US 6,233,132 B1 · Zero cross relay actuation method and system implementing same

Abstract

An electromechanical relay drive system which prolongs relay life by ensuring operation of the relay in a manner to make and break contact between the contact electrodes at a zero crossing point of the switched waveform. Relay aging and environmental variations are dynamically compensated upon each actuation of the electromechanical relay to ensure proper timing of the energization and de-energization of the relay to ensure switching at the zero crossing point. Additionally, the drive system described compensates for variations in the actual contact operation during actuation for the positive and negative half cycle of the switched waveform. Furthermore, the system of the instant invention alternately energizes and de-energizes the electromechanical relay during the positive and negative half cycles of the switched waveform to prevent metal deposition from one contact electrode to the other. This system calculates the appropriate delays on a dynamic historical perspective by sensing slope changes of the coil voltage and current.

Claims29

Dependent claims

A method of controlling the actuation of an electrical relay having a coil and at least two electrical contacts, one of which being coupled to an electrical source, comprising the steps of:

actuating the relay;
monitoring a first electrical parameter of the coil during actuation of the relay;
calculating an actuation time of the relay based on the monitored first electrical parameter of the coil;
monitoring a second and a third electrical parameter of the electrical source;
calculating an actuation command delay based on the actuation time of the relay and the second parameter of the electrical source;
and
delaying actuation of the relay for the actuation command delay based on the third electrical parameter.

4 more elements

A relay actuation circuit for use with a relay having at least one coil and at least one set of contacts, at least one of the contacts being coupled to a source of ac electric power, comprising:

a slope detector circuit coupled to the coil and monitoring a slope of a parameter of electric power during energization of the coil;
a relay driver circuit;
and
a logic processor circuit in sensory communication with said slope detector circuit, and in controllable contact with said relay driver circuit, said logic processor circuit including a timing circuit;
and
wherein said logic processor circuit determines a relay actuation delay time as a period from initiation of said relay driver circuit to a positive change in slope of said parameter following a negative slope after an initial positive slope.

3 more elements

Dependencies are inferred from the claim text.

Zero cross relay actuation method and system implementing same

Life of this patent

Zero cross relay actuation method and system implementing same

Life of this patent

Abstract

Claims29