METHOD AND SYSTEM FOR CONTROLLING POWER DISTRIBUTION IN A HYBRID FUEL CELL VEHICLE

• US 20040083039A1
• Filed: 04/16/2003
• Published: 04/29/2004
• Est. Priority Date: 10/23/2002
• Status: Active Grant

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Spiteri, Raymond, Hunt, Thomas Howard
• Granted Patent: US 6,792,341 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A power distribution control system for a hybrid fuel cell vehicle is provided. The system includes a high voltage energy converter (HVEC) for providing current from an electrical bus to the battery, or from the battery to the bus. As a vehicle load increases, the HVEC temporarily provides current to the bus from the battery. A feedforward signal is input into a fuel cell subsystem so that the fuel cell begins to generate additional current. As additional fuel cell current becomes available, an HVEC controller reduces the amount of current the HVEC provides to the bus from the battery, until there is a zero net current flow to and from the battery. At this point, a state of equilibrium is reached and the fuel cell provides all the current required by the vehicle loads.

Claims

1. A power distribution control system for a vehicle having a fuel cell and a second power source connected to an electrical bus, the control system comprising:

a voltage regulator configured to control voltage on the bus;

a first controller for controlling the voltage regulator, the first controller being configured to determine a voltage command and send the voltage command to the voltage regulator, the voltage command being related to a target current flow for the second power source, and further related to a target rate for reaching the target current flow; and

a second controller for controlling the fuel cell, the second controller being configured to provide a fuel cell current request to the fuel cell, and further configured to provide an input to the first controller, the input being related to available fuel cell current.

2. The control system of claim 1, further comprising a gain scheduler for selectively applying a gain to signals from the second controller.

3. The control system of claim 1, further comprising a computer programmed and configured to execute control algorithms, the control algorithms including the first controller and the second controller.

4. The control system of claim 3, wherein the computer is further programmed and configured with an adaptive polarization curve function, the adaptive polarization curve function being configured to develop an equilibrium relationship between fuel cell current and fuel cell voltage, and further configured to output a signal to modify the voltage command from the first controller.

5. The control system of claim 1, wherein the second power source is one of a nickel metal hydride battery, a lead acid battery, and an ultra-capacitor.

6. The control system of claim 1, further comprising a resistor in selective electrical communication with the voltage regulator, the resistor being configured to selectively receive current through the voltage regulator.

7. The control system of claim 1, wherein the voltage regulator and the fuel cell are disposed on the bus such that all vehicle electrical loads connect to the bus between the voltage regulator and the fuel cell.

8. The control system of claim 1, further comprising a third controller, the third controller being configured to generate the target current flow.

9. The control system of claim 8, wherein the target rate is an actual rate of change of available fuel cell current.

10. A method of controlling the power distribution in a vehicle having a fuel cell and a second power source connected to an electrical bus, the method comprising:

adjusting current flow of the second power source a first time at least partly based on a vehicle electrical load change;

adjusting available fuel cell current at least partly based on the vehicle electrical load change; and

continuously adjusting the current flow of the second power source until an equilibrium point is reached, the continuous adjustment being at least partly based on an actual rate of change of the available fuel cell current.

11. The method of claim 10, wherein the equilibrium point is reached when the current flow of the second power source is a predetermined constant.

12. The method of claim 10, wherein the first adjustment of the current flow compensates for the electrical load change, thereby maintaining a substantially constant voltage on the electrical bus.

13. The method of claim 10, further comprising determining a first error signal, the first error signal being the difference between the available fuel cell current and fuel cell current used.

14. The method of claim 13, wherein the continuous adjustment of the current flow comprises generating a first voltage command when the first error signal is within a predetermined tolerance band, and generating a second voltage command when the first error signal is outside the predetermined tolerance band.

15. The method of claim 14, wherein the first voltage command is at least partly based on a second error signal, the second error signal being the difference between a measured current and a requested current.

16. The method of claim 14, wherein the first and second voltage commands are partly based on a polarization curve.

17. The method of claim 14, further comprising applying a selectable gain to the first error signal.

18. The method of claim 10, wherein the continuous adjustment of the current flow comprises determining voltage commands to facilitate a constant current flow, and applying the voltage commands such that a rate of change of current flow is substantially equal to the rate of change of available fuel cell current.

19. A vehicle having a fuel cell and a second power source connected to an electrical bus, and a power distribution system for controlling the distribution of power in the vehicle, the power distribution system comprising:

a voltage regulator configured to control voltage on the bus;

a first controller for controlling the voltage regulator, the first controller being configured to determine a voltage command and send the voltage command to the voltage regulator, the voltage command being related to a target current flow for the second power source, and further related to a target rate for reaching the target current flow; and

a second controller for controlling the fuel cell, the second controller being configured to provide a fuel cell current request to the fuel cell, and further configured to provide an input to the first controller, the input being related to available fuel cell current.

20. A computer programmed and configured to execute control algorithms for controlling the power distribution system in a vehicle, the vehicle having a fuel cell and a second power source, the computer comprising:

an algorithm for adjusting current flow of the second power source a first time in response to a vehicle electrical load change, an algorithm for adjusting available fuel cell current at least partly based on the vehicle electrical load change, and an algorithm for continuously adjusting the current flow of the second power source until an equilibrium point is reached, the continuous adjustment of the current flow being at least partly based on an actual rate of change of the available fuel cell current.