Is there any electric circuit that can help a 2000W Inverter to run a motor with 500W but actually want a big power resource at launch time such as refrigerator?

I think if we have a big Capacitor it will work, is this true and how to implement this in the real world?

  • \$\begingroup\$ Have you checked the current limit in the inverter setup? HTH. \$\endgroup\$ – user8648 Mar 14 '12 at 16:10
  • \$\begingroup\$ Google "soft start". \$\endgroup\$ – nibot Mar 14 '12 at 17:54
  • \$\begingroup\$ What sort of wall outlet/circuit was this fridge intended for? A 120VAC 15A outlet can only be expected to supply 1800W, so a 2000W inverter ought to do it unless the fridge was intended for a beefier circuit. Also if it isn't new, the fridge might just need servicing to reduce mechanical losses. \$\endgroup\$ – Jay Kominek Mar 14 '12 at 19:51

No, not really for AC. That is assuming I understand the somewhat garbled question correctly as "Is there a simple way to help a AC inverter deal with motor startup current beyond the inverter's rating?".

A capacitor could possibly work if the power was DC. A capacitor can dump a lot of current quickly for a short time. The problem is that motor startup current is required for a long time relative to what a reasonable size capactor can provide. Motor startup can last a few seconds, so whatever power source is used needs to be able to provide that.

That all said, if the motor normally requires 500 W, doesn't it startup up well enough with 2 kW supply? Have you tried it? It seems like there is a reasonable chance it would work, given the 4x overhead you have. What voltage? What is the motor stall current?

  • \$\begingroup\$ May be starting into a compression stroke with no flywheel effect. \$\endgroup\$ – Russell McMahon Mar 14 '12 at 14:30
  • \$\begingroup\$ Thanks for answer, i tried to run a refrigerator but the inverter shutdown automatically when the compressor run i think my 2kW inverter give 1.4kW virtually, so i need any think may help,i believe that if compressor lunched the inverter will continue supply it. \$\endgroup\$ – homer tem Mar 14 '12 at 17:05
  • 1
    \$\begingroup\$ @homer: Sounds like you need a bigger inverter then. You also need to make sure that your DC power source is capable of delivering the power. Maybe the inverter is fine, but the battery or whatever you have supplying the inverter can't handle the motor starting power. \$\endgroup\$ – Olin Lathrop Mar 14 '12 at 17:23

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