Progress on power electronics for electrocaloric heat pump systems

This work gives an overview on power electronics for charging and discharging electrocaloric capacitors, which aim to increase the system coefficient of performance (COP) of electrocaloric heat pumps towards the higher material performance limit. The electrical charging efficiency (which is either characterized for electrocaloric capacitors, or often only for ideal capacitive loads) is reviewed for resonant-circuits (up to 70%), two-level halfbridge converters (around 99.2%) and multi-level or partial-power processing converters (up to 99.75%, powerstage only, without control, gate drive and sensing losses). Alternative stepwise capacitor charging circuits with up to 240 levels and up to 95% electrical efficiency are also reviewed. The importance of high electrical charging efficiency is discussed. While the work focuses mainly on electrocaloric ceramics, which often require ultra-high external electrical charging efficiencies, electrocaloric polymers (with different permittivity and dissipation factor characteristics) are also discussed. Efficient power electronics contributes to solid-state, emission-free and efficient electrocaloric heat pumps.