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There are multiple ways for doing that. You can use a mixture of current and voltage feedback or current only. In general you are trying to get a measure of phase difference between two signals that represents your offset between driver frequency and resonance frequency. The main difficulty is to measure the resonator current at resonance (or close to it), as it is not only a very high current but also at high frequency.

Hello, I haven't looked at the temperature of the transformer but I intend to measure and regulate the primary current of the transformer in order to not draw to much current and save the IGBTs and Diodes. I also want to measure the power from the grid twice a second with a PZEM-004T module. This way I hope to get good control over the Power draw of the unit. But if you say I should, then I will also measure the temperature of the Transformer while in development. I don't think I could add another secondary because of the core diameter. I use 8mm copper tubing for the secondary circuit. I will upload some update videos of the induction heater. How did you program the μC in order to lock the frequency? Do you have a video on TH-cam where you show your unit? I would be interested to see it. Best regards

@@dickesf8525 Its a good idea to measure the input power. I currently have an 100A AC meter that measures the line amperage. You mentioned the PZEM-004 module. Does this take into consideration the power factor? The microcontroller is the atmega8 that is programmed with Arduino. The microcontroller measures the phase difference between the capacitor voltage and the Inverter voltage. Theese voltages are fed into the xor gate of the pll ic. Different phases give different duty cycle of the output of the xor gate. The microcontroller reads that and applies a compensated voltage on the pll ic in order to keep the phase 90degrees. Its important to begin scanning from a higher frequency than the Fresonant. My current protection circuit works with a current transformer of the primary fed into a comparator. If the limit is exceeded the output of the comparator triggers a flip flop circuit that shuts down the pll ic. Lastly my only way to reduce the power is to detune the circuit (increasing the frequency above the resonance). I don't have a TH-cam video yet, i will upload one though.

​@@livewire2404 Yes the PZEM-004T measures the voltage, current and frequency and calculates the power factor, as well as the real power and also keeps track of the used energy. It is basically a complete power meter module with UART interface and Arduino library. I will use an STM32f303 controller though. So you are using an PLL IC, probably the 4046, and then you are using the µC as the filter between the phase comparator and the VCO? And by adjusting the voltage into the VCO via software you are controlling the power of the system?! I thought about implementing a software PLL but I am not sure if the 72MHz STM is fast enough here for the ~60kHz of my Oscillator. I will se how this will go.

@@dickesf8525 Yes, and the 4046 is providing the PWM pulses to the inverter. By adjusting the voltage on the VCO pin (pin 9) i can vary the frequency. The μC provides a pwm signal that it is filtered into a dc voltage to the VCO pin. The frequency of the pwm doesnt matter as long as its filtered to pure dc voltage. The duty of this pwm signal is propotional to the output frequency of the pll. You can skip the 4046 ic if you use direct pwm from the stm32. Make sure to calculate if the 16bit timer has good frequency resolution in order to adjust the frequency precicely in order to have a phase lock. I would recomend an external xor gate to measure the phase diference between the inverter voltage and the capacitor tank voltage. I think you would need more capacitance on the DC after the rectifier. The ripple current is very high and it would destroy theese caps. Also with more stable DC voltage you would get more power out of it. I am curious about your AC mains filter. Looks like some components of switch mode power supplies. Why is there an additional bridge rectifier next to the large blue capacitor? Also i had used similar cooper tube iron couplers and they got red hot at power levels more than 3kw. You can change them out to brass ones. The iron ones add some inductance and alot of losses.

@@livewire2404 Isn't it also possible to use two signals, which are already 90° out of phase with the 4046?! If I am correct one could also measure the pahse difference between the capacitor voltage and the resonator current. The STM32 has also one 32-Bit timer. I have to check again. An external XOR Gate could work, but I should use one with Schmitt-Trigger, right?! I only had the space for two of the smaller caps, but i left some space for bigger screw terminals so that i could add some external ones later. The caps got a littel warm, I noticed that but it was ok. The main AC component should hopefully come via the snubber cap but I can only try and see now. Otherwise this would be an easy upgrade. The mains filter is something I think of as mandatory and slightly displeasing at the same time because i just used parts from an old device that I still had and soldered them together the same way as before. I don't think this filter is working too well with the currents present. The Chokes got quite warm. The additional FBR is dead and was used before i bought the bigger one. A new Filter PCB is in the making. The copper tubing would indeed melt but i watercool it and it stays at room temperature this way. The water however heats up quite fast and I need a bigger tank. The couplers are made out of brass and plated with crome for the looks. My father had them laying around and I took them because new ones for the 8mm tubing were quite expensive.

Moin! Zum Einen ist er einstellbar, zum Anderen hatte ich ihn gerade rumliegen. Allerdings wäre ein Buck/Boost-Wandler besser gewesen, weil der die Spannung auch hoch setzten könnte.

Ich hatte drei von denen mal auf einem Elektronikflohmarkt gekauft. :)

Danke

Danke 👍 Wie gut das Audio zu hören ist hängt meiner Erfahrung nach stark vom Duty-Cycle ab. Der Duty-Cycle für die maximale Lichtbogenlänge ist leider nicht der gleiche wie der für ein möglichst gutes Audio Erlebnis. Das hätte ich im Video etwas besser einstellen können. Danke für den Hinweis.

@@dickesf8525 den kannste aber bei 50:50 einstellen und da solltlest aufjedenfall gutes audio haben oder dein vorverstärker reicht nicht

Ich freue mich auf weitere Videos von dir ;)

Danke, danke! So viel Lob auf einmal. Grüße zurück!

Danke! 😁👍

Die Zeit war bei meinem RTC Modul voreingestellt. Man kann aber über ein, zum RTC Modul passendes, Arduino Sketch selbst eine Zeit vorgeben.

@@dickesf8525 kannst du mir vielleicht bei der Programmierung meiner Uhr helfen?

Ich wüsste nicht wie ich dir direkt helfen könnte, aber ich kann den Code für meine Uhr noch in die Beschreibung tun. Mit den Programmiertutorials auf TH-cam solltest du das dann gut hin bekommen. :) Die Videobeschreibung werde ich im Laufe des Tages dann mit dem Code oder einem Link dazu ergänzen 👍

@@dickesf8525 genau das hilft mir nichts. Habe einen Sketch, einen arduino und die Hardware für die Uhr. Bei vielen Leuten funktioniert der Aufbau nur ich scheitere daran. Bräuchte Hilfe von jemandem der Ahnung hat und sich den Sketch mal anschaut weshalb es bei mir nicht funktioniert

In dem Fall kann ich dir auch nicht helfen. Für diese spezielle Art von Unterstützung solltest du dich bei einem der entsprechenden Foren (EEVblog Forum, Mikrocontroller.net, usw.) anmelden. Da kannst du den Leuten deinen Code und deine Schaltpläne zeige oder was du halt dazu so hast und die können dir Helfen. Über TH-cam geht sowas leider nicht.

Definitiv.

Moin. Ob Dali das auch so macht weiß ich nicht aber generell funktionieren Bändchenlautsprecher nach diesem Prinzip. Der Aufbau ist bei gekauften Modellen natürlich deutlich professioneller, vorallem in Bezug auf den Wirkungsgrad usw.. Die gekauften Modelle haben beispielsweise Viel mehr Lamellen und sind viel Dichter aufgebaut.

@@dickesf8525 vielen Dank für deine schnelle Rückmeldung! :) Klingt alles sehr plausibel was du sagst, habe Mal gehört sie seien sehr feuchteanfällig .. denkst du man muss aufpassen dass man eine gewisse Luftfeuchte Grenze nicht überschreitet?