Diagnosis-free sensorless control method of dual three-phase permanent magnet synchronous motor compatible with single-phase open-circuit fault

Abstract

The application discloses a kind of compatible single-phase open-circuit fault's double three-phase permanent magnet synchronous motor's diagnosis-free sensorless control method, first, using second-order generalized integrator, based on frequency difference, harmonic subspace current is separated into fundamental component and 5, 7 harmonic components.5, 7 harmonic components are used as current loop feedback, and harmonic suppression voltage is generated by regulator;Fundamental component is input to the fault model observer considering voltage constraint, and feedforward compensation voltage is estimated.The above-mentioned two parts of compensation voltage are superimposed on harmonic subspace, finally, corrected command voltage is used as the input of sensorless algorithm, combined with back-EMF observer and phase-locked loop, the accurate estimation of rotor position and speed is realized.The method does not need to rely on fault diagnosis, can realize unified control structure under healthy operation and a variety of single-phase open-circuit fault conditions, avoid the complexity brought by traditional method when switching control strategy before and after fault.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology and relates to a sensorless control method for a dual three-phase permanent magnet synchronous motor. Specifically, it relates to a universal sensorless control method for a dual three-phase permanent magnet synchronous motor that is applicable to both healthy and single-phase open-circuit faults. Background Technology

[0002] Traditionally, fault diagnosis has been considered a prerequisite for fault-tolerant control of sensorless systems. However, the introduction of diagnosis itself can negatively impact the reliability of motor drive systems. In the field of fault-tolerant control of multiphase motors, most existing strategies require adjustments to the motor model, modulation method, and control structure based on specific fault types, and the fault-tolerant methods vary significantly under different fault modes. These issues often lead to a complex overall control algorithm structure, increased computational burden, decreased system stability, and increased difficulty in mode switching. Summary of the Invention

[0003] To address the aforementioned challenges, this invention fully leverages the inherent fault tolerance of dual three-phase permanent magnet synchronous motor drive systems, providing a diagnostic-free, sensorless control method for dual three-phase permanent magnet synchronous motors compatible with single-phase open-circuit faults. This method eliminates the need for fault diagnosis, enabling a unified control structure under both healthy operation and various single-phase open-circuit fault conditions, avoiding the complexity of frequent control strategy switching before and after faults in traditional methods. By constructing a diagnostic-free, universal control framework, this invention not only reduces the design difficulty and computational burden of fault-tolerant control schemes but also effectively avoids the risk of system instability caused by misdiagnosis, improving the reliability of the drive system. It provides a simple and efficient solution for sensorless operation of dual three-phase permanent magnet synchronous motors in high-reliability application scenarios.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A diagnostic-free, sensorless control method for a dual three-phase permanent magnet synchronous motor compatible with single-phase open-circuit faults includes the following steps:

[0006] Step (1) The collected six-phase currents of the dual three-phase permanent magnet synchronous motor are decoupled into current components in the torque subspace and harmonic subspace through vector space decoupling transformation:

[0007]

[0008] In the formula, , , and These are the currents in the torque subspace and harmonic subspace, respectively. , , , , and The results are the six-phase current sampling results of a dual three-phase permanent magnet synchronous motor;

[0009] Step (2) Use a second-order generalized integrator to perform frequency separation of the current in the harmonic subspace;

[0010] Step (3) extracts the 5th and 7th harmonic current components. As the feedback value of the current regulator in the harmonic subspace, it is used to generate the harmonic suppression voltage. :

[0011]

[0012] In the formula, and In the harmonic subspace The proportional and integral coefficients of the shaft current regulator; for The reference current of the shaft current regulator; ;

[0013] Step (4) uses the extracted fundamental frequency current component As input, the required compensation voltage is estimated using a fault model observer that considers voltage constraints:

[0014]

[0015] In the formula, and These are the resistance and leakage inductance of the permanent magnet synchronous motor, respectively. represent Estimated compensation voltage for the shaft, Represents the independent variable in the discrete domain. For switching cycles;

[0016] Step (5) superimposes the harmonic suppression voltage and the estimated compensation voltage calculated in steps (3) and (4) respectively into the harmonic subspace;

[0017] Step (6) combines the collected inverter DC bus voltage with The shaft current regulator command voltage is calculated. The command voltage of the shaft is used as input; the command voltage and current signal of the torque subspace are used as input to construct a back EMF observer, and the observed back EMF is sent to the phase-locked loop to accurately calculate the rotor position and speed information.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention establishes an accurate motor model after a fault by considering voltage transmission errors caused by faults. Based on this, voltage feedforward compensation is introduced into the harmonic subsystem, thereby effectively suppressing voltage distortion and phase current harmonics caused by open-circuit faults, fundamentally eliminating the adverse effects of faults on rotor position estimation. At the same time, this invention completely eliminates reliance on fault diagnosis, avoiding system risks and performance degradation caused by misdiagnosis or diagnostic delays.

[0020] 2. This invention overcomes the limitation of traditional methods that require switching control structures before and after a fault. It not only maintains high-precision position estimation under healthy conditions but also significantly reduces position estimation errors without fault diagnosis under phase loss faults, and effectively suppresses torque fluctuations. This method is particularly suitable for sensorless drive systems of dual three-phase permanent magnet synchronous motors with stringent reliability requirements. Attached Figure Description

[0021] Figure 1 A block diagram of a diagnostic-free, sensorless control method for dual three-phase permanent magnet synchronous motors compatible with single-phase open-circuit faults;

[0022] Figure 2 The results show the experimental waveforms of phase current, position, and position error under rated load using traditional methods.

[0023] Figure 3 The experimental results of phase current, position, and position error waveforms under rated load using the method of this invention are shown. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0025] This invention provides a diagnostic-free, sensorless control method for a dual three-phase permanent magnet synchronous motor compatible with single-phase open-circuit faults. First, a second-order generalized integrator is used to separate the harmonic subspace current into a fundamental frequency component and 5th and 7th harmonic components based on frequency differences. The 5th and 7th harmonic components are used as current loop feedback, generating a harmonic suppression voltage via a regulator. The fundamental frequency component is input to a fault model observer considering voltage constraints to estimate the feedforward compensation voltage. The two compensation voltages are superimposed on the harmonic subspace, which can suppress voltage distortion caused by open-circuit faults at the source and effectively reduce the harmonic content in the phase current. Finally, the corrected command voltage is used as the input to the sensorless algorithm, combined with a back EMF observer and a phase-locked loop, to achieve accurate estimation of rotor position and speed. The specific steps are as follows:

[0026] (1) The collected six-phase currents of the dual three-phase permanent magnet synchronous motor are decomposed into current components in the torque subspace and harmonic subspace by vector space decoupling transformation:

[0027]

[0028] In the formula, , , and These are the currents in the torque subspace and harmonic subspace, respectively. , , , , and The results are the six-phase current sampling results of a dual three-phase permanent magnet synchronous motor.

[0029] (2) Frequency separation of currents in the harmonic subspace is performed using a second-order generalized integrator. Taking shaft current as an example, the separated fundamental frequency current component and the 5th and 7th harmonic current components are expressed as follows: and .

[0030] (3) Extract the 5th and 7th harmonic current components As the feedback value of the current regulator in the harmonic subspace, it is used to generate the harmonic suppression voltage. :

[0031]

[0032] In the formula, and In the harmonic subspace The proportional and integral coefficients of the shaft current regulator; for The reference current of the shaft current regulator is usually = 0.

[0033] (4) The extracted fundamental frequency current component As input, the required compensation voltage is estimated using a fault model observer that considers voltage constraints. The transfer function in the discrete-domain model can be expressed as:

[0034]

[0035] In the formula, and These are the resistance and leakage inductance of the permanent magnet synchronous motor, respectively. represent Estimated compensation voltage for the shaft, The switching cycle.

[0036] (5) The above two parts of the compensation voltage and The superposition effect in the harmonic subspace, the structural block diagram of the method proposed in this invention is as follows. Figure 1 As shown.

[0037] (6) Combining the collected inverter DC bus voltage with The shaft current regulator command voltage is calculated. The command voltage of the shaft. Using the command voltage and current signal from the torque subspace as input, a back EMF observer is constructed, and the observed back EMF is fed into a phase-locked loop to accurately calculate the rotor position and speed information.

[0038] Steps (2), (3), (4) and (5) together constitute the sensorless control method for dual three-phase permanent magnet synchronous motors proposed in this invention, which is also the core link of this invention to achieve fault-tolerant operation without diagnosis under fault conditions.

[0039] The core of this invention lies in achieving high-precision rotor position estimation under phase loss faults without the need for fault diagnosis. To fully verify the technical effectiveness of the sensorless control scheme proposed in this invention, an extremely rigorous multi-fault transient test condition was employed: the motor operates from a healthy state → switches to a single-phase open-circuit fault operation in phase A (lasting 1 second) → switches to a single-phase open-circuit fault operation in phase C (lasting 1 second) → then returns to a healthy state. Throughout the entire process involving multiple fault occurrences, the motor drive system consistently employs the same fixed sensorless control strategy, requiring no adjustments, reconfigurations, or mode switching. A comparative analysis of experimental results between traditional methods and the scheme proposed in this invention is as follows: Figure 2 and Figure 3 As shown. A key advantage of the proposed solution is that it does not rely on diagnostic information, employs a universal control topology, and ensures a seamless transition between healthy operation and single-phase open-circuit fault operation. This solution does not contain any fault detection logic, requires no comparison of current amplitude, phase, or symmetry, no threshold judgment, and does not involve any if-else structures for fault identification or adaptive adjustment.

[0040] Experimental results clearly demonstrate that during the transient process of switching between healthy operation and multiple single-phase open-circuit faults, the position error of the sensorless solution proposed in this invention remains continuously smooth, without significant jumps or abrupt changes. Even under extreme conditions—such as consecutive faults in two adjacent phases—its position estimation still maintains high accuracy and stability. This provides clear experimental evidence for the core advantage of the diagnostic-free design concept—that it is entirely possible to eliminate the need for a dedicated fault location and reconstruction mechanism while retaining excellent estimation accuracy, further verifying the superiority of the method of this invention.

Claims

1. A diagnostic-free, sensorless control method for a dual three-phase permanent magnet synchronous motor compatible with single-phase open-circuit faults, characterized in that... The method includes the following steps: Step (1) The collected six-phase current of the dual three-phase permanent magnet synchronous motor is decoupled into current components in torque subspace and harmonic subspace by vector space decoupling transformation. Step (2) Use a second-order generalized integrator to perform frequency separation of the current in the harmonic subspace; Step (3) extracts the 5th and 7th harmonic current components. As the feedback value of the current regulator in the harmonic subspace Used to generate harmonic suppression voltage ; Step (4) uses the extracted fundamental frequency current component As input, the required estimated compensation voltage is estimated by using a fault model observer that considers voltage constraints; Step (5) superimposes the harmonic suppression voltage and the estimated compensation voltage calculated in steps (3) and (4) respectively into the harmonic subspace; Step (6) combines the collected inverter DC bus voltage with The shaft current regulator command voltage is calculated. The command voltage of the shaft is used as input; the command voltage and current signal of the torque subspace are used as input to construct a back EMF observer, and the observed back EMF is sent to the phase-locked loop to accurately calculate the rotor position and speed information.

2. The diagnostic-free sensorless control method for a dual three-phase permanent magnet synchronous motor compatible with single-phase open-circuit faults according to claim 1, characterized in that... The current components of the torque subspace and harmonic subspace are represented as follows: In the formula, , , and These are the currents in the torque subspace and harmonic subspace, respectively. , , , , and The results are the six-phase current sampling results of a dual three-phase permanent magnet synchronous motor.

3. The diagnostic-free sensorless control method for a dual three-phase permanent magnet synchronous motor compatible with single-phase open-circuit faults according to claim 1, characterized in that... The harmonic suppression voltage is expressed as: In the formula, and In the harmonic subspace The proportional and integral coefficients of the shaft current regulator; for Reference current of the shaft current regulator.

4. The diagnostic-free sensorless control method for a dual three-phase permanent magnet synchronous motor compatible with single-phase open-circuit faults according to claim 1, characterized in that... The estimated compensation voltage is expressed as: In the formula, and These are the resistance and leakage inductance of the permanent magnet synchronous motor, respectively. represent Estimated compensation voltage for the shaft, Represents the independent variable in the discrete domain. The switching cycle.

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