Abstract: A circuit for shutting down an inverter that includes at least a series combination of first and second gate controlled rectifiers and a load. The circuit is comprised of means for sensing the direction and magnitude of the instantaneous current flowing through the load, and means responsive to the direction and magnitude of the sensed current for generating an output signal when the magnitude of the current exceeds a predetermined threshold level and the current is flowing in a first direction. The circuit further comprises means responsive to the simultaneous receiving of a shutdown signal and the generated output signal for further generating a gating pulse to be applied to the second gate controlled rectifier to cause the current flowing through the load to quickly extinguish. Further included is means responsive to the shutdown signal for inhibiting further regular gating of the gate controlled rectifiers to ensure quick turn off of the inverter.

Abstract: A circuit disposed between a power supply and a load for detecting the flow of an excess of power from the load back through the supply. The circuit is comprised of means for sensing the instantaneous current flowing between the power supply and the load, and means for sensing the instantaneous output voltage from the power supply. The circuit is further comprised of means responsive to the sensed instantaneous voltage and current for generating a signal that is indicative of instantaneous power flowing between the power supply and the load. Means is also provided for filtering out those components of the signal indicative of the instantaneous power which are at a frequency higher than the frequency of the AC current flowing between the power supply and the load to obtain a signal having a magnitude indicative of the average power flowing therebetween.

Abstract: A circuit for preventing overdischarge of a rechargeable lead acid storage battery. The circuit is comprised of means for sensing the rate of discharge of the battery, means for generating a safe final discharge voltage which varies inversely with the sensed rate of discharge of the battery, means for producing a triggering signal when the generated safe final discharge voltage is equal to or greater than the actual voltage of the battery, and means responsive to the trigger signal for disconnecting the battery from a load.

Abstract: A circuit for detecting a missed commutation in an inverter. The circuit includes means coupled to the center tap of a commutating interval current limiting reactor which is connected in series with and interposed between a pair of gate controlled rectifiers for generating a first signal upon detecting and for the duration of an interval when both of the rectifiers are ON. The circuit further provides means, responsive to a first pulse used to initiate an interval when either of the pair of rectifiers is to be "ON", for generating a second signal. Also provided is a means responsive to the first and second signals for generating a control signal to cause cessation of the operation of the inverter, if the first signal is absent during the total occurrence of the second signal.