Toroidal Inductor for SMPS Output Filters and PFC Stages

Yes. We build boost PFC chokes on toroidal powder cores, with heavier gauge or multi-strand copper where the line current calls for it. To quote, we need the input voltage range, output power, switching frequency, target ripple and conduction mode. Standard toroidal parts run up to 25 A; higher currents are handled as custom designs.

For inductors carrying DC, iron powder is the usual toroidal choice because its distributed gap resists saturation. An ungapped ferrite toroid has high permeability and saturates at a small DC current, so it suits common mode chokes and low-bias filtering, not energy storage. Where iron powder loss is too high at your frequency, alloy powder cores such as Sendust or MPP are available through our custom range.

The usual causes are core loss from a large ripple at high frequency, copper loss from undersized wire, or partial saturation at peak current, which increases ripple further. Measuring the current waveform shows which applies: ripple that curves upward sharply near the peak indicates saturation.

Not as a main energy-storage part. In a flyback converter the transformer itself stores the energy, so the output is filtered by capacitors. Many designs add a small inductor to form a second-stage LC filter that reduces switching noise on the output. That post-filter part carries the full load current but needs only a low inductance, often a few µH.

The online catalogue lists stock toroidal power inductors, and stock items typically dispatch within 24 hours. If no listed value fits, custom samples are typically supplied within 7 to 10 working days. Quantities are flexible, from about 10 pieces for R&D. RoHS and REACH compliant materials are used, and certificate copies are available on request.