Granted Patent B2

US 9,754,744 · App. 14/835,917 · Granted Sep 5, 2017

Abstract

Claims (43)

1. A relay turn-off control system for use with an alternating-current (AC) signal input, comprising:

a relay;

a relay current load sensor connected to the relay;

a rectifier circuit connected to the relay current load sensor and having an output;

a microprocessor connected to the rectifier circuit output; and

wherein the microprocessor is configured to:

a) define a plurality of successive time increments where each of the plurality of successive time increments combined are equal to a cycle time of the AC signal input;

b) output a first relay turn-off signal to the relay at a first of the plurality of successive time increments;

c) measure a duration time, after step b or f, for the rectifier circuit output to indicate that the relay has turned off;

d) perform a modulo operation of (duration time) mod (half the cycle time), wherein a remainder of the modulo operation is one of a non-zero value and a zero value;

e) store the remainder and an associated time increment in a memory coupled with the microprocessor;

f) output a next relay turn-off signal to the relay at a next of the plurality of successive time increments;

g) repeat steps c-f until the stored remainders of successive modulo operations transition from the non-zero value to the zero value or from the zero value to the non-zero value; and

h) set a relay turn-off signal output time at the associated time increment where the remainder of successive modulo operations transitioned from the non-zero value to the zero value or from the zero value to the non-zero value.

2. The control system of claim 1 , wherein the rectifier circuit output is synchronous with the AC signal input.

3. The control system of claim 1 , wherein the cycle time is divided into equal time increments.

4. The control system of claim 3 , wherein a number of the plurality of successive time increments is taken from a group consisting of 16, 32, and 64.

5. The control system of claim 1 , wherein the duration time is measured from a first rising edge to a last falling edge of the rectifier circuit output.

6. A relay turn-off control system for use with an alternating-current (AC) signal input, comprising:

a relay;

a relay current load sensor connected to the relay;

a rectifier circuit connected to the relay current load sensor and having an output;

a microprocessor connected to the rectifier circuit output; and

wherein the microprocessor is configured to set a relay turn-off signal output time based on an empirically determined duration time for the relay to turn-off and further based on determining a zero-cross period via use of a modulo operation;

wherein the zero-cross period is determined by configuring the microprocessor to:

a) define a plurality of successive time increments where each of the plurality of successive time increments combined are equal to a cycle time of the AC signal input;

b) perform a modulo operation of (duration time) mod (half the cycle time), wherein a remainder of the modulo operation is one of a non-zero value and a zero value;

c) store the remainder and an associated time increment in a memory coupled with the microprocessor;

d) output a next relay turn-off signal to the relay at a next of the plurality of successive time increments;

e) repeat steps b-d until the stored remainders of successive modulo operations transition from the non-zero value to the zero value or from the zero value to the non-zero value; and

f) set a relay turn-off signal output time at the associated time increment where the remainder of successive modulo operations transitioned from the non-zero value to the zero value or from the zero value to the non-zero value.

7. The control system of claim 6 , wherein the empirically determined duration time includes measuring, after the microprocessor outputs a relay turn-off signal to the relay, a time for the rectifier circuit output to indicate that the relay has turned off.

8. The control system of claim 7 , wherein the duration time is measured from a first rising edge to a last falling edge of the rectifier circuit output.

9. The control system of claim 6 , wherein the cycle time is divided into equal time increments.

10. The control system of claim 6 , wherein the rectifier circuit output is synchronous with the AC signal input.

11. A method performed by a microprocessor forming a part of a relay control system for use with an alternating-current (AC) signal input and where the relay control system includes a relay, a relay current load sensor connected to the relay, a rectifier circuit connected to the relay current load sensor and the microprocessor connected to a rectifier circuit output, comprising:

a) outputting a first relay turn-off signal to a relay at a first of a plurality of successive time increments where each of the plurality of successive time increments combined are equal to a cycle time of the AC signal input;

b) measuring a duration time, after step a or e, for the rectifier circuit output to indicate that the relay has turned off;

c) performing a modulo operation of (duration time) mod (half the cycle time), wherein a remainder of the modulo operation is one of a non-zero value and a zero value;

d) storing the remainder and an associated time increment in a memory coupled with the microprocessor;

e) outputting a next relay turn-off signal to the relay at a next of the plurality of successive time increments;

f) repeating steps b-e until the stored remainders of successive modulo operations transition from the non-zero value to the zero value or from the zero value to the non-zero value; and

g) setting a relay turn-off signal output time at the associated time increment where the remainder of successive modulo operations transitioned from the non-zero value to the zero value or from the zero value to the non-zero value.

Assignments (6)