Method and device for controlling permanent magnet synchronous motor without position sensor

Abstract

The embodiment of the invention provides a position sensorless permanent magnet synchronous motor control method and device, and the method comprises the steps: determining a first control voltage based on a reference current and a response current, injecting a high-frequency pulse square wave into the first control voltage, and obtaining a second control voltage, and carrying out space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage. Wherein an injection phase shift angle with positive and negative alternating characteristics is introduced into the high-frequency pulse square wave injected into the first control voltage, that is, the injection phase shift angle is subjected to positive and negative switching once at the starting moment of each period of the high-frequency pulse square wave, so that offset of third-time position harmonics can be realized, and the position estimation precision is improved; and the specific reason of the error does not need to be modeled. According to the embodiment of the invention, the scheme is simple, and no complex parameter setting process exists.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of motor control technology, and in particular to a position sensorless permanent magnet synchronous motor control method, a position sensorless permanent magnet synchronous motor control device, an electronic device, and a computer-readable storage medium. Background Art

[0002] Permanent Magnet Synchronous Motor (PMSM) is usually used in scenarios that require high power density, high torque density and high efficiency. Traditional field-oriented control (FOC) of permanent magnet synchronous motors requires accurate position and speed information from position sensors. In order to improve the cost-effectiveness, space utilization and robustness of motor drive systems, sensorless control of permanent magnet synchronous motors has been widely studied.

[0003] The Square Wave Voltage Injection (SWVI) method is widely used due to its simple implementation, good dynamic performance and robustness to nonlinearity. By increasing the injection frequency to the maximum, which is half of the pulse width modulation (PWM) switching frequency in the common single sample-single update mode, the bandwidth of the system can be further improved by eliminating the low-pass filter for current separation. However, when the injection frequency is increased to half of the PWM frequency, a third harmonic error will appear in the estimated position, thereby reducing the estimation accuracy. Traditional error compensation methods have a strong dependence on motor parameters and operating conditions, and therefore cannot be widely used. Summary of the invention

[0004] The embodiments of the present application provide a position sensorless permanent magnet synchronous motor control method, a position sensorless permanent magnet synchronous motor control device, an electronic device and a computer-readable storage medium, which aim to reduce the third harmonic in the estimated position and improve the accuracy of the position estimation.

[0005] In a first aspect, an embodiment of the present application provides a position sensorless permanent magnet synchronous motor control method, the method comprising: Obtaining reference current and response current of the permanent magnet synchronous motor; determining a first control voltage based on the reference current and the response current; Injecting a high-frequency pulse square wave into the first control voltage to obtain a second control voltage, wherein the high-frequency pulse square wave is determined based on an injection phase shift angle, and the injection phase shift angle is switched between positive and negative once at the start of each cycle of the high-frequency pulse square wave; The permanent magnet synchronous motor is subjected to space vector pulse width modulation based on the second control voltage.

[0006] In an embodiment of the present application, firstly, a first control voltage is determined based on a reference current and the response current, and then a high-frequency pulse square wave is injected into the first control voltage to obtain a second control voltage, and then space vector pulse width modulation is performed on the permanent magnet synchronous motor based on the second control voltage. Among them, the high-frequency pulse square wave injected into the first control voltage introduces an injection phase shift angle with positive and negative alternating characteristics, that is, the injection phase shift angle is switched between positive and negative once at the beginning of each cycle of the high-frequency pulse square wave, so that the third position harmonic can be reduced and the accuracy of position estimation can be improved without modeling the specific cause of the error. The scheme of the embodiment of the present application is simple, and there is no complicated parameter setting process.

[0007] In a possible implementation of the present application, the method further includes: Separating a first fundamental response current and a high-frequency response current from the response current; Acquire an estimated position, and determine an equivalent position error based on the high frequency response current and the estimated position; Perform a phase-locked loop based on the equivalent position error to obtain an updated estimated position; The step of determining a first control voltage based on the reference current and the response current comprises: determining a second fundamental response current based on the first fundamental response current and the updated estimated position; determining the first control voltage based on an error between the reference current and the second fundamental response current; The performing space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage includes: determining a third control voltage based on the second control voltage and the updated estimated position; The permanent magnet synchronous motor is subjected to space vector pulse width modulation based on the third control voltage.

[0008] In a possible implementation of the present application, determining the equivalent position error based on the high frequency response current and the estimated position includes: Multiplying the high-frequency response current by the sign of the high-frequency pulse square wave to obtain a demodulated high-frequency response current; determining an estimated position vector based on the estimated position and the injection phase shift angle; The demodulated high frequency response current is cross-multiplied with the estimated position vector to obtain the equivalent position error.

[0009] In a possible implementation of the present application, before performing a phase-locked loop based on the equivalent position error, the method further includes: The equivalent position error is normalized based on the high frequency response current.

[0010] In a possible implementation of the present application, the method further includes: separating a high frequency response current from the response current; Acquire an estimated position, and determine an equivalent position error based on the high frequency response current and the estimated position; Determine the injection phase shift angle based on the equivalent position error; The injection phase shift angle is adjusted based on the injection phase shift angle size.

[0011] In a possible implementation of the present application, determining the injection phase shift angle based on the equivalent position error includes: Based on two consecutive equivalent position errors, an average equivalent position error is determined; Based on the average equivalent position error, the estimated position, the injected phase shift angle and the true position, construct an average equivalent position error model, wherein the average equivalent position error model includes a position estimation component and a high-order harmonic component; Determine the injection phase shift angle when the high-order harmonic component is zero based on the average equivalent position error model; The injection phase shift angle is adjusted based on the injection phase shift angle size.

[0012] In a possible implementation of the present application, the injection phase shift angle when the high-order harmonic component is zero has a plurality of different candidate values; and adjusting the injection phase shift angle based on the injection phase shift angle includes: Constructing a total harmonic distortion model based on the higher-order harmonic components and the position error gain; Based on the total harmonic distortion model, determining the total harmonic distortion corresponding to each of the candidate values; The injection phase shift angle is adjusted based on the candidate value with the minimum total harmonic distortion.

[0013] In a second aspect, an embodiment of the present application provides a position sensorless permanent magnet synchronous motor control device, the device comprising: A current acquisition module, used to obtain a reference current and a response current of the permanent magnet synchronous motor; a voltage determination module, configured to determine a first control voltage based on the reference current and the response current; A square wave injection module, used for injecting a high-frequency pulse square wave into the first control voltage to obtain a second control voltage, wherein the high-frequency pulse square wave is determined based on an injection phase shift angle, and the injection phase shift angle is switched between positive and negative once at the start of each cycle of the high-frequency pulse square wave; A modulation module is used to perform space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage.

[0014] In a third aspect, an embodiment of the present application provides an electronic device, including: Memory, used to store programs; A processor is used to execute the program stored in the memory. When the processor executes the program stored in the memory, the processor is used to execute the method described in the first aspect above.

[0015] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to execute the position sensorless permanent magnet synchronous motor control as described in the first aspect above.

[0016] The solutions provided in the second to fourth aspects are used to implement or cooperate with the position sensorless permanent magnet synchronous motor control method provided in the first aspect, and can therefore achieve the same or corresponding beneficial effects as the first aspect, and will not be repeated here.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic flow chart of a method for controlling a position sensorless permanent magnet synchronous motor provided in an embodiment of the present application; Figure 2 A schematic diagram of the architecture of a position sensorless permanent magnet synchronous motor control method provided in an embodiment of the present application; Figure 3 A schematic diagram of the architecture of the position estimation part provided in an embodiment of the present application; Figure 4 A schematic diagram of a position sensorless permanent magnet synchronous motor control device provided in an embodiment of the present application; Figure 5 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical methods and advantages of this application more clear, the following is a further detailed description of this application in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain this application and are not used to limit this application.

[0020] It should be noted that the meaning of "multiple" (or multiple) involved in the description of the embodiments of the present application is more than two, "greater than", "less than", "exceed", etc. are understood as not including the number itself, and "above", "below", "within", etc. are understood as including the number itself. If there is a description of "first", "second", etc., it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0021] In the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the situation where A exists alone, A and B exist at the same time, and B exists alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, at least one of a, b and c can mean: a exists alone, b exists alone, c exists alone, a and b exist at the same time, a and c exist at the same time, b and c exist at the same time, or a, b and c exist at the same time, wherein a, b, c can be single or multiple.

[0022] The terms "substantially", "about" and similar terms used in the embodiments of the present application are used as approximate terms rather than as terms of degree, and are intended to take into account the inherent deviations of measurements or calculations known to those of ordinary skill in the art. In addition, the use of "may" when describing the embodiments of the present application refers to "possible one or more embodiments". The terms "use", "using", and "used" used in the embodiments of the present application may be considered to be synonymous with the terms "utilize", "utilizing", and "utilized", respectively. In addition, the term "exemplary" is intended to refer to an example or illustration.

[0023] Permanent Magnet Synchronous Motor (PMSM) is usually used in scenarios that require high power density, high torque density and high efficiency. Traditional field-oriented control (FOC) of permanent magnet synchronous motors requires accurate position and speed information from position sensors. In order to improve the cost-effectiveness, space utilization and robustness of motor drive systems, sensorless control of permanent magnet synchronous motors has been widely studied.

[0024] The Square Wave Voltage Injection (SWVI) method is widely used due to its simple implementation, good dynamic performance and robustness to nonlinearity. SWVI is a technology for sensorless control of motors. It injects a high-frequency pulse square wave signal into the motor stator and uses the change in the motor response to obtain the motor's rotor position or speed information. In high-frequency injection control, the injection frequency is usually increased to the maximum, that is, half of the pulse width modulation (PWM) switching frequency in the common single sampling-single update mode. The bandwidth of the system can be further increased by eliminating the low-pass filter for current separation. However, when the injection frequency is increased to half of the PWM frequency, a third harmonic error will appear in the estimated position, thereby reducing the estimation accuracy. Traditional error compensation methods have a great dependence on motor parameters and working conditions, so they cannot be widely used.

[0025] Existing methods for eliminating harmonics of position estimation errors include high-order filters, optimization operations, and artificial intelligence. High-order filters can effectively eliminate position estimation errors when the harmonic order is known in advance. However, since the harmonics are closer to the fundamental frequency, it is difficult to extract the third harmonic without affecting the filter bandwidth, especially at low speeds. Optimization operations and artificial intelligence take up a lot of computing resources, and the bandwidth is reduced due to the additional controller, and the parameter tuning process is complicated.

[0026] In view of the shortcomings of half-switching frequency square wave injection, the embodiment of the present application proposes a sensorless drive scheme for permanent magnet synchronous motor based on phase-shifted square wave injection (PS-SWVI). By introducing an alternating polarity phase shift angle in the injected voltage vector, the method can reduce the third position harmonic without modeling the specific cause of the error. The embodiment of the present application is easy to implement and does not require a complex parameter setting process.

[0027] The technical solutions of the embodiments of the present application are described in detail below through some embodiments. The following embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0028] See also Figure 1 , is a flow chart of a method for controlling a permanent magnet synchronous motor without a position sensor provided in an embodiment of the present application. The execution subject of the method for controlling a permanent magnet synchronous motor without a position sensor is a device having a permanent magnet synchronous motor control function, such as a permanent magnet synchronous motor control device. For ease of description, the present application embodiment is described by taking the execution subject as an electronic device as an example.

[0029] like Figure 1As shown, the position sensorless permanent magnet synchronous motor control method provided in the embodiment of the present application includes but is not limited to the following steps: Step S110: Obtain a reference current and a response current of the permanent magnet synchronous motor.

[0030] Exemplarily, the reference current represents a set current value, and the response current can be determined by sampling the three-phase current of the permanent magnet synchronous motor.

[0031] Step S120: determining a first control voltage based on the reference current and the response current.

[0032] Exemplarily, the reference current represents a desired current value, and the error between the reference current and the response current is calculated, and then the first control voltage is determined based on the error, so as to drive and control the permanent magnet synchronous motor based on the first control voltage.

[0033] Exemplarily, in a specific implementation, the reference current and the response current can be input into a PI controller, and the PI controller outputs a first control voltage through a linear combination of the proportion and integral of the control deviation formed by the reference current and the response current, thereby controlling the permanent magnet synchronous motor of the controlled object.

[0034] Step S130, injecting a high-frequency pulse square wave into the first control voltage to obtain a second control voltage, wherein the high-frequency pulse square wave is determined based on an injected phase shift angle, and the injected phase shift angle is switched between positive and negative once at the start of each cycle of the high-frequency pulse square wave.

[0035] It should be understood that the embodiment of the present application realizes the estimation of the rotor position by injecting a high-frequency square wave voltage signal into the stator winding of the motor, so as to realize the position sensorless control of the permanent magnet synchronous motor at zero speed or low speed. Different from the traditional pulsating square wave voltage injection (SWVI) technology, the embodiment of the present application proposes a phase-shifted square wave injection (PS-SWVI) technology. Specifically, a controllable injection phase shift angle is introduced into the high-frequency pulse square wave, and the injection phase shift angle has an alternating polarity, that is, a positive and negative switch is performed at the beginning of each cycle of the high-frequency pulse square wave.

[0036] Exemplarily, the high-frequency pulse square wave injected in the PS-SWVI technology proposed in the embodiment of the present application can be expressed as: (Formula 1) in, (Formula 2) Among them, V h Represents the high-frequency injected voltage amplitude; The angle for the introduced phase shift injection; Indicates the size of the introduced phase-shift injection angle; This is a floor operation.

[0037] According to the positive and negative values ​​of the injection angle, the corresponding high-frequency response current is analyzed and the following can be obtained: (Formula 3) The superscript “+” indicates the high-frequency response current when the injection angle is positive, and the superscript “-” indicates the high-frequency response current when the injection angle is negative. I p and I n is the positive and negative sequence of the high frequency response current ,and is the average high frequency inductance, It is the high frequency inductance difference.

[0038] Among them, when the phase-shift injection angle is positive, the equivalent position error can be expressed as: = = sin(2 -2 )= cos(2 )sin(2 )+cos(2 )sin(2 )= + (Formula 4) in, Indicates estimated position; represents the position error, which is determined by the deviation between the actual position and the estimated position of the motor rotor; k represents the gain of the equivalent position deviation; and b represents the offset of the equivalent position deviation.

[0039] (Formula 5) Similar to the analysis when the phase-shift injection angle is positive, when the phase-shift injection angle is positive or negative, the gain and offset of the equivalent position error can be expressed as: (Formula 6) According to Formula 5 and Formula 6, when the injection voltage amplitude is the same, the response current amplitude is equal for positive and negative injection angles. Therefore, the gain of the equivalent position error is the same, and the offset has opposite signs at positive and negative injection angles. Therefore, when the injection angle switches its sign in each injection sequence, the DC offset caused by the phase shift of the square wave voltage vector injected by the high frequency can be offset.

[0040] Step S140: performing space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage.

[0041] It should be understood that space vector pulse width modulation (SVPWM) is performed based on the second control voltage to output a corresponding PWM signal to control the inverter to drive the permanent magnet synchronous motor with a synthesized voltage. Specifically, the second control voltage can be inverse park transformed, and the transformed voltage is input into the SVPWM module for modulation, and the synthesized voltage space vector is output to the inverter to drive the switching state of the three half bridges of the inverter at that moment and thus control the rotation of the motor.

[0042] In the embodiment of the present application, a sensorless drive scheme for permanent magnet synchronous motor based on phase-shifted square wave injection (PS-SWVI) is proposed to address the shortcomings of half-switching frequency square wave injection. Compared with the traditional error compensation method, the method of the embodiment of the present application can suppress the third position harmonic without knowing the detailed model of the specific error cause by introducing an alternating polarity phase shift angle in the injected voltage vector, thereby improving the estimation accuracy and avoiding the problem of inaccurate compensation caused by changes in motor parameters.

[0043] The PS-SWVI proposed in the embodiment of the present application does not need to rely on motor parameters for position estimation. In addition, the position estimation process can remain unchanged from the traditional SWVI. Therefore, the method is easy to implement.

[0044] Above, the details of the overall process of the image generation method in the embodiment of the present application are introduced through steps S110 to 140. Below, the contents further included in each step are described in detail.

[0045] It should be noted that, for step S110, the reference current of the permanent magnet synchronous motor may be preset, or may be determined based on the output signal of the speed loop in the FOC framework.

[0046] In step S110, the process of obtaining the response current of the permanent magnet synchronous motor may be to sample the three-phase current of the permanent magnet synchronous motor, and then perform dimensionality reduction processing on the three-phase current, i.e., space vector transformation, usually by using the Clarke transformation algorithm to transform the three-phase electrical signal ( ) is converted into a two-phase signal ( ), one phase is the zero-sequence component (also called the DC component) and the other phase is the positive-sequence component (also called the rotating component).

[0047] In a possible implementation manner, the method of the embodiment of the present application further includes: separating a first fundamental response current and a high-frequency response current from the response current.

[0048] Specifically, the response current in the α-β coordinate system can be The fundamental response current and the high-frequency response current are separated, and the fundamental response current and the reference current are subsequently used for PI control to output the control voltage of the motor, and the high-frequency response current is used to estimate the position of the motor rotor.

[0049] It should be noted that after separating the first fundamental response current and the high-frequency response current from the response current, the method of the embodiment of the present application may also include: obtaining an estimated position, and determining an equivalent position error based on the high-frequency response current and the estimated position; then, performing a phase-locked loop based on the equivalent position error to obtain an updated estimated position.

[0050] It is understandable that the embodiment of the present application injects a high-frequency pulse square wave signal into the motor stator and uses the change in the motor response to obtain the motor's rotor position information. Therefore, it is necessary to separate the high-frequency response current from the motor's response current, and then estimate the motor's rotor position based on the high-frequency response current, analyze the deviation between the current estimated position and the previous estimated position, and obtain the position error value. The embodiment of the present application performs phase-locked loop adjustment based on the position error value to achieve error compensation and output an updated estimated position.

[0051] In a possible specific example, by performing difference or sum operation on the current before and after, the fundamental current and high-frequency current of the response current are separated to obtain the high-frequency response current; the equivalent position error is determined based on the high-frequency response current and the estimated position, which can be implemented by referring to the above formula 4 and will not be repeated here; a phase-locked loop is performed based on the equivalent position error, that is, the equivalent position error is converted to The error is input to the phase-locked loop module, which outputs the estimated speed and estimated position of the permanent magnet synchronous motor rotor based on the error as feedback for the speed loop and current loop under the FOC framework.

[0052] It should be noted that, for step S120, the process of determining the first control voltage based on the reference current and the response current may include: determining the second fundamental response current based on the first fundamental response current and the updated estimated position; and then determining the first control voltage based on the error between the reference current and the second fundamental response current.

[0053] It can be understood that the embodiment of the present application uses the fundamental response current and the reference current to calculate the error, and then performs PI control based on the error to output the control voltage (first control voltage) of the motor. In order to use the fundamental response current and the reference current for PI control, the separated fundamental response current can be first transformed from the α-β coordinate system to the dq coordinate system through the Park transformation algorithm to further reduce the dimension of the fundamental response current and convert it into a linear variable. The dq coordinate system always rotates with the rotor, and the rotation angle θ takes the value of the estimated position, that is: the motor rotor position estimated by the high-frequency response current is applied to the Park transformation to transform the fundamental response current from the α-β coordinate system to the dq coordinate system. In the embodiment of the present application, the fundamental response current before the Park transformation is referred to as the first fundamental response current, and the fundamental response current after the Park transformation is referred to as the second fundamental response current.

[0054] It should be noted that, for step S130, the process of performing space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage may include: determining a third control voltage based on the second control voltage and the updated estimated position; and then, performing space vector pulse width modulation on the permanent magnet synchronous motor based on the third control voltage.

[0055] It can be understood that the first control motor output by the reference current and the response current through PI operation, and the second control voltage formed by combining the first control voltage and the high-frequency pulse square wave are both voltages in the dq coordinate system. The implementation of space vector pulse width modulation (SVPWM) requires the use of a stationary α-β coordinate system. Therefore, it is necessary to perform an inverse Park transformation on the second control voltage to convert it into the α-β coordinate system to obtain a third control voltage, and then perform SVPWM on the permanent magnet synchronous motor based on the third control voltage. The PWM signal output by the SVPWM controls the switching state of the inverter to generate specific voltage vectors. These vectors generate voltage on the motor stator, thereby controlling the magnetic flux and torque of the motor.

[0056] It is understandable that the inverse Park transformation requires the rotation angle of the motor rotor, so in specific implementation, the updated estimated position needs to be used to perform an inverse Park transformation on the second control voltage.

[0057] In a possible implementation of the present application, an equivalent position error is determined based on the high-frequency response current and the estimated position, including: multiplying the high-frequency response current with the sign of the high-frequency pulse square wave to obtain a demodulated high-frequency response current; determining an estimated position vector based on the estimated position and the injected phase shift angle; and cross-multiplying the demodulated high-frequency response current with the estimated position vector to obtain an equivalent position error.

[0058] It can be understood that the amplitude of the high frequency response current is , can be demodulated by multiplying the sign of the injected voltage, such as or Then, the equivalent position error is obtained by cross-producting with the estimated position vector. The estimated position vector is determined based on the estimated position and the injection phase shift angle. For example, when the injection angle is considered to be 0, the equivalent position error is obtained by cross-producting with the estimated position vector as follows: = sin(2 (Formula 7) In a possible implementation of the present application, before performing a phase-locked loop based on the equivalent position error, the equivalent position error is normalized based on the high-frequency response current to simplify the algorithm implementation and improve the calculation efficiency.

[0059] In a possible implementation of the present application, the method of the embodiment of the present application also includes: separating a high-frequency response current from the response current; obtaining an estimated position, and determining an equivalent position error based on the high-frequency response current and the estimated position; determining an injection phase shift angle based on the equivalent position error; and adjusting the injection phase shift angle based on the injection phase shift angle.

[0060] For example, considering the existence of the third harmonic component and assuming that the position error is suppressed to zero, the steady-state high-frequency response current vector when the injection angle is positive can be modeled as: (Formula 8) in yes is the amplitude of the positive third harmonic component, so the equivalent position error can be expressed as: = ≈ + sin (Formula 9) Similarly, the steady-state high-frequency response current vector when the injection angle is negative can be modeled as: (Formula 10) Correspondingly, the equivalent position error can be expressed as: = ≈ + sin (Formula 11) It can be seen from formula 9 and formula 11 that adjusting the injection phase shift angle , the third harmonic component in the equivalent position error can be adjusted. Therefore, the equivalent position error can be modeled, and based on the equivalent position error model, the optional value of the injection phase shift angle when the third harmonic component is to be suppressed to zero can be determined, and then the injection phase shift angle can be adjusted based on the injection phase shift angle.

[0061] In a possible implementation of the present application, the process of determining the injection phase shift angle based on the equivalent position error may include: determining the average equivalent position error based on two adjacent equivalent position errors; constructing an average equivalent position error model based on the average equivalent position error, estimated position, injection phase shift angle and true position, the average equivalent position error model including a position estimation component and a high-order harmonic component; determining the injection phase shift angle when the high-order harmonic component is zero based on the average equivalent position error model; and adjusting the injection phase shift angle based on the injection phase shift angle.

[0062] It can be understood that since the injection angle is switched instantaneously, the nonlinear effects causing the third harmonic can be considered the same. Therefore, ..same, , the average equivalent position error can be expressed as: ( ) = + sin (Formula 12) in, represents the position estimate, sin Represents the third harmonic component.

[0063] It can be understood that since the injection angle is a sign switch, this method only considers angles from 0 to 180 degrees. It can be seen from formula 12 that when When the angle is 30 degrees, 90 degrees, and 150 degrees, the amplitude of the third harmonic is zero, so the third-order position error can be eliminated.

[0064] In a possible implementation of the present application, there are multiple different candidate values ​​for the injection phase shift angle when the high-order harmonic component is zero; the injection phase shift angle is adjusted based on the injection phase shift angle, including: constructing a total harmonic distortion model based on the high-order harmonic component and the position error gain; based on the total harmonic distortion model, determining the total harmonic distortion corresponding to each candidate value; and adjusting the injection phase shift angle based on the candidate value with the smallest total harmonic distortion.

[0065] As in the previous example, when When the injection angle is 30 degrees, 90 degrees, and 150 degrees, the amplitude of the third harmonic is zero, but when the injection angle is 90 degrees, the high-frequency voltage is completely injected into the q-axis, resulting in non-negligible torque pulsation. Therefore, the following analysis will only consider the case where the injection angle amplitude is 30 degrees and 150 degrees. When considering other harmonic components, the average equivalent position estimation error can be rewritten as: + (Formula 13) Assuming that the amplitude of each harmonic component is the same, when only considering the 1st to 6th harmonics, when the injection angle is 30° and 150°, the amplitude of the common harmonic components (1, 2, 3, 6) is the same. Therefore, the injection angle can be determined by calculating the total harmonic distortion (THD). THD can be defined as the ratio of the sum of harmonic distortion to the fundamental component. THD can be expressed as: (Formula 14) because The amplitude of is only determined by the amplitude of the injected pulse square wave, so it has nothing to do with the injection angle. It is only for comparison. The amplitudes of the high-order harmonic components of each order are the same. Therefore, formula 14 can be simplified to: (Formula 15) Considering the harmonic order from 1 to 6, then The THD is calculated to be 59.15, The THD is calculated to be 66.43. Therefore, the final choice is is the optimal injection angle because it has lower THD.

[0066] See also Figure 2 , is a schematic diagram of the architecture of a position sensorless permanent magnet synchronous motor control method provided in an embodiment of the present application. Figure 2 The architecture shown is used to exemplarily illustrate the implementation process of a position sensorless permanent magnet synchronous motor control method provided in an embodiment of the present application.

[0067] like Figure 2 As shown, the implementation process of a position sensorless permanent magnet synchronous motor control method provided in an embodiment of the present application may include: S310, sampling the three-phase current of the permanent magnet synchronous motor to obtain a response current; S320, yes Perform Clarke transformation to obtain ; S330, yes Current separation to isolate the fundamental part of the response current and high frequency part ; S340, based on estimated position For the basic part Perform park transformation to obtain current , where the estimated position Based on the high frequency part Determined by making a position estimate; S350, the reference current and Input to the PI controller to get the control voltage ; S360, Inject high frequency pulse square wave , and the control voltage is obtained ,in, Based on the injection phase shift angle Determine the injection phase shift angle At the beginning of each cycle of the high-frequency pulse square wave, a positive and negative switch is performed. equal or - ; S370, based on estimated position For control voltage Perform inverse park transformation and get ; S380, based on Perform SVPWM modulation and output the corresponding PWM signal To control the inverter to drive the permanent magnet synchronous motor with a synthetic voltage.

[0068] like Figure 2 As shown, based on the high frequency part Estimated location The process includes signal processing and observer processing. Next, the position estimation part will be further introduced.

[0069] like Figure 3 As shown, it is a schematic diagram of the architecture of the position estimation part provided in the embodiment of the present application, based on Figure 3 According to the architecture shown, the process of estimating the motor rotor position in the embodiment of the present application may include: S410, The sign of the injected pulse square wave voltage Multiply to achieve The demodulation of ; S420, With the estimated position vector Perform cross product to get the equivalent position error ; S430, equivalent position error and Divide to achieve Normalization of S440, Perform two delays ( ), to take the two adjacent Value (one-time injection Positive, once injected is negative) to calculate the average equivalent position error; S450, Input to the PLL module , to get the estimated speed , and then the estimated position is obtained by integrating the velocity .

[0070] It should be noted that the estimated position Need to be fed back to the fundamental current Park conversion, control voltage In the inverse park transformation.

[0071] It should be noted that the estimated position It also needs to be fed back to the equivalent position error 's calculation to achieve a closed loop.

[0072] It should be noted that the phase-locked loop module The estimated position and velocity can be filtered by the low-pass characteristic of the PI controller, and division and differentiation operations are avoided, thereby reducing the estimation error caused by noise in the system.

[0073] It should be noted that the above step S410 belongs to the signal processing part in the position estimation, and S420-S450 belong to the observer processing part in the position estimation.

[0074] In order to improve the bandwidth of the observer, the method of the embodiment of the present application proposes an improved position estimation process. By adding an averaging process to the equivalent position error of the previous injection sequence, the high-frequency components introduced by this method can be effectively reduced, thereby improving the bandwidth of the observer and the controller.

[0075] In the embodiment of the present application, a low-speed sensorless control scheme for a permanent magnet synchronous motor based on phase-shifted square wave injection (PS-SWVI) is proposed to address the problem of third harmonic position error in the traditional square wave injection sensorless control of a permanent magnet synchronous motor. This scheme reduces the third-order estimation error while achieving sensorless control, and is simple to implement and does not depend on motor parameters. The method of the embodiment of the present application can offset the third harmonic component in the estimation error by introducing two injection angles of equal amplitude and opposite magnitude, and perform signal processing optimization to reduce position and speed oscillations. Subsequently, the rotor position and speed information are estimated through a phase-locked loop (PLL), making sensorless control possible.

[0076] In general, compared with the traditional error compensation method, the method provided by the embodiment of the present application can suppress the third position harmonics when the detailed model of the specific error cause is unknown, thereby improving the estimation accuracy and avoiding the problem of inaccurate compensation caused by changes in motor parameters; compared with the high-order filter observer method, the method provided by the embodiment of the present application has a simple demodulation scheme and observer structure, and does not require a complex parameter adjustment process, which reduces the difficulty of implementation and the system calculation burden. In addition, the method provided by the embodiment of the present application also modifies the demodulation process by analyzing the equivalent position error to reduce high-frequency oscillations.

[0077] The method of the embodiment of the present application is described above, and the device provided by the embodiment of the present application is introduced below.

[0078] See also Figure 4 , is a schematic diagram of a position sensorless permanent magnet synchronous motor control device provided in an embodiment of the present application, and the permanent magnet synchronous motor control device has the function of implementing the position sensorless permanent magnet synchronous motor control method provided in any of the above embodiments. The function can be implemented by hardware, or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions.

[0079] In a possible implementation, the position sensorless permanent magnet synchronous motor control device includes: A current acquisition module, used to obtain a reference current and a response current of the permanent magnet synchronous motor; A voltage determination module, configured to determine a first control voltage based on a reference current and a response current; A square wave injection module, used for injecting a high-frequency pulse square wave into the first control voltage to obtain a second control voltage, wherein the high-frequency pulse square wave is determined based on an injection phase shift angle, and the injection phase shift angle is switched between positive and negative once at the start of each cycle of the high-frequency pulse square wave; The modulation module is used to perform space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage.

[0080] It should be noted that the information interaction, execution process, etc. between the above-mentioned modules / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0081] It should be noted that the apparatus described in the embodiments of the present application is only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some communication interface, device or unit, which may be electrical, mechanical or other forms.

[0082] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0083] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0084] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a processor-executable non-volatile computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium.

[0085] See also Figure 5 The embodiment of the present application further provides an electronic device 300. The electronic device 300 may be a server or a terminal, and the internal structure of the electronic device 300 includes but is not limited to: A memory 310, used for storing programs; The processor 320 is used to execute the program stored in the memory 310. When the processor 320 executes the program stored in the memory 310, the processor 320 is used to execute the position sensorless permanent magnet synchronous motor control method as in any of the previous embodiments.

[0086] The processor 320 and the memory 310 may be connected via a bus or other means.

[0087] The memory 310 is a non-transient computer-readable storage medium that can be used to store non-transient software programs and non-transient computer executable programs, such as the position sensorless permanent magnet synchronous motor control described in any embodiment of the present application. The processor 320 implements the position sensorless permanent magnet synchronous motor control method as described in any of the previous embodiments by running the non-transient software programs and instructions stored in the memory 310.

[0088] The memory 310 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store the execution of the above-mentioned position sensorless permanent magnet synchronous motor control method. In addition, the memory 310 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 310 may optionally include a memory remotely arranged relative to the processor 320, and these remote memories may be connected to the processor 320 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0089] The non-transient software programs and instructions required to implement the above-mentioned position sensorless permanent magnet synchronous motor control method are stored in the memory 310. When executed by one or more processors 320, the position sensorless permanent magnet synchronous motor control method provided by any embodiment of the present application is executed.

[0090] An embodiment of the present application further provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the above-mentioned position sensorless permanent magnet synchronous motor control method.

[0091] In one embodiment, the storage medium stores computer executable instructions, which are executed by one or more control processors, for example, by one or more processors 320 in the above-mentioned electronic device 300, so that the above-mentioned one or more processors 320 can execute the position sensorless permanent magnet synchronous motor control method provided in any embodiment of the present application.

[0092] It will be appreciated by those skilled in the art that all or some of the steps and systems in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or transient medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically include computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0093] In addition, an embodiment of the present application further provides a computer program product, including a computer program, which, when executed by a processor, implements a position sensorless permanent magnet synchronous motor control method as in any of the previous embodiments.

[0094] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for the parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0095] It should also be understood that the various implementations provided in the embodiments of the present application can be combined arbitrarily to achieve different technical effects.

[0096] Finally, it should be noted that the embodiments described above are only specific implementation methods of the present application, which are used to illustrate the technical solution of the present application rather than to limit it. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that any technician familiar with this technical field can still modify the technical solution recorded in the aforementioned embodiments within the technical scope disclosed in the present application, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiments of the present application, and should all be covered by the protection scope of the present application.

Claims

1. A method for controlling a permanent magnet synchronous motor without a position sensor, characterized in that: The method comprises: Obtaining reference current and response current of the permanent magnet synchronous motor; determining a first control voltage based on the reference current and the response current; Injecting a high-frequency pulse square wave into the first control voltage to obtain a second control voltage, wherein the high-frequency pulse square wave is determined based on an injection phase shift angle, and the injection phase shift angle is switched between positive and negative once at the start of each cycle of the high-frequency pulse square wave; The permanent magnet synchronous motor is subjected to space vector pulse width modulation based on the second control voltage.

2. The method according to claim 1, characterized in that The method further comprises: Separating a first fundamental response current and a high-frequency response current from the response current; Acquire an estimated position, and determine an equivalent position error based on the high frequency response current and the estimated position; Perform a phase-locked loop based on the equivalent position error to obtain an updated estimated position; The step of determining a first control voltage based on the reference current and the response current comprises: determining a second fundamental response current based on the first fundamental response current and the updated estimated position; determining the first control voltage based on an error between the reference current and the second fundamental response current; The performing space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage includes: determining a third control voltage based on the second control voltage and the updated estimated position; The permanent magnet synchronous motor is subjected to space vector pulse width modulation based on the third control voltage.

3. The method according to claim 2, characterized in that The determining of an equivalent position error based on the high frequency response current and the estimated position comprises: Multiplying the high-frequency response current by the sign of the high-frequency pulse square wave to obtain a demodulated high-frequency response current; determining an estimated position vector based on the estimated position and the injection phase shift angle; The demodulated high frequency response current is cross-multiplied with the estimated position vector to obtain the equivalent position error.

4. The method according to claim 2, characterized in that: Before performing a phase-locked loop based on the equivalent position error, the method further includes: The equivalent position error is normalized based on the high frequency response current.

5. The method according to claim 1, characterized in that The method further comprises: separating a high frequency response current from the response current; Acquire an estimated position, and determine an equivalent position error based on the high frequency response current and the estimated position; Determine the injection phase shift angle based on the equivalent position error; The injection phase shift angle is adjusted based on the injection phase shift angle size.

6. The method according to claim 5, characterized in that The step of determining the injection phase shift angle based on the equivalent position error comprises: Based on two consecutive equivalent position errors, an average equivalent position error is determined; Based on the average equivalent position error, the estimated position, the injected phase shift angle and the true position, construct an average equivalent position error model, wherein the average equivalent position error model includes a position estimation component and a high-order harmonic component; Determine the injection phase shift angle when the high-order harmonic component is zero based on the average equivalent position error model; The injection phase shift angle is adjusted based on the injection phase shift angle size.

7. The method according to claim 6, characterized in that There are multiple different candidate values ​​for the injection phase shift angle when the high-order harmonic component is zero; The step of adjusting the injection phase shift angle based on the injection phase shift angle comprises: Constructing a total harmonic distortion model based on the higher-order harmonic components and the position error gain; Based on the total harmonic distortion model, determining the total harmonic distortion corresponding to each of the candidate values; The injection phase shift angle is adjusted based on the candidate value with the minimum total harmonic distortion.

8. A permanent magnet synchronous motor control device without position sensor, characterized in that: The device comprises: A current acquisition module, used to obtain a reference current and a response current of the permanent magnet synchronous motor; A voltage determination module, configured to determine a first control voltage based on a reference current and the response current; A square wave injection module, used for injecting a high-frequency pulse square wave into the first control voltage to obtain a second control voltage, wherein the high-frequency pulse square wave is determined based on an injection phase shift angle, and the injection phase shift angle is switched between positive and negative once at the start of each cycle of the high-frequency pulse square wave; A modulation module is used to perform space vector pulse width modulation on the permanent magnet synchronous motor based on the second control voltage.

9. An electronic device, characterized in that: include: Memory, used to store programs; A processor, configured to execute the program stored in the memory. When the processor executes the program stored in the memory, the processor is configured to execute: a method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: Computer executable instructions are stored, and the computer executable instructions are used to execute: the method according to any one of claims 1 to 7.

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