Tweet
Just for academic discussion, here's my results showing current limiting and voltage scaling of 6.3VAC. My inrush simulation wasn't really supposed to be super accurate, I mostly wanted to show it working. The yellow trace is the unlimited heater current. The red trace is the unregulated 6.3VAC winding voltage, and the blue trace is the regulated output. Y scale is Amps or Volts, depending on the trace.
The regulator is essentially a hysteresis controlled buck converter, minus the catch diode. It uses a 100khz clock and SR flip-flop for time delay to keep the loop from collapsing. (Not a D - I think my D model isn't working correctly). The current limit is set to 5.65A, and the reference voltage is taken from the incoming AC, scaled by 0.9. If the output cap gets too big, it lags a bit at the zero crossings and looks funky. While there are inexpensive low pin count (and hence parts count) controllers, the bulk of the circuitry is in rectifying the control signals, which no off the shelf controller is likely to do.
The regulator is essentially a hysteresis controlled buck converter, minus the catch diode. It uses a 100khz clock and SR flip-flop for time delay to keep the loop from collapsing. (Not a D - I think my D model isn't working correctly). The current limit is set to 5.65A, and the reference voltage is taken from the incoming AC, scaled by 0.9. If the output cap gets too big, it lags a bit at the zero crossings and looks funky. While there are inexpensive low pin count (and hence parts count) controllers, the bulk of the circuitry is in rectifying the control signals, which no off the shelf controller is likely to do.
Comment