heatpcb-designpowertransformer
I'm trying to design a step up transformer that can run my 220V heating element on 110V outlet. I've looked for such transformers through retail, but most of them are bulky and heavy.
Is there a way to design a smaller version of this bulky transformer, that will be able to provide 2000W of power to my 220V heating element running from 110V outlet?
What you could use is a boost converter such as the LT3573: -
This will charge up a capacitor to 300V. I reckon the parts would cost less than $20 and there are plenty of other similar chips of this type from Linear technology and TI for instance.
The circuit above produces 300Vdc and uses primary voltage sensing to determine the secondary voltage. Using what is known as a cockroft walton diode-capacitor voltage multiplier could get you much more than this quite easily. You would typically use this type of circuit directly on the transfomer secondary.
TAKE CARE - THESE VOLTAGES ARE QUITE LETHAL AND SCARY
Earthing or grounding is designed to protect the users of electrical equipment by preventing dangerous voltages to appear on metal casings, etc.
simulate this circuit – Schematic created using CircuitLab
Figure 1. Building supply neutral is earthed / grounded at the supply transformer.
In most countries the electrical utility grounds one of the wires from the local step-down transformer. This "neutralises" the wire as there is now no potential relative to earth. The live wire, on the other hand, has full voltage between it and earth. This explains why your transformer will work with the neutral wire connected to earth. The fact that it works also suggests that you don't have "earth leakage" or "ground fault" protection in your house. (You should have.)
My question is, What is wrong with this design, and why did it sort of work?
It sort of worked for the reasons explained above.
There is plenty wrong with your circuit:
Additional information:
Figure 2. Supply transformer supply and earthed appliance.
Yes Live is the supply, Neutral is the return and the Earth is protection. Normally there is no current in the earth wire but if, for example, a live wire fell off inside the appliance and contacted the metal there is a risk of electrocution. Earthing the appliance prevents the case rising to dangerous voltages. In the event of a severe fault a high current may flow but the fuse will then blow, making the system safe.
Double insulated devices don't need to be earthed so a two-pin plug is adequate.
Finally, what you are doing is dangerous given your poor understanding. I recommend that you work on low-voltage circuits until your knowledge of electrical theory is improved.
Best Answer
A two thousand Watt transformer is going to be big and heavy. For AC conversion the transformer is a good way to go though. They are efficient and produce real AC waveform outputs.
It is possible to envision a design that would convert the voltage by rectifying the input AC to DC. That would then be converted to a different voltage using a high frequency switcher design and then synthesize a fake AC output. Such device would not be trivial to build however but it could be smaller due to the smaller magnetics required.
Personally I think you would be way better off to set your 220 volt heater aside and get a replacement product that is designed from the outset to work on 110V. And surprisingly that may even cost less.