System and Method for Dual Energy Storage Management

• US 20090212626A1
• Filed: 02/12/2009
• Published: 08/27/2009
• Est. Priority Date: 02/26/2008
• Status: Active Grant

• Current Assignee: AFS Trinity Power Corporation
• Original Assignee: AFS Trinity Power Corporation
• Inventors: Bender, Donald, Snyder, Philip Kenneth
• Granted Patent: US 8,138,720 B2
• Time in Patent Office: Days
• US Class Current: 307/10.100
• CPC Class Codes: B60K 6/105 the accumulator being a flywheel
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• CPC Class Codes: B60K 6/448 Electrical distribution type
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60K 6/52 Driving a plurality of drive axles, e.g. four-wheel drive
• CPC Class Codes: B60L 15/209 for overtaking
• CPC Class Codes: B60L 2220/20 DC electrical machines
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/40 : Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A dual-energy storage system is described, having two energy sources: (a) a fast-energy storage devices (FES) such as an ultracapacitor, and (b) a long duration or steady power device, such as a fuel-cell or battery. A power converter or controller executes an energy management algorithm to determine when to provide bursts of additional power/current from the fast-energy storage device, and when to recharge the fast-energy storage device.

A method is further described of adaptively managing the state of charge of an ultracapacitor or other Fast Energy Storage device in the dual energy storage system of a Plug-in Hybrid propulsion system. The method provides good protection of the battery, good performance, and minimizes the required capacity of the ultracapacitor.

Claims

1. A method of controlling power distribution, comprising:

determining a load current drawn by a load;

estimating an estimated. battery current to be supplied from a battery to the load, based on the load current;

determining a transient current required from a fast energy storage to the load based on the estimated battery current and the load current; and

controlling discharge of the transient current from the fast energy storage to the load.

2. The method of claim 1, further comprising recharging the fast energy storage if the load current is below a predetermined level.

3. The method of claim 1, wherein the estimating further comprises filtering the load current to generate the estimated battery current.

4. The method of claim 1, further comprising limiting the estimated battery current to a maximum threshold value.

5. The method of claim 3, wherein if the estimated battery current remains near the maximum threshold value for more than a predetermined period of time, reducing the estimated battery current to lower threshold value below the maximum threshold value.

6. The method of claim 3, further comprising recharging the fast energy storage if the load current is below the lower threshold value.

7. The method of claim 1, wherein at least one of the estimating, determining, or controlling occur at a power controller.

8. The method of claim 1, wherein the method is performed at a universal power supply (UPS).

9. The method of claim 1, wherein the method is performed at an at least partially electric vehicle.

10. The method of claim 1, wherein the method is performed at a lift power controller converter in a lift mechanism.

11. The method of claim 1, wherein determining the load current includes measuring energy associated with the load current at a sensor coupled to a poweltrain of a vehicle.

12. The method of claim 1, wherein determining the load current includes measuring a position of a throttle control, wherein the throttle control is configured to increase or decrease the load current to the load.

13. The method of claim 2, wherein the load current is filtered using a low-pass filter.

14. The method of claim 1, wherein estimating the estimated battery current includes estimating a safe battery current that a battery can provide without damaging the battery.

15. The method of claim 1, wherein the transient current is a difference between the load current and the estimated battery current.

16. The method of claim 1, further comprising reducing the load current when the fast energy storage reaches a minimum charge.

17. The method of claim 16, further comprising limiting the estimated battery current drawn from the battery to a maximum battery current level.

18. The method of claim 17, further comprising varying the maximum battery current level in response to a temperature of the battery.

19. The method of claim 1, further comprising upon reaching a low charge state of the fast energy storage, gradually reducing the transient current from the fast energy storage to protect the fast energy storage from damage.

20. The method of claim 1, wherein the controlling includes sending a discharge command to a power converter controller to manage a flow of electrical energy from the fast energy storage and the battery.

21. The method of claim 1, further comprising analyzing the load current and determining when a steady state has been reached, and determining an estimated recharge current to be supplied to the fast energy storage by the battery, based on the steady state.

22. The method of claim 21, further comprising monitoring a state of charge of the fast energy storage and gradually reducing the estimated recharge current to be supplied by the battery, to protect the fast energy storage from damage.

23. The method of claim 22, further comprising sending a recharge command to a power converter controller, wherein the power converter controller manages a flow of electrical energy between the fast energy storage and the battery.

24. The method of claim 21, wherein determining when a steady state has been reached includes comparing the transient current to a seek band, wherein the seek band specifies a range of transient current in which the fast energy storage will be recharged.

25. The method of claim 21, wherein analyzing the load current includes determining if the load is stopped or operating in a steady state, and if the load is stopped, controlling the recharge current to charge the fast energy storage to the maximum charge, and if the load is operating in a steady state, controlling the recharge current to charge the fast energy storage to below the maximum charge.

26. A computer readable storage medium storing one or more programs configured for execution by one or more processors, the one or more programs comprising instructions to:

determine a load current drawn by a load;

estimate an estimated battery current to be supplied from a battery to the load, based on the load current;

determine a transient current required from a fast energy storage to the load based on the estimated battery current and the load current; and

control discharge of the transient current from the fast energy storage to the load.

27. A method of adaptively controlling a load driven by a system that includes a battery and a fast energy storage, the method comprising:

determining a load current drawn by the load;

determining an estimated battery current by filtering the load current;

bounding the estimated battery current to an upper first threshold value; and

bounding the estimated battery current to a lower second threshold value.

28. The method of claim 27, further comprising limiting a maximum current drawn from the battery to the upper first threshold value, if the current drawn by the load is above the upper first threshold value for a period of time.

29. The method of claim 27, further comprising recharging the fast energy storage if the load current is below the lower second threshold value.

30. The method of claim 27, further comprising determining a transient current required from the fast energy storage to the load based on the estimated battery current, and controlling discharge of the transient current from the fast energy storage to the load.

31. A computer readable storage medium storing one or more programs configured for execution by one or more processors, the one or more programs comprising instructions to adaptively control power distribution in a system that includes a battery and a fast energy storage, comprising instructions to:

determine a load current drawn by the load;

determine an estimated battery current by filtering the load current;

bound the estimated battery current to an upper first threshold value; and

bound the estimated battery current to a lower second threshold value.