Motor vehicles – Power – Electric
Reexamination Certificate
2002-06-06
2004-02-17
Johnson, Brian L. (Department: 3618)
Motor vehicles
Power
Electric
C180S065100, C429S006000, C429S006000, C701S022000
Reexamination Certificate
active
06691810
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for controlling a fuel cell vehicle having a fuel cell stack and an electric double layer capacitor which are connected parallel to each other as a power supply for a propulsive motor of the fuel cell vehicle, and more particularly to the art of limiting the electric energy that is outputted to the propulsive motor to propel the fuel cell vehicle.
2. Description of the Related Art
One known control apparatus for use on a fuel cell vehicle for controlling the supply of electric energy consumed by the fuel cell vehicle is shown in
FIG. 4
of the accompanying drawings.
As shown in
FIG. 4
, the control apparatus has a fuel cell
102
as a power supply for a motor drive unit
101
which supplies electric energy to a propulsive motor
100
and electric accessories (not shown) such as an air-conditioning unit, etc. An electric double layer capacitor
103
is connected parallel to the fuel cell
102
for discharging electric energy to make up for a shortage of electric energy generated by the fuel cell
102
when the amount of reactive gases supplied to the fuel cell
102
becomes insufficient due to a response delay of a reactive gas supply unit
104
.
A fuel cell control unit
105
detects an operating state of the fuel cell
102
based on the pressure (Pgas), the flow rate (Qgas), and the temperature (Tgas) of reactive gases (hydrogen and air) supplied to the fuel cell
102
, and recognizes an upper limit amount of amount (Ifc_LMT) of the electric energy that can be outputted from the fuel cell
102
based on the detected operating state. An electric vehicle control unit
106
calculates a motor-requested electric energy (PD_REQ) which is required to energize the motor
100
based on the amount of depression (Ap) of an accelerator pedal on the vehicle and the rotational speed (Nm) of the motor
100
.
A power supply management control unit
107
indicates a target amount of electric energy (Ifc_CMD) to be generated by the fuel cell
102
to the fuel cell control unit
105
depending on the motor-requested electric energy (PD_REQ) and an electric energy (Pload) consumed by the electric accessories. The power supply management control unit
107
also indicates an output limit electric energy (PLD) which represents an upper limit amount of the electric energy that can be outputted from the motor drive unit
101
to the motor
100
, depending on the upper limit amount of generated electric energy (Ifc_LMT), to the electric vehicle control unit
106
so that the amount of electric energy generated by the fuel cell
102
will not become insufficient.
The fuel cell control unit
105
determines a command value of the supplied amount of reactive gases (CMP_CMD) for the reactive gas supply unit
104
in order to achieve the target amount of electric energy (Ifc_CMD). The electric vehicle control unit
106
determines a torque command (TQ_CMD) for the motor drive unit
101
so that the electric energy outputted to the motor
100
will not exceed the output limit electric energy (PLD).
As a result, the fuel cell
102
operates to generate an amount of electric energy depending on the motor-requested electric energy (PD_REQ). Since the electric energy outputted from the motor drive unit
101
to the motor
100
is limited to an amount equal to or smaller than the output limit electric energy (PLD), the amount of electric energy generated by the fuel cell
102
is preventing from becoming insufficient.
When water produced by an electrochemical reaction of the reactive gases is trapped in cell units of the fuel cell
102
, the output electric energy of the fuel cell
102
is lowered. If the fuel cell
102
suffers such a malfunction, then its electric generating capability is reduced, and the upper limit amount of generated electric energy (Ifc_LMT) is also reduced. If the upper limit amount of generated electric energy (Ifc_LMT) is reduced, the output limit electric energy (PLD) is also reduced, lowering an upper limit of the torque command (TRQ_CMD) for the motor drive unit
101
.
Therefore, when the fuel cell
102
malfunctions, causing a sudden drop of the upper limit amount of generated electric energy (Ifc_LMT), while the fuel cell vehicle is running, the output torque produced by the motor
100
is abruptly reduced due to a reduction in the upper limit of the torque command (TRQ_CMD). As a result, the driver and passengers of the fuel cell vehicle are likely to suffer anxiety and discomfort the instant the output torque produced by the motor
100
is abruptly reduced.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a control apparatus for controlling a fuel cell vehicle to prevent the output torque of a propulsive motor from dropping sharply in the even of a malfunction of a fuel cell mounted on the fuel cell vehicle.
According to the present invention, there is provided an improvement over an apparatus for controlling a fuel cell vehicle having motor driving means for outputting electric energy depending on a given torque command to a propulsive motor, a fuel cell for use as a power supply for the motor driving means, and an electric double layer capacitor connected parallel to the fuel cell, for being charged by the fuel cell and discharged to supplement a shortage of an amount of electric energy generated by the fuel cell.
The apparatus comprises upper limit electric energy recognizing means for detecting an operating state of the fuel cell and recognizing an upper limit amount of electric energy generated by the fuel cell depending on the detected operating state, upper limit discharged electric energy recognizing means for recognizing an upper limit amount of discharged electric energy representing an amount of electric energy discharged from the electric double layer capacitor when the amount of electric energy generated by the fuel cell reaches the upper limit amount of generated electric energy, upper limit total electric energy recognizing means for recognizing an upper limit amount of total electric energy representing an upper limit amount of total electric energy which can be outputted from the fuel cell and the electric double layer capacitor, depending on the upper limit amount of discharged electric energy and the upper limit amount of generated electric energy, and torque command limiting means for limiting the torque command to at most an upper limit of torque depending on the upper limit amount of total electric energy.
The upper limit total electric energy recognizing means recognizes the upper limit amount of total electric energy depending on the upper limit amount of generated electric energy of the fuel cell and the upper limit amount of discharged electric energy of the electric double layer capacitor. Even if the fuel cell malfunctions and the upper limit amount of generated electric energy of the fuel cell which is recognized by the upper limit electric energy recognizing means sharply drops, a reduction in the upper limit amount of total electric energy is suppressed by an amount of electric energy discharged from the electric double layer capacitor.
The torque command limiting means limits the torque command to at most the upper limit of torque depending on the upper limit amount of total electric energy. When the fuel cell malfunctions while the fuel cell vehicle is running, the torque command for the motor is prevented from being abruptly reduced, thus preventing the output torque of the motor from being lowered. Accordingly, the driver and passengers of the fuel cell vehicle are prevented from suffering anxiety and discomfort due to a change in the behavior of the fuel cell vehicle which would otherwise be caused by a sharp decrease in the output torque of the motor.
The apparatus further comprises open voltage recognizing means for recognizing an open voltage across the electric double layer capacitor, and storage means for storing data of a characteristic map representing the correlation between the amount of electric
Aoyagi Satoshi
Hasuka Yoshinobu
Saeki Hibiki
Uenodai Asao
Honda Giken Kogyo Kabushiki Kaisha
Johnson Brian L.
Lahive & Cockfield LLP
Phan Hau
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