Hello! 👋

 🚀  My name is Sotiris Zorbas and I’m a power electronics engineer, from Greece 🏖️. I’m one of the new additions in the Frenetic family, the new kid on the block, as they say…😅

Not exactly Instagram worthy, but hey if it’s in the lab it shouldn’t be pretty, right?

My journey with Frenetic started a few months ago, when I was hired to design, build and debug a 3kW PFC that would be used to test Frenetic’s designs under real conditions.

From now on I’ll be testing magnetics under real conditions, on the lab bench, to verify simulations results.

These results will help us verify most parts in 🚀"The Library" 🚀 as Dr. Molina mentioned in his previous newsletter.

👉 What we mainly care about is temperature and how winding and core choices affect the overall power dissipation thus temperature rise.

👉 Using a proven library design, that’s ready to be shipped to you 🚙 will save you lots of time.

That data will be sent to the AI design team as a feedback, helping them train the algorithms and spot differences, as well.

Without boring everyone with details 😵 I’ll quickly remind the engineers what is power factor(PF).

⚡   AC loads, like home appliances, can be resistive, capacitive, inductive in their nature.

⚡   Unless we’re talking about pure resistive loads, everything else makes PF less than the ideal 1. When PF=1 that means that the voltage-current don’t have a phase difference and most of power generated from the power plant will be converted to real power at the load, minus the powerline power loss.

⚡   When PF<1 there is reactive power in the system (measured in VAR).

⚡   Why do we care about VARs? Only power measured in W (real power) produces a real effect, whether that’s heat, or movement etc…

⚡   We care because, increasing reactive power increases the RMS current. Increasing current, increases powerline losses exponentially (P=I²R), a very real effect. 👀  

👉 Every appliance that’s connected to the grid and it’s above 75W needs to meet the EN/IEC 61000-3-2 regulation standard, in most countries. The regulation basically mandates the engineers to use power factor correction, if they are building devices above that power level.

💥Enough with theory - let’s move on to the real test for this week. 💥  

Here is the PFC inductor rated at a maximum of 3kW, I’ll be testing for this week’s newsletter:

         👉 Inductor design project 😊

▶️    How did it perform under 3kW PFC load for 1hr? 🧐

▶️   BTW no air-forced cooling used, just natural convection!

🤔11.8% ? Hmmm is this close enough? After some head scratching, I realized that I didn’t consider two things that contribute to the error.

🔑   The first was that with a 3kW load in the room for 1hr the room temperature had risen! How much? In my case up to 23.5°C when the last measurement was taken at the end of the test. This alone brings error down to 6%.

🔑 The second error source comes from the infrared camera mismatch between set emissivity to the camera and real inductor emissivity of radiation. A 1-2% error there is not unusual.

So less than 5% error… Can’t complain about that 🤗

Now it’s 🍺 time!

Anyway if anyone likes to ask a question, correct me on something, or simply needs a bit of help to unlock a mystery in his brain (if I can help), don’t hesitate to email me at sotiris.zorbas@frenetic.ai. I’m the type of engineer that spends hours on a problem, will read what’s available first, and then ask a question. It works but it’s painful. Sometimes all you need is 1 min out of someone else’s time. Be like that instead...

💥   A complete PFC design guide that takes the user step by step into the design process of a 3kW CCM Boost PFC will be available in our training program . The content of the PFC video presentation I’m preparing for the training program is this:

✅   Basic PFC theory

✅   Classic Boost PFC - circuits analysis/part selection

✅   PCB layout – From theory to practice

✅   Magnetics design

✅   Experiments, results, probing, waveforms

WHAT’S COMING NEXT WEEK?

👉 Next week, another inductor test will be presented. I’ll start talking about specific things on the PFC design subject and some probing traps for young players out there! Also, I’ve written an app note/design guide with details about this inductor, along with details about measurements that will be shared in the next newsletter. Stay tuned! 😎  

👋  Until next week 👋