Method and apparatus to regulate the supply of power to an electric drive using a hybrid energy supply system in a vehicle
First Claim
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1. A method to regulate a supply of energy to an electric motor from a hybrid energy supply system that comprises at least one fuel cell, at least one energy storage buffer, a bi-directional converter electrically coupled between the fuel cell and the energy storage buffer, and a DC/DC converter electrically coupled between the bi-directional converter and the energy storage buffer, the method comprising:
- producing a vehicle current request value based at least in part on a detected position of a throttle;
determining an output voltage of the fuel cell;
in a first operating mode, current controlling the DC/DC converter if the output voltage of the fuel cell is between an upper limit value and a lower limit value so that the current supplied to the electric motor by the fuel cell is approximately equal to the vehicle current request value;
voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or below the lower limit value to raise the output voltage of the fuel cell to a level of at least the lower limit value, and voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or above the upper limit value to lower the output voltage of the fuel cell, to a level not greater than the upper limit value.
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Abstract
Regulation of energy supplied to an electric motor from an energy supply system including a fuel cell and an energy storage buffer such as a battery, improves the dynamic response of the motor by adding current from the energy storage buffer to the current from the fuel cell during acceleration.
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Citations
22 Claims
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1. A method to regulate a supply of energy to an electric motor from a hybrid energy supply system that comprises at least one fuel cell, at least one energy storage buffer, a bi-directional converter electrically coupled between the fuel cell and the energy storage buffer, and a DC/DC converter electrically coupled between the bi-directional converter and the energy storage buffer, the method comprising:
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producing a vehicle current request value based at least in part on a detected position of a throttle;
determining an output voltage of the fuel cell;
in a first operating mode, current controlling the DC/DC converter if the output voltage of the fuel cell is between an upper limit value and a lower limit value so that the current supplied to the electric motor by the fuel cell is approximately equal to the vehicle current request value;
voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or below the lower limit value to raise the output voltage of the fuel cell to a level of at least the lower limit value, and voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or above the upper limit value to lower the output voltage of the fuel cell, to a level not greater than the upper limit value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An apparatus to regulate the energy supply of an electric motor and further loads using a hybrid energy supply system that comprises a fuel cell stack and an energy storage buffer;
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a power bus electrically coupling the fuel cell stack to the electric motor;
a DC/DC converter electrically coupled between the power bus and the energy storage buffer;
a bi-directional converter electrically coupled between the power bus and the electric motor;
a voltage sensor electrically coupled across the fuel cell stack to determine a fuel cell stack output voltage;
a current sensor electrically coupled to the fuel cell stack to determine a fuel cell stack output current;
a throttle;
a position detector coupled to detect a position of the throttle;
a motor controller coupled to control the electric motor;
a vehicle controller configured to produce a current request value based at least in part on a position of the throttle and further configured to provide a setpoint to the motor controller;
a fuel cell controller coupled to receive the current request value from the vehicle controller, and to provide indications of an available vehicle current, a maximum vehicle current, and a minimum available vehicle current to the vehicle controller, the fuel cell controller further coupled to receive an indication of the fuel cell output voltage from the voltage sensor;
the motor controller, vehicle controller and fuel cell controller coupled and configured to, in a first operating mode, current control the DC/DC converter if the fuel cell stack output voltage is between an upper limit value and a lower limit value so that the current supplied to the electric motor by the fuel cell is approximately equal to the vehicle current request value;
voltage control the DC/DC converter if the fuel cell stack output voltage is at or below the lower limit value to raise the fuel cell stack output voltage to a level of at least the lower limit value, and voltage controlling the DC/DC converter if the fuel cell stack output voltage is at or above the upper limit value to lower the fuel cell stack output voltage to a level not greater than the upper limit value; and
in a second operating mode, reverse the flow of current of the DC/DC converter and the bi-directional converter to charge the energy storage buffer;
current controlling the DC/DC converter;
current controlling the bi-directional converter if the output voltage of the fuel cell is at or below the upper limit value to reduce power to the electric motor to the set point value; and
voltage controlling the bi-directional converter if the output voltage of the fuel cell exceeds the upper limit value in order to limit the output voltage of the fuel cell to the upper limit value. - View Dependent Claims (21)
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22. An apparatus to regulate a supply of energy to an electric motor from a hybrid energy supply system that comprises at least one fuel cell, at least one energy storage buffer and a DC/DC converter electrically coupled between the fuel cell and the energy storage buffer, comprising:
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means for producing a vehicle current request value based on a detected position of a throttle;
means for determining an output voltage of the fuel cell;
in a first operating mode, means for;
current controlling the DC/DC converter if the output voltage of the fuel cell is between an upper limit value and a lower limit value so that the current supplied to the electric motor by the fuel cell is approximately equal to the vehicle current request value;
voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or below the lower limit value to raise the output voltage of the fuel cell to a level of at least the lower limit value, and voltage controlling the DC/DC converter if the output voltage of the fuel cell is at or above the upper limit value to lower the output voltage of the fuel cell to a level not greater than the upper limit value; and
in a second operating mode, means for;
reversing the flow of current of the DC/DC converter and the bi-directional converter to charge the energy storage buffer;
current controlling the DC/DC converter;
current controlling the bi-directional converter if the output voltage of the fuel cell is at or below the upper limit value to reduce power to the electric motor to a set point value; and
voltage controlling the bi-directional converter if the output voltage of the fuel cell exceeds the upper limit value in order to limit the output voltage of the fuel cell to the upper limit value.
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Specification