A motor adaptive PI adjusting method and device, motor and storage medium

Abstract

This invention discloses a method, device, motor, storage medium, and computer program product for adaptive PI control of a motor. It is applied to a dual closed-loop motor control system including a speed loop and a current loop, where the control system is equipped with a PI controller for speed and current regulation. The method includes: acquiring the actual back EMF characteristic quantity of the motor under its current operating state and the reference back EMF characteristic quantity corresponding to the current motor speed; performing a difference operation between the actual and reference back EMF characteristic quantities to obtain a back EMF difference value; determining the motor's load state based on a comparison between the back EMF difference value and a preset threshold; and selecting matching PI parameters and loading them onto the PI controller based on the load state. This scheme improves the universality and adaptability of the adaptive PI control scheme for motors and effectively reduces the adaptation and debugging costs for different motor and load combinations.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, specifically relating to a motor adaptive PI control method, device, motor, storage medium, and computer program product, and particularly to a permanent magnet synchronous motor adaptive PI control method, device, motor, storage medium, and computer program product based on back electromotive force. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in drive systems of various household appliances due to their advantages such as high efficiency, low noise, and high power density. The stability of the motor's speed operation directly determines its operating noise, control accuracy, and the temperature rise of controller components, making it a core indicator for evaluating motor drive performance. Currently, the industry commonly employs a dual-closed-loop PI control strategy combining speed and current loops. This strategy uses a PI regulator to correct the speed and current feedback signals, achieving smooth motor speed regulation.

[0003] To adapt to different operating conditions such as no-load and load, existing technologies mainly adopt two types of PI regulation methods: one is fixed parameter PI control, in which the motor operates under the same set of PI parameters throughout the entire process. This method is simple to implement, but it cannot take into account the control requirements under different loads and is prone to problems such as speed fluctuation and motor vibration under no-load or load conditions; the other is adaptive PI control based on current threshold, which determines the load status of the motor by detecting the magnitude of the stator current and switches the corresponding PI parameters according to the load status, which can improve the operating stability under multiple operating conditions to a certain extent.

[0004] However, the above-mentioned adaptive PI regulation scheme based on current threshold has problems: the determination of load status depends entirely on the preset stator current switching threshold. However, the no-load and load current levels of different motor models and loads with different characteristics (such as different specifications of wind turbines) are significantly different. The preset fixed current threshold cannot be universal. The minimum switching current value must be tested and calibrated separately for each combination of motor and load. This results in poor versatility of the scheme, long product adaptation and debugging cycle, high cost, and difficulty in meeting the rapid development needs of multi-category motor products.

[0005] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0006] The purpose of this invention is to provide a method, device, motor, storage medium, and computer program product for adaptive PI regulation of motors, in order to solve the problems of poor universality and high product adaptation and debugging costs in existing adaptive PI regulation schemes for motors, which require separate calibration of switching current for different motors and loads. The invention achieves the effect of identifying the load state and adaptively switching PI parameters by using the back electromotive force difference value, eliminating the dependence on the stator current switching threshold, greatly improving the universality and adaptability of the adaptive PI regulation scheme for motors, and effectively reducing the adaptation and debugging costs of different combinations of motors and loads.

[0007] This invention provides an adaptive PI control method for a motor, applied to a dual closed-loop motor control system including a speed loop and a current loop. The control system is equipped with a PI controller for speed and current regulation. The method includes: acquiring the actual back EMF characteristic quantity of the motor under its current operating state and the reference back EMF characteristic quantity corresponding to the current motor speed; performing a difference operation on the actual back EMF characteristic quantity and the reference back EMF characteristic quantity to obtain a back EMF difference value; determining the motor load state based on the comparison result of the back EMF difference value and a preset threshold; and selecting matching PI parameters and applying them to the PI controller based on the load state.

[0008] In some implementations, obtaining the actual back electromotive force characteristic quantity under the current operating state of the motor includes: calculating the voltage and current signals of the motor through a rotor position observer to obtain the actual back electromotive force characteristic quantity.

[0009] In some implementations, obtaining the reference back electromotive force characteristic quantity corresponding to the current motor speed includes: calculating the reference back electromotive force characteristic quantity at the corresponding speed based on the proportional relationship between back electromotive force and speed, according to the current motor speed.

[0010] In some implementations, the load state of the motor is determined based on the comparison between the back EMF difference value and a preset threshold, including: when the back EMF difference value is greater than or equal to the preset threshold and the duration reaches the preset duration, the motor is determined to be in a loaded state; when the back EMF difference value is less than the preset threshold and the duration reaches the preset duration, the motor is determined to be in an unloaded state.

[0011] In some implementations, the PI parameters include no-load PI parameters and loaded PI parameters; the no-load PI parameters are loaded onto the PI regulator in the no-load state, and the loaded PI parameters are loaded onto the PI regulator in the loaded state.

[0012] In conjunction with the above method, another aspect of the present invention provides a motor adaptive PI control device, applied to a dual closed-loop motor control system including a speed loop and a current loop, wherein the control system is equipped with a PI regulator for speed and current regulation; characterized in that the device includes: an acquisition unit configured to acquire the actual back EMF characteristic quantity of the motor under the current operating state and the reference back EMF characteristic quantity corresponding to the current speed of the motor; a processing unit configured to perform subtraction processing on the actual back EMF characteristic quantity and the reference back EMF characteristic quantity to obtain a back EMF difference value; the processing unit is further configured to determine the load state of the motor based on the comparison result of the back EMF difference value and a preset threshold; and a loading unit configured to select matching PI parameters according to the load state and load them to the PI regulator.

[0013] In conjunction with the above-described device, the present invention further provides a motor, comprising: the motor adaptive PI adjustment device described above.

[0014] In conjunction with the above method, the present invention further provides a storage medium comprising a stored program, wherein, when the program is executed, the device on which the storage medium is located executes the above-described motor adaptive PI control method.

[0015] In conjunction with the above method, the present invention further provides a computer program product comprising a computer program that, when processed and executed, implements the steps of the above-described motor adaptive PI control method.

[0016] The present invention obtains the current actual back EMF characteristic quantity of the motor and the reference back EMF characteristic quantity corresponding to the current speed, calculates the difference between the two characteristic quantities to obtain the back EMF difference value, determines the motor load state based on the comparison result of the back EMF difference value and a preset threshold, and then selects matching PI parameters according to the load state and applies them to the system's PI regulator. This eliminates the dependence on stator current switching thresholds in traditional solutions, significantly improves the universality and adaptability of the motor adaptive PI regulation scheme, and effectively reduces the adaptation and debugging costs for different motor and load combinations.

[0017] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating an embodiment of the adaptive PI control method for motors of the present invention;

[0020] Figure 2 This is a schematic diagram of a structure of an embodiment of the motor adaptive PI control device of the present invention;

[0021] Figure 3 This is a block diagram of the motor control system.

[0022] Figure 4 This is a flowchart illustrating the adaptive PI control method for permanent magnet synchronous motors based on back electromotive force.

[0023] Referring to the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0024] 101 - Acquisition unit; 102 - Processing unit; 103 - Loading unit. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] According to an embodiment of the present invention, an adaptive PI control method for a motor is provided, applied to a dual closed-loop motor control system including a speed loop and a current loop. The speed loop is the outer loop, used to regulate the motor speed for stability; the current loop is the inner loop, used to regulate the winding current for stability. The two work together to achieve smooth speed regulation of the motor. The control system is equipped with a PI controller for speed and current regulation, i.e., a proportional-integral controller. The proportional element quickly responds to control deviations, and the integral element eliminates steady-state deviations. It is the core control unit in the motor closed-loop control used to correct speed and current signals.

[0027] like Figure 3The dual closed-loop motor control system shown employs a cascaded control architecture of an outer speed loop and an inner current loop. Combined with coordinate transformation, space vector modulation, and rotor position estimation modules, it achieves smooth motor speed regulation in sensorless scenarios. The specific working process is as follows: The system takes a given speed as the input target. The difference between the given speed and the actual speed fed back by the rotor position estimation module is sent to the speed loop PI regulator. The regulator outputs the q-axis current reference value as the control target of the inner current loop. The d-axis and q-axis current reference values ​​are subtracted from the actual d- and q-axis currents fed back by coordinate transformation, respectively, and sent to their corresponding current loop PI regulators, outputting d- and q-axis control voltages in the rotating coordinate system. These two voltages are then converted from the rotating dq coordinate system voltages to the stationary αβ coordinate system by the Park inverse transformation module, combined with the rotor position estimation. These voltages are then sent to the SVPWM space vector pulse width modulation module to generate... The modulation pulse is used to drive the power transistors; the pulse signal is input to the three-phase inverter bridge to convert DC power into three-phase AC power with adjustable amplitude and frequency to drive the motor body; during motor operation, the system collects two-phase stator current in real time, first converts the current in the three-phase stationary abc coordinate system into the current in the two-phase stationary αβ coordinate system through Clark transformation, and then converts it into the current in the two-phase rotating dq coordinate system through Park transformation combined with the rotor position angle, and feeds it back to the input of the corresponding current loop to form the inner current loop closed loop; at the same time, the rotor position estimation module collects the voltage and current signals in the stationary coordinate system, and estimates the rotor position and motor speed in real time through the observer algorithm. The rotor position is used for coordinate synchronization of Park transformation and inverse Park transformation, and the estimated speed is fed back to the speed loop input to be compared with the given speed to form the outer speed loop closed loop; the rotor position estimation module can also output back electromotive force related characteristic quantities.

[0028] like Figure 1 The flowchart of an embodiment of the method of the present invention is shown. The motor adaptive PI adjustment method may include steps S110 to S140.

[0029] In step S110, the actual back EMF characteristic quantity of the motor under the current operating state and the reference back EMF characteristic quantity corresponding to the current motor speed are obtained.

[0030] Back electromotive force (EMF) characteristic quantities are quantitative parameters that characterize the magnitude of a motor's back EMF. These can include various forms such as the amplitude, effective value, and components in a specific coordinate system, reflecting the total flux linkage state within the motor. The magnitude of the back EMF has a clear correlation with the motor speed and is also affected by the level of the total flux linkage within the motor. The reference back EMF characteristic quantity corresponds to the reference flux linkage level at the same speed, while the actual back EMF characteristic quantity corresponds to the motor's current true flux linkage level. Only by combining these two can the influence of the speed itself on the back EMF be eliminated, reflecting only the flux linkage differences caused by load variations.

[0031] In some implementations, step S110, obtaining the actual back EMF characteristic quantity under the current operating state of the motor, includes: calculating the voltage and current signals of the motor through a rotor position observer to obtain the actual back EMF characteristic quantity.

[0032] Rotor position observers can estimate internal state variables such as rotor position, operating speed, and back electromotive force in real time by collecting measurable voltage and current signals of the motor. Common implementation forms include sliding mode observers and Kalman filter observers. It is the core computing module of sensorless motor control system.

[0033] Back electromotive force (EMF) is the electromotive force induced in the stator windings by the rotor magnetic field of a motor. It is an internal electromagnetic quantity of the motor and cannot be directly measured by hardware sensors. It must be derived from the motor's electromagnetic mathematical model using directly acquired voltage and current signals. The rotor position observer is an essential module in sensorless motor control systems. Its core function is to estimate the rotor position and real-time speed, and the calculation process itself includes the derivation of back EMF. Reusing this module to extract actual back EMF characteristics eliminates the need for additional hardware sampling circuits and dedicated sensors, as well as the need to build a completely new computational chain. This allows for the acquisition of the required characteristics without increasing system hardware costs. Furthermore, the rotor position observer itself possesses signal filtering and anti-interference capabilities, suppressing the impact of sampling noise on the calculation results, resulting in higher stability and accuracy of the output back EMF characteristics.

[0034] Specifically, during motor operation, the control system collects voltage and current signals from the stator side of the motor and inputs the collected electrical signals into the rotor position observer. The rotor position observer performs iterative calculations based on a preset mathematical model of motor voltage and finally outputs the actual back electromotive force characteristic quantity of the motor under the current operating state.

[0035] In some implementations, step S110, obtaining the reference back EMF characteristic quantity corresponding to the current motor speed, includes: calculating the reference back EMF characteristic quantity at the corresponding speed based on the proportional relationship between back EMF and speed, according to the current motor speed.

[0036] The reference back electromotive force (EMF) characteristic quantity refers to the reference value of the back EMF corresponding to the reference flux state under the same speed conditions. It usually corresponds to the back EMF level when the motor is running under no-load conditions and is a reference standard for judging the load level. The back EMF is generated by the rotor permanent magnet magnetic field cutting the stator winding. Under the premise that the permanent magnet flux remains constant, the amplitude of the back EMF is strictly proportional to the motor speed; the higher the speed, the greater the amplitude of the back EMF.

[0037] The value of back electromotive force (EMF) is affected by both motor speed and the level of internal total flux linkage. If the absolute value of the actual back EMF is used directly to judge the load, it's impossible to distinguish whether the change in value is caused by speed fluctuations or by flux linkage changes due to load variations. Calculating the baseline back EMF characteristic quantity at the current speed ensures that the baseline value and the actual value are compared at the same speed, completely eliminating the interference of speed changes on the back EMF value. This ensures that the subsequent difference only reflects flux linkage changes caused by the load, guaranteeing the accuracy of load condition judgment. Furthermore, this proportional relationship is an inherent electromagnetic characteristic of the motor, related only to inherent parameters such as the flux linkage of the motor's permanent magnets. It eliminates the need to calibrate corresponding parameters separately for different external loads, fundamentally ensuring the universal adaptability of the solution.

[0038] Specifically, the current operating speed of the motor is acquired in real time, and based on the direct proportional relationship between back electromotive force and speed, the reference back electromotive force characteristic quantity corresponding to the current speed is obtained through calculation.

[0039] For example, during motor operation, calculations are performed based on the motor's dq-axis voltage model using a rotor position observer. The dq-axis voltage equations are as follows:

[0040]

[0041]

[0042] Among them, U q U d These are the stator voltages along the q-axis and d-axis, respectively. q i d These are the stator currents along the d-axis and q-axis, respectively, R s L is the stator resistance. d L q These are the d-axis and q-axis inductances, respectively, W e Ψ is the electric angular velocity of the motor. f It is a permanent magnet flux linkage. Based on this voltage model, the expression for the back electromotive force can be derived as follows: .

[0043] Under the same speed conditions, the stator current amplitude is very small when the motor is running under no-load, and the air gap magnetic field is mainly generated by the permanent magnet alone, resulting in the highest total flux linkage and the corresponding back electromotive force (EMF) reaching its maximum value at that speed. Since the back EMF amplitude is directly proportional to the motor speed, the no-load reference back EMF E1 at the same speed can be calculated based on the current speed. When the motor is running under load, a d-axis current component is generated in the stator current to output electromagnetic torque. The magnetic field generated by this component is opposite to the direction of the permanent magnet magnetic field, i.e., a demagnetizing effect is produced, which weakens the total flux linkage of the motor. According to the back EMF calculation formula, the decrease in total flux linkage will cause the back EMF amplitude to decrease synchronously. At this time, the actual back EMF calculated by the observer is E2, and E2 is less than the no-load reference back EMF E1 at the same speed.

[0044] In step S120, the difference between the actual back EMF characteristic quantity and the reference back EMF characteristic quantity is processed to obtain the back EMF difference value.

[0045] When the motor is running under no-load, the total flux linkage is strongest, and the back electromotive force (EMF) is at a relatively high level. When running under load, the demagnetizing effect generated by the stator current weakens the total flux linkage, resulting in an actual back EMF lower than the reference level. By performing a difference operation, the flux linkage change caused by the load can be quantified into a specific difference value, transforming the judgment of the load state into a comparison of numerical magnitudes, which facilitates the logical judgment in the program.

[0046] Specifically, the difference between the actual back EMF characteristic quantity and the reference back EMF characteristic quantity at the same time and speed is calculated to obtain the difference result. For example, the back EMF difference ΔE = E1 - E2.

[0047] In step S130, the load state of the motor is determined based on the comparison result between the back electromotive force difference value and the preset threshold.

[0048] Load status refers to the level of load the motor is under during operation, mainly divided into no-load status and loaded status. The preset threshold is the judgment boundary used to distinguish between no-load and loaded status. The magnitude of the difference directly corresponds to the degree of flux weakening caused by the motor load. When the difference is in different ranges, it corresponds to different load levels of the motor, thereby realizing automatic identification of load status.

[0049] In some implementations, step S130, determining the load state of the motor based on the comparison result between the back EMF difference value and a preset threshold, includes: when the back EMF difference value is greater than or equal to the preset threshold and the duration reaches a preset duration, determining that the motor is in a loaded state; when the back EMF difference value is less than the preset threshold and the duration reaches a preset duration, determining that the motor is in an unloaded state.

[0050] The preset threshold is a critical value for the back EMF difference used to distinguish between no-load and loaded states; the preset duration is used to filter out misjudgments caused by instantaneous fluctuations. Only when the difference meets the threshold condition and continues to reach this duration will the corresponding load state be finally confirmed.

[0051] The magnitude of the back EMF difference directly corresponds to the degree of flux weakening caused by the motor load. The heavier the load, the more pronounced the demagnetizing effect, and the larger the back EMF difference. By dividing the difference range with a preset threshold, the continuously changing difference can be transformed into a clear load state classification. Adding a preset delay judgment mechanism can filter out short-term interference signals. Only when the difference state remains stable for the set duration is the change in load state confirmed, effectively avoiding misjudgments and frequent switching, and ensuring the smoothness and stability of the control process.

[0052] Specifically, the control system continuously calculates the back EMF difference value during operation and simultaneously times the state where the difference value meets the corresponding threshold condition. When the back EMF difference value is greater than or equal to the preset threshold and the duration of this state reaches the preset duration, the system determines that the motor is in a loaded state. When the back EMF difference value is less than the preset threshold and the duration of this state reaches the preset duration, the system determines that the motor is in an unloaded state.

[0053] In step S140, a matching PI parameter is selected and loaded into the PI regulator according to the load state.

[0054] Motor control characteristics differ under different load conditions. A single PI parameter cannot simultaneously ensure control stability under both no-load and load conditions. An excessively high parameter under no-load conditions can cause current oscillations, while an excessively low parameter under load conditions can lead to sluggish response. By matching the PI parameter to the load condition, the speed and current regulation under different operating conditions can be kept in an appropriate parameter state, ensuring operational stability under all operating conditions.

[0055] In some implementations, the PI parameters include no-load PI parameters and loaded PI parameters; the no-load PI parameters are loaded onto the PI regulator in the no-load state, and the loaded PI parameters are loaded onto the PI regulator in the loaded state.

[0056] The no-load PI parameter corresponds to a smaller proportional coefficient, used to suppress current overshoot and control oscillations under no-load conditions. The load PI parameter corresponds to a larger proportional coefficient, used to improve the regulation response speed under load conditions.

[0057] The control characteristics of a motor differ significantly under different load conditions. Under no-load conditions, the equivalent load inertia of the motor is small, and the stator operating current amplitude is low. If the proportional coefficient of the PI parameter is too large, the current regulation response speed will be too fast, easily leading to current overshoot. In severe cases, it can cause current loop oscillation, ultimately manifesting as motor vibration, speed fluctuation, and increased operating noise. Under load conditions, the equivalent load inertia of the motor increases, and the operating current amplitude rises. If the proportional coefficient of the PI parameter is too small, the speed and current regulation response will be slow, and the speed recovery speed will be slow when the load is disturbed, making it impossible to quickly enter a stable operating state. Configuring dedicated PI parameters for no-load and load conditions allows the control loops under both conditions to operate with appropriate regulation parameters, balancing the stability of no-load operation and the response speed of load operation. This fundamentally solves the problem that a single PI parameter cannot simultaneously adapt to the control needs of all operating conditions.

[0058] Specifically, when the system determines that the motor is in an unloaded state, the unloaded PI parameters are loaded into the PI regulator of the control system, and the regulator performs closed-loop regulation of speed and current based on these parameters; when the system determines that the motor is in a loaded state, the loaded PI parameters are loaded into the PI regulator of the control system, and the regulator performs closed-loop regulation of speed and current based on these parameters.

[0059] This invention identifies the motor load state by using the back EMF difference value and adaptively switches PI parameters, eliminating the dependence on stator current switching thresholds in traditional solutions. It also eliminates the need to calibrate judgment parameters separately for different motors and loads, greatly improving the versatility of the solution and product adaptability. At the same time, it can match adaptive control parameters for different load conditions, ensuring stable motor speed and current under all operating conditions and suppressing operating vibration and noise.

[0060] Figure 4This is a flowchart illustrating an adaptive PI control method for a permanent magnet synchronous motor based on back electromotive force (EMF). The method includes: first, performing program initialization to configure motor parameters, no-load back EMF reference parameters, and basic data such as thresholds and delay parameters required for subsequent judgments; after initialization, the system verifies whether the parameters are configured correctly. If not, it returns to continue the initialization process. Once the parameters are configured, the motor enters normal operation. During normal operation, the system simultaneously performs two calculations: one calculates the no-load reference back EMF value E1 corresponding to the current real-time speed, and the other detects the actual back EMF value E2 at the same speed using a rotor position observer; after both values ​​are output, they are uniformly entered into a difference calculation stage to obtain the difference ΔE between the reference back EMF and the actual back EMF. After the difference calculation is completed, the load status determination stage begins. First, it checks if ΔE is greater than or equal to a preset threshold. If ΔE is less than the preset threshold, the motor is directly determined to be in an unloaded state, and the corresponding PI parameters for the unloaded condition are called. If ΔE is greater than or equal to the preset threshold, it further checks if the duration of this difference state is greater than a preset delay time. If the duration does not meet the delay requirement, it is still determined to be in an unloaded state, and the unloaded PI parameters are maintained. If the duration meets the delay requirement, the motor is determined to be in a loaded state, and the corresponding PI parameters for the loaded condition are called. After completing the load status determination and PI parameter selection, the system applies the selected PI parameters to the current loop and speed loop regulators to ensure stable control of motor speed and current.

[0061] The technical solution of this embodiment obtains the current actual back EMF characteristic quantity of the motor and the reference back EMF characteristic quantity at the corresponding speed. After obtaining the back EMF difference value through difference calculation, the motor load state is determined by comparing it with a preset threshold. Finally, the corresponding parameters are matched and loaded for the PI regulator. This can get rid of the dependence on the stator current switching threshold, significantly improve the universal adaptability of the motor's adaptive PI regulation, and effectively reduce the adaptation and debugging cost of different motor and load combinations.

[0062] According to embodiments of the present invention, a motor adaptive PI control device corresponding to the motor adaptive PI control method is also provided. It is applied to a dual closed-loop motor control system comprising a speed loop and a current loop. The speed loop is the outer loop, used to regulate the motor speed for stability; the current loop is the inner loop, used to regulate the winding current for stability. The two loops work together to achieve smooth speed regulation of the motor. The control system is equipped with a PI controller for speed and current regulation, i.e., a proportional-integral controller. Through the proportional element, it quickly responds to control deviations, and through the integral element, it eliminates steady-state deviations. It is the core control unit in the motor closed-loop control used to correct speed and current signals.

[0063] See Figure 2The schematic diagram shown is a structural diagram of an embodiment of the device of the present invention. The motor adaptive PI adjustment device may include: an acquisition unit 101, a processing unit 102, and a loading unit 103.

[0064] The acquisition unit 101 is configured to acquire the actual back EMF characteristic quantity of the motor under the current operating state and the reference back EMF characteristic quantity corresponding to the current motor speed.

[0065] Back electromotive force (EMF) characteristic quantities are quantitative parameters that characterize the magnitude of a motor's back EMF. These can include various forms such as the amplitude, effective value, and components in a specific coordinate system, reflecting the total flux linkage state within the motor. The magnitude of the back EMF has a clear correlation with the motor speed and is also affected by the level of the total flux linkage within the motor. The reference back EMF characteristic quantity corresponds to the reference flux linkage level at the same speed, while the actual back EMF characteristic quantity corresponds to the motor's current true flux linkage level. Only by combining these two can the influence of the speed itself on the back EMF be eliminated, reflecting only the flux linkage differences caused by load variations.

[0066] In some implementations, the acquisition unit 101 acquires the actual back electromotive force characteristic quantity of the motor under the current operating state, including: calculating the voltage and current signals of the motor through a rotor position observer to obtain the actual back electromotive force characteristic quantity.

[0067] Rotor position observers can estimate internal state variables such as rotor position, operating speed, and back electromotive force in real time by collecting measurable voltage and current signals of the motor. Common implementation forms include sliding mode observers and Kalman filter observers. It is the core computing module of sensorless motor control system.

[0068] Back electromotive force (EMF) is the electromotive force induced in the stator windings by the rotor magnetic field of a motor. It is an internal electromagnetic quantity of the motor and cannot be directly measured by hardware sensors. It must be derived from the motor's electromagnetic mathematical model using directly acquired voltage and current signals. The rotor position observer is an essential module in sensorless motor control systems. Its core function is to estimate the rotor position and real-time speed, and the calculation process itself includes the derivation of back EMF. Reusing this module to extract actual back EMF characteristics eliminates the need for additional hardware sampling circuits and dedicated sensors, as well as the need to build a completely new computational chain. This allows for the acquisition of the required characteristics without increasing system hardware costs. Furthermore, the rotor position observer itself possesses signal filtering and anti-interference capabilities, suppressing the impact of sampling noise on the calculation results, resulting in higher stability and accuracy of the output back EMF characteristics.

[0069] Specifically, during motor operation, the control system collects voltage and current signals from the stator side of the motor and inputs the collected electrical signals into the rotor position observer. The rotor position observer performs iterative calculations based on a preset mathematical model of motor voltage and finally outputs the actual back electromotive force characteristic quantity of the motor under the current operating state.

[0070] In some implementations, the acquisition unit 101 acquires the reference back electromotive force characteristic quantity corresponding to the current motor speed, including: based on the proportional relationship between back electromotive force and speed, calculating the reference back electromotive force characteristic quantity at the corresponding speed according to the current motor speed.

[0071] The reference back electromotive force (EMF) characteristic quantity refers to the reference value of the back EMF corresponding to the reference flux state under the same speed conditions. It usually corresponds to the back EMF level when the motor is running under no-load conditions and is a reference standard for judging the load level. The back EMF is generated by the rotor permanent magnet magnetic field cutting the stator winding. Under the premise that the permanent magnet flux remains constant, the amplitude of the back EMF is strictly proportional to the motor speed; the higher the speed, the greater the amplitude of the back EMF.

[0072] The value of back electromotive force (EMF) is affected by both motor speed and the level of internal total flux linkage. If the absolute value of the actual back EMF is used directly to judge the load, it's impossible to distinguish whether the change in value is caused by speed fluctuations or by flux linkage changes due to load variations. Calculating the baseline back EMF characteristic quantity at the current speed ensures that the baseline value and the actual value are compared at the same speed, completely eliminating the interference of speed changes on the back EMF value. This ensures that the subsequent difference only reflects flux linkage changes caused by the load, guaranteeing the accuracy of load condition judgment. Furthermore, this proportional relationship is an inherent electromagnetic characteristic of the motor, related only to inherent parameters such as the flux linkage of the motor's permanent magnets. It eliminates the need to calibrate corresponding parameters separately for different external loads, fundamentally ensuring the universal adaptability of the solution.

[0073] Specifically, the current operating speed of the motor is acquired in real time, and based on the direct proportional relationship between back electromotive force and speed, the reference back electromotive force characteristic quantity corresponding to the current speed is obtained through calculation.

[0074] For example, during motor operation, calculations are performed based on the motor's dq-axis voltage model using a rotor position observer. The dq-axis voltage equations are as follows:

[0075]

[0076]

[0077] Among them, U q U d These are the stator voltages along the q-axis and d-axis, respectively. qi d These are the stator currents along the d-axis and q-axis, respectively, R s L is the stator resistance. d L q These are the d-axis and q-axis inductances, respectively, W e Ψ is the electric angular velocity of the motor. f It is a permanent magnet flux linkage. Based on this voltage model, the expression for the back electromotive force can be derived as follows: .

[0078] Under the same speed conditions, the stator current amplitude is very small when the motor is running under no-load, and the air gap magnetic field is mainly generated by the permanent magnet alone, resulting in the highest total flux linkage and the corresponding back electromotive force (EMF) reaching its maximum value at that speed. Since the back EMF amplitude is directly proportional to the motor speed, the no-load reference back EMF E1 at the same speed can be calculated based on the current speed. When the motor is running under load, a d-axis current component is generated in the stator current to output electromagnetic torque. The magnetic field generated by this component is opposite to the direction of the permanent magnet magnetic field, i.e., a demagnetizing effect is produced, which weakens the total flux linkage of the motor. According to the back EMF calculation formula, the decrease in total flux linkage will cause the back EMF amplitude to decrease synchronously. At this time, the actual back EMF calculated by the observer is E2, and E2 is less than the no-load reference back EMF E1 at the same speed.

[0079] The processing unit 102 is configured to perform a difference processing on the actual back EMF characteristic quantity and the reference back EMF characteristic quantity to obtain the back EMF difference value.

[0080] When the motor is running under no-load, the total flux linkage is strongest, and the back electromotive force (EMF) is at a relatively high level. When running under load, the demagnetizing effect generated by the stator current weakens the total flux linkage, resulting in an actual back EMF lower than the reference level. By performing a difference operation, the flux linkage change caused by the load can be quantified into a specific difference value, transforming the judgment of the load state into a comparison of numerical magnitudes, which facilitates the logical judgment in the program.

[0081] Specifically, the difference between the actual back EMF characteristic quantity and the reference back EMF characteristic quantity at the same time and speed is calculated to obtain the difference result. For example, the back EMF difference ΔE = E1 - E2.

[0082] The processing unit 102 is further configured to determine the load state of the motor based on the comparison result between the back electromotive force difference value and a preset threshold.

[0083] Load status refers to the level of load the motor is under during operation, mainly divided into no-load status and loaded status. The preset threshold is the judgment boundary used to distinguish between no-load and loaded status. The magnitude of the difference directly corresponds to the degree of flux weakening caused by the motor load. When the difference is in different ranges, it corresponds to different load levels of the motor, thereby realizing automatic identification of load status.

[0084] In some embodiments, the processing unit 102 determines the load state of the motor based on the comparison result between the back EMF difference value and a preset threshold, including: when the back EMF difference value is greater than or equal to the preset threshold and the duration reaches a preset duration, it determines that the motor is in a loaded state; when the back EMF difference value is less than the preset threshold and the duration reaches a preset duration, it determines that the motor is in an unloaded state.

[0085] The preset threshold is a critical value for the back EMF difference used to distinguish between no-load and loaded states; the preset duration is used to filter out misjudgments caused by instantaneous fluctuations. Only when the difference meets the threshold condition and continues to reach this duration will the corresponding load state be finally confirmed.

[0086] The magnitude of the back EMF difference directly corresponds to the degree of flux weakening caused by the motor load. The heavier the load, the more pronounced the demagnetizing effect, and the larger the back EMF difference. By dividing the difference range with a preset threshold, the continuously changing difference can be transformed into a clear load state classification. Adding a preset delay judgment mechanism can filter out short-term interference signals. Only when the difference state remains stable for the set duration is the change in load state confirmed, effectively avoiding misjudgments and frequent switching, and ensuring the smoothness and stability of the control process.

[0087] Specifically, the control system continuously calculates the back EMF difference value during operation and simultaneously times the state where the difference value meets the corresponding threshold condition. When the back EMF difference value is greater than or equal to the preset threshold and the duration of this state reaches the preset duration, the system determines that the motor is in a loaded state. When the back EMF difference value is less than the preset threshold and the duration of this state reaches the preset duration, the system determines that the motor is in an unloaded state.

[0088] The loading unit 103 is configured to select a matching PI parameter and load it onto the PI regulator based on the load state.

[0089] Motor control characteristics differ under different load conditions. A single PI parameter cannot simultaneously ensure control stability under both no-load and load conditions. An excessively high parameter under no-load conditions can cause current oscillations, while an excessively low parameter under load conditions can lead to sluggish response. By matching the PI parameter to the load condition, the speed and current regulation under different operating conditions can be kept in an appropriate parameter state, ensuring operational stability under all operating conditions.

[0090] In some implementations, the PI parameters include no-load PI parameters and loaded PI parameters; the no-load PI parameters are loaded onto the PI regulator in the no-load state, and the loaded PI parameters are loaded onto the PI regulator in the loaded state.

[0091] The no-load PI parameter corresponds to a smaller proportional coefficient, used to suppress current overshoot and control oscillations under no-load conditions. The load PI parameter corresponds to a larger proportional coefficient, used to improve the regulation response speed under load conditions.

[0092] The control characteristics of a motor differ significantly under different load conditions. Under no-load conditions, the equivalent load inertia of the motor is small, and the stator operating current amplitude is low. If the proportional coefficient of the PI parameter is too large, the current regulation response speed will be too fast, easily leading to current overshoot. In severe cases, it can cause current loop oscillation, ultimately manifesting as motor vibration, speed fluctuation, and increased operating noise. Under load conditions, the equivalent load inertia of the motor increases, and the operating current amplitude rises. If the proportional coefficient of the PI parameter is too small, the speed and current regulation response will be slow, and the speed recovery speed will be slow when the load is disturbed, making it impossible to quickly enter a stable operating state. Configuring dedicated PI parameters for no-load and load conditions allows the control loops under both conditions to operate with appropriate regulation parameters, balancing the stability of no-load operation and the response speed of load operation. This fundamentally solves the problem that a single PI parameter cannot simultaneously adapt to the control needs of all operating conditions.

[0093] Specifically, when the system determines that the motor is in an unloaded state, the unloaded PI parameters are loaded into the PI regulator of the control system, and the regulator performs closed-loop regulation of speed and current based on these parameters; when the system determines that the motor is in a loaded state, the loaded PI parameters are loaded into the PI regulator of the control system, and the regulator performs closed-loop regulation of speed and current based on these parameters.

[0094] This invention identifies the motor load state by using the back EMF difference value and adaptively switches PI parameters, eliminating the dependence on stator current switching thresholds in traditional solutions. It also eliminates the need to calibrate judgment parameters separately for different motors and loads, greatly improving the versatility of the solution and product adaptability. At the same time, it can match adaptive control parameters for different load conditions, ensuring stable motor speed and current under all operating conditions and suppressing operating vibration and noise.

[0095] Since the processing and functions implemented by the device in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0096] By employing the technical solution of this invention, the actual back EMF characteristic quantity and the reference back EMF characteristic quantity at the same speed are extracted and the difference is calculated. Combined with a preset threshold, the load state is determined, and then matching control parameters are loaded onto the PI regulator. This can break free from the limitation of the stator current threshold, greatly enhance the adaptability of different motors and load scenarios, and significantly reduce the debugging cost in the product adaptation stage.

[0097] According to an embodiment of the present invention, a motor corresponding to a motor adaptive PI control device is also provided. This motor may include the motor adaptive PI control device described above.

[0098] Since the processing and functions implemented by the motor in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned device, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0099] The technical solution of this invention identifies the motor load status based on the difference comparison of back EMF characteristic quantities. In a dual closed-loop motor control system including speed loop and current loop, the actual back EMF characteristic quantity and the reference back EMF characteristic quantity corresponding to the current speed are collected synchronously. After the difference is calculated, the load status is determined by combining it with a preset threshold. The corresponding parameters are then matched and loaded for the PI regulator. This eliminates the need to rely on the stator current switching threshold, effectively improving the universal adaptability in multiple scenarios and reducing the debugging workload of different motor and load combinations.

[0100] According to an embodiment of the present invention, a storage medium corresponding to the motor adaptive PI control method is also provided, the storage medium including a stored program, wherein the program controls the device where the storage medium is located to execute the motor adaptive PI control method described above when it is executed.

[0101] Since the processing and functions implemented by the storage medium in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0102] By employing the technical solution of this invention, in a dual closed-loop motor control system with speed loop and current loop, the actual back EMF characteristic quantity of the motor is extracted in real time, and the reference back EMF characteristic quantity corresponding to the current speed is calculated simultaneously. The difference between the two is used to obtain the back EMF difference value, which is then compared with a preset threshold to determine the load state. Adapted PI parameters are then loaded onto the PI regulator, eliminating reliance on the preset stator current switching threshold. This significantly improves the universal adaptability of the regulation logic and effectively compresses the adaptation cycle for different motor and load combinations.

[0103] According to an embodiment of the present invention, a computer program product corresponding to the motor adaptive PI control method is also provided. The computer program product includes a computer program that, when processed and executed, implements the steps of the above-described motor adaptive PI control method.

[0104] Since the processing and functions implemented by the computer program product in this embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0105] By adopting the technical solution of the present invention, in a dual closed-loop motor control system consisting of a speed loop and a current loop, the actual back EMF characteristic quantity of the current operation and the reference back EMF characteristic quantity of the corresponding speed are first obtained. After the load state is determined by difference calculation and threshold comparison, matching parameters are loaded for the PI regulator. This eliminates the traditional stator current switching threshold determination method, significantly improves the universal adaptability of the regulation logic, and reduces the debugging cost of different motor and load combinations.

[0106] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous methods can be freely combined and superimposed.

[0107] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A motor adaptive PI control method, applied to a dual closed-loop motor control system including a speed loop and a current loop, wherein the control system is equipped with a PI controller for speed and current regulation; characterized in that, The method includes: Obtain the actual back EMF characteristic quantity of the motor under the current operating state and the reference back EMF characteristic quantity corresponding to the current motor speed; The difference between the actual back EMF characteristic quantity and the reference back EMF characteristic quantity is processed to obtain the back EMF difference value; The load state of the motor is determined based on the comparison result between the back electromotive force difference value and the preset threshold. Based on the load status, select the matching PI parameters and load them into the PI regulator.

2. The adaptive PI control method for motors according to claim 1, characterized in that, Obtain the actual back electromotive force characteristic quantities of the motor under the current operating state, including: The actual back electromotive force characteristic quantity is obtained by calculating the voltage and current signals of the motor through the rotor position observer.

3. The adaptive PI control method for motors according to claim 1, characterized in that, Obtain the reference back electromotive force characteristic quantity corresponding to the current motor speed, including: Based on the direct proportionality between back EMF and rotational speed, the characteristic quantity of the reference back EMF at the corresponding rotational speed is calculated according to the current rotational speed of the motor.

4. The adaptive PI control method for motors according to claim 1, characterized in that, Based on the comparison between the back electromotive force difference value and a preset threshold, the load state of the motor is determined, including: When the back electromotive force difference is greater than or equal to a preset threshold and the duration reaches a preset duration, it is determined that the motor is in a loaded state. When the back electromotive force difference is less than a preset threshold and the duration reaches a preset duration, the motor is determined to be in an unloaded state.

5. The adaptive PI control method for motors according to any one of claims 1 to 4, characterized in that, The PI parameters include no-load PI parameters and loaded PI parameters; no-load PI parameters are applied to the PI regulator under no-load conditions, and loaded PI parameters are applied to the PI regulator under loaded conditions.

6. A motor adaptive PI control device, applied to a dual closed-loop motor control system including a speed loop and a current loop, wherein the control system is equipped with a PI controller for speed and current regulation; characterized in that, The device includes: The acquisition unit is configured to acquire the actual back EMF characteristic quantity of the motor under the current operating state and the reference back EMF characteristic quantity corresponding to the current motor speed. The processing unit is configured to perform a difference processing on the actual back EMF characteristic quantity and the reference back EMF characteristic quantity to obtain the back EMF difference value. The processing unit is further configured to determine the load state of the motor based on the comparison result between the back electromotive force difference value and a preset threshold. The loading unit is configured to select matching PI parameters and load them onto the PI regulator based on the load state.

7. An electric motor, characterized in that, include: The motor adaptive PI control device as described in claim 6.

8. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the storage medium to perform the motor adaptive PI control method as described in any one of claims 1 to 5.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the motor adaptive PI control method as described in any one of claims 1 to 5.

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