Method for distributing aircraft energy flow by system

Abstract

The invention provides a method for distributing aircraft energy flow by a system, which relates to the technical field of aircrafts and comprises the following steps of: S1, judging whether a motor outputs negative torque in a flight process; if yes, collecting the total generated power of the motor outputting the negative torque, and going to S2; otherwise, returning to S1; s2, judging whether the maximum charging power of the battery is smaller than the total power generation power or not; if yes, proceeding to S3; otherwise, the motor outputting the negative torque is connected to the battery; s3, whether the sum of the maximum charging power of the battery and the maximum discharging power of the discharging resistor is smaller than the total power generation power or not is judged; if yes, going to S4; otherwise, going to S5; s4, whether the driving power of the motor outputting the positive torque is allowed to be increased or not is judged; if yes, increasing, and going to S5; otherwise, performing three-phase short circuit on the motor; and S5, the motor outputting the negative torque is connected to the battery and the bleeder resistor. According to the method, energy flow processing under complex working conditions can be realized without adding hardware equipment, and the system response capability is improved.

Description

Technical Field

[0001] The present invention relates to the field of aircraft technology, and in particular to a method for systematically distributing aircraft energy flow. Background Art

[0002] The controller of a multi-rotor aircraft controls the rotation of each corresponding motor. The rotation of the motor drives the rotation of the rotor. The lift force generated by the rotor overcomes the gravity of the aircraft. The lift force is controlled by controlling the rotation speed of the motor, thereby controlling the rise or descent of the aircraft.

[0003] In normal operation, each motor outputs positive torque, and the motor speed is controlled by controlling the output torque. Then the energy goes from the battery to the motor, the battery works in discharge mode, and the motor works in drive mode. However, when an emergency occurs, we need to control one or several motors to quickly reduce the speed to achieve rapid attitude adjustment of the aircraft. The motor needs to output negative torque to quickly reduce the speed. At this time, the motor of the entire aircraft will generate a large amount of power generation energy. This part of the energy needs to be released or transferred in a timely and rapid manner, otherwise it will cause serious failures in the entire electrical system (such as overvoltage, etc.).

[0004] There are two existing methods for discharging and transferring motor generated energy: (1) storing the energy by charging the battery; (2) adding a discharge resistor to the battery bus to discharge the generated energy through the resistor.

[0005] The above two methods will have several problems in actual use. The first is the scheme of charging the battery. The mainstream high-voltage battery currently uses a ternary lithium battery pack. The peak discharge current and peak charge current of the battery are important parameters of the battery, and the actual charge and discharge current will also be affected by factors such as the temperature of the battery pack, SOC (remaining power), SOH (battery health status), etc. Therefore, in some extreme cases (such as low temperature, SOC close to 100%, SOH does not allow high current charging), the battery pack cannot accept this part of energy.

[0006] The second way of discharging is through resistors. Resistors discharge energy by generating heat, which will generate a lot of heat. At the same time, resistors cannot discharge continuously. When the time interval between two discharges is short, the resistor temperature is high, and the second allowable discharge power will be smaller, which will cause the system energy to be unable to be discharged. At the same time, the design requirements of the aircraft generally require light weight and small size. Therefore, if the design is based on a larger power discharge resistor, the weight and volume of the aircraft will increase significantly, which cannot meet the system design. If the discharge resistor power is selected to be small, it will lead to the inability to discharge the generated energy in time. Summary of the invention

[0007] The technical problem to be solved by the present invention is that the multi-rotor aircraft in the prior art cannot release energy in time when the motor outputs negative torque. In order to overcome the above defects of the prior art, the present invention provides a method for systematically distributing aircraft energy flow.

[0008] The present invention provides a method for systematically distributing aircraft energy flow, comprising the following steps:

[0009] S1. Determine whether the motor of the aircraft outputs negative torque during flight;

[0010] If yes, collect the total power generation P_sys of all motors that output negative torque, and go to step S2; otherwise, return to step S1;

[0011] S2, judging whether the maximum charging power P_bat allowed by the battery is less than the total power generation power P_sys;

[0012] If yes, proceed to step S3; otherwise, connect all motors that output negative torque to the battery to charge the battery;

[0013] S3, judging whether the sum of the maximum charging power P_bat allowed by the battery and the maximum discharge power P_res allowed by the discharge resistor is less than the total power generation power P_sys;

[0014] If yes, go to step S4; otherwise, go to step S5;

[0015] S4, determining whether it is allowed to increase the driving power of the motor that outputs positive torque;

[0016] If yes, the driving power of the motor that outputs positive torque is increased to (P_sys-P_bat-P_res), and the process goes to step S5; otherwise, the upper bridge or lower bridge of the three-phase full-bridge IGBT is fully turned on to short-circuit the three phases of the motor;

[0017] S5. Connect all motors that output negative torque to the battery and the discharge resistor to charge the battery and discharge it through the discharge resistor.

[0018] Compared with the prior art, the method for distributing aircraft energy flow in a system in the present application has the following advantages: no additional hardware equipment is required, and no additional weight, volume, and cost of the product is required; the power requirement of the discharge resistor can be reduced, thereby reducing the weight, volume, and cost of the entire system; energy flow processing under various complex working conditions can be achieved, the response capability of the entire system can be improved, and the special needs of the aircraft can be met; and the safety of the entire system can be effectively protected and the service life of the product can be improved while realizing the function.

[0019] In a possible implementation manner, the aircraft is a biplane aircraft, and the motor includes a first motor and a second motor; in step S1, it is determined whether the first motor or the second motor outputs a negative torque during the flight of the aircraft.

[0020] Compared with the existing technology, for a biplane aircraft, only two motors need to be analyzed to make a judgment.

[0021] In a possible implementation, each of the motors is a three-phase motor, and the electrical system of the aircraft includes a battery, a controller, a three-phase full-bridge IGBT and a three-phase motor, the power supply end of the controller is electrically connected to the battery, the output end of the controller is electrically connected to the three-phase full-bridge IGBT, the three intermediate bridges of the three-phase full-bridge IGBT are respectively electrically connected to the three phases of the three-phase motor, and the three-phase motor is a star-connected three-phase motor.

[0022] Compared with the prior art, for a three-phase motor with a star connection, the three-phase motor can be short-circuited so that the energy generated by the three-phase motor is consumed through the winding and will not be transmitted to the bus to affect the battery.

[0023] In a possible implementation manner, the negative torque Te output by the motor is 4.5×(Phif / Ld) 2 ×Rs÷We;

[0024] Among them, Phif is the rotor flux of the motor, Ld is the equivalent motor inductance of the d-axis, Rs is the motor resistance, and We is the rotational electrical frequency of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of a method for distributing energy flow of an aircraft according to a system of the present invention;

[0026] Figure 2 A controller and a three-phase full-bridge connection circuit diagram in a method for distributing aircraft energy flow in a system of the present invention;

[0027] Figure 3 The present invention is a three-phase connection circuit diagram of a motor in a method for systematically distributing aircraft energy flow. DETAILED DESCRIPTION

[0028] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0029] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0030] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] See also Figures 1 to 3 As shown, the embodiment of the present application discloses a method for systematically allocating energy flow of an aircraft, comprising the following steps:

[0032] S1. Determine whether the motor of the aircraft outputs negative torque during flight;

[0033] If yes, collect the total power generation P_sys of all motors that output negative torque, and go to step S2; otherwise, return to step S1;

[0034] S2, judging whether the maximum charging power P_bat allowed by the battery is less than the total power generation power P_sys;

[0035] If yes, proceed to step S3; otherwise, connect all motors that output negative torque to the battery to charge the battery;

[0036] S3, judging whether the sum of the maximum charging power P_bat allowed by the battery and the maximum discharge power P_res allowed by the discharge resistor is less than the total power generation power P_sys;

[0037] If yes, go to step S4; otherwise, go to step S5;

[0038] S4, determining whether it is allowed to increase the driving power of the motor that outputs positive torque;

[0039] If yes, the driving power of the motor that outputs positive torque is increased to (P_sys-P_bat-P_res), and the process goes to step S5; otherwise, the upper bridge or lower bridge of the three-phase full-bridge IGBT is fully turned on to short-circuit the three phases of the motor;

[0040] S5. Connect all motors that output negative torque to the battery and the discharge resistor to charge the battery and discharge it through the discharge resistor.

[0041] Among them, the maximum charging power P_bat allowed by the battery is updated in real time by the battery management system BMS through CAN messages; the maximum discharge power P_res allowed by the resistor is updated in real time by the motor controller sampling the resistor temperature and calculating internally.

[0042] This embodiment does not require additional hardware equipment, and does not require additional increase in product weight, volume, and cost; it can reduce the power requirement of the discharge resistor, thereby reducing the weight, volume, and cost of the entire system; it can realize energy flow processing under various complex working conditions, improve the responsiveness of the entire system, and meet the special needs of the aircraft; it can effectively protect the safety of the entire system and increase the service life of the product while realizing the function.

[0043] The aircraft is a biplane aircraft, and the motor includes a first motor and a second motor. In step S1, it is determined whether the first motor or the second motor outputs a negative torque during the flight of the aircraft.

[0044] Of course, other multi-wing aircraft are also possible, and we only need to analyze the output of each motor.

[0045] In this embodiment, a dual-rotor aircraft is taken as an example, that is, the motor includes a first motor and a second motor. Therefore, the torque output by the two motors includes four types:

[0046] Working condition 1: the first motor outputs positive torque, and the second motor outputs positive torque;

[0047] Working condition 2: the first motor outputs positive torque and the second motor outputs negative torque;

[0048] Working condition 3: the first motor outputs negative torque and the second motor outputs positive torque;

[0049] Working condition 4: the first motor outputs negative torque, and the second motor outputs negative torque.

[0050] According to these four working conditions, the battery is mainly divided into the following modes:

[0051] Discharge mode:

[0052] In working condition 1, the energy transfer path is mainly from the high-voltage battery to the first motor and the second motor, so the whole system works in the discharge mode;

[0053] In working condition 2, when the driving power of the first motor is greater than the generating power of the second motor, the system works in the discharge mode;

[0054] In working condition 3, when the power generated by the first motor is less than the driving power of the second motor, the system works in the discharge mode;

[0055] Charging Mode:

[0056] In working condition 2, when the driving power of the first motor is less than the generating power of the second motor, the system works in charging mode;

[0057] In working condition 3, when the power generated by the first motor is greater than the driving power of the second motor, the system operates in charging mode;

[0058] In working condition 4, the energy transfer path is mainly from the motor to the battery, so the entire system works in charging mode.

[0059] In this embodiment, in the charging mode, for a dual-rotor aircraft, the following solutions can be used to quickly adjust the aircraft attitude or emergency brake, while discharging the generated energy flow:

[0060] Solution 1: Charging only through the battery. In this case, both the charging power and charging current must meet the battery limit.

[0061] Solution 2: Discharge only through the bleeder resistor;

[0062] Solution 3: In working conditions 2 and 3, the driving power of the motor that originally outputs positive torque can be increased to make the driving power greater than the generating power;

[0063] Solution 4: In working condition 4, the three phases of the motor are short-circuited and braking is achieved through the generated short-circuit braking torque.

[0064] Compared with the prior art, which only discharges energy through battery charging or discharge resistors, this embodiment can implement different discharge methods for different working conditions, allowing the entire system to distribute the energy flow of the aircraft more reasonably and ensure that the entire electrical system will not affect the battery.

[0065] In this embodiment, the entire electrical system of the dual-rotor aircraft includes a battery, a controller, a three-phase full-bridge IGBT and a three-phase motor, the power supply end of the controller is electrically connected to the battery, and the controller controls the three-phase full-bridge IGBT to drive the three-phase motor. The three middle bridges of the three-phase full-bridge IGBT are respectively electrically connected to the three phases of the three-phase motor, and the three-phase motor is a three-phase motor with a star connection method.

[0066] In this embodiment, by turning on the upper bridge or lower bridge of the three-phase full-bridge IGBT, the UVW three-phases of the motor are physically short-circuited. At this time, the motor will generate a large current and corresponding braking force, but this part of the energy is consumed by the windings of the motor, and the energy will not be transmitted to the bus.

[0067] The current amplitude at this time is calculated as follows:

[0068] I=Phif / Ld

[0069] Among them, Phif is the rotor flux of the motor, the unit is Wb; Ld is the equivalent motor inductance of the d-axis, the unit is H.

[0070] The braking torque generated is calculated by dividing the generated energy by the speed, so the energy consumption is calculated first:

[0071] P=P_cu+P_fe

[0072] Among them, P_cu is the motor copper loss; P_fe is the motor iron loss.

[0073] P_cu=3*I*I*Rs

[0074] Where Rs is the motor resistance.

[0075] Since the calculation of motor iron loss is very complicated and is related to the motor's electromagnetic scheme, temperature, and frequency, according to experience, the iron loss is estimated as half of the iron loss, so the motor energy loss can be obtained as:

[0076] P=1.5*3*I*I*Rs

[0077] The resulting braking torque is then calculated as follows:

[0078] Te=(1.5*3*I*I*Rs) / We

[0079] Where We is the electrical frequency of rotation of the motor.

[0080] Therefore, the negative torque Te output by the motor = 4.5 × (Phif / Ld) 2 ×Rs÷We.

[0081] The motor can be decelerated by a three-phase short circuit, without adding any additional hardware equipment, and without increasing the weight, volume, and cost of the product. By analyzing the energy flow under various working conditions and the system energy flow distribution strategy, energy flow processing under various complex working conditions can be achieved, thereby improving the responsiveness of the entire system and meeting the special needs of the aircraft. Under the premise of achieving the function, the safety of the entire system can be effectively protected and the service life of the product can be increased.

[0082] In the description of the embodiments of the present application, it should be noted that in the description of the present application, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description, and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application.

[0083] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0084] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for systematically distributing aircraft energy flow, characterized in that: The steps include: S1. Determine whether the motor of the aircraft outputs negative torque during flight; If yes, collect the total power generation P_sys of all motors that output negative torque, and go to step S2; otherwise, return to step S1; S2, judging whether the maximum charging power P_bat allowed by the battery is less than the total power generation power P_sys; If yes, proceed to step S3; otherwise, connect all motors that output negative torque to the battery to charge the battery; S3, judging whether the sum of the maximum charging power P_bat allowed by the battery and the maximum discharge power P_res allowed by the discharge resistor is less than the total power generation power P_sys; If yes, go to step S4; otherwise, go to step S5; S4, determining whether it is allowed to increase the driving power of the motor that outputs positive torque; If yes, the driving power of the motor that outputs positive torque is increased to (P_sys-P_bat-P_res), and the process goes to step S5; otherwise, the upper bridge or lower bridge of the three-phase full-bridge IGBT is fully turned on to short-circuit the three phases of the motor; S5. Connect all motors that output negative torque to the battery and the discharge resistor to charge the battery and discharge it through the discharge resistor.

2. The method for systematically distributing aircraft energy flow according to claim 1, characterized in that: The aircraft is a biplane aircraft, and the motor includes a first motor and a second motor. In step S1, it is determined whether the first motor or the second motor outputs a negative torque during the flight of the aircraft.

3. The method for systematically distributing aircraft energy flow according to claim 1, characterized in that: Each of the motors is a three-phase motor. The electrical system of the aircraft includes a battery, a controller, a three-phase full-bridge IGBT and a three-phase motor. The power supply end of the controller is electrically connected to the battery, the output end of the controller is electrically connected to the three-phase full-bridge IGBT, and the three intermediate bridges of the three-phase full-bridge IGBT are respectively electrically connected to the three phases of the three-phase motor. The three-phase motor is a star-connected three-phase motor.

4. The method for systematically distributing aircraft energy flow according to claim 3, characterized in that: Negative torque Te output by the motor = 4.5 × (Phif / Ld) 2 ×Rs÷We; Among them, Phif is the rotor flux of the motor, Ld is the equivalent motor inductance of the d-axis, Rs is the motor resistance, and We is the rotational electrical frequency of the motor.

Images