WO2021238047A1

WO2021238047A1 - Power system of electric propulsion rotary wing aircraft, and control method therefor

Info

Publication number: WO2021238047A1
Application number: PCT/CN2020/124377
Authority: WO
Inventors: 陈方; 田沛东
Original assignee: 上海交通大学
Priority date: 2020-05-28
Filing date: 2020-10-28
Publication date: 2021-12-02
Also published as: CN111703580B; CN111703580A

Abstract

A power system of an electric propulsion rotary wing aircraft, and a control method therefor. The power system of an aircraft comprises a fusion energy storage system, a brushless direct current motor speed regulator, a brushless direct-current motor, propellers mounted on the brushless direct current motor, a flight control computer, an aircraft inertial sensor, a height sensor and a remote control signal receiver. The power system of an electric propulsion rotary wing aircraft can predict power requirements of an aircraft, so as to achieve good management of the power output of the energy storage system. The control method for the power system can satisfy the real-time power requirement and power reserve requirement of the aircraft by using a power system having a lower weight, and the control method for the power system can also prolong the service life of an energy system, so as to improve the safety, maneuverability and endurance of the aircraft.

Description

Electric propulsion rotorcraft power system and control method thereof

Technical field

The invention relates to an aircraft, in particular to an electric propulsion rotorcraft power system and a control method thereof.

Background technique

We are on the eve of the electric engine revolution. The replacement of traditional forms of energy with electric energy is an inevitable development direction. Popularizing electric propulsion is bound to break the current pattern of traditional aircraft and engine manufacturing. Electric propulsion technology has significant advantages, and autonomous manned aircraft based on electric propulsion is the technological development direction of urban air traffic solutions. Pure electric drive power system is the core technology of electric propulsion aircraft.

With the rapid development of the new energy field in recent years, the research on various energy storage units has become mature, but each energy storage unit has its own unavoidable defects. Among them, lithium batteries have the advantage of high energy density, but have disadvantages such as low specific power and short cycle life, so their energy release ability is poor; supercapacitors have the advantage of high power density, but they are at a significant disadvantage in terms of specific energy parameters. , So the energy storage performance is poor.

The main bottleneck in the application of electric propulsion systems to aircraft at this stage is the large difference in power requirements of aircraft in different flight states. Traditional power systems based on a single energy storage element cannot simultaneously take into account high output efficiency and quickly respond to the rapidly changing power requirements of aircraft. For example, the current electric propulsion aircraft power system widely uses lithium battery-based power systems, and the response speed is slow in the face of large changes in the power requirements of the aircraft in different flight modes, resulting in poor power matching effects and high battery life losses.

Summary of the invention

The purpose of the present invention is to provide an electric propulsion rotorcraft power system and its control method. On the basis of meeting the rapid response to the power demand of the aircraft, the high-efficiency output of the power system is realized at the same time. Therefore, the core of the present invention lies in the matching of the power requirements of the aircraft and the power output of the energy storage system. Through the power system control method based on aircraft flight mode recognition, the aircraft power system can predict the power demand of the aircraft to achieve the purpose of better management of the power output of the energy storage system.

Through the power system control method, the real-time power demand and power reserve demand of the aircraft can be met with a lower weight power system. At the same time, the power system control method can also extend the service life of the energy system, making the aircraft safe, maneuverable, and endurance. improve.

The technical solution of the present invention is as follows:

An electric propulsion rotorcraft power system, which is characterized in that the aircraft power system includes a fusion energy storage system, a brushless DC motor governor, a brushless DC motor, a propeller mounted on the brushless DC motor, and a flight control computer , Aircraft inertial sensors, altitude sensors and remote control signal receivers;

The brushless DC motor speed controller is composed of a first AC inverter, a second AC inverter, a third AC inverter, and a fourth AC inverter. The aircraft inertial sensor, height sensor, and The output end of the remote control signal receiver is connected to the flight control computer. The fusion energy storage system includes a lithium battery and a super capacitor. The output end of the super capacitor uses a bidirectional DC/DC converter to control the energy flow, and In parallel with the lithium battery, the output terminal of the voltage sensor connected in parallel with the lithium battery is connected to the input terminal of the flight control computer, and the output terminal of the voltage sensor connected in parallel with the super capacitor is connected to the flight control computer. The input terminal of the computer is connected, and the positive electrode of the lithium battery is respectively connected to the positive electrode of the input terminal of the first AC inverter, the second AC inverter, the third AC inverter, and the fourth AC inverter. , The negative electrode of the lithium battery is respectively connected to the negative electrode of the input terminals of the first AC inverter, the second AC inverter, the third AC inverter, and the fourth AC inverter, and the first The output ends of an AC inverter, a second AC inverter, a third AC inverter, and a fourth AC inverter are connected to the first brushless DC motor, the second brushless DC motor, and the third AC inverter. The brushed DC motor and the fourth brushless DC motor are connected in a one-to-one correspondence, and the control output end of the flight control computer is respectively connected to the two-way DC/DC converter, the first AC inverter, and the second AC inverter. The control ends of the third AC inverter and the fourth AC inverter are connected.

The aircraft height sensor is an ultrasonic distance sensor or a barometric altimeter.

The method for controlling the power system of the electric propulsion rotorcraft is characterized in that the method includes the following steps:

1) Aircraft flight mode recognition and power prediction, including:

① The flight control computer collects and filters the data of the aircraft inertial sensor to obtain the aircraft attitude angle

θ, ψ, three-axis acceleration a _x , a _y , a _z in the aircraft body coordinate system, three-axis angular velocity ω _x , ω _y , ω _z and angular acceleration p, q, r information in the aircraft body coordinate system, and collect the information And filter the data of the aircraft height sensor to obtain the height information h of the aircraft from the ground;

②Based on the aircraft inertial sensor data, the flight control computer discriminates the aircraft's flight speed change mode, attitude change mode, and altitude change mode;

③The flight control computer combined with the aircraft control command input predicts whether the aircraft power demand category is low power, instantaneous high power, or long-term high power according to the preset weight value;

2) The flight control computer classifies the working modes of lithium batteries and supercapacitors according to the types of aircraft power requirements: the working modes of lithium batteries are divided into 4 levels with preset output power of P1, P2, P3, and P4 And P1<P2<P3<P4, the working mode of super capacitor is divided into 5 modes: disconnection, discharge, slow charging, faster charging and fast charging. SOC is used to represent the state of charge of the super capacitor, which defines the state of charge of the graded super capacitor. : The upper limit of the primary SOC is H1, the upper limit of the secondary SOC is H2, the lower limit of the primary SOC is L1, the lower limit of the secondary SOC is L2 and 0<L2<L1<H1<H2<100%, the lithium The judgment method of battery and super capacitor working mode is as follows:

If the aircraft power demand category is low power consumption at this time:

If SOC>H2 is determined, the preset output power of the lithium battery is set to P1, and the working mode of the supercapacitor is disconnected;

If it is determined that H1<SOC<H2, the preset output power of the lithium battery is set to P2, and the working mode of the supercapacitor is slow charging;

If it is determined that L1<SOC<H2, the preset output power of the lithium battery is set to P3, and the working mode of the supercapacitor is faster charging;

If SOC<L1 is determined, the preset output power of the lithium battery is set to P4, and the working mode of the supercapacitor is fast charging;

If the aircraft power demand category is instantaneous high power consumption at this time:

If SOC>L2 is judged, the preset output power of the lithium battery is set to P3, and the working mode of the supercapacitor is discharge;

If SOC<L2 is judged, the preset output power of the lithium battery is set to P4, and the working mode of the supercapacitor is disconnected;

If the aircraft power demand category is long-term high power consumption at this time:

If SOC>L1 is judged, the preset output power of the lithium battery is set to P3, and the working mode of the supercapacitor is discharge;

If SOC<L1 is judged, the preset output power of the lithium battery is set to P4, and the working mode of the supercapacitor is disconnected;

3) Lithium battery and supercapacitor output power setting: smooth the output power of the lithium battery based on the filtering algorithm, use supercapacitors to make up for the lack of power or store excess power, so that the total power output meets the power requirements of the aircraft, while the output of the lithium battery fluctuates Smaller and close to the preset output power of the lithium battery described in step 2);

4) The power output of the super capacitor is controlled through the two-way DC\DC converter, and the first AC inverter, the second AC inverter, the third AC inverter, and the fourth AC inverter are used to control the power output of the super capacitor. The inverter controls the overall power output of the energy system, drives the first brushless DC motor, the second brushless DC motor, the third brushless DC motor, and the fourth brushless DC motor to provide power for the propeller. Need motivation.

The technical effects of the present invention are as follows:

1. The present invention realizes the high-efficiency output of the power system while satisfying the rapid response to the power demand of the aircraft. Therefore, the core of the present invention lies in the matching of the power requirements of the aircraft and the power output of the energy storage system. Through the power system control method based on aircraft flight mode recognition, the aircraft power system can predict the power demand of the aircraft to achieve the purpose of better management of the power output of the energy storage system.

2. Through the power system control method, the power system of lower weight can meet the real-time power demand and power reserve demand of the aircraft. At the same time, the power system control method can also extend the service life of the energy system, making the aircraft safe, maneuverable and more efficient. Increased endurance.

Description of the drawings

Figure 1 is a schematic diagram of the circuit structure and control signals of the power system of the present invention;

Figure 2 is a flow chart of the working principle of the power system control method of the present invention;

Figure 3 is a flow chart of the principle of the aircraft pattern recognition method of the present invention;

4 is a schematic flow chart of the method for setting the working mode of the lithium battery and the super capacitor according to the present invention;

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

The specific implementation manner will be described below with reference to FIGS. 1-4. Please refer to Figure 1 first. It can be seen from the figure that the electric propulsion rotorcraft power system based on flight mode recognition of the present invention includes: a fusion energy storage system, a brushless DC motor governor, a brushless DC motor, and the brushless The propeller on the DC motor, the flight control computer, the aircraft inertial sensor, the altitude sensor and the remote control signal receiver; the brushless DC motor speed controller is composed of the first AC inverter, the second AC inverter, and the third AC inverter. The output terminals of the aircraft inertial sensor, the altitude sensor and the remote control signal receiver are connected to the flight control computer, and the fusion energy storage system includes lithium batteries and super The output terminal of the super capacitor adopts a bidirectional DC/DC converter to control the energy flow, and is connected in parallel with the lithium battery. The output terminal of the voltage sensor connected in parallel with the lithium battery is connected to the flight control computer The input terminal is connected, the output terminal of the voltage sensor connected in parallel with the super capacitor is connected to the input terminal of the flight control computer, and the positive electrode of the lithium battery is connected to the first AC inverter and the second AC The positive poles of the input terminals of the inverter, the third AC inverter, and the fourth AC inverter are connected, and the negative poles of the lithium battery are respectively connected to the first AC inverter, the second AC inverter, and the first AC inverter. The negative poles of the input ends of the three AC inverters and the fourth AC inverter are connected, and the output of the first AC inverter, the second AC inverter, the third AC inverter, and the fourth AC inverter The terminals are respectively connected to the first brushless DC motor, the second brushless DC motor, the third brushless DC motor, and the fourth brushless DC motor. The three-phase connector of the output terminal of the AC inverter is connected to the brushless DC motor. The three-phase connectors of the DC motor are connected, and the connectors do not distinguish a specific connection sequence. Changing the connection of any two-phase connector can change the direction of rotation of the brushless DC motor after it is energized. The control output of the flight control computer is connected to the two-way DC/DC converter, the first AC inverter, and the second AC. The control ends of the inverter, the third AC inverter, and the fourth AC inverter are connected.

This implementation method adopts the working principle of the power system control method shown in Figure 2, namely:

Step 1 Aircraft flight mode recognition and power prediction;

Step 2 Recognition of the state of charge of lithium batteries and supercapacitors;

Step 3 Lithium battery and super capacitor working mode setting;

Step 4 Lithium battery and super capacitor output power setting.

Step 5 Control the power output of the super capacitor through the bidirectional DC\DC converter, and control the overall power output of the energy system through the AC inverter, drive the brushless DC motor, and drive the propeller to provide the required power.

Further, in this implementation method, the aircraft flight mode recognition and power prediction described in step 1 are implemented through the principle of the aircraft mode recognition method as shown in FIG. 3. The principle steps of the aircraft pattern recognition method are:

The flight control computer described in step 1-1 collects and filters the aircraft inertial sensor data to obtain the aircraft attitude angle

θ, ψ, three-axis acceleration a _x , a _y , a _z in the aircraft body coordinate system, three-axis angular velocity ω _x , ω _y , ω _z and angular acceleration p, q, r in the aircraft body coordinate system, and collect the aircraft height sensor (It can be an ultrasonic distance sensor or barometric altimeter) data and filter to get the height of the aircraft from the ground h;

Step 1-2 judge the flight speed change mode of the aircraft. In this implementation method, a nonlinear autoregressive time series neural network is used, and the neural network function generated by the network predicts the power demand at the next time step, and recognizes the power demand pattern in the flight state. The nonlinear autoregressive time series neural network described in this implementation method is obtained through computer simulation and aircraft flight test data training. Through the nonlinear autoregressive time series neural network function, the aircraft attitude angle described in step 1-1 can be used

θ, ψ, three-axis acceleration a _x , a _y , a _z in the aircraft body coordinate system, three-axis angular velocity ω _x , ω _y , ω _z and angular acceleration p, q, r in the aircraft body coordinate system, the height of the aircraft from the ground The h data solves the time series of the flight speed change mode, attitude change mode, and altitude change mode of the aircraft.

Steps 1-3 identify the category of aircraft power requirements. The power demand categories are: low power, instantaneous high power, and long-term high power. In this implementation method, a fuzzy inference algorithm is used to identify the aircraft power demand category in the flight state. Using the flight speed change mode, attitude change mode, and altitude change mode time sequence of the aircraft described in steps 1-2, the aircraft remote control command input is used as fuzzy input variables. Among them, the flight speed change mode has three membership functions: stationary (STA), deceleration (DEC) and acceleration (ACC); the altitude change mode has five membership functions: high speed descent (MDEC), descent (DEC), fixed altitude ( HAV), ascent (CLI) and high-speed ascent (MCLI); the attitude change mode has three membership functions: stable (STA), rotation (ROT), and high-speed rotation (MROT). The output variable is the aircraft power demand category, and its range is [0,1], with three membership functions: low power (LOW), instantaneous high power (IH), long-term high power (LH); aircraft remote control command input has two Three membership functions: low (LOW) and high (HIGH). On the basis of summing up expert experience, establish fuzzy control rule base. Fuzzy logic operation is used to realize the recognition of aircraft power demand categories based on flight speed change mode, attitude change mode, altitude change mode time series, and aircraft remote control command input.

Further, in this implementation method, the lithium battery and supercapacitor working mode setting in step 3 is implemented by the principle of the lithium battery and supercapacitor working mode setting method as shown in FIG. 4. The method for setting the working mode of the lithium battery and the super capacitor is specifically as follows:

According to the power requirements of the aircraft, the operating modes of the lithium battery and super capacitor are set in different levels. The working mode of lithium battery is divided into 4 levels with preset output power of P1, P2, P3, P4 (P1<P2<P3<P4), and the working mode of super capacitor is divided into disconnection, discharge, slow charging, faster 5 modes of charging and fast charging. Use SOC to represent the state of charge of supercapacitors and define the state of charge of graded supercapacitors: the upper limit of the first SOC H1, the upper limit of the second SOC H2, the lower limit of the first SOC L1, the lower limit of the second SOC L2 ((0<L2<L1<H1< H2<100%), the specific judgment method is:

If the aircraft power demand category is low power consumption at this time, and it is determined that SOC>H2, the preset output power of the lithium battery is set to P1, and the supercapacitor working mode is disconnected; if H1<SOC<H2 is determined, the preset output of the lithium battery is determined The power is set to P2, the supercapacitor work mode is slow charging; if L1<SOC<H2 is determined, the preset output power of the lithium battery is set to P3, and the supercapacitor work mode is faster charging; if SOC<L1 is determined, the lithium battery The default output power is set to P4, and the supercapacitor working mode is fast charging.

If the aircraft power demand category is instantaneous high power consumption at this time, and it is judged that SOC>L2, the preset output power of the lithium battery is set to P3, and the working mode of the supercapacitor is discharge; if SOC<L2 is judged, the preset output power of the lithium battery is set Set it to P4, and the supercapacitor working mode is disconnected.

If the aircraft power demand category is long-term high power consumption at this time, and SOC>L1 is judged, the preset output power of the lithium battery is set to P3, and the supercapacitor working mode is discharge; if SOC<L1 is judged, the preset output power of the lithium battery is Set to P4, and the supercapacitor working mode is disconnected.

According to a fourth aspect of the present invention, there is provided a method for setting the output power of a lithium battery and a super capacitor. The method includes: smoothing the output power of the lithium battery based on a filtering algorithm, using a super capacitor to make up for the lack of power or storing excess power, While the total power output meets the power requirements of the aircraft, the output of the lithium battery has less fluctuation and is close to the preset output power of the lithium battery according to claim 3.

The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

An electric propulsion rotorcraft power system, characterized in that the power system includes: a fusion energy storage system, a brushless DC motor governor, a brushless DC motor, a propeller mounted on the brushless DC motor, and a flight control computer , Aircraft inertial sensors, altitude sensors and remote control signal receivers;

The brushless DC motor speed controller is composed of a first AC inverter, a second AC inverter, a third AC inverter, and a fourth AC inverter. The aircraft inertial sensor, height sensor, and The output end of the remote control signal receiver is connected to the flight control computer. The fusion energy storage system includes a lithium battery and a super capacitor. The output end of the super capacitor uses a bidirectional DC/DC converter to control the energy flow, and In parallel with the lithium battery, the output terminal of the voltage sensor connected in parallel with the lithium battery is connected to the input terminal of the flight control computer, and the output terminal of the voltage sensor connected in parallel with the super capacitor is connected to the flight control computer. The input terminal of the computer is connected, and the positive electrode of the lithium battery is respectively connected to the positive electrode of the input terminal of the first AC inverter, the second AC inverter, the third AC inverter, and the fourth AC inverter. , The negative electrode of the lithium battery is respectively connected to the negative electrode of the input terminals of the first AC inverter, the second AC inverter, the third AC inverter, and the fourth AC inverter, and the first The output ends of an AC inverter, a second AC inverter, a third AC inverter, and a fourth AC inverter are connected to the first brushless DC motor, the second brushless DC motor, and the third AC inverter. The brushed DC motor and the fourth brushless DC motor are connected in a one-to-one correspondence, and the control output end of the flight control computer is respectively connected to the two-way DC/DC converter, the first AC inverter, and the second AC inverter. The control ends of the third AC inverter and the fourth AC inverter are connected.
The electric propulsion rotorcraft power system according to claim 1, wherein the aircraft height sensor is an ultrasonic distance sensor or a barometric altimeter.
The method for controlling the power system of an electric propulsion rotorcraft according to claim 1, characterized in that the method comprises the following steps:

1) Aircraft flight mode recognition and power prediction, including:

① The flight control computer collects and filters the data of the aircraft inertial sensor to obtain the aircraft attitude angle
θ, ψ, three-axis acceleration a x , a y , a z in the aircraft body coordinate system, three-axis angular velocity ω x , ω y , ω z and angular acceleration p, q, r information in the aircraft body coordinate system, and collect the information And filter the data of the aircraft height sensor to obtain the height information h of the aircraft from the ground;

②Based on the aircraft inertial sensor data, the flight control computer discriminates the aircraft's flight speed change mode, attitude change mode, and altitude change mode;

③The flight control computer combined with the aircraft control command input predicts whether the aircraft power demand category is low power, instantaneous high power, or long-term high power according to the preset weight value;

2) The flight control computer classifies the working modes of lithium batteries and supercapacitors according to the types of aircraft power requirements: the working modes of lithium batteries are divided into 4 levels with preset output power of P1, P2, P3, and P4 And P1<P2<P3<P4, the working mode of super capacitor is divided into 5 modes: disconnection, discharge, slow charging, faster charging and fast charging. SOC is used to represent the state of charge of the super capacitor, which defines the state of charge of the graded super capacitor. : The upper limit of the primary SOC is H1, the upper limit of the secondary SOC is H2, the lower limit of the primary SOC is L1, the lower limit of the secondary SOC is L2 and 0<L2<L1<H1<H2<100%, the lithium The judgment method of battery and super capacitor working mode is as follows:

If the aircraft power demand category is low power consumption at this time:

If SOC>H2 is determined, the preset output power of the lithium battery is set to P1, and the working mode of the supercapacitor is disconnected;

If it is determined that H1<SOC<H2, the preset output power of the lithium battery is set to P2, and the working mode of the supercapacitor is slow charging;

If it is determined that L1<SOC<H2, the preset output power of the lithium battery is set to P3, and the working mode of the supercapacitor is faster charging;

If SOC<L1 is determined, the preset output power of the lithium battery is set to P4, and the working mode of the supercapacitor is fast charging;

If the aircraft power demand category is instantaneous high power consumption at this time:

If SOC>L2 is judged, the preset output power of the lithium battery is set to P3, and the working mode of the supercapacitor is discharge;

If SOC<L2 is judged, the preset output power of the lithium battery is set to P4, and the working mode of the supercapacitor is disconnected;

If the aircraft power demand category is long-term high power consumption at this time:

If SOC>L1 is judged, the preset output power of the lithium battery is set to P3, and the working mode of the supercapacitor is discharge;

If SOC<L1 is judged, the preset output power of the lithium battery is set to P4, and the working mode of the supercapacitor is disconnected;

3) Lithium battery and supercapacitor output power setting: smooth the output power of the lithium battery based on the filtering algorithm, use supercapacitors to make up for the lack of power or store excess power, so that the total power output meets the power requirements of the aircraft, while the output of the lithium battery fluctuates Smaller and close to the preset output power of the lithium battery described in step 2);

4) The power output of the super capacitor is controlled through the two-way DC\DC converter, and the first AC inverter, the second AC inverter, the third AC inverter, and the fourth AC inverter are used to control the power output of the super capacitor. The inverter controls the overall power output of the energy system, drives the first brushless DC motor, the second brushless DC motor, the third brushless DC motor, and the fourth brushless DC motor to provide power for the propeller. Need motivation.