Fuzzy logic protection circuit provides a flexible response in severe transient environments

A power supply input protection circuit has been developed using fuzzy logic technology to guard against severe transient environments. The protection circuit incorporates active inrush current limiting and provides a flexible response to bus voltages under 22.5 VDC or over 30.0 VDC. Active series limiting of overvoltage transients allows the use of smaller transient suppressors and provides automatic recovery following severe transients. A decision, based on system knowledge in the form of rules, is made to allow the power supply to continue operating or to shut down until the transient condition is removed. Test results are presented for a 1.5 kW power supply subjected to high- and low-energy transients