Just another rough calculation
In order to be aware of the relation cuurent/ time I give you this example:
Resistance of the coil:___1Ohm
Inductance:__________1,5mH
Supply voltge:________36V
Current max.:________36A (as Ufo & Larry mentioned)
_______________________________
63,5% of max current - pulse time: R (Ohm)*C (mH) = 1.5ms -> 22.6A (63.5% of 36A)
99,9% of max current - pulse time: R*C*5 = 7.5ms -> 35.96A
________________________________
10Hz corresponds to_100ms full cycle
10Hz / 50% duty_____50ms pulse
The max. useful pulse time is 7.5ms
The not used surplus time is 50ms-7.5ms=42.5ms -> heat only
Required duty cycle for:
@10Hz: constant 7.5ms pulse:7.5% for 100ms fullcycle(10Hz)
q100Hz: constant 7.5ms pulse: 75% for 10ms (100Hz)
Conversely:
At the arrangement above the optimum frequency for 50% duty cycle and full current use is: 66Hz. Let some margin and go to 70Hz (time is somewhat shorter @50% duty cycle)
Please believe in Ufo employing a coil of 1Ohm. If you get lower it is not easy to handle it! In that case you get an extremely high shark fin for current comprising a short circuit to your battery after very short time.
But don't worrys about your battery! You sacrifice your beloved FETs as fuse! It is like burning dollar notes for heating your home.
In order to be aware of the relation cuurent/ time I give you this example:
Resistance of the coil:___1Ohm
Inductance:__________1,5mH
Supply voltge:________36V
Current max.:________36A (as Ufo & Larry mentioned)
_______________________________
63,5% of max current - pulse time: R (Ohm)*C (mH) = 1.5ms -> 22.6A (63.5% of 36A)
99,9% of max current - pulse time: R*C*5 = 7.5ms -> 35.96A
________________________________
10Hz corresponds to_100ms full cycle
10Hz / 50% duty_____50ms pulse
The max. useful pulse time is 7.5ms
The not used surplus time is 50ms-7.5ms=42.5ms -> heat only
Required duty cycle for:
@10Hz: constant 7.5ms pulse:7.5% for 100ms fullcycle(10Hz)
q100Hz: constant 7.5ms pulse: 75% for 10ms (100Hz)
Conversely:
At the arrangement above the optimum frequency for 50% duty cycle and full current use is: 66Hz. Let some margin and go to 70Hz (time is somewhat shorter @50% duty cycle)
Please believe in Ufo employing a coil of 1Ohm. If you get lower it is not easy to handle it! In that case you get an extremely high shark fin for current comprising a short circuit to your battery after very short time.
But don't worrys about your battery! You sacrifice your beloved FETs as fuse! It is like burning dollar notes for heating your home.
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