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Methods to Jump-Start a Single-Thermopile Powered Valve Control System

IP.com Disclosure Number: IPCOM000034050D
Publication Date: 2005-Jan-13
Document File: 3 page(s) / 24K

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U.S. 4,734,658: PATENT

Abstract

This publication describes a number of methods to provide electric energy to start a single thermopile powered valve control system. These methods are alternatives to start the microcontroller based system until another converter can be used to fully power the system with the thermopile voltage.

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Methods to Jump-Start a Single-Thermopile Powered Valve Control System

                                                Honeywell International, Inc.

Inventors: Douglas Bird, Brent Chian, Bruce Hill, Timothy Nordberg, and Rolf Strand

Abstract:  This publication describes a number of methods to provide electric energy to start a single thermopile powered valve control system.  These methods are alternatives to start the microcontroller based system until another converter can be used to fully power the system with the thermopile voltage.

Background:  A gas fired appliance such as a water heater or a fireplace may have a single thermopile as an electrical power source to provide electricity to run a micro based system.  The control system may have a built-in step-up DC/DC converter which, once started, can convert the thermopile output voltage to a higher level suitable to run the controller.  The thermopile output voltage alone may be too low (frequently only a few hundred milli-volts) to start the DC/DC converter, and therefore another method is required to start the microcontroller and/or the DC/DC converter.

Description of the Invention:   Six different methods to produce or provide temporary electrical potential of about 2 volts or higher to jump start a combustion control system which has a built-in DC/DC converter are described.  Once startup voltage has been provided, the DC/DC converter is used to continue stepping-up voltage from a low voltage source such as a thermopile.  The attached Figures are referenced in the description below.

            Referring to Figure 1, a piezo buzzer can be used to generate electrical charge when the piezo element is struck, bent, or otherwise mechanically deformed.  A rectifier network can be used to direct the charge to charge up a capacitor to more than 2 volts and start the system.  The piezo can be connected directly to one or two I/O pins of the microcontroller utilizing the I/O protection diodes as a rectifier network.  The piezo can also be used as an audio warning device after the micro is powered up.  An oscilloscope plot was recorded from an experiment using this method and is shown in Figure 5.  The plot includes Vdd and micro output to show how long the micro can run.  The test was performed with one hit to the piezo buzzer with a 3.2 uF capac...