Power regeneration can be so easy

At the Hannover Industrial Fair Lenze is presenting the prototype of a new kind of solution for feeding energy back into mains and is demonstrating its strength as an innovator once again. The concept's main features are its easy handling, compact design, and great efficiency. Because the infeed path and the feedback path have been separated, they can be separately dimensioned, which makes it possible to dimension them precisely to provide whatever the system requires. The new regenerative power unit deploys brand-new technology: at its core are fast-switching semiconductors made of silicon carbide (SiC), enabling the unit to achieve a high level of efficiency while also being extremely compact and light. Thanks to their high efficiency, the units pay for themselves in a very short time. They can be scaled from 2 kW to 48 kW, and even as a retrofit they can be very easily integrated into existing installations. This opens up completely new perspectives for the machine-building industry, even in applications where energy recovery has so far not been economically feasible.

Lenze has developed the new unit in two research projects, working in collaboration with the University of Ostwestfalen-Lippe and backed by funding from the German Federal Ministry of Education and Research. With this solution, Lenze is aiming for the effective regeneration of the exact amount of brake energy that remains in multi-axis applications, such as storage and retrieval units in automated warehouses, after mechanical optimisation, needs-oriented drive dimensioning, and energy exchange in a DC bus connection. The new unit can also be used in horizontally deployed single axes, where the traditional regenerative power units so far have never been economical enough because of the small amount of brake energy generated by those applications. This field of application includes drives in horizontal materials-handling technology, for example.

At the heart of the new regenerative power units there are fast-switching semiconductors made of silicon carbide (SiC). This high-tech substance enables the unit's innovative components to achieve high switching frequencies, so the devices are only half as big and heavy as the current comparable technology. And there is more good news for the machine-operating companies: in comparison with block-commutation solutions, the new devices will pay for themselves in half the time: the goal is to reach full amortisation in less than two years, depending on the amount of energy used by the machine. Lenze has designed the new power feedback system in a way that enables the device to be deployed without having to set parameters and without any signal interfaces. The installation takes places on the DC bus of the inverter or, if that is not available, on the brake chopper connection. This makes it easy even to retrofit the new technology to existing systems. The device's power range can be very easily scaled by means of a parallel connection.