Hi,

For my wireless power transfer, the picture shows the secondary side (Receiving).
I'm trying to measure the efficiency of full bridge rectifier by using "eff = (v2*i2) / (v1*i1)" and i'm getting very wrong result.
Voltage is measured with oscilloscope and current with multimeter.

v2 = 17.982v (dc coupled) & i2 = 0.22a (dc) hence p2 = 3.956w

v1 = 32.5v (ac coupled) & i1 = 0.0615a (ac) hence p1 = 1.998w
and eff value would be 1.9799

what am i doing wrong ??

R1 is the resistor load, 83ohm.
L1 is the secondary coil.

for diodes, i'm using 1N5711 schottky diode.
frequency is at 53khz.


thanks

 

How arte you measuring the voltages and currents?
Are you reading RMS, average, peak, or peak to peak?

 

How arte you measuring the voltages and currents?
Are you reading RMS, average, peak, or peak to peak?

Voltage(rms) by oscilloscope. Ac coupled for v1 and dc coupled for v2. Current by multimeter

 

The oscilloscope has an RMS function but how about the multimeter. Standard (cheap) multimeters read average values.

 

The oscilloscope has an RMS function but how about the multimeter. Standard (cheap) multimeters read average values.

with a fluke 175 true rms multimeter

 

Hello,

The capacitor C1 will act as a wattless voltage dropper.
The value will influence the output voltage.

Bertus

 

Hello,

The capacitor C1 will act as a wattless voltage dropper.
The value will influence the output voltage.

Bertus

Hi, how then should i measure the efficiency of the rectifier? The c1 is resonant cap for wpt.

 

This is how over unity devices created: misunderstanding how AC power is calculated. You cannot get average power by multiplying average voltage by average current. You have to integrate the product over the entire period. The phase of the two makes the difference.

Bob

 

the I₁ likely should be at "primary's" "return" node - from D2 D4 -or- at the other side of the capacitor -or- both "averaged" + ? about your waveform

 

Do you suppose the fact that a 1N5711 is only rated at 15 ma continuous current (or average current in your case) has anything to do with the problem?


Consider the 1N5819, it was designed for the kind of circuit you have.