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I bought a cheap VFD (variable frequency drive), it takes 3 phase input, but allows too for 1 phase input connecting the neutral and phase on the the first and third phase input. The vfd to my knowledge rectifies and filters the input, so with 1 phase it gets 230Vac and produces 325dc, but when the input is 3 phases the voltage between them is 398 so 563Vdc is generated. How is that handled by the VFD as no voltage conversion happens using transformers ?

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230 VAC three phase will still produce about 325 VDC for the bus link. You may be thinking about European 230 VAC which is about 400 VAC phase-to-phase. You would probably need a different VFD rated for that, although the one you have may work at that voltage. The VFD would just need to monitor the link voltage and adjust the PWM duty cycle accordingly. Check the manual for the one you have.

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  • \$\begingroup\$ The manual doesn't state anything in relation to that. The electrical scheme could state something eventually but I don't have any \$\endgroup\$ Oct 30, 2022 at 9:14

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