Differential active magnetic suspension control system and method

Abstract

The present invention discloses a differential active magnetic suspension control system and method. The system comprises an upper actuating coil, a lower actuating coil, an upper differential displacement sensor, a lower differential displacement sensor, a controller, an upper power amplifier and a lower power amplifier. The upper differential displacement sensor and the lower differential displacement sensor are respectively used to collect the distance between them and the suspended body, and feed back the displacement signal to the controller. The controller is used to calculate the displacement signal and the current feedback signal to obtain the control signal, and transmit the control signal to the upper power amplifier and the lower power amplifier respectively. The upper power amplifier and the lower power amplifier are used to control the current value of the upper actuating coil and the lower actuating coil respectively according to the control signal. The upper actuating coil and the lower actuating coil are used to generate electromagnetic force according to the corresponding current value, so that the suspended body is in a stable dynamic suspension state.

Description

Technical Field

[0001] The invention belongs to the field of automation technology, and in particular relates to a differential active magnetic suspension control system and method. Background Art

[0002] Active magnetic suspension system is a typical mechatronics technology. At present, most magnetic suspension control systems on the market use the analysis conclusions of negative spring theory and rotor dynamics model, and use computers to complete the control. The design process is very complicated. Mature engineering products are still controlled by individual companies in developed countries, and the price of the whole system is very high, often ranging from hundreds of thousands to millions of yuan.

[0003] Many domestic companies have also established their own large magnetic levitation bearing design teams, but now only a few of them have their own primary products, so the widespread application of magnetic levitation systems is largely restricted. Summary of the invention

[0004] In view of this, the main object of the present invention is to provide a differential active magnetic suspension control system and method.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] An embodiment of the present invention provides a differential active magnetic suspension control system, which includes an upper actuating coil, a lower actuating coil, an upper differential displacement sensor, a lower differential displacement sensor, a controller, an upper power amplifier, and a lower power amplifier; the upper actuating coil and the lower actuating coil are arranged opposite to each other and a space for suspending a suspended body is arranged between the two;

[0007] The upper differential displacement sensor and the lower differential displacement sensor are used to respectively collect the distance between them and the suspended body and feed back the displacement signal to the controller;

[0008] The controller is used to calculate the displacement signal and the current feedback signal to obtain a control signal, and transmit the control signal to the upper power amplifier and the lower power amplifier respectively;

[0009] The upper power amplifier and the lower power amplifier are used to control the current values ​​of the upper actuating coil and the lower actuating coil respectively according to the control signal;

[0010] The upper actuating coil and the lower actuating coil are used to generate electromagnetic force according to corresponding current values, so that the suspension body is in a stable dynamic suspension state.

[0011] In the above scheme, the controller includes an upper actuating coil control circuit and a lower actuating coil control circuit. The upper actuating coil control circuit is connected to the upper actuating coil and the upper differential displacement sensor, and is used to control the current of the upper actuating coil according to the current value of the upper actuating coil and the displacement signal collected by the upper differential displacement sensor; the lower actuating coil control circuit is connected to the lower actuating coil and the lower differential displacement sensor, and is used to control the current of the lower actuating coil according to the current value of the lower actuating coil and the displacement signal collected by the lower differential displacement sensor.

[0012] In the above scheme, the upper actuating coil control circuit and the lower actuating coil control circuit both include a position feedback circuit, a PID processing circuit, a current feedback circuit, a current sampling circuit, and a drive circuit; the position feedback circuit is used to calculate the set value and the displacement signal collected by the upper differential displacement sensor or the lower differential displacement sensor, and output the calculation result to the PID processing circuit;

[0013] The PID processing circuit is used to perform PID operation on the control signal of the upper actuating coil or the lower actuating coil, and the operation result is output to the current feedback circuit;

[0014] The current feedback circuit is used to calculate the PID calculation result and the current sampling value of the upper actuating coil or the lower actuating coil, and output the calculation result to the drive circuit;

[0015] The current sampling circuit is used to sample the current of the upper actuating coil or the lower actuating coil, and output the sampled value to the current feedback circuit;

[0016] The driving circuit is used to convert the control signal into a duty cycle signal, control the on and off of the high-power switch tube, and then control the current of the upper actuating coil or the lower actuating coil, and finally control the electromagnetic force of the upper actuating coil or the lower actuating coil to provide an electromagnetic force of appropriate size for the suspension of the suspended body.

[0017] In the above scheme, the position feedback circuit includes resistors R16 to R20 and an operational amplifier U3A. The first terminal of the operational amplifier U3A is connected to the PID processing circuit, the second terminal is grounded via resistor R17, the first path resistor R19 of the third terminal is connected to the upper differential displacement sensor or the lower differential displacement sensor, the second path resistor R18 is connected to the set value of the upper actuating coil or the lower actuating coil, the third path resistor R20 is grounded, the fourth terminal is connected to VCC, and the third terminal is connected to VEE; resistor R16 is connected between the first terminal and the 11th terminal of the operational amplifier U3A.

[0018] In the above scheme, the PID processing circuit includes capacitors C7 to C9, resistors R22 to R28, capacitors C7 to C9, operational amplifiers U4A, and operational amplifiers U4B. The first terminal of the operational amplifier U4A is connected to the sixth terminal of the operational amplifier U4B via resistor R26, the second terminal is connected to the third terminal via resistor R27, capacitor C9, resistor R28, and capacitor C7, the third terminal is grounded via resistor R21, the fourth terminal is connected to VCC, and the eleventh terminal is connected to VEE; one terminal of the capacitor C9 is connected to the position feedback circuit and the above operation circuit. The resistor R28 and the capacitor C7 are connected in parallel with the resistor R22, and both ends are connected to the second and third ends of the operational amplifier U4A respectively. The resistor R22 is connected in parallel with the capacitor C8; the fifth end of the operational amplifier U4B is grounded via the resistor R24, and the resistor R26 and the sixth end of the operational amplifier U4B are connected to the current feedback circuit via the resistor R25. The first end of the operational amplifier U4B outputs a signal to the upper actuating coil or the lower actuating coil via the resistor R25 and the current feedback circuit.

[0019] In the above scheme, the current feedback circuit includes an operational amplifier U5A, resistors R29 to R31, the first terminal of the operational amplifier U5A is connected to the drive circuit, the second terminal is connected to the current sampling circuit via resistor R32, the third terminal is grounded via resistor R30, and the other terminal is connected to the PID processing circuit via resistor R29, the fourth terminal is connected to VCC, and the 11th terminal is connected to VEE; the resistor R31 is connected between the first terminal and the second terminal of the operational amplifier U5A.

[0020] In the above scheme, the current sampling circuit includes an operational amplifier U6B, an operational amplifier U6A, and resistors R33 to R38. The third terminal of the operational amplifier U6B is connected to the current feedback circuit in one way, and is connected to the sixth terminal through a resistor R36 in the other way. The sixth terminal is connected to the first terminal of the operational amplifier U6A through a resistor R34, and the fifth terminal is grounded through a resistor R38; the first terminal of the operational amplifier U6A is connected to the second terminal through a resistor R35, the 11th terminal VEE, the second terminal is connected to the resistor R33 through a capacitor C10, the fourth terminal is grounded through a resistor R37, and the fourth terminal is connected to VCC; the two ends of the resistor R33 are connected to the drive circuit.

[0021] In the above scheme, the driving circuit includes a PWM chip, a diode D4, a transistor Q1, and a resistor R39. The VIN terminal of the PWM chip is connected to the PID processing circuit, one path of the PWM end is connected to VDD via the transistor Q1 and the upper actuating coil or the lower actuating coil, and the other path is connected to ground via the resistor R39. A diode D4 is connected in parallel to the upper actuating coil or the lower actuating coil; and both ends of the diode D4 are connected to the current sampling circuit.

[0022] In the above scheme, the upper differential displacement sensor and the lower differential displacement sensor both include an excitation source circuit, a probe circuit, a signal modulation circuit, and an upper and lower limit alarm circuit; the excitation source circuit is used to generate a sinusoidal wave excitation signal; the probe circuit is used to convert the displacement of the suspended body into a voltage signal. Under the action of the sinusoidal wave excitation signal, the voltage values ​​at both ends of the two inductance coil probes change approximately linearly with the displacement change of the suspended body, and the voltage signal of the inductance coil is processed into a DC voltage signal through a rectifier and a filter circuit; the signal modulation circuit is used to modulate the voltage signal of the inductance coil probe of the probe circuit and output a 0-5V standard voltage signal; the upper and lower limit alarm circuit is used to determine the upper and lower limit states of the position of the suspended body according to user settings.

[0023] An embodiment of the present invention also provides a differential active magnetic levitation control method, which comprises: respectively collecting the distances between the suspended body and the upper actuating coil and the lower actuating coil and generating a displacement signal, performing calculations based on the displacement signal and the current feedback signal to obtain a control signal, and controlling the current values ​​of the upper actuating coil and the lower actuating coil respectively according to the control signal; the upper actuating coil and the lower actuating coil generate electromagnetic force according to the corresponding current values, so that the suspended body is in a stable dynamic suspension state.

[0024] Compared with the prior art, the present invention uses a positive spring system in the design of a magnetic levitation control system, which greatly reduces the complexity of the design of the magnetic levitation control system. Control can be achieved using a simple digital-to-analog circuit; it breaks the monopoly of magnetic levitation technology and is conducive to the popularization and application of magnetic levitation technology; the circuit is simple and reliable, and the cost is greatly reduced. Its price is about one tenth of the market price. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A structural schematic diagram of a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0026] Figure 2 A circuit diagram of a position feedback circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0027] Figure 3 A circuit diagram of a PID processing circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0028] Figure 4 A circuit diagram of a current feedback circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0029] Figure 5 A circuit diagram of a current sampling circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0030] Figure 6A circuit diagram of a drive circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0031] Figure 7 A circuit diagram of an excitation circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0032] Figure 8 A circuit diagram of a probe circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0033] Fig. 9 A circuit diagram of a signal modulation circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0034] Fig.10 A circuit diagram of an upper and lower limit alarm circuit in a differential active magnetic suspension control system is provided for an embodiment of the present invention;

[0035] Fig.11 It is the structural diagram of the double spring system model;

[0036] Fig.12 It is a curve diagram of the change law of the actuating coil voltage;

[0037] Fig.13 It is a structural schematic diagram of the physical model of single-degree-of-freedom magnetic levitation with damping;

[0038] Fig.14 A flow chart of a differential active magnetic suspension control method is provided for an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] The embodiment of the present invention provides a differential active magnetic suspension control system, such as Figure 1 As shown, the system includes an upper actuating coil 1, a lower actuating coil 2, an upper differential displacement sensor 3, a lower differential displacement sensor 4, a controller 5, an upper power amplifier 6, and a lower power amplifier 7; the upper actuating coil 1 and the lower actuating coil 2 are arranged opposite to each other and a space for suspending a suspended body 8 is arranged between the two;

[0041] The upper differential displacement sensor 3 and the lower differential displacement sensor 4 are used to respectively collect the distance between them and the suspended body 8, and feed back the displacement signal to the controller 5;

[0042] The controller 5 is used to calculate the displacement signal and the current feedback signal to obtain a control signal, and transmit the control signal to the upper power amplifier 6 and the lower power amplifier 7 respectively;

[0043] The upper power amplifier 6 and the lower power amplifier 7 are used to control the current values ​​of the upper actuating coil 1 and the lower actuating coil 2 respectively according to the control signal;

[0044] The upper actuating coil 1 and the lower actuating coil 2 are used to generate electromagnetic force according to corresponding current values, so that the suspension body 8 is in a stable dynamic suspension state.

[0045] The controller 5 includes an upper actuating coil control circuit and a lower actuating coil control circuit. The upper actuating coil control circuit is connected to the upper actuating coil 1 and the upper differential displacement sensor 3, and is used to control the current of the upper actuating coil 1 according to the current value of the upper actuating coil 1 and the displacement signal collected by the upper differential displacement sensor 3; the lower actuating coil control circuit is connected to the lower actuating coil 2 and the lower differential displacement sensor 4, and is used to control the current of the lower actuating coil 2 according to the current value of the lower actuating coil 2 and the displacement signal collected by the lower differential displacement sensor 4.

[0046] The upper actuating coil control circuit and the lower actuating coil control circuit both include a position feedback circuit, a PID processing circuit, a current feedback circuit, a current sampling circuit, and a drive circuit; the position feedback circuit is used to calculate the set value and the displacement signal collected by the upper differential displacement sensor 3 or the lower differential displacement sensor 4, and output the calculation result to the PID processing circuit;

[0047] The PID processing circuit is used to perform PID operation on the control signal of the upper actuating coil 1 or the lower actuating coil 2, and the operation result is output to the current feedback circuit;

[0048] The current feedback circuit is used to calculate the PID calculation result and the current sampling value of the upper actuating coil 1 or the lower actuating coil 2, and output the calculation result to the drive circuit;

[0049] The current sampling circuit is used to sample the current of the upper actuating coil 1 or the lower actuating coil 2, and the sampled value is output to the current feedback circuit;

[0050] The driving circuit is used to convert the control signal into a duty cycle signal, control the on and off of the high-power switch tube, and then control the current of the upper actuating coil 1 or the lower actuating coil 2, and finally control the electromagnetic force of the upper actuating coil 1 or the lower actuating coil 2, providing an electromagnetic force of appropriate size for the suspension of the suspended body 8.

[0051] like Figure 2As shown, the position feedback circuit includes resistors R16 to R20 and an operational amplifier U3A. The first terminal of the operational amplifier U3A is connected to the PID processing circuit, the second terminal is grounded via a resistor R17, the first path resistor R19 of the third terminal is connected to the differential displacement sensor 3 or the lower differential displacement sensor 4, the second path resistor R18 is connected to the set value of the upper actuating coil 1 or the lower actuating coil 2, the third path resistor R20 is grounded, the fourth terminal is connected to VCC, and the 11th terminal is connected to VEE; the resistor R16 is connected between the first terminal and the 11th terminal of the operational amplifier U3A.

[0052] like Figure 3 As shown, the PID processing circuit includes capacitors C7 to C9, resistors R22 to R28, capacitors C7 to C9, operational amplifier U4A, and operational amplifier U4B. The first terminal of the operational amplifier U4A is connected to the sixth terminal of the operational amplifier U4B via resistor R26, the second terminal is connected to the third terminal via resistor R27, capacitor C9, resistor R28, and capacitor C7, the third terminal is grounded via resistor R21, the fourth terminal is connected to VCC, and the 11th terminal is connected to VEE; one terminal of the capacitor C9 is connected to the position feedback circuit and the upper actuating coil 1 or the input signal of the lower actuating coil 2, the resistor R22 is connected in parallel to the resistor R28 and the capacitor C7, and the two ends are respectively connected to the second and third ends of the operational amplifier U4A, and the capacitor C8 is connected in parallel to the resistor R22; the fifth end of the operational amplifier U4B is grounded via a resistor R24, and the resistor R26 and the sixth end of the operational amplifier U4B are connected to a current feedback circuit via a resistor R25, and the first end of the operational amplifier U4B outputs a signal to the upper actuating coil 1 or the lower actuating coil 2 via the resistor R25 and the current feedback circuit.

[0053] like Figure 4 As shown, the current feedback circuit includes an operational amplifier U5A, resistors R29 to R31, the first terminal of the operational amplifier U5A is connected to the drive circuit, the second terminal is connected to the current sampling circuit via the resistor R32, the third terminal is grounded via the resistor R30, and the other terminal is connected to the PID processing circuit via the resistor R29, the fourth terminal is connected to VCC, and the 11th terminal is connected to VEE; the resistor R31 is connected between the first and second terminals of the operational amplifier U5A.

[0054] like Figure 5As shown, the current sampling circuit includes an operational amplifier U6B, an operational amplifier U6A, and resistors R33 to R38. The third terminal of the operational amplifier U6B is connected to the current feedback circuit in one path, and is connected to the sixth terminal through a resistor R36 in another path. The sixth terminal is connected to the first terminal of the operational amplifier U6A through a resistor R34, and the fifth terminal is grounded through a resistor R38; the first terminal of the operational amplifier U6A is connected to the second terminal through a resistor R35, the 11th terminal is VEE, the second terminal is connected to the resistor R33 through a capacitor C10, the fourth terminal is grounded through a resistor R37, and the fourth terminal is connected to VCC; the two ends of the resistor R33 are connected to the drive circuit.

[0055] like Figure 6 As shown, the driving circuit includes a PWM chip, a diode D4, a transistor Q1, and a resistor R39. The VIN terminal of the PWM chip is connected to the PID processing circuit, one path of the PWM end is connected to VDD via the transistor Q1 and the upper actuating coil 1 or the lower actuating coil 2, and the other path is connected to ground via the resistor R39. A diode D4 is connected in parallel to the upper actuating coil 1 or the lower actuating coil 2; and both ends of the diode D4 are connected to the current sampling circuit.

[0056] Furthermore, the upper differential displacement sensor 3 and the lower differential displacement sensor 4 both include an excitation source circuit, a probe circuit, a signal modulation circuit, and an upper and lower limit alarm circuit; the excitation source circuit is used to generate a sinusoidal wave excitation signal; the probe circuit is used to convert the displacement of the suspended body 8 into a voltage signal. Under the action of the sinusoidal wave excitation signal, the voltage values ​​at both ends of the two inductance coil probes change approximately linearly with the displacement change of the suspended body 8, and the voltage signal of the inductance coil is processed into a DC voltage signal through a rectification and filtering circuit; the signal modulation circuit is used to modulate the voltage signal of the inductance coil probe of the probe circuit and output a 0-5V standard voltage signal; the upper and lower limit alarm circuit is used to determine the upper and lower limit states of the position of the suspended body 8 according to user settings.

[0057] like Figure 7 As shown, the excitation source circuit includes an operational amplifier U1, resistors R1 to R5, capacitors C1, C2, diode D1, and diode D2. The sixth terminal of the operational amplifier U1 outputs a sinusoidal wave excitation signal POS0, the third terminal is grounded via capacitor C1, the other terminal is connected to the sixth terminal via capacitor C2 and resistor R2, the second terminal is grounded via resistor R4, the fourth and fifth terminals are connected to VEE and VCC respectively, the capacitor C1 is connected in parallel with resistor R1, one end of the resistor R3 is connected between the second terminal of the operational amplifier U1 and resistor R4, and the other end is connected to the sixth terminal of the operational amplifier U1 via resistor R5; diodes D1 and diode D2 are connected in parallel on both sides of the resistor R5 respectively;

[0058] like Figure 8As shown, the probe circuit includes an inductor coil probe L1, an inductor coil probe L2, capacitors C3 to C5, a full-bridge rectifier circuit D3, a resistor R6, and a resistor R15. The first end of the full-bridge rectifier circuit D3 is connected between the inductor coil probe L1 and the inductor coil probe L2 in series via the capacitor C3, the second and fourth ends are respectively connected to one end of the inductor coil probe L2, and the third end is connected to one end of the inductor coil probe L2 via the resistor R6 and the resistor R15. The third end of the full-bridge rectifier circuit D3 is between one end of the inductor coil probe L2, and the two ends of the resistor R6 are respectively connected in parallel with the capacitor C5 and the capacitor C4; one end of the inductor coil probe L1 is connected to the sinusoidal wave excitation signal POS0, and the other end of the inductor coil probe L2 is grounded;

[0059] like Fig. 9 As shown, the signal modulation circuit includes an operational amplifier U2D, an operational amplifier U2B, an operational amplifier U2C, resistors R7 to R13, and a capacitor C6. The first terminal of the operational amplifier U2D outputs a signal, and the other terminal is connected to the seventh terminal of the operational amplifier U2B through resistors R13 and R11. The 11th terminal is connected to VEE, the third terminal is connected between the resistors R13 and R11, the 14th terminal is connected to the eighth terminal of the operational amplifier U2C through resistor R12, and the other terminal is connected to VCC through resistor R14 and capacitor C6. The operational amplifier U2B and The 4th terminal of the operational amplifier U2C is connected between the capacitor C6 and VCC, the 6th terminal of the operational amplifier U2B is connected to the 9th terminal of the operational amplifier U2C via the resistor R8, the 11th terminal of the operational amplifier U2B is connected to the 11th terminal of the operational amplifier U2C, one end of the resistor R8D is connected between the 7th terminal of the operational amplifier U2B and the resistor R11 via the resistor R9, and the other end is connected between the 8th terminal of the operational amplifier U2C and the resistor R12 via the resistor R10, one end of the resistor R7 is connected between the capacitor C6 and the resistor R14, and the other end is connected to VCC.

[0060] like Fig.10 As shown, the upper and lower limit alarm circuit includes an operational amplifier U3A, an operational amplifier U3B, and resistors R16 to R21. The first terminals of the operational amplifier U3A and the operational amplifier U3B are connected in common to output a high level and are connected to VCC via resistor R19. The second terminal of the operational amplifier U3A is connected to resistor R20 via resistor R16, and the third terminal is connected to a signal modulation circuit via resistor R18. The second terminal of the operational amplifier U3B is connected to the third terminal of the operational amplifier U3A, and the third terminal is connected to resistor R21 via resistor R17; one terminal of the resistor R20 is connected to VCC, and the other terminal is grounded; one terminal of the resistor R21 is connected to VCC, and the other terminal is grounded.

[0061] This patent is applicable to the design of radial magnetic bearings, axial magnetic bearings, maglev trains, maglev gyroscopes and momentum wheels, and can be applied to rotating machinery and linear motion machinery. Once the magnetic levitation bearing technology becomes popular, it will have a profound impact on the upgrading of the manufacturing industry, energy conservation and environmental protection, and the reduction of noise pollution.

[0062] like Fig.11 As shown in the figure, the ball m is connected to a spring K1 and a spring K2 at the top and bottom. In order to conveniently describe the change of the tension of the two springs on the ball m, the mass of the ball m itself is ignored during the movement.

[0063] When the ball m deviates from the equilibrium position and moves downward, the deformation of the upper spring K1 increases, and the tension of the upper spring K1 increases. At the same time, the deformation of the lower spring K2 decreases, and the tension of the lower spring K2 decreases. At this time, the total tension on the ball m is the upward restoring force, which causes the ball m to move upward and return to the equilibrium position.

[0064] When the ball m deviates from the equilibrium position and moves upward, the force it is subjected to is opposite, and the ball m will move downward and return to the equilibrium position.

[0065] Obviously, such a double spring system is a stable system, so the present invention has the ability to automatically return to a balanced position.

[0066] The present invention utilizes a differential displacement sensor and a differential control circuit to realize such a double-spring stabilization system.

[0067] The process description of the change law of the actuating coil voltage:

[0068] like Fig.12 As shown, at the initial stage of power-on, the voltage of actuating coil 1 is greater than the voltage of actuating coil 2, and the suspension will move toward the direction of actuating coil 1.

[0069] When the suspension passes the equilibrium position in the positive direction of X, the voltage of the actuating coil 2 is greater than the voltage of the actuating coil 1, and the suspension automatically moves to the negative direction of X and returns to the equilibrium position.

[0070] When the suspension moves in the negative direction of X beyond the equilibrium point, the voltage of the actuating coil 1 is greater than the voltage of the actuating coil 2, and the suspension moves in the positive direction of X again.

[0071] This kind of control is just like the double spring system, converting the whole system into a steady-state system.

[0072] The principle of current feedback in the present invention is described as follows:

[0073] The physical model of single-degree-of-freedom magnetic levitation with damping, such as Fig.13As shown in (2), the mathematical model of single-degree-of-freedom magnetic levitation is ma=Qy+Pi, where m is mass, a is acceleration, Qy is displacement term, and Pi is current. Current feedback is the damping term of the system. Appropriate selection of current feedback parameters can effectively improve the stiffness of the system and is conducive to the stable operation of the system.

[0074] The present invention starts from the physical principle of electromagnetic force of magnetic suspension bearings, adjusts the magnitude of the actuating force by adjusting the current of the actuating coil, and uses the differential displacement sensor signal to adjust the voltage of the electromagnetic actuating coil. The original negative spring system is cleverly converted into a positive spring system, so that the suspension can automatically return to the equilibrium position, thereby revealing the inherent essential law of active magnetic suspension bearings. The entire system becomes a form similar to a "tumbler", and the suspension vibrates slightly around the equilibrium position. As long as the parameters are selected appropriately, high control accuracy can be obtained.

[0075] It is particularly important to note that after adopting the differential control method, a simple digital-to-analog circuit can be used to realize the control of the active magnetic bearing, simplifying the original complex design work into a design work that can be completed by two or three people, and the economy is very significant.

[0076] The embodiment of the present invention also provides a differential active magnetic suspension control method, such as Fig.14 As shown, the method is: respectively collecting the distances between the suspended body 8 and the upper actuating coil 1 and the lower actuating coil 2 and generating a displacement signal, performing calculations based on the displacement signal and the current feedback signal to obtain a control signal, and respectively controlling the current values ​​of the upper actuating coil 1 and the lower actuating coil 2 according to the control signal; the upper actuating coil 1 and the lower actuating coil 2 generate electromagnetic forces based on the corresponding current values, so that the suspended body 8 is in a stable dynamic suspension state.

[0077] After the system is powered on, current flows through the upper actuating coil 1, and the electromagnetic force generated by it causes the suspension 8 to move upward. At this time, the differential displacement sensor measures the distance the suspension 8 moves upward and transmits the displacement signal to the controller 5; after the controller 5 calculates the displacement signal and the current feedback signal, it transmits the control signal to the upper power amplifier 6 and the lower power amplifier 7 respectively.

[0078] The upper power amplifier 6 and the lower power amplifier 7 respectively control the current values ​​of the upper actuating coil 1 and the lower actuating coil 2, and then control the electromagnetic force generated by the upper actuating coil 1 and the lower actuating coil 2, so that the suspension 8 gradually moves to the equilibrium position. After the above closed-loop control, the suspension 8 finally reaches the equilibrium position and is in a stable dynamic suspension state.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A differential active magnetic suspension control system, characterized in that: The system comprises an upper actuating coil, a lower actuating coil, an upper differential displacement sensor, a lower differential displacement sensor, a controller, an upper power amplifier, and a lower power amplifier; the upper actuating coil and the lower actuating coil are arranged opposite to each other and a space for suspending a floating body is arranged between the two; The upper differential displacement sensor and the lower differential displacement sensor are used to respectively collect the distance between them and the suspended body and feed back the displacement signal to the controller; The controller is used to calculate the displacement signal and the current feedback signal to obtain a control signal, and transmit the control signal to the upper power amplifier and the lower power amplifier respectively; The upper power amplifier and the lower power amplifier are used to control the current values ​​of the upper actuating coil and the lower actuating coil respectively according to the control signal; The upper actuating coil and the lower actuating coil are used to generate electromagnetic force according to the corresponding current value, so that the suspended body is in a stable dynamic suspension state; Wherein, the upper differential displacement sensor and the lower differential displacement sensor both include an excitation source circuit, a probe circuit, a signal modulation circuit, and an upper and lower limit alarm circuit; the excitation source circuit is used to generate a sinusoidal wave excitation signal; the probe circuit is used to convert the displacement of the suspension into a voltage signal. Under the action of the sinusoidal wave excitation signal, the voltage values ​​at both ends of the two inductance coil probes change approximately linearly with the displacement change of the suspension, and the voltage signal of the inductance coil is processed into a DC voltage signal through a rectifier and a filter circuit; the signal modulation circuit is used to modulate the voltage signal of the inductance coil probe of the probe circuit and output a 0-5V standard voltage signal; the upper and lower limit alarm circuit is used to determine the upper and lower limit states of the position of the suspension according to user settings; The excitation source circuit includes an operational amplifier U1, resistors R1 to R5, capacitors C1, C2, diode D1, and diode D2. The sixth terminal of the operational amplifier U1 outputs a sinusoidal wave excitation signal POS0, the third terminal is grounded via capacitor C1, the other terminal is connected to the sixth terminal via capacitor C2 and resistor R2, the second terminal is grounded via resistor R4, the fourth and fifth terminals are connected to VEE and VCC respectively, the capacitor C1 is connected in parallel with resistor R1, one end of the resistor R3 is connected between the second terminal of the operational amplifier U1 and resistor R4, and the other end is connected to the sixth terminal of the operational amplifier U1 via resistor R5; diodes D1 and diode D2 are connected in parallel on both sides of the resistor R5 respectively.

2. The differential active magnetic suspension control system according to claim 1, characterized in that: The controller includes an upper actuating coil control circuit and a lower actuating coil control circuit. The upper actuating coil control circuit is connected to the upper actuating coil and the upper differential displacement sensor, and is used to control the current of the upper actuating coil according to the current value of the upper actuating coil and the displacement signal collected by the upper differential displacement sensor; the lower actuating coil control circuit is connected to the lower actuating coil and the lower differential displacement sensor, and is used to control the current of the lower actuating coil according to the current value of the lower actuating coil and the displacement signal collected by the lower differential displacement sensor.

3. The differential active magnetic suspension control system according to claim 2, characterized in that: The upper actuating coil control circuit and the lower actuating coil control circuit both include a position feedback circuit, a PID processing circuit, a current feedback circuit, a current sampling circuit, and a drive circuit; the position feedback circuit is used to calculate the set value and the displacement signal collected by the upper differential displacement sensor or the lower differential displacement sensor, and output the calculation result to the PID processing circuit; The PID processing circuit is used to perform PID operation on the control signal of the upper actuating coil or the lower actuating coil, and the operation result is output to the current feedback circuit; The current feedback circuit is used to calculate the PID calculation result and the current sampling value of the upper actuating coil or the lower actuating coil, and output the calculation result to the drive circuit; The current sampling circuit is used to sample the current of the upper actuating coil or the lower actuating coil, and output the sampled value to the current feedback circuit; The driving circuit is used to convert the control signal into a duty cycle signal, control the on and off of the high-power switch tube, and then control the current of the upper actuating coil or the lower actuating coil, and finally control the electromagnetic force of the upper actuating coil or the lower actuating coil to provide an electromagnetic force of appropriate size for the suspension of the suspended body.

4. The differential active magnetic suspension control system according to claim 3, characterized in that: The position feedback circuit includes resistors R16 to R20 and an operational amplifier U3A. The first terminal of the operational amplifier U3A is connected to the PID processing circuit, the second terminal is grounded via resistor R17, the first path resistor R19 of the third terminal is connected to the upper differential displacement sensor or the lower differential displacement sensor, the second path resistor R18 is connected to the set value of the upper actuating coil or the lower actuating coil, the third path resistor R20 is grounded, the fourth terminal is connected to VCC, and the 11th terminal is connected to VEE; the resistor R16 is connected between the first terminal and the 11th terminal of the operational amplifier U3A.

5. The differential active magnetic suspension control system according to claim 4, characterized in that: The PID processing circuit includes capacitors C7 to C9, resistors R22 to R28, capacitors C7 to C9, operational amplifier U4A, and operational amplifier U4B. The first terminal of the operational amplifier U4A is connected to the sixth terminal of the operational amplifier U4B via resistor R26, the second terminal is connected to the third terminal via resistor R27, capacitor C9, resistor R28, and capacitor C7, the third terminal is grounded via resistor R21, the fourth terminal is connected to VCC, and the 11th terminal is connected to VEE; one terminal of the capacitor C9 is connected to the position feedback circuit and the upper actuating coil or the input signal of the lower actuating coil, the resistor R22 is connected in parallel to the resistor R28 and the capacitor C7, and both ends are respectively connected to the 2nd and 3rd ends of the operational amplifier U4A, and the capacitor C8 is connected in parallel to the resistor R22; the 5th end of the operational amplifier U4B is grounded via a resistor R24, and the resistor R26 and the 6th end of the operational amplifier U4B are connected to a current feedback circuit via a resistor R25, and the 1st end of the operational amplifier U4B outputs a signal to the upper actuating coil or the lower actuating coil via the resistor R25 and the current feedback circuit.

6. The differential active magnetic suspension control system according to claim 5, characterized in that: The current feedback circuit includes an operational amplifier U5A, resistors R29 to R31, the first terminal of the operational amplifier U5A is connected to the drive circuit, the second terminal is connected to the current sampling circuit via resistor R32, the third terminal is grounded via resistor R30, and the other terminal is connected to the PID processing circuit via resistor R29, the fourth terminal is connected to VCC, and the 11th terminal is connected to VEE; the resistor R31 is connected between the first and second terminals of the operational amplifier U5A.

7. The differential active magnetic suspension control system according to claim 6, characterized in that: The current sampling circuit includes an operational amplifier U6B, an operational amplifier U6A, and resistors R33 to R38. The third terminal of the operational amplifier U6B is connected to the current feedback circuit in one path, and is connected to the sixth terminal through a resistor R36 in another path. The sixth terminal is connected to the first terminal of the operational amplifier U6A through a resistor R34, and the fifth terminal is grounded through a resistor R38; the first terminal of the operational amplifier U6A is connected to the second terminal through a resistor R35, the 11th terminal is VEE, the second terminal is connected to the resistor R33 through a capacitor C10, the fourth terminal is grounded through a resistor R37, and the fourth terminal is connected to VCC; the two ends of the resistor R33 are connected to the drive circuit.

8. The differential active magnetic suspension control system according to claim 7, characterized in that: The driving circuit includes a PWM chip, a diode D4, a transistor Q1, and a resistor R39. The VIN terminal of the PWM chip is connected to the PID processing circuit, one path of the PWM end is connected to VDD via the transistor Q1 and the upper actuating coil or the lower actuating coil, and the other path is connected to ground via the resistor R39. A diode D4 is connected in parallel to the upper actuating coil or the lower actuating coil; and both ends of the diode D4 are connected to the current sampling circuit.

9. A control method for a differential active magnetic suspension control system according to any one of claims 1 to 8, characterized in that: The control method comprises: respectively collecting the distance between the suspended body and the upper actuating coil and the lower actuating coil and generating a displacement signal, performing calculations based on the displacement signal and the current feedback signal to obtain a control signal, and respectively controlling the current values ​​of the upper actuating coil and the lower actuating coil based on the control signal; the upper actuating coil and the lower actuating coil generate electromagnetic force based on the corresponding current values, so that the suspended body is in a stable dynamic suspension state; The distances between the suspended body and the upper actuating coil and the lower actuating coil are respectively collected and a displacement signal is generated, including: The displacement of the suspension is converted into a voltage signal. Under the action of the sinusoidal wave excitation signal, the voltage value at both ends of the two inductance coil probes changes approximately linearly with the displacement change of the suspension. The voltage signal of the inductance coil is processed into a DC voltage signal through rectification and filtering circuits. The voltage signal of the inductor coil probe of the probe circuit is modulated, and a 0-5V standard voltage signal is output to obtain a displacement signal.

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