Guru
Joined: 13/10/2014
Location: AustraliaPosts: 1860
| Posted: 04:20am 30 Apr 2025 |
Toroid Buzz in on Bench test Inverter:
Controller in test mode - UNLOADED.
As the DC voltage is slowly increased past 34 volts, the Toroid starts to quietly Buzz, I then creep the voltage up to 40V and AC regulates at 240V, the buzz decreases slightly and continues up to 50V, above 51V it goes quite, however if I cause a SUDDEN >2v increase in voltage, the Toroid sits there Buzzing.
If you then cause a sudden >2v drop in DC voltage, the toroid goes silent, this behavior is seen all the way down in voltage until below regulation.
When the Toriod buzzes, it continues until even a small load, causes a disturbance and the Toroid goes silent once again.
However at the point below regulation (in above text) the Toroid Buzzes, and the effect can reverse, IE sudden Voltage increase makes Toriod silent, sudden decreases makes it Buzz.
Somewhere below the AC Regulation point, REG=240v and now AC=236v for example, when you get it just right, you can hear a slow cycling Buzz from none to just audible, but not every time you try. But I would sort of expect this with inverter noise and right on the edge and going in and out of regulation, I wonder if there might be some noise getting into the builds due to the location of the Controller? or not!
FYI Nano in simple terms: - unless my memory is failing me.
The Nano is just loafing along, SPWM setup takes 12µS setting each 1/2 cycle + if updating LCD output an extra 4µS when needed. The ISR runs every 50µS (like clock work) where it checks for the completion of each 10mS half cycle of SPWM generation and initiates the next half, at which time SPWM control runs to handle various states of SPWM generation, followed by I/O processing, prepare LCD buffer, Error checking, and USB Menu requests, etc.
The Nano needs to complete the above tasks in under 10ms
However, total round trip time for all tasks is under 500µs to 600µs <1ms WORST possible CASE
whereupon the Nano sits there basically twiddling it's thumbs for another 9ms, waiting for the next half cycle trigger. These times have been verified endlessly with test debug setup and time logging.
BTW: The response time for an over-current event to full Shutdown in the Nano is <51µs worst case - no matter what the Nano is doing (Unless it's off).
Note The controller board also hardware disables SPWM and latches it off in an over current event.
.
Edited 2025-04-30 15:10 by KeepIS