Addressing high-voltage current-sensing design challenges in HEV/EVs
Electrification has created a new paradigm in automotive power systems; whether the design is a hybrid electric vehicle (HEV) or fully electric vehicle (EV), there are new design challenges to address. In this technical article, I’d like to highlight some of the primary challenges in high-voltage current sensing and share additional resources to aid and simplify your design process.
High voltage (≥400V) fully electric systems aim to lower the current consumption for the traction system that moves the vehicle. This requires isolating the solution so that the ‘hot’, high-voltage side can provide current measurement to the ‘cold’ side (attached to low-voltage ≤5V microcontrollers or other circuitry).
The high current presents an issue when trying to measure with a shunt resistor due to the I2R power dissipation.
To use a shunt in these conditions means that you must select a sub-100µΩ shunt resistor, but these resistors tend to be larger and costlier than more common milliohm resistors. One alternative is to use magnetic-based solutions, but these are less accurate and have higher temperature drift than shunt-based solutions.
Overcoming these performance drawbacks will dramatically increase the cost and complexity of a magnetic solution as well.
To read more from Texas Instruments, click here.