Transformers and Power: How Can Impedance Matching Improve Power Transfer?

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Discussion Overview

The discussion revolves around the concept of impedance matching in transformers and how it can improve power transfer to a load. Participants explore the relationship between load and source resistances, the role of transformer turns ratios, and the implications of complex impedance in the context of a homework problem.

Discussion Character

  • Homework-related
  • Technical explanation
  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • One participant notes the need for load resistance to match source resistance for maximum power transfer, expressing confusion about the requirement for "one additional component."
  • Another participant suggests that the load's complex impedance must be considered, including both resistance and reactance, and hints at the importance of transformer impedance matching.
  • There is a discussion about how to choose a transformer turns ratio to match the resistances according to the maximum power transfer theorem.
  • Participants calculate the reflected load impedance and discuss the relationship between load and source resistances, with one participant deriving a turns ratio of 1.04.
  • There are corrections regarding the calculation of the reflected load impedance and the sign of the inductor's impedance, with participants refining their understanding of the concepts involved.
  • One participant proposes an update to their calculations and discusses the need to draw a circuit diagram, questioning whether to depict an ideal transformer or an equivalent circuit.
  • There is a mention of adding two inductors to create the transformer circuit and whether these inductors need to have specified values.

Areas of Agreement / Disagreement

Participants generally agree on the importance of matching load and source resistances for optimal power transfer, but there are multiple competing views on the specifics of the calculations and the implications of the transformer turns ratio. The discussion remains unresolved on certain technical details and calculations.

Contextual Notes

Some participants express uncertainty about the calculations involving the turns ratio and the reflected impedance, indicating a need for further clarification on the relationships between the various components involved.

Who May Find This Useful

This discussion may be useful for students studying electrical engineering concepts, particularly those focusing on transformers, impedance matching, and circuit analysis.

  • #31
Aristotle said:
I see..I appreciate the big picture. So the reason why you changed the imaginary part seen from primary to load to "-j.16400" is due to the maximum power theorem correct?
Right. The load inductance is reflected into the primary as inductance (positive impedance value). The negative impedance of the capacitor cancels it when they are added together (they are in series). So the voltage source "sees" a purely resistive load.
 
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  • #32
gneill said:
Right. The load inductance is reflected into the primary as inductance (positive impedance value). The negative impedance of the capacitor cancels it when they are added together (they are in series). So the voltage source "sees" a purely resistive load.
Mind is blown :woot: Thank you again.
 
  • #33
I
problem sol'n.PNG


I must be missing something conceptually. How did you get this to a capacitor. This is what I tried
 
  • #34
Shenanigan_engineer said:
IView attachment 96947
I must be missing something conceptually. How did you get this to a capacitor. This is what I tried
Your first formula describes the impedance that the transformer presents to the rest of the primary circuit. Calculate that impedance without including the rest of the primary circuit.
upload_2016-3-6_18-35-58.png


Once you've done that you can consider the maximum power theorem for the new equivalent circuit in conjunction with the source voltage, its resistance, and whatever series device you choose to insert. Note that the equivalent impedance that the load presents to the primary is inductive. You choose a capacitor to add in series so that the maximum power transfer can be attained.
 
  • #35
That helps a lot, after applying that to the problem it was a lot clearer. Thanks a ton.
 

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