Definition and Classification of High Frequency Transformer

 

What is a high frequency electronic transformer? In fact, the definition of high-frequency electronic transformers is very clear. In order to show the true nature of high-frequency electronic transformers, it is necessary to clarify the concepts of transformers, electronic transformers, and high-frequency electronic transformers in order to eliminate misunderstandings.

 

First of all, we have to figure out what a transformer is. A transformer that works on the principle of electromagnetic induction means that an alternating voltage is applied to the primary winding of the coil, and an output voltage is induced in the secondary winding, so as to transmit energy, transform voltage (or signal), and electrically isolate.

 

To produce electromagnetic induction, the primary winding must be applied with alternating voltage. The kind that uses DC voltage as a working power source is an inverter that converts DC to AC.

 

As long as there is electromagnetic induction, the transformer can work. The magnetic core is not necessary. For example, an electronic transformer with an operating frequency of MHz is an air-core transformer made from a printed circuit board. The statement that high-frequency electronic transformers are "magnetic transformers used in circuits with frequency conversion" is a double misunderstanding of not only including the frequency conversion circuit in the scope of the transformer, but also thinking that the transformer must have a magnetic core.

 

The transformer transmits energy through electromagnetic induction regardless of the operating frequency. The size of the transmitted energy is related to the material, structure, size and operating frequency of the transformer. If the transmitted energy is a fixed value, the operating frequency is high, and the number of energy transmissions within a certain period of time is large, and the energy transmitted each time can be small, the transformer uses less materials and has a small structure. It is a misunderstanding that the transformer transmission energy is limited and high frequency is used to increase the transmission energy. Using pulse width modulation (PWM) to change the power and voltage of the transformer is just an additional control method. Not only high-frequency transformers can be used, but low-frequency transformers can also be used. It is also a misunderstanding that there is a difference in the way that high-frequency transformers and low-frequency transformers transmit energy after PWM control, and the ways in which high-frequency transformers and low-frequency transformers change voltage are different.

 

Next, we have to figure out what is an electronic transformer? Electronic transformers are transformers used in electronic circuits and electronic equipment. If the scope is expanded, it includes all electromagnetic components such as transformers, inductors, and transformers used in electronic circuits and electronic equipment. Electronics is not limited to power electronics, but also includes industrial electronics, information electronics, wireless electronics and microelectronics. Although electronic transformers are different from power transformers, they are not different from RF signal transformers, nor are they limited to "power in switching power converter circuits." transformer". Power transformer is just one kind of electronic transformer. Therefore, it is a misunderstanding to limit electronics to power electronics and to limit electronic transformers to power transformers.

 

Then, we have to figure out what a high-frequency electronic transformer is. Nowadays, there is a common saying about the high, medium and low division of the working frequency of electronic transformers, that is, the working frequency of 50Hz or 60Hz is called the power frequency, or the lower frequency is called the low frequency; 60Hz to 20kHz is called the intermediate frequency, and 400Hz is the intermediate frequency, not Power frequency; above 20kHz is called high frequency. Why choose 20kHz as the limit? Because 20kHz is the upper limit of the audio frequency, no audible noise will be heard if it exceeds it. Therefore, the operating frequency exceeds 20kHz, from 20kHz to MHz level, GHz level is high frequency.

 

High frequency can also be divided into higher frequency (20kHz～50kHz), medium and high frequency (50kHz～200kHz), high frequency (200kHz～1MHz), ultra high frequency (above 1MHz), but they are all high frequency, not because of application The power is different, and there is a different understanding of high frequency. It is a misunderstanding that there are different ranges of high frequencies under different powers.