ZERO CROSSING SYNCHRONOUS AC SWITCHING CIRCUITS EMPLOYING PIEZOCERAMIC BENDER-TYPE SWITCHING DEVICES

摘要

Zero Crossing Synchronous AC SwitchingCircuits Employing Piezoceramic Bender-Type Switching DevicesABSTRACT OF THE DISCLOSUREZero crossing synchronous AC switching circuitsare provided which employ piezoelectric ceramic bender-typeswitching devices for use in supplying loads of a resistive,inductive or capacitive nature. The circuits include zerocrossing sensing sub-circuits for sensing the passage throughzero value of a supply source of alternating currentvoltage and/or current and for deriving zero crossingtiming singals representative of the occurrance of thezero crossings. The zero crossing timing signals areemployed to control operation of a bender energizingpotential control sub-circuit for selectivelycontrolling application or removal of a benderenergizing potential across the piezoelectric bendermember of the bender-type switching devices. Phaseshift networks are included in the circuit for shifting thephase or time of application of the selectively appliedbender energization potential so as to cause it to closeor open a set of load current carrying switch contactssubstantially at or near the naturally occurring zerocrossings of the applied alternating current supplying theload.