Permanent magnet fault-tolerant vernier rim motor fault-tolerant control method based on non-dimensionality-reduction decoupling

Abstract

The invention discloses a permanent magnet fault-tolerant vernier rim motor fault-tolerant control method based on non-dimensionality reduction decoupling, and the method comprises the steps: setting a six-phase permanent magnet fault-tolerant vernier rim propulsion motor to be in double-Y 30-degree distribution, and driving the motor through six independent H-bridge inverters, and performing fault-tolerant control on the motor by adopting a maximum torque control method under different fault conditions: when the motor has a one-phase open-circuit fault, a two-phase open-circuit fault and a one-phase short-circuit fault, performing fault-tolerant control by adopting a current vector compensation method, and a maximum torque control method is adopted to select partial reference current of the fault-free phase to compensate the reference current of the fault phase, and a current compensation equation is changed in different fault states. According to the method, the maximum output torque after the fault-tolerant control strategy is used is ensured, and when the motor has a multi-phase fault, the fault phase is compensated by using the healthy phase.

Description

Technical Field

[0001] The invention relates to the field of motor control, and in particular to a permanent magnet fault-tolerant vernier rim motor fault-tolerant control method based on non-dimensionality reduction decoupling. Background Art

[0002] Rim thruster is a new type of electric propulsion, where the stator of the motor is directly connected to the hull, while the rotor is integrated with the propeller blades. Using a permanent magnet fault-tolerant vernier motor as the built-in motor can improve the torque density, propulsion efficiency and reliability of the electric propulsion system.

[0003] Permanent magnet fault-tolerant vernier rim thruster motor (FTPMV-RDM) is a combination of a vernier motor and a rim thruster. Due to the high torque density, strong fault tolerance and more flexible control freedom of FTPMV-RDM under low-speed operation, it has broad application prospects in ships with high requirements for reliability and torque density of electric propulsion systems.

[0004] When a FTPMV-RDM fails, on the one hand, the motor output torque will decrease, resulting in reduced thrust or complete failure; on the other hand, the motor output torque pulsation increases, resulting in increased vibration of the electric propulsion system, affecting the stability and safety of the ship's navigation. Therefore, the fault-tolerant control strategy proposed when the motor fails is very important.

[0005] The currently commonly used fault-tolerant control strategy based on reduced-order decoupling requires the establishment of a reduced-dimensional decoupling mathematical model after a fault. The corresponding decoupling transformation matrix is ​​also different and needs to be switched under different fault conditions, making the implementation of the fault-tolerant control strategy more complicated. Therefore, how to increase the output torque and reduce the torque pulsation while using the same decoupling transformation in normal system operation and fault operation is also an urgent problem to be solved. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention discloses a permanent magnet fault-tolerant vernier rim motor fault-tolerant control method based on non-dimensionality reduction decoupling, which specifically includes the following steps:

[0007] The six-phase FTPMV-RDM is taken as the control object. The motor is double Y 30° distributed and driven by six independent H-bridge inverters. The maximum torque control method is used to perform fault-tolerant control on the six-phase FTPMV-RDM under different fault conditions.

[0008] When the motor has a one-phase open circuit fault, a two-phase open circuit fault and a one-phase short circuit fault, fault-tolerant control is performed based on the voltage equation, flux equation and torque equation of the motor, using the space vector decoupling transformation matrix in the normal state and the current vector compensation method, and the maximum torque control method is used to select the reference current of some fault-free phases to compensate the reference current of the faulty phase, and the current compensation equation is changed under different fault states;

[0009] Since the six-phase FTPMV-RDM has no neutral point connection, the six-phase currents in the fault-tolerant control under different fault conditions must meet the following constraints:

[0010] i A +i U +i B +i V +i C +i W =0.

[0011] Furthermore, when a one-phase open circuit fault occurs in the motor, the current of phase A becomes 0, and the current of phase A is compensated by injecting current into the healthy phases U and V. According to the current vector diagram and constraints under the one-phase open circuit fault state, the current of each phase after compensation is obtained according to the maximum torque control method:

[0012]

[0013] Furthermore, when a two-phase open circuit fault occurs in the motor, the currents of phase A and phase W become 0. The current vector fault-tolerant control strategy is adopted, and the current vectors of the remaining fault-free phases U, V, B, and C are used to compensate the currents of phase A and phase W. According to the current vector diagram and constraints under the two-phase open circuit fault state, the current of each phase after compensation is obtained according to the maximum torque control method:

[0014]

[0015] Furthermore, when a short circuit occurs in one phase of the motor, the original current of phase A becomes a short-circuit current i SA , using the fault-tolerant strategy for a single-phase short-circuit fault, using the healthy U-phase and V-phase reference currents to compensate and eliminate the adverse effects of the single-phase short-circuit current, thereby obtaining the reference current after fault tolerance. According to the current vector diagram and constraints under the single-phase short-circuit fault state, the reference current of each phase after compensation is obtained:

[0016]

[0017] Due to the adoption of the above technical scheme, the present invention provides a fault-tolerant control method for a permanent magnet fault-tolerant vernier rim motor based on non-dimensionality reduction decoupling. The method utilizes the structural characteristics of the stator of the FTPMV-RDM as a six-phase isolated winding, and each phase winding is powered by a separate H-bridge drive circuit. The same decoupling transformation is used during normal operation and fault operation of the system, and the fault-tolerant control strategy is simplified. At the same time, a maximum torque control method is added to the fault-tolerant method. Compared with the existing methods, the fault-tolerant control method continues to use the decoupling transformation matrix in the normal state when the motor has a one-phase open circuit, two-phase open circuit, and one-phase short circuit fault. Its voltage equation, flux equation, and torque equation are not affected, and it also ensures that the output torque is maximized after using the fault-tolerant control strategy. When a multi-phase fault occurs in the motor, the healthy phase relative to the fault phase can be used for compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 The permanent magnet fault-tolerant cursor rim propulsion motor and its drive system topology in the present invention

[0020] Figure 2 The six-phase stationary coordinate system, two-phase stationary coordinate system and two-phase rotating coordinate system of the permanent magnet fault-tolerant vernier rim propulsion motor in the present invention are shown in FIG.

[0021] Figure 3 The topological structure of the drive system of the permanent magnet fault-tolerant vernier rim propulsion motor in the present invention under the condition of one-phase open circuit fault

[0022] Figure 4 The topological structure of the drive system of the permanent magnet fault-tolerant vernier rim propulsion motor in the present invention under the two-phase open circuit fault state

[0023] Figure 5 The topological structure of the drive system of the permanent magnet fault-tolerant vernier rim propulsion motor in the present invention under the condition of one-phase short circuit fault

[0024] Figure 6 The current vector diagram of the permanent magnet fault-tolerant vernier rim propulsion motor in the present invention under the condition of one-phase open circuit fault

[0025] Figure 7 The current vector diagram of the permanent magnet fault-tolerant vernier rim propulsion motor in the present invention under the two-phase open circuit fault state

[0026] Figure 8The current vector diagram of the permanent magnet fault-tolerant vernier rim propulsion motor in the present invention under the condition of one-phase short circuit fault

[0027] Fig. 9 The control block diagram of the model predictive control system of the permanent magnet fault-tolerant cursor rim propulsion motor of the present invention using the fault-tolerant control strategy

[0028] Fig.10 The torque, speed and current waveforms of the permanent magnet fault-tolerant cursor rim propulsion motor in the present invention during normal operation

[0029] Fig.11 The torque, speed and current waveforms of the permanent magnet fault-tolerant vernier rim propulsion motor of the present invention when one phase is open circuit fault

[0030] Fig.12 The torque, speed and current waveforms of the permanent magnet fault-tolerant vernier rim propulsion motor of the present invention when two phases are open circuit fault

[0031] Fig.13 The torque, speed and current waveforms of the permanent magnet fault-tolerant vernier rim propulsion motor of the present invention when one phase is short-circuited during operation DETAILED DESCRIPTION

[0032] In order to make the technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0033] like Figure 1 The figure shows the topological structure of the H-bridge inverter of the surface-mounted permanent magnet fault-tolerant vernier rim propulsion motor. The stator has two sets of windings, each set of windings is 30° apart in space, and the stator adopts a single-layer independent concentrated winding. Adjacent phase windings are separated by isolation teeth and arranged according to A, U, B, V, C, and W. Each phase of the motor is driven by an independent H-bridge inverter circuit, thus achieving physical isolation, magnetic isolation, thermal isolation, and electrical isolation between the phases. Figure 2 The following are the six-phase stationary coordinate system, two-phase stationary coordinate system and two-phase rotating coordinate system diagrams of the surface-mounted permanent magnet fault-tolerant vernier rim propulsion motor; Figure 3 , 4 , 5 is the topological structure of the drive system of the permanent magnet fault-tolerant vernier rim propulsion motor under different fault conditions; Figure 6 , 7 8 is the current vector diagram of the permanent magnet fault-tolerant vernier rim propulsion motor under different fault conditions; Fig. 9 This is the control block diagram of the model predictive control system of the permanent magnet fault-tolerant vernier rim propulsion motor using this fault-tolerant control strategy, where FT represents the operating state of the motor, FT=0 means normal operation; FT=1 means a single-phase open circuit fault; FT=2 means a two-phase open circuit fault; and FT=3 means a single-phase short circuit fault.

[0034] When the six-phase permanent magnet fault-tolerant vernier rim propulsion motor is operating normally, the instantaneous value of each phase electromotive force is

[0035]

[0036] Among them, k e is the back electromotive force, θ e is the electrical angle of the motor rotor. To obtain the maximum output electromagnetic torque, the current of each phase of the motor should be synchronized with the back electromotive force, so the instantaneous value of the current of each phase is

[0037]

[0038] Since the phases of the six-phase permanent magnet fault-tolerant vernier rim propulsion motor are independent of each other, without considering the cogging torque pulsation, the output torque T o It can be expressed as

[0039]

[0040] According to the definition of copper loss, the instantaneous copper loss of the six-phase permanent magnet fault-tolerant vernier rim propulsion motor is:

[0041]

[0042] In order to measure the motor performance and efficiency, the peak-to-peak torque ripple and average relative copper loss are defined as

[0043]

[0044]

[0045] Among them, T max 、T min are the maximum and minimum output torque of the motor respectively; P cuo is the copper consumption of the system when there is no fault, is the average instantaneous copper loss.

[0046] When a motor fails, the fault-tolerant control method includes the following steps:

[0047] When one phase (phase A) of the motor has an open circuit fault, the current of phase A becomes 0. If no fault-tolerant control strategy is adopted, the instantaneous output torque and instantaneous copper loss are

[0048]

[0049] At this time, the peak-to-peak torque pulsation T ripple =20%, average relative copper consumption P CuR =0.83.

[0050] Using this fault-tolerant control strategy, assuming that the reference current after compensation is:

[0051]

[0052] According to the current vector and constraint conditions under one-phase open circuit fault state, the motor is controlled to be fault-tolerant according to the maximum torque control mode. The reference current after compensation of each phase can be obtained by solving the equations.

[0053]

[0054] Substituting (9) into (10), we can obtain σ1 = 0.577, σ2 = -0.577. The reference current after compensation is finally obtained as:

[0055]

[0056] The instantaneous output torque and instantaneous copper loss after adopting the fault-tolerant control strategy are calculated by (11):

[0057]

[0058] At this time, the output torque is maximum and the peak-to-peak torque pulsation T ripple =0, average relative copper loss P CuR =1.28.

[0059] According to the coordinate transformation formula and the d-axis and q-axis current calculation formulas:

[0060]

[0061] Finally, the q-axis current given value is obtained.

[0062] Similarly, when a two-phase (A phase and W phase) open circuit fault occurs in the motor, the current of phase A and phase W becomes 0. If no fault-tolerant control strategy is adopted, the instantaneous output torque and instantaneous copper loss are

[0063]

[0064] At this time, the peak-to-peak torque pulsation T ripple =50%, average relative copper consumption P CuR =0.67.

[0065] With this fault-tolerant control strategy, the healthy phases U and V compensate for the A phase, and the healthy phases B and C compensate for the W phase. Therefore, the reference current after compensation is:

[0066]

[0067] The instantaneous output torque and instantaneous copper loss after adopting the fault-tolerant control strategy are calculated by (19):

[0068]

[0069] At this time, the output torque is maximum and the peak-to-peak torque pulsation T ripple =28.3%, average relative copper loss P CuR =1.22.

[0070] Then, according to the coordinate transformation formulas (14) and (15) and the d-axis and q-axis current calculation formula (16), the q-axis current given value is finally obtained.

[0071] When a phase short circuit occurs in the motor, the current after compensation is assumed to be:

[0072]

[0073] According to the six-phase current constraint conditions and the current vector diagram under the one-phase short-circuit fault state, it can be known that the current after compensation satisfies

[0074]

[0075] Substituting (8) into (9) yields μ1 = -0.577, μ2 = 0.577. Therefore, the current after compensation is:

[0076]

[0077] Then, according to the coordinate transformation formulas (14) and (15) and the d-axis and q-axis current calculation formula (16), the q-axis current given value is finally obtained.

[0078] The rotor position θ of the permanent magnet fault-tolerant motor is obtained by the sensor. The motor speed n can be obtained by calculating the rotor position signal. The given speed n is subtracted from the current speed n of the motor and processed by the PI regulator to obtain the motor's q-axis current given value. Will Input to the module that controls the motor. When the motor fails, the above fault-tolerant control strategy takes effect and outputs the compensated current

[0079]

[0080] Next, we conduct simulation experiments to verify the normal operation of the motor. The motor speed is 300r / min and the load torque is 15N·m. Fig.10 The following are the torque, speed and current waveforms of the motor when it is operating normally. Then, the motor is simulated and verified under the same simulation conditions when it fails. One-phase open circuit failure: The motor has an open circuit failure in phase A at 0.5s. The fault-tolerant control strategy is added at 0.55s. Fig.11 The following are the torque, speed and current waveforms when a single-phase open circuit fault occurs in the motor. Fig.11It shows that when the fault occurs, the torque does not decrease, but the torque pulsation increases, the current of phase A is 0, and the currents of phases B and C increase; after adopting the fault-tolerant control method, the torque pulsation decreases, and the currents of phases B and C decrease. A and W two-phase open circuit fault: The motor has an open circuit fault in phases A and W at 0.5s, and the fault-tolerant control strategy is added at 0.55s. Fig.12 Shown are the torque, speed and current waveforms when a two-phase open circuit fault occurs in the motor. Fig.12 It shows that when the fault occurs, the torque does not decrease, but the torque pulsation increases more obviously, the current of phases A and W is 0, and the current of phases B, C, U and V increases; after adopting the fault-tolerant control method, the torque pulsation decreases, and the current of phases B, C, U and V decreases. One-phase short-circuit fault: The motor has a short-circuit fault in phase A at 0.5s, and the fault-tolerant control strategy is added at 0.55s. Fig.13 The following are the torque, speed and current waveforms when a single-phase short circuit occurs in the motor.

[0081] Fig.13 It shows that when a fault occurs, the torque pulsation increases sharply, the current of phase A becomes a short-circuit current, and the currents of phases B and C increase; after adopting the fault-tolerant control method, the torque pulsation decreases. The simulation results show that the permanent magnet fault-tolerant vernier rim propulsion motor can complete rapid startup and stable operation in the normal state. At the same time, the motor can still maintain the stability of torque and speed when one phase, two phases are open circuit and one phase is short circuited by adopting the fault-tolerant control strategy, which proves that the fault-tolerant control strategy greatly improves the stability of the electric propulsion system with the permanent magnet fault-tolerant vernier rim propulsion motor as the core.

[0082] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fault-tolerant control method for a permanent magnet fault-tolerant vernier rim motor based on non-dimensionality reduction decoupling, characterized in that include: The six-phase permanent magnet fault-tolerant vernier rim propulsion motor is set to double Y 30° distribution, and six independent H-bridge inverters are used to drive the motor. The maximum torque control method is used to perform fault-tolerant control of the motor under different fault conditions: When the motor has a one-phase open circuit fault, a two-phase open circuit fault and a one-phase short circuit fault, fault-tolerant control is performed based on the voltage equation, flux equation and torque equation of the motor, using the space vector decoupling transformation matrix in the normal state and the current vector compensation method, and the maximum torque control method is used to select the reference current of some fault-free phases to compensate the reference current of the faulty phase, and the current compensation equation is changed under different fault states; Since the six-phase permanent magnet fault-tolerant vernier rim propulsion motor has no neutral point connection, the six-phase currents in the fault-tolerant control under different fault conditions must meet the following constraints: i A +i U +i B +i V +i C +i W =0。 2. The permanent magnet fault-tolerant vernier rim motor fault-tolerant control method based on non-dimensionality reduction decoupling according to claim 1 is characterized in that: When a single-phase open-circuit fault occurs in the motor, the current of phase A becomes 0. The current of phase A is compensated by injecting current into the healthy phases U and V. According to the current vector diagram and constraints under the single-phase open-circuit fault state, the current of each phase after compensation is obtained according to the maximum torque control method:

3. The permanent magnet fault-tolerant vernier rim motor fault-tolerant control method based on non-dimensionality reduction decoupling according to claim 1 is characterized in that: When a two-phase open circuit fault occurs in the motor, the currents of phase A and phase W become 0. The current vector fault-tolerant control strategy is adopted, and the current vectors of the remaining fault-free phases U, V, B, and C are used to compensate the currents of phase A and phase W. According to the current vector diagram and constraints under the two-phase open circuit fault state, the current of each phase after compensation is obtained according to the maximum torque control method:

4. The permanent magnet fault-tolerant vernier rim motor fault-tolerant control method based on non-dimensionality reduction decoupling according to claim 1 is characterized in that: When a phase short circuit occurs in the motor, the original current of phase A becomes the short circuit current i SA , using the fault-tolerant strategy for a single-phase short-circuit fault, using the healthy U-phase and V-phase reference currents to compensate and eliminate the adverse effects of the single-phase short-circuit current, thereby obtaining the reference current after fault tolerance. According to the current vector diagram and constraints under the single-phase short-circuit fault state, the reference current of each phase after compensation is obtained:

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