Transformer and Magnetic Circuit Fundamentals

This set of vocabulary flashcards covers the definition and uses of transformers, as well as core concepts of magnetic circuits including permeability, Magnetomotive force, magnetic flux density, and reluctance.

Transformer

A static device that transfers electrical energy from one electrical circuit to another through a magnetic field without a change in electrical frequency.

Impedance matching

A use of transformers in electronic control circuits to ensure maximum power transfer from a source to a load.

DC Isolation

The ability of a transformer to isolate direct current while permitting the flow of alternating current.

Gate pulse triggering

A specific application of transformers used in the field of power electronics.

Permeability ($\mu$)

The ability of a material to allow magnetic lines of force to pass through it or the ability of a material to create an internal magnetic field.

Free space permeability ($\mu_0$)

A constant value in magnetic circuits defined as $4\times 10^{-7}\,H/m$.

Magnetomotive force (MMF)

The force responsible for the motion of magnetic flux, calculated as $MMF = NI$, where $N$ is the number of turns and $I$ is the current.

Magnetic field intensity ($H$)

Defined as the Magnetomotive force (MMF) per unit length, or $H = \frac{NI}{l}$, where $l$ is the mean core length.

Magnetic flux density ($B$)

Defined by the relationship $B = \mu H$ or $B = \frac{\Phi}{A}$, and can be expressed as $B = \frac{\mu NI}{l}$.

Magnetic flux ($\Phi$)

The total magnetic field passing through a given area, calculated as $\Phi = B \cdot A$ or $\Phi = \frac{MMF}{\text{Reluctance}}$.

Reluctance

The opposition offered to magnetic flux by the magnetic circuit, mathematically defined as $\frac{l}{\mu A}$.