Use of multi layer ceramic (MLC) capacitors in high power converters

A high-ripple current high-voltage multi-layer ceramic (MLC) capacitor was investigated for use in a HF high-power converter application. The MLC capacitor was utilized in lieu of conventional metallized film snubber capacitors, due to its superior low equivalent series inductance (ESL) per μf value attribute. Also, the RMS current rating per capacitor volume ratio is high, because the MLC may be operated with a 125°C surface temperature rise. However, the present MLC design tradeoff is the higher initial cost per μf. This paper characterizes the MLC capacitor equivalent series components, determines maximum allowable RMS current based on thermal constraints and gives a design example of the MLC capacitor used as a split and distributed resonant capacitor in a high power 200 kVA RDCL soft switching GTO power converter