Circuit diagnostics from flame sensing AC component
First Claim
Patent Images
1. A diagnostic flame sensing circuit comprising:
- a chopper;
a high voltage DC source connected to a first terminal of the chopper; and
a filter connected to a second terminal of the chopper; and
wherein;
a first output of the filter is provided to a flame sensor;
a second output of the filter comprises diagnostic information;
when the flame sensing circuit is activated, an analysis of the second output of the filter reveals a condition of one or more circuit components of the flame sensing circuit; and
the revealed condition of one or more circuit components of the flame sensing circuit includes one or more of;
a resistor having leakage;
a resistor being open;
a capacitor being smaller than normal;
a resistor to resistor ratio being incorrect;
a capacitor being shorted;
a frequency of a pulse width modulator being too low;
a capacitor having leakage;
the sensing timing of an analog-to-digital converter being out of sync with an output signal of the chopper;
the chopper having stopped;
a DC-DC voltage converter component not operating;
a frequency of a pulse width modulator being too low;
a capacitor being open;
the output of the second filter containing too much noise; and
a microcontroller having lost control over the chopper.
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Abstract
A diagnostic flame sensing circuit having less filtration so that an AC component of a flame sensing input is available for circuit diagnostics. Synchronized data sampling may used to detect the peak to peak magnitude of the residual AC component. A comparison of the magnitude of the component relative to a magnitude of the component during normal operation of the circuit may be used to check the condition of nearly all of the elements in the circuit.
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Citations
11 Claims
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1. A diagnostic flame sensing circuit comprising:
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a chopper; a high voltage DC source connected to a first terminal of the chopper; and a filter connected to a second terminal of the chopper; and wherein; a first output of the filter is provided to a flame sensor; a second output of the filter comprises diagnostic information; when the flame sensing circuit is activated, an analysis of the second output of the filter reveals a condition of one or more circuit components of the flame sensing circuit; and the revealed condition of one or more circuit components of the flame sensing circuit includes one or more of; a resistor having leakage; a resistor being open; a capacitor being smaller than normal; a resistor to resistor ratio being incorrect; a capacitor being shorted; a frequency of a pulse width modulator being too low; a capacitor having leakage; the sensing timing of an analog-to-digital converter being out of sync with an output signal of the chopper; the chopper having stopped; a DC-DC voltage converter component not operating; a frequency of a pulse width modulator being too low; a capacitor being open; the output of the second filter containing too much noise; and a microcontroller having lost control over the chopper. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification