Anti-interference variable load stable control method for electromechanical servo system

Abstract

The invention provides an anti-interference variable load stable control method for an electromechanical servo system, which adopts different control algorithms for an ascending section and a descending section of a load, and adopts a single chopping modulation mode of a motor when a potential load ascends. When the load is reduced, a single-chopping modulation and double-chopping modulation combined mode is adopted, when the motor is in a motor state, the single-chopping modulation mode is adopted, when the motor is in a generator state, the double-chopping modulation mode is adopted, and segmented PID control is combined, so that stable control under the potential load and power generation state is realized; and the robustness of the product is improved. The system adapts to underwater and ground environments, has relatively high anti-interference performance, is suitable for potential loads, and switches a PWM modulation mode according to whether the motor is in a generator state or not, so that the motor stably ascends and descends; the method can be suitable for being popularized to all aerospace electromechanical servo systems with potential load characteristic requirements, and has universality.

Description

Technical Field

[0001] The invention belongs to the technical field of ship electromechanical servo system control, and in particular relates to a ship electromechanical servo system control method. Background Art

[0002] Brushless DC motors have the advantages of good speed regulation, high power density, and high efficiency, and are widely used in electromechanical servo systems. However, since the current cannot change suddenly during commutation, it will produce additional torque pulsation components, affecting the stability of the control system.

[0003] The document "Torque Pulsation Suppression of Brushless DC Motors under PWM Modulation" analyzes the effects of different pulse width modulation methods on the electromagnetic torque of brushless DC motors. The brushless DC motors analyzed in the article are all in the motor state, but in actual work, due to the heavy load of the aircraft servo system, the motor may work in the generator state. When the motor is in the power generation state, the forward and reverse switching process of the motor is likely to cause instability in the control system.

[0004] At present, in the field of shipbuilding, the research object of electromechanical servo systems is mostly the rudder system of the aircraft, involving Chinese patent CN102323820A, named an intelligent rudder system and its control method, which detects the actual position and heading of the ship based on the navigator on the hull and the three-dimensional electronic compass combined navigator to perform closed-loop control of the rudder. The advantage is that it can respond quickly according to the navigation status of the ship and realize real-time closed-loop control of the rudder. However, this method has the following main problems:

[0005] (1) The motors of the intelligent rudder system are all in the motor state. This method cannot adapt to the situation where the control object is a potential load, that is, the motor works in the power generation state;

[0006] (2) The working state of the intelligent rudder system is adjusted in real time according to the state of the ship, and has the characteristics of fast response speed. This method cannot meet the requirements of stable operation of the control object. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an anti-interference variable load stable control method for an electromechanical servo system. When the motor is in the motor state, a single chop modulation method is adopted, and when the motor is in the generator state, a double chop modulation method is adopted, and combined with segmented PID control, the load is a potential load, and the stable control in the power generation state is achieved, and the robustness of the product is improved. It is suitable for both underwater and ground environments and has strong anti-interference.

[0008] The present invention provides an anti-interference variable load stable control method for an electromechanical servo system. The electromechanical servo system comprises: a controller, a brushless DC motor, a mechanical output mechanism, an angular displacement sensor, and a load. The method comprises: when the brushless DC motor is in a motor state, a single-chop modulation mode is adopted; when the motor is in a generator state, a double-chop modulation mode is adopted. The double-chop modulation mode is that when the controller is in each conduction state, all power tubes of the upper and lower bridge arms are subjected to PWM modulation; the single-chop modulation mode is that when the controller is in each conduction state, only one power tube of the upper bridge arm or the lower bridge arm is subjected to PWM modulation.

[0009] The beneficial effects of the present invention are as follows:

[0010] 1. The present invention is suitable for both underwater and ground environments and has strong anti-interference performance;

[0011] 2. The present invention is applicable to potential loads. According to whether the motor is in the generator state, the PWM modulation mode is switched to make it rise and fall smoothly;

[0012] 3. The present invention can be applied to aerospace electromechanical servo systems with characteristic requirements for all potential loads and has universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention:

[0014] Figure 1 It is a load platform for lifting and lowering antennas of aircraft;

[0015] Figure 2 It is a brushless DC motor drive circuit;

[0016] Figure 3 It is a schematic diagram of the double chop modulation method;

[0017] Figure 4 It is a schematic diagram of single chop modulation mode;

[0018] Figure 5 It is a flow chart of the control method. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0021] like Figure 1 As shown, an aircraft lifting antenna load platform, the aircraft servo system is centered on the controller, driving the brushless DC motor to drive the load up and down, and the load is raised and lowered between parallel to the ground (i.e., the angle with the ground is 0 degrees) and perpendicular to the ground (i.e., the angle with the ground is 90 degrees).

[0022] like Figure 2 As shown in the figure, a brushless DC motor drive circuit is used. The brushless DC motor cooperates with the rotor position sensor through an electronic commutator to control the conduction time and power-on sequence of each phase winding of the stator. V1~V6 are power tubes, and VD1~VD6 are freewheeling diodes. Brushless DC motors often adopt a two-two conduction, three-phase six-state conduction method. According to the number of PWM action tubes in each conduction state, PWM modulation methods can be divided into two types, "double chop" modulation method and "single chop" modulation method. In the "double chop" modulation method, the power tubes of the upper and lower bridge arms are all PWM modulated in each conduction state of the controller, such as Figure 3 The "single chopping" modulation mode is that when the controller is in each conduction state, only one power tube of the upper bridge arm or the lower bridge arm performs PWM modulation, such as Figure 4 shown.

[0023] like Figure 5 The figure shows a flow chart of the control method. The control system software adopts different control algorithms for the rising and falling sections of the load. When the potential load rises, the work done by gravity is opposite to the direction of the load movement, and the motor is in the motor state. Therefore, the rising section adopts the single-chop modulation method of the motor. When the load is falling, the work done by gravity is in the same direction as the load movement. Due to the effect of gravity, the load will work in the power generation state, and the forward and reverse switching process of the motor is likely to cause instability of the control system; in order to make the load fall smoothly, the falling section adopts a combination of single-chop modulation and double-chop modulation. When the motor is in the motor state, the single-chop modulation method is adopted, and when the motor is in the generator state, the double-chop modulation method is adopted.

[0024] The specific steps are as follows:

[0025] (1) Determine whether the potential load is in the ascending stage. If the load is in the ascending stage, the work done by gravity is opposite to the direction of load movement, and the motor is in the motor state. The ascending stage adopts the single-chop modulation mode of the motor and adopts the position-speed dual closed-loop control algorithm.

[0026] (2) According to the result of step (1), the load is in the ascending section, and it is determined whether the load has reached the maximum position, which is 90 degrees in the present invention. If the load has not reached the maximum position, the PID parameters are assigned to make the load run at an appropriate speed; if the load reaches the maximum position, the PID parameters are reduced to decelerate the load and slowly reach the target position.

[0027] The position loop parameters of the present invention are as follows: when the load position is less than 89 degrees, the speed command is equal to 110 r / min; when the load position is greater than 89 degrees, the speed command is equal to 0. The PID parameters are Kp=20.0; Ki=0.0; Kd=0.0.

[0028] The speed loop parameters of the present invention are as follows: when the load position is less than 89 degrees, the PID parameters are Kp=20.0; Ki=0.0; Kd=0.0. When the load position is greater than 89 degrees, the PID parameters are Kp=5.0; Ki=0.0; Kd=0.0.

[0029] (3) According to the result of step (1), determine whether the potential load is in the descending stage. If it is in the descending stage, determine whether the motor is in the generating state. When the motor is in the motor state, a single chop modulation method is used. When the motor is in the generator state, a double chop modulation method is used. The descending stage adopts the position-speed dual closed-loop control algorithm.

[0030] (4) When the load is in the descending section, it is determined whether the load has reached the target. The present invention is 0 degrees. If the load has not reached the target, the PID parameters are assigned to make the load run at an appropriate speed. If the load reaches the target, the PID parameters are reduced to decelerate the load and slowly reach the target position.

[0031] The position loop parameters of the present invention are as follows: when the load position is greater than 20 degrees, the speed command is equal to -110r / min; when the load position is less than 20 degrees and greater than 1 degree, the speed command is equal to -50r / min; when the load position is less than 1 degree, the speed command is equal to 0r / min.

[0032] The speed loop parameters of the present invention are as follows: when the load position is from 90 degrees to 75 degrees, the proportional gain is Kp=25.0; Ki=0.0; Kd=0.0; when the load position is from 75 degrees to 0 degrees, Kp is increased from 5 to 25 using 5S, Ki=0.0, Kd=0.0; and then decreased from 25 to 5 using 5S, Ki=0.0001, Kd=0.0.

[0033] (5) The output values ​​calculated in step (2) and step (4) are output step-limited to ensure that the output value does not change significantly each time. The output change value of the present invention is less than 0.0002 of the previous output value each time. The closed-loop cycle of the servo system is 0.5 ms, that is, it takes 0.25 s to reach the given value of the output value.

[0034] (6) The output value calculated in step (5) is limited to ensure that the output value of the servo system is within the required range. The output limit value of the present invention is 65% of the maximum value.

[0035] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for anti-interference variable load stable control of an electromechanical servo system, characterized in that: The electromechanical servo system includes: a controller, a brushless DC motor, a mechanical output mechanism, an angular displacement sensor, and a load; the method includes: when the brushless DC motor is in a motor state, a single-chop modulation method is adopted, and when the motor is in a generator state, a double-chop modulation method is adopted; the double-chop modulation method is that when the controller is in each conduction state, all the power tubes of the upper and lower bridge arms are subjected to PWM modulation, and the single-chop modulation method is that when the controller is in each conduction state, only one power tube of the upper bridge arm or the lower bridge arm is subjected to PWM modulation.

2. The anti-interference variable load stable control method of an electromechanical servo system according to claim 1 is characterized in that: Different control algorithms are adopted for the rising and falling sections of the load. When the potential load rises, the work done by gravity is opposite to the direction of load movement, the motor is in the motor state, and the single-chop modulation method of the motor is adopted in the rising section; when the load decreases, it is determined whether the motor is in the power generation state. When the motor is in the motor state, the single-chop modulation method is adopted, and when the motor is in the generator state, the double-chop modulation method is adopted.

3. The anti-interference variable load stable control method of an electromechanical servo system according to claim 2 is characterized in that: The specific steps are as follows: (1) Determine whether the potential load is in the ascending stage. If the load is in the ascending stage, the work done by gravity is opposite to the direction of load movement, the motor is in the motor state, and the ascending stage adopts the single-chop modulation mode of the motor and adopts the position-speed dual closed-loop control algorithm; (2) According to the result of step (1), the load is in the ascending stage, and it is determined whether the load has reached the maximum position, which is 90 degrees in the present invention. If the load has not reached the maximum position, the PID parameters are assigned to make the load run at an appropriate speed; if the load reaches the maximum position, the PID parameters are reduced to decelerate the load and slowly reach the target position; (3) According to the result of step (1), determine whether the potential load is in the descending stage. If it is in the descending stage, determine whether the motor is in the generating state. When the motor is in the motor state, a single chopping modulation method is adopted. When the motor is in the generator state, a double chopping modulation method is adopted. The descending stage adopts a position-speed dual closed-loop control algorithm. (4) When the load is in the descending section, it is determined whether the load has reached the target. The present invention is 0 degrees. If the load has not reached the target, the PID parameters are assigned to make the load run at an appropriate speed. If the load reaches the target, the PID parameters are reduced to decelerate the load and slowly reach the target position. (5) performing output step limiting on the output values ​​calculated in step (2) and step (4) to ensure that the output values ​​do not change significantly each time; (6) The output value calculated in step (5) is limited to ensure that the output value of the servo system is within the required range.

4. The anti-interference variable load stable control method of an electromechanical servo system according to claim 3 is characterized in that: Each output change is less than 0.0002 of the previous one.

5. The anti-interference variable load stable control method of an electromechanical servo system according to claim 3 is characterized in that: The output amplitude limiting value of the present invention is 65% of the maximum value.

Images