A Fault Tolerant Control Method for the Common Leg of a Semi-Centralized Open-Winding Drive System

Abstract

The present invention belongs to the technical field of motor fault control, and discloses a fault-tolerant control method for a common bridge arm in a semi-centralized open winding drive system. This fault-tolerant control method is aimed at the open-phase fault of the common bridge arm of the inverter in the semi-centralized open winding. The fault-tolerant control method includes the following steps: calculating the thrust command of the motor using a speed regulator; converting the thrust command into the dq0-axis synchronous current command of the motor; calculating the dq0-axis synchronous voltage command of the motor using a current regulator in combination with the actual dq0-axis current of the motor, transforming the dq0-axis synchronous voltage command of the motor into the symmetric abc-phase voltage command in the abc three-phase coordinate system, and distributing the symmetric abc-phase voltage command to each inverter. The present invention can achieve fault tolerance for the open circuit of the common bridge arm in the semi-centralized open winding drive system. At the same time, compared with the traditional open circuit fault-tolerant control strategy, the present invention can reduce the system loss and phase loss and improve the torque output ability of the fault system.

Description

Technical Field

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

[0002] In an open winding drive system, the end windings of the motor are opened, and each end is connected to an inverter for power supply. Compared with the traditional motor drive structure, the open winding drive system has advantages such as a wide speed regulation range and strong fault tolerance. However, it faces problems such as a large number of switching devices and a high failure rate. Based on this, a semi-centralized open winding system is proposed. In this structure, one end of each three-phase motor is powered by an independent inverter respectively, and the other end is powered by a common inverter. This structure not only retains the advantages of the open winding structure but also can reduce the use of switching devices, and to a certain extent, reduces the adverse effects of high failure rate and high hardware cost brought by the open winding topology.

[0003] Compared with the open winding structure, although the semi-centralized open winding structure can reduce the failure rate of the inverter to a certain extent, there is still a problem of open circuit faults. Therefore, the system needs to consider fault-tolerant control operation to improve the reliability of the drive system. Currently, for the open circuit faults of the inverter, there are mainly two types of topological structures studied, namely the open winding structure and the three-phase four-leg structure. The fault-tolerant control strategies proposed for these two control structures usually only apply to single-motor structures. However, for the open circuit fault problem of the common bridge arm in the semi-centralized open winding system, there is no relevant literature for research.

[0004] Therefore, a fault-tolerant control method for a common bridge arm in a semi-centralized open winding drive system is proposed. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a fault-tolerant control method for a common bridge arm in a semi-centralized open winding drive system, which can achieve fault tolerance for open circuit faults of the common bridge arm in the semi-centralized open winding drive system and reduce the loss of the system.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A fault-tolerant control method for a common bridge arm in a semi-centralized open winding drive system includes the following steps:

[0008] (1) Using a speed regulator and combining the actual speed and the reference speed during the operation of the motor, calculate the thrust command of the motor as follows:

[0009] F * = k pv (v * - v) + k iv ∫(v* -v)dt

[0010] where v and v* are the reference speed and the actual speed of the motor, and k pv and k iv are the proportional-integral coefficients of the speed regulator respectively.

[0011] (2) Convert the thrust command of the motor to the dq0-axis synchronous current command of the motor in the following way:

[0012]

[0013] where are the dq0-axis synchronous current commands of motor 1 respectively; are the dq0-axis synchronous current commands 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 is the thrust equivalent current.

[0014] I m is calculated from the thrust command:

[0015]

[0016] where τ s is the pole pitch of the motor, and ψ f is the permanent magnet flux linkage of the motor.

[0017] (3) Based on the dq0-axis synchronous current commands of the motor, use the current regulator and combine with the actual dq0-axis current of the motor to calculate the dq0-axis synchronous voltage commands of the motor in the following way:

[0018]

[0019]

[0020] where R s is the phase resistance of the motor, L s is the synchronous inductance of the motor, L0 is the zero-sequence inductance of the motor, ω e is the electrical angular frequency of the motor, ψ f is the permanent magnet flux linkage of the motor, ψ 3f is the third-harmonic permanent magnet flux linkage of the motor; are the dq0-axis synchronous voltage commands of the two motors; i d1 、i q1 、i 01 、i d2 、i q2 、i 02 are the actual dq0-axis currents of the two motors.

[0021] (4) Transform the dq0-axis synchronous voltage command of the motor to the abc three-phase coordinate system to obtain the symmetric abc-phase voltage command. The specific method is as follows:

[0022]

[0023]

[0024] Among them, θ1 is the electrical angle of motor 1; θ2 is the electrical angle of motor 2, are the symmetric abc-phase voltage commands of the two motors.

[0025] (5) Allocate the symmetric abc-phase voltage command to each inverter to achieve control. The specific allocation method is as follows:

[0026]

[0027]

[0028]

[0029] Among them, δ a1 、δ b1 、δ c1 are the duty cycles of the independent inverter 1; δ a2 、δ b2 、δ c2 are the duty cycles of the independent inverter 2; δ ap 、δ bp 、δ cp are the duty cycles of the shared inverter; u dc is the DC bus voltage.

[0030] Advantages of the present invention:

[0031] The method of the present invention can achieve open-circuit fault tolerance control for the common bridge arm fault of the semi-concentrated open winding motor drive system. Compared with the existing open winding fault tolerance control methods, the present invention can reduce both the system loss and the maximum phase loss, and improve the torque output ability. Description of the drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0033] Figure 1 is the topology diagram of the semi-concentrated open winding system in the embodiment of the present invention;

[0034] Figure 2 It is the three-phase current comparison diagram of two motors before and after the fault in the embodiment of the present invention;

[0035] Figure 3 It is the dq0-axis current comparison diagram of two motors before and after the fault in the embodiment of the present invention;

[0036] Figure 4 It is the thrust comparison diagram of two motors before and after the fault in the embodiment of the present invention;

[0037] Figure 5 It is the thrust and speed comparison diagram of the drive system before and after the fault in the embodiment of the present invention;

[0038] Figure 6 It is the phase loss comparison diagram in the embodiment of the present invention;

[0039] Figure 7 It is the system loss comparison diagram in the embodiment of the present invention. Specific embodiments

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0041] In the description of the present invention, it should be understood that the terms "open hole", "upper", "lower", "thickness", "top", "middle", "length", "inner", "periphery", etc. indicating the orientation or position relationship are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0042] In order to verify the effect of the control method of the present invention, two primary permanent magnet linear motors (Motor 1 and Motor 2) are selected to verify the open-circuit fault tolerance control performance of the common bridge arm of the proposed control method.

[0043] The parameters of the two primary permanent magnet linear motors are the same, which are: stator phase resistance 3Ω, stator synchronous inductance Ls = 33.5mH, and permanent magnet flux linkage 0.125Wb.

[0044] A semi-centralized open-winding drive system common bridge arm fault tolerance control method described in the present invention specifically includes the following steps:

[0045] (1) Using a speed regulator and combining the actual speed and the reference speed during the operation of the motor, calculate the thrust command of the motor as follows:

[0046] F * = k pv (v * - v) + k iv ∫(v * - v)dt

[0047] where v and v* are the reference speed and the actual speed of the motor, and k pv and k iv are the proportional and integral coefficients of the speed regulator, respectively.

[0048] (2) Convert the thrust command of the motor to the dq0-axis synchronous current command of the motor in the following way:

[0049]

[0050] where, are the dq0-axis synchronous current commands of motor 1, respectively; are the dq0-axis synchronous current commands 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 is the thrust equivalent current.

[0051] I m can be calculated from the thrust command:

[0052]

[0053] where τ s is the pole pitch of the motor, and ψ f is the permanent magnet flux linkage of the motor.

[0054] (3) Based on the dq0-axis synchronous current command of the motor, use the current regulator and combine it with the actual dq0-axis current of the motor to calculate the dq0-axis synchronous voltage command of the motor in the following way:

[0055]

[0056]

[0057] where R s is the phase resistance of the motor, L s is the synchronous inductance of the motor, L0 is the zero-sequence inductance of the motor, ω e is the electrical angular frequency of the motor; ψ 3f is the third-harmonic permanent magnet flux linkage of the motor; are the dq0-axis synchronous voltage commands of the two motors; i d1 、i q1 、i 01 、id2 、 i q2 、 i 02 are the actual dq0-axis currents of the two motors.

[0058] (4) Transform the dq0-axis synchronous voltage commands of the motors into the abc three-phase coordinate system to obtain the symmetric abc-phase voltage commands. The specific method is as follows:

[0059]

[0060]

[0061] where θ1 is the electrical angle of motor 1; θ2 is the electrical angle of motor 2, are the symmetric abc-phase voltage commands of the two motors.

[0062] (5) Distribute the symmetric abc-phase voltage commands to each inverter to achieve control. The specific distribution method is as follows:

[0063]

[0064]

[0065]

[0066] where δ a1 、 δ b1 、 δ c1 are the duty cycles of the independent inverter 1; δ a2 、 δ b2 、 δ c2 are the duty cycles of the independent inverter 2; δ ap 、 δ bp 、 δ cp are the duty cycles of the shared inverter; u dc is the DC bus voltage.

[0067] According to Figure 2-7 it can be seen that the torque output of each motor before and after the fault is not in a constant state, but the torque of the overall motor drive system is constant. The present invention can achieve fault tolerance for the shared leg fault of the semi-centralized open winding motor drive system. At the same time, compared with the traditional fault tolerance control method, the present invention can effectively reduce the phase loss and the maximum loss of the system.

[0068] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0069] The above has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A fault-tolerant control method for a common bridge arm in a semi-centralized open winding drive system, characterized in that, Including the following steps: (1) Using a speed regulator and combining the actual speed and the reference speed during the operation of the motor, calculate the thrust command of the motor as follows: F * = k pv (v * - v) + k iv ∫(v * - v)dt where v and v* are the reference speed and the actual speed of the motor, and k pv and k iv are the proportional-integral coefficients of the speed regulator, respectively; (2) Convert the thrust command of the motor to the dq0-axis synchronous current command of the motor in the following manner: Among them, i*d1, i*q1, and i*01 are the dq0-axis synchronous current commands of motor 1 respectively; i*d2, i*q2, and i*02 are the dq0-axis synchronous current commands 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 is the thrust equivalent current; I m Calculated from the thrust command: Among them, τ s is the bipolar pitch of the motor, and ψ f is the magnetic flux linkage of the permanent magnet of the motor; (3) Based on the dq0-axis synchronous current command of the motor, use a current regulator and combine the actual dq0-axis current of the motor to calculate the dq0-axis synchronous voltage command of the motor in the following manner: wherein, R s is the phase resistance of the motor, L s is the synchronous inductance of the motor, L0 is the zero-sequence inductance of the motor, ω e is the electrical angular frequency of the motor, ψ f is the permanent magnet flux linkage of the motor, ψ 3f is the third harmonic permanent magnet flux linkage of the motor; u*d1, u*q1, u*01, u*d2, u*q2, u*02 are the dq0-axis synchronous voltage commands of the two motors; i d1 , i q1 , i 01 , i d2 , i q2 , i 02 are the actual dq0-axis currents of the two motors; (4) Transform the dq0-axis synchronous voltage command of the motor to the abc three-phase coordinate system to obtain the symmetric abc-phase voltage command in the following specific manner: where, θ1 is the electrical angle of motor 1; θ2 is the electrical angle of motor 2, and u*a1, u*b1, u*c1, u*a2, u*b2, u*c2 are the symmetric abc-phase voltage commands of the two motors; (5) Distribute the symmetric abc-phase voltage commands to each inverter to achieve control in the following specific distribution manner: Among them, δ a1 , δ b1 , δ c1 are the duty cycles of the independent inverter 1; δ a2 , δ b2 , δ c2 are the duty cycles of the independent inverter 2; δ ap , δ bp , δ cp are the duty cycles of the shared inverter; u dc is the DC bus voltage.

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