Li-ion battery monitoring system

Power Electronics / Power Management

31 March 2010 Power Electronics / Power Management

Lithium-ion (Li-ion) batteries are growing in popularity as energy storage reservoirs for high-voltage energy, industrial and automotive applications, such as wind turbines, photovoltaic cells and hybrid electric vehicles, and this has spurred demand for safer, higher performing battery monitoring and protection systems. Analog Devices (AD) has addressed the requirements of Li-ion battery manufacturers and power system designers with the unveiling of a Li-ion battery monitoring and protection system that integrates all necessary components, including voltage and current measurement, signal isolation and safety monitoring.

Compared to NiMH (nickel-metal hydride) batteries, Li-ion batteries have a better energy-to-weight ratio, offer more efficient storage capacity over multiple charge-discharge cycles, and suffer less charge leakage when not in use. And unlike NiMH batteries traditionally used in high-voltage applications, battery stacks using Li-ion technology can comprise a large number of individual cells totalling hundreds of volts. Each cell must be properly monitored and balanced to ensure user safety, improve battery performance and extend battery life.

In addition to its voltage measurement, current measurement, isolator, safety monitor and battery management unit offering, AD’s new AD8280 safety monitor provides the designer with the final piece needed to develop the complete front-end of a battery monitoring and protection system. The device is an integrated solution that monitors six cell voltages and two temperature inputs. It is powered completely from the battery stack, providing either a shared or a separate alarm for any of three conditions – over-voltage, over-temperature or under-voltage.

The AD8280 features extensive self-test upon prompt, enhancing the designer’s ability to meet functional safety requirements such as ISO26262 and IEC61508. A large, continuous range of trip point settings provides the flexibility to work with any Li-ion battery chemistry. The device enables flexible safety monitor configurations and its daisy-chain communications option minimises the need for isolators in a high-voltage cell stack. Its low-power mode enables the user to minimise battery drain when the battery is not in use. The part is compliant with AEC-Q100 and EMI (electromagnetic interference) standards, making it suitable for automotive applications.

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Li-ion battery monitoring system

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