Andorra 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 48V input 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 48V input 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 48V input power supply. Such as power carrier, wireless communication, wireless identification, etc. The 48V input power supply requirements for power carrier applications are as follows.

HVDC module power supply
High-power switching high-voltage DC power supplies are widely used in large-scale equipment such as electrostatic dust removal, water quality improvement, medical X-ray machines and CT machines. The voltage is as high as 50~159kV, the current reaches more than 0.5A, and the power can reach 100kW.
Since the 1970s, some Japanese companies have begun to use inverter technology to rectify the mains and invert it to an intermediate frequency of about 3kHz, and then boost it. In the 1980s, high-frequency switching power supply technology developed rapidly. Siemens of Germany uses power transistors as the main switching elements to increase the switching frequency of the power supply to above 20kHz. And the dry-type transformer technology is successfully applied to the high-frequency high-voltage power supply, the high-voltage transformer oil tank is cancelled, and the volume of the transformer system is further reduced.

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 48V input power supply.