The Difference Between Power Frequency Transformers and High-Frequency Transformers

Power frequency transformers are also called low-frequency transformers to distinguish them from the high-frequency transformers used in switch-mode power supplies. Power frequency transformers were extensively used in traditional power supplies. Since the voltage regulation in these traditional power supplies was achieved through linear regulation, they are also known as linear power supplies. The power frequency generally refers to the mains frequency, which is 50Hz in China and 60Hz in some other countries. Transformers that can change the voltage of AC power at this frequency are called power frequency transformers.

High-frequency transformers are power transformers operating at frequencies above the mid-frequency range (10kHz). They are primarily used in high-frequency switch-mode power supplies as the main transformer, and also in high-frequency inverter power supplies and high-frequency inverter welding machines. The main advantages of high-frequency transformers are also reflected in the following two points:

1. Improved Conversion Efficiency: Power supplies using high-frequency transformers operate with their power transistors switching instantly between the ON and OFF states – a continuous switching cycle. Hence, they are called "switch-mode power supplies." They achieve approximately 30% lower losses compared to traditional iron-core transformers.

2. Ability to Transform High-Frequency Pulses: The iron core of an ordinary transformer does not have the high permeability of ferrite cores used in high-frequency transformers and cannot achieve this.

High-frequency transformers are also used in everyday appliances like radios, televisions, microwave ovens, and especially in switch-mode power supplies. Power frequency transformers are widely used in scenarios where there is no requirement to change the mains frequency. High-frequency transformers are applied in situations where the electrical signal frequency needs to be increased. Therefore, the operating frequency of a transformer depends on the frequency requirements of the electrical device it powers. Consequently, when selecting a transformer, it is crucial to pay attention to its frequency rating. Using a transformer that does not meet the frequency requirements of the device can easily cause abnormal operation, overheating, or even burnout of the equipment.