TRIAC OR BYPASS CIRCUIT AND MOSFET POWER STEAL COMBINATION

• US 20140312131A1
• Filed: 04/23/2013
• Published: 10/23/2014
• Est. Priority Date: 04/23/2013
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Tousignant, Daniel, Landry, Daniel, Daher, Alex
• Granted Patent: US 9,584,119 B2
• Time in Patent Office: Days
• US Class Current: 236/1.C
• CPC Class Codes: H03K 17/16 Modifications for eliminating interference voltages or currents
• CPC Class Codes: H03K 17/725 for ac voltages or currents H03K17/722, H03K17/735 take precedence

Abstract

A power supply unit for use with thermostats or other like devices requiring power. A power supply unit may be designed to keep electromagnetic interference emissions at a minimum, particularly at a level that does not violate governmental regulations. A unit may be designed so that there is enough power for a triggering a switch at about a cross over point of a waveform of input power to the unit. Power for triggering may come from a storage source rather than line power to reduce emissions on the power line. Power for the storage source may be provided with power stealing. Power stealing may require switching transistors which can generate emissions. Gate signals to the transistors may be especially shaped to keep emissions from transistor switching at a minimum.

Claims

1. A power supply unit for a heat, ventilation and air conditioning thermostat, comprising:

a triac having an input, a gate and an output;

a bypass circuit having an input connected to the input of the triac;

a stealing circuit having an input connected to an output of the bypass circuit; and

a MOSFET power steal module having an input connected to the output of the triac; and

wherein the input of the triac and an output of the MOSFET power steal module are primary terminals for connection in a power circuit.

2. The unit of claim 1, wherein the power circuit comprises a power source connected in series with an electrical load.

3. The unit of claim 2, wherein the electrical load is electric heating mechanism.

4. The unit of claim 1, wherein:

the stealing circuit comprises an energy storage module;

the MOSFET power steal module steals energy and the energy goes to the energy storage module; and

the energy is used to trigger the triac at a zero crossing of line voltage from the power source.

5. The unit of claim 1, further comprising a gate signal shaper connected to the MOSFET power steal module.

6. The unit of claim 5, wherein the gate signal shaper provides a gate signal that results in a soft transition of turning on and off of the MOSFETs.

7. The unit of claim 4, further comprising a half wave zero cross detect module connected to the line voltage, to a gate signal shaper, and to a triac gate triggering module.

8. Power supply electronics for a thermostat, comprising:

a first terminal for connection to a first line of a power source;

a bypass circuit having an input connected to the first terminal;

a triac having an input connected to the first terminal;

a second terminal for connection to a load;

a stealing circuit having an input connected to an output of the bypass circuit and an output connected to the second terminal; and

a power steal module having an input connected to the output of the triac and an output connected to the second terminal.

9. The electronics of claim 8, wherein:

the power steal module comprises one or more MOSFETs that are switched on to steal power;

the stealing circuit comprises an energy storage unit; and

stolen power goes to the energy storage unit.

10. The electronics of claim 8, wherein the bypass circuit comprises an RC network.

11. The electronics of claim 8, wherein the bypass circuit comprises an AC-DC converter.

12. The electronics of claim 9, further comprising a linear regulator and a super capacitor connected to an output of the energy storage unit.

13. The electronics of claim 10, further comprising a DC-DC converter connected to an output of the energy storage unit.

14. The electronics of claim 8, wherein if the power steal module comprises two or more MOSFETs, then a serial MOSFETs power stealing approach is effected.

15. A thermostatic power supply comprising:

a bypass circuit;

a first terminal for connection to a power source;

a second terminal for connection to a load;

a bypass circuit having an input connected to the first terminal;

an energy storage module having an input connected to the bypass circuit and an output connected to the second terminal;

a triggerable switch having an input connected to the first terminal; and

a power steal module having an input connected to an output of the triggerable switch and an output connected to the second terminal.

16. The supply of claim 15, further comprising:

a DC-DC converter having an input connected to the output of the energy storage module; and

wherein the bypass circuit comprises an AC-DC converter.

17. The supply of claim 15, further comprising:

a linear regulator having an input connected to the output of the energy storage module; and

wherein the bypass circuit comprises an RC network.

18. The supply of claim 17, further comprising a super capacitor connected to the linear regulator.

19. The supply of claim 15, wherein the triggerable switch is selected from a group consisting of a triac, SCR and a relay.

20. The supply of claim 15, wherein the power steal module comprises one or more switching MOSFETs.