A power module is a power converter that can be mounted directly on the printed circuit board. It is generally divided into AC to DC or DC to DC according to the conversion mode. With the development of science and technology, the volume of power supply tends to be modular and miniaturized, so the emergence of power module. Its highest degree of integration, the main circuit of switching power supply integrated in the chip, can achieve broadband modulation, isolation and a variety of protection and other functions.
The common rationale consists of the following parts, the input rectifier filter, including the rectifier bridge and the input filter capacitor. Monolithic switching power supply comprises power switching tube, controller and MOSFET. There are high frequency transformer, leakage level clamp protection circuit, optocoupler feedback circuit, output rectifier filter, bias circuit and other parts.
Through the input rectifier filter, the power module can generally adapt to the input voltage range of 85~265V AC or 100~370V DC. The frequency can be selected from 47~400Hz, and the general frequency is 50/60Hz. Because of its small size, high integration, high cost performance and the best performance index, only the most simple peripheral circuit, with a few discrete components can be used. It has the advantages of high efficiency, high reliability, flexible design and so on. It has become the preferred integrated circuit for the development and design of small and medium power switching power supply.
The power module selection scheme has low technical requirements, simple design, small space occupation, high reliability, and can be changed at any time. When the product design needs to be changed, just parallel or replace the power module. Therefore, it is widely used in industrial control, mechanical equipment, ships, aerospace, communications, military, data communication, handheld electronic products, instruments and meters, LED lighting, intelligent, electric power, railway, security, mining, medical, automotive electronics and other fields.
At present, it is almost difficult for a single power module to pass SURGE, EFT, CE, RE and other EMC experiments. Although foreign products have long life, high reliability and good EMI control, their anti-interference performance is still not strong enough. Most switching power supplies are certified by UL and 3C, and EMI performance is guaranteed. However, after modularization, they fail to pass EMI testing. In order to make the equipment pass EMC testing, peripheral circuit design is needed.
The best choice of power module is to choose the power used in 30-80% of the appropriate, generally within the power range of its performance to play stable and reliable. There are mainly commercial grade, industrial grade and military grade. Different grades have different requirements for operating temperature, vibration, humidity and so on. In order to ensure the long-term stable and reliable work of the product, the actual application environment should be considered when selecting the product.