Current zero cross switching relay module using a voltage monitor
First Claim
1. A relay switching system comprising:
- a. a relay having at least one pair of contacts, wherein a first contact of the pair of contacts is coupled to an AC power source, thereby forming a first coupling, and wherein a second contact of the pair of contacts is coupled to a load, thereby forming a second coupling;
b. a voltage detector, in communication with the second coupling, for detecting inductive kickback in the load voltage signal across the second coupling;
c. a reference circuit, in communication with the first coupling, for detecting voltage zero cross for the line voltage signal across the second coupling;
d. a relay driver, in communication with the relay, for switching the relay in response to a control signal; and
e. a processor in communication with the voltage detector, the reference circuit, and the relay driver, the processor configured to produce a control signal at a time T, wherein T is X time units prior to the next voltage zero cross for the line voltage signal;
wherein the processor continuously adjusts X by adding an error value, and wherein the processor calculates the error value by analyzing the inductive kickback in the load voltage signal; and
wherein the processor calculates the sign of the error value based on the sign of the inductive kickback in the load voltage signal and the sign of the line voltage signal subsequent to the last switching.
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Accused Products
Abstract
Assemblies, systems, and methods which prolong relay life by dynamically compensating the make and break contact timing between the contact points of the relay and a zero crossing point of the power supply'"'"'s waveform are provided according to the present disclosure. The life cycle of the relay components are dramatically increased through the use of these assemblies, systems, and methods due to a decrease in arcing and other physically damaging phenomena between the contacts of the relay. The present disclosure also provides for assemblies, systems, and methods whereby a processor analyzes the inductive kickback effect in the relay load voltage signal and dynamically adjust the relay open time such that the inductive kickback effect is minimized. In exemplary embodiments, the systems/methods provided herein advantageously adjust the relay open time such that the relay switching time corresponds with current zero cross and do so without requiring complicated current monitoring components.
106 Citations
14 Claims
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1. A relay switching system comprising:
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a. a relay having at least one pair of contacts, wherein a first contact of the pair of contacts is coupled to an AC power source, thereby forming a first coupling, and wherein a second contact of the pair of contacts is coupled to a load, thereby forming a second coupling; b. a voltage detector, in communication with the second coupling, for detecting inductive kickback in the load voltage signal across the second coupling; c. a reference circuit, in communication with the first coupling, for detecting voltage zero cross for the line voltage signal across the second coupling; d. a relay driver, in communication with the relay, for switching the relay in response to a control signal; and e. a processor in communication with the voltage detector, the reference circuit, and the relay driver, the processor configured to produce a control signal at a time T, wherein T is X time units prior to the next voltage zero cross for the line voltage signal; wherein the processor continuously adjusts X by adding an error value, and wherein the processor calculates the error value by analyzing the inductive kickback in the load voltage signal; and wherein the processor calculates the sign of the error value based on the sign of the inductive kickback in the load voltage signal and the sign of the line voltage signal subsequent to the last switching. - View Dependent Claims (2, 3, 4, 5, 13)
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6. A method for switching a relay comprising the steps of:
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a. providing a relay having at least one pair of contacts, wherein a first contact of the pair of contacts is coupled to an AC power source, thereby forming a first coupling, and wherein a second contact of the pair of contacts is coupled to a load, thereby forming a second coupling; b. providing a relay driver, in communication with the relay, for switching the relay in response to a control signal; c. determining time, T, for producing a control signal, wherein T is X time units before the time of the next voltage zero cross for the line voltage signal across the second coupling; d. switching the relay by producing a control signal at time T; e. calculating an error value for X by analyzing inductive kickback in the load voltage signal across the second coupling; and f. adjusting X and T by adding the error value to X; wherein the sign of the error value is calculated based on the sign of the inductive kickback in the load voltage signal and the sign of the line voltage signal subsequent to the last switching. - View Dependent Claims (7, 8, 9, 10, 11, 12, 14)
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Specification