Energy-efficient chokes for inverters in wind turbines

“The direct current from the modules must be converted into a sinusoidal waveform with the values required by the grid. The converter’s filters, which consist of capacitors and filter chokes, ensure that the current being fed into the grid exhibits a near sinusoidal waveform”, explains Stefan Schauer, technical sales manager at SMP. To meet the ever more demanding requirements of modern wind turbines, SMP has developed high-performance, low-loss chokes.

Developed by SMP especially for inverters used in wind turbines, the materials used have low magnetostriction and exceptionally low eddy current and hysteresis losses. This means that the inverters in which they are used are highly efficient, so that a larger proportion of the generated power can be fed back into the grid. This results in a faster return of investments. “The profitability of a wind turbine is directly related to the efficiency of the inverters, which, in turn, is determined by the energy efficiency of the components used”, ads Stefan Schauer. “The manufacturers pay very close attention to the components’ efficiency, which must be as high as possible.”

In addition to low losses, components in power converters are required to have low-intensity stray fields. SMP chokes achieve this through an encapsulated design. This offers the advantage that other components can be placed in close vicinity to the chokes without the risk of magnetic interaction. Compact choke design is another important aspect. In comparison to conventional designs, SMP chokes occupy 25 percent less space.

The chokes are maintenance-free and have a long lifespan – a significant contribution to reducing the expensive maintenance of wind turbines. SMP chokes have also been tested and approved for use in offshore installations.

For use in photovoltaics, railway engineering, drives, power electronics, power generation, and instrumentation and control, SMP supplies inductive components for frequencies up to 200 kHz and current ratings up to 1000 amperes. Depending on their application, they are constructed either as single-conductor choke for high-current applications, 1 ph individual chokes, 3 ph choke modules, or LC filters. These components offer a high energy storage capacity in a compact and cost-conscious design as well as reduced losses and good EMC characteristics. SMP manufactures all components to customer specifications using in-house developed powder composites. All products are RoHS- and REACH-compliant and the materials used are UL-listed. To allow for a wide range of requirements, components can be made to all common international standards.