Abstract:
A direct current (DC) deicing control system including a direct current (DC) power source, and a periodic deicing waveform generator electrically connected to the DC power source. The periodic deicing waveform generator outputs a switched DC voltage having a periodic electrical current waveform including periods of zero voltage and periods of non-zero voltage. The periods of zero voltage define arc extinguishing events reducing arc formation in the DC deicing control system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 62/117,144 filed on Feb. 17, 2015. The contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Exemplary embodiments pertain to the art of aircraft deicing systems and, more particularly, to a direct current (DC) deicing control system, a DC deicing system, and an aircraft including a DC deicing system. 
         [0003]    Aircraft, both fixed wing and rotary wing, employ deicing systems on various external surfaces. Deicing systems may be mounted to fuselage panels, wing panels, or rotary blades and are operated to eliminate or at least reduce ice buildup. Typically, a deicing system will employ heaters that cause any built up ice to de-bond and be removed by aerodynamic forces during flight. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    Disclosed is a direct current (DC) deicing control system including a DC power source, and a periodic deicing waveform generator electrically connected to the DC power source. The periodic deicing waveform generator outputting a switched DC voltage having a periodic electrical current waveform including periods of zero voltage and periods of non-zero voltage. The periods of zero voltage define arc extinguishing events reducing arc formation in the DC deicing control system. 
         [0005]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase periodic waveform generator configured and disposed to deliver a plurality of circuit phases to at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage. 
         [0006]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shifting periodic deicing waveform generator configured and disposed to deliver a plurality of circuit phases to at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, the periods of zero voltage for each of the plurality of circuit phases being off-set relative to the periods of zero voltage for others of the plurality of circuit phases. 
         [0007]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shaped periodic deicing waveform generator configured and disposed to deliver a plurality of circuit phases to at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, each of the periods of zero voltage including a curvilinear profile. 
         [0008]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shaped periodic deicing waveform generator configured and disposed to deliver a plurality of circuit phases to at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, each of the periods of non-zero voltage including a curvilinear profile. 
         [0009]    Also disclosed is a direct current (DC) deicing system including at least one deicing mat, and a DC deicing control system operably connected to the deicing mat. The DC deicing control system having a DC power source and a periodic deicing waveform generator electrically connected to the DC power source and the deicing mat. The periodic deicing waveform generator outputting a switched DC voltage having a periodic electrical current waveform to the at least one deicing mat. The periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage. The periods of zero voltage define arc extinguishing events reducing arc formation in the DC deicing control system. 
         [0010]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase periodic deicing waveform generator delivering a plurality of periodic phases to the at least one deicing mat, each of the plurality of periodic phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage. 
         [0011]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shifting periodic deicing waveform generator delivering a plurality of circuit phases to the at least one deicing mat, each of the plurality of periodic phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, the periods of zero voltage for each of the plurality of circuit phases being off-set relative to the periods of zero voltage for others of the plurality of circuit phases. 
         [0012]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shaped periodic deicing waveform generator delivering a plurality of circuit phases to the at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, each of the periods of zero voltage including a curvilinear profile. 
         [0013]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shaped periodic deicing waveform generator delivering a plurality of circuit phases to the at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, each of the periods of non-zero voltage including a curvilinear profile. 
         [0014]    Further disclosed is an aircraft including a fuselage, at least one deicing mat operably coupled to the fuselage, and a direct current (DC) deicing control system operably coupled to the deicing mat, the DC deicing control system having a DC power source, and a deicing waveform generator electrically connected to the DC power source and the at least one deicing mat. The deicing waveform generator outputting a switched DC voltage having a periodic electrical current waveform to the at least one deicing mat. The periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage. The periods of zero voltage define arc extinguishing events reducing arc formation in the DC deicing control system 
         [0015]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase periodic deicing waveform generator delivering a plurality of circuit phases to the at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage. 
         [0016]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shifting periodic deicing waveform generator delivering a plurality of circuit phases to the at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, the periods of zero voltage for each of the plurality of circuit phases being off-set relative to the periods of zero voltage for others of the plurality of circuit phases. 
         [0017]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shaped periodic deicing waveform generator delivering a plurality of circuit phases to the at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, each of the periods of zero voltage including a curvilinear profile. 
         [0018]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the periodic deicing waveform generator comprises a polyphase, phase shaped periodic deicing waveform generator delivering a plurality of circuit phases to the at least one deicing mat, each of the plurality of circuit phases including a periodic electrical current waveform having periods of zero voltage and periods of non-zero voltage, each of the periods of non-zero voltage including a curvilinear profile. 
         [0019]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the aircraft comprises a rotary wing aircraft including at least one rotor assembly operably connected to the fuselage. 
         [0020]    In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the at least one deicing mat is operably mounted to at least one rotor blade of the at least one rotor assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0022]      FIG. 1  depicts a rotary wing aircraft including a direct current (DC) deicing system, in accordance with an exemplary embodiment; 
           [0023]      FIG. 2  depicts a block diagram illustrating a DC deicing controller and periodic deicing waveform generator of the deicing system of  FIG. 1 ; and 
           [0024]      FIG. 3  depicts a polyphase, shifted and shaped DC output from the periodic deicing system of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
         [0026]      FIG. 1  depicts an exemplary embodiment of a rotary wing, vertical takeoff and land (VTOL) aircraft  10 . The aircraft  10  includes an airframe or fuselage  12  with an extending tail  14 . A main rotor assembly  18  is located at the fuselage  12  and rotates about a main rotor axis (not shown). In an exemplary embodiment, the fuselage  12  includes a cockpit  20  having two seats for flight crew (e.g., pilot and co-pilot) and six seats for passengers (not shown). Main rotor assembly  18  is driven by a power source, for example, one or more engines  24 , via a gearbox  26 . Main rotor assembly  18  includes a rotor hub  28  that supports a plurality of rotor blades, one of which is indicated at  32 . Aircraft  10  may also include a tail rotor assembly  44  supported by extending tail  14 . 
         [0027]    In accordance with an aspect of an exemplary embodiment, aircraft  10  includes a direct current (DC) deicing system  50 . DC deicing system  50  includes a first deicing mat  52  arranged on fuselage  12  near cockpit  20  and a second deicing mat  53  arranged on fuselage  12  near tail  14 . Further deicing mats  55  and  56  may be applied to surfaces of rotor blades  32 . DC deicing system  50  also includes a DC deicing control system  64  having a DC power source  68  and a periodic deicing waveform generator  70 . As will be detailed more fully below, periodic deicing waveform generator  70  may selectively deliver a periodic electrical current to each deicing mat  52 ,  53  and  55 ,  56 . Of course, it should be understood that the number and location of the deicing mats may vary. 
         [0028]    As shown in  FIG. 2 , deicing mat  52  includes a first heater coil  81 , a second heater coil  82  and a third heater coil  83 . Heater coils  81 - 83  are electrically coupled to DC power source  68  through periodic deicing waveform generator  70 . In accordance with an aspect of an exemplary embodiment periodic deicing waveform generator  70  takes the form of a polyphase periodic deicing waveform generator delivering a periodic electrical current waveform to each heater coil  81 - 83 . In accordance with another aspect of an exemplary embodiment, periodic deicing waveform generator  70  delivers a first electrical current waveform  88  to heater coil  81 , a second electrical current waveform  89  to heater coil  82 , and a third electrical current waveform  90  to heater coil  83 . Each of the first, second and third electrical current waveforms  88 ,  89  and  90  represent a switched DC waveform having defined periods of zero voltage. 
         [0029]    As shown in  FIG. 3 , first electrical current wave form  88  includes a plurality of periods of zero voltage  92  and a plurality of periods of non-zero voltage  93 . Similarly, second electrical current wave form  89  includes a plurality of periods of zero voltage  95  and a plurality of periods of non-zero voltage  96 , and third electrical current waveform  90  includes a plurality of periods of zero voltage  98  and a plurality of periods of non-zero voltage  99 . In accordance with another aspect of an exemplary embodiment, periodic deicing waveform generator  70  takes the form of a phase shifting periodic deicing waveform generator. More specifically, periods of zero voltage  92  are off-set relative to periods of zero voltage  95 ,  98  and periods of non-zero voltage  93  are off-set relative to periods of non-zero voltage  96  and  99 . Further periods of zero voltage  95  are off-set relative to periods of zero voltage  92 ,  98  and periods of non-zero voltage  96  are off-set relative to periods of non-zero voltage  93  and  99 . By shifting the periods of zero voltage relative to other periods of zero voltage and periods of non-zero voltage relative to other periods of non-zero voltage, DC deicing waveform generator  70  produces a more uniform loading from DC power source  68 . 
         [0030]    In accordance with another aspect of an exemplary embodiment, periodic deicing waveform generator  70  takes the form of a wave shaping periodic waveform generator. More specifically, each electrical waveform  88 - 90  includes a generally curvilinear profile. More specifically, each of the periods of zero voltage  92 ,  95  and  98  include a curvilinear profile, and each of the periods of non-zero voltage  93 ,  96 , and  99  include a curvilinear profile. By removing sharp corners typically associated with DC waveforms, periodic deicing waveform generator  70  creates a polyphase waveform which reduces any potential or tendency for arcing. Further, outputting a switched DC waveform having periods of zero voltage every cycle, would be rapidly extinguish any arcs that may form. More specifically, a zero crossing for each period will provide an arc extinguishing event, e.g., a defined period of zero voltage, once per cycle thereby resulting in fewer arcs being formed and or propagated. 
         [0031]    While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.