Toroids help banish damaging inverter currents

Toroids made from the nanocrystalline material Nanoperm are increasingly used to reduce damaging motor bearing currents in high-power inverter systems operating at high switching frequencies.

Toroids made from the nanocrystalline material Nanoperm are increasingly used to reduce damaging motor bearing currents in high-power inverter systems operating at high switching frequencies.

These unwanted currents can cause the bearings to corrugate, followed by electrical breakdown of the lubrication, which will soon cause the whole motor to fail.

Using nanocrystalline cores significantly reduces both the overvoltage peaks at the motor terminals, but also the asymmetrical EMI currents which both are generated by the parasitic capacities of the motor itself together with the motor cable.

In order to achieve an efficient reduction of those destructive effects, one or more nanocrystalline cores of suitable geometry can be put commonly over the connector cables each in the DC-link as well as at the inverter output.

In this configuration, the cores operate as common-mode chokes.

This method significantly increases the service life of the motor bearings and thus reduces maintenance costs and standstill periods.

All together the enormous costs of loss of production can be reduced dramatically.

For this application Magnetec have developed special design software that enables it to provide suitable tailor-made attenuation kits quickly for every kind of inverter configuration.

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