Controller and method for balancing discharge or charge of battery packs in energy storage system

Patent metadata

Field	Value
Publication number	US-12149083-B2
Application number	US-202117506153-A
Country	US
Kind code	B2
Filing date	Oct 20, 2021
Priority date	Oct 20, 2021
Publication date	Nov 19, 2024
Grant date	Nov 19, 2024

Abstract

A controller, a system including such a controller, and a method for controlling or managing discharge or charge of a plurality of battery packs are provided. The controller includes one or more processor and at least one tangible, non-transitory machine readable medium encoded with one or more programs configured to perform steps to determine a respective power discharge or charge for each battery packs based on characteristic data of each battery pack, a power demand, and the first weighting factor (a) and the second weighting factor (b) for power assignment based on voltage and state of charge of each battery pack. The controller provides signals with instructions to the plurality of battery packs and/or the one or more power converters for discharging power from or charging power to the plurality of battery packs.

First claim

What is claimed is:

1. A system, comprising:
a plurality of battery packs;
one or more power converters, each power converter coupled with at least one of the plurality of battery packs and configured to convert direct current (DC) from one battery pack to alternating current (AC) or vice versa; and
a controller coupled to the plurality of battery packs and the one or more power converters, the controller comprising one or more processor and at least one tangible, non-transitory machine readable medium encoded with one or more programs configured to perform steps comprising:
collecting characteristic data of each battery pack including a present voltage (V i ), state of charge (SOC i ), a number of cells in each battery packs (Nc), a maximum voltage (V c max ) and a minimum voltage (V c min ) of a cell;
receiving a total power demand (D) needed to be dispatched from the system or to be charged to the system in a first time interval;
assigning a first weighting factor (a) and a second weighting factor (b) for power assignment based on voltage and state of charge of each battery pack, respectively, wherein a+b=1;
determining a respective power discharge or charge for each battery pack based on the present voltage (V i ), the state of charge (SOC i ), the number of cells in each battery packs (Nc), the maximum voltage (V c max ) and the minimum voltage (V c min ) of a cell, the first weighting factor (a), the second weighting factor (b), and the total power demand (D); and
providing signals with instructions to the plurality of battery packs and the one or more power converters for discharging power from or charging power to the plurality of battery packs based on the respective power discharge or charge of each battery pack and/or keeping a certain battery pack idle.

2. The system of claim 1 , wherein the step of determining a respective power discharge or charge for each battery pack comprises:
calculating voltage distribution parameter (V i ′) for each cell in a respective battery pack, wherein V i ′=(V i /N ci −V c min )/(V c max −V c min );
setting a baseline SOC (SOC b ) for each of the plurality of battery packs;
calculating a variation of state of charge (SOC i ′) for each battery pack by using conditions and equations including:
for discharge (D<0), when SOC i >SOC b , SOC i ′=SOC i −SOC b and when
SOC i ≤SOC b , SOC i ′=0; or
for charge (D>0), when SOC i <SOC b , SOC i ′=SOC b −SOC i and when
SOC i ≥SOC b , SOC i ′=0;

calculating a voltage-charge combination factor (C i ) of each battery pack, wherein C i is defined as C i =a*V i ′+b*SOC i ′; and
calculating a respective power discharge or charge (di) for each battery pack based on the total power demand (D) and the voltage-charge combination factor (C i ) of each battery pack, wherein d i =D*C i /Sum (C i ), and Sum (C i ) is a sum of the voltage-charge combination factor of (C i ) of each of the plurality of battery packs.

3. The system of claim 1 , wherein the controller is configured to repeat the steps to re-determine the respective power discharge or charge for each battery pack in a second time interval after the first time interval ends.

4. The system of claim 1 , wherein the plurality of battery packs are heterogeneous battery packs selected from new batteries, second-use electric vehicle (EV) batteries, or combinations thereof.

5. The system of claim 1 , further comprising one or more battery power management unit (BPMU), each BPMU connected with one or more battery packs and configured to monitor the one or more battery packs and provide characteristic data of the one or more battery packs to the controller.

6. The system of claim 1 , wherein the system is an electrical energy storage system, and the total power demand is provided from an upper level energy management system.

7. A controller for controlling discharge or charge of a system comprising a plurality of battery packs, comprising one or more processor and at least one tangible, non-transitory machine readable medium encoded with one or more programs configured to perform steps of:
collecting characteristic data of each battery pack including a present voltage (V i ), state of charge (SOC i ), a number of cells in each battery packs (Nc), a maximum voltage (V c max ) and a minimum voltage (V c min ) of a cell;
receiving a total power demand (D) needed to be dispatched from the system or to be charged to the system in a first time interval;
assigning a first weighting factor (a) and a second weighting factor (b) for power assignment based on voltage and state of charge of each battery pack, respectively, wherein a+b=1;
determining a respective power discharge or charge for each battery pack based on the present voltage (V i ), the state of charge (SOC i ), the number of cells in each battery packs (N ci ), the maximum voltage (V c max ) and the minimum voltage (V c min ) of a cell, the first weighting factor (a), the second weighting factor (b), and the total power demand (D); and
providing signals with instructions to the plurality of battery packs and one or more power converters for discharging power from or charging power to the plurality of battery packs based on the respective power discharge or charge of each battery pack and/or keeping a certain battery pack idle.

8. The controller of claim 7 , wherein the controller is configured to determine a respective power discharge or charge for each battery pack through steps comprising:
calculating voltage distribution parameter (V i ′) for each cell in a respective battery pack, wherein V i ′=(V i /N ci −V c min )/(V c max −V c min );
setting a baseline SOC (SOC b ) for each of the plurality of battery packs;
calculating a variation of state of charge (SOC i ′) for each battery pack by using conditions and equations including:
for discharge (D<0), when SOC i >SOC b , SOC i ′=SOC i −SOC b and when
SOC i ≤ SOC b , SOC i ′=0; or
for charge (D>0), when SOC i <SOC b , SOC i ′=SOC b −SOC i and when
SOC i ≥ SOC b , SOC i ′=0;

calculating a voltage-charge combination factor (C i ) of each battery pack, wherein C i is defined as C i =a*V i ′+b*SOC i ′; and
calculating a respective power discharge or charge (d i ) for each battery pack based on the total power demand (D) and the voltage-charge combination factor (C i ) of each battery pack, wherein d i =D*C i /Sum (C i ), and Sum (C i ) is a sum of the voltage-charge combination factor of (C i ) of each of the plurality of battery packs.

9. The controller of claim 7 , wherein the controller is configured to repeat the steps to re-determine the respective power discharge or charge for each battery pack in a second time interval after the first time interval ends.

10. The controller of claim 7 , wherein the controller is configured to discharge power from the plurality of battery packs to a grid or load, or charge power from the grid or load to the plurality of battery packs.

11. A method for controlling discharge or charge of a system comprising a plurality of battery packs through a controller therein, comprising:
collecting characteristic data of each battery pack including a present voltage (V i ), state of charge (SOC i ), a number of cells in each battery packs (Nc), a maximum voltage (V c max ) and a minimum voltage (V c min ) of a cell;
receiving a total power demand (D) needed to be dispatched from the system or to be charged to the system in a first time interval;
assigning a first weighting factor (a) and a second weighting factor (b) for power assignment based on voltage and state of charge of each battery pack, respectively, wherein a+b=1;
determining a respective power discharge or charge for each battery pack based on th

Assignees

• China Energy Investment Corp Ltd
• Nat Inst Clean & Low Carbon Energy

Inventors

• Sharma Ratnesh
• Singh Surinder
• Ohara Brandon
• Furukawa Motoko
• Keyes Roger

Classifications

• H02J2105/37

  exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H02J7/52

  for charge balancing, e.g. equalisation of charge between batteries · CPC title

• H02J7/84

  Control of state of health [SOH] · CPC title

• H02J7/50

  acting upon multiple batteries simultaneously or sequentially · CPC title