6 months ago



Managing the energy

Managing the energy levels of drives and entire machines The required conditions for protection of electrical drives against voltage fluctuations, power outages or drop in peak loads can hardly be more diverse. The company, Michael Koch GmbH offers wide range of products from safe braking resistors to high-performance, high-power, and high-capacity energy management systems, all of which ensure that the drives and peripheral equipment run smoothly and reliably. MOTION AND DRIVES Energy management is often equated to software-based monitoring, but that’s not the entire reality. This is perfectly illustrated by the German company, Michael Koch GmbH. The company focuses on taking direct control of the drive energy and 01 Koch’s Dynamic Storage Manager (DSM 4.0) that of the peripheral equipment. For systems that produce regenerative energy e.g., during tool changeover on a machine tool, a safe braking resistor with a high protection rating can be integrated to dissipate this energy. The design can be based on the maximum permissible surface temperature, thus allowing for the braking resistors to be mounted outside the control cabinet and hence prevent the need for active ventilation. The typical application case for 02 Safe braking resistors is with emergency Discharge Unit shutdowns of machines that (SDU) designed for normally run continuously. With capacitors in the such machines, regenerative DC link of up to energy is only produced in very 200 kJ of energy rare cases. They yield very little regenerative energy, therefore installing an energy recovery system does not pay off even over the machine’s entire service life. Similarly even for many small drives that only brake once in a while, storing such infrequent regenerative energy is hardly economical, the easiest and safest solution in such cases is the use of braking resistors. Braking and cycle times play a decisive role when choosing the right solution. In many cases, braking only lasts fractions of a second and the resulting energy being dissipated via the braking resistor only amounts to a few joules. If this 32 WORLD OF INDUSTRIES 7/2018

happens every few seconds, the resulting energy does not even amount to one kilojoule per hour of operation. In other terms, a kilojoule of energy must be produced per second in order to save one kWh per hour of operation. And with that it becomes clear, what is decisive in the choice between a braking resistor or any other energy management solution. Increasing energy efficiency and productivity In cases where sufficient regenerative energy is produced even in short cycles, it pays off to store this energy and supply it to the drive system when necessary. Koch offers the Dynamic Energy Storage (DES), which is connected directly to the DC link of the drive inverter. It is designed for fast repetitive energy strokes and can increase the energy efficiency of a machine significantly depending on the specific application. In many cases, the energy savings are well over 15 to 30 %. For DES suitable application, a rule of thumb to be followed is, the shorter the intervals between the braking processes, the higher the energy saving potential. In the case of chippers and high-speed sorters, the intervals can be fractions of a second, meaning that integration of Koch’s energy storage solutions can immediately lead to the desired increase in efficiency. For drive electronics that are heavily burdened by intense acceleration and braking every second, the DES also relieves the inverter significantly, which in turn increases the service life and helps avoid unplanned downtimes. At the same time, the machine can also be operated at faster speeds if the mechanics allow it. Here, increases in productivity by well over 10 % can been achieved in supply and discharge applications that use robots. For applications where the customer has higher power and energy requirements, Koch’s KTS systems well suited. KTS series offers a wide range of ready-to-connect energy management systems with peak outputs of well over 100 kW and up to 1.8 MJ of energy. They are based on a combination of power electronics, supercapacitor modules, as well as necessary and optional devices. The DSM 4.0 is well equipped to master the power electronics whereas the supercapacitor modules store the electric energy. Here, the simulative calculations that depend on the application parameters are decisive, as they determine the necessary components to be used. For instance, if 20 kW must be stored over 15 seconds and then supplied back to the drive at one- minute intervals, users can opt for KTS system that comes in a control cabinet with dimensions of H 2 000 x W 600 x D 600 mm. The KTS systems are connected directly to the DC link of the drive or drive system. They therefore supply uninterruptible energy or buffer regenerative energy cyclically when necessary, both of which might also be necessary depending on the application. In such cases, the KTS systems are the ideal solution. These come with all the necessary safety systems, fully wired and ready to connect. The systems are configured ready-to-use and integration is very easy, often requiring just the connection of the power and communication cables. Stability and safety in unstable networks Koch’s energy storage solutions are not only designed to supply energy for electric drives. The 24 V emergency power supply (NEV) supplies the 24 V circuits of the machine or plant with uninterruptible power. These include control units and/or IPC, sensors, and the brake control modules. The problematic issues connected with short-term power outages and associated data loss in unstable networks is now a thing of the past. Another solution that comes in handy during maintenance is the safe discharge unit (SDU). This discharges the storage voltage to a safe level in a reasonable amount of time while maintaining a maximum surface temperature of 55 °C at an ambient temperature of 20 °C. The company now offers a new dimension in performance and energy with the recently introduced modular and flexible energy management system (KTS). The benefits of energy management solutions can be explored with a much larger number of machines. It is extremely easy to design via the web-based tool, with integrated safety measures and necessary periphery equipment assembled, in custom-made, ready-to-connect control cabinets. A safe system that offers many advantages in the desired form. And when it comes to safe braking resistors, Koch positions itself as a competent partner with it’s wide range of safe braking resistors, which support energy amounts of up to several megajoules, benefits that many dream of. Photographs: Michael Koch GmbH 03 Braking resistors installed in a housing, ideal for use in dusty environments


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