A high efficiency bidirectional multicell battery balancer has been released by Linear Technology that equalises cell state of charge (SoC) in a series-connected battery stack.
The company advises that with its LTC3300-1, applications such as electric vehicles (EVs), plug-in hybrid EVs and large energy storage systems using cells with mismatched capacities are no longer as limited by low capacity cell in the stack.
This device is able to enhance battery performance by transferring charge to or from adjacent cells in order to bring mismatched cells into SoC balance within the stack.
By redistributing charge throughout the stack, lost capacity is compensated for, enabling faster charging and extending the run time and usable lifetime of the battery stack.
A key component in of the device is a high performance battery management system (BMS) for series-connected Li-Ion or LiFePO4 batteries. The device operates as a fault-protected controller IC for transformer-based bidirectional active balancing. The part utilises a nonisolated bidirectional synchronous flyback topology to balance up to six series-connected cells.
Charge can be transferred between a selected cell and 12 or more adjacent cells. All balancers can operate independently and simultaneously with charge/discharge currents up to 10A. Bidirectional operation and simultaneous balancing is sais tominimise the time required to equalise stack SoC, and the parts’ high transfer efficiency (up to 92 percent) enables high current balancing with minimal power dissipation.
Control of each balancer is provided via a level-shifting SPI-compatible serial interface which enables multiples of the device to be connected in series, without optocouplers or isolators. The part’s stackable architecture together with interleaved transformer connections enable efficient balancing of every cell in an arbitrarily tall string (>1000V) of series-connected batteries. All associated gate drive circuitry, precision current sensing, fault protection circuitry and a robust serial data interface with built-in watchdog timer and cyclic redundancy check (CRC) data error checking are integrated.
Linear technology Corporation
www.linear.com/product/LTC3300-1
