Texas Instrument’s High-Accuracy Battery Monitor Helps Engineers Diagnose Failures in High-Voltage Battery Management Systems

TI’s BMS solution offers diagnosing battery failures of 100 ms in 400-V systems enables greater system reliability and battery safety. Image used courtesy of Texas Instruments. 

Some challenges that are faced in the automotive manufacturing process is how engineers can filter noise that is propagated throughout the system, accurately measure battery cell voltage, and temperature monitoring. Each piece of data needs to be reported back to the microcontroller (MCU) from the monitoring IC.

 

 

Texas Instruments (TI) is a world known semiconductor company that designs, manufactures, tests and sells analog and embedded processing chips for markets such as industrial, automotive, personal electronics, communications equipment. At the start of 2021, TI announced its industry first, an automotive battery monitor and balancer that was capable of reaching 800 V systems. The current market has lower than 80V of operational voltage for monitoring systems that are external ICs that are equipped with an EVs’ BMS. 

TI’s BQ79616-Q1 helps to achieve battery safety standards while extending the distance of the driving range. The monitoring IC allows for larger conservation of power that improves cell balancing amongst the design.

A unique feature is the fault alert tool, this provides a total shutdown of the system when the vehicle is parked or turned off. This allows for uninterrupted support for actions such as remote key entry, security and battery monitoring. When the car is parked, to ensure proper health of the battery, the MCU has to periodically wake up to look for faults in high-voltage battery packs. This periodic wakeup draws current and can prematurely discharge the 12-V battery.

 

With communication not accessible in sleep mode, the BQ79600-Q1 paired with the battery monitor provides an option to transmit the fault status. Image used courtesy of Texas Instruments.

 

TI’s solution has the ability to measure the state-of-charge and health of the BMS that delivers cell-voltage measurements with less than 2mV of error. The IC has a low pass filter and an analog to digital converter that is daisy-chained to a MCU and communication interface. An interface that pairs well with this new monitor is TI’s BQ79600-Q1, a bridge IC that translates signals to transmit from the MCU to the monitoring IC. 

 

How TI Holds Up to ADI and Infineon

In the world of developing BMS for high-powered EVs, Analog Devices (ADI) and Infineon are the go-to for EV manufacturers.  ADI and Infineon were creating an entire BMS system, wireless and wired, which set them apart from TI. However, shortly after TI’s announcement for the battery monitor, they added a CC2662R-QI SimpleLink, a BMS’s centralized wireless MCU. It establishes a radio link with multiple BQ79616-Q1 battery monitors/balancers which are placed wherever the individual battery cells are physically located. Providing a wireless BMS design that can be constantly monitored, controlled, and balanced through wireless connection. 

What separates TI from the competition is the fact that it has separate components aside from the BMS that can be individually maintained and replaced where as if an ADI or Infineon’s BMS system experiences a fault , then the entire system has to be analyzed and replaced. Even though each BMS manufacturer is saving EVs space, cost and eliminating cabling, not having individual ICs to debug and access can limit design flexibility. 

TI’s device enables the conservation of 12-V battery power and supports functional safety requirements like cell monitoring for overvoltage, undervoltage, overtemperature, under temperature, thermistor over temperature and thermistor under temperature, even when the EV is parked or turned off.