blueroomelectronics
Well-Known Member
This has got to be a school project.
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The advantage of a shunt regulator is that it is really simple. The disadvantage is that it will dissipate more power as heat than a series regulator when the battery is fully charged. Both will charge the battery just as fast.Can I keep the battery voltage with in limits with out wasting power?
If you want to avoid heat build up, you need to use PWM in your series regulator.
This has got to be a school project.
Refer the schematic belowThe advantage of a shunt regulator is that it is really simple. The disadvantage is that it will dissipate more power as heat than a series regulator when the battery is fully charged. Both will charge the battery just as fast.
Once the battery is charged, there is no getting away from wasting power, no matter which method you use.
If you want to avoid heat build up, you need to use PWM in your series regulator.
Refer the schematic below
My load is 600mA at 12 V supply. The FET is driven from a microcontroller. This MC doesn't have a PWM output. The solution came to my mind is:
1. Sense the current through the load.
2.Convert to binary and feed to the MC .(I think three bits are enough for my requirement)
3.MC will change the duty cycle to the driver input.
Request your comments and suggestions on how to implement.
I would suggest the same solution as 'TChild' whats the problem with a 600mA constant current source.?
What configuration are you using for the LED's [series/parallel] and their voltage drop,?
Problem with constant current source (I think, you mean shunt regulation) is the poor efficiency, especially at higher input voltages (initial cost per watt for solar energy is high)
I use series parallel combination.
Using different colors of LEDs. Voltage drop 2V, 3.5V etc for different types.
At 12v supply, current is adjusted to be around 20mA through each LED.
hi,
Constant current is not shunt regulation.
hi,
Constant current is not shunt regulation.
I went through constant current source. i think, efficiency problem will remain in that case also. Right?
I think the only solution is switching regulation. Do you agree?
Have a look at this basic CC circuit.
at the end of the day ANY current and/or voltage regulation wastes current whichever type of linear regulating circuit you use, the only way to obtain maximum efficienzy is to use some sort of switch mode regulator
Let the input votage be 15.5V. The PWM will reduce the duty cycle. But peak current will be higher as the voltage applied is higher (FET acts as switch and battery has high current capacity). So I don't think battery or FET will not limit current. Right?With the Mosfet driven by PWM then the current-limiting is provided by the battery or the Mosfet.
It is true that higher current to be driven when duty cycle is less. But in the case of linear constant current source voltge is dropped by the series device and hence power loss. But in the case of PWM, the FET acts as a switch and hence efficiency is very high. So almost full power is supplied to the load.With the duty-cycle reduced then the current in the LEDs must be much higher to provide the same brightness as with DC.
So the PWM circuit is not more efficient than a linear constant current source.
Then the LEDs instantly burn out because the peak current is too high.But in the case of PWM, the FET acts as a switch and hence efficiency is very high. So almost full power is supplied to the load.