Method for managing power transfer between power generation mode and assist mode

Abstract

The invention relates to a method for managing the power transfer of a turbine engine between a power generation mode and an assist mode, the turbine engine having a high-pressure shaft driving a high-pressure electric machine and a low-pressure shaft driving a low-pressure electric machine, high-pressure power (PHP) being extracted from the high-pressure shaft and low-pressure power (PBP) being extracted from the low-pressure shaft, the power generation mode corresponds to a predetermined power sharing between the high voltage power and the low voltage power and the assist mode corresponds to a request for injecting additional power onto the high voltage shaft or the low voltage shaft, in which method the power generation mode corresponds to a predetermined power sharing between the high voltage power and the low voltage power, in order to achieve the requested additional power. When the extraction of high-voltage power or low-voltage power is interrupted and a high-voltage motor or a low-voltage motor respectively driving a high-voltage shaft or a low-voltage shaft whose extraction of high-voltage power or low-voltage power is interrupted enters a motor mode. Residual power extracted from the high-voltage shaft or the low-voltage shaft in the generator mode is adjusted according to high-voltage or low-voltage injection power output from the high-voltage motor or the low-voltage motor that has entered the motor mode.

Description

Technical Field

[0001] The present invention relates to the field of internal hybrid power for more electrified or even highly electrified aircraft turbine engines. Background Art

[0002] Climate change is a focus of numerous global legislative and regulatory bodies. Specifically, various carbon emission restriction measures have been, are being, or will be introduced by countries. Specifically, an ambitious standard applies to both new aircraft and those currently in service, requiring the implementation of technical solutions to bring them into compliance with current regulations. For many years, civil aviation has been committed to contributing to the fight against climate change.

[0003] Technological R & D work has made it possible to significantly improve the environmental performance of aircraft. The applicant has considered factors affecting all design and development stages in order to obtain aerospace components and materials with lower energy consumption, greater environmental friendliness, and a moderate environmental impact during integration and use in civil aviation, with the aim of improving the energy efficiency of these aircraft.

[0004] Therefore, the applicant is constantly striving to reduce its impact on the climate by using various methods and developing virtuous development and manufacturing processes that minimize greenhouse gas emissions, thereby reducing the environmental footprint of its activities.

[0005] This ongoing research and development work involves both new-generation aircraft turbine engines, the lightweighting of aircraft (especially through the materials used and lighter on-board equipment), the development of electric power technologies for propulsion, and aviation biofuels as an important complement to technological progress.

[0006] The hybrid power of the turbine engine is achieved by an electrical system that forms an interface between the mechanical shaft of the turbine engine and the aircraft's electrical grid.

[0007] This system must enable the start-up function of the turbine engine (HP and / or LP), the generation of controlled electrical power to supply propulsion and non-propulsion loads and injection, and the output of power from the shaft of the turbine engine in a controlled manner during operation in the auxiliary mode of the turbine engine. By controlling the voltage of the busbar (for the frequency and maximum amplitude of the AC voltage, and for the amplitude of the DC voltage), the balance between the power consumed by the load and the power generated by the available power sources is ensured, while complying with the system's limiting conditions.

[0008] More precisely, when the turbine engine requires assistance, the power source involved in regulating the generated voltage will stop generating power and enter the electric motor mode. This switch in the operating mode causes a sharp voltage fluctuation, which then moves away from the predefined voltage envelope ( Figure 5) This envelope defines limits that the turbomachine must not exceed, either transiently or in steady state, during normal operation 500 and abnormal operation (network problems, i.e. short circuits) 502.

[0009] To control this voltage and keep it within these envelopes, the known practice is to perform load shedding (e.g. non - priority loads) by temporarily reconfiguring the electrical system, or to supply the high - frequency (HF) part of the power to be generated using an external power source with a dynamic range greater than that of the turbomachine power supply (whether or not associated with temporary load shedding), or to oversize certain passive components of the electrical system (such as the capacitors of power electronics).

[0010] However, these solutions are not without drawbacks. Load shedding does not include any prediction of power consumption or grid behavior, while adding an external power source is entirely based on frequency sharing of the power generated between the turbomachine and this external power source, with the turbomachine supplying only the average power. Finally, over - sizing the system causes a mass penalty and is therefore hardly desirable for aerospace applications. Summary of the Invention

[0011] For this purpose, the present invention is based on the results of technical research and aims to significantly improve the performance of aircraft and thereby contribute to reducing the environmental impact of these aircraft. To this end, the main objective of the present invention is to limit the sharp voltage fluctuations when the turbomachine enters the auxiliary mode, predict sudden changes in available power, and without any on - board weight penalty, while meeting the quality constraints of the electrical grid.

[0012] These objectives are achieved by a method for managing the power transfer between a turbomachine in a power generation mode and an auxiliary mode, the turbomachine having a high - pressure shaft driving a high - voltage electric machine and a low - pressure shaft driving a low - voltage electric machine, high - pressure power being output from the high - pressure shaft and low - pressure power being output from the low - pressure shaft, the power generation mode corresponding to a predetermined power sharing between the high - pressure power and the low - pressure power, the auxiliary mode corresponding to a request to inject additional power into the high - pressure shaft or the low - pressure shaft, characterized in that, in order to achieve the requested additional power, when the high - pressure power or the low - pressure power output is interrupted and the high - voltage electric machine or the low - voltage electric machine respectively driving the high - pressure shaft or the low - pressure shaft with the interrupted output enters the motor mode, the remaining output power of the high - pressure shaft or the low - pressure shaft in the generator mode is adjusted based on the injected high - pressure power or low - pressure power from the high - voltage electric machine or the low - voltage electric machine that has entered the motor mode.

[0013] Thus, by sending the power requested by the power source entering the auxiliary mode to the power source in the power generation mode, the request can be predicted, voltage variations can be limited, and the transient response can be controlled while keeping the voltage within the defined envelopes.

[0014] Preferably, if the high-pressure or low-pressure motor has a different dynamic range, the injection of the requested additional power is accomplished by matching the dynamic range of the remaining output high-pressure or low-pressure power output.

[0015] The invention also relates to a turbomachine having: a high-pressure shaft and a low-pressure shaft, a high-pressure power being output from the high-pressure shaft and a low-pressure power being output from the low-pressure shaft; a control module that receives power setpoints from an ECU and a power converter associated with a high-pressure motor and a low-pressure motor respectively mounted on the high-pressure shaft and the low-pressure shaft; a power generation mode corresponding to a predetermined power sharing between the high-pressure power and the low-pressure power; and an auxiliary mode corresponding to injecting additional power into the high-pressure shaft or the low-pressure shaft, characterized in that, in order to achieve the requested additional power, the control module is configured such that: when the output of the high-pressure power or the low-pressure power is interrupted and the high-pressure motor or the low-pressure motor respectively driving the interrupted high-pressure shaft or low-pressure shaft is put into the motor mode, the remaining output power of the high-pressure shaft or the low-pressure shaft in the generator mode is adjusted based on the injected high-pressure or low-pressure power from the high-pressure motor or the low-pressure motor that has entered the motor mode.

[0016] Preferably, the control module further includes: an auxiliary module and a selection module, the auxiliary module being configured to add the injected high-pressure or low-pressure power to the remaining output high-pressure or low-pressure power, the selection module being configured to select the output power from the auxiliary module.

[0017] Preferably, each auxiliary module includes an adder and an adaptation module having transfer functions F1 and F2 for matching the dynamic range of the remaining output high-pressure power or low-pressure power according to the respective dynamic ranges of the high-pressure motor and the low-pressure motor.

[0018] According to the dynamic range of the motors, if the high-pressure and low-pressure motors have the same dynamic range, the transfer function is equal to 1; if the dynamic range of the motor entering the motor mode is slower than the dynamic range of the motor remaining in the generator mode, the transfer function is a phase delay; if the dynamic range of the motor entering the motor mode is faster than the dynamic range of the motor remaining in the generator mode, the transfer function is a phase advance function. Description of the Drawings

[0019] Other features and advantages of the invention will become apparent from the following description with reference to the drawings, which illustrate only exemplary embodiments of the invention without any limitation, and in which:

[0020] Figure 1 Figure 1 illustrates the architecture of an internal hybrid system of a turbomachine according to the invention,

[0021] ​​Figure 2 Figure 2 Details the innovative control module of the internal hybrid system of Figure 1 , and

[0022] Figure 3 Figure 3 Illustrates the output setpoint of the power associated with the request for assistance,

[0023] Figure 4 Figure 4 Shows the different steps of the method implemented in the internal hybrid system of Figure 1 , and

[0024] Figure 5 Figure 5 Shows an example of the voltage envelope applicable to the internal hybrid system of Figure 1 . DETAILED DESCRIPTION

[0025] When there is a request for assistance, the power source of the turbine engine that participates in regulating the generated voltage will stop operating and enter the electric motor mode to inject the necessary power, and provide the function of assisting the turbine engine. Since the remaining power sources have a certain response time, that is, the time it takes for them to reconfigure to supply the insufficient power, the generated voltage will drop significantly and exceed the set envelope limit, especially when the balance between the generated power and the consumed power is no longer maintained.

[0026] To solve this problem, the present invention proposes to act on the control modules of the remaining power sources after a request for assistance for the turbine engine to modify their behavior, so that the transient response of the generated voltage remains within a predefined envelope.

[0027] Figure 1 Illustrates an example of the architecture of the internal hybrid system of turbine engine 100, which is based on parallel-connected DC channels, typically the HP channel (corresponding to the high-pressure shaft 102 of the turbine engine) and the LP channel (corresponding to its low-pressure shaft 104). Each of these two DC channels is driven by electric motors 106 and 108, which are typically permanent magnet synchronous machines, and is associated with controlled AC-DC reversible power converters 110 and 112, which deliver DC voltage to the DC bus 114, and the DC bus is connected to the load 116 (propulsion or non-propulsion type) to be powered. The control of the reversible power converter is traditionally provided by the control module 118, which receives instructions from the controller of the turbine engine ECU (electronic control unit) 120, which controls the combustion engine, and thus has, in particular, the following functions: allocating the percentage of the electric motor's participation in power generation to optimize the operating point of the turbine engine.

[0028] ​​​​​​​​To this end, the ECU 120 will request the control module 118 to share the output power between the HP axis and the LP axis to supply the load 116, which consumes the power L of the network and generally exhibits variable dynamic range behavior, especially so-called active loads.

[0029] As Figure 2 shown, this predefined sharing of the output power between the HP axis and the LP axis is requested by the ECU. The ECU is initially, for example, in a power generation mode, in which 60% of the power L is output from the HP axis and 40% of the power L is output from the LP axis. To achieve the additional power required for the auxiliary request, the ECU can enter an auxiliary mode, in which the high-voltage power output from the HP axis is interrupted, the high-voltage motor enters the motor mode to inject high-voltage power, and then 100% of the power L is supplied by the LP axis, plus the load requested by the HP axis, as illustrated in this figure.

[0030] However, after entering the auxiliary mode, due to this instantaneous change in the power ratio, the transiently supplied power 130 deviates from the desired power 140. Therefore, the problem is to find a way to compensate for the difference between the transiently supplied power and the desired power by the remaining power sources, so as to keep the power generation voltage within a predefined envelope until reaching the steady state, without adding any external power sources.

[0031] More specifically, this power difference under transient conditions is expressed by the following formula (1):

[0032]

[0033] Therefore,

[0034]

[0035] where

[0036] C: Value of the power capacitor on the DC bus

[0037] Ps: Power of the power source

[0038] P1: Power of the load

[0039] Wc: Energy in the power capacitor

[0040] Since it is not possible to conceive of increasing the size of the capacitors of the power electronics, which would lead to an over-sized design of the system, nor to conceive of accelerating the voltage and current control loops, which would involve limitations on the control lines (ECU cycle time, command delay, speed of the power electronics, etc.), the present invention adds a function in the control module 118 to provide regulation of the generated voltage in order to limit its variations during a request for assistance for a turbomachine and to keep it within the range of variations defined by the envelope. Since no external power source has been added or the capacitors of the power electronics responsible for storing electrical energy have been over-sized, the mass is optimized.

[0041] Figure 3 The components forming the thus modified control module 118 are detailed, which module also comprises: a voltage regulation module 200, which delivers a predefined voltage envelope or the power P required to ensure these envelopes; a mode generation module 202, connected thereto and receiving the power setpoint of the ECU 120 and coordinating the sharing of the power of the load L between the HP shaft and the LP shaft; two associated assistance modules, one 204 associated with the high-pressure shaft and the other 206 associated with the LP shaft and configured to respectively add the low-pressure P LP or the high-pressure P HP injected power to the remaining high-pressure P HP or low-pressure P LP output power; and a selection module 208, which is configured to select the output power P LP and P HP from the mode generation module or from the assistance module based on the power mode (MODE) from the ECU 120. Each assistance module includes adders 300, 302 for quantifying the power additionally generated on one side and the power output on the other side; and adaptive modules 304, 306 having transfer functions F1, F2 depending on the dynamic range of the associated machine.

[0042] For example, if the ECU requests negative power from the LP shaft (PLP in motor mode), then in order to calculate P HP , the adder subtracts this negative power P LP from the input power P to the assistance module 204, i.e. 100% of the power of the load since P LP has entered the motor mode. The P HP at the output is equal to P + P LP .

[0043] The transfer functions F1 and F2 are used to adapt the dynamic range of the power output from the remaining machine to the dynamic range of the machine that has entered the motor mode in order to predict its power requirements. Depending on the particular case, F1 and F2 can be equal to:

[0044] - If the two machines installed on the HP shaft and the LP shaft have the same dynamic range, then F1 and F2 are equal to 1 (unity);

[0045] - If the machine entering the motor mode has a slower dynamic range than the machine remaining in the generator mode, then F1 and F2 are a phase delay or any function that allows the response of the remaining machine to be slowed down, such as a first-order transfer function;

[0046] - If the machine entering the motor mode has a faster dynamic range than the remaining machines, then F1 and F2 are phase-advance functions.

[0047] Figure 4 The different steps of the method implemented in the control module are illustrated.

[0048] In the first step 400, the system is in the normal operating state in the power generation mode, and the output power is shared between the high-pressure shaft and the low-pressure shaft. In the next step 402, a request for operation in the auxiliary mode is issued. For example, the high-pressure motor (i.e., the motor driving the high-pressure shaft) that is in the generator mode in the normal operating mode (which is interrupted) enters the motor mode. In the new step 404, the auxiliary module associated with the high-pressure shaft comes into action to transfer the high-pressure power to the low-pressure shaft, and then in the final step 406, the power output by the low-pressure shaft is adjusted based on this high-pressure power to achieve the additional power requested by the auxiliary mode.

[0049] It should be noted that the present invention can be applied to the internal hybridization of turbine engines regardless of the number of motors installed on the propulsion system and the type of turbine engine, such as a hybrid turbofan engine, a hybrid turboprop engine, or a hybrid helicopter turbine engine.

Claims

1. A method for managing power transfer between a power generation mode and an auxiliary mode of a turbine engine (100), the turbine engine having a high-pressure shaft (102) driving a high-pressure electric machine (106) and a low-pressure shaft (104) driving a low-pressure electric machine (108), high-pressure power (HP) being output from the high-pressure shaft and low-pressure power (LP) being output from the low-pressure shaft, the power generation mode corresponding to a predetermined power sharing between the high-pressure power and the low-pressure power, and the auxiliary mode corresponding to a request for injecting additional power into the high-pressure shaft or the low-pressure shaft. It is characterized in that To achieve the requested additional power, when the output of the high-pressure power or the low-pressure power is interrupted and the high-pressure electric machine or the low-pressure electric machine driving the high-pressure shaft or the low-pressure shaft with the interrupted output respectively enters the motor mode, the remaining output power of the high-pressure shaft or the low-pressure shaft in the generator mode is adjusted based on the injected high-pressure power or low-pressure power from the high-pressure electric machine or the low-pressure electric machine that has entered the motor mode.

2. The method for managing power transfer according to claim 1, wherein if the high-pressure electric machine or the low-pressure electric machine has a different dynamic range, the injection of the requested additional power is accomplished by matching the dynamic range of the output of the remaining output high-pressure power or low-pressure power.

3. A turbomachine (100) having: a high-pressure shaft (102) and a low-pressure shaft (104), with high-pressure power (HP) output from the high-pressure shaft and low-pressure power (LP) output from the low-pressure shaft; a control module (118) that receives power setpoints from an ECU (120) and power converters (110, 112) associated with a high-pressure electric machine (106) and a low-pressure electric machine (108) respectively mounted on the high-pressure shaft and the low-pressure shaft; a power generation mode corresponding to a predetermined power sharing between the high-pressure power and the low-pressure power; and an auxiliary mode corresponding to injecting additional power into the high-pressure shaft or the low-pressure shaft, characterized in that, To achieve the requested additional power, the control module (118) is configured such that: when the output of the high-pressure power or the low-pressure power is interrupted and the high-pressure electric machine or the low-pressure electric machine driving the high-pressure shaft or the low-pressure shaft with the interrupted output respectively enters the motor mode, the remaining output power of the high-pressure shaft or the low-pressure shaft in the generator mode is adjusted based on the injected high-pressure power or low-pressure power from the high-pressure electric machine or the low-pressure electric machine that has entered the motor mode.

4. The turbine engine according to claim 3, wherein the control module further includes auxiliary modules (204, 206) and a selection module (208), the auxiliary modules being configured to add the injected high-pressure power or low-pressure power to the remaining output high-pressure power or low-pressure power, and the selection module being configured to select the output power from the auxiliary modules.

5. The turbine engine according to claim 4, wherein each auxiliary module includes an adder (300, 302) and an adaptation module (304, 306), the adaptation module having transfer functions F1, F2 for matching the dynamic range of the remaining output high-pressure power or low-pressure power according to the respective dynamic ranges of the high-pressure electric machine and the low-pressure electric machine.

6. The turbine engine according to claim 5, wherein if the high-pressure electric machine and the low-pressure electric machine have the same dynamic range, the transfer function is equal to 1.

7. The turbine engine according to claim 5, wherein if the dynamic range of the electric machine entering the motor mode is slower than the dynamic range of the electric machine remaining in the generator mode, the transfer function is a phase delay.

8. The turbine engine according to claim 5, wherein if the dynamic range of the electric machine entering the motor mode is faster than the dynamic range of the electric machine remaining in the generator mode, the transfer function is a phase advance function.

9. A turbine engine according to any one of claims 3 to 8, including an aero turbine engine, such as a hybrid turbofan, a hybrid turboprop or a hybrid helicopter turbine engine.

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