DC power supply using fuel cell
First Claim
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1. A direct current power supply system for a vehicle, comprising:
- a pair of terminals that provide an electric power;
a fuel cell connected to the terminals;
a DC/DC converter connected to the terminals;
an electric power storage unit that is connected to the terminals via the DC-DC converter in parallel with the fuel cell, the electric power storage unit being able to be charged and discharged, wherein a maximum output power of the fuel cell is greater than a maximum output power of the electric power storage unit; and
a control unit adapted to set a lower limit of an output ratio of said fuel cell to said electric power storage unit, set an upper limit of the output ratio of said fuel cell to said electric power storage unit, and set an actual output ratio based upon said lower limit, said upper limit and an energy efficiency of the vehicle.
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Abstract
A power supply system includes a fuel cell and a battery connected in parallel. A DC-DC converter is connected to the battery. A maximum output ratio of the fuel cell and the battery is set to be in a range where the output of the fuel cell is within 65 to 80% of the total output. Accordingly, electric power loss owing to conversion performed by the DC-DC converter is reduced to achieve a high energy efficiency.
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Citations
17 Claims
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1. A direct current power supply system for a vehicle, comprising:
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a pair of terminals that provide an electric power;
a fuel cell connected to the terminals;
a DC/DC converter connected to the terminals;
an electric power storage unit that is connected to the terminals via the DC-DC converter in parallel with the fuel cell, the electric power storage unit being able to be charged and discharged, wherein a maximum output power of the fuel cell is greater than a maximum output power of the electric power storage unit; and
a control unit adapted to set a lower limit of an output ratio of said fuel cell to said electric power storage unit, set an upper limit of the output ratio of said fuel cell to said electric power storage unit, and set an actual output ratio based upon said lower limit, said upper limit and an energy efficiency of the vehicle. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A vehicle comprising:
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a motor serving as a driving power source, a drive circuit that drives the motor by electric power, a direct current power supply unit that supplies the electric power to the drive circuit, wherein the direct current power supply unit comprises;
a pair of terminals that provide an electric power;
a fuel cell connected to the terminals;
a DC/DC converter connected to the terminals; and
an electric power storage unit that is connected to the terminals via the DC-DC converter in parallel with the fuel cell, the electric power storage unit being able to be charged and discharged, wherein a maximum output power of the fuel cell is greater than a maximum output power of the electric power storage unit; and
a control unit adapted to set a lower limit of an output ratio of said fuel cell to said electric power storage unit, set an upper limit of the output ratio of said fuel cell to said electric power storage unit, and set an actual output ratio based upon said lower limit, said upper limit and an energy efficiency of the vehicle. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for supplying a direct current from a fuel cell and an electric power storage unit that can be charged and discharged to output terminals, which are connected in parallel with the output terminals, wherein a maximum output power of the fuel cell is greater than a maximum output power of the electric power storage unit, the method comprising:
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(a) operating the fuel cell to generate a predetermined voltage;
(b) converting a voltage generated by the electric power accumulating unit by using the DC-DC converter to a voltage equal to the predetermined voltage generated by the fuel cell and applying the converted voltage to the terminals; and
setting an output ratio of said fuel cell to said electric power storage unit by setting a lower limit of the output ratio, setting an upper limit of the output ratio, and setting the output ratio based upon said lower limit, said upper limit and an energy efficiency of the vehicle. - View Dependent Claims (15)
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16. A direct current power supply system for a vehicle, comprising:
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a pair of terminals that provide an electric power;
a fuel cell connected to the terminals;
a DC/DC converter connected to the terminals;
an electric power storage unit that is connected to the terminals via the DC-DC converter in parallel with the fuel cell, the electric power storage unit being able to be charged and discharged, wherein a maximum output power of the fuel cell is greater than a maximum output power of the electric power storage unit; and
control means for setting a lower limit of an output ratio of said fuel cell to said electric power storage unit based on vehicle driving conditions, setting an upper limit of the output ratio of said fuel cell to said electric power storage unit based on vehicle driving conditions, and setting an actual output ratio based upon said lower limit, said upper limit and an energy efficiency of the vehicle. - View Dependent Claims (17)
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Specification