Single-phase open-circuit self-fault-tolerant power distribution control method for dual three-phase permanent magnet synchronous motor

Abstract

The application relates to a single-phase open-circuit self-fault-tolerant power distribution control method of a dual three-phase permanent magnet synchronous motor, which has self-fault-tolerant capability under arbitrary single-phase open circuit. The self-fault-tolerant capability means that fault diagnosis is not needed in fault-tolerant operation, and thus the complicated diagnosis algorithm and misjudgment risk can be avoided. The method realizes the decoupling of torque control, fault-tolerant control and power distribution control by establishing a novel control model containing three subspaces. The technical advantages are as follows: 1) the diagnosis-free self-fault-tolerant capability can be realized for any single-phase open-circuit fault under power distribution, and thus the reliability is improved; 2) the average power of two sub three-phase motors after any single-phase open-circuit fault is the same as that before the fault, that is, the power distribution is not affected by the open-phase fault; 3) under any power distribution condition, the motor runs in the minimum copper loss state that can be realized before and after the open-phase, and thus the energy efficiency is improved; and 4) the controller reconstruction and reference current adjustment are not needed in the open-phase fault-tolerant operation, and thus the control process is simplified.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of dual three-phase permanent magnet synchronous motor control, and particularly relates to power distribution control and fault-tolerant control from two technical angles. BACKGROUND

[0002] Compared with traditional three-phase permanent magnet synchronous motors, dual three-phase permanent magnet synchronous motors have higher torque density, higher operation reliability, higher control freedom (stronger flexibility), and the like, and thus are widely used in the fields of aerospace, rail transit, ship propulsion, and the like. Owing to the modular three-phase characteristics of dual three-phase permanent magnet synchronous motors, the powers generated by two sub three- phases can be independently controlled. When the powers of the two sub three-phases are controlled to be different values, the motor can be regarded as being in a power distribution state. In actual applications, through power distribution control of the dual three-phase permanent magnet synchronous motor, the following advantages can be obtained.

[0003] 1) When two sub three-phases of the dual three-phase permanent magnet synchronous motor are powered by two independent busbars respectively, the power distribution control of the dual three-phase permanent magnet synchronous motor is equivalent to indirectly regulating the powers of different busbars. Therefore, in addition to realizing the inherent electromechanical energy conversion function of the electric drive system, the energy management of different busbar energy sources can also be realized without additional power converters. Therefore, the volume and cost of the system can be reduced. At the same time, since the electromechanical energy conversion of the motor and the energy management of different busbar energy sources can be completed in a single stage of power conversion, the energy transmission efficiency of the system can also be improved.

[0004] 2) Considering the aging degree difference of different components (such as inverter switching devices, busbar capacitors, and the like) in the drive system, appropriate power distribution control of the two sub three-phases of the dual three-phase permanent magnet synchronous motor can prolong the service life and enhance the endurance from the overall perspective of the system.

[0005] Owing to the above advantages, in recent years, the power distribution control technology of the dual three-phase permanent magnet synchronous motor has also been developed and applied. However, the existing power distribution control technology is mostly based on the condition that the windings of the motor are normal. When the windings of the motor are in an open-phase fault, the traditional fault-tolerant control often needs effective fault diagnosis as a prerequisite. Compared with power equalization operation, at this time, the "open-phase fault" and "unbalanced power distribution" will become two different types of unbalanced excitation sources in the system. Therefore, the difficulty of fault diagnosis will be increased, and thus the risk of misdiagnosis will be increased. Therefore, for the power distribution operation of the dual three-phase permanent magnet synchronous motor, it is of great significance to study a control method that can naturally realize effective fault tolerance without fault diagnosis, so as to improve the reliability of the drive system. SUMMARY

[0006] The main purpose of the present application is to provide a novel control method for a dual three-phase permanent magnet synchronous motor, aiming to ensure power distribution control while further possessing self-fault-tolerant capability for possible single-phase open-circuit faults. The effectiveness of the proposed control method is verified through simulation.

[0007] For a dual three-phase permanent magnet synchronous motor with mutually isolated neutral points, its classic vector space decomposition (VSD) model contains two mutually orthogonal subspaces, namely the αβ subspace and the xy subspace, and the αβ subspace is usually converted into the dq subspace through Park transformation. Among them, the dq subspace current reflects the output of the overall electromagnetic torque of the dual three-phase permanent magnet synchronous motor, while the fundamental component in the xy subspace current reflects the power difference of the two sub-three-phase windings. Therefore, by controlling the dq subspace current and the fundamental component in the xy subspace current, the power distribution control of the dual three-phase permanent magnet synchronous motor can be realized.

[0008] In actual motor operation, to ensure effective fault tolerance for any possible open-circuit fault, the traditional control method often needs to be based on effective fault diagnosis. To avoid the problem of increased fault diagnosis difficulty and increased risk of misdiagnosis caused by the dual imbalance factors of "open-phase fault" and "power distribution", the present application proposes a single-phase open-circuit fault-free diagnosis self-fault-tolerant control method that can operate at two sub-three-phase with any power distribution ratio.

[0009] After the open-phase fault occurs, to ensure the constancy of the overall electromagnetic torque of the motor, the reference current of the dq subspace should be maintained in the same state as before the fault, and the reference current of the xy subspace needs to be adjusted to meet the needs of fault-tolerant control and power distribution control. At this time, since the implementation of open-phase fault tolerance and power distribution both rely on the control of the current in the same subspace (xy subspace), this coupling relationship makes it difficult for fault-tolerant control to escape the dependence on fault diagnosis. Therefore, the present application proposes an improved VSD modeling method containing three subspaces for the xy subspace in the VSD model, by fully exploiting the phase sequence characteristic differences of the xy subspace current under the two operating requirements of "fault-tolerant operation" and "power distribution operation". Specifically, without adjusting the construction method of the dq subspace of the VSD model, the xy subspace is further split into a positive-sequence xy subspace and a negative-sequence xy subspace. Through this new modeling method of the dual three-phase permanent magnet synchronous motor, torque control, power distribution control, and fault-tolerant control can be decoupled into three different subspaces. On this basis, by reasonably configuring the reference currents in each subspace, the fault-free diagnosis self-fault-tolerant effect under single-phase open-circuit fault can be effectively realized under any power distribution operation. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 : Schematic diagram of open-phase fault of double three-phase permanent magnet synchronous motor driving system.

[0011] Figure 2 : Overall control block diagram of the control method.

[0012] Figure 3 : 2:1 power distribution control effect of double three-phase permanent magnet synchronous motor under the condition of switching from normal to C2 open circuit (reference speed 1000 r / min, load torque 10 N·m) based on the control method - dq subspace actual current waveform.

[0013] Figure 4 : 2:1 power distribution control effect of double three-phase permanent magnet synchronous motor under the condition of switching from normal to C2 open circuit (reference speed 1000 r / min, load torque 10 N·m) based on the control method - xy_p subspace actual current waveform.

[0014] Figure 5 : 2:1 power distribution control effect of double three-phase permanent magnet synchronous motor under the condition of switching from normal to C2 open circuit (reference speed 1000 r / min, load torque 10 N·m) based on the control method - xy_n subspace actual current waveform.

[0015] Figure 6 : 2:1 power distribution control effect of double three-phase permanent magnet synchronous motor under the condition of switching from normal to C2 open circuit (reference speed 1000 r / min, load torque 10 N·m) based on the control method - actual speed, electromagnetic torque waveform.

[0016] Figure 7 : 2:1 power distribution control effect of double three-phase permanent magnet synchronous motor under the condition of switching from normal to C2 open circuit (reference speed 1000 r / min, load torque 10 N·m) based on the control method - power waveform of two sub three-phase of motor.

[0017] Figure 8 : 2:1 power distribution control effect of double three-phase permanent magnet synchronous motor under the condition of switching from normal to C2 open circuit (reference speed 1000 r / min, load torque 10 N·m) based on the control method - each phase current waveform.

[0018] Figure 9 : 2:1 power distribution control effect of double three-phase permanent magnet synchronous motor under the condition of switching from normal to A1 open circuit (reference speed 1000 r / min, load torque 10 N·m) based on the control method - dq subspace actual current waveform.

[0019] Figure 10 : 2:1 power distribution control effect of dual three-phase permanent magnet synchronous motor based on the proposed control method under the condition of switching from normal to A1 phase open circuit (reference speed 1000 r / min, load torque 10 N·m) - xy_p subspace actual current waveform.

[0020] Figure 11 : 2:1 power distribution control effect of dual three-phase permanent magnet synchronous motor based on the proposed control method under the condition of switching from normal to A1 phase open circuit (reference speed 1000 r / min, load torque 10 N·m) - xy_n subspace actual current waveform.

[0021] Figure 12 : 2:1 power distribution control effect of dual three-phase permanent magnet synchronous motor based on the proposed control method under the condition of switching from normal to A1 phase open circuit (reference speed 1000 r / min, load torque 10 N·m) - actual speed, electromagnetic torque waveform.

[0022] Figure 13 : 2:1 power distribution control effect of dual three-phase permanent magnet synchronous motor based on the proposed control method under the condition of switching from normal to A1 phase open circuit (reference speed 1000 r / min, load torque 10 N·m) - power waveform of two sub-three-phase of the motor.

[0023] Figure 14 : 2:1 power distribution control effect of dual three-phase permanent magnet synchronous motor based on the proposed control method under the condition of switching from normal to A1 phase open circuit (reference speed 1000 r / min, load torque 10 N·m) - each phase current waveform. DETAILED DESCRIPTION

[0024] The technical solutions of the present application are further described below in combination with the drawings and examples.

[0025] Figure 1 A dual three-phase permanent magnet synchronous motor drive system open phase fault schematic diagram is given, wherein the open phase fault takes C2 phase as an example. As can be seen from the figure, the dual three-phase permanent magnet synchronous motor has A1B1C1 and A2B2C2 two sub-three-phase windings which are mutually different by 30° in space, and the neutral points O1 and O2 of the two sub-three-phase windings are isolated from each other. When C2 phase open phase fault occurs, the current in the remaining normal phase windings (A1, B1, C1, A2, B2 phases) should be adjusted to ensure the smoothness of the motor output electromagnetic torque. In addition, considering the power distribution demand of the two sub-three-phase of the dual three-phase permanent magnet synchronous motor, the ratio of the average power of the two sub-three-phase should be further ensured to remain unchanged compared with before the open phase fault.

[0026] In the specific control process, first, the actual current values (i A1, i B1 , i C1 , i A2 , i B2 , i C2 ), and based on the VSD transformation matrix shown in equation (1), the currents of each phase of the motor can be converted to two mutually orthogonal subspaces, namely the αβ subspace and the xy subspace. ;

[0027] where i α and i β are the currents on the two orthogonal axes (the α-axis and the β-axis) of the αβ subspace, i x and i y are the currents on the two orthogonal axes (the x-axis and the y-axis) of the xy subspace.

[0028] By performing a Park transformation on the currents of the αβ subspace and defining the resulting currents as the dq subspace currents, the dq subspace currents can be expressed as:

[0029] ;

[0030] where i d and i q are the currents on the two orthogonal axes (the d-axis and the q-axis) of the dq subspace, and θ e is the rotor electrical angle of the dual three-phase permanent magnet synchronous motor.

[0031] The expression of the electromagnetic torque T e of the dual three-phase permanent magnet synchronous motor is shown in equation (3):

[0032] T e = 3P[ψ f i q +(L d -L q )i d i q ](3);

[0033] where P is the number of pole pairs of the motor, ψ f is the permanent magnet flux linkage, L d and L q are the d-axis and q-axis inductances of the dq subspace. It can be seen that T e is only related to the dq subspace currents, and is not directly related to the xy subspace currents. Therefore, to ensure that the electromagnetic torque is constant before and after the open-phase fault, the dq subspace currents should be kept constant.

[0034] On the other hand, in the VSD model of the dual three-phase permanent magnet synchronous motor, the fundamental component in the xy subspace currents reflects the power difference between the two sub three- phases. In the case where all phases are normal, when the dq subspace currents take id = 0, i q = I > 0), if the power ratio of two sub-three-phase is required to be K1 : K2 (K1 + K2 = 1), by controlling the xy subspace current to the form shown in equation (4), the corresponding power distribution effect can be achieved under the premise of minimum copper loss.

[0035] ;

[0036] When a certain phase of the dual three-phase permanent magnet synchronous motor is open-circuit fault, taking C2 phase open circuit as an example, at this time, since i C2 is forced to zero, the αβ subspace current and the xy subspace current obtained after the VSD transformation shown in equation (1) produce the coupling relationship shown in equation (5):

[0037] i y = -i β (5);

[0038] If the dq subspace current is controlled to the ideal value (i d = 0, i q = I > 0) after the open-phase fault, combining equation (2) and equation (5), it can be known that the y-axis current of the xy subspace at this time is specifically shown in equation (6):

[0039] i y = -i β = -Icosθ e (6);

[0040] Based on equation (6), it can be known that the y-axis current i y cannot be controlled to the form shown in equation (4) after the open-phase fault. Therefore, in order to still achieve the power distribution of K1 : K2 after single-phase open circuit fault, the x-axis current i x of the xy subspace needs to be further adjusted. Without loss of generality, it can be first assumed that the ideal form of the x-axis current under the corresponding fault condition is equation (7), and the corresponding undetermined values I x and θ x can be determined in combination with the power distribution coefficient requirement and the minimum copper loss and other indicators.

[0041] i x = I x sin(θ e + θ x ) (7);

[0042] 1) Determine the preliminary relationship of I x and θ x based on the power distribution requirement;

[0043] When id = 0 control is adopted, the electromagnetic torque (Te1 ,T e2 ) are proportional to the q-axis currents (i q1 ,i q2 ) of the two sub-three-phase respectively. When the dq subspace currents satisfy i d = 0, i q = I > 0, and the xy subspace currents satisfy equation (6), equation (7), the following relationship can be obtained:

[0044] ;

[0045] It can be seen from equation (8) that the q-axis currents (electromagnetic torques) of the two sub-three-phase are the superposition of the direct current component and the 2nd-order alternating current component (the 2nd-order alternating current component amplitudes of the q-axis currents (electromagnetic torques) of the two sub-three-phase are equal, and the phases are opposite, so the total electromagnetic torque of the motor only contains the direct current component) at this time. Since the two sub-three-phase share the same rotor (i.e. the same speed), the electromagnetic torque of the two sub-three-phase with periodic fluctuation indicates that the instantaneous power of the two sub-three-phase also has periodic fluctuation. Therefore, the power distribution of the two sub-three-phase K1 : K2 under single-phase circuit fault corresponds to the ratio of the average power (not the instantaneous power) of the two sub-three-phase K1 : K2. Therefore, it can be known from equation (8) that at this time, equation (9) needs to be satisfied:

[0046] ;

[0047] Further, let K1 : K2 = K, then from equation (9), the preliminary relationship of I x and θ x that satisfies the power distribution requirement is:

[0048] ;

[0049] 2) determine the final value of I x and θ x based on the minimum copper loss requirement;

[0050] When the dq subspace currents have been controlled to the ideal form of i d = 0, i q = I > 0, in order to ensure the minimum copper loss, the copper loss generated by the xy subspace should be as small as possible. Combined with equation (6), equation (7), the xy subspace copper loss P Cu_xy has the following characteristics:

[0051] ;

[0052] Wherein, set then the average value of f(θ e ) on θ e ∈ [0, 2π] can be expressed as:

[0053] ;

[0054] Therefore, when P Cu_xy is minimum, π(K tan 2 θ x +K+1) is minimum, that is, it needs to satisfy:

[0055] θ x =0 (13);

[0056] In combination with formula (10) and K=K1:K2 (K1 +K2=1), it can be obtained that:

[0057] ;

[0058] Therefore, in combination of formula (6), formula (7), formula (13) and formula (14), in order to realize the power distribution ratio operation of two sub-three-phase according to K1:K2 (K1 +K2=1) after single-phase open-circuit fault, while ensuring effective fault tolerance and minimum copper loss, the xy subspace current should be controlled in the following form:

[0059] ;

[0060] However, it is worth mentioning that the xy subspace ideal current shown in formula (15) is for C2 phase open-circuit. When single-phase open-circuit fault occurs in other phases, the xy subspace ideal current should be adjusted according to similar analysis method. In other words, if fault diagnosis is not performed, effective power distribution and fault tolerance control cannot be directly realized according to the above derivation results.

[0061] Assuming that the open-phase fault occurs in the C2 phase, if self-fault-tolerant control without fault diagnosis can be realized, in principle, the xy subspace actual current before fault needs to be automatically converged to the form shown in formula (4) under constant xy subspace reference current, and the xy subspace actual current after fault needs to be automatically converged to the form shown in formula (15). However, by comparing formula (4) and formula (15), it can be found that no matter what control method is adopted for the xy subspace current, the actual currents of the xy subspace before and after fault cannot be converged to the two different forms of formula (4) and formula (15) under constant reference current. Therefore, in order to realize single-phase open-circuit fault diagnosis-free self-fault-tolerant control under power distribution, the present application further proposes the following method.

[0062] First, based on the symmetrical component method, the xy subspace can be decomposed into a positive-sequence xy subspace (denoted as "xy_p subspace") and a negative-sequence xy subspace (denoted as "xy_n subspace"). After this operation, taking the C2 phase open circuit fault as an example, the ideal fault-tolerant current of the xy subspace shown in equation (15) is decomposed into the "xy_p subspace" and the "xy_n subspace". The ideal fault-tolerant current of the "xy_p subspace" and the ideal fault-tolerant current of the "xy_n subspace" are shown in equations (16) and (17) respectively, and their relationship with the original ideal fault-tolerant current of the xy subspace shown in equation (15) is shown in equation (18):

[0063] ;

[0064] In the formula, i x_p And i y_p are respectively "x y_p The current i on the two orthogonal axes (x_p axis and y_p axis) of the subspace. x_n and i y_n These are the currents on the two orthogonal axes (x_n axis and y_n axis) of the "xy_n subspace".

[0065] By comparing equations (4) and (17), it can be found that the ideal current of the original xy subspace under fault-free conditions corresponds to the ideal current of the "xy_n subspace" after the C2 phase open circuit fault. In other words, it can be considered that by performing positive and negative sequence decomposition on the xy subspace, the ideal current of the "xy_n subspace" remains unchanged regardless of whether the C2 phase is open circuit (i.e., it is only affected by power distribution control), while the occurrence of a fault will only cause the ideal current of the "xy_p subspace" to change from zero to the non-zero fundamental value shown in equation (16). It is worth noting that the non-zero fundamental ideal current of the "xy_p subspace" after the fault shown in equation (16) is i C2 =0 to ensure that the dq subspace current is controlled to the ideal value (i d =0, i q =I>0) is a forced result, meaning that the corresponding current cannot be controlled to zero.

[0066] Furthermore, based on similar analytical methods, it can be proven that regardless of which phase the single-phase open-circuit fault occurs in, the following two characteristics hold true:

[0067] 1) In order to achieve phase failure tolerance, power distribution and minimum copper loss before and after phase failure, the ideal current of the "xy_n subspace" after phase failure is always equal to the ideal current of the original xy subspace before phase failure as shown in equation (4). That is, the ideal current of the "xy_n subspace" under any single-phase circuit failure is all as shown in equation (17).

[0068] 2) To realize open-phase fault tolerance, power distribution and minimum copper loss before and after open-phase, the ideal current of "xy_p subspace" before open-phase is zero, while the ideal current of "xy_p subspace" after open-phase is the current containing only fundamental component forcedly introduced by open-phase fault.

[0069] Based on the above features, the current control of xy subspace can be converted into the current control of "xy_p subspace" and "xy_n subspace". Specifically:

[0070] 1) For "xy_p subspace", the current controller is only used to adjust the components other than the fundamental current component. For this purpose, the feedback current of "xy_p subspace" current controller is the current obtained by separating the fundamental component from the actual current of the subspace. To realize the separation of the fundamental component of the actual current of "xy_p subspace", a notch filter with the fundamental frequency as the center frequency can be used, and its transfer function is shown in equation (19):

[0071] ;

[0072] In the equation, ξ is the damping coefficient of the notch filter, ω e is the angular velocity of the fundamental frequency of the motor.

[0073] Since the "xy_p subspace" current controller does not control the fundamental current component, the reference current can be set to zero regardless of whether the fault occurs, that is, equation (20).

[0074] ;

[0075] Through the above configuration, the actual current of "xy_p subspace" before the fault can be automatically adjusted to zero under the constant reference current before and after the fault (thus the fault diagnosis can be avoided), and the actual current of "xy_p subspace" after the fault can be automatically adjusted to the ideal form containing only the fundamental component under the corresponding fault condition (for example, the ideal form of "xy_p subspace" current under C2 open-phase is equation (16)).

[0076] In addition, to realize the suppression of the main harmonic current component of the VSD model xy subspace (the main harmonics before single-phase open-phase fault are 5th and 7th harmonics, and the main harmonics after fault are 3rd, 5th and 7th harmonics), the corresponding harmonic suppression operation should also be performed in "xy_p subspace". Based on the principle of fault diagnosis-free, the harmonic suppression framework before and after open-phase fault needs to be unified. Therefore, a quasi-proportional resonant controller with three resonance points of 3 times, 5 times and 7 times the fundamental frequency is selected as the "xy_p subspace" current controller. The transfer function of the corresponding current controller is shown in equation (21):

[0077] ;

[0078] where K p_(xy _ p) is a proportional coefficient, K r_m _ (xy _ p) is a resonance coefficient at the resonance point of m times the fundamental frequency, ω

[0079] ω c_m_(xy_p) is a bandwidth at the resonance point of m times the fundamental frequency.

[0080] 2) For the "xy_n subspace", regardless of whether a fault occurs or not, to achieve power distribution with minimum copper loss, the ideal current is of the form shown in equation (17). Therefore, the reference current of the "xy_n subspace" can be uniformly set as:

[0081] ;

[0082] To achieve effective tracking of the fundamental reference current shown in equation (22), the current controller selects a quasi-proportional resonant controller with the fundamental frequency as the resonance point. In addition, considering the suppression of the main harmonic current component before and after the fault, the current controller of this subspace is further introduced with three resonance points of 3 times the fundamental frequency, 5 times the fundamental frequency and 7 times the fundamental frequency. Therefore, the transfer function of the "xy_n subspace" current controller is shown in equation (23):

[0083] ;

[0084] where K p_ (xy _n) is a proportional coefficient, K r_m _ (xy _n) is a resonance coefficient at the resonance point of m times the fundamental frequency, ω c_m_(xy_n) is a bandwidth at the resonance point of m times the fundamental frequency.

[0085] The above control method can make the "xy_p subspace" current and the "xy_n subspace" current automatically converge to the corresponding ideal value before and after any single-phase open-circuit fault under constant reference current. The equivalent effect of this control process to the traditional xy subspace is that it can make the xy subspace current before the fault automatically converge to the ideal form shown in equation (4), while making the xy subspace current after any single-phase open-circuit fault automatically converge to an ideal form different from equation (4) (for example, the ideal form of the xy subspace current under C2 phase open-circuit is equation (15)). Therefore, it can achieve diagnostic-free self-fault-tolerant power distribution while ensuring minimum copper loss.

[0086] In addition to converting the current control of the xy subspace into the current control of the new "xy_p subspace" and "xy_n subspace", the current control of the dq subspace is completely equivalent to the traditional method. Considering the direct current reference of the dq subspace (i d ref = 0, i q refThe tracking requirement of the single-phase open-circuit fault is met, and the dq subspace main harmonic current components (2nd, 4th and 6th harmonic) after the single-phase open-circuit fault are inhibited, a quasi-proportional integral resonant controller with three resonance points of 2 times, 4 times and 6 times of the fundamental frequency is used as the dq subspace current controller, and the transfer function is shown in formula (24):

[0087] ;

[0088] In the formula, K p_(dq) is a proportional coefficient, K i_(dq) is an integral coefficient, K r_m_(dq) is a resonance coefficient at the resonance point of m times of the fundamental frequency, ω c_m_(dq) is a bandwidth at the resonance point of m times of the fundamental frequency.

[0089] Based on the above design process, Figure 2 the overall control block diagram of the double three-phase permanent magnet synchronous motor single-phase open-circuit self-fault tolerant power distribution control method is given, which specifically includes the coordinated control of the dq, xy_p and xy_n subspace currents.

[0090] To verify the effectiveness of the double three-phase permanent magnet synchronous motor single-phase open-circuit self-fault tolerant power distribution control method, simulation software is used for analysis and verification. The parameters of the double three-phase permanent magnet synchronous motor used are shown in Table 1.

[0091] Table 1: Parameters of the double three-phase permanent magnet synchronous motor

[0092] ;

[0093] Figures 3 to 8 The control effect of the three-subspace type control method when C2 phase is switched from normal to open-phase under the condition of rated reference speed, rated load torque and 2:1 power distribution instruction. As shown in Figure 3 , after the open-phase fault occurs, the dq subspace current can be maintained constant, ensuring that Figure 6 the motor speed and electromagnetic torque are not affected by the open-phase fault. At the same time, for the “xy_p subspace”, even if the reference currents before and after the fault are both zero, the fundamental current component introduced due to the open-phase fault is effectively retained (as shown in Figure 4 ) by the fundamental wave notch processing of the actual current, ensuring effective self-fault tolerance. In addition, as shown in Figure 5 , the “xy_n subspace” current before and after the fault both satisfy the characteristics shown in formula (22), thus ensuring Figure 7 .

[0094] The ratio (2:1) of the average power (700W and 350W respectively) of the two sub-three-phase motors is not affected by the open-phase fault.

[0095] To further verify the universality of the proposed method for any single-phase open-circuit fault, Figures 9 to 14 The control effect of the proposed three-subspace type control method when the A1 phase is switched from normal to open-phase is given. The reference speed and load torque are still set to the rated value, and the power distribution instruction is still set to 2:1. The results show that the proposed control method can realize effective self-fault tolerance while ensuring that the power distribution coefficient remains unchanged, regardless of whether the open-phase fault occurs in the sub-three-phase with a smaller power distribution coefficient or in the sub-three-phase with a larger power distribution coefficient. Figures 3 to 14 The results shown can be seen that, regardless of whether the open-phase fault occurs in the sub-three-phase with a smaller power distribution coefficient or in the sub-three-phase with a larger power distribution coefficient, the proposed control method can realize effective self-fault tolerance while ensuring that the power distribution coefficient remains unchanged.

[0096] Based on the disclosure of the above description, those skilled in the art of the present application can also make changes and modifications to the above embodiments. Therefore, the present application is not limited to the specific embodiments described above. Any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present application shall fall within the scope of the present application. In addition, although some specific terms are used in the present specification, these terms are only for convenience of explanation and do not constitute any limitation on the present application.

Claims

1. A single-phase open-circuit self-fault-tolerant power distribution control method for a dual three-phase permanent magnet synchronous motor, characterized by, The control process comprises the following steps: Step 1: In each control cycle, the actual currents i A1 , B1 , C1 , A2 , B2 , C2 of each phase of the dual three-phase permanent magnet synchronous motor are collected, and a vector space decoupling transformation is performed to obtain two mutually orthogonal subspace currents, i α , β e.g. αβ subspace currents i x , y and xy subspace currents i Step 2: Perform a Park transformation on the αβ subspace currents i α , i β ; and define the resulting currents as dq subspace currents i d , i q ; Step 3: based on the symmetrical component method, positive and negative sequence decomposition is performed on the xy subspace to obtain a positive sequence xy subspace and a negative sequence xy subspace, which are defined as "xy_p subspace" and "xy_n subspace" respectively; Step 4: Actual current i in the dq subspace d , q Close loop control is performed to set the reference value i d and i q of i d ref = 0, i q ref = I; the output value of the close loop control is used as the reference voltage u d ref , u q ref in the dq subspace; Step 5: current closed-loop control is performed on the "xy_p subspace", and the feedback current under closed-loop control is not directly the actual current i x_p 、 y_p ; instead, the feedback current is set as a notch filter with the fundamental frequency as the center frequency to the actual current i x_p 、 y_p after the fundamental component separation; at the same time, the "xy_p subspace" current closed-loop control reference value i x_p ref 、 y_p ref is: ； The closed loop control output value as "xy_p subspace" reference voltage u x_p ref , u y_p ref ; Step 6: current closed-loop control is performed on the "xy_n subspace", and the feedback current under closed-loop control directly uses the actual current i x_n , y_n of the "xy_n subspace" x_n ref , y_n ref is set as: ， In the formula, K1 and K2 are power distribution coefficients of two sub three-phase of double three-phase permanent magnet synchronous motor respectively, and satisfy K1+K2=1, I is the reference value of dq subspace current i q , θ e is the rotor electrical angle of double three-phase permanent magnet synchronous motor; the closed-loop control output value is taken as the "xy_n subspace" reference voltage u x_n ref , u y_n ref ; Step 7: Obtain the xy subspace reference voltage u from the "xy_p subspace" reference voltage obtained in step 5 and the "xy_n subspace" reference voltage obtained in step 6 x ref , u y ref ; Step 8: According to the dq subspace reference voltage obtained in step 4 and the xy subspace reference voltage obtained in step 7, space vector pulse width modulation is performed to obtain motor phase driving signals S A1 、S B1 、S C1 、S A2 、S B2 、S C2 , the whole control process is completed.

2. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The vector space decoupling transformation process in step 1 is as follows: 。 3. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The Park transformation process in step 2 is as follows: 。 4. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The relationship between the "xy_p subspace", "xy_n subspace" obtained in step 3 and the current in the xy subspace is as follows: 。 5. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The dq subspace current closed-loop controller in step 4 is a quasi-proportional integral resonant controller with three resonance points of 2 times the fundamental frequency, 4 times the fundamental frequency and 6 times the fundamental frequency, and its transfer function is as follows: ， where K p_(dq) is a proportionality coefficient, K i_(dq) is an integration coefficient, K r_m_(dq) is a resonance coefficient at the resonance point of m times the fundamental frequency, ω c_m_(dq) is a bandwidth at the resonance point of m times the fundamental frequency, ω e is the angular speed of the motor fundamental frequency.

6. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The transfer function of the notch filter with the fundamental frequency as the center frequency in step 5 is as follows: ， where ξ is the notch filter damping coefficient, ω e is the motor fundamental angular velocity.

7. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The "xy_p subspace" current closed-loop controller in step 5 is a quasi-proportional resonant controller with three resonance points of 3 times the fundamental frequency, 5 times the fundamental frequency and 7 times the fundamental frequency, and its transfer function is as follows: ， where K p_(xy_p) is a proportionality factor, K r_m_(xy_p) is a resonance factor at the resonance point of m times the fundamental frequency, ω c_m_(xy_p) is a bandwidth at the resonance point of m times the fundamental frequency, ω e is the angular speed of the fundamental frequency of the electric machine.

8. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The "xy_n subspace" current closed-loop controller in step 6 is a quasi-proportional resonant controller with four resonance points of 1 times the fundamental frequency, 3 times the fundamental frequency, 5 times the fundamental frequency and 7 times the fundamental frequency, and its transfer function is as follows: ， where K p_(xy_n) is a proportionality factor, K r_m_(xy_n) is a resonance factor at the resonance point of m times the fundamental frequency, ω c_m_(xy_n) is a bandwidth at the resonance point of m times the fundamental frequency, ω e is the angular speed of the fundamental frequency of the electric machine.

9. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The specific implementation of the step 7 is to add u x_p ref , u y_p ref and u x_n ref , u y_n ref to obtain the xy subspace reference voltage u x ref , u y ref , that is, u x ref = u x_p ref + u x_n ref , u y ref = u y_p ref + u y_n ref .

10. The dual three-phase permanent magnet synchronous motor single-phase open-circuit self-fault-tolerant type power distribution control method according to claim 1, characterized by, The step 8 comprises: Step 801: Perform inverse Park transformation on the dq subspace reference voltage u d ref u q ref of the following equation: ， The αβ subspace reference voltage u is obtained as α ref , u β ref ; Step 802: Based on the classical vector space decoupling model framework, the αβ subspace reference voltage u obtained in step 801 is selected α ref , u β ref and the xy subspace reference voltage u obtained in step 7 x ref , u y ref The basic voltage vectors of the motor are obtained by calculating the action time of each basic voltage vector, and the motor phase driving signals S A1 , S B1 , S C1 , S A2 , S B2 , S C2 .

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