56 January/February 2025 | E-Mobility Engineering Nick Flaherty investigates techniques that enable digital controllers to interface safely with high-voltage systems Isolated states As automotive designs move to electrification, highpower electronics have become critical components in new electronic drivetrain and battery systems. Communication and control from low-voltage digital devices requires electrical isolation of the high-voltage elements from the low-voltage side, covered by the extra-low voltage (SELV) regulations. This allows for existing 12 V power, 24 V in offroad vehicles and emerging 48 V designs. In all these applications, galvanic isolation, usually semiconductor-based, is required to allow digital controllers to interface safely with the high-voltage systems of a modern EV. A typical EV combines many power functions, including the traction inverter, climate control and heating, and the onboard charger. These systems operate at radically different voltage levels that must be isolated. Galvanic isolation prevents the flow of current between the different voltage domains while still supporting the flow of data and power, and it can be integrated into a power device such as a gate driver that controls the inverter. Other approaches, such as optical isolation and electromechanical contactors, can cut off the highvoltage portions of a vehicle to protect both the equipment and the users. Electromechanical contactors are particularly vital for offroad and industrial vehicles, such as agricultural equipment and electric mining trucks with huge battery packs delivering large amounts of power. Historically, galvanic isolation for data transmission has been implemented using optical technology, with an LED or laser source and a photodiode receiver. However, the demands of the automotive market in general, and EVs in particular, have spurred the development and adoption of digital isolation technologies to offer an alternative. Fundamentally, the first priority in any high-voltage power system is to protect maintenance personnel, operators, drivers and passengers. Galvanic isolation satisfies this priority by isolating the high voltage from other low-voltage human interface sections. The second priority is to establish reliable, safe operation between Isolation in a chip (Image courtesy of Texas Instruments)
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