Switchable energy feedback electromagnetic suspension and control method

Abstract

The invention discloses a switchable energy feedback electromagnetic suspension and a control method. The switchable energy feedback electromagnetic suspension comprises a sensor, a central control unit (ECU), an electromagnetic vibration reduction unit, a three-phase rectifier, a two-stage DCDC converter, an energy feedback circuit and an energy consumption circuit body. The suspension comprises an energy feedback mode and an energy consumption mode which can be switched, in the energy feedback mode, energy generated by vibration is absorbed through a super capacitor, and the vibration reduction performance of the suspension is guaranteed while the energy is recycled; and in the energy consumption mode, energy generated by vibration is dissipated through heating of the resistor, the excellent vibration reduction performance is guaranteed, meanwhile, secondary storage is conducted on the super capacitor, and the energy feedback efficiency is improved. According to the suspension system and the control method, the energy feedback efficiency can be effectively improved on the premise that the vibration reduction performance is guaranteed, and the problem that the vibration reduction system and the energy feedback efficiency of a traditional energy feedback suspension system are difficult to consider at the same time is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration reduction, and in particular to a switchable energy-feeding electromagnetic suspension and a control method thereof. Background Art

[0002] The suspension system is a structure used to connect the body and wheels of cars and other vehicles. Its main functions are to support the weight of the vehicle, absorb and buffer vibrations, and improve handling. It is a key component that determines the comfort and stability of the vehicle. There are three mainstream suspension systems at present, namely passive, semi-active and active suspension. Among them, active suspension has the best performance, but energy consumption is a major technical problem that needs to be solved.

[0003] The energy-regenerating suspension is a semi-active control suspension with energy recovery. It monitors the vehicle's driving status and road conditions in real time and actively adjusts the damping force to optimize comfort and handling. At the same time, the energy-regenerating suspension also integrates an energy recovery function, which can convert the vibration energy generated by the suspension movement during vehicle driving and store it in electrical energy. However, the existing energy-regenerating suspension has an irreconcilable contradiction between vibration reduction performance and energy storage efficiency. Low energy-regenerating efficiency due to ensuring vibration reduction performance has become a common problem at present.

[0004] Therefore, reconciling the contradiction between vibration reduction performance and energy storage efficiency to achieve the best driving experience and energy-saving efficiency is of great significance to improving vehicle performance. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned technologies, the present invention provides a switchable energy-feeding electromagnetic suspension and a control method. The device is provided with a two-stage DC / DC converter and a switching module to ensure that the vehicle has good vibration reduction performance throughout the whole process. The device also has the function of switching between energy consumption and energy-feeding modes. The energy-feeding efficiency of the suspension is improved by rapid charging and discharging of a supercapacitor, thereby achieving the best energy-feeding efficiency while ensuring the comfort of the vehicle.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A switchable energy-feeding electromagnetic suspension system includes an electromagnetic actuator, a three-phase rectifier, a first DC / DC converter, a switchable circuit, a second DC / DC converter, a linear displacement sensor, an acceleration sensor, a signal processor, a central control unit ECU, a first PWM controller, a second PWM controller, and a battery pack. The electromagnetic actuator can be regarded as composed of three current sources, a resistor, and an inductor connected to their circuits. The vibration of the suspension causes relative movement between the permanent magnet and the coil in the motor, thereby generating induced electromotive force and induced current, which are collected and converted into electrical energy while the vehicle body vibrates; the three-phase rectifier is composed of 6 diodes connected to its circuit, so that the currents of different directions generated by each phase of the electromagnetic actuator pass through the three-phase rectifier, and the alternating current generated by the three-phase asynchronous motor is converted into direct current.

[0008] The first DCDC converter is composed of a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, two capacitors, an inductor, and a circuit composed of them. Mode 1: The first MOSFET and the fourth MOSFET are closed at the same time, and the second MOSFET and the third MOSFET are opened at the same time. Mode 2: The first MOSFET and the third MOSFET are closed at the same time, and the second MOSFET and the fourth MOSFET are opened at the same time. Mode 3: The second MOSFET and the third MOSFET are closed at the same time, and the first MOSFET and the fourth MOSFET are opened at the same time. Among them, mode 2 and mode 3 form a BUCK circuit, and mode 1 and mode 2 form a BOOST circuit. Together, they form a BUCK-BOOST circuit to regulate the rise and fall of the output voltage. Prevent the circuit current from decreasing or disappearing after the terminal voltage of the supercapacitor increases to be greater than or equal to the rectified voltage during the charging process of the supercapacitor, resulting in uncontrollable suspension damping force.

[0009] The switchable circuit is composed of a first switch, a second switch, a third switch, a normally closed switch, a diode, a supercapacitor and its circuit. When the second switch is closed, the first switch and the third switch are disconnected, the circuit enters the energy feeding mode, and the mechanical energy of the vehicle body vibration caused by the road surface excitation is converted into electrical energy through the electromagnetic actuator and stored in the supercapacitor. When the first switch and the third switch are closed, the second switch is disconnected, and the circuit enters the energy consumption mode. The principle is similar to the energy feeding mode, and the electrical energy is converted into heat energy and dissipated in the resistor. Due to the disconnection of the second switch, the heat dissipation of the resistor and the discharge process of the supercapacitor are independent of each other. The energy stored in the supercapacitor, after its voltage is boosted by the second DC / DC converter, the energy is input into the battery for storage. The second DC / DC converter has the same structure as the first DC / DC converter. In a cycle of supercapacitor charging and discharging, the charging time is much longer than the discharging time, so the time of the energy feeding mode is much longer than that of the energy consumption mode. The energy consumption mode accounts for a low proportion of the entire cycle, which reduces the heating of the resistor and improves the utilization rate of energy. PI controls the two modes of energy feeding and energy consumption. It adjusts the circuit current by regulating the duty cycle through PWM waves, so as to achieve adjustable damping force for vibration control of the cab suspension, and finally stores the energy in the battery pack to realize energy collection and vibration control of the energy feeding suspension.

[0010] The present invention provides a control method for a switchable energy-feeding electromagnetic suspension. The sensors include a wired displacement sensor and an acceleration sensor. The function of the wired displacement sensor is to convert the linear mechanical displacement into an electrical signal. The acceleration sensor obtains the acceleration and converts it into an electrical signal by testing the inertial force exerted on the mass block. The sensor transmits the displacement and force information of the vehicle body vibration to the central control unit ECU through an electrical signal, and the central control unit ECU calculates and outputs a reference current value I ref To the PI controller. When the car body vibrates, the energy generated by the vibration cuts the magnetic flux lines through the electromagnetic actuator to generate AC power. The three-phase rectifier converts the AC power into DC power, and its current is I M The PI controller converts the theoretical current I ref The actual current I M The difference is made, and the duty cycle D is output, which is sent to the first PWM controller to obtain a PWM wave that controls the current. The first PWM controller outputs the PWM wave to the first DC / DC converter to adjust the buck-boost size so that the actual current I M The theoretical current I transmitted to the central control unit ECU through proportional regulation ref Keep approaching, thereby controlling the actual current I M The size of the actual damping force of the suspension electromagnetic shock absorber is adjusted to further achieve real-time control of the damping force and reduce the vibration amplitude of the vehicle body.

[0011] The control strategy of the switchable energy-feeding electromagnetic suspension is as follows: when the vehicle body vibrates, the electromagnetic suspension starts to work, and the central control unit ECU detects the terminal current and terminal voltage of the supercapacitor. If the terminal voltage is less than 4V, the circuit enters the energy-feeding mode; the central control unit ECU controls the closing of the second switch and disconnects the first and third switches. The circuit enters the energy-feeding mode, the supercapacitor enters the charging mode, and the terminal voltage gradually increases. If the terminal voltage is greater than 4V, the circuit enters the energy-consuming mode and reduces the terminal voltage of the supercapacitor.

[0012] When entering the energy feeding mode, U n (n=1, 2, 3) represents the induced voltage of each stator coil, E m and w e represent the amplitude and angular frequency of the induced voltage respectively.

[0013] U1=E m sin(w e t-120°)

[0014] U2=E m sinw e t

[0015] U3=E m sin(w e t+120°)

[0016] Instantaneous total electrical power P E Equal to the power P captured in the charging circuit c The power P lost in the internal resistance i The internal resistance is R i , the capacitance and resistance are R e , which can be expressed as:

[0017]

[0018]

[0019] When the generator is working, the rotor angular velocity is proportional to the induced voltage. Then the induced voltage E m It can be expressed as:

[0020]

[0021] When the DC / DC converter controls the buck-boost, V IN With V OUT The relationship is:

[0022]

[0023] Where D is the value of PWM duty cycle, V IN is the input voltage, V OUTis the output voltage;

[0024] According to the energy conservation principle in the electromechanical field, P E It can also be expressed as:

[0025]

[0026] Where, T E Represents the electromagnetic torque on the generator shaft, which is equal to the generator's rotational damping coefficient C R The product of the generator shaft speed γ is:

[0027]

[0028] Therefore, the controllable damping of the variable damping system in the energy feedback mode is C R (t):

[0029]

[0030] During the entire process of supercapacitor charging, the value of the supercapacitor terminal voltage is detected in real time. If the value does not exceed 8V, the supercapacitor is in charging mode. When the terminal voltage of the supercapacitor exceeds 8V, the central control unit ECU receives a signal, controls the first switch to close, and the second switch to open, and the circuit enters the energy consumption mode. Energy is dissipated by the resistor in the form of heat, and the supercapacitor is discharged and stored in the battery after being boosted by the second DC / DC converter. At this time, the sensor detects the voltage and current data of the battery pack.

[0031] In the energy consumption mode, the motor and rectifier are equivalent to a voltage source e, and the internal resistance is R i , the external resistor is R e , D is the value of PWM duty cycle, equivalent resistance R E for:

[0032]

[0033] R m is the resistance value when the MOSFET switch is on, which can be set to 0Ω. The equivalent resistance of the external resistor and the MOSFET switch can be defined as follows:

[0034] R E =(1-D)R e

[0035] The generated voltage is proportional to the motor speed w, and the voltage constant is k e , the generated voltage can be obtained:

[0036] e=k e w

[0037] The current is I p, so that the torque T a for:

[0038]

[0039] where k i is the torque constant, k in the motor i =k e ;

[0040] Therefore, the controllable damping of the variable damping system in the energy consumption mode is c r (t):

[0041]

[0042] When the battery is not fully charged, the third switch is closed, the supercapacitor continues to discharge, and the central control unit ECU detects the battery voltage and transmits it to the second PWM controller to control the charging voltage of the battery. The current generated by the discharge of the supercapacitor is boosted by the second DCDC controller to obtain a voltage that is always higher than a certain value of the battery voltage to charge the battery pack. The battery's electrical energy can provide electrical energy for sensors or active control. When it is detected that the supercapacitor is continuously discharging and the terminal voltage is less than 4V, the circuit enters the charging mode. When the battery is fully charged, the third switch remains disconnected, the supercapacitor cannot discharge, its terminal voltage remains unchanged, and the control circuit remains in the energy consumption mode.

[0043] Furthermore, the four electromagnetic energy-feeding suspensions are an integrated system that can charge the battery by recovering the energy of a single or multiple electromagnetic suspensions. If the battery pack is discharging, but the discharge efficiency is less than the charging efficiency of the four supercapacitors, the central control unit ECU can control the four normally closed switches to be disconnected in turn, and the four supercapacitors are discharged in turn. In this case, the total discharge efficiency of the supercapacitors decreases, and there is no need to discharge and stop frequently.

[0044] The beneficial effects of the present invention are:

[0045] (1) The present invention has an energy consumption and energy feedback multi-mode autonomous switching system. During the switching process, the vibration reduction performance is taken as the goal, and the excellent vibration reduction performance can be always maintained to ensure the vehicle riding comfort.

[0046] (2) The switchable energy-feeding electromagnetic suspension provided by the present invention is equipped with a two-stage DCDC buck-boost module, which realizes graded energy storage through switching, can obtain more efficient energy recovery, and improve the energy-saving performance of the vehicle.

[0047] (3) The switchable energy-feeding electromagnetic suspension and electromagnetic power generation technology provided by the present invention not only have excellent energy-saving performance, but also overcome the problems of low nonlinear control accuracy and pollution of traditional oil-liquid shock absorbers.

[0048] (4) The switchable energy-feeding electromagnetic suspension provided by the present invention adopts an electrical network system, which has the advantages of high integration and low space requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a simplified structural diagram of the switchable energy-feeding electromagnetic suspension system;

[0050] Figure 2 It is a schematic diagram of the structure of a switchable energy-feeding electromagnetic suspension system;

[0051] Figure 3 It is a diagram of a DC / DC converter;

[0052] Figure 4 It is the control logic diagram of switchable energy-feeding electromagnetic suspension;

[0053] Figure 5 Main power tracking diagram;

[0054] Figure 6 This is a comparison chart with the passive suspension acceleration;

[0055] Figure 7 This is the voltage diagram of the supercapacitor terminal.

[0056] In the figure: 1. electromagnetic actuator; 101. generator; 102. resistor; 103. inductor; 2. three-phase rectifier; 201. diode; 3. first DC / DC converter; 301. first MOSFET; 302. second MOSFET; 303. third MOSFET; 304. fourth MOSFET; 305. capacitor; 306. inductor 4. switchable circuit; 401. first switch; 401. second switch; 403. third switch; 404. normally closed switch; 405. resistor; 406. diode; 407. super capacitor; 5. second DC / DC converter; 6. linear displacement sensor; 7. acceleration sensor; 8. signal processor; 9. central processing unit ECU; 10. PI controller; 11. first PWM controller; 12. battery pack; 13. second PWM controller. Specific implementation plan

[0057] The present invention will be further described below in conjunction with the accompanying drawings:

[0058] like Figure 1 As shown, a switchable energy-feedback electromagnetic suspension system is installed between the vehicle body and the tire and connected in parallel with the spring.

[0059] like Figure 2As shown, a switchable energy-feeding electromagnetic suspension system includes an electromagnetic actuator 1, a three-phase rectifier 2, a first DC / DC converter 3, a switchable circuit 4, a second DC / DC converter 5, a linear displacement sensor 6, an acceleration sensor 7, a signal processor 8, a central control unit ECU9, a PI controller 10, a first PWM controller 11, a battery pack 12, and a second PWM controller 13. Further, the electromagnetic actuator 1 can be regarded as being composed of three generators 101, a resistor 102, and an inductor 103 connected to their circuits. The vibration of the suspension causes relative movement between the permanent magnet and the coil in the motor, thereby generating induced electromotive force and induced current, and the vibration generated is collected and converted into electrical energy while the vehicle body vibrates; the three-phase rectifier 2 is composed of 6 diodes 201 connected to its circuit, so that the currents of different directions generated by each phase of the electromagnetic actuator 1 pass through the three-phase rectifier 2, and the alternating current generated by the electromagnetic actuator 1 is converted into direct current.

[0060] like Figure 3 As shown, the first DCDC converter 3 is composed of a first MOSFET 301, a second MOSFET 302, a third MOSFET 303, a fourth MOSFET 304, two capacitors 305, an inductor 306, and a circuit composed thereof. Through mode 1: the first MOSFET 301 and the fourth MOSFET 304 are closed at the same time, the second MOSFET 301 and the third MOSFET 301 are opened at the same time, mode 2: the first MOSFET 301 and the third MOSFET 303 are closed at the same time, the second MOSFET 302 and the fourth MOSFET 304 are opened at the same time, mode 3: the second MOSFET 302 and the third MOSFET 303 are closed at the same time, the first MOSFET 301 and the fourth MOSFET 304 are opened at the same time, mode 2 and mode 3 form a BUCK circuit, mode 3 and mode 4 form a BOOST circuit, and together form a BUCK-BOOST circuit to regulate the rise and fall of the output voltage. Prevent the circuit current from decreasing or disappearing after the terminal voltage of the supercapacitor increases to be greater than or equal to the rectified voltage during the charging process of the supercapacitor, resulting in uncontrollable suspension damping force.

[0061] The switchable circuit is composed of a first switch 401, a second switch 402, a third switch 403, a normally closed switch 404, a resistor 405, a resistor diode 406, a super capacitor 407 and a circuit thereof. When the second switch 402 is closed, the first switch 401 and the third switch 403 are disconnected, and the circuit enters the energy feeding mode. The mechanical energy of the vehicle body vibration caused by the road excitation is converted into electrical energy by the generator 101 and stored in the super capacitor 407. When the first switch 401 and the third switch 403 are closed, and the second switch 402 is disconnected, the circuit enters the energy consumption mode. The principle is similar to the energy feeding mode. The electrical energy is converted into heat energy and dissipated in the resistor 405. Due to the disconnection of the second switch 402, the heat dissipation of the resistor 405 and the discharge process of the super capacitor 407 are independent of each other. The energy stored in the super capacitor 407, after its voltage is boosted by the second DC / DC converter 5, the energy is input into the battery 12 for storage. The second DC / DC converter 5 has the same structure as the first DC / DC converter 3, and the role of the diode 406 is to prevent the current from reversing.

[0062] A control method for a switchable energy-feeding electromagnetic suspension, wherein the sensors include a wired displacement sensor 6 and an acceleration sensor 7, wherein the function of the wired displacement sensor 6 is to convert a linear mechanical displacement into an electrical signal. The acceleration sensor 7 obtains acceleration and converts it into an electrical signal by testing the inertial force on the mass. The sensor transmits the displacement and force information of the vehicle body vibration to the central control unit ECU9 through an electrical signal, and outputs a reference current value to the PI controller 10 through calculation by the central control unit ECU9. While the vehicle body is vibrating, the energy generated by the vibration is collected to generate alternating current through the electromagnetic actuator 1, and the three-phase rectifier 2 converts the alternating current generated by the electromagnetic actuator 1 into direct current. The PI controller 9 compares the theoretical current transmitted by the central control unit ECU8 with the actual current obtained by conversion, combines integral control with proportional control, and obtains a duty cycle for controlling the energy-feeding circuit. The PI controller 10 outputs the duty cycle to the first PWM controller 11, obtains a PWM wave to adjust the magnitude of the buck-boost current, and the actual current of the circuit is close to the theoretical current transmitted by the central control unit ECU9, thereby adjusting the magnitude of the actual damping force of the suspension electromagnetic shock absorber, further realizing real-time control of the damping force, and reducing the vibration amplitude of the vehicle body.

[0063] like Figure 4As shown, the control strategy of the switchable energy-feeding electromagnetic suspension is as follows: when the vehicle body vibrates, the electromagnetic suspension starts to work, and the central control unit ECU9 detects the terminal current and terminal voltage of the supercapacitor 407. If the terminal voltage value is less than 4V, the circuit enters the energy-feeding mode; the central control unit ECU9 controls the closing of the second switch 402 and disconnects the first switch 401 and the third switch 403. The circuit enters the energy-feeding mode, the supercapacitor 407 enters the charging mode, and the terminal voltage gradually increases. If the terminal voltage is greater than 4V, the circuit enters the energy-consuming mode and reduces the terminal voltage of the supercapacitor 407.

[0064] In the energy-feedback mode, U n (n=1,2,3) represents the induced voltage of each stator coil, E m and w e represent the amplitude and angular frequency of the induced voltage respectively.

[0065] U1=E m sin(w e t-120°)

[0066] U2=E m sinw e t

[0067] U3=E m sin(w e t+120°)

[0068] Instantaneous total electrical power P E Equal to the power P captured in the charging circuit c The power P lost in the internal resistance i The internal resistance is R i , the capacitance and resistance are R e , which can be expressed as:

[0069]

[0070] When the generator is working, the rotor angular velocity is proportional to the induced voltage. Then the induced voltage E m It can be expressed as:

[0071]

[0072] When the DC / DC converter controls the buck-boost, V IN With V OUT The relationship is:

[0073] D is the value of PWM duty cycle, V IN is the input voltage, V OUT Output voltage

[0074]

[0075] According to the energy conservation principle in the electromechanical field, P E It can also be expressed as:

[0076]

[0077] Where T E Represents the electromagnetic torque on the generator shaft, which is equal to the generator's rotational damping coefficient C R The product of the generator shaft speed γ is:

[0078]

[0079] Therefore, the controllable damping of the variable damping system in the energy feedback mode is C R (t):

[0080]

[0081] During the whole process, the value of the terminal voltage of the supercapacitor 407 is detected in real time. If the value does not exceed 8V, the supercapacitor is in charging mode. When the terminal voltage of the supercapacitor 407 exceeds 8V, the central control unit ECU9 receives a signal, controls the first switch 401 to close, and the second switch 402 to open, and the circuit enters the energy consumption mode. The energy is dissipated by the resistor 405 in the form of heat, and the supercapacitor 407 is discharged and stored in the battery after being boosted by the second DC / DC converter 5. At this time, the sensor detects the voltage and current data of the battery pack.

[0082] In the energy consumption mode, the motor and rectifier are equivalent to a voltage source e, and the internal resistance is R i , the external resistor is R e , D is the value of PWM duty cycle, equivalent resistance R E for:

[0083]

[0084] R m is the resistance value when the MOSFET switch is on, which can be set to 0Ω. The equivalent resistance of the external resistor and the MOSFET switch can be defined as follows:

[0085] R E =(1-D)R e

[0086] The generated voltage is proportional to the motor speed w, and the voltage constant is k e , the generated voltage can be obtained:

[0087] e=k e w

[0088] The current is I p, so that the torque T a for:

[0089]

[0090] where k i is the torque constant, k in the motor i =k e ;

[0091] Therefore, the controllable damping of the variable damping system in the energy consumption mode is c r (t):

[0092]

[0093] When the battery 12 is not fully charged, the third switch 403 is closed, the supercapacitor 407 continues to discharge, and the central control unit ECU9 detects the battery voltage and transmits it to the second PWM controller 13 to control the voltage of the battery 12. The current generated by the discharge of the supercapacitor 407, its voltage is boosted by the second DCDC controller 5 to obtain a voltage that is always higher than a certain value of the battery 12 voltage, and the battery 12 is charged. The electrical energy of the battery 12 can provide electrical energy for sensors or active control. When it is detected that the supercapacitor 407 is continuously discharging and the terminal voltage is less than 4V, the circuit enters the charging mode. When the battery 12 is full, the third switch 403 remains disconnected, the supercapacitor 407 stops discharging, its terminal voltage remains unchanged, and the control circuit remains in the energy consumption mode.

[0094] Furthermore, the four electromagnetic energy-feeding suspensions are an integrated system with the same structure, and can charge the battery 12 by recovering the energy of a single or multiple electromagnetic suspensions. If the battery pack 12 is discharging, but the discharge efficiency is lower than the charging efficiency of the four supercapacitors 407, the central control unit ECU9 controls the four normally closed switches 404 to be disconnected in turn, and the four supercapacitors 407 are discharged in turn. In this case, the total discharge efficiency of the supercapacitors 407 decreases, and frequent discharge and stop are not required.

Claims

1. A switchable energy-feeding electromagnetic suspension system, characterized in that: It includes an electromagnetic actuator, a three-phase rectifier, a first DC / DC converter, a switchable circuit, a second DC / DC converter, a linear displacement sensor, an acceleration sensor, a signal processor, a central control unit ECU, a PI controller, a first PWM controller, a battery pack, and a second PWM controller; The switchable circuit is composed of a first switch, a second switch, a third switch, a normally closed switch, a diode, a supercapacitor and a circuit thereof; when the second switch is closed and the first switch and the third switch are opened, the circuit enters a feeding mode, and the mechanical energy of the vehicle body vibration caused by road excitation is converted into electrical energy through an electromagnetic actuator and stored in a supercapacitor. Close the first switch, the third switch, and open the second switch, and the circuit enters the energy consumption mode. The principle is similar to the energy feeding mode, that is, the electrical energy is converted into heat and dissipated in the resistor. Due to the disconnection of the second switch, the heat dissipation of the resistor and the discharge process of the supercapacitor are independent of each other. The voltage of the energy stored in the supercapacitor is boosted by the second DC / DC converter and then input into the battery for storage. In a cycle of supercapacitor charging and discharging, the charging time is much longer than the discharge time, so the energy feeding mode is much longer than the energy consumption mode. The energy consumption mode accounts for a relatively low proportion of the entire cycle, which reduces the heating of the resistor and improves the energy utilization rate. PI controls the two modes of energy feeding and energy consumption, and adjusts the current of the energy feeding circuit by regulating the duty cycle through the PWM wave, so as to achieve adjustable damping force for vibration control of the cab suspension, and finally store the energy in the battery pack to achieve energy collection and vibration control of the energy feeding suspension.

2. The control strategy of the switchable energy-feeding electromagnetic suspension according to claim 1 is characterized in that: When the vehicle body vibrates, the electromagnetic suspension starts to work, and the central control unit ECU detects the terminal current and terminal voltage of the supercapacitor. If the terminal voltage is less than 4V, the circuit enters the energy feeding mode; the central control unit ECU controls the closing of the second switch and disconnects the first switch and the third switch; the circuit enters the energy feeding mode, the supercapacitor enters the charging mode, and the terminal voltage gradually increases; If its terminal voltage is greater than 4V, the circuit enters energy consumption mode to reduce the terminal voltage of the supercapacitor; When entering the energy feeding mode, U n (n=1,2,3) represents the induced voltage of each stator coil, E m and w e represent the amplitude and angular frequency of the induced voltage respectively; U1=E m sin(w e t-120°) U2=E m sinw e t U3=E m sin(w e t+120°) Instantaneous total electrical power P E Equal to the power P captured in the charging circuit c The power P lost in the internal resistance i The internal resistance is R i , the capacitance and resistance are R e , which can be expressed as: When the generator is working, the rotor angular velocity is proportional to the induced voltage, so the induced voltage E m It can be expressed as: When the DC / DC converter controls the buck-boost, V IN With V OUT The relationship is: D is the value of PWM duty cycle, V IN is the input voltage, V OUT is the output voltage; According to the energy conservation principle in the electromechanical field, P E It can also be expressed as: Where T E Represents the electromagnetic torque on the generator shaft, which is equal to the generator's rotational damping coefficient C R The product of the generator shaft speed γ is: Therefore, the controllable damping of the variable damping system in the energy feedback mode is C R (t): During the whole process of charging the supercapacitor, its terminal voltage value is detected in real time. If it does not exceed 8V, the supercapacitor is in charging mode continuously. When the terminal voltage of the supercapacitor exceeds 8V, the central control unit ECU receives a signal, controls the first switch to close and the second switch to open, and the circuit enters energy consumption mode. Energy is dissipated by the resistor in the form of heat, and the supercapacitor is discharged and stored in the battery pack after being boosted by the second DC / DC converter. At this time, the sensor detects the voltage and current data of the battery pack. In the energy consumption mode, the motor and rectifier are equivalent to a voltage source e, and the internal resistance is R i , the external resistor is R e , D is the value of PWM duty cycle, equivalent resistance R E for: R m is the resistance value when the MOSFET switch is on, which can be set to 0Ω. The equivalent resistance of the external resistor and the MOSFET switch can be defined as follows: R E =(1-D)R e The generated voltage is proportional to the motor speed w, and the voltage constant is k e , the generated voltage can be obtained: e=k e In The current is I p , so that the torque T a for: where k i is the torque constant, k in the motor i =k e ; Therefore, the controllable damping of the variable damping system in the energy consumption mode is c r (t): When the battery pack is not fully charged, the third switch is closed, the supercapacitor continues to discharge, the central control unit ECU detects the battery pack voltage, outputs a PWM and transmits it to the second PWM controller, the current and voltage generated by the supercapacitor discharge are stepped up and down by the second DCDC controller to obtain a voltage that is always higher than a certain value of the battery pack voltage, and the battery pack is charged; the battery's electrical energy can provide electrical energy for sensors or active control, when it is detected that the supercapacitor is continuously discharging and the terminal voltage is less than 4V, the circuit enters the charging mode; when the battery pack is fully charged, the third switch remains disconnected, the supercapacitor stops discharging, its terminal voltage remains unchanged, and the control circuit remains in the energy consumption mode.

3. A switchable energy-feeding electromagnetic suspension system according to claim 1, characterized in that: The four electromagnetic energy-feeding suspensions are an integrated system that can charge the battery by recovering the energy of a single or multiple electromagnetic suspensions. If the battery pack is discharging, but the discharge efficiency is lower than the charging efficiency of the four supercapacitors, the central control unit ECU can control the four normally closed switches to be disconnected in turn, and the four supercapacitors discharge in turn. In this case, the total discharge efficiency of the supercapacitors decreases, and frequent discharge and stopping are not required.

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