Power system

Abstract

To make more effective use of the power generated by a power generating element and stabilizes the power supply to a load.SOLUTION: A power system 1 is provided with a battery 13, a first DC / DC converter 14 to which the discharge power output by the battery 13 is input, a second DC / DC converter 15 that outputs supply power to a load 4 using the power generated by a power generation element 3 and the output power of the first DC / DC converter 14, a third DC / DC converter 16 that supplies charging power to the battery 13 using the power generated by the power generation element 3, and a control unit 30 that controls the first DC / DC converter 14 on the basis of the output voltage of the first DC / DC converter 14 and controls the second DC / DC converter 15 on the basis of the output voltage of the second DC / DC converter 15.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power supply system that supplies power to a load by using power generated by a power generating element having an internal resistance. [Background technology]

[0002] The power supply system disclosed in Patent Document 1 includes a battery, a first converter to which discharge power output by the battery is input, a power generating element, a second converter to which generated power output by the power generating element is input, and a control circuit that controls the first and second converters by referring to the output voltages and output currents of the first and second converters. In this power supply system, the outputs of the first and second converters are connected to a load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4333658 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, the outputs of the first and second converters are connected to each other, so fluctuations in the output voltage of one converter affect the control of the other converter, making it difficult to stabilize the total power supplied to the load from the first and second converters.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to more effectively utilize the power generated by a power generating element and to easily stabilize the power supplied to a load. [Means for solving the problem]

[0006] In order to achieve the above object, a first aspect of the present disclosure is a power supply system that supplies supply power to a load using generated power output by a power generation element having an internal resistance, the power supply system comprising: a battery; a first DC / DC converter to which discharge power output by the battery is input; a second DC / DC converter that outputs the supply power using the generated power and the output power of the first DC / DC converter; a third DC / DC converter that supplies charging power to the battery using the generated power; and a control unit that controls the first DC / DC converter based on an output voltage of the first DC / DC converter, and controls the second DC / DC converter based on the output voltage of the second DC / DC converter.

[0007] As a result, the output of the first DC / DC converter is connected to the input side of the second DC / DC converter, which makes it easier to control and stabilize the output voltage of the second DC / DC converter compared to when the outputs of the first and second DC / DC converters are connected to each other. Therefore, the power supplied to the load by the second DC / DC converter can be easily stabilized.

[0008] In addition, the battery can be charged by the power generated by the power generating element.

[0009] A second aspect of the present disclosure is a power supply system that supplies supply power to a load using generated power output by a power generation element having an internal resistance, and is characterized in comprising: a battery; a first DC / DC converter capable of operating in a discharge mode in which discharge power output by the battery is input and a charge mode in which charging power is supplied to the battery using the generated power; a second DC / DC converter that outputs the supply power using the generated power and the output power of the first DC / DC converter; and a control unit that controls the first DC / DC converter based on an output voltage of the first DC / DC converter and controls the second DC / DC converter based on the output voltage of the second DC / DC converter.

[0010] As a result, the output of the first DC / DC converter is connected to the input side of the second DC / DC converter, which makes it easier to control and stabilize the output voltage of the second DC / DC converter compared to when the outputs of the first and second DC / DC converters are connected to each other. Therefore, the power supplied to the load by the second DC / DC converter can be easily stabilized.

[0011] In addition, the battery can be charged by the power generated by the power generating element.

[0012] A third aspect of the present disclosure is characterized in that, in the first or second aspect, the power generating element further includes a current detection unit that detects an output current of the power generating element and a voltage detection unit that detects an output voltage of the power generating element, and the control unit controls the first DC / DC converter based on the detection value of the current detection unit and the detection value of the voltage detection unit.

[0013] This allows the control unit to adjust the power supplied from the battery to the load according to the detection value of the current detection unit and the detection value of the voltage detection unit, that is, according to the power generated by the power generation element.

[0014] A fourth aspect of the present disclosure is characterized in that, in the third aspect, the control unit controls the first DC / DC converter so that the product of the detection value of the current detection unit and the detection value of the voltage detection unit becomes the maximum output power of the power generation element.

[0015] This allows the power generated by the power generating element to be used effectively, and the supply voltage to be stabilized.

[0016] A fifth aspect of the present disclosure is characterized in that, in the first aspect, the power generating device further includes a current detection unit that detects an output current of the power generating element and a voltage detection unit that detects an output voltage of the power generating element, and the control unit controls the third DC / DC converter based on the detection value of the current detection unit and the detection value of the voltage detection unit.

[0017] This makes it possible to adjust the charging power supplied to the battery according to the detection value of the current detection section and the detection value of the voltage detection section, that is, according to the power generated by the power generating element.

[0018] A sixth aspect of the present disclosure is characterized in that, in the fifth aspect, the control unit controls the third DC / DC converter so as to maximize the charging power based on the detection value of the current detection unit and the detection value of the voltage detection unit.

[0019] This allows the power generated by the power generating element to be used effectively, and the battery can be charged efficiently.

[0020] A seventh aspect of the present disclosure is characterized in that, in the second aspect, the power generating device further includes a current detection unit that detects an output current of the power generating element and a voltage detection unit that detects an output voltage of the power generating element, and the control unit controls the first DC / DC converter based on the detection value of the current detection unit and the detection value of the voltage detection unit so as to maximize the charging power.

[0021] This allows the power generated by the power generating element to be used effectively, and the battery can be charged efficiently. Effect of the Invention

[0022] According to the present disclosure, it is possible to easily stabilize the power supplied to the load, and also to charge the battery using the power generated by the power generation element. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a block diagram showing a configuration of a power supply system according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is an example of a circuit diagram showing a detailed configuration of the first to third DC / DC converters. [Diagram 3] FIG. 3 is a flowchart illustrating the operation of the power supply system according to the first embodiment. [Figure 4]FIG. 4 is a flowchart illustrating the operation of the power supply system in the charging mode. [Diagram 5] FIG. 5 is a graph illustrating the relationship between the output voltage and the output power of the power generating element when the maximum output power of the power generating element is equal to or greater than the required power. [Figure 6] FIG. 6 is a diagram equivalent to FIG. 5 in the case where the maximum output power of the power generating element is less than the required power. [Figure 7] FIG. 7 is a view corresponding to FIG. 1 of the second embodiment. [Figure 8] FIG. 8 is a view corresponding to FIG. 2 of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0025] <Embodiment 1> 1 shows the configuration of a power supply system 1 according to a first embodiment of the present disclosure. This power supply system 1 supplies power to a load 4 using power generated by a power generation element 3 having an internal resistance 31. As the power generation element 3, for example, a thermoelectric element such as Flexina (registered trademark), a perovskite solar cell, or a piezoelectric element such as a piezo film can be used.

[0026] The power supply system 1 includes a current detection unit 11, a voltage detection unit 12, a battery 13, a first DC / DC converter 14, a second DC / DC converter 15, a third DC / DC converter 16, a first diode 20, and a control unit 30.

[0027] The current detector 11 detects the output current of the power generating element 3 .

[0028] The voltage detection unit 12 detects the output voltage of the power generating element 3 .

[0029] The battery 13 outputs discharge power and is supplied with charging power.

[0030] As shown in FIG. 2, the first DC / DC converter 14 includes a first input terminal 14a, a first input side capacitor 14b, a first input side coil 14c, a first switch element 14d, a first filter capacitor 14e, a first filter coil 14f, a second diode 14g, a first output side capacitor 14h, a first output terminal 14i, and a first voltage detector 14j.

[0031] Discharge power output by the battery 13 is input to the first input terminal 14a.

[0032] One end of the first input side capacitor 14b is connected to the first input terminal 14a, and the other end of the first input side capacitor 14b is grounded.

[0033] One end of the first input coil 14c is connected to the first input terminal 14a.

[0034] One end of the first switch element 14d is connected to the other end of the first input coil 14c, and the other end of the first switch element 14d is grounded.

[0035] One end of the first filter capacitor 14e is connected to one end of the first switch element 14d.

[0036] One end of the first filter coil 14f is connected to the other end of the first filter capacitor 14e, and the other end of the first filter coil 14f is grounded.

[0037] The anode of the second diode 14g is connected to the other end of the first filter capacitor 14e and to the one end of the first filter coil 14f.

[0038] One end of the first output-side capacitor 14h is connected to the cathode of the second diode 14g, and the other end of the first output-side capacitor 14h is grounded.

[0039] The first output terminal 14i is connected to the one end of the first output-side capacitor 14h.

[0040] The first voltage detector 14j detects the voltage at the first output terminal 14i, that is, the output voltage of the first DC / DC converter .

[0041] The second DC / DC converter 15 outputs power to be supplied to the load 4 using the power generated by the power generating element 3 and the output power of the first DC / DC converter 14. The second DC / DC converter 15 includes a second input terminal 15a, a second input side coil 15b, a second switch element 15c, a second filter capacitor 15d, a second filter coil 15e, a third diode 15f, a second output side capacitor 15g, a second output terminal 15h, and a second voltage detector 15i.

[0042] The second input terminal 15a receives the power generated by the power generating element 3 and the output power of the first DC / DC converter 14. Specifically, the power generating element 3 is connected to the second input terminal 15a via a first diode 20. In addition, the first output terminal 14i of the first DC / DC converter 14 is connected to the second input terminal 15a. Currents from the power generating element 3 and the first output terminal 14i of the first DC / DC converter 14 join and flow into the second input terminal 15a.

[0043] One end of the second input coil 15b is connected to the second input terminal 15a.

[0044] One end of the second switch element 15c is connected to the other end of the second input coil 15b, and the other end of the second switch element 15c is grounded.

[0045] One end of the second filter capacitor 15d is connected to the one end of the second switch element 15c.

[0046] One end of the second filter coil 15e is connected to the other end of the second filter capacitor 15d, and the other end of the second filter coil 15e is grounded.

[0047] The anode of the third diode 15f is connected to the other end of the second filter capacitor 15d and to the one end of the second filter coil 15e.

[0048] One end of the second output-side capacitor 15g is connected to the cathode of the third diode 15f, and the other end of the second output-side capacitor 15g is grounded.

[0049] The second output terminal 15h is connected to the one end of the second output side capacitor 15g and the load 4.

[0050] The second voltage detector 15 i detects the voltage at the second output terminal 15 h , that is, the output voltage of the second DC / DC converter 15 .

[0051] The third DC / DC converter 16 supplies charging power to the battery 13 by using the power generated by the power generating element 3. The third DC / DC converter 16 includes a third input terminal 16a, a third input side capacitor 16b, a third input side coil 16c, a third switch element 16d, a third filter capacitor 16e, a third filter coil 16f, a fourth diode 16g, a third output side capacitor 16h, a first current detector 16i, a third voltage detector 16j, a fourth output side capacitor 16k, and a third output terminal 16m.

[0052] The third input terminal 16a receives the power generated by the power generating element 3. Specifically, the power generating element 3 is connected to the third input terminal 16a via a first diode 20.

[0053] One end of the third input side capacitor 16b is connected to the third input terminal 16a, and the other end of the third input side capacitor 16b is grounded.

[0054] One end of the third input coil 16c is connected to the third input terminal 16a.

[0055] One end of the third switch element 16d is connected to the other end of the third input coil 16c, and the other end of the third switch element 16d is grounded.

[0056] One end of the third filter capacitor 16e is connected to one end of the third switch element 16d and the other end of the third input coil 16c.

[0057] One end of the third filter coil 16f is connected to the other end of the third filter capacitor 16e, and the other end of the third filter coil 16f is grounded.

[0058] The anode of the fourth diode 16g is connected to the other end of the third filter capacitor 16e and to the one end of the third filter coil 16f.

[0059] One end of the third output-side capacitor 16h is connected to the cathode of the fourth diode 16g, and the other end of the third output-side capacitor 16h is grounded.

[0060] The first current detector 16 i detects the charging current flowing from the third DC / DC converter 16 to the battery 13 .

[0061] The third voltage detector 16 j detects the output voltage of the third DC / DC converter 16 .

[0062] One end of the fourth output side capacitor 16k is connected to one end of the third output side capacitor 16h, and the other end of the fourth output side capacitor 16k is grounded.

[0063] The third output terminal 16m is connected to one end of a fourth output-side capacitor 16k.

[0064] The control unit 30 includes first to third control ICs (integrated circuits) 31 to 33 and a microcomputer .

[0065] The first control IC 31 controls the first switch element 14d of the first DC / DC converter 14 based on the detection value of the first voltage detector 14j, i.e., the output voltage of the first DC / DC converter 14, so as to set the output voltage to a predetermined first target value. The first control IC 31 also sets the first target value in response to an MPPT control signal output by the microcomputer 34.

[0066] The MPPT control signal is adjusted by the microcomputer 34 so that the product of the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12 is maximized. Therefore, the first control IC 31 can maximize the product of the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12 by controlling the first switch element 14d of the first DC / DC converter 14 with reference to this MPPT control signal.

[0067] The second control IC 32 controls the second switch element 15c of the second DC / DC converter 15 based on the detection value of the second voltage detector 15i, i.e., the output voltage of the second DC / DC converter 15, so as to set the output voltage to a predetermined second target value.

[0068] The third control IC 33 refers to the charging current variable signal output by the microcomputer 34, and controls the third switch element 16d based on the detection value of the first current detector 16i and the detection value of the third voltage detector 16j.

[0069] The charging current variable signal is adjusted by the microcomputer 34 so that the product of the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12 is maximized within a range in which the charging current value does not exceed the upper limit. Therefore, the third control IC 33 can maximize the product of the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12 within a range in which the charging current value does not exceed the upper limit by controlling the third switch element 16d with reference to this charging current variable signal.

[0070] The detailed control operation of the control unit 30 will be described later.

[0071] The first diode 20 regulates current flow from the first output terminal 14i of the first DC / DC converter 14, the second input terminal 15a of the second DC / DC converter 15, and the third input terminal 16a of the third DC / DC converter 16 to the power generation element 3.

[0072] FIG. 3 is a flowchart illustrating the operation of power supply system 1 configured as described above.

[0073] First, in S101, the first DC / DC converter 14 is started up with a predetermined first target value set as an initial value. The first control IC 31 controls the output voltage V BUS The first switch element 14d is controlled so that the first target value becomes the initial value of the first target value.

[0074] Next, in S102, the power generating element 3 starts generating power.

[0075] Next, in S103, the second DC / DC converter 15 is started up.

[0076] Next, in S104, the control unit 30 detects the detection value of the first voltage detector 14j, i.e., the output voltage V BUS is the detection value V of the voltage detection unit 12. IN Then, it is determined whether the output voltage V of the first DC / DC converter 14 is greater than the output voltage V of the power generating element 3. BUSis the detection value V of the voltage detection unit 12. IN On the other hand, if the output voltage V of the first DC / DC converter 14 is larger than BUS is the detection value V of the voltage detection unit 12. IN If it is equal to or less than this, the control unit 30 proceeds to the process of S106.

[0077] In S105, the control unit 30 controls the output voltage V BUS In the subsequent steps S107 to S114, the control unit 30 controls the output power P IN The output voltage V of the first DC / DC converter 14 is set to be maximum. BUS Adjust.

[0078] In S106, the control unit 30 detects the detection value of the first voltage detector 14j, i.e., the output voltage V BUS is the detection value V of the voltage detection unit 12. IN Then, it is determined whether the output voltage V BUS is the detection value V of the voltage detection unit 12. IN If the output voltage V of the first DC / DC converter 14 is equal to V, the control unit 30 proceeds to step S107. BUS is the detection value V of the voltage detection unit 12. IN If it is not equal to, the control unit 30 proceeds to the process of S109.

[0079] In S107, the control unit 30 detects the current detection value of the current detection unit 11 and the voltage detection value V IN Based on this, the maximum output power P of the power generating element 3 IN(max) and the maximum output voltage V of the power generating element 3 IN(max) Specifically, the control unit 30 calculates the output voltage V BUS By changing V BUS The detection value V of the current detection unit 11 and the detection value V of the voltage detection unit 12 before the change IN And, V BUS The detected value V of the current detection unit 11 and the detected value V of the voltage detection unit 12 after the changeIN As a result, the maximum output power P IN(max) and the output power of power generating element 3 is the maximum output power P IN(max) The detection value V of the voltage detection unit 12 when IN For example, first, the control unit 30 calculates V BUS The current value of the current detection unit 11 and the voltage value of the voltage detection unit 12 before the change, and V BUS A power curve such as graphs G1 and G2 shown in Fig. 5 can be identified based on the current value of the current detection unit 11 and the voltage value of the voltage detection unit 12 after the change. The graph showing the relationship between the output voltage and output power of the power generation element 3 changes depending on the environment (ambient temperature, etc.). For example, when a thermoelectric element is used as the power generation element 3, the graph showing the relationship between the output voltage and output power of the power generation element 3 changes depending on the ambient temperature. In Fig. 5, Voc is the open circuit voltage. The control unit 30 then determines the power value at the apex of the identified graph as the maximum output power P of the power generation element 3. IN(max) The voltage value at the apex can be determined as the maximum output voltage V IN(max) It can be identified as:

[0080] Next, in S108, the control unit 30 calculates the output power P IN is the total power consumption P S Here, the power consumption in the power supply system 1 also includes the power loss in the second DC / DC converter 15. IN is the total power consumption P S If the output power P IN is the total power consumption P S If it is less than the limit, the control unit 30 proceeds to the process of S110.

[0081] In S109, the control unit 30 controls the output voltage V BUS is the detection value V of the voltage detection unit 12. IN The first target value is set to be, for example, 1 V lower than the first target value, and the process proceeds to S116.

[0082] In S110, the control unit 30 calculates the current output power P IN(Z) is the output voltage V of the first DC / DC converter 14. BUS The output power P of the power generating element 3 after the voltage is reduced by a predetermined amount IN(Z+1) It is determined whether the output voltage V of the first DC / DC converter 14 is smaller than BUS The output power P of the power generating element 3 after the change IN(Z+1) can be estimated based on the graph specified in S107 (for example, graphs G1 and G2 in FIG. 5). IN(Z) is the output power P IN(Z+1) If the output power P IN(Z) is the output power P IN(Z+1) If it is not smaller than , the control unit 30 proceeds to the process of S112.

[0083] In S111, the control unit 30 reduces the first target value by a predetermined value to thereby reduce the output voltage V BUS Then, the control unit 30 returns to the process of S108.

[0084] In S112, the control unit 30 calculates the current output power P IN(Z) is the output voltage V of the first DC / DC converter 14. BUS The output power P of the power generating element 3 after the voltage is reduced by a predetermined amount IN(Z+1) It is judged whether the output power P IN(Z) is the output power P IN(Z+1) If the output power P IN(Z) is the output power P IN(Z+1) If it is not greater than , the control unit 30 proceeds to the process of S114.

[0085] In S113, the control unit 30 increases the first target value by a predetermined value to thereby increase the output voltage V BUS Then, the control unit 30 returns to the process of S108.

[0086] In S114, the control unit 30 maintains the first target value to control the output voltage V BUS maintain.

[0087] Next, in S115, the control unit 30 detects the detection value V IN Or the output power P of the power generating element 3 IN The voltage detection unit 12 detects the voltage V IN Or the output power P of the power generating element 3 IN When the value changes, the process returns to S104.

[0088] In S116, the control unit 30 calculates the output power P IN is the total power consumption P S It is determined whether the output power P of the power generating element 3 is greater than IN is the total power consumption P S If the output power P IN is the total power consumption P S If it is equal to or less than this, the process proceeds to S104.

[0089] In S117, the power supply system 1 executes the charging mode operation.

[0090] Hereinafter, the operation of the charging mode performed by the power supply system 1 will be described with reference to FIG.

[0091] First, in S201, the third control IC 33 starts charging the battery 13 using the power generated by the power generating element 3 by controlling the third switch element 16d of the third DC / DC converter 16.

[0092] Next, in S202, the control unit 30 detects the detection value of the current detection unit 11 and the detection value V of the voltage detection unit 12 in the same manner as in S107. IN Based on this, the maximum output power P of the power generating element 3 IN(max) and the maximum output voltage V of the power generating element 3 IN(max) Calculate.

[0093] Next, in S203, the control unit 30 calculates the current output power P IN(Z) However, the output power P of the power generating element 3 after the charging current of the third DC / DC converter 16 is increased by a predetermined amount IN(Z+1) It is judged whether the output power P IN(Z) is the output power P IN(Z+1) If the output power P IN(Z) is the output power P IN(Z+1) If it is not smaller than , the control unit 30 proceeds to the process of S205.

[0094] In S204, the control unit 30 controls the charging current I CHG is the predetermined maximum current I CHG(MAX) It is determined whether the charging current I CHG is the predetermined maximum current I CHG(MAX) If the charging current I CHG is the predetermined maximum current I CHG(MAX) If so, the control unit 30 proceeds to the process of S208.

[0095] In S205, the control unit 30 controls the third switch element 16d of the third DC / DC converter 16 to reduce the charging current or to stop charging.

[0096] In S206, the control unit 30 controls the third switch element 16d of the third DC / DC converter 16 to increase the charging current.

[0097] In S207, the control unit 30 determines whether or not the battery 13 is fully charged. If the battery 13 is fully charged, the control unit 30 proceeds to the process of S210, whereas if the battery 13 is not fully charged, the control unit 30 returns to the process of S202.

[0098] In S208, the control unit 30 sets the charging current to the maximum current I CHG(MAX)The value is kept unchanged and the process proceeds to S209.

[0099] In S209, the control unit 30 determines whether or not the battery 13 is fully charged. If the battery 13 is fully charged, the control unit 30 proceeds to the process of S210. On the other hand, if the battery 13 is not fully charged, the control unit 30 proceeds to the process of S211.

[0100] In S210, the control unit 30 controls the third switch element 16d of the third DC / DC converter 16 to stop charging the battery 13.

[0101] In S211, the control unit 30 detects the detection value V IN Or the output power P of the power generating element 3 IN The voltage detection unit 12 detects the voltage V IN Or the output power P of the power generating element 3 IN When the value changes, the process returns to S202.

[0102] In the power supply system 1 configured as described above, as shown in graphs G1 and G2 of FIG. 5, the maximum output power P IN(max) However, the total power consumption P S If the total power consumption is P S This can be fully achieved by the power generating element 3 alone. Therefore, there is no need to consume the power of the battery 13.

[0103] In addition, as shown in graph G2, the output power P IN is the total power consumption P S If the charging power P CHG For example, the third DC / DC converter 16 is controlled so that the output voltage of the power generating element 3 and the output voltage V of the first DC / DC converter 14 are maximized. BUSThe relationship between the charging current I CHG By increasing the value of the power generation element 3, the power generation and charging power P CHG Therefore, the power generated by the power generating element 3 can be effectively utilized, and the battery 13 can be efficiently charged.

[0104] On the other hand, the maximum output power P IN(max) However, the total power consumption P S If the power is less than the required power, the shortage of power is supplied by the first DC / DC converter 14. In this case, the control unit 30 controls the output voltage V BUS For example, change the voltage to the apex of graph G3 in FIG. 6, and the power generating element 3 will output the maximum output power P IN(max) This allows the power of the power generating element 3 to be used effectively. For example, the output voltage V BUS 6 from point A to point B on the graph G3, the power of the power generating element 3 can be used effectively. In this way, based on the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12, the control unit 30 determines whether the product of the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12 is the maximum output power P IN(max) The first DC / DC converter 14 can be controlled so as to satisfy the following: As a result, the control unit 30 can maximize the power generated by the power generating element 3, so that the voltage applied to the load 4 can be stabilized and the power consumption of the battery 13 can be suppressed.

[0105] Therefore, according to the first embodiment, the output of the first DC / DC converter 14 is connected to the input side of the second DC / DC converter 15, which makes it easier for the control unit 30 to control and stabilize the output voltage of the second DC / DC converter 15 compared to the case where the output of the first DC / DC converter 14 is connected to the output of the second DC / DC converter 15. Therefore, the power supplied to the load 4, which is output by the second DC / DC converter 15, can be stabilized.

[0106] In addition, the control unit 30 controls the first DC / DC converter 14 based on the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12, so that the power supplied from the battery 13 to the load 4 can be adjusted according to the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12, that is, according to the power generated by the power generation element 3.

[0107] Furthermore, the control unit 30 can adjust the charging power supplied to the battery 13 according to the detection value of the current detection unit 11 and the detection value of the voltage detection unit 12, that is, according to the power generated by the power generating element 3.

[0108] <Embodiment 2> Fig. 7 is a diagram corresponding to Fig. 1 of the second embodiment, and Fig. 8 is a diagram corresponding to Fig. 2 of the second embodiment. The power supply system 1 according to the second embodiment includes a bidirectional DC / DC converter 21 instead of the first and third DC / DC converters 14, 16 of the first embodiment. Moreover, the control unit 30 includes a control microcomputer (microcomputer) 35 instead of the first control IC 31 and the third control IC 33.

[0109] The bidirectional DC / DC converter 21 can operate in a discharge mode in which discharge power output by the battery 13 is input, and in a charge mode in which charging power is supplied to the battery 13 using power generated by the power generation element 3. The bidirectional DC / DC converter 21 includes a power generation element side terminal 21a, a power generation element side capacitor 21b, a fourth switch element 21c, a fourth filter coil 21d, a fourth filter capacitor 21e, a fifth switch element 21f, a battery side coil 21g, a first battery side capacitor 21h, a second current detector 21i, a fourth voltage detector 21j, a fifth voltage detector 21k, a second battery side capacitor 21m, and a battery side terminal 21n.

[0110] The power generating element 3 is connected to the power generating element side terminal 21a via a first diode 20.

[0111] One end of the power generation element side capacitor 21b is connected to the power generation element side terminal 21a, and the other end of the power generation element side capacitor 21b is grounded.

[0112] One end of the fourth switch element 21c is connected to the power generation element side terminal 21a.

[0113] One end of the fourth filter coil 21d is connected to the other end of the fourth switch element 21c, and the other end of the fourth filter coil 21d is grounded.

[0114] One end of the fourth filter capacitor 21e is connected to the one end of the fourth filter coil 21d.

[0115] One end of the fifth switch element 21f is connected to the other end of the fourth filter capacitor 21e, and the other end of the fifth switch element 21f is grounded.

[0116] One end of the battery side coil 21g is connected to the one end of the fifth switch element 21f and the other end of the fourth filter capacitor 21e.

[0117] One end of the first battery-side capacitor 21h is connected to the other end of the battery-side coil 21g, and the other end of the first battery-side capacitor 21h is grounded.

[0118] The second current detector 21 i detects the charging current flowing from the bidirectional DC / DC converter 21 to the battery 13 .

[0119] The fourth voltage detector 21j detects the output voltage to the power generation element side terminal 21a of the bidirectional DC / DC converter 21.

[0120] The fifth voltage detector 21k detects the output voltage of the bidirectional DC / DC converter 21 to the battery side terminal 21n.

[0121] One end of the second battery side capacitor 21m is connected to the one end of the first battery side capacitor 21h, and the other end of the second battery side capacitor 21m is grounded.

[0122] The battery side terminal 21n is connected to the one end of the second battery side capacitor 21m and to the battery 13.

[0123] The control microcomputer 35 controls the fourth and fifth switch elements 21c, 21f so as to set the output voltage to a predetermined first target value based on the detection value of the fourth voltage detector 21j, i.e., the output voltage to the power generation element side terminal 21a of the bidirectional DC / DC converter 21. The control microcomputer 35 also sets the first target value based on the MPPT control signal output by the microcomputer 34.

[0124] In addition, the control microcomputer 35 refers to the charging current variable signal output by the microcomputer 34, and controls the fourth and fifth switch elements 21c, 21f based on the detection value of the second current detector 21i and the detection value of the fifth voltage detector 21k.

[0125] The bidirectional DC / DC converter 21 fulfills the functions of the first and third DC / DC converters 14, 16 of embodiment 1. At this time, the control microcomputer 35 fulfills the functions of the first and third control ICs 31, 33 of embodiment 1. The control microcomputer 35 refers to the detection value of the fourth voltage detector 21j instead of the detection value of the first voltage detector 14j of embodiment 1, refers to the detection value of the second current detector 21i instead of the detection value of the first current detector 16i of embodiment 1, and refers to the detection value of the fifth voltage detector 21k instead of the detection value of the third voltage detector 16j of embodiment 1.

[0126] The other configurations and operations are the same as those of the first embodiment, so the same components are given the same reference numerals and detailed descriptions thereof are omitted. [Industrial Applicability]

[0127] INDUSTRIAL APPLICABILITY The present disclosure is useful as a power supply system that supplies power to a load by using generated power output by a power generation element having an internal resistance. [Explanation of symbols]

[0128] 1 Power System 3 Power generating element 4. Load 11 Current detection section 12 Voltage detection section 13 Battery 14 First DC / DC Converter 15 Second DC / DC Converter 16 The third DC / DC converter 21 Bidirectional DC / DC converter (first DC / DC converter) 30 Control section 31 Internal Resistance I CHG charging current I CHG(MAX) maximum current V BUS Output Voltage P IN Output power (power generation) V IN Detection Value P IN(max) Maximum Output Power

Claims

1. A power supply system that supplies power to a load using power generated by a power generation element having an internal resistance, A battery; a first DC / DC converter to which discharge power outputted by the battery is input; a second DC / DC converter that outputs the supply power using the generated power and the output power of the first DC / DC converter; a third DC / DC converter that uses the generated power to supply charging power to the battery; a control unit that controls the first DC / DC converter based on an output voltage of the first DC / DC converter, and that controls the second DC / DC converter based on an output voltage of the second DC / DC converter.

2. A power supply system that supplies power to a load using power generated by a power generation element having an internal resistance, A battery; a first DC / DC converter operable in a discharge mode in which discharge power output by the battery is input, and in a charge mode in which charging power is supplied to the battery using the generated power; a second DC / DC converter that outputs the supply power using the generated power and the output power of the first DC / DC converter; a control unit that controls the first DC / DC converter based on an output voltage of the first DC / DC converter, and that controls the second DC / DC converter based on an output voltage of the second DC / DC converter.

3. 3. The power supply system according to claim 1, A current detection unit that detects an output current of the power generating element; Further comprising a voltage detection unit that detects an output voltage of the power generation element, The power supply system according to claim 1, wherein the control unit controls the first DC / DC converter based on a detection value of the current detection unit and a detection value of the voltage detection unit.

4. 4. The power supply system according to claim 3, The control unit controls the first DC / DC converter so that the product of the detection value of the current detection unit and the detection value of the voltage detection unit becomes the maximum output power of the power generation element.

5. 2. The power supply system according to claim 1, A current detection unit that detects an output current of the power generating element; Further comprising a voltage detection unit that detects an output voltage of the power generation element, The power supply system according to claim 1, wherein the control unit controls the third DC / DC converter based on a detection value of the current detection unit and a detection value of the voltage detection unit.

6. 6. The power supply system according to claim 5, a control unit that controls the third DC / DC converter based on a detection value of the current detection unit and a detection value of the voltage detection unit so as to maximize the charging power.

7. 3. The power supply system according to claim 2, A current detection unit that detects an output current of the power generating element; Further comprising a voltage detection unit that detects an output voltage of the power generation element, a control unit that controls the first DC / DC converter based on a detection value of the current detection unit and a detection value of the voltage detection unit so as to maximize the charging power.

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