Newbie
Joined: 05/07/2019
Location: ItalyPosts: 23
| Posted: 03:05pm 11 Feb 2021 |
Goodmorning everyone!
3 kinds of inverter arrived from aliexpress so i can also experiment.
the first, simple squarer that drives driversfinals:
the second, EG8010 which drives power amplifiers + recycled ups transformer.
the third, AC/DC converter with SG3525 and EG8010 for direct DC/AC
on H-bridge with high voltage.
with great amazement all 3 inverters work, proved simple
a few watt incandescent bulb + current limiter
DC input for safety, you never know.
life expectancy at 80% of power output is a mystery.
I have a couple of questions regarding the last two inverters
to which I cannot technically answer.
- we have a way / circuit to bypass EG8010 and use
Chinese low voltage hardware with arduino and sketch nano1?
I assume you need drivers like the ir2110 or similar present on the EG8010 and something that emulates the protections offered by the opamps.
I would like to be able to test the sketch with as little hardware as possible
on Chinese inverter.
- why is the high voltage inverter not used in the amateur field?
my first answer is to be sure not to handle DC at 310 or more volts.
I assume that the sketch nano1 can safely drive through drivers
with adequate dead time, a high voltage H bridge.
if safety and efficiency are not the problem, what would improve using the output transformer?
- is there a way to deform inverter output waveform in a controlled way?
i know series diode test on light bulb to saw waveform,
as did Peter in this thread pages ago.
but it would be useful to introduce other types of distortion such as the inductive type that is generated by a fridge motor or a starting drill.
but without using a fridge or a drill that consume too much current.
an LCR circuit that distorts in the same way but with low consumption?
I apologize in advance for the probably trivial questions for some people.
i am trying to figure out how to correct the inverter output shape.
this without relying only on the voltage peak dictated by the feedback to follow the output voltage on both half-waves (I imagine a half-wave on unipolar EG8010)
the idea is to sample the output waveform and compare each sample to the one present in array l[NPWM] at the same time of reading.
the difference between the comparison gives the value to be given in
the OCR1A when it will create the output PWM pulse to correct the output deformation.
can my logic be correct?
adding a few lines to the sketch I calculated the time it takes the ISRs and ADCs to do their thing, as Peter had already written in the comments.
if the ADC readings are few and accurate, thanks to internal VREF from 1.1, I think the waveform control idea is feasible.
I also ported the sketch to stm32f103c8 (blue pill) without using stm32duino but STM32 on IDE arduino.
bare metal registers are crazy, but once you understand everything works perfectly.
ln attached if anyone wants to experiment.
there are not all active pins but only those for testing which I played on breadboard.
obviously you can then import them if necessary.
2021-02-11_154623_stm32f103c_nano_1_v7_no_bessel_angelo_syncv5_forum.zip
I tried the port to understand how much the timing affects etc.
but it is how the code is written and the use of registers that make the difference, always.
I will also try to use the stm32f411 (blackpill 100mhz) but I assume there are no problems whatsoever o improvements apart from points per wave and pwm frequency tested only on breadboard for now.
thanks for your advice on my doubts,
Ciao! A.
Edited 2021-02-12 01:16 by iannez