Flame detector trapezoidal excitation generator output control circuit and method
AssigneeHoneywell International Inc.
InventorsMark Merry, Jeff Miller, Frank Madison
Life of this patent
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Abstract
An electronic circuit for generating a trapezoidal excitation waveform includes a controllable frequency source and a trapezoidal waveform generator. The controllable frequency source generates a source waveform that, upon energization thereof, has an initial frequency value, and decreases in frequency to a substantially constant frequency value a time period after energization. The trapezoidal waveform generator receives the source waveform and, in response, generates a trapezoidal waveform at least when the source waveform frequency attains the substantially constant frequency value.
Claims21
An electronic circuit for generating a trapezoidal excitation waveform, comprising:
- a controllable frequency source configured to generate a source waveform having a frequency that, upon energization of the controllable frequency source, decreases from an initial frequency value to a substantially constant frequency value a time period after energization of the controllable frequency source;
- and
- a trapezoidal waveform generator coupled to receive the source waveform and operable, in response thereto, to generate a trapezoidal waveform at least when the source waveform frequency attains the substantially constant frequency value.
A flame detector, comprising:
- a sensor configured to detect the presence of a flame and supply a signal representative of an intensity of the flame;
- an excitation circuit coupled to the sensor and operable to supply a sensor excitation signal thereto, the excitation circuit including:
- a controllable frequency source configured to generate a source waveform having a frequency that, upon energization of the controllable frequency source, decreases from an initial frequency value to a substantially constant frequency value a time period after energization of the controllable frequency source;
- and
- a trapezoidal waveform generator coupled to receive the source waveform and operable, in response thereto, to generate a trapezoidal waveform at least when the source waveform frequency attains the substantially constant frequency value.
A gas turbine engine, comprising:
- a compressor having an inlet and a compressed air outlet;
- a turbine having at least an inlet;
- a combustor having at least an air inlet, a fuel inlet, and a combustion gas outlet, the air inlet in fluid communication with the compressed air outlet, the fuel inlet adapted to receive a flow of fuel from a fuel source, and the combustion gas outlet in fluid communication with the turbine inlet;
- and
- a flame detector coupled to the combustor, the flame detector configured to detect the presence of a flame in the combustor and supply a signal representative of an intensity of the flame;
- an excitation circuit coupled to the flame detector and operable to supply an excitation signal thereto, the excitation circuit including:
- a controllable frequency source configured to generate a source waveform having a frequency that, upon energization of the controllable frequency source, decreases from an initial frequency value to a substantially constant frequency value a time period after energization of the controllable frequency source;
- and
- a trapezoidal waveform generator coupled to receive the source waveform and operable, in response thereto, to generate a trapezoidal waveform at least when the source waveform frequency attains the substantially constant frequency value.
A method of generating a trapezoidal waveform, comprising:
- generating a square wave having a frequency that decreases from an initial frequency value to a substantially constant frequency value over a time period;
- integrating the square wave to thereby generate a triangular wave having a peak voltage magnitude that increases from an initial voltage value to a substantially constant voltage value over the time period;
- and
- limiting the peak voltage magnitude of the triangular wave to a predetermined value,
- wherein the trapezoidal waveform is generated when the triangular wave peak voltage magnitude exceeds the predetermined value.
Dependencies are inferred from the claim text.