Method of controlling an electric machine and vehicle

Abstract

The application provides a motor control method and a vehicle, and relates to the technical field of motor control. The method comprises the following steps: determining an estimation strategy of a motor based on a voltage signal and a current signal of the motor, wherein the estimation strategy is that two modes of voltage signal injection estimation and adaptive sliding mode observation estimation are independently operated in parallel in different rotating speed intervals of a motor rotor; determining an estimation result of the motor rotor based on the estimation strategy, the voltage signal and the current signal, wherein the estimation result comprises an electrical angle position of the motor rotor; and controlling the motor to operate based on the estimation result. The technical problem of inaccurate position and speed observation of the motor rotor in the related art is solved.

Description

Technical Field

[0001] This application relates to the field of motor control technology, and in particular to a motor control method and a vehicle. Background Technology

[0002] In the drive system of new energy electric vehicles, permanent magnet synchronous motors are widely used due to their high power density, high efficiency and excellent speed regulation performance; traditional vector control relies on mechanical position sensors (such as rotary transformers, photoelectric encoders and eddy current sensors) to obtain the rotor position.

[0003] Related technologies utilize the fundamental wave model of the motor to estimate the rotor position and speed by detecting back electromotive force or flux linkage. Typical technologies include sliding mode observers, model reference adaptive systems, and extended Kalman filters. These methods have high estimation accuracy and dynamic response capabilities when running at medium and high speeds. However, at zero or extremely low speeds, the back electromotive force amplitude is too small, the signal-to-noise ratio is extremely low, and the position information cannot be effectively extracted, forming an observation "blind zone".

[0004] In summary, the relevant technologies suffer from the technical problem of inaccurate observation of the motor rotor's position and speed. Summary of the Invention

[0005] In view of the above problems, this application provides a motor control method and vehicle for improving the accuracy of motor rotor position and speed observation, and the technical solution is as follows: A method for controlling an electric motor, the method comprising: Based on the voltage and current signals of the motor, an estimation strategy for the motor is determined. The estimation strategy involves using two methods, voltage signal injection estimation and adaptive sliding mode observation estimation, to perform parallel and independent calculations in different speed ranges of the motor rotor. Based on the estimation strategy, the voltage signal, and the current signal, the estimation result of the motor rotor is determined, and the estimation result includes the electrical angle position of the motor rotor; Based on the estimation results, the motor is controlled to operate.

[0006] In this way, by first determining the first estimated speed based on the voltage and current signals, then dividing the operating range according to the first estimated speed and matching the corresponding estimation strategy, and finally determining the position estimation result based on the estimation strategy and controlling the motor operation, an appropriate estimation method can be adopted for different operating ranges, avoiding the limitations of a single estimation method and improving the accuracy of rotor position estimation and the reliability of motor operation under different operating conditions.

[0007] Optionally, the estimation strategy for determining the motor based on the motor's voltage and current signals includes: Based on the voltage and current signals, the initial speed of the motor rotor is determined; In response to the fact that the absolute value of the initial speed is less than the first speed threshold, the motor is determined to be in a first operating range. The first speed threshold corresponds to the lowest speed at which the motor back electromotive force is observed. The first operating range is the operating range in which the motor back electromotive force is relatively weak. In response to the absolute value of the initial speed being greater than or equal to the first speed threshold and less than or equal to the second speed threshold, it is determined that the motor is in a second operating range. The second operating range is a speed transition range between the first operating range and the third operating range. The second speed threshold corresponds to the upper limit speed at which additional losses are generated. The second speed threshold is greater than the first speed threshold. In response to the absolute value of the initial speed being greater than the second speed threshold, the motor is determined to be in a third operating range, which is the operating range where the motor has a strong back electromotive force; The estimation strategy is determined based on the first operating range, the second operating range, and the third operating range.

[0008] In this way, by dividing the operating range into three zones based on the absolute value of the first estimated speed, and clearly defining the first speed threshold as the effective lower limit of the third estimation strategy and the second speed threshold as the effective upper limit of the first estimation strategy, it is possible to simultaneously cover the forward and reverse operation of the motor, avoid the interference of speed polarity on the zone determination, and make the zone division based on the inherent physical characteristics of the estimation method, thereby improving the scientificity and stability of the zone division.

[0009] Optionally, determining the estimation strategy based on the first operating range, the second operating range, and the third operating range includes: In response to the operating range being the first operating range, the estimation strategy is determined to be the first estimation strategy, which is an estimation strategy based on voltage signal injection and relying on the motor salient pole effect to estimate the rotor position and speed. In response to the operating range being the second operating range, the estimation strategy is determined to be the second estimation strategy, which is an estimation strategy based on a weighted fusion of the output results of the first estimation strategy and the output results of the third estimation strategy; In response to the operating range being the third operating range, the estimation strategy is determined to be the third estimation strategy, which is an estimation strategy for rotor position and velocity estimation by observing back electromotive force through adaptive sliding mode.

[0010] In this way, by matching estimation strategies based on high-frequency signal injection, weighted fusion, and adaptive sliding mode observation to the first, second, and third operating ranges respectively, each operating range can adopt an estimation method that best suits its physical characteristics, solving the problem that a single estimation method cannot take into account the performance under all operating conditions and improving the adaptability of full-speed domain estimation.

[0011] Optionally, when the operating range is the first operating range, the method further includes: Obtain the current speed command of the motor, which represents the speed control command issued by the upper-level controller to the motor controller; Based on the current speed command, the voltage signal, and the current signal, the operating condition of the motor is determined; Based on the operating conditions, the injection parameters of the motor are determined, and the injection parameters are used to indicate characteristic parameters of the voltage signal injected into the motor; The estimation result is determined based on the injection parameters.

[0012] In this way, by obtaining the current speed command in the first operating range, combining it with the voltage and current signals to determine the motor operating conditions, and then determining the injection parameters based on the operating conditions, the injection parameters can be dynamically adjusted according to the real-time operating status of the motor. This avoids the defect that fixed injection parameters cannot adapt to changes in operating conditions and improves the matching degree between injection parameters and operating conditions.

[0013] Optionally, the operating conditions include light-load low-speed operating conditions and heavy-load high-speed operating conditions. Determining the injection parameters of the motor based on the operating conditions includes: In response to the motor being in the light-load, low-speed operating condition, the injection parameter is determined to be the first injection parameter; In response to the motor being in the heavy-load rapid operating condition, the injection parameter is determined to be a second injection parameter, wherein the amplitude and frequency corresponding to the second injection parameter are greater than the amplitude and frequency corresponding to the first injection parameter.

[0014] In this way, by injecting the corresponding voltage signal in the first operating range, collecting the current response signal and calculating the electrical angle position, the rotor position can be effectively obtained under the condition of weak back EMF without relying on the motor back EMF for estimation, thus solving the problem that the traditional back EMF observation method cannot stably estimate under low-speed conditions.

[0015] Optionally, determining the estimation result based on the injection parameters includes: Based on the injection parameters, a corresponding voltage signal is injected into the motor, and the current response signal of the motor after the voltage signal is injected is collected; The electrical angle position of the motor rotor is obtained by solving the current response signal. The estimation result is determined based on the electrical angle position.

[0016] In this way, by weighting and fusing the output results of the first estimation strategy and the third estimation strategy in the second operating interval, the advantages of the two estimation strategies can be combined, avoiding the performance shortcomings of a single strategy in the transition interval, and improving the continuity and stability of the rotor position estimation results in the transition interval.

[0017] Optionally, when the operating range is the second operating range, the method further includes: Obtain the estimation results output by the first estimation strategy and the third estimation strategy of the motor, as well as the initial estimated speed; Based on the initial estimated speed, the weighted fusion parameters of the motor are determined. The weighted fusion parameters are used to indicate the fusion weight ratio rule of the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy. Based on the weighted fusion parameters, the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy are fused to obtain the fused estimation value of the position and speed of the motor rotor. The estimation result is determined based on the fusion estimate.

[0018] In this way, by determining the adaptive parameters of sliding mode observation based on voltage and current signals in the third operating range, and then constructing an adaptive sliding mode observer based on these parameters and observing the back electromotive force, the core coefficient of the sliding mode observer can be dynamically adjusted according to the real-time operating state of the motor, thereby improving the adaptability of the sliding mode observer to changes in motor parameters and external disturbances.

[0019] Optionally, when the operating range is the third operating range, the method further includes: Based on the voltage signal and the current signal, the sliding mode observation adaptive parameters of the motor are determined. The sliding mode observation adaptive parameters are used to realize the sliding mode observer control rules and the motor parameter adaptive compensation rules. Based on the sliding mode observation adaptive parameters, the sliding mode observer is parameter compensated, and the back electromotive force observation signal output by the parameter-compensated sliding mode observer is acquired. The electrical angle position of the motor rotor is obtained by solving the back electromotive force observation signal; The estimation result is determined based on the electrical angle position.

[0020] In this way, the electrical angle position is obtained by calculating the back electromotive force in the third operating range, without the need for additional excitation signal injection. This avoids the additional losses and interference caused by the injected signal, and improves the operating efficiency and stability of the motor under medium and high speed conditions.

[0021] Optionally, controlling the motor operation based on the estimation result includes: Based on the estimation results, the current error signal is determined; Based on the current error signal, a motor drive control signal is generated; The motor is controlled to run based on the motor drive control signal.

[0022] In this way, by determining the current error signal based on the position estimation result, and then generating the motor drive control signal and controlling the motor operation, the drive control signal can be generated based on accurate rotor position information, thereby improving the accuracy and response speed of motor current control.

[0023] A control device for an electric motor, the device comprising: The first determining module is used to determine the estimation strategy of the motor based on the voltage and current signals of the motor. The estimation strategy is to use two methods, voltage signal injection estimation and adaptive sliding mode observation estimation, to be calculated in parallel and independently in different speed ranges of the motor rotor. The second determining module is used to determine the estimation result of the motor rotor based on the estimation strategy, the voltage signal and the current signal, wherein the estimation result includes the electrical angle position of the motor rotor; A control module is used to control the operation of the motor based on the estimation results.

[0024] A vehicle comprising: the vehicle performing a motor control method as described above for any of the optional motors.

[0025] By employing the above technical solution, this application provides a motor control method that determines a first estimated speed based on the existing voltage and current signals of the motor system. This allows for rapid acquisition of a preliminary judgment of the rotor speed without the need for additional hardware sensors, providing a real-time, low-cost basis for subsequent operating range division. Based on the first estimated speed, the motor's full-speed-range operating state is scientifically divided according to the strength of the back electromotive force and the applicability of the estimation method. This ensures that the range division conforms to the inherent physical characteristics of the motor rather than being arbitrarily set, laying the foundation for matching the estimation strategy. According to the divided operating ranges, the optimal estimation rule is dynamically matched and executed from a set of multiple differentiated rotor position estimation rules, fundamentally avoiding the inherent limitation that a single estimation method cannot simultaneously adapt to all operating conditions with vastly different back electromotive forces. Then, based on the matched optimal estimation strategy, the rotor position estimation result is determined, ensuring that the position estimation under each operating condition uses the most suitable method, effectively improving the accuracy of rotor position estimation under different operating conditions. Finally, the motor operation is controlled based on the accurate position estimation result, thereby improving the overall stability and control reliability of the motor.

[0026] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0027] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 One of the flowcharts of the motor control method provided in this application is shown; Figure 2 A second schematic flowchart of the motor control method provided in an embodiment of this application is shown; Figure 3 The third schematic flowchart of the motor control method provided in this application is shown; Figure 4 The fourth schematic flowchart of the motor control method provided in this application embodiment is shown; Figure 5 The fifth illustration shows a flowchart of the motor control method provided in an embodiment of this application; Figure 6 The sixth schematic flowchart of the motor control method provided in this application embodiment is shown; Figure 7A schematic diagram of the structure of a motor control device provided in an embodiment of this application is shown. Detailed Implementation

[0028] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0029] Traditional permanent magnet synchronous motor control systems often employ position sensors such as photoelectric encoders and rotary transformers to obtain rotor position information. However, the presence of position sensors not only increases system cost and size but also reduces system reliability under harsh conditions such as high temperature and strong vibration. Therefore, sensorless control technology has become a research hotspot in the field of motor control. Currently, sensorless motor control technology has mainly formed two mainstream technical routes: one is based on high-frequency signal injection, which is suitable for low-speed operation of the motor; the other is based on back EMF observation, which is suitable for medium- and high-speed operation of the motor.

[0030] Control methods based on high-frequency signal injection are only effective in the zero-speed range. When the motor enters the medium-speed range, the continuously injected high-frequency signal will couple with the motor's fundamental signal, causing a significant decrease in the accuracy of rotor position estimation. At the same time, the additional high-frequency injection will continuously generate power loss, torque pulsation, and electromagnetic noise, making it completely unsuitable for stable control in the medium-speed range. The observation accuracy of control methods in the medium-speed range based on back EMF observation is highly dependent on the accuracy of the motor's fundamental mathematical model. However, in automotive scenarios, the motor temperature rise causes a significant drift in stator resistance, and load magnetic saturation inevitably leads to significant changes in stator inductance and permanent magnet flux linkage parameters. The fixed mathematical model of conventional observers cannot completely offset the observation bias caused by such time-varying parameters, which easily leads to inaccurate observations and system instability. The parameter robustness defects are strongly tied to the model itself.

[0031] Although those skilled in the art have long been aware of the operating condition adaptability characteristics of the two types of schemes, they have long been unable to effectively integrate them. The core reason is that the technical principles, output characteristics, and operating conditions adaptable to the two types of schemes are completely mutually exclusive. Forcibly combining them will create new structural contradictions that cannot be resolved by conventional means. The design of the algorithm switching threshold for the two types of schemes presents an inherent dilemma. If the algorithm switching threshold is set at a lower speed, the back EMF amplitude is insufficient, and the back EMF-based observer has not yet entered its stable operating range, resulting in a sharp drop in observation accuracy after switching. If the switching threshold is set at a higher speed, the high-frequency injection signal has already severely coupled with the fundamental signal, significantly amplifying the position observation error. Control performance deteriorates even before switching. This dilemma cannot be solved by the conventional design of a fixed speed threshold. Simultaneously, the high-frequency… The position output of the injection method is based on the salient pole effect signal demodulation. Its error characteristics and dynamic response bandwidth are completely different from those of the sliding mode observer based on the fundamental wave model. There is no natural linear matching relationship between the observation outputs of the two. Simply using conventional weight allocation and simple switching will inevitably lead to a step jump in the position and speed estimates during the switching process, causing large fluctuations in speed and torque, and in severe cases, even causing the system to lose synchronization. In addition, existing conventional combination schemes need to extend the transition interval to achieve smooth switching, causing both types of algorithms to run under non-optimal conditions for a long time. The loss noise problem of high frequency injection and the insufficient accuracy of back EMF observation are amplified simultaneously. If the transition interval is shortened to ensure control accuracy, it will directly lead to the loss of smoothness in the switching process and torque jitter. This contradiction cannot be fundamentally solved within the relevant conventional technical framework.

[0032] To address the technical problem of improving the accuracy of rotor position and speed observation in related technologies, this application provides a motor control method, such as... Figure 1 As shown, Figure 1 This is a schematic flowchart illustrating a motor control method provided in an embodiment of this application. The method includes: S11. Determine the motor estimation strategy based on the motor's voltage and current signals.

[0033] The estimation strategy is used to match and execute the rotor position and speed estimation rules based on the real-time operating state of the motor represented by voltage and current signals. The estimation strategy employs two parallel and independent methods—voltage signal injection estimation and adaptive sliding mode observation estimation—across different rotor speed ranges. Voltage signal: refers to the electrical signal obtained by sampling the instantaneous voltage across the three-phase stator windings of the motor through the voltage sampling circuit built into the motor controller. It is a fundamental physical quantity reflecting the stator magnetic field state. Examples include Ua, Ub, and Uc signals in the three-phase stationary coordinate system, and uα and uβ signals in the two-phase stationary coordinate system obtained after coordinate transformation. Current signal: refers to the electrical signal obtained by sampling the instantaneous current flowing through the three-phase stator windings of the motor through the current sampling circuit built into the motor controller. It directly reflects the motor's load, torque output state, and operating conditions. Examples: Includes Ia, Ib, and Ic signals in a three-phase stationary coordinate system, and iα and iβ signals in a two-phase stationary coordinate system obtained after coordinate transformation; Estimation strategy: refers to a set of multiple differentiated rotor position and speed estimation rules pre-stored in the non-volatile memory of the motor controller. Each set of rules corresponds to an independent estimation algorithm with different applicable operating conditions and performance characteristics. Examples: Includes high-frequency signal injection estimation strategy, weighted fusion estimation strategy, adaptive sliding mode observation estimation strategy, etc.; Real-time operating state refers to the motor's operating state at a certain moment, characterized by multiple characteristic quantities of voltage and current signals. Different operating states correspond to the applicability of different estimation methods. Examples: Includes zero-low speed operating state, transitional operating state, medium-high speed operating state, light-load operating state, heavy-load operating state, steady-state operating state, dynamic operating state, etc.

[0034] Specifically, the raw voltage and current signals acquired in real time are preprocessed, including low-pass filtering to remove high-frequency noise, dead-zone compensation to eliminate inverter nonlinearity errors, and amplitude calibration to correct sampling errors, resulting in clean and accurate voltage and current signals. Multiple feature quantities characterizing the motor's operating state are extracted from the preprocessed voltage and current signals. These feature quantities include, but are not limited to, the first estimated speed, current amplitude, voltage amplitude, power factor, estimated torque, estimated stator resistance, and estimated stator inductance. The extracted feature quantities are compared with pre-set state determination thresholds to determine the motor's current operating state. Based on the pre-established correspondence between operating states and estimation rules, an estimation rule corresponding to the current operating state is matched from the set of estimation rules to serve as the estimation strategy for the current moment.

[0035] For example, the three-phase stator voltages Ua, Ub, Uc and three-phase stator currents Ia, Ib, Ic of the motor are acquired at a sampling frequency of 10kHz using the 12-bit ADC sampling circuit of the motor controller. The acquired raw signals are then preprocessed: a Butterworth low-pass filter with a cutoff frequency of 2kHz is used to remove high-frequency noise; a preset dead-time compensation table is used to eliminate voltage errors caused by the dead time of the inverter switching transistors; and factory calibration coefficients are used to correct the gain and offset errors of the sampling circuit. The voltage and current signals in the three-phase stationary coordinate system are converted into stator voltages uα, uβ and stator currents iα, iβ in the two-phase stationary coordinate system using Clark transformation. Finally, based on uα, uβ and iα, iβ, the signals are processed by... The fundamental wave mathematical model calculates the first estimated speed ω1 of the motor rotor. The motor operating state is determined based on the absolute value of the first estimated speed ω1: when |ω1| is less than the first speed threshold (e.g., 100 rpm), it is determined to be a zero-low speed operating state; when |ω1| is greater than or equal to the first speed threshold and less than or equal to the second speed threshold (e.g., 500 rpm), it is determined to be a transitional operating state; when |ω1| is greater than the second speed threshold, it is determined to be a medium-high speed operating state. Finally, according to the pre-established correspondence, a high-frequency signal injection estimation rule is matched for the zero-low speed operating state, a weighted fusion estimation rule is matched for the transitional operating state, and an adaptive sliding mode observation estimation rule is matched for the medium-high speed operating state, which serves as the estimation strategy for the current moment.

[0036] In this embodiment, the estimation strategy can be determined using only the signals obtained from the voltage and current sampling circuits that are standard on the motor control system. There is no need to add additional position sensors, speed sensors or other dedicated detection hardware, which will not increase the hardware cost and size of the system. By establishing the correspondence between "signal characteristics - operating status - estimation rules", the estimation method can be dynamically matched, which can avoid the inherent limitation that a single estimation algorithm can only work effectively under specific operating conditions. The estimation method can be automatically adjusted with the changes in the motor operating status, which helps to improve the effectiveness of rotor position estimation under different operating conditions and enhance the stability of system operation.

[0037] S12. Based on the estimation strategy, voltage signal, and current signal, determine the estimation result of the motor rotor.

[0038] The estimation result refers to the physical quantities related to the motor rotor's operating state obtained after processing the voltage and current signals using an estimation strategy. Examples include the motor rotor's electrical angular position, mechanical angular position, rotor speed, rotor acceleration, and rotor flux linkage amplitude. Electrical angular position refers to the angular position of the magnetic field generated by the permanent magnets of the motor rotor relative to the axis of the three-phase stator windings, and is a core reference parameter for coordinate transformation in motor vector control.

[0039] Specifically, according to the estimation strategy determined in step S11, the corresponding algorithm execution module is loaded, and the module's operating parameters are initialized. Real-time acquired and preprocessed voltage and current signals are input into the algorithm execution module. The algorithm execution module processes the input voltage and current signals according to its internal operational logic to obtain intermediate calculation results. Post-processing of the intermediate calculation results is performed, including filtering and smoothing, outlier removal, and angle normalization, to obtain and output the final motor rotor estimation result. The operating parameters of the algorithm execution module can be adaptively adjusted according to the motor's operating state. The basis for parameter adjustment includes, but is not limited to, speed, load, temperature, and voltage fluctuations. In addition to the electrical angle position, the estimation result may also include rotor speed, rotor acceleration, and rotor flux amplitude calculated based on the electrical angle position. Post-processing includes, but is not limited to, low-pass filtering, median filtering, moving average filtering, angle limiting, and angle normalization.

[0040] In one specific embodiment, when the estimation result is abnormal, the valid estimation result from the previous moment is used as a substitute, and the fault diagnosis process is triggered.

[0041] For example, when the estimation strategy determined in step S11 is a high-frequency signal injection estimation rule, the corresponding high-frequency signal demodulation module is loaded, and the module parameters are initialized: the injection voltage amplitude is 10V, the injection frequency is 1kHz, the center frequency of the bandpass filter is 1kHz, and the bandwidth is 200Hz; a preset high-frequency pulsating voltage signal is injected into the stator winding of the motor, which is superimposed on the fundamental voltage signal of the motor; then the stator current signal superimposed with high-frequency components is acquired, and the high-frequency current response component is extracted through the bandpass filter; then the rotor salient pole position information, including the amplitude and phase of the high-frequency current, is extracted from the high-frequency current response component through the signal demodulation algorithm; finally, the salient pole position information is processed through the arctangent function to calculate the electrical angle position θ of the motor rotor, and θ is normalized from 0° to 360°.

[0042] In this embodiment, the voltage and current signals are processed using an estimation strategy corresponding to the current operating state. This fully leverages the performance characteristics of different estimation methods under their respective applicable operating conditions, avoiding the problem of a single algorithm's estimation effect decreasing or even failing to estimate under unsuitable operating conditions. It helps to obtain stable rotor position estimation results over a wide range of motor speeds, providing a reliable position reference for subsequent motor control.

[0043] S13. Based on the estimation results, control the motor operation.

[0044] Specifically, the rotor electrical angle position obtained in step S12 is used as the reference angle for coordinate transformation; then, the physical quantities of the motor in the three-phase stationary coordinate system are converted into physical quantities in the two-phase rotating coordinate system that are easier to control through coordinate transformation; then, a current closed-loop control is constructed in the two-phase rotating coordinate system to obtain the voltage control command of the motor; finally, the voltage control command is converted into the inverter drive signal through pulse width modulation technology to control the on and off of the inverter power switching transistors, thereby controlling the motor operation.

[0045] In this embodiment, motor control based on rotor position estimation results can provide an accurate coordinate transformation reference for motor vector control, which helps to improve the effectiveness of current closed-loop control and reduce motor torque pulsation and speed fluctuation. It does not rely on position sensors, which can improve the reliability of the system under harsh conditions such as high temperature, strong vibration, and high humidity, and extend the service life of the system. It also helps to improve the dynamic response performance and steady-state operation performance of the motor, and improve the overall control effect of the motor.

[0046] In the above scheme, the first estimated speed is determined based on the existing voltage and current signals of the motor system. This allows for a rapid preliminary assessment of the rotor speed without the need for additional hardware sensors, providing a real-time, low-cost basis for subsequent operating range division. Based on the first estimated speed, the motor's full-speed-range operating states are scientifically divided according to the strength of the back electromotive force and the applicability of the estimation method. This ensures that the range division conforms to the inherent physical characteristics of the motor rather than being arbitrarily set, laying the foundation for matching the estimation strategy. According to the divided operating ranges, the optimal estimation rule is dynamically matched and executed from a set of multiple differentiated rotor position estimation rules, fundamentally avoiding the inherent limitation of a single estimation method being unable to simultaneously adapt to all operating conditions with vastly different back electromotive forces. Then, the rotor position estimation result is determined based on the matched optimal estimation strategy, ensuring that the most suitable method is used for position estimation under each operating condition, effectively improving the accuracy of rotor position estimation under different operating conditions. Finally, the motor operation is controlled based on the accurate position estimation result, thereby improving the overall stability and control reliability of the motor.

[0047] In some embodiments, such as Figure 2 As shown, based on the motor's voltage and current signals, the estimation strategy for the motor is determined, including: S111. Determine the initial speed of the motor rotor based on the voltage and current signals.

[0048] Among them, the estimated rotor speed used for the initial division of the motor's operating range is a rough speed result obtained by rapidly calculating the voltage and current signals based on the motor's fundamental mathematical model.

[0049] Specifically, the preprocessed voltage and current signals are acquired; then the preprocessed signals are substituted into the pre-established mathematical model of the motor fundamental frequency for calculation; finally, the initial speed of the motor rotor is obtained and output.

[0050] In this embodiment, the initial speed of the motor rotor can be calculated using only the existing voltage and current sampling signals of the motor control system, without the need for additional speed sensors or other detection hardware, thus not increasing system costs. It can quickly obtain the preliminary judgment result of the motor rotor speed, providing a real-time basis for the subsequent division of the operating range, which helps to improve the system's response speed.

[0051] S112. In response to the absolute value of the initial speed being less than the first speed threshold, the motor is determined to be in the first operating range.

[0052] The first speed threshold refers to a pre-set critical speed value used to divide the first operating range into the second operating range, corresponding to the lowest speed at which the third estimation strategy can work effectively. Example: This threshold can be set according to the motor parameters, application scenario, and the performance of the estimation method, and is typically set to a value between 50 rpm and 200 rpm. The first operating range can also be called the zero-low-speed zone: this refers to the operating range where the motor speed is low and the back electromotive force is relatively weak. Within this first operating range, the estimation method based on back electromotive force is unlikely to obtain effective estimation results.

[0053] Specifically, the absolute value of the initial speed obtained in step S111 is calculated; then, the absolute value of the initial speed is compared with a pre-stored first speed threshold; when it is determined that the absolute value of the initial speed is less than the first speed threshold, it indicates that the current speed level of the motor is in a low range, and the amplitude of the back electromotive force generated by the rotation of the motor rotor is low. Based on this, it is determined that the motor is currently in the first operating range. For example, assuming the initial speed is... The first speed threshold is ω1. When |ω|<ω1, the motor is determined to be in the first operating range.

[0054] In this embodiment, the low-speed operating range of the motor is clearly defined by the first speed threshold, which can distinguish the weak back EMF condition from other conditions, laying the foundation for matching an estimation strategy suitable for the low-speed condition and helping to avoid the problem of estimation failure under the low-speed condition.

[0055] S113. In response to the absolute value of the initial speed being greater than the second speed threshold, determine that the motor is in the third operating range.

[0056] The third operating range, also known as the medium-high speed range, refers to the operating range where the motor speed is relatively high and the back electromotive force is relatively strong. The estimation method based on back electromotive force can achieve better estimation results in this third operating range. Back electromotive force: refers to the induced electromotive force generated when the permanent magnet magnetic field cuts the stator winding when the motor rotor rotates. Its amplitude is proportional to the motor speed.

[0057] Specifically, the absolute value of the initial speed obtained in step S111 is calculated; then, the absolute value of the initial speed is compared with a pre-stored second speed threshold; when the absolute value of the initial speed is greater than the second speed threshold, it indicates that the motor's current speed level has entered the medium-high speed range. Based on this, it is determined that the motor is currently in the third operating range. For example, assuming the initial speed is... The second speed threshold is ω2. When |ω|>ω2, the motor is determined to be in the third operating range.

[0058] In this embodiment, the medium-to-high speed operating range of the motor is clearly defined by the second speed threshold, which can distinguish the operating conditions with strong back electromotive force from other operating conditions. This lays the foundation for subsequent matching of estimation strategies suitable for medium-to-high speed operating conditions and helps to avoid the additional losses and electromagnetic noise problems caused by high-frequency injection signals under medium-to-high speed operating conditions.

[0059] S114. In response to the absolute value of the initial speed being greater than or equal to the first speed threshold and less than or equal to the second speed threshold, determine that the motor is in the second operating range.

[0060] The second operating range, also known as the transition zone, refers to the speed transition zone between the first and third operating ranges. Within this second operating range, both the first and third estimation strategies can achieve certain estimation results, but each has limitations when used alone. The second speed threshold is a pre-set critical speed value used to divide the second and third operating ranges; it corresponds to the speed at which the additional losses generated by the first estimation strategy reach an acceptable upper limit. Example: It can be set according to the motor's loss characteristics, noise requirements, and application scenarios, typically between 300 rpm and 1000 rpm. The second speed threshold can be set according to the motor's loss characteristics and electromagnetic noise requirements. The second speed threshold can be adjusted online according to the motor's operating temperature and load status. Additional losses refer to the additional copper losses, iron losses, and inverter switching losses generated due to the injection of high-frequency signals into the motor, which reduce the motor's operating efficiency.

[0061] Specifically, the absolute value of the initial rotational speed obtained in step S111 is calculated; then, the absolute value of the initial rotational speed is compared with the first rotational speed threshold and the second rotational speed threshold respectively; when it is determined that the absolute value of the initial rotational speed is greater than or equal to the first rotational speed threshold and less than or equal to the second rotational speed threshold, it indicates that the amplitude of the back electromotive force generated by the rotation of the motor rotor has reached the lowest observable level. Based on this, it is determined that the motor is currently in the second operating range. For example, assuming the initial rotational speed is... The first speed threshold is ω1, and the second speed threshold is ω2. When ω1≤|ω|≤ω2, the motor is determined to be in the second operating range.

[0062] In this embodiment, by setting the second operating range as a transition area between the first and third operating ranges, the problem of abrupt changes in estimation results caused by direct switching between the two estimation strategies can be avoided. At the same time, by setting the second speed threshold as the upper limit speed at which additional losses occur, the additional losses caused by the high-frequency injection signal can be controlled within an acceptable range while ensuring the estimation effect.

[0063] S115. Determine the estimation strategy based on the first operating range, the second operating range, and the third operating range.

[0064] The fact that the operating range is the first operating range indicates that the motor is currently in a low-speed condition with weak back EMF. The third estimation strategy based on back EMF cannot obtain effective estimation results. However, the first estimation strategy based on voltage signal injection and relying on the salient pole effect of the motor does not depend on back EMF and can obtain effective estimation results under this condition, making it more suitable for the current operating state. Therefore, the first estimation strategy is determined to be the first estimation strategy. The first estimation strategy is an estimation strategy that estimates the rotor position and speed based on voltage signal injection and relying on the salient pole effect of the motor. It can also be called the high-frequency signal injection estimation strategy. Among them, voltage signal injection refers to injecting an additional high-frequency voltage excitation signal into the stator winding of the motor. This signal is superimposed on the fundamental voltage signal of the motor to excite the salient pole characteristics of the motor. Salient pole effect: refers to the physical characteristic that the inductance value of the stator winding of the permanent magnet synchronous motor changes with the rotor position. It is the physical basis for the high-frequency injection method to realize rotor position estimation.

[0065] In this embodiment, an estimation strategy based on voltage signal injection is matched for the first operating range where the back EMF is weak. This first estimation strategy does not rely on the back EMF of the motor for estimation, which can solve the problem that the traditional back EMF observation method cannot work effectively under low-speed conditions. It only uses the inherent salient pole characteristics of the motor to extract rotor position information without the need for additional hardware, which helps to improve the effectiveness of rotor position estimation under low-speed conditions and ensure the stability of the motor at low speed.

[0066] The fact that the operating range is the third operating range indicates that the motor is currently operating at a medium-to-high speed. The back EMF generated by the rotor rotation has sufficient amplitude and the signal-to-noise ratio meets the observation requirements, supporting the stable operation of the estimation method based on back EMF observation. However, continuing to inject high-frequency voltage signals would introduce significant additional losses, noise, and fundamental frequency coupling interference, which is detrimental to the efficient and stable operation of the motor. Therefore, the third estimation strategy is determined, which is an estimation strategy that uses adaptive sliding mode observation of back EMF to estimate the rotor position and speed. Adaptive sliding mode observation refers to a sliding mode observation method with parameter self-adaptation capabilities, capable of adjusting the observer parameters online to compensate for the effects of motor parameter changes and external disturbances. Back EMF observation refers to a method of estimating the back EMF inside the motor, which cannot be directly measured, using the motor's mathematical model and measurable voltage and current signals.

[0067] In this embodiment, an adaptive sliding mode observation estimation strategy is matched for the third operating range with a strong back electromotive force. This third estimation strategy does not require injecting additional excitation signals into the motor, and there are no additional losses or electromagnetic noise problems, which helps to improve the efficiency and stability of the motor at medium and high speeds. Through the adaptive parameter compensation mechanism, the influence of changes in motor parameters can be offset to a certain extent, which helps to improve the robustness of the estimation results.

[0068] The fact that the operating range is the second operating range indicates that the motor is currently in the transition speed range between low speed and medium-high speed. On the one hand, the back electromotive force has reached a certain amplitude, and the third estimation strategy can output a preliminary estimation result, but its stability still has room for improvement. On the other hand, the additional losses and signal coupling effects brought about by the injection of high-frequency voltage signals are gradually increasing. Using the first estimation strategy alone is not conducive to the system operating efficiency and estimation effect. It is difficult to obtain better performance in this range by using any strategy alone. Based on this, the second estimation strategy is determined. The second estimation strategy is an estimation strategy that uses weighted fusion of the output results of the first estimation strategy and the output results of the third estimation strategy to achieve smooth transition of the range and suppression of estimation jitter. It can also be called a weighted fusion estimation strategy. The weighted fusion method includes, but is not limited to, linear weighted fusion, exponential weighted fusion, and fuzzy weighted fusion.

[0069] In this embodiment, a weighted fusion estimation strategy that matches the cross-application range of two estimation strategies is used. This strategy combines the performance advantages of the first and third estimation strategies, avoiding the performance shortcomings of a single strategy in the transition range. By using a weighted fusion approach, the two estimation strategies can be smoothly switched, which can solve the problem of abrupt changes in estimation results caused by hard switching. This helps to improve the continuity of rotor position estimation results in the transition range and reduce motor torque pulsation and speed fluctuations.

[0070] In this embodiment, by matching corresponding estimation strategies to different operating ranges, the performance characteristics of different estimation methods under their respective applicable operating conditions can be fully utilized, avoiding the inherent limitations of a single estimation method being unable to adapt to all operating conditions. By adopting a weighted fusion strategy in the transition range, a smooth transition between different estimation strategies can be achieved, which helps to improve the stability and continuity of rotor position estimation across the entire speed range.

[0071] In the above scheme, steps S111 to S115 determine the initial speed of the motor based on voltage and current signals, and scientifically divide the first, second, and third operating ranges by combining dual speed thresholds. This clarifies the operating characteristics of each range and the adaptability of the estimation method. Then, corresponding estimation strategies are matched for different ranges. No additional hardware sensors are required, which avoids the inherent limitation that a single estimation method cannot adapt to all operating conditions. It achieves dynamic adaptation between the estimation strategy and the real-time operating status of the motor, laying the foundation for reliable estimation of rotor position and speed. At the same time, it takes into account the estimation effect, system efficiency, and operational stability under different operating conditions, and improves the robustness of sensorless motor control.

[0072] In some embodiments, such as Figure 3 As shown, when the operating range is the first operating range, the method further includes: S1211, Obtain the current motor speed command.

[0073] Among them, the current speed command is used to represent the speed control command issued by the upper controller to the motor controller. The upper controller in the vehicle system usually refers to the vehicle controller. The motor controller receives the speed command and executes the motor closed-loop control, and is responsible for completing actions such as rotor estimation, current loop adjustment, and driving the inverter.

[0074] Specifically, the motor controller receives speed command signals from the upper-level controller in real time through a communication interface or signal acquisition port; after format parsing, filtering or limiting the speed command signal, it is used as a key input reflecting the system control requirements and participates in the comprehensive judgment of subsequent operating conditions.

[0075] In this embodiment, by obtaining the current speed command from the upper-level controller, the target operating speed information of the motor can be directly obtained, providing an external command-level basis for subsequent judgment of the motor's operating condition. This makes the condition judgment not only rely on the internal electrical signals of the motor, but also combine the system-level control intent, which is conducive to improving the rationality of subsequent injection parameter selection and making high-frequency injection behavior more in line with the actual control needs of the whole vehicle or the whole machine.

[0076] S1212. Determine the operating conditions of the motor based on the current speed command, voltage signal, and current signal.

[0077] The operating conditions are determined by the motor's operating state, which is jointly determined by the speed requirement, load size, and dynamic response speed. In this embodiment, they are divided into light-load low-speed condition and heavy-load high-speed condition. Light-load low-speed condition: the operating state with a low target motor speed, low output torque, and low current amplitude; heavy-load high-speed condition: the operating state with a rapid change in the target motor speed, high output torque, and significantly higher current amplitude.

[0078] Specifically, first, determine the speed requirement level based on the current speed command; second, determine the motor load based on the amplitude and rate of change of the current signal; and third, determine the current excitation level of the motor by combining the voltage signal. Combining the above three types of information, the motor operating status is classified as either light load low speed condition or heavy load high speed condition.

[0079] For example, when the target speed corresponding to the current speed command is low, and the amplitude of the motor's three-phase current is small and the current change is gradual, the motor is determined to be in a light-load, low-speed operating condition. When the current speed command rises rapidly, the target speed increases significantly, and the motor current amplitude increases significantly, indicating an increase in the motor's output torque, the motor is determined to be in a heavy-load, high-speed operating condition. By reflecting demand through speed commands and reflecting the actual load through voltage and current, a comprehensive judgment of the operating condition can be achieved.

[0080] In this embodiment, the external speed command is combined with the real-time voltage and current signals inside the motor to determine the operating condition. This can simultaneously reflect the control requirements and the actual electrical state of the motor, making the division of operating conditions more in line with the actual load and dynamic requirements. This avoids the deviation caused by relying on a single signal for judgment and provides a reliable basis for the adaptive adjustment of subsequent injected parameters.

[0081] S1213. Determine the injection parameters of the motor based on the operating conditions.

[0082] Among them, the injection parameters are used to indicate the characteristic parameters of the voltage signal injected into the motor, and are used to describe the characteristics of the high-frequency injected voltage signal, mainly including amplitude, frequency, waveform type, etc.

[0083] Specifically, the operating conditions include light-load low-speed and heavy-load high-speed conditions. Based on the operating conditions, in response to the motor being in light-load low-speed condition, the injection parameter is determined as the first injection parameter. The first injection parameter is suitable for light-load low-speed condition, with a lower amplitude and frequency to reduce losses and noise. For example, the preset first injection parameter is a high-frequency pulse voltage with an amplitude of 8V and a frequency of 1kHz. In response to the motor being in heavy-load high-speed condition, the injection parameter is determined as the second injection parameter. The second injection parameter is suitable for heavy-load high-speed condition, with a higher amplitude. The second injection parameter has a higher frequency to enhance the salient pole response and anti-interference capability. The amplitude and frequency of the second injection parameter are greater than those of the first injection parameter. For example, the second injection parameter is a high-frequency pulse voltage with an amplitude of 15V and a frequency of 2kHz. That is, according to the operating condition type determined by S1212, the corresponding injection parameter group is called from the preset parameter table. If it is a light load and low speed condition, the first injection parameter is selected; if it is a heavy load and fast speed condition, the second injection parameter is selected. Finally, the determined injection parameters are output to the signal generation module to construct the voltage signal to be injected.

[0084] Among them, the light load and low speed operating condition refers to the operating state where the motor speed is lower than the first speed threshold and the load current is small. At this time, the back electromotive force signal of the motor is weak, and the position estimation needs to be achieved by injecting a high-frequency signal. However, since the load is light, there is no need for an excessively high injection signal strength. By reducing the amplitude and frequency of the high-frequency injection signal, the additional torque ripple can be effectively reduced, high-frequency noise can be suppressed, and system losses can be reduced. The heavy load and fast operating condition refers to the operating state where the motor speed is lower than the first speed threshold and the load current is large or a fast start / large torque output is required. At this time, in order to ensure the robustness and accuracy of rotor position observation and avoid position estimation loss, it is necessary to increase the amplitude and frequency of the high-frequency injection signal and enhance the high-frequency response signal strength, so as to achieve smooth start and reliable operation with high torque at zero speed or low speed.

[0085] It should be noted that for light-load high-speed operation, the motor speed is already higher than the second speed threshold, and the back EMF signal is strong enough. It automatically switches to the medium-high speed range and uses an adaptive sliding mode observer to complete the position and speed estimation. There is no need to inject high-frequency signals. Therefore, it is not the target of the adaptive high-frequency injection strategy and will not be discussed further. For heavy-load low-speed operation, it is essentially a high-load operation state in the zero low-speed range. The adjustment logic is the same as that of heavy-load fast operation. Both need to increase the amplitude and frequency of high-frequency injection to ensure the observation accuracy. This is already included in the technical solution for heavy-load fast operation.

[0086] In this embodiment, by matching the corresponding injection parameters according to different operating conditions, a smaller amplitude and frequency injection signal can be used in light load and low speed scenarios to reduce unnecessary losses and noise; while a higher amplitude and frequency injection signal can be used in heavy load and fast scenarios to improve the reliability of current response and anti-interference capability, thereby balancing estimation effect, system efficiency and operational stability under different operating conditions.

[0087] S1214. Determine the estimation result based on the injection parameters.

[0088] Specifically, based on the injection parameters, a corresponding voltage signal is injected into the motor, and the current response signal of the motor after the injection voltage signal is acquired. The high-frequency electrical component corresponding to the injected voltage signal is separated from the current response signal. Based on the high-frequency electrical component, the salient pole position characteristics of the motor rotor are determined. The electrical angle position of the motor rotor is calculated based on the salient pole position characteristics. For example, through filtering, demodulation, and phase extraction, the rotor electrical angle position is reconstructed from the high-frequency current response. The electrical angle position, the angle of the rotor magnetic field relative to the stator winding, is the core position information necessary for vector control. Based on the electrical angle position, the estimation result is determined; that is, a corresponding high-frequency voltage signal is generated according to the injection parameters and superimposed on the fundamental voltage. Then, the motor stator current is sampled, and the high-frequency response component is extracted. The component related to the rotor position is obtained through a signal demodulation algorithm. The electrical angle position is calculated, and this constitutes the estimation result containing position information.

[0089] In this embodiment, performing high-frequency voltage injection and current response calculation according to the matched injection parameters enables the position estimation process to be highly adapted to the current operating conditions. While ensuring the effective extraction of the rotor position, it avoids the problems of excessive loss or insufficient anti-interference caused by fixed injection parameters, which is conducive to improving the stability and adaptability of the estimation results in the first operating range.

[0090] In the above scheme, steps S1211 to S1214 target the low-speed condition in the first operating range. By obtaining the current speed command from the upper controller and combining it with voltage and current signals, the operating condition of the motor is comprehensively judged, and then the corresponding high-frequency voltage injection parameters are adaptively matched. For light-load low-speed conditions, low-amplitude and low-frequency injection parameters are used to reduce losses and noise, while for heavy-load fast conditions, high-amplitude and high-frequency injection parameters are used to improve anti-interference capability. Then, based on the injection parameters, voltage injection and current response acquisition and calculation are completed, which solves the estimation problem caused by the weak back electromotive force under low-speed conditions, improves the stability and adaptability of rotor position estimation in the first operating range, and ensures the smooth operation of the motor at low speeds.

[0091] In some embodiments, such as Figure 4 As shown, when the operating range is the second operating range, the method further includes: S1221. Obtain the estimation results output by the first estimation strategy and the third estimation strategy of the motor, as well as the initial estimated speed.

[0092] Specifically, the motor controller runs the first estimation strategy and the third estimation strategy in parallel within the second operating range; it reads the rotor position and speed related results obtained by the two strategies respectively; at the same time, it reads the initial estimated speed determined in the previous steps; and it caches the above three types of information in a unified manner as input data for subsequent weighted fusion processing.

[0093] In this embodiment, the output results of the two estimation strategies and the initial estimated speed are acquired simultaneously in the second operating interval. This can make full use of the estimation information of the low-speed estimation method and the medium-to-high-speed estimation method in the transition interval, providing multi-source data support for subsequent fusion processing, which is conducive to improving the integrity and reliability of rotor position and speed information in the transition interval.

[0094] S1222. Based on the initial estimated speed, determine the weighted fusion parameters of the motor.

[0095] The weighted fusion parameter is used to indicate the fusion weighting rule between the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy.

[0096] Specifically, the initial estimated speed is substituted into the preset weight calculation rules; based on the relative position of the speed between the first speed threshold and the second speed threshold, the weight coefficients corresponding to the first estimation result and the third estimation result are calculated; the weight coefficients are made to show a continuous changing trend as the speed increases, thus completing the determination of the weighted fusion parameters.

[0097] For example, suppose the first speed threshold is 100 rpm and the second speed threshold is 500 rpm. The weighting coefficient k is calculated based on the initial estimated speed ω, k = (ω0... 100) / (500 100), where k ranges from 0 to 1. The weight of the first estimation result is 1. k is the weight of the third estimation result. For example, when ω=300rpm, k=0.5, and the two estimation results each account for half of the weight; when ω is close to 100rpm, the first estimation result has a higher weight; when ω is close to 500rpm, the third estimation result has a higher weight.

[0098] In this embodiment, the weighted fusion parameters are determined based on the initial estimated speed, which allows the weight ratio to change continuously with the actual speed of the motor in the transition range. This enables the fusion rules to dynamically adapt to the current operating conditions of the motor, which helps to smoothly transition the contribution levels of the two estimation results and lays the foundation for obtaining continuous and stable fusion results in the future.

[0099] S1223. Based on the weighted fusion parameters, the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy are fused to obtain the fused estimation value of the position and speed of the motor rotor.

[0100] Specifically, the first estimation result, the third estimation result, and the corresponding weighted fusion parameters are read respectively; the rotor position information and speed information are weighted according to the weight coefficients respectively; the calculation results are post-processed such as amplitude limiting and smoothing to finally obtain the fused rotor position and speed estimation value.

[0101] In this embodiment, the two types of estimation results are fused according to weighted fusion parameters adapted to the rotational speed. This combines the advantages of the high-frequency injection method in the low-speed range and the sliding mode observation method in the medium- and high-speed range, weakens the shortcomings of a single estimation method in the transition range, and helps to improve the continuity of the estimation results, reduce estimation jitter and abrupt changes, and improve the stability of the motor operation in the transition range.

[0102] S1224. The fusion estimate is determined as the estimation result.

[0103] Specifically, the fusion estimate obtained in S1223 is formatted and normalized; the angle is periodically constrained and the rotational speed is range-limited; after removing outliers, it is determined as the final result for motor control at the current moment and output.

[0104] In this embodiment, the fused estimated value is directly used as the final estimation result, which can fully reflect the advantages of multi-strategy fusion in the transition interval, making the final output rotor position and speed information smoother and more stable. This is beneficial for providing a reliable position and speed reference for motor control and improving the control effect of the motor during the interval switching process.

[0105] In the above scheme, steps S1221 to S1224 are for the transitional working condition of the second operating range. The output results of the first estimation strategy and the third estimation strategy and the initial estimated speed are obtained simultaneously. The dynamically changing weighted fusion parameters are determined based on the initial estimated speed. By combining the advantages of the two estimation strategies through weighted fusion, the shortcomings of the single strategy in the transition range are weakened, and a smooth transition from the first estimation strategy to the third estimation strategy is achieved. This effectively suppresses estimation jitter and sudden changes in results, improves the continuity of rotor position and speed estimation in the transition range, reduces torque pulsation of the motor during the interval switching process, and improves the smoothness of the motor's transitional operation.

[0106] In some embodiments, such as Figure 5 As shown, when the operating range is the third operating range, the method also includes: S1231. Based on voltage and current signals, determine the adaptive parameters for sliding mode observation of the motor.

[0107] Among them, the sliding mode observation adaptive parameters are used to realize the sliding mode observer control rules and the motor parameter adaptive compensation rules. That is, a set of variable parameters used to configure the sliding mode observer control law and adaptively correct the motor parameter deviation, which can be updated in real time with the motor electrical state; the sliding mode observer control rules refer to the control law and sliding surface function related parameters used in the sliding mode observer to drive the observation error to zero, such as sliding mode gain, approach law coefficient, etc.; the motor parameter adaptive compensation rules refer to the calculation rules for online correction of motor stator resistance, stator inductance and other parameters according to the observation error, which are used to offset the observation deviation caused by parameter changes.

[0108] Specifically, the collected and preprocessed voltage and current signals are input into the parameter calculation unit. Based on the observation error and the motor mathematical model, the adjustable parameters related to sliding mode observation are calculated in real time through an adaptive law. This set of parameters is used to construct the sliding mode control law and to track and compensate the motor's main parameters. Finally, adaptive parameters for sliding mode observation adapted to the current operating conditions are obtained. For example, when the detected current error is too large, the adaptive learning rate is appropriately increased to accelerate parameter tracking; when the motor operating temperature rises, the stator resistance compensation is increased synchronously to ensure that the observer always maintains suitable operating parameters.

[0109] In this embodiment, the sliding mode observation adaptive parameters are determined based on the real-time voltage and current signals of the motor. This allows the relevant parameters of the observer to be dynamically adjusted according to the motor's operating state, rather than using fixed parameters. This helps to reduce the impact of motor parameter drift and changes in operating conditions on the observation results, improves the adaptability and anti-interference capability of the sliding mode observer in the medium- and high-speed range, and provides support for the subsequent reliable acquisition of back EMF signals.

[0110] S1232. Based on the sliding mode observation adaptive parameters, perform parameter compensation on the sliding mode observer and collect the back electromotive force observation signal output by the parameter-compensated sliding mode observer.

[0111] Parameter compensation refers to the process of substituting the adaptively calculated compensation amount into the sliding mode observer model to correct the observer's internal parameters, making them more closely match the motor's current actual state. The back EMF observation signal refers to the observation value output by the sliding mode observer, reflecting the motor rotor flux linkage and speed information, and is the direct basis for calculating the rotor's electrical angle position. The sliding mode observer is a state observer built based on sliding mode variable structure theory, used to reconstruct the unmeasurable back EMF signal inside the motor from voltage and current.

[0112] Specifically, the sliding mode observation adaptive parameters obtained from S1231 are written into the sliding mode observer's computing unit to complete the online update and compensation of the sliding mode control law and motor model parameters; real-time voltage and current signals are input into the compensated sliding mode observer for state observation; the observer converges to obtain the estimated component of the back electromotive force according to the variable structure control rule; the back electromotive force observation signal is collected and output as the input for subsequent position calculation.

[0113] In this embodiment, online parameter compensation for the sliding mode observer is performed using adaptive parameters, which can reduce the adverse effects of factors such as motor parameter perturbation and inverter nonlinearity on the observation process. This makes the back EMF observation signal closer to the actual operating state of the motor, which is beneficial to improving the stability and reliability of back EMF observation in the medium and high speed range and providing a high-quality signal for subsequent rotor position calculation.

[0114] S1233. Solve the back electromotive force observation signal to obtain the electrical angle position of the motor rotor.

[0115] Specifically, the process involves acquiring the filtered orthogonal back EMF observation signal; converting the two orthogonal signals into rotor electrical angle information using a preset position calculation algorithm; normalizing the angle and correcting the phase of the calculation result to match the actual rotor position of the motor; and finally outputting a continuous electrical angle position signal.

[0116] In this embodiment, the rotor electrical angle position is calculated based on a stable back EMF observation signal. This fully utilizes the characteristics of sufficient back EMF amplitude and high signal-to-noise ratio in the medium-to-high speed range, and obtains reliable rotor position information without injecting high-frequency signals. This helps reduce additional system losses and electromagnetic noise, while also improving the continuity of electrical angle position acquisition.

[0117] S1234. Determine the estimation result based on the electrical angle position.

[0118] Specifically, the electrical angle position obtained from S1233 is used as the core, and its format is sorted, amplitude is limited, and outliers are removed; the rotor speed can be obtained by differential or differential calculation of the electrical angle as needed; the position information is combined with the optional speed information to form a complete estimation result and output to the motor control module.

[0119] In this embodiment, the calculated electrical angle position is used as the core to form the final estimation result, which can provide a reliable position reference for motor vector control, enabling the motor to achieve stable sensorless operation in the medium and high speed range; at the same time, since no high-frequency injection is required, it is beneficial to reduce losses, improve operating efficiency, and improve the overall control effect of the motor in the third operating range.

[0120] In the above scheme, steps S1231 to S1234 are for the medium- and high-speed operating conditions in the third operating range. Based on voltage and current signals, the adaptive parameters of sliding mode observation are determined to realize the adaptive compensation between the sliding mode observer control rules and motor parameters. This reduces the impact of motor parameter drift and operating condition changes on the observation effect. Then, a stable back EMF observation signal is obtained through the compensated sliding mode observer. The reliable rotor electrical angle position is obtained by calculation and the estimation result is determined. There is no need to inject high-frequency signals, which reduces the additional losses and electromagnetic noise of the system. This improves the reliability of back EMF observation and the stability of position estimation in the medium- and high-speed range, and ensures the efficient and stable operation of the motor at medium and high speeds.

[0121] In some embodiments, such as Figure 6 As shown, when controlling the motor operation based on the estimation results, it includes: S131. Based on the estimation results, determine the current error signal.

[0122] Among them, the current error signal refers to the difference signal obtained after processing the current setpoint and the actual current sample value, which is used to reflect the degree of deviation between the actual motor current and the target current.

[0123] Specifically, the rotor electrical angle position in the estimated result is read and used for Park transformation (also known as rotational transformation, which transforms a two-phase stationary coordinate system to a two-phase rotating coordinate system); the actual sampled three-phase current is transformed by Clark transformation (also known as 3 / 2 transformation, which transforms a three-phase stationary coordinate system to a two-phase stationary coordinate system) and Park transformation to obtain the direct-axis current and quadrature-axis current; the direct-axis and quadrature-axis currents are subtracted from the corresponding current setpoints to obtain the direct-axis current error and quadrature-axis current error, which are then combined to form the current error signal.

[0124] In this embodiment, a current error signal is constructed based on the estimation results obtained from the aforementioned different operating ranges. This effectively integrates the rotor electrical angle position and speed information into the current loop control logic, making the comparison process between the current setpoint and the actual feedback more closely match the actual position of the motor rotor. This helps to improve the following performance of the current control, reduce control deviations caused by position deviations, and provide a foundation for the subsequent stable generation of drive signals.

[0125] S132. Generate motor drive control signal based on current error signal.

[0126] Specifically, the direct-axis and quadrature-axis current error signals are input to the corresponding regulators, and the direct-axis voltage command and quadrature-axis voltage command are obtained through adjustment calculations. Based on the electrical angle position in the estimation results, the voltage command is subjected to inverse Park transformation (transforming the voltage command in the rotating coordinate system back to the stationary coordinate system) to obtain the voltage command in the stationary coordinate system. This set of voltage commands is the control signal used to drive the motor.

[0127] In this embodiment, a motor drive control signal is generated based on the current error signal. This signal can be used to enable the actual current to quickly track the current setpoint through closed-loop regulation, thereby achieving effective control of the motor torque and magnetic flux. At the same time, relying on the aforementioned relatively stable estimation results, the control signal fluctuation is reduced, which helps to improve the dynamic response performance of the motor and reduce torque pulsation.

[0128] S133. Control the motor operation based on the motor drive control signal.

[0129] Specifically, the motor drive control signal is input to the pulse width modulation module to generate a multi-channel switching signal with a corresponding duty cycle; the switching signal is output to the power transistor drive terminal of the inverter to control the on / off timing of each phase bridge arm; the inverter outputs a three-phase alternating voltage to the motor stator winding according to the switching signal, thereby driving the motor to run according to the control target.

[0130] In this embodiment, the final control of the motor is achieved based on the drive control signal generated by the closed loop. This can truly transform the rotor position estimation result optimized in the full speed domain into a stable and reliable motor operating state, maintaining good operating performance in different speed ranges. At the same time, no position sensor is required, which helps to improve system reliability, reduce costs, and improve overall operating smoothness.

[0131] In the above scheme, steps S131 to S133 effectively integrate the rotor position and speed estimation results optimized in the full speed domain into the motor control loop. The estimation results are used to realize the coordinate transformation of the current and the determination of the current error signal. Then, based on the current error signal, the motor drive control signal is generated by the regulator through calculation and inverse coordinate transformation. Finally, the motor is driven by the pulse width modulation and the inverter. The reliable estimation results are transformed into a smooth motor control effect, which improves the tracking of the current control, reduces torque pulsation and speed fluctuation, and realizes stable operation of the motor in the full speed domain without position sensors. It takes into account the control effect, operating efficiency and system reliability, while reducing hardware costs.

[0132] In addition, such as Figure 7 As shown, Figure 7 This is a schematic diagram of the structure of a motor control device 700 provided in an embodiment of this application. The motor control device 700 includes: The first determining module 701 is used to determine the estimation strategy of the motor based on the voltage signal and current signal of the motor. The estimation strategy is used to match and execute the position and speed estimation rules of the motor rotor according to the real-time operating state of the motor represented by the voltage signal and current signal. The second determining module 702 is used to determine the estimation result of the motor rotor based on the estimation strategy, voltage signal and current signal. The estimation result includes the electrical angle position of the motor rotor. Control module 703 is used to control the operation of the motor based on the estimation results.

[0133] In the above scheme, the first estimated speed is determined based on the existing voltage and current signals of the motor system. This allows for a rapid preliminary assessment of the rotor speed without the need for additional hardware sensors, providing a real-time, low-cost basis for subsequent operating range division. Based on the first estimated speed, the motor's full-speed-range operating states are scientifically divided according to the strength of the back electromotive force and the applicability of the estimation method. This ensures that the range division conforms to the inherent physical characteristics of the motor rather than being arbitrarily set, laying the foundation for matching the estimation strategy. According to the divided operating ranges, the optimal estimation rule is dynamically matched and executed from a set of multiple differentiated rotor position estimation rules, fundamentally avoiding the inherent limitation of a single estimation method being unable to simultaneously adapt to all operating conditions with vastly different back electromotive forces. Then, the rotor position estimation result is determined based on the matched optimal estimation strategy, ensuring that the most suitable method is used for position estimation under each operating condition, effectively improving the accuracy of rotor position estimation under different operating conditions. Finally, the motor operation is controlled based on the accurate position estimation result, thereby improving the overall stability and control reliability of the motor.

[0134] In one specific embodiment, the first determining module 701 is further configured to: The initial speed of the motor rotor is determined based on voltage and current signals; In response to the absolute value of the initial speed being less than the first speed threshold, the motor is determined to be in the first operating range. The first speed threshold corresponds to the lowest speed at which the motor back EMF is observed. The first operating range is the operating range where the motor back EMF is relatively weak. In response to the absolute value of the initial speed being greater than the second speed threshold, the motor is determined to be in the third operating range, which is the operating range where the motor has a strong back electromotive force. In response to the absolute value of the initial speed being greater than or equal to the first speed threshold and less than or equal to the second speed threshold, the motor is determined to be in the second operating range. The second operating range is the speed transition range between the first operating range and the third operating range. The second speed threshold corresponds to the upper limit speed at which additional losses are generated. The second speed threshold is greater than the first speed threshold. The estimation strategy is determined based on the first operating range, the second operating range, and the third operating range.

[0135] In one specific embodiment, the first determining module 701 is further configured to: In response to the operating range being the first operating range, the estimation strategy is determined to be the first estimation strategy, which is an estimation strategy based on voltage signal injection and relying on the motor salient pole effect to estimate the rotor position and speed. In response to the operating range being the third operating range, the estimation strategy is determined to be the third estimation strategy, which is the estimation strategy of estimating rotor position and velocity by observing back electromotive force through adaptive sliding mode. In response to the operating range being the second operating range, the estimation strategy is determined to be the second estimation strategy, which is an estimation strategy based on a weighted fusion of the output results of the first estimation strategy and the output results of the third estimation strategy.

[0136] In one specific embodiment, when the operating range is the first operating range, the second determining module 702 is further configured to: Obtain the current speed command of the motor. The current speed command is used to represent the speed control command issued by the upper controller to the motor controller. Based on the current speed command, voltage signal, and current signal, determine the motor's operating condition; Based on the operating conditions, the injection parameters of the motor are determined. The injection parameters are used to indicate the characteristic parameters of the voltage signal injected into the motor. The estimation result is determined based on the injection parameters.

[0137] In one specific embodiment, the operating conditions include a light-load, low-speed operating condition and a heavy-load, high-speed operating condition. Based on the operating conditions, the second determining module 702 is further configured to: In response to the motor being under light load and low speed conditions, the injection parameter is determined to be the first injection parameter; In response to the motor being under heavy load and high speed, the injection parameter is determined to be the second injection parameter, and the amplitude and frequency corresponding to the second injection parameter are greater than the amplitude and frequency corresponding to the first injection parameter.

[0138] In one specific embodiment, the second determining module 702 is further configured to: Based on the injection parameters, a corresponding voltage signal is injected into the motor, and the current response signal of the motor after the voltage signal is injected is collected; The electrical angle position of the motor rotor is obtained by solving the current response signal; The estimation result is determined based on the electrical angle position.

[0139] In one specific embodiment, when the operating range is the second operating range, the second determining module 702 is further configured to: Obtain the estimation results output by the first estimation strategy and the third estimation strategy of the motor, as well as the initial estimated speed; Based on the initial estimated speed, the weighted fusion parameters of the motor are determined. The weighted fusion parameters are used to indicate the fusion weight ratio rule of the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy. Based on the weighted fusion parameters, the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy are fused to obtain the fused estimation value of the position and speed of the motor rotor. The estimation result is determined based on the fused estimate.

[0140] In one specific embodiment, when the operating range is the third operating range, the second determining module 702 is further configured to: Based on voltage and current signals, the sliding mode observation adaptive parameters of the motor are determined. These parameters are used to implement the sliding mode observer control rules and the motor parameter adaptive compensation rules. Based on the sliding mode observation adaptive parameters, the sliding mode observer is parameter compensated, and the back electromotive force observation signal output by the parameter compensated sliding mode observer is collected. The electrical angle position of the motor rotor is obtained by solving the back electromotive force observation signal; The estimation result is determined based on the electrical angle position.

[0141] In one specific embodiment, the control module 703 is further configured to: Based on the estimation results, the current error signal is determined; Based on the current error signal, generate the motor drive control signal; The motor is controlled based on the motor drive control signal.

[0142] Regarding the apparatus in the above embodiments, the specific manner in which each unit performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0143] This embodiment also provides a vehicle, including: the vehicle executes a motor control method as described above, thereby achieving the same effect as the above implementation method.

[0144] The beneficial effects of the above embodiments can be referred to the beneficial effects of the corresponding methods provided above, and will not be repeated here.

[0145] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0146] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0147] In the description of this application, it should be understood that if the terms "upper", "lower", "front", "rear", "left" and "right" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the position or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0148] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0149] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for controlling an electric motor, characterized in that, The method includes: Based on the voltage and current signals of the motor, an estimation strategy for the motor is determined. The estimation strategy involves using two methods, voltage signal injection estimation and adaptive sliding mode observation estimation, to perform parallel and independent calculations in different speed ranges of the motor rotor. Based on the estimation strategy, the voltage signal, and the current signal, the estimation result of the motor rotor is determined, and the estimation result includes the electrical angle position of the motor rotor; Based on the estimation results, the motor is controlled to operate.

2. The control method according to claim 1, characterized in that, The estimation strategy for determining the motor based on the motor's voltage and current signals includes: Based on the voltage and current signals, the initial speed of the motor rotor is determined; In response to the fact that the absolute value of the initial speed is less than the first speed threshold, the motor is determined to be in a first operating range. The first speed threshold corresponds to the lowest speed at which the motor back electromotive force is observed. The first operating range is the operating range in which the motor back electromotive force is relatively weak. In response to the absolute value of the initial speed being greater than the second speed threshold, the motor is determined to be in a third operating range, which is the operating range where the motor has a strong back electromotive force; In response to the absolute value of the initial speed being greater than or equal to the first speed threshold and less than or equal to the second speed threshold, it is determined that the motor is in a second operating range. The second operating range is a speed transition range between the first operating range and the third operating range. The second speed threshold corresponds to the upper limit speed at which additional losses are generated. The second speed threshold is greater than the first speed threshold. The estimation strategy is determined based on the first operating range, the second operating range, and the third operating range.

3. The control method according to claim 2, characterized in that, The step of determining the estimation strategy based on the first operating interval, the second operating interval, and the third operating interval includes: In response to the operating range being the first operating range, the estimation strategy is determined to be the first estimation strategy, which is an estimation strategy based on voltage signal injection and relying on the motor salient pole effect to estimate the rotor position and speed. In response to the operating range being the third operating range, the estimation strategy is determined to be the third estimation strategy, which is an estimation strategy for rotor position and velocity estimation by adaptive sliding mode observation of back electromotive force. In response to the operating range being the second operating range, the estimation strategy is determined to be the second estimation strategy, which is an estimation strategy based on a weighted fusion of the output results of the first estimation strategy and the output results of the third estimation strategy.

4. The control method according to claim 2, characterized in that, When the operating range is the first operating range, the method further includes: Obtain the current speed command of the motor, which represents the speed control command issued by the upper-level controller to the motor controller; Based on the current speed command, the voltage signal, and the current signal, the operating condition of the motor is determined; Based on the operating conditions, the injection parameters of the motor are determined, and the injection parameters are used to indicate characteristic parameters of the voltage signal injected into the motor; The estimation result is determined based on the injection parameters.

5. The control method according to claim 4, characterized in that, The operating conditions include light-load low-speed conditions and heavy-load high-speed conditions. Determining the injection parameters of the motor based on these operating conditions includes: In response to the motor being in the light-load, low-speed operating condition, the injection parameter is determined to be the first injection parameter; In response to the motor being in the heavy-load rapid operating condition, the injection parameter is determined to be a second injection parameter, wherein the amplitude and frequency corresponding to the second injection parameter are greater than the amplitude and frequency corresponding to the first injection parameter.

6. The control method according to claim 4, characterized in that, Determining the estimation result based on the injection parameters includes: Based on the injection parameters, a corresponding voltage signal is injected into the motor, and the current response signal of the motor after the voltage signal is injected is collected; The electrical angle position of the motor rotor is obtained by solving the current response signal. The estimation result is determined based on the electrical angle position.

7. The control method according to claim 2, characterized in that, When the operating range is the second operating range, the method further includes: Obtain the estimation results output by the first estimation strategy and the third estimation strategy of the motor, as well as the initial estimated speed; Based on the initial estimated speed, the weighted fusion parameters of the motor are determined. The weighted fusion parameters are used to indicate the fusion weight ratio rule of the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy. Based on the weighted fusion parameters, the estimation results output by the first estimation strategy and the estimation results output by the third estimation strategy are fused to obtain the fused estimation value of the position and speed of the motor rotor. The fusion estimate is determined as the estimation result.

8. The control method according to claim 1, characterized in that, When the operating range is the third operating range, the method further includes: Based on the voltage signal and the current signal, the sliding mode observation adaptive parameters of the motor are determined. The sliding mode observation adaptive parameters are used to realize the sliding mode observer control rules and the motor parameter adaptive compensation rules. Based on the sliding mode observation adaptive parameters, the sliding mode observer is parameter compensated, and the back electromotive force observation signal output by the parameter compensated sliding mode observer is collected. The electrical angle position of the motor rotor is obtained by solving the back electromotive force observation signal; The estimation result is determined based on the electrical angle position.

9. The control method according to claim 1, characterized in that, The step of controlling the motor operation based on the estimation result includes: Based on the estimation results, the current error signal is determined; Based on the current error signal, a motor drive control signal is generated; The motor is controlled to run based on the motor drive control signal.

10. A vehicle, characterized in that, include: The vehicle performs the motor control method as described in any one of claims 1 to 9.

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