Hello, I'm toying with the idea of a multi-channel battery charger. But a key component is a swtching transformer to provide isolate voltages to power the charging circuits for each channel. So I need a toroidal transformer with an input center tap (for push-pull) and eight 1:1 output taps that can work at at least 100kHz and support 10A per output winding (which would mean an 80A input winding I guess).
My design goal is for a charger than can chanrge a multi-cell pack from a 6V-24V source hence the 1:1 transformer ratio and the high current. In reality the current is usually going to be less by half as much or more. Each output winding is going to have a buck regulator that requires enough input voltage to run itself and produce 4.2V for the purpose of charging the battery cell. So the voltage on the output windings just has to be ~6V to power the buck. Being a 1:1 ratio, and the fact that usually a 12V supply or higher is available, the actual current in the transformer can easily be at least half as much, with the buck regulator stepping down the voltage and stepping up the current to required charging levels.
I'm having trouble finding the equations to figure out the core size to select and sources for said cores. I also don't have a feel for the numbers or materials, so if such a large transformer for such a high frequency is not possible, please let me know. Because from where I'm sitting, now that I actually typed out my requirements, I suspect it might be too large at too high a frequency.
My design goal is for a charger than can chanrge a multi-cell pack from a 6V-24V source hence the 1:1 transformer ratio and the high current. In reality the current is usually going to be less by half as much or more. Each output winding is going to have a buck regulator that requires enough input voltage to run itself and produce 4.2V for the purpose of charging the battery cell. So the voltage on the output windings just has to be ~6V to power the buck. Being a 1:1 ratio, and the fact that usually a 12V supply or higher is available, the actual current in the transformer can easily be at least half as much, with the buck regulator stepping down the voltage and stepping up the current to required charging levels.
I'm having trouble finding the equations to figure out the core size to select and sources for said cores. I also don't have a feel for the numbers or materials, so if such a large transformer for such a high frequency is not possible, please let me know. Because from where I'm sitting, now that I actually typed out my requirements, I suspect it might be too large at too high a frequency.
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