PATENT DOCUMENT

Abstract:
An example power management arrangement includes a motor controller configured to communicate power to a motor drive bridge to drive a motor. The motor controller is configurable to selectively receive power from each of a first power supply and a second power supply. The voltage of the power from the first power supply is different than a voltage of the power from the second power supply. An example power adjusting method includes receiving power at a motor controller, adjusting a voltage of the received power using the motor controller, communicating the power with the adjusted voltage from the motor controller to a motor drive bridge to drive a motor.

Full Description:
BACKGROUND 
     This application relates generally to adjusting power. More particularly, this application relates to adjusting a voltage of power. 
     Power conversion products, such as servo position-control drives, motor speed-control drives, power supplies, etc., typically utilize relatively unmodified power. The power moves directly from a single bus power source to a servo position-control drive, for example. The power may be processed to protect the quality of the provided power. The processing does not significantly change the power. The processing is typically limited to filtering electromagnet interference from the power or to a factor correction of the power. 
     In a prior art arrangement, a motor assembly includes a servo motor portion and a motor controller portion. The motor assembly is configured to actuate a fuel valve or other engine components within a gas turbine engine, such as bleed valves or compressor variable geometries. The motor controller receives unaltered power directly from a single bus. The motor controller communicates the power to the servo motor. The prior art motor assembly is not able to receive power from another bus having another bus voltage. The servo motor assembly typically includes heat sinks that are used to communicate thermal energy away from the servo motor. The heat sinks undesirably increase the size of the servo motor assembly. The motor is unitary electric motor, for example, and includes an actuator assembly having an explosion-proof construction that facilitates use in explosive gas environments. 
     SUMMARY 
     An example power management arrangement includes a motor controller configured to communicate power to a motor drive bridge to drive a motor. The motor controller is configurable to selectively receive power from each of a first power supply and a second power supply. The voltage of the power from the first power supply is different than a voltage of the power from the second power supply. 
     An example power adjusting method includes receiving power at a motor controller, adjusting a voltage of the received power using the motor controller, communicating the power with the adjusted voltage from the motor controller to a motor drive bridge to drive a motor. 
     Another example method of powering a motor includes receiving power at a motor controller, using the motor controller to adjust a voltage of the received power, powering components of a motor using the power having the adjusted voltage. 
     These and other features of the example disclosure can be best understood from the following specification and drawings, the following of which is a brief description: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic view of an example gas turbine engine having a power management arrangement. 
         FIG. 2  shows a schematic view of the  FIG. 1  power management arrangement. 
         FIG. 3  shows a flow of an example power adjusting method. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , an example gas turbine engine  10  includes (in serial flow communication) an inlet section  14 , a centrifugal compressor  18 , a combustor section  26 , a turbine wheel  30 , and a turbine exhaust  34 . The gas turbine engine  10  is circumferentially disposed about an engine centerline X. During operation, air is pulled into the gas turbine engine  10  by the inlet section  14 , pressurized by the centrifugal compressor  18 , mixed with fuel, and burned in the combustor section  26 . The turbine wheel  30  extracts energy from the hot combustion gases flowing from the combustor section  26 . 
     The turbine wheel  30  utilizes the extracted energy from the hot combustion gases to power the centrifugal compressor  18 . The examples described in this disclosure are not limited to the radial turbine type auxiliary power units described, however, and may be used in axial architectures. The examples also may be used in gas turbine engines that are single-spool designs, two-spool designs, and three-spool designs. That is, there are various types of engines and engine architectures that could benefit from the examples disclosed herein, which are not limited to the radial turbine design shown. 
     The combustor section  26  of the gas turbine engine  10  is configured to receive fuel from a fuel supply  42 . In this example, the fuel is sprayed from an injector  44  into the combustor section  26 . 
     A motor assembly  46  has motor components  48  controlled by a motor controller  58 . The motor assembly  46  is a servo motor assembly in this example. The motor components  48 , such as rotors and coils, are configured to actuate a valve  50  to control the flow of fuel between the fuel supply  42  and the combustor section  26 . In another example, the motor components  48  are configured to actuate a bleed valve or to vary geometries of the compressor  18 . 
     The motor assembly  46  also includes a heat sink  68  that helps remove thermal energy from the motor assembly  46  that is generated during operation. 
     The examples described in this disclosure are not limited to the motor assembly  46  that controls the valve  50  of the gas turbine engine  10 . That is, other types of motors in other environments would benefit from teachings of the examples described in this disclosure. In other examples, the motor assembly  46  is used in factory automation, process control (fluids, gases, etc.), structural testing, aircraft simulators, etc., which use electric actuators with motor controllers and single power buses. 
     The example motor assembly  46  is powered by a power supply  54  having a bus voltage of about 120 V. Other examples of the gas turbine engine  10  utilize power supplies having different bus voltages, such as 12 V, 24 V, 48 V, etc. 
     In this example, the motor controller  58  includes a power management section  62  and a motor drive bridge section  66 . Power moves from the power supply  54  through the power management section  62  before moving to the motor drive bridge section  66 . The motor controller  58  is part of the motor assembly  46  in this example. In another example, the motor controller  58  is separate from the motor assembly  46 . 
     The example power management section  62  has a buck boost portion that adjusts the voltage of power from the power supply  54  to a level appropriate for driving the motor components  48 . In one example, the power management section  62  adjusts the voltage of the received power downward from 120 V to 60 V before the power reaches the motor drive bridge section  66 . That is, the power enters the power management section  62  at 120 V and exits the power management section  62  at 60 V. Adjusting the voltage allows the motor assembly to be powered by bus voltages ranging from 60 V to 120 V. 
     The example power management section  62  includes at least one switch  74 , at least one diode  78 , and an inductor  82 . A person skilled in the art and having benefit of this disclosure would understand how to reduce a voltage of the power provided by the power supply  54  using the power management section  62 . As can be appreciated, the adjustments to the voltage by the power management section  62  are more substantial than the prior art arrangements that processed power. 
     The example motor drive bridge section  66  includes a plurality of switches  70   a - 70   f  that are used to regulate current to the motor assembly  46 . One or more of phases A-C are typically energized to hold the motor assembly  46  in a given position. The switches  70   a - 70   f  control which phases A-C are energized. In one example, phases A and B are energized by pulse width modulating the switch  70   a  while allowing current to move through a reverse diode of the switch  70   b . Example switches  70   a - 70   f  include insolated gate bipolar transistors (IGBTs) and field effect transistors (FETs) or some combination of these. 
     In one example, the motor assembly  46  is driven at  20 A with a terminal winding resistance of 0.25 ohms. The motor assembly  46  utilizes IGBTs as switches  70   a - 70   f  that have a forward voltage of 1.6 V, a switching time (T sw ) of 150 nsec, an inverse diode forward voltage of 1.5 V and a switching frequency of 15 kHz. Such an example generates about 73 Watts of thermal energy (motor drive bridge loss), which is calculated as follows: 
     
       
         
           
             
               Motor 
               ⁢ 
               
                   
               
               ⁢ 
               drive 
               ⁢ 
               
                   
               
               ⁢ 
               bridge 
               ⁢ 
               
                   
               
               ⁢ 
               loss 
             
             = 
             
                 
               
                 
                   [ 
                   
                     Upper 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     IGBT 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Switching 
                     ⁢ 
                     
                       
                           
                       
                       ⁢ 
                       
                           
                       
                     
                     ⁢ 
                     Loss 
                   
                   ] 
                 
                 + 
                 
                   [ 
                   
                     Upper 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     IGBT 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     DC 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Loss 
                   
                   ] 
                 
                 + 
                 
                     
                   
                     
                       [ 
                       
                         Lower 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         Drive 
                         ⁢ 
                         
                           
                               
                           
                           ⁢ 
                           
                               
                           
                         
                         ⁢ 
                         IGBT 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         DC 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         Loss 
                       
                       ] 
                     
                     + 
                     
                         
                       
                         
                           [ 
                           
                             Lower 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             Free 
                             ⁢ 
                             
                               - 
                             
                             ⁢ 
                             Wheeling 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             IGBT 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             Diode 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             Loss 
                           
                           ] 
                         
                         = 
                         
                           
                             
                               2 
                               * 
                               
                                 ∫ 
                                 
                                   
                                     
                                       T 
                                       SW 
                                     
                                     ⁡ 
                                     
                                       [ 
                                       
                                         
                                           V 
                                           IGBT 
                                         
                                         * 
                                         
                                           I 
                                           IGBT 
                                         
                                       
                                       ] 
                                     
                                   
                                   ⁢ 
                                   
                                     ⅆ 
                                     t 
                                   
                                 
                               
                             
                             + 
                             
                               ∫ 
                               
                                 
                                   
                                     T 
                                     on 
                                   
                                   ⁡ 
                                   
                                     [ 
                                     
                                       
                                         V 
                                         IGBT 
                                       
                                       * 
                                       
                                         I 
                                         IGBT 
                                       
                                     
                                     ] 
                                   
                                 
                                 ⁢ 
                                 
                                   ⅆ 
                                   t 
                                 
                               
                             
                             + 
                             
                               
                                 V 
                                 IGBT 
                               
                               * 
                               
                                 I 
                                 IGBT 
                               
                             
                             + 
                             
                               ∫ 
                               
                                 
                                   
                                     T 
                                     off 
                                   
                                   ⁡ 
                                   
                                     [ 
                                     
                                       
                                         V 
                                         IGBTDiode 
                                       
                                       * 
                                       
                                         I 
                                         IGBT 
                                       
                                     
                                     ] 
                                   
                                 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 
                                   ⅆ 
                                   t 
                                 
                               
                             
                           
                           = 
                           
                               
                             
                               
                                 [ 
                                 
                                   2 
                                   * 
                                   
                                     V 
                                     rail 
                                   
                                   * 
                                   
                                     I 
                                     m 
                                   
                                   * 
                                   
                                     
                                       T 
                                       SW 
                                     
                                     / 
                                     T 
                                   
                                 
                                 ] 
                               
                               + 
                               
                                 [ 
                                 
                                   
                                     V 
                                     IGBT 
                                   
                                   * 
                                   
                                     I 
                                     m 
                                   
                                   * 
                                   
                                     
                                       T 
                                       on 
                                     
                                     / 
                                     T 
                                   
                                 
                                 ] 
                               
                               + 
                               
                                   
                                 
                                   
                                     
                                       [ 
                                       
                                         
                                           I 
                                           m 
                                         
                                         * 
                                         
                                           V 
                                           IGBT 
                                         
                                       
                                       ] 
                                     
                                     + 
                                     
                                       [ 
                                       
                                         
                                           I 
                                           m 
                                         
                                         * 
                                         
                                           V 
                                           IGBTDiode 
                                         
                                         * 
                                         
                                           
                                             T 
                                             off 
                                           
                                           / 
                                           T 
                                         
                                       
                                       ] 
                                     
                                   
                                   = 
                                   
                                       
                                     
                                       
                                         [ 
                                         
                                           2 
                                           * 
                                           120 
                                           * 
                                           20 
                                           * 
                                           150 
                                           ⁢ 
                                           e 
                                           ⁢ 
                                           
                                             - 
                                           
                                           ⁢ 
                                           
                                             9 
                                             / 
                                             66.7 
                                           
                                           ⁢ 
                                           
                                               
                                           
                                           ⁢ 
                                           e 
                                           ⁢ 
                                           
                                             - 
                                           
                                           ⁢ 
                                           6 
                                         
                                         ] 
                                       
                                       + 
                                       
                                           
                                         
                                           
                                             [ 
                                             
                                               1.6 
                                               * 
                                               20 
                                               * 
                                               2.78 
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               e 
                                               ⁢ 
                                               
                                                 - 
                                               
                                               ⁢ 
                                               
                                                 6 
                                                 / 
                                                 66.7 
                                               
                                               ⁢ 
                                               e 
                                               ⁢ 
                                               
                                                 - 
                                               
                                               ⁢ 
                                               6 
                                             
                                             ] 
                                           
                                           + 
                                           
                                             [ 
                                             
                                               
                                                 20 
                                                 2 
                                               
                                               * 
                                               1.6 
                                             
                                             ] 
                                           
                                           + 
                                           
                                               
                                             
                                               
                                                 [ 
                                                 
                                                   20 
                                                   * 
                                                   1.5 
                                                   * 
                                                   63.9 
                                                   ⁢ 
                                                   e 
                                                   ⁢ 
                                                   
                                                     - 
                                                   
                                                   ⁢ 
                                                   
                                                     6 
                                                     / 
                                                     66.7 
                                                   
                                                   ⁢ 
                                                   e 
                                                   ⁢ 
                                                   
                                                     - 
                                                   
                                                   ⁢ 
                                                   6 
                                                 
                                                 ] 
                                               
                                               ≈ 
                                               
                                                 73 
                                                 ⁢ 
                                                 
                                                     
                                                 
                                                 ⁢ 
                                                 Watts 
                                               
                                             
                                           
                                         
                                       
                                     
                                   
                                 
                               
                             
                           
                         
                       
                     
                   
                 
               
             
           
         
       
     
     In another example, 250 V FETs are used as switches  70   a - 70   f  in place of the IGBTs. The 250 V FETs have an inverse diode forward voltage of 1.5V and a terminal winding resistance (Rdson) of 40 mOhms at 100 degrees C. Such an example generates about 43 Watts of thermal energy (motor drive bridge loss), which is calculated as follows: 
     
       
         
           
             
               Motor 
               ⁢ 
               
                   
               
               ⁢ 
               drive 
               ⁢ 
               
                   
               
               ⁢ 
               bridge 
               ⁢ 
               
                   
               
               ⁢ 
               loss 
             
             = 
             
               
                 [ 
                 
                   Upper 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   FET 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   Switching 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   Loss 
                 
                 ] 
               
               + 
               
                   
                 
                   
                     [ 
                     
                       Upper 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       FET 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       DC 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Loss 
                     
                     ] 
                   
                   + 
                   
                     [ 
                     
                       Lower 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Drive 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       FET 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       DC 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Loss 
                     
                     ] 
                   
                   + 
                   
                       
                     
                       
                         [ 
                         
                           Lower 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           Free 
                           ⁢ 
                           
                             - 
                           
                           ⁢ 
                           Wheeling 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           FET 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           Switching 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           Loss 
                         
                         ] 
                       
                       + 
                       
                           
                         
                           
                             [ 
                             
                               Lower 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Free 
                               ⁢ 
                               
                                 - 
                               
                               ⁢ 
                               Wheeling 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               FET 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               DC 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Loss 
                             
                             ] 
                           
                           + 
                           
                               
                             
                               
                                 [ 
                                 
                                   Lower 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   Free 
                                   ⁢ 
                                   
                                     - 
                                   
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   Wheeling 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   FET 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   Diode 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   Dead 
                                   ⁢ 
                                   
                                     - 
                                   
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   Time 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   Loss 
                                 
                                 ] 
                               
                               = 
                               
                                 
                                   2 
                                   * 
                                   
                                     ∫ 
                                     
                                       
                                         
                                           T 
                                           SW 
                                         
                                         ⁡ 
                                         
                                           [ 
                                           
                                             
                                               V 
                                               FET 
                                             
                                             * 
                                             
                                               I 
                                               FET 
                                             
                                           
                                           ] 
                                         
                                       
                                       ⁢ 
                                       
                                         ⅆ 
                                         t 
                                       
                                     
                                   
                                 
                                 + 
                                 
                                   ∫ 
                                   
                                     
                                       
                                         T 
                                         on 
                                       
                                       ⁡ 
                                       
                                         [ 
                                         
                                           
                                             R 
                                             DSon 
                                           
                                           * 
                                           
                                             I 
                                             FET 
                                             2 
                                           
                                         
                                         ] 
                                       
                                     
                                     ⁢ 
                                     
                                       ⅆ 
                                       t 
                                     
                                   
                                 
                                 + 
                                 
                                   
                                     R 
                                     DSon 
                                   
                                   * 
                                   
                                     I 
                                     FET 
                                     2 
                                   
                                 
                                 + 
                                 
                                   2 
                                   * 
                                   
                                     
                                       ∫ 
                                       TSW 
                                     
                                     ⁢ 
                                     
                                       
                                         [ 
                                         
                                           
                                             V 
                                             FET 
                                           
                                           * 
                                           
                                             I 
                                             FET 
                                           
                                         
                                         ] 
                                       
                                       ⁢ 
                                       
                                         ⅆ 
                                         t 
                                       
                                     
                                   
                                 
                                 + 
                                 
                                   ∫ 
                                   
                                     
                                       T 
                                       off 
                                     
                                     ⁢ 
                                     
                                         
                                       
                                         
                                           
                                             
                                               [ 
                                               
                                                 
                                                   R 
                                                   DSon 
                                                 
                                                 * 
                                                 
                                                   I 
                                                   FET 
                                                   2 
                                                 
                                               
                                               ] 
                                             
                                             ⁢ 
                                             
                                               ⅆ 
                                               t 
                                             
                                           
                                           + 
                                           
                                             ∫ 
                                             
                                               
                                                 
                                                   T 
                                                   dead 
                                                 
                                                 ⁡ 
                                                 
                                                   [ 
                                                   
                                                     
                                                       V 
                                                       FETDiode 
                                                     
                                                     * 
                                                     
                                                       I 
                                                       FET 
                                                     
                                                   
                                                   ] 
                                                 
                                               
                                               ⁢ 
                                               
                                                   
                                               
                                               ⁢ 
                                               
                                                 ⅆ 
                                                 t 
                                               
                                             
                                           
                                         
                                         = 
                                         
                                             
                                           
                                             
                                               [ 
                                               
                                                 2 
                                                 * 
                                                 
                                                   V 
                                                   rail 
                                                 
                                                 * 
                                                 
                                                   I 
                                                   m 
                                                 
                                                 * 
                                                 
                                                   
                                                     T 
                                                     SW 
                                                   
                                                   / 
                                                   T 
                                                 
                                               
                                               ] 
                                             
                                             + 
                                             
                                               [ 
                                               
                                                 
                                                   R 
                                                   DSon 
                                                 
                                                 * 
                                                 
                                                   I 
                                                   m 
                                                   2 
                                                 
                                                 * 
                                                 
                                                   
                                                     T 
                                                     on 
                                                   
                                                   / 
                                                   T 
                                                 
                                               
                                               ] 
                                             
                                             + 
                                             
                                                 
                                               
                                                 
                                                   [ 
                                                   
                                                     
                                                       I 
                                                       m 
                                                       2 
                                                     
                                                     * 
                                                     
                                                       R 
                                                       dson 
                                                     
                                                   
                                                   ] 
                                                 
                                                 + 
                                                 
                                                   [ 
                                                   
                                                     2 
                                                     * 
                                                     
                                                       V 
                                                       FETDiode 
                                                     
                                                     * 
                                                     
                                                       I 
                                                       m 
                                                     
                                                     * 
                                                     
                                                       
                                                         T 
                                                         SW 
                                                       
                                                       / 
                                                       T 
                                                     
                                                   
                                                   ] 
                                                 
                                                 + 
                                                 
                                                     
                                                   
                                                       
                                                     
                                                       
                                                         [ 
                                                         
                                                           
                                                             I 
                                                             m 
                                                             2 
                                                           
                                                           * 
                                                           
                                                             R 
                                                             dson 
                                                           
                                                           ⁢ 
                                                           
                                                             
                                                             T 
                                                             off 
                                                             
                                                             / 
                                                             T 
                                                           
                                                         
                                                         ] 
                                                       
                                                       ⁢ 
                                                       
                                                           
                                                       
                                                       ⁢ 
                                                       
                                                           
                                                         
                                                           + 
                                                           
                                                               
                                                             
                                                             
                                                             [ 
                                                             
                                                             
                                                             V 
                                                             FETDiode 
                                                             
                                                             * 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             I 
                                                             m 
                                                             
                                                             * 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             
                                                             T 
                                                             DeadSW 
                                                             
                                                             / 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             T 
                                                             
                                                             
                                                             ] 
                                                             
                                                             = 
                                                             
                                                               
                                                             
                                                             
                                                             [ 
                                                             
                                                             2 
                                                             * 
                                                             120 
                                                             * 
                                                             20 
                                                             * 
                                                             150 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             9 
                                                             / 
                                                             66.7 
                                                             
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                             [ 
                                                             
                                                             .008 
                                                             * 
                                                             
                                                             20 
                                                             2 
                                                             
                                                             * 
                                                             2.78 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             6 
                                                             / 
                                                             
                                                               
                                                             
                                                             66.7 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                               
                                                             
                                                             
                                                             [ 
                                                             
                                                             
                                                             20 
                                                             2 
                                                             
                                                             * 
                                                             .008 
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                               
                                                             
                                                             [ 
                                                             
                                                             
                                                             2 
                                                             * 
                                                             1.5 
                                                             * 
                                                             20 
                                                             * 
                                                             150 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             9 
                                                             / 
                                                             
                                                               
                                                             
                                                             66.7 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                             
                                                             
                                                             [ 
                                                             
                                                             
                                                             20 
                                                             2 
                                                             
                                                             * 
                                                             .008 
                                                             * 
                                                             63.9 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             6 
                                                             / 
                                                             66.7 
                                                             
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                             [ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             1.5 
                                                             * 
                                                             20 
                                                             * 
                                                             300 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             9 
                                                             / 
                                                             66.7 
                                                             
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             
                                                             ≈ 
                                                             
                                                             43 
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             Watts 
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                           
                                                         
                                                       
                                                     
                                                   
                                                 
                                               
                                             
                                           
                                         
                                       
                                     
                                   
                                 
                               
                             
                           
                         
                       
                     
                   
                 
               
             
           
         
       
     
     In another example, 100 V FETs are used as switches  70   a - 70   f  in place of the IGBTs. The 100 V FETs have an inverse diode forward voltage of 1.5V and a terminal winding resistance (Rdson) of 8.0 mOhms at a junction temperature of 100 degrees C. Such an example generates about 18 Watts of thermal energy or motor drive bridge loss, which is calculated as follows: 
     
       
         
           
             
               Motor 
               ⁢ 
               
                   
               
               ⁢ 
               drive 
               ⁢ 
               
                   
               
               ⁢ 
               bridge 
               ⁢ 
               
                   
               
               ⁢ 
               loss 
             
             = 
             
               
                 [ 
                 
                   Upper 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   FET 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   Switching 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   Loss 
                 
                 ] 
               
               + 
               
                   
                 
                   
                     [ 
                     
                       Upper 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       FET 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       DC 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Loss 
                     
                     ] 
                   
                   + 
                   
                     [ 
                     
                       Lower 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Drive 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       FET 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       DC 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Loss 
                     
                     ] 
                   
                   + 
                   
                       
                     
                       Lower 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Free 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       Wheeling 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       FET 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Switching 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Loss 
                     
                     ] 
                   
                   + 
                   
                       
                     
                       
                         [ 
                         
                           Lower 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           Free 
                           ⁢ 
                           
                             - 
                           
                           ⁢ 
                           Wheeling 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           FET 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           DC 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           Loss 
                         
                         ] 
                       
                       + 
                       
                           
                         
                           
                             [ 
                             
                               Lower 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Free 
                               ⁢ 
                               
                                 - 
                               
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Wheeling 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               FET 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Diode 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Dead 
                               ⁢ 
                               
                                 - 
                               
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Time 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               Loss 
                             
                             ] 
                           
                           = 
                           
                             
                               2 
                               * 
                               
                                 ∫ 
                                 
                                   
                                     
                                       T 
                                       SW 
                                     
                                     ⁡ 
                                     
                                       [ 
                                       
                                         
                                           V 
                                           FET 
                                         
                                         * 
                                         
                                           I 
                                           FET 
                                         
                                       
                                       ] 
                                     
                                   
                                   ⁢ 
                                   
                                     ⅆ 
                                     t 
                                   
                                 
                               
                             
                             + 
                             
                               ∫ 
                               
                                 
                                   
                                     T 
                                     on 
                                   
                                   ⁡ 
                                   
                                     [ 
                                     
                                       
                                         R 
                                         DSon 
                                       
                                       * 
                                       
                                         I 
                                         FET 
                                         2 
                                       
                                     
                                     ] 
                                   
                                 
                                 ⁢ 
                                 
                                   ⅆ 
                                   t 
                                 
                               
                             
                             + 
                             
                               
                                 R 
                                 DSon 
                               
                               * 
                               
                                 I 
                                 FET 
                                 2 
                               
                             
                             + 
                             
                               2 
                               * 
                               
                                 
                                   ∫ 
                                   TSW 
                                 
                                 ⁢ 
                                 
                                   
                                     [ 
                                     
                                       
                                         V 
                                         FET 
                                       
                                       * 
                                       
                                         I 
                                         FET 
                                       
                                     
                                     ] 
                                   
                                   ⁢ 
                                   
                                     ⅆ 
                                     t 
                                   
                                 
                               
                             
                             + 
                             
                               ∫ 
                               
                                 
                                   T 
                                   off 
                                 
                                 ⁢ 
                                 
                                     
                                   
                                     
                                       
                                         
                                           [ 
                                           
                                             
                                               R 
                                               DSon 
                                             
                                             * 
                                             
                                               I 
                                               FET 
                                               2 
                                             
                                           
                                           ] 
                                         
                                         ⁢ 
                                         
                                           ⅆ 
                                           t 
                                         
                                       
                                       + 
                                       
                                         ∫ 
                                         
                                           
                                             
                                               T 
                                               dead 
                                             
                                             ⁡ 
                                             
                                               [ 
                                               
                                                 
                                                   V 
                                                   FETDiode 
                                                 
                                                 * 
                                                 
                                                   I 
                                                   FET 
                                                 
                                               
                                               ] 
                                             
                                           
                                           ⁢ 
                                           
                                               
                                           
                                           ⁢ 
                                           
                                             ⅆ 
                                             t 
                                           
                                         
                                       
                                     
                                     = 
                                     
                                         
                                       
                                         
                                           [ 
                                           
                                             2 
                                             * 
                                             
                                               V 
                                               rail 
                                             
                                             * 
                                             
                                               I 
                                               m 
                                             
                                             * 
                                             
                                               
                                                 T 
                                                 SW 
                                               
                                               / 
                                               T 
                                             
                                           
                                           ] 
                                         
                                         + 
                                         
                                           [ 
                                           
                                             
                                               R 
                                               DSon 
                                             
                                             * 
                                             
                                               I 
                                               m 
                                               2 
                                             
                                             * 
                                             
                                               
                                                 T 
                                                 on 
                                               
                                               / 
                                               T 
                                             
                                           
                                           ] 
                                         
                                         + 
                                         
                                             
                                           
                                               
                                             
                                               
                                                 [ 
                                                 
                                                   
                                                     I 
                                                     m 
                                                     2 
                                                   
                                                   * 
                                                   
                                                     R 
                                                     dson 
                                                   
                                                 
                                                 ] 
                                               
                                               + 
                                               
                                                 [ 
                                                 
                                                   2 
                                                   * 
                                                   
                                                     V 
                                                     FETDiode 
                                                   
                                                   * 
                                                   
                                                     I 
                                                     m 
                                                   
                                                   * 
                                                   
                                                     
                                                       T 
                                                       SW 
                                                     
                                                     / 
                                                     T 
                                                   
                                                 
                                                 ] 
                                               
                                               + 
                                               
                                                   
                                                 
                                                   
                                                     [ 
                                                     
                                                       
                                                         I 
                                                         m 
                                                         2 
                                                       
                                                       * 
                                                       
                                                         R 
                                                         dson 
                                                       
                                                       ⁢ 
                                                       
                                                         
                                                           T 
                                                           off 
                                                         
                                                         / 
                                                         T 
                                                       
                                                     
                                                     ] 
                                                   
                                                   ⁢ 
                                                   
                                                       
                                                   
                                                   ⁢ 
                                                   
                                                       
                                                     
                                                       + 
                                                       
                                                           
                                                         
                                                           + 
                                                           
                                                               
                                                             
                                                             
                                                             [ 
                                                             
                                                             
                                                             V 
                                                             FETDiode 
                                                             
                                                             * 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             I 
                                                             m 
                                                             
                                                             * 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             
                                                             T 
                                                             DeadSW 
                                                             
                                                             / 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             T 
                                                             
                                                             
                                                             ] 
                                                             
                                                             = 
                                                             
                                                               
                                                             
                                                             
                                                             [ 
                                                             
                                                             2 
                                                             * 
                                                             120 
                                                             * 
                                                             20 
                                                             * 
                                                             150 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             9 
                                                             / 
                                                             66.7 
                                                             
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                             [ 
                                                             
                                                             .008 
                                                             * 
                                                             
                                                             20 
                                                             2 
                                                             
                                                             * 
                                                             2.78 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             6 
                                                             / 
                                                             
                                                               
                                                             
                                                             66.7 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                               
                                                             
                                                             
                                                             [ 
                                                             
                                                             
                                                             20 
                                                             2 
                                                             
                                                             * 
                                                             .008 
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                               
                                                             
                                                             [ 
                                                             
                                                             
                                                             2 
                                                             * 
                                                             1.5 
                                                             * 
                                                             20 
                                                             * 
                                                             150 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             9 
                                                             / 
                                                             
                                                               
                                                             
                                                             66.7 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             
                                                             
                                                             + 
                                                             
                                                               
                                                             
                                                             
                                                             
                                                             [ 
                                                             
                                                             
                                                             20 
                                                             2 
                                                             
                                                             * 
                                                             .008 
                                                             * 
                                                             63.9 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             6 
                                                             / 
                                                             66.7 
                                                             
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             + 
                                                             
                                                             [ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             
                                                             1.5 
                                                             * 
                                                             20 
                                                             * 
                                                             300 
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             
                                                             9 
                                                             / 
                                                             66.7 
                                                             
                                                             ⁢ 
                                                             e 
                                                             ⁢ 
                                                             
                                                             - 
                                                             
                                                             ⁢ 
                                                             6 
                                                             
                                                             ] 
                                                             
                                                             
                                                             ≈ 
                                                             
                                                             18 
                                                             ⁢ 
                                                             
                                                               
                                                             
                                                             ⁢ 
                                                             Watts 
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                           
                                                         
                                                       
                                                     
                                                   
                                                 
                                               
                                             
                                           
                                         
                                       
                                     
                                   
                                 
                               
                             
                           
                         
                       
                     
                   
                 
               
             
           
         
       
     
     As can be appreciated from the above calculations, the example incorporating the 100 V FETs generates less thermal energy than the other examples. The power management section  62  in this example reduces the voltage from a 120 VDC source to a level suitable for using with the 100 V FETs, such as reducing the 120 V to 60 V. As less thermal energy is generated, the motor assembly  46  can have a smaller area devoted to the heat sink  68  and a smaller enclosure. Reducing the voltage of the power sent to the motor assembly  46  thus facilitates selecting the motor assembly  46  having a relatively small spatial envelope. 
     In another example, the motor assembly  46  was previously used in another application where the motor assembly  46  was provided power by another power supply (not shown) having a bus voltage of 24 V. The input voltage to the motor assembly  46  is increased from 24 V to 60 V using the buck boost power management section  62  in such an example for use by the motor assembly  46 . The buck boost power management section  62  may utilize a switch  90  and a diode  94  to increase the voltage in this manner. The buck boost power management section  62  is thus configured to adjust the voltage upward in some examples. 
     Referring now to  FIG. 3  with continuing reference to  FIG. 2 , an example method  100  of adjusting power includes a step  104  of selecting desired motor assembly  46 . The selection is based on the available spatial envelope for the motor assembly  46  within the gas turbine engine  10  in one example. In another example, the selection is based on the cost of the motor assembly  46 . 
     At step  108 , the method  100  sends power to the motor controller  58  from the power supply  54 , which supplies power at 120 V in this example 
     At step  112 , the voltage of the power is adjusted using the power management section  62  of the motor controller  58 . The voltage is adjusted to a level appropriate for use with the motor assembly  46  selected in the step  104 . In some examples, the voltage is adjusted downward. In other examples, the voltage is adjusted upwards the adjustments to the voltage are greater than 10% in this example. 
     At step  116 , the adjusted power from step  112  is communicated from the power converter  58  to the motor assembly  46  selected in the step  104 . The motor assembly  46  powers the valve  50 , for example. 
     Features of the disclosed examples include adjusting the voltage of power provided by a bus to match the voltage requirements of a desired motor assembly. The motor assembly is selected based on the spatial envelope available for mounting the motor or based on the availability of the motor assembly, for example. 
     Although a preferred embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.