Principle Of Constant Voltage Transformer

There is a "日"-shaped iron core in Constant Voltage Transformer(CVT), the primary coil is in one window hole, and the secondary coil and the resonant coil are in another window hole. The resonant coil is connected to a resonant circuit with a capacitor whose resonant frequency is close to the power supply frequency.

When the primary power supply is turned on, the resonant circuit starts to vibrate, making the secondary iron core shallowly saturated, forming a constant alternating magnetic field. Its magnetic induction intensity is within a certain range and is basically not affected by the change of input voltage, so the induced electromotive force of the secondary coil remains unchanged. In this case, the primary input current only plays the role of replenishing energy.

The output voltage of the constant voltage transformer is only related to the magnetic performance parameters and cross-sectional area of ​​the iron core, and has nothing to do with the ratio of primary to secondary turns.

The efficiency, volume and weight of the constant voltage transformer are similar to those of ordinary transformers. When the iron core material is better, the output voltage changes less than 1.5[%] when the mains voltage changes from 160-250 volts; when the load current changes from full load to half, the output voltage changes by about 1.5-4[%], and when the output is short-circuited, the output current rises by about 1 times, so it is not afraid of long-term short circuit.