U-Heart: a new concept of fault-tolerant DC-DC converter

U-Heart is a new concept of multi-port isolated DC-DC converter developed to bring optimum availability with minimum redundancy. It is beneficial in sectors where outage and maintenance costs are high, but still with concerns regarding the system installation cost. As a multi-port converter, U-Heart can furthermore be used to connect several power networks, such as energy storage (batteries, super-capacitors), the main grid, renewable energy sources (solar PV panels, fuel cells, etc.), DC loads, etc.

U-Heart is a reconfigurable multicellular converter equipped with our top-of-the-line fault detection circuit. When a fault is picked-up in one of the cells, said cell is excluded from the power transfer and the rest of the reconfigured converter resumes operating, at a slightly decreased power rating. In fields where keeping all cells operating is required, an improved technique was developed: by self-healing, the converter can keep operating at full power. By allowing to optimise repair scheduling, maintenance costs are reduced. U-Heart is therefore a concept of maintenance-friendly power converter.

Since March 2022, the European Innovation Council (EIC) has been funding Super-HEART, a new project that aims at pushing U-Heart towards the market. Click here to read more about it.

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Application Examples

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Net-zero energy buildings

In net-zero energy and autonomous buildings, the power produced locally, the energy storage units, and the grid must be connected reliably and efficiently. Our multi-port, isolated, U-Heart converter is most valuable to do so safely, and at a minimal cost.

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The tremendous datacentre outage cost underlines the importance of having a highly reliable power supply. Our reconfigurable U-Heart power converter brings maximum availability with minimum redundancy, and thereby with minimum cost.

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DC industry

Industry 4.0 requires a hybrid grid able to power AC and DC loads. Availability is paramount and must be achieved at a minimum cost. U-Heart can create such an hybrid micro-grid, whilst facilitating the integration of local power production.

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Leisure industry

Leisure vehicles and boats need a regulator to connect PV-panels, wind generator, batteries…, and the distribution network. Our isolated multi-port U-Heart converter is most valuable to do so reliably, safely, and at a minimal cost.

Laboratory Tests

The following video offers insights into the working of the U-Heart DC-DC converter and shows some test results:

A team specialised in DC-DC power conversion

Our team of engineers and researchers is focused on the development and test of high efficiency, highly reliable, DC-DC converters. We have strong interactions with companies and international research centers. Furthermore, our work is published in the best scientific journals.

Our main laboratory can be used to develop and test DC-DC converters working with voltages up to 1 kV and tens of kW. It is equipped with modern and high-quality instruments allowing us to perform accurate voltage, current, and power measurements. We can also make wideband component analyses and perform non-normative EMC tests. We also have access to a medium voltage laboratory, allowing us to work under voltages as high as 10 kV, with a maximum current of 1.6 kA, and up to 1 MW of circulating power.

Below are some other projects our team is currently developing:

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Fast charging station for e-vehicles

The ongoing electrification of the transport sector raises demands for new power electronic solutions. Consequently, modular converter structures are state of the art for fast charging. With our solution, high compacity and efficiency are achieved by removing the bulky 50 Hz transformer. Furthermore, modularity increases system-level reliability.

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Wireless power transfer

In applications where connectors can hardly be used because they are costly, impractical, or unreliable, wireless links can be made. Using GaN transistors, we develop solutions using a single pair of coils for simultaneous bidirectional wireless information and power transfer (SWIPT). Possible applications are underwater drone, medical implants, etc.


“Spannungswandler” (Voltage Converter, Method for Operation Thereof, and Computer Program), by L. F. Costa, M. Liserre, M. Andresen, and G. Buticchi. (2021, September). European Patent Nr. 18708394.4 (DE102017104138A1; EP3590183A1; WO2018158294A1) [Online]. Available: https://register.epo.org/application?number=EP18708394&tab=main

"Spannungswandler mit flexibler MVDC link Architektur (VESTA)", L. F. Costa, M. Liserre, Patent Pending.

Main Publications

L. F. Costa, G. Buticchi and M. Liserre, "Optimum Design of a Multiple-Active-Bridge DC–DC Converter for Smart Transformer," in IEEE Transactions on Power Electronics, vol. 33, no. 12, pp. 10112-10121, Dec. 2018. DOI: 10.1109/TPEL.2018.2799680, DOI: 10.1109/TPEL.2018.2799680


T. Pereira, F. Hoffmann, R. G. Zhu, and M. G. Liserre, "A Comprehensive Assessment of Multiwinding Transformer-Based DC-DC Converters," in IEEE Transactions on Power Electronics (early access), DOI: 10.1109/TPEL.2021.3064302.


“Market analysis for a reconfigurable isolated multiport DC-DC Converter,” BidCON-Business Development Consulting, report commissioned by U-HEART Project, 2020.

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Our team at Kiel University is composed of power electronics experts. Do not hesitate to contact the chair leader Pr. Marco Liserre