CN110838808A - Diagnosis-free self-healing method for open-circuit fault of dual-phase permanent magnet synchronous motor drive system - Google Patents

Abstract

The invention discloses a diagnosis-free self-repairing method for an open-circuit fault of a dual-phase permanent magnet synchronous motor drive system, relates to a motor fault diagnosis technology, and belongs to the technical field of measurement and testing. The diagnosis-free self-healing method proposed by the invention combines the advantages of PI control and deadbeat control, and by optimizing the reference value given by the harmonic current plane, the originally suppressed self-healing ability of the dual-phase motor drive system can be fully exerted , realizes high-performance fault-tolerant control, does not need to diagnose fault types in advance, is generally applicable to switch tube faults, motor single-phase open circuit and multi-phase open circuit faults, and fundamentally avoids long-term faults caused by misdiagnosis and time-consuming diagnosis. running problem. At the same time, the method does not need to modify the motor model, modulation strategy or control framework according to different fault categories, which reduces the complexity of control and minimizes the adverse effects of the fault-tolerant scheme itself.

Description

Diagnosis-free self-healing method for open-circuit fault of dual-phase permanent magnet synchronous motor drive system

technical field

The invention discloses a fault-free self-repair method for a dual-phase permanent magnet synchronous motor drive system, relates to a motor fault diagnosis technology, and belongs to the technical field of measurement and testing.

Background technique

In recent years, multiphase motor drive systems have attracted more and more attention in high-power, high-reliability applications such as aerospace, electric vehicles, and naval propulsion. Among all kinds of multi-phase motors, the dual-phase motor drive system has become a promising new drive system because it can eliminate the six-order torque ripple through the coordinated control of the two sets of windings. In systems with high reliability requirements, identifying any potential anomalies and faults as early as possible and implementing fault-tolerant control can maximize the preservation of the original operating performance of the motor drive system and avoid dangerous situations. The existing fault-tolerant control often has the following two problems: On the one hand, the traditional open-circuit fault-tolerant control strategy for multi-phase motors must modify the original motor model, modulation strategy or control framework according to the fault type, which makes the fault-tolerant control strategy change. It takes up a lot of computing resources, reduces the utilization rate of the DC bus voltage, and leads to the instability of the transient switching process of the system. On the other hand, the current fault detection methods often only focus on a single or several types of faults. But different kinds of faults may have the same fault characteristics, which are easy to be misdiagnosed and may cause more serious damage. At the same time, it takes a certain amount of time to diagnose faults, which leads to an inevitable delay in the introduction of fault-tolerant strategies, which may lead to long-term fault operation problems.

SUMMARY OF THE INVENTION

The purpose of the present invention is to address the shortcomings of the above-mentioned background technology, and to provide a fault-free self-repair method for a dual-phase permanent magnet synchronous motor drive system, which can quickly and accurately perform fault-tolerant control on motor open-circuit faults without diagnosing fault types. , to avoid the problem of long-term failure operation caused by misdiagnosis and time-consuming diagnosis. At the same time, there is no need to adjust the motor model, modulation strategy and control framework, which solves the technical problems of complex control schemes and time-consuming misdiagnosis and diagnosis of existing fault-tolerant control strategies for multi-phase motors.

The present invention adopts following technical scheme for realizing above-mentioned purpose of invention:

A dual-phase permanent magnet synchronous motor drive system open-circuit fault diagnosis-free self-repair method, the steps of which are as follows:

1) Collect the output signals of the motor speed sensor and the phase current sensor, and obtain the αβ axis and xy axis current components through the decoupling transformation module;

2) Obtain the amplitude and phase information of the xy-axis current at time k through the enhanced phase-locked loop module;

3) Considering the motor rotation and sampling delay, the phase of the xy-axis current is subjected to phase compensation for two sampling periods to obtain the phase information of the xy-axis current at time k+2;

4) Multiply the current amplitude obtained by the enhanced phase-locked loop by the minimum loss coefficient K _ml to obtain a new xy-axis current amplitude considering the loss, and then combine it with the compensated phase of the xy-axis to obtain the loss-considering, compensation After the xy-axis current, the minimum loss coefficient K _ml should be less than 1, and the larger the better under the premise of achieving the control effect;

5) Compare the compensated xy-axis current amplitude with the preset threshold I _th . If the compensated xy-axis current amplitude is less than or equal to the threshold, the xy-axis current reference value is set to 0, which is consistent with normal operation. , if the compensated xy-axis current amplitude is greater than the threshold value, the xy-axis current reference value is set to the compensated xy-axis current value considering the loss, and the xy-axis current threshold should be selected from the maximum amplitude of the pulsation during normal operation. more than twice the

6) The current prediction module obtains the predicted value of the xy-axis current at time k+1 by discretizing the differential equations of the motor voltage and current;

7) Based on the idea of current deadbeat control, the deadbeat control module takes the xy-axis current reference value as the predicted value at time k+2, and calculates the xy-axis voltage space vector reference value that takes into account the influence of the time delay of one sampling period;

8) According to the torque plane voltage space vector reference value obtained by the dq-axis current closed-loop PI control and the harmonic plane voltage space vector reference value calculated by the deadbeat module, the six-phase voltage reference value is obtained by using the vector space decoupling inverse transformation;

9) The space vector modulation module modulates according to the reference value of each phase voltage vector, and outputs the corresponding pulse action signal to control the inverter.

The present invention adopts the above-mentioned technical scheme, and has the following beneficial effects:

(1) The hybrid control framework proposed by the present invention combines the advantages of both PI control and deadbeat control. The PI control ensures the precise control of the dq-axis current, and the deadbeat control ensures that the xy-axis current has no effect on the DC and AC forms. The current reference values all have good tracking performance, which lays the foundation for fault-tolerant control. By optimizing the reference value given by the harmonic current plane, the originally suppressed self-healing ability of the dual-phase motor drive system can be fully exerted, achieving high performance. Performance fault tolerance control.

(2) Because it is not necessary to diagnose the fault type in advance, the present invention fundamentally avoids the problem of misdiagnosis, and also avoids the problem of long-term fault operation caused by time-consuming diagnosis.

(3) The diagnosis-free self-healing fault-tolerant control strategy proposed by the present invention is universal, and is suitable for the working conditions of open-circuit failure, single-phase open-circuit fault and multi-phase open-circuit fault of the multi-phase motor drive system, avoiding the situation of misdiagnosis .

(4) The fault-tolerant control strategy proposed by the present invention does not need to modify the motor model, modulation strategy or control framework according to different fault types, avoids complex adjustment of the fault-tolerant control strategy for different fault types and fault locations, and reduces the The complexity of control minimizes the adverse effects of the fault tolerance scheme itself.

Description of drawings

1 is a block diagram of a hybrid control structure for a dual-phase permanent magnet synchronous motor drive system;

Among them, 1.1 is the speed loop PI regulator, 1.2 is the q-axis current PI regulator, 1.3 is the d-axis current PI regulator, 1.4 is the synchronous inverse transformation module, 1.5 is the decoupling inverse transformation module, 1.6 is the polar coordinate transformation module, 1.7 is the three-phase voltage space vector modulation module, 1.8 is the DC bus, 1.9 is the six-phase inverter, 1.10 is the dual three-phase permanent magnet synchronous motor, 1.11 is the decoupling transformation module, 1.12 is the harmonic plane current prediction module, 1.13 1.14 is a deadbeat control module, 1.15 is a synchronous conversion module, and 1.16 is a speed calculation module.

Fig. 2(a) and Fig. 2(b) are the current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under the A-phase open-circuit fault, respectively;

Among them, 2.1 is the positive direction of the A-phase current, 2.2 is the positive direction of the B-phase current, 2.3 is the C-phase current positive direction, 2.4 is the trajectory of the α ₁ -β ₁ plane current when the motor is running normally, and 2.5 is the α ₁ in the motor fault state. The actual trajectory of the _-β1 plane current, 2.6 is the ideal trajectory of the α1 -β1 plane current in the motor fault state, 2.7 is the positive direction _of the D _- phase current, 2.8 is the E-phase current positive direction, 2.9 is the F-phase current positive direction, 2.10 is the trajectory of the α2 _- β2 plane current when the motor is in normal operation, 2.11 is the actual trajectory of the α2 _{- β2} plane current in the motor fault state, 2.12 is the ideal trajectory of the _{α2 - β2} plane current in the motor fault state, 2.13 is the current closed-loop control effect of the xy-axis, corresponding to the horizontal arrow pointing to the _β2 coordinate axis in the figure, and 2.14 is the current closed-loop control effect of the dq-axis, corresponding to the horizontal arrow pointing to the ideal trajectory in the figure.

Figure 3 is the x-axis current waveform diagram under the A-phase open circuit fault;

Among them, 3.1 is the actual value of the x(y) axis current, 3.2 is the ideal value of the x(y) axis current, 3.3 is the given reference value of the x(y) axis current, and 3.4 is the dq axis current closed-loop control effect, corresponding to the point in the figure The vertical arrow of the ideal trajectory, 3.5 is the current closed-loop control effect of the x(y) axis, corresponding to the vertical arrow pointing to the time axis in the figure.

Fig. 4 is the structural block diagram of the optimization method of the harmonic plane current reference value;

Among them, 4.1 is the enhanced phase-locked loop module, 4.2 is the minimum loss coefficient, 4.3 is the phase conversion module, and 4.4 is the reference value generation module.

Figure 5 is a diagram of the harmonic plane current self-healing process;

Where, 5.1 is the actual value of the x(y) axis current, 5.2 is the given reference value of the x(y) axis current, and 5.3 is the ideal value of the x(y) axis current.

Figure 6(a) and Figure 6(b) are the ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under a single-phase open-circuit fault, respectively;

Among them, 6.1 is the positive direction of the A-phase current, 6.2 is the ideal trajectory of the α1 _- β1 plane current under the motor D _- phase open _- circuit fault, 6.3 is the α1 _- β1 plane current trajectory under the normal state of the motor, and 6.4 is the B-phase current. Positive direction, 6.5 is the ideal trajectory of α ₁ -β ₁ plane current under motor E-phase open-circuit fault, 6.6 is the positive direction of C-phase current, 6.7 is the ideal α ₁ -β ₁ plane current trajectory under motor F-phase open circuit fault, 6.8 is The ideal trajectory of α ₁ -β ₁ plane current under motor C-phase open-circuit fault, 6.9 is the ideal α ₁ -β ₁ plane current trajectory under motor A-phase open-circuit fault, 6.10 is the ideal α ₁ -β ₁ plane current under motor B-phase open-circuit fault Trajectories, 6.11 is the ideal trajectory of α ₂ -β ₂ plane current under motor A-phase open-circuit fault, 6.12 is the positive direction of D-phase current, 6.13 is the ideal α ₂ -β ₂ plane current trajectory under motor C-phase open-circuit fault, 6.14 is the motor The ideal trajectory of α ₂ -β ₂ plane current under B-phase open circuit fault, 6.15 is the positive direction of E-phase current, 6.16 is the α ₂ -β ₂ plane current trajectory under the normal state of the motor, 6.17 is the positive direction of F-phase current, 6.18 is α ₂ -β ₂ plane current ideal trajectory under F-phase open circuit fault, 6.19 is the ideal α _{2 -β 2 plane current trajectory under D-phase open circuit fault, 6.20 is the α 2 -β 2 plane current} ideal trajectory under E-phase open circuit fault.

Fig. 7(a) and Fig. 7(b) are the ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under a two-phase open-circuit fault with a fault phase angle of 90°, respectively;

Among them, 7.1 is the positive direction of the A-phase current, 7.2 is the ideal α1-β1 plane current trajectory under the motor B _- phase and D _- phase open _- circuit fault, 7.3 is the α1 _- β1 plane current trajectory under the normal state of the motor, and 7.4 is the motor The ideal trajectories of α ₁ -β ₁ plane currents under A-phase and F-phase open-circuit faults, 7.5 is the positive direction of B-phase current, 7.6 is the C-phase current positive direction, and 7.7 is the motor's C-phase and E-phase open circuit faults α ₁ - β1 plane current ideal trajectory, 7.8 is the ideal α2- _β2 plane current trajectory under motor A-phase and F-phase open-circuit faults, 7.9 is the positive direction of motor D _- phase current, 7.10 is motor C-phase and E-phase open _- circuit faults under _α2 -β ₂ plane current ideal trajectory, 7.11 is the α ₂ -β ₂ plane current trajectory in the normal state of the motor, 7.12 is the α ₂ -β ₂ plane current ideal trajectory under the motor's B-phase and D-phase open circuit faults, 7.13 is the E-phase current. Positive direction, 7.14 is the positive direction of F-phase current.

Fig. 8(a) and Fig. 8(b) are the ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under a two-phase open-circuit fault with a fault phase angle of 30° or 150°, respectively;

Among them, 8.1 is the positive direction of the A-phase current, 8.2 is the ideal trajectory of the α1 _- β1 plane current under the motor B-phase and F-phase open-circuit faults, and 8.3 is the α1 _{- β1} plane current under the motor B _- phase and E-phase open-circuit faults Ideal trajectory, 8.4 is the α ₁ -β ₁ plane current trajectory under the normal state of the motor, 8.5 is the α ₁ -β ₁ plane current ideal trajectories under the motor's A-phase and D-phase open-circuit faults, and 8.6 is the motor's A-phase and E-phase open-circuit faults α1 _{- β1} plane current ideal trajectory, 8.7 is the positive direction of B-phase current, 8.8 is the C-phase current positive direction, 8.9 is the α1 _- β1 plane current ideal trajectory under motor C-phase and D _- phase open circuit faults, 8.10 is the ideal locus of the α ₁ -β ₁ plane current under the motor C-phase and F-phase open-circuit faults, 8.11 is the α ₂ -β ₂ plane current ideal trajectories under the motor's B-phase and F-phase open-circuit faults, and 8.12 is the motor C-phase and F-phase open circuit The ideal trajectories of α ₂ -β ₂ plane currents under fault, 8.13 is the positive direction of D-phase current, 8.14 is the ideal trajectories of α ₂ -β ₂ plane currents under motor A-phase and E-phase open-circuit faults, and 8.15 is the motor's B-phase and E-phase The ideal trajectories of α ₂ -β ₂ plane currents under open-circuit faults, 8.16 is the ideal trajectories of α ₂ -β ₂ plane currents under motor A-phase and D-phase open-circuit faults, and 8.17 is α ₂ -β ₂ under motor C-phase and D-phase open-circuit faults The ideal trajectory of the plane current, 8.18 is the positive direction of the E-phase current, 8.19 is the α ₂ -β ₂ plane current trajectory under the normal state of the motor, and 8.20 is the positive direction of the F-phase current.

Fig. 9(a) and Fig. 9(b) are the ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under the two-phase open-circuit fault of a single set of three-phase windings, respectively;

Among them, 9.1 is the positive direction of the A-phase current, 9.2 is the ideal α1 _- β1 plane current trajectory under the open-circuit fault of the D _- phase, E _- phase and F-phase of the motor, 9.3 is the α1 _- β1 plane current trajectory under the normal state of the motor, 9.4 is the positive direction of the motor phase B current, 9.5 is the positive direction of the motor C phase current, 9.6 is the ideal trajectory of the α ₁ -β ₁ plane current under the open-circuit fault of the motor A, B and C phases, 9.7 is the D phase current positive direction, 9.8 is the ideal trajectory of the α ₂ -β ₂ plane current under the open-circuit fault of the A-phase, B-phase and C-phase of the motor, 9.9 is the α ₂ -β ₂ plane current trajectory under the normal state of the motor, 9.10 is the E-phase current positive direction, 9.11 is F The positive direction of the phase current, 9.12 is the ideal trajectory of the α ₂ -β ₂ plane current under the open-circuit fault of the D-phase, E-phase and F-phase of the motor.

Detailed ways

The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Modifications in the form of valence all fall within the scope defined by the appended claims of the present application.

The present invention provides an open-circuit fault-free self-repairing method for a dual-phase permanent magnet synchronous motor drive system. In view of the problems of complex control schemes and time-consuming misdiagnosis and diagnosis in the existing fault-tolerant control strategies of multi-phase motors, the present invention proposes The method can quickly and accurately realize fault-tolerant control of motor open-circuit faults, without diagnosing the fault type, avoiding the problem of long-term fault operation caused by time-consuming misdiagnosis and diagnosis, and also does not require the motor model, modulation strategy and The control frame is adjusted.

The present invention proposes a hybrid control scheme for a dual-phase permanent magnet synchronous motor drive system, including a speed loop PI regulator 1.1, a q-axis current PI regulator 1.2, a d-axis current PI regulator 1.3, a synchronous inverse conversion module 1.4, a solution Coupling-inverse transformation module 1.5, polar coordinate transformation module 1.6, three-phase voltage space vector modulation module 1.7, DC bus 1.8, six-phase inverter 1.9, dual three-phase permanent magnet synchronous motor 1.10, decoupling transformation module 1.11, harmonic plane Current prediction module 1.12, dual-phase permanent magnet synchronous motor speed encoder 1.13, deadbeat control module 1.14, synchronous transformation module 1.15, speed calculation module 1.16.

The hybrid control of the present invention consists of the PI control of the dq-axis current and the deadbeat control of the xy-axis current. In the torque plane, a typical PI control is used to achieve precise closed-loop control of the dq-axis current. In the harmonic plane, in order to ensure that the harmonic current can obtain good tracking performance for both the DC reference value under normal operating conditions and the AC reference value under fault self-repair status, the present invention adopts deadbeat control to realize the control of the xy-axis current. Closed-loop control.

The harmonic plane current prediction module of the present invention is obtained by discretizing the motor xy-axis voltage equation. According to the discretization results, the current value at time k+1 is calculated as follows:

和

是k+1时刻x、y轴电流的预测值，

和

是k时刻x、y轴电流的采样值，

和

是k时刻x、y轴电压的采样值，R_s是定子电阻值，T_s是采样周期，L_ls是定子漏感值。in,

and

is the predicted value of the x and y-axis currents at time k+1,

and

is the sampling value of the x and y-axis currents at time k,

and

is the sampling value of the x, y-axis voltage at time k, R _s is the stator resistance value, T _s is the sampling period, and L _ls is the stator leakage inductance value.

The specific implementation mode of the deadbeat control module of the present invention is: according to the current deadbeat control theory, after considering the sampling delay, the harmonic plane voltage reference value calculated based on the motor model is:

和

是k+1时刻x、y轴电流的预测值，

和

是x、y轴电流参考值，

和

是x、y轴电压的参考值，R_s是定子电阻值，T_s是采样周期，L_ls是定子漏感值。in,

and

is the predicted value of the x and y-axis currents at time k+1,

and

are the current reference values of the x and y axes,

and

is the reference value of the x, y-axis voltage, R _s is the stator resistance value, T _s is the sampling period, and L _ls is the stator leakage inductance value.

The structural block diagram of the hybrid control of the dual-phase permanent magnet synchronous motor drive system proposed by the present invention is shown in FIG. 1 . First, the six-phase currents of A, B, C, D, E, and F are extracted from the dual-phase permanent magnet synchronous motor, and the current value in the α-β, xy coordinate system can be obtained through the decoupling conversion module 1.11. The xy-axis current passes through the current prediction module 1.12 to obtain the xy-axis current value at time k+1, and then combines with the given xy-axis current value reference value to obtain the xy-axis reference voltage through the deadbeat control module 1.14. At the same time, the α and β axis currents pass through the synchronous transformation module 1.15 to obtain the feedback value of the dq axis current. The actual speed of the motor is obtained by the signal obtained by the encoder 1.13 after passing through the speed calculation module 1.16. The speed loop PI regulator 1.1 is used to generate the q-axis current reference value, the q-axis current PI regulator 1.2 is used to generate the q-axis voltage reference value, and the d-axis current PI regulator 1.3 is used to generate the d-axis voltage reference value. The reference voltage of the torque plane and the reference voltage of the loss plane are obtained through the decoupling inverse transformation module 1.5 to obtain the six-phase reference voltages U _A -U _F . The reference voltages of the three phases A, B, and C and the reference voltages of the three phases D, E, and F pass through their polar coordinate transformation modules 1.6, respectively, and are modulated into control signals in the three-phase voltage space vector modulation module 1.7. The inverter 1.9 realizes the power amplification of the control signal, and finally realizes the control of the dual three-phase permanent magnet synchronous motor 1.10. In this embodiment, the structure of the control system in the normal state and the fault state is the same, and both are the hybrid control scheme shown in FIG. 1 .

The present invention analyzes the open-circuit fault of the winding as follows: the six-phase current of the motor is transformed into two α-β coordinate systems respectively through coordinate transformation, there are:

where i _α1 and i _β1 are the α ₁ -axis current and β ₁ -axis current in the α ₁ -β ₁ plane, i _α2 and i _β2 are the α ₂ -axis current and β ₂ -axis current in the α ₂ -β ₂ plane, i _A , i _B , i _C , i _D , i _E , i _F are the A, B, C, D, E, F phase winding currents. The relationship between the above formula and the vector space decoupling coordinate system is:

Among them, i _α , i _β , i _x , and i _y are the α, β, x, y-axis currents obtained by decoupling, i _α1 and i _β1 are the α ₁ -β ₁ plane α ₁ -axis current and β ₁ -axis current, i _α2 and i _β2 are the α ₂ -β ₂ plane α ₂ -axis current and β ₂ -axis current. Take the open circuit of the A-phase winding as an example for analysis. Figure 2 is a graph of the current trajectories in the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under an A-phase open-circuit fault. During normal operation, the two sets of windings of the motor flow through a considerable current, respectively contributing half of the electromagnetic torque. At this time, the running trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane are circles with the same diameter, such as 2.4 and 2.10. When the A-phase is open, the A-phase current is immediately forced to 0, which also causes i _α1 to become 0, while the i _β1 , which is perpendicular to the A-phase current, is not affected. So when phase A is open, the actual current trace in the α ₁ -β ₁ plane is a straight line. According to the equivalent rotating magnetomotive force theory, if the second set of windings can compensate for the missing current of the first set of windings, the motor can still generate stable torque. In other words, if i _α1 can be fully compensated by i _α2 , fault-tolerant operation can be achieved. Therefore, as shown in Fig. 2(a) and Fig. 2(b), when a fault occurs, the ideal current trajectory is an ellipse in the α ₂ -β ₂ plane and a straight line in the α ₁ -β ₁ plane. According to formula (4), the current relationship at fault can be obtained as:

Among them, the superscript F represents the physical quantity after the failure. According to the above formula, the A-phase open-circuit fault will cause errors in the tracking of i _α and i _x , as shown in Figure 2.14 in Figure 2(b), in the fault state, the closed-loop control effect of the dq-axis current makes i _α2 There is a tendency to increase to the ideal trajectory, so the dq-axis current closed-loop control helps to eliminate torque ripple. But at this time i _x is equal to -i _α2 , the xy-axis current control effect will hinder the increase of i _α2 and increase the torque ripple, as shown in 2.15. Finally, the dq-axis current closed-loop and xy-axis current closed-loop control will reach a balance, so the actual current in the fault state will be less than the ideal current, and the actual current trajectory of the α2 _{- β2} plane will be inside the ideal current trajectory, as shown in 2.11 . Overall, the difference between the ideal current and the actual current results in torque ripple. Figure 3 shows the waveforms of the ideal and actual currents on the x-axis under an A-phase open-circuit fault. Similarly, the dq-axis current closed-loop control 3.4 makes the actual value tend to the ideal value, which helps to reduce the difference between the ideal current and the actual current, while the xy-axis current closed-loop control 3.3 prevents the actual value from increasing and makes it tend to 0, making the ideal The difference between the current and the actual current increases. Therefore, when the effects of the two closed-loop controls are balanced, the actual current is between 0 and the ideal current, as shown in 3.1. Therefore, it is unreasonable to directly give the harmonic current reference value to 0, which inhibits the self-healing capability of the dual-phase motor drive system. The analysis of single-phase open-circuit faults here is also applicable to the case of switch tube faults and multi-phase open-circuit faults.

Based on the above analysis, the present invention proposes a diagnosis-free self-repair method for the open-circuit fault of a dual-phase permanent magnet synchronous motor drive system, and optimizes the selection of the harmonic plane current reference value through an enhanced phase-locked loop. In the event of a fault, the x, y axis current reference values will be automatically adjusted according to the actual x, y axis current. In this way, the error between the actual current and the ideal current will gradually decrease to zero. When the x and y-axis current reference values reach the ideal value, the reference value of the current in the corresponding faulty phase will be reduced to 0, and the faulty motor drive system can be regarded as a normal operating state. Therefore, the system can automatically realize fault-tolerant control without changing the motor model, decoupling matrix, modulation strategy and control system framework.

The harmonic current reference value optimization method according to the present invention is shown in FIG. 4 . Enhanced phase-locked loop 4.1 is used to estimate the magnitude and phase of the actual current in the xy-axis. The minimum loss factor of 4.2 is introduced to avoid the situation that the actual current continues to increase after reaching the ideal current, and at the same time, it also ensures the minimum copper loss of the motor in the fault state. Considering the influence of motor rotation and sampling delay, the phase of the actual current of the xy-axis is compensated for two sampling periods when generating the xy-axis current reference value. In normal operation, both the x and y-axis current reference values are set to 0, but after a fault occurs, one of the x and y-axis current reference values is still set to 0. Therefore, in order to ensure that only the reference value that needs to be adjusted is modified in a fault state, the present invention introduces a conditional criterion to further optimize the setting of the xy-axis current reference value, as shown in reference value generation module 4.4. Only when the amplitude I _x or I _y of the generated reference value is greater than the preset threshold value I _th , the generated reference value will be truly given, otherwise the corresponding reference value is still set to 0.

The implementation process of the self-healing method according to the present invention is shown in FIG. 5 . As mentioned above, the dq-axis current closed-loop control helps to reduce the difference between the actual value and the ideal value, while the unreasonable setting of the xy-axis current reference value to 0 will inhibit the self-healing ability of the motor when it fails. In the diagnosis-free self-repair method proposed by the present invention, the reference value of the xy-axis current can be automatically adjusted by the optimization method of the reference value of harmonic current in Fig. The problem that the wave plane current reference value is given unreasonably. When an open circuit or a switch tube fault occurs, the xy-axis current reference value is 0 at the moment of the fault. Due to the closed-loop control of the dq-axis currents, either the x-axis current or the y-axis current or both will deviate from the 0 given before the fault and lie between the ideal current and 0, as shown in Figure 3. Because in the self-healing method proposed by the present invention, the xy-axis current reference value can be automatically adjusted according to the magnitude and phase of the actual current estimated by the enhanced phase-locked loop, and the newly given reference value will be closer to the ideal current. Since the effect of the dq-axis closed-loop control always exists, the actual current will always be between the newly given reference value and the ideal current value, that is, the shaded area in Figure 5. It can be seen from Figure 5 that the amplitude error and phase error of the actual current and the ideal current are gradually decreasing. For a dual-phase motor whose neutral points of two windings are isolated from each other, the current control dimension during normal operation is four dimensions. The single-phase open-circuit fault and the two-phase open-circuit fault reduce the current control dimension to three-dimensional and two-dimensional, respectively. When operating under fault conditions, the current control dimension above two dimensions is the premise of the normal control of the torque plane current. For two-phase open circuit faults, the current control dimension is reduced to two dimensions. In this case all control dimensions are used for the current control of the torque plane. For single-phase open-circuit faults, one remaining control dimension affects the current profile in the harmonic plane. The magnitude of the xy-axis current is positively correlated with the motor copper losses. Therefore, the introduction of the minimum loss coefficient K _ml can avoid the situation that the actual current of the xy-axis continues to increase after reaching the ideal current. Finally, the reference value and actual value of the harmonic plane current are equal to the ideal value, at this time, the given reference value of the fault phase current will be equal to 0. As a result, the faulty motor can still be regarded as a normal operating state, realizing automatic fault-tolerant control without changing the motor model, decoupling matrix, modulation strategy and control system framework.

Because the present invention is based on the inherent self-repairing capability of the dual-phase motor drive system, the proposed diagnosis-free self-repairing method is effective for both switch tube faults and winding open-circuit faults. The ideal current trajectories under the open-circuit fault of the switch tube are the same as the ideal current trajectories under the open-circuit fault of the corresponding winding. For example, the ideal current trajectory under the fault condition of the upper arm switch tube of phase A of the inverter is exactly the same as the ideal current trajectory under the open-circuit fault of the A-phase winding. To illustrate the self-healing capability of the dual-phase motor drive system, ideal current trajectories under different faults according to the present invention are shown in Figures 6-9.

The ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under the single-phase open-circuit fault proposed by the present invention are shown in Figures 6(a) and 6(b). As mentioned earlier, when a single-phase open-circuit fault occurs, the current trace of the faulted phase winding immediately becomes a straight line. Due to the effect of dq-axis current closed-loop control, the remaining normal windings will automatically perform equivalent compensation for the missing current of the faulty phase as shown in Figure 6. The current trace F _M refers to the ideal current trace (M=A, B, C, D, E, F) in case of M-phase open-circuit fault. It can be seen from Figure 6 that the ideal current traces for different single-phase open-circuit faults have the same shape: a straight line in the plane of the faulted phase and an ellipse in the plane of the other set of windings.

Two-phase open-circuit faults in different motor windings can be divided into two types according to the current trajectory. The first is a two-phase open-circuit fault with a fault phase angle of 90°; the second is a fault phase with an angle of 30° or 150°. Two-phase open circuit fault. Because each set of three-phase windings has an open-circuit fault in one phase, the current trajectories of both winding planes are forced to be constrained to a straight line, as shown in Figures 7 and 8.

The ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under a two-phase open-circuit fault with a fault phase angle of 90° proposed by the present invention are shown in Figures 7(a) and 7(b). Because the direction of the missing current vector in different winding planes is vertical under such faults, the current lost in one plane can be directly compensated by the remaining current in the other plane, as shown in Figure 7. For example, when an open-circuit fault occurs when the A-phase and F are the same, the α1 _- axis current and β2 _- axis current become 0, respectively. Because of the self-healing capability of the motor controlled by the dq-axis current closed-loop, the α1 _- axis current and the β2 _- axis current are compensated by the α2 _- axis current and the β1 _- axis current. Therefore, the α ₂ -axis current and the β ₁ -axis current become twice as large, as shown in Figure 7.

The ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under the two-phase open-circuit fault with the fault phase included angle of 30° or 150° proposed by the present invention are shown in Fig. 8(a) and Fig. 8(b) shown. Simultaneous open-circuit faults in windings with an included angle of 30° or 150° can cause severe reductions in the α-axis or β-axis current. Therefore, the compensation for the fault phase current will make the ideal current amplitude much larger than the current in the case of a two-phase open-circuit fault with a fault phase angle of 90°, as shown in Figure 8. For example, when an open-circuit fault occurs when the A-phase and D-phase are the same, the α-axis current is severely reduced, and only the α-axis current synthesized by the E-phase and the F-phase can be compensated for the α _- axis current. When the α-axis current compensation is completed, the β-axis current will be much larger than the magnitude required to establish the equivalent rotating MMF. Therefore, the β ₁ -axis current will automatically cancel the excess β ₂ -axis current to ensure the synthesis of the equivalent rotating magnetomotive force. Ultimately, the length of the ideal current traces for both the α1 _- β1 plane and the _{α2 - β2} plane is four times the diameter of the normal running trace circle, as shown in Figure 8.

The ideal current trajectories of the α ₁ -β ₁ plane and the α ₂ -β ₂ plane under the two-phase open-circuit fault of a single set of three-phase windings proposed by the present invention are shown in Figures 9(a) and 9(b). When a two-phase open fault occurs in the same winding, all phase currents in that winding will go to 0, so the faulted winding cannot contribute alpha-axis current or beta-axis current. The missing alpha and beta axis currents will be fully compensated by another set of windings, as shown in Figure 9. For example, when an open-circuit fault occurs when phases A and B are the same, the current trajectory of the first set of windings will be forced to be constrained to the origin of the α1 _{- β1} plane, while the other set of windings will automatically control the α-axis due to the dq-axis current closed-loop control. and β-axis current to compensate. Therefore the ideal current trajectory in the α ₂ -β ₂ plane is a concentric circle with twice the diameter of the normal running trajectory circle.

Claims (4)

1. The diagnosis-free self-repairing method for open-circuit fault of double three-phase permanent magnet synchronous motor driving system is characterized in that a PI control strategy pair is adopteddqClosed loop control of shaft current to update torque plane reference voltage, pairxyThe shaft current is subjected to dead-beat control to update the harmonic plane reference voltage, wherein the dead-beat control is performedxyThe method for determining the shaft current reference value comprises the following steps: initializationxyThe reference value of the shaft current is 0, and the current moment is extractedxyAmplitude and phase information of the shaft current, for the present momentxyThe amplitude and the phase of the shaft current are respectively subjected to the amplification processing of the minimum loss coefficient and the phase compensation of two sampling periods to obtain the updated amplitude and phasexyShaft current after updatexyUpdated when shaft current exceeds thresholdxyShaft current asxyShaft current reference value, after updatingxyShaft current not exceeding threshold valuexyThe shaft current reference value is 0.

2. The diagnosis-free and self-repairing method for the open-circuit fault of the double three-phase permanent magnet synchronous motor driving system according to claim 1, characterized by comprising the following steps of performing dead-beat controlxyThe shaft current reference value iskPredicted value at +2 time point, predicted from motor phase current sample value and voltage sample valuexyAxial current ofkAt +1 timexyShaft current according tok+2 timexyPredicted value of shaft current, pairkAt +1 timexyThe shaft current is subjected to dead-beat control to obtain a harmonic plane reference voltage value considering the time delay influence of one sampling period, and the harmonic plane reference voltage is updated and obtaineddqAnd performing decoupling transformation, polar coordinate transformation and space vector transformation on the updated torque plane reference voltage in the shaft current closed-loop control to update the motor driving signal.

3. The diagnosis-free self-repairing method for the open-circuit fault of the double-three-phase permanent magnet synchronous motor driving system according to claim 2, wherein the diagnosis-free self-repairing method is used for predicting the open-circuit fault according to the phase current sampling value and the voltage sampling value of the motorxyThe method of the shaft current is to discretize the differential equation of the motor voltage and the current.

4. The double three-phase permanent magnet synchronous motor driving system open-circuit fault diagnosis-free self-repairing method according to claim 1, characterized in that the method is generatedxyThe device for the shaft current reference value comprises:

enhanced phase-locked loop with input terminated prior timexyShaft current for extracting the present momentxyAmplitude and phase information of the shaft current;

an adder having two input terminals respectively connected to the current timexyPhase information of the shaft current and an electrical angle generated by twice the sampling period are used for accumulating the electrical angles of the two sampling periods on the basis of the extracted phase information;

sin function module with input end connected to adder output end and output end compensated by two sampling periodsxyA sin function of the shaft current phase;

a multiplier with two input ends respectively connected with the output end of the minimum loss coefficient and sin function module and used for counting the current timexyThe amplitude and the phase of the shaft current are respectively subjected to the amplification processing of the minimum loss coefficient and the phase compensation of two sampling periods to obtain the updated amplitude and phasexyShaft current; and a process for the preparation of a coating,

one input end of the alternative data selector is connected with 0, and the other input end is connected with the updated data selectorxyShaft current after updatexyOutputting updated output when shaft current exceeds thresholdxyShaft current after updatexy0 is output when the shaft current does not exceed the threshold.

Images