Sunday, 9 September 2012

Charging circuit



The main circuit for this Wind Power Generator in Train System is charging circuit. The system is using wind generator to charge the 12VDC battery. A relay is used to start or stop charging. This relay is controlled by PIC microcontroller. Whenever the charging operation is running, a LED indicator will turn on else the LED indicator will turn off.

Two voltage dividers are being used to detect battery voltage and wind generator voltage. The voltage divider is used to avoid over voltage over 5V access PIC microcontroller. 



Below shows the calculation for the voltage divider:-
  •        When voltage input from wind generator or battery is 15.64V, PIC will get maximum voltage 5V.



Ratio = Voltage input from wind generator or battery / PIC voltage
Ratio = 15.64V/5V
Ratio = 3.128/1
So, the ratio is 3 to 1

Voltage divider formula:-
VDR = [R1 / (R1+R2)] x Vin

[4.7k / (4.7k + 10k)] x 5V = 1.599V
[10k / (10k + 4.7k)] x 5V = 3.401V
Total voltage = V1 + V2
Total voltage = 3.401V + 1.599V
Total voltage = 5V

3.401V x 3.128 = 1064V
1.599V x 3.128 = 5V
Total voltage = V1 + V2
Total voltage = 10.64V + 5V
Total voltage = 15.64V

So, input voltage must not exceeding 15.64V or else PIC will burn because PIC only supports 5V.

2 comments:

  1. Hi,
    I want your help to understand one of the line in your program.
    set_adc_channel(1);
    delay_ms(10);
    adc2=read_adc();
    mybat=adc2/65.41;
    delay_ms(10);

    how did you calculated 65.41

    ReplyDelete
  2. It is a useful and charming post.It is extremely helpful for me.

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    ReplyDelete