Sensing and balancing chip targets battery management system designs
Infineon Technologies has launched a sensing and balancing for battery management system designs to extend the range and reliability of electric vehicles.
The TLE9012AQU supports up to twelve battery cells with an accuracy of ± 5.8 mV over the entire temperature and voltage range as well as the operating life cycle. This improved accuracy extends the range of the battery pack and the long term reliability. It also supports up to five external temperature sensors, providing an integrated cell balancing function with an iso-UART interface for communication.
The device is especially designed for battery management system (BMS) designs in hybrid and electric cars, but it is also suitable for other applications. The device is supports different topologies in battery packs.
“There are different cell topologies in a pack depending on how many cells are in parallel or series so different topologies are handled by this chipset,” said Dr Clemens Muller, director of application management at Infineon. “A multi-string topology allows you to change between parallel blocks and serial, for example to charge with lower voltage and switch to a higher voltage for driving.”
The TLE9012AQU provides the necessary measurement data and ensures a balanced state of charge through cell balancing. Among other things, this prevents the weakest cell from determining the total usable capacity of the battery.
With twelve channels, the TLE9012AQU is particularly suitable for battery management system designs that are partitioned with twelve cells per module so that one device is used per module. The iso-UART interface for data exchange between these modules and with the microcontroller allows easy voltage isolation and ensures data integrity. The communication supports more than 20 serially connected devices and a ring topology. This ensures that even if a single device fails, the communication chain is not broken and the rest of the system remains functional.
A programmable filter reduces the impact of noise on the signal to improve the overall measurement accuracy. Performing the measurement in all cells simultaneously means the results remain comparable even in the presence of temporary interference factors, and a compensation algorithm with integrated stress sensor and extended temperature compensation ensures the long-term stability of the measurements.
The cell balancing is achieved via twelve balancing switches integrated on the chip – one per channel. They are designed for currents up to 150 mA. For higher balancing currents in the battery management system, the device also supports external switches. The cell balancing can be programmed to stop without a signal from the microcontroller after a defined time of up to 32 hours or when the cell has reached a defined voltage. This allows the microcontroller to switch to sleep mode and thus save energy.
Alongside the TLE9012AQU, Infineon is launching a matching iso-UART transceiver, the TLE9015QU. Both devices will be available in July 2020.