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  1. #1
    Some advice wanted please.

    Can modern VFD's generate 380v 3 phase from single phase 220v?

    I'd assumed that they usually run at the same output voltage as the input so 220v 1ph in and 220v 3ph out, so to run a standard 3ph motor, you have to rewire it from delta to star.

    I was looking at some of the VFD's on ebay and came across some that suggest they do some sort of voltage doubling to give 380v 3 phase ouput.

    Are the specs bogus?

    A 4kw VFD was priced at 170, so more expnsive than the 220v 1ph to 220v 3ph models.

  2. #2
    JAZZCNC's Avatar
    Lives in wakefield, United Kingdom. Last Activity: 17 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 8-9 years. Has a total post count of 6,340. Received thanks 1,045 times, giving thanks to others 46 times.
    Yes, you can get 220v to 380v but they are not common. Mainly because to do their trickery they dump a lot of interference back into the electrical Grid so you might get few angry neighbors or even knock on the door from power company.!!...... That said I know a few who have them and work without any problems.

  3. #3
    Quote Originally Posted by JAZZCNC View Post
    Yes, you can get 220v to 380v but they are not common. Mainly because to do their trickery they dump a lot of interference back into the electrical Grid so you might get few angry neighbors or even knock on the door from power company.!!...... That said I know a few who have them and work without any problems.
    Thanks Jazz.

    I'll have a look at the wiring situation and if star to delta is not too tricky, I'll stick with a 220 in/out version.

  4. #4
    You've got it wrong. There's a 220V to 380V VFD! For details, please refer to this article:http://www.cnweiken.cn/en/list/49/175.htm

  5. #5
    This vfd converts the power frequency AC 220V power supply into a DC power supply through a rectifier (double voltage rectification) on the basis of the ordinary frequency converter, and then converts the DC power supply into a three-phase 380V AC power source whose frequency and voltage can be controlled. Supply the motor. This method does not boost through the transformer, but only boosts through the rectifier boost circuit, which greatly reduces the size and weight of the inverter. Compared to the voltage booster, the cost is lower.

  6. #6
    Quote Originally Posted by cnweiken View Post
    This vfd converts the power frequency AC 220V power supply into a DC power supply through a rectifier (double voltage rectification) on the basis of the ordinary frequency converter, and then converts the DC power supply into a three-phase 380V AC power source whose frequency and voltage can be controlled. Supply the motor. This method does not boost through the transformer, but only boosts through the rectifier boost circuit, which greatly reduces the size and weight of the inverter. Compared to the voltage booster, the cost is lower.
    Thanks for the link.

    Yes I see that 220v single to 380v three phase do exist. For 4kw power, they are quite expensive compared to 220v single to 220v three phase VFDs.

    Jazz says they also put nasty noise back into the supply.

    One benefit is that I do not need to rewire my motors though.

    Can't find the Boost version of your VFD on AliExpress. Link on your site took me to a DC input version!

  7. #7
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 20 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,343. Received thanks 263 times, giving thanks to others 6 times.
    https://cnweiken.aliexpress.com/stor...516455484.html

    A DC voltage doubler is actually a pretty simple circuit, it's just that bumping ~340VDC to 530VDC at the currents needed, generally leads to some quite substantial noise/harmonic/interference production.
    It's not a problem if done in a suitable enclosure and using suitable filtering, but we all know how the Chinese like their minimalistic approaches to engineering at the cheaper end of the market...

    But having said that, I am considering one of these boost VFDs for my big mill (it's maybe a physical big mill, but its old enough to only have a 3KW motor). The 4KW is only $205 delivered, so it's not the end of the world if it turns out to be hopeless and wipe out all electronics in the neighbourhood :-)
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  8. #8
    I shouldn't be too worried about wiping out electronics in the neighbourhood, as in term of high frequency interference from the output switching edges (which is what normally does that) there's no reason why a voltage doubler input is likely to be much worse that a standard bridge circuit, it's all down to the input filtering. The main problem as you point out is the harmonic current generation due to the very short and very large current spikes it draws when charging the internal capacitors from the AC mains waveform, which the power companies hate as it puts a very uneven load on the generators and squares off the top of the supposedly sinusoidal AC waveform. It can be ameliorated to some extent by putting a hefty inductor in the supply line, I did this on a SMPS I designed a while back where for various reasons we didn't want to add an active Power Factor Corrector (PFC) front end, and it worked well enough to get it through the relevant harmonic current regs. The other thing to also watch out for on such voltage doubler circuits is the lifetime of the capacitors, as they're getting some serious current pulses going through them, cheapo ones just won't last.

  9. #9
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 4 Hours Ago Has been a member for 6-7 years. Has a total post count of 1,415. Received thanks 104 times, giving thanks to others 67 times.
    Ive got two. Ecogogo, love them. Speak to John Pei, he can provide a quote.

    johnpei2012@foxmail.com


    ShenZhen ECOGOO Electrical Co.,Ltd

    Phone: 86-139-24624957

    Tel: 075528485003

    http://www.ecogoo.com.cn

    Address: 7F Bldg #E, North Area No. 8

    Shangxue Technology Industrial city,

    Shenzhen,China

  10. #10
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 4 Hours Ago Has been a member for 6-7 years. Has a total post count of 1,415. Received thanks 104 times, giving thanks to others 67 times.
    Just make sure you get the one that does do 220V in and 380V out.

    I run Thor's spindle on one and also power my surface grinder (380V) from one. They arent as cheap as the HY drives but a lot better device and the only way to reasonably make 3 phase power without messing with crappy rotary convertors.

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