Aircraft electric brake pressure closed-loop control method and device

Abstract

The invention provides an aircraft electric brake pressure closed-loop control method and device, improves an existing brake pressure single-loop control method, and solves the technical problem that a brushless direct current motor is poor in control precision and reliability. The method comprises the following steps: forming a pressure closed-loop control process by using a pressure target value and a brake pressure feedback value; planning a pressure output curve, and adjusting the change rate of a pressure target value; performing amplitude limiting control on the current output by the inverter according to a current amplitude limiting rule; limiting the voltage output by the inverter according to a voltage limit value formed by a current amplitude limiting control algorithm to form a final control voltage; a PWM signal sequence is formed according to the final control voltage output in the pressure closed-loop control process, and the voltage and current output by an inverter are controlled. Motor current amplitude limiting can be carried out without high-precision current sampling, the motor current can be effectively prevented from being large, and power devices such as an MOSFET of a motor inverter cannot be damaged. The response speed and the practicability are high.

Description

Technical Field

[0001] The present invention relates to the technical field of brake technology, and in particular to a closed-loop control method and device for aircraft electric brake pressure. Background Art

[0002] The brake system is one of the important subsystems of the aircraft. It brakes and corrects the aircraft when it lands. The performance directly affects the safety of the aircraft. Traditional aircraft brake systems usually use hydraulic systems, which have poor maintainability and repairability. Aircraft all-electric brakes are a new braking concept that uses electrical energy as the source of braking energy. A full-electric brake system structure is as follows: Figure 1 As shown in the figure, the brake controller collects brake force feedback signals through pressure sensors, collects motor rotor position signals through Hall sensors, receives brake force target value signals and motor current signals, performs brake pressure closed-loop control, outputs pulse width modulation (PWM) signals, controls the rotation of brushless DC motors through inverters, drives electric actuators to squeeze brake discs to output brake force, and achieves braking of aircraft wheels. The fully electric brake replaces the hydraulic actuator with an electric mechanism, and uses cables instead of hydraulic lines, avoiding the risk of hydraulic oil leakage and greatly improving the safety and maintainability of the brake system.

[0003] In the prior art, a three-loop control structure of brake force, speed, and current is proposed, and the three loops all adopt PI control algorithm. Through simulation comparison, it can be seen that the three-loop control structure has a higher bandwidth, and the control effect is better than the pressure single closed-loop control technology and the pressure and current double closed-loop control technology. This algorithm has a good control effect in theory and simulation. However, the three-loop cascade control structure is not only complex, but also has many adjustable control parameters. In practical applications, the brake system generally uses a brushless DC motor equipped with a switch-type Hall position sensor. The system is affected by factors such as the low accuracy of the Hall position sensor, the low acquisition accuracy of the current sensor, and the large torque pulsation of the six-step commutation control method. The speed and current control accuracy of the inner loop is low, especially in the case of low pressure. The control accuracy is worse, which ultimately leads to the poor actual use effect of the three-loop control of brake pressure. Although the control algorithm is simple, the single-loop control method of brake pressure is easy to cause pressure overshoot, the motor current is oscillating, and overcurrent is prone to occur, which may damage power devices such as MOSFET in the inverter. Summary of the invention

[0004] In view of the above problems, an embodiment of the present invention provides an aircraft electric brake pressure closed-loop control method and device, which improves the existing brake pressure single-loop control method and solves the technical problems of poor control accuracy and reliability of brushless DC motors.

[0005] The closed-loop control method of aircraft electric brake pressure according to an embodiment of the present invention comprises:

[0006] The pressure closed-loop control process is formed by using the pressure target value and the brake pressure feedback value;

[0007] Plan the pressure output curve and adjust the change rate of the pressure target value;

[0008] The current output by the inverter is limited according to the current limiting rule;

[0009] The voltage output by the inverter is limited according to the voltage limit value formed by the current limiting control algorithm to form a final control voltage;

[0010] The final control voltage outputted by the pressure closed-loop control process forms a PWM signal sequence to control the voltage and current outputted by the inverter.

[0011] In one embodiment of the present invention, the pressure closed-loop control process calculates the difference by comparing the pressure target value and the feedback pressure value, and calculates the output voltage using proportional-integral-differential control.

[0012] In one embodiment of the present invention, the pressure output curve is as follows:

[0013] F e =(F T -F * [k-1]) / T s

[0014]

[0015] F * [k] = P * [k-1]+F e ·T s

[0016] Among them, F e is the pressure change rate, F T is the pressure target value, Ts is the calculation period, F * [k-1] is the pressure command value of the previous calculation cycle, F * [k] is the reset pressure command value. slope is the value of the rate of change parameter.

[0017] In one embodiment of the present invention, the change rate parameter value includes a rising rate and a falling rate, and the rising rate is smaller than the falling rate.

[0018] In one embodiment of the present invention, the process of limiting the current output by the inverter includes:

[0019] Compare the difference between the positive current limit value Ip and the motor feedback current value i, and use the proportional integral PI control algorithm to calculate the output voltage upper limit value Up;

[0020] Compare the difference between the negative current limit value In and the motor feedback current value i, and use the proportional integral PI control algorithm to calculate the output voltage lower limit value Un.

[0021] In one embodiment of the present invention, the process of limiting the voltage output by the inverter includes:

[0022] Compare the difference between the pressure command value F* and the brake pressure feedback value F, and use the proportional integral PI control algorithm to calculate the control voltage U output by the inverter;

[0023] According to the voltage upper limit value Up and voltage lower limit value Un output by the current limiting control, the control voltage U is limited to form the final control voltage U*. The formula is as follows:

[0024] U*=max(min(U,Up),Un)

[0025] Among them, min() is the minimum function, and max() is the maximum function.

[0026] In one embodiment of the present invention, the PWM duty cycle formula is as follows:

[0027]

[0028] U dc Indicates the power bus voltage; the final control voltage U* includes the motor rotation direction. When the final control voltage U* is greater than 0, the motor rotates forward, and when the voltage U* is less than 0, the motor rotates reversely.

[0029] The aircraft electric brake pressure closed-loop control device according to the embodiment of the present invention comprises:

[0030] A memory for storing program codes in the process of processing the closed-loop control method for electric brake pressure of an aircraft as claimed in any one of claims 1 to 7;

[0031] A processor is used to execute the program code.

[0032] The aircraft electric brake pressure closed-loop control device according to the embodiment of the present invention comprises:

[0033] The basic closed-loop establishment module is used to form a pressure closed-loop control process using the pressure target value and the pressure feedback value of the brake disc;

[0034] The pressure target optimization module is used to plan the pressure output curve and adjust the change rate of the pressure target value;

[0035] A current limit control module, used to perform current limit control of the inverter output according to the current signal feedback value of the inverter and the current limit rule;

[0036] A voltage limiting output module is used to limit the voltage output by the inverter according to the voltage limit value formed by the current limiting control algorithm to form a final control voltage;

[0037] The power signal generation module is used to form a PWM signal sequence according to the final control voltage output by the pressure closed-loop control process to control the voltage and current output by the inverter.

[0038] The aircraft electric brake pressure closed-loop control method and device of the embodiment of the present invention adopts brake pressure curve planning and current limit control based on the pressure closed-loop control structure to ensure that the brake has high control accuracy and practicality. The motor current only participates in the current limit control and does not participate in the pressure closed-loop regulation. Even if the motor current sensor has low accuracy, it will not affect the brake pressure control accuracy. The motor current can be limited without high-precision current sampling, which can effectively prevent the motor current from being large and will not cause damage to power devices such as MOSFET of the motor inverter. It has fast response speed and high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Shown is a schematic diagram of the architecture of the all-electric brake system structure used in the present invention.

[0040] Figure 2 FIG. 1 is a flow chart of a closed-loop control method for electric brake pressure of an aircraft according to an embodiment of the present invention.

[0041] Figure 3 FIG. 1 is a schematic diagram of signal transmission of a closed-loop control method for aircraft electric brake pressure according to an embodiment of the present invention.

[0042] Figure 4 FIG. 1 is a schematic diagram showing a comparison between a brake pressure command and a pressure feedback value simulation in a closed-loop control method for electric brake pressure of an aircraft according to an embodiment of the present invention.

[0043] Figure 5 FIG. 1 is a schematic diagram showing the effect of a motor current limiting simulation in a closed-loop control method for aircraft electric brake pressure according to an embodiment of the present invention.

[0044] Figure 6 FIG. 1 is a schematic diagram of the architecture of an aircraft electric brake pressure closed-loop control device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention clearer and more understandable, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] A closed-loop control method for aircraft electric brake pressure according to an embodiment of the present invention is as follows Figure 2 As shown. Figure 2 In this embodiment, the present invention comprises:

[0047] Step 100: Using the pressure target value and the brake pressure feedback value to form a pressure closed-loop control process.

[0048] Those skilled in the art can understand that the pressure target value refers to the target pressure expected to be achieved for braking (acting on the brake disc). In theory, the control data of the corresponding control structure is formed according to the pressure target value to control the formation of the corresponding target pressure. The pressure closed-loop control process formed by the pressure target value and the pressure feedback value of the brake disc working condition can establish the signal transmission architecture foundation of the feedback-control closed loop with rapid feedback and a single control amount. The single pressure closed-loop control process can ensure the reliability of the feedback-control closed loop, and the requirements for the number and type of configurations of high-precision sensors are relatively low, but pressure overshoot and motor current oscillation are prone to occur.

[0049] Step 200: Plan the pressure output curve and adjust the change rate of the pressure target value.

[0050] By planning the pressure output curve between the pressure command value and the pressure target value, a change rate limit for the pressure target value is formed, avoiding the inherent defects of the existing control, such as pressure overshoot and motor current oscillation, so that the motor current change amplitude is smaller and smoother.

[0051] Step 300: performing a current limiting control on the current output by the inverter according to a current limiting rule.

[0052] By controlling the upper and lower limits of the current signal output by the inverter, overcurrent in the inverter can be avoided. The upper and lower limit control values ​​are set in combination with the output current capacity of the motor and the output current capacity of the inverter power device.

[0053] Step 400: limiting the voltage output by the inverter according to the voltage limit value formed by the current limiting control algorithm to form a final control voltage.

[0054] The limited current signal is converted and adjusted by the algorithm to form a corresponding voltage limit value, and the voltage limit value is used to form the final control voltage output by the inverter. The voltage value output by the inverter is the voltage value input to the motor winding.

[0055] Step 500: A PWM signal sequence is formed according to the final control voltage outputted by the pressure closed-loop control process to control the voltage and current outputted by the inverter.

[0056] The pressure closed-loop control process outputs a voltage control signal, which is converted into a PWM signal sequence output. The inverter forms a power signal based on the PWM signal. Combined with the conventional six-step commutation control method, it is input into the motor winding of the brushless DC motor, adjusts the output torque and speed of the brushless DC motor, and drives the brake device to output braking force.

[0057] The aircraft electric brake pressure closed-loop control method of the embodiment of the present invention adopts brake pressure curve planning and current limit control based on the pressure closed-loop control structure to ensure that the brake has high control accuracy and practicality. The motor current only participates in the current limit control and does not participate in the pressure closed-loop regulation. Even if the motor current sensor has low accuracy, it will not affect the brake pressure control accuracy. The motor current can be limited without high-precision current sampling, which can effectively prevent the motor current from being large and will not cause damage to power devices such as the motor and inverter MOSFET. It has fast response speed and high practicality.

[0058] The signal transmission of the closed-loop control method of aircraft electric brake pressure according to one embodiment of the present invention is as follows Figure 3 As shown. Combined Figure 2 and Figure 3 As shown, in one embodiment of the present invention, in step 100, the pressure closed-loop control process compares the pressure target value F T The difference is calculated from the feedback pressure value F, and the output voltage U is calculated using proportional integral differential control (PID), which forms the motor winding voltage value.

[0059] The aircraft electric brake pressure closed-loop control method of the embodiment of the present invention first forms a pressure closed-loop control algorithm, establishes a basic pressure feedback control process, and forms a simple and reliable single phase-locked loop control structure.

[0060] Combination Figure 2 and Figure 3 As shown, in one embodiment of the present invention, in step 200, a pressure function of a dependent variable and an independent variable is formed between the pressure command value and the pressure target value to form a pressure output curve, and the pressure command value is used to limit the change rate of the pressure target value. After the pressure output curve is planned, the pressure target value is replaced by the pressure command value. The function expression of the pressure output curve is as follows:

[0061] F e =(F T -F * [k-1]) / T s

[0062]

[0063] F * [k] = P * [k-1]+F e ·Ts

[0064] Among them, F e is the pressure change rate, F T is the pressure target value, Ts is the calculation period, F * [k-1] is the pressure command value of the previous calculation cycle, F * [k] is the reset pressure command value. slope It is the change rate parameter value, which is set according to the performance requirements of the brake system. It can be set to two different values: rising rate and falling rate. The pressure rising rate is generally set smaller than the falling rate.

[0065] The aircraft electric brake pressure closed-loop control method of the embodiment of the present invention optimizes the change rate of the pressure target value through the pressure curve, and uses an alternative pressure command value to avoid overshoot in the pressure closed-loop control process, thereby achieving smoother motor current adjustment amplitude and more stable braking torque.

[0066] Combination Figure 2 and Figure 3 As shown, in one embodiment of the present invention, in step 300, the process of limiting the current output by the inverter according to the current limiting rule includes:

[0067] Compare the difference between the positive current limit value Ip and the motor feedback current value i, and use the proportional integral PI control algorithm to calculate the output voltage upper limit value Up;

[0068] Compare the difference between the negative current limit value In and the motor feedback current value i, and use the proportional integral PI control algorithm to calculate the output voltage lower limit value Un.

[0069] The motor feedback current value i is the output current value of the inverter, and the positive current limit and the negative current limit refer to controlling the upper limit and lower limit of the motor winding current respectively.

[0070] The current limit value is set based on the output current capability of the motor and the output current capability of the inverter power device. In one embodiment of the present invention, the positive current limit value Ip takes the minimum of the above two values, and leaves a certain margin, In = -Ip (Ip>0).

[0071] The closed-loop control method for aircraft electric brake pressure of the embodiment of the present invention ensures the operating reliability of the power device through the adaptation of current limiting and power device, and avoids the potential cost of using a high-sensitivity sensor.

[0072] Combination Figure 2 and Figure 3 As shown, in one embodiment of the present invention, in step 400, the process of limiting the voltage output by the inverter by the current limit control algorithm includes:

[0073] Compare the difference between the pressure command value F* and the brake pressure feedback value F, and use the proportional integral PI control algorithm to calculate the control voltage U output by the inverter;

[0074] According to the voltage upper limit value Up and voltage lower limit value Un output by the current limiting control, the control voltage U is limited to form the final control voltage U*. The formula of the final control voltage U* is expressed as follows:

[0075] U*=max(min(U,Up),Un)

[0076] Among them, min() is the minimum function, and max() is the maximum function.

[0077] The aircraft electric brake pressure closed-loop control method of the embodiment of the present invention utilizes the current limiting state to directly form the voltage control condition, thereby avoiding the complexity of the sensor configuration and the circuit structure.

[0078] Combination Figure 2 and Figure 3 As shown, in one embodiment of the present invention, in step 500, the final control voltage U* is converted into a PWM signal output, and the PWM duty cycle calculation formula is as follows:

[0079]

[0080] In the above formula, U dc Indicates the power bus voltage; the final control voltage U* sign includes the motor rotation direction. When the final control voltage U* is greater than 0, the motor rotates forward, and when the final control voltage U* is less than 0, the motor rotates reversely.

[0081] The PWM signal is amplified by the inverter and combined with the six-step commutation control method to adjust the output torque and speed of the brushless DC motor and drive the brake device to output braking force.

[0082] The closed-loop control method for aircraft electric brake pressure of the embodiment of the present invention ensures the control accuracy of the output electric power signal through the PWM signal, so that the control performance is guaranteed.

[0083] The comparison of the brake pressure command and the pressure feedback value simulation in the closed-loop control method of the aircraft electric brake pressure in one embodiment of the present invention is as follows: Figure 4 As shown. Figure 4 In the simulation, a certain type of electric brake control system is taken as an example. According to the braking response requirements, the brake pressure command change rate is set to 20Mpa / s, and the motor winding current limit value is 30A. In the simulation results, the brake pressure command value formed by the pressure target value after the pressure planning curve is optimized is basically synchronized with the pressure feedback value of the brake disc, and there is no pressure over-adjustment phenomenon.

[0084] The motor current limit simulation in the closed-loop control method of aircraft electric brake pressure in one embodiment of the present invention is as follows Figure 5 As shown. Figure 5 In the process, the electrode current intensity is kept within the positive and negative current limiting amplitude range, and the control process is stable and reliable.

[0085] An aircraft electric brake pressure closed-loop control device according to an embodiment of the present invention comprises:

[0086] A memory, used to store program codes in the process of processing the closed-loop control method for electric brake pressure of an aircraft in the above embodiment;

[0087] The processor is used to execute the program code in the processing of the aircraft electric brake pressure closed-loop control method in the above embodiment.

[0088] The processor may be a DSP (Digital Signal Processor) digital signal processor, an FPGA (Field-Programmable Gate Array) field programmable gate array, an MCU (Microcontroller Unit) system board, a SoC (system on a chip) system board, or a PLC (Programmable Logic Controller) minimum system including I / O.

[0089] An aircraft electric brake pressure closed-loop control device according to an embodiment of the present invention is as follows Figure 6 As shown. Figure 6 In this embodiment, the present invention comprises:

[0090] A basic closed-loop establishing module 10 is used to form a pressure closed-loop control process using a pressure target value and a brake pressure feedback value;

[0091] The pressure target optimization module 20 is used to plan the pressure output curve and adjust the change rate of the pressure target value;

[0092] A current limit control module 30, used for controlling the current limit output by the inverter according to the current limit rule;

[0093] A voltage limiting output module 40 is used to limit the voltage output by the inverter according to the voltage limit value formed by the current limiting control algorithm to form a final control voltage;

[0094] The power signal generating module 50 is used to form a PWM signal sequence according to the final control voltage outputted by the pressure closed-loop control process, so as to control the voltage and current outputted by the inverter.

[0095] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention 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 by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A closed-loop control method for aircraft electric brake pressure, characterized in that: include: The pressure closed-loop control process is formed by using the pressure target value and the brake pressure feedback value; Plan the pressure output curve and adjust the change rate of the pressure target value; The current output by the inverter is limited according to the current limiting rule; The voltage output by the inverter is limited according to the voltage limit value formed by the current limiting control algorithm to form a final control voltage; The final control voltage outputted by the pressure closed-loop control process forms a PWM signal sequence to control the voltage and current outputted by the inverter.

2. The closed-loop control method for aircraft electric brake pressure according to claim 1, characterized in that: The pressure closed-loop control process calculates the difference by comparing the pressure target value and the feedback pressure value, and calculates the output voltage by using proportional-integral-differential control.

3. The closed-loop control method for aircraft electric brake pressure according to claim 1, characterized in that: The pressure output curve is as follows: F e =(F T -F * [k-1]) / T s F * [k]=P * [k-1]+F e ·t s Among them, F e is the pressure change rate, F T is the pressure target value, Ts is the calculation period, F * [k-1] is the pressure command value of the previous calculation cycle, F * [k] is the reset pressure command value. slope is the value of the rate of change parameter.

4. The closed-loop control method for aircraft electric brake pressure as claimed in claim 3, characterized in that: The change rate parameter value includes a rising rate and a falling rate, and the rising rate is smaller than the falling rate.

5. The closed-loop control method for aircraft electric brake pressure according to claim 1, characterized in that: The process of limiting the current output by the inverter includes: Compare the difference between the positive current limit value Ip and the motor feedback current value i, and use the proportional integral PI control algorithm to calculate the output voltage upper limit value Up; Compare the difference between the negative current limit value In and the motor feedback current value i, and use the proportional integral PI control algorithm to calculate the output voltage lower limit value Un.

6. The closed-loop control method for aircraft electric brake pressure as claimed in claim 1, characterized in that: The process of limiting the voltage output by the inverter includes: Compare the difference between the pressure command value F* and the brake pressure feedback value F, and use the proportional integral PI control algorithm to calculate the control voltage U output by the inverter; According to the voltage upper limit value Up and voltage lower limit value Un output by the current limiting control, the control voltage U is limited to form the final control voltage U*. The formula is as follows: U*=max(min(U,Up),Un) Among them, min() is the minimum function, and max() is the maximum function.

7. The closed-loop control method for aircraft electric brake pressure as claimed in claim 1, characterized in that: The PWM duty cycle formula is as follows: U dc Indicates the power bus voltage; the final control voltage U* includes the motor rotation direction. When the final control voltage U* is greater than 0, the motor rotates forward, and when the voltage U* is less than 0, the motor rotates reversely.

8. An aircraft electric brake pressure closed-loop control device, characterized in that: include: A memory for storing program codes in the process of processing the closed-loop control method for electric brake pressure of an aircraft as claimed in any one of claims 1 to 7; A processor is used to execute the program code.

9. An aircraft electric brake pressure closed-loop control device, characterized in that: include: The basic closed-loop establishment module is used to form a pressure closed-loop control process using the pressure target value and the brake pressure feedback value; The pressure target optimization module is used to plan the pressure output curve and adjust the change rate of the pressure target value; A current limiting control module, used for controlling the current limiting of the inverter output according to the current limiting rule; A voltage limiting output module is used to limit the voltage output by the inverter according to the voltage limit value formed by the current limiting control algorithm to form a final control voltage; The power signal generation module is used to form a PWM signal sequence according to the final control voltage output by the pressure closed-loop control process to control the voltage and current output by the inverter.

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