Multi-switch tube open-circuit fault tolerance method and system for dual three-phase permanent magnet motor system

Abstract

The invention discloses a multi-switch tube open-circuit fault-tolerant method and system for a dual three-phase permanent magnet motor system, and the method comprises the steps: calculating a current compensation value of a healthy phase through employing a Lagrange multiplier method according to the open-circuit fault conditions of different switch tubes on the premise that the magnetomotive force of a motor before and after a fault is not changed, and employing the minimum copper loss as a constraint condition; adding a corresponding phase current compensation value to each healthy phase so as to obtain a corresponding fault-tolerant reference current; coordinates of the sampled phase current and the fault-tolerant reference current under the fault condition are converted to a rotating coordinate system, and the reference voltage of each plane is solved through PI closed-loop control; and pulse waveforms generated by each plane reference voltage under a natural coordinate system act on the switch tube by using a carrier pulse width modulation strategy, so that fault-tolerant control of the open-circuit fault of the switch tube of the dual three-phase permanent magnet motor driving system is realized. According to the invention, fault-tolerant control under various switch tube open-circuit fault conditions is realized, and the reliability of the motor driving system under fault operation is improved.

Description

Technical Field

[0001] The present invention belongs to the field of multi-phase motor fault-tolerant control applications, and in particular relates to a multi-switch open-circuit fault-tolerant method and system for a dual three-phase permanent magnet motor system. Background Art

[0002] Dual three-phase permanent magnet synchronous motors (PMSMs) have attracted widespread attention in numerous applications due to their high efficiency, high torque density, and excellent dynamic performance. However, in actual operation, DPMSM drive systems can experience various types of faults, such as single-switch open-circuit failures. These faults can degrade system performance or even cause the entire drive system to fail. To improve the reliability and stability of DPMSMs, research on fault-tolerant control strategies is crucial.

[0003] Fault-tolerant control methods for dual three-phase permanent magnet synchronous motors have achieved some success. Existing research primarily focuses on fault scenarios where a single phase or two phases are open, but struggles to address complex faults such as single or multiple open switches at different locations that do not cause a complete phase failure. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a multi-switch open-circuit fault-tolerant method and system for a dual three-phase permanent magnet motor system. For the open-circuit fault of a single switch tube or two switch tubes in different positions in the drive system, by changing the system reference current at the time of the fault, PI current control is used to ensure that the system still has stable torque output capability when such complex faults occur, thereby significantly improving the reliability and fault tolerance of the system.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A multi-switch open-circuit fault-tolerant method for a dual three-phase permanent magnet motor system:

[0007] Based on the different open-circuit fault conditions of the drive system's switch tubes, the Lagrange multiplier method is used to calculate the phase current compensation value of the healthy phase, with the total stator rotating magnetomotive force remaining unchanged before and after the motor fault as the premise and the minimum copper loss as the constraint. The speed loop adopts PI closed-loop control to obtain the reference value of the q-axis current, which replaces the current amplitude. When different switch tube open-circuit faults occur, the corresponding phase current compensation value is added to each healthy phase to obtain the fault-tolerant reference current for different switch tube open-circuit faults.

[0008] The sampled six-phase currents of the motor and the fault-tolerant reference currents of different switch tube open-circuit faults are transformed into a rotating coordinate system, and the reference voltages of each plane are calculated through PI closed-loop control. The reference voltages of each plane are then transformed into a natural coordinate system through an inverse transformation.

[0009] The carrier pulse width modulation strategy is used to apply the pulse waveform generated by the reference voltage in the natural coordinate system to the switch tube to achieve fault-tolerant control of the open-circuit fault of the switch tube in the dual three-phase permanent magnet motor drive system.

[0010] Further technical solution, after each healthy phase adds the corresponding phase current compensation value, the phase current i nf The general expression is:

[0011] i nf =I m [sin(θ e -θ p )+C p ]

[0012] Among them, I m is the current amplitude, θ e is the rotor position angle, θ p is the corresponding healthy winding space angle, C p is the compensation amount corresponding to the healthy phase current.

[0013] According to a further technical solution, the open circuit failure conditions of different switch tubes in the driving system include: open circuit failure of a single switch tube, open circuit failure of two switch tubes on the same side, open circuit failure of two switch tubes on different sides, and open circuit failure of two switch tubes in the same bridge arm.

[0014] A further technical solution also requires that the sum of the phase currents of the single-neutral-point dual-three-phase permanent magnet synchronous motor is 0. Taking the open-circuit fault of the switch tube on phase A of the motor as an example, based on the fact that the total stator rotating magnetomotive force before and after the fault is equal and the sum of the phase currents of the single-neutral-point dual-three-phase permanent magnet synchronous motor is 0, the following can be simplified:

[0015]

[0016] Among them, C B is the compensation value corresponding to the B phase current, C C is the compensation value corresponding to the C phase current, C D is the compensation value corresponding to the D phase current, C E is the compensation value corresponding to the E phase current, C F is the compensation value corresponding to the F phase current, θ e is the rotor position angle, I dc is the DC component, △i A is the AC component of phase A current.

[0017] A further technical solution uses the simplified optimization condition of minimizing stator copper loss as the objective function, with the constraints that the total stator rotating magnetomotive force before and after the fault is equal and the sum of the phase currents of the single neutral point dual three-phase permanent magnet synchronous motor is 0. Taking the open circuit fault of the switch tube on phase A of the motor as an example, the Lagrangian function is expressed as:

[0018]

[0019] Among them, λ1, λ2, λ3 are Lagrangian operators, i Af 、i Bf 、i Cf 、i Df 、i Ef 、i Ff is the current of each phase during open circuit fault.

[0020] A further technical solution is that when a single switch tube fails, taking the open circuit failure of the switch tube on phase A of the motor as an example, the Lagrange multiplier method is used to calculate the phase current compensation value of the healthy phase as follows:

[0021]

[0022] Among them, C B is the compensation value corresponding to the B phase current, C C is the compensation value corresponding to the C phase current, C D is the compensation value corresponding to the D phase current, C E is the compensation value corresponding to the E phase current, C F is the compensation value corresponding to the F phase current, θ e is the rotor position angle, I dc is the DC component, △i A is the AC component of phase A current.

[0023] A further technical solution is to use the Lagrange multiplier method to calculate the phase current compensation value of the healthy phase when two switch tubes on the same side have open circuit faults, taking the open circuit faults of the switch tubes on phases A and C of the motor as an example:

[0024]

[0025] Among them, △i C is the AC component of phase C current.

[0026] A further technical solution is to use the Lagrange multiplier method to calculate the phase current compensation value of the healthy phase when two switch tubes on different sides fail to open circuit, taking the upper switch tube of phase A and the lower switch tube of phase B of the motor as an example.

[0027]

[0028] Among them, △i B is the AC component of phase B current.

[0029] A further technical solution is to use the Lagrange multiplier method to calculate the phase current compensation value of the healthy phase when two switches in the same bridge arm fail to open circuit, taking the upper and lower switches of motor phase A as an example.

[0030]

[0031] A dual three-phase permanent magnet motor system multi-switch open circuit fault-tolerant system, comprising:

[0032] Signal acquisition module, real-time acquisition of phase current, rotor position and angular velocity of dual three-phase permanent magnet synchronous motor;

[0033] The fault-tolerant reference current calculation module calculates the phase current compensation value of the healthy phase using the Lagrange multiplier method when different switching tubes in the dual three-phase permanent magnet synchronous motor drive system fail to open circuit. The calculation assumes that the total stator rotating magnetomotive force remains unchanged before and after the motor failure and that the minimum copper loss is a constraint. The fault phase current is obtained using Fourier expansion, and the corresponding compensation value is added to the healthy phase. The final combination generates the six-phase fault-tolerant reference current.

[0034] The coordinate transformation module transforms the six-phase current of the motor and the fault-tolerant reference current into the rotating coordinate system, and transforms the reference voltage of each plane into the natural coordinate system;

[0035] PI dual closed-loop control module, used to calculate the reference value of the q-axis current and the reference voltage of each plane;

[0036] The PWM pulse output module generates a pulse waveform from the fault-tolerant reference voltage in the natural coordinate system through the carrier pulse width modulation strategy and acts on the switch tube.

[0037] Beneficial effects of the present invention:

[0038] 1) Improving the reliability of the dual three-phase permanent magnet synchronous motor drive: The present invention can generate corresponding fault-tolerant reference currents based on the principle of constant magnetomotive force for different open-circuit fault conditions of the switch tubes in the drive system, and achieve fault tolerance through PI control, thereby ensuring the stable operation of the system under various faults.

[0039] 2) Reduce copper loss and torque ripple: Under the premise of unchanged magnetomotive force, the Lagrange multiplier method is applied to calculate the compensation amount of healthy phase current under the condition of minimum copper loss. This not only effectively reduces torque ripple, but also significantly reduces the system copper loss under fault conditions, thereby improving operating efficiency.

[0040] 3) Reduced maintenance costs: This fault-tolerant control method can achieve fault tolerance by switching the corresponding reference current when different switch tubes fail to open the circuit, without replacing system components, thereby avoiding sudden system shutdowns, reducing equipment damage and production losses, and significantly reducing operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1( a ) is a block diagram of a multi-switch open-circuit fault-tolerant method for a dual three-phase permanent magnet motor system according to the present invention;

[0042] FIG1( b ) is a structural diagram of a multi-switch open-circuit fault-tolerant system of a dual three-phase permanent magnet motor system according to the present invention;

[0043] Figure 2 Schematic diagram of a single switch tube open circuit fault in the dual three-phase permanent magnet synchronous motor drive system of the present invention (taking the open circuit fault of the switch tube on phase A as an example);

[0044] Figure 3 Schematic diagram of the open circuit fault of two switches on the same side of the dual three-phase permanent magnet synchronous motor drive system of the present invention (taking the open circuit fault of the switches on phases A and C as an example);

[0045] Figure 4 Schematic diagram of open circuit faults of two switching tubes on different sides of the dual three-phase permanent magnet synchronous motor drive system of the present invention (taking the open circuit faults of the upper switching tube of phase A and the lower switching tube of phase B as an example);

[0046] Figure 5 Schematic diagram of an open-circuit fault of two switches in the same bridge arm of the dual three-phase permanent magnet synchronous motor drive system of the present invention (taking the open-circuit fault of the upper and lower switches of phase A as an example);

[0047] Figure 6 This is a graph showing the output torque results of the method proposed in the present invention when a single switch tube fails (taking the open circuit failure of the switch tube on phase A as an example);

[0048] Figure 7 This is a graph showing the output torque results of the method proposed in the present invention when two switch tubes on the same side have open circuit faults (taking the open circuit faults of the switch tubes on phases A and C as an example);

[0049] Figure 8 This is a graph showing the output torque results of the method proposed in the present invention when two switch tubes on different sides have open circuit faults (taking the upper switch tube of phase A and the lower switch tube of phase B as an example);

[0050] Figure 9 This is a graph showing the output torque results of the method proposed in the present invention for an open-circuit fault of two switching tubes in the same bridge arm (taking the open-circuit fault of the upper and lower switching tubes of phase A as an example). DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be 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.

[0052] As shown in Figure 1(b), the structural diagram of a multi-switch open-circuit fault-tolerant system of a dual three-phase permanent magnet motor system of the present invention includes a drive system switch open-circuit fault-tolerant instruction input unit, a signal acquisition module, a coordinate transformation module, a PI dual closed-loop control module, a fault-tolerant reference current calculation module and a PWM pulse output module.

[0053] Among them, the drive system switch tube open circuit fault tolerance command input unit is responsible for receiving external commands, such as start, stop, speed commands, etc.

[0054] Signal acquisition module: responsible for real-time acquisition of phase current, rotor position information and angular velocity information of the dual three-phase permanent magnet synchronous motor, and sending the collected data to the coordinate transformation module;

[0055] Fault-tolerant reference current calculation module: This module is responsible for calculating the corresponding fault-tolerant reference current when different switch tubes in the dual three-phase permanent magnet synchronous motor drive system have open-circuit faults, based on different fault conditions, and sends the calculated data to the coordinate transformation module;

[0056] Coordinate transformation module: Receives the phase current and rotor position information collected by the signal acquisition module, obtains the actual current in the rotating coordinate system through coordinate transformation, and sends the actual current after coordinate transformation to the PI dual closed-loop control module; Receives the fault-tolerant reference current calculation module to calculate the fault-tolerant reference current under the corresponding fault condition, obtains the fault-tolerant reference current in the rotating coordinate system through coordinate transformation, and sends the fault-tolerant reference current after coordinate transformation to the PI dual closed-loop control module; Receives the fault-tolerant reference voltage under the corresponding fault condition under the rotating coordinate system by the PI dual closed-loop control module, obtains the fault-tolerant reference voltage in the natural coordinate system through coordinate transformation, and sends the fault-tolerant reference voltage after coordinate transformation to the PWM pulse output module;

[0057] PI dual closed-loop control module: Based on the actual current in the rotating coordinate system and the fault-tolerant reference current under the corresponding fault conditions sent by the coordinate transformation module, the reference voltages of each plane in the rotating coordinate system are obtained through PI control, and then the reference voltages of each plane in the rotating coordinate system are sent to the coordinate transformation module;

[0058] PWM pulse output module: Receives the fault-tolerant reference voltage in the natural coordinate system transmitted by the coordinate transformation module, and applies the pulse waveform generated by the compensated voltage vector to the switch tube through the carrier pulse width modulation strategy, thereby realizing open-circuit fault-tolerant control of multiple switch tubes in the dual three-phase permanent magnet motor system.

[0059] As shown in FIG1( a ), the present invention provides a method for multi-switch open-circuit fault tolerance in a dual three-phase permanent magnet motor system. The specific implementation steps include:

[0060] Step 1) According to the open circuit fault conditions of different switch tubes in the drive system, the phase current of the fault phase is expanded using Fourier series to obtain the phase current expression of the fault phase.

[0061] The open circuit faults of the switch tubes in the dual three-phase permanent magnet synchronous motor drive system can be mainly divided into three types: ① the upper switch tube of the inverter bridge arm is open; ② the lower switch tube of the inverter bridge arm is open; ③ both the upper and lower switch tubes of the inverter bridge arm are open.

[0062] ① The switch tube on the inverter bridge arm is open, and the phase current i nf1 The waveform can be expanded using the Fourier series to obtain a specific expression:

[0063] i nf1 =I m [0.5sin(θ e -θ n )-I dc +Δi n ]

[0064] in:

[0065]

[0066] Where, I m is the current amplitude; θ e is the rotor position angle; θ n is the winding space angle corresponding to the fault; I dc is the DC component, and I dc =1 / π;△i n An intermediate amount.

[0067] ② The switch tube under the inverter bridge arm is open, and the fault phase current i nf2 The waveform can be expanded using the Fourier series to obtain a specific expression:

[0068] i nf2 =I m [0.5sin(θ e -θ n )+I dc -Δi n ]

[0069] ③ The upper and lower switches of the inverter bridge arm are both open, and the fault phase current i nf3 Specific expression:

[0070] i nf3 =0

[0071] Step 2) Determine the general expression after adding the compensation amount to the healthy phase.

[0072] Step 2.1) Adding appropriate compensation to the healthy phase can ensure the torque output capacity of the motor. The phase current i after adding compensation to the healthy phase nf The general expression is:

[0073] i nf =I m [sin(θ e -θ p )+C p ]

[0074] Among them, θ p is the healthy corresponding winding space angle; C p is the compensation amount corresponding to the healthy phase current.

[0075] Step 2.2) The following is an analysis of the open circuit fault of the drive system switch tube: ① If Figure 2 As shown, a single switch tube open circuit fault (a total of 12 cases, this embodiment takes the A phase switch tube open circuit fault as an example); ② As Figure 3 As shown, the two switch tubes on the same side have open circuit faults (a total of 30 cases, this embodiment takes the open circuit faults of the switch tubes on phases A and C as an example); ③ As Figure 4 As shown, two switch tubes on different sides have open circuit faults (a total of 30 cases, this embodiment takes the upper switch tube of phase A and the lower open circuit fault of phase B as an example); ④ As Figure 5 As shown, two switch tubes in the same bridge arm have open circuit faults (a total of 6 cases, this embodiment takes the open circuit faults of the upper and lower switch tubes of phase A as an example).

[0076] ① In the case of a single open-circuit fault (taking the open-circuit fault of the switch on phase A as an example), the phase current of the faulty phase A and the phase currents of the healthy phases B, C, D, E, and F can be expressed as:

[0077]

[0078] Where, △i A is the AC component of phase A current, C B is the compensation value corresponding to the B phase current, C C is the compensation value corresponding to the C phase current, C D is the compensation value corresponding to the D phase current, C E is the compensation value corresponding to the E phase current, C F is the compensation value corresponding to the F phase current.

[0079] ② In the case of open-circuit faults of two switches on the same side (taking the open-circuit faults of switches on phases A and C as an example), the phase currents of the faulty phases A and C and the phase currents of the healthy phases B, D, E, and F can be expressed as:

[0080]

[0081] Where, △i c is the AC component of phase C current.

[0082] ③ In the case of open-circuit faults of two switches on different sides (taking the upper switch of phase A and the lower switch of phase B as an example), the phase currents of the faulty phases A and B and the phase currents of the healthy phases C, D, E, and F can be expressed as:

[0083]

[0084] Where, △iB is the AC component of phase B current.

[0085] ④ In the case of an open-circuit fault between two switches in the same bridge arm (taking the open-circuit fault of the upper and lower switches of phase A as an example), the phase current of the faulty phase A and the phase currents of the healthy phases B, C, D, E, and F can be expressed as:

[0086]

[0087] Step 3) The basic constraints are that the magnetomotive force of the dual three-phase permanent magnet motor remains unchanged and the sum of the six-phase currents is zero.

[0088] Under normal circumstances, the current of each phase can be expressed as:

[0089]

[0090] The total stator rotating magnetomotive force can be expressed as:

[0091] M=N s (μ A i A +μ B i B +μ C i C +μ D i D +μ E i E +μ F i F )

[0092] The rotation factors of each phase are:

[0093]

[0094] Where N s is the number of winding turns.

[0095] When a switch open-circuit fault occurs in a dual three-phase permanent magnet synchronous motor drive system, the total stator rotating magnetomotive force can be expressed as:

[0096] M f =N s (μ A i Af +μ B i Bf +μ C i Cf +μ D i Df +μ E i Ef +μ F i Ff )

[0097] In order to suppress torque ripple and ensure torque output capacity, the total stator rotating magnetomotive force before and after the fault is equal; furthermore, considering that the sum of the phase currents of the single neutral point dual three-phase permanent magnet synchronous motor is 0. Combining the above two basic constraints, it can be expressed as:

[0098]

[0099] Step 4) Introducing the minimum copper loss, calculate the phase current compensation of the healthy phase under different switch tube open circuit faults.

[0100] The Lagrange multiplier method is used to calculate the phase current compensation of the healthy phase with the minimum copper consumption time under different switch tube open circuit faults in the drive system.

[0101] ① For a single open-circuit fault (taking the open-circuit fault of the switch on phase A as an example), based on the fact that the total stator rotating magnetomotive force before and after the fault is equal and the sum of the phase currents of the single-neutral-point dual-three-phase permanent magnet synchronous motor is zero, the following two basic constraints are simplified:

[0102]

[0103] The copper loss calculation formula for the dual three-phase permanent magnet synchronous motor under fault is:

[0104]

[0105] Among them, R s Stator resistance.

[0106] Since the stator resistance remains unchanged, the optimization condition for minimizing stator copper loss can be simplified to:

[0107]

[0108] Taking the simplified optimization condition of minimizing stator copper loss as the objective function, and the constraints that the total stator rotating magnetomotive force before and after the fault is equal and the sum of the phase currents of the single neutral point dual three-phase permanent magnet synchronous motor is 0, the Lagrangian function can be expressed as:

[0109]

[0110] Among them, λ1, λ2, and λ3 are Lagrangian operators.

[0111] In order to minimize copper loss, the C B 、C C 、C D 、C E 、C F , λ1, λ2, λ3 and calculate the partial derivatives, and make them equal to 0, the optimal healthy phase compensation for the minimum copper consumption can be calculated:

[0112]

[0113] ② For two non-adjacent switch open-circuit faults (taking the open-circuit faults of phases A and C as an example), the same method as the open-circuit fault of phase A can be used to calculate the optimal healthy phase compensation with the minimum copper consumption time using the Lagrange multiplier method:

[0114]

[0115] ③ For two open-circuit faults on different sides (taking the upper switch of phase A and the lower switch of phase B as an example), the same method as the open-circuit fault of the upper switch of phase A can be used to calculate the optimal healthy phase compensation with the minimum copper consumption time using the Lagrange multiplier method:

[0116]

[0117] ④ In the case of an open-circuit fault between two switches in the same bridge arm (taking the open-circuit fault of the upper and lower switches of phase A as an example), the same method as the open-circuit fault of the upper switch of phase A can be used to calculate the optimal healthy phase compensation amount with the minimum copper consumption time using the Lagrange multiplier method:

[0118]

[0119] Step 5) The speed loop adopts PI control to obtain the q-axis current reference value. After adding the compensation value to each healthy phase, the reference current when the corresponding switch tube has an open circuit fault is obtained.

[0120] Step 5.1) Calculate the speed error between the given speed n* and the actual speed n of the motor in real time, and obtain the reference value of the required q-axis current through the speed loop PI regulator

[0121] Step 5.2) Replace the current amplitude with the reference value of the q-axis current to obtain the reference current corresponding to different switch tube open circuit faults.

[0122] ① When a single switch tube fails open circuit (taking the open circuit fault of the switch tube on phase A as an example), the reference current of the faulty phase A and the healthy phases B, C, D, E, and F can be expressed as:

[0123]

[0124] ② In the case of open-circuit faults between two non-adjacent switches (taking the open-circuit faults of switches on phases A and C as an example), the reference currents of the faulty phases A and C and the healthy phases B, D, E, and F can be expressed as:

[0125]

[0126] ③ In the case of open-circuit faults of two switches on different sides (taking the upper switch of phase A and the lower switch of phase B as an example), the reference currents of the faulty phases A and B and the healthy phases C, D, E, and F can be expressed as:

[0127]

[0128] ④ In the case of an open-circuit fault between two switches in the same bridge arm (taking the open-circuit fault of the upper and lower switches of phase A as an example), the current of the faulty phase A and the reference currents of the healthy phases B, C, D, E, and F can be expressed as:

[0129]

[0130] Step 6) Using the decoupling matrix, the calculated phase current reference value expressions of the healthy phase and the faulty phase are transformed into a synchronous rotating coordinate system.

[0131] Step 6.1) Step 5.2) Obtain the reference current i for fault-tolerant control after the open circuit failure of different switch tubes in the drive system Af 、i Bf 、i Cf 、i Df 、i Ef 、i Ff Then, the space vector decoupling matrix is ​​used to transform the variables of the natural coordinate system into the stationary coordinate system. The transformation process is:

[0132]

[0133] in, They are the currents of α axis, β axis, x axis, y axis, o1 axis and o2 axis respectively, and the space vector decoupling matrix T 6s As shown below:

[0134]

[0135] Step 6.2) For a dual three-phase permanent magnet synchronous motor, only the fundamental component of the αβ subspace participates in the electromechanical energy conversion. To simplify the analysis, the variables in the stationary coordinate system are transformed into the synchronous rotating coordinate system. The transformation process is as follows:

[0136]

[0137] Among them, the dual three-phase motor synchronous rotation transformation matrix T αβ-dq for:

[0138]

[0139] in, are the d-axis and q-axis currents.

[0140] Step 7) The current loop adopts PI control to obtain the reference voltage of each plane in the stationary coordinate system.

[0141] The PI current control of the present invention is achieved by Subtract i d 、i q 、i x 、i y 、i o1 、i o2 After that, the PI control is used to obtain in are the voltage reference values ​​of the d-axis, q-axis, x-axis, y-axis, o1-axis, and o2-axis, respectively. d 、i q 、i x 、i y 、i o1 、i o2 The six-phase current of the dual three-phase permanent magnet motor is decoupled by the space vector matrix T 6s and the synchronous rotation transformation matrix T αβ-dq The d-axis, q-axis, x-axis, y-axis, o1-axis, and o2-axis currents obtained after transformation.

[0142] Step 8) Using the inverse transformation of the decoupling matrix, the obtained reference voltage is transformed into the natural coordinate system.

[0143] The reference voltage obtained in step 8.1) By the rotation transformation matrix T αβ-dq The inverse transformation can obtain the reference voltage of each plane in the stationary coordinate system. The specific transformation is as follows:

[0144]

[0145] Step 8.2) Decouple the matrix T through the space vector 6s By inverse transformation, we can get the reference phase voltages of phases A, B, C, D, E, and F in the natural coordinate system. The specific transformation is as follows:

[0146]

[0147] in, They are the phase voltage given values ​​of the dual three-phase permanent magnet synchronous motors.

[0148] Step 9) The reference voltage vector in the natural coordinate system is modulated by carrier pulse width modulation to obtain a switching signal and act on the power switching device to achieve closed-loop control of the dual three-phase permanent magnet synchronous motor.

[0149] Set the phase voltage of the dual three-phase permanent magnet synchronous motor to the given value Through carrier pulse width modulation (CBPWM), the switching signal is obtained and acts on the power switching device to achieve closed-loop control of the motor.

[0150] Figure 6 The torque waveform of the dual three-phase permanent magnet synchronous motor is given when a single switch tube open circuit fault occurs (taking the open circuit fault of the switch tube on phase A as an example). After the system reaches a steady state after using the method proposed in the present invention, the system is operated. Figure 7 The torque waveform of a dual three-phase permanent magnet synchronous motor is given when two switch tubes on the same side have open-circuit faults (taking the open-circuit faults of the switch tubes on phases A and C as an example). After the system reaches a steady state after operating using the method proposed in the present invention, the system is put into a steady-state state. Figure 8 The torque waveform of a dual three-phase permanent magnet synchronous motor is given when two switch tubes on different sides have open circuit faults (taking the upper switch tube of phase A and the lower open circuit fault of phase B as an example). After the system reaches a steady state after operating using the method proposed in the present invention, the system is put into a steady state. Figure 9 The torque waveforms of a dual three-phase permanent magnet synchronous motor, after the system reaches steady state using the proposed method, are presented when two switches in the same arm fail (using the upper and lower switches of phase A as an example). These results demonstrate that the proposed fault-tolerant control method can achieve stable motor operation.

[0151] The above embodiments are intended only to illustrate the design concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the present invention and implement it accordingly, thereby obtaining a fault-tolerant control method for a dual three-phase permanent magnet synchronous motor drive system in the event of a switch failure. Therefore, any equivalent changes or modifications based on the principles and design concepts disclosed herein are intended to be within the scope of protection of the present invention.

Claims

1. A method for open-circuit fault tolerance of multiple switching tubes in a dual three-phase permanent magnet motor system, characterized by: Based on the open-circuit fault conditions of different switching tubes in the drive system, the phase current compensation value of the healthy phase is calculated using the Lagrange multiplier method, with the total stator rotating magnetomotive force unchanged before and after the motor fault as the premise and the minimum copper loss as the constraint condition; The speed loop uses PI closed-loop control to obtain the reference value of the q-axis current, which replaces the current amplitude. When different switch tubes have open-circuit faults, the corresponding phase current compensation value is added to each healthy phase to obtain the fault-tolerant reference current for different switch tube open-circuit faults. The sampled six-phase currents of the motor and the fault-tolerant reference currents of different switch tube open-circuit faults are transformed into a rotating coordinate system, and the reference voltages of each plane are calculated through PI closed-loop control. The reference voltages of each plane are then transformed into a natural coordinate system through an inverse transformation. The carrier pulse width modulation strategy is used to apply the pulse waveform generated by the reference voltage in the natural coordinate system to the switch tube to achieve fault-tolerant control of the open-circuit fault of the switch tube in the dual three-phase permanent magnet motor drive system.

2. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 1, characterized in that: After each healthy phase is added with the corresponding phase current compensation value, the phase current i nf The general expression is: I nf =I m [sin(θ e -θ p )+C p ] Among them, I m is the current amplitude, θ e is the rotor position angle, θ p is the healthy corresponding winding space angle, C p is the compensation amount corresponding to the healthy phase current.

3. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 1, characterized in that: The open circuit fault conditions of different switch tubes in the drive system include: single switch tube open circuit fault, open circuit fault of two switch tubes on the same side, open circuit fault of two switch tubes on different sides, and open circuit fault of two switch tubes in the same bridge arm.

4. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 1, characterized in that: The prerequisite also includes that the sum of the phase currents of the single-neutral-point dual-three-phase permanent magnet synchronous motor is zero. Taking the open-circuit fault of the switch tube on phase A of the motor as an example, based on the equality of the total stator rotating magnetomotive force before and after the fault and the sum of the phase currents of the single-neutral-point dual-three-phase permanent magnet synchronous motor is zero, the following can be simplified: Among them, C B is the compensation value corresponding to the B phase current, C C is the compensation value corresponding to the C phase current, C D is the compensation value corresponding to the D phase current, C E is the compensation value corresponding to the E phase current, C F is the compensation value corresponding to the F phase current, θ e is the rotor position angle, I dc is the DC component, △i A is the AC component of phase A current.

5. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 4, characterized in that: The simplified optimization condition of minimizing stator copper loss is used as the objective function. The constraints are that the total stator rotating magnetomotive force before and after the fault is equal and the sum of the phase currents of the single-neutral-point dual-three-phase permanent magnet synchronous motor is zero. Taking the open-circuit fault of the switch tube on phase A of the motor as an example, the Lagrangian function is expressed as: Among them, λ1, λ2, λ3 are Lagrangian operators, i Af 、i Bf 、i Cf 、i Df 、i Ef 、i Ff is the current of each phase during open circuit fault.

6. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 3, characterized in that: When a single switch tube fails, taking the open circuit fault of the switch tube on phase A of the motor as an example, the phase current compensation value of the healthy phase is calculated using the Lagrange multiplier method as follows: Among them, C B is the compensation value corresponding to the B phase current, C C is the compensation value corresponding to the C phase current, C D is the compensation value corresponding to the D phase current, C E is the compensation value corresponding to the E phase current, C F is the compensation value corresponding to the F phase current, θ e is the rotor position angle, I dc is the DC component, △i A is the AC component of phase A current.

7. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 6, characterized in that: When two switches on the same side have open circuit faults, taking the open circuit faults of the switches on phases A and C of the motor as an example, the phase current compensation value of the healthy phase is calculated using the Lagrange multiplier method as follows: Among them, △i c is the AC component of phase C current.

8. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 6, characterized in that: When two switch tubes on different sides fail to operate, taking the upper switch tube of phase A and the lower switch tube of phase B of the motor as an example, the phase current compensation value of the healthy phase is calculated using the Lagrange multiplier method as follows: Among them, △i B is the AC component of phase B current.

9. The method for multi-switch open-circuit fault tolerance of a dual three-phase permanent magnet motor system according to claim 6, characterized in that: When two switches in the same bridge arm fail to open circuit, taking the upper and lower switches of motor phase A as an example, the Lagrange multiplier method is used to calculate the phase current compensation value of the healthy phase as follows:

10. A system for implementing the multi-switch open-circuit fault tolerance method of a dual three-phase permanent magnet motor system according to any one of claims 1 to 9, characterized in that: include: Signal acquisition module, real-time acquisition of phase current, rotor position and angular velocity of dual three-phase permanent magnet synchronous motor; The fault-tolerant reference current calculation module uses the Lagrange multiplier method to calculate the phase current compensation value of the healthy phase when different switch tubes in the dual three-phase permanent magnet synchronous motor drive system have open-circuit faults, with the total stator rotating magnetomotive force unchanged before and after the motor fault as the premise and the minimum copper loss as the constraint. The coordinate transformation module transforms the six-phase current of the motor and the fault-tolerant reference current into the rotating coordinate system, and transforms the reference voltage of each plane into the natural coordinate system; PI dual closed-loop control module, used to calculate the reference value of the q-axis current and the reference voltage of each plane; The PWM pulse output module generates a pulse waveform from the fault-tolerant reference voltage in the natural coordinate system through the carrier pulse width modulation strategy and acts on the switch tube.

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