Why can't power transformers change frequency?

Power transformers can be transformed, and the improved voltage is more suitable for production and life needs. Many people may want to know whether power transformers can be frequency-converted, that is to say, the frequency of transformers. The answer is no. Let's go to understand together. Let's look at the reason why the frequency can't be changed.

Transformers are manufactured based on the principle of electromagnetic induction. The core of electromagnetic induction is the change of magnetic flux in the closed loop to generate voltage. The magnetic flux is transmitted in a closed iron core, so the rate of change is the same, that is, the frequency on both sides is the same. However, because the number of turns of the coils on both sides is different, the voltage changes, that is, the voltage transformation is realized.

The structure of the frequency converter is generally to first convert the alternating current into direct current through an uncontrollable rectifier circuit and add it to the capacitor, and then realize the frequency conversion through the switch of the power electronic device. Therefore, the inverter is a switching power supply, but the output voltage waveform is not a standard sine wave, but a PWM wave, but the corresponding current waveform is close to a sine wave. At present, SVPWM technology is mostly used for the control of power electronic devices. Of course, the inverter will also change the voltage when the frequency is changed, the purpose is to keep the magnetic flux of the motor at a constant value. The typical change is that when the frequency is lower than 50HZ, the voltage is reduced and constant torque control is used; when the frequency is higher than 50HZ, the voltage is the rated voltage of the motor and does not rise with it, and constant power control is used.

By understanding the power transformer and the frequency converter, it is found that their structures are completely different. The transformer is a closed iron core, and the rate of change is the same, which cannot achieve the purpose of frequency conversion.