Nano Power Inverter - Roll Your Own Style

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poida

Guru

Joined: 02/02/2017
Location: Australia
Posts: 1421
Posted: 01:08am 05 Jul 2022      

I'm not doing anything much actually. (Waiting for some cable to arrive so I can
make the 3 phase inverter)

I think I know what you are observing when interrupted slow stops are then changed to a inverter start.
The code as it stands will immediately interrupt the slow stop ramp down
when it gets the command to start. This will have a sharp discontinuity in the power output. It will go from a fraction of full power to ZERO in one step.
And then start ramping up to AC output setpoint.

All I needed was a small change to one one of code to prevent this sharp step from happening.

if (init_done == 0 && sst == 0 )     // this is changed to prevent init of inverter during slow stop
     {
     init_vars();
     init_done = 1;
     }


I needed to test that sst = 0 as well before I initialise the code and restart
the inverter. During init code, sst will be set = 0 and that is the reason
why we get the sharp discontinuity if the slow stop still has some steps
to complete to get to zero.

Now it ramps smoothly up to setpoint or down to zero or even smoothly
changes direction up/down/up when you change the inverter run signal.

here is a version that has 1000 step ramp up and down

nano_1_v7_no_bessel_smooth_stop_1K_steps.zip

I have had a good number of interesting incidents with test inverters
and all of these were due to errors in programming during developing new functions
(e.g. variable AC freq, variable PWM base freq etc.)

I can't recall ever having a bad thing happen when running correct and finalised code
apart from electronic errors such as an already blown power board.