inductive charger question...about dc to ac to dc conversion
inductive charger question...about dc to ac to dc conversion
(OP)
I'm attempting to create an inductive charger. What are the most efficient ways to convert a dc power supply, into ac, and then after that ac is picked up by the recieving coil, what is the most efficient way to convert the ac back to dc? Right now i am using zener diodes, and am wasting a lot of power.






RE: inductive charger question...about dc to ac to dc conversion
RE: inductive charger question...about dc to ac to dc conversion
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If we learn from our mistakes,
I'm getting a great education!
RE: inductive charger question...about dc to ac to dc conversion
RE: inductive charger question...about dc to ac to dc conversion
------------------------------
If we learn from our mistakes,
I'm getting a great education!
RE: inductive charger question...about dc to ac to dc conversion
Can you describe more fully what you need to design. Originally you asked about an inductive charger but the discussion now seems to be about a DC-DC power supply.
RE: inductive charger question...about dc to ac to dc conversion
RE: inductive charger question...about dc to ac to dc conversion
RE: inductive charger question...about dc to ac to dc conversion
------------------------------
If we learn from our mistakes,
I'm getting a great education!
RE: inductive charger question...about dc to ac to dc conversion
RE: inductive charger question...about dc to ac to dc conversion
I think androidmj wants to get power from one piece of equipment to another separate pice of equipment without any galvanic connection between them. This normally uses two tranformer cores, one in each piece of equipment, which are brought into close proximity when power transfer is required.
When I worked for a previous employer we designed a means of transferring significant levels of power between two sealed units. The development unit used two ferrite cores, each carrying a winding, which when brought together completed a magnetic circuit. The magnetic circuit had a sizeable airgap (actually filled with plastic insulation, but in magnetic terms it was an airgap) which made its magnetising inductance large. This was nearly ten years ago so my recollection is sketchy, but the principle details were a half-bridge inverter driving the primary winding at a few kHz, fast rectifier on the secondary side for low losses, smoothing and a conventional DC/DC converter for the load. The magnetising inductance was tuned for resonance with a capacitor to reduce the drive requirements, and the drive circuit swung its frequency either side of nominal to maintain resonance when the magnetising inductance changed as the secondary core was removed or inserted - this was important in our application because we were transferring several kW across the gap and off-resonance currents were high.
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If we learn from our mistakes,
I'm getting a great education!
RE: inductive charger question...about dc to ac to dc conversion
RE: inductive charger question...about dc to ac to dc conversion
Can you reduce the power requirement?
<nbucska@pcperipherals DOT com> subj: eng-tips
RE: inductive charger question...about dc to ac to dc conversion
Can you describe what kind of load the desired DC output will see? Are you trying to charge a battery?
RE: inductive charger question...about dc to ac to dc conversion
One of your problems is that the leakage reactance is high with this kind of application. At the frequency you are using the coupling will be very poor as most of your driving voltage is dropped across the leakage reactance. You need to draw out the transformer equivalent circuit and examine how the leakage and magnetising reactances interact with your drive circuit. Consider using a much lower frequency - about 10kHz or so.
Yes, we used a full wave rectifier. We were transmitting about 6kW across the air gap with a secondary voltage of about 350V or so, so the power was considerably higher than in your application.
------------------------------
If we learn from our mistakes,
I'm getting a great education!