+ v 0-pk - i l (t) + v l (t) - + v s (t) - v s (t) i s (t) i 1 (t) i 2 (t) i 3 (t) i 4 (t) full wave...
TRANSCRIPT
+V0-pk
- iL(t)+
vL(t)-
+vS(t)
-
vS(t)
iS(t)i1(t) i2(t)
i3(t)i4(t)
Full Wave Rectifier
i1(t)=i3(t)i2(t)=i4(t)iL(t)
=i1(t) + i2(t)=i3(t) + i4(t)
=i1(t) - i4(t)=i3(t) - i2(t)
vL(t)iS(t)
+V0-pk
- IL
+vL(t)
-
Full Wave Rectifier
iR(t)
vL(t)
iR(t)
+VL
-
ic(t)
VL
IL
is(t)
ic(t)
is(t)
By inspection: IS = IR (RMS)
2
T
Diode Off, Capacitor Discharging
Diode On, Capacitor Charging
Ipk
2pkI
Q
2DC pk
QI I
T T
For Full Wave Rectifier2DC pk
QI I
T T
For Half Wave Rectifier
T
Diode Currents
Current Distortion – BAD juju
• Excess currents in distribution infrastructure– Heat– Wasted Power/Lost Revenue
• Shunt capacitors– High currents due to low reactance at
harmonics– Undesired resonances
• Induced distortion of Voltage Waveform
Power Quality GuidelinesIEEE-519Consumers – Limit Distortion on load current waveformUtilities - Limit distortion of voltage waveform
Isc/I1 Odd Harmonics THD %
H < 11 11< h <17 17< h <23 23< h <35 35< h
<20 4.0 2.0 1.5 0.6 0.3 5.0
20 - 50 7.0 3.5 2.5 1.0 0.5 8.0
50 - 100 10.0 4.5 4.0 1.5 0.7 12.0
100 - 1000 12.0 5.5 5.0 2.0 1.0 15.0
>1000 15.0 7.0 6.0 2.5 1.4 20.0