Question about MCU Inside UX-52 Inverter – Adjustable voltage at fixed frequency - Page 1
Forum section: electronics / beginners

author: testingeneer
author_rank: Newbie
timestamp: June 28, 2025, 09:18:57 pm
content: Hi everyone!I’m currently building a levitation experiment based on the Thomson ring principle at home. The goal is to create a strong, pulsating magnetic field using a coil to lift an aluminum ring into the air. I wound the coil myself (enameled copper wire, 1 mm, 20 m), and it’s mounted on a soft iron core. It’s the same principle as shown in this link:https://makezine.com/projects/electromagnetic-aluminum-levitator/I'd like to have better control over the voltage, ideally with variable adjustment.Because I’m on a budget, I purchased a relatively inexpensive MCU Inside UX-52 Inverter via Amazon.Product link: [https://www.amazon.de/Frequenzumrichter-Mini-Motorwechselrichter-176-264-Eingang-Wasserpumpen/dp/B0D2WX2ZC7/ref=sr_1_2?__mk_de_DE=ÅMÅŽÕÑ&crid=D3XEJTNKV8L2&dib=eyJ2IjoiMSJ9.mv3EFlL66ZdypzvJxDYOe3wiuRmkadnB7yKt2szt72bFt5_DZ1rZGkaCjGc1uOB2vaMujTNw79RsEjAPo4hFbA.FK85qlaMX8lIBHBYXRtgVsZynvaTVLE5zvqAXqo6bnk&dib_tag=se&keywords=1,1kw+frewuenzumrichter+1ph+176-264vMCU+Inside+UX-52+Inverter&qid=1751143861&sprefix=1+1kw+frewuenzumrichter+1ph+176-264vmcu+inside+ux-52+inverter,aps,94&sr=8-2]The photos below show my actual device:My question: Has anyone used this model or is familiar with how this inverter is controlled?According to the datasheet, it takes a 230 V AC input and provides a 3-phase AC output: 0–220 V / 1–400 Hz.👉 I’d like to know if it’s possible to adjust the output voltage while keeping the frequency fixed (e.g., 50 Hz). Or is the inverter locked into a V/f (voltage-to-frequency) ratio, meaning that voltage and frequency are always scaled together?If it is possible: How do you configure it? Is there a menu setting to manually define output voltage at a fixed frequency?I’d really appreciate any tips, experiences, or technical insights!Thanks a lot and best regards

author: jwet
author_rank: Frequent Contributor
timestamp: July 01, 2025, 01:19:06 pm
content: I'll take a stab since you got no replies. Maybe someone wiser can chime in.Simple AC motor controls have voltage and frequency linked. I believe they maintain a constant ratio of V to (square root of F). The speed is set by the frequency but you have to adjust the voltage to make things balance out. Many moons ago, some sadistic professor made me derive why this is so but that brain cell is long gone. If you google V/rt Hz or similar, you'll find some stuff. I imagine you'd like to have something similar with your coil. You're trying to scale flux really which involves both V and F (or time). I'm not smart enough to derive that stuff anymore but I'll bet you can find some references somewhere.I looked through the table of what you can tweak in your box and didn't see this, its likely not something worth adjusting for motors.

author: WattsThat
author_rank: Frequent Contributor
timestamp: July 01, 2025, 01:57:20 pm
content: As already stated, a VFD is not designed for fixed frequency. After all, the acronym is Variable Frequency Drive and the VFD output characteristics of Volts per Hertz are exactly what you want if you want a variable force.A VFD is designed to control a motor where keeping the output voltage and frequency tracking together at a ratio keeps the magnetic flux in the motor constant over its operating range. This keeps the relationship between amps and torque constant. Torque in a motor would be the same as the force created by your electromagnet. So, if you fix the frequency and only vary the voltage, you get changing flux (the magnetic coupling force) resulting in high amps and low force. Not what you want.All that said, the VFD may or may not be able to power your coil. Don’t overlook the fact the you’re in France where mains are 240V 50Hz and the maker coil is (designed?) for 120V 60Hz. You could setup the VFD for a maximum output of 120V 60Hz if you wound/built the device per the original plans. What we don’t know is if the VFD can deliver the amps required by the coil as it doesn’t appear to be documented. The VFD is capable of 6 amps?Another VFD issue is that it expects the output current to be balanced across the three output terminals, you’ll only be using two. That may result in a fault which hopefully the VFD can programmed to ignored if it doesn’t like the single phase output.