1、DC switching power supply protection technology DC switching regulator used in high-power switching devices more expensive prices, the control circuit is more complicated, and, switching regulators are generally supported by the large number of highly integrated devices installed electronic systems.
2、 Transistors and integrated device, tolerance, the ability of poor thermal shock. Thus switching regulators should take into account the protection of their own regulator and load security. Many of the types of protection circuit here on polarity protection, procedural protection, over-current prote
3、ction, over-voltage protection, under-voltage protection and thermal protection circuits. Usually use several ways to protect the combination of a complete system of protection. DC switching regulator input are generally not regulated DC power supply. The operation will be mistakes or accidents to i
4、ts polarity wrong, will be damaged switching power supply. Polarity protection purpose, which is to enable switching regulator only when connected with the correct polarity of the DC power supply regulator, to work. Wizard of single-use devices can achieve power supply polarity protection. The most
5、simple polarity protection circuit as shown in Figure 1.The diode D to flow switching regulator of the input current, this circuit applications in low-power switching regulators to be more suitable. In the larger power of the occasion, put procedures polarity protection circuit as a link in the prot
6、ection, eliminating the polarity protection for high-power diodes, power will be reduced. In order to facilitate the operation, ease of identification polarity correct or not, in Figure 1 in the diode, then light. Switching power supply circuit complexity, basically can be divided into low-power and
7、 high-power control part of the switch. Is a high-power switching transistors, for the protection of switching transistors in the open or shutdown the safety of power, we must let modulator, such as a low-power amplifier control circuit. Accordingly, we must ensure that the correct procedures boot.
8、Switching Regulators general of the inputs to a small inductance, capacitance of the input filter. Boot in an instant, filter capacitor will flow through large inrush current, inrush current can be several times more than the normal input current. This large inrush current general will contact the p
9、ower switch or relay contacts melting, and the input fuse links. In addition, the inrush current will damage capacitors to shorten the life of premature damage. To this end, a boot should access the current limiting resistor, through the current limiting resistor capacitor to the charge. In order no
10、t to limit the flow resistance of the excessive consumption of power, which affects the normal switching regulator, in the boot after the end of the transient process, with a short then automatically relays it to DC power directly to the switching regulator electricity, as shown in Figure 2. This ci
11、rcuit switching regulator known that the soft-start circuit. Switching Regulators in the control circuit logic components or operational amplifiers required auxiliary power supply. To this end, auxiliary power switch must be in the circuit. This circuit can be controlled to ensure the boot. The proc
12、edure is generally boot: Identification of the polarity of the input power supply voltage protection circuit work boot auxiliary power supply and work through the current limiting resistor R of the switching regulators input capacitor C Switching Regulators charge modulation circuit, Short-circuit c
13、urrent limiting resistor Switching Regulators stability. In the switching regulator, to start the machine, because of its large output capacitor capacity, filling the needs of the rated output voltage of a certain period of time. During this time, the importation of low sampling amplifier output vol
14、tage sampling, in accordance with the closed-loop system of regulation will be forced to switch transistor on-time lengthened this way, the switching transistor during this period will become discontinuous conduction , and easy to damage. To this end,the boot this request within a certain period of
15、time, switch output modulation circuit switching transistor base to the drive pulse width modulation signal can be guaranteed by the deadline for switching transistor switching gradually become normal state, and therefore should be set up to cope with boot protection Soft Start. 直流开关稳压电源的保护技术 直流开关稳压
16、调节器通常用于高电压电源转换设备中，并且价钱十分昴贵，控制系统也是十分的复杂同时配电器系统需要配有大量电子装置的高集成度的设备来构成，晶体管，电容及它的热冲击能力也是十分重要的。对于直流开关稳压电源它的器件的稳定性 以及它的负荷能力，所以很多种形式的护电路应用在这里的极性保护，和序保护，过电保护，过压保护，低压保护，散热保护等，通常通过各种方法把这些保护电路和电路系统完好的结合起来！ 直流稳压电路的输入端通常情况下不是稳定的直流源一般而言把普通交流电接到输入端，这样的做如果不经转换装置直接接到需要直流的电路中通常会产生错误或对电路的极性产生损伤，将会损坏这个开关电源。极性保护电路的作用正是当在
17、这些情况下对电路进行保护使其正常工作的作用，使信号发生设备在此极性保护电路支持下正常工作。其中，为防止随开关启 -闭所发生的电压浪 涌，可采用 R-C 或 L-C 缓冲器，而对由二极管存储电荷所致的电流浪涌可采用非晶态等磁芯制成的磁缓冲器。不过，对 1MHz 以上的高频，要采用谐振电路，以使开关上的电压或通过开关的电流呈正弦波，这样既可减少开关损耗，同时也可控制浪涌的发生。这种开关方式称为谐振式开关。最简单的极性保护电路的主要工作器件是二极管，流过稳压电源的电流简单的通过二极管循环流动，然而这个简单的装置应用在简单的低压直流稳压电源中是比较合适的。更复杂一些的电源的极性保护电路在极性保护和滤波
18、等方面起着非常重要的作用，高压二极管就会比较适合。为了使 其更加简易保护高品质的二极管是非常重要的。 直流开关稳压电源的电路还是比较复杂的，在基本的开关稳压电路部分分为了低压电路部分和高压电路部分。一个高压开关转换晶体管在电路的开启和关闭的时候起到很大的作用，故我们需要使用类似于低压放大器电路的调节器 .所以我们需要弄清整个电路电流的流经途径。开关稳压装置通常在输入端滤波器前加入一个小的滤波电容，在输入端经常出现瞬间起峰电流，滤波电容的主要作用就是要滤除掉这些对电路产生不良影响的电流，一个较大的起峰电流可能会取代输入电流或者把继电器接触点熔化，瞬间起峰电流还可能使滤 波电容击穿，从而使电路短路把电路烧毁，因些我们还需要一个限流电阻器，这样电流就能得到有效的控制。为了避免限流电阻过度消耗能量对转换装置产生干扰，在保护程序中将自动很快的把流过限流电阻的电流直接转入到电路中 .
