April 2013

Energy-efficient industrial electronics

Lower losses, more powerful and longer lived

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The trend toward green energy demands maximum energy efficiency from the applications connected to the grid. EPCOS and TDK products are assuming key functions in this process and thus help to realize environmentally friendly energy technology as well as industrial machines, equipment and systems.

EPCOS aluminum electrolytic capacitors with screw terminals satisfy the rigorous requirements with respect to current capability, reliability, service life and temperature. In addition, these capacitors offer the high energy density needed for use in compact power electronics modules. These extremely rugged EPCOS components also feature the performance required for state-of-the-art direct-drive converters in wind turbines. A maximum rated voltage is a co-determining factor for the cost-optimized use of capacitors in industrial and energy systems. The rated voltage of two newly developed series of EPCOS aluminum electrolytic capacitors with screw terminals has now been increased from 550 V DC to 600 V DC. Thanks to these significant voltage increases, manufacturers of industrial power supplies, frequency converters for drives, inverters for photovoltaic plants and converters for wind turbines can now connect fewer series capacitors in the DC links, thus reducing costs and the space required.

Innovative magnets for high power densities
Innovative TDK neodymium magnets of the NEOREC series are used to achieve a maximum power density of the synchronous generators in wind power plants (Figure 1). Depending on their material composition, they offer magnetic field strengths of up to 3000 kA/m and resonance flux densities of up to 1.5 T. These magnets are also very well suited for industrial motors, allowing these to be both compact and highly efficient at the same time. In addition, TDK offers a series of ferrite magnets that require no rare earths at all. They are ideally suited for the development of efficient motors.

Figure 1: TDK neodymium magnets of the NEOREC series

TDK neodymium magnets are suitable for efficient generators and motors.

Key components for drives
The proportion of industrial drives controlled by state-of-the-art frequency converters continues to grow. Their energy efficiency can then be significantly increased and their power consumption reduced. In these frequency converters, EPCOS aluminum electrolytic capacitors are frequently key components for stabilizing the DC link voltage. These capacitors are characterized by low ESR and ESL values, which further increase the efficiency. Thanks to special base-cooling concepts, their service life has been greatly extended. At the same time, this helps to achieve very compact designs.

Besides the proven aluminum electrolytic capacitors, EPCOS power film capacitors are also playing an ever more important role in the DC links of industrial converters. They are also suited for use in converters and inverters of wind power and solar generators. Especially because of their low ESL and ESR values combined with high capacitance values and rated voltages, such film capacitors are predestined for industrial electronics applications. A further advantage is their extremely long service life. This makes film capacitors well suited for converters designed to have an extremely long service life and low maintenance requirements. TDK is one of the few manufacturers to offer both capacitor technologies – aluminum and film – thus enabling customers to find optimized solutions for their applications.

The TDK CeraLink™ offers a completely new approach to DC link capacitors (Figure 2). It is based on PLZT ceramic (lead lanthanum zirconate titanate) and covers a capacitance range from 1 µF to 100 µF with a rated voltage of 400 V DC. A further type features a rated voltage of 800 V DC and a capacitance of 5 µF. Thanks to their low ESL value of less than 4 nH as well as their low ESR of less than 4 mΩ, these new capacitors are ideally suited for applications with rapid rise times and high switching frequencies. This especially includes the converters used in industrial and automotive electronics, which operate with new fast-switching MOSFETS or IGBTs.

Figure 2: TDK CeraLink™ capacitor family


These ceramic-based capacitors are ideally suited for converters operating with rapid rise times and high switching frequencies.

Power capacitors for power transmission
Two trends are increasingly making headway to minimize line losses and use energy as efficiently as possible: high-voltage DC (HVDC) transmission and the introduction of smart grids. HVDC routes halve the losses sustained by conventional three-phase networks. Multilevel voltage-sourced technology is used for network links, especially to offshore wind farms of the kind currently being built in the North and Baltic Seas. Capacitive voltage dividers are used here to convert the DC current back to AC. They are based on specially developed EPCOS MKK power capacitors with high capacitances and rated voltages.

Reactive power is produced when inductive loads such as transformers and motors are operated. It has no use but cannot be avoided. EPCOS power factor capacitors of the PhaseCap® and PhiCap™ series have contributed for decades to power factor correction and thus also help save costs and protect the environment. In addition to these capacitors, for which the company is the world market leader, the range of EPCOS products also includes controllers, thyristor modules, contactors and chokes.

Wide range of EMC and overvoltage protection

EPCOS EMC filters are indispensible for suppressing RF interference in industrial electronics applications. They are offered in 2-, 3- and 4-line versions with current capabilities of up to 2000 A. Thanks to the extensive range of types, all EMC problems can be solved by using standard products as well as customer-specific solutions. Decentralized power generation is leading to growing problems with overvoltages. EPCOS varistors and gas-filled surge arresters are used to reliably protect valuable industrial electronics equipment and installations. The EPCOS ETFV varistor series is especially well suited for the inverters used in photovoltaic installations. This product is designed to handle multiple pulse loads and also has an integrated thermal fuse that disconnects the component in the event of overload. In addition to many variants of monolithic varistors with diverse terminal configurations and load capabilities, multilayer varistors are also ideally suited for protecting the I/Os of control electronics.

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