High-Temperature, High-Power Performance of Ceramic Filter Capacitors

Power conversion electronics in military vehicles and aircraft are currently experiencing high temperatures and future generations will see these temperatures rise even higher. The high temperatures arise not only from the environment but also from high power dissipation in the components themselves. Capacitors can occupy almost 50% of the real estate in some power converters and these capacitors are subjected to very high currents at high frequencies in dc-dc converters or 60-Hz 120 VAC in the output stage of an inverter. Dissipation resulting from the high power levels can lead to internal capacitor temperatures at least 50°C above their ambient and so for military hybrid electric vehicles (HEVs) capacitors are expected to reach at least 150°C and possibly 200°C, while future aircraft component temperatures are expected to exceed 250°C. A new family of high-temperature dielectrics based on sodium bismuth titanate has been developed by these authors and capacitors are now available from Novacap under the...