snubber.doc

Snubber Circuit 2008-12-08 09:56 缓冲电路（Snubber Circuit）又称为吸收电路。其中的电阻和电容分别称为缓冲电阻（snubber resistence）和缓冲电容（Snubber capacitance）。其作用是抑制电力电子器件的内因过电压、du/dt或者过电流di/dt,减小器件的开关损耗。缓冲电路可分为关断缓冲电路和开通缓冲电路。关断缓冲电路又称为du/dt抑制电路，用于吸收器件的关断过电压和换相过电压，抑制du/dt，减小关断损耗。开通缓冲电路又称为di/dt，用于抑制器件开通时的电流过冲和di/dt，减小器件的开通损耗。可将关断缓冲电路和开通缓冲电路结合在一起，称其为复合缓冲电路。还可以用另外的分类方法：缓冲电路中储能元件的能量如果消耗在其吸收电阻上，则称其为耗能式缓冲电路；如果缓冲电路能将其储能元件的能量回馈给负载或电源，则称其为馈能式缓冲电路，或称为无损吸收电路。 Snubber From Wikipedia, the free encyclopedia Electrical systems Snubbers are frequently used in electrical systems with an inductive load where the sudden interruption of current flow would lead to a sharp rise in voltage across the device creating the interruption. This sharp rise in voltage might lead to a transient or permanent failure of the controlling device. A spark is likely to be generated arcing and to cause electromagnetic interference. The snubber prevents this undesired voltage by conducting transient current around the device. [edit] RC snubbers RC snubbers A simple snubber comprising a small resistor R in series with a small capacitor C is often used. This combination can be used to suppress（抑制） the rapid（快速） rise in voltage across a thyristor, preventing the erroneous turn-on of the thyristor; it does this by limiting the rate of rise in voltage dV/dt across the thyristor to a value which will not trigger it. Snubbers are also often used to prevent arcing across the contacts of relays and switches and the electrical interference and welding/sticking of the contacts that can occur. An appropriately-designed RC snubber can be used with either dc or ac loads. This sort of snubber is commonly used with inductive loads such as electric motors. The voltage across a capacitor cannot change instantaneously, so a decreasing transient current will flow through it for a small fraction of a second, allowing the voltage across the switch to increase more slowly when the switch is opened. While the values can be optimised for the application, a 1