IGBT Sense Emitter Current Testing Using the B1505A
应用文章
Insulated gate bipolar transistors (IGBTs) have become the key energy-saving devices for use in switching applications such as switching convertors and invertors. However, IGBTs used in circuits that drive inductive loads (such as induction motors or igniters) risk damage due to excessive currents caused by a motor jamming or a short in the igniter circuit.
To detect overcurrents and prevent damage, some IGBTs have a second emitter terminal known as a sense emitter. The ratio of sense emitter current to emitter current is very small (one part to several thousand or several tens of thousands). The sense emitter current is monitored using a shunt resistor; the voltage across the shunt resistor in-turn feeds into an overcurrent protection circuit. When the overcurrent detector circuit senses the voltage exceeding a specified limit, it turns off the IGBT (Figure 1).