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Transformers

Transformers. Transformers. The "simple transformer law" relates output voltage to input voltage and turns ratio. Investigate the importance of frequency and other parameters in determining the non-ideal behaviour of transformers. The "simple transformer law".

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Transformers

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  1. Transformers

  2. Transformers • The "simple transformer law" relates output voltage to input voltage and turns ratio. Investigate the importance of frequency and other parameters in determining the non-ideal behaviour of transformers.

  3. The "simple transformer law"

  4. Using the Kirchhoff's andFaraday’s laws

  5. Neglects No magnetic hysteresis We also need to separate running with load and free running, as it’s particular case.

  6. Dependence of coefficient against frequency (with load)

  7. Dependence of coefficient against frequency (free running)

  8. Dependence of coefficient against voltage

  9. Dependence ofcoefficient against resistance

  10. Part 1 • Measuring parameters of our transformer

  11. 1st experiment: VAC A Ohm’s law: V We used small DC voltages to measure the resistance of the winding

  12. Plot VAC, 1st winding

  13. Plot VAC, 2nd winding

  14. Theory We will seek the solution of this equations in form:

  15. Vector diagram ~

  16. Inductance. Currentfading V

  17. Measures by currentfading

  18. Linearization

  19. Calculation from graph of inductance

  20. Theory and practice, dependence on frequency(with load) theory experiment

  21. Dependence M against frequency M(mutual inductance factor) depends on frequency because of depending µ on it

  22. Dependence on frequency(with load) after addition M dependence

  23. Diffusion flux Diffusion flux Inside flux

  24. Demonstration. Flux.

  25. Without core

  26. Rotation

  27. Dependence of coefficient against angle

  28. Linearization

  29. Part 2 • Describing all looses in the transformer

  30. Losses We measured steel losses using the chain (right). A V V ~

  31. Steel looses. Foucault currents r h

  32. Dependence offull losses in the 1st winding against voltage

  33. Dependence oftemperature losses in the 1st winding against voltage

  34. Dependence ofsteel losses against voltage

  35. Dependence ofdiffusionfluxagainst voltage

  36. Rebuilding a chain We can rebuild our chain using diffusion inductance

  37. Including diffusion flux

  38. Demonstration. Ferromagnetic

  39. Part 3 • Measuring and modeling hysteresis

  40. Hysteresis

  41. Changing U0

  42. Modeling hysteresis loop If we know all the coefficients, we can have as a result of our model real hysteresis loop

  43. Modeling changing signal

  44. Changing w

  45. Changing n • We are changing numbers of coil turns A V V ~

  46. Dependence ofcoefficient against number of turns

  47. Theory

  48. Resonance mode We can imagine a real winding as system of coils, resistances and capacitors.

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