Connecting electrical storage devices in parallel

Patent metadata

Field	Value
Publication number	US-9853465-B2
Application number	US-201213402622-A
Country	US
Kind code	B2
Filing date	Feb 22, 2012
Priority date	Feb 23, 2011
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A circuit and a method for connecting a first electrical storage device and a second electrical storage device in parallel is disclosed. The first electrical storage device and the second electrical storage device have in each case a no-load voltage U Bat1 , U Bat2 and an impedance R 1 and R 2 , respectively, and have connecting terminals for charge withdrawal or charge supply. The no-load voltage U Bat1 of the first storage device is greater than the no-load voltage U Bat2 of the second storage device. In the case of a charge withdrawal, a charge is initially only withdrawn from the first storage device and the second storage device is connected in parallel with the first storage device when the difference of the voltage dropped across the connecting terminals of the first storage device and the no-load voltage U Bat2 of the second storage device is less than a predetermined differential add-on voltage.

First claim

What is claimed is:

1. A method for connecting a first electrical storage device and a second electrical storage device in parallel:
wherein the first electrical storage device and the second electrical storage device have a no-load voltage and an impedance, respectively;
wherein the first electrical storage device is connected to connecting terminals for charge withdrawal or charge supply via two first electrical conductors, wherein an electrical connection between the first electrical storage device and one of the connecting terminals is establishable or interruptible by a first switch;
wherein the second electrical storage device is connected to the connecting terminals via two second electrical conductors, wherein an electrical connection between the second electrical storage device and one of the connecting terminals is establishable or interruptible by a second switch;
wherein when the first switch is open the electrical connection between the first electrical storage device and one of the connecting terminals is completely interrupted and wherein when the second switch is open the electrical connection between the second electrical storage device and one of the connecting terminals is completely interrupted;
wherein when an initial no-load voltage of the first storage device is greater than an initial no-load voltage of the second storage device;
comprising the steps of:
during a charge withdrawal:
the electrical connection between the first electrical storage device and the one of the connecting terminals is established by the first switch and the electrical connection between the second electrical storage device and the one of the connecting terminals is interrupted by the second switch so that initially charge is withdrawn only from the first electrical storage device;
the electrical connection between the second storage device and the one of the connecting terminals is established by the second switch when a difference between a terminal voltage of the first electrical storage device and the no-load voltage of the second electrical storage device is less than a predetermined differential add-on voltage;
wherein during the charge withdrawal when both electrical storage devices are connected, the second electrical storage device is separated from the first electrical storage device and from a load when a net current from the second electrical storage device does not exceed a certain discharge amount; and
wherein the predetermined differential add-on voltage is V d <I max *R, where I max represents a lower value of a maximum permissible current during an adding or turning-off of the second electrical storage device and of a maximum current which may be permissibly withdrawn from the first and/or second electrical storage device, and R represents an impedance of the electrical storage devices effective after the first and the second electrical storage devices have been connected in parallel.

2. The method according to claim 1 :
wherein during a charge supply, when the initial no-load voltage is greater than the initial no-load voltage:
the electrical connection between the second electrical storage device and the one of the connecting terminals is established by the second switch and the electrical connection between the first electrical storage device and the one of the connecting terminals is interrupted by the first switch so that initially only the second electrical storage device is supplied with a charge; and
the electrical connection between the first electrical storage device and the one of the connecting terminals is established by the first switch when a difference of a terminal voltage of the second electrical storage device and the no-load voltage of the first electrical storage device is less than the predetermined differential add-on voltage.

3. The method according to claim 1 , wherein the first or the second electrical storage device have several electrical storage devices connected in parallel.

4. The method according to claim 1 , wherein when more than two electrical storage devices are connected in parallel, the predetermined differential add-on voltage is adapted to an effective impedance of the parallel connected electrical storage devices.

5. The method according to claim 2 , wherein the differential add-on voltage of an equal amount is selected in the charge withdrawal and the charge supply.

6. The method according to claim 2 , wherein in the charge withdrawal, the charge withdrawn from the first electrical storage device per unit time is kept constant while the second electrical storage device is connected in parallel with the first electrical storage device, and wherein in the charge supply, the charge supplied to the second electrical storage device per unit time is kept constant while the first electrical storage device is connected in parallel with the second electrical storage device.

7. The method according to claim 6 , wherein signals are exchanged with a load circuit for controlling a load or source, and wherein during a charge withdrawal the charge withdrawn from the first electrical storage device per unit time is kept constant in dependence on the signals, and wherein during a charge supply the charge supplied to the second electrical storage device per unit time is kept constant in dependence on the signals.

8. The method according to claim 2 , wherein the second electrical storage device is separated from the first electrical storage device and from the load when a terminal voltage of the second electrical storage device deviates from the initial no-load voltage of the second electrical storage device by less than a predetermined differential turn-off voltage.

9. The method according to claim 8 , wherein the predetermined differential turn-off voltage differs from the differential add-on voltage.

10. The method according to claim 9 , wherein during the charge withdrawal, the predetermined differential turn-off voltage is greater than the predetermined differential add-on voltage and during the charge supply, the predetermined differential turn-off voltage is lower than the predetermined differential add-on voltage.

11. The method according to claim 10 , wherein the predetermined differential add-on voltage and the predetermined differential turn-off voltage have a same amount but different signs.

12. The method according to claim 8 , wherein the separation only takes place when a total current no longer exceeds a permissible current of the first electrical storage device.

13. The method according to claim 1 , wherein the first and/or second electrical storage device are/is a battery.

14. An electrical circuit, comprising:
a first electrical storage device;
a second electrical storage device;
wherein the first electrical storage device is connected to connecting terminals for charge withdrawal or charge supply via two first electrical conductors, wherein a first switch is provided in one of the first electrical conductors which interrupts or establishes an electrical connection between the first electrical storage device and the connecting terminals;
wherein the second electrical storage device is connected to the connecting terminals via two second electrical conductors, wherein a second switch is provided in one of the second electrical conductors which interrupts or establishes an electrical connection between the second electrical storage device and the connecting terminals;
wherein when the first switch is open the electrical connection between the first electrical storage device and the connecting terminals is completely interrupted and wherein when the second switch is open the e

Assignees

• Biebach Jens
• Boebel Friedrich
• Torqeedo Gmbh

Inventors

• Biebach Jens
• Boebel Friedrich

Classifications

• H02J7/575 Primary

  Parallel/serial switching of connection of batteries to charge or load circuit · CPC title

• H02J7/0024 Primary

  Electricity · mapped topic

• H01M10/441

  for several batteries or cells simultaneously or sequentially · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title