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# Transformers - PowerPoint PPT Presentation

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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Presentation Transcript

### 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.

No magnetic hysteresis

We also need to separate running with load and free running, as it’s particular case.

Dependence of coefficient against frequency (with load)

Dependence of coefficient against frequency (free running)

Dependence of coefficient against voltage

Dependence ofcoefficient against resistance

• Measuring parameters of our transformer

1st experiment: VAC

A

Ohm’s law:

V

We used small DC voltages to measure the resistance of the winding

Plot VAC, 1st winding

Plot VAC, 2nd winding

We will seek the solution of this equations in form:

theory

experiment

M(mutual inductance factor) depends on frequency because of depending µ on it

Diffusion flux dependence

Diffusion flux

Inside flux

Without core dependence

Rotation dependence

Linearization dependence

Part 2 dependence

• Describing all looses in the transformer

Losses dependence

We measured steel losses using the chain (right).

A

V

V

~

Dependence of dependencefull losses in the 1st winding against voltage

Dependence of dependencetemperature losses in the 1st winding against voltage

Dependence of dependencesteel losses against voltage

Dependence of dependencediffusionfluxagainst voltage

Rebuilding a chain dependence

We can rebuild our chain using diffusion inductance

Demonstration dependence. Ferromagnetic

Part 3 dependence

• Measuring and modeling hysteresis

Hysteresis dependence

Changing U dependence0

Modeling hysteresis loop dependence

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

Changing w dependence

Changing n dependence

• We are changing numbers of coil turns

A

V

V

~

Dependence of dependencecoefficient against number of turns

Theory dependence

Resonance mode dependence

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

Conclusions dependence

• Transformer coefficient depends on

• frequency because of the resistances of windings and the dependence of induction on frequency

• the load because of the resistance of the 2nd winding

• input voltage because of hysteresis mode

• turns number of the windings because of dependence M on it

Dependence of dependencesteel losses in the 2nd winding of voltage

Dependence of dependence coefficient against frequency (with load)

Unideal transformer dependence

Resistance of the winding

Losses of the flux

Losses in the core