Texas Instruments tells us that Battery-monitoring systems are used to estimate state of health (SOH) and state of charge (SOC), especially in Electric Vehicles (EVs). To get detailed information about SOH and SOC, integrating accurate sensors into the battery-monitoring system is critical to protect the battery from damage. For a typical battery, current, voltage and temperature, sensors must measure the following parameters:
The current flowing into (when charging) or out of (when discharging) the battery.
The pack voltage.
The individual cell voltages.
The temperature of the cells.
Let’s look at the location of current sensors in a block diagram of a battery-control unit. See Figure 1.
The location of the current sensor in a battery-control system (Image courtesy of Texas Instruments)
Using an isolated shunt current-sense measurement system provides excellent isolation between the hot and cold sides in an automotive application; this system helps with battery sensing reliability. TI has the following devices like the AMC1301 which provides current signal isolation and the ISOW7821 that provides power isolation. The PGA400-Q1 eliminates the offset and gain errors. See Figure 2.
An isolated shunt current-sense measurement system (Image courtesy of Texas Instruments)