Permanent magnet synchronous motor locked-rotor detection method and device and electronic equipment

Abstract

The invention provides a permanent magnet synchronous motor locked-rotor detection method and device and electronic equipment, and belongs to the technical field of motor detection. Alpha-beta current and voltage can be obtained based on three-phase current conversion of the motor; obtaining an actual induced voltage under the dq coordinate system through a motor observer; based on the electrical angular velocity and the motor constant of the motor, obtaining a theoretical induced voltage under a non-locked-rotor condition; and judging whether the motor is locked or not according to the difference between the actual induced voltage and the theoretical induced voltage. When locked-rotor occurs, signals of the stator and the rotor are asynchronous, the actual rotating speed of the rotor is reduced, and the induced voltage generated by the rotor on the stator is reduced, namely, the actual induced voltage is reduced, and the difference between the actual induced voltage and the theoretical induced voltage is increased, so that whether the motor is locked or not can be judged. Compared with an existing mode, such as rotating speed threshold judgment or current threshold judgment, the sensitivity of induced voltage change is higher, so that the speed of the induced voltage locked-rotor judgment mode is higher, and the locked-rotor detection efficiency is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of motor detection, and in particular to a method, device and electronic equipment for detecting stalled rotor of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors, such as PMSM, oil pumps, air pumps, fans, air conditioning compressors, etc., are important equipment widely used in industrial and civil fields. The performance stability during operation directly affects production efficiency and safety. In actual operation, stalling may occur due to various reasons, that is, the rotor stops rotating (including complete stop, semi-stalled shaking state, mild stalled very low speed rotation state) while the motor continues to run, which will not only cause equipment damage, but also may cause serious accidents. Therefore, the application of stall detection technology becomes crucial.

[0003] At present, the existing technology usually calculates the required value based on the motor speed, current change amplitude, the duration of the current greater than the set threshold current, or by real-time monitoring of the motor current, DC bus voltage and rotor speed and other parameters and sampling, and judges with the set value, that is, the threshold of the normal operating range, and then determines whether it is a stalled state. Taking the existing speed judgment logic as an example, when the PMSM speed is less than the speed threshold and the current consumption is greater than the stall current threshold, it is judged to be stalled. On the one hand, the existing method requires a large number of sensors to collect data, analog-to-digital conversion, and filtering to indirectly judge the stall. On the other hand, the sensitivity of the speed or current threshold judgment is low, which leads to slow stall detection speed and low efficiency. Summary of the invention

[0004] The present invention provides a permanent magnet synchronous motor stall detection method, device and electronic equipment to solve the problems of slow speed and low efficiency of existing stall detection methods.

[0005] In a first aspect, the present invention provides a method for detecting a stalled permanent magnet synchronous motor, comprising: obtaining the three-phase current, electrical angular velocity and induced voltage constant of the motor; based on the three-phase current in a three-phase coordinate system, coordinate transformation obtains the α-axis current and β-axis current in a two-phase stationary coordinate system, and obtains the α-axis stator voltage and the β-axis stator voltage; based on the α-axis current, β-axis current, α-axis stator voltage and β-axis stator voltage, based on motor observer estimation, obtains the actual induced voltage in a synchronous rotating coordinate system; based on the electrical angular velocity and the induced voltage constant, obtains the theoretical induced voltage in a non-stalled state; based on the difference between the actual induced voltage and the theoretical induced voltage and a preset difference threshold, determines whether the motor is stalled.

[0006] In a possible implementation, obtaining the three-phase current of the motor includes: using a single-resistance sampling method or a dual-resistance sampling method to obtain any two-phase current of the motor; based on the any two-phase current, reconstructing the current according to Kirchhoff's law to obtain the third-phase current.

[0007] In a possible implementation, the coordinate transformation based on the three-phase current in the three-phase coordinate system to obtain the α-axis current and β-axis current in the two-phase stationary coordinate system, and the α-axis stator voltage and β-axis stator voltage include: based on the three-phase current in the three-phase coordinate system, the coordinate transformation to obtain the α-axis current and β-axis current in the two-phase stationary coordinate system; based on the α-axis current and β-axis current, the coordinate transformation to obtain the d-axis current and q-axis current in the synchronous rotating coordinate system; based on the d-axis current and q-axis current, the d-axis stator voltage and q-axis stator voltage are obtained through the stator voltage equation; based on the d-axis current and q-axis current, the coordinate transformation to obtain the α-axis stator voltage and β-axis stator voltage in the stationary coordinate system.

[0008] In a possible implementation, the stator voltage equation is:

[0009]

[0010] Among them, u d is the d-axis stator voltage; u q is the shaft stator voltage; ω e is the electrical angular velocity; ψ d , q are the d-axis and q-axis components of the three-phase stator flux respectively; p is the differential operator; i d is the d-axis current; i q is the q-axis current; R is the stator resistance; where ψ d , q The stator flux equation is obtained as follows:

[0011]

[0012] Among them, L d , L q is the d-axis and q-axis components of the three-phase stator inductance, ψ f Rotor permanent magnet flux.

[0013] In one possible implementation, obtaining the actual induced voltage in the synchronous rotating coordinate system based on the motor observer and the α-axis current, β-axis current, α-axis stator voltage and β-axis stator voltage includes: obtaining the α-axis back electromotive force and the β-axis back electromotive force based on the motor observer and the α-axis current, β-axis current, α-axis stator voltage and β-axis stator voltage; obtaining the actual induced voltage in the synchronous rotating coordinate system based on the α-axis back electromotive force and the β-axis back electromotive force.

[0014] In a possible implementation, estimating the α-axis back electromotive force and the β-axis back electromotive force based on the motor observer according to the α-axis current, the β-axis current, the α-axis stator voltage, and the β-axis stator voltage includes:

[0015] The α-axis back EMF and β-axis back EMF are obtained based on the following formulas:

[0016]

[0017] Among them, U α is the α-axis stator voltage; U β is the β-axis stator voltage; E α is the α-axis back electromotive force; E β is the β-axis back electromotive force.

[0018] In a possible implementation, obtaining the theoretical induced voltage in a non-locked rotor condition based on the electrical angular velocity and the induced voltage constant includes:

[0019] The theoretical induced voltage under non-locked rotor conditions is obtained based on the following formula:

[0020] E2=K e *ω e +K d

[0021] Where, E2 is the theoretical induced voltage; K e is the induced voltage constant; K d is a fixed induction voltage offset.

[0022] In a second aspect, the present invention provides a permanent magnet synchronous motor stall detection device, comprising: an acquisition module, used to acquire the three-phase current, electrical angular velocity and induced voltage constant of the motor; a conversion module, used to obtain the α-axis current and β-axis current in a two-phase stationary coordinate system based on the three-phase current in the three-phase coordinate system, and obtain the α-axis stator voltage and the β-axis stator voltage; a first acquisition module, used to obtain the actual induced voltage in a synchronous rotating coordinate system based on the α-axis current, β-axis current, α-axis stator voltage and β-axis stator voltage, based on the motor observer estimation; a second acquisition module, used to obtain the theoretical induced voltage in a non-stalled condition based on the electrical angular velocity and the induced voltage constant; a judgment module, used to judge whether the motor is stalled based on the difference between the actual induced voltage and the theoretical induced voltage and a preset difference threshold.

[0023] In a third aspect, the present invention provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the processor implements the steps of the method described in the first aspect or any possible implementation manner of the first aspect.

[0024] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in the first aspect or any possible implementation of the first aspect are implemented.

[0025] The present invention provides a permanent magnet synchronous motor stall detection method, device and electronic equipment. The present invention obtains αβ current and αβ stator voltage based on the three-phase current transformation of the motor; then obtains the actual induced voltage in the dq coordinate system through the motor observer based on the αβ current and αβ stator voltage; obtains the theoretical induced voltage in the non-stalled state based on the electrical angular velocity and motor constant of the motor; and judges whether the motor is stalled according to the difference between the actual induced voltage and the theoretical induced voltage. Specifically, when stall occurs, the stator and rotor signals are not synchronized, the actual rotor speed decreases, and the induced voltage generated by the rotor on the stator decreases, that is, the actual induced voltage decreases, and the difference between the actual induced voltage and the theoretical induced voltage increases, thereby judging whether the motor is stalled. Compared with existing methods, such as speed threshold judgment or current threshold judgment, the sensitivity of the induced voltage change is higher, so the speed of the induced voltage stall judgment method is faster and the stall detection efficiency is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 is an application scenario diagram of a permanent magnet synchronous motor stall detection method provided by an embodiment of the present invention;

[0028] Figure 2 It is a flow chart of an implementation method of a permanent magnet synchronous motor stall detection method provided by an embodiment of the present invention;

[0029] Figure 3 It is a structural schematic diagram of a motor stall detection system during the implementation of the present invention;

[0030] Figure 4 This is a motor stall determination block diagram provided by an embodiment of the present invention;

[0031] Figure 5 It is a main flow chart of the motor stall detection method provided by the present invention;

[0032] Figure 6 It is a structural schematic diagram of a permanent magnet synchronous motor stall detection device provided by an embodiment of the present invention;

[0033] Figure 7 is a schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0036] Figure 1 This is an application scenario diagram of the permanent magnet synchronous motor stall detection method provided by the embodiment of the present invention. Figure 1 As shown, the permanent magnet synchronous motor works under the drive of three-phase alternating current, for example, the permanent magnet synchronous motor is driven by the a-phase, b-phase and c-phase alternating current in the figure. The controller can collect motor parameters and control the operation of the motor. The controller can include both hardware parts and software parts, for example, a control strategy or a detection method can be executed. For another example, in this solution, the permanent magnet synchronous motor stall detection method can be executed in the controller.

[0037] The embodiments of the present invention can be applied to a variety of application scenarios, which involve detection of stall of a permanent magnet synchronous motor, and the specific application scenarios are not limited here. For example, the motor can be a fan motor or an air conditioner compressor motor.

[0038] When a permanent magnet synchronous motor drives a load, it may experience a stall problem. Stalls include a complete stop of the rotor, a semi-stalled state with a shaky rotor, and a mild stalled state with a very low speed, while the motor continues to run. Existing stall detection methods include speed detection or current detection.

[0039] Taking the current mainstream speed judgment logic as an example, when the speed of the permanent magnet synchronous motor is less than the speed threshold and the current consumption is greater than the stall current threshold, it is judged to be stalled. However, since the load changes with the external environment, there will be a sudden increase in load demand, the speed will drop in a short time, the current will increase, and the control response will take time, that is, the detection method has a certain hysteresis and will be misjudged as stalled. The above judgment method relies on the processing of the motor sampling current, but stalling is often accompanied by the occurrence of overcurrent faults. If the stall is not judged and protected in time, the system will mistakenly trigger an overcurrent fault. On the one hand, the existing method requires a large number of sensors to collect data, analog-to-digital conversion, and filtering to indirectly judge the stall. On the other hand, the sensitivity of the speed or current threshold judgment is low, which leads to slow stall detection speed and low efficiency.

[0040] Most existing methods use sensors for sampling. On the one hand, sensors increase equipment costs. On the other hand, they make indirect judgments based on the data collected by the sensors, which affects reliability. For example, the speed threshold judgment method requires a position sensor to be installed on the motor to monitor the actual speed. This requires that the motor be equipped with a position sensor, which limits the scope of application of the method. For another example, the current threshold judgment method requires three current sensors to be installed on the motor to monitor the three-phase real-time current. Moreover, the current threshold judgment method requires that the motor be over-currented before it can detect stalling, and the detection speed is slow.

[0041] The embodiment of the present invention provides a permanent magnet synchronous motor stall detection method, which determines the stall of the permanent magnet synchronous motor based on an induced electromotive force error, so as to solve the problems of slow speed and low efficiency of the existing stall detection method.

[0042] Figure 2 is a flowchart of a method for detecting stalled permanent magnet synchronous motor provided by an embodiment of the present invention, referring to Figure 2 , as detailed below:

[0043] In step 201, the three-phase current, electrical angular velocity and induced voltage constant of the motor are obtained.

[0044] Exemplarily, the motor is a permanent magnet synchronous motor. For example, the motor can be a sensorless permanent magnet synchronous motor. It should be noted that the sensorless permanent magnet synchronous motor here refers to a permanent magnet synchronous motor without a mechanical position sensor. Mechanical position sensors generally include photoelectric encoders or rotary transformers. The stall detection method of the embodiment of the present invention does not require a mechanical position sensor, reduces hardware dependence, and improves applicability. The following describes how to obtain each parameter.

[0045] In a possible implementation, obtaining the three-phase current of the motor includes: using a single-resistance sampling method or a dual-resistance sampling method to obtain any two-phase current of the motor; based on any two-phase current, reconstructing the current according to Kirchhoff's law to obtain the third-phase current.

[0046] It should be noted that according to Kirchhoff's law, the sum of the three-phase currents at the same time is 0. That is, I a +I b +I c =0. Therefore, the current reconstruction can be performed based on any two-phase current to obtain the third-phase current. In some embodiments, after the permanent magnet synchronous motor operates normally, the controller collects the three-phase current I a ,I b ,I c Any two-phase current I a and I b , then I c By calculating I c =-(I a +I b The embodiment of the present invention collects two-phase currents for current reconstruction, which reduces the use of sensors compared to the current threshold judgment which requires real-time collection of three-phase actual currents.

[0047] In one possible implementation, the electrical angular velocity of the motor is obtained based on the motor observer. Exemplarily, the motor observer may include a synovial observer, a Romberg observer or an adaptive observer, etc. Here, the motor observer is essentially at the software algorithm level, not a physical sensor. The motor observer algorithm can be executed in the motor controller. The motor observer can estimate the rotor position information, that is, the electrical angular velocity can be obtained. It should be noted that when the rotor rotates one circle, the mechanical angle is equal to 360°, and the electrical angle is equal to the number of pole pairs * 360. The electrical angle can be understood as the sum of the angles rotated by all pole pairs. That is, under normal operation, the mechanical speed of the rotor is not exactly the same as the electrical angular velocity, but correspondingly, there is a linear relationship. The embodiment of the present invention obtains the electrical angular velocity of the motor through the motor observer, which avoids the use of a mechanical position sensor to monitor the speed. Please note that in the embodiment of the present invention, the electrical angular velocity is used as an intermediate quantity to obtain the induced voltage, and is not directly used to judge the stall.

[0048] The induced voltage constant is the inherent value of the motor, also called the back electromotive force constant, with the unit of V / (rad / s). It is a parameter that measures the ability of a coil or winding to convert magnetic flux into voltage. Therefore, in a possible implementation, the induced voltage constant is obtained based on the inherent characteristics of the permanent magnet synchronous motor.

[0049] In step 202, based on the three-phase current in the three-phase coordinate system, coordinate transformation is performed to obtain the α-axis current and the β-axis current in the two-phase stationary coordinate system, and the α-axis stator voltage and the β-axis stator voltage are obtained.

[0050] In some embodiments, based on the three-phase current in the three-phase coordinate system, the α-axis current and the β-axis current in the two-phase stationary coordinate system can be obtained through CLARK coordinate transformation. Exemplarily, the α-axis current and the β-axis current are obtained based on the following formula:

[0051]

[0052] Among them, i a 、i b 、i c Represents the three-phase current in the three-phase coordinate system; i α represents the α-axis current; i β represents the β-axis current.

[0053] During the operation of the permanent magnet synchronous motor, there is a correlation between current and voltage. For example, the electromagnetic relationship of the permanent magnet synchronous motor can be described by a voltage equation. The voltage equation reflects the relationship between the stator voltage and current. Therefore, in some embodiments, based on the three-phase current in the three-phase coordinate system, the α-axis stator voltage and the β-axis stator voltage can be obtained. The following is a comprehensive embodiment to illustrate step 202.

[0054] In a possible implementation, based on the three-phase current in the three-phase coordinate system, coordinate transformation to obtain the α-axis current and the β-axis current in the two-phase stationary coordinate system, and obtaining the α-axis stator voltage and the β-axis stator voltage include:

[0055] Step 2021: Based on the three-phase current in the three-phase coordinate system, coordinate transformation is performed to obtain the α-axis current and the β-axis current in the two-phase stationary coordinate system.

[0056] Step 2022: Based on the α-axis current and the β-axis current, coordinate transformation is performed to obtain the d-axis current and the q-axis current in the synchronous rotating coordinate system.

[0057] Exemplarily, coordinate transformation is performed based on the following formula to obtain the d-axis current and the q-axis current in the synchronous rotating coordinate system:

[0058]

[0059] Among them, θ e Indicates the electrical angle. For example, the electrical angle at the current moment can be obtained based on the motor observer.

[0060] Step 2023, based on the d-axis current and the q-axis current, obtain the d-axis stator voltage and the q-axis stator voltage through the stator voltage equation;

[0061] In some embodiments, the stator voltage equation is:

[0062]

[0063] Among them, ud is the d-axis stator voltage; u q is the shaft stator voltage; ω e is the electrical angular velocity; ψ d , q are the d-axis and q-axis components of the three-phase stator flux respectively; p is the differential operator; i d is the d-axis current; i q is the q-axis current; R is the stator resistance; where ψ d , q The stator flux equation is obtained as follows:

[0064]

[0065] Among them, L d , L q is the d-axis and q-axis components of the three-phase stator inductance, ψ f Rotor permanent magnet flux.

[0066] Step 2024: Based on the d-axis stator voltage and the q-axis stator voltage, coordinate transformation is performed to obtain the α-axis stator voltage and the β-axis stator voltage in the stationary coordinate system.

[0067] Exemplarily, the α-axis stator voltage and the β-axis stator voltage are obtained by performing coordinate transformation based on the following formula:

[0068]

[0069] The above steps obtain the α-axis current, β-axis current, α-axis stator voltage and β-axis stator voltage. The following steps explain how to obtain the induced voltage.

[0070] In step 203, according to the α-axis current, the β-axis current, the α-axis stator voltage and the β-axis stator voltage, the actual induced voltage in the synchronous rotating coordinate system is estimated based on the motor observer.

[0071] In a possible implementation, according to the α-axis current, the β-axis current, the α-axis stator voltage, and the β-axis stator voltage, the actual induced voltage in the synchronous rotating coordinate system is estimated based on the motor observer, including:

[0072] Step 2031 , according to the α-axis current, the β-axis current, the α-axis stator voltage and the β-axis stator voltage, the α-axis back electromotive force and the β-axis back electromotive force are estimated based on the motor observer.

[0073] Exemplarily, the motor observer may include a sliding film observer, a Romberg observer or an adaptive observer, etc. Taking the sliding film observer as an example, in the field of motor control, the sliding film observer (SMO) is a technology for sensorless control of permanent magnet synchronous motors. The sliding film observer uses the motor mathematical model and the sliding film variable structure to indirectly detect the rotor position, and has good robustness and performance. It estimates the rotor position and angular velocity through the voltage and current equations in the αβ coordinate system, which can solve problems in traditional sensor control, such as the jitter phenomenon. The following is a specific example to illustrate how to obtain the back electromotive force.

[0074] In some embodiments, estimating the α-axis back electromotive force and the β-axis back electromotive force based on the motor observer according to the α-axis current, the β-axis current, the α-axis stator voltage, and the β-axis stator voltage includes:

[0075] The α-axis back EMF and β-axis back EMF are obtained based on the following formulas:

[0076]

[0077] Among them, U α is the α-axis stator voltage; U β is the β-axis stator voltage; E α is the α-axis back EMF, or the α-axis extended back EMF; E β It is the β-axis back electromotive force, or called the β-axis extended back electromotive force.

[0078] Exemplarily, the permanent magnet synchronous motor is an embedded permanent magnet synchronous motor, which is characterized by having a certain salient pole ratio, that is, the salient pole ratio is greater than 1, L d <Lq。

[0079] Step 2032: Based on the α-axis back electromotive force and the β-axis back electromotive force, the actual induced voltage in the synchronous rotating coordinate system is obtained.

[0080] In some embodiments, obtaining the actual induced voltage in the synchronous rotating coordinate system based on the α-axis back electromotive force and the β-axis back electromotive force includes:

[0081] The actual induced voltage in the synchronous rotating coordinate system is obtained based on the following formula:

[0082]

[0083] Among them, E1 is the actual induced voltage.

[0084] The above steps obtain the actual induced voltage, and the following steps explain how to obtain the theoretical induced voltage.

[0085] In step 204, a theoretical induced voltage in a non-locked rotor condition is obtained based on the electrical angular velocity and the induced voltage constant.

[0086] For example, the speed can be estimated by the observer, and then the electrical angular velocity can be obtained to calculate the induced voltage formula. It should be noted that it is assumed that the motor is running normally at the current moment, and the electrical angular velocity is equivalent to the mechanical speed of the rotor. That is, assuming that there is no stalling, the electrical angular velocity and the induced voltage constant are used to calculate how much induced voltage should be generated on the stator if the rotor rotates normally without stalling.

[0087] In a possible implementation, based on the electrical angular velocity and the induced voltage constant, the theoretical induced voltage under non-locked rotor conditions is obtained, which includes:

[0088] The theoretical induced voltage under non-locked rotor conditions is obtained based on the following formula:

[0089] E2=K e *ω e +K d

[0090] Where, E2 is the theoretical induced voltage; K e is the induced voltage constant; K d is a fixed induction voltage offset.

[0091] In step 205, it is determined whether the motor is stalled based on the difference between the actual induced voltage and the theoretical induced voltage and a preset difference threshold.

[0092] In a possible implementation, the actual induced voltage is subtracted from the theoretical induced voltage to obtain an induced voltage difference. If the induced voltage difference is greater than a preset difference threshold, it is determined that the motor is stalled. If the induced voltage difference is not greater than the preset difference threshold, it is determined that the motor is not stalled.

[0093] In one possible implementation, whether the motor is stalled is determined based on the difference between the actual induced voltage and the theoretical induced voltage and a preset difference threshold, as well as the duration of the induced voltage difference being greater than the difference threshold. For example, if the induced voltage difference is greater than the difference threshold and the duration is greater than the preset value, it is determined whether the motor is stalled.

[0094] Exemplarily, the software program in the controller is provided with a preset threshold error0, and a difference error12 between the induced voltage E1 observed and converted by the comparison observer and the actual induced voltage E2 calculated in real time according to the current speed. If the difference error12 is greater than the preset threshold error0 and lasts for the set time t0, satisfying the above-mentioned judgment logic, that is, meeting the judgment criteria, then it is judged that the motor is stalled.

[0095] Exemplarily, a stall flag may be set in the controller to provide effective input for the controller protection strategy, thereby avoiding the burning of the motor due to prolonged stalling and ensuring the safe operation of the motor.

[0096] Regarding the judgment logic, it should be explained that: when the motor is not blocked and operates normally, the stator and rotor signals are synchronized, the rotor corresponds to the mechanical signal, and the stator corresponds to the electrical signal. The rotation of the rotor will generate a corresponding induced voltage on the stator. At this time, the electrical angular velocity estimated by the observer and the actual mechanical speed are corresponding, so the error value between the induced voltage E1 converted by the observer and the calculated induced voltage E2 is very small and within the preset threshold.

[0097] When the motor is stalled, the stator and rotor signals will no longer be synchronized, and the actual mechanical speed and electrical angular velocity will no longer correspond. It can be seen from the actual situation that at this time the actual rotation speed of the motor is much smaller than the speed corresponding to the electrical angular velocity estimated by the observer. Therefore, the induced voltage generated by the motor rotor on the stator is very small. Therefore, the error value between the induced voltage E1 converted by the observer and the calculated induced voltage E2 is large (the actual measurement and the above normal operation are not in the same order of magnitude), which is outside the preset threshold.

[0098] The embodiment of the present invention obtains αβ current and αβ stator voltage based on the three-phase current transformation of the motor; then, based on the αβ current and αβ stator voltage, the actual induced voltage in the dq coordinate system is obtained through the motor observer; based on the electrical angular velocity and motor constant of the motor, the theoretical induced voltage in the non-stalled state is obtained; and according to the difference between the actual induced voltage and the theoretical induced voltage, whether the motor is stalled is determined. Specifically, when stalling occurs, the stator and rotor signals are not synchronized, the actual rotor speed decreases, and the induced voltage generated by the rotor on the stator decreases, that is, the actual induced voltage decreases, and the difference between the actual induced voltage and the theoretical induced voltage increases, thereby determining whether the motor is stalled. Compared with existing methods, such as speed threshold judgment or current threshold judgment, the sensitivity of the induced voltage change is higher, so the induced voltage stall judgment method is faster and the stall detection efficiency is higher.

[0099] Regarding the higher sensitivity of the induced voltage change, it should be noted that the motor controller belongs to a voltage-type inverter, and its control process can be understood as: voltage → current → magnetic field → force → torque → position change (angle) → angular velocity → speed. So:

[0100] 1. When a stall occurs, the first thing that changes is the related voltage, followed by intuitive parameters such as current and speed. Therefore, the induced voltage that is directly related to the stall is more sensitive.

[0101] 2. In the embodiment of the present invention, the two induced voltages reflect one electrical parameter (stator side) and one mechanical parameter (rotor side). When the motor is operating normally, the stator and rotor operate synchronously, and the difference between the two parameters is very small. When the motor is stalled, the difference between the two parameters increases rapidly.

[0102] In summary, compared with relying on current or speed, the sensitivity of induced voltage changes is higher and can reflect the stall state more timely and accurately.

[0103] The embodiment of the present invention obtains the induced voltage at the software algorithm level based on observer estimation, which reduces the processes of sensor acquisition of real-time data, analog-to-digital conversion, data filtering, etc., improves the speed of motor voltage acquisition, and improves the speed of stall detection. At the same time, the use of sensors is reduced and the cost is also reduced. For example, the electrical angular velocity can be estimated based on the observer to avoid the use of position sensors. The stall detection method based on induced electromotive force error judgment in the embodiment of the present invention has the advantages of simple algorithm, low cost and high reliability.

[0104] The embodiment of the present invention is based on sensorless control, reduces the cost of the detection system, enhances the anti-interference ability of the system, and improves the reliability of the system. The two-phase current output by the motor is collected, and after mathematical coordinate transformation, the induced voltage E1 of the current state is observed and converted by the observer. E2 is calculated in real time according to the current speed and the induced voltage constant.

[0105] The embodiment of the present invention makes a determination in the program software, that is, the software algorithm layer continuously detects the motor state, reduces the hysteresis of other current detection methods, and further reduces a series of impacts caused by misjudgment detection.

[0106] Regarding hysteresis: This method directly uses software parameters and motor inherent parameters for real-time calculation and comparison, and the judgment logic is also very simple. If the speed or current is used for judgment, they need to be converted and filtered before the algorithm judgment can be made, which will cause hysteresis.

[0107] Regarding reducing misjudgment: If the stall judgment is not timely and accurate, either hardware overcurrent will occur first, or the motor will remain in a stall state without timely and correct stall judgment. According to actual measurements, the method of the embodiment of the present invention is 700ms earlier than the hardware overcurrent fault without stall protection.

[0108] The stall detection method according to the embodiment of the present invention is described below with a comprehensive embodiment.

[0109] Figure 3 Schematic diagram of the structure of the motor stall detection system during the implementation of the present invention. Figure 3, the motor controller is connected to the motor. The motor controller includes a controller module, a signal acquisition module, and a stall detection module. The power module is connected to the motor controller to provide high-voltage DC input and low-voltage voltage input for the motor control system; the control module is connected to the motor to control the motor operation; the signal acquisition module collects the current signal of the motor and transmits it to the control module for motor control. The stall judgment module is connected to the control module, and determines whether the current motor is in a stall state according to the module calculation value and the estimated value of the estimator in the motor control module, and reports and stores the stall fault.

[0110] Figure 4 is a motor stall determination block diagram provided by an embodiment of the present invention; Figure 4 , three-phase current sampling or single-phase current sampling and current reconstruction; the position and speed observer can obtain the electrical angular velocity and the induced electromotive force observation value; the induced electromotive force calculation value is obtained based on the electrical angular velocity. Then the stall judgment is carried out.

[0111] Figure 5 This is a main flow chart of the motor stall detection method provided by the present invention; Figure 5 First, initialize the stall judgment algorithm to detect whether the PMSM motor is in operation; if it is in operation, perform signal acquisition and processing, the observer outputs the induced voltage E1, and calculates the induced voltage E2 in real time. Determine whether the difference error12 is greater than the preset threshold error0. If error12 is greater than the preset threshold error0, determine whether the duration t of error12 being greater than error0 is greater than the set time t0. If so, determine that the PMSM motor is stalled and control the motor to stop working.

[0112] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0113] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0114] Figure 6 : is a schematic diagram of the structure of a permanent magnet synchronous motor stall detection device provided by an embodiment of the present invention. For the sake of convenience, only the parts related to the embodiment of the present invention are shown, which are described in detail as follows:

[0115] Reference Figure 6 The permanent magnet synchronous motor stall detection device 6 comprises:

[0116] The acquisition module 61 is used to acquire the three-phase current, electrical angular velocity and induced voltage constant of the motor.

[0117] The conversion module 62 is used for obtaining the α-axis current and the β-axis current in the two-phase stationary coordinate system through coordinate conversion based on the three-phase current in the three-phase coordinate system, and obtaining the α-axis stator voltage and the β-axis stator voltage.

[0118] The first obtaining module 63 is used to obtain the actual induced voltage in the synchronous rotating coordinate system based on the motor observer estimation according to the α-axis current, the β-axis current, the α-axis stator voltage and the β-axis stator voltage.

[0119] The second obtaining module 64 is used to obtain a theoretical induced voltage in a non-locked rotor condition based on the electrical angular velocity and the induced voltage constant.

[0120] The judgment module 65 is used to judge whether the motor is stalled according to the difference between the actual induced voltage and the theoretical induced voltage and a preset difference threshold.

[0121] The embodiment of the present invention obtains αβ current and αβ stator voltage based on the three-phase current transformation of the motor; then, based on the αβ current and αβ stator voltage, the actual induced voltage in the dq coordinate system is obtained through the motor observer; based on the electrical angular velocity and motor constant of the motor, the theoretical induced voltage in the non-stalled state is obtained; and according to the difference between the actual induced voltage and the theoretical induced voltage, whether the motor is stalled is determined. Specifically, when stalling occurs, the stator and rotor signals are not synchronized, the actual rotor speed decreases, and the induced voltage generated by the rotor on the stator decreases, that is, the actual induced voltage decreases, and the difference between the actual induced voltage and the theoretical induced voltage increases, thereby determining whether the motor is stalled. Compared with existing methods, such as speed threshold judgment or current threshold judgment, the sensitivity of the induced voltage change is higher, so the induced voltage stall judgment method is faster and the stall detection efficiency is higher.

[0122] Figure 7 Schematic diagram of an electronic device provided by an embodiment of the present invention. Figure 7 As shown, the electronic device 7 of this embodiment includes: a processor 70, a memory 71, and a computer program 72 stored in the memory 71 and executable on the processor 70. When the processor 70 executes the computer program 72, the steps in the above-mentioned permanent magnet synchronous motor stall detection method embodiments are implemented, for example Figure 2 Alternatively, when the processor 70 executes the computer program 72, the functions of each module / unit in the above-mentioned device embodiments are realized, for example, Figure 6 The functions of modules 61 to 65 are shown.

[0123] Exemplarily, the computer program 72 may be divided into one or more modules / units, which are stored in the memory 71 and executed by the processor 70 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, which are used to describe the execution process of the computer program 72 in the electronic device 7. For example, the computer program 72 may be divided into Figure 6 Modules 61 to 65 are shown.

[0124] The electronic device 7 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The electronic device 7 may include, but is not limited to, a processor 70 and a memory 71. Those skilled in the art will appreciate that Figure 7 It is only an example of the electronic device 7 and does not constitute a limitation of the electronic device 7. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0125] The processor 70 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0126] The memory 71 may be an internal storage unit of the electronic device 7, such as a hard disk or memory of the electronic device 7. The memory 71 may also be an external storage device of the electronic device 7, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 7. Further, the memory 71 may also include both an internal storage unit and an external storage device of the electronic device 7. The memory 71 is used to store the computer program and other programs and data required by the electronic device. The memory 71 may also be used to temporarily store data that has been output or is to be output.

[0127] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0128] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0129] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0130] In the embodiments provided by the present invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0131] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0132] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0133] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned permanent magnet synchronous motor stall detection method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium.

[0134] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for detecting stall of a permanent magnet synchronous motor, characterized in that: include: Obtaining three-phase current, electrical angular velocity and induced voltage constant of the motor; Based on the three-phase current in the three-phase coordinate system, coordinate transformation is performed to obtain the α-axis current and the β-axis current in the two-phase stationary coordinate system, and the α-axis stator voltage and the β-axis stator voltage are obtained; According to the α-axis current, the β-axis current, the α-axis stator voltage and the β-axis stator voltage, an actual induced voltage in a synchronous rotating coordinate system is obtained based on the motor observer estimation; Based on the electrical angular velocity and the induced voltage constant, a theoretical induced voltage under a non-locked rotor condition is obtained; Whether the motor is stalled is determined based on a difference between the actual induced voltage and the theoretical induced voltage and a preset difference threshold.

2. The method for detecting stall of a permanent magnet synchronous motor according to claim 1, characterized in that: Obtaining the three-phase current of the motor includes: Use a single resistor sampling method or a double resistor sampling method to obtain any two-phase current of the motor; Based on any two-phase currents, current reconstruction is performed according to Kirchhoff's law to obtain the third-phase current.

3. The method for detecting stall of a permanent magnet synchronous motor according to claim 1, characterized in that: The coordinate conversion based on the three-phase current in the three-phase coordinate system to obtain the α-axis current and the β-axis current in the two-phase stationary coordinate system, and to obtain the α-axis stator voltage and the β-axis stator voltage includes: Based on the three-phase current in the three-phase coordinate system, coordinate transformation is performed to obtain an α-axis current and a β-axis current in a two-phase stationary coordinate system; Based on the α-axis current and the β-axis current, coordinate transformation is performed to obtain the d-axis current and the q-axis current in a synchronous rotating coordinate system; Based on the d-axis current and the q-axis current, a d-axis stator voltage and a q-axis stator voltage are obtained through a stator voltage equation; Based on the d-axis stator voltage and the q-axis stator voltage, coordinate transformation is performed to obtain an α-axis stator voltage and a β-axis stator voltage in a stationary coordinate system.

4. The method for detecting stall of a permanent magnet synchronous motor according to claim 3, characterized in that: The stator voltage equation is: Among them, u d is the d-axis stator voltage; u q is the shaft stator voltage; ω e is the electrical angular velocity; ψ d , q are the d-axis and q-axis components of the three-phase stator flux respectively; p is the differential operator; i d is the d-axis current; i q is the q-axis current; R is the stator resistance; Among them, ψ d , q The stator flux equation is obtained as follows: Among them, L d , L q is the d-axis and q-axis components of the three-phase stator inductance, ψ f Rotor permanent magnet flux.

5. The method for detecting stall of a permanent magnet synchronous motor according to claim 1, characterized in that: According to the α-axis current, β-axis current, α-axis stator voltage and β-axis stator voltage, the actual induced voltage in the synchronous rotating coordinate system is estimated based on the motor observer, including: According to the α-axis current, the β-axis current, the α-axis stator voltage and the β-axis stator voltage, an α-axis back electromotive force and a β-axis back electromotive force are estimated based on a motor observer; Based on the α-axis back electromotive force and the β-axis back electromotive force, an actual induced voltage in a synchronously rotating coordinate system is obtained.

6. The method for detecting stall of a permanent magnet synchronous motor according to claim 5, characterized in that: According to the α-axis current, the β-axis current, the α-axis stator voltage, and the β-axis stator voltage, the α-axis back electromotive force and the β-axis back electromotive force estimated based on the motor observer include: The α-axis back EMF and β-axis back EMF are obtained based on the following formulas: Among them, U α is the α-axis stator voltage; U β is the β-axis stator voltage; E α is the α-axis back electromotive force; E β is the β-axis back electromotive force.

7. The method for detecting stall of a permanent magnet synchronous motor according to claim 1, characterized in that: Based on the electrical angular velocity and the induced voltage constant, the theoretical induced voltage under non-locked rotor conditions is obtained, including: The theoretical induced voltage under non-locked rotor conditions is obtained based on the following formula: E2=K e *oh e +K d Where, E2 is the theoretical induced voltage; K e is the induced voltage constant; K d is a fixed induction voltage offset.

8. A permanent magnet synchronous motor stall detection device, characterized in that: include: An acquisition module, used for acquiring the three-phase current, electrical angular velocity and induced voltage constant of the motor; A conversion module, configured to obtain an α-axis current and a β-axis current in a two-phase stationary coordinate system by coordinate conversion based on the three-phase current in the three-phase coordinate system, and to obtain an α-axis stator voltage and a β-axis stator voltage; A first obtaining module is used to obtain an actual induced voltage in a synchronous rotating coordinate system based on the α-axis current, the β-axis current, the α-axis stator voltage and the β-axis stator voltage and estimation based on a motor observer; A second obtaining module is used to obtain a theoretical induced voltage under a non-locked rotor condition based on the electrical angular velocity and the induced voltage constant; The judging module is used to judge whether the motor is stalled according to the difference between the actual induced voltage and the theoretical induced voltage and a preset difference threshold.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the permanent magnet synchronous motor stall detection method as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the permanent magnet synchronous motor stall detection method as described in any one of claims 1 to 7 are implemented.

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