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Forum Index : Electronics : Current source inverter, blog

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zaphod

Regular Member

Joined: 03/06/2018
Location: United Kingdom
Posts: 93

Posted: 07:19am 15 Mar 2019

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Today I would like to report on what I hope is the last of the great intractables..... namely POWER CONTROL. This is based on DCbus voltage that sounds simple enough however the source of the bus is not batteries but a boost converter running an mppt algorithm connected to the panels. This results in instability as the two regulators argue among themselves!

I had a go at spice modeling with limited success as shown below but does give an idea of the utility of spice.

The problem was resolved as usual in both hardware and software, firstly the stored energy was increased something like from 30-130 Joules to give the relatively slow booster time to catch up with load changes and then the CSI regulator was changed in several ways but most importantly to limit the slope of increasing power. As shown in the scope shot below this has been quite successful, CSI power is in yellow and DCbus ripple in red.

I should add the DCbus has to be maintained within fairly tight limits, it is a nominal 180V but >195V the booster will shutdown in overvoltage protection and <165V and the CSI will shutdown with undervoltage protection.
Edited by zaphod 2019-03-16

Cheers Roger
1Kwp DIY PV + Woodburner + Rainwater scavanger :)

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