Browse Publications Technical Papers 2014-01-0417
2014-04-01

Thin-Film High Voltage Capacitors on Ultra-Thin Glass for Electric Drive Vehicle Inverter Applications 2014-01-0417

The propulsion system in most Electric Drive Vehicles (EDVs) requires an internal combustion engine in combination with an alternating current (AC) electric motor. An electronic device called a power inverter converts battery DC voltage into AC power for the motor. The inverter must be decoupled from the DC source, so a large DC-link capacitor is placed between the battery and the inverter. The DC-link capacitors in these inverters negatively affect the inverters size, weight and assembly cost.
To reduce the design/cost impact of the DC-link capacitors, low loss, high dielectric constant (κ) ferroelectric materials are being developed. Ceramic ferroelectrics, such as (Pb,La)(Zr,Ti)O3 [PLZT], offer high dielectric constants and high breakdown strength. Argonne National Laboratory and Delphi Electronics & Safety have been developing thin-film capacitors utilizing PLZT. Capacitors made with PLZT are well suited for power applications due to its high dielectric constant, low loss, high temperature capability, low equivalent series resistance, high breakdown strength and benign failure.
Previously published papers described PLZT capacitors created by depositing PLZT onto metal foils; this paper describes an ultra-thin flexible glass as the substrate with a thin metal (platinum- Pt) vapor deposited as an electrode. PLZT is deposited onto the metal to create the dielectric. A top electrode metal is then applied by electron beam evaporation to create the capacitor [1] [2].
This project involved the fabrication and electrical evaluation of thin-film capacitors built on flexible glass for Electric Drive Vehicle inverters. The capacitors were tested for dielectric integrity, capacitance, dielectric constant and voltage breakdown. Results from these tests, processing challenges, and implementation methods will be described.

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