CELL BALANCING MODULE, VOLTAGE BALANCER DEVICE, AND METHOD FOR VOLTAGE BALANCING, PARTICULARLY FOR VOLTAGE BALANCING OF A STACK OF BATTERIES

• US 20140035532A1
• Filed: 02/14/2012
• Published: 02/06/2014
• Est. Priority Date: 02/15/2011
• Status: Active Grant

• Current Assignee: ams AG (Ams-Osram AG)
• Original Assignee: ams AG (Ams-Osram AG)
• Inventors: Brandl, Manfred, Vernekar, Sandeep, Ele, Vijay, Singamala, Sudhakar, Babu, V. Veeresh
• Granted Patent: US 9,647,463 B2
• Time in Patent Office: Days
• US Class Current: 320/128
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• 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 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• 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

The invention relates to a cell balancing module, particularly for voltage balancing of a stack of batteries. The cell balancing module comprises an interface (SPI, VrefH, VrefL) to input a coded reference voltage (Vref) and input nodes (In1, . . . , InN) for connecting a stack of energy storage cells (BAT1, . . . , BATn). A switching unit (SW) is connected to each of the input nodes (In1, . . . , InN) and a local balancing unit (loc) coupled to the switching unit (SW) and the interface (SPI, VrefH, VrefL). The local balancing unit (loc) is designed to compare the coded reference voltage (Vref) with cell voltages (VBAT1, . . . , VBATn) of the stack of energy storage cells (BAT1, . . . , BATn) to be connected and to charge balance the stack of energy storage cells (BAT1, . . . , BATn) to be connected depending on the comparison of coded reference voltage (Vref) and cell voltages (VBAT1, . . . , VBATn). The invention also relates to a voltage balancing device and method for cell balancing, particularly for voltage balancing of a stack of batteries.

Claims

1. A cell balancing module, particularly for voltage balancing of a stack of batteries, comprising:

an interface to input a coded reference voltage derived from at least two reference voltages;

input nodes for connecting a stack of energy storage cells;

a switching unit connected to each of the input nodes; and

a local balancing unit which is coupled to the switching unit and to the interface and which is designed to compare the coded reference voltage with cell voltages of the stack of energy storage cells to be connected, and designed to charge balance by charging or discharging the stack of energy storage cells to be connected depending on the comparison of the coded reference voltage and the cell voltages.

2. The cell balancing module according to claim 1, wherein the interface is a serial interface, in particular a serial peripheral interface.

3. The cell balancing module according to claim 1 or 2, wherein the local balancing unit comprises:

at least one comparator which is coupled to the switching unit via a first input for comparison of the coded reference voltage, to be provided at a second input of the at least one comparator, and the cell voltages of the stack of energy storage cells to be connected; and

a control logic which is connected to the interface, to an output of the at least one comparator and to the switching unit in which the control logic controls the switching unit such as to electrically connect the cell voltages to the first input of the comparator, respectively.

4. The cell balancing module according to claim 3, wherein the local balancing unit comprises a digital-to-analog converter,

which is connected to the second input of the at least one comparator and connected to the control logic via a control channel, and

which is designed to convert the coded reference voltage into an analog local reference voltage to be provided at the second input of the at least one comparator, or

wherein the local balancing unit comprises an analog-to-digital converter,

which is coupled to the switching unit such as to convert the cell voltages into digital local cell voltages to be provided at the first input of the at least one comparator, and

which is controllably connected to the control logic.

5. The cell balancing module according to claim 1, further comprising means to synchronize operation of the local balancing unit depending on an external trigger signal to be applied via the interface.

6. The cell balancing module according to claim 1, wherein the interface comprises input and output means to establish a daisy chain connection to further cell balancing modules.

7. The cell balancing module according to claim 1, wherein the local balancing unit comprises means to derive an amount of charge balance of the stack of energy storage cells such as to determine, based on a balance voltage provided at the output of the at least one comparator, whether to charge or discharge the stack of energy storage cells.

8. A voltage balancer device, particularly for voltage balancing of a stack of batteries, comprising:

at least one cell balancing module according to claim 1; and

means for coding the coded reference voltage connected to the interface of at least one cell balancing module.

9. The voltage balancer device according to claim 8, wherein a number of n cell balancing modules are inter-connected by way of a daisy chain via their respective interfaces.

10. The voltage balancer device according to claim 9, wherein

a first cell balancing module is designed to be a master module in the daisy chain of n cell balancing modules,

the other cell balancing modules are designed to be slave modules, and

the daisy chain connection between the master module and slave modules is a serial interface, in particular based on the serial peripheral interface.

11. The voltage balancer device according to claim 10, wherein the master is designed to simultaneously

send the coded reference voltage to the slave modules via the daisy chain, and

synchronize charge balancing in the charge balancing modules by controlling the slave modules using the trigger signal to be applied via the respective interfaces.

12. The voltage balancer device according to one of claims 8 to 11, wherein charging nodes are connected

to a power converter to charge, or

to a resistor to discharge the stack of energy storage cells.

13. The voltage balancer device according to claim 9, wherein the means for coding a coded reference voltage comprise:

voltage measurement circuit designed to determine total system voltage of the stack of energy storage cells to be connected;

a further analog-to-digital converter connected to the voltage measurement circuit and designed to convert the total system voltage into a digital representation; and

a control unit connected to the further analog-to-digital converter and designed to code the coded reference voltage based on the digital representation and to be transmitted via the means for transmitting.

14. A method for voltage balancing, particularly for voltage balancing of a stack of batteries, comprising:

encoding a coded reference voltage from at least two reference voltages;

transmitting the coded reference voltage to at least one cell balancing module connected to a stack of energy storage cells;

comparing respective cell voltages of the stack of energy storage cells at the at least one balancing module to the coded reference voltage; and

charge balancing by charging or discharging such that the respective cell voltages are adjusted depending on the comparison between the respective stack voltages and the coded reference voltage.

15. The method for voltage balancing according to claim 14, further comprising synchronizing the transmission of the coded reference voltage to the at least one cell balancing module or further cell balancing modules and/or charge balancing with an external or internal trigger signal.