Independent bridge arm fault-tolerant control method for semi-centralized open-winding motor drive system

Abstract

The present invention discloses a fault-tolerant control method for an independent bridge arm of a semi-centralized open-winding motor drive system, and relates to the technical field of motor fault control. The present invention addresses an open-phase fault in an independent bridge arm of a semi-centralized open-winding inverter, and includes the following steps: calculating the thrust demand of the drive system; converting the thrust command into the dq-axis synchronous current command of the motor using a fundamental wave loss minimum allocation strategy; calculating the synchronous voltage demand command using a current regulator and transforming it to an abc coordinate system; and distributing the voltage command to the remaining bridge arms. The present invention can achieve single-bridge arm fault tolerance in a semi-centralized open-winding drive system. Compared to traditional fault-tolerant control strategies, the present invention can reduce system losses and maximum phase losses.

Description

Technical Field

[0001] The present invention relates to the technical field of motor fault control, and in particular to a method for fault-tolerant control of independent bridge arms of a semi-centralized open-winding motor drive system. Background Art

[0002] A semi-centralized open-winding system is a topology typically used for multiple three-phase motors. In this structure, each three-phase motor is powered by an independent inverter at one end and a shared inverter at the other. This structure offers some of the advantages of traditional open-winding motors, such as a wide speed regulation range and strong fault tolerance. It also reduces the use of switching devices, which can, to a certain extent, mitigate the adverse effects of open-winding topologies, such as high failure rates and high hardware costs. Although the inverter failure rate can be reduced to a certain extent in semi-centralized open-winding systems, open-circuit failures still exist. Therefore, the system needs to consider fault-tolerant control operation to improve the reliability of the drive system.

[0003] Currently, two main topologies are being studied for open-circuit faults in inverters: the open-winding structure and the three-phase four-bridge-arm structure. The fault-tolerant control strategies proposed for these two control structures are generally only applicable to single-motor structures. However, for the semi-centralized open-winding structure, the multi-motor system can have more control freedom, so the losses in the fault-tolerant operation condition can be reduced to a certain extent.

[0004] To this end, we propose a fault-tolerant control method for independent bridge arm faults in a semi-centralized open-winding motor drive system. Summary of the Invention

[0005] The object of the present invention is to provide a fault-tolerant control method for an independent bridge arm of a semi-centralized open-winding motor drive system, which can achieve fault tolerance of a single-phase open-circuit fault of the semi-centralized open-winding drive system and reduce system losses.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a fault-tolerant control method for independent bridge arms of a semi-centralized open-winding motor drive system, specifically as follows:

[0007] (1) Obtain the actual speed and reference speed of the motor during operation, and use the speed regulator to calculate the thrust requirement F* of the drive system, as follows:

[0008] F * =k pv (v * -v)+k iv ∫(v * -v)dt

[0009] Among them, v and v* are the reference speed and actual speed of the motor, k pv and kiv are the proportional-integral coefficients of the speed regulator respectively.

[0010] (2) Using the fundamental wave loss minimum allocation strategy, the calculated drive system thrust command is converted into the dq axis synchronous current command of the motor. The specific method is as follows:

[0011]

[0012] in, They are the dq0 axis synchronous current instructions of motor 1 respectively; are the dq0-axis synchronous current instructions of motor 2 respectively; θ1 is the electrical angle of motor 1; θ2 is the electrical angle of motor 2; Δθ is the angle difference between the two motors, Δθ=θ2-θ1; I m It can be calculated by the thrust command:

[0013]

[0014] Among them, τ s is the bipolar pitch of the motor, ψ f is the flux linkage of the motor's permanent magnets.

[0015] (3) Obtain the actual dq axis current of the motor and use the current regulator to calculate the synchronous voltage demand instruction, as follows:

[0016]

[0017]

[0018] in, is the dq axis voltage command of the two motors; k pd1 ,k id1 ,k pq1 ,k iq1 are the proportional coefficient and integral coefficient of the dq axis current regulator of motor 1 respectively; k pd2 ,k id2 ,k pq2 ,k iq2 are the proportional coefficient and integral coefficient of the dq axis current regulator of motor 2 respectively; i d1 ,i q1 ,i d2 ,i q2 is the actual dq axis current of the two motors.

[0019] The proportional resonant controller is used to calculate the zero-sequence current as follows:

[0020]

[0021] in is the zero-sequence voltage reference value calculated by the proportional resonant regulator at time k, k-1, k-2 e k ,e k-2 is the difference between 0 and zero sequence current at time k, k-2; T s is the computing cycle of the real-time processor; ω c is the proportional resonant frequency; ω0 is the electrical angular velocity of the motor; K s is the proportional resonance coefficient of the motor; the zero-sequence voltage reference value of the faulty motor 2 is 0.

[0022] (4) Transform the synchronous voltage demand instruction into the abc three-phase coordinate system. The specific method is as follows:

[0023]

[0024]

[0025] Where θ2 is the electrical angle of motor 2, are the symmetrical abc phase voltage instructions of the two motors.

[0026] (5) The actual voltage command of the motor is calculated based on the symmetrical abc phase voltage command. The specific method is as follows:

[0027]

[0028]

[0029] Among them, u a1 ,u b1 ,u c1 ,u a2 ,u b2 ,u c2 are the actual abc phase voltage instructions of the two motors.

[0030] (6) Allocate the actual voltage command to the remaining bridge arms. The specific method is as follows:

[0031]

[0032]

[0033]

[0034] Among them, δ a1 ,δ b1 ,δ c1 is the duty cycle of independent inverter 1; δ a2 ,δ b2 ,δ c2 is the duty cycle of the independent inverter 2; δap ,δ bp ,δ cp is the duty cycle of the shared inverter; u dc is the DC bus voltage.

[0035] The present invention has at least the following beneficial effects:

[0036] The present invention can realize open-circuit fault-tolerant control of independent bridge arm faults in a semi-centralized open-winding motor drive system. Compared with the existing open-winding fault-tolerant control method, the present invention can simultaneously reduce system loss and maximum phase loss, and improve torque output capacity.

[0037] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The three-phase currents of the two motors before and after the fault of the present invention;

[0039] Figure 2 is the dq axis current before and after the fault of the present invention;

[0040] Figure 3 is the thrust of the motor before and after the failure of the present invention;

[0041] Figure 4 The thrust and speed of the drive system before and after the failure of the present invention;

[0042] Figure 5 The phase loss comparison between the present invention and the traditional method is shown in FIG.

[0043] Figure 6 Comparison of system losses between the present invention and the traditional method;

[0044] Figure 7 This is the hardware connection topology diagram of the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0046] To verify the effectiveness of the present invention, two primary permanent magnet linear motors (Motor 1 and Motor 2) were selected to examine the open-circuit fault-tolerant control performance of the proposed control method's independent bridge arms. The parameters of these linear motors were: stator phase resistance 3Ω, stator synchronous inductance Ls = 33.5mH, and permanent magnet flux linkage 0.125Wb.

[0047] See also Figure 1-7 The present invention provides a technical solution: a fault-tolerant control method for an independent bridge arm of a semi-centralized open-winding motor drive system, specifically as follows:

[0048] 1. Obtain the actual speed and reference speed of the motor during operation, and use the speed regulator to calculate the thrust requirement F* of the drive system as follows:

[0049] F * =k pv (v * -v)+k iv ∫(v * -v)dt

[0050] Among them, v and v* are the reference speed and actual speed of the motor, k pv and k iv are the proportional-integral coefficients of the speed regulator respectively.

[0051] 2. Establish a dq coordinate system, define the direct axis of the motor as the d-axis and the quadrature axis as the q-axis, and convert the calculated thrust command of the drive system into the dq-axis synchronous current command of the motor as follows:

[0052]

[0053] in, They are the dq0 axis synchronous current instructions of motor 1 respectively; are the dq0-axis synchronous current instructions of motor 2 respectively; θ1 is the electrical angle of motor 1; θ2 is the electrical angle of motor 2; Δθ is the angle difference between the two motors, Δθ=θ2-θ1; I m It can be calculated by the thrust command:

[0054]

[0055] Among them, τ s is the bipolar pitch of the motor, ψ f is the flux linkage of the motor's permanent magnets.

[0056] 3. Obtain the actual dq axis current of the motor, then use the current regulator to calculate the synchronous voltage demand instruction, and then transform the synchronous voltage demand instruction into the abc three-phase coordinate system to obtain the symmetrical abc phase voltage instruction.

[0057] (1) Calculate the synchronous voltage demand instruction using the current regulator, as follows:

[0058]

[0059]

[0060] in, is the dq axis voltage command of the two motors; k pd1 ,k id1 ,k pq1 ,k iq1 are the proportional coefficient and integral coefficient of the dq axis current regulator of motor 1 respectively; k pd2 ,k id2 ,k pq2 ,k iq2 are the proportional coefficient and integral coefficient of the dq axis current regulator of motor 2 respectively; i d1 ,i q1 ,i d2 ,i q2 is the actual dq axis current of the two motors.

[0061] The proportional resonant controller is used to calculate the zero-sequence current as follows:

[0062]

[0063] in is the zero-sequence voltage reference value calculated by the proportional resonant regulator at time k, k-1, k-2 e k ,e k-2 is the difference between 0 and zero sequence current at time k, k-2; T s is the computing cycle of the real-time processor; ω c is the proportional resonant frequency; ω0 is the electrical angular velocity of the motor; K s is the proportional resonance coefficient of the motor; the zero-sequence voltage reference value of the faulty motor 2 is 0;

[0064] (2) Transform the synchronous voltage demand instruction into the abc three-phase coordinate system. The specific method is as follows:

[0065]

[0066]

[0067] Where θ2 is the electrical angle of motor 2, are the symmetrical abc phase voltage instructions of the two motors.

[0068] 4. The actual voltage command of the motor is calculated based on the symmetrical abc phase voltage command, and then the actual voltage command is distributed to the remaining bridge arms to achieve control.

[0069] (1) The actual voltage command of the motor is calculated based on the symmetrical abc phase voltage command. The specific method is as follows:

[0070]

[0071]

[0072] Among them, u a1 ,u b1 ,u c1 ,u a2 ,u b2 ,u c2 is the actual abc phase voltage command of the two motors;

[0073] (2) Allocate the actual voltage command to the remaining bridge arms. The specific method is as follows:

[0074]

[0075]

[0076]

[0077] Among them, δ a1 ,δ b1 ,δ c1 is the duty cycle of independent inverter 1; δ a2 ,δ b2 ,δ c2 is the duty cycle of the independent inverter 2; δ ap ,δ bp ,δ cp is the duty cycle of the shared inverter; u dc is the DC bus voltage.

[0078] according to Figure 1-7 It can be seen that the torque output of each motor is not in a constant state before and after the fault, but the torque of the motor drive system as a whole is constant. At the same time, compared with the traditional fault-tolerant control method, the present invention can effectively reduce the phase loss and maximum loss of the system.

[0079] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0080] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there can be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there can be a central element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0082] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Claims

1. A fault-tolerant control method for independent bridge arms of a semi-centralized open-winding motor drive system, characterized in that: The details are as follows: (1) Obtain the actual speed and reference speed of the motor during operation, and use the speed regulator to calculate the thrust requirement F* of the drive system, as follows: F * =k pv (in * -v)+k iv ∫(v * -v)dt Among them, v and v* are the reference speed and actual speed of the motor, k pv and k iv are the proportional-integral coefficients of the speed regulator respectively; (2) Using the fundamental wave loss minimum allocation strategy, the calculated drive system thrust command is converted into the dq axis synchronous current command of the motor. The specific method is as follows: in, They are the dq0 axis synchronous current instructions of motor 1 respectively; are the dq0-axis synchronous current instructions of motor 2 respectively; θ1 is the electrical angle of motor 1; θ2 is the electrical angle of motor 2; Δθ is the angle difference between the two motors, Δθ=θ2-θ1; I m It can be calculated by the thrust command: Among them, τ s is the bipolar pitch of the motor, ψ f is the flux linkage of the motor’s permanent magnet; (3) Obtain the actual dq axis current of the motor and use the current regulator to calculate the synchronous voltage demand instruction, as follows: in, is the dq axis voltage command of the two motors; k pd1 ,k id1 ,k pq1 ,k iq1 are the proportional coefficient and integral coefficient of the dq axis current regulator of motor 1 respectively; k pd2 ,k id2 ,k pq2 ,k iq2 are the proportional coefficient and integral coefficient of the dq axis current regulator of motor 2 respectively; i d1 ,i q1 ,i d2 ,i q2 is the actual dq axis current of the two motors; The proportional resonant controller is used to calculate the zero-sequence current as follows: in is the zero-sequence voltage reference value calculated by the proportional resonant regulator at time k, k-1, k-2 e k ,e k-2 is the difference between 0 and zero sequence current at time k, k-2; T s is the computing cycle of the real-time processor; ω c is the proportional resonant frequency; ω0 is the electrical angular velocity of the motor; K s is the proportional resonance coefficient of the motor; the zero-sequence voltage reference value of the faulty motor 2 is 0; (4) Transform the synchronous voltage demand instruction into the abc three-phase coordinate system. The specific method is as follows: Where θ2 is the electrical angle of motor 2, is the symmetrical abc phase voltage command of the two motors; (5) The actual voltage command of the motor is calculated based on the symmetrical abc phase voltage command. The specific method is as follows: Among them, u a1 ,u b1 ,u c1 ,u a2 ,u b2 ,u c2 is the actual abc phase voltage command of the two motors; (6) Allocate the actual voltage command to the remaining bridge arms. The specific method is as follows: Among them, δ a1 ,δ b1 ,δ c1 is the duty cycle of independent inverter 1; δ a2 ,δ b2 ,δ c2 is the duty cycle of the independent inverter 2; δ ap ,δ bp ,δ cp is the duty cycle of the shared inverter; u dc is the DC bus voltage.

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