What is Impedance Conversion in a Transformer?

The ratio of the primary impedance to the secondary impedance of the transformer is equal to the square of the ratio of the number of turns on the primary side to the number of turns on the secondary side.

1. Analyze the no-load circuit on the primary side and draw the equivalent circuit on the no-load side.

2. Load on the secondary side.

The circuit is analyzed and the equivalent circuit on the secondary side is drawn.

3. Pass.

The electromagnetic induction between the primary and secondary sides is analyzed, and the impedance of the secondary side is converted to the primary side.

4. Draw the total primary side equivalent circuit including the original no-load primary side and the converted secondary side.

5. Vector analysis is usually used.

It is hypothesized that the ratio of turns of the primary and secondary of the transformer is n:1, and according to the characteristics of the transformer, the secondary voltage is 1 n of the primary and the current is n times that of the primary.

Primary impedance = primary voltage and primary current.

Secondary impedance = secondary voltage Secondary current = (1 n) primary voltage (n primary current) = [1 (nn)] primary impedance. Or that the primary impedance = (nn) secondary impedance.

This shows that the impedance of each coil of the transformer is proportional to the square of the number of coil turns. Taking advantage of this feature, the impedance can be converted by using coils of different turns of the transformer. The simplest, is the TV antenna, the impedance is 300 when using the flat feeder, the antenna input of the TV is 75, and an impedance conversion socket must be used, which is a ferrite core of 2:

1 transformer, 300 and 75 are impedance matched.

Impedance conversion: When the load impedance and the characteristic impedance of the transmission line are not equal, or when two transmission lines with different characteristic impedances are connected, the impedance matching can be achieved with the impedance adjuster above.

As long as one or more transmission line segments are inserted between two transmission lines that need to be matched, the conversion between different impedances can be completed to obtain a good match, so it is called an impedance converter.

Generally, the impedance of piezoelectric sensors is very high, and the input impedance of the signal amplification processing part is mostly very low (except for insulated grid MOSFETs). The impedance converter is used to convert the high impedance of the piezoelectric sensor into the low impedance required for signal amplification processing.

Transformer impedance refers to the impedance of the windings of the coil in the transformer, including resistance, inductive reactance, and capacitive reactance.

The standards for transformers have clear provisions on impedance and loss. After some users increase or decrease the impedance voltage, the loss is still unreasonable according to the standard requirements. If the impedance voltage becomes smaller, a reasonable change is:

If the no-load loss is good, the surplus becomes larger, and the load loss becomes smaller; If the impedance voltage becomes larger, the reasonable change is: the no-load loss becomes smaller, and the load loss becomes larger.

The standard value of the impedance voltage of the transformer (now called "short-circuit impedance" in the standard) is expressed as the percentage of defects (standard unit value). The standard values of different transformers are clearly specified in the national standards for transformers.

However, errors can occur during transformer manufacturing. The margin of error is: between + to (previously +-10%).

If the transformer is short, the standard value of the circuit impedance is 4%, and the transformer impedance range should be qualified according to the previous 10%. And to put this data on the transformer nameplate. <>