Patent ID: 6108220
Filing Date: 2000-08-22
Classification: H02M,H05B

Abstract:
A vital load driver for supplying power to a load;(a) a fail-safe circuit comprising a rectifier for full wave rectification of an alternating current power;(b) a synchronous inverter for assembling a waveform from the rectified output of said rectifier said synchronous inverter further including,a synchronizer controlling the output of said synchronous inverter in response to a control signal to have a phase relationship generally corresponding to said alternating current power, first and second sets of paired switches, said switch sets being connected in said synchronous inverter so that in a first half-cycle of said alternating current power, said first switch set is in an ""on"" position and said second switch set is in an ""off"" position, and in a next occurring half cycle of said alternating current power, said first switch set is in an ""off"" position and said second switch set is in an ""on"" position, said switch sets being configured so that if said control signal is not present, neither said set of switches operates and said secondary of said transformer does not feed said load;(c) a transformer having a primary fed from the output of said synchronous inverter and secondary feeding said load; and,(d) a current sensor for detecting an increase in current resulting from a DC component being fed to said transformer.