Efficiency Calculations for Power Converters

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A power converter’s effectivity (AC-DC or DC-DC) is set by evaluating its enter power to its output power. Extra exactly, the effectivity of the converter is calculated by dividing the output power (Pout) by its enter power (Pin). The Greek image Eta “η” is often used to signify “Efficiency.” Right here is the components for figuring out a power converter’s Efficiency (η).

η = Pout / Pin

For instance, the effectivity of a converter that gives 500W of output power (Pout) and requires 625W for the enter power (Pin), can be 80% (500W/625W=0.80). On this case, the enter power exceeds the output power by 125W or 20%, which is misplaced/wasted power. Due to this fact, 20% of the enter power is transformed to warmth power that have to be faraway from the converter somehow of cooling (conduction, convection, and/or radiation).

Since all power converters have inherent conversion losses, the output power is all the time lower than the enter power. Most frequently, the producer of the power converter specifies its effectivity and most output power on the product’s datasheet. When the effectivity (η) and output power (Pout) is thought, the end-user can decide how a lot enter power (Pin) will probably be required and the way a lot power will probably be wasted (Pwaste) and transformed to warmth power underneath full load circumstances.



Listed here are the formulation to find out Pwaste and Pin with pattern calculations utilizing the examples listed above.

Pwaste = (Pout/η) – Pout
Pwaste = (500W/0.80) – 500W = 625W - 500W = 125W

Pin = Pout + Pwaste
Pin = 500W + 125W = 625W

Clearly, with a better effectivity converter, Pwaste is lowered. Utilizing the instance above, however with an improved effectivity of 90% (as a substitute of 80%), listed below are the revised calculations:

Pwaste = (Pout/η) – Pout
Pwaste = (500W/0.90) – 500W = 555.5W - 500W = 55.5W

Per the examples above, by using a extra environment friendly power converter it reduces Pwaste from 125W to 55.5W, which offers a considerable financial savings to the consumer in each electrical power and cooling prices.

Listed here are alternate formulation for calculating the components related to power converter efficiencies:

Pin = Pout/η
Pwaste = Pin – Pout
Pwaste = Pout (1/η - 1)

In some formulation, Pwaste is known as Pd, the place “Pd” means the power dissipated (within the type of warmth) throughout the power converter. Pwaste = Pd.

When coping with AC-DC power provides, not solely is “Efficiency” necessary, however so is the power provide’s “Power Issue.” Details about the impact and significance of the power think about power provides is roofed within the following article.

Power Issue Correction

http://power-topics.blogspot.com/search/label/Power%20Factor%20Correction

Extra details about power converter efficiencies and cooling strategies/methods might be discovered at these net hyperlinks:

Power Converter Efficiencies

http://power-topics.blogspot.com/2011/06/power-supply-losses-and-impact-of.html
http://us.tdk-lambda.com/lp/ftp/other/cost-savings-high-efficiency.pdf
http://us.tdk-lambda.com/lp/news/2012_release05.htm

Cooling Strategies

http://power-topics.blogspot.com/2009/01/what-size-fan-do-i-need.html
http://us.tdk-lambda.com/lp/ftp/Other/cooling_bricks_ecn.pdf