Sensorless control system and method for permanent magnet synchronous motor

Abstract

The application discloses a sensorless control system and method of a permanent magnet synchronous motor, and belongs to the field of motor control. The sensorless control system of the permanent magnet synchronous motor comprises a speed loop controller, a current loop controller, an inverter, a coordinate transformer, a position error observer and a rotating speed observer. The position error observer is an amplitude observer based on a moving average filter. The moving average filter has a band-stop characteristic in multiple frequency intervals, and high-frequency signals to be filtered out are only distributed in several specific frequency ranges. Therefore, the moving average filter can effectively filter out noise, solves a phase time delay problem caused by low-pass and band-pass filters, and realizes accurate tracking of the rotor position.

Description

Technical Field

[0001] This invention relates to the field of motor control, and in particular to a sensorless control system and method for a permanent magnet synchronous motor. Background Technology

[0002] Vector control boasts excellent dynamic performance, torque response, and a wide speed range, making it widely used in the control of permanent magnet synchronous motors (PMSMs). However, its control performance is heavily dependent on various motor parameters, typically requiring high-precision encoders to obtain motor speed. Since the introduction of encoders reduces system stability and increases manufacturing and maintenance costs, research into sensorless control has become a popular area of ​​research.

[0003] High-frequency signal injection is a method for obtaining rotor position information based on the salient pole characteristics of a motor. Because it does not rely on the motor's back electromotive force, high-frequency signal injection performs well even at low speeds and when stationary. Therefore, it can be used not only for rotor initial position detection but also for sensorless control of a PMSM (Motor-Mounted Module). Traditional high-frequency signal injection methods use phase-locked loops (PLLs) to obtain rotor position information. The introduction of low-pass and band-pass filters negatively impacts system performance, primarily in the following ways: 1) it reduces system bandwidth, affecting dynamic performance; 2) it introduces a phase delay, potentially causing motor start-up failure. Summary of the Invention

[0004] The purpose of this invention is to provide a sensorless control system and method for permanent magnet synchronous motors, which can solve the phase delay problem caused by low-pass and band-pass filters and achieve accurate tracking of rotor position.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A sensorless control system for a permanent magnet synchronous motor includes: a speed loop controller, a current loop controller, an inverter, a coordinate transformer, a position error observer, and a speed observer;

[0007] The position error observer is an amplitude observer based on a moving average filter;

[0008] The speed loop controller, current loop controller, inverter, permanent magnet synchronous motor, coordinate transformer, position error observer and speed observer are connected in sequence. The speed observer is also connected to the speed loop controller, current loop controller and coordinate transformer respectively to form a closed loop.

[0009] The speed loop controller is used to obtain the desired current value based on the error between the desired speed and the actual speed;

[0010] The current loop controller is used to inject a high-frequency pulsating signal and, using the desired current value and the estimated rotor position, outputs a PWM pulse signal as the control signal for the inverter.

[0011] Inverters are used to control the speed of permanent magnet synchronous motors based on PWM pulse signals;

[0012] The coordinate transformer is used to convert the three-phase alternating signal in the three-phase stationary coordinate system output after the speed control of the permanent magnet synchronous motor into a current signal in the two-phase rotating coordinate system based on the estimated rotor position.

[0013] The position error observer is used to filter the current signal error in the two-phase rotating coordinate system using a moving average filter, and obtain the rotor position error based on the filtered current signal error.

[0014] The speed observer is used to obtain the estimated rotor position and the actual rotor speed based on the rotor position error. The actual rotor speed is transmitted to the speed loop controller, and the estimated rotor position is transmitted to the current loop controller and the coordinate transformer respectively to form a closed loop control.

[0015] Optionally, when using a moving average filter to filter the error of the current signal in a two-phase rotating coordinate system, the following two conditions must be met:

[0016]

[0017] ω s =Mω h

[0018] Among them, T ω ω is the window length of the moving average filter. h ω is the frequency of the high-frequency pulse signal. s M is the switching frequency of the inverter, where M is an integer.

[0019] Optionally, the time-domain transfer function of the moving average filter is: Among them, G MAF (s) is the time-domain transfer function, where s is a complex parameter;

[0020] The transfer function of the discretized moving average filter is: Among them, G MAF (z) is the discretized transfer function, N is the ratio, and N = T ω / T s T s Let z be the sampling period of the current, and z be a complex parameter.

[0021] The stopband center frequency of the moving average filter is Where, ω n is the stopband center frequency, and n is a positive integer.

[0022] Optionally, the current loop controller includes: a torque component-side PI controller, a magnetizing component-side PI controller, an inverse Park transform module, and a space vector pulse width modulation module;

[0023] The torque component-side PI controller is connected to both the speed loop controller and the inverse Parker transformation module. The torque component-side PI controller is used to control the torque component i of the desired current value. q Perform control to output the desired q-axis voltage;

[0024] The excitation component-side PI controller is connected to the inverse Park transformation module. The excitation component-side PI controller is used to control the excitation component i of the desired current value. d The system controls and outputs the desired d-axis voltage. This desired d-axis voltage is then superimposed with a high-frequency pulsating voltage signal and input to the inverse Park transformation module. The excitation component i of the desired current value... d Equal to 0;

[0025] The inverse Park transformation module is connected to the space vector pulse width modulation module. The inverse Park transformation module is used to convert the expected voltage on the q-axis and the expected voltage on the d-axis after superimposing the high-frequency pulsating voltage signal into voltage components in a two-phase stationary coordinate system based on the estimated rotor position.

[0026] The space vector pulse width modulation module is connected to the inverter. The space vector pulse width modulation module is used to generate PWM pulse signals based on the voltage components in the two-phase stationary coordinate system using the SVPWM algorithm.

[0027] Optionally, the position error observer includes: a current signal error calculation module, a moving average filter, and an integrator;

[0028] The input terminals of the current signal error calculation module are connected to the coordinate transformer and the integrator, respectively, and the output terminal is connected to the moving average filter. The current signal error calculation module is used to obtain the q-axis current signal in a two-phase rotating coordinate system from the coordinate transformer and to obtain the observed high-frequency current amplitude from the integrator. Furthermore, based on the q-axis current signal in the two-phase rotating coordinate system and the observed high-frequency current amplitude... Determine the error of the current signal in a two-phase rotating coordinate system;

[0029] The moving average filter is connected to the integrator. The moving average filter is used to filter the error of the current signal in the two-phase rotating coordinate system, and the observed high-frequency current amplitude is obtained by compensation through the integrator.

[0030] Optionally, the formula for calculating the current signal error in the two-phase rotating coordinate system is as follows:

[0031] e = HF(ω) h t)+HF(ω s t)+HF(ΔI q h)

[0032] in,

[0033] e represents the current signal error in the two-phase rotating coordinate system, HF() represents the high-frequency signal component, t represents time, and ΔI represents the current signal error. qh q-axis current signal in a two-phase rotating coordinate system and feedback signals The amount of error between them The amplitude of the fundamental current. The amplitude of the induced current generated by the high-frequency pulsed voltage signal. High-frequency noise generated by inverter switching transistors The amplitude.

[0034] Optionally, the rotational speed observer is an extended state observer;

[0035] The expression for the extended state observer is:

[0036] in, The first derivative of the rotor position estimate. The first derivative of the estimated electric angular velocity. The first derivative of the estimated value of the uncertain part of the system. J is the moment of inertia of the permanent magnet synchronous motor, p is the number of pole pairs, and T is the moment of inertia of the motor. L Where B is the load torque, ω is the coefficient of friction. e Let ω be the electric angular velocity. e =p·ω m ω m Let Δθ be the mechanical angular velocity. e T represents the rotor position estimation error. e The electromagnetic torque is represented by β1, β2, and β3, which are the first, second, and third parameters, respectively. ξ is the damping coefficient, ω b As an intermediate variable, ω 3dB This represents the desired bandwidth.

[0037] Optionally, it also includes: a first low-pass filter and a second low-pass filter;

[0038] The first low-pass filter is connected to both the coordinate transformer and the current loop controller. The first low-pass filter is used to process the d-axis current signal in a two-phase rotating coordinate system. Filtering is performed to input the fundamental current signal of the d-axis to the current loop controller;

[0039] The second low-pass filter is connected to both the coordinate transformer and the current loop controller. This second low-pass filter is used to process the q-axis current signal in a two-phase rotating coordinate system. Filtering is performed to input the fundamental current signal of the q-axis to the current loop controller.

[0040] A sensorless control method for a permanent magnet synchronous motor includes:

[0041] The desired current value is obtained based on the error between the desired speed and the actual speed.

[0042] A high-frequency pulse signal is injected into the current loop controller, and a PWM pulse signal is output based on the desired current value and the estimated rotor position.

[0043] Speed ​​control of permanent magnet synchronous motor is performed based on PWM pulse signal;

[0044] Based on the estimated rotor position, the three-phase alternating signal output from the three-phase stationary coordinate system after speed control of the permanent magnet synchronous motor is converted into a current signal in a two-phase rotating coordinate system.

[0045] A moving average filter is used to filter the current signal error in the two-phase rotating coordinate system, and the rotor position error is obtained based on the filtered current signal error.

[0046] Based on the rotor position error, the estimated rotor position and the actual rotor speed are obtained, forming a closed-loop control.

[0047] Optionally, when using a moving average filter to filter the error of the current signal in a two-phase rotating coordinate system, the following two conditions must be met:

[0048]

[0049] ω s =Mω h

[0050] Among them, T ω ω is the window length of the moving average filter. h ω is the frequency of the high-frequency pulse signal. s M is the switching frequency of the inverter, where M is an integer.

[0051] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0052] This invention discloses a sensorless control system and method for a permanent magnet synchronous motor. The position error observer is an amplitude observer based on a moving average filter. The moving average filter exhibits band-stop characteristics in multiple frequency ranges, while the high-frequency signals that need to be filtered out are only distributed in a few specific frequency ranges. Therefore, the moving average filter can effectively filter out noise, solving the phase delay problem caused by low-pass and band-pass filters, and achieving accurate tracking of the rotor position. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a structural block diagram of a sensorless control system for a permanent magnet synchronous motor provided in an embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of the coordinate system provided in an embodiment of the present invention;

[0056] Figure 3 This is a structural block diagram of a position error observer provided in an embodiment of the present invention;

[0057] Figure 4 A comparison diagram of the frequency characteristics of a moving average filter and a notch filter provided in an embodiment of the present invention;

[0058] Figure 5 Simulation diagram of rotor position estimation performance of conventional high-frequency pulse signal injection method provided in embodiments of the present invention;

[0059] Figure 6 Simulation diagram of rotor position estimation performance of the improved high-frequency pulse signal injection method of this invention;

[0060] Figure 7 The simulation diagram shows the speed response of a sensorless control strategy based on traditional high-frequency pulse signal injection.

[0061] Figure 8 The figure shows the speed response simulation of the control scheme proposed in this invention.

[0062] Figure 9 This is a flowchart of a sensorless control method for a permanent magnet synchronous motor provided in an embodiment of the present invention. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] The purpose of this invention is to provide a sensorless control system and method for permanent magnet synchronous motors, which can solve the phase delay problem caused by low-pass and band-pass filters and achieve accurate tracking of rotor position.

[0065] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0066] This invention provides a sensorless control system for a permanent magnet synchronous motor. It designs a novel observer and adopts a sensorless control structure based on vector control, using a high-frequency signal injection method to obtain rotor position and speed.

[0067] This invention provides a sensorless control system for a permanent magnet synchronous motor, such as... Figure 1 As shown, it includes: a speed loop controller, a current loop controller, an inverter, a coordinate transformer, a position error observer, and a speed observer.

[0068] The position error observer is an amplitude observer based on a moving average filter. The speed loop controller, current loop controller, inverter, permanent magnet synchronous motor (PMSM), coordinate transformer, position error observer, and speed observer are connected sequentially. The speed observer is also connected to the speed loop controller, current loop controller, and coordinate transformer, forming a closed loop. The speed loop controller obtains the desired current value based on the error between the desired and actual speeds. The current loop controller injects a high-frequency pulsating signal and outputs a PWM pulse signal using the desired current value and the estimated rotor position, serving as the control signal for the inverter. The inverter performs speed control on the PMSM based on the PWM pulse signal. The coordinate transformer converts the three-phase alternating signal in the three-phase stationary coordinate system output after speed control of the PMSM into a current signal in the two-phase rotating coordinate system based on the estimated rotor position. The position error observer uses a moving average filter to filter the error in the current signal in the two-phase rotating coordinate system and obtains the rotor position error based on the filtered current signal error. The speed observer is used to obtain the estimated rotor position and the actual rotor speed based on the rotor position error. The actual rotor speed is transmitted to the speed loop controller, and the estimated rotor position is transmitted to the current loop controller and the coordinate transformer respectively to form a closed loop control.

[0069] The principle of high-frequency pulse signal injection method is as follows: Figure 2 As shown, an estimated rotating coordinate system needs to be constructed. (Coordinate system), the position of which is determined by the estimated rotor angle. To decide. and the actual rotor position angle θ e There is an error Δθ e The role of the position observer is to make Δθ e Approaching 0, thus enabling infinitely close to θ e .

[0070] Under high-frequency conditions, the voltage equation of the PMSM in the dq coordinate system can be expressed as:

[0071]

[0072] In the formula u dh and u qh Representing the d-axis voltage and q-axis voltage in the dq coordinate system, respectively, i dh and i qh L represents the d-axis current and q-axis current, respectively. d and L q These represent the d-axis inductance and the q-axis inductance, respectively, and P is the differential operator.

[0073] Transform the voltage equation to Coordinate system, can be obtained

[0074]

[0075] In the formula and Represent coordinate system shaft voltage and shaft voltage, and Represent shaft current and shaft current,

[0076] 1) Speed ​​Loop Controller

[0077] The speed loop controller is implemented using a PI controller, utilizing the desired speed N. ref and actual rotational speed N e The error is measured by using a PI controller to obtain the desired current value, which is then used as the given signal for the current loop controller.

[0078] 2) Current loop controller

[0079] The current loop controller also uses a PI controller. After coordinate transformation, the three-phase current of the motor is decomposed into torque components (i... q ) and excitation component (i d Both are controlled separately.

[0080] In this invention, i is used d =0 control strategy, therefore the torque component side PI controller is connected to the speed loop, and the output of the speed loop is used as the setpoint of the torque component side PI controller; while the setpoint of the excitation component side is a constant value of 0.

[0081] After obtaining the output of the PI controller on the excitation variable side, a high-frequency pulsating voltage signal needs to be superimposed. High-frequency pulsed signals are used to obtain rotor position information, and are used as the input signal for the high-frequency signal injection method. Where V... h ω represents the amplitude of the high-frequency signal. g The frequency of the signal is specified. The output signal of the PI controller then needs to be converted into a PWM pulse signal using the SVPWM algorithm to control the inverter, thereby achieving speed control of the PMSM.

[0082] For example, the current loop controller includes: a torque component-side PI controller, a magnetizing component-side PI controller, an inverse Park transform module, and a space vector pulse width modulation module.

[0083] The torque component-side PI controller is connected to both the speed loop controller and the inverse Parker transformation module. The torque component-side PI controller is used to control the torque component i of the desired current value. q Perform control to output the desired q-axis voltage. (Refer to...) Figure 1 The torque component of the desired current value i q The difference between the fundamental current signal of the q-axis output by the second low-pass filter LPF and the input to the torque component side PI controller is calculated.

[0084] The excitation component-side PI controller is connected to the inverse Park transformation module. The excitation component-side PI controller is used to control the excitation component i of the desired current value. d The system controls and outputs the desired d-axis voltage. This desired d-axis voltage is then superimposed with a high-frequency pulsating voltage signal and input to the inverse Park transformation module. The excitation component i of the desired current value... d Equals 0. (Refer to...) Figure 1 The excitation component i of the desired current value d The difference between the current fundamental signal on the d-axis output of the first low-pass filter LPF and the input to the excitation component side PI controller is calculated.

[0085] The inverse Park transform module is connected to the space vector pulse width modulation module. The inverse Park transform module converts the expected q-axis voltage and the expected d-axis voltage (after superimposing a high-frequency pulsating voltage signal) into voltage components in a two-phase stationary coordinate system, based on the estimated rotor position. The space vector pulse width modulation module is connected to the inverter. This module generates PWM pulse signals using the SVPWM algorithm based on the voltage components in the two-phase stationary coordinate system.

[0086] Figure 1 In this context, Anti-Park stands for Inverse Park Transformation. Its main function is to transform coordinates, converting variables in the dq coordinate system into variables in the αβ coordinate system. The dq coordinate system is a rotating coordinate system, whose position is affected by the rotor angle of the motor, while the αβ coordinate system (two-phase stationary coordinate system) is stationary and does not change with the rotor rotation.

[0087] 3) Coordinate Transformer

[0088] The coordinate transformer converts the three-phase alternating signal in the three-phase stationary coordinate system into a DC signal (i.e., excitation component and torque component) in the two-phase rotating coordinate system (dq coordinate system) in order to improve the control performance of the PI controller.

[0089] The coordinate transformer converts the three-phase alternating signal in the three-phase stationary coordinate system into... The DC signal in the coordinate system. After coordinate transformation, the induced current generated by the injected high-frequency pulsating signal can be expressed as:

[0090]

[0091] As can be seen from formula (3), the generated high-frequency induced current contains rotor position information. Therefore, it is necessary to design a position error observer to extract the rotor position estimation error Δθ. e .

[0092] This invention is achieved through To obtain rotor position error information in practical application scenarios It can be represented as

[0093]

[0094] in Represents the fundamental current, used for current loop control. This represents the induced current generated by the injected high-frequency pulsating voltage signal. It is high-frequency noise generated by the inverter switching transistors.

[0095] Figure 1 In this context, Clark represents the Clark transform, and Park represents the Park transform.

[0096] 4) Position error observer

[0097] The position error observer is implemented using an improved amplitude observer. The induced current generated in the PMSM by the injected high-frequency pulsating signal contains rotor position information, which the position error observer utilizes... q This is used to extract the current rotor position error.

[0098] To address the adverse effects of phase delay and limited bandwidth caused by low-pass filters, this invention employs an improved amplitude observer (EAO) to extract rotor position error information. The block diagram of this observer is shown below. Figure 3 As shown.

[0099] For ease of analysis, equation (4) is first transformed into the following form.

[0100]

[0101] in and They are variables and The amplitude, and ω s This refers to the switching frequency of the inverter. According to... Figure 3 As can be seen from the structure of EAO, the moving average filter (MAF) filters the current error and extracts the high-frequency induced current amplitude error ΔI. qh Then, through the integrator, Compensation is then performed. First, the current error signal e is analyzed, which can be expressed in the form of equation (6).

[0102] e = HF(ω) h t)+HF(ω s t)+HF(ΔI q h) (6)

[0103] in

[0104]

[0105] Analysis of equations (6) and (7) reveals that the desired signal is only -0.5ΔI. qh For this step, all other high-frequency signals need to be filtered out. The simplest way is to use a low-pass filter, but low-pass filters reduce the system bandwidth.

[0106] To address the above problems, this invention employs a time-domain transfer function (MAF) to extract the current error signal. The time-domain transfer function of the MAF is:

[0107]

[0108] After discretization, the transfer function is transformed into

[0109]

[0110] Where T ω N is the window length of MAF, where N = T ω / T s T s The sampling period for the current is given. The frequency characteristics of the MAF are as follows: Figure 4 As shown, it exhibits resistance characteristics. Figure 4 The horizontal axis represents frequency, and the vertical axis represents gain. However, compared to ordinary band-stop filters, the advantage of MAF lies in its band-stop characteristics across multiple frequency ranges, with its stopband center frequency being [missing value].

[0111]

[0112] Where n is a positive integer. Based on the analysis of equation (7), the high-frequency signals that need to be filtered out are only distributed within a few specific frequency ranges. Therefore, when designing the control parameters, only the following two conditions need to be met:

[0113] i)

[0114] ii)ω s Select as ω h multiples of

[0115] Noise can be effectively filtered out using MAF. Furthermore, the EAO employs a negative feedback structure, which further ensures the observed high-frequency current amplitude. The accuracy.

[0116] Figure 3 In this context, κ is a proportionality coefficient, which can be understood as the gain coefficient in the subsequent integrator. and Δθ e The relationship between them is a simple proportional one. Because there is an adjustable proportional coefficient in the subsequent stage, this... It can be approximated as Δθ e .

[0117] 5) Rotational speed observer

[0118] The speed observer is implemented using an extended state observer (ESO), which observes the current rotor position and speed by using the rotor position error obtained from the position error observer. This speed value is then provided as the actual speed to the speed loop, thus forming a control closed loop.

[0119] The motion equation of PMSM is

[0120]

[0121] Where J is the moment of inertia of the PMSM, and T e and T L These are the electromagnetic torque and the load torque, respectively, where B is the coefficient of friction, and ω is the coefficient of friction. m It is the mechanical angular velocity, which is related to the electrical angular velocity ω. e The relationship is ω e =p·ω m Where p is the pole logarithm. Replacing the unknown states and disturbances in the system with Q, equation (11) can be transformed into...

[0122]

[0123] in The extended state observer (ESO) can be designed according to formula (12), and its expression is:

[0124]

[0125] β1, β2, and β3 are parameters of the ESO. The values ​​of β1, β2, and β3 can be determined using the following method.

[0126]

[0127] Where ξ is the damping coefficient, and ω b It can be obtained through the following formula

[0128]

[0129] Where ω 3dB This represents the desired bandwidth.

[0130] Depend on Figure 1 It can be seen that the output of the rotational speed observer is the mechanical angular velocity ω. m and estimated rotor position and After multiplying, we get the actual rotational speed N. e .

[0131] Figure 5 and Figure 6 These are comparative simulation results of rotor position observation performance. Figure 5 This is a traditional high-frequency pulse signal injection method. Figure 6 This invention presents the method proposed in this paper. It can be seen that traditional methods exhibit a certain lag in observing rotor position (Theta) at the initial moment, and the settling time is relatively long. In contrast, this invention can achieve more accurate tracking of the rotor position.

[0132] Figure 7 and Figure 8 These are comparative simulation results of the rotational speed response for a complete closed-loop control strategy. Figure 7 This is a sensorless control strategy based on traditional high-frequency pulse signal injection. Figure 8 This invention presents a sensorless control strategy based on the method proposed in this paper. Traditional methods generate significant overshoot during speed regulation, while the method proposed in this invention, thanks to its excellent rotor position observation performance, can achieve speed tracking with minimal or even zero overshoot during speed regulation.

[0133] The beneficial effects of this invention are mainly reflected in:

[0134] 1. A novel demodulation method is adopted for high-frequency induced current to solve the phase delay problem caused by low-pass and band-pass filters and improve the dynamic performance of the system.

[0135] 2. Using ESO as the rotation speed observer further improves the convergence speed;

[0136] 3. The control structure of this invention is simple, flexible, and easy to implement, and the control concept is easy to understand, making it easy to apply and promote in practical engineering.

[0137] This invention also provides a sensorless control method for a permanent magnet synchronous motor, such as... Figure 9 As shown, it includes:

[0138] Step S1: Obtain the desired current value based on the error between the desired rotational speed and the actual rotational speed;

[0139] Step S2: Inject a high-frequency pulse signal into the current loop controller, and output a PWM pulse signal by combining the desired current value and the estimated rotor position;

[0140] Step S3: Speed ​​control of the permanent magnet synchronous motor is performed according to the PWM pulse signal;

[0141] Step S4: Based on the estimated rotor position, convert the three-phase alternating signal in the three-phase stationary coordinate system output by the speed control of the permanent magnet synchronous motor into a current signal in the two-phase rotating coordinate system.

[0142] Step S5: Use a moving average filter to filter the current signal error in the two-phase rotating coordinate system, and obtain the rotor position error based on the filtered current signal error.

[0143] When using a moving average filter to filter the error of the current signal in a two-phase rotating coordinate system, the following two conditions must be met:

[0144]

[0145] ωs =Mω h

[0146] Among them, T ω ω is the window length of the moving average filter. h ω is the frequency of the high-frequency pulse signal. s M is the switching frequency of the inverter, where M is an integer.

[0147] Step S6: Based on the rotor position error, obtain the estimated rotor position and the actual rotor speed to form a closed-loop control.

[0148] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0149] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A sensorless control system for a permanent magnet synchronous motor, characterized in that, include: Speed ​​loop controller, current loop controller, inverter, coordinate transformer, position error observer, and speed observer; The position error observer is an amplitude observer based on a moving average filter; The speed loop controller, current loop controller, inverter, permanent magnet synchronous motor, coordinate transformer, position error observer and speed observer are connected in sequence. The speed observer is also connected to the speed loop controller, current loop controller and coordinate transformer respectively to form a closed loop. The speed loop controller is used to obtain the desired current value based on the error between the desired speed and the actual speed; The current loop controller is used to inject a high-frequency pulsating signal and, using the desired current value and the estimated rotor position, outputs a PWM pulse signal as the control signal for the inverter. Inverters are used to control the speed of permanent magnet synchronous motors based on PWM pulse signals; The coordinate transformer is used to convert the three-phase alternating signal in the three-phase stationary coordinate system output after the speed control of the permanent magnet synchronous motor into a current signal in the two-phase rotating coordinate system based on the estimated rotor position. The position error observer is used to filter the current signal error in the two-phase rotating coordinate system using a moving average filter, and obtain the rotor position error based on the filtered current signal error. The speed observer is used to obtain the estimated rotor position and the actual rotor speed based on the rotor position error. The actual rotor speed is transmitted to the speed loop controller, and the estimated rotor position is transmitted to the current loop controller and the coordinate transformer respectively to form a closed loop control. The position error observer includes: a current signal error calculation module, a moving average filter, and an integrator; The input terminals of the current signal error calculation module are connected to the coordinate transformer and the integrator, respectively, and the output terminal is connected to the moving average filter. The current signal error calculation module is used to obtain the q-axis current signal in a two-phase rotating coordinate system from the coordinate transformer and to obtain the observed high-frequency current amplitude from the integrator. Furthermore, based on the q-axis current signal in the two-phase rotating coordinate system and the observed high-frequency current amplitude... Determine the error of the current signal in a two-phase rotating coordinate system; The moving average filter is connected to the integrator. The moving average filter is used to filter the error of the current signal in the two-phase rotating coordinate system, and the observed high-frequency current amplitude is obtained by compensation through the integrator. .

2. The sensorless control system for permanent magnet synchronous motors according to claim 1, characterized in that, When using a moving average filter to filter the error of the current signal in a two-phase rotating coordinate system, the following two conditions must be met: = M in, This is the window length of the moving average filter. The frequency of the high-frequency pulse signal. This refers to the switching frequency of the inverter. M It is an integer.

3. The sensorless control system for permanent magnet synchronous motors according to claim 2, characterized in that, The time-domain transfer function of the moving average filter is: ;in, For time-domain transfer function, s For complex parameters; The transfer function of the discretized moving average filter is: ;in, , N The ratio, , The sampling period for the current. z For complex parameters; The stopband center frequency of the moving average filter is ;in, The stopband center frequency, It is a positive integer.

4. The sensorless control system for a permanent magnet synchronous motor according to claim 1, characterized in that, The current loop controller includes: a torque component-side PI controller, an excitation component-side PI controller, an inverse Park transform module, and a space vector pulse width modulation module; The torque component-side PI controller is connected to both the speed loop controller and the inverse Parker transformation module. The torque component-side PI controller is used to process the torque component of the desired current value. Perform control to output the desired q-axis voltage; The excitation component-side PI controller is connected to the inverse Parker transformation module. The excitation component-side PI controller is used to control the excitation component of the desired current value. The system controls and outputs the desired d-axis voltage. This desired d-axis voltage is then superimposed with a high-frequency pulsating voltage signal and input to the inverse Parker transformation module. The excitation component of the desired current value... Equal to 0; The inverse Park transformation module is connected to the space vector pulse width modulation module. The inverse Park transformation module is used to convert the expected voltage on the q-axis and the expected voltage on the d-axis after superimposing the high-frequency pulsating voltage signal into voltage components in a two-phase stationary coordinate system based on the estimated rotor position. The space vector pulse width modulation module is connected to the inverter. The space vector pulse width modulation module is used to generate PWM pulse signals based on the voltage components in the two-phase stationary coordinate system using the SVPWM algorithm.

5. The sensorless control system for a permanent magnet synchronous motor according to claim 3, characterized in that, The formula for calculating the current signal error in the two-phase rotating coordinate system is as follows: in, , = - ; The error in the current signal under a two-phase rotating coordinate system. For high-frequency signal components, t For time, q-axis current signal in a two-phase rotating coordinate system and feedback signals The amount of error between them , The amplitude of the fundamental current. The amplitude of the induced current generated by the high-frequency pulsed voltage signal. High-frequency noise generated by inverter switching transistors The amplitude.

6. The sensorless control system for a permanent magnet synchronous motor according to claim 3, characterized in that, The rotational speed observer is an extended state observer; The expression for the extended state observer is: ; in, The first derivative of the rotor position estimate. The first derivative of the estimated electric angular velocity. The first derivative of the estimated value of the uncertain part of the system. , This represents the moment of inertia of the permanent magnet synchronous motor. For extreme logarithms, For load torque, The coefficient of friction, Electric angular velocity, , For mechanical angular velocity, For rotor position estimation error, For electromagnetic torque, , and These are the first, second, and third parameters, respectively. , The damping coefficient is... As an intermediate variable, , This represents the desired bandwidth.

7. The sensorless control system for a permanent magnet synchronous motor according to claim 1, characterized in that, Also includes: First low-pass filter and second low-pass filter; The first low-pass filter is connected to both the coordinate transformer and the current loop controller. The first low-pass filter is used to process the d-axis current signal in a two-phase rotating coordinate system. Filtering is performed to input the fundamental current signal of the d-axis to the current loop controller; The second low-pass filter is connected to both the coordinate transformer and the current loop controller. This second low-pass filter is used to process the q-axis current signal in a two-phase rotating coordinate system. Filtering is performed to input the fundamental current signal of the q-axis to the current loop controller.

8. A sensorless control method for a permanent magnet synchronous motor, characterized in that, The method is applied to a sensorless control system for a permanent magnet synchronous motor as described in claim 1, and the method includes: The desired current value is obtained based on the error between the desired speed and the actual speed. A high-frequency pulse signal is injected into the current loop controller, and a PWM pulse signal is output based on the desired current value and the estimated rotor position. Speed ​​control of permanent magnet synchronous motor is performed based on PWM pulse signal; Based on the estimated rotor position, the three-phase alternating signal output from the three-phase stationary coordinate system after speed control of the permanent magnet synchronous motor is converted into a current signal in a two-phase rotating coordinate system. A moving average filter is used to filter the current signal error in the two-phase rotating coordinate system, and the rotor position error is obtained based on the filtered current signal error. Based on the rotor position error, the estimated rotor position and the actual rotor speed are obtained, forming a closed-loop control.

9. The sensorless control method for a permanent magnet synchronous motor according to claim 8, characterized in that, When using a moving average filter to filter the error of the current signal in a two-phase rotating coordinate system, the following two conditions must be met: = M in, This is the window length of the moving average filter. The frequency of the high-frequency pulse signal. This refers to the switching frequency of the inverter. M It is an integer.

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