Reasons for the burnout of military power modules

The working process of the power module is very special. The working sequence and voltage increase are divided into 3 stages. Stage 1 is the rectification of 380V AC to 400VDC, stage 2 is to continue to charge the DC-LINK capacitor to 570VDC after 400VDC is detected, and stage 3 is to wait for the pulse to make The power signal appears, and the DC-LINK voltage is raised to 600VDC. Since the start, drive enable, and pulse enable signals are provided at the same time, the above three-step interval is extremely short. The IGBT rectifier bridge starts to work as soon as the enable conditions are met. When the IGBT rectifier bridge and pulse distribution circuit are unstable, humid, and When a large current breakdown or pulse disorder occurs due to dust accumulation and other reasons, the surge current impacts the IGBT DC side of the coordinate axis power module through the DC bus bar, which is the root cause of the short circuit and burnt of the power module. When the IGBT rectifier bridge is short-circuited, the incoming line reactor should have a certain protective effect to prevent the current from rising too fast. The decrease in insulation capacity will cause the inductance to decrease sharply, which cannot effectively protect it. This is also the second time that the power module is burned. The main reason.

The normal voltage supply range in my country is: 380 (1-15%) V--380 (1+10%) V alternating current. The voltage requirement of Siemens power module: 380±5 V AC. When the power supply exceeds the voltage required by Siemens, the self-protection function (fuse) of the power module will be lost, and the fuse and three associated electrical components will be broken down at the same time, resulting in the power module burn.

The power module is a power supply that can be directly mounted on a printed circuit board. Its characteristics are that it can be an application-specific integrated circuit (ASIC), digital signal processor (DSP), microprocessor, memory, field programmable gate array (FPGA) ) And other digital or analog loads to provide power. Generally speaking, this type of module is called a point-of-load (POL) power supply system or a point-of-use power supply system (PUPS). Due to the many advantages of the modular structure, the modular power supply is widely used in switching equipment, access equipment, mobile communications, microwave communications, optical transmission, routers and other communications fields, as well as automotive electronics, aerospace, and so on.