What's mean for high frequency transformer operate without loading

- Jul 05, 2018-

The high frequency transformer operates without loading

The no-load operation of the high frequency transformer refers to the working state of the primary winding of the high frequency transformer connected to the power source and the secondary winding open. At this point, the current in a winding is called the no-load current of the transformer. No-load current generates no-load magnetic field. Under the action of the main magnetic field (i.e. the magnetic field of the first and second windings), the electromotive force is induced in the first and second windings. Transformer no-load running, while the secondary side no power output, but the primary side is still part of the active power from the grid, to compensate for flux saturation, bow | within the core of magnetic hysteresis loss and eddy current loss or iron loss. The size of hysteresis loss depends on the frequency of power supply and the area of magnetic hysteresis loop of core material. The eddy current loss is proportional to the square of the maximum flux density and frequency. There is also copper loss caused by no-load current. For transformers of different capacity, the size of no-load current and no-load loss is different.

Circuit analysis:
: 1. The main magnetic flux leakage flux ɸ ɸ m s
2. Self-induced electromotive force e1 and es
3. Mutual inductance emf e2
4. I1 = i0i2 = 0 u1 = - e1u2 = u20 = e2

During no-load operation, the main magnetic field is generated by the original side current. When the rated voltage is added to the original side winding, the no-load voltage of the side winding is the rated voltage of the side winding.

No-load current:
It is mainly used to generate the main magnetic field, so it is also called excitation current. At the same time for the transformer loss, called no-load loss.
No-load loss:
When the transformer is idle, the original side absorbs a small amount of active power from the power source, which is used to supply iron loss and copper loss of the original side winding. Because the no-load current and the copper loss of the original side winding are small, the no-load loss is approximately equal to the iron loss.