10 Kilowatt Induction Heater

[Ubergeek63]

If you have this stuff sitting on a table, and you have no shielding or PPE no matter what you think your design is capable of you are taking ZERO safety precautions. What I described to you is not exaggerated. I saw it happen to a guy three years ago. and he had 25 years experience as a licensed professional. If you are only 15 there is no way you know enough to do this right. I read the part where you have an underrated transformer and had to give it several hours to cool between uses. Every time you overheat it that way you are slowly breaking down it's dialectic material. At some point it will fail and start an arc flash event. I fear for you and your family's safety I wonder if your parents know what you are doing in their house. You need to do a reality check. I am pretty sure this will not change your mind. Go find a professional power electronics engineer and show him what you are doing and let him read this. I have no doubt he will verify what I have told you

My wife's response to this kid is that rewiring his anal penetrator for dual voltage does not qualify him for what he is attempting

to that I might add he should disconnect the wires from the bolts in his neck as well

 

[MOSFET KILLER]

@Sceadwian--I have a 60 amp service in my garage to power my welder, LASER and eventually metal casting setup. It works fine since I have a 200 amp service at my house and have never maxed it out.
@tcmtech--Thank you for not discouraging me from taking on this quite impulsive task. I remember playing with HV boost converters several years ago, I had one up to 1100 volts with a single stage boost converter (but that's with no load .
@SLACer--I am not like most 15 year old kids, I believe that you have people of my age stereotyped. I am aware of the dangers of arc flash, but as tcmtech said, at this voltage and current 6'' is greatly exaggerated. I am going to get everything approved by other minds and test everything at low power before I plug this into the 240V.

 

[MOSFET KILLER]

@Ubergeek63--You are a real piece of work, next time keep it to yourself, I have a really good reason to build this now, to shut you up!

 

[MOSFET KILLER]

Anyway, with that unpleasntness behind us, not to name any names. I have a rough schematic of the power supply. I have not got around to labelling any parts yet. The PFC pre-regulator contains two boost converters in parallel but driven 180 degrees out of phase. The IC that I am using is a UCC28070, it is an interleaving CCM power factor correction controller. The buck regulator is controlled by the circuit in the previous schematic. The relays form a soft start circuit that will prevent massive current from being drawn to charge the filter capacitors. The two current transformers are 1:100 and run back to the UCC28070.

 

[Ubergeek63]

@Ubergeek63--You are a real piece of work, next time keep it to yourself, I have a really good reason to build this now, to shut you up!

wont shut me up even though it will be amazing if you succeed without doing damage. mind you the authorities would think otherwise ... not to mention that you are invalidating your house insurance and if something does happen the insurance company is going to laugh at your dad when he tries to collect!

 

[tcmtech]

At 15 he is still a minor and as far as I understand it thats sort of what insurance is for, to cover the costs of damage that kids occasionally do!
If he is building a 10 Kw induction heater I suspect dear old dad has his eye on him anyway.

In his first post on the second paragraph he clearly states he has a 60 amp line available to work with. I know many city people who have a similar line in their garages so at least around here it quite common.
Many city folks have campers and RV's that often require a 240 volt 30 amp or greater line for an external power source when they are parked (my grandparents one does).
As far as I know that makes them perfectly legal and up to code by having a 240 volt outlet for what ever reason they need it for.

 

[tcmtech]

If you are running into problems with HF transformer power limitations I would suggest checking with your local welder and plasma cutter service shop and see if you could get a used HF transformer cores from a big inverter welder or plasma cutter. Most often the windings burn up but the cores stay intact. Plus they are specifically built for high power operation for extended time periods.

If you cant find any locally I have a few mid sized transformers from inverter based plasma cutter power supplies that ran in the 5 -6 Kw range. I would be willing to donate an old set of them to you for experimenting with just for the cost of shipping for around $15.

 

[MOSFET KILLER]

@tcmtech--My dad knows that I am building a 10 kw induction heater, I have to tell him considering that I am using his basement to build this in. He does not have much understanding of electronics but he can see that I am taking appropriate safety precautions and he is not worried.

When the electrician wired my 60 amp panel, he said everything was done legally, whatever I choose to hook up to it is my own problem. He did laugh when I asked him to label one of the breakers LASER. He said in 25 years it was the first time he had ever heard that .

 

[MOSFET KILLER]

I will need a decently sized output transformer that can handle 10 kw without saturating. Saturation would explode the inverter. I will need a transformer that I can fit several turns of #6 wire and 2 turns of 64mm copper tubing for the secondary.

 

[MOSFET KILLER]

Does anyone have any experience with active power factor correction? I want to design a circuit to keep the input power factor low >0.9. The circuit that I have planned uses the UCC28070, does anyone have any experience with the '28070? This is the first time I have attempted active power factor correction but I will need it for this project.

 

[MOSFET KILLER]

Inverter schematic is here!

It is a standard halfbridge, nothing special.

 

[MOSFET KILLER]

Current Sense Transformer

I am designing a circuit to provide current feedback to the control circuit. I want isolation from the output of the inverter which is at 320V and is off the line!

So, let's start with materials, iron powder is out because it gets really hot from the high frequency current. So, we need a ferrite core that will not saturate. I will be using a toroidal core with 100 turns of #20 wire.
Here are the specifications:
--> 10 kHz minimum frequency
--> Up to 100 amps peak
--> 1 turn primary, 100 turns secondary
--> 320 volts peak

Next is the burden resistor value.

100A/100=1A
1A*2.2Ω=2.2V
100 amps is redundant, it is just an absolute maximum rating.

60A/100=0.6A
0.6A*2.2Ω=1.32V
60 amps is a more reasonable estimate which gives 1.32V output.

The wattage of the burden resistor is also important.

1A*2.2V=2.2W

0.6A*1.32V=0.792W

A 2 watt resistor should be sufficent for this application since we are only looking at an expected 60 amps peak under normal operating conditions.

<Edit>
I just read that a burden resistor should not be used for more than 55% of it's power capacity due to changes in value as heat builds up. I may go for a 3-4 watt resistor because this is a very important component and its failure could cause undesireable consequences. I know that this is overkill but a higher wattage resistor is not that expensive and I just want to be 100% sure that this will give me accurate results.
</Edit>

I will use a comparator to turn the current waveform into a square wave for the phase comparator. Another comparator will form a peak current detector to trip an SR latch and shut down several different parts of the curcuit. Current feedback will also be used to limit voltage at the buck converter to keep the output power constant under different operating conditions such as loading.

So, I guess my main question is how to pick a ferrite core material and size for this application?

Alex Sears

 

[usefi5961]

dear sir:
in ozon generator(8kw) used ixfn27n80 that i can not find it please help me can i used 2 igbt parallel instead it?
the mc33262 used in circuit.can anyone give me other schematic for pfc 10kw?

 

[chfazi]

10 kilowatt induction

dear sir i want to 10 kilowatt induction complete diagram with application........