Asymmetrical unipolar flame ionizer using a step-up transformer

Abstract

A system and method for electrically charging a combustion flame with a power supply.

What is claimed is: 
     
         1 . A system for electrically controlling a combustion flame, comprising:
 a burner configured to generate the combustion flame,
 wherein the combustion flame includes a resistance and a capacitance; 
   an ionizer positioned proximate to the burner to supply ions of a first polarity to the combustion flame to charge the capacitance of the combustion flame to one or more voltage levels; and   a power supply coupled to the ionizer and configured to provide an output voltage signal of the first polarity to the ionizer to excite the ionizer to supply the ions of the first polarity to the combustion flame,
 wherein the power supply includes a transformer and an output dampener operatively coupled in parallel to the transformer, 
 wherein the output dampener suppresses a second polarity of the output voltage signal to limit delivery of ions of the second polarity to the combustion flame by the ionizer. 
   
     
     
         2 . The system of  claim 1 , wherein the capacitance is between three and five picofarads (3-5 pF). 
     
     
         3 . The system of  claim 1 , wherein the ionizer is positioned at least 1 inch away from combustion flame. 
     
     
         4 . The system of  claim 1 , wherein the first polarity is positive and the second polarity is negative. 
     
     
         5 . The system of  claim 1 , wherein the first polarity is negative and the second polarity is positive. 
     
     
         6 . The system of  claim 1 , wherein the ionizer includes an emitting electrode. 
     
     
         7 . The system of  claim 6 , wherein the ionizer includes a collecting electrode. 
     
     
         8 . The system of  claim 7 , wherein the emitting electrode and the collecting electrode are positioned on opposite sides of the combustion flame to direct a flow of the ions into the combustion flame. 
     
     
         9 . The system of  claim 7 , wherein the collecting electrode is the burner that is configured to generate the combustion flame. 
     
     
         10 . The system of  claim 1 , wherein the ionizer is configured to supply the ions upon excitation with approximately 4 kV. 
     
     
         11 . The system of  claim 1 , wherein output voltage signal of the first polarity is a square-wave pulse. 
     
     
         12 . The system of  claim 1 , wherein the power supply includes a primary winding and a secondary winding. 
     
     
         13 . The system of  claim 12 , wherein the output dampener is electrically coupled in parallel to the primary winding. 
     
     
         14 . The system of  claim 12 , wherein the output dampener is electrically coupled in parallel to the secondary winding. 
     
     
         15 . The system of  claim 12 , wherein the output dampener includes a resistor. 
     
     
         16 . The system of  claim 15 , wherein the output dampener includes a diode electrically coupled in series to the resistor. 
     
     
         17 . The system of  claim 16 , wherein the diode is oriented to allow current to continue flowing through the primary winding of the transformer after power is removed from the primary winding. 
     
     
         18 . A system for electrically controlling a combustion flame, comprising:
 a first power supply configured to generate a first output voltage pulse of a first polarity in excess of a first predetermined threshold,
 wherein the first power supply includes a first step-up transformer, 
 wherein the first power supply includes a first output dampener coupled to the first step-up transformer and configured to at least partially suppress a second output voltage pulse of a second polarity to prevent the second output voltage pulse from exceeding a second predetermined threshold; 
   a second power supply configured to generate a third output voltage pulse of the first polarity in excess of the first predetermined threshold,
 wherein the second power supply includes a second step-up transformer, 
 wherein the second power supply includes a second output dampener coupled to the second step-up transformer and configured to at least partially suppress a fourth output voltage pulse of the second polarity to prevent the fourth output voltage pulse from exceeding the second predetermined threshold, 
 wherein the second polarity is different than the first polarity; 
   a first ionizer operatively coupled to the first power supply and configured to supply first ions of the first polarity to a combustion flame to charge the combustion flame, in response to receipt of the first output voltage pulse;   a second ionizer operatively coupled to the second power supply and configured to supply second ions of the first polarity to the combustion flame to charge the combustion flame, in response to receipt of the third output voltage pulse; and   a controller communicatively coupled to the first power supply and to the second power supply to selectively cause the first ionizer and the second ionizer to supply the first ions and the second ions to the combustion flame.   
     
     
         19 . The system of  claim 18 , wherein the first predetermined threshold is approximately 4 kV and the second predetermined threshold is approximately −4 kV. 
     
     
         20 . The system of  claim 18 , wherein the first polarity is positive and the second polarity is negative. 
     
     
         21 . The system of  claim 18 , wherein the controller time-multiplexes operation of the first power supply and the second power supply so that the first output voltage pulse and the third output voltage pulse are generated sequentially. 
     
     
         22 . The system of  claim 18 , wherein the first output dampener includes a first resistor and a first diode, wherein the first diode is oriented to enable a first current to continue flowing through a primary winding of the first transformer, wherein the second output dampener includes a second resistor and a second diode, wherein the second diode is oriented to enable a second current to continue flowing through a primary winding of the second transformer. 
     
     
         23 . The system of  claim 18 , wherein the first ionizer includes a first emitter electrode and a first collector electrode, wherein the second ionizer includes a second emitter electrode and a second collector electrode. 
     
     
         24 . The system of  claim 23 , wherein the first emitter electrode and the first collector electrode are positioned on first opposite sides of the combustion flame, and the second emitter electrode and the second collector electrode are positioned on second opposite sides of the combustion flame. 
     
     
         25 . The system of  claim 18 , further comprising:
 a third power supply configured to generate a fifth output voltage pulse of the second polarity in excess of the second predetermined threshold,
 wherein the third power supply includes a third step-up transformer, 
 wherein the third power supply includes a third output dampener coupled to the third step-up transformer and configured to at least partially suppress a sixth output voltage pulse of the first polarity to prevent the sixth output voltage pulse from exceeding the first predetermined threshold; and 
   a third ionizer operatively coupled to the third power supply and configured to supply third ions of the second polarity to the combustion flame to charge the combustion flame, in response to receipt of the fifth output voltage pulse,   wherein the controller is configured to time multiplex operation of the third power supply to selectively cause the third power supply to generate the fifth output pulse to supply the combustion flame with the third ions of the second polarity.   
     
     
         26 . The system of  claim 18 , wherein the combustion flame includes a resistance and a capacitance, wherein the capacitance is approximately 3-5 pF. 
     
     
         27 . A method for electrically controlling a combustion flame, comprising:
 generating, with a power supply, a voltage signal having a first portion of a first polarity and having a second portion of a second polarity,
 wherein the first portion of the voltage signal is greater than or equal to a first predetermined threshold; 
   suppressing the second portion of the voltage signal, with an output dampener, to prevent the second portion of the voltage signal from exceeding a second predetermined threshold, by reducing a rate of current change in a transformer of the power supply, while generating the second portion of the voltage signal; and   generating ions of the first polarity, with an ionizer, in response to receiving the first portion of the voltage signal,
 wherein generating ions includes supplying the ions to a combustion flame to charge the combustion flame to a voltage to alter one or more characteristics of the combustion flame. 
   
     
     
         28 . The method of  claim 27 , wherein the combustion flame includes a capacitance. 
     
     
         29 . The method of  claim 28 , wherein the capacitance is between three and five picofarads (3-5 pF). 
     
     
         30 . The method of  claim 27 , wherein the first polarity is positive and the second polarity is negative. 
     
     
         31 . The method of  claim 27 , wherein the first predetermined threshold is 4 kV and the second predetermined threshold is −4 kV. 
     
     
         32 . The method of  claim 27 , wherein the output dampener includes a resistor and a diode coupled in series, wherein the output dampener is coupled in parallel to the transformer. 
     
     
         33 . The method of  claim 27 , wherein the transformer includes a primary winding and a secondary winding and the output dampener is coupled to the primary winding. 
     
     
         34 . The method of  claim 27 , wherein suppressing the second portion of the voltage signal to prevent the second portion of the voltage signal from exceeding the second predetermined threshold prevents the ionizer from generating ions of the second polarity. 
     
     
         35 . The method of  claim 27 , wherein the first predetermined threshold is a corona onset voltage for a fluid that is proximate to the ionizer. 
     
     
         36 . The method of  claim 27 , wherein the second predetermined threshold is a negative corona onset voltage. 
     
     
         37 . The method of  claim 27 , wherein the ionizer includes an emitter electrode and a collector electrode. 
     
     
         38 . The method of  claim 27 , wherein the ionizer includes an emitter electrode and the combustion flame functions as a collector electrode. 
     
     
         39 . The method of  claim 27 , wherein the ionizer includes an emitter electrode and a burner is coupled to the power supply to function as a collector electrode, wherein the burner generates the combustion flame. 
     
     
         40 . The method of  claim 27 , wherein the power supply generates the voltage signal in response to receiving a command signal from a controller.