In response to the rapidly growing demand for higher-performance DC link capacitors for electric vehicle (EV) chargers, Cornell Dubilier Electronics (CDE) has expanded its standard-product offerings with devices issued through franchise distributor New Yorker Electronics. While the inverter circuitry at the heart of EV charging stations may seem familiar to design engineers, there are operational, environmental and mechanical demands that make Level 3 EV charging stations unique. The latest designs are pushing voltages and current handling to higher levels to shorten 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 modeling based on project application conditions.”
Before the EV charger market started to take off, CDE was already deeply involved in the design and manufacture of DC link and pulse power capacitors for high-power applications in military and green-energy fields. This base was further enhanced by the acquisition of the custom film capacitor division of NWL in 2021.
Components available include screw terminal and snap-in aluminum electrolytics as well as polypropylene film capacitors; air or water-cooled types, with oil-impregnated or dry-epoxy construction. Constructions include multiple terminal options in metal or plastic cases. CDE’s process begins with the customer providing the required specifications, including life and other application requirements. These specifications help determine if a standard or custom solution is recommended. To validate the recommendation, CDE utilizes advanced in-house thermal modeling and product testing capabilities. CDE has dedicated engineering resources to design custom DC link capacitors that meet the exact power requirements and unique mechanical packaging to fit complex applications. On the manufacturing side, the company has multiple North American manufacturing facilities.
CDE’s custom-engineered DC link capacitors are designed specifically for Level 3 EV charging applications. The high-power demands of Level 3 charging require robust DC link capacitors, having exceptional life and reliability over a broad range of operating conditions. CDE offers high capacitance values with low inductance (less than 5 nH), high ripple current (100s of Amps), self-healing and low loss dielectrics. Voltage range: 450 V DC to 3,800 V DC; -40° C to 135° C operating temperature, with life expectancies of 200,000 hours typical.