Autonomous battery control and optimization

Patent metadata

Field	Value
Publication number	US-10277041-B2
Application number	US-201615224123-A
Country	US
Kind code	B2
Filing date	Jul 29, 2016
Priority date	Jan 7, 2014
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

An apparatus includes a battery state module that determines a battery state of each of a plurality of battery cells forming a battery unit. A battery state includes a health of the battery cell. A battery state of a battery cell differs from a battery state of other battery cells of the battery unit. Each battery cell is connected to a shared bus through a bypass converter that provides power from the battery cell to the shared bus. A charge/discharge modification module determines, based on battery state, an amount to vary a charging characteristic for each battery cell compared to a reference charging characteristic. Each charging characteristic varies as a function of a reference state. A charge/discharge module adjusts charging/discharging of a battery cell of the battery unit based on the charging characteristic of the battery cell.

First claim

What is claimed is:

1. An apparatus comprising:
a battery state module that determines a battery state of each battery cell of a plurality of battery cells forming a battery unit, a battery state of a battery cell comprising a health of the battery cell, wherein a battery state of at least one battery cell of the battery unit differs from a battery state of one or more other battery cells of the battery unit, each battery cell is connected in parallel to a shared bus through a bypass converter, each bypass converter comprising a direct current (“DC”)-to-DC converter, each bypass converter providing power from the battery cell to the shared bus;
a charge/discharge modification module that determines, based on the determined battery state of each battery cell of the battery unit, an amount to vary a charging characteristic for each battery cell of the battery unit with respect to a reference charging characteristic, wherein the charging characteristic for each battery cell varies as a function of a reference state; and
a charge/discharge module that adjusts charging and discharging of a battery cell of the battery unit based on the charging characteristic of the battery cell by controlling the bypass converter connected to the battery cell, wherein the charge/discharge modification module populates an objective map for each battery cell of the battery unit, the objective map of a battery cell comprising a target state-of-charge for each value of the reference state between at least a maximum value of the reference state and a minimum value of the reference state.

2. The apparatus of claim 1 , wherein the reference state comprises one of voltage of the shared bus, a reference state-of-charge, a reference cell voltage, a reference cell open circuit voltage, a reference cell history, and a reference signal from an equation calculating one or more parameters of the reference state.

3. The apparatus of claim 1 , wherein each charging characteristic comprises a maximum target state-of-charge correlated to a maximum value of the reference state.

4. The apparatus of claim 3 , wherein the reference charging characteristic comprises a maximum target state-of-charge of a healthiest battery cell of the battery unit correlated to the maximum value of the reference state, wherein the maximum target state-of-charge of the healthiest battery cell is higher than the maximum target state-of-charge of the battery cells of the battery unit other than the healthiest battery cell.

5. The apparatus of claim 4 , wherein the maximum target state-of-charge of a battery cell is proportionally related to the maximum target state-of-charge of the healthiest battery cell based on battery state.

6. The apparatus of claim 1 , wherein the reference charging characteristic comprises a charging characteristic of an average battery cell, wherein each charging characteristic comprises a maximum target state-of-charge correlated to a maximum value of the reference state, wherein the maximum target state-of-charge of each battery cell is related to the maximum target state-of-charge of the average battery cell based on battery state compared to the battery state of the average battery cell.

7. The apparatus of claim 6 , wherein the charging characteristic of the average battery cell comprises one of:
an average battery state based on the battery states of each battery cell of the battery unit; and
a predetermined reference charging characteristic.

8. The apparatus of claim 1 , wherein each objective map comprises a same target state-of-charge for a transition value of the reference state, the transition value of the reference state comprising a value of the reference state between the minimum value of the reference state and the maximum value of the reference state.

9. The apparatus of claim 8 , further comprising a life control module that determines a maximum target state-of-charge for each battery cell based on the battery state of each battery cell compared to the reference charging characteristic and populates the objective map of each battery cell of the battery unit to have the same target state-of-charge at the transition voltage as the reference charging characteristic and to diverge in target state-of-charge from the reference charging characteristic as the reference state approaches the maximum value of the reference state.

10. The apparatus of claim 9 , wherein the objective map for each battery cell of the battery unit diverges linearly from the same target state-of-charge at the transition value of the reference state to the maximum target state-of-charge of each battery cell of the battery unit.

11. The apparatus of claim 8 , further comprising a power optimized balancing module that determines values for the objective map for a battery cell of the battery unit based on an internal resistance of the battery cell, wherein the target state-of-charge for a particular reference state below the transition value of the reference state is correlated to a battery cell voltage at or above a minimum battery cell voltage plus a voltage drop across the internal resistance of the battery cell at a maximum battery cell current.

12. The apparatus of claim 11 , wherein the power optimized balancing mode module determines a minimum target state-of-charge corresponding to the minimum value of the reference state based on the internal resistance of the battery cell, wherein the minimum target state-of-charge of the battery cell is determined to maintain the battery cell voltage at the minimum battery cell voltage, while the reference state is at the minimum value of the reference state, accounting for voltage drop across the internal resistance while current for the battery cell is at a maximum cell current, wherein the power optimized balancing mode module populates the objective map of the battery cell to transition linearly between the minimum target state-of-charge and the same target state-of-charge at the transition value of the reference state.

13. The apparatus of claim 1 , wherein the charge/discharge modification module determines the amount to vary the charging characteristic of a battery cell of the battery unit based on a current age of the battery cell and a target end-of-life age of a reference battery cell associated with the reference charging characteristic and a difference between a capacity of the battery cell and the reference battery cell at the current age of the battery cell and the reference battery cell.

14. The apparatus of claim 13 , wherein the charge/discharge modification module adjusts a maximum target state-of-charge of the battery cell to minimize a projected difference between the capacity of the battery cell and the capacity of the reference battery cell at the target end-of-life age of the reference battery cell.

15. The apparatus of claim 1 , wherein the charge/discharge module of a battery cell of the battery unit controls the bypass converter for the battery cell to adjust charging and discharging the battery cell based on the charging characteristic of the battery cell.

16. The apparatus of claim 15 , wherein the bypass converter comprises at least one dual active bridge converter stage.

17. The apparatus of claim 15 , wherein each bypass converter is controlled by a separate charge/discharge module and autonomously controls charging and discharging of the connected battery cell independent of other bypass converters and associated charge/discharge modules of other battery cells of the battery unit, wherein each charge/discharge module adjusts charging and discharging based on the charging charact

Assignees

• Univ Utah State
• Ford Global Tech Llc
• Alliance Sustainable Energy
• The Regents Of The Univ Of Colorado A Body
• Univ Colorado Regents

Inventors

• Zane Regan A
• Evzelman Michael
• Costinett Daniel
• Maksimovic Dragan
• Anderson Richard Dyche
• Smith Kandler
• Trimboli Michael Scott
• Plett Gregory L

Classifications

• H02J7/865

  Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence) · CPC title

• H02J7/84

  Control of state of health [SOH] · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H02J7/54

  Passive balancing, e.g. using resistors or parallel MOSFETs · CPC title

• H02J7/00

  Circuit arrangements for charging or discharging batteries or for supplying loads from batteries · CPC title