 Quick CG schematic sketch, up for criticism.
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TheMerovingian
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Registered Member #14
Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383
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Let me explain why it would not work:
One transistor has the emitter tied on ground (ground-referenced)
and one has the emitter tied on the coil "high-side". Since the load is the coil itself, It will see full capacitor voltage, so the "high side" will float to V0 (300-400V for example).
Since the emitter is connected to the high side the emitter itself will float to 300-400V. To drive an IGbt you need at leas 12V respect HIS emitter, this means 312-412V respect to system ground. That's why you need an isolated floating-emitter driver such as the Ir2181 (max 600V). You cannot drive it dyrectly or you will blow BOTH transistors. Assuming you would able to turn them on. After the current rises in the coil the top gate will see 12V-300V = -288V and his gate will blow, after the gate is shorted it will be connected the the high voltage side (300V) and will blow the bottom fet and the driving circuitry to pieces.
Search for Halfbridge drivers to see some circuit topologies
Cheers
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