Do you know how to solve the internal and external interference problems of switching power supply manufacturers?
Usually, it is divided into two categories, namely, the interference formed by the internal components of the switching power supply manufacturer. There is also the interference caused by the switching power supply manufacturers affected by external factors. Both of these involve human and natural factors.
First, the internal interference of switching power supply manufacturers
Switching power supply manufacturers say that the key to EMI is the high-order harmonic current interference caused by the basic ballast and the peak voltage interference caused by the output power conversion circuit.
1. There is a distributed capacitance between the switch tube and the heat pipe radiator and the leads inside the chassis and power supply. When the switch tube passes through a large pulse current, the waveform has many high-frequency components. At the same time, the main parameters of the components used in power-off applications, such as the storage time of the switching power tube, the large current of the output stage, and the reverse recovery time of the switching rectifier diode, will cause the control loop to be short-circuited instantaneously, resulting in a large short-circuit current. , The load of the switch tube is a high-frequency transformer or an inductor of energy storage technology. At the moment when the switch tube is turned on, a large inrush current occurs at the primary stage of the transformer, resulting in peak noise.
2. The transformer in the high-frequency transformer switching power supply is used as protection and transformer, but due to leakage inductance, it will cause electromagnetic induction noise. At the same time, in the case of high frequency, the distributed capacitance between the layers of the transformer will transmit the high-order harmonic noise on the multiple side to the secondary, and the distributed capacitance of the transformer to the chassis forms another high-frequency loop, which makes the transformer form another high-frequency loop. Magnetic fields caused by the surrounding are more likely to couple to other leads to form noise.
Second, the external interference of switching power supply manufacturers
The external interference of switching power supply manufacturers can exist in common mode or differential mode. The type of disturbance can vary from short-duration spike disturbances to complete power outages. At least voltage transitions, frequency transitions, waveform dropouts, constant noise or low frequency oscillations are included.
The key that can be transmitted according to the power supply and cause the destruction of the equipment or affect its work is the rapid electrical transient monopulse and surge shock wave, and the interference such as electrostatic discharge, if the power supply equipment itself does not cause problems such as vibration stoppage and output voltage drop, it will be It is not easy to cause the impact on the power-consuming equipment caused by the power supply.