E币每日电源有奖问答（2.1）
回答每题奖10e币（根据回答酌情奖励）
1.什么是涌浪电流(Inrush Current)?
2.合闸浪涌电流的起因，限制方法?
答：1.交换式电源供应器在输入电源送电的瞬间会出现一短暂(1/2~1电源周期，EX:60Hz电源1/120~1/60秒)的大电流(依产品设计约为20~60A，请参考产品规格书)，产品开机之后便恢复正常电流输入，每次都在电源输入端送电的瞬间才会出现，此为正常现象，并不会造成电源供应器的损坏。但不建议持续对电源供应器开机/关机。
2.起因：电容输入式整流滤波电路在接通交流电压时，合闸时往往引起较大的浪涌电流：（1）滤波电压纹波越小，输入滤波电容越大。（2）直流从电网输入，电压高。
措施：在输入整流回路内串入限流电阻R。
1.浪涌电流指电源接通瞬间，流入电源设备的峰值电流。由于输入滤波电容迅速充电，所以该峰值电流远远大于稳态输入电流。
2（1）.当某些大容量的电气设备接通或断开时，由于电网中存在电感，将在电网产生“浪涌电压”，从而引发浪涌电流。
（2）.电源应该限制AC开关、整流桥、保险丝、EMI滤波器件能承受的浪涌水平。
浪涌电流指电源接通瞬间，流入电源设备的峰值电流。由于输入滤波电容迅速充电，所以该峰值电流远远大于稳态输入电流。电源应该限制AC开关、整流桥、保险丝、EMI滤波器件能承受的浪涌水平。反复开关环路，AC输入电压不应损坏电源或者导致保险丝烧断。浪涌电流是指电网中出现的短时间象“浪”一样的高电压引起的大电流。当某些大容量的电气设备接通或断开时，由于电网中存在电感，将在电网产生“浪涌电压”，从而引发浪涌电流。 一般不管设备容量大小，都会存在浪涌电压，问题是小容量的设备产生的浪涌电压较小，不会产生多大的危害，因此常常被人们所忽略。 在脱线变换器启动期间，因对大容量电容器充电会产生一个大电流。这个大电流比系统正常电流大几倍乃至几十倍(即所谓浪涌电流)，而这可能使AC线路的电压降落，从而影响连接在同一AC线路上的所有设备的运行，有时会烧断保险丝和整流二极管等元件。
1、浪涌电流是指电网中出现的短时间象“浪”一样的高电压引起的大电流，是注入电源设备的峰值电流。
2、由于输入滤波电容迅速充电，所以该峰值电流远远大于稳态输入电流，形成浪涌电流。加入热敏电阻，可以限制浪涌电流
1."Inrush current, input surge current or switch-on surge" refers to the maximum, instantaneous input current drawn by an electrical device when first turned on.
2. A resistor in series with the line can be used to limit the current charging input capacitors. However, this approach is not very efficient, especially in high power devices, since the resistor will have a voltage drop and dissipate some power.
Inrush current can also be reduced by inrush current limiters. Negative temperature coefficient (NTC) thermistors are commonly used in switching power supplies, motor drives and audio equipment to prevent damage caused by inrush current. A thermistor is a thermally-sensitive resistor with a resistance that changes significantly and predictably as a result of temperature changes. The resistance of an NTC thermistor decreases as its temperature increases[1] .
As the inrush current limiter self-heats, the current begins to flow through it and warm it. Its resistance begins to drop and a relatively small current flow charges the input capacitors. After the capacitors in the power supply become charged, the self heated inrush current limiter offers little resistance in the circuit, with a low voltage drop with respect to the total voltage drop of the circuit. A disadvantage is that immediately after the device is switched off, the NTC resistor is still hot and has a low resistance. It cannot limit the inrush current unless it cools for more than 1 minute to get a higher resistance. Another disadvantage is that the NTC thermistor is not short circuit proof.
Another way to avoid the transformer inrush current is a "transformer switching relay". This does not need time for cool down. It can deal also with power line half-wave voltage-dips and is short circuit proof. This technique is Important for IEC 61000-4-11 tests.
Another option, particularly for high voltage circuits, is to use a pre-charge circuit. The circuit would support a current limited precharge mode during the charging of capacitors, and then switch to an unlimited mode for normal operation when the voltage on the load is 90% of full charge.
1.浪涌电流指电源接通瞬间，流入电源设备的峰值电流。也可以说是整流二极管在非常短促的时间内所能安全承受 的最大电流值。过电流的主要危险在于二极管出现缓慢过热现象。
2.开关电源的输入电路大都采用电容滤波型整流电路，在进线电源合闸瞬间，由于电容器上的初始电压为零，电容器充电瞬间会形成很大的浪涌电流，特别是大功率开关电源，采用容量较大的滤波电容器，使浪涌电流达100A以上。在电源接通瞬间如此大的浪涌电流，重者往往会导致输入熔断器烧断或合闸开关的触点烧坏，整流桥过流损坏;轻者也会使空气开关合不上闸。上述现象均会造成开关电源无法正常工作，为此几乎所有的开关电源都设置了防止流涌电流的软启动电路。
1.指电源接通浪涌电流瞬间，流入电源设备的峰值电流。也就是指二极管在非常短促的时间内所能安全承受的大电流值。称之为浪涌电流。
2.电源的输入电路大都采用电容滤波型整流电路，在进线电源合闸瞬间，由于电容器上的初始电压为零，电容器充电瞬间会形成很大的浪涌电流，特别是大功率开关电源，采用容量较大的滤波电容器，使浪涌电流达100A以上。在电源接通瞬间如此大的浪涌电流，重者往往会导致输入熔断器烧断或合闸开关的触点烧坏，整流桥过流损坏;轻者也会使空气开关合不上闸。上述现象均会造成开关电源无法正常工作，为此几乎所有的开关电源都设置了防止流涌电流的软启动电路，以保证二手机器人电源正常而可靠运行。
哈哈，牛