Multi-mode switching dual three-phase motor open-phase fault self-healing fault-tolerant control method

Abstract

The invention discloses a multi-mode switching dual three-phase motor open-phase fault self-healing fault-tolerant control method, and belongs to the technical field of motor control. The fault-tolerant control method comprises the steps that six-phase variables are mapped to different planes, the current of a fundamental wave plane is adjusted through a PI controller, a bidirectional PI controller is adopted to restrain harmonic current, a cascaded wave trap is utilized to enable fundamental frequency components to circulate, and the fundamental frequency components are output to a voltage source inverter through SVPWM to achieve control over a motor. After a fault-tolerant state is entered, stator copper loss and torque output capability of the motor are comprehensively considered, and an optimal operation mode can be automatically switched according to a load condition. The method has the characteristics of no need of fault positioning and consistent control architecture, current reference does not need to be changed through additional operation in the control process, secondary faults caused by wrong reference are avoided, the complexity of control implementation is simplified, the problems of delay and errors in the fault positioning process can be eliminated, and the fault positioning accuracy is improved. And stable operation of the motor can be maintained before and after the open-phase fault.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method. Background Art

[0002] Most of the existing fault-tolerant control methods for dual three-phase motors rely on an accurate fault location process, that is, first locate the faulty phase and then switch the corresponding current reference value. However, this method has several significant disadvantages. First, the positioning process takes a certain amount of time, which may lead to a decrease in the transient performance of the system. Especially in applications with high dynamic requirements, delays may cause the system to fail to respond quickly. In addition, the positioning process depends on the accuracy of sensors and algorithms, and is easily affected by motor parameter fluctuations and external noise, which can cause judgment errors. This error will lead to incorrect current reference value settings, thereby increasing torque pulsation and may even cause the system to lose control, affecting the safety and reliability of the equipment.

[0003] Traditional fault-tolerant control schemes are still very complex, especially when the current reference value needs to be adjusted dynamically according to the fault phase. Incorrect current reference will cause secondary faults. Since dual three-phase motors have more windings, their control architecture and reference signal adjustment are more complicated than traditional three-phase motors. This complexity not only increases the difficulty of implementing the control system, but also increases the cost of design and maintenance. In actual industrial applications, this complex fault location and adjustment process may lead to higher maintenance requirements and system downtime, which in turn affects production efficiency.

[0004] In response to these problems, the current dual three-phase motor control technology urgently needs a fault-tolerant control method that can exempt the fault location process to improve the reliability of the system, avoid the complex adjustment of the control architecture, and ensure that the motor can run stably and continuously when a fault occurs. At the same time, in order to adapt to the needs of multiple load conditions, it should have the ability to switch modes. The present invention proposes a multi-mode switching dual three-phase motor phase-loss fault self-healing fault-tolerant control method to solve the above problems. The method maintains a consistent control architecture before and after the fault. Without changing the current reference, the motor can transition to a fault-tolerant state to achieve self-healing of the fault, eliminating the need for fault location and reference switching, thereby simplifying the control process, reducing the difficulty of system implementation, and significantly improving the fault-tolerant performance and stability. The method is applicable to a variety of operating modes, comprehensively considering the stator copper loss and torque output capacity of the motor. Compared with traditional methods, better fault-tolerant performance can be achieved within a wide load range. Summary of the invention

[0005] In view of the deficiencies of the prior art in the above-mentioned background technology, the present invention provides a multi-mode switching dual three-phase motor phase-loss fault self-healing fault-tolerant control method, which can achieve effective fault tolerance and self-healing without changing the control architecture and current reference value when a phase-loss fault occurs, and without locating the faulty phase, thereby ensuring continuous and stable operation of the motor. During operation, the fault-tolerant mode of the motor can be switched in real time according to different load torques, thereby ensuring optimal fault-tolerant performance when the motor operates within a wide load range.

[0006] The technical solutions to achieve the purpose of the present invention are as follows:

[0007] A multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method comprises the following steps:

[0008] Step S1, constructing a mathematical model based on the vector space decoupling theory, mapping the six-phase variables in the natural stationary coordinate system to the dq fundamental plane, the z1-z2 harmonic plane and the o1-o2 zero-sequence plane through decoupling transformation;

[0009] Step S2: For the fundamental wave plane, set the reference speed n * The current reference value i of the q-axis is calculated by the PI controller by subtracting the actual speed n collected by the rotary encoder. q * , set the d-axis current reference value i d * is 0; for the harmonic plane, always let the harmonic plane current reference value i z * 1.i z * 2 is 0, no adjustment is required during the control process; the zero-sequence plane does not need to be controlled, and the overall current control dimension of the system is 4-dimensional;

[0010] Step S3: After a phase failure occurs, z * 1.i z * 2 and harmonic plane current i z1 、i z2 After making the difference, the harmonic plane current is suppressed through the bidirectional PI controller;

[0011] Step S4, connecting a notch filter in series to the output end of the bidirectional PI controller to allow the fundamental wave component during fault-tolerant operation to pass through;

[0012] Step S5, using bilinear transformation to discretize the transfer function of the notch filter for digital control program implementation;

[0013] Step S6: Current loop output plane reference voltage u of fundamental wave plane and harmonic wave plane d * 、uq * 、u z * 1.u z * 2. The reference voltage is decoupled and inversely transformed in the vector space to obtain the reference voltage u in the natural stationary coordinate system A * 、u B * 、u C * 、u D * 、u E * 、u F * , and then obtain the duty cycle required by each phase switch tube through SVPWM, and output it to the voltage source inverter to realize motor control; the SVPWM is space vector pulse width modulation;

[0014] Step S7: During normal operation, i z1 、i z2 It fluctuates slightly around 0; after entering the fault-tolerant state, the motor runs in the stator copper loss minimum mode by default, i z1 、i z2 No longer 0;

[0015] Step S8: The motor is in a fault-tolerant state, and the torque derating factor K is detected in real time. T Switching operation mode, including stator copper loss minimum mode and maximum torque output mode; the torque derating factor K T Equal to the actual load torque divided by the rated torque;

[0016] Step S9: When the torque derating factor K T When a certain threshold is exceeded, the motor is shut down to prevent overheating and damage.

[0017] Furthermore, in step S1, the decoupling transformation is implemented by a decoupling transformation matrix, as follows:

[0018]

[0019] Where x represents the motor variable, θ e is the stator electrical angle; the motor variables include voltage, current, and flux.

[0020] Furthermore, in step S4, the transfer function of the notch filter is:

[0021]

[0022] where ω eis the resonant angular frequency, set it to the fundamental angular frequency, k b is the adjustment coefficient related to bandwidth;

[0023] Furthermore, in step S5, the expression of the transfer function of the notch filter after discretization by bilinear transformation in the z domain is as follows:

[0024]

[0025] The coefficients in the formula are as follows:

[0026]

[0027] Among them, T s is the sampling period of the controller.

[0028] Furthermore, in step S7, a flag F is constructed. n Used to mark whether the motor has entered the fault-tolerant state and to indicate subsequent mode switching. n The expression is as follows:

[0029]

[0030] Where T is the fundamental period of the phase current, and the threshold is set. When F n When it is greater than 1.5, it is considered that the motor has entered the fault-tolerant state.

[0031] Furthermore, in step S8, the standard of the motor operation mode is: when K T When K is less than or equal to 0.555, the motor runs in the minimum stator copper loss mode; T When it is greater than 0.555 and less than or equal to 0.577, the motor runs in the maximum torque output mode; when the motor is in the fault-tolerant state, it runs in the minimum stator copper loss mode by default. T When it is less than or equal to 0.555, no additional operation is required; when K T When it is greater than 0.555 and less than or equal to 0.577, the amplitude of the phase current is detected, and the phase with unchanged amplitude before and after fault tolerance is disconnected through a circuit breaker or the drive signal is closed, and the motor is switched to the maximum torque output mode.

[0032] Furthermore, in step S9, the torque derating factor K of the shutdown process T The threshold is set to 0.577.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention proposes a multi-mode switching dual three-phase motor phase-loss fault self-healing fault-tolerant control method. Compared with the traditional scheme, this method does not require fault location and avoids negative problems such as increased torque pulsation caused by positioning delay and misalignment.

[0035] (2) The fault-tolerant control method proposed in the present invention adopts a unified control architecture before and after fault tolerance, and there is no need to repeatedly switch the current reference value according to the different fault phases. This simplifies the complexity of control implementation, realizes fault self-healing, saves control resources, and avoids secondary faults caused by erroneous references.

[0036] (3) The fault-tolerant control method proposed in the present invention can switch between the stator copper loss minimum mode and the maximum torque output mode according to different load conditions, thereby ensuring better fault-tolerant performance within a wide load range. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a block diagram of the self-healing fault-tolerant control system for dual three-phase motors with phase loss faults proposed by the present invention;

[0038] Figure 2 This is a dual three-phase motor drive topology diagram used in the present invention;

[0039] Figure 3 It is a control block diagram of the bidirectional PI controller proposed by the present invention;

[0040] Figure 4 The Bode diagram of the notch filter proposed by the present invention;

[0041] Figure 5 It is a schematic diagram of mode switching of the motor of the present invention in a fault-tolerant state;

[0042] Figure 6 The schematic diagram of mode switching of the motor of the present invention in a fault-tolerant state;

[0043] Figure 7 This is a six-phase current waveform diagram of the motor of the present invention in a stator copper loss minimum mode when the B phase is missing;

[0044] Figure 8 It is an experimental diagram of the dq axis current waveform, speed waveform, and harmonic plane current waveform when the motor B phase of the present invention is in the stator copper loss minimum mode;

[0045] Fig. 9 This is an experimental diagram of six-phase current waveforms in mode switching when the motor B phase is missing;

[0046] Fig.10 These are experimental diagrams of the dq-axis current waveform, speed waveform, and harmonic plane current waveform when the motor B phase is missing and in mode switching. DETAILED DESCRIPTION

[0047] The present invention is described below based on examples, but the present invention is not limited to these examples. In the detailed description of the present invention below, some specific details are described in detail. For those skilled in the art, the present invention can be fully understood without the description of these details.

[0048] A multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method comprises the following steps:

[0049] Step S1, construct a mathematical model based on the vector space decoupling theory, and map the six-phase variables in the natural stationary coordinate system to the dq fundamental plane, the z1-z2 harmonic plane and the o1-o2 zero-sequence plane through decoupling transformation.

[0050] Step S2: For the fundamental wave plane, set the reference speed n * The current reference value of the q-axis is obtained by subtracting the actual speed n calculated by the rotary encoder and passing through the PI controller. The d-axis current does not participate in the torque output, so the d-axis current reference value is Set to 0. For the harmonic plane, the control structure proposed by the present invention always sets the harmonic plane current reference value to The current reference value is 0, and there is no need to additionally locate the fault phase to switch to a different current reference value. Due to the neutral point isolation, the zero-sequence plane does not need to be controlled, and the overall current control dimension of the system is 4-dimensional.

[0051] Step S3: After a phase failure occurs, due to the additional introduction of negative sequence components, in order to improve the suppression effect and reduce the harmonic content in the phase current, and harmonic plane current i z1 、i z2 After making the difference, the harmonic plane current is suppressed through the bidirectional PI controller, such as Figure 2 The principle is to use the rotating coordinate transformation to convert the positive and negative sequence harmonic currents into DC quantities for control. Considering the low-order harmonic content after phase loss, k is set to 3, 5, 7, and multiple bidirectional PI controllers are used for parallel output.

[0052] Step S4: In order not to interfere with the necessary fundamental frequency components in the harmonic plane current during fault-tolerant operation, a notch filter is connected in series to the output end of the bidirectional PI controller to suppress low-order harmonics in the harmonic plane current during fault-tolerant operation.

[0053] Step S5: discretize the transfer function of the notch filter by using bilinear transformation for implementation of digital control program.

[0054] Step S6: Current loop output plane reference voltages of fundamental wave plane and harmonic wave plane The reference voltage is obtained by vector space decoupling and inverse transformation to obtain the reference voltage in the natural stationary coordinate system. Then, the duty cycle required by each phase switch is obtained through SVPWM and output to the voltage source inverter to realize motor control; the SVPWM is space vector pulse width modulation; the final system overall control block diagram is as follows Figure 4 shown.

[0055] Step S7: During normal operation, i z1 、i z2 It fluctuates slightly around 0; after entering the fault-tolerant state, the motor runs in the stator copper loss minimum mode by default, i z1 、i z2 No longer 0.

[0056] Step S8: The motor is in a fault-tolerant state, and the torque derating factor K is detected in real time. T Switching operation mode, including stator copper loss minimum mode and maximum torque output mode; the torque derating factor K T Equal to the actual load torque divided by the rated torque.

[0057] Step S9: When the torque derating factor K T When a certain threshold is exceeded, the output load exceeds the limit that the motor's fault-tolerant operation can withstand, and the motor is shut down to prevent overheating and damage.

[0058] Furthermore, in step S1, the decoupling transformation is implemented by a decoupling transformation matrix, as follows:

[0059]

[0060] Where x represents the motor variable, θ e is the stator electrical angle; the motor variables include voltage, current, and flux.

[0061] Furthermore, in step S4, the transfer function of the notch filter is:

[0062]

[0063] where ω e is the resonant angular frequency, set it to the fundamental angular frequency, k b is the adjustment coefficient related to bandwidth; take ω e is 50πrad / s, k b Take 1 as an example and draw the Bode diagram of the notch filter as follows: Figure 3 As shown, the gain of the trap is very small at the fundamental frequency component, and the harmonic plane current reference value is 0. In conjunction with the bidirectional PI controller, it can suppress low-order harmonics that produce additional losses, but will not affect the passage of the fundamental frequency component.

[0064] Furthermore, in step S5, the expression of the transfer function of the notch filter after discretization by bilinear transformation in the z domain is as follows:

[0065]

[0066] The coefficients in the formula are as follows:

[0067]

[0068] Among them, T s is the sampling period of the controller.

[0069] Furthermore, in step S7, a flag F is constructed. n Used to mark whether the motor has entered the fault-tolerant state and to indicate subsequent mode switching. n The expression is as follows:

[0070]

[0071] Where T is the fundamental period of the phase current, and the threshold is set. When F n When it is greater than 1.5, it is considered that the motor has entered the fault-tolerant state.

[0072] Furthermore, in step S8, the standard of the motor operation mode is: when K T When K is less than or equal to 0.555, the motor runs in the minimum stator copper loss mode, which can ensure the highest operating efficiency of the motor; T When it is greater than 0.555 and less than or equal to 0.577, the motor runs in the maximum torque output mode, which can ensure a stronger load capacity; when the motor is in the fault-tolerant state, it runs in the minimum stator copper loss mode by default. T When it is less than or equal to 0.555, no additional operation is required; when K T When it is greater than 0.555 and less than or equal to 0.577, the amplitude of the phase current is detected, and the phase with unchanged amplitude before and after fault tolerance is disconnected through the circuit breaker or the drive sealing signal is closed, and the motor is switched to the maximum torque output mode.

[0073] Furthermore, in step S9, the torque derating factor K of the shutdown process T The threshold is set to 0.577.

[0074] Furthermore, the experimental waveform of the embodiment is as follows Figures 7 to 10 As shown, the torque and speed of the motor can remain stable before and after fault tolerance, and effective fault tolerance can be achieved without additional changes to the current reference value, and mode switching can be achieved.

[0075] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned specific embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned specific embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method, characterized in that: The method comprises the following steps: Step S1, constructing a mathematical model based on the vector space decoupling theory, mapping the six-phase variables in the natural stationary coordinate system to the dq fundamental plane, the z1-z2 harmonic plane and the o1-o2 zero-sequence plane through decoupling transformation; Step S2: For the fundamental wave plane, set the reference speed n * The current reference value of the q-axis is calculated by the PI controller by subtracting the actual speed n collected by the rotary encoder. Set the d-axis current reference value is 0; for the harmonic plane, always set the harmonic plane current reference value is 0, and no adjustment is required during the control process; the zero-sequence plane does not need to be controlled, and the overall current control dimension of the system is 4-dimensional; Step S3: After a phase failure occurs, and harmonic plane current i z1 、i z2 After making the difference, the harmonic plane current is suppressed through the bidirectional PI controller; Step S4, connecting a notch filter in series to the output end of the bidirectional PI controller to allow the fundamental wave component during fault-tolerant operation to pass through; Step S5, using bilinear transformation to discretize the transfer function of the notch filter for digital control program implementation; Step S6: Current loop output plane reference voltages of fundamental wave plane and harmonic wave plane The reference voltage is obtained by vector space decoupling and inverse transformation to obtain the reference voltage in the natural stationary coordinate system. Then, the duty cycle required by each phase switch is obtained through SVPWM, and output to the voltage source inverter to realize motor control; the SVPWM is space vector pulse width modulation; Step S7: During normal operation, i z1 、i z2 It fluctuates slightly around 0; after entering the fault-tolerant state, the motor runs in the stator copper loss minimum mode by default, i z1 、i z2 No longer 0; Step S8: The motor is in a fault-tolerant state, and the torque derating factor K is detected in real time. T Switching operation mode, including stator copper loss minimum mode and maximum torque output mode; the torque derating factor K T Equal to the actual load torque divided by the rated torque; Step S9: When the torque derating factor K T When a certain threshold is exceeded, the motor is shut down to prevent overheating and damage.

2. A multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method according to claim 1, characterized in that: In step S1, the decoupling transformation is implemented by a decoupling transformation matrix, which is as follows: Where x represents the motor variable, θ e is the stator electrical angle; the motor variables include voltage, current, and flux.

3. The multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method according to claim 1 is characterized in that: In step S4, the transfer function of the notch filter is: where ω e is the resonant angular frequency, set it to the fundamental angular frequency, k b is the adjustment factor related to bandwidth.

4. The multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method according to claim 1 is characterized in that: In step S5, the expression of the transfer function of the notch filter after discretization by bilinear transformation in the z domain is as follows: The coefficients in the formula are as follows: Among them, T s is the sampling period of the controller.

5. The multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method according to claim 1 is characterized in that: In step S7, a flag F is constructed. n Used to mark whether the motor has entered the fault-tolerant state and to indicate subsequent mode switching. n The expression is as follows: Where T is the fundamental period of the phase current, and the threshold is set. n When it is greater than 1.5, it is considered that the motor has entered the fault-tolerant state.

6. A multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method according to claim 1, characterized in that: In step S8, the standard of the motor operation mode is: when K T When K is less than or equal to 0.555, the motor runs in the minimum stator copper loss mode; T When it is greater than 0.555 and less than or equal to 0.577, the motor runs in the maximum torque output mode; when the motor is in the fault-tolerant state, it runs in the minimum stator copper loss mode by default. T When it is less than or equal to 0.555, no additional operation is required; when K T When it is greater than 0.555 and less than or equal to 0.577, the amplitude of the phase current is detected, and the phase with unchanged amplitude before and after fault tolerance is disconnected through a circuit breaker or the drive signal is closed, and the motor is switched to the maximum torque output mode.

7. A multi-mode switching dual three-phase motor phase failure self-healing fault-tolerant control method according to claim 1, characterized in that: In step S9, the torque derating factor K of the shutdown process T The threshold is set to 0.577.

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