New high-end sinusoidal filters protect high speed motors

The aim of the output filters of the new COMBILINE Z2 series is clear: to reduce the EMC load and therefore increase the service life of motors in machines and systems. However, there are other factors in favour of using these filters, which KEB Automation has designed specifically for use in high speed applications.

“The Z2 high speed filters are matched to the COMBIVERT F6 and S6 drive controllers and are suitable for applications such as turbo blowers, radial compressors and high speed machine tool spindles,” explains Christian Mehlhaff, hardware designer in the Filter and EMC division at KEB Automation. “Due to a design with very low losses, efficient solutions with high efficiencies can be achieved.”

Through the interaction of KEB drive controllers and the appropriate EMC (Electromagnetic Compatibility) technology, plant and machine builders use the full potential of the drive. Against this background, the Z2 sinusoidal filters are characterised, among other things, by the fact that a high degree of flexibility is provided by the combination of choke and capacitor.

“As the switching and motor frequencies normally vary in different applications, filters have always been individually rebuilt up to now. With the Z2, KEB is now taking a new approach that follows the modular principle – we can make use of any components that are required for the system,” says Mehlhaff.

For the individual combinations, the system is simulated and analysed in advance on the basis of motor, filter and system data. A new tool is also currently under development that will be integrated into KEB’s COMBIVIS Wizard software, which will allow users to specify all the required characteristics for the application so that COMBIVIS parameters for the system are automatically filled in correctly.

Reduced rotor heating, longer service life

The motor is supplied with a sinusoidal voltage, which prevents additional losses due to ripple currents of the drive converter switching frequency in the stator and rotor. The result is reduced heating of the magnets in the rotor and a longer service life of the motor. With the Z2 sinusoidal filters and the standard drive converters from KEB, fast rotating machines up to 100,000 rpm can be operated in the power range from 750W to 450kW.

Last but not least, motor noise is reduced and the EMC behaviour of the overall drive is improved by the filters. Therefore, the sinusoidal filters, which are designed with a low-loss core material and have a particularly high efficiency of >99%, are designed as “high speed filters” that significantly reduce losses in the motor.