A fault-tolerant control method and system for superconducting motors considering quench failure.

Abstract

The application discloses a superconducting motor fault-tolerant control method and system considering quench faults, and belongs to the field of motor control. The method obtains a rotor flux estimation value by using a rotor flux estimation model according to a voltage control vector and a response current vector; if it is determined that a superconducting motor has occurred a quench fault, the method obtains a state current observation value of the superconducting motor under the quench fault by using a state current observation model according to the rotor flux estimation value and the response current vector; the method determines a voltage control vector of the superconducting motor under the quench fault by using a fault-tolerant control model according to a given current vector, the state current observation value of the superconducting motor under the quench fault and the response current vector; and the method applies the voltage control vector to the superconducting motor, so that the response current vector of the superconducting motor under the quench fault is equal to the given current vector. The application can effectively solve the robustness control problem of the superconducting motor when the quench fault occurs, and realizes stable operation of the superconducting motor.

Description

Technical Field

[0001] This invention relates to the field of motor control, and in particular to a fault-tolerant control method and system for superconducting motors that takes into account quenching faults. Background Technology

[0002] Superconductors possess three fundamental properties: zero resistance, the Meissner effect, and the Josephson effect. Critical temperature, critical magnetic field, and critical current are three crucial parameters of a superconductor. If any of these parameters exceeds its critical value, the superconducting magnet will undergo a phase transition, becoming a normal conductor; this process is called loss of quench.

[0003] Superconducting motors offer high power density, effectively addressing the capacity expansion bottleneck of traditional wind turbines. For offshore wind farms, the transportation and installation costs of superconducting motors will be significantly lower than those of heavy traditional wind turbines. Furthermore, China's second-generation high-temperature superconducting materials boast world-leading performance, while their price is approaching that of copper wire with comparable performance. The industrialization of superconducting products, represented by superconducting motors, is becoming increasingly apparent.

[0004] For various reasons, the temperature, magnetic field, or current in a localized area of ​​a high-temperature superconducting material may exceed a critical value. This region will then exit the superconducting state and transition to a normal state. If the region quickly recovers to the superconducting state, this process is called recoverable quenching. If the region remains in the normal state and the normal state propagates to the surrounding superconducting regions, causing the normal state region to expand continuously, this process is called irrecoverable quenching.

[0005] The excitation coil of a high-temperature superconducting wind turbine operates under constant DC conditions. Under DC conditions, the critical current value of the coil is one of the important indicators for evaluating its performance. When the operating current of the excitation coil exceeds its critical current, the coil faces the danger of quenching, which can seriously affect the stable and safe operation of the high-temperature superconducting motor. When a superconducting motor quenches, the superconductor transitions from a superconducting state with zero resistance to a normal state with relatively high resistance. The excitation current decreases sharply, thus reducing the magnetic flux generated by the rotor. The stator current is limited, leading to a loss of the motor's load-bearing capacity and motor deceleration. Summary of the Invention

[0006] The purpose of this invention is to provide a fault-tolerant control method and system for superconducting motors that takes into account quench failure, which can effectively solve the robust control problem faced by superconducting motors when quench failure occurs and achieve stable operation of superconducting motors.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A fault-tolerant control method for superconducting motors considering quench failure includes:

[0009] A rotor flux estimation model is established; a state current observation model for the superconducting motor under quench fault is constructed; a fault-tolerant control model for the superconducting motor under quench fault is established; based on the current voltage control vector and the current response current vector, the rotor flux estimation model is used to obtain the estimated rotor flux value at the current moment; if the difference between the estimated rotor flux value at the current moment and the estimated rotor flux value at the previous moment is large, it is determined that the superconducting motor has experienced a quench fault; based on the current rotor flux estimation value and the current response current vector, the state current observation model is used to obtain the observed state current value of the superconducting motor under quench fault; based on the given current vector, the observed state current value of the superconducting motor under quench fault, and the current response current vector, the fault-tolerant control model is used to determine the voltage control vector of the superconducting motor under quench fault; the voltage control vector of the superconducting motor under quench fault is applied to the superconducting motor, so that the response current vector of the superconducting motor under quench fault is equal to the given current vector, thereby controlling the superconducting motor to operate stably.

[0010] A fault-tolerant control system for a superconducting motor that considers quenching faults, the system comprising: a fault-tolerant controller, a flux detection module, and a state current observation module.

[0011] The flux detection module is connected to both the fault-tolerant controller and the state current observation module. The state current observation module is connected to the fault-tolerant controller. The flux detection module performs flux detection based on the response current vector and the voltage control vector output by the fault-tolerant controller at each moment to obtain the rotor flux estimate at each moment. When the rotor flux estimate at the current moment differs from the rotor flux estimate at the previous moment, it determines that the superconducting motor has experienced a quench fault and transmits the rotor flux estimate at the current moment to the state current observation module. The state current observation module uses the rotor flux estimate at the current moment and the response current vector at the current moment, and employs a state current observation model to obtain the state current observation value under the quench fault condition of the superconducting motor. The fault-tolerant controller, given the current vector, the state current observation value under the quench fault condition of the superconducting motor, and the response current vector at the current moment, uses a fault-tolerant control model to determine the voltage control vector under the quench fault condition of the superconducting motor, and applies the voltage control vector to the superconducting motor to make the response current vector under the quench fault condition equal to the given current vector, thereby controlling the superconducting motor to operate stably.

[0012] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0013] This invention discloses a fault-tolerant control method and system for superconducting motors considering quench faults. It identifies the magnitude of the rotor flux linkage of the superconducting motor through a rotor flux linkage estimation model, and then calculates the observed state current value in real time using a state current observation model. This state current observation value is used as a feedback quantity to determine the voltage control vector under quench fault conditions. The voltage control vector under quench fault conditions is applied to the superconducting motor, enabling the response current to accurately track the given current, ensuring continued operation of the superconducting motor after quench faults, thereby achieving fault-tolerant control. This effectively solves the robust control problem faced by superconducting motors when quench faults occur, and realizes stable operation of the superconducting motor. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic flowchart of a fault-tolerant control method for superconducting motors that considers quench failure, provided in Embodiment 1 of the present invention.

[0016] Figure 2 This is a schematic diagram of rotor angle conversion provided in Embodiment 1 of the present invention.

[0017] Figure 3 This is a schematic diagram of the variation of the rotor flux of the superconducting motor provided in Embodiment 1 of the present invention.

[0018] Figure 4 This is a control block diagram of a superconducting motor fault-tolerant control system considering quench failure provided in Embodiment 2 of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a fault-tolerant control method for superconducting motors that takes into account quenching faults. The method includes a superconducting motor control method based on model predictive control and a self-tuning identification method for rotor flux linkage.

[0021] This invention combines model predictive control with self-tuning identification of rotor flux linkage. First, based on the current predictive control model of the superconducting motor, the impact of magnetic field reduction on current control and motor operating state is analyzed. Second, based on the integral of induced voltage and current during controlled rotor motion, a mathematical model is developed to accurately observe the flux linkage and obtain the observed value of the state current. Finally, the observed value of the state current is fed back to the controller, enabling the response current to accurately track the given current, thereby achieving stable motor operation.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1

[0024] like Figure 1 As shown in this embodiment, a fault-tolerant control method for a superconducting motor considering quench failure includes:

[0025] Step 1: Establish a rotor flux estimation model.

[0026] The rotor flux linkage of a superconducting motor can be represented along the αβ axis, as shown below:

[0027]

[0028] Where, λ αβ i aβ It represents the total magnetic flux and current along the αβ axis.

[0029] The initial excitation current of the superconducting motor is It is the shaft excitation current, I nom This is the normal motor current, which aligns and stabilizes the rotor in one position, so that... Where θ me It is the mechanical position of the rotor. This is the rotor position during open-loop operation. Through the rotating current vector, the rotor is forced to rotate by an angle Δθ at the instant t = t0. At t = t1, the rotor stabilizes at the angle Δθ.

[0030] The transition angle Δθ can be any angle from 0 to 2π. The rotor angle transition can be abrupt or a smooth, controlled transition (e.g., ...). Figure 2 (As shown). Since the implementation is based on voltage and current values ​​on the αβ axis, and the transition method is not expected to have a significant impact on parameter estimation due to the difference between the initial and final angles.

[0031] The total magnetic flux at time t = t1 can be expressed as:

[0032]

[0033] where v αβ is the voltage on the αβ axis, and λ αβ (t0) is the total magnetic flux at t = t0, and R s is the stator resistance of the superconducting motor. Therefore:

[0034]

[0035] The magnetic flux within the time interval t0 < t < t1 can be expressed as:

[0036]

[0037] That is:

[0038]

[0039] Secondly, the superconducting magnetic flux at t = t0 and t = t1 can be expressed as:

[0040]

[0041] where Λ is the amplitude of the superconducting magnetic flux.

[0042]

[0043]

[0044] From the above equation, we can obtain:

[0045]

[0046] Applying the product cosine trigonometric identity for summation, the above equation can be rewritten as:

[0047]

[0048] Therefore:

[0049]

[0050] Similarly:

[0051]

[0052] In the formula, is the component of the rotor magnetic flux on the α axis at t1, is the component of the rotor magnetic flux on the α axis at t0, Λ is the amplitude of the superconducting magnetic flux, is the rotor position at the open-loop t0, and Δθ is the angle by which the rotor moves under the rotating current vector; is the component of the rotor magnetic flux on the β axis at t1, is the component of the rotor magnetic flux on the β axis at t0.

[0053] Therefore, Λ can be calculated using superconducting flux linkage, while the rotor moves by an angle Δθ:

[0054]

[0055] The rotor flux linkage amplitude of the superconducting motor can be obtained from equation (5):

[0056]

[0057] Substituting equation (16) into equation (6), we can obtain... and λ αβ (t0).

[0058] After obtaining the estimated value of the superconducting motor rotor flux linkage on the αβ axis through the above steps, the estimated value of the rotor flux linkage on the dq axis can be obtained by changing the park value, that is:

[0059]

[0060] In the formula, and These are the estimated values ​​of the rotor flux linkage on the d-axis and q-axis, respectively. This represents the rotor position during open-loop operation. and These are the estimated values ​​of rotor flux linkage on the α-axis and β-axis, respectively; Let be the rotor flux linkage vector at time t1, and Λ be the amplitude of the superconducting flux linkage. The rotor position at time t1 when the loop is open; u is an estimated value of the superconducting flux linkage amplitude. αβ For voltage control vector, i αβ In response to the current vector, Here is the estimated stator resistance of the superconducting motor, L is the reactance, and i is the value of the stator resistance. αβ (t1) represents the total magnetic flux at time t1, and λ αβ (t0) represents the total flux linkage at time t0.

[0061] Step 2: Construct a state current observation model for a superconducting motor under quench fault conditions.

[0062] The specific steps of predictive control for superconducting motors are as follows:

[0063] The voltage equation for a superconducting motor in a dq synchronous shaft system is:

[0064]

[0065] In the formula: u d ,u q Let i be the voltage across the dq axis. d i qLet R be the dq-axis current, R be the stator resistance, ω be the electric angular velocity, and λ be the electric angular velocity. d ,λ q This represents the component of the stator flux linkage on the dq axis.

[0066] The flux linkage equation is as follows:

[0067]

[0068] L d ,L q For d-axis reactance and q-axis reactance, λ f0 It is a permanent magnet flux linkage.

[0069] When a superconducting motor experiences de-quenching, the superconductor in the rotor transitions from a superconducting state to a normal state, significantly increasing the rotor resistance and drastically reducing the excitation current. This results in a decrease in the magnetic flux linkage generated by the rotor. During de-quenching, the motor's magnetic flux vector changes from its initial value of λ. f0 Transform into λ f There is a deviation angle γ between the direction of the motor's magnetic field and the direction of the rotor magnetic flux, such as Figure 3 As shown. Its components on the dq axis are:

[0070]

[0071] By choosing the d-axis and q-axis currents as the system state variables, the state equations of the superconducting motor in the dq coordinate system can be obtained as follows:

[0072]

[0073] in:

[0074]

[0075] The first-order Euler method is used to discretize equation (21) to obtain the discrete state-space function of the superconducting motor under fault conditions, as shown below:

[0076]

[0077] in:

[0078]

[0079]

[0080]

[0081] T s One control cycle.

[0082] Assuming the superconducting motor is at kT sIf the timer runs normally, the magnetic field loss occurs at (k+1)T. s Time. The controller first determines the time based on the motor's position at kT. s The current normal operating state of time is used to calculate in (k+1)T s The voltage vector to be applied at time (k+1)T. s At that moment, from kT s The voltage vector calculated at each moment is applied to the actual motor model experiencing a quench fault to generate a new response current vector i(k+1), the process of which can be represented by equation (23). It can be concluded that:

[0083]

[0084] in:

[0085]

[0086] i * (k+1) is a given current vector.

[0087] After a superconducting motor experiences a quench failure, Δλ fd <0,Δλ fq >0, adopt The control strategy. Where Δλ fd Let Δλ be the change in magnetic flux along the d-axis. fq Let be the change in magnetic flux along the q-axis.

[0088] λ ext =λ f0 +(L d -L q )i d (twenty four)

[0089] Where λ ext This refers to the effective flux linkage of the motor.

[0090] The electromagnetic torque equation of a superconducting motor is expressed as:

[0091]

[0092] T e n is the electromagnetic torque of the motor. p Magnetic field is the number of pole pairs of the motor, λ s For the magnetic flux of the motor, i s This is the stator current of the motor.

[0093] As can be seen from equation (23), there is a current deviation i after the magnetic field loss. d =Δi d >0, which will result in an effective flux linkage ψ ext The decrease. If equation (25) is maintained, iq This will increase, and from equation (23), we can see the current deviation after flux loss, therefore i q This will increase further. The motor uses i d =0 control strategy, i q It cannot exceed the limit value i smax Therefore, the electromagnetic torque will decrease. The discrete state-space function (21) of the superconducting motor under fault conditions is rewritten as:

[0094]

[0095] State current observations and They are respectively:

[0096]

[0097] The above process can be summarized as follows: The response current vector is transformed from the αβ coordinate system to the dq coordinate system; based on the response current vector and the estimated rotor flux in the dq coordinate system, the state current observation model of the superconducting motor under quench fault is constructed as follows:

[0098]

[0099]

[0100] In the formula, and These are the observed state current values ​​on the d-axis and q-axis under discrete state k, respectively, where R is the stator resistance and L is the current. d and L q The reactances T along the d-axis and q-axis are respectively. s For one control cycle; i d (k) and i q (k) represents the response currents along the d-axis and q-axis in discrete state k, i d (k) and i q The vector formed by (k) is the response current vector in the dq coordinate system; ω(k) is the electric angular velocity in discrete state k. and These are the estimated values ​​of rotor flux linkage on the d-axis and q-axis, respectively.

[0101] Step 3: Establish a fault-tolerant control model for the superconducting motor under quench failure.

[0102] Substituting equation (27) into equation (26):

[0103]

[0104] By selecting the d-axis and q-axis currents as system state variables, the discrete state-space function of the superconducting motor under fault conditions can be obtained as follows:

[0105]

[0106] When the fault condition is obtained through equation (29), the voltage vector output by the fault-tolerant controller is:

[0107]

[0108] Equation (30) is equivalent to:

[0109]

[0110]

[0111] In the formula, u d (k) and u q (k) represent the voltage control quantities along the d-axis and q-axis under discrete state k, respectively, i d * (k+1) and i q * (k+1) represent the given currents on the d-axis and q-axis respectively under discrete state k+1, i d (k) and i q (k) represents the d-axis and q-axis response currents under discrete state k. and These are the state current observations on the d-axis and q-axis under discrete state k, respectively.

[0112] Step 4: Based on the current voltage control vector and the current response current vector, use the rotor flux estimation model to obtain the estimated value of the rotor flux at the current moment.

[0113] Steps 1 and 4 constitute the self-tuning identification of the rotor flux linkage. This invention develops a mathematical model to identify the magnitude of the superconducting motor rotor flux linkage based on the integration of voltage and current during controlled rotor angle transitions, achieving self-tuning identification of the superconducting motor flux linkage amplitude.

[0114] Step 5: If the rotor flux linkage estimate at the current moment changes abruptly from the rotor flux linkage estimate at the previous moment, then the superconducting motor is determined to have lost quench.

[0115] When the rotor flux linkage estimate at the current moment changes abruptly from the rotor flux linkage estimate at the previous moment, it can no longer meet the flux linkage requirements under superconductivity.

[0116] Step 6: Based on the current rotor flux estimate and the current response current vector, use the state current observation model to obtain the state current observation value of the superconducting motor under quench fault conditions.

[0117] Step 7: Based on the given current vector, the observed state current value of the superconducting motor under quench fault, and the response current vector at the current moment, determine the voltage control vector under the superconducting motor under quench fault using the fault-tolerant control model.

[0118] For example, the specific implementation process of step 7 is as follows:

[0119] Based on the given current vector, the observed state current value of the superconducting motor under quench fault, and the response current vector at the current moment, the voltage control quantity in the dq coordinate system is obtained using the fault-tolerant control model. The voltage control quantity in the dq coordinate system is then converted into the voltage control quantity in the αβ coordinate system, which serves as the voltage control vector under quench fault of the superconducting motor.

[0120] The method for determining the given current vector is as follows: based on the speed feedback value and speed setpoint output by the superconducting motor, the PI control method is used to obtain the current setpoint value of the q-axis when the superconducting motor experiences a quench fault; the current setpoint value of the d-axis when the superconducting motor experiences a quench fault is set to 0; wherein, the current setpoint value of the d-axis and the current setpoint value of the q-axis constitute the given current vector.

[0121] Step 8: Apply the voltage control vector to the superconducting motor under quench fault conditions, so that the response current vector under quench fault conditions is equal to the given current vector, thereby controlling the superconducting motor to operate stably.

[0122] One method to apply the voltage control vector to the superconducting motor under quench fault conditions is as follows:

[0123] A voltage control vector is synthesized under a quench fault in the superconducting motor to obtain a synthesized voltage; a response current in the static coordinate system corresponding to the synthesized voltage is generated; and the response current in the static coordinate system is applied to the superconducting motor.

[0124] This invention employs a fault-tolerant control algorithm based on online flux linkage detection. Addressing the fault situation caused by the superconductor returning to its normal state after a quench in a superconducting motor, the algorithm monitors rotor flux linkage changes in real time and calculates the observed state current value. This state current observation is then used as feedback input to the controller, enabling the response current to accurately track the given current, reducing the decrease in effective flux linkage, and thus achieving fault-tolerant control.

[0125] The effects of this invention are as follows:

[0126] (1) A mathematical model was developed to identify the size of the superconducting motor rotor flux based on the integration of voltage and current during controlled rotor angle transition.

[0127] (2) Monitor the superconductor flux in real time, calculate the state current observation value in real time, and input the state current observation value as feedback quantity into the controller.

[0128] (3) After the state current observation is input to the controller as feedback, the response currents of the d-axis and q-axis can accurately track the given current. Since the response currents of the d-axis and q-axis can accurately track the given current, the reduction of effective flux linkage is reduced, thus ensuring the stable operation of the superconducting motor.

[0129] Example 2

[0130] In order to implement the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, this embodiment of the invention provides a fault-tolerant control system for superconducting motors that considers quenching faults, including: a fault-tolerant controller, a magnetic flux detection module, and a state current observation module.

[0131] The flux detection module is connected to both the fault-tolerant controller and the state current observation module; the state current observation module is connected to the fault-tolerant controller.

[0132] The flux detection module is used to perform flux detection based on the response current vector and the voltage control vector output by the fault-tolerant controller at each moment, obtain the rotor flux estimate at each moment, and determine that the superconducting motor has lost quench fault when the rotor flux estimate at the current moment is different from the rotor flux estimate at the previous moment, and transmit the rotor flux estimate at the current moment to the state current observation module.

[0133] The state current observation module is used to obtain the state current observation value of the superconducting motor under quench fault based on the rotor flux estimate and the response current vector at the current moment and the state current observation model.

[0134] The fault-tolerant controller is used to determine the voltage control vector under the given current vector, the observed state current value of the superconducting motor under the quench fault, and the response current vector at the current moment using the fault-tolerant control model. The voltage control vector under the given current vector is then applied to the superconducting motor to make the response current vector under the given current vector equal to the given current vector, thereby controlling the superconducting motor to operate stably.

[0135] Furthermore, the system also includes: an SVPWM module, a converter, a coordinate transformation module, and a PI controller.

[0136] The SVPWM module is connected to both the fault-tolerant controller and the converter. The SVPWM module is used to synthesize the voltage control vector output by the fault-tolerant controller and transmit the synthesized voltage to the converter.

[0137] The converter is connected to the coordinate transformation module and the superconducting motor respectively. The converter is used to transmit the response current in the static coordinate system corresponding to the composite voltage to the coordinate transformation module and the superconducting motor.

[0138] The coordinate transformation module is connected to the magnetic flux detection module and the fault-tolerant controller respectively. The coordinate transformation module is used to convert the response current in the static coordinate system into the response current vector in the αβ coordinate system and the response current vector in the dq coordinate system, and transmit the response current vector in the αβ coordinate system to the magnetic flux detection module and the response current vector in the dq coordinate system to the fault-tolerant controller.

[0139] The PI controller is connected to the superconducting motor and the fault-tolerant controller respectively. The PI controller is used to obtain the given current vector when the superconducting motor fails due to a quench fault, based on the speed feedback value and speed setpoint of the superconducting motor, and transmit it to the fault-tolerant controller.

[0140] Fault-tolerant control system block diagram as follows Figure 4 As shown. First, the flux linkage fault detection section detects flux linkage changes, and the state current observation section calculates the observed state current value. Then, the current operating state of the motor and the observed state current value are fed back to the fault-tolerant control module equation (30) to calculate the voltage vector u(k+1) required for the response current to accurately track the given current. Finally, the SVPWM method is used to synthesize the output voltage vector to eliminate current deviation and stabilize the faulty motor.

[0141] The superconducting motor fault-tolerant control system considering quench failure provided in Embodiment 2 of the present invention has a similar working principle and beneficial effects to the superconducting motor fault-tolerant control system method considering quench failure described in Embodiment 1 above. Therefore, it will not be described in detail here. For specific details, please refer to the introduction of the above method embodiments.

[0142] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0143] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A fault-tolerant control method of a superconducting electric machine considering loss-of-field faults, characterized in that, The method comprises the steps of: establishing a rotor flux linkage estimation model; constructing a state current observation model of the superconducting motor under the quench fault; establishing a fault-tolerant control model of the superconducting motor under the quench fault; obtaining a rotor flux linkage estimation value at the current moment by using the rotor flux linkage estimation model according to a voltage control vector at the current moment and a response current vector at the current moment; determining that the superconducting motor has occurred the quench fault if the rotor flux linkage estimation value at the current moment and a rotor flux linkage estimation value at a previous moment have a step change; obtaining a state current observation value of the superconducting motor under the quench fault by using the state current observation model according to the rotor flux linkage estimation value at the current moment and the response current vector at the current moment; determining a voltage control vector of the superconducting motor under the quench fault by using the fault-tolerant control model according to a given current vector, the state current observation value of the superconducting motor under the quench fault and the response current vector at the current moment; applying the voltage control vector of the superconducting motor under the quench fault to the superconducting motor, so that the response current vector of the superconducting motor under the quench fault is equal to the given current vector, and the superconducting motor is controlled to stably operate.

2. The superconducting machine fault-tolerant control method considering loss of field fault according to claim 1, characterized in that, The rotor flux linkage estimation model is: wherein and are the estimated values of the rotor flux on the d-axis and q-axis, respectively, is the rotor position in open loop, and are the estimated values of the rotor flux on the a-axis and β-axis, respectively; is the rotor flux vector at time t1, Λ is the amplitude of the superconducting flux, is the rotor position in open loop at time t1; is the estimated value of the superconducting flux amplitude, u αβ is the voltage control vector, i αβ is the response current vector, is the estimated value of the stator resistance of the superconducting machine, L is the reactance, i αβ (t1) is the total flux at time t1, λ αβ (t0) is the total flux at time t0, t0 is the time when the rotor starts to rotate, t1 is the time when the rotor rotation angle is stable, Δθ is the rotor rotation angle.

3. The superconducting machine fault-tolerant control method considering loss of field fault according to claim 1, characterized in that, The state current observation model of the superconducting motor under the quench fault comprises the steps of: converting the response current vector from an αβ coordinate system to a dq coordinate system; constructing the state current observation model of the superconducting motor under the quench fault according to the response current vector in the dq coordinate system and the rotor flux linkage estimation value, and the state current observation model is: where, and are the state current observations on d-axis and q-axis in discrete state k, R is the stator resistance, L d and L q are the reactance on d-axis and q-axis, T s is a control period; i d (k) and i q (k) are the response currents on d-axis and q-axis in discrete state k, i d (k) and i q (k) constitute the response current vector in dq coordinate system; ω(k) is the electrical angular velocity in discrete state k, and are the rotor flux estimations on d-axis and q-axis.

4. The superconducting machine fault-tolerant control method considering loss of field fault of claim 1, wherein, The fault-tolerant control model is: wherein u d (k+1) and u q (k+1) are the voltage control variables of the d-axis and q-axis in the discrete state k+1, respectively, and F is an intermediate variable, T s is a control period, L d and L q are the reactances of the d-axis and q-axis, respectively; and are the given currents on the d-axis and q-axis in the discrete state k+1, respectively, i d (k) and i q (k) are the response currents of the d-axis and q-axis in the discrete state k, respectively, and are the state current observation values on the d-axis and q-axis in the discrete state k, respectively.

5. The superconducting machine fault-tolerant control method considering loss of field fault of claim 1, wherein, The determination method of the given current vector comprises the steps of: obtaining a current given value of a q-axis of the superconducting motor under the quench fault by using a PI control method according to a speed feedback value and a speed given value of the superconducting motor; setting the current given value of a d-axis of the superconducting motor under the quench fault to 0; wherein the current given value of the d-axis and the current given value of the q-axis constitute the given current vector.

6. The superconducting machine fault-tolerant control method considering loss of field fault of claim 1, wherein, The determination of the voltage control vector of the superconducting motor under the quench fault by using the fault-tolerant control model according to the given current vector, the state current observation value of the superconducting motor under the quench fault and the response current vector at the current moment comprises the steps of: obtaining a voltage control amount in the dq coordinate system by using the fault-tolerant control model according to the given current vector, the state current observation value of the superconducting motor under the quench fault and the response current vector at the current moment; converting the voltage control amount in the dq coordinate system into a voltage control amount in an αβ coordinate system, and taking the voltage control amount in the αβ coordinate system as the voltage control vector of the superconducting motor under the quench fault.

7. The superconducting machine fault-tolerant control method considering loss of field fault of claim 1, wherein, The application of the voltage control vector of the superconducting motor under the quench fault to the superconducting motor comprises the steps of: synthesizing the voltage control vector of the superconducting motor under the quench fault to obtain a synthesized voltage; generating a response current in a static coordinate system corresponding to the synthesized voltage; applying the response current in the static coordinate system to the superconducting motor.

8. A superconducting machine fault-tolerant control system considering quench faults, characterized in that, The system applies the fault-tolerant control method of the superconducting motor considering the quench fault in any one of claims 1-7, and the system comprises a fault-tolerant controller, a magnetic flux detection module and a state current observation module. The flux detection module is connected with the fault-tolerant controller and the state current observation module respectively; the state current observation module is connected with the fault-tolerant controller; The flux detection module is used for detecting the flux according to the response current vector at each moment and the voltage control vector output by the fault-tolerant controller, obtaining the rotor flux estimation value at each moment, and determining that the superconducting motor has a quench fault when the rotor flux estimation value at the current moment is different from the rotor flux estimation value at the previous moment, and transmitting the rotor flux estimation value at the current moment to the state current observation module; The state current observation module is used for obtaining the state current observation value of the superconducting motor under the quench fault by using the state current observation model according to the rotor flux estimation value at the current moment and the response current vector at the current moment; The fault-tolerant controller is used for determining the voltage control vector of the superconducting motor under the quench fault by using the fault-tolerant control model according to the given current vector, the state current observation value of the superconducting motor under the quench fault and the response current vector at the current moment, and applying the voltage control vector of the superconducting motor under the quench fault to the superconducting motor, so that the response current vector of the superconducting motor under the quench fault is equal to the given current vector, and the superconducting motor is controlled to stably operate.

9. The superconducting machine fault-tolerant control system considering loss of field faults of claim 8, wherein, The system further comprises an SVPWM module, a converter, a coordinate transformation module and a PI controller; The SVPWM module is connected with the fault-tolerant controller and the converter respectively, and the SVPWM module is used for synthesizing the voltage control vector output by the fault-tolerant controller and transmitting the synthesized voltage to the converter; The converter is connected with the coordinate transformation module and the superconducting motor respectively, and the converter is used for transmitting the response current in the static coordinate system corresponding to the synthesized voltage to the coordinate transformation module and the superconducting motor; The coordinate transformation module is connected with the flux detection module and the fault-tolerant controller respectively, and the coordinate transformation module is used for converting the response current in the static coordinate system into the response current vector in the αβ coordinate system and the response current vector in the dq coordinate system, and transmitting the response current vector in the αβ coordinate system to the flux detection module and the response current vector in the dq coordinate system to the fault-tolerant controller; The PI controller is connected with the superconducting motor and the fault-tolerant controller respectively; the PI controller is used for obtaining the given current vector of the superconducting motor under the quench fault according to the speed feedback value and the speed given value of the superconducting motor, and transmitting the given current vector to the fault-tolerant controller.

Images