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Selection of dcdc power supply module in power industry

Edit:Nanjing Fulaixiang Electronics Co., Ltd.UpDate:2018-06-28

dcdc module power supplyMore and more applications are used in communications, industrial automation, power control, rail transit, mining, military industry and other industries. The modular design can effectively simplify the customer's circuit design and improve the reliability and maintenance efficiency of the system. At the same time, due to the different characteristics of sub-industries, their requirements are naturally different. This article mainly introduces the selection of power supply modules in the power industry.


Due to the complexity of the power grid, the power industry also has diverse requirements for dcdc power supplies. The following briefly introduces several key selection points:


2.1 Low no-load power consumption


Some monitoring equipment in the electric power industry only operates when abnormal and requires high power, and is in a standby state for a long time during normal operation, such as FTU and anti-shake modules. Most of these systems use batteries as a backup power source. If the no-load power consumption of the dcdc module is too high, it will cause problems such as short battery life and premature damage. For example, in a certain anti-shake module project, when the power grid loses voltage, the power module needs to provide about 20W of power to power the relay within 1.5 seconds, but most of the time, the relay does not operate and the system is close to no load. At this time, the energy of the battery is consumed by dcdc, and the greater the no-load power consumption of the power supply, the shorter the battery life. In order to extend the battery life, the no-load power consumption of the power supply must not be higher than 0.3W, and the no-load power consumption of the 20W power supply on the market is generally about 0.5W-1.5W.

2.2 High efficiency in full load range


As mentioned above, many devices in the power industry are under light load or even no-load conditions for a long time, so achieving high efficiency in the full load range is of great significance to the reliability of the power supply system, but this is often ignored by most power supply manufacturers. In order to make the technical parameters more attractive, many manufacturers often achieve high full load efficiency, but the efficiency is low under light load conditions of 5%-50%, which will cause the actual working temperature of the power module to rise higher, resulting in A series of thermal design issues. In fact, for the power supply system, the full range of high efficiency means lower power loss and temperature rise, which can effectively improve the system reliability. Therefore, when selecting the power supply, special attention should be paid to its corresponding efficiency under no-load and light-load conditions. curve.


2.3 High isolation voltage, low isolation capacitance


Generally, the isolation voltage of the dcdc power module in the industrial control industry only needs 1500VDC, but the control system in the power industry generally chooses a power module with a withstand voltage of 3000VDC and above to ensure that the control system is not affected by the outside world.


In the case of power electronic products, it is also necessary to pay attention to minimize the parasitic capacitance between the primary side and the secondary side, that is, it is required to select a power module with as low isolation capacitance as possible to reduce the impact of common mode interference on the system. Generally speaking, the 1-2W unregulated open-loop dcdc powered by the driver is recommended to select an isolation capacitor lower than 10pF, while for the closed-loop design of dcdc, try to select an isolation capacitor lower than 150pF.


2.4 EMC characteristics


EMC performance is the guarantee for the normal and safe operation of electronic systems. At present, the electronic industry has put forward high requirements on the EMC performance of products. Due to poor EMC processing, the system resets and restarts or even fails early, so the excellent EMC characteristics can be improved The competitiveness of power products.


2.5 Limit temperature characteristics


The power industry products are applied in a very wide geographical area, from the scorching heat of Hainan in the tropics to the severe cold of winter in the northeast, and most of the products are in outdoor environments. Therefore, the operating temperature range of the dcdc module power supply is required to be at least -40°C~+85°C.


The extreme temperature test is a method to test the reliability of the power module, such as high temperature aging, high temperature& low temperature live performance test, high and low temperature cycle impact test and long time high temperature and high humidity test. Formal power supply development will go through the above tests. Doing these reliability tests can provide an important reference for selection.


The selection of dcdc power modules needs to be selected according to the special characteristics of the power industry. For example, the overall power needs to be more energy-efficient and efficient, then power module products with high efficiency and low no-load power consumption are required; products need to consider the system under various EMC interference environments The stability of work requires a power supply module with excellent EMC performance. And so on, at the same time, the power module is only a kind of functional integration, and more need to consider the system application design from the system system level to improve the reliability of the power system.