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

Abstract

The invention relates to a single-phase open-circuit self-fault-tolerant power distribution control method for double three-phase permanent magnet synchronous motors. The method has the self-fault-tolerant capability under any single-phase open circuit. The self fault tolerance, namely fault tolerance operation, does not need fault diagnosis, so that a tedious diagnosis algorithm and a misjudgment risk can be avoided. According to the method, decoupling of torque control, fault-tolerant control and power distribution control is realized by establishing a novel control model comprising three subspaces. The method has the technical advantages that 1) diagnosis-free self-fault tolerance can be realized for any single-phase open-circuit fault occurring under power distribution, so that the reliability is improved; 2) after any single-phase open-circuit fault occurs, the average power of two sub-three phases of the motor can be automatically ensured to be the same as that before the fault, that is, the power distribution is not influenced by the open-phase fault; (3) under any power distribution condition, the motor runs in a minimum copper loss state which can be realized by corresponding working conditions before and after phase failure, so that the energy efficiency is improved; and 4) controller reconstruction and reference current adjustment do not need to be carried out during fault-tolerant fault tolerance, so that the control flow 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 the dual three-phase permanent magnet synchronous motor, the power generated by two sub three- phases can be independently controlled. When the powers of the two sub three-phases of the motor 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, power distribution control of the dual three-phase permanent magnet synchronous motor is equivalent to indirectly regulating the power 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 to a certain extent. 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 neutral point mutual isolation, 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 break away from 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. 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. 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. 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. 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.

[0014] 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.

[0015] Figure 10 : 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 - xy_p subspace actual current waveform.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) — actual current waveform in xy_n subspace. 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. 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. 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

[0016] The technical solutions of the present application are further described below in combination with the drawings and examples.

[0017] Figure 1 A schematic diagram of the open-phase fault of the dual three-phase permanent magnet synchronous motor drive system is given, where the open-phase fault is taken as an example of C2 phase. 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 the C2 phase occurs open-phase fault, the currents 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, it is also necessary to further ensure that the ratio of the average power of the two sub-three-phase remains unchanged compared with before the open-phase fault.

[0018] In the specific control process, first, the actual current values (i A1 ,i B1 ,i C1 ,i A2 ,i B2 ,i C2 ) of each phase of the motor are collected, 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, i.e. αβ subspace and xy subspace.

[0019]

[0020] wherein iα and i β are currents on two orthogonal axes (a-axis and β-axis) in αβ subspace, respectively. x and i y are currents on two orthogonal axes (x-axis and y-axis) in xy subspace, respectively.

[0021] By performing Park transformation on the currents in αβ subspace and defining the resulting currents as currents in dq subspace, the currents in dq subspace can be expressed as:

[0022]

[0023] where i d and i q are currents on two orthogonal axes (d-axis and q-axis) in dq subspace, respectively, and θ e is the rotor electrical angle of the dual three-phase permanent magnet synchronous motor.

[0024] The expression of electromagnetic torque T e of the dual three-phase permanent magnet synchronous motor is shown in equation (3):

[0025] T e = 3P [ψ f i q + (L d - L q ) i d i q ] (3)

[0026] 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 in dq subspace, respectively. It can be seen that T e is only related to the currents in dq subspace, and is not directly related to the currents in xy subspace. Therefore, to ensure that the electromagnetic torque is constant before and after the open-phase fault, the currents in dq subspace should be kept constant.

[0027] 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 currents in dq subspace are controlled to i d = 0, i q = I > 0, if the ratio of the powers of the two sub three-phases is required to be K1:K2 (K1+K2=1), then by controlling the currents in xy subspace to the form shown in equation (4), the corresponding power distribution effect can be achieved under the premise of minimum copper loss.

[0028]

[0029] When a circuit breaking fault occurs in one phase of the dual three-phase permanent magnet synchronous motor, taking the C2 phase circuit breaking as an example, the phase current is forced to zero, and thus the αβ subspace current and the xy subspace current obtained after the VSD conversion shown in formula (1) have the coupling relationship shown in formula (5): C2

[0030] i y =-i β (5)If the dq subspace current is controlled to the ideal value (i d =0, i q =I>0) after the phase breaking fault, it can be known from formula (2) and formula (5) that the y-axis current of the xy subspace at this time is specifically shown in formula (6):

[0031] i y =-i β =-Icosθ e (6)

[0032] Based on formula (6), it can be known that the y-axis current i y after the phase breaking fault cannot be controlled to the form shown in formula (4). Therefore, in order to still achieve the power distribution of K1:K2 after the single-phase circuit breaking 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 formula (7), and the corresponding to-be-determined values I x and θ x can be determined in combination with the power distribution coefficient requirement and the copper loss minimization index.

[0033] i x =I x sin(θ e +θ x ) (7)1) Determine the preliminary relationship of I x and θ x based on the power distribution requirement

[0034] When i d =0 is adopted for control, the electromagnetic torques (T e1 , T e2 ) of the two sub three-phase of the dual three-phase permanent magnet synchronous motor are respectively proportional to the q-axis currents (i q1 , i q2 ) of the two sub three-phase. When the dq subspace current satisfies i d =0, i q =I>0, and the xy subspace current satisfies formula (6) and formula (7), the following relationship can be obtained:

[0035]

[0036] ​As can be seen from equation (8), the q-axis current (electromagnetic torque) of each of the two sub-three-phase permanent magnet synchronous motor is the superposition of a direct current component and a 2nd-order alternating current component (the 2nd-order alternating current component of the q-axis current (electromagnetic torque) of each of the two sub-three-phase permanent magnet synchronous motor has the same amplitude and opposite phase, so the total electromagnetic torque of the motor only contains a direct current component). Since the two sub-three-phase permanent magnet synchronous motors share the same rotor (i.e., the same speed), the periodic fluctuation of the electromagnetic torque of the two sub-three-phase permanent magnet synchronous motors indicates that the instantaneous power of the two sub-three-phase permanent magnet synchronous motors also has periodic fluctuation. Therefore, the power distribution of the two sub-three-phase permanent magnet synchronous motors K1:K2 under single-phase circuit fault corresponds to the ratio of the average power (rather than the instantaneous power) of the two sub-three-phase permanent magnet synchronous motors K1:K2. Therefore, it can be known from equation (8) that the following equation needs to be met at this time:

[0037]

[0038] Further, let K1:K2=K, then from equation (9), it can be obtained that I x and θ x meet the following preliminary relationship:

[0039]

[0040] 2) Determine the final value of I x and θ x based on the minimum copper loss requirement

[0041] When the dq subspace current has been controlled to the ideal form i d =0, i q =I>0, in order to ensure the minimum copper loss, the copper loss generated by the xy subspace needs to be as small as possible. In combination with equations (6) and (7), the xy subspace copper loss P Cu_xy has the following characteristics:

[0042]

[0043] wherein, let the average value of f(θ e ) in θ e ∈[0,2π] can be expressed as:

[0044]

[0045] Therefore, when P Cu_xy is the smallest, π(Ktan 2 θ x +K+1) needs to be the smallest, that is, the following equation needs to be met:

[0046] θ x =0 (13)

[0047] In combination with equation (10) and K=K1:K2 (K1+K2=1), the following equation can be obtained:

[0048]

[0049] Therefore, combining formula (6), formula (7), formula (13) and formula (14), to realize the operation of two sub-three-phase according to the power distribution ratio of K1:K2 (K1+K2=1) after single-phase circuit fault, while ensuring effective fault tolerance and minimum copper loss, the xy subspace current should be controlled as follows:

[0050]

[0051] However, it is worth mentioning that the xy subspace ideal current shown in formula (15) is for C2 phase circuit breaking. When single-phase circuit fault occurs in other phases, the xy subspace ideal current should be adjusted accordingly according to similar analysis method. In other words, without fault diagnosis, effective power distribution and fault tolerance control cannot be realized directly according to the above derivation results.

[0052] 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) with 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, to realize single-phase circuit fault diagnosis-free self-fault-tolerant control under power distribution, the present application further proposes the following method.

[0053] Firstly, 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 circuit breaking fault as an example, the xy subspace ideal fault-tolerant current shown in formula (15) is decomposed into the “xy_p subspace” and the “xy_n subspace”. The “xy_p subspace” ideal fault-tolerant current and the “xy_n subspace” ideal fault-tolerant current are shown in formula (16) and formula (17) respectively, and the relationship with the original xy subspace ideal fault-tolerant current shown in formula (15) is shown in formula (18).

[0054]

[0055] In the formula, i x_p and i y_p are the currents on the two orthogonal axes (x_p axis and y_p axis) of the “xy_p subspace”, i x_nand i y_n are the currents on the two orthogonal axes of the "xy_n subspace" (x_n axis and y_n axis), respectively.

[0056] By comparing equation (4) with equation (17), it can be found that the ideal current of the original xy subspace when there is no fault corresponds to the ideal current of the "xy_n subspace" after the C2-phase is disconnected. In other words, at this time, 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 (i.e., it is only affected by the power distribution control) regardless of whether the C2-phase is disconnected or not, and the occurrence of the fault only causes 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 is a forced result caused by ensuring that the dq subspace current is controlled to the ideal value (i d = 0, i q = I > 0) and that the corresponding current cannot be controlled to zero.

[0057] Further, according to a similar analysis method, it can be proved that the following two characteristics are true regardless of which phase the single-phase disconnection fault occurs in:

[0058] 1) To achieve fault tolerance, power distribution, and minimum copper loss before and after the phase disconnection, the ideal current of the "xy_n subspace" after the phase disconnection is equal to the ideal current of the original xy subspace before the phase disconnection shown in equation (4), that is, the ideal current of the "xy_n subspace" under any single-phase disconnection fault is equation (17);

[0059] 2) To achieve fault tolerance, power distribution, and minimum copper loss before and after the phase disconnection, the ideal current of the "xy_p subspace" before the phase disconnection is zero, and the ideal current of the "xy_p subspace" after the phase disconnection is a fundamental component-only current that is forced to be introduced by the phase disconnection fault.

[0060] Based on the above characteristics, the current control on the xy subspace can be converted into current control on the "xy_p subspace" and the "xy_n subspace". Specifically:

[0061] 1) For the "xy_p subspace", the current controller thereof is only used to adjust components other than the fundamental current component. To this end, the feedback current of the "xy_p subspace" current controller is the current obtained by separating the fundamental component from the actual current of the subspace. To achieve the separation of the fundamental component of the actual current of the "xy_p subspace", a notch filter with a fundamental frequency as the center frequency can be used, and the transfer function thereof is shown in equation (19):

[0062]

[0063] where ξ is the damping coefficient of the notch filter, ω e is the fundamental angular speed of the motor.

[0064] 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 a fault occurs, i.e., formula (20).

[0065]

[0066] With the above configuration, the actual current of the "xy_p subspace" before the fault can be automatically adjusted to zero under the constant reference current before and after the fault (thereby eliminating fault diagnosis), and the actual current of the "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 the "xy_p subspace" current under C2 phase open circuit is formula (16)).

[0067] In addition, to achieve suppression of the VSD model xy subspace main harmonic current component (the main harmonics before single-phase open circuit 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 the "xy_p subspace". Based on the principle of fault-free diagnosis, the harmonic suppression framework before and after the open-phase fault needs to be unified. Therefore, a quasi-proportional resonant controller with three resonance points of 3rd, 5th and 7th fundamental frequency is selected as the "xy_p subspace" current controller. The transfer function of the corresponding current controller is shown in formula (21):

[0068]

[0069] where K p_(xy_p) is the proportional coefficient, K r_m_(xy_p) is the resonance coefficient at the resonance point of m times the fundamental frequency, and ω c_m_(xy_p) is the bandwidth at the resonance point of m times the fundamental frequency.

[0070] 2) For the "xy_n subspace", regardless of whether a fault occurs, to achieve power distribution with minimum copper loss, the ideal current is in the form shown in formula (17). Therefore, the reference current of the "xy_n subspace" can be uniformly set as:

[0071]

[0072] To achieve effective tracking of the fundamental reference current shown in formula (22), the current controller selects a quasi-proportional resonant controller with the fundamental frequency as the resonance point. In addition, the suppression of the main harmonic current component before and after the fault is also considered, and three resonance points of 3rd, 5th and 7th fundamental frequency are further introduced to the subspace current controller. Therefore, the transfer function of the "xy_n subspace" current controller is shown in formula (23):

[0073]

[0074] wherein 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.

[0075] The above control method can make the "xy_p subspace" current and the "xy_n subspace" current automatically converge to the corresponding ideal values before and after any single-phase open-circuit fault under a constant reference current. The control process is equivalent to the effect of the traditional xy subspace, which can make the xy subspace current before the fault automatically converge to the ideal form shown in equation (4) under a constant reference current, and make 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 open-circuit is equation (15)). Therefore, diagnostic-free self-fault tolerance under power distribution can be achieved while ensuring minimal copper loss.

[0076] 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 tracking requirement of the direct-axis and quadrature-axis direct-current reference currents (i d ref = 0, i q ref = I > 0), and at the same time achieving suppression of the main harmonic current components (2nd, 4th, 6th harmonics) of the dq subspace after single-phase open-circuit fault, 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 is adopted as the dq subspace current controller, and its transfer function is shown in equation (24):

[0077]

[0078] wherein 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 the fundamental frequency, ω c_m_(dq) is a bandwidth at the resonance point of m times the fundamental frequency.

[0079] 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.

[0080] To verify the effectiveness of the proposed single-phase circuit-breaking self-tolerant power distribution control method for dual three-phase permanent magnet synchronous motors, simulation software was used for analysis and verification. The parameters of the dual three-phase permanent magnet synchronous motors used are shown in Table 1.

[0081] Table 1 Parameters of Dual Three-Phase Permanent Magnet Synchronous Motors

[0082]

[0083] Figures 3 to 8 This paper examines the control effect of a proposed three-subspace control method when phase C2 switches from normal to phase loss under rated reference speed, rated load torque, and a 2:1 power distribution command. Figure 3 It can be seen that when a phase loss fault occurs, the dq subspace current can remain constant, ensuring that... Figure 6 The motor speed and electromagnetic torque shown were not affected by the phase loss fault. Furthermore, for the "xy_p subspace," even though the reference current is zero before and after the fault, the fundamental current component introduced by the phase loss fault is effectively preserved by using fundamental notch filtering on the actual current (e.g., ...). Figure 4 As shown), this ensures effective self-fault tolerance. Furthermore, by... Figure 5 It can be seen that the current in the "xy_n subspace" satisfies the characteristics shown in equation (22) before and after the fault, thus ensuring that Figure 7 The ratio (2:1) of the average power of the two sub-three-phase motors shown (700W and 350W respectively) is not affected by the phase loss fault.

[0084] 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 control method is presented when phase A1 switches from normal to phase loss. The reference speed and load torque are both set to their rated values, and the power distribution command is still set to 2:1. (Summary) Figures 3 to 14 The results show that, regardless of whether the phase loss fault occurs in a sub-phase with a smaller power distribution factor or a sub-phase with a larger power distribution factor, the proposed control method can achieve effective self-fault tolerance while ensuring that the power distribution factor remains unchanged.

[0085] Based on the disclosure in the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above. Any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A single-phase circuit-breaking self-fault-tolerant power distribution control method for dual three-phase permanent magnet synchronous motors, characterized in that, By constructing a novel control model containing three subspaces, the decoupling of torque control, fault-tolerant control, and power distribution control is achieved.

2. The single-phase circuit-breaking self-fault-tolerant power distribution control method for dual three-phase permanent magnet synchronous motors according to claim 1, characterized in that, The three subspaces in the new control model are constructed by retaining the dq subspace unchanged and further decomposing the xy subspace into a positive-order xy subspace and a negative-order xy subspace, based on the two subspaces (dq subspace and xy subspace) in the classic vector space decoupling model of the dual three-phase permanent magnet synchronous motor.

3. The single-phase circuit-breaking self-fault-tolerant power distribution control method for a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that, The dq subspace current controller is a quasi-proportional-integral resonant controller with three resonant points: 2 times the fundamental frequency, 4 times the fundamental frequency, and 6 times the fundamental frequency, thereby realizing electromagnetic torque control and harmonic current suppression before and after a fault.

4. The single-phase circuit-breaking self-fault-tolerant power distribution control method for dual three-phase permanent magnet synchronous motors according to claim 2, characterized in that, The positive sequence xy subspace current controller is a quasi-proportional resonant controller with three resonant points: 3 times the fundamental frequency, 5 times the fundamental frequency, and 7 times the fundamental frequency. The feedback current of the corresponding controller is the current after the actual current of the positive sequence xy subspace is processed by the fundamental notch filter, thereby realizing the suppression of harmonic current before and after the fault and the fault-tolerant operation after the fault.

5. The single-phase circuit-breaking self-fault-tolerant power distribution control method for a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that, The negative sequence xy subspace current controller is a quasi-proportional resonant controller with four resonant points: 1, 3, 5, and 7 times the fundamental frequency, thereby realizing power distribution operation and harmonic current suppression before and after a fault.

6. The single-phase circuit-breaking self-fault-tolerant power distribution control method for a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that, By rationally configuring the reference currents of the dq subspace, positive sequence xy subspace, and negative sequence xy subspace, and by coordinating the control of the actual currents of each subspace, self-fault tolerance without fault diagnosis can be achieved for any single-phase open-circuit fault that occurs under power distribution, thereby improving reliability.

7. The single-phase circuit-breaking self-fault-tolerant power distribution control method for a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that, By rationally configuring the reference currents of the dq subspace, positive sequence xy subspace, and negative sequence xy subspace, and by coordinating the control of the actual currents of each subspace, the average power of the two sub-three phases of the motor can be automatically ensured to be the same as before the fault after any single-phase open circuit fault, that is, the power distribution is not affected by the phase failure fault.

8. The single-phase circuit-breaking self-fault-tolerant power distribution control method for a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that, By rationally configuring the reference currents of the dq subspace, positive sequence xy subspace, and negative sequence xy subspace, and by coordinating the control of the actual currents of each subspace, the motor can operate at the minimum copper loss state achievable under the corresponding working conditions before and after phase loss under any power distribution conditions, thereby improving energy efficiency.

9. The single-phase circuit-breaking self-fault-tolerant power distribution control method for a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that, By rationally configuring the reference currents of the dq subspace, positive sequence xy subspace, and negative sequence xy subspace, and by coordinating the control of the actual currents of each subspace, phase loss fault tolerance can be achieved without reconfiguring the controller or adjusting the reference current, thereby simplifying the control process.

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