New Tech Tuesdays: Protecting EV Chargers with High-Voltage Pre-Charge Relays
Key Highlights
- Higher DC bus voltages improve energy efficiency but pose challenges in component sizing and system footprint.
- Modern PCB power relays help reduce size while maintaining robust protection for high-voltage circuits.
- Pre-charge circuits with relays and resistors safely manage inrush currents, preventing damage to sensitive components.
New Tech Tuesdays
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Engineers designing next-generation electric vehicle (EV) chargers and energy storage systems face relentless pressure to increase efficiency and capacity. Meeting this demand requires shifting to higher operating voltages, often up to 1500VDC. While elevated voltages improve energy conversion and integration with renewable sources, they introduce significant challenges in component sizing. This week’s New Tech Tuesdays explores the engineering challenges of managing high-voltage inrush currents and examines how modern printed circuit board (PCB) power relays shrink footprints while protecting critical circuitry.
Managing High-Voltage Scaling
Power architectures in EV charging infrastructure, energy storage systems, and solar-plus-storage installations continue to push DC bus voltages higher. At a given power level, a higher DC bus voltage can reduce current, which helps lower conduction losses, heat generation, and conductor sizing. In EV fast-charging and energy storage system (ESS) architectures, this can enable higher-power charging and more practical integration with local energy storage and renewable generation. However, scaling up the voltage often inflates the equipment size. Historically, controlling such large DC voltages requires bulky, heavy contactors, creating a footprint dilemma for designers who must keep systems compact.
Protecting Systems with a Pre-Charge Relay
High-voltage systems rely on large capacitors that draw a large inrush current when powered on. Unchecked, this sudden surge can easily damage sensitive electronic components. A pre-charge circuit safely manages this initial load by pairing a pre-charge relay with a current-limiting resistor. When the system powers up, the pre-charge relay closes first, routing current through the resistor to safely charge the capacitor. Once the DC-link capacitor reaches a predefined voltage threshold near the source voltage, the main contactor closes, and the pre-charge circuit disengages. >>Click to read the entire article at Mouser
