The topic of efficient utilisation of renewable energy in the production process is becoming more and more important. One way of increasing efficiency is to set up a DC- network in the production facility. In this case, production machines are not supplied by the usual alternating current network, but by an independent direct current system.
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This system is fed via a so-called Active Front End (AFE). The AFE is connected to the standard 3-phase 400V AC-network. After active input conversion with integrated stabilisation, a DC-network with a voltage of 560 to 840 VDC is available. The AFE automatically provides a feed-in and feed-back direction, both ways have the same high degree of efficiency.
An additional buffering can be created with battery systems. Photovoltaic systems or other energy generation systems can then be integrated directly into the system without further conversion.
In comparison with conventional production machines, conversions can be saved as the converters are powered directly with the so-called intermediate circuit voltage. This saves energy and improves electromagnetic compatibility (EMC). Braking energy is also used to charge the battery instead of converting it into heat via a braking resistor.
BOY presented a practical example of this technology at FAKUMA 2023. The BOY 35 E with electric removal handling was operated by a 650V DC network. With an average power requirement of approx. 1.5 kW /h, the machine can be powered via a PV-system when the sun is shining, so that no external energy needs to be purchased.
This means that PV-energy generated on site can be utilised directly without the energy losses resulting from the conversion of direct current (of the PV-system) to alternating current to direct current (intermediate circuit). In addition, these systems help to protect the supply network, as no idle power is generated. EMC-interferences are also reduced and power peaks are minimised.
In areas with unstable power supplies, network fluctuations and short-term breakdowns can be bypassed and thus prevent machine damages and production downtimes.
Thomas Kühr, Head of Electrical Design at BOY: "This is an innovative way to make the company's energy supply more secure."
