JP2005310740A - Power supply system of fuel cell, electronic device, and power supplying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply system of a fuel cell capable of effectively taking out output power from the fuel cell and a secondary battery, and provide an electronic device and a power supplying method. <P>SOLUTION: The power supply system comprises a voltage conversion circuit 130 and a rectifier circuit 150, and constructed so as to generate a voltage 134 for switching by converting output voltage of the fuel cell with a set voltage 115, which is an output voltage corresponding to the maximum output power of the fuel cell 110, as a standard, and output at least either the voltage for switching or an output voltage 121 of the secondary battery 120 through the rectifier circuit. By the above, the fuel cell and the secondary battery can be operated simultaneously in a state of utilizing the output power of the fuel cell to the maximum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a fuel cell and a secondary battery, a power supply system for a fuel cell that supplements the output power of the fuel cell with the secondary battery and supplies power to a load portion, and the power supply system for the fuel cell. The present invention relates to an electronic device and a power supply method in the fuel cell power supply system.

  Portable electronic devices such as mobile phones, portable information terminals, notebook personal computers, portable audio devices, and portable visual devices are becoming popular. Conventionally, such portable electronic devices are driven by a primary battery or a secondary battery. The primary battery is disposable, and the secondary battery can be reused, but needs to be charged after using a certain amount of power, and thus requires a charging device and a charging time. As the secondary battery, a nickel cadmium battery or a lithium ion battery is used, and a small battery having a high energy density has been developed. However, a secondary battery that can be continuously driven for a longer time is desired.

In order to meet this demand, fuel cells that do not require charging have been proposed. A fuel cell is a generator that electrochemically converts chemical energy of fuel into energy. Among fuel cells, a polymer electrolyte fuel cell (PEFC) that uses a perfluorocarbon sulfonic acid-based electrolyte to reduce hydrogen gas at the anode electrode and reduce oxygen at the cathode electrode to generate electricity is a battery with high output density And is being developed for automobiles.
However, in a polymer electrolyte fuel cell, hydrogen gas has a low volumetric energy density, and it is necessary to increase the volume of the fuel tank, as well as a device for supplying fuel gas and oxidizing gas to a power generator, and battery performance. Since an auxiliary device such as a humidifier for stabilization is necessary, the power generator becomes large, and the polymer electrolyte fuel cell is not suitable as a power source for portable equipment. Therefore, development of a direct methanol fuel cell (DMFC) that generates electricity by directly extracting protons from methanol is also in progress.

Although the DMFC has a disadvantage that the output is smaller than that of the PEFC, the volume energy density of the fuel can be increased, and the auxiliary equipment of the power generation device can be reduced, so that the size can be reduced. There are advantages, attracting attention as a power source for portable devices, and several proposals have been made.
The direct methanol fuel cell generates power by a reaction such as the following equation.
Anode electrode CH ₃ OH + H ₂ O → 6H ⁺ + 6e ⁻ + CO ₂
Cathode 6H ⁺ + 6e ⁻ + 3 / 2O ₂ → 3H ₂ O
That is, at the anode electrode, methanol and water react in a catalytic reaction containing platinum and ruthenium to generate hydrogen ions, electrons, and carbon dioxide. The electrons are output from the anode electrode as electric power, and the hydrogen ions are ionized. Conducts through the permeable membrane to the cathode side. At the cathode electrode, hydrogen ions receive supply of electrons from the cathode electrode, and react with oxygen in the air to generate water. At this time, the temperature of the power generation unit is as high as the characteristics of the ion exchange membrane permit, that is, the temperature in the range of 60 ° C. to 80 ° C. and high humidity, and the efficiency of the DMFC is good.

However, in the current DMFC, the theoretical electromotive force, which is an ideal output, cannot be obtained due to resistance elements caused by various losses (polarization) generated inside the fuel cell, and the output is lower than the theoretical electromotive force. ing. The loss due to polarization is a loss caused by resistance polarization that is a resistance component that hinders the flow of ions and electrons in the electrolyte, loss due to activation polarization consumed by activation energy in an electrochemical reaction, and chemical reaction. There is a loss due to what is called diffusion polarization, which is consumed when the reactants and reaction products that occur continuously diffuse and move by themselves.
These polarizations occur at the anode and cathode, and material development is underway to solve these problems. Although it has been improved, for example, even if the ideal electromotive force of DMFC is 1.21V and the theoretical efficiency is 97%, it is actually about 0.3V because of the internal voltage drop at the practical level. is there.

Therefore, the VI characteristic of the output voltage with respect to the load current of the fuel cell itself is largely dependent on the load current, while other secondary batteries and primary batteries have a substantially constant and stable output with respect to the load current. Has drooping characteristics. That is, when a large load current is taken out, there is a characteristic that the output voltage decreases due to the internal resistance of the fuel cell. Therefore, in the fuel cell, there is generally an optimum current that can extract the maximum power.
Further, as a feature of the fuel cell, a system that uses an auxiliary device such as a pump for supplying fuel, circulating air, and the like is realistic, and stable operation and end operation can be performed. On the other hand, at the time of start-up, there is a disadvantage that power generation does not start unless air and fuel are supplied to the battery cells. Once power generation is started, it is possible to supply power to the auxiliary equipment such as the pump with its own generated power, but at the start-up or at the end of work, there is another auxiliary power source, generally a rechargeable secondary battery. is necessary.
Examples of the parallel operation of the second power source and the fuel cell are disclosed in the following Patent Documents 1 and 2, both of which are intended for stable power supply, and have the maximum power generation capacity in the fuel cell. It is not a structure to pull out.
JP 59-230434 A Japanese Patent Laid-Open No. 3-40729

When the fuel cell and the secondary battery are operated in parallel with respect to the load, the output of the fuel cell capable of continuous operation is taken out to the maximum, and the shortage is output from the secondary battery. When there is a surplus power, a system for charging the secondary battery is effective. For example, in mobile notebook personal computers, the power for normal CPU operation, hard disk drive, and screen display is equivalent to constant power, and is supplied from the fuel cell. A configuration is considered in which a shortage is output from the secondary battery when power other than the normal power to the external device when connected and operated is required.
However, in a fuel cell, when an excessive load current is output even instantaneously during operation, the electrolyte membrane and the electrode assembly (MEA) are damaged, and a sudden voltage drop occurs above a certain load current. In this case, even if the load is reduced, the fuel cell has a characteristic that it does not recover the initial output and is destroyed. Therefore, in the fuel cell, even if the output current is taken out more than the optimum load current, the output voltage is lowered and the power exceeding the maximum power cannot be taken out. If this point is taken into consideration and the fuel cell is designed with a sufficient output characteristic, the shape becomes excessively large and hinders reduction in size and weight.
Further, in a lithium ion secondary battery, the capacity that can be output from the battery is constant even when a large amount of power is taken out. However, the battery life is shortened. Even in a lithium ion battery, if the discharge capacity is sufficiently exhausted, the output voltage also drops to a voltage called a discharge end voltage. For example, over discharge at 2.3 V or less is prohibited due to material characteristics with respect to the maximum charging voltage of 4.3 V per cell, and the operating voltage on the device side is in the range of 4.2 to 3.0 V. .

Therefore, as disclosed in the above Japanese Patent Application Laid-Open No. 59-230434, the method of adding the output of the fuel cell and the output of the lithium secondary battery via the diode is caused by the voltage drop caused by the discharge of the lithium battery. Thus, the reference voltage for switching between the fuel cell and the lithium battery varies. Therefore, the fuel cell outputs at an unexpected low voltage, and the invention of the above publication may cause destruction of the fuel cell as described above.
The present invention has been made to solve the above-described problems, and is provided with a fuel cell power supply system that is small in size and can efficiently extract output power from a fuel cell and a secondary battery, and the fuel cell power supply system. It is an object of the present invention to provide an electronic device and a power supply method in the fuel cell power supply system.

In order to achieve the above object, the present invention is configured as follows.
That is, according to the fuel cell power supply system of the first aspect of the present invention, the fuel cell that generates power and supplies power to the load section;
A secondary battery that complements the output power of the fuel cell and supplies power to the load unit;
A switching voltage that is connected between the output side of the fuel cell and the load unit and is used to determine that power is supplied from at least one of the fuel cell and the secondary battery to the load unit. In order to set, a voltage conversion circuit that converts the output voltage of the fuel cell with the set voltage as a reference to set the switching voltage, and
Connected between the output side of the voltage conversion circuit and the output side of the secondary battery and the load section, and the switching voltage corresponding to the output voltage of the voltage conversion circuit exceeds the output voltage of the secondary battery. Sometimes power is supplied from the fuel cell to the load section through the voltage conversion circuit, and when the switching voltage is equal to the output voltage of the secondary battery, from the secondary battery and from the fuel cell through the voltage conversion circuit. A rectifier circuit that supplies power to the load unit in parallel, and supplies power from the secondary battery to the load unit when the switching voltage is less than the output voltage of the secondary battery;
It is provided with.

The fuel cell power supply system includes a fuel cell and a secondary battery, and supplies power from at least one of the fuel cell to the load portion. The fuel cell power is obtained by utilizing the VI characteristic peculiar to the fuel cell. It is a power supply system that can draw out the maximum. That is, the fuel cell has a large internal resistance compared to other types of cells, and the VI characteristic is a drooping characteristic in which the output voltage decreases as the load increases. Since the fuel cell having such characteristics and the secondary battery that outputs a relatively constant voltage with respect to load fluctuations are operated in parallel, the output voltage of the secondary battery corresponds to the drooping characteristic of the fuel cell. The voltage at the output voltage change portion (droop voltage) is set, and the fuel cell and the secondary battery are connected in parallel via the rectifier circuit to supply power. In addition, the switching voltage used for determining whether to supply power from at least one of the fuel cell and the secondary battery to the load in order to take out the output of the fuel cell mainly is the maximum output power of the fuel cell. The output voltage of the fuel cell is converted and set based on the output voltage of the corresponding fuel cell.
In addition, as a secondary battery, a lithium ion battery, a nickel cadmium battery, a lead acid battery etc. can be used, for example.

  The fuel cell power supply system particularly includes a voltage conversion circuit and a rectification circuit. In the voltage conversion circuit, a switching voltage used to determine that power is supplied from at least one of the fuel cell and the secondary battery to the load unit is set. The switching voltage is an output voltage of the fuel cell. It is set by conversion and is almost constant. The rectifier circuit compares the switching voltage with the output voltage of the secondary battery, and acts to supply power to the load unit from the higher voltage output. Therefore, unlike the conventional case, it is possible to prevent the reference voltage that determines which of the fuel cell and the secondary battery supplies power to the load unit from fluctuating due to the voltage drop of the output voltage of the secondary battery.

  The voltage conversion circuit includes a voltage detection unit, a voltage setting unit, and a feedback unit. The voltage detection unit detects the output voltage of the fuel cell. When the output voltage exceeds the set voltage, the voltage setting unit and the feedback unit set the fuel cell to a voltage exceeding the maximum output voltage of the secondary battery. The output voltage is converted to set the switching voltage. On the other hand, when the voltage detection unit detects that the output voltage of the fuel cell has become equal to or lower than the set voltage, the feedback unit stops the output from the voltage setting unit. During the period from when the output voltage of the fuel cell becomes equal to or lower than the set voltage due to the output stop until the breakdown voltage of the fuel cell is reached, the output voltage of the voltage conversion circuit is equal to or lower than the discharge end voltage of the secondary battery. Will be lowered. The voltage conversion circuit has such a voltage drooping characteristic.

  Furthermore, the fuel cell power supply system can include a charging circuit for charging the secondary battery. The charging circuit includes an output voltage comparison circuit and a charge switching circuit. The output voltage comparison circuit compares the output voltage of the fuel cell with the set voltage, and compares the output voltage of the secondary battery with the chargeable voltage of the secondary battery. The charge switching circuit is provided only when the output voltage comparison circuit detects that the output voltage of the fuel cell exceeds the set voltage and the output voltage of the secondary battery is less than or equal to a chargeable voltage. Is applied to the secondary battery to charge the secondary battery.

  In addition, after the charging switching circuit starts charging the secondary battery, the output voltage comparison circuit further detects a charging stop voltage that is an arbitrary voltage value less than the set voltage. When the output voltage comparison circuit detects the charge stop voltage, the charge switching circuit stops charging the secondary battery.

  Further, the fuel cell power supply system may include an output stop circuit. The output stop circuit is connected between the output side of the secondary battery and the load section, and indicates that the output voltage of the secondary battery has dropped to a load stop voltage slightly exceeding the discharge end voltage in the secondary battery. To detect. The output stop circuit stops the output from the secondary battery to the load unit when the load stop voltage is detected.

  The electronic device according to the second aspect of the present invention includes the fuel cell power supply system according to the first aspect and a load unit that receives power supply from the fuel cell power supply system.

According to the fuel cell power supply system of the third aspect of the present invention, a fuel cell for generating the first power,
A secondary battery that generates second power;
The output voltage level of the fuel cell is connected to the output of the fuel cell, the first specified value and the second specified value are compared, and the fuel cell output voltage level is less than the first specified value. A fuel cell controller that stops power generation of the fuel cell and determines output power of the fuel cell and the secondary battery based on a comparison between the fuel cell output voltage level and the second specified value;
It is provided with.

  According to the fuel cell power supply system in the first aspect described above, the fuel cell power supply system includes the voltage conversion circuit and the rectifier circuit, so that the set voltage that is the output voltage corresponding to the maximum output power of the fuel cell is used as a reference. The output voltage of the fuel cell is converted to generate a switching voltage, and at least one of the switching voltage and the output voltage of the secondary battery is output through the rectifier circuit. Therefore, the fuel cell and the secondary battery can be operated in parallel in a state where the power of the fuel cell is utilized to the maximum, and the output power can be efficiently extracted from the fuel cell and the secondary battery.

  In addition, since the voltage conversion circuit and the rectifier circuit are provided, the voltage that determines which of the fuel cell and the secondary battery supplies power to the load portion is reduced to the voltage drop of the output voltage of the secondary battery as in the past. It is possible to prevent a state of fluctuation due to the cause. Further, according to this configuration, the fuel cell does not output at an unexpected low voltage, and the fuel cell is not destroyed. Further, the voltage detection unit, the voltage setting unit, and the feedback unit included in the voltage conversion circuit forcibly adjust the output voltage of the voltage conversion circuit when the output voltage of the fuel cell becomes equal to or lower than the set voltage. The voltage conversion circuit has a drooping characteristic for dropping. Therefore, the fuel cell does not output at a low voltage, and it can be prevented that the fuel cell is destroyed.

  In addition, since the voltage conversion circuit and the rectifier circuit are provided, the output power can be efficiently taken out from the fuel cell and the secondary battery, and since it has the drooping characteristic, the power system for the fuel cell is a fuel cell. Since it is not necessary to take a large design margin in the case, the size can be reduced.

  Furthermore, by providing the charging circuit, the secondary battery can be charged when the above-described effects are achieved and the output of the fuel cell has a margin. In addition, since the charging circuit includes the output voltage comparison circuit and the charge switching circuit, the charging can be performed only when the output power of the fuel cell has a margin and the secondary battery has a chargeable voltage. Therefore, the secondary battery can be charged without imposing a burden on the power supply to the load unit.

  Further, the output voltage comparison circuit detects the charge stop voltage, so that the secondary battery can be prevented from changing from the charged state to the output state at a stretch, and the burden on the secondary battery can be reduced.

  Furthermore, by providing an output stop circuit, if the output voltage of the secondary battery drops to near the load stop voltage, the output from the secondary battery to the load section is stopped, so the secondary battery is damaged. Can be prevented.

  According to the electronic device of the second aspect described above, since the fuel cell power supply system having the above-described effects is provided, stable power supply can be performed, and the entire device can be made compact.

  A power supply system for a fuel cell according to an embodiment of the present invention, an electronic device including the power supply system for a fuel cell, and a power supply method in the power supply system for the fuel cell will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected about the same component.

1st Embodiment;
As an example of the fuel cell power supply system, in the fuel cell power supply system 101 shown in FIG. 1, a fuel cell 110 that generates power using hydrogen and oxygen and supplies power to the load unit 210, and output power of the fuel cell 110 The secondary battery 120 that supplies power to the load unit 210, the voltage conversion circuit 130 connected between the output side of the fuel cell 110 and the secondary battery 120, the output side of the voltage conversion circuit 130, and 2 A rectifier circuit 150 connected between the output side of the secondary battery 120 and a load unit 210 is provided. The voltage conversion circuit 130 and the rectifier circuit 150 correspond to the fuel cell controller.
The fuel cell power supply system 101 and the load unit 210 can constitute an electronic device 201, for example, a notebook personal computer as shown in FIG. In this case, the personal computer main body includes a secondary battery 120, a voltage conversion circuit 130, a rectifier circuit 150, and a load unit 210, and the fuel cell 110 can be configured to be detachable from the personal computer main body.

Here, the fuel cell 110 is of the above-described DMFC type, and a membrane electrode assembly (MEA) is formed by sandwiching an ion conductive membrane between a pair of anode electrode and cathode electrode. In the present embodiment, the fuel cell 110 is configured by connecting 30 power generation cells having the membrane electrode assembly in series. The theoretical voltage of one power generation cell is 1.21V, but in reality, the voltage drops due to various losses, and the release voltage at no load is about 23V.
In general, in a fuel cell alone, as shown in FIG. 3, the output voltage 111 of the fuel cell 110 decreases as the current supplied to the load unit 210 increases. There is output power 112. In the present embodiment, the maximum output power 112 can be extracted when the output voltage 111 is 10.4 V and 1.6 A is supplied, and the maximum output power 112 is 16.6 W. As described above, since the fuel cell 110 generates a voltage drop according to the output (load) current, there is a specific output voltage corresponding to the maximum output power 112, and the output power that can be taken out at or above the specific voltage. 113 drops. As described later, in the present embodiment, the specific output voltage corresponding to the maximum output power 112 is set as the set voltage 115. The set voltage 115 corresponds to an example that performs the function of the first specified value.

Further, as shown in FIG. 3, when the load current is taken out by 1.8 A or more, the output voltage 111 of the fuel cell 110 rapidly decreases, and the electric power 113 that can be taken out also decreases. This state is a dangerous situation for the fuel cell 110, and an irreversible reaction occurs and the fuel cell 110 itself is damaged, so that the original sufficient electric power cannot be generated even when restarted. As described above, the fuel cell 110 has the breakdown voltage 114 that breaks down when the load current is taken out and becomes a specific voltage or less. In general, in the DMFC, about 0.26 V per power generation cell is regarded as a breakdown voltage. In this embodiment, as described above, 30 cells are connected in series, so that about 7.8 V, that is, about 8 V corresponds to the breakdown voltage 114.
These characteristics are general properties of the DMFC, and when a power generation cell constituted by one MEA is connected in series, the breakdown voltage 114 is obtained by adding a voltage corresponding to the number of connections. In addition, in such output management of the fuel cell 110, it is effective to manage the output voltage 111 because the voltage value reacts sensitively rather than the current value to be extracted.

  In the present specification, the secondary battery 120 is a battery that does not include the fuel cell 110, and in the present embodiment, two lithium ion batteries are used as the auxiliary secondary battery 120 and are connected in series. The charging voltage of one lithium ion battery is 4.2 V as shown in FIG. 5, the discharge end voltage 122 is 3.0 V, and the capacity is 830 mAh. Practically, when a load current of 0.5 A is supplied at a constant output voltage of 4 V, the lifetime is 1.5 hours. When two such lithium ion batteries are connected in series, the initial voltage, that is, the maximum output voltage 123 of the lithium ion battery 120 is 8.4 V as shown in FIG. 4, and the final discharge voltage 122 is 6.0 V. It becomes. In the two lithium ion batteries 120 connected in series, the voltage that can be supplied is doubled, and about 4 W of power can be supplied for 1.5 hours.

Unlike the fuel cell 110, the lithium ion battery 120 can supply a substantially constant output voltage 121 without depending on the load current in the normal use state, as shown in FIG. In the present embodiment, the output voltage 121 of the lithium ion battery 120 is approximately 8.0V.
As shown in FIG. 5, which shows the discharge characteristics when the load is constant at 2 W in the case of a lithium ion battery alone, the output voltage 121 drops when the lithium ion battery is used up to the maximum load capacity. , 3.0V final discharge voltage 122 is the limit voltage of the lithium ion battery. If the discharge is continued beyond the end-of-discharge voltage 122, an irreversible reaction occurs even in the lithium ion battery, leading to the destruction of the battery.

  In the case of the lithium ion battery 120, the management of the charging voltage and the end-of-discharge voltage 122 is important. The secondary battery 120 is a power source essential for the operation of the auxiliary device that starts the fuel cell 110. When the power of the fuel cell 110 alone is insufficient for the load, the secondary battery 120 is added and output as an auxiliary power source. In addition, even when the fuel cell 110 is finally powered on, the secondary battery 120 is necessary to secure post-processing power after completion of the operation of the auxiliary device.

  In the notebook personal computer as the electronic device 201, the fuel cell 110 and the secondary battery 120 of the lithium ion battery described above are operated in parallel, and the maximum load is 20 W in this embodiment. The normal power of the personal computer 201 is 16 W, and the internal CPU, HDD, liquid crystal display, etc. operate well within 16 W. However, if an external device such as an FDD or a memory card is attached to the external port, the maximum power consumption Is designed to be 20W.

  In order to cover all the 20 W of power required by the personal computer 201 with the fuel cell 110 alone, a fuel cell having a size equivalent to that is required. Since the power generation capability of the fuel cell is proportional to the area of the MEA that causes an electrochemical reaction, the volume increases approximately in proportion to the 1.5th power of the generated power. Therefore, when a 16 W fuel cell is designed for 20 W, the volume increases about 1.4 times. It is important to make fuel cells for mobile applications as compact as possible from the viewpoint of commercial value. Further, since the fuel can be exchanged and supplied, and continuous operation is an advantage of the fuel cell, the power of the fuel cell is given priority to the power supply to the electronic device 201.

  In the fuel cell power supply system 101 of the present embodiment, the following power management is performed. That is, the lithium ion battery 120 that requires a charging operation is used for driving an auxiliary device when power cannot be supplied from the fuel cell 110, that is, when the fuel cell 110 is started up when the fuel cell 110 is overloaded. Normally, the fuel cell 110 supplies power to the load unit 210. Further, for example, when the personal computer 201 is lightly loaded such as when data processing is interrupted, the lithium ion battery 120 is charged by the output power of the fuel cell 110.

The voltage conversion circuit 130 is connected between the output side of the fuel cell 110 and the load unit 210 as described above, and supplies power to the load unit 210 from at least one of the fuel cell 110 and the secondary battery 120. In order to set the switching voltage used to determine this, the output voltage 111 of the fuel cell 110 is converted based on the set voltage to set the switching voltage. The switching voltage corresponds to an example that performs the function of the second specified value.
Since the output voltage 111 of the fuel cell 110 has a specific output voltage corresponding to the maximum power 112 of the fuel cell 110 as described above, in the present embodiment, as shown in FIG. The specific output voltage of the fuel cell 110 corresponding to 112 is the set voltage 115. In the case of this embodiment, specifically, the set voltage 115 is 10.4V.

  Specifically, the voltage conversion circuit 130 having such a function includes a voltage detection unit 131 that detects the output voltage 111 of the fuel cell 110 and a voltage setting that sets the switching voltage, as shown in FIG. Unit 132 and a feedback unit 133 that applies feedback to the voltage output from the voltage setting unit 132. In the present embodiment, the switching voltage 134 corresponding to the output voltage of the voltage conversion circuit 130 is set to 8.5 V, which is slightly higher than 8.0 V, which is the output voltage 121 of the lithium ion battery 120 as the secondary battery. doing. As described above, the output voltage 121 of the lithium ion battery 120 is substantially constant regardless of the load, whereas the output voltage 111 of the fuel cell 110 fluctuates and the output voltage 121 of the lithium ion battery 120 varies. The voltage is set higher than the output voltage 121 of the lithium ion battery 120 because it is desirable to supply power from the fuel cell 110 side to the load unit 210. In addition, when the power supply source is switched between the lithium ion battery 120 and the fuel cell 110, the voltage difference is set to 0.5 V so that the voltage does not change extremely. Of course, the voltage difference and the switching voltage value are set according to a configuration example of the fuel cell power supply system, and are not limited to the above values.

The voltage setting unit 132 includes an oscillator 1321, a first transistor 1322, a coil 1323, a capacitor 1324, and a third transistor 1325. The output voltage 111 of the fuel cell 110 is switched by the first transistor 1322 and the output voltage 111 is changed. The output voltage 111 of the fuel cell 110 is smoothed through a low-frequency component by the coil 1323 and the capacitor 1324 with a pulsed voltage. The feedback unit 133 feeds back the voltage of the capacitor 1324, that is, the output voltage Vout of the voltage setting unit 132, and when the voltage exceeds a specified voltage described later, the switching of the first transistor 1322 is stopped and the voltage falls below the specified voltage. Then, the switching is performed and the smoothing is performed. Note that the third transistor 1325 controls the switching on and off of the first transistor 1322. The feedback unit 133 includes a resistor 1331 that divides the output voltage Vout of the voltage setting unit 132, and divides the output voltage Vout to generate a base voltage Vb that is applied to the base of the third transistor 1325.
As described above, the voltage setting unit 132 turns on and off the switching of the first transistor 1322 and performs the smoothing. The smoothed voltage becomes the output voltage of the voltage conversion circuit 130, that is, the switching voltage 134 shown in FIG.

The voltage detection unit 131 includes a second transistor 1311 and a resistor 1312 that sets a base voltage of the second transistor 1311 to around 0.6V.
The voltage detection unit 131 configured as described above, the voltage setting unit 132, and the feedback unit 133 function as follows. That is, the output voltage 111 of the fuel cell 110 exceeds the set voltage 115 when the maximum power 112 of the fuel cell 110 is lower, that is, when the load current is relatively low. At this time, the base voltage of the second transistor 1311 exceeds 0.6V, the second transistor 1311 is in the ON state, and the output voltage V2 of the voltage detector 131 is at the GND level. Therefore, in the feedback unit 133, the feedback voltage V3 divides the output voltage Vout by the resistor 1331 regardless of the output voltage V2, and generates the base voltage Vb. In the present embodiment, the feedback voltage V3 is 0.6V with respect to the design value 8.5V of the output voltage Vout. Therefore, the third transistor 1325 of the voltage setting unit 132 is turned on when the base voltage Vb exceeds 0.6V, that is, when the output voltage Vout exceeds 8.5V, and the first transistor 1322 of the voltage setting unit 132 is turned on. Switching stops. On the other hand, when the base voltage Vb is 0.6 V or less, that is, when the output voltage Vout is 8.5 V or less, the third transistor 1325 is turned off and the first transistor 1322 is switched. In this way, the output voltage Vout is fixed to approximately 8.5V.

  On the other hand, as the load current of the fuel cell 110 increases, the output voltage 111 of the fuel cell 110 gradually decreases due to its characteristics, and when it exceeds the maximum output current of 1.6 A, The output voltage 111 is the set voltage 115 or less. At this time, the base voltage of the second transistor 1311 is 0.6 V or less, and the second transistor 1311 is turned off. Therefore, the output voltage V2 of the voltage detector 131 becomes the output voltage 111 of the fuel cell 110. In the feedback unit 133, the output voltage V2 affects the feedback voltage V3, and the output voltage 111 is applied as it is at a sufficiently low voltage. Accordingly, the base voltage Vb of the third transistor 1325 of the voltage setting unit 132 exceeds 0.6 V regardless of the output voltage Vout, the third transistor 1325 is turned on, and the first transistor 1322 of the voltage setting unit 132 is turned on. Switching stops. Therefore, the voltage detector 131 does not output. Thus, when the output voltage 111 of the fuel cell 110 becomes equal to or lower than the set voltage 115, as shown in FIG. 6, the voltage conversion circuit 130 droops to drop the output voltage, that is, the switching voltage 134 forcibly. Has characteristics. The drooping characteristic is that when the output voltage 111 of the fuel cell 110 becomes equal to or lower than the set voltage 115 until the breakdown voltage 114 of the fuel cell 110 reaches 8 V in this embodiment, the voltage conversion circuit 130 The output voltage drops to the discharge end voltage 122 of the secondary battery 120, which is 6 V or less in this embodiment.

  The rectifier circuit 150 includes a diode 151 connected to the output side of the voltage conversion circuit 130 and a diode 152 connected to the output side of the lithium ion battery 120. The output voltage of the voltage conversion circuit 130 described above, that is, The switching voltage 134 of about 8.5 V and the output voltage 121 of the lithium ion battery 120 of about 8.0 V are applied. Each of the diodes 151 and 152 is connected to the load unit 210, and is energized when a voltage is applied in the forward direction.

Therefore, when the switching voltage 134, which is the output voltage of the voltage conversion circuit 130, exceeds the output voltage 121 of the lithium ion battery 120 as in normal times, the diode 152 connected to the lithium ion battery 120 has a reverse direction. Since the voltage acts, the diode 152 is turned off and is not output from the lithium ion battery 120 to the load unit 210, but is supplied to the load unit 210 from the fuel cell 110 side, that is, from the voltage conversion circuit 130. Conversely, when the output voltage 121 of the lithium ion battery 120 exceeds the switching voltage 134 that is the output voltage of the voltage conversion circuit 130, the diode 151 is turned off and the diode 152 is turned on. Power is supplied to the unit 210.
Further, when the switching voltage 134 that is the output voltage of the voltage conversion circuit 130 is equal to the output voltage 121 of the lithium ion battery 120, power is supplied from both the voltage conversion circuit 130 and the lithium ion battery 120.

  As described above, power is normally supplied from the voltage conversion circuit 130 to the load unit 210 as described above, but as described above, when the fuel cell 110 extracts the load current, the output voltage decreases. Therefore, when the load current is taken out from the fuel cell 110 until the output voltage 121 of the lithium ion battery 120 becomes less than 121, the diode 151 is automatically turned off as described above, and the load portion from the fuel cell 110 side, that is, the voltage conversion circuit 130 is No current flows to 210, and instead, the diode 152 on the lithium ion battery 120 side is turned on and power is supplied from the lithium ion battery 120.

  However, when no current flows from the fuel cell 110 side, there is no load, so the fuel cell 110 is restored, the output voltage 111 of the fuel cell 110 rises, and the output voltage of the voltage conversion circuit 130 rises. 151 is turned on, and energization from the voltage conversion circuit 130 to the load unit 210 is resumed. With this energization, the output voltage of the voltage conversion circuit 130 drops again, and the energization from the voltage conversion circuit 130 to the load unit 210 is stopped. Therefore, such an operation is repeated, and on the fuel cell 110 side, an output corresponding to the output voltage 121 of the lithium ion battery 120 is supplied to the load unit 210, and the remaining power is supplied from the lithium ion battery 120. Become.

The operation of the fuel cell power supply system 101 in the present embodiment configured as described above will be described below.
As described above, when the load current is relatively low and the output voltage 111 of the fuel cell 110 exceeds the set voltage 115 of 10.4 V, as described above, the fuel cell power supply system in FIG. In the fuel cell power supply system 101, power is supplied from the fuel cell 110 side to the load unit 210 as indicated by a first portion 108 a of the output voltage 108 of 101.

  On the other hand, when the load current increases and the output voltage 111 of the fuel cell 110 becomes 10.4 V or less of the set voltage 115, the output voltage of the voltage conversion circuit 130, that is, the switching voltage 134, as described above, Since the voltage is forcibly lowered rapidly, the output voltage of the voltage conversion circuit 130 becomes less than the output voltage 121 of the lithium ion battery 120. Therefore, power is supplied from the lithium ion battery 120 to the load unit 210 as shown in the second portion 108b of the system output voltage 108 in FIG. At this time, as described above, power is supplied alternately to the load unit 210 from the fuel cell 110 side and the lithium ion battery 120 side.

As described above, the operation in which the output power of the fuel cell 110 is used to the maximum and the shortage can be supplied from the lithium ion battery 120 is unique in that the output voltage of the fuel cell 110 changes according to the load current. In consideration of the characteristics of the lithium ion battery 120 that outputs a substantially constant voltage with respect to the load current, the drooping characteristics of the voltage conversion circuit 130 are provided, and the drooping characteristics are provided. This is realized by connecting the output side of the voltage conversion circuit 130 and the output side of the lithium ion battery 120 in parallel with a diode.
That is, a state where the power of the fuel cell can be maximized cannot be maintained by simply connecting the fuel cell and the lithium ion battery to the diode in parallel. In the present embodiment, the voltage conversion circuit 130 is provided, the output voltage when the fuel cell 110 supplies the maximum power is set as the set voltage 115, and the output voltage 111 of the fuel cell 110 is converted with the set voltage 115 as a reference. Since the switching voltage 134 is generated, it is possible to supply power using the maximum output power of the fuel cell 110. The drooping characteristic is a characteristic in which the output voltage of the voltage conversion circuit 130 is lowered to the discharge end voltage 122 or less of the lithium ion battery 120 until the breakdown voltage 114 of the fuel cell 110 is reached. Therefore, the output voltage of the fuel cell 110 does not reach the breakdown voltage 114, and the fuel cell 110 can be prevented from being destroyed.

  In addition, when the fuel cell 110 side and the lithium ion battery 120 side are connected in parallel by the diodes 151 and 152, a slight voltage drop occurs in the diodes 151 and 152. In order to prevent the voltage drop as much as possible, the diodes 151 and 152 are preferably Schottky diodes.

A second embodiment;
Since the above-described lithium ion battery 120 can be charged, in the fuel cell power supply system of the second embodiment, when the output power of the fuel cell 110 has a margin, the output voltage 111 of the fuel cell 110 is used. The structure which charges the lithium ion battery 120 is shown.
The fuel cell power supply system 102 will be described with reference to FIG.
In addition to the configuration of the fuel cell power supply system 101 described above, the fuel cell power supply system 102 is newly provided with a charging circuit 160 for charging the lithium ion battery 120. Further, as a modification of the fuel cell power supply system 102, an output stop circuit 170 may be further provided. FIG. 2 shows a case where the output stop circuit 170 is provided. In FIG. 2, an auxiliary device driving circuit 190 for driving an auxiliary device used when starting the fuel cell 110 is also illustrated. Other configurations are the same as those in the first embodiment described above. Therefore, the description of the same components is omitted here.

The charging circuit 160 will be described.
As described above, when the fuel cell power supply system 102 is also provided in, for example, a laptop personal computer, the power consumption required for the personal computer in accordance with the work environment such as peripheral devices, memory, display, and CPU operation is fluctuate. Therefore, when there is a margin in the power supply of the fuel cell 110, the secondary battery can be charged with the margin of power. Therefore, the fuel cell power supply system 102 is provided with a charging circuit 160.
The charging circuit 160 is connected to the secondary battery, in this embodiment, the lithium ion battery 120, and the fuel cell 110, and is a circuit that charges the lithium ion battery 120 as described above. Circuit 162.

The output voltage comparison circuit 161 is connected to the output side of the fuel cell 110 and the lithium ion battery 120, compares the output voltage 111 of the fuel cell 110 with the set voltage 115, and the output voltage 121 of the lithium ion battery 120. This is a circuit that compares the rechargeable voltage in the lithium ion battery 120. Here, the rechargeable voltage is a voltage at which the lithium ion battery 120 can be charged. In this embodiment, two lithium ion batteries are connected in series. The value is 10% lower than the maximum output voltage 123 of 8.4V, and is set to 7.6V indicated by reference numeral 124 in FIG. Of course, it is not limited to 7.6V.
In such an output voltage comparison circuit 161, the output voltage 111 of the fuel cell 110 exceeds the set voltage 115, that is, 10.4V in this embodiment, and the output voltage 121 of the lithium ion battery 120 is the chargeable voltage 124, that is, 7.6V. Only when the following is detected, the charge switching circuit 162 is activated.

  The charge switching circuit 162 is connected between the output side of the fuel cell 110 and the output side of the lithium ion battery 120. The output of the fuel cell 110 is output only when instructed by the output voltage comparison circuit 161 as described above. In this circuit, the voltage 111 is applied to the lithium ion battery 120 to charge the lithium ion battery 120. That is, the lithium ion battery 120 is charged when the output voltage 111 of the fuel cell 110 exceeds the set voltage 115, that is, 10.4 V, that is, when the power is supplied from the fuel cell 110 side to the load unit 210. This is when the output power of the fuel cell 110 has a margin.

  Note that even when power is supplied only from the fuel cell 110 to the load unit 210, even when there is a margin in the fuel cell 110, the load increases due to the charging of the lithium ion battery 120, and the output power of the fuel cell 110 is increased. It is also conceivable that there will be no more room. Therefore, excessive charging is not performed in the charging operation. Therefore, the charging circuit 160 limits the charging current, and in this embodiment, the charging circuit 160 is configured to charge with a charging current of 0.16A. The charging current corresponds to a charging current for charging the lithium ion battery 120 of this embodiment in which two batteries having a capacity of 830 mAh are connected in series in 10 hours, and is an output current when the maximum output power of the fuel cell 110 is supplied. It corresponds to a value of 1/10 of a certain 1.6A.

  Further, as described above, in this embodiment, the output voltage 121 of the lithium ion battery 120 is equal to or lower than the chargeable voltage 124 and the set voltage 115 corresponding to the output voltage at the maximum power of the fuel cell 110. The fuel cell 110 is configured to enter the charging mode when a voltage exceeding 10.4 V is output, but considering the charging load, it is preferable to shift to the charging mode at a slightly higher output voltage 111 of the fuel cell 110. . Therefore, instead of the set voltage 115, for example, an output voltage corresponding to 90% of the maximum output power may be compared with the output voltage 111 of the fuel cell 110. As described above, when the charging power is limited to 10% of the maximum output power, the charging can be performed without excess or deficiency. That is, the output voltage 111 of the fuel cell 110 corresponding to 90% is 10.9 V, and the output current is 1.4 A. When the fuel cell 110 outputs 1.4 A at 10.9 V and enters the charging mode and supplies a charging current of 0.16 A, the output voltage 111 of the fuel cell 110 decreases to about 10.4 V. That is, the charging time corresponds to the maximum power supply time of the fuel cell 110, and charging can be performed efficiently.

Further, when the load suddenly increases with respect to the fuel cell 110 during the charging operation, the output voltage 111 of the fuel cell 110 rapidly decreases due to the increase of the load current, and as described above, the fuel cell 110 and the lithium ion The battery 120 and the load unit 210 are alternately supplied with power. In such a case, for the lithium ion battery 120, the charging mode is rapidly shifted to the discharging mode, and such a rapid switching operation is not preferable.
Therefore, it is preferable to stop the charging mode in advance immediately before the output voltage 111 of the fuel cell 110 reaches the maximum power 112 of the fuel cell 110 and shift to the alternate power output state. Therefore, it is possible to design such that charging is stopped with reference to 10.5 V of the charging stop voltage 116 shown in FIG. 3, which is the output voltage 111 of the fuel cell 110 when reaching 97% of the maximum power 112, for example.

As described above, in the fuel cell power supply systems 101 and 102 according to the present embodiment, it is understood that the power supply to the load unit 210 can be efficiently performed by managing the output voltage 111 of the fuel cell 110.
When the charging mode is entered, operating the load electronic device in the power saving mode makes it possible to ensure a smoother operation of the power supply system. For example, if the load electronic device is mainly a CPU operation in a personal computer or the like, for example, the operation clock frequency itself is lowered, or if it is a video display device, for example, the brightness of the liquid crystal screen is slightly lowered to reduce the secondary The load on the fuel cell during the battery charging mode can be reduced. Therefore, the load margin in the charging mode of the fuel cell is increased, and even if the load rapidly increases during charging, a margin can be generated in the power supply system.

  In general, lithium ion batteries are charged at a constant voltage and a constant current for safety measures. When the amount of charge is small, a constant current that does not allow an excessive current to flow, and a charging voltage that does not exceed the charge voltage when full charge is approached is set to constant voltage charging. This also applies to the systems 101 and 102 of the present embodiment, and constant current charging is performed at a charging current of 0.16 A until the voltage of the lithium ion battery reaches the maximum output voltage of 8.4 V. When 4V was reached, a charging method was used in which the charging voltage was maintained at 8.4V.

As a modification of the second embodiment, a case where the output stop circuit 170 is provided will be described.
In the first and second embodiments described above, since the fuel cell 110 and the secondary battery 120 are operated in parallel, the operation of the system is stopped when one of the batteries malfunctions. I have to let it. When the fuel cell 110 as the main power source becomes inoperable due to a temperature factor such as a shortage of fuel or when the operating temperature rises abnormally with respect to the boiling point of methanol as the fuel, as described above, In the system, power can be supplied from the secondary battery 120 in the short term. However, when the output voltage 121 of the lithium ion battery of the secondary battery 120 becomes equal to or lower than the discharge end voltage 122, the lithium ion battery is destroyed, and the auxiliary device operation management after the operation of the fuel cell 110 is disabled becomes impossible. For example, operations such as opening and closing of fuel-related valves, operation of the heat dissipation fan, and remaining amount display become impossible. In order to prevent such a situation, a means for disconnecting the output of the power supply system from the load unit 210 immediately before the end-of-discharge voltage 122 of the secondary battery 120 is important.
Therefore, as shown in FIG. 2 as a modified example, the output stop circuit 170 can be provided between the output side of the lithium ion battery 120 and the load unit 210. The output stop circuit 170 detects that the output voltage 121 of the lithium ion battery 120, which is a secondary battery, has dropped to the load stop voltage 125 shown in FIG. When the load stop voltage 125 is detected, the output from the lithium ion battery 120 to the load unit 210 is stopped. In this modification, the load stop voltage 125 is set to about 6.2V.

In each of the above-described embodiments, the lithium ion battery 120 of the secondary battery adopts a form in which two batteries are connected in series. Therefore, the voltage conversion circuit 130 steps down the output voltage 111 of the fuel cell 110. Although the step-down type has been described, it is needless to say that the step-down type is not limited thereto, and a step-up type voltage conversion circuit can be configured in relation to the output voltage 121 of the secondary battery 120. Even in the boost type, the same effect as described above can be obtained by limiting the lower limit voltage with a voltage corresponding to the maximum output power of the fuel cell 110 and adding the same with a diode. The charging operation can be performed in the same manner.
In each of the above-described embodiments, the lithium ion battery is used as the secondary battery. However, the present invention is not limited to this, and can be realized with other auxiliary batteries, and can be replaced with a DC power source created from a commercial power source. It is.

  The present invention includes a fuel cell and a secondary battery, and supplements the output power of the fuel cell with the secondary battery to supply power to a load unit, and the fuel cell power system. Applicable to electronic devices equipped.

The figure which shows the structure of the power supply system for fuel cells in 1st Embodiment of this invention. The figure which shows the structure of the power supply system for fuel cells in 2nd Embodiment of this invention. The graph which shows the voltage-current characteristic in the fuel cell with which the power supply system for fuel cells shown in FIG.1 and FIG.2 is equipped. The graph which shows the voltage-current characteristic in the lithium ion battery with which the power supply system for fuel cells shown in FIG.1 and FIG.2 is equipped. The graph which shows the discharge characteristic of a single lithium ion battery. The graph which shows the voltage-current characteristic of the voltage conversion circuit with which the power supply system for fuel cells shown in FIG.1 and FIG.2 is equipped. The graph which shows the voltage-current characteristic in the power supply system for fuel cells shown in FIG.1 and FIG.2. The perspective view of the electronic device provided with the power supply system for fuel cells shown in FIG.1 and FIG.2.

Explanation of symbols

101, 102 ... Fuel cell power supply system, 110 ... Fuel cell,
111 ... output voltage, 112 ... maximum output power, 114 ... breakdown voltage,
115 ... set voltage, 116 ... charge stop voltage, 122 ... discharge end voltage,
123: Maximum output voltage, 124: Chargeable voltage, 125: Load stop voltage,
130 ... Voltage conversion circuit, 131 ... Voltage detection unit, 132 ... Voltage setting unit,
133 ... Feedback unit, 134 ... Switching voltage, 150 ... Rectifier circuit,
160 ... charging circuit, 161 ... output voltage comparison circuit, 162 ... charge switching circuit,
170 ... output stop circuit,
210: A lithium ion battery.

Claims (12)

A fuel cell (110) for generating electricity and supplying power to the load section (210);
A secondary battery (120) that complements the output power of the fuel cell and supplies power to the load;
A switching voltage (which is connected between the output side of the fuel cell and the load unit, and is used to determine that power is supplied from at least one of the fuel cell and the secondary battery to the load unit ( 134) to set the switching voltage by converting the output voltage of the fuel cell with reference to the set voltage (115),
Connected between the output side of the voltage conversion circuit and the output side of the secondary battery and the load section, and the switching voltage corresponding to the output voltage of the voltage conversion circuit exceeds the output voltage of the secondary battery. Sometimes power is supplied from the fuel cell to the load section through the voltage conversion circuit, and when the switching voltage is equal to the output voltage of the secondary battery, from the secondary battery and from the fuel cell through the voltage conversion circuit. A rectifier circuit (150) for supplying power to the load unit in parallel and supplying power from the secondary battery to the load unit when the switching voltage is less than the output voltage of the secondary battery;
A power supply system for a fuel cell, comprising: The set voltage in the voltage conversion circuit is the voltage of the fuel cell when the maximum output power (112) of the fuel cell is output,
When the output voltage of the fuel cell exceeds the set voltage, the voltage conversion circuit converts the output voltage of the fuel cell to a voltage exceeding the maximum output voltage (123) of the secondary battery, and converts the voltage for switching. Set,
2. The fuel cell power supply system according to claim 1, wherein when the output voltage of the fuel cell becomes equal to or lower than the set voltage, the voltage conversion circuit has a drooping characteristic that forcibly drops the output voltage of the voltage conversion circuit.   The drooping characteristic in the voltage conversion circuit is that the output voltage of the voltage conversion circuit is changed from when the output voltage of the fuel cell becomes equal to or lower than the set voltage to the breakdown voltage (114) of the fuel cell. The power supply system for a fuel cell according to claim 2, which has a characteristic of dropping to a discharge end voltage (122) or less of the secondary battery. The voltage conversion circuit includes a voltage detection unit (131) that detects the output voltage of the fuel cell, a voltage setting unit (132) that sets the switching voltage, and a feedback to the voltage output from the voltage setting unit. And a return part (133) for applying
When the voltage detection unit detects that the output voltage of the fuel cell exceeds the set voltage, the voltage setting unit sets the output voltage of the fuel cell to the switching voltage by the voltage feedback action of the feedback unit. The feedback unit stops the output to the voltage setting unit when the voltage detection unit detects that the output voltage of the fuel cell is equal to or lower than the set voltage. A fuel cell power supply system according to claim 1.   The power supply system for a fuel cell according to any one of claims 1 to 4, wherein the rectifier circuit is formed of a diode.   The power supply system for a fuel cell according to any one of claims 1 to 5, further comprising a charging circuit (160) connected to the fuel cell and the secondary battery to charge the rechargeable secondary battery. The charging circuit is
It is connected to the output side of the fuel cell and the secondary battery, compares the output voltage of the fuel cell with the set voltage, and outputs the output voltage of the secondary battery to the rechargeable voltage (124 Output voltage comparison circuit (161) for comparison with
Connected between the output side of the fuel cell and the output side of the secondary battery, the output voltage of the fuel cell exceeds the set voltage, and the output voltage of the secondary battery is less than or equal to the chargeable voltage. A charge switching circuit (162) for charging the secondary battery by applying the output voltage of the fuel cell to the secondary battery only when the output voltage comparison circuit detects
The power supply system for a fuel cell according to claim 6.   After the charging switch circuit starts charging the secondary battery, the output voltage comparison circuit further detects a charge stop voltage (116) that is an arbitrary voltage value less than the set voltage, and outputs the output 8. The fuel cell power supply system according to claim 7, wherein when the voltage comparison circuit detects the charge stop voltage, the charge switching circuit stops charging the secondary battery.   Connected between the output side of the secondary battery and the load section, the output voltage of the secondary battery has dropped to a load stop voltage (125) slightly exceeding the discharge end voltage (122) of the secondary battery. And further comprising an output stop circuit (170) for stopping the output from the secondary battery to the load section when the load stop voltage is detected. Power system. A fuel cell power supply system (101, 102) according to any of claims 1 to 9,
A load section (210) that receives power from the fuel cell power supply system;
An electronic device characterized by comprising: A fuel cell power supply comprising a fuel cell (110) that generates power and supplies power to the load unit (210), and a secondary battery (120) that supplements the output power of the fuel cell and supplies power to the load unit. In the power supply method in the system,
A switching voltage (134) for determining that power is supplied from at least one of the fuel cell and the secondary battery to the load unit is set to a voltage value of the output voltage (111) of the fuel cell. Convert and set the output voltage of the fuel cell based on the voltage (115),
When the output voltage of the fuel cell exceeds the set voltage, the switching voltage is set to a voltage exceeding the maximum output voltage (123) of the secondary battery, and power is supplied from the fuel cell to the load unit. ,
When the output voltage of the fuel cell becomes equal to or lower than the set voltage, the switching voltage is forcibly lowered to supply power from the secondary battery to the load unit.
The power supply method in the power supply system for fuel cells characterized by the above-mentioned. A fuel cell (110) for generating first power;
A secondary battery (120) for generating second power;
The output voltage level of the fuel cell is connected to the output of the fuel cell, and the first specified value (115) and the second specified value (134) are compared, and the fuel cell output voltage level is the first specified value. A fuel cell controller that stops the power generation of the fuel cell when the following conditions are satisfied and determines the output power of the fuel cell and the secondary battery based on a comparison between the fuel cell output voltage level and the second specified value ( 130, 150),
A power supply system for a fuel cell, comprising:

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