Drives and Controls Magazine
SiC-based regen system could pay for itself in two years
Published:  03 December, 2014

At the recent SPS IPC Drives show in Germany, Lenze demonstrated a new approach to recovering braking energy and feeding it back into the mains, that is designed to be efficient, compact and easy to apply. The technology, based on fast-switching silicon carbide (SiC) semiconductors, can achieve rapid paybacks and can be used in applications where regenerative braking has previously been considered too costly.

The system can be deployed without having to set parameters and without needing any signal interfaces. It is installed on an inverter’s DC bus or, if that is not possible, on the brake chopper connection. The technology can be retrofitted easily to existing installations, Lenze says, opening up new possibilities for machine-builders. The power range can be scaled from 2–48kW by using parallel connections.

The SiC devices at the heart of the system allow it to be highly efficient (about 98%), while also being compact and light. They are only half as big and heavy as comparable conventional technologies. Because of its high efficiency, the SiC-based regenerative energy system could pay for itself in less than two years, depending on the amount of energy used – about half the time needed for block-commutation systems, Lenze suggests.

The technology separates the feed-in path from the feedback path, allowing them to be sized separately and precisely to suit an application. It is designed to regenerate the exact amount of brake energy that remains in multi-axis applications – such as storage and retrieval systems in automated warehouses – after mechanical optimisation, drive dimensioning, and energy exchange in a DC bus connection.

Lenze demonstrated its novel braking energy recovery technology at the SPS IPC Drives show in Germany

The technology can also be applied to single horizontal axes in applications such as materials-handling, where conventional regenerative systems are not usually considered economical because of the small amount of braking energy generated by such applications. 

Lenze has developed the new technology in two research projects, working with the University of Ostwestfalen-Lippe and backed by funding from the German Federal Ministry of Education and Research.