When the AC power off, the bus is under pressure, the duty cycle increases to 98%, suddenly power on, can not over current protection, explosion, why can not flow protection?
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When the AC power off, the bus is under pressure, the duty cycle increases to 98%, suddenly power on, can not over current protection, explosion, why can not flow protection?
Hi John,
red: mosfet current
yellow:driver signal
t1-t2: turn off the AC grid,but ucc28180 still working(use the extra DC source),the bus cap voltage is reduce,so the D increase to the max,see the yellow signal.
t2-t3: suddenly,turn on the AC grid ,there will be a large spike current throuth the extra diode i draw and the Risense(because test the mosfet curren ,there is no spike current in the scope),so the chip check the over current and turn off the driver immediatly.
t4: the chip begin wave, two cycle,the current reach 15A.until the fifth cycle,turn off the driver(pic 3).