An impact-resistant electromagnetic suspension system and control method

Abstract

The application belongs to the technical field of vehicle control, and provides an anti-impact electromagnetic suspension system and a control method, the system comprising: an electromagnetic damper, an air spring and an external resistance control unit, the electromagnetic damper comprising a damper shell, a ball screw, a screw nut, a vibration transmission device and an anti-impact device, a coil being bonded in the damper shell; the vibration transmission device is matched with the screw nut through the anti-impact device; the outer surface of the rotating shell is uniformly covered with magnets. The application omits the motor, the shaft coupling and other components in the general electromagnetic damper, designs the ball screw, the coil and the magnets generated by the electromagnetic damping to the same plane, significantly reduces the axial length of the damper, controls the switch of the external resistance through a semi-active control strategy, further controls the current inside the coil, controls the size of the ampere force, and realizes the real-time control of the electromagnetic damper.

Description

Technical Field

[0001] This invention relates to automotive electromagnetic suspension technology. Background Technology

[0002] Modern electric vehicles are developing towards safety, comfort, energy efficiency, environmental friendliness, and intelligence, and people's pursuit of automotive comfort and overall quality is increasing. The application of vehicle suspension systems composed of air springs and electromagnetic dampers can significantly improve the ride comfort, handling stability, and NVH performance of the entire vehicle, thereby greatly improving the driving experience and becoming one of the hot topics in automotive technology and product development.

[0003] Current electromagnetic suspension designs generally employ a coupling to axially connect the motor rotor and ball screw, or a folded pulley to connect the ball screw's movement to the motor. When a vehicle experiences an impact from the ground, the vibration is transmitted to the electromagnetic damper. The ball screw converts the linear motion into rotational motion, which in turn drives the motor via the coupling, thus generating a damping effect and recovering energy. However, ensuring sufficient ball screw travel results in current electromagnetic suspension technologies being either too long or too bulky, significantly hindering their practical application in vehicles. Conventional electromagnetic dampers occupy more chassis space, requiring the reinstallation and rearrangement of other chassis components to ensure damping effectiveness. Furthermore, the increased number of structural components in conventional electromagnetic dampers increases overall vehicle weight, reducing energy efficiency. Finally, the complex design of electromagnetic dampers increases vehicle maintenance and repair costs.

[0004] Secondly, current electromagnetic suspension technology treats high-energy instantaneous impacts as a special type of vibration. Such high-energy instantaneous impacts can easily damage the structure of the damper, and the instantaneous impacts also generate large instantaneous currents, which can easily damage the internal circuitry.

[0005] Finally, most existing electromagnetic suspension technologies that utilize electromagnetic induction technology change the suspension damping coefficient by manually adjusting the system state. When the vehicle encounters extremely uneven road surfaces or continuous speed bumps, the damping cannot be adjusted, resulting in the vehicle still experiencing significant vibrations. Summary of the Invention

[0006] To address the issues of excessive size in existing electromagnetic suspension systems and the lack of effective solutions for handling severe impacts, an impact-resistant electromagnetic vibration damping suspension design is proposed, along with a control method and circuit scheme for real-time damping adjustment. The technical solution is as follows: An impact-resistant electromagnetic suspension system includes: an electromagnetic damper, an air spring, and an external resistance control unit. The electromagnetic damper comprises a damper housing, a ball screw, a screw nut, a vibration transmission device, and an impact-resistant device. A coil is bonded inside the damper housing, and the vibration transmission device engages with the screw nut via the impact-resistant device. A rotating shell is installed inside the damper housing and is fixedly connected to the ball screw. The outer surface of the rotating shell is uniformly covered with magnets. When the magnets rotate, the coil bonded inside the damper housing generates a current that cuts the magnetic field lines, resulting in a damping effect. The flexible airbag and the damper housing form a sealed cavity to create an air spring. The external resistance control unit outputs an optimal external resistance to control the current generated inside the control coil.

[0007] Furthermore, the impact-resistant device includes a ball screw connector, a guide slider, and a disc spring. The vibration transmission device is fixedly connected to the guide slider by a thread, and the guide slider is fixedly connected to the ball screw connector by a thread. A disc spring is placed between the guide slider and the screw nut, and between the screw connector and the screw nut.

[0008] Furthermore, the external resistor control unit includes a central controller and multiple resistors connected in the coil power supply circuit. Each resistor corresponds to a set of switching circuits. The central controller further controls the number of resistors connected in the power supply circuit by controlling the switching circuits.

[0009] Furthermore, the switching circuit includes a power supply, an optocoupler, a boost module, and a first MOSFET and a second MOSFET. The two ends of the resistor are respectively connected to the first MOSFET and the second MOSFET with opposite directions. The optocoupler is used to control the conduction and cutoff of the first MOSFET and the second MOSFET. The power supply outputs voltage to the first MOSFET and the second MOSFET through the boost module.

[0010] This invention also proposes an anti-impact electromagnetic suspension control method, comprising:

[0011] Step A: Obtain the real-time optimal control force based on the electromagnetic suspension information;

[0012] Step B: Find the optimal external resistance corresponding to the optimal control force;

[0013] Step C: Control the optimal external resistor to be connected to the coil power supply circuit via the controller.

[0014] Further, step A includes:

[0015] Step A1: Establish the dynamic model of the impact-resistant suspension.

[0016]

[0017] In the formula m s Z is the sprung mass of the suspension. u For the sprung displacement, Let u represent the sprung acceleration, u be the optimal control force calculated based on the real-time state of the vehicle at a certain moment during operation, k2 be the nonlinear coefficient of the air spring, and b be the spring constant. s The coefficient of inertia is represented by the ball screw and other components in the electromagnetic suspension, and c is the coefficient of friction in the suspension.

[0018] The above equation can be rewritten as:

[0019] in

[0020]

[0021] Step A2: Assign two weighting coefficients τ1 and τ2 to the control target of the electromagnetic suspension: sprung acceleration. Relative displacement Z of the suspension u -Z s

[0022] Z = τ(CX + D) 11 w+D 12 u)

[0023] in

[0024] Step A3: Real-time optimal control force u = KX, where K is the control gain matrix.

[0025] Further, step B includes:

[0026] Step B1: The optimal damping of the electromagnetic vibration damper is obtained by back-calculating the real-time optimal control force u:

[0027]

[0028] Step B2, Obtain the optimal external resistance as follows:

[0029]

[0030] Where, k i k e Let r be the current and current constant of the electromagnetic vibration damper, and r0 be the internal resistance of the electromagnetic vibration damper. and These are the sprung and unsprung speeds of the suspension, respectively, and R is the ball screw transmission ratio.

[0031] Further, step C includes: when r des ≥r cmax Then the external resistance value is taken as r cmax The implementation plan is to keep all switches in the open state. i =0; when r des ≤r cmin If the external resistance reaches its minimum value (s1 = 1), then the resistance is 0 in all other states. Otherwise, the following rules apply:

[0032] C1, Calculation yields r c All values ​​are stored as an array A, and a new array B is created using the elements of array A. The array elements are: n = |r c -r des |;

[0033] C2. Initialize the variable min as the first element in array B, as the initial value of the current minimum value;

[0034] C3. Use a for loop to iterate through the array elements, find the smaller element, and update the value of min.

[0035] C4. Output the resistance value r in array A corresponding to the minimum value min. c ;

[0036] C5. The controller is based on the resistance value r. c Control the state of the switch.

[0037] Furthermore, a disc spring selection step is included before step A, specifically:

[0038] S1. Based on mechanical admittance theory, the admittance of the system consisting of a disc spring and an electromagnetic damper connected in series in the frequency domain is:

[0039]

[0040] Where k is the spring constant of the disc spring in the impact-resistant electromagnetic vibration damper, c is the damping coefficient of the electromagnetic vibration damper, w is the frequency, and j is the imaginary unit. For the system's equivalent damping, The equivalent stiffness of the system;

[0041] S2. Draw the equivalent stiffness and equivalent damping diagrams of the system. Taking the main stiffness of the electromagnetic suspension as the minimum value, increase the disc spring stiffness in sequence. Select the disc spring stiffness that shows the most significant change in equivalent damping and equivalent stiffness within the main vibration reduction range of the car (2-8Hz) to determine the disc spring selection.

[0042] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0043] This invention provides a compact, shock-resistant electromagnetic suspension structure design that eliminates the need for a motor and coupling. By designing the ball screw, the coil generated by the electromagnetic damper, and the magnet on the same cross-section, the axial length of the damper is significantly reduced. Through the rational design of the shock-resistant part of the electromagnetic damper, the control effect of the electromagnetic suspension under impact excitation is improved, enhancing ride comfort. By using a semi-active control strategy, the switching of the external resistor is controlled, and further, the current inside the coil is controlled to control the magnitude of the Ampere force generated, achieving real-time control of the electromagnetic damper. Attached Figure Description

[0044] Figure 1 This is a structural diagram of the impact-resistant electromagnetic suspension of the present invention;

[0045] Figure 2 yes Figure 1 Structural diagram of ball screw and screw nut, etc.;

[0046] Figure 3 This is a block diagram of the impact-resistant electromagnetic suspension system of the present invention;

[0047] Figure 4 This is a schematic diagram of the switching circuit principle of the present invention;

[0048] Figure 5-1 This is a power schematic diagram of the impact-resistant electromagnetic vibration damper of the present invention;

[0049] Figure 5-2 This is a schematic diagram of the vibration transmissibility of the electromagnetic vibration damper of the present invention;

[0050] Figure 6-1 This is the equivalent stiffness diagram of the electromagnetic vibration damper in this invention.

[0051] Figure 6-2 This is the equivalent damping diagram of the electromagnetic vibration damper in this invention.

[0052] As shown in the above figures: 1. Electromagnetic vibration damper; 2. Air spring;

[0053] 101. Damper housing; 102. Ball screw; 103. Rotating housing; 104. Ball screw connector; 105. Screw nut; 106. Guide slider; 107. Screw fixing bolt; 108. Large nut; 109. Angular contact ball bearing; 110. Disc spring; 111. Coil; 112. Magnet; 113. Stainless steel tube;

[0054] 202. Outer sealing ring; 202. Air plug; 203. Lower end cap; 204. Flexible airbag; 205. Fixed inner liner; 206. Inner sealing ring; 207. Small pressure pad; 208. Upper end cap. Detailed Implementation

[0055] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0056] 3. Example 1, see reference Figure 1 , Figure 2 This embodiment proposes an impact-resistant electromagnetic suspension system, which includes an electromagnetic damper 1 and an air spring 2.

[0057] The electromagnetic vibration damper 1 includes a damper housing 101, a ball screw 102, a screw nut 105, a vibration transmission device, an impact-resistant device, and an external resistance control unit. A coil 111 is bonded inside the damper housing 101; the vibration transmission device engages with the screw nut 105 via the impact-resistant device; the ball screw 102 is installed inside a rotating housing 103, which is rotatably mounted inside the damper housing 101 via bearings; the outer surface of the rotating housing 103 is uniformly covered with magnets 112; the external resistance control unit outputs the optimal external resistance, thereby controlling the current generated inside the control coil 111. The impact-resistant device in this embodiment includes a ball screw connector 104 and a guide slider 106. The ball screw connector 104 is cylindrical and is movably fitted onto the ball screw 102 to form a cavity for the screw nut 105. The guide slider 106 is also cylindrical, with one end fixed to the vibration transmission device and the other end fitted onto the ball screw connector 104. Disc springs 110 are installed at both ends of the screw nut 105. Thus, disc springs are placed between the guide slider and the screw nut, and between the screw connector and the screw nut. When facing impact vibration, the force is first buffered by the disc springs, and the buffered force is then transmitted to the electromagnetic vibration damper, converting the instantaneous impact force into low-frequency vibration.

[0058] Specifically, in this embodiment, the electromagnetic vibration damper 1 omits the motor and coupling, and the structure of the electromagnetic vibration damper 1 is rationally laid out. The ball screw 102, the coil 111 generated by the electromagnetic damping, and the magnet 112 are designed on the same cross-section. The ball screw 102 converts the reciprocating motion of the vibration into rotational motion. A low-cost stainless steel tube 113 is used for motion and force transmission. That is, the stainless steel tube 113 is used to connect with the screw nut 105. The design of the round hole plug, the fixing nut, and the plug ensures the stable connection between one end of the electromagnetic vibration damper and the vehicle body, while facilitating disassembly. Screw fixing bolts 107 are installed at both ends of the ball screw. The part that mates with the screw nut is designed with two parts: a guide slider 106 and a ball screw connector 104 to ensure the stable connection between the stainless steel tube 113 and the screw nut 105, while ensuring that the screw nut 105 can perform smooth linear motion. Vehicle vibration is transmitted to stainless steel tube 113, causing ball nut to move linearly, which in turn drives lead screw to rotate. Lead screw is fixedly connected to rotating housing 103, causing rotating housing 103 to rotate. Magnets 112 are evenly covered on the surface of rotating housing 103. To facilitate the fixing of angular contact ball bearing 109, magnets 112 are designed in a stepped shape. Multiple layers of coils 111 are evenly pasted inside the outer shell 101 of electromagnetic vibration damper 1. When magnets 112 rotate inside coils 111, they generate Ampere force, similar to the principle of a DC brushless motor. The magnitude of the Ampere force can be controlled by controlling the current inside coils 111, realizing real-time control of electromagnetic vibration damper 1.

[0059] For the housing design, in order to ensure the maintenance and disassembly of the electromagnetic vibration damper 1, one end of the housing is designed as a detachable shaft head, which is connected to the housing by eight countersunk bolts.

[0060] For ease of assembly, in this embodiment, the stainless steel tube 113 is threadedly connected to the guide slider 106, and the fixed slider is then threadedly connected to the ball screw connector 104. A buffer is placed between the guide slider 106 and the ball nut, and between the ball screw connector and the ball screw nut. When vibrations with low energy density are transmitted to the electromagnetic suspension through the stainless steel tube 113, the buffer does not function until the transmitted force reaches the preload of the buffer; in this state, the electromagnetic suspension is in normal vibration damping mode. When a larger impact force is transmitted to the electromagnetic suspension through the stainless steel tube 113 and reaches the preload of the buffer, it will be converted into a smaller vibration force by the buffer.

[0061] In a specific embodiment, the buffer element is a disc spring 110. Four disc springs 110 are placed in two groups between the guide slider 106 and the lead screw nut 105, and between the ball screw connector 104 and the lead screw nut 105, respectively. When facing impact vibration, the force is first buffered by the disc springs 110, and the buffered force is then transmitted to the electromagnetic vibration damper 1, converting the instantaneous impact force into low-frequency vibration. The disc springs 110 can withstand static loads, impact loads, or dynamic alternating loads, and can meet the stringent requirements for fatigue life and load loss.

[0062] In this embodiment, a sealed cavity is formed by the flexible airbag 204 and the outer shell of the electromagnetic damper 1. The elastic force of the air spring 2 is indirectly controlled by controlling the air pressure inside the sealed cavity. The outer sealing ring 202, the lower end cover 203, the fixed inner liner 205, the inner sealing ring 206, the small pressure pad 207, and the upper end cover 208 constitute the fixing and sealing components of the air spring 2. The air spring 2 can be inflated and deflated through the air plug 202.

[0063] In this embodiment, the external resistor control unit includes a central controller and multiple resistors connected in the power supply circuit of the coil 111. Each resistor corresponds to a set of switching circuits. The central controller further controls the number of resistors connected in the power supply circuit by controlling the switching circuits.

[0064] The resistance value of the controllable resistor in the circuit is:

[0065]

[0066] Where s i This indicates the state of the controllable switch, which is either 0 or 1. For example, when the first switch is closed, s1 = 1, and when it is open, s1 = 0. In a special case, the sixth branch is set to normally open, i.e., s6 = 1 is a constant value. i For each power resistor, the first branch has no resistor, i.e., r1 = 0. For ease of explanation later, assume r2 to r6 are 3, 8, 15, 50, and 100 ohms respectively. c The number of varieties can reach In practical applications, designers can optimize the selection of resistors based on the detailed manufacturing process of the electromagnetic vibration damper 1, and the number of circuit branches can be expanded to increase the adjustability of the controllable resistor.

[0067] In the design of the switching circuit, considering that the electromagnetic damper is constantly operating at high speed, its circuit current is almost always several amperes or even tens of amperes, while the control circuit current is extremely small, this embodiment uses optocouplers to achieve circuit isolation to ensure safety. Furthermore, the large current in the electromagnetic damper circuit means that ordinary solid-state relays cannot meet the requirements for real-time control. This embodiment connects two MOSFETs in series with opposite directions in the circuit. On the one hand, even under high current conditions, it ensures a response time of less than 10ms; on the other hand, it allows the circuit to be in an open state when no high-level signal is received.

[0068] Specifically, the switching circuit includes a power supply, an optocoupler, a boost module, and a first MOSFET and a second MOSFET. The two ends of the resistor are connected to the first MOSFET and the second MOSFET with opposite directions, respectively. The optocoupler is used to control the conduction and cutoff of the first MOSFET and the second MOSFET. The power supply is used to power the optocoupler and also outputs voltage to power the first MOSFET and the second MOSFET through the boost module.

[0069] refer to Figure 3 The circuit uses a low-voltage 5V power supply. When the circuit is powered normally, LED1 is lit. When SW1 provides a high-level signal, the optocoupler is activated, and LED2 lights up. The low-voltage power supply is boosted from 5V to 12V via a boost module. The 12V power supply continuously powers Q2 and Q3. Q2 and Q3 can only be activated when SW1 provides a high-level signal causing the optocoupler to connect, at which point the power resistor is connected to the circuit. This completes the process of connecting the power resistor to the circuit by providing a high or low-level signal.

[0070] Example 2: This example proposes an anti-impact electromagnetic suspension control method.

[0071] The impact-resistant electromagnetic suspension of this invention is essentially a semi-active suspension. The advantage of semi-active control lies in achieving significantly better performance than passive suspension with almost no energy consumption. The control scheme for this embodiment of the semi-active electromagnetic suspension is as follows: first, an optimal control force is calculated using suspension information through a central controller; second, a semi-active control scheme is designed to track this optimal control force. This invention proposes an active control method based on H∞, F des This indicates the optimal control force of the suspension.

[0072] (1). Solving for the real-time optimal control force

[0073] The simplified dynamic model of this impact-resistant suspension is established as follows:

[0074]

[0075] In the formula m s Z is the sprung mass of the suspension.u For the sprung displacement, Let u represent the spring acceleration, k2 be the optimal control force generated by the electromagnetic damper under ideal conditions, and b be the nonlinear coefficient of the air spring. s Let represent the inertial force coefficient of the ball screw, etc., in the electromagnetic suspension, and c represent the friction coefficient of the suspension. The above equation can be rewritten as:

[0076] in

[0077] x1=z u -z s , X = [x1x2] T w = [d1 d2] T

[0078] In this embodiment, the control target of the suspension is sprung acceleration. Relative displacement Z of the suspension u -Z s The two weighting coefficients τ1 and τ2 are assigned to the control target.

[0079] Z = τ(CX + D) 11 w+D 12 u)

[0080] in

[0081] Given H∞ feedback control law:

[0082] u=KX

[0083] The control gain matrix K is obtained from the following:

[0084]

[0085] Where P = P T >0 indicates a positive definite matrix, * denotes a symmetric term in the matrix, and γ represents the expected interference attenuation level.

[0086] Process the above equation and define Q = P. -1 Y = KQ, therefore:

[0087]

[0088] Y and Q can be obtained using MATLAB's LMI toolbox, and the state feedback gain matrix K can be obtained.

[0089] H-infinity controllers can ensure the stability and performance of control systems under uncertainties such as model perturbations, measurement errors, and external environmental excitations. They have a certain degree of anti-interference capability against model uncertainties and are an effective method for solving nonlinear and uncertain robustness problems in fields such as intelligent driving. At the same time, H-infinity control combines the robust stability and control performance of the system in a unified design framework, avoiding repeated manual adjustments to the controller parameters.

[0090] (2) Semi-active control strategy

[0091] The damping force of electromagnetic vibration damper 1 is related to the system state and its own equipment parameters, specifically:

[0092] F c =k i I

[0093] I = E / (r0 + r) c )

[0094]

[0095] Where k i k e Let be the current and voltage constants of electromagnetic damper 1, which are related to the design of the damper. I and E are the current and electromotive force of the electromagnetic damper, respectively. The rotational speed of the rotating housing of the electromagnetic vibration damper. and These represent the sprung and unsprung speeds of the suspension, respectively; R is the transmission ratio of the ball screw 102; and r0 and r c Combining the above four equations for the internal resistance and external variable resistance of the electromagnetic vibration damper, we can obtain:

[0096]

[0097] The damping coefficient is expressed as follows:

[0098]

[0099] Where C is the damping of the electromagnetic vibration damper, and through the above analysis, it can be obtained that by controlling the external variable resistor r of the electromagnetic vibration damper 1... c This allows for adjustment of the output force of the electromagnetic vibration damper.

[0100] The optimal ideal force u that changes in real time is obtained from (1). If the electromagnetic damper is to be optimal, a resistance value that corresponds to the relative speed of the suspension in real time is required. This invention realizes the total resistance change in the electromagnetic damper circuit by opening and closing multiple resistance branches.

[0101] The optimal damping of the electromagnetic vibration damper is derived by inversely from the active ideal force u:

[0102]

[0103] The corresponding optimal external resistance is:

[0104]

[0105] The semi-active tracking control strategy in this embodiment is specifically described as follows: when r des ≥r cmax Then the external resistance value is taken as r cmax The implementation plan is to keep all switches in the open state. i =0; when r des ≤r cmin If the external resistance reaches its minimum value (s1 = 1), then the resistance is 0 in all other states. Otherwise, the following rules apply:

[0106] S1: Get r c All values ​​are stored in an array A, and a new array B is created using the elements of array A. The elements of array B are:

[0107] n = |r c -r des |

[0108] S2: Initialize the variable min as the first element numbers[0] in array B, as the initial value of the current minimum value;

[0109] S3: Use a for loop to traverse the array elements, starting from index 1, which is the second element of the array, and compare each other element in the array with the current minimum value min. If a smaller element is found, update the value of min.

[0110] S4: Output the resistance value r in array A corresponding to the minimum value min. c ;

[0111] S5: The controller controls the switch status.

[0112] The electromagnetic vibration damper designed in this invention requires only milliwatt-level energy consumption from the controller. Utilizing this semi-active tracking control strategy, semi-active vibration control can be achieved. The designed damper eliminates components such as the motor and coupling found in conventional electromagnetic vibration dampers, significantly reducing its size. It can adjust the damping coefficient in real-time and precisely according to changes in the suspension system's state, adapting to the performance requirements of various road conditions. The proposed semi-active tracking control strategy is based on an in-depth analysis of the dynamic characteristics of the suspension system and the construction of a mathematical model. With the help of vehicle body sensors and real-time data processing algorithms, it achieves precise control of the damper's operating state. This real-time response and adaptive adjustment capability effectively overcomes the limitations of traditional suspension systems in dealing with complex road conditions, demonstrating superior performance advantages and broad application prospects.

[0113] This completes the semi-active control process of the electromagnetic vibration damper.

[0114] The compact electromagnetic suspension system designed in this invention, while ensuring the excellent low-frequency vibration control of traditional electromagnetic suspension, further enhances passenger comfort by adding shock-resistant devices to the electromagnetic dampers, especially when encountering impact excitations during vehicle operation, such as driving into large, unavoidable potholes or driving over high speed bumps.

[0115] The impact-resistant electromagnetic suspension of this invention adopts a "time-for-space" strategy, such as... Figure 5-1 The diagram shows the power output of the electromagnetic vibration damper. The solid line represents a conventional damper, and the dashed line represents the impact-resistant damper. The area enclosed by power and time represents the impact energy that needs to be addressed. During the dissipation of this energy, the instantaneous power required by the impact-resistant electromagnetic vibration damper is significantly lower than that of the conventional electromagnetic vibration damper. Because an elastic element is placed during the vibration transmission to the damper, it takes time for the preload of the elastic element to be reached when a severe impact occurs. During this time, the large impact is reduced to a normal vibration. Otherwise, the electromagnetic vibration damper would directly dissipate the incoming large impact energy, potentially causing damage to the suspension and electrical structures. Although the time to recover to the minimum sprung acceleration is slightly prolonged, the maximum sprung acceleration is significantly reduced, achieving a superior impact resistance effect.

[0116] Through real-time control of electromagnetic damping, it is possible to achieve, for example Figure 5-2 The real-time changes in the transmissivity characteristics of the damper shown ensure that the damper can achieve better vibration reduction in random excitation environments.

[0117] This embodiment also includes a disc spring selection step before step (1), specifically:

[0118] Step 1: Based on mechanical admittance theory, the frequency domain admittance of the system consisting of a disc spring and an electromagnetic damper connected in series is obtained as follows:

[0119]

[0120] Where k is the spring constant of the disc spring in the impact-resistant electromagnetic vibration damper, c is the damping coefficient of the electromagnetic vibration damper, w is the frequency, and j is the imaginary unit. For the system's equivalent damping, The equivalent stiffness of the system;

[0121] Step 2: Draw the equivalent stiffness and equivalent damping diagrams of the system. Taking the main stiffness of the electromagnetic suspension as the minimum value, the disc spring stiffness is increased in sequence. The disc spring stiffness with the most significant change in equivalent damping and equivalent stiffness in the main vibration reduction area of ​​the car (2-8Hz) is selected to determine the disc spring type.

[0122] Figure 6-1 and Figure 6-2 The equivalent stiffness and equivalent damping of the electromagnetic damper under four different disc spring stiffnesses are given. k1 is selected as the maximum value of the air spring. When the disc spring stiffness is k1, the change in equivalent damping is obvious at low frequencies, but the maximum value of the equivalent stiffness is too small. When the disc spring stiffness is k4, the change in equivalent stiffness is the most obvious, but the change in its equivalent damping curve is not as obvious as k1, k2, and k3. Therefore, a value of k2 or k3 can be initially selected as the stiffness value of the disc spring. Subsequently, k2 and k3 can be used as the minimum and maximum values, respectively, and the above steps can be repeated to select the most suitable disc spring stiffness value.

[0123] The embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An impact-resistant electromagnetic suspension system, characterized in that, include: Electromagnetic vibration damper, air spring and external resistor control unit; the electromagnetic vibration damper includes damper housing, ball screw, screw nut, vibration transmission device and shock-resistant device. A coil is bonded inside the damper housing, and the vibration transmission device is connected to the lead screw nut via an anti-impact device. A rotating shell is installed inside the damper housing, which is fixedly connected to the ball screw. The outer surface of the rotating shell is uniformly covered with magnets. When the magnets rotate, the coil bonded inside the damper housing forms a phenomenon where current cuts magnetic field lines, thus producing a damping effect. The flexible airbag and the damper housing form a sealed cavity to create an air spring. The external resistance control unit is used to output the optimal external resistance, thereby controlling the current generated inside the control coil; The impact-resistant device includes a ball screw connector, a guide slider, and a disc spring. The vibration transmission device is fixedly connected to the guide slider by a thread, and the guide slider is fixedly connected to the ball screw connector by a thread. A disc spring is placed between the guide slider and the screw nut, and between the screw connector and the screw nut. The external resistance control unit includes a central controller and multiple resistors connected in the coil power supply circuit. Each resistor corresponds to a set of switching circuits. The central controller further controls the number of resistors connected in the power supply circuit by controlling the switching circuits to change the resistance value of the circuit and realize the damping change of the electromagnetic vibration damper. The switching circuit includes a power supply, an optocoupler, a boost module, and a first MOSFET and a second MOSFET. The two ends of the resistor are respectively connected to the first MOSFET and the second MOSFET with opposite directions. The optocoupler is used to control the conduction and cutoff of the first MOSFET and the second MOSFET. The power supply is used to power the optocoupler and outputs voltage to power the first MOSFET and the second MOSFET through the boost module.

2. A shock-resistant electromagnetic suspension control method based on the system described in claim 1, characterized in that... include: Step A: Obtain the real-time optimal control force based on the electromagnetic suspension information; Step B: Find the optimal external resistance corresponding to the optimal control force; Step C: Control the optimal external resistor to be connected to the coil power supply circuit via the controller.

3. The anti-impact electromagnetic suspension control method according to claim 2, characterized in that: Step A includes: Step A1: Establish the dynamic model of the impact-resistant suspension. In the formula The sprung mass of the suspension. For the sprung displacement, The sprung speed of the suspension. Indicates the spring acceleration. For unsprung displacement, The unsprung speed of the suspension. Indicates unsprung acceleration. The optimal control force for a vehicle with an electromagnetic shock absorber at a certain moment of travel. Let be the nonlinear coefficient of the air spring. This indicates the inertial force coefficient of components such as ball screws in electromagnetic suspension systems. The coefficient of friction is the frictional force in the suspension. The above equation can be rewritten as: , in Step A2: Combine the two weighting coefficients The control target assigned to the electromagnetic suspension: sprung acceleration Relative displacement of the suspension Minimum; in Step A3: Use the above formula to give the real-time optimal control force. ,in The control gain matrix is ​​designed.

4. The anti-impact electromagnetic suspension control method according to claim 3, characterized in that: Step B includes: Step B1: Through optimal control force The optimal damping of the electromagnetic vibration damper is obtained by reverse engineering: Step B2, the optimal external resistance should be: in, , The current and voltage constants of the electromagnetic vibration damper are... The internal resistance of the electromagnetic vibration damper. and These are the sprung and unsprung speeds of the suspension, respectively. This refers to the mechanical transmission ratio of the electromagnetic vibration damper.

5. The anti-impact electromagnetic suspension control method according to claim 4, characterized in that: Step C includes: when Then the external resistance value is taken as The implementation plan is to keep all switches in the open state. , i>1; when Then the external resistance reaches its minimum value, even if All other states are 0. and These are the maximum and minimum resistance values ​​of the external adjustable resistor module, respectively. In addition to these two cases, the calculation shall be performed according to the following rules: C1. Calculate all the resistance values ​​of the adjustable resistor module into an array A. The number of array elements in array A, i.e., the number of different resistance value types that can be achieved using N resistors, is: And create a new array B using the elements of array A, with the following array elements: ; C2. Initialize the variable min as the first element in array B, as the initial value of the current minimum value; C3. Use a for loop to iterate through the array elements, find the smaller element, and update the value of min. C4. Output the resistance value in array A corresponding to the minimum value min. ; C5. The controller determines the resistance value. Control the state of the switch.

6. The anti-impact electromagnetic suspension control method according to claim 5, characterized in that: The step A is preceded by a disc spring selection step, specifically: S1. According to the mechanical admittance theory, the admittance of the electromagnetic vibration damper system in the frequency domain is: in The spring constant of the disc spring in the impact-resistant electromagnetic vibration damper. The damping coefficient of the electromagnetic vibration damper. For frequency, It is the imaginary unit, and also For the system's equivalent damping, The equivalent stiffness of the system; S2. Based on S1, draw the equivalent stiffness and equivalent damping diagrams of the electromagnetic damper system. Starting with the minimum main stiffness of the electromagnetic suspension, gradually increase the stiffness of the disc springs. The selection of disc springs can be roughly determined by choosing the disc spring stiffness that shows the most significant changes in equivalent damping and equivalent stiffness within the 2-8Hz range, which is the main vibration reduction area of ​​the car.

Images