An aircraft engine and a method for extracting and distributing power thereof

Abstract

The invention discloses an aero-engine and a power extraction and distribution method thereof, which include a first-level control and a second-level control. The second-level control plans a power extraction and distribution strategy according to flight conditions, power, thrust instructions and electrical load instructions. When the engine is in a steady state, the impact on the engine caused by a sudden change in high-power electrical load and electric energy feedback is balanced. When the engine is operating at the boundary of a flight envelope or in a transition state, the operability of the engine is improved. The output of the second-level control is used as an input instruction of the first-level control to complete closed-loop control of a first generator, a second generator and an energy storage device. The application reduces the impact on the engine dynamics caused by a sudden change in high-power electrical load or the generation of feedback electric energy, and improves the operability of a multi-rotor engine at the boundary of the flight envelope and in a transition state.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft engine control, and in particular to an aircraft engine and a method for extracting and distributing power thereof. Background Art

[0002] The generator on the aircraft mainly extracts mechanical energy from the engine shaft and converts it into electrical energy. Since the power level of the electrical load on the current aircraft is relatively small (hundreds of kilowatts), the impact of the generator power extraction on the engine performance can be ignored. However, the power demand under new architectures such as multi-electric engines, multi-electric aircraft, and hybrid electric propulsion can reach above megawatts. At this time, the dynamic changes in the generator power extraction will affect the engine operation stability and need to be considered. For example, a sudden increase in power extraction on the high-pressure rotor of a dual-rotor engine will cause the working line of the low-pressure compressor to move up and reduce the surge margin. A sudden increase in power extraction on the low-pressure rotor will cause the working line of the low-pressure compressor to move down and increase the surge margin. In addition, the feedback power generated by the electrical load under the new architecture is also much greater than that of the current aircraft. The high-power feedback power will impact the operation of the generator, and then affect the engine rotor connected to the generator. Therefore, the impact of large-power load mutations and power feedback on the engine operation stability needs to be considered.

[0003] Due to the aerodynamic thermodynamic characteristics of the engine, the different rotors in the multi-rotor engine are coupled in motion and cannot work at their respective optimal operating points. When the engine is operating at the boundary of the flight envelope or in a transition state, the impact of this coupling on the engine's operability is more prominent. As early as the 1960s, scholars and engine manufacturers proposed the use of mechanical hydraulic methods to decouple the rotors. However, due to the complexity and low efficiency of the device, it has not been applied in practice. The application of large-capacity generators provides a solution, that is, by reasonably distributing the power extracted by the generator from the engine shaft, changing the torque of the shaft, and realizing the decoupling of the rotor, the operability of the engine is improved. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide an aircraft engine and a power extraction and distribution method thereof, which can reduce the impact on the engine dynamics caused by sudden changes in high-power electrical loads or the generation of feedback electrical energy, and at the same time can reasonably distribute the power extraction of the generator from the engine shaft, provide a method for solving the dynamic coupling of rotors in a multi-rotor engine, and improve the operability of the engine at the boundary of the flight envelope and in the transition state.

[0005] Technical solution: The aircraft engine described in the present invention includes:

[0006] a first rotating shaft, the first rotating shaft being connected to a high-pressure turbine and a high-pressure compressor of the engine;

[0007] a second rotating shaft, the second rotating shaft being connected to a low-pressure turbine and a low-pressure compressor of the engine;

[0008] A FADEC system, wherein the FADEC system includes an engine controller, an actuator, and an engine sensor;

[0009] a first generator, wherein the first generator extracts power from the first rotating shaft and the generated alternating current is converted into direct current by a first AC / DC bidirectional converter;

[0010] a second generator, the second generator extracting power from the second rotating shaft, and the generated alternating current is converted into direct current by a second AC / DC bidirectional converter;

[0011] An energy storage device, the energy storage device comprising a battery and a super capacitor, the battery being connected to the first DC / DC bidirectional converter, and the super capacitor being connected to the second DC / DC bidirectional converter;

[0012] An electrical load, wherein a sudden increase in the electrical load manifests itself as a load step, and a sudden reduction in the electrical load generates feedback electrical energy;

[0013] a DC bus, the DC bus connecting the first generator, the second generator, the energy storage device and the electrical load;

[0014] Electrical sensors measure voltage, current and power of the first generator, the second generator, the energy storage device, the DC bus and the electrical load.

[0015] A power extraction and distribution method for an aircraft engine includes a first-level control and a second-level control, wherein the second-level control plans a power extraction and distribution strategy according to flight conditions, power, thrust instructions, and electrical load instructions, and the output of the second-level control is used as an input instruction of the first-level control. The closed-loop control of a first generator, a second generator, and an energy storage device is completed through a first-level controller, and the first-level controller includes a first AC / DC control unit, a second AC / DC control unit, a first DC / DC control unit, and a second DC / DC control unit.

[0016] Preferably, the second level control plans the power extraction and distribution strategy according to the flight conditions, power, thrust instructions and electrical load instructions, specifically including:

[0017] The engine controller determines whether the engine is in a steady state or a transition state;

[0018] When the engine is in steady state, the engine controller executes the steady state control plan. At the same time, the power extraction and distribution strategy controller determines the electrical load state. If the load is a step, the power state SOC of the energy storage device is further determined. If SOC>0.2, the energy storage device is discharged. If SOC<0.2, the energy storage device is prohibited from discharging, and the second generator increases power extraction. If the load feeds back electrical energy, the energy storage device SOC is further determined. If SOC>0.8, the energy storage device is prohibited from charging, and the first generator reduces power extraction. If SOC<0.8, the energy storage device is charged. If the load is steady, the engine is controlled according to the normal plan.

[0019] When the engine is in a transition state, the engine controller executes the transition state control plan and determines whether the engine is in an acceleration state or a deceleration state; if the engine is in a deceleration state, the power extraction and distribution strategy controller determines the SOC of the energy storage device. If the SOC is greater than 0.2, the second generator increases power extraction and injects it into the first generator, and the energy storage device is prohibited from charging; if the SOC is less than 0.2, the energy storage device is prohibited from discharging, the second generator increases power extraction, reduces the torque of the second shaft, and the excess electric energy is injected into the first generator; if the engine is in an acceleration state, the SOC of the energy storage device is determined. If the SOC is greater than 0.2, the energy storage device is discharged, power is injected into the first generator, and the torque of the first shaft is increased; if the SOC is less than 0.2, the energy storage device is prohibited from discharging, the second generator increases power extraction, injects electric energy into the first generator, and increases the torque of the first shaft.

[0020] Preferably, the first AC / DC control unit measures the current, speed and torque signals of the first generator, and after comparing and calculating with the control instructions output by the second-level control, outputs a duty cycle signal to the first AC / DC bidirectional power converter to control the amount of alternating current generated by the first generator, change the amount of power extracted from the high-voltage rotor, and thereby increase or decrease the high-voltage rotor torque.

[0021] Preferably, the second AC / DC control unit measures the current, speed and torque signals of the second generator, compares and calculates with the control instructions output by the second-level control, and outputs a duty cycle signal to the second AC / DC bidirectional power converter to adjust the amount of alternating current generated by the second generator, change the amount of power extracted from the low-voltage rotor, and thereby increase or decrease the low-voltage rotor torque.

[0022] Preferably, the first DC / DC control unit measures the voltage and power signal of the DC bus, compares and calculates the control signal output by the second-level control, and outputs a duty cycle signal to the first DC / DC bidirectional power converter to control the battery to absorb or release electrical energy.

[0023] Preferably, the second DC / DC control unit measures the voltage and power signal of the DC bus, compares and calculates the control signal output by the second level control, and outputs a duty cycle signal to the second DC / DC bidirectional power converter to control the supercapacitor to absorb or release electrical energy.

[0024] Beneficial effects:

[0025] (1) In terms of engine stability, the present invention can reduce the impact on the engine dynamics caused by sudden changes in high-power electrical load or when feedback electrical energy is generated;

[0026] (2) In terms of engine operability, the present invention can improve the operability of a multi-rotor engine at the flight envelope boundary and in the transition state;

[0027] (3) In terms of the engine system structure, the present invention can reduce the peak capacity requirement of the generator, thereby reducing the size and weight of the generator, reducing the dissipative components and cooling system used to consume feedback electrical energy, and eliminating the bleed valve device between the low-pressure compressor and the high-pressure compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the system schematic diagram of the engine in this application;

[0029] Figure 2 It is a schematic diagram of the control architecture for power extraction and distribution of the second level control in this application;

[0030] Figure 3 is a schematic diagram of the power extraction and allocation strategy of the second level control in this application;

[0031] Figure 4 This is a schematic diagram of the first-level controller in this application controlling the battery to absorb or release electrical energy. DETAILED DESCRIPTION

[0032] The present application is further described below in conjunction with specific embodiments.

[0033] like Figure 1 As shown, it is a system schematic diagram of the engine in this application. In this embodiment, it includes:

[0034] a first rotating shaft, the first rotating shaft being connected to a high-pressure turbine and a high-pressure compressor of the engine;

[0035] a second rotating shaft, the second rotating shaft being connected to a low-pressure turbine and a low-pressure compressor of the engine;

[0036] A FADEC system, wherein the FADEC system includes an engine controller, an actuator, and an engine sensor;

[0037] a first generator, wherein the first generator extracts power from the first rotating shaft and the generated alternating current is converted into direct current by a first AC / DC bidirectional converter;

[0038] a second generator, the second generator extracting power from the second rotating shaft, and the generated alternating current is converted into direct current by a second AC / DC bidirectional converter;

[0039] An energy storage device, the energy storage device comprising a battery and a super capacitor, the battery being connected to the first DC / DC bidirectional converter, and the super capacitor being connected to the second DC / DC bidirectional converter;

[0040] An electrical load, wherein a sudden increase in the electrical load manifests itself as a load step, and a sudden reduction in the electrical load generates feedback electrical energy;

[0041] a DC bus, the DC bus connecting the first generator, the second generator, the energy storage device and the electrical load;

[0042] Electrical sensors measure voltage, current and power of the first generator, the second generator, the energy storage device, the DC bus and the electrical load.

[0043] The power extraction and distribution method of the engine in this application includes a first-level control and a second-level control, such as Figure 2 and 3 As shown, the second level of control plans the power extraction and distribution strategy according to the flight conditions, power, thrust instructions and electrical load instructions, including:

[0044] The engine controller determines whether the engine is in a steady state or a transition state;

[0045] When the engine is in steady state, the engine controller executes the steady-state control plan. At the same time, the power extraction and distribution strategy controller determines the electrical load state. If the load is a step, the power state SOC of the energy storage device is further determined. If SOC>0.2, the energy storage device is discharged. If SOC<0.2, the energy storage device is prohibited from discharging, and the second generator increases power extraction. If the load feeds back electrical energy, the SOC of the energy storage device is further determined. If SOC>0.8, the energy storage device is prohibited from charging, and the first generator reduces power extraction. If SOC<0.8, the energy storage device is charged. If the load is steady, the engine is controlled according to the normal plan.

[0046] When the engine is in a transition state, the engine controller executes the transition state control plan and determines whether the engine is in an acceleration state or a deceleration state; if the engine is in a deceleration state, the power extraction and distribution strategy controller determines the SOC of the energy storage device. If the SOC is greater than 0.2, the second generator increases power extraction and injects it into the first generator, and the energy storage device is prohibited from charging; if the SOC is less than 0.2, the energy storage device is prohibited from discharging, the second generator increases power extraction, reduces the torque of the second shaft, and the excess electric energy is injected into the first generator; if the engine is in an acceleration state, the SOC of the energy storage device is determined. If the SOC is greater than 0.2, the energy storage device is discharged, power is injected into the first generator, and the torque of the first shaft is increased; if the SOC is less than 0.2, the energy storage device is prohibited from discharging, the second generator increases power extraction, injects electric energy into the first generator, and increases the torque of the first shaft.

[0047] The second-level control plans the power extraction and distribution strategy according to the flight conditions, power, thrust instructions and electrical load instructions, and uses the output as the input instruction of the first-level control. The first-level controller completes the closed-loop control of the first generator, the second generator and the energy storage device.

[0048] In this embodiment, the first-level controller includes a first AC / DC control unit, a second AC / DC control unit, a first DC / DC control unit, and a second DC / DC control unit.

[0049] In this embodiment, the first AC / DC control unit measures the current, speed and torque signals of the first generator, compares and calculates with the control instructions output by the second-level control, and outputs a duty cycle signal to the first AC / DC bidirectional power converter to control the amount of alternating current generated by the first generator, change the amount of power extracted from the high-voltage rotor, and thereby increase or decrease the high-voltage rotor torque.

[0050] In this embodiment, the second AC / DC control unit measures the current, speed and torque signals of the second generator, compares and calculates with the control instructions output by the second-level control, and outputs a duty cycle signal to the second AC / DC bidirectional power converter to adjust the amount of alternating current generated by the second generator, change the amount of power extracted from the low-voltage rotor, and thereby increase or decrease the low-voltage rotor torque.

[0051] like Figure 4 As shown, in this embodiment, the first DC / DC control unit measures the voltage and power signal of the DC bus, compares and calculates the control signal output by the second-level control, and outputs a duty cycle signal to the first DC / DC bidirectional power converter to control the battery to absorb or release electrical energy.

[0052] In this embodiment, the second DC / DC control unit measures the voltage and power signal of the DC bus, compares and calculates the control signal output by the second level control, and outputs a duty cycle signal to the second DC / DC bidirectional power converter to control the supercapacitor to absorb or release electrical energy.

Claims

1. A method for extracting and distributing power of an aircraft engine, Features: It includes the first level control and the second level control. The second level control plans the power extraction and distribution strategy according to the flight conditions, power, thrust instructions and electrical load instructions, which specifically includes: The engine controller determines whether the engine is in a steady state or a transition state; When the engine is in steady state, the engine controller executes the steady state control plan. At the same time, the power extraction and distribution strategy controller determines the electrical load state. If the load is a step, the power state SOC of the energy storage device is further determined. If SOC>0.2, the energy storage device is discharged. If SOC<0.2, the energy storage device is prohibited from discharging, and the second generator increases power extraction. If the load feeds back electrical energy, the energy storage device SOC is further determined. If SOC>0.8, the energy storage device is prohibited from charging, and the first generator reduces power extraction. If SOC<0.8, the energy storage device is charged. If the load is steady, the engine is controlled according to the normal plan; When the engine is in a transition state, the engine controller executes the transition state control plan and determines whether the engine is in an acceleration state or a deceleration state; if the engine is in a deceleration state, the power extraction and allocation strategy controller determines the SOC of the energy storage device. If the SOC>0.2, the second generator increases power extraction and injects it into the first generator, and the energy storage device is prohibited from charging; if the SOC<0.2, the energy storage device is prohibited from discharging, the second generator increases power extraction, reduces the torque of the second shaft, and the excess electric energy is injected into the first generator; if the engine is in an acceleration state, the SOC of the energy storage device is determined. If the SOC>0.2, the energy storage device discharges, injects power into the first generator, and increases the torque of the first shaft; If the SOC is less than 0.2, the energy storage device is prohibited from discharging, the second generator increases power extraction, injects electrical energy into the first generator, and increases the torque of the first shaft.

2. A method for extracting and distributing power of an aircraft engine according to claim 1, Features: The output of the second-level control is used as the input instruction of the first-level control, and the closed-loop control of the first generator, the second generator and the energy storage device is completed through the first-level controller. The first-level controller includes a first AC / DC control unit, a second AC / DC control unit, a first DC / DC control unit and a second DC / DC control unit.

3. A method for extracting and distributing power of an aircraft engine according to claim 2, Features: The first AC / DC control unit measures the current, speed and torque signals of the first generator, compares and calculates with the control instructions output by the second-level control, and outputs a duty cycle signal to the first AC / DC bidirectional power converter to control the amount of alternating current generated by the first generator, change the amount of power extracted from the high-voltage rotor, and thereby increase or decrease the high-voltage rotor torque.

4. The method for extracting and distributing power of an aircraft engine according to claim 2, Features: The second AC / DC control unit measures the current, speed and torque signals of the second generator, compares and calculates with the control instructions output by the second-level control, and outputs a duty cycle signal to the second AC / DC bidirectional power converter to adjust the amount of alternating current generated by the second generator, change the amount of power extracted from the low-voltage rotor, and thereby increase or decrease the low-voltage rotor torque.

5. The method for extracting and distributing power of an aircraft engine according to claim 2, Features: The first DC / DC control unit measures the voltage and power signal of the DC bus, compares and calculates the control signal output by the second-level control, and outputs a duty cycle signal to the first DC / DC bidirectional power converter to control the battery to absorb or release electrical energy.

6. A method for extracting and distributing power of an aircraft engine according to claim 2, Features: The second DC / DC control unit measures the voltage and power signal of the DC bus, compares and calculates the control signal output by the second level control, and outputs a duty cycle signal to the second DC / DC bidirectional power converter to control the supercapacitor to absorb or release electrical energy.

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