Power Electronics - Performance Parameters

It is important to determine the performance parameters for different converters whose topologies can be single phase or multi-phase.

Assumptions

The devices used are ideal, that is, they do not have any losses

The devices have resistive loads

$$V_{DC}=frac{1}{T} int_{0}^{T}V_{L}left ( t ight )dt$$

$$V_{L}=sqrt{frac{1}{T}}int_{0}^{T}V_{L}^{2}left ( t ight )dt$$

$$FF=frac{V_{L}}{V_{DC}}$$

$$RF=frac{sqrt{V_{L}^{2}-V_{DC}^{2}}}{V_{DC}}=sqrt{FF^{2}-1}$$

$$eta =frac{P_{DC}}{P_{L}+P_{D}}$$

Where the above are defined as −

$P_{DC}=V_{DC} imes I_{DC}$

$P_{L}=V_{L} imes I_{L}$

$P_{D}=R_{D} imes I_{L}^{2}$($P_{D}$ is the rectifier losses and $R_{D}$ the resistance)

$$eta =frac{V_{DC}I_{DC}}{left ( V_{L}I_{L} ight )+left ( R_{D}I_{L}^{2} ight )}=frac{V_{DC}^{2}}{V_{L}^{2}} imes frac{1}{1+frac{R_{D}}{R_{L}}}$$

But $R_{D}=0$

Therefore,

$$eta =left ( frac{V_{DC}}{V_{L}} ight )^{2}=left ( frac{1}{FF} ight )^{2}$$

$$TUF=frac{P_{DC}}{VA :Rating :of :the :Transformer }=frac{P_{DC}}{frac{VA_{p}+VA_{s}}{2}}$$

VA_p and VA_s are the primary and secondary power ratings of the transformer.