Zero Cross Engineering logo: an optocoupler with a zero-crossing triac Zero Cross Engineering logo: an optocoupler with a zero-crossing triac Zero Cross Engineering
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All (4)
ATPDraw (3)
control (1)
EMT (3)
inverters (2)
LV distribution (2)
power electronics (2)
power quality (3)
Simulink (1)

Zero Cross Engineering

An applied engineering notebook on power system transients, power quality and inverter control.

I’m Facundo Dimotta. After almost twenty years designing, building and operating MV/LV distribution networks, I use this notebook to study what the grid does when things change fast: switching transients, harmonics, and inverters taking over from rotating machines.

Each study states its model, its parameters and its limitations. When I find a mistake, I correct it and record the change at the end of the publication. More about me and this site →

Closing the Voltage Loop With a PR Controller: Filter Resonance, Finite Gain and Non-Linear Loads

Simulink
control
power electronics
inverters
power quality

Why does a PR-controlled inverter settle at 89 % of its voltage reference, and why does its waveform flatten under load? A Simulink study where every number can be traced back to the model parameters.

Aug 27, 2026
8 min

Why an Unloaded Inverter Rings at 500 Hz, and Why It Doesn’t Stop

ATPDraw
EMT
power electronics
inverters

An EMT study of an inverter with a transformer and LC filter before and after its load is connected. The resonance frequency, the decay time and the effect of the load all follow from the filter parameters.

May 29, 2026
4 min

The Return Path: What Flows in the Neutral With a Single-Phase Rectifier

ATPDraw
EMT
power quality
LV distribution

How much current does the neutral carry when one rectifier load is connected, and what is it made of? An ATP study with an explicit neutral impedance and a phase transfer.

Mar 17, 2026
5 min

Transferring a Non-Linear Load Between Phases in a LV Network

ATPDraw
EMT
power quality
LV distribution

What happens to the network and to the load itself when a rectifier load is moved from one phase to another? An ATP study on a realistic LV feeder, from the harmonic content to the dip seen by the DC bus.

Mar 10, 2026
5 min
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© 2026 Facundo Dimotta · Content licensed under CC BY 4.0

 
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