Motor drive control method and computer storage medium

Abstract

The present invention discloses a motor drive control method based on a synchronous frequency back-EMF observer. The method is based on a control system comprising a back-EMF observer, a high-order phase-locked loop (PLL), a speed loop, a current loop, an SVPWM module, and an inverter, with the back-EMF observer connected to the high-order PLL. A computer storage medium is also disclosed. The present invention effectively solves the problem of inaccurate back-EMF information calculation, enabling real-time and accurate calculation of the rotor position of a permanent magnet synchronous motor (PMSM), improving the steady-state and dynamic performance of the PMSM drive control technology. The present invention constructs a synchronous frequency back-EMF observer based on a mathematical model of the PMSM voltage and a triangular decomposition of the calculated back-EMF signal. By utilizing its bandpass characteristics, the observer effectively suppresses harmonics and DC disturbances in the back-EMF signal, significantly improving the accuracy of rotor flux calculation.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric transmission, and in particular relates to a motor drive control method based on a synchronous frequency back electromotive force observer, and a computer storage medium. Background Art

[0002] With the vigorous development and progress of motor control theory and power electronics integration technology, permanent magnet synchronous motors have been widely used in various industrial fields such as machine tools, electric vehicles and automated production due to their small size, simple structure, fast dynamic response, high efficiency and high power density.

[0003] Field-oriented control, the most widely used permanent magnet synchronous motor control strategy, generates a reference torque by feeding back speed information and decouples stator current using rotor position, achieving high-precision control of both speed and current. High-performance control of permanent magnet synchronous motors requires real-time, accurate rotor position information, which can typically be obtained directly through mechanical sensors such as tachometers and photoelectric encoders. However, the installation of traditional mechanical sensors increases the size and cost of the motor system. Furthermore, because mechanical sensors are susceptible to environmental damage, they increase the complexity of the motor system and reduce overall reliability. A real-time permanent magnet synchronous motor parameter calculation method can replace traditional mechanical sensors by calculating rotor position information from voltage and current signals, effectively addressing the challenges associated with mechanical sensors and having significant implications for the development of permanent magnet synchronous motor control technology.

[0004] Existing real-time permanent magnet synchronous motor parameter calculation methods can be categorized into two main types based on the motor's operating speed: the salient pole model method, used at low speeds, and the fundamental frequency model method, used at medium and high speeds. The salient pole model method, which can be further divided into high-frequency signal injection and PWM excitation methods, is based on the motor's saliency effect and is used to calculate rotor position information. The fundamental frequency model method requires obtaining the back EMF, which contains information about the rotor position angle. However, due to inverter nonlinearity, magnetic field space harmonics, and current measurement errors, the calculated back EMF contains harmonics and DC components, increasing the harmonic content of the calculated rotor position angle and severely affecting the accuracy of the rotor position angle calculation. Therefore, there is a need to improve the accuracy of back EMF observation to achieve high-performance motor control methods. Summary of the Invention

[0005] In view of the technical problem in the prior art that the calculation accuracy of the rotor position angle is affected by the back electromotive force error, one of the objectives of the present invention is to provide a motor drive control method based on a synchronous frequency back electromotive force observer.

[0006] In order to achieve the above object, the present invention solves the technical problem by adopting a technical solution: a motor drive control method, comprising the following steps:

[0007] S101, sampling the permanent magnet synchronous motor to obtain the motor three-phase current i A ,i B ,i C , and then obtain the α and β axis currents i respectively through coordinate transformation α ,i β and d,q axis current i d ,i q , establish the voltage mathematical model u of the permanent magnet synchronous motor in the α, β coordinate system αβ =(R s +ρL q )i αβ +e αβ , where u αβ is the voltage in the α, β coordinate system, i αβ is the current in the α, β coordinate system, R s is the stator resistance, L q is the stator q-axis inductance in the d, q coordinate system, ρ=d / dt is the differential operator, and the equivalent back electromotive force e in the α, β coordinate system is obtained. αβ =-[(L d -L q )ω e i d +ω e ψ f ](sinθ e -jcosθ e ), where L d is the stator d-axis inductance, i d is the d-axis current in the d,q coordinate system, ψ f is the permanent magnet flux, θ e is the rotor position angle, and the back electromotive force signal is calculated by triangular decomposition In the formula is the calculated back electromotive force in the α, β coordinate system, is the reference speed provided by the frequency-locked loop, a0 and b0 are weight coefficients, and

[0008]

[0009]

[0010] S102, constructing a synchronous frequency back-EMF observer, inputting the stator voltage and current signals of the permanent magnet synchronous motor into the synchronous frequency back-EMF observer, and utilizing the bandpass characteristic of the synchronous frequency back-EMF observer to eliminate harmonics and DC components in the calculated back-EMF signal to obtain an ideal back-EMF signal;

[0011] S103: Input the ideal back electromotive force signal output by the back electromotive force observer into a high-order phase-locked loop to calculate the motor rotor speed and rotor position angle, thereby realizing drive control of the permanent magnet synchronous motor.

[0012] Furthermore, the process of obtaining the ideal back EMF signal in step S102 is as follows: a frequency-locked loop is used to provide reference speed information for the synchronous frequency back EMF observer to avoid the influence of speed fluctuation errors, and the ideal back EMF signal is output by determining the bandpass characteristics by calculating the transfer function of the back EMF observer.

[0013] Furthermore, the frequency-locked loop provides a reference speed for the back-electromotive force observer, which is expressed as In the formula is the calculated current in the α, β coordinate system, k pa ,k ia is the frequency-locked loop coefficient, s is the Laplace operator, and based on the above formula, the back electromotive force signal can be designed to be expressed as:

[0014]

[0015]

[0016] Where x 1αβ ,x 2αβ is an intermediate variable, and The transfer function of the back EMF observer is expressed as

[0017]

[0018] Where k1 and k2 are the coefficients of the back-electromotive force observer.

[0019] The specific process of step S103 of the motor drive control method is as follows:

[0020] S301, the rotor position angle error calculated by the high-order phase-locked loop is expressed as In the formula is the rotor position angle calculated by the high-order phase-locked loop, The rotor position angle error calculated by the high-order phase-locked loop;

[0021] S302, the rotor position angle calculated by the high-order phase-locked loop is expressed as Where k p ,k i , k a is the coefficient of the high-order phase-locked loop;

[0022] S303, differentiating the calculated rotor position angle to obtain a motor rotor speed;

[0023] S304, set the given speed ω ref The motor rotor speed output by the high-order phase-locked loop The difference is input into the PI regulator of the speed loop to obtain the q-axis reference current And the set d-axis reference current Through the two PI regulators of the current loop, according to the d,q axis reference current With d,q axis sampling current i d ,i q The difference between the d and q axis reference voltages is obtained. Then the d, q axis reference voltage Perform coordinate transformation to obtain the α, β axis stator voltage u α ,u β ; Set the α,β axis stator voltage u α ,u β The SVPWM module is input to obtain an output signal, which is then input into the inverter to control on / off to achieve motor control.

[0024] A second object of the present invention is to provide a computer storage medium on which a motor drive control program is stored, and when the motor drive control program is executed by a processor, the steps of the above-mentioned motor drive control method are implemented.

[0025] Compared with the existing method, the advantages of the present invention are:

[0026] The back-electromotive force observer of the present invention utilizes the bandpass characteristic to eliminate the harmonics and DC components in the back-electromotive force signal, that is, it proposes the necessity of eliminating the slope and DC components in the back-electromotive force signal, and then proposes a corresponding feasible technical solution. Through the back-electromotive force observer based on the bandpass characteristic, the harmonics and DC disturbances in the calculated back-electromotive force are effectively suppressed, and the calculation accuracy of the back-electromotive force is significantly improved.

[0027] The present invention constructs a synchronous frequency back-EMF observer based on the mathematical model of the permanent magnet synchronous motor voltage and the triangular decomposition of the calculated back-EMF signal. The bandpass characteristic of the back-EMF observer is utilized to eliminate the harmonics and DC components in the calculated back-EMF, output an ideal back-EMF signal, and effectively solve the problem of inaccurate calculation of rotor position information.

[0028] Based on the above-mentioned technical means proposed, the present invention can effectively improve the calculation accuracy of back electromotive force information, provide higher position calculation accuracy during load disturbances and speed changes, and effectively improve the reliability of permanent magnet synchronous motor drive control. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a vector control block diagram of the permanent magnet synchronous motor drive control method of the present invention;

[0030] Figure 2 1 is a structural block diagram of a back electromotive force observer with a bandpass characteristic according to the present invention;

[0031] Figure 3 The frequency response characteristics of the back electromotive force observer at different center frequencies of the present invention;

[0032] Figure 4 This is a structural block diagram of the high-order phase-locked loop of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] Example 1

[0035] The present invention discloses a motor drive control method based on a synchronous frequency back electromotive force observer, which is based on a control system including a back electromotive force observer, a high-order phase-locked loop, a speed loop, a current loop, an SVPWM module, and an inverter; wherein the back electromotive force observer utilizes the input stator voltage and current signals of the permanent magnet synchronous motor and the bandpass characteristics to eliminate the harmonics and DC components in the calculated back electromotive force to obtain an ideal back electromotive force signal; wherein the synchronous frequency back electromotive force observer is constructed according to the triangular decomposition of the permanent magnet synchronous motor voltage mathematical model and the calculated back electromotive force signal; the back electromotive force observer is connected to the high-order phase-locked loop, and the back electromotive force observer is connected to the high-order phase-locked loop. The detector outputs an ideal back-EMF signal, which is fed into a high-order phase-locked loop (PLL) to calculate the motor rotor speed and position signals. The speed loop uses the difference between the given speed and the calculated motor rotor speed to generate the q-axis reference current, with the d-axis reference current set to 0. The current loop generates the d- and q-axis reference voltages based on the difference between the d- and q-axis reference currents and the d- and q-axis sampled currents. The d- and q-axis reference voltages undergo coordinate transformation to generate the α- and β-axis stator voltages. The SVPWM module uses the input α- and β-axis stator voltages to generate an output signal, which is fed into the inverter to control on / off switching, thereby achieving motor control. The specific steps are as follows.

[0036] S101, sampling the permanent magnet synchronous motor to obtain the motor three-phase current i A ,i B ,i C , and then obtain the α and β axis currents i respectively through coordinate transformation α ,i β and d, q axis current i d ,i q , establish the voltage mathematical model u of the built-in permanent magnet synchronous motor in the α, β coordinate system αβ =(R s +ρL q )i αβ +e αβ, where u αβ is the voltage in the α, β coordinate system, i αβ is the current in the α, β coordinate system, R s is the stator resistance, L q is the stator q-axis inductance in the d,q coordinate system, ρ=d / dt is the differential operator, and the equivalent back electromotive force e in the α,β coordinate system is obtained. αβ =-[(L d -L q )ω e i d +ω e ψ f ](sinθ e -jcosθ e ), where L d is the stator d-axis inductance, i d is the d-axis current in the d,q coordinate system, ψ f is the permanent magnet flux, θ e is the rotor position angle, and the back electromotive force signal is calculated by triangular decomposition In the formula is the calculated back electromotive force in the α, β coordinate system, is the reference speed calculated by the frequency-locked loop, a0 and b0 are weight coefficients, and

[0037]

[0038]

[0039] S102, constructing a synchronous frequency back-EMF observer, inputting the stator voltage and current signals of the permanent magnet synchronous motor into the synchronous frequency back-EMF observer, and utilizing the bandpass characteristics of the synchronous frequency back-EMF observer to eliminate harmonics and DC components in the calculated back-EMF signal to obtain an ideal back-EMF signal.

[0040] The process of obtaining the ideal back-EMF signal is as follows: the frequency-locked loop is used to provide reference speed information for the synchronous frequency back-EMF observer to avoid the influence of speed fluctuation error. By calculating the transfer function of the back-EMF observer, the band-pass characteristic is determined to output the ideal back-EMF signal. α ,i β and voltage u α ,u β Input the back EMF observer and use the bandpass characteristic to eliminate the harmonics and DC components in the calculated back EMF signal to obtain the ideal back EMF signal.

[0041] The frequency-locked loop provides the reference speed for the back-EMF observer, which is expressed as In the formula is the calculated current in the α, β coordinate system, k pa ,k ia is the frequency-locked loop coefficient, s is the Laplace operator, and based on the above formula, the back electromotive force signal can be designed to be expressed as:

[0042]

[0043]

[0044] Where x 1αβ ,x 2αβ is an intermediate variable, and The transfer function of the back EMF observer is expressed as

[0045]

[0046] Where k1 and k2 are the coefficients of the back-electromotive force observer.

[0047] S103: The ideal back-EMF signal output by the back-EMF observer is input into a high-order phase-locked loop to calculate the motor rotor speed and position signal, i.e., the rotor position angle, to achieve drive control of the permanent magnet synchronous motor. The process is as follows.

[0048] S301, the rotor position angle error calculated by the high-order phase-locked loop is expressed as In the formula is the rotor position angle calculated by the high-order phase-locked loop, The rotor position angle error calculated by the high-order phase-locked loop.

[0049] S302, the rotor position angle calculated by the high-order phase-locked loop is expressed as Where k p ,k i ,k a are the coefficients of the high-order phase-locked loop.

[0050] S303: Differentiate the calculated rotor position angle to obtain a motor rotor speed.

[0051] S304 adopts dual closed-loop control of speed loop and current loop, obtains rotor position information and calculates motor rotor speed through position-free detection algorithm The given speed ω ref The motor rotor speed output by the high-order phase-locked loop The difference is input into the PI regulator of the speed loop to obtain the q-axis reference current The d-axis reference current Generally it is given directly, and the d-axis reference current can be set Through the two PI regulators of the current loop, according to the d,q axis reference current With d,q axis sampling current id ,i q The difference between the d and q axis reference voltages is obtained. Then the d, q axis reference voltage Perform coordinate transformation to obtain the α, β axis stator voltage u α ,u β ; Set the α,β axis stator voltage u α ,u β The SVPWM module is input to obtain an output signal, which is then input into the inverter to control on / off to achieve motor control.

[0052] The motor rotor speed obtained is applied to the speed loop and current loop, and the calculated rotor position is applied to the Park and Inverse Park transformation modules.

[0053] The low-pass characteristics of the back-EMF observation scheme in the prior art cannot eliminate the DC component of the back-EMF. Compared with the prior art, the technical solution of the present invention proposes a synchronous frequency back-EMF observer with a bandpass characteristic that can eliminate the harmonics and DC components in the back-EMF signal; a frequency-locked loop is used to provide reference speed information for the back-EMF observer to avoid the influence of speed fluctuation errors.

[0054] The present invention applies a back-electromotive force observer with a bandpass characteristic to a permanent magnet synchronous motor drive system, that is, the voltage and current under the α and β coordinates are input into the back-electromotive force observer; the back-electromotive force observer with a bandpass characteristic is used to eliminate harmonics and DC components in the back-electromotive force signal, and output ideal back-electromotive force information; the motor rotor speed and position information are calculated through a high-order phase-locked loop; the calculated rotor speed is applied to the speed loop and the current loop, and the calculated rotor position is applied to the Park and anti-Park transformation modules, ultimately realizing the drive control of the permanent magnet synchronous motor.

[0055] Example 2

[0056] Based on the above technical ideas, the present invention will be further described below in conjunction with embodiments.

[0057] Figure 1 This is a vector control frame of the built-in permanent magnet synchronous motor drive control method based on back electromotive force observation provided by an embodiment of the present invention. The figure also includes a PI control module, a coordinate transformation module, an SVPWM module, an inverter, a built-in permanent magnet synchronous motor and a position observer.

[0058] Figure 2 The block diagram of the back electromotive force observer with passband characteristics provided by the embodiment of the present invention is shown in FIG. According to the motor model, the voltage generated by PI control is The current after sampling i αβBy constructing a back-electromotive force observer, the current error can be modulated by sine and cosine signals to successfully estimate the back-electromotive force, and the orthogonal relationship of the back-electromotive force can be used to generate an estimated motor frequency for use in the observer.

[0059] Figure 3 The frequency response characteristics of the back electromotive force observer at different center frequencies provided by the embodiment of the present invention are shown. As the center frequency increases, the phase delay of the observer is always zero and there is no attenuation in the amplitude, which shows that the proposed observer has good zero phase shift and zero amplitude characteristics. Figure 3 It can be seen that the back-electromotive force observer has a bandpass characteristic at different center frequencies and can effectively eliminate DC and harmonic components.

[0060] It should be noted that according to the above control ideas, the technical solution of the present invention can realize the accurate calculation of the back electromotive force signal and realize the motor rotor speed. and rotor position angle Dynamic acquisition of the permanent magnet synchronous motor can ultimately achieve drive control. Generally speaking, after obtaining the ideal back electromotive force signal, the rotor position angle and the motor rotor speed can be updated.

[0061] Figure 4 This diagram shows the structure of a high-order phase-locked loop (PLL) used in a drive control method for an internal permanent magnet synchronous motor, according to an embodiment of the present invention. Back-electromotive force (BEM) is used as the input signal, and a heterodyne method is used to obtain the rotor position estimation error. This error is passed through a PI regulator to obtain the estimated speed, and then through an integral step to obtain the rotor position. To mitigate the effects of changes in back-electromotive force and flux amplitude on position estimation during dynamic speed changes, a normalization process is employed to eliminate the impact of speed variations on the PLL bandwidth, thereby improving position and speed estimation performance.

[0062] In order to ensure accurate calculation of the rotor position, this embodiment establishes a high-order phase-locked loop to calculate the rotor position angle error, and its function expression is: in is the rotor position angle calculated by the high-order phase-locked loop, is the rotor position angle error calculated by the high-order phase-locked loop; the rotor position angle calculated by the high-order phase-locked loop is expressed as Where k p ,k i ,k a are the coefficients of the high-order phase-locked loop.

[0063] It should be understood that the above-mentioned technical means of calculating the rotor position angle using a high-order phase-locked loop is the preferred means of the technical solution of the present invention. In other feasible embodiments, the present invention is not limited to the execution of this technical process. Without departing from the technical principles of S101 to S103 of the present invention, not executing the above-mentioned technical process is also considered to fall within the scope of protection of the present invention.

[0064] In this embodiment, the calculated rotor position angle is differentiated to calculate the rotor speed.

[0065] Example 3

[0066] This embodiment provides a computer storage medium, on which a computer program is stored. A processor in a computer device invokes the computer program to implement:

[0067] Inputting the stator voltage and current signals of the permanent magnet synchronous motor into the synchronous frequency back electromotive force observer;

[0068] Utilizing the bandpass characteristics of the synchronous frequency back-EMF observer, harmonics and DC components in the calculated back-EMF are eliminated to obtain an ideal back-EMF signal, wherein the synchronous frequency back-EMF observer is constructed based on a mathematical model of the permanent magnet synchronous motor voltage and a triangular decomposition of the calculated back-EMF signal;

[0069] The ideal back electromotive force signal is input into a high-order phase-locked loop to calculate the motor rotor speed and position signal, thereby realizing the drive control of the permanent magnet synchronous motor.

[0070] For the specific implementation process of each step, please refer to the description of the above method.

[0071] The readable storage medium is a computer-readable storage medium, which may be an internal storage unit of the controller described in any of the aforementioned embodiments, such as a hard disk or memory of the controller. The readable storage medium may also be an external storage device of the controller, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the controller. Furthermore, the readable storage medium may also include both an internal storage unit of the controller and an external storage device. The readable storage medium is used to store the computer program and other programs and data required by the controller. The readable storage medium may also be used to temporarily store data that has been output or is to be output.

[0072] Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned readable storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0073] It should be understood that in the embodiments of the present invention, the processor referred to may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The memory may include a read-only memory and a random access memory, and provides instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0074] It should be emphasized that the examples described in the present invention are illustrative rather than restrictive. Therefore, the present invention is not limited to the examples described in the specific embodiments. Any other embodiments derived by those skilled in the art based on the technical solution of the present invention that do not depart from the purpose and scope of the present invention, whether modified or replaced, also fall within the scope of protection of the present invention.

Claims

1. A motor drive control method based on a control system including a back-EMF observer, a high-order phase-locked loop, a speed loop, a current loop, an SVPWM module, and an inverter, wherein the back-EMF observer is connected to the high-order phase-locked loop, and characterized in that: The following steps are included S101, samples the permanent magnet synchronous motor to obtain three-phase current i A , i B , i C , and then through coordinate transformation we can get α , β Shaft current i α , i β and d , q Shaft current i d , i q , establish permanent magnet synchronous motor in α , β Voltage mathematical model in coordinate system u αβ =( R s + ρL q ) i αβ + e αβ , where u αβ for α , β The voltage in the coordinate system, i αβ for α , β The current in the coordinate system, R s is the stator resistance, L q for d , q Stator in coordinate system q Shaft inductance, ρ = d / dt As differential operator, we get α , β Equivalent back electromotive force in the coordinate system , where L d For stator d Shaft inductance, i d for d , q In the coordinate system d Shaft current, ψ f is the permanent magnet flux, θ e is the rotor position angle, and the back electromotive force signal is calculated by triangular decomposition , where for α , β The back electromotive force in the coordinate system is, The reference speed provided by the frequency-locked loop, a 0 , b 0 is the weight coefficient, and , ; S102, constructing a synchronous frequency back-EMF observer, inputting the stator voltage and current signals of the permanent magnet synchronous motor into the synchronous frequency back-EMF observer, using the synchronous frequency back-EMF observer to eliminate harmonics and DC components in the back-EMF signal, using a frequency-locked loop to provide reference speed information for the synchronous frequency back-EMF observer, and outputting an ideal back-EMF signal by calculating the transfer function of the back-EMF observer; the reference speed provided by the frequency-locked loop to the back-EMF observer is expressed as , where For calculation α , β The current in the coordinate system, k pa , k ia is the frequency-locked loop coefficient, s is the Laplace operator, and the back electromotive force signal is calculated , , Where x 1αβ , x 2αβ is an intermediate variable, and , , then the transfer function of the back EMF observer is expressed as , where k 1 , k 2 is the coefficient of the back-EMF observer; S103, input the ideal back electromotive force signal into the high-order phase-locked loop to calculate the motor rotor speed and rotor position angle , to realize the drive control of permanent magnet synchronous motor.

2. A motor drive control method according to claim 1, characterized in that: The process of step S103 is as follows: S301, rotor position angle error calculated by high-order phase-locked loop ; S302, rotor position angle calculated by high-order phase-locked loop , where k p , k i , k a is the coefficient of the high-order phase-locked loop; S303, the rotor position angle Differentiate to get the motor rotor speed ; S304, set the given speed The motor rotor speed output by the high-order phase-locked loop The difference is input into the PI regulator of the speed loop to obtain q Axis reference current , and the set d-axis reference current ; Through the two PI regulators of the current loop, according to d , q Axis reference current and d , q Axis sampling current The difference is obtained d,q Axis reference voltage , and then d,q Axis reference voltage Perform coordinate transformation to obtain α , β Shaft stator voltage ;Will α , β Shaft stator voltage The SVPWM module is input to obtain an output signal, which is then input into the inverter to control on / off to achieve motor control.

3. A computer storage medium, characterized in that The computer storage medium stores a motor drive control program, which, when executed by a processor, implements the steps of the motor drive control method according to any one of claims 1 to 2.

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