Chemistry: electrical current producing apparatus – product – and – Having magnetic field feature
Reexamination Certificate
2001-06-04
2004-11-09
Gulakowski, Randy (Department: 1746)
Chemistry: electrical current producing apparatus, product, and
Having magnetic field feature
C429S006000, C429S006000
Reexamination Certificate
active
06815100
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control device for starting a fuel cell vehicle, and in particular, relates to a technique for starting the fuel cell in a hybrid-type power source device provided with a power storage unit for assisting a power supply from the fuel cell.
2. Description of the Related Art
Conventionally, a hybrid-type fuel cell power generation system is known, which comprises a fuel cell and a power storage unit such as a battery or a capacitor (electric double layer capacitor or condenser) in order to compensate the output responsiveness of the fuel cell, which is driven by a fuel gas supply. The fuel cell vehicle is installed with a solid polymer-type fuel cell, which is composed of a plurality of cells, each of which is formed by sandwiching a solid polymer electrolyte membrane corresponding to a solid polymer ion exchange membrane between an anode and a cathode.
In the above conventional hybrid-type fuel cell power generation system, when starting the fuel cell, first, air is supplied to a pressure control valve at the fuel side, for example, and fuel gas is supplied to the fuel electrode in response to air pressure supplied to the pressure control valve.
Thus, before starting the fuel cell, the power storage unit supplies electric driving power to the compressor which supplies air. In addition to auxiliary devices for driving the fuel cell, the power storage unit supplies electric power to the motor for driving the vehicle when the vehicle starts immediately after the start of the fuel cell, so that the power stored in the power storage unit is reduced, and the voltage between both terminals of the power storage unit is reduced.
When the fuel cell is connected to the power storage unit, whose voltage between both terminals has been reduced, a large current rapidly flows from the fuel cell to the power storage unit. In the course of translating the voltage between both terminals of the fuel cell and the power storage unit into a balanced state, the voltage between both terminals of the fuel cell is reduced. Then, the fuel cell is in danger of losing hydrogen or the water content in the solid polymer electrolyte film, or of experiencing a decrease in the durability of the fuel cell.
As described above, if the fuel cell is connected to the capacitor under a condition that the terminal voltage of the capacitor greatly differs from the terminal voltage of the fuel cell (output voltage of the fuel cell) at the time, for example, of starting the fuel cell, a large current may flow, which may cause a danger that the performance or the durability of the fuel cell will become deteriorated.
SUMMARY OF THE INVENTION
In the conventional fuel cell power source device, when the fuel cell is being started, air is first supplied to the pressure control valve for supplying fuel, and fuel supply is started in response to the air pressure supplied to the pressure control valve.
Thus, prior to activation of the fuel cell, a driving electric power is supplied to the fuel supply device such as an air compressor. In addition to the activation of the fuel cell driving auxiliary machines and various control devices, electric power is supplied from the capacitor to the propulsion motor, which is driven immediately after starting the fuel cell vehicle, which results in reducing the capacitor energy causing depression of the terminal voltage of the capacitor.
If the capacitor, in which terminal voltage has been depressed, and the fuel cell are connected, a large current flows from the fuel cell towards the capacitor, the terminal voltage of the fuel cell is reduced in the course of recovering both terminal voltages of the fuel cell and the capacitor to an equilibrium voltage. When the terminal voltage of the fuel cell is depressed, the performance or the long-term stability of the fuel cell are in risk of being deteriorated, or hydrogen and water in the solid polymer electrolyte membrane are in danger of being evaporated.
As described above, when the fuel cell and the capacitor are connected to each other under conditions that the terminal voltage of the capacitor is far below the terminal voltage of the fuel cell, a large current flows from the fuel cell to the capacitor, which may cause a danger to the performance and long-term stability of the fuel cell will be deteriorated.
The present invention was made in order to solve the above problems and an object of the present invention is to provide a control device for starting the fuel cell vehicle and which is capable of preventing an excessive reduction of the voltage between both terminals of the fuel cell.
One aspect of the present invention provides a control apparatus for starting a fuel cell vehicle comprising: a fuel cell (for example, a fuel cell
11
in the embodiment) supplying electric power to a load (for example, driving motor
13
, PDU
14
, and air compressor
15
, etc. in the embodiment); a capacitor (for example, power storage unit
12
in the embodiment) for assisting the supply of electric power to the load and for storing generated energy of the fuel cell; a fuel cell driving device (for example, air compressor
15
in the embodiment) for supplying reaction gases (for example, hydrogen gas and air in the embodiment) and for driving the fuel cell; and a current limiting device (for example, a secondary precharge circuit
17
in the embodiment) for limiting an output current (for example, output current Ifc in the embodiment) from the fuel cell; wherein, at the time of starting the fuel cell, the capacitor supplies electric energy to the fuel cell driving device and the current limiting device prohibits the fuel cell from outputting an output current until an output voltage (for example, output voltage Vfc in the embodiment) of the fuel cell reaches a predetermined voltage, and, after the output voltage rises to more than the predetermined voltage (for example, V
MOT
≈Vst≈Vfc in the embodiment), the current limiting device limits the output current of the fuel cell to below a predetermined current value until the difference between the output voltage of the fuel cell and a terminal voltage of the capacitor (for example, terminal voltage Vst in the embodiment) reaches a predetermined voltage difference (for example, predetermined voltage difference &Dgr;V in the embodiment).
According to the above constitution of the control apparatus for starting a fuel cell vehicle, since the output current of the fuel cell is limited at the time of starting the fuel cell, it is possible to prevent the terminal voltage of the fuel cell from reducing rapidly.
That is, at the time of starting the fuel cell, air is supplied to the pressure control device for supplying fuel to the fuel electrode of the fuel cell in addition to the air electrode of the fuel cell. In this case, the capacitor supplies electric power to the fuel cell driving device and the terminal voltage of the capacitor reduces. By providing a primary precharge circuit, which is provided with a resistor having a relatively high resistance, the capacitor can output a limited current to the fuel cell driving device or the power drive unit of the driving motor through the resistor, to thereby prevent the fuel cell from generating large output current.
In the above case, the DC-DC chopper prohibits the output current flowing from the fuel cell until the output voltage of the fuel cell reaches a predetermined voltage, and, the DC-DC chopper limits the output current flowing from the fuel cell, even after the output voltage of the fuel cell has been reached to a predetermined voltage, thereby, it is possible for a large current to flow from the fuel cell to the capacitor.
The above mechanism prevents a large current from flowing from the fuel cell to the capacitor until the voltage difference between the terminal voltage of the fuel cell and the terminal voltage of the capacitor become less than a predetermined value. Thus, in that period, the capacitor is gradually charged by a limited current from the fuel cell,
Aoyagi Satoshi
Hasuka Yoshinobu
Saeki Hibiki
Arent & Fox PLLC
Gulakowski Randy
Honda Giken Kogyo Kabushiki Kaisha
Wills M.
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