The German Fraunhofer Institute for Applied Solid State Physics (IAF) has developed a highly efficient circuit topology for voltage converters with an electrical efficiency of 99.74%. The technology could significantly increase the power factor of electric heat pumps, and researchers are now considering semiconductor gallium nitride (GaN)-based components to increase power density and efficiency.
IAF has developed special power electronics for electric heat pumps to significantly increase their electrical efficiency.
With the electrothermal effect, electric voltage is fed into an electrothermal material made of special ceramics or polymers, and the material heats up. As soon as the stress is removed, the material cools again, making the whole process almost completely reversible.
IAF researchers claimed to have created a highly efficient circuit topology for voltage converters with an electrical efficiency of 99.74%. Today’s heat pumps are technically limited to about 50% of the physical Carnot limit, but an electric heat pump could theoretically reach 85%.
These solid fuel heat pumps are intended to be brought to the market as an alternative to those based on the prevailing compressor technology, as they promise higher efficiency and do not require refrigerants.
Scientists are now investigating components based on the semiconductor gallium nitride (GaN) to increase power density and efficiency. They have succeeded in developing a highly efficient circuit topology for voltage converters based on GaN transistors, with an electrical efficiency of 99.74%. The GaN-based multilevel DC/DC converter greatly exceeds the current state of research with sub-90% charging efficiency in the electrical control of these new heat pumps.
The increase in the efficiency of the power electronics also has a direct effect on the performance of the entire system, which directly leads to a higher coefficient of performance of the entire heat pump system. However, there is still a lot to research in order to make solid fuel heat pumps a more efficient and completely emission-free solution for heating and cooling.
“In order to realize the high power factor of electric heat pumps, the very high efficiency of materials, electronics and heat transfer is essential,” said Kilian Bartholomé, director of the ElKaWe project. “If you can get all this under control, electrical energy technology has huge potential.”
Six Fraunhofer institutes were involved in the ElKaWe project. They have published the results IEEE Journal of Emerging and Selected Topics in Power Electronics.