OK, C11 once charged will supposedly discharge slowly thru L1 (Choke). The purpose of the L1 (choke) would be to act a surge suppressor for the transients so the 7812 doesn't burn up.
Yes This feedback loop as you stated is the major power loop for the OU system, right?
In my posts I use two phrases containing the word "loop" The "major power loop" consisting of L2, SB1, R3, C11, R1, L1, D5, C3, D6 in that order (with Q1 as a catalyst). The small signal "feedback loop" consisting of the "feedback takeoff point", R7, C15, pin 2 & pin 15, culminating in pin 3. So, as C11 charges up at the same time it would be discharging into the L1 (choke) to feed the 7812 to power the TL494.
Yes, I like to think about the VR1 as the origin of the auxiliary power supply. But until the system is free running, the input voltage/current must pass thru L1 (choke) from opposite side to charge C11
Yes, in other words it appears that the author had intended to charge the major energy tank (C11) from the external battery via L3 in the bootstrap mode and from L2 via D6 in the self-running mode. the then thru L1 Primary to the Drain of the MOSFET (when switching).
That is the major discharge path for C11. ...So C11 is held @ Vcc as a minimum voltage thru L1 (choke).
What is Vcc in your analysis? Voltage across C11 or C6 or C3 ? As stated C11 can charge to a higher voltage when L1 EMF (primary) and C3 voltage exceed Vcc.
IMO only D6 and L2 provide the recharge path for C11. I don't count the series LC tank formed by C11 & L1 during the power-up transient. My idea is this: What if a small boost/buck converter (1-3 amp variety) was substituted in place of the 7812 volt reg. When the voltage dipped below the set value, the boost converter would raise it, and when it went above, the buck would lower it.... This *could* give more leeway to the operation of the control circuitry to get it free running. Usually these small boost/bucks converters have decent efficiency ratings.
Yes, a buck/boost converter would be able to maintain the auxiliary voltage with wider input voltage range on C11 via L3.
« Last Edit: 2014-04-18, 16:33:30 by verpies »
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