Hi All,
I am working on a project that will run an alternator to generate a charging voltage for a battery bank. I will be controlling the speed of the alternator to get my desired charge voltage (after the rectifier).
The charge voltage from the alternator/rectifier is fed to a battery bank via a FET switch so I can connect/disconnect with my microcontroller. The battery bank has a current shunt in series with the ground so I can measure the charge current in the bank.
My question is can I PWM the FET to control the amount of current? It seems by doing so, ultimately I would only be affecting the voltage (and the current by law)
What is the most effective way to control the current of this circuit? I would like between 2-4A and the charge voltages can range from 14V-55V depending on the battery config. So wattage from about 56-220W.
I am assuming simple resistor limiting will be super power hungry.
Thanks!!
...
Plus when the battery bank is powering a load instead of charging, I can limit the current instead of popping breakers.
You say a 12V alternator will charge a 55V bank....
Hi All,
What is the most effective way to control the current of this circuit? I would like between 2-4A and the charge voltages can range from 14V-55V depending on the battery config. So wattage from about 56-220W.
Seems like the best way to do it would be with the field voltage rather than trying to control the speed or trying to pwm it.
You can think of an alternator as a constant-current source, with an open-circuit voltage of ~120V.
That doesn't make any sense at all being alternators have voltage regulators that keep the output voltage constant while the load current can vary from zero up to whatever the upper limit is of the alternators output. Thats why alternators have voltage regulators not current controllers in their regulation systems.
Automotive alternators require a voltage regulator which operates by modulating the small field current to produce a constant voltage at the battery terminals.
Then why does a properly functioning alternator it try to put out a constant voltage, usually around 14.2 VDC and any amount of amps up to its designed working load limit while the current from it varies?...
Ya but the speed controls the frequency not the voltage.I will be controlling the speed of the alternator to get my desired charge voltage (after the rectifier).
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