Method and apparatus for controlling a relay

Patent metadata

Field	Value
Publication number	US-11367579-B2
Application number	US-202117140425-A
Country	US
Kind code	B2
Filing date	Jan 4, 2021
Priority date	Jan 27, 2020
Publication date	Jun 21, 2022
Grant date	Jun 21, 2022

Abstract

In a method for controlling a relay with a relay contact, switching as an opening operation or a closing operation at the relay is temporally captured with respect to accurate opening or closing of the relay contact in comparison with a switching voltage zero crossing of a switching voltage to be switched. An actual switching time is determined and is corrected by means of further capturing of switching operations. A microcontroller is used for this purpose, and the signals can be digitally captured, that is to say at an A/D input.

First claim

The invention claimed is:

1. A method for controlling a relay, said relay having a relay contact, the method comprising the steps of:
switching as an opening operation or as a closing operation at said relay is temporally captured with respect to an accurate opening or an accurate closing of said relay contact in comparison with a switching voltage zero crossing of a switching voltage to be switched,
determining a period between control of said relay using a switching trigger signal and an actual opening or an actual closing of said relay contact with stopping or starting of a switching current flow as a switching delay,
monitoring said switching voltage to be switched by said relay,
after enabling a command to switch, controlling said relay to switch using said switching trigger signal in a manner moved forward in terms of time by said switching delay before a subsequent switching voltage zero crossing,
capturing an actual switching time carried out in addition to said switching voltage zero crossing,
conducting a check to determine whether said actual switching time was too late or too early by a switching difference relative to said switching voltage zero crossing, wherein said switching delay is corrected with said switching difference for subsequent identical switching:
by adding said switching difference to said switching delay if said actual switching time was too late by said switching difference relative to said switching voltage zero crossing, or
by subtracting said switching difference from said switching delay if said actual switching time was too early by said switching difference relative to said switching voltage zero crossing,

wherein:
a microcontroller is used to capture said switching or said opening operation and said closing operation and said switching voltage zero crossing; and
said opening operation and said closing operation are each alternatively conducted at an end of a positive half-cycle and at an end of a negative half-cycle of said switching voltage, such that the opening operation is carried out alternatively and continuously after the end of the positive half-cycle, then after the end of the negative half-cycle, and then again after an end of another positive half-cycle in a repetitive manner, and such that the closing operation is carried out alternately and continuously after the end of the positive half-cycle, and then after the end of the negative half-cycle, and then after the end of the another positive half-cycle in a repetitive manner.

2. The method as claimed in claim 1 , wherein said switching is carried out in a temporal range of +/−0.4 ms around said switching voltage zero crossing.

3. The method as claimed in claim 1 , wherein resistive loads are switched during said switching.

4. The method as claimed in claim 3 , wherein solely resistive loads are switched during said switching.

5. The method as claimed in claim 1 , wherein a closing switching delay and an opening switching delay are determined separately for said closing operation and said opening operation, respectively.

6. The method as claimed in claim 1 , wherein, after enabling a command to switch, said relay is controlled to switch, in a manner moved forward in terms of time by said switching delay before a subsequent switching voltage zero crossing, within a duration of a half-cycle of said switching voltage and after a last captured switching voltage zero crossing.

7. The method as claimed in claim 1 , wherein, after a first operation of switching on an electrical appliance with said relay therein, said relay is switched once in any desired manner at any desired time in order to roughly capture a duration of said switching delay as an initial switching delay, wherein, when first switching said relay, said initial switching delay is then used as period for controlling said relay with said switching trigger signal before a switching voltage zero crossing, wherein said switching delay is then captured and is further used instead of said initial switching delay for further operation of said electrical appliance with switching of said relay.

8. The method as claimed in claim 1 , wherein said switching delay is corrected for each subsequent switching operation or each subsequent opening operation and closing operation.

9. The method as claimed in claim 1 , wherein a switching delay of an earlier switching is stored, and, if currently captured values for said switching delay differ by more than 20% from said switching delay of an earlier switching, a fault in said relay or in control for said relay is detected and is signaled to an operator.

10. The method as claimed in claim 9 , wherein said switching delay of said earlier switching is stored both for an opening operation and for a closing operation.

11. The method as claimed in claim 9 , wherein said closing operation of said relay as a switching-on operation is prevented and is not carried out.

12. The method as claimed in claim 1 , wherein between 1000 and 20,000 measurement points per second are used as a sampling frequency for said microcontroller.

13. An apparatus configured to implement the method of claim 1 , said apparatus comprising:
a relay with a relay contact,
a load to be connected to a switching voltage by said relay,
connections to a controller for controlling said relay,
a microcontroller which is connected to signal inputs having a signal corresponding to said switching voltage and a signal corresponding to said actual opening or said actual closing of said relay contact,
wherein the microcontroller is configured to control said opening operation and said closing operation in said repetitive, continuous, and alternative manner.

14. The apparatus as claimed in claim 13 , wherein said apparatus is integrated in an electrical household appliance or in a cooking appliance.

15. The apparatus as claimed in claim 14 , wherein said apparatus is integrated in a controller for said electrical household appliance or said cooking appliance.

16. The apparatus as claimed in claim 14 , wherein said load is a resistive load.

Assignees

• Ego Elektro Geraetebau Gmbh

Inventors

• Engelhardt Patrick
• Kraemer Eduard

Classifications

• H01H9/56 Primary

  for ensuring operation of the switch at a predetermined point in the AC cycle · CPC title

• H01H2009/566

  with self learning, e.g. measured delay is used in later actuations · CPC title

• H01H47/18

  for introducing delay in the operation of the relay (short-circuited conducting sleeves, bands or discs H01H50/46) · CPC title