[SOLVED] grid tied inverter controller

[AssemblyLine]

Hello
Consider the application of a microinverter with input from solar panel 20-45 V dc (or similar) and output 230V ac into the grid, power 300-500 W. MPPT feature also needed.

Do you know any 100% analog solution, without involving microcontrollers?
the ideal solution would be a single IC to control both stages, but I believe the disadvantages would overcome the benefits, so a two IC solution is also good.

For the DC-DC stage, I know a couple ICs (mostly for LLC topology), but for the dc-ac stage, I do not know.

So is there any IC that can control a MOSFET-full bridge to output a sine wave and have output voltage regulation ?

 

[KlausST]

Hi,

My thoughts:
A pure analog solution may have an ideal efficiency of 70% or so. I rather expect 50% or less.

A grid tied inverter usually does not need a voltage regulation. The voltage is determined by the grid. A GTI uses current control.

Klaus

 

[FvM]

I presume, 100% analog doesn't mean analog output stage but pwm with dedicated controller IC instead of microcontroller. There's a previous thread discussing the same topic

https://www.edaboard.com/threads/control-chips-for-50hz-mains-inverters.399704

 

[cupoftea]

i think it can be done with an analog controller, but it needs to be a configurable analog controller.....ie, the peak current threshold, and frequency of operation, need to be changeable.
The thread pointed out by FvM shows it is possible at a single power level, but the sim shown there gets into trouble when you go to a differnet power level.

 

[Easy peasy]

The simplest a solution is a controlled flyback to create the sine current on the secondary at the elevated volts ( looks like rectified sine wave )

then 4 igbt's to form an "unfolding" stage - i.e. to direct the output of the flyback to the mains so that the polarity is correct for pos & neg cycles

all this can be done in analog without issue, UC3854 can be used to control the flyback

(p.s. this has been done in very high volume manufacture u-inverters )

 

[BradtheRad]

Previous thread about controlling a grid-tied inverter.

edaboard.com/threads/control-chips-for-50hz-mains-inverters.399704/

 

[AssemblyLine]

Hello all and thanks for the answers...
My "100% analog" idea was in fact microcontroller-less. Or at least something with the least amount of configurations; like a preprogrammed MCU-based IC that does what I need l; it can have some one-time configurations over an UART or similar.
I do not have the time and skills for embedded programming.

So I was searching for ICs to do that; especially the inverter stage; an ICs which can generate PWMs with sinusoidal modulations and which have integrated a feedback loop.

After some searches, I have found an ASIC (actually a family) : EG8025 (drivers included); EG8030 (3 phase), EG8010 (1 phase). These are quite unique ICs and have not found other similar ICs.
There are some motor controllers which can generate sinusoidal modulated PWMs like NXP's MC3PHAC which I think can be used (in an unorthodox way) to control the inverter stage.

--- Updated Nov 6, 2021 ---

Hi,

My thoughts:
A pure analog solution may have an ideal efficiency of 70% or so. I rather expect 50% or less.

A grid tied inverter usually does not need a voltage regulation. The voltage is determined by the grid. A GTI uses current control.

Klaus

And do you know any IC that does current control and SPWM?