JP2973681B2 - DC booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main DC power source such as a thermoelectric generator utilizing the Seebeck effect in which a temperature difference is generated between the junction surfaces of P-type and N-type semiconductor elements, and a voltage is generated between the junction surfaces. The present invention relates to a DC booster used for boosting a DC output voltage of an output device.

[0002]

2. Description of the Related Art FIG. 2 is a circuit diagram of a thermoelectric generator connected to a conventional DC booster, wherein 15 is a thermoelectric generator and 20 is a DC booster.

[0003] First, the principle and structure of a thermoelectric generator will be described. FIG. 5 is a configuration diagram showing the principle of thermoelectric power generation. In FIG. 5, 1 indicates a P-type thermoelectric element, and 2 indicates an N-type thermoelectric element. Generally, when a temperature difference is applied between the junction surfaces of P-type and N-type semiconductor elements, a voltage is generated between the junction surfaces. This effect is called a Seebeck effect, and a semiconductor element having a large Seebeck effect, such as PbTe or Bi ₂ Te _3, is particularly called a thermoelectric element. One end face of the P-type thermoelectric element 1 and one end face of the N-type thermoelectric element 2 are joined via an electrode 3H, and this electrode 3H is joined to a heat transfer wall 5H via an insulating layer 4H. The other end face of the N-type thermoelectric element 2 and the other end face of the P-type thermoelectric element 1 are respectively joined to electrically separated electrodes 3La and 3Lb, and these electrodes 3La and 3Lb are interposed via an insulating layer 4L. To the heat transfer wall 5L. Heat transfer wall 5H high temperature heat source Q _H
Is heated to heat a joint surface (hereinafter, referred to as a high-temperature side joint surface) in contact with the heat transfer wall 5H, and the low-temperature heat source Q _L
By cooling the heat transfer wall 5L in the above, a joint surface (hereinafter referred to as a low-temperature side joint surface) in contact with the heat transfer wall 5L is cooled,
When a temperature difference is given between these joining surfaces, the electrodes 5La, 5L
When a voltage is generated between the terminals b and a load 6 is connected between the output terminals P and N drawn from these electrodes, a current I flows and power is supplied. FIG. 5 shows a case in which each of the P-type and N-type thermoelectric elements is one. However, a plurality of P-type and N-type thermoelectric elements are thermally connected in parallel to each other.
By connecting the molds alternately in series, the generated voltage increases and a high output is obtained.

FIGS. 3 and 4 show a conventional example of a power generation unit 13 of a thermoelectric generator 15 utilizing the above-described thermoelectric power generation principle. FIG. 3 is a system diagram including a side sectional view of a power generation unit main body. 4
FIG. 2 is a system diagram including a front view showing a partial cross section of a power generation unit main body. 3 and 4, the power generation unit main body 10 has a plurality of P-type thermoelectric elements 1 and N-type thermoelectric elements 2 arranged alternately in a cylindrical shape and a radial direction, respectively, and these thermoelectric elements are arranged on the inner surface and the outer surface of the cylindrical shape. Then, the P-type and N-type are electrically connected alternately in series via the electrodes 3H or 3L to form a high-temperature side bonding surface and a low-temperature side bonding surface. The electrode 3H is coupled to the inner heat transfer wall 5H via the insulating layer 4H, and the electrode 3L is coupled to the outer heat transfer wall 5L via the insulating layer 4L. These plurality of P-type thermoelectric elements 1, N-type thermoelectric elements 2, electrodes 3
H, 3L, insulating layers 4H, 4L, and heat transfer walls 5H, 5L. By heating the heat transfer wall 5H on the cylindrical inner surface of the power generation unit main body 10, the high-temperature side joint surface is heated, and the heat transfer wall 5L is cooled, thereby cooling the low-temperature side joint surface to form these joints. When a temperature difference is applied between the surfaces, a voltage is generated between both ends of the thermoelectric elements connected in series. This voltage is output from output terminals P and N drawn from both ends.

[0005] 12 is an automatic combustion apparatus, to produce a hot gas G ₁ for example by burning oil. The hot gas G ₁ is introduced into the cylindrical bore of the thermoelectric generator unit 10 through the connecting pipe 11A, connecting pipe 11B after heating the heat transfer wall 5H
It is discharged as an exhaust gas G ₂ through. The automatic combustion device 12 is connected to output terminals P and N of the power generation unit main body 10,
The combustion state is controlled so that the generated DC output voltage is constant. A cooling fin 7 cools the cylindrical heat transfer wall 5L of the power generation unit main body 10. The cooling fins 7 are normally cooled by a cooling fan 8.

Reference numeral 14 denotes an output stabilizing circuit for making the DC output current of the power generation unit main body 10 constant irrespective of a change in load, and is provided as necessary. FIG. 6 shows a circuit example of the output stabilizing circuit 14. The collector / emitter of the transistor 15 and the resistor 16 are connected in series between the positive-side and negative-side output terminals c and d, respectively. The negative input terminal b is connected to the output terminal c and the negative output terminal d via the resistor 17. Both terminals of the resistor 17 are connected to a control circuit 18 for controlling the base current of the transistor 15. As an initial state, a part of the input current is supplied to the resistor 16 via the transistor 15 so that the voltage between both terminals of the resistor 17 becomes constant when the load increases (the DC output voltage of the power generation unit main body 10). Is constant), and the control circuit 18
, The current flowing through the resistor 16 is reduced, and when the load decreases, the current flowing through the resistor 16 is increased. The output control by the above-described automatic combustion device 12 has a low control responsiveness due to the heat capacity of the thermoelectric element and the like, but the output control by the output stabilizing circuit has a characteristic that it is purely electric and has a high responsiveness.

In FIG. 2, reference numeral 20 denotes a DC booster, whose positive-side and negative-side main input terminals IP and IN are respectively the positive-side and negative-side output terminals of the thermoelectric generator 15 (in this example, this thermoelectric generator). 15 are connected to the positive and negative output terminals c and d) of the output stabilizing circuit 14, and a boosted DC voltage is output from the positive and negative main output terminals OP and ON. The DC booster 20 has positive and negative input terminals e and f respectively connected to a positive main input terminal I and a negative main input terminal I.
The DC / DC converter 21 is connected to P and IN, and its positive and negative output terminals h are connected to the positive and negative main output terminals OP and ON, respectively.

FIG. 7 shows a circuit example of a DC / DC converter 21. A transformer 24 having a neutral point primary coil and both terminals of the primary coil of the transformer 24 are connected via transistors 22 and 23, respectively. The neutral point is connected to the positive input terminal e, the neutral point is connected to the negative input terminal f, and both terminals of the secondary coil are connected to the positive and negative output terminals g and h via the full-wave rectifier circuit 25. The positive and negative output terminals g and h are connected to the switching control circuit 26 of the transistors 22 and 23. The control circuit 26 controls the transistor 22
And the transistor 23 are alternately turned on and off at a predetermined high frequency, an AC voltage is generated in the secondary coil of the transformer 24 in proportion to 1/2 of the number of turns of the primary coil and in proportion to the number of turns of the secondary coil. By rectifying the AC voltage of the secondary coil with the full-wave rectifier 25, the positive and negative output terminals g,
h outputs a DC voltage. The DC output voltage can be a boosted DC voltage by appropriately selecting the number of turns of the primary and secondary coils. The DC output voltage is input to the control circuit 25, and the DC output voltage can be controlled to be constant by changing the switching width of the transistors 22 and 23 according to the voltage value.

The DC output voltage of the thermoelectric generator 15
That is, the DC input voltage V of the DC booster 20₁Is, for example, 1
2V, and its DC output voltage is
Pressure V _TwoIs boosted, for example, to 24V, which is twice as high.

[0010]

The above-mentioned DC booster receives a main current output device, for example, a full DC output of a thermoelectric generator, and all the inputs are boosted by a DC / DC converter and output. The loss generated in the DC / DC converter is a loss generated for all DC outputs output from the DC booster, and is a large loss. Since the efficiency of thermoelectric generators is low at a few percent to tens of percent, this loss in a DC booster further reduces this lower efficiency of the thermoelectric generator.

An object of the present invention is to provide a DC booster in which generated loss is reduced as much as possible.

[0012]

In order to achieve the above object, a DC booster according to the present invention comprises a positive side and a negative side main input terminal connected to a positive side and a negative side output terminal of a main DC output device, respectively. A DC / DC converter in which the positive and negative input terminals are connected to the positive and negative main input terminals, respectively, and the negative output terminal is connected to the positive main input terminal; A main output terminal connected to the positive output terminal of the DC converter and a main output terminal connected to the negative main input terminal;

[0013]

The DC booster of the present invention has a positive main input terminal connected to the positive output terminal of the main DC output device, a negative main input terminal connected to the negative output terminal of the main DC output device, and a positive input terminal connected to the positive main input terminal and the negative main input terminal. A DC / DC converter having a negative input terminal connected to the positive input terminal and a negative input terminal connected to the negative input terminal, and a positive side connected to a positive output terminal of the DC / DC converter. Since the main output terminal and the negative main output terminal connected to the negative main input terminal are provided, the DC outputs output from the positive and negative main output terminals become positive and negative main output terminals. The sum of the DC output directly output from the DC input input to the input terminal and the DC output output via the DC / DC converter. Therefore, the loss that occurs in the DC / DC converter is a part of the DC output that is output from the positive and negative main output terminals of the DC booster, and the generated loss is reduced.

Here, if the ratio of the DC output shared by the DC / DC converter is small, the generation loss is reduced, but the DC output of the DC booster is also reduced, so that the generation loss of the DC / DC converter is reduced. From the viewpoint of the DC output as a DC booster, the ratio of the DC output directly output and the DC output output via the DC / DC converter among the DC inputs input to the positive and negative main input terminals is It is more effective to set the boost ratio (DC output voltage / DC input voltage) of the DC / DC converter to about 1: 1, that is, about 1.

[0015]

FIG. 1 is a circuit diagram of a main DC output device, for example, a thermoelectric generator, to which a DC booster of the present invention is connected.
Reference numeral 15 denotes a thermoelectric generator, 20 denotes a DC booster, and the thermoelectric generator 15 is a thermoelectric generator 1 shown in FIG.
Exactly the same as 5. The DC booster 20 is connected to the positive and negative output terminals of the thermoelectric generator 15 (the positive and negative output terminals c and d of the output stabilizing circuit 14 of the thermoelectric generator 15 in the example of FIG. 1), respectively. The positive side and negative side main input terminals IP and IN to be connected, and the positive side and negative side input terminals e and f are respectively connected to these positive side and negative side main input terminals IP and IN.
Are connected, and the negative-side input terminal h is connected to the positive-side main input terminal IP (the DC converter 21 is the same as the DC-DC converter 21 shown in FIG. 2). And the positive output terminal g of the DC / DC converter 21
The positive main output terminal OP and the negative main input terminal I
N is connected to the negative side main output terminal ON.

The DC output voltage of the thermoelectric generator 15, that is, the voltage between the positive and negative main input terminals IP and IN is V ₁ , and the step-up ratio (DC output voltage / DC input voltage) of the DC / DC converter is α. Then, the DC output voltage of the DC booster 20, that is, the positive side and negative side main output terminals OP and O
The N-to-N voltage V ₂ is as shown in equation (1).

V ₁ + αV ₁ = V ₂ (1)

By changing the step-up ratio α of the DC / DC converter 21, the DC output voltage V ₂ of the DC step-up device 20 can be set to a predetermined value.

The DC output current of the DC booster is
That is, if the current output from the positive side and negative side main output terminals OP and ON is I ₂ , Equation (2) is obtained from Equation (1).

V ₁ I ₂ + αV ₁ I ₂ = V ₂ I ₂ (2)

In the equation (2), V ₂ I ₂ denotes a DC output output from the positive side and negative side main output terminals OP and ON, and this DC output V ₂ I ₂ is a positive side and a negative side main input. It is the sum of V ₁ I ₂ output directly from the DC inputs input to the terminals IP and IN and αV ₁ I ₂ output via the DC / DC converter 21. Therefore, the DC / DC converter 2
The loss that occurs at 1 is the positive and negative main output terminals OP and O
DC output α of a part of DC output V ₂ I ₂ output from N
V ₁ I ₂ and the resulting loss is reduced.

Here, if the ratio of the DC output shared by the DC / DC converter is small, the generated loss is reduced, but the DC output of the DC booster 20 is also reduced.
From the balance between the loss generated by the DC converter 21 and the DC output of the DC booster 20, the positive-side and negative-side main input terminals IP, IN
Output V directly output from the DC input
The percentage of the DC output alpha] V ₁ I _{2 of 1} I ₂ to be output via a DC-DC converter 21 is 1: about 1, i.e. be set to about one up ratio α of the DC-DC converter more effective For example, with respect to the input DC voltage 12V of the positive and negative main input terminals IP and IN of the DC booster 20, the output DC voltage 12V of the DC / DC converter, that is, the boost ratio α is 1
When the DC output voltage of the positive and negative main output terminals OP and ON is obtained as 24 V, the generated loss is reduced to half.

[0023]

The DC booster of the present invention has a positive main input terminal and a negative main input terminal connected to the positive output terminal and the negative main output terminal of the main DC output device, respectively. A DC / DC converter whose positive side and negative side input terminals are respectively connected, and whose negative side output terminal is connected to the positive side main input terminal, and which is connected to the positive side output terminal of this DC / DC converter. A positive main output terminal and a negative main output terminal connected to the negative main input terminal.
Since the ratio of the DC output shared by the DC / DC converter has been reduced and the generated loss has been reduced, for example, by connecting to a thermoelectric generator having a low efficiency of several to ten and several percent, the low efficiency is minimized. It is possible to increase the voltage without reduction.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a thermoelectric generator to which a DC booster of the present invention is connected.

FIG. 2 is a circuit diagram of a thermoelectric generator connected to a conventional DC booster.

3 is a system diagram including a side cross-sectional view of a power generation unit main body of the power generation unit of the thermoelectric generator of FIG. 2;

4 is a system diagram including a front view showing a partial cross section of a power generation unit main body of the power generation unit of the thermoelectric generator of FIG.

FIG. 5 is a configuration diagram showing the principle of thermoelectric power generation.

6 is a circuit diagram showing an example of an output stabilization circuit of the thermoelectric generator of FIG.

FIG. 7 is a circuit diagram showing an example of a DC / DC converter of the conventional DC boost circuit of FIG. 2;

[Explanation of symbols]

 15 Thermoelectric generator (main DC output device) 20 DC booster 21 DC / DC converter c Positive output terminal (of main current output device 15) d Negative output terminal (of main current output device 15) e Positive side Input terminal (for DC / DC converter 21) f Negative input terminal (for DC / DC converter 21) g Positive output terminal (for DC / DC converter 21) h Negative output terminal (for DC / DC converter) 21) IP Positive main input terminal (for DC booster 20) IN Negative main input terminal (for DC booster 20) OP Positive main output terminal (for DC booster 20) ON Negative main output terminal (for DC booster 20) Of the booster 20)

Claims (3)

(57) [Claims] A positive and negative main input terminal connected to a positive and negative output terminal of a main DC output device, respectively, and the positive and negative main input terminals are respectively connected to the positive and negative input terminals. Are connected, a DC-DC converter whose negative side output terminal is connected to the positive side main input terminal, and a positive side main output terminal connected to the positive side output terminal of this DC / DC converter, A DC booster comprising: a negative main output terminal connected to the negative main input terminal. 2. The DC booster according to claim 1, wherein the DC-DC converter has a boost ratio (DC output voltage / DC input voltage) of about 1. 3. The DC booster according to claim 1, wherein the positive-side and negative-side main input terminals are respectively composed of a plurality of P-type thermoelectric elements and an N-type thermoelectric element, which are thermally in parallel and electrically. P-type and N-type thermoelectric power generation units joined in series alternately. The thermoelectric elements thermally connected in parallel are heated on one side and cooled on the other side. The positive and negative output terminals of a main DC output device comprising a thermoelectric generator in which DC power is output from both ends of these thermoelectric elements joined in series by giving a temperature difference between these joint surfaces A DC booster connected to each other.