I was wondering what would be the frequency of the current harmonics at the input of a 1phase diode bridge rectifier. My believe is that it should be 60Hz for Is1, 180Hz for Is3, essentially every 60Hz for an odd component.
Electronic – Frequencies of current harmonics 1 phase diode bridge rectifier
bridge-rectifierdiodespower electronicssingle-phase
Related Solutions
simulate this circuit – Schematic created using CircuitLab
Figure 1. Centre-tapped energy harvester.
If you double the coil windings you can halve the diode losses as shown in Figure 1. Only one diode will be conducting at any time compared with two on a full-wave bridge.
Since each winding conducts only half the time the wire gauge can be reduced for the same total output power.
It won't hurt to parallel the diodes and may result in ever-so-slightly lower voltage drop.
it's not surprising you are seeing close to 20Vdc at the output. The nominal voltage of your transformer secondary is 12Vac (which could be even higher ~14Vac). Now, the ac voltages you have are RMS. So the capacitor is going to charge up to the peak value of the sine wave, which is 12Vac*sqrt(2) = ~17V for a secondary output of 12Vac. If this were more like 14Vac at the secondary, it would make sense why you are seeing 20Vdc at the output.
Related Topic
- Electronic – Can somebody explain why normal diode(1N4001 or 1N4007) is used in rectifier bridge insteed of schottky diode
- Electronic – Diode Array for Full-Wave Rectifier for PoE
- Electronic – Use of different diodes in a bridge rectifier
- Electronic – Difference between Peak rectifier vs Full wave rectifier
Best Answer
Consider approximations that you have low ripple voltage Vpp< 10% Vavg.
Then a current pulse per cycle must Ipk must be 10x the average current in <10% of the T cycle time to maintain this average current load.
So you must realize a narrow pulse that rises fast and tapers off slow must have at least all the harmonics of the fundamental up to the 5th harmonics at least and attenuated up towards the 10th harmonic. There will be more below some threshold such as -20 dB of pk.
f-3db=0.35/Tr holds true from 10~90% rise time , Tr for the -3dB BW of spectrum.
Odd harmonics only hold true for Square waves and their integrals like Triangle waves.