BALANCING ENERGY IN A PARALLELIZED BATTERY SYSTEM

• US 20200130512A1
• Filed: 10/24/2018
• Published: 04/30/2020
• Est. Priority Date: 10/24/2018
• Status: Active Grant

• Current Assignee: Proterra Powered LLC
• Original Assignee: Proterra AG
• Inventors: SCHEPMANN, Seneca
• Granted Patent: US 10,744,899 B2
• Time in Patent Office: Days
• CPC Class Codes: B60L 2200/18 Buses
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 50/66 Arrangements of batteries
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A method for balancing energy in an energy storage system of an electric vehicle includes detecting a first voltage of a first energy storage unit (ESU) and a second voltage of a second energy storage unit of the energy storage system, and determining a discharge time corresponding to the detected second voltage. The method may also include discharging energy from the first energy storage unit, while not discharging energy from the second energy storage unit, for a duration of the determined discharge time.

Claims

1. A method for balancing energy in an energy storage system of an electric vehicle, the energy storage system including a plurality of energy storage units (ESUs), the method comprising:

detecting a first voltage of a first ESU of the plurality of ESUs and a second voltage of a second ESU of the plurality of ESUs, wherein when the first voltage is higher than the second voltage;

determining a discharge time corresponding to the detected second voltage; and

discharging energy from the first ESU, while not discharging energy from the second ESU, for a duration of the determined discharge time.

2. The method of claim 1, further including directing energy from a power bus to the second ESU for the duration of the determined discharge time.

3. The method of claim 1, wherein discharging energy from the first ESU includes simultaneously directing energy to the second ESU.

4. The method of claim 1, wherein the plurality of ESUs are connected in parallel to a power bus.

5. The method of claim 1, further including detecting a third voltage of a third ESU of the plurality of ESUs and, when the third voltage has a magnitude between the first voltage and the second voltage, determining a second discharge time corresponding to the detected third voltage.

6. The method of claim 5, wherein discharging energy from the first includes not discharging energy from the third ESU for a duration of the determined second discharge time.

7. The method of claim 6, further including discharging energy from the third ESU after the duration of the determined second discharge time.

8. The method of claim 1, further including discharging energy from the second ESU after the duration of the determined discharge time.

9. The method of claim 1, wherein determining a discharge time corresponding to the detected second voltage includes determining the discharge time from a map that correlates different voltages to different discharge times.

10. The method of claim 1, wherein the electric vehicle is an electric bus.

11. A method for balancing energy in an energy storage system of an electric vehicle, the energy storage system including at least a first, a second, and a third energy storage unit (ESU) configured to be electrically connected in parallel, the method comprising:

detecting a first voltage of the first ESU, a second voltage of the second ESU, and a third voltage of the third ESU, wherein when the first voltage is higher than the second voltage and the second voltage is higher than the third voltage;

determining a second discharge time corresponding to the detected second voltage and a third discharge time corresponding to the third voltage; and

discharging energy from the first ESU, while not discharging energy from the second ESU and the third ESU, for a duration of the determined second discharge time.

12. The method of claim 11, further including discharging energy from the second ESU, while not discharging energy from the third ESU, after the duration of the determined second discharge time.

13. The method of claim 11, further including discharging energy from the third ESU after the duration of the determined third discharge time.

14. The method of claim 11, wherein discharging energy from the first ESU includes directing energy to the third ESU.

15. The method of claim 11, wherein determining the second discharge time and the third discharge time includes determining the second and third discharge times from a map that correlates different voltages to different discharge times.

16. The method of claim 11, wherein the electric vehicle is a heavy duty electric vehicle.

17. An electric vehicle, including:

an energy storage system including a plurality of energy storage units (ESUs) electrically connected in parallel;

one or more traction motors configured to be powered by the energy storage system; and

a controller configured to (a) detect a voltage of a first ESU of the plurality of ESUs, (b) determine a discharge time corresponding to the detected voltage, and (c) not discharge energy from the first ESU for a duration of the determined discharge time.

18. The electric vehicle of claim 17, wherein the controller is a first controller and the electric vehicle further includes a second controller configured to (a) detect a second voltage of a second ESU of the plurality of ESUs, (b) determine a second discharge time corresponding to the detected second voltage, and (c) not discharge energy from the second ESU for a duration of the determined second discharge time.

19. The electric vehicle of claim 18, wherein the first controller and the second controller are the same or part of a single control system.

20. The electric vehicle of claim 18, wherein the first controller is different from, and not operably connected to, the second controller.