Driving motor system current sensor abnormity identification and fault-tolerant control method and device

Abstract

The invention provides a comprehensive anomaly recognition and fault-tolerant control method based on current sensor fault modeling, offset coordinate system transformation, a full-order sliding-mode observer and current space vector error projection, which comprises an innovative algorithm for accurately modeling and classifying various typical faults and carrying out fault detection and positioning by using the models. Based on a current sensor fault detection strategy of an offset coordinate system, through specific Clark transformation and coordinate offset, in combination with current residual amplitude reconstruction and hysteresis comparison, a reconstruction error is obtained through reconstruction of a current space vector error and projection, a sliding mode surface is formed by the reconstruction error and a measurement error, and accurate reconstruction of fault phase current is achieved. According to the method, various fault types and positions thereof can be accurately identified, the faults can be more accurately positioned, and the accuracy of fault detection is improved. When the current sensor breaks down, fault phase current can be effectively reconstructed, stable operation of the system is guaranteed, and better dynamic performance and control precision are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control detection, and in particular relates to a method and device for abnormality identification and fault-tolerant control of a current sensor of a drive motor system. Background Art

[0002] In the drive motor system, the current sensor is susceptible to interference or other factors and may fail, such as offset failure, stuck / disconnected fault, gain failure, etc. These failures may cause the system to fail to operate normally and even cause safety problems. It is necessary to accurately identify the abnormal conditions of the current sensor, including the fault type and fault location, to improve the reliability and safety of the system. When the current sensor is abnormal, the fault-tolerant control method in the prior art has many shortcomings, such as large amount of calculation and high requirements on processor performance, which is difficult to implement in the actual system, unsatisfactory control effect, poor transient performance, low control accuracy and other problems.

[0003] With the development of control theory and the update of components, permanent magnet synchronous motor (PMSM) drive systems have been widely used in many fields because of their advantages such as high power factor, high efficiency and high torque density. In these drive systems, current sensors are one of the key components used to collect motor current information to achieve precise control and protection functions.

[0004] However, the actual application scenarios are complex and changeable, and the motor system faces various working conditions, such as temperature changes, vibrations, electromagnetic interference, etc. These factors pose a threat to the normal operation of the current sensor, increasing the probability of its failure, thereby affecting the performance and reliability of the entire drive system. In the PMSM drive system without position sensor control, the failure problem of the current sensor is particularly prominent. At least two stator AC current sensors are required to achieve current closed-loop control, but in some cases, such as limited space, it is inconvenient to install too many sensors, and the current sensor itself is easily disturbed by unknown reasons during operation and fails, resulting in inaccurate feedback current information, which may cause the system to fail to operate normally. For example, when the current sensor fails, it may cause subsequent position observation and speed control to fail, the current loop feedback is inaccurate, and ultimately lead to system crash.

[0005] Existing technical solutions: At present, some patents have proposed methods for current sensor abnormality identification and fault-tolerant control. For example, CN202311138084.0, according to the flag bit to form a state quantity, according to the state quantity to determine the phase failure fault; CN202411120399.7, through the collected three-phase current, the phase current of different phases is obtained, the mathematical relationship of the phase current is established, and the mathematical model is used to detect whether there is an open circuit fault in the three-phase motor current sensor; CN202111400083.X, the controller given value is used as the replacement value of the abnormal feedback value after transformation, that is, according to the principle of inverse Park transformation, the dq axis current given value under the two-phase rotating coordinate is used to obtain the current estimation value under the axis, and the abnormal value of the α or β axis current is selectively replaced according to the specific fault type; CN201710237740.0, based on the model reference adaptive system (MRAS) observer of motor speed and resistance identification, the estimated rotor speed and resistance are sent to the decision unit to identify whether the motor position sensor is faulty, which has a certain fault tolerance.

[0006] However, the existing methods have the following disadvantages: In terms of fault detection: the model-based method is greatly affected by changes in motor parameters, and parameter design is difficult, resulting in limited accuracy and reliability; the signal-based method is complex to calculate, has poor real-time performance, and is difficult to apply in actual systems; the knowledge-based method is highly data-dependent, difficult to build, slow to converge, and difficult to integrate into the main control chip.

[0007] In terms of fault-tolerant control: simple switching control sacrifices accuracy and stability; the single current sensor sampling algorithm has problems such as high hardware cost, complex algorithm or poor versatility; the reconstructed current method has shortcomings such as poor transient performance, low accuracy, and great influence of parameters. Summary of the invention

[0008] In view of this, in order to solve the problems of limited accuracy of current sensor fault detection and poor versatility and low precision of fault-tolerant control, the present invention proposes a method for abnormal identification and fault-tolerant control of current sensors in drive motor systems. This method models common faults of current sensors, theoretically analyzes their impact on the motor drive system, combines simulation results (such as current, torque, and speed waveform analysis under different faults), summarizes the system current characteristics after the fault as a basis for judgment, and selects typical faults for fault detection based on the offset coordinate system. Through the design of the current observer, fault-tolerant control is performed based on the current space vector error projection. In order to achieve the above purpose, the technical solution adopted by the present invention is: A method for abnormal identification and fault-tolerant control of a current sensor of a drive motor system, comprising a current sensor fault detection method and a fault-tolerant control method based on current space vector error projection; If a current sensor fault is detected, executing the fault-tolerant control based on current space vector error projection; The current sensor fault detection comprises the following steps: The three-phase current is converted into a first stationary coordinate system and a second stationary coordinate system by using a coordinate transformation method; According to the motor position information, the reference current is obtained through the coordinate transformation formula; Compare the reference current with the measured current to obtain a residual signal; Reconstructing the residual signal amplitude; The reconstructed amplitude is compared with a threshold value to evaluate the working state of the phase current sensor; The fault-tolerant control based on current space vector error projection comprises the following steps: Construct a full-order adaptive stator current sliding mode observer; The reconstruction error is used as a correction term of the current sliding mode observer and input into the current sliding mode observer; The current sliding mode observer reconstructs the fault phase current according to the input correction term and circuit parameters to obtain the estimated value of the fault phase current; The reconstructed fault phase current replaces the measurement signal and participates in the closed-loop fault-tolerant control.

[0009] Specifically, the coordinate transformation adopts Clark transformation.

[0010] Specifically, a hysteresis loop is set while reconstructing the amplitude of the residual signal to improve the anti-interference capability.

[0011] Specifically, a low-pass filter is set while replacing the measurement signal.

[0012] In a second aspect, a device for abnormal identification and fault-tolerant control of a current sensor of a drive motor system is provided, comprising a current sensor fault detection module and a fault-tolerant control module based on current space vector error projection; Wherein, if a current sensor fault is detected, the fault-tolerant control module based on current space vector error projection starts to work; The current sensor fault detection module is used for: The three-phase current is converted into a first stationary coordinate system and a second stationary coordinate system by using a coordinate transformation method; According to the motor position information, the reference current is obtained through the coordinate transformation formula; Compare the reference current with the measured current to obtain a residual signal; Reconstructing the residual signal amplitude; The reconstructed amplitude is compared with a threshold value to evaluate the working state of the phase current sensor; The fault-tolerant control module based on current space vector error projection is used for: A full-order adaptive stator current sliding mode observer is constructed through one-phase current; The reconstruction error is used as a correction term of the current sliding mode observer and input into the current sliding mode observer; The current sliding mode observer reconstructs the fault phase current according to the input correction term and circuit parameters to obtain the estimated value of the fault phase current; The reconstructed fault phase current replaces the measurement signal and participates in the closed-loop fault-tolerant control.

[0013] In a third aspect, a drive motor system is provided, comprising an inverter, a drive motor, a control system, a plurality of signal sensors, and also comprising a drive motor system current sensor abnormality identification and fault-tolerant control device as described in the second aspect.

[0014] Beneficial effects of the present invention: 1. The present invention can accurately identify various fault types and their locations, locate faults more accurately, and improve the accuracy of fault detection by modeling and classifying current sensor faults in detail and combining them with a fault detection method based on an offset coordinate system.

[0015] 2. The fault-tolerant control strategy proposed in the present invention is based on a full-order sliding mode observer and current space vector error projection. When a current sensor fails, it can effectively reconstruct the fault phase current, ensure stable operation of the system, and have better dynamic performance and control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention has the following accompanying drawings: Figure 1 An overall structural block diagram of a high-power electromechanical composite transmission drive motor system according to an embodiment of the present invention; Figure 2 Example of current reference value transformation along phase a; Figure 3 Current sensor fault diagnosis and fault tolerance flow chart; Figure 4 Fault-tolerant control flow chart. DETAILED DESCRIPTION

[0017] In order to make the objects, advantages and features of the present invention more obvious, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 In a specific embodiment, a high-power electromechanical hybrid transmission drive motor system is composed of the following parts: 1' inverter, 2' drive motor, 3' control system and various signal sensors. Indicates the DC bus voltage; , ( , the same below) are the inverter upper and lower bridge arm power switch tubes respectively, , They are the freewheeling diodes of the upper and lower bridge arm power switch tubes respectively; PMSM stands for permanent magnet synchronous drive motor; CTA stands for current sensor, which is installed on phase a and phase b respectively and is used to collect motor current signals; Resolver stands for position sensor, whose main task is to decode the rotor position and speed information of the motor for motor vector control. Figure 1 As shown in 4', the system also includes two modules, 4.1' is current sensor fault detection, and 4.2' is fault-tolerant control based on current space vector error projection, which are coupled with other parts.

[0019] The functions and implementation methods of each part are described in detail below: 4.1' Current sensor fault detection part: Select the A axis of the three-phase coordinate system as the reference of the two-phase stationary coordinate system, and the sensor samples the A and B two-phase current signals. Through the Clark transformation formula: Select the coordinate transformation method to diagnose the fault of the current sensor. Using this method, the abc three-phase current needs to be converted to coordinate system. It should be pointed out that when When the position of the shaft is different, the selected Clark transformation formula is also different. On the other hand, in practical applications, the traction motor usually contains only two current sensors, which can be assumed to be located on phases a and b respectively. , then the c-phase current Available a, b two-phase current and In this case, the coordinate transformation is simplified to and Project to Take the case where the α-axis coincides with the a-phase. At this time, the three-phase stationary coordinate system abc is converted to the two-phase stationary coordinate system The transformation diagram is shown in Figure 2. At this time, the Clark transformation formula is as shown in the formula:

[0020] The first stationary coordinate system: select the A axis of the three-phase coordinate system as the reference of the two-phase stationary coordinate system. When the axis of the axis coincides with phase a, this coordinate system is used to diagnose the fault of the current sensor. In this coordinate system, the abc three-phase current is converted to In the coordinate system, coordinate transformation and calculation of the current residual signal are performed to evaluate the working status of the phase A current sensor.

[0021] Second stationary coordinate system: By offsetting the stationary coordinate system by 120 degrees, its reference axis system The A axis overlaps with the B axis in the stationary three-phase reference system to obtain a coordinate system. In this coordinate system, the Clark transformation is also used to perform coordinate transformation to detect the working state of the B phase current sensor.

[0022] According to the motor position information (provided by the position observer), the reference current is obtained through the coordinate transformation formulas (2) and (3), and then compared with the measured current to obtain the residual signal.

[0023] ; ; For other faults except offset fault, the residual signal is an AC signal, and its amplitude needs to be reconstructed. For example, the absolute value operation is performed first in equation (4).

[0024] ;

[0025] As shown in formula (5), the alternating current residual signal is processed into a positive signal, and then the error of the residual signal is obtained through the heterodyne method.

[0026] ;

[0027] in, They represent the actual value and estimated value of the current residual signal amplitude respectively, which are input into the PI controller to converge to obtain the residual amplitude, and the reconstructed amplitude is compared with the threshold to realize fault detection and location.

[0028] Preferably, a hysteresis loop (such as 0.5A width) can be set at the same time to improve the anti-interference capability.

[0029] Similarly, in different In the phase coordinate system, the coordinate transformation is obtained The algorithm flow chart of current sensor fault diagnosis based on these 8 values ​​is as follows: Figure 3 shown.

[0030] The fault detection process is as follows: start.

[0031] Coordinate transformation is performed in the first stationary coordinate system to obtain the measured value and reference value of the current, and the amplitude of the current residual signal is obtained through amplitude calculation, which is compared with the threshold to evaluate the working state of the A-phase current sensor. If the residual signal amplitude exceeds the preset fault reference deviation value, the A-phase current sensor is deemed to be failed; if the comparison result is within the allowable deviation range, the sensor is deemed to be working normally.

[0032] The current residual signal amplitude obtained in the second stationary coordinate system is compared with the threshold value. If the residual signal amplitude exceeds the preset fault reference deviation value, it is determined that the B-phase current sensor fails; if the comparison result is within the allowable deviation range, it is determined that the sensor is working normally.

[0033] Combining the above results, we get the working state combination of the four sensors, and then we are done.

[0034] 4.2' Fault-tolerant control based on current space vector error projection: Once a current sensor failure is detected, the system will automatically switch to fault-tolerant control mode. A full-order adaptive stator current observer is constructed through one-phase current, and an analog sensor is constructed after the current sensor failure. The current errors of the α and β axes in the stationary coordinate system are considered and introduced into the full-order adaptive stator current observer to obtain satisfactory control performance.

[0035] Assuming that the current sensor of phase B is faulty, establish the current sliding mode observer: ; ;

[0036] in: ; ; ; ; ; ;

[0037] To obtain accurate reconstructed phase current error , first reconstruct the current space vector error , through a specific formula: ; ;

[0038] Using heterodyne method: ;

[0039] By extracting and controlling Converges to zero and obtains the current space vector error The phase current error is then reconstructed according to the above relationship . It is used as the correction term of the current sliding mode observer to obtain the fault phase current , replacing the measurement signal for closed-loop fault-tolerant control.

[0040] Preferably, a low-pass filter (LPF) can be set to attenuate the output pulsation caused by the proportional link in the PI controller, and its cut-off frequency can be set higher (e.g. ) to reduce the negative impact of phase delay on current error reconstruction.

[0041] The fault-tolerant control process is as follows: The reconstruction error is used as a correction term of the current sliding mode observer and is input into the current sliding mode observer.

[0042] The current sliding mode observer reconstructs the fault phase current according to the input correction term and other related parameters (such as α-axis current, voltage, etc.) to obtain the estimated value of the fault phase current.

[0043] The reconstructed fault phase current replaces the measurement signal and participates in the closed-loop fault-tolerant control, thereby realizing the control of the drive motor system and ensuring that the system can still operate stably and efficiently when the current sensor is abnormal, and has good dynamic performance and control accuracy.

[0044] By setting a low-pass filter (LPF), the cut-off frequency can be set higher (such as 300Hz) to attenuate the output pulsation caused by the proportional link in the PI controller, reduce the negative impact of phase delay on current error reconstruction, and further optimize the fault-tolerant control effect.

[0045] It should be noted that any process or method description in the embodiments may be understood as representing a module, fragment or portion of a code including one or more executable instructions for implementing steps of a specific logical function or process, and that the scope of the preferred embodiments of the present invention includes alternative implementations in which the functions may not be performed in the order shown or discussed, including performing the functions in a substantially simultaneous manner or in the reverse order according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0046] It should be noted that the logic and / or steps in the embodiments, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or equipment (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or equipment and execute instructions), or in combination with these instruction execution systems, devices or equipment. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or equipment, or in combination with these instruction execution systems, devices or equipment. More specific examples of computer-readable media (non-exhaustive list) include the following: an electrical connection with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0047] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0048] A person skilled in the art may understand that all or part of the steps of implementing the above-mentioned embodiment method may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one of the steps of the method embodiment or a combination thereof.

[0049] In addition, each functional module in the embodiment of the present invention may be integrated into a processing module, or each module may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0050] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0051] The above embodiments describe the technical solutions of the present invention in detail. Obviously, the present invention is not limited to the described embodiments. Based on the embodiments of the present invention, people familiar with the technical field can also make various changes accordingly, but any changes that are equivalent or similar to the present invention belong to the scope of protection of the present invention.

[0052] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for abnormal identification and fault-tolerant control of a current sensor in a drive motor system, characterized in that: Including current sensor fault detection method, fault-tolerant control method based on current space vector error projection; If a current sensor fault is detected, executing the fault-tolerant control based on current space vector error projection; The current sensor fault detection comprises the following steps: The three-phase current is converted into a first stationary coordinate system and a second stationary coordinate system by using a coordinate transformation method; According to the motor position information, the reference current is obtained through the coordinate transformation formula; Compare the reference current with the measured current to obtain a residual signal; Reconstructing the residual signal amplitude; The reconstructed amplitude is compared with a threshold value to evaluate the working state of the phase current sensor; The fault-tolerant control based on current space vector error projection comprises the following steps: Construct a full-order adaptive stator current sliding mode observer; The reconstruction error is used as a correction term of the current sliding mode observer and input into the current sliding mode observer; The current sliding mode observer reconstructs the fault phase current according to the input correction term and circuit parameters to obtain the estimated value of the fault phase current; The reconstructed fault phase current replaces the measurement signal and participates in the closed-loop fault-tolerant control.

2. The control method according to claim 1, characterized in that: The coordinate transformation adopts Clark transformation.

3. The control method according to claim 1, characterized in that: The hysteresis loop is set while reconstructing the amplitude of the residual signal to improve the anti-interference capability.

4. The control method according to claim 1, characterized in that: The replacement measurement signal is simultaneously provided with a low-pass filter.

5. A device for abnormal identification and fault-tolerant control of a current sensor in a drive motor system, characterized in that: It includes a current sensor fault detection module and a fault-tolerant control module based on current space vector error projection; Wherein, if a current sensor fault is detected, the fault-tolerant control module based on current space vector error projection starts to work; The current sensor fault detection module is used for: The three-phase current is converted into a first stationary coordinate system and a second stationary coordinate system by using a coordinate transformation method; According to the motor position information, the reference current is obtained through the coordinate transformation formula; Compare the reference current with the measured current to obtain a residual signal; Reconstructing the residual signal amplitude; The reconstructed amplitude is compared with a threshold value to evaluate the working state of the phase current sensor; The fault-tolerant control module based on current space vector error projection is used for: A full-order adaptive stator current sliding mode observer is constructed through one-phase current; The reconstruction error is used as a correction term of the current sliding mode observer and input into the current sliding mode observer; The current sliding mode observer reconstructs the fault phase current according to the input correction term and circuit parameters to obtain the estimated value of the fault phase current; The reconstructed fault phase current replaces the measurement signal and participates in the closed-loop fault-tolerant control.

6. A drive motor system, comprising an inverter, a drive motor, a control system, and a plurality of signal sensors, characterized in that: It also includes a drive motor system current sensor abnormality identification and fault-tolerant control device as described in claim 5.

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