I am studying conversion ratio of a halfwave rectifier from here.
It says that
Conversion ratio (also called "rectification ratio", and confusingly, "efficiency") η is defined as the ratio of DC output power to the input power from the AC supply. Then the definition of conversion ratio is given as: $$\eta=\frac{P_\text{DC}}{P_\text{AC}}$$ where \$P_\text{DC}=I_\text{DC}^2R_L\$ calculated using average dc current and \$P_\text{AC}=I_\text{RMS}^2(R_L\$+Resistance of secondary coil+ diode forward resistance).
I am unable to understand its intuitive meaning and have the following questions:
- If the output of halfwave rectifier is given by DC voltage that has ripples, which we consider as the time varying part, then how does RMS voltage contribute to that time varying part so that it can be considered as an AC component.
2 How exactly does RMS voltage capture the time varying part when its definition says that here.
For alternating electric current, RMS is equal to the value of the constant direct current that would produce the same power dissipation in a resistive load.
- Does RMS voltage some how relate to the concept of variance and DC voltage to mean, so we have a mean part and RMS is the variation around it? No doubt RMS voltage is calculated like square root of second moment of a PDF.
Most of the answers seems to say that efficiency as the percentage of power delivered to the load, relative to the input power.
This is not the case here. Please note that for input I_rms is used while for output I_dc.
Interestingly, I_rms is also supplied to the load resistor for the halfwave rectifier (\$I_{RMS}=I_m/2\$ and not \$I_\text{RMS}=I_m/\sqrt(2)\$)definitely it is the \$I_\text{RMS}\$ after passing through diode. Why not take efficiency in terms of only I_rms? Definitely there is some time varying part of DC that is playing a role here. Therefore it is not efficiency but conversion ratio.
An interesting observation:
For AC current with zero DC:
I_dc=0, I_rms=I_m*0.707
For half wave rectifier output:
I_dc=0.318 I_m, I_rms=I_m*0.5
For pure DC:
I_dc=I_rms
As the amount of AC component/ripples decreases the I_rms is getting closer to I_dc
Please check here to not get confused conversion ratio with efficiency