Patent Application
20160052642
The present invention generally relates to health management systems and methods for aircrafts with electric drive taxi systems.
Some aircrafts now include electric drive taxi systems to replace or augment the main aircraft engines while the aircraft is on the ground taxiing. Many of these electric drive systems may use controllers which control and monitor current and voltage supplied to electric motors, which rotate the wheels on landing gear to move the aircraft, and may monitor other operating parameters as well. The monitored parameters may present an opportunity for performing real-time and ongoing diagnostic and prognostic operations onboard the aircraft. These operations may diagnose immediate maintenance and operational problems and/or identify when components of the electric drive taxi-system may need service.
While past systems may monitor landing gear component health, the components may not include components of an electric drive taxi system.
As can be seen, there may be an ongoing need for diagnostic and prognostic maintenance monitoring of electric drive taxi systems.
In one aspect of the present invention, an aircraft electric taxi health management system, comprises a pilot interface unit configured to accept taxi drive commands, and generate a first torque command and a second torque command as a function of the taxi drive commands; a first electric motor drivingly connected to at least one wheel on a first landing gear assembly, and including a first motor current and a first motor voltage; a second electric motor drivingly connected to at least one wheel on a second landing gear assembly, and including a second motor current and a second motor voltage; a first motor controller configured to electrically drive the first electric motor as a function of the first torque command, monitor the first motor current and the first motor voltage of the first electric motor, and generate a first motor torque signal as a function of the first motor current and the first motor voltage; a second motor controller configured to electrically drive the second electric motor as a function of the second torque command, monitor the second motor current and the second motor voltage of the second electric motor, and generate a second motor torque signal as a function of the second motor current and the second motor voltage; and a health management controller configured to compare first torque command and the first motor torque signal, and the second torque command and the second motor torque signal, and generate electric taxi system maintenance signals based on the comparison.
In another aspect of the present invention, an aircraft electric taxi health management method, comprises accepting taxi drive commands through a pilot interface unit; generating a first torque command and a second torque command as a function of the taxi drive commands; driving a first electric motor with a first motor controller based on the first torque command; driving a second electric motor with a second motor controller based on the second torque command; monitoring a first motor current and a first electric motor voltage of the first electric motor, and generating first motor signals as a function of the first motor current and the first motor voltage; monitoring a second motor current and a second electric motor voltage of the second electric motor, and generating second motor signals as a function of the second motor current and the second motor voltage; and comparing the first motor signals to the second motor signals; and generating electric taxi system maintenance signals based on the comparison.
In yet another aspect of the present invention, an aircraft with an electric taxi system, comprises a pilot interface unit configured to accept taxi drive commands, and generate a first torque command and a second torque command as a function of the taxi drive commands; a first landing gear assembly including a first electric motor drivingly connected to at least one wheel, the first electric motor including a first motor current and a first motor voltage; a second landing gear assembly including a second electric motor drivingly connected to at least one wheel, the second electric motor including a second motor current and a second motor voltage; an auxiliary power unit selectively electrically connected to a first electric motor controller and the a second electric motor controller; the first motor controller configured to electrically drive the first electric motor as a function of the first torque command, monitor a first motor current and a first motor voltage of the first electric motor, and generate first motor signals as a function of the first motor current and the first motor voltage; the second motor controller configured to electrically drive the second electric motor as a function of the second torque command, monitor a second motor current and a second motor voltage of the second electric motor, and generate second motor signals as a function of the second motor current and the second motor voltage; and a health management controller configured to compare the first motor signals to the second motor signals; and generate electric taxi system maintenance signals based on the comparison.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.
The present invention generally provides a health management system and method for an aircraft with an electric drive taxi system. In general, aircraft with electric drive systems may use controllers which control and monitor current and voltage supplied to electric motors, which rotate the wheels on landing gear to move the aircraft, and may monitor other operating parameters as well. The monitored parameters may present an opportunity for performing real-time and ongoing diagnostic and prognostic operations onboard the aircraft. These operations may diagnose immediate maintenance and operational problems and/or identify when components of the electric drive taxi-system may need service.
Referring now to
The first motor 132 and the second motor 134 may include any electric motor suitable for an aircraft 101 electric drive taxi system as is known in the art. The motors 132, 134 may be, for example, AC permanent magnet motors.
The aircraft 101 may include an auxiliary power unit (APU) assembly 102 which may include an APU power source 104 drivingly connected to an APU starter-generator 108 through an APU gear-box 106, and a mechanical connection 110. The APU starter-generator 108 may be selectively electrically connected to and may selectively provide electric power to the first motor controller 128, and the second motor controller 130 to move the aircraft 101 along the ground during taxi and landing operations. The APU 102 may also power other systems on the aircraft during flight and ground operations as would be known in the art.
Power from the APU starter generator 108 may flow through a first primary distribution panel (PDP) 114 and a second primary distribution panel (PDP) 116 to a first AC/DC converter 124 and a second AC/DC converter 126 respectively. Both the first PDP 114 and the second PDP 116 may include an AC power bus 118, 120. The AC power buses 118, 120 may be about 115 Vac and may be selectively electrically connected to the APU starter generator 108 and the AC/DC converters 124, 126 through switches 122 and other electrical connectors 157. In general, electrical power connections in the schematic of
The first motor controller 128 and the second motor controller 130 may be electrically connected to and provide current to the first motor 132 and the second motor 134 respectively, in a manner that causes the first motor 132 and the second motor 134 to generate torque and operate at a speed matching the commands from the HM controller 150. For example, the first and second motor controller 128, 130 may include inverter assemblies (not shown) which provide current at a frequency and amplitude which will result in the desired torque and speed. The first and second motor controllers 128, 130 may be communicatively connected through communication links 156 to the pilot interface unit 112 to receive torque commands, and to the HM controller 150. In general, communication links 156 are represented by lines with hatch marks in
The first and second motor controllers 128, 130 may be operably connected to the first and second motors 132, 134, to monitor the first motor current, the first motor voltage, the second motor current, and the second motor voltage respectively. The first and second motor controllers 128, 130 may include one or more processors and memory components (not shown) as is known in the art. The first motor controller 128 may generate first motor signals as a function of the first motor current and first motor voltage. The second motor controller 130 may generate second motor signals as a function of second motor current and second motor voltage respectively. The first and second motor controllers 128, 130 may be communicatively connected to motor sensors 160 which may include motor temperature sensors 162. The motor temperature sensors 162 may be configured to generate a motor temperature sensor signal indicative of the temperature of a component of, or an area of the first or second motor 132, 134.
The first landing gear assembly 136 may include a first main gear load sensor 142 and a first brake temperature sensor 146. The second landing gear assembly 138 may include a second main gear loading sensor 144, and a second brake temperature sensor 148. The first and second main gear load sensors 142, 144 may be configured to generate a first main gear load signal and a second main gear load signal respectively, the main gear load signals indicative of the weight load on the main gear of the landing assemblies 136, 138. Main gear load sensors 142, 144 are known in the art, and may, for example, include a strain gauge. The first and second main gear load sensors 142, 144, may be communicatively connected to the HM controller 150.
The first and second brake temperature sensors 146, 148 may be configured to generate first and second brake temperature signals indicative of the temperature of a component of the braking system of the first and second landing gear assemblies 136, 138 respectively. For, example, the first and second brake temperature signals may be indicative of the temperature of a brake caliper (not shown) on a brake pad assembly (not shown). The first and second brake temperature sensors 146, 148 may be any brake temperature sensors known in the art. The first and second brake temperature sensors 146, 148 may be communicatively connected to the HM controller 150.
The HM system 100 may include a heading determination system 152 configured to determine the heading of the aircraft 101. Aircraft heading determination systems 152 are known in the art, and may include, in non-limiting examples, a GPS system, an inertial navigation system (INS), attitude and heading reference system (AHRS), and/or a smart map system. The heading determination system 152 may be located onboard the aircraft 101, and/or located remotely as is known in the art. The heading determination system 152 may be communicatively connected to the HM controller 150.
The HM system 100 may include a nose gear angle sensor 154 configured to generate a nose gear angle signal indicative of the steering angle of a nose gear of the aircraft 101. Nose gear angle sensors 154 are known in the art. The nose gear angle signal may be indicative of the heading of the aircraft. The nose gear angle sensor 154 may be communicatively connected to the HM controller 150.
The pilot interface unit 112 may be configured to allow an operator (pilot) to enter a desired aircraft speed and desired heading commands. The pilot interface unit 112 may generate first torque, first speed, second torque, second speed, and tiller commands as a function of the desired speed and heading commands entered. The pilot interface unit 112 may be dedicated to an electric taxi drive system, or may be an interface that allows control of multiple systems. The pilot interface unit 112 may generate a tiller angle signal as a function of the heading commands entered. The pilot interface unit 112 may be communicatively connected to the HM controller 150.
The HM controller 150 may include a processor 151 and a memory component 153. The processor 151 may include microprocessors or other processors as known in the art. In some embodiments the processor 151 may include multiple processors. The HM controller 150 may execute instructions, as described below and in relation to
Such instructions may be read into or incorporated into a computer readable medium, such as the memory component 153, or provided external to processor 151. The instructions may include multiple lines or divisions of code. The lines or divisions of code may not be consecutive order, and may not be located in the same section of code. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions as described above, below, or in relation to the drawings.
The term “computer-readable medium” as used herein refers to any non-transitory medium or combination of media that participates in providing instructions to the processor 151 for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks. Volatile media includes dynamic memory. Transmission media includes coaxial cables, copper wire and fiber optics.
Although shown as one physical unit, the HM controller 150 may include multiple units, or be part of a larger controller unit, as is known in the art.
The HM controller 150 may include an e-taxi performance model 159 which may predict the performance of the electric drive taxi system and components of the electric drive taxi system as a function of operating parameters. The e-taxi performance model 159, may include multiple motor current prediction models (shown in relation to
The HM controller 150 may include a load determination model 158 which may estimate the load on the first motor 132 and the second motor 134 as a function of operating parameters and other variables. For example, operating parameters may include fuel consumption of the APU power source 104, aircraft 101 weight, and steering parameters; and other variables may include the number of passengers on the aircraft 101, and the weight and distribution of cargo. Load determination model 158 may include any model for estimating the load on the first motor 132 and the second motor 134 known in the art. Although illustrated separately from the processor 151 and the memory component 153, the e-taxi performance model 159, and the load determination model 158 may include parts of or the whole of the processor 151 and the memory component 153.
Referring now to
The method 200 may begin at 214 by determining if equal torque and equal speed are expected from the first motor 132 and the second motor 134. In an embodiment where the first landing gear assembly 136 and the first motor 132 are located on the right side of the aircraft 101, and the second landing gear assembly 138 and the second motor 134 are located on the left side of the aircraft 101, generally, if the aircraft 101 is traveling in a straight path, it may be expected that the tires 140 on both sides will operate in similar conditions. If the tires 140 are operating in similar conditions, it may be expected that the first motor 132 and the second motor 134 will be required to generate equal torque and operate at equal speeds. The HM controller 150 may determine that the aircraft 101 is traveling in a straight path through the heading determination system 152, the nose gear angle signal, or the tiller angle as communicated from the pilot interface unit 112. If the HM controller 150 determines that equal torque and equal speed may be expected from the first motor 132 and the second motor 134, an initial health check may be performed at 213. The health check method may be any method of checking that the motors 132, 134 are functioning in a manner that the HM system 100 will function properly.
Referring now to
After the maintenance warning associated with the RPL1st being greater than the RPL threshold or if the RPL1st is not greater than the RPL threshold, the second motor 134 torque may be determined as a function of the second motor current and the second motor voltage for a time period (step 312). Second motor ripple (RPL2nd) may be determined as a function of the second motor torque by the HM controller 150, as is known in the art (step 314), and compared to a ripple threshold (RPL threshold) (step 316). The time period may be any time period equal to or greater than that needed to determine the RPL2nd. If RPL2nd is greater than the RPL threshold, the HM controller 150 may generate a maintenance warning (step 318) and the method ends (step 324). If RPL2nd is not greater than the RPL threshold, the HM controller 150 may check if both RPL1st and RPL2nd are not greater than the RPL, (step 320) and if both RPL1st and RPL2nd are not greater than the RPL, the HM controller 150 will determine that the motors 132, 134 are functioning in a manner that the HM system 100 will function properly (step 322). The method will then end (step 324).
Referring back to
The HM controller 150 may determine if the running average of the difference between the first motor torque and the second motor torque exceeds a predetermined limit (block 232). The predetermined limit may be stored in a limit table (block 234). If the difference between the first motor torque and the second motor torque exceeds the predetermined limit, a maintenance flag may be set (block 236). The maintenance flag may be a stored flag in a memory section to be accessed by maintenance and service personnel, may be a warning which is displayed to the flight deck or other personnel, may be an audible alarm, or any other form of maintenance flag as would be known in the art.
The HM controller 150 may determine if the running average of the difference between the first motor speed and the second motor speed exceeds a predetermined limit (block 232). The predetermined limit may be stored in a limit table (block 234). If the difference between the first motor speed and the second motor speed exceeds the predetermined limit, a maintenance flag may be set (block 236) as described above.
The HM Controller 150 may include fault condition reasoner logic (block 240) to further analyze possible problems in the electric taxi system (block 238) as a function of condition indicators (242), when a maintenance flag is set, or in response to the condition indicators (242). Condition indicators (242) may be any operating parameter which may be used in pre-programmed logic to determine what fault conditions may be causing a difference between the first and second motor torque or speed to exceed the predetermined limit. For example, the condition indicators (242) may include the first main gear load signal, the second main gear load signal, the first brake temperature signal, the second brake temperature signal, the flight deck commanded (block 216) first motor torque (block 218), and second motor torque (block 220), the calculated first motor torque and speed (block 224), and the calculated second motor torque and speed (block 226). In other embodiments, other electric taxi system operating parameters may be included in the condition indicators (242) as would be known in the art. The HM controller 150 may generate maintenance advice as a function of the condition indicators (244) and the fault condition reasoner logic (block 240). In one example, the HM controller 150 may compare the first commanded torque (block 218) with the first motor torque (block 224) and generate electric taxi system maintenance signals as a function of the comparison. In another example, the HM controller 150 may compare the second commanded torque (block 220) with the second motor torque (block 226) and generate electric taxi system maintenance signals as a function of the comparison.
The fault condition reasoner logic may be in the form of tables, algorithms, models, state machines, or other methods of determining faults and providing maintenance advice as is known in the art. Non-limiting examples may be methods of determining if tires are properly inflated, methods of determining brake pad wear, methods of preventing skid, methods of controlling traction, methods of determining side loading, methods of determining weight and balance, and methods of determining wear or damage to the first motor 132 or the second motor 134 components. Exemplary methods which may be included in the fault reasoner logic are described in relation to
Referring now to
The first drive wheel torque (DWT1st) may be determined as a function of the first motor current as is known in the art (step 408). The first main gear load (MGL1st) may be determined from the first main gear load signal (step 410). A first windage (windage1st) may be a force the first motor torque must overcome created on the aircraft 101 by friction from air, and may be a function of aircraft 101 characteristics and weight, and environmental conditions such as wind speed and ground condition. The windage1st may be calculated as is known in the art (step 412). A first breakaway (breakaway1st) may be the friction force the first motor torque must overcome before the first wheel may begin turning. The breakaway may be calculated as is known in the art (step 414). The first motor speed (RPM1st) may be calculated as a function of the first motor current, the first motor voltage, the first windage, and the first breakaway as is known in the art (step 416).
The first tire inflation (TI1st) may be calculated as a function of DWT1st, MGL1st, windage1st, and breakaway (step 418). The second tire inflation (TI2nd) may be calculated similarly to the TI1st (steps 420-430). For example, the TI1st and TI2nd may be expressed as follows:
TIX=f(DWTX,MGLX,RPMX) Equation 1
where DWT is the drive wheel torque, MGL is the second main gear load, RPM is the second motor speed, and the subscript X designates first or second.
A relative TI1st and TI2nd may be calculated as a function of TI1st and TI2nd. For example, the relative TI1st and TI2nd may be calculated per the equation below:
Relative TIX=TIX/(TI1st+TI2nd) Equation 2
If both the relative TI1st and the relative TI2nd are in an acceptable range (steps 432 and 434), the inflation of both tires 140 is acceptable (step 440). If either the relative TI1st and the relative TI2nd are not in the acceptable range then the HM controller 150 may issue maintenance advice including a specific maintenance warning with information on which side tires 140 may not have acceptable tire inflation (step 438). The method 400 then ends (step 440).
Referring now to
The method starts (step 502) and the DWT1st, MGL1st, windage1st, breakaway1st, RPM1st, and NSA may be determined similarly to the method 400 to check tire inflation described above in relation to
SLF
X
=f(DWTX,RPMX,MGLX,sin(NSA)) Equation 3
where SLFx is the side load factor, DWTx is the drive wheel torque, RPMx is the motor speed, MGLx is the main gear load, NSA is the nosegear steering anglem and the subscript x refers to which landing gear the side load factor is being calculated on (first or second).
The SLF1st may be compared with the relative TI1st which may be determined similarly to the method 400 described above in relation to
The second side load factor (SLF2nd) may be determined in a similar manner as the SLF1st (step 524) and compared to the relative TI2nd in a similar manner (step 526). If the difference between the SLF2nd and the relative TI2nd is determined to be in a predetermined acceptable range, the SLF2nd may be considered to be acceptable (step 528). If the difference between the SLF2nd and the relative TI2nd is determined not to be in a predetermined acceptable range, the HM controller 500 may generate a maintenance warning in any of the embodiments previously in relation to
Referring now to
A pilot or other operator may enter vehicle control commands from the flight deck of the aircraft 101 through the pilot interface unit 112 which may be translated into first motor toque commands and second motor torque commands (block 602). The first and second motor current and voltage may be monitored by the first and second motor controllers 128, 130 respectively (block 604, 618). The first and second motor controllers 128, 130 may calculate the first motor speed as a function of the first motor current and voltage; and the second motor speed as a function of the second motor current and voltage, as described above in reference to
The HM controller 150 may perform a running average of the first motor speed and the second motor speed (block 608, 622) and determine the first motor acceleration (dVel1st/dt) and the second motor acceleration (dVel2ND/dt).
In order to maintain traction control of the first wheel, the HM controller 150 may compare the dVel1st/dt with a traction control predetermined acceleration limit (ACCthreshold-trac) (block 610) and if dVel1st/dt is greater than the ACCthreshold-trac, generate a reduce drive torque signal (block 612). The reduce drive torque signal may trigger a flight deck warning, for example in the form of a visual or audio signal, or a modification of the first motor torque commands. A modification of the first motor torque commands may assist the first wheel in regaining or maintaining traction control. Similarly, in order to maintain traction control of the second wheel, the HM controller 150 may compare the dVel2nd/dt with the ACCthreshold-trac (block 624) and if dVel2nd/dt is greater than the ACCthreshold-trac, generate a reduce drive torque signal (block 626). The reduce drive torque signal may trigger a flight deck warning or a modification of the second motor torque commands. A modification of the second motor torque commands may assist the second wheel in regaining or maintaining traction control.
In order to prevent skidding of the first wheel, the HM controller 150 may compare the dVel1st/dt with an anti-skid predetermined acceleration limit (ACCthreshold-skid) (block 614) and if dVel1st/dt is less than the ACCthreshold-skid, generate a reduce braking torque signal (block 616). The reduce braking torque signal may trigger a flight deck warning, for example in the form of a visual or audio signal, or a modification of a first braking command. A modification of the first braking command may assist in preventing, limiting, or stopping skidding of the first wheel. Similarly, in order to prevent skidding of the second wheel, the HM controller 150 may compare the dVel2nd/dt with the ACCthreshold-skid (block 628) and if dVel2nd/dt is less than the predetermined ACCthreshold-skid, generate a reduced braking torque signal (block 630). The reduce braking torque signal may trigger a flight deck warning or a modification of a second braking command. A modification of the second braking command may assist in preventing, limiting, or stopping skidding of the second wheel.
Referring now to
During mechanical braking upon landing of the aircraft 101, the aircraft 101 kinetic energy may be counteracted by reverse engine thrust and heating of the brake rotors, pads, and calipers. As the brake pads wear, their thermal capacity may be reduced and a heat path length to the calipers may be reduced, potentially resulting in a faster increase in the temperature of the calipers and a faster increase in the first brake temperature (BT) signal and/or the second BT signal. A trend showing that the rate at which the first BT signal and/or the second BT signal increases is increasing, may be related to brake pad thickness and wear.
The method 700 starts (step 702) and the rate of increase in the first brake caliper (d(BTst)/dt) may be determined as a function of the first BT signal (BT Signal1st) (step 704) by the HM controller 150. The MGL1st may be determined as a function of the first main gear load signal (step 706) by the HM controller 150. First brake pad wear (BP1st) may be determined as a function of the d(BT1st)/dt and the MGL1st (step 708) by the HM controller 150. For example, BP1st may be expressed as follows:
BP
X
=f(d(BTX)/dt,MGLX) Equation 4
where BPX is brake pad wear, d(BTX)/dt is the rate of change of the BT signal, MGLX is the load on the main gear of the landing assembly, and the subscript X indicates the side (first or second).
The HM controller 150 may compare the BP1st with one or more predetermined threshold values and as a result of the comparison determine if the BP1st is in an acceptable range (step 710). If the BP1st is not in an acceptable range the HM controller 150 may generate a maintenance warning (712). The maintenance warning may be stored, and/or displayed or in other ways communicated to the flight deck and/or other personnel.
The HM controller 150 may determine the second brake pad wear (BP2nd) (steps 714-718), determine if BP2nd is in an acceptable range (step 720), and if not generate a maintenance warning (step 722), in a similar way as BP1st. The method 700 may then end (step 724).
Referring now to
WBX=MGLX/(MGL1st+MGL2nd) Equation 5
where WBX is weight and balance, MGLX is the load on the main gear of the landing assembly, and the subscript X indicates the side (first or second), subscript 1st indicates the first side, and subscript 2nd indicates the second side.
Ideally, the WB1st equals 0.5. The HM controller 150 may determine if the WB1st is in an acceptable range (step 810), and if the WB1st is not in an acceptable range, the HM controller 150 may generate a warning (step 812) which may be stored in the HM controller memory and/or be communicated through display or audio means to the pilot or other personnel. The HM controller 150 may determine if the WB1st is in a danger range (step 814), and if the WB1st is in a danger range, the HM controller 150 may generate a flight deck warning which may immediately inform personnel in the flight deck that a serious weight balance issue exists (step 816). Although determining WB1st may determine any weight balance problem, the HM controller 150 may repeat these steps for the second side of the aircraft 101 (steps 818-826) as a failsafe and then end (828).
Referring now to
Components of the HM system 100 illustrated in
The load determination module 158 in the HM controller may determine the load (block 902) on the first and second motors 132, 134. In addition to monitoring the first and second motor current and voltage (block 220, 222), the first and second motor controllers 128, 130 (or alternatively, the HM controller 150) may monitor the temperature of the first and second motors 132, 134 (block 906, 908). The temperatures of the motors 132, 134 may be monitored by thermocouples in the windings or frame, or in any way known in the art.
The HM controller 150 may calculate first motor CIs 982 as a function of the first motor load, the first motor current, the first motor voltage, the first motor speed, the first motor torque, the first motor commanded torque, and the first motor desired speed, and may utilize an electric current predictor model 930 (shown in
Referring now to
In the case of motors 132, 134, supply voltage variation may produce motor current characteristics similar to symptoms of faults that the CIs 982 may be designed to capture. Residual motor currents 942 may be the difference between the monitored motor currents and a model predicted current, and may decouple the effect on motor current characteristics due to supply voltage variations from the effect due to actual faults. The e-taxi performance model 156 may include the electric current predictor model 930. The current predictor model 930 may include one or more models 938. The models 938 may include any type of current prediction model known in the art, including, for example, a first principle model and/or an empirical model. The models 938 may include models which predict motor current more accurately when the motor loads are within a predetermined range. Multiple models 938 may be included in the electric current predictor model 930, and may each predict motor current more accurately within different predetermined load ranges, but together may cover a broad load range.
Motor load variation may also produce current characteristics similar to symptoms of faults that the CIs 982 may be designed to capture. Motor load variation may produce non-stationary voltage and current signals. Signal processing the steady-state and transient current signals separately may decouple the effect on motor current characteristics due to motor load variations from the effect due to actual faults. Signal segmentation technique may be used to separate the motor current and residual current signals into steady-state and the transient components. CIs 980 may be computed using different methods for steady-state and the transient monitored and residual current components. CIs 980 from steady-state signals may be computed using fast Fourier transform methods (FFT), whereas CIs 980 from transient signals may be computed based on multi-resolution analysis, such as wavelet or time-frequency analysis.
The flow chart of
The current predictor model 930 may generate a model predicted current signal 940 as a function of motor load 926, speed 932, and voltage 934 signals. The current prediction model 930 may use any of multiple current prediction models 938 to generate the model predicted current signal 940 based on the load signal 926. The current predictor model 930 may, for example, include a table matching load signals 926 with appropriate models 938. The model predicted current signal 940 may be compared with the monitored current signal 936 and a residual current signal 942 generated.
A signal segmentation module 944 may separate the residual current signal 942, and the monitored current signal 936 into monitored and residual stationary current signals 946, and monitored and residual non-stationary current signals 948; as a function of the voltage signal 934. A harmonics separation module 950 may separate the monitored stationary current signal 946, the monitored non-stationary current signal 948, the residual stationary current signal 946, and the residual non-stationary current signal 948, into fundamental 956, 958 and harmonic 960, 962 component signals. A CI computation module 964 may compute Peak, RMS, Total Harmonic Distortion, and/or Symmetrical Component CIs 980 from the monitored stationary fundamental current signal 958, the monitored stationary harmonic current signal 962, the monitored non-stationary fundamental current signal 958, the monitored non-stationary current signal 962, the residual stationary fundamental current signal 956, the residual stationary harmonic current signal 960, the residual non-stationary fundamental current signal 956, and the residual non-stationary harmonics current signal 960.
A temperature monitoring module 968 may generate a CI 970 based on motor temperature signals 966. A control loop monitoring module may produce a CI 978 based upon a comparison of the desired motor torque and speed 972, and the actual motor torque and speed 974.
Referring now back to
A progression operator may analyze the CIs 982 and difference between the first and second CIs 982s to calculate trends in the periodic CI 982 and difference signals (block 916). Trend analysis of signals is known in the art. A diagnostic operator may analyze the CIs 982 and difference between the first and second CIs 982 to determine real time faults (block 918). For example, the diagnostic operator may compare CIs 982 or functions of the CIs 982 with predetermined limits and ranges. Diagnostic analysis of signals is known in the art. If real time faults are determined to exist, the HM controller 150 may generate maintenance flags and warnings (block 924).
CI 982 trend data associated with faults of the particular motors 132, 134 on the aircraft 101 may be stored in the HM controller 150. The HM controller 150 may determine relevant stored trend data (block 920) and compare this trend data with CIs 982 trend data from the progressive operator (block 922). Based on the comparison, the HM controller 150 may store or generate maintenance flags, information and/or messages (block 924).
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
