Intelligent input for relay device containing a solid state relay

Patent metadata

Field	Value
Publication number	US-2017194956-A1
Application number	US-201614987484-A
Country	US
Kind code	A1
Filing date	Jan 4, 2016
Priority date	Jan 4, 2016
Publication date	Jul 6, 2017
Grant date	—

Abstract

Relays can be used in a variety of applications that use a smaller signal to control a higher power load. Some example loads include motors, stadium lighting and the like. Mechanical relays consist of a coil controlling a magnet that moves electrical contacts. Solid state relays can offer advantages such as lower power consumption and higher reliability than mechanical relays. However, using a solid state relay in a system designed for a mechanical relay can require some significant changes to the system. This disclosure presents a device, a system and technique to operate a solid state relay (SSR) in applications that use mechanical relays while minimizing the need for potentially costly modifications.

First claim

1 . A solid state relay (SSR) device that includes an output port and an input port, the relay device comprising:
a power switch wherein an output of the power switch corresponds to the output port of the SSR device; and a control unit configured to:
receive an input signal at the input port of the SSR device;
determine a voltage level of the input signal received at the input port; and
in response to the voltage level of the input signal satisfying a threshold, wait for a predetermined time delay, and after the predetermined time delay, control the output of the power switch, thereby controlling the output of the SSR device.

2 . The device of claim 1 , wherein the control unit determines the voltage level of the input signal satisfies a threshold by determining that the voltage level is both:
greater than a first threshold voltage, and less than a second threshold voltage.

3 . The device of claim 2 wherein the control unit is configured to detect a first fault in the input signal based on the value of the first voltage threshold, wherein the first fault comprises a short to ground (STG).

4 . The device of claim 2 wherein the control unit is configured to detect a second fault and a third fault in the input signal, based the value of the second voltage threshold, wherein the second fault comprises a short to battery (STB) and the third fault comprises a leakage in the input signal.

5 . The device of claim 2 wherein the control unit comprises:
a first comparator;
a second comparator; and
a time delay unit that includes a trigger input,
wherein the trigger input is coupled to both an output of the first comparator and an output of the second comparator,
wherein the time delay unit, in response to a trigger signal at the trigger input, is configured to wait for a pre-determined time delay, and after the pre-determined time delay, control the output of the power switch,
wherein a first input of the first comparator is coupled to the input port of the relay device and a second input of the first comparator is coupled to the first voltage threshold,
wherein a first input of the second comparator is coupled to the input port of the SSR device a second input of the second comparator coupled to the second voltage threshold,
wherein the output of the first comparator, in response to the voltage level of the input signal being greater than the first voltage threshold, outputs the trigger signal to the trigger input, and
wherein the output of the second comparator, in response to the voltage level of the input signal being less than the second voltage threshold, outputs the trigger signal to the trigger input.

6 . The device of claim 1 , wherein the predetermined time delay is a configurable parameter.

7 . The device of claim 2 , configured with an independent hysteresis for the first voltage threshold and the second voltage threshold.

8 . The device of claim 7 wherein the predetermined time delay is between approximately 5 milliseconds and approximately 30 milliseconds.

9 . The device of claim 7 wherein the time delay unit controls the power switch by activating a switch comprising one or more of: a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), a metal-oxide semiconductor field effect transistor (MOSFET), and an opto-isolator.

10 . A method comprising:
receiving an input signal at an input port of a solid state relay (SSR) device; determining whether a voltage level of the input signal received at the input port of the SSR device satisfies a threshold; and in response to the voltage level of the input signal satisfying the threshold, controlling an output of the SSR device after a predetermined time delay.

11 . The method of claim 10 , wherein determining whether the voltage level of the input signal received at the input port of the SSR device satisfies a threshold comprises determining that the input signal voltage level is greater than a first voltage threshold and less than a second voltage threshold.

12 . The method of claim 11 further comprising:
in response to determining whether a voltage level of the input signal received at the input port of the SSR device satisfies the threshold, outputting a trigger signal such that the trigger signal has a first logic level if the voltage level of the input signal received at the input port of the relay device satisfies the threshold and such that the trigger signal has a second logic level otherwise,
wherein the input port of the SSR device is coupled both to a first input of a first comparator and to a first input of a second comparator,
wherein a second input of the first comparator is coupled to the first voltage threshold and a second input of the second comparator is coupled to the second voltage threshold,
wherein outputting the trigger signal comprises:
outputting the first logic level by an output of the first comparator if the voltage level of the input signal received at the input port of the relay device is greater than the first voltage level and outputting a second logic level by the output of the first comparator otherwise; and
outputting the first logic level by an output of the second comparator if the voltage level of the input signal is less than the second voltage level and outputting a second logic level by the output of the second comparator otherwise; and

in response to the trigger signal having the first logic level, thereby indicating the voltage level of the input signal satisfies the threshold, controlling an output of the SSR device after a predetermined time delay.

13 . The method of claim 11 wherein the voltage level of the input signal received at the input port of the SSR device satisfying a threshold indicates that the SSR device determined the input signal was free of a fault comprising one or more of: a short to battery (STB), a short to ground (STG) and leakage in the input signal.

14 . The method of claim 10 , wherein the predetermined time delay comprises a delay between approximately 5 milliseconds and approximately 30 milliseconds.

15 . The method of claim 10 , wherein the predetermined time delay comprises delaying for sufficient time to debounce the input signal.

16 . A system comprising:
a solid state (SSR) relay device that includes an output port and an input port, the SSR device comprising:
a power switch wherein an output of the power switch corresponds to the output of the SSR device; and
a control unit configured to:
receive an input signal at the input port of the SSR device;
determine a voltage level of the input signal received at the input port; and
in response to the voltage level of the input signal satisfying a threshold, wait for a predetermined time delay, and after the predetermined time delay, control the output of the power switch, thereby controlling the output of the SSR device;

an input switch configured to supply the input signal to the input port of the SSR device; and a load controlled by the output port of the SSR device.

17 . The system of claim 16 , wherein the input switch is selected from a group consisting of a mechanical switch, a hall switch, a control unit switch and an electronic control unit.

18 . The system of claim 16 wherein the load comprises one or more of: a motor, a solenoid, an actuator, a lighting fixture, and a valve.

19 . The system of claim 16 wherein the threshold is configured to detect a fault, wherein the fault comprises a short to battery (STB), a short to ground (STG) and leakage in the input sig

Assignees

• Infineon Technologies Ag

Inventors

• Ugale Ramdas Rangnath
• Py Jerome

Classifications

• H03K17/28 Primary

  Modifications for introducing a time delay before switching (modifications to provide a choice of time-intervals for executing more than one switching action H03K17/296) · CPC title

• H02H9/04

  responsive to excess voltage (lightning arrestors H01C7/12, H01C8/04, H01G9/18, H01T) · CPC title

• H01H47/002

  Monitoring or fail-safe circuits · CPC title

• H03K2017/515

  Mechanical switches; Electronic switches controlling mechanical switches, e.g. relais · CPC title

• H03K17/567

  Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT · CPC title