I am in the process of creating a high-current inverter, with a current rating of 100A. I have completed the simulation, but am having difficulty finding an inductor with a high enough current rating for my needs. Are there any alternative options to an LC filter that I could consider in order to achieve the desired level of filtering?
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1\$\begingroup\$ You haven't said what filtering you require nor the cut-off frequency nor the filtering attenuation nor the switching operating frequency <-- that's not a lot to go on. However, when you say Are there any alternative options to an LC filter the answer is probably no but, different arrangements of LC filters can be successful. \$\endgroup\$– Andy akaJan 1 at 13:51
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2 Answers
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If you cannot find an inductor with sufficient current rating, you can:
- reduce inductance specification (e.g. by increasing the switching frequency)
- use several parallel inductors (which also reduces inductance though). 4 equal inductors (two parallel branches if two in series each) will make one new inductor with the same DCR, same inductance and twice the current rating
- use several parallel half bridges, each with their own inductor (multiphase converter)
- wind your own large choke on a large enough core
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2\$\begingroup\$ Of all the options @tobalt mentioned, I think the multi-phase (that is, multiple power trains operating at the same switching frequency but on different phases) approach is best. This approach reduces the stress on the power train components, and increases the ripple frequency which makes it easier to filter. \$\endgroup\$– SteveShJan 1 at 13:54
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\$\begingroup\$ @SteveSh agreed. But it is also likely the one with the highest additional development effort. So the higher the target product quantity, the more worthwhile \$\endgroup\$– tobaltJan 1 at 14:51
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One alternative option to an LC filter that you could consider is an RC filter. An RC filter consists of a resistor (R) and a capacitor (C) connected in series or parallel, and is used to remove high-frequency noise from a signal. RC filters are generally less effective at removing high-frequency noise than LC filters, but they are simpler and cheaper to construct, and may be sufficient for some applications.
Another option you could consider is a transformer. A transformer is an electrical device that is used to transfer electrical energy from one circuit to another by means of electromagnetic induction. Transformers can be used to isolate circuits from one another and to filter out high-frequency noise.
It is also possible to use a combination of different filter types to achieve the desired level of filtering. For example, you could use an LC filter in combination with an RC filter or a transformer to provide additional filtering of high-frequency noise.
Keep in mind that the most suitable filter type for your application will depend on the specific requirements of your inverter, such as the desired level of filtering, the operating frequency range, the size and weight constraints, and the cost and availability of components. It is a good idea to carefully consider all of these factors when selecting a filter for your inverter.
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\$\begingroup\$ How will the resistor cope with the 100 amps specified in the question? Have you considered how much power dissipation this will create? \$\endgroup\$– Andy akaJan 1 at 17:30