AC Power supply- electromagnetic interference

With the continuous development and maturity of Switching Power Supply technology, the demand for switching Power Supply in various application fields is also growing. Switching power supply has gradually replaced the market position of traditional linear power supply. Power is higher, while volume and weight are significantly reduced, providing more cost-effective options for many space constrained areas.

As we all know, switching power supply will bring electromagnetic interference, which will pollute the power grid and directly affect the normal operation of other equipment. As radiation interference, it will also cause electromagnetic pollution to the space. Therefore, the electromagnetic compatibility of power supply must be considered when purchasing power supply. Electromagnetic compatibility refers to the ability of equipment or system to work normally in its electromagnetic environment without any intolerable electromagnetic disturbance.

APM Programmable AC Power Supply series adopts active PFC circuit with power factor up to 0.99. With soft start and relay on timing control, it can effectively suppress the generation of surge current and reduce the amplitude of harmonic current. The input filter can suppress or remove electromagnetic interference and achieve the purpose of electromagnetic compatibility. Zero voltage / zero current conduction type is selected for the switching device, and the loop and parameter design are reasonable to avoid resonance. In the structural design, in addition to considering the air duct direction, and also fully considering the shielding requirements, reasonable PCB wiring and proper application of magnetic beads play an important role in the suppression of electromagnetic interference.

Understand the influence of electromagnetic interference on test through comparison:

The screenshot below is from an end user in China. Before purchasing APM programmable AC Power Supply, he chose other brands power supply. After the power supply is connected to the power grid, it will affect other electrical equipment in the power grid, resulting in high output ripple of DC Power Supply in the power grid, which cannot be tested normally (as shown in Figure 1 below). Even if the ground connection is removed, the AC DC Power Supply are separated to a far distance and connected through different air switches, the Line Disturbance still exists. (See Figure 2 below)

In the same test environment using APM technologies programmable AC power supply, Programmable DC Power Supply output pure and stable, no impact. APM technologies programmable AC power supply passes the strict EMC test level, and meets the requirements of class a of EU Electromagnetic Compatibility Directive 2014 / 30 / EU / en61326-1:2013 and FCC CFR 47 Part 15. It can meet the test occasions with higher requirements for electromagnetic compatibility.