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davef
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Joined: 14/05/2006
Location: New Zealand
Posts: 499

Posted: 09:10am 22 Sep 2016

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On my PowerMaster PM3000L 24V inverter with, for example, a 1kW resistive load the input current varies at a 100Hz rate and looks like a reasonable sinewave.

The current varies from quite a low value, say a few Amps up to 100A then back down to a few Amps over the 100Hz period. Average current about 50Amps and inverter efficiency about 90%.

There are quite a few inverter projects underway on the forum and I was hoping that people could tell me if what I see is common, or are there inverters that draw a steady DC current from the battery?

Thanks,
Dave

Madness

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Joined: 08/10/2011
Location: Australia
Posts: 2498

Posted: 11:16am 22 Sep 2016

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I am no expert but you see mentioned a lot "Ripple" which is what you are seeing, what capacitors does it have across the input?

There are only 10 types of people in the world: those who understand binary, and those who don't.

davef
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Joined: 14/05/2006
Location: New Zealand
Posts: 499

Posted: 05:35pm 22 Sep 2016

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No idea.

I have since been told that all inverters behave like this. The capacitance required to filter out the 100Hz would be very LARGE.

Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 11:36pm 22 Sep 2016

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I'm curious. How did you measure (with what) that current?

BTW, the capacitors used in my inverter add up to 60,000uF/100V electrolytics.

Klaus

oztules

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Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 12:09am 23 Sep 2016

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Yes what goes out must come in ......with a few losses.

At low power, the 60000uf I have will cover it pretty well, but as you get up to 2kw it is a significant flattened sine wave with the carrier impressed in it as well, and more pronounced as you climb up the scale.

..........oztules

Village idiot...or... just another hack out of his depth

davef
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Joined: 14/05/2006
Location: New Zealand
Posts: 499

Posted: 08:04am 23 Sep 2016

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Using at 90A 100mV shunt and a 'scope.

Thanks guys.

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