A 99.74% Efficient Capacitor-Charging Converter Using Partial Power Processing for Electrocalorics

Abstract

This work combines a 99.2% efficient GaN-based low-voltage fast-switching half-bridge converter with a Si-based high-voltage slow-switching and almost lossless switched capacitor multiplexer using a partial power processing approach to a six-level prototype with 99.74% efficiency. A loss breakdown shows how the ideal partial power processing efficiency is theoretically increased to 99.84% by using four additional voltage levels, but then reduced to the measured efficiency by the additional static and dynamic losses of the multiplexer. For electrocaloric heat pumps, an emerging technology for cooling and heating applications with zero global warming potential, such high charging efficiencies enable a high heat pump system coefficient of performance (COP). Based on available data of electrocaloric lead magnesium niobate (PMN)-based samples, and based on a first-principle and best-case analysis for Carnotlike cycles, it is predicted that the 99.74% electrical charging efficiency in combination with the electrocaloric material data enables to surpass 50% of the thermal Carnot limit (for cooling with a heat pump). Ultra-high efficiency of power converters thus pave the way towards future electrocaloric heat pumps of competitive system performance.

Double-Bond-induced Morphotropic Phase Boundary leads to Enhanced Electrocaloric Effect in VDF-Based Polymer Flexible Devices

“…Concomitantly, low hysterestic losses, U loss , and thus low remanent polarization, P r , are maintained in the 0.2% DB-modified polymers, because the increase of the alltrans containing crystalline phase, φ FE , remains limited. Both of these trends (summarized schematically in Figure 2c) contribute to the increase of ΔT EC , which is proportional to the electricfield-induced polarization change P P r max 2 2 . 20 Broadband dielectric spectroscopy (BDS) was used to further quantify the effect of the introduction of DB on the structure of P(VDF-ter-TrFE-ter-CFE) and elucidate the origin of the dielectric enhancement.…”

“…Lowefficiency and high global warming impact technologies must be phased-out from the RC. With theoretical efficiency over 80%, 1,2 solid-state cooling based on the electrocaloric (EC) effect has emerged as a serious candidate to facilitate this transition, but its potential for applications is still hindered by the low performance of EC materials. EC cooling is based on the electrocaloric effect (ECE), which arises from the increase of the net polarization in polar crystals upon the application of an external electric field, E. Under adiabatic conditions, the system compensates the decrease of dipolar entropy (inherent to the alignment of dipoles) with an increase in lattice vibration entropy, i.e., an adiabatic temperature increase, ΔT EC , thus keeping the overall entropy of the system constant.…”

Colossal electrocaloric effect in an interface-augmented ferroelectric polymer

“…Compared with the base TP (COP mat is 10.9), the DMHD-modified TPD-1% exhibited excellent refrigeration efficiency of 91% (COP mat is 27.4), considering a 100% charge recovery ratio (Fig. 4G), which has been achieved in a custom-made charge recovery circuit for EC technology ( 55 ). By operating under an ultralow electric field, the TPD-1% offered a greatly improved COP mat that could further reduce the size and weight of the power source for a potential portable EC cooling device.…”

High cooling performance in a double-loop electrocaloric heat pump

“…Therefore, these results show that energy recovery is key to improve the efficiency of electrocaloric systems. Very recently, Mönch et al showed that an energy recovery as high as 99.7% is possible, which is very promising (41).…”

“…Very recently, Mönch et al . showed that an energy recovery as high as 99.7% is possible, which is very promising ( 41 ).…”