by selecting a current sensor that can accurately detect the current value according to the magnitude of the flowing current value and using the current value detected by the selected current sensor. Because.

  That is, since the temperature difference in the thermoelectric module 4 is small, in the low power generation state where the generated power of the thermoelectric module 4 is small and the input current Iin is also small, the input current Iin detected by the low-voltage side current sensor 25A is set as the target operating current Itgt. This is used for calculating the phase difference δtgt. On the other hand, in the high power generation state where the generated power of the thermoelectric module 4 is large and the input current Iin is large because the temperature difference in the thermoelectric module 4 is large, instead of the input current Iin detected by the low voltage side current sensor 25A, the high voltage side current The input current Iin calculated by converting the output current Iout detected by the sensor 25B is used for the calculation process of the target operating current Itgt and the target phase difference δtgt.

  When the input current Iin is detected by the low-voltage side current sensor in a high power generation state, the input current Iin is large, so the low-voltage side current sensor is required to have a wide current detection range. Will become bigger. However, since the current flowing on the high voltage side is reduced by the DC-DC converter 20 even in a high power generation state, a low current type with a narrow current detection range can be used as a current sensor, so that the current sensor can be reduced in size and cost. It becomes possible.

  Also, if the input current Iin is detected only by the low-voltage side current sensor without setting the high-voltage side current sensor, the current must be detected by a current sensor having a wide current detection range. The resolution deteriorates, and the current value flowing in the low power generation state cannot be detected with high accuracy. However, a current sensor with a narrow current detection range that can detect the magnitude of a current value flowing in a low power generation state as a current sensor on the low power generation side by detecting current with two current sensors on the low voltage side and the high voltage side Therefore, the resolution of the current sensor can be increased, and the current value flowing in the low power generation state can be detected with high accuracy.

  Therefore, in S070, the output power P1 and the threshold value Pth are compared (S070). When the output power P1 is greater than or equal to the threshold value Pth, a high-voltage side current sensor is used instead of the low-voltage side current sensor 25A as a use sensor for detecting a current value used for calculating the target operating current Itgt and the target phase difference δtgt. 25B is set (S080). When the output power P1 is smaller than the threshold value Pth, a low-voltage side current sensor is used instead of the high-voltage side current sensor 25B as a use sensor for detecting a current value used for calculating the target operating current Itgt and the target phase difference δtgt. 25A is set (S090).

The threshold value Pth for switching the current sensor will be described. Assuming that the low voltage side voltage is V1 and the maximum value of the detectable current of the low voltage side current sensor 25A is I1max, the threshold value Pth is:
Pth = V1 × I1max
Can be expressed as Further, assuming that the maximum output power assumed for the thermoelectric module 4 is Pmax and the high-voltage side voltage is V2, the threshold value Pth is:
Pth = Pmax × (V1 / V2)
Can also be expressed.

  For example, if V1 is 40V, V2 is 240V, and the maximum output power Pmax is 2400W, Pth is 400W.

  FIG. 9 is a diagram showing the sensor characteristics of the current sensor. The maximum current I1max that can be detected by the low-voltage side current sensor 25A is 10A, and the maximum current I2max that can be detected by the high-voltage side current sensor 25B is also 10A. Therefore, the low-voltage side current sensor 25A is set up to 0 to 400W, and the high-voltage side sensor 25B is set up to 400W to 2400W.

  Next, processing after S100 in FIG. 5 will be described.

  In S100, the current search unit of the controller 10 first uses the power P1 based on Vin detected by the low-voltage side voltage sensor 26A and the target operating current Itgt (use the value set in S050 in the case of the initial loop in FIG. 5). = Itgt × Vin is calculated.

  Further, in S110, the current search unit adds a small difference ΔI to the target operating current Itgt, and in S120, the controller 10 performs PWM control of the DC-DC converter 20 based on Itgt = Itgt + ΔI, and the current search unit The power P2 = Itgt × Vin is calculated from the voltage Vin detected by the voltage sensor 26A and Itgt = Itgt + ΔI.

  Further, in S130, the current search unit subtracts the slight difference 2ΔI from Itgt. In S140, the controller 10 performs PWM control of the DC-DC converter 20 based on Itgt = Itgt-2ΔI, and the current search unit The power P3 = Itgt × Vin is calculated from the voltage Vin detected by the voltage sensor 26A and the current Itgt = Itgt-2ΔI.

  If P1 is larger than P2 and P3 in S150, P1 is located on the top of the peak PI curve shown in FIG. The current Itgt = Itgt + ΔI.

  In S150, if P1 is not larger than P2 and P3, the process proceeds to S180, and the current search unit determines whether P3 is larger than P2, and if P3 is larger than P2, FIG. In the PI curve shown, P1 is located on the right side of the top of the mountain-shaped curve, so that it is determined that it is descending to the right and the target operating current Itgt is left as it is.

  In S180, when P3 is not larger than P2, the current search unit is positioned on the left side of the top of the mountain-shaped PI curve shown in FIG. In S190, the current Itgt = Itgt + 2ΔI.

  The search process of the target operating current Itgt that is the maximum output of the thermoelectric module 4 by the hill-climbing method after S100 is repeated unless the engine stop signal is detected, and the target operating current Itgt is converged to a value that provides the maximum output. .

  Further, the controller 10 calculates a target phase difference δtgt that maximizes the electric power extracted from the thermoelectric module 4 according to a predetermined control program, and outputs a low-pressure side drive signal and a high-voltage side drive signal with the calculated target phase difference δtgt. To do. The target phase difference δtgt may be a phase difference that maximizes the output power P output from the output side of the DC-DC converter 20. For example, the controller 10 controls the phase difference δ so that the deviation between the input current Iin and the target operating current Itgt calculated in the calculation processing flow of FIG. 5 becomes zero. The phase difference δ that makes this deviation zero corresponds to the target phase difference δtgt.

  FIG. 6 is an example of a calculation process flow of the target phase difference δtgt executed by the controller 10. This calculation process flow is executed by timer interruption, and starts from S300.

  The controller 10 refers to the target operating current Itgt calculated by the calculation process flow of FIG. 5 (S310), and detects the input current Iin by a current sensor (S320). The detection of the input current Iin in S320 is performed based on the detection value by the current sensor of either the low voltage side current sensor 25A or the high voltage side current sensor 25B set by the calculation process flow of FIG. That is, when the low voltage side current sensor 25A is set, the current value itself detected by the low voltage side current sensor 25A corresponds to the input current Iin. On the other hand, when the high-voltage side current sensor 25B is set, the input current Iin is detected by converting the current value detected by the high-voltage side current sensor 25B according to a predetermined conversion formula or conversion map. The PWM control unit of the controller 10 calculates the target phase difference δtgt at which the deviation between the target operating current Itgt referenced in S310 and the input current Iin detected in S320 becomes zero according to a predetermined calculation formula or calculation map (S330). .

  Therefore, the controller 10 is detected by the target operating current Itgt (use the value set in S050 in the first loop of FIG. 5) and the low-voltage side current sensor 25A in the low power generation state where the generated power of the thermoelectric module 4 is small. Based on the input current Iin, the target phase difference δtgt is calculated according to the calculation process flow of FIG. On the other hand, the controller 10 is detected by the target operating current Itgt (use the value set in S050 in the first loop of FIG. 5) and the high-voltage side current sensor 25B in the high power generation state where the generated power of the thermoelectric module 4 is large. Based on the input current Iin calculated by converting the output current Iout, the target phase difference δtgt is calculated according to the calculation process flow of FIG.

  Therefore, according to the above-described embodiment, since the input current Iin detected in the low power generation state has a smaller current value than in the high power generation state, the current sensor having a relatively narrow current detectable range is defined as the low voltage side current sensor 25A. Can be used. Therefore, compared with the case where the input current Iin from the low power generation state where the current value of the input current Iin is small to the high power generation state where the current value of the input current Iin is large is used as the low voltage side current sensor 25A. Since the resolution of the current sensor can be increased, the accuracy of current detection can be increased, and the calculation accuracy of the target operating current Itgt and the target phase difference δtgt can also be increased.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, an example has been given in which the heat source of the thermoelectric module is exhaust gas passing through the exhaust pipe of the engine of the vehicle, but the heat source may have other thermal energy.

  Moreover, although the DC-DC converter 20 illustrated the case where it pressure | voltage-rises, the case where it pressure | voltage-falls is sufficient. In this case, when the thermoelectric module 4 is in the low power generation state, the controller 10 may perform the above-described control using the detection value of the current sensor that detects the current of the circuit after the step-down. The controller 10 may perform the above-described control using the detection value by the current sensor that detects the current of the previous circuit.

It is the figure which showed the example of arrangement | positioning of the thermoelectric module used with the thermoelectric generator which is one Embodiment of this invention. It is the figure which showed the relationship between the thermoelectric generator 100 which is one Embodiment of this invention, and the thermoelectric module 4. FIG. FIG. 3 is a relationship diagram between a controller 10 and a DC-DC converter 20. For the phase difference _{T A} of the DC-DC converter 20 is a characteristic diagram of the output power P (a) and the characteristic diagram of the output current I (b). It is an example of the calculation processing flow of the target operating current Itgt executed by the controller 10. It is an example of the calculation processing flow of target phase difference (delta) tgt performed by the controller. It is the map which defined the relationship between the open circuit voltage Vin_ocv and the initial stage operating current Iinit. It is a schematic diagram which shows the concept of the process which searches the electric current used as the maximum output by the hill-climbing method. It is the figure which showed the sensor characteristic of the current sensors 25A and 25B.

Explanation of symbols

2 exhaust pipe 4 thermoelectric module 5 cooling device 7 power storage device 10 controller 20 DC-DC converter 20A low voltage side converter 20B high voltage side converter 20C transformer 25A low voltage side current sensor 25B high voltage side current sensor 100 thermoelectric generator

Claims (3)

A DC-DC converter that converts the voltage of the first voltage system to which the thermoelectric module is connected to the voltage of the second voltage system to which the power storage device is connected;
A first current sensor for detecting a current flowing in the first voltage system;
A second current sensor for detecting a current flowing through the second voltage system;
Detection by a current sensor that detects a current flowing in a voltage system having a lower voltage than one of the first current sensor and the second current sensor in a low power generation state where the generated power of the thermoelectric module is low. Based on the value, the current flowing through the thermoelectric module is controlled,
In a high power generation state in which the power generated by the thermoelectric module is higher than that in the low power generation state, a current flowing in a voltage system having a higher voltage than one of the first current sensor and the second current sensor is detected. And a control means for controlling a current flowing through the thermoelectric module based on a detection value obtained by a current sensor. The DC-DC converter
With a transformer,
First voltage conversion means for converting the voltage of the first voltage system to output to the transformer;
Second voltage conversion means for converting the output voltage of the transformer into a voltage of the second voltage system;
2. The thermoelectric generator according to claim 1, wherein the control unit controls current flowing in the thermoelectric module by controlling voltage conversion of the first voltage conversion unit and the second voltage conversion unit.   The thermoelectric generator according to claim 2, wherein the thermoelectric module is disposed in an exhaust pipe of an engine of a vehicle.

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