Meeting needs of next-gen EV charger designers with custom capacitors

Cornell Dubilier Electronics has expanded its standard-product offerings with devices available from New Yorker Electronics. While the inverter circuitry at the centre of EV charging stations can seem familiar to design engineers, there are operational, environmental and mechanical requirements that make Level 3 EV charging stations unique. The latest designs push voltages and current handling to higher levels to reduce recharge times.

According to Bob Kropiewnicki, director of Applications Engineering of CDE: "We've found that design engineers engaged in Level 3 charger projects are faced with a balancing act to mitigate significant circuit harmonics that cause heating problems. Adequate input and output filtering, strategic current paths, and reducing inductance and ESR are all concerns."

Kropiewnicki continued: "All too often, the DC link capacitor is an afterthought which forces those problems to be dealt with in ways that are more complex than necessary. A better solution is to focus on the requirements of the DC link as early as possible in the design process. We are able to predict performance by using our advanced capacitor modelling based on project application conditions."

Before the EV charger market began to take off, the company was already deeply involved in designing and manufacturing DC link and pulse power capacitors for high-power applications in defence and green-energy fields.

Components include screw terminal, snap-in aluminium electrolytics and polypropylene film capacitors; air or water-cooled types, with oil-impregnated or dry-epoxy construction. Constructions comprise multiple terminal options in metal or plastic cases. The company's process begins with the customer supplying the required specifications, including life and other application needs. These specifications help determine if a standard or custom solution is recommended. It uses advanced in-house thermal modelling and product testing capabilities to validate the recommendation. It has dedicated engineering resources to design custom DC link capacitors that fulfil the exact power needs and unique mechanical packaging to fit complex applications.

The company's custom-engineered DC Link capacitors are developed specifically for Level 3 EV charging applications. The high-power demands of Level 3 charging demand robust DC link capacitors, having excellent life and reliability over a wide range of operating conditions. It provides high capacitance values with low inductance (<5nH), high ripple current (100s of Amps), self-healing, and low loss dielectrics. The voltage range is from 450VDC to 3800VDC, -40C to +135C operating temperature, with typical life expectancies of 200,000 hours.