Patent Description:
Rotor dynamics refer to motions and forces generated by high speed rotating machinery as a result of rotor rotation. These generally unwanted vibrations and motions can induce stress, drive vibration into the structure supporting the machinery or engine, and may result in rubbing between the rotating and static structure. Typically, rotor dynamics are accounted for during a machine design process by a combination of geometrical design of the rotor and static structures, and sets of springs and dampers, usually placed near or integral to bearing mounts. However, vibration modes can still result at certain operating speeds that excite rotor dynamic motions in rotating machinery.

<CIT> discloses an electrical power arrangement wherein torque vibration from a first electrical machine may be determined and then balanced by utilizing a second electrical machine to introduce an anti-phase torque vibration.

<CIT> discloses a gas turbine power generation system having a power oscillation damping control system for improved electric power stability.

<CIT> discloses a method and damping device for damping a torsional oscillation in a rotating drive train.

According to a first aspect, there is provided a rotor dynamics adjustment system as claimed in claim <NUM>.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where the damping correction torque includes a phase, a magnitude, and a sign of one or more torques to diminish the dynamic motion of the rotor system.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where the rotor system is a spool of a gas turbine engine.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where the electric motor is directly coupled to the shaft.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where wherein the electric motor is coupled to the shaft through a geared interface.

In addition to one or more of the features described above, there is provided a gas turbine engine as claimed in claim <NUM>.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where the electric motor-generator operable as a starter motor and as a generator to produce electric power.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where the rotor system is a low speed spool, and further including a high speed spool having a high pressure compressor, a high pressure turbine, and a second shaft concentrically arranged with respect to the shaft of the low speed spool.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include a second electric motor operably coupled to the second shaft, where the electric motor and the second electric motor are independently controlled to each supply a supplemental motive force and fuel combustion in the combustor section provides a primary motive force for the low speed spool and the high speed spool.

According to a second aspect, there is provided a method of adjusting rotor dynamics as claimed in claim <NUM>.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where the rotor system includes at least one compressor section and at least one turbine section operably coupled to a shaft, and the electric motor is directly coupled to the shaft.

In addition to one or more of the features described above or below, or as an alternative, further embodiments may include where the rotor system includes at least one compressor section and at least one turbine section operably coupled to a shaft, and the electric motor is coupled to the shaft through a geared interface.

A technical effect of the apparatus, systems and methods is achieved by using dynamic torque and power capability of an electric motor operably coupled to a shaft of a rotating machine to damp out or excite rotor dynamic motions as described herein.

In one disclosed embodiment, the engine <NUM> bypass ratio is greater than about ten (<NUM>:<NUM>), the fan diameter is significantly larger than that of the low pressure compressor <NUM>, and the low pressure turbine <NUM> has a pressure ratio that is greater than about five (<NUM>:<NUM>). The geared architecture <NUM> may be an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>:<NUM>. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

The fan section <NUM> of the engine <NUM> is designed for a particular flight condition--typically cruise at about <NUM> Mach and about <NUM>,<NUM> feet (<NUM>,<NUM> meters).

While the example of <FIG> illustrates one example of the gas turbine engine <NUM>, it will be understood that any number of spools, inclusion or omission of the gear system <NUM>, and/or other elements and subsystems are contemplated. Further, rotor systems described herein can be used in a variety of applications and need not be limited to gas turbine engines for aircraft applications. For example, rotor systems can be included in power generation systems, which may be ground-based as a fixed position or mobile system, and other such applications.

Referring now to the drawings, <FIG> illustrates a rotor system <NUM> that includes at least one compressor section <NUM> and at least one turbine section <NUM> operably coupled to a shaft <NUM>. The rotor system <NUM> can be a spool of the gas turbine engine <NUM> of <FIG>, such as the low speed spool <NUM> or the high speed spool <NUM>. For example, when embodied as the low speed spool <NUM>, the at least one compressor section <NUM> can be equivalent to the low pressure compressor <NUM>, the shaft <NUM> can be equivalent to the inner shaft <NUM>, and the at least one turbine section <NUM> can be equivalent to the low pressure turbine <NUM> of <FIG>. When embodied as the high speed spool <NUM>, the at least one compressor section <NUM> can be equivalent to the high pressure compressor <NUM>, the shaft <NUM> can be equivalent to the outer shaft <NUM>, and the at least one turbine section <NUM> can be equivalent to the high pressure turbine <NUM> of <FIG>.

In the example of <FIG>, a rotor dynamics adjustment system <NUM> is operably coupled to the rotor system <NUM>. The rotor dynamics adjustment system <NUM> includes an electric motor <NUM> directly coupled to the shaft <NUM>. The rotor dynamics adjustment system <NUM> also includes drive electronics <NUM> operable to control current to the electric motor <NUM> to adjust the speed and/or torque of the electric motor <NUM>. The electric motor <NUM> can be a direct current (DC) motor or an alternating current (AC) motor including conventional motor components, such as a motor rotor and motor stator, including a plurality of motor windings and/or permanent magnets. The drive electronics <NUM> can also include conventional motor current control electronics, such as filters, switching components, rectifiers, inverters, and the like. The electric motor <NUM> is a motor-generator operable in a generator mode to increase a load on the rotor system <NUM> and in a motoring mode to decrease the load of the rotor system <NUM>. Thus, the drive electronics <NUM> may include power regulating circuitry and/or power converters to regulate electric power produced by the electric motor <NUM> in generator mode. For example, the electric motor <NUM> can act as a variable frequency generator in generator mode due to speed fluctuations of rotation of the shaft <NUM>, which may be primarily driven by the at least one turbine section <NUM>. In some embodiments, the electric motor <NUM> may be operable as a starter motor to partially or completely power rotation of the shaft <NUM> in a starting mode of operation (e.g., to start the gas turbine engine <NUM> of <FIG>). Other uses and functions for the electric motor <NUM> are contemplated.

A controller <NUM> of the rotor dynamics adjustment system <NUM> can monitor one or more rotor system sensors <NUM> while the rotor system <NUM> is rotating. The rotor system sensors <NUM> can be any type or combination of sensors operable to measure aspects of the motion of the rotor system <NUM>. For example, the rotor system sensors <NUM> can include one or more accelerometers, speed sensors, torque sensors, and the like. The controller <NUM> can control a speed and torque of the electric motor <NUM> through the drive electronics <NUM>. The controller <NUM> may also control other system aspects, such as controlling operation of the gas turbine engine <NUM> of <FIG>. In embodiments, the controller <NUM> can include a processing system <NUM>, a memory system <NUM>, and an input/output interface <NUM>. The processing system <NUM> can include any type or combination of central processing unit (CPU), including one or more of: a microprocessor, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like. The memory system <NUM> can store data and instructions that are executed by the processing system <NUM>. In embodiments, the memory system <NUM> may include random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic, or any other computer readable medium onto which is stored data and algorithms in a non-transitory form. The input/output interface <NUM> is configured to collect sensor data from the one or more rotor system sensors <NUM> and interface with the drive electronics <NUM> and/or other systems (not depicted).

The controller <NUM> is operable to characterize a dynamic motion of the rotor system <NUM> based on the sensor data from the one or more rotor system sensors <NUM>. For example, the controller <NUM> may monitor a rotational speed of the shaft <NUM> and a vibrational amplitude and phase of the rotor system <NUM>. The controller <NUM> can also monitor one or more torques on the shaft <NUM>, for example, through direct torque measurements from the one or more rotor system sensors <NUM> or derived torques based on system models and/or known relationships based on mass, acceleration, and/or geometric configuration of the rotor system <NUM>. The controller <NUM> is configured to determine a damping correction torque to diminish the dynamic motion of the rotor system <NUM> and command the electric motor <NUM> to apply the damping correction torque to the rotor system <NUM>. The damping correction torque can include a phase, a magnitude, and a sign of one or more torques to diminish the dynamic motion of the rotor system <NUM>. The controller <NUM> is configured to drive the electric motor <NUM> to apply one or more torque perturbations to a steady state load of the rotor system <NUM> to modify the dynamic motion of the rotor system <NUM>. Further, the controller <NUM> is configured to operate the electric motor <NUM> in a generator mode to increase a load on the rotor system <NUM> and in a motoring mode to decrease the load of the rotor system <NUM>. By damping out or exciting rotor dynamic motions through the electric motor <NUM>, the dynamic motions of the rotor system <NUM> can be controlled.

The general form of the mathematical representation of these rotor systems, such as rotor system <NUM>, can be derived from the geometry of the respective system and is well understood. As used herein, "rotor systems" refer to the rotor and all of the static structure which contributes to the relevant dynamics of an engine. From these representations, robust control laws for a controller can be formatted using standard procedures. One such procedure is to excite the rotor system <NUM>, for example with the motor <NUM> and controller <NUM>, and measure the rotor response. The excitation can take several forms, such as: sinusoidal frequency and amplitude sweeps, ramps, stochastic disturbances, and others as is well known. The data so generated can then be used to identify the relevant dynamics of the engine geometry, most conveniently as separate vibrational modes often described in the form of eigenvectors and eigenvalues. Given this information, many standard mathematical techniques can be employed to formulate both linear and non-linear control laws. Note that this procedure need not be carried out on each engine unit, but may be more capable if done so depending on the geometrical uniformity of the manufacturing and assemble process.

Referring now to <FIG>, a schematic diagram of the rotor system <NUM> with a rotor dynamics adjustment system <NUM> is depicted as an alternate embodiment of the rotor dynamics adjustment system <NUM> of <FIG>. In the example of <FIG>, similar to <FIG>, the controller <NUM> is operable to measure motion of the rotor system <NUM> through one or more rotor system sensors <NUM> and command the drive electronics <NUM> to modify a speed and/or torque of the electric motor <NUM> to apply a damping correction torque to the rotor system <NUM>. Rather than the electric motor <NUM> being directly coupled to the shaft <NUM>, a rotor dynamics adjustment system <NUM> of <FIG> includes a geared interface <NUM> that operably couples the electric motor <NUM> to the shaft <NUM>. The geared interface <NUM> can include, for instance, a motor gear <NUM> coupled to a motor shaft <NUM> driven by the electric motor <NUM>. The geared interface <NUM> can also include a rotor gear <NUM> coupled to the shaft <NUM>. The motor gear <NUM> and the rotor gear <NUM> can each be beveled gears. The motor shaft <NUM> can be a tower shaft that enables the electric motor <NUM> to be separated at a greater distance from the rotor system <NUM> than in the rotor dynamics adjustment system <NUM> of <FIG>. Further separation of the electric motor <NUM> from the rotor system <NUM> can improve accessibility to the electric motor <NUM> for servicing and may reduce heating effects of the rotor system <NUM> on the electric motor <NUM> (e.g., due to fuel combustion). Damping correction torque computations by the controller <NUM> can be adjusted to compensate for effects of the geared interface <NUM>, such as gear backlash between the motor gear <NUM> and the rotor gear <NUM>.

<FIG> is a schematic diagram of a dual rotor system <NUM> with dynamic motion damping according to an embodiment. The dual rotor system <NUM> includes a first rotor system 402A and a second rotor system 402B, which may be an embodiment of the gas turbine engine <NUM> of <FIG>. For instance, the first rotor system 402A can be the low speed spool <NUM> of the gas turbine engine <NUM>, and the second rotor system 402B can be the high speed spool <NUM> of the gas turbine engine <NUM>. The first rotor system 402A can include a first compressor section 204A and a first turbine section 208A operably coupled to a first shaft 206A. The second rotor system 402B can include a second compressor section 204B and a second turbine section 208B operably coupled to a second shaft 206B, where the second shaft 206B is concentrically arranged with respect to the first shaft 206A. With respect to the gas turbine engine <NUM> of <FIG>, the first compressor section 204A can be equivalent to the low pressure compressor <NUM>, the first shaft 206A can be equivalent to the inner shaft <NUM>, and the first turbine section 208A can be equivalent to the low pressure turbine <NUM> of <FIG>. Similarly, the second compressor section 204B can be equivalent to the high pressure compressor <NUM>, the second shaft 206B can be equivalent to the outer shaft <NUM>, and the second turbine section 208B can be equivalent to the high pressure turbine <NUM> of <FIG>.

In the example of <FIG>, a rotor dynamics adjustment system <NUM> includes a first electric motor 212A driven by first drive electronics 214A and a second electric motor 212B driven by second drive electronics 214B. A first set of one or more rotor system sensors 218A may be associated with the first rotor system 402A, and a second set of one or more rotor system sensors 218B may be associated with the second rotor system 402B. A single instance of the controller <NUM> can be configured to independently control the first electric motor 212A responsive to sensor data from the first set of one or more rotor system sensors 218A, and separately control the second electric motor 212B responsive to sensor data from the second set of one or more rotor system sensors 218B. In other embodiments, the controller <NUM> is further subdivided as two or more separate controls, for instance, where a separate instance of the controller <NUM> is provided for each of the first rotor system 402A and the second rotor system 402B. The first electric motor 212A and the second electric motor 212B can be independently controlled to each supply a supplemental motive force to the respective shafts 206A, 206B, where fuel combustion in the combustor section <NUM> (<FIG>) can provide a primary motive force for the first rotor system 402A as the low speed spool <NUM> and for the second rotor system 402B as the high speed spool <NUM>.

In some embodiments, the first electric motor 212A is operably coupled to the first shaft 206A using a direct coupling, while the second electric motor 212B is operably coupled to the second shaft 206B using a geared interface <NUM>. Similar to <FIG>, the geared interface <NUM> can include, for instance, a motor gear <NUM> coupled to a motor shaft <NUM> driven by the second electric motor 212B and a rotor gear <NUM> coupled to the second shaft 206B. While the example of <FIG>, depicts the rotor dynamics adjustment system <NUM> with the first and second electric motor 212A, 212B in different configurations, it will be understood that both of the first and second electric motors 212A, 212B can be directly or indirectly coupled to corresponding first and second shafts 206A, 206B. Further, the first electric motor 212A may be indirectly coupled through a tower shaft to the first shaft 206A, while the second electric motor 212B is directly coupled to the second shaft 206B. Further, the coupling locations of the first and second electric motors 212A, 212B to the first and second shafts 206A, 206B can vary, and the coupling locations depicted in <FIG> are merely one example.

Referring now to <FIG> with continued reference to <FIG>, <FIG> is a flow chart illustrating a method <NUM> for adjusting rotor dynamics, in accordance with an embodiment. The method <NUM> may be performed, for example, by the rotor dynamics adjustment systems <NUM>, <NUM>, <NUM> of <FIG>. For purposes of explanation, the method <NUM> is described primarily with respect to the rotor dynamics adjustment system <NUM> of <FIG>; however, it will be understood that the method <NUM> can be performed on other configurations, such as the rotor dynamics adjustment systems <NUM>, <NUM> of <FIG> and <FIG>, as well as other configurations (not depicted).

At block <NUM>, a controller <NUM> monitors one or more rotor system sensors <NUM> of a rotor system <NUM> while the rotor system <NUM> is rotating. At block <NUM>, the controller <NUM> characterizes a dynamic motion of the rotor system <NUM> based on the sensor data from the one or more rotor system sensors <NUM>. At block <NUM>, the controller <NUM> determines a damping correction torque to diminish the dynamic motion of the rotor system <NUM>. The damping correction torque can include a phase, a magnitude, and a sign of one or more torques to diminish the dynamic motion of the rotor system <NUM>. At block <NUM>, the controller <NUM> commands an electric motor <NUM> operably coupled to the rotor system <NUM> to apply the damping correction torque to the rotor system <NUM>. The electric motor <NUM> applies one or more torque perturbations to a steady state load of the rotor system <NUM> to modify the dynamic motion of the rotor system <NUM>, for instance, to damp or excite the dynamic motion of the rotor system <NUM>.

Claim 1:
A rotor dynamics adjustment system (<NUM>; <NUM>; <NUM>) comprising:
a rotor system (<NUM>; 402A, 402B) comprising at least one compressor section (<NUM>; 204A, 204B) and at least one turbine section (<NUM>; 208A, 208B) operably coupled to a shaft (<NUM>; 206A, 206B);
one or more rotor system sensors (<NUM>; 218A, 218B) configured to collect a plurality of sensor data from the rotor system;
an electric motor (<NUM>; 212A, 212B) operably coupled to the rotor system; and
a controller (<NUM>) configured to:
monitor the one or more rotor system sensors while the rotor system is rotating;
characterize a dynamic motion of the rotor system based on the sensor data from the one or more rotor system sensors;
determine a damping correction torque to diminish the dynamic motion of the rotor system; and
command the electric motor to apply the damping correction torque to the rotor system,
characterised in that the controller is configured to command the electric motor (<NUM>; 212A, 212B) to apply one or more torque perturbations to modify the dynamic motion of the rotor system;
the electric motor (<NUM>; 212A, 212B) is a motor-generator;
the controller is configured to operate the electric motor-generator in a generator mode to increase a load on the rotor system (<NUM>; 402A, 402B) to apply the damping correction torque to the rotor system; and
the controller is configured to operate the electric motor-generator in a motoring mode to decrease the load of the rotor system by driving the electric motor-generator to apply the damping correction torque to the rotor system.