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Chokes for inverters in wind turbines feature low losses

Chokes for inverters in wind turbines feature low losses

SMP's (Sintermetalle Prometheus GmbH & Co KG) chokes for inverters in wind turbines are now also approved for use in offshore installations. These inductive components feature low losses, very low stray fields, and a highly compact design. The chokes’ cores consist of powder composites specifically engineered for this application.

The direct current from the wind turbines 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. To maximize the inverter’s efficiency, its components must exhibit low losses.

The materials that SMP developed especially for use in its energy efficient, high performance chokes have low magnetostriction and exceptionally low eddy current and hysteresis losses. Their encapsulated design ensures that the power converters emit only low-intensity stray fields, so that they do not affect other components. The chokes have a space-saving compact design, are maintenance free, and have a long lifespan.

Offshore wind turbines are prone to corrosion. To protect them from the corrosive action of the sea water, special salt-resistant materials, additional corrosion protection, and a complete encapsulation of certain subassemblies are necessary. SMP’s inductive components for wind turbine inverters are now certified IP66 and approved for use in offshore installations.

Because of IP66 protection, these chokes can be fitted outside the inverters, which means that the heat generated by the choke is not discharged inside the inverter. This results in a lower internal inverter temperature, which removes the need for cooling fans, saving both energy and installation space.

Placing the choke outside the inverter has the further advantage of reducing the inverter’s overall dimensions, which further cuts space and energy demand. To simplify mounting outside the inverters, SMP provides the chokes with special mounting fixtures. The choke and the mounting plate are fitted on the device’s outside and the connecting cables pass through a sealed opening.

SMP supplies inductive components for frequencies up to 200 kHz and current ratings up to 1,000 amperes for use in onshore wind turbines, photovoltaic plants, railway engineering, medical engineering as well as in drives, power electronics, power generation, and instrumentation and control. Depending on their application, they are constructed either as single-conductor chokes for high-current applications, single-phase individual chokes, three-phase 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.

For more information, contact Westendorf Associates Inc., P.O. Box 22, Elm Grove, WI 53122. Phone: (414) 380-9730.

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