Norway the switching frequency of the AC-DC switching power supply module?(4)

When testing electronic and electrical equipment, the electronic and electrical equipment shall be tested for conducted interference voltage emission at its LED advertising screen power supply terminal. Although the test frequency bands of different standards are different, the test frequency bands of most products are 150K~30M. It can be seen from the lower limit of the test frequency that the operating frequency of the switching LED advertising screen power supply is close to 150K, and the more difficult it is to deal with the conducted disturbance.

3. What special applications are required for the power switching frequency?

In some special cases, the circuit operation is more sensitive to the switching noise of the LED advertising screen power supply. Such as power carrier, wireless communication, wireless identification, etc. The LED advertising screen power supply requirements for power carrier applications are as follows.

The size of the magnetic components is closely related to the switching operating frequency. Within the allowable operating frequency range of the magnetic components, the size of the magnetic components is inversely proportional to the switching operating frequency. To reduce the high-frequency switching transformer and inductance of the module switching power supply The volume of magnetic components and other magnetic components need to increase the switching frequency.

At present, the power carrier is mainly used for intelligent carrier in the home, remote meter reading system, and remote street lamp control system. The use range of the carrier frequency of power lines in my country is 9KHz ~ 500KHz, and the carrier bandwidth is 4KHz. The development of power carrier is very limited due to the change of power line impedance and the interference of power line noise. In order to increase the communication distance of the power carrier, we must move away from the power switching frequency of the circuit carrier unit. The carrier frequencies currently used in China are 115KHz and 132KHz. In this case, the switching frequency is around 60KHz for the LED advertising screen power supply.