Method for determining position of motor, phase-locked loop and motor control system

Abstract

The invention relates to a method for determining the position of a motor, a phase-locked loop and a motor control system. The method comprises the following steps: acquiring a first counter electromotive force and a second counter electromotive force corresponding to the motor; the method further comprises the step of determining a position error between the actual position and the observation position of the motor according to the first counter electromotive force and the second counter electromotive force based on a multi-order control module, and the order of the multi-order control module is larger than 3. Further, the method includes determining an observed position of the motor based on the position error. As the multi-order control module can track high-order dynamic changes such as acceleration and jerk, dynamic lag errors caused by acceleration / deceleration of the motor can be eliminated. According to the method for determining the position of the motor provided by the embodiment of the invention, accurate prediction of the position of the motor can be realized when the motor is in any working condition, so that the stability and the reliability of a motor control system are improved.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and more particularly, to a method, a phase-locked loop, and a motor control system for determining the position of a motor. Background Art

[0002] A permanent magnet synchronous motor (PMSM) is a synchronous motor that uses permanent magnets to generate a magnetic field, and the rotational speed of its rotor is consistent with the current frequency of the stator winding. Due to its advantages such as high efficiency and high power density, the permanent magnet synchronous motor is highly favored in industrial applications. A permanent magnet synchronous motor generally includes a rotor and a stator, and its working principle is based on the interaction between the rotating magnetic field generated by the stator and the magnetic field generated by the permanent magnets on the rotor.

[0003] Traditional methods for determining the position of a motor rotor mainly include implementing sensorless control of PMSM using a fundamental frequency model method. It estimates the back electromotive force or flux linkage information by introducing an observer, and then uses a phase-locked loop (PLL) to obtain the motor speed and rotor position information. However, traditional phase-locked loops cannot effectively track speed changes, resulting in a large dynamic tracking error.

[0004] In summary, the deficiencies of traditional methods for determining the position of a motor are as follows: the position error of the determined motor rotor is large, and the dynamic performance is poor. Summary of the Invention

[0005] Embodiments of the present invention propose a method, a phase-locked loop, and a motor control system for determining the position of a motor. This method uses a multi-order control module that can track acceleration and eliminate the dynamic lag error caused by motor acceleration / deceleration, thereby being able to determine a relatively accurate observed position of the motor.

[0006] In a first aspect of the present invention, a method for determining the position of a motor is provided. The method includes obtaining a first back electromotive force and a second back electromotive force corresponding to the motor. The method further includes determining, based on a multi-order control module, a position error between the actual position and the observed position of the motor according to the first back electromotive force and the second back electromotive force, where the order of the multi-order control module is greater than 3. In addition, the method further includes determining the observed position of the motor based on the position error.

[0007] In a second aspect of the present invention, a computing device is provided. The computing device includes one or more processors; and a storage device for storing one or more programs, which when executed by the one or more processors, cause the one or more processors to implement the method provided in the first aspect of the present invention.

[0008] In a third aspect of the present invention, a phase-locked loop for determining the position of a motor is provided. The phase-locked loop includes a phase detector, a multi-stage loop filter, and a voltage-controlled oscillator. The multi-stage loop filter includes a multi-stage control module. The phase detector is configured to determine the position error between the actual position and the observed position of the motor based on the first back electromotive force and the second back electromotive force of the motor. The multi-stage control module of the multi-stage loop filter is configured to dynamically compensate the position error to determine the compensated position error, and the order of the multi-stage control module is greater than 3. And the voltage-controlled oscillator is configured to output the observed position of the motor based on the compensated position error.

[0009] In a fourth aspect of the present invention, a computer-readable storage medium is provided. Computer-executable instructions are stored on the computer-readable storage medium, and the computer-executable instructions are executed by a processor to implement the method provided in the first aspect of the present invention.

[0010] According to a fifth aspect of the present invention, a computer program product is provided, including machine-executable instructions, which cause the machine to execute the method provided in the first aspect of the present invention when executed.

[0011] It should be understood that the content described in the summary of the invention is not intended to limit the key or important features of the embodiments of the present invention, nor to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In conjunction with the accompanying drawings and with reference to the following detailed description, the above and other features, advantages, and aspects of the embodiments of the present invention will become more apparent. In the drawings, the same or similar reference numerals denote the same or similar elements, where:

[0013] Figure 1 A schematic diagram showing an example environment in which multiple embodiments of the present invention can be implemented;

[0014] Figure 2 A flowchart showing a method for determining the position of a motor according to some embodiments of the present invention;

[0015] Figure 3 A schematic diagram showing the normalization of the back electromotive force provided according to some embodiments of the present invention;

[0016] Figure 4 A schematic diagram showing the error feedforward path of a phase-locked loop provided according to some embodiments of the present invention;

[0017] Figure 5 A schematic diagram showing the architecture of a phase-locked loop provided according to some embodiments of the present invention;

[0018] Figure 6Shows a schematic structural diagram of a phase-locked loop provided according to some embodiments of the present invention;

[0019] Figure 7 Shows a block diagram of a device for determining the position of a motor according to some embodiments of the present invention; and

[0020] Figure 8 Shows a block diagram of a device that can implement multiple embodiments of the present invention. Detailed implementation manners

[0021] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Instead, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0022] In the description of the embodiments of the present invention, the term "including" and its similar terms should be understood as open inclusion, that is, "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc. may refer to different or the same objects. There may also be other explicit and implicit definitions below.

[0023] As described above, in the process of determining the position of a motor by a traditional phase-locked loop, if the direction of the back electromotive force of the motor changes (such as the motor reverses), a non-convergence problem may occur, resulting in an increase in the position estimation error. In addition, during the acceleration and deceleration process of the motor, the proportional-integral (PI) controller of the traditional phase-locked loop cannot effectively track the speed change, resulting in a large dynamic tracking error. This will lead to poor dynamic performance of the phase-locked loop and limit the possibility of the entire system to obtain a higher bandwidth.

[0024] To this end, an embodiment of the present invention proposes a method for determining the position of a motor. In an embodiment of the present invention, the method includes obtaining a first back electromotive force and a second back electromotive force corresponding to the motor. The method further includes determining, based on a multi-order control module, a position error between the actual position and the observed position of the motor according to the first back electromotive force and the second back electromotive force, where the order of the multi-order control module is greater than 3. In addition, the method further includes determining the observed position of the motor based on the position error. Since the multi-order control module can track high-order dynamic changes such as acceleration and jerk, it can eliminate the dynamic lag error caused by motor acceleration / deceleration. That is to say, the method for determining the motor position provided by the embodiment of the present invention can accurately predict the motor position under any working condition of the motor, thereby improving the stability and reliability of the motor control system.

[0025] Figure 1 FIG. shows a schematic diagram of an example environment 100 in which multiple embodiments of the present invention can be implemented. As Figure 1 shown, in environment 100, it includes a motor 102 and a phase-locked loop 104 coupled to the motor 102. The motor 102 can be a synchronous motor (such as a permanent magnet synchronous motor, a stepper motor, a reluctance synchronous motor), or an asynchronous motor (such as an induction motor, an AC commutator motor, etc.). Taking the motor 102 as a permanent magnet synchronous motor as an example, the motor 102 mainly consists of components such as a stator, a rotor, and an end cover. When the stator winding is powered on, the motor starts and rotates according to the principle of an asynchronous motor, and accelerates to the synchronous speed. The synchronous electromagnetic torque generated by the rotor permanent magnet field and the stator magnetic field pulls the rotor into synchronization, and the motor enters synchronous operation. In some embodiments, the phase-locked loop 104 can be an automatic control system for phase synchronization, which can lock the phase of the input signal (Vi) and output a signal (Vo) synchronized with the phase of the input signal. In motor control, the phase-locked loop 104 can be used to obtain the position information of the rotor, thereby achieving precise control of the motor. It should be noted that the above system can be applied to various scenarios, such as the medical field, the aerospace field, the industrial automation field, etc., and the present invention is not limited thereto.

[0026] In some embodiments, the phase-locked loop 104 may include a phase detector (PD) 106 (such as a sine-wave phase detector), a loop filter (LF) 108, and a voltage-controlled oscillator (VCO) 110. Among them, the phase detector 106 can output a function of the phase difference of the signal by comparing the phases of the input signal and the output signal of the voltage-controlled oscillator. The input signal of the phase-locked loop 104 may be sourced from the sensors of the motor 102 (such as resolver encoders, linear hall encoders, etc.), or from the estimation results of the self-observer. In some embodiments, the input signal of the phase-locked loop 104 may be the back electromotive force of the motor 102. For example, it may be the quadrature back electromotive force of the motor 102, such as the quadrature α-axis back electromotive force, the quadrature β-axis back electromotive force, etc.

[0027] The loop filter 108 can be understood as a low-pass filter (such as a first-order low-pass filter, a second-order low-pass filter, etc.), which can filter out the high-frequency components and noise in the output voltage of the phase detector 106 and only retain the low-frequency components. The loop filter can output the control voltage of the voltage-controlled oscillator 110, thereby achieving the control of the output signal frequency of the voltage-controlled oscillator 110. In some embodiments, the phase detector 106 can compare the error between the phase of the input back electromotive force signal of the motor 102 and the estimated phase generated inside the phase-locked loop 104 (generated by the voltage-controlled oscillator 110). The output error signal (angle error) will be processed by the loop filter 108, and then the frequency of the voltage-controlled oscillator 110 will be adjusted so that the estimated position gradually converges to the actual position. It can be understood that the phase of the input back electromotive force is related to the actual position of the rotor, and the estimated phase generated inside the phase-locked loop 104 is related to the observed position of the rotor.

[0028] It can be understood that in actual applications, the phase-locked loop indirectly estimates the position of the motor rotor through the back electromotive force signal. When the motor accelerates, decelerates, or the load changes suddenly, the actual position of the rotor will change rapidly, resulting in a lag or lead between the observed position output by the phase-locked loop and the actual position. This lag or lead will introduce tracking errors, affecting the accuracy and stability of the motor controller. On this basis, in order to improve the accuracy of the determined motor rotor position and eliminate the tracking errors caused by acceleration, speed, etc., a multi-order control module of the phase-locked loop 104 ( Figure 1is not shown and is deployed in the loop filter 108) to dynamically compensate for errors. Among them, the multi-order control module can be a controller with multiple independent control parameters. For example, it can be a controller with 3, 4, or 5 independent control parameters. For example, the multi-order control module can be a third-order controller or other higher-order controllers (such as a fourth-order controller, a fifth-order controller, etc.). For example, when the multi-order control module is a third-order controller, the third-order controller can track the acceleration component of the frequency through a proportional-integral-double integral (PI2) structure to eliminate dynamic tracking errors.

[0029] As Figure 1 shown, the third-order controller can be part of the loop filter 108 to perform more complex filtering on the error signal output by the phase detector 106. Through the adjustment of the third-order controller, the phase-locked loop 104 can more accurately track the frequency and phase changes of the input signal, improving the stability and accuracy of the system. That is to say, the multi-order control module can achieve zero steady-state error under uniform speed, uniform acceleration, and variable acceleration working conditions by tracking the acceleration component.

[0030] In this example environment 100, the motor 102 also includes a controller (not shown in the figure), and the controller is deployed in the motor 102. The observed position output by the phase-locked loop 104 can be sent to the controller, and the controller controls the rotor of the motor 102 according to the observed position output by the phase-locked loop. For example, the controller can determine the target position that the rotor of the motor 102 should reach based on the received observed position and generate corresponding control signals. These control signals are sent to the drive circuit of the motor 102 to achieve precise control of the rotor of the motor 102.

[0031] In this way, since the multi-order control module can track high-order dynamic changes such as acceleration and jerk, it can eliminate the dynamic lag error caused by motor acceleration / deceleration, so that the phase-locked loop can accurately predict the motor position in any working condition of the motor, thereby improving the stability and reliability of the motor control system.

[0032] Figure 2 shows a flowchart of a method 200 for determining the motor position according to some embodiments of the present invention. The method 200 can be executed by Figure 1 the phase-locked loop 104 shown in Figure 2As shown, at block 202, method 200 may include obtaining a first back electromotive force and a second back electromotive force corresponding to the motor. Among them, the back electromotive force may be an electromotive force generated inside the motor during operation, and its magnitude and direction are related to the rotational speed and magnetic flux of the motor. For example, it may be the electromotive force generated by the relative movement of the rotor magnetic field and the stator winding of the motor. In some embodiments, the first back electromotive force and the second back electromotive force may be back electromotive forces of different phases at the same moment, or back electromotive forces of different phases at different moments. For example, in the orthogonal coordinate system, the first back electromotive force may be the α-axis back electromotive force, that is, the electromotive force component of the motor in the α-axis direction; the second back electromotive force may be the β-axis back electromotive force, that is, the electromotive force component of the motor in the β-axis direction.

[0033] In some embodiments, the back electromotive force can be obtained by directly measuring the voltage of the motor stator winding, or by observer estimation. Among them, the observer can be a control algorithm based on the mathematical model of the motor, which can estimate the internal state variables of the motor in real time. For example, by constructing a Luenberger observer or an extended Kalman filter, etc., the α-axis back electromotive force and β-axis back electromotive force of the motor can be estimated in real time. In other embodiments, the back electromotive force can also be estimated by using Model Reference Adaptive Control (MRAC). For example, the back electromotive force can be estimated by comparing the difference between the actual output of the motor and the output of the reference model.

[0034] At block 204, method 200 may include determining the position error between the actual position and the observed position of the motor based on a multi-order control module according to the first back electromotive force and the second back electromotive force, and the order of the multi-order control module is greater than 3. The multi-order control module can be a controller with multiple independent control parameters. For example, it can be a controller with multiple links. The independent control parameters can be gain coefficients corresponding to different links, and different control parameters correspond to different dynamic compensation targets. For example, the independent control parameters may include, but are not limited to, proportional gain parameters, integral time parameters, derivative time parameters, etc. In some embodiments, the multi-order control module may include, but is not limited to, a third-order controller, a fourth-order controller, etc. The third-order controller includes proportional, integral, and double integral links for tracking position, speed, and acceleration errors. The fourth-order controller can include proportional, integral, double integral, triple integral, etc. links for tracking position, speed, acceleration, and jerk (i.e., the rate of change of acceleration) errors. For example, the fourth-order controller can track the rate of change of acceleration for ultra-high speed or frequently variable acceleration scenarios to further reduce high-order dynamic errors.

[0035] In some embodiments, the phase-locked loop can determine the position error between the observed position and the actual position based on the input first back electromotive force and second back electromotive force. For example, the phase detector of the phase-locked loop can determine the actual position of the motor (such as the motor rotor) based on the input first back electromotive force and second back electromotive force, and the voltage-controlled oscillator of the phase-locked loop can output the observed position. It can be understood that the frequency of the voltage-controlled oscillator can be controlled by the loop filter of the phase-locked loop. On this basis, the phase detector can determine the position error between the observed position and the actual position of the motor. This error is used to drive the phase-locked loop to adjust the output, so that the predicted position of the output gradually approaches the actual position. In some embodiments, the multi-order control module can track the acceleration component of the frequency and eliminate the dynamic tracking error.

[0036] In block 206, method 200 may include determining the observed position of the motor based on the position error. Wherein, the observed position of the motor may be the position of the components included in the motor, for example, it may be the observed position corresponding to the rotor of the motor. When the position error determined based on the phase-locked loop is zero, the observed position of the motor is the same as the actual position of the motor. On this basis, the voltage-controlled oscillator of the phase-locked loop can output the corresponding observed position. For example, the multi-order control module can process the position error or angle error output by the phase detector to generate a control signal to drive the voltage-controlled oscillator to adjust the frequency and phase of the feedback signal, so that the position error is zero and position synchronization is achieved. That is to say, through the dynamic compensation of the multi-order control module, the observed position output by the voltage-controlled oscillator can approach the actual position of the motor.

[0037] In this way, since the multi-order control module can track high-order dynamic changes such as acceleration and jerk, it can eliminate the dynamic lag error caused by the acceleration / deceleration of the motor. Thus, the phase-locked loop can accurately predict the motor position under any working condition of the motor, thereby improving the stability and reliability of the motor control system.

[0038] In actual applications, the amplitude of the back electromotive force of the motor is proportional to the speed of the motor. And the loop gain of the phase-locked loop is usually directly related to the amplitude of the back electromotive force. When the speed of the motor changes, the loop gain of the phase-locked loop also changes. This will cause the bandwidth of the phase-locked loop to be inconsistent under different working conditions. On this basis, in order to improve the efficiency of parameter adjustment, the back electromotive force can be normalized to eliminate the influence of the amplitude on the loop gain. For example, by dividing the back electromotive force by its amplitude, the amplitude of the back electromotive force input to the phase-locked loop can be made constant, thereby stabilizing the loop gain and bandwidth. The normalized back electromotive force signal only retains the phase information and is independent of the speed.

[0039] Figure 3 Shows a schematic diagram of back electromotive force normalization provided according to some embodiments of the present invention. As Figure 3 shown, the back electromotive force can be and perform normalization processing to obtain orthogonal signals with unit amplitude: Among them, the back electromotive force after normalization satisfies That is, the amplitude is constantly 1. In this way, normalization can be used to suppress the influence of the back electromotive force amplitude fluctuation on the loop and reduce the amplification effect of high-frequency noise. That is to say, the normalization operation can decouple the loop gain of the phase-locked loop from the motor state.

[0040] In some embodiments, in order to improve the tracking ability and response speed of the phase-locked loop, error feedforward can be introduced into the phase-locked loop. Among them, error feedforward refers to directly superimposing the compensation amount on the control signal based on the real-time prediction of the dynamic characteristics (such as acceleration) of the input signal. That is to say, error feedforward can directly introduce this information into the control loop by predicting the disturbance or input change of the system in advance, so as to perform compensation before the disturbance occurs, rather than waiting until the error occurs and then adjusting through feedback. This can significantly improve the response speed and tracking accuracy of the system. For example, a feedforward channel can be added to the phase-locked loop to directly inject the dynamic characteristic parameters (such as acceleration and jerk) of the input signal into the control loop. In this way, the feedforward channel can convert the dynamic characteristic parameters into phase correction amounts and directly superimpose them on the output position (or VCO control voltage) of the phase-locked loop. In this way, the feedforward path can be regarded as open-loop compensation and work together with the feedback loop, equivalently expanding the closed-loop bandwidth of the system and improving the tracking ability for high-frequency dynamic signals.

[0041] Figure 4 shows a schematic diagram of the error feedforward path of the phase-locked loop provided by some embodiments of the present invention. As Figure 4 shown, the phase-locked loop can include a feedforward path 402. The output of the feedforward path 402 can be superimposed on the observed position calculated by the loop filter to obtain the final actual observed position The input of the feedforward path 402 can be the error ε between the observed position and the actual motor rotor position . For example, the feedforward path 402 can extract the dynamic component (such as acceleration) from the error signal output by the phase discriminator, and generate a feedforward compensation amount L after being processed by a low-pass filter (cutoff frequency ω and directly superimpose it on the observed position Among them, low-pass filtering can suppress high-frequency noise and retain the low-frequency dynamic characteristics (such as acceleration change rate) of the error. In this way, the use of the feedforward path can improve the tracking ability and response speed of the phase-locked loop, making the predicted position output by the phase-locked loop more accurate.

[0042] In some embodiments, the order of the multi-order control module can be greater than 3. The order of a controller is determined by the degree of the highest-order term in its transfer function. For example, a third-order controller includes a third-order integral or derivative term. A third-order controller can track acceleration (second derivative), and a fourth-order controller can track jerk (third derivative). That is to say, the multi-order control module can track the change in acceleration. In this way, when the acceleration changes, the double integral of the multi-order control module can compensate for the phase lag caused by the rate of change of frequency (acceleration) during motor acceleration / deceleration, thereby ensuring rapid convergence of the error. That is to say, the acceleration tracking ability of the multi-order controller can dynamically compensate for the rotor position error (phase / frequency error) in the back electromotive force and generate an error correction amount. In this way, the phase-locked loop can correct the predicted position through closed-loop feedback and output the actual predicted rotor position. It should be noted that the order of the control module can be extended according to requirements (such as fourth-order, fifth-order) to cope with more complex dynamic disturbances (such as load mutations, non-linear friction).

[0043] In some embodiments, in order to achieve precise control of the motor position error, multiple gain coefficients of the multi-order control module can be adjusted based on experimental debugging and the actual environment. For example, the gain coefficients of the multi-order control module can be adjusted according to the dynamic characteristics of the motor. Among them, the dynamic characteristics of the motor can be used to characterize the dynamic response and steady-state performance indicators of the motor. For example, it can include the relationship between rotational speed and electromagnetic torque, flux regulation characteristics, fluctuation characteristics, response time (or response speed), steady-state error, overshoot, etc.

[0044] It can be understood that factors such as the working environment where the motor is located, such as temperature, humidity, electromagnetic interference, etc., will also have different effects on the motor performance. Of course, the motor performance corresponding to the type of motor (such as permanent magnet synchronous motor, induction motor, etc.) or the operating scenario (such as high speed / low speed, start-stop parameters, load fluctuations, etc.) is also different. On this basis, the gain coefficients of the multi-order control module can also be adjusted in combination with the working environment, operating scenario or type of the motor.

[0045] In some embodiments, taking the multi-order control module as a third-order controller as an example, the process of determining the gain coefficients of the multi-order control module is described. Based on the motor mathematical model (such as the back electromotive force equation, mechanical motion equation), the transfer function of the third-order controller in the phase-locked loop can be derived. For example, it can be H(s)=K p +K i / s+K a / s 2 . Among them, K p is the proportional gain, K i is the integral gain, K ais the double integral gain. On this basis, the parameter values of the transfer function can be set based on the empirical values of the motor system (for example, K p can be set to 1, K i can be set to 10, and K a can be set to 0.1). In this way, when the motor is stationary or moving at a constant speed, the convergence process of the observed position error can be observed (the observation indicators can be that the overshoot is less than 10%, the adjustment time can be the time to reach the steady state, and the steady state error can approach zero). It can be understood that in order to ensure that the motor has a position observation with a dynamic tracking error of zero under the working conditions of uniform acceleration and uniform deceleration, the motor can be made to execute an acceleration-deceleration-forward and reverse rotation cycle, and the dynamic error between the observed position and the actual position can be recorded, so as to adjust the proportional gain, integral gain, or double integral gain, etc. For example, the convergence speed, overshoot, steady state error, and other indicators of the position error can be optimized by adjusting the gain coefficient. For example, the response speed can be increased by increasing Kp. Or the steady state error can be eliminated by adjusting Ki. Or the acceleration tracking ability can be optimized and the dynamic lag can be reduced by adjusting Ka.

[0046] In some embodiments, a parameter tuning method can be used to adjust multiple gain coefficients. The parameter tuning method can include but is not limited to the trial and error method, pole placement method, frequency domain analysis method, Ziegler-Nichols method, etc. Among them, the pole placement method can associate the controller parameters with the system pole positions, and ensure stability by setting the pole distribution (such as the left half plane). The frequency domain analysis method can adjust the parameters to meet the phase margin and gain margin requirements through the Bode plot or Nyquist plot. It should be noted that the adjustment between multiple gain coefficients can be independent of each other. For example, the proportional gain can be adjusted first and then the integral gain. Of course, multiple gain coefficients can also be adjusted simultaneously, and this application does not limit this here.

[0047] In this way, based on the dynamic characteristics and working environment of the motor, adjusting multiple gain coefficients of the third-order controller can make the position error of the motor approach zero under working conditions such as uniform speed, acceleration, forward and reverse rotation, etc. In this way, the precise control of the position error of the motor by the phase-locked loop is realized. On the one hand, it not only improves the stability and accuracy of the system, but on the other hand, it also provides a strong guarantee for the stable operation of the motor.

[0048] Figure 5 shows a schematic diagram of the architecture of a phase-locked loop provided according to some embodiments of the present invention. As Figure 5 shown, the phase-locked loop can include a third-order controller 502 and a feedforward path 504. It can be understood that the third-order controller 502 can also be a fourth-order controller, a fifth-order controller, etc. The feedforward path 504 can be a low-pass filter with a cut-off frequency of ω L . The input of the phase-locked loop can be the back electromotive force of the motor, such as the α-axis back electromotive force and the back electromotive force of the β-axis On this basis, the back electromotive force can be normalized by using the normalization method described in the above embodiments. On this basis, after the loop filter and voltage-controlled oscillator of the phase-locked loop are processed, the error ε between the observed position of the motor rotor and the actual position of the motor rotor can be expressed by the following formula (1):

[0049]

[0050] where θ e is the actual position of the motor rotor, is the observed position of the motor rotor. It can be seen that the improved position error expression remains unchanged in the case of small angles. It can be understood that the deviation e e between the actual rotational speed ω and the observed rotational speed ω can be:

[0051] As Figure 5 shown, in order to enable the phase-locked loop to work properly during the motor acceleration and deceleration phases, the PI controller structure can be further improved. For example, a multi-order controller such as a third-order controller 502 can be used to control the system. The error transfer function G(s) of the third-order controller 502 can be the following formula (2):

[0052]

[0053] On this basis, according to the final value theorem, the dynamic tracking errors of the phase-locked loop under uniform motion, uniform acceleration motion, and variable acceleration motion of the motor can be respectively expressed by the following formula (3), formula (4), and formula (5):

[0054]

[0055] It can be seen that the tracking errors corresponding to the phase-locked loop are stable when the motor is in uniform motion, uniform acceleration motion, or variable acceleration motion. That is to say, under any working conditions of the motor, due to the existence of the third-order controller, the phase-locked loop can achieve position observation with a dynamic tracking error of zero.

[0056] As Figure 5As shown, when the phase-locked loop includes the feedforward path 504, the final observed position is obtained by superimposing the output of the feedforward path 504 and the observed position of the voltage-controlled oscillator output. It can be understood that the feedforward amount of the feedforward path does not affect the stability of the closed-loop system. On this basis, the stability under the forward and reverse operating conditions of the motor can be judged according to the error of the normal loop of the phase-locked loop (excluding the feedforward path 504). After the third-order controller 502 is introduced into the phase-locked loop, the system order will increase accordingly. On this basis, when using the original speed and position descriptions, there will be second derivative terms. For the convenience of expression, the acceleration error can be introduced to describe the speed derivative.

[0057]

[0058] On this basis, the loop error equation of the third-order controller 502 can be determined as the following formula (7):

[0059]

[0060] Furthermore, the corresponding Jacobian matrix can be determined as the following formula (8):

[0061]

[0062] Wherein, m1, m2, and m3 in the Jacobian matrix can be abbreviations of polynomials containing relevant parameters, and the specific expressions can be the following formula (9):

[0063]

[0064] At this time Where a can be any value. At this time, all the characteristic roots of the Jacobian matrix are in the left half plane. If the angle, speed, and acceleration are used as a three-dimensional coordinate system, the phase trajectories in space all converge to these three stable lines. That is to say, when the motor is in the forward and reverse switching operating conditions, the sign of the back electromotive force will jump. However, the above phase trajectories indicate that the convergence state of the system has nothing to do with the back electromotive force. Therefore, no matter how the back electromotive force jumps, the phase-locked loop can always converge, that is, the phase-locked loop can work stably under the forward and reverse operating conditions of the motor. Through the dynamic adjustment of the multi-order controller and the compensation of error feedforward, the observed position output by the phase-locked loop can accurately track the actual rotor position. Even when the motor is in high speed, acceleration / deceleration, or forward and reverse operating conditions, the phase-locked loop can still maintain high-precision tracking.

[0065] Based on this, through the method for determining the motor position provided by the embodiments of the present application, it is possible to determine the relatively accurate position of the motor under various operating conditions such as uniform speed, uniform acceleration, and variable acceleration of the motor, and realize the output of the observed position with zero tracking error.

[0066] In some embodiments, the multi-order control module may include multiple integrator components. Different integrators undertake different compensation tasks and act together in the motor control system, thereby improving the stability and accuracy of the motor control system. For example, the multiple integrators may include a first integrator, a second integrator, and a third integrator. Among them, the first integrator can be used to compensate for phase errors. During the operation of the motor, due to the influence of various factors, there may be a phase deviation between the actual position and the desired position. The first integrator can gradually adjust the control signal through integral operation to reduce this phase error and ensure more accurate position control of the motor. In some embodiments, the second integrator can be used to compensate for frequency offset. The frequency offset may refer to the difference between the actual operating frequency of the motor and the desired frequency. This difference may be caused by factors such as load changes and power supply voltage fluctuations. The second integrator dynamically adjusts the control strategy through integral operation to eliminate this frequency offset and keep the motor running stably at the desired frequency. The third integrator can be used to compensate for the rate of change of frequency. The rate of change of frequency may refer to the rate at which the operating frequency of the motor changes over time. The third integrator can predict and compensate for the rate of change of frequency through integral operation, thereby improving the anti-interference ability and stability of the system.

[0067] Figure 6 FIG. shows a schematic structural diagram of a phase-locked loop according to some embodiments of the present invention. As Figure 6 shown, the phase-locked loop includes a phase detector 602, a multi-order loop filter 604, and a voltage-controlled oscillator 606. The phase detector 602 can determine the actual position of the motor rotor based on the input back electromotive force, such as the α-axis back electromotive force and the β-axis back electromotive force and compare the actual position with the observed position output by the voltage-controlled oscillator 606 to generate a position error. The multi-order controller in the multi-order loop filter 604 can track and compensate for dynamic errors through high-order terms such as proportional, integral, and double integral. On this basis, the multi-order loop filter 604 can output a control voltage to drive the voltage-controlled oscillator 606 to generate a frequency signal. By integrating the output frequency, the observed position of the motor rotor can be obtained. The observed position is fed back to the phase detector 602 to form a closed-loop control, continuously correcting the error until convergence.

[0068] Figure 7 FIG. shows a block diagram of a device 700 for determining the position of a motor according to some embodiments of the present invention. As Figure 7As shown, device 700 includes a back electromotive force acquisition unit 702 configured to acquire a first back electromotive force and a second back electromotive force corresponding to a motor. Device 700 further includes a position error determination unit 704 configured to determine a position error between an actual position and an observed position of the motor based on a multi-order control module according to the first back electromotive force and the second back electromotive force, and the order of the multi-order control module is greater than 3. Device 700 further includes an observed position determination unit 706 configured to determine the observed position of the motor based on the position error.

[0069] It can be understood that by using device 700 of the present invention, at least one of the many advantages that can be achieved by the method or process described above can be realized.

[0070] In some embodiments of the present invention, the position error determination unit 704 is configured to: determine a candidate position error between the actual position and the observed position of the motor based on the first back electromotive force and the second back electromotive force; and determine the position error between the actual position and the observed position by compensating the candidate position error based on the multi-order control module.

[0071] In some embodiments of the present invention, the observed position determination unit 706 is further configured to: determine a corresponding feedforward compensation amount and a candidate predicted position corresponding to the motor based on the position error; and determine the observed position of the motor based on the feedforward compensation amount and the candidate predicted position.

[0072] In some embodiments of the present invention, the multi-order control module includes a first integrator, a second integrator, and a third integrator. The first integrator is used to compensate for phase error, the second integrator is used to compensate for frequency offset, and the third integrator is used to compensate for the rate of change of frequency.

[0073] In some embodiments of the present invention, the observed position determination unit 706 is further configured to: determine the feedforward compensation amount based on the position error through a low-pass filter, and the cut-off frequency of the low-pass filter is determined based on the dynamic characteristics of the motor.

[0074] In some embodiments of the present invention, device 700 further includes a gain coefficient adjustment unit, which is further configured to: acquire the dynamic characteristics and the working environment of the motor; and adjust the gain coefficient of the first integrator and / or the gain coefficient of the second integrator and / or the gain coefficient of the third integrator based on the dynamic characteristics and the working environment.

[0075] In some embodiments of the present invention, the back electromotive force acquisition unit 702 is further configured to: acquire a first candidate back electromotive force and a second candidate back electromotive force corresponding to the motor; and determine the corresponding first back electromotive force by normalizing the first candidate back electromotive force, and determine the corresponding second back electromotive force by normalizing the second candidate back electromotive force.

[0076] Figure 8 Figure 800 shows a schematic block diagram of an example device that can be used to implement an embodiment of the present invention. As Figure 8 shown, device 800 includes a computing unit (i.e., CPU 801), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (i.e., ROM 802) or computer program instructions loaded from a storage unit 808 into a random access memory (i.e., RAM 803). In RAM 803, various programs and data required for the operation of device 800 can also be stored. CPU 801, ROM 802, and RAM 803 are connected to each other via a bus 804. An input / output interface (i.e., I / O interface 805) is also connected to bus 804.

[0077] A plurality of components in device 800 are connected to I / O interface 805, including: an input unit 806, such as a keyboard, a mouse, etc.; an output unit 807, such as various types of displays, speakers, etc.; a storage unit 808, such as a magnetic disk, an optical disc, etc.; and a communication unit 809, such as a network card, a modem, a wireless communication transceiver, etc. Communication unit 809 allows device 800 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0078] CPU 801 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of CPU 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 801 executes the various methods and processes described above, such as method 200. For example, in some embodiments, method 200 can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as storage unit 808. In some embodiments, part or all of the computer program can be loaded and / or installed onto device 800 via ROM 802 and / or communication unit 809. When the computer program is loaded into RAM 803 and executed by CPU 801, one or more steps of method 200 described above can be executed. Alternatively, in other embodiments, CPU 801 can be configured to execute method 200 in any other suitable manner (e.g., by means of firmware).

[0079] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. By way of example, and without limitation, the types of hardware logic components that can be used include: Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), Application Specific Standard Products (ASSPs), Systems on Chip (SOCs), Complex Programmable Logic Devices (CPLDs), and the like.

[0080] The program code for implementing the methods of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to the processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the program codes are executed by the processor or controller, the functions / operations specified in the flowchart and / or block diagram are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0081] In the context of the present invention, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a Read-Only Memory (ROM), an Erasable Programmable Read-Only Memory (EPROM or Flash memory), an optical fiber, a portable Compact Disc Read-Only Memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. Additionally, although the operations are depicted in a particular order, this should be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although a number of specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present invention. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single implementation. Conversely, the various features that are described in the context of a single implementation can also be implemented separately or in any suitable sub-combination in multiple implementations.

[0082] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. On the contrary, the specific features and acts described above are merely example forms of implementing the claims.

Claims

1. A method for determining the position of an electric machine, characterized in that, Applied to include: Obtain a first back electromotive force and a second back electromotive force corresponding to the motor; Based on a multi - order control module, determine a position error between an actual position and an observed position of the motor according to the first back electromotive force and the second back electromotive force, and the order of the multi - order control module is greater than 3; and Based on the position error, determine the observed position of the motor.

2. The method according to claim 1, characterized in that, Determining the position error between the actual position and the observed position of the motor according to the first back electromotive force and the second back electromotive force includes: Based on the first back electromotive force and the second back electromotive force, determine a candidate position error between the actual position and the observed position of the motor; and Based on the multi - order control module, determine the position error between the actual position and the observed position by compensating the candidate position error.

3. The method according to claim 1, wherein Determining the observed position of the motor based on the position error includes: Based on the position error, determine a corresponding feed - forward compensation amount and a candidate observed position corresponding to the motor; and Based on the feed - forward compensation amount and the candidate observed position, determine the observed position corresponding to the motor.

4. The method according to claim 3, characterized in that, Determining the corresponding feed - forward compensation amount based on the position error includes: Based on the position error, determine the feed - forward compensation amount through a low - pass filter, and the cut - off frequency of the low - pass filter is determined based on the dynamic characteristics of the motor.

5. The method according to claim 1, characterized in that, Wherein the multi - order control module includes a first integrator, a second integrator, and a third integrator. The first integrator is used to compensate for phase error, the second integrator is used to compensate for frequency offset, and the third integrator is used to compensate for the rate of change of frequency.

6. The method according to claim 5, wherein The method further includes: Obtain the dynamic characteristics and the working environment of the motor; and Based on the dynamic characteristics and the working environment, adjust the gain coefficient of the first integrator and / or the gain coefficient of the second integrator and / or the gain coefficient of the third integrator.

7. The method according to claim 1, wherein Obtaining the first back electromotive force and the second back electromotive force corresponding to the motor includes: Obtain a first candidate back electromotive force and a second candidate back electromotive force corresponding to the motor; and Determine the corresponding first back electromotive force by normalizing the first candidate back electromotive force, and determine the corresponding second back electromotive force by normalizing the second candidate back electromotive force.

8. A phase - locked loop for determining the position of a motor, the phase - locked loop includes a phase detector, a multi - order loop filter, and a voltage - controlled oscillator. The multi - order loop filter includes a multi - order control module, wherein: The phase detector is used to determine a position error between an actual position and an observed position of the motor based on a first back electromotive force and a second back electromotive force of the motor; The multi - order control module of the multi - order loop filter is used to dynamically compensate the position error to determine a compensated position error; and The voltage - controlled oscillator is used to output the observed position of the motor based on the compensated position error.

9. The method according to claim 8, wherein The phase - locked loop further includes a feed - forward error path, and the feed - forward error path is used to determine a corresponding feed - forward compensation amount based on the position error. The observed position of the motor is determined based on the feed - forward compensation amount and the compensated position error.

10. A motor control system, characterized in that, The motor control system includes a phase-locked loop according to claim 8 and a motor coupled to the phase-locked loop, wherein: The motor includes a stator, a rotor, and a controller. The stator and the rotor are respectively connected to the controller, and the controller is configured to control the rotor and / or the stator of the motor according to the observed position output by the phase-locked loop.

11. A computing device, characterized in that, Comprising: At least one processor; And A memory coupled to the at least one processor and having instructions stored thereon, the instructions, when executed by the at least one processor, cause the device to perform the method according to any one of claims 1-7.

12. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a machine, it performs the method according to any one of claims 1-7.

13. A computer program product, characterized in that, Comprising machine-executable instructions that, when executed, cause a machine to perform the method according to any one of claims 1-7.

Images