Distributed battery power electronics architecture and control

Patent metadata

Field	Value
Publication number	US-9368991-B2
Application number	US-201314066839-A
Country	US
Kind code	B2
Filing date	Oct 30, 2013
Priority date	Oct 30, 2012
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A battery pack having a plurality of battery pack modules, wherein each battery pack module includes a battery cell and a power converter. The power converters of the plurality of battery pack modules are connected in series to form a string of N battery pack modules such that the voltage across the N battery pack modules defines the output voltage of the battery pack. A controller regulates the output voltage of each battery cell or module power converter and the output voltage of the battery pack by independently controlling each battery cell module in accordance with variables such as state-of-charge (SOC), state-of-health (SOH) and temperature, capacity, and temperature of each individual battery cell module. The power converter may be used to measure impedance of the battery pack by adding a sinusoidal perturbation signal to a reference voltage of the cell battery pack module.

First claim

What is claimed is:

1. A battery pack, comprising:
a plurality of battery pack modules, each battery pack module comprising a battery cell and a power converter; and
a controller that regulates an output voltage of the battery pack by outputting a control signal to each power converter of each of the plurality of battery pack modules in accordance with each battery pack module's impedance as measured by adding a sinusoidal duty cycle perturbation signal (d ac ) at a frequency of interest (f p ) with a peak amplitude of D ac , to a DC duty cycle (D dc ) of each power converter of each of the plurality of battery pack modules,
wherein a power converter of each of the plurality of battery pack modules are connected in series to form a string of N battery pack modules, wherein each battery pack module is independently controlled by the controller, and wherein the voltage across the N battery pack modules defines the output voltage of the battery pack.

2. The battery pack of claim 1 , wherein a battery pack voltage reference value is determined by the controller in a constant voltage mode, wherein an initial voltage reference value for each battery pack module is determined by dividing the battery pack voltage reference value by a number of active battery pack modules in the battery pack, and wherein the initial voltage reference value for each battery pack module is used to regulate an output voltage of a respective battery pack module.

3. The battery pack of claim 2 , wherein a voltage loop multiplier is specified by the controller for each battery pack module, and wherein the voltage loop multiplier is used to adjust a state of charge (SOC) of each battery pack module.

4. The battery pack of claim 3 , wherein the voltage loop multiplier is determined by comparing the SOC of each battery pack module to a reference SOC value.

5. The battery pack of claim 4 , wherein the reference SOC value is determined by adding the SOC of each battery pack module and dividing a total by the number of active battery pack modules.

6. The battery pack of claim 4 , wherein a SOC multiplier is specified for each battery pack module to alter the charge rate or discharge rate of a respective battery pack module.

7. The battery pack of claim 2 , wherein an estimate of an impedance of each of the battery pack modules is performed by add a sinusoidal signal to the initial voltage reference value for each battery pack module.

8. The battery pack of claim 7 , wherein each sinusoidal signal applied to the initial voltage reference value for each battery pack module is shifted to cancel the sinusoidal signal in the output voltage.

9. The battery pack of claim 7 , wherein the impedance is used by the controller to determine a state of charge (SOC) and/or state of health (SOH) of each cell and battery pack module.

10. The battery pack of claim 1 , wherein a battery pack current reference value is determined by the controller in a constant current mode, wherein an initial current reference value for each battery pack module is determined by dividing the battery pack current reference value by a number of active battery pack modules in the battery pack, and wherein the initial current reference value for each battery pack module is used to regulate an output current of a respective battery pack module.

11. The battery pack of claim 10 , wherein a current loop multiplier is specified by the controller for each battery pack module, and wherein the current loop multiplier is used to adjust a state of charge (SOC) of each battery pack module.

12. The battery pack of claim 11 , wherein the current loop multiplier is determined by comparing the SOC of each battery pack module to a reference SOC value.

13. The battery pack of claim 12 , wherein the reference SOC value is determined by adding the SOC of each battery pack module and dividing a total by the number of active battery pack modules.

14. The battery pack of claim 12 , wherein a SOC multiplier is specified for each battery pack module to alter the charge rate or discharge rate of a respective battery pack module.

15. The battery pack of claim 1 , wherein the controller operates in a constant current charging mode until a battery cell voltage reaches a maximum, and wherein the controller thereafter operates in a constant voltage charging mode until a battery cell current falls below a minimum value.

16. The battery pack of claim 1 , wherein the power converter of each of the battery pack modules has the DC duty cycle value (D dc ) to produce a corresponding DC battery voltage V battery _ dc and DC battery current I battery _ dc .

17. The battery pack of claim 16 , wherein the perturbation frequency (f p ) is significantly lower than the switching frequency (f sw ) of the power converter to generate sinusoidal ripples superimposed over the power converter DC output voltage V o _ dc , DC battery voltage V battery _ dc and DC battery current I battery _ dc .

18. The battery pack of claim 16 , wherein a peak-to-peak value of the battery voltage (V battery-pp ) and the battery current (I battery-pp ) is measured to determine a battery impedance magnitude value at the given perturbation frequency (f p ).

19. The battery pack of claim 18 , wherein if there is a phase shift between the battery voltage and current and/or phase information, the following relationship is used to determine the phase of the battery impedance at f p :
∠ z battery =φ v −φ i

wherein φ v is a phase of the battery voltage and φ i is a phase of the battery current.

Assignees

• Univ Alabama
• Univ Alabama

Inventors

• Qahouq Jaber Abu

Classifications

• H02J7/56 Primary

  Active balancing, e.g. using capacitor-based, inductor-based or DC-DC converters · CPC title

• H02J2207/20

  Charging or discharging characterised by the power electronics converter · CPC title

• H02J7/00

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

• H02J7/667

  disconnection of loads if battery is not under charge, e.g. in vehicle if engine is not running · CPC title

• H02J7/0065 Primary

  Electricity · mapped topic