definition of DC-AC inverter efficiency

[hearter]

We have heard people claim inverter efficiency up to 99%, but really what is the definition of efficiency? if you account for the heat dissipation by the tansistors and passive components, there is no way you can simulate the efficiency and 99% is definitely can not be achieved. anyone has insight on this topic?

thanks

 

[keith1200rs]

Why do you say that you cannot simulate the efficiency? By careful design and using synchronous rectifiers, very high efficiencies can be achieved. Have you any particular device in mind? The LM2651 has a peak efficiency of 97%, for example.

Keith.

The chip example I gave is actually DC-DC, but the same principles apply.

 

[Tahmid]

Hi,
Efficiency = ( Power out / Power in ) * 100%
99% efficiency would mean, with 100W power input, you get 99W power output. This, I feel, is not possible practically. Maybe upto 95%, higher becomes very difficult, since every component has some resistance, and wastes energy through that.
However, simple efficient circuits are those that reach 80-85% efficiency. Above that, the system would be highly efficient.

You can find the efficiency, like:
If you have an inverter, measure the output voltage and current flowing to load, measure the input voltage and current flow. Find Pout and Pin and find Eff = (Pou/Pin)*100%

Hope this helps.
Tahmid.

 

[hearter]

hello everyone,
I know Pout/Pin, what I don't know is that how do you take into account the heat dissipation by the swtching devices(such as H-bridge), these are major loss of power I believe. However, you can not simulate them, can you?

 

[keith1200rs]

Yes, you can simulate losses in all the devices providing you have models for them.

Keith.