High frequency transformer is a device that operates based on the principle of electromagnetic induction, mainly used to transform voltage, current, and impedance in high-frequency circuits. The following is a detailed analysis of its electromagnetic induction mechanism and working principle:

1、 Electromagnetic induction mechanism

Electromagnetic induction is the fundamental principle of high-frequency transformer operation. According to Faraday's law of electromagnetic induction, when the magnetic flux passing through a closed conductor circuit changes, an induced electromotive force is generated in the circuit. In high-frequency transformers, this principle is achieved through the following methods:

Magnetic field generation: When an alternating voltage is applied to the primary winding (also known as the primary coil) of a high-frequency transformer, an alternating current is generated. This alternating current generates alternating magnetic flux in the magnetic core, which constantly changes over time.

Induced electromotive force generation: alternating magnetic flux passes through both the primary winding and the secondary winding (also known as the secondary coil) simultaneously. According to the law of electromagnetic induction, the primary winding generates self induced electromotive force, while the secondary winding generates mutual induced electromotive force. The magnitude of this mutual inductance electromotive force is directly proportional to the number of turns in the winding and the rate of change in magnetic flux.

2、 Working principle

The working principle of high-frequency transformers can be summarized into three stages: energy storage, energy transfer, and feedback and regulation (if there is a feedback winding):

Energy storage: On the primary side of the high-frequency transformer, the input high-frequency AC power passes through the primary winding. According to Ampere's Law, current generates a magnetic field around a wire. Due to the alternating current, the magnetic field also changes alternately with time. The magnetic core plays a role in guiding and enhancing the magnetic field here. It has high magnetic permeability, which can concentrate the majority of the magnetic field inside the core, greatly improving the magnetic field strength and coupling efficiency.

Energy transfer: The changing magnetic field is coupled to the secondary winding through the magnetic core. According to Faraday's law of electromagnetic induction, changes in magnetic flux in the secondary winding will induce an electromotive force. If the secondary winding is connected to a load, current will flow through the load, thereby achieving the transfer of electrical energy from the primary circuit to the secondary circuit. In this process, the turns ratio of the coil determines the ratio of the input voltage to the output voltage.

Feedback and regulation: Some high-frequency transformers are equipped with feedback windings to monitor output voltage or current and provide feedback to the power control circuit. When the output changes, the signal generated by the feedback winding changes accordingly, and the control circuit adjusts the input of the primary winding accordingly to ensure stable output.

3、 Characteristics of high-frequency transformers

Compared with low-frequency transformers, high-frequency transformers have the following characteristics:

High operating frequency: The operating frequency of high-frequency transformers is usually between tens of kHz and several MHz, while the operating frequency of low-frequency transformers is generally 50Hz or 60Hz. A higher operating frequency enables high-frequency transformers to have faster changes in magnetic flux in the magnetic core at the same power, allowing for energy conversion using smaller magnetic cores and fewer turns of windings, thereby reducing the volume and weight of the transformer.

Special magnetic core material: High frequency transformers require the use of materials with low hysteresis loss and low eddy current loss as the magnetic core, such as ferrite magnetic cores. These materials have high electrical resistivity and can reduce eddy current losses. Low frequency transformers commonly use silicon steel sheets as magnetic core materials, which have good magnetic properties and low cost at low frequencies.

The winding design is complex: at high frequencies, the winding exhibits skin effect and proximity effect, causing current to concentrate on the surface of the conductor, increasing winding resistance and losses. Therefore, high-frequency transformer windings often use multiple thin wires wound together or with Leeds wires to increase the effective cross-sectional area of the wires and reduce losses. The winding design of low-frequency transformers is relatively simple.

In summary, high-frequency transformers achieve energy storage, transmission, and regulation through the principle of electromagnetic induction. Its working principle is based on fundamental electromagnetic principles such as Faraday's law of electromagnetic induction and Ampere's law. In high-frequency circuits, high-frequency transformers have the advantages of small size, light weight, high efficiency, and stable performance, and are widely used in devices such as switching power supplies and electronic ballasts.