Automotive manufacturers across the globe are announcing aggressive plans to launch new models of battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs) and full-hybrid electric vehicles (FHEV). As automotive designs move to electrification, high-wattage power electronics become critical components in the drivetrain and battery systems. These high-wattage electronics need to be communicated with and controlled by low-voltage digital controllers requiring electrical isolation of the low-voltage side from the high-power system. In these applications, galvanic isolation is required to allow the digital controllers to safely interface with the high-voltage systems of a modern EV.
Electric Vehicle System Overview
EV/HEV battery management systems typically include four major circuit assemblies:
Battery Management System Overview
The BMS manages stored power in a non-board high voltage (HV) battery and delivers power to the rest of the vehicle. The main functions include cell balancing, cell health and wear leveling, charge and discharge monitoring, and safety assurance. These functions require galvanic isolation to separate lower voltage systems from high voltage domain in the following ways:
DC-DC Converter Overview
DC-DC converters are used to convert DC voltages from one voltage domain to another for powering various auxiliary systems. Isolation products have numerous uses inside DC-DC converters in the electrical domains of EV or HEV. These functions require galvanic isolation to separate control systems from high-voltage domains in the following areas:
On-Board Chargers Overview
The OBC converts AC power from an external charging source into a DC voltage that is used to charge the battery pack in the vehicle. In addition, the OBC performs other functions including charge rate monitoring and protection.
In the OBC system, isolated gate drivers are used to chop the input signal into a switched square wave to drive a transformer to create the required output DC voltage. This output voltage can be monitored to provide closed-loop feedback to the system controller using isolated analogy sensors. Furthermore, the entire system can be monitored and controlled via an isolated CAN bus with digital isolators with and without integrated DC/DC power converters.
Traction Inverter Overview:
Traction inverters are used to convert stored DC high voltage from a battery or DC bus link into multi-phase AC power for driving a traction motor. Isolation products have numerous uses inside traction inverters in the drive train of EV or HEV through the following:
Silicon Labs Solutions:
The race to electrify automotive fleets is accelerating with more vehicles arriving from more manufacturers every year. Semiconductor-based isolation offers significant advantages over legacy optocoupler solutions, which make them an ideal choice in demanding EV applications.
Silicon Labs offers a broad portfolio with a rich variety of digital isolators, isolated gate drivers, and current sensors. With robust qualification, support, and excellent technical performance, learn more about how you can fit Silicon Labs’ product offerings in your design solutions in this Quick Reference Guide.