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Inductive coupling help reqd..

T

TT_Man

Jan 1, 1970
0
I have a product that I want to upgrade to inductive coupling for battery
charging. The base could fit inside the source coil, but the coil would need
to have an internal diameter of about 3" This could completely enclose the
receiver coil in the base of the unit. E.G two concentric coils.. Charge
current needs to be in the order of 100mA @ 10V.
Is this feasible using a 230V mans coil ? Efficiency is not an issue.
Most of my searching reveals high frequency type systems. Is this mandatory?
 
B

Baron

Jan 1, 1970
0
TT_Man said:
I have a product that I want to upgrade to inductive coupling for
battery charging. The base could fit inside the source coil, but the
coil would need to have an internal diameter of about 3" This could
completely enclose the receiver coil in the base of the unit. E.G two
concentric coils.. Charge current needs to be in the order of 100mA @
10V. Is this feasible using a 230V mans coil ? Efficiency is not an
issue. Most of my searching reveals high frequency type systems. Is
this mandatory?

There are one or two electric toothbrushes that use this trick to charge
the battery in the brush from 240V 50Hz.
 
J

John Tserkezis

Jan 1, 1970
0
TT_Man said:
I have a product that I want to upgrade to inductive coupling for battery
charging. The base could fit inside the source coil, but the coil would need
to have an internal diameter of about 3" This could completely enclose the
receiver coil in the base of the unit. E.G two concentric coils.. Charge
current needs to be in the order of 100mA @ 10V.
Is this feasible using a 230V mans coil ? Efficiency is not an issue.

Efficiency IS an issue. There are more ramifications that a few cents per
year extra in power consumption. Melting plastics for one thing (albeit for
higher power devices).
Most of my searching reveals high frequency type systems. Is this mandatory?

Makes for smaller coils for one thing. Depends on how "portable" you want
to make the device.

Again, don't disregard little things like this. I replaced my cordless
drill battery with an SLA type I had on hand, because it was quick and easy
and I couldn't be bothered going out to buy the proper one the next day.

Nearly 6 pounds in the battery alone. Great capacity, but ruins the balance
and more importantly, the aesthetics of the tool.
 
J

Joerg

Jan 1, 1970
0
TT_Man said:
I have a product that I want to upgrade to inductive coupling for battery
charging. The base could fit inside the source coil, but the coil would need
to have an internal diameter of about 3" This could completely enclose the
receiver coil in the base of the unit. E.G two concentric coils.. Charge
current needs to be in the order of 100mA @ 10V.
Is this feasible using a 230V mans coil ? Efficiency is not an issue.
Most of my searching reveals high frequency type systems. Is this mandatory?

Pretty much, since 50/60Hz doesn't couple too well. Mainly because you'd
need oodles of turns to get up to the required inductance and also
because it's a fixed frequency.

The trick is to make the setup series resonant. Typical frequencies at
this power level are in the 50-100kHz range.
 
T

TT_Man

Jan 1, 1970
0
Joerg said:
Pretty much, since 50/60Hz doesn't couple too well. Mainly because you'd
need oodles of turns to get up to the required inductance and also because
it's a fixed frequency.

The trick is to make the setup series resonant. Typical frequencies at
this power level are in the 50-100kHz range.

O.K. Does anyone have any pointers for a reference design? My google
searches have come up with very little...
 
J

Joerg

Jan 1, 1970
0
TT_Man said:
O.K. Does anyone have any pointers for a reference design? My google
searches have come up with very little...

Haven't seen any on the web and I can't disclose any stuff I did for
clients. Just look for series resonant converters. The trick is to
mitigate the inevitable huge leakage inductance that results from the
coils' poor coupling but you can only do that for one side. That would
usually be the input side.
 
J

JosephKK

Jan 1, 1970
0
Efficiency IS an issue. There are more ramifications that a few cents per
year extra in power consumption. Melting plastics for one thing (albeit for
higher power devices).


Makes for smaller coils for one thing. Depends on how "portable" you want
to make the device.

Again, don't disregard little things like this. I replaced my cordless
drill battery with an SLA type I had on hand, because it was quick and easy
and I couldn't be bothered going out to buy the proper one the next day.

Nearly 6 pounds in the battery alone. Great capacity, but ruins the balance
and more importantly, the aesthetics of the tool.

I will leave unsaid but hinted at my utterly derogatory assertions
about worrying over the aesthetics of a tool over the function.
 
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