Kuliah DC Chopper

DC CHOPPER DESIGN

Performance parameter ;

1. Chopping frequency, fs
2. Choping period, Ts
3. On time of the chopper (ton) ton + toff = T
4. Duty cycle, k = ton/Ts
5. DC input voltage, Vs
6. Average output(load) voltage, Vo(dc) = k.Vs (for buck type)
7. Average output (load) current,
Io(dc) = Vo/R   (pure resistive load)
8. Dc input current, Is(dc)= k Io(dc)  (buck)
9. Output DC voltage, Po(dc) = Vo . Io
10. The peak to peak current of the inductor is given by :

 dI  = Vo (Vs - Vo)/(L . fs. Vs)

11. the peak to peak capacitor ripple voltage is given by :

 dV = dI /(8 C f)

 Let's Try
1. Chopping frequency, fs = 20 kHz
2. Choping period, Ts = 1/fs
3. On time of the chopper (ton)  ton = .
4. Duty cycle, k = ton/Ts = Vo/Vs =0,25
5. DC input voltage, Vs = 48 Volt
6. Average output(load) voltage  Vo(dc) = 12 volt
Load , R  = 5 Ohm


7. Average output (load) current,
Io(dc) = Vo/R  = 12/5 = 2,4 A


8. Dc input current, Is(dc)= k Io(dc)  (buck)  = 0,25 x 2.4 = 0.6 A



9. Output DC voltage, Po(dc) = Vo . Io

= 12 x 2.4 =28.8 Watt

10 dV <=2.5 %
   dV = 12 * 2,5% = 0.3 Volt
11. dI <=5%
   dI = 0,05 * 2.4 = 0.12 A

L = ?
C = ?

10. The peak to peak current of the inductor is given by :

 dI  = Vo (Vs - Vo)/(L . fs. Vs)

11. the peak to peak capacitor ripple voltage is given by :
  dV = dI /(8 C f)

Reference : Kuliah Pak Ekki Kurniawan