HYBRID ENERGY STORAGE SYSTEM

• US 20110084648A1
• Filed: 10/09/2009
• Published: 04/14/2011
• Est. Priority Date: 10/09/2009
• Status: Active Grant

• Current Assignee: Turntide Technologies, Inc.
• Original Assignee: Illinois Institute of Technology
• Inventors: Cao, Jian, Emadi, Ali
• Granted Patent: US 8,860,359 B2
• Time in Patent Office: Days
• US Class Current: 320/103
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 2220/10 Batteries in stationary systems, e.g. emergency power source in plant
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• 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 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A hybrid energy storage system for supplying power to an application with a fluctuating load profile, such as, for example, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, wind energy harvesting equipment and solar energy harvesting equipment. The hybrid energy storage system includes an ultra-capacitor electrically connected to a DC bus and a power source electrically connected to the DC bus via a controlled switch. The hybrid energy storage system further including a DC/DC converter connected between the power source and the ultra-capacitor, the DC/DC converter boosting a voltage of the power source to charge the ultra-capacitor. The DC/DC converter is preferably controlled to maintain a voltage of the ultra-capacitor at a higher value than the voltage of the power source.

Claims

1. A hybrid energy storage system comprising:

an ultra-capacitor electrically connected to a DC bus;

a power source electrically connected to the DC bus via a switch; and

a bi-directional DC/DC converter electrically connected between the ultra-capacitor and the power source.

2. The hybrid energy storage system of claim 1, further comprising a motor in electrical connection with the DC bus.

3. The hybrid energy storage system of claim 1, wherein the power source comprises a battery or a fuel cell.

4. The hybrid energy storage system of claim 1, wherein the switch comprises a powered diode.

5. The hybrid energy storage system of claim 1, wherein the hybrid energy storage system operates sequentially in a plurality of modes of operation including a low-power mode, a high-power mode, a controlled charging mode or a peak-power mode.

6. The hybrid energy storage system of claim 5, wherein the bi-directional DC/DC converter is controlled to maintain the ultra-capacitor at a voltage greater than a voltage of the power source.

7. The hybrid energy storage system of claim 6, wherein during the low-power mode the switch is off and the bi-directional DC/DC converter provides power to the DC bus.

8. The hybrid energy storage system of claim 6, wherein during the high-power mode the switch is on directly connecting the power source with the DC bus.

9. The hybrid energy storage system of claim 6, wherein during the peak-power mode the DC bus is at a voltage equal to a voltage of the ultra-capacitor and the bi-directional DC/DC converter operates in a boost mode.

10. The hybrid energy storage system of claim 5, wherein the controlled charging mode comprises a first phase and a second phase, wherein during the first phase a generated energy is conveyed to the ultra-capacitor and during the second phase the bi-directional DC/DC converter operates in a buck mode to convey the generated energy to the power source.

11. The hybrid energy storage system of claim 10, wherein the ultra-capacitor further comprises an ultra-capacitor voltage upper limit, during the controlled charging mode the hybrid energy storage system operates in the first phase when the ultra-capacitor is at a voltage that is less than the ultra-capacitor voltage upper limit, and the hybrid energy storage system operates in the second phase when the ultra-capacitor is at a voltage that is approximately equal to the ultra-capacitor voltage upper limit.

12. The hybrid energy storage system of claim 1, further comprising an input to charge at least one of the ultra-capacitor or the power source from a peripheral source.

13. The hybrid energy storage system of claim 12, wherein the peripheral source comprises an electrical grid, a solar panel, a back-up battery or a generator.

14. A method of powering a machine with a hybrid energy storage system, the method comprising the steps of:

powering the machine with an alternating combination of an ultra-capacitor and a power source;

transmitting power between the ultra-capacitor, the power source and the machine via a DC bus and a bi-directional DC/DC converter electrically connected between the power source and the ultra-capacitor; and

providing a direct electrical connection between the power source and the DC bus when a power demand of the machine is greater than a capacity of the bi-directional DC/DC converter.

15. The method of claim 14, wherein the machine comprises one of a propulsion load in a vehicle, a non-propulsion load in a vehicle, a robotic application, or an active power filter.

16. The method of claim 14, wherein a powered diode in a forward biased mode provides the direct electrical connection between the power source and the ultra-capacitor.

17. The method of claim 14, wherein the power source comprises a battery or a fuel cell.

18. The method of claim 14, further comprising the step of:

maintaining the ultra-capacitor at a voltage that is greater than a voltage of the power source.

19. The method of claim 14, further comprising the step of:

determining the power demand of the machine is less than or equal to the capacity of the bi-directional DC/DC converter;

determining the machine is not generating power to the DC bus; and

operating the hybrid energy storage system in a low-power mode, wherein in the low-power mode the bi-directional DC/DC converter operates in a boost mode supplying power to the DC bus.

20. The method of claim 14, further comprising the step of:

determining the power demand of the machine is greater than the capacity of the bi-directional DC/DC converter;

determining the machine is not generating power to the DC bus; and

operating the hybrid energy storage system in a high-power mode, wherein in the high-power mode a switch is on, directly connecting the power supply with the DC bus to power the machine.

21. The method of claim 14, further comprising the step of:

determining the machine is generating power to the DC bus;

determining the ultra-capacitor is at a voltage less than an ultra-capacitor voltage upper limit; and

operating the hybrid energy storage system in a controlled charging mode first phase, wherein the controlled charging mode first phase comprises directing power from the machine to the ultra-capacitor.

22. The method of claim 14, further comprising the step of:

determining the machine is generating power to the DC bus;

determining the ultra-capacitor is at a voltage approximately equal to an ultra-capacitor voltage upper limit; and

operating the hybrid energy storage system in a controlled charging mode second phase, wherein the controlled charging mode second phase comprises operating the bi-directional DC/DC converter in a buck mode to convey power from the machine to the power source.

23. The method of claim 14, further comprising the step of:

determining the ultra-capacitor is at a voltage greater than a voltage of the power source; and

operating the hybrid energy storage system in a peak-power mode, wherein during the peak-power mode a voltage at the DC bus is equal to the voltage of the ultra-capacitor and the bi-directional DC/DC converter operates in combination with the ultra-capacitor to provide a peak-power.

24. The method of claim 14, further comprising the step of:

determining the ultra-capacitor is at a voltage approximately equal to a voltage of the power source; and

operating the hybrid energy storage system in a high-power mode, wherein the high-power mode comprises turning the switch on to directly connect the power source with the DC bus.

25. The method of claim 14, further comprising the step of:

determining the ultra-capacitor is at a voltage less than a voltage of the power source; and

operating the hybrid energy storage system in a high-power mode, wherein the high-power mode comprises turning the switch on to directly connect the power source with the DC bus.

26. The method of claim 14, further comprising the step of:

operating the bi-directional DC/DC converter in a reverse direction to charge the power source from the ultra-capacitor.

27. The method of claim 14, further comprising the step of:

charging at least one of the ultra-capacitor or the power source from an electric grid.