Wittmann EcoPower DC – Direct Current as Power Source
WITTMANN BATTENFELD presented to Fakuma visitors an all-electric machine from the new EcoPower B8X series driven via a solar power storage battery.
The concept of operating a machine with direct current generated by renewable energy from solar power was presented by WITTMANN BATTENFELD for the first time at the K 2022, and was met with wide interest. Firstly, supplying a machine with energy generated by an in-house solar power station enables users to save costs and preserve the environment as well. Secondly, direct current can be stored easily in batteries and is thus an ideal means to cover expensive current peaks and improve the reliability of the power supply. Another advantage is the possibility of saving CO2 emissions by using direct current technology to increase energy efficiency and save resources.
The all-electric EcoPower from WITTMANN BATTENFELD, equipped with highly dynamic servo motors to drive its main movements, is particularly suitable for use in a DC power network. The machine comes with the patented KERS – kinetic energy recovery system – as standard. This system converts kinetic energy into electric energy during deceleration processes. For example, the resulting electric current is used within the machine for barrel heating.
With KERS, the energy consumption can be reduced still further. This equally applies to a DC-compatible robot, which is powered directly via the DC voltage interim circuit of the EcoPower and then also returns any surplus energy to the interim circuit whenever its axes are decelerated. If the machine operates in a DC network, the deceleration energy can also be fed into the DC network. This energy can also power other machines connected to the DC network, or the energy can be stored in batteries.
Since its first presentation of this technology, WITTMANN BATTENFELD has taken further developmental steps to advance this innovative concept. For optimal counselling of interested parties, the machine manufacturer searched for a suitable partner specialising in DC infrastructure and found it in the Swiss company innovenergy® AG.
innovenergy® has been developing and operating energy storage systems with salt batteries for almost 10 years. Originally, it developed the sodium-nickel technology for e-successful mobility, but it has recently entered the sector of stationary storage batteries for a great variety of different applications. innovenergy® offers a portfolio of 9 kWh to 999 kWh storage capacity and inverter capacities ranging from 3 kVA to 300 kVA. To date, it has successfully installed some 1,000 salt battery storage systems.
In developing its innovations for the industrial sector, innovenergy® found that the issues of energy efficiency, connected load limitations of AC infrastructures, independence and autarky, and failure safety in cases of mains interruption are gaining more and more significance.
All of these aspects can be addressed profitably by what is known as a DConnect system: renewable energy generators (photovoltaics or wind power), energy storage batteries and consumers are linked with each other in a separate DC network, which enables direct use of the generated energy with hardly any conversion loss. Only surplus electricity is returned to the power network.
In this way, DC/AC/DC conversion losses between the solar power station and the machine can be reduced by up to 15%. The entire potential of photovoltaic systems on large roof areas can also be utilised without investing in a mains connection extension, which might otherwise be necessary. The DC-connected salt battery storage systems provide sufficient energy reserves for regular operation and for bridging mains network power failures.
With a DConnect, innovenergy® can supply an efficient, low-cost overall solution all the way from the initial concept and detail design to the selection of suitable DC components.
To implement and install the DC network components, innovenergy® will train and support local AC network planners and installation partners to ensure seamless interaction between the existing AC installation and the DC microgrid.
innovenergy® presented its functional concept to Fakuma visitors in a live demonstration. At the WITTMANN booth, the use of direct current without first passing through inverters was shown on an EcoPower 180/750+ B8X. With a single-cavity mould from the Austrian company Kunststofftechnik Grabher GmbH, a drainage body was manufactured from polypropylene. The part was then removed by a modified WX142 robot in the DC version from WITTMANN.
To enable a live presentation of the DC technology to the visitors, the machine remained disconnected from the main network of the exhibition hall during the fair. It was powered independently via a solar power storage battery consisting of ultra-modern, ecological salt battery technology supplied by innovenergy®. To balance the brief load peaks of the injection moulding machine, additional electrochemical capacitors, known as super-caps, were used to complement the sodium-nickel storage batteries. The battery has a total capacity of over 45 kWh, which was sufficient for continuous machine operation throughout the 8-hour trade fair days.
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