Control method

Abstract

The invention provides a control method. The control method comprises the following steps: controlling a motor to start based on a rotating speed-current serial double closed-loop mode; and when the driving force and the loading force of the motor are balanced, switching to control the motor to work based on a pressure-current series-connection type double closed-loop mode or a position-current series-connection type double closed-loop mode. According to the configuration, on one hand, different control modes are used in different stages, and the overall complexity of the control scheme is reduced; on the other hand, the logic of the switching control sub-schemes is modified, so that the switching opportunity between the two control sub-schemes is more reasonable; the problem that in the prior art, the whole control scheme is complex or the switching opportunity of the control sub-schemes is unreasonable is solved. In one embodiment of the invention, when the difference value between the driving force and the load force is small, the output amplitude limiting of the current inner loop is triggered, and the stability during dynamic switching can be further improved.

Description

Technical Field

[0001] This invention relates to the field of thrust-type electric actuators, and in particular to a control method. Background Technology

[0002] Thrust-type electric actuators are widely used in industry, especially in the automotive sector, where they are commonly used as electronic clutches, active stabilizer bars, and electromechanical brakes. Their simple structure, rapid response, and precise drive force output are key reasons for their widespread adoption.

[0003] In applications where electric motors are used as drive mechanisms for thrust-type electric actuators, the control process typically includes a backlash elimination stage and a pressure following stage. For this control scenario, traditional control schemes include a full-process pressure-speed-current series three-loop control scheme and a control scheme that first uses a speed-current series two-loop control, then switches to a pressure-current series two-loop control.

[0004] Among them, the pressure-speed-current series three-loop control scheme can track the target pressure well, but due to the large number of closed-loop components, the system response delay increases. Simultaneously, coordinating and matching the control parameters of each component is difficult, increasing the complexity of controller design. A control scheme that first uses a speed-current series dual-loop control and then switches to a pressure-current series dual-loop control reduces the difficulty of coordinating and matching control parameters by eliminating one loop; however, the switching time between the two dual-loop control schemes becomes a crucial factor affecting the control performance. The commonly used switching point is the moment when the gap just disappears. However, at the moment the gap just disappears, the motor speed is often still increasing, and switching out of the speed-current series dual-loop control at this point affects the overall control process time. Furthermore, in traditional practices, the current inner loop is not limited during dynamic switching of control modes, leading to fluctuations in motor speed or current during dynamic switching, which in turn causes oscillations in the actuator system.

[0005] It is worth emphasizing that although the above content is a description of objective phenomena existing in the prior art, the summary of the above control schemes, especially the identification and formulation of technical problems, still contains the creative labor of the inventors.

[0006] In summary, existing technologies suffer from problems such as overly complex overall control schemes or unreasonable timing of switching between control sub-schemes, resulting in poor stability during switching. Summary of the Invention

[0007] The purpose of this invention is to provide a control method to solve the problems in the prior art where the overall control scheme is too complex or the timing of switching between control sub-schemes is unreasonable and the stability is poor during switching.

[0008] To address the aforementioned technical problems, this invention provides a control method applied to a thrust-type electric actuator, the thrust-type electric actuator including a motor; the control method includes: controlling the motor to start based on a speed-current series dual closed-loop method; and, when the driving force and load force of the motor are balanced, switching to controlling the motor to operate based on a preset control method.

[0009] The preset control method is either a pressure-current series dual closed-loop control method or a position-current series dual closed-loop control method.

[0010] Optionally, the step of controlling the motor start-up based on the speed-current series dual closed-loop method includes: setting the target speed to the maximum operating speed of the motor.

[0011] Optionally, the step of controlling the motor start-up based on the speed-current series dual closed-loop method includes: controlling the motor based on a field weakening control algorithm.

[0012] Optionally, when the difference between the driving force and the load force is within a first preset range, it is determined that the driving force and the load force are balanced.

[0013] Optionally, the step of controlling the motor start-up based on the speed-current series dual closed-loop method includes: when the difference between the driving force and the load force is within a second preset range, triggering the output limiting of the inner current loop.

[0014] Optionally, the output limiting value of the inner current loop decreases as the difference between the driving force and the load force decreases, and the output limiting value of the inner current loop increases as the difference between the driving force and the load force increases.

[0015] Optionally, the driving force is calculated based on the current of the motor, and the load force is calculated based on sensor feedback or the signal from sensor feedback.

[0016] Optionally, the load force is based on feedback from a clamping force sensor.

[0017] Optionally, the switching to the preset control mode occurs later than the time when the gap between the output of the thrust-type electric actuator and the load is eliminated.

[0018] Optionally, the speed-current series dual closed-loop method includes: controlling the target current based on the difference between the target speed and the actual speed of the motor, and controlling the current of the motor based on the difference between the target current and the actual current of the motor.

[0019] The pressure-current series dual closed-loop method includes: controlling the target current based on the difference between the target pressure and the actual thrust at the output end of the thrust-type electric actuator, and controlling the motor current based on the difference between the target current and the actual current.

[0020] The position-current series dual closed-loop method includes: controlling the target current based on the difference between the target position and the actual position of the output end of the thrust-type electric actuator, and controlling the motor current based on the difference between the target current and the actual current.

[0021] Compared with existing technologies, the control method provided by this invention includes: controlling motor startup based on a speed-current series dual closed-loop method; and, when the driving force and load force of the motor are balanced, switching to a pressure-current series dual closed-loop method or a position-current series dual closed-loop method to control the motor operation. This configuration, on the one hand, reduces the overall complexity of the control scheme by using different control methods at different stages; on the other hand, it modifies the logic of switching control sub-schemes, making the switching timing between the two control sub-schemes more reasonable; thus solving the problems of overly complex overall control schemes or unreasonable switching timing of control sub-schemes in existing technologies. In one embodiment of this invention, when the difference between the driving force and the load force is small, the output limiting of the inner current loop is triggered, which can further improve the stability during dynamic switching. Attached Figure Description

[0022] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0023] Figure 1 This is a schematic flowchart of a control method according to an embodiment of the present invention;

[0024] Figure 2 This is a control block diagram of a control method according to an embodiment of the present invention;

[0025] Figure 3 This is a control block diagram of a control method according to another embodiment of the present invention.

[0026] in:

[0027] 1- Switching stage; 2- Limiting stage. Detailed Implementation

[0028] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0029] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. “One end” and “the other end,” as well as “proximal end” and “distal end,” generally refer to two corresponding parts, including not only endpoints. The terms “installed,” “connected,” and “joined” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral part; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements or an interaction between two elements. Furthermore, as used in this invention, the phrase "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] The core idea of ​​this invention is to provide a control method to solve the problems in the prior art where the overall control scheme is too complex or the timing of switching between control sub-schemes is unreasonable and the stability is poor during switching.

[0031] The following description refers to the accompanying drawings.

[0032] Please refer to Figure 1 This embodiment provides a control method applied to a thrust-type electric actuator, which includes a motor.

[0033] The control method includes:

[0034] S10, the motor is started based on a speed-current series dual closed-loop control method.

[0035] S20, when the difference between the driving force and the load force of the motor is within a first preset range, it is determined that the driving force and the load force are balanced.

[0036] S30, when the driving force and load force of the motor are balanced, switch to control the motor operation based on pressure-current series dual closed-loop mode.

[0037] In other embodiments, in step S30, the pressure-current series dual closed-loop method can also be replaced by the position-current series dual closed-loop method.

[0038] The design considerations for the above scheme are as follows: This embodiment uses the balance between motor driving force and load force as the time point for dynamic switching between speed-current series dual closed-loop control and pressure-current series dual closed-loop control. Compared to the commonly used moment when the gap is just eliminated as the dynamic switching time point, this approach takes into account the characteristic that the motor speed can continue to increase due to the inertia of the actuator after the gap is just eliminated. When the motor driving force and load force reach balance, the motor speed is basically at its maximum. At this time, as the actuator moves further forward, the load force begins to exceed the motor driving force, and the motor speed begins to decrease. At this moment, the control switches to pressure-current series dual closed-loop control, allowing the actuator to quickly follow the target pressure. In specific implementation, the difference between the motor driving force and the load force can be within a small calibrated range as the dynamic switching time point, thereby enhancing the robustness of the switching and avoiding frequent switching from affecting the stability of the control.

[0039] This configuration, compared to the commonly used dynamic switching point where the gap is just eliminated, fully utilizes the characteristic that the motor speed can still be further increased when the gap is just eliminated, maximizing the use of the motor's maximum speed and minimizing the overall control time. Simultaneously, since the motor driving force and load force are balanced at this switching point, the control mode switching has a smaller impact on the system's dynamic response, which is beneficial to control stability. In other words, the switching time of the preset control mode is later than the moment the gap between the output end of the thrust-type electric actuator and the load is eliminated.

[0040] The motor outputs thrust to the load through mechanisms such as the speed reduction and torque amplification mechanism and the motion conversion mechanism. The clearance mentioned above refers to all clearances between the motor, the speed reduction and torque amplification mechanism, the motion conversion mechanism, and the load.

[0041] By switching between the two sub-schemes, the intermediate speed closed loop is eliminated compared to the pressure-speed-current series three-loop system. Therefore, the system delay can be shorter, allowing it to follow the target pressure more quickly and accurately to achieve the control target.

[0042] Specifically, step S10 includes: S11, setting the target speed to the maximum operating speed of the motor; S12, controlling the motor based on a field weakening control algorithm; and S13, triggering the output limiting of the inner current loop when the difference between the driving force and the load force is within a second preset range.

[0043] The purpose of steps S11 and S12 is to employ a speed-current series dual closed-loop control scheme during the actuator control gap elimination phase to minimize control time. This involves setting the target speed to the highest achievable speed of the motor. Simultaneously, a field weakening control algorithm is used to fully utilize the motor's performance and eliminate the gap in the shortest possible time. Step S13 aims to ensure stability during dynamic switching of the actuator control mode. Before the switching point, the output of the inner current loop is limited according to a certain rule. Upon reaching the dynamic switching point, since the output of the control loop has been suppressed to the maximum extent, seamless switching can be achieved, effectively solving the problem of motor speed and current fluctuations during switching and ensuring control stability. Specifically, a limiting function can be triggered when the difference between the motor driving force and the load force is less than a calibrated value. This limiting value changes with the magnitude of the difference, avoiding the influence of a fixed limiting value on the control response, thereby ensuring stability and responsiveness during dynamic switching of the control mode.

[0044] That is, the output limiting value of the inner current loop decreases as the difference between the driving force and the load force decreases, and increases as the difference between the driving force and the load force increases. The specific functional relationship between the limiting value and the difference can be set according to actual needs.

[0045] Please refer to Figure 2 The speed-current series dual closed-loop method includes: controlling the target current based on the difference between the target speed and the actual speed of the motor, and controlling the motor current based on the difference between the target current and the actual current of the motor; the pressure-current series dual closed-loop method includes: controlling the target current based on the difference between the target pressure and the actual thrust at the output end of the thrust-type electric actuator, and controlling the motor current based on the difference between the target current and the actual current.

[0046] Figure 2In this circuit, the operating logic of switching loop 1 is as follows: when Fm - Ff ≥ C1, the output signal of the speed loop is transmitted to the output terminal as the target current; when Fm - Ff < C1, the output signal of the pressure loop is transmitted to the output terminal as the target current. Fm represents the driving force, Ff represents the load force, and C1 represents the boundary condition of the first preset range d. It is understood that in other embodiments, the switching logic of switching loop 1 can be adaptively modified to meet different operational needs. Figure 2 In this circuit, the limiting circuit 2 works as follows: when the input signal is greater than or equal to the positive limiting value, it outputs the positive limiting value; when the input signal is less than or equal to the negative limiting value, it outputs the negative limiting value; otherwise, it outputs the input signal. The limiting circuit 2 is activated only when Fm - Ff ≤ C2. When the limiting circuit 2 is not activated, it can be understood that the output of the current loop is directly input to the thrust-type electric actuator. The positive and negative limiting values ​​are collectively referred to as the limiting value. The terms "increase" and "decrease" in the preceding text refer to increases and decreases in absolute value.

[0047] When the preset control mode is a position-current series dual closed-loop mode, it can be followed as follows: Figure 3 The content shown should be understood as follows. That is, the position-current series dual closed-loop method includes: controlling the target current based on the difference between the target position and the actual position of the output end of the thrust-type electric actuator, and controlling the motor current based on the difference between the target current and the actual current.

[0048] In one specific embodiment, the driving force is calculated based on the current of the motor, and the load force is based on sensor feedback, such as the load force being based on clamping force sensor measurement feedback.

[0049] This embodiment primarily targets the application of thrust-type electric actuators. To further shorten control time, it proposes an overall control framework that first switches to a speed-current series dual closed-loop control, and then switches to a pressure-current series dual closed-loop control. The dynamic switching point between the two control modes is defined as the equilibrium between the motor driving force and the load force. Simultaneously, the control output is limited according to a certain pattern before switching. Compared to traditional solutions, this embodiment has the following advantages:

[0050] 1. Compared to the full-process pressure-speed-current series three-loop control, the first-stage speed-current series two-loop control sets the target speed to its maximum, fully utilizing the advantages of the speed loop. Furthermore, the removal of the preceding pressure loop helps reduce system response delay, ultimately allowing the motor to quickly reach its maximum speed. The subsequent pressure-current series two-loop control, by eliminating the intermediate speed loop, also reduces system delay, facilitating faster tracking of the target pressure.

[0051] 2. Using the point where the motor driving force and load force reach equilibrium as the dynamic switching point between the two control modes, compared to the commonly used point where the gap is just eliminated, fully utilizes the characteristic that the motor speed can still be further increased when the actuator just eliminates the gap. This maximizes the use of the motor's maximum speed and minimizes the overall control time. Simultaneously, because the motor driving force and load force are balanced at this switching point, the impact of control mode switching on the system's dynamic response is minimal, which is beneficial to control stability.

[0052] 3. Before the dynamic switching of control modes, the current inner loop is triggered by the difference between the motor driving force and the load force. The limiting value changes according to a certain rule, which helps to ensure the stability of the actuator during switching and minimizes the impact on the control response time.

[0053] In summary, this embodiment provides a control method, including: controlling the motor startup based on a speed-current series dual closed-loop method; and, when the driving force and load force of the motor are balanced, switching to a pressure-current series dual closed-loop method or a position-current series dual closed-loop method to control the motor operation. This configuration, on the one hand, reduces the overall complexity of the control scheme by using different control methods at different stages; on the other hand, it modifies the logic of switching control sub-schemes, making the switching timing between the two control sub-schemes more reasonable; thus solving the problems of overly complex overall control schemes or unreasonable switching timing of control sub-schemes in existing technologies. In a preferred embodiment, when the difference between the driving force and the load force is small, the output limiting of the inner current loop is triggered, which can further improve the stability during dynamic switching.

[0054] The above description is only a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.

Claims

1. A control method, characterized in that, The method is applied to a thrust-type electric actuator, which includes a motor; the control method includes: The motor startup is controlled based on a speed-current series dual closed-loop method; and... When the driving force and load force of the motor are balanced, the motor is switched to be controlled based on a preset control mode. The preset control method is either a pressure-current series dual closed-loop control method or a position-current series dual closed-loop control method.

2. The control method according to claim 1, characterized in that, The steps for controlling the motor start-up based on the speed-current series dual closed-loop method include: setting the target speed to the maximum operating speed of the motor.

3. The control method according to claim 1, characterized in that, The steps for controlling the motor start-up based on the speed-current series dual closed-loop method include: controlling the motor based on the field weakening control algorithm.

4. The control method according to claim 1, characterized in that, When the difference between the driving force and the load force is within a first preset range, it is determined that the driving force and the load force are balanced.

5. The control method according to claim 1, characterized in that, The steps for controlling the motor start-up based on the speed-current series dual closed-loop method include: when the difference between the driving force and the load force is within a second preset range, the output limiting of the inner current loop is triggered.

6. The control method according to claim 5, characterized in that, The output limit value of the inner current loop decreases as the difference between the driving force and the load force decreases, and the output limit value of the inner current loop increases as the difference between the driving force and the load force increases.

7. The control method according to claim 1, characterized in that, The driving force is calculated based on the current of the motor, and the load force is calculated based on sensor feedback or the signal from sensor feedback.

8. The control method according to claim 7, characterized in that, The load force is based on the feedback from the clamping force sensor.

9. The control method according to claim 1, characterized in that, The switching to the preset control mode occurs later than the time when the gap between the output of the thrust-type electric actuator and the load is eliminated.

10. The control method according to claim 1, characterized in that, The speed-current series dual closed-loop method includes: controlling the target current based on the difference between the target speed and the actual speed of the motor, and controlling the current of the motor based on the difference between the target current and the actual current of the motor; The pressure-current series dual closed-loop method includes: controlling the target current based on the difference between the target pressure and the actual thrust at the output end of the thrust-type electric actuator, and controlling the motor current based on the difference between the target current and the actual current; The position-current series dual closed-loop method includes: controlling the target current based on the difference between the target position and the actual position of the output end of the thrust-type electric actuator, and controlling the motor current based on the difference between the target current and the actual current.

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