1、恒流行:电流恒定不变,电压下降
2、回卷型:初始电流恒定不变,电压下降到一定数值电流开始减小.
3、限功率型:限定输出的总功率
4、打隔型:过流后,电流电压下降到0,然后又开始上升,周而复始.
5:复合型:将多种保护符合起来.
我所知道的就这些,希望大家讨论各种方式以及实现的方法和使用的场合.
过流保护的几种方式
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@shandongtao
恒压式比较好!在有负载时
我看到这样一个资料,其中关于电流限制这方面的电路没有弄清楚.
Key Design Notes
• The constant voltage (CV) mode control is implemented with resistors, R8, R9, R10 and R11, shunt regulator, U2, feedback
capacitor, C9 and opto-coupler, U3.
• The constant current (CC) mode control is designed with resistors, R8, R9, R15, R16, R17 and R19, NPN transistor, Q1 and
NTC, TH1. When the voltage across current sensing resistors, R15,R16 and R17 is 0.7V, the NPN transistor turns on and the
current through the opto coupler LED increases. This reduces the feedback voltage and duty ratio. Therefore, the output
voltage decreases and the output current is regulated.
• The NTC(negative thermal coefficient) is used to compensate the temperature characteristics of the transistor Q1.
它是如何来控制电流的呢
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Key Design Notes
• The constant voltage (CV) mode control is implemented with resistors, R8, R9, R10 and R11, shunt regulator, U2, feedback
capacitor, C9 and opto-coupler, U3.
• The constant current (CC) mode control is designed with resistors, R8, R9, R15, R16, R17 and R19, NPN transistor, Q1 and
NTC, TH1. When the voltage across current sensing resistors, R15,R16 and R17 is 0.7V, the NPN transistor turns on and the
current through the opto coupler LED increases. This reduces the feedback voltage and duty ratio. Therefore, the output
voltage decreases and the output current is regulated.
• The NTC(negative thermal coefficient) is used to compensate the temperature characteristics of the transistor Q1.
它是如何来控制电流的呢
500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/26/1107398247.gif');}" onmousewheel="return imgzoom(this);"> 0
@jiurl
基极的电压是否通过NTC(TH1)电阻反馈得到的?Q1没有导通就是说基极的电压没有达到0.7V,R15~17流过的电流不够大,是吗,那么这个电流回路是在那里呢.呵呵,还是有些不太明白.
看看图P
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500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/26/1107409994.gif');}" onmousewheel="return imgzoom(this);"> 0
@jiurl
基极的电压是否通过NTC(TH1)电阻反馈得到的?Q1没有导通就是说基极的电压没有达到0.7V,R15~17流过的电流不够大,是吗,那么这个电流回路是在那里呢.呵呵,还是有些不太明白.
回路是这样的:
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500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/26/1107425050.jpg');}" onmousewheel="return imgzoom(this);"> 0
