A sensorless control method for permanent magnet synchronous motor based on speed loop internal model control

Abstract

The present invention belongs to the field of motor control technology, and specifically is a sensorless control method for a permanent magnet synchronous motor based on speed loop internal model control. The method comprises the following steps: step 1, mathematically modeling a built-in three-phase permanent magnet synchronous motor; step 2, designing a speed loop internal model controller to control the permanent magnet synchronous motor. The present invention uses rotating high-frequency voltage signal injection to perform sensorless motor control, does not require the installation and calibration of sensors, and reduces the possibility of sensor failure. The speed controller in the magnetic field-oriented vector control is improved, and the idea of ​​the internal model controller is introduced to simplify the parameter setting problem, which is convenient for adjusting the controller parameters.

Description

Technical Field

[0001] The invention belongs to the technical field of motor control, and in particular is a sensorless control method for a permanent magnet synchronous motor based on speed loop internal model control. Background Art

[0002] When using magnetic field-oriented vector control, in order to achieve high-performance three-phase permanent magnet synchronous motor control system, it is generally necessary to obtain accurate rotor position and speed information, but mechanical sensors increase system cost and limit the promotion and application of products; mechanical sensors increase motor volume and shaft moment of inertia, reduce motor power density; mechanical sensors are easily interfered by temperature and electromagnetic noise, reducing the operating reliability of the device. There are also some special applications where traditional mechanical position sensors cannot be used at all. Sensorless control technology detects relevant electrical signals in motor windings and uses certain control algorithms to estimate rotor position and speed. By using sensorless control technology of permanent magnet synchronous motor, mechanical sensors can be omitted, simplifying the connection lines between the inverter and the motor, reducing system cost and improving system reliability. At the same time, for magnetic field-oriented vector control, controller design for the speed loop can simplify the number of controller parameter setting problems and reduce the workload of controller debugging. Summary of the invention

[0003] To solve the above problems, the present invention provides a sensorless control method for a permanent magnet synchronous motor based on speed loop internal model control. The method uses rotating high-frequency voltage signal injection to perform sensorless control of the motor. It does not require the installation and calibration of sensors, reducing the possibility of sensor failure. It also improves the speed controller in the magnetic field-oriented vector control, introduces the idea of ​​an internal model controller to simplify the parameter setting problem, and facilitates the adjustment of controller parameters.

[0004] The technical solution of the present invention is described as follows in conjunction with the accompanying drawings:

[0005] A sensorless control method for a permanent magnet synchronous motor based on a speed ring inner model comprises the following steps:

[0006] Step 1: mathematically model the built-in three-phase permanent magnet synchronous motor under fundamental wave and high frequency excitation;

[0007] Step 2: Design a speed loop internal model controller to control the permanent magnet synchronous motor.

[0008] Furthermore, the specific method of step one is as follows:

[0009] 11) Establish the fundamental wave mathematical model of the three-phase permanent magnet synchronous motor as shown below:

[0010]

[0011] In the formula, u d is the d-axis component of the stator voltage; R is the stator resistance; i d is the d-axis component of the stator current; is the d-axis component of the stator flux; ω e is the electrical angular velocity; is the q-axis component of the stator flux; u q is the q-axis component of the stator voltage; i q is the q-axis component of the stator current;

[0012] 12) Establish the stator flux equation as follows:

[0013]

[0014] Where, L d is the d-axis inductance component; is the permanent magnet flux; L q is the q-axis inductance component;

[0015] 13) Combining steps 11) and 12), the voltage equation is changed to the following:

[0016]

[0017] 14) Convert to the stationary coordinate system as follows:

[0018]

[0019] In the formula, i α is the α-axis component of the stator current; i β is the β-axis component of the stator current; is the α-axis component of the stator flux; is the β-axis component of the stator flux; L=(L d +L q ) / 2, is the average inductance; ΔL=(L q -L d ) / 2 is the semi-differential inductance;

[0020] 15) In the stationary coordinate system, define the inductance matrix as follows:

[0021]

[0022] In the formula, θ e is the rotor position angle;

[0023] 16) The equations for the three-phase permanent magnet synchronous motor under high frequency excitation are established as follows:

[0024]

[0025] In the formula, u din is the d-axis component of the stator voltage after high-frequency voltage is injected; u qin is the q-axis component of the stator voltage after high-frequency voltage is injected; i din is the d-axis component of the stator current after high-frequency voltage is injected; i qin is the q-axis component of the stator current after high-frequency voltage is injected;

[0026] 17) Assume that the frequency of the injected high-frequency signal is ω in , the amplitude is V in , then the mathematical expression of the injected high-frequency voltage signal is as follows:

[0027]

[0028] In the formula, u αin is the α-axis component of the stator voltage after high-frequency voltage is injected; u βin is the β-axis component of the stator voltage after high-frequency voltage is injected;

[0029] 18) Convert the injected high-frequency voltage signal to the synchronous rotating coordinate system as follows:

[0030]

[0031] 19) In the synchronous rotating coordinate system, the current response equation of the three-phase permanent magnet synchronous motor injected with high-frequency voltage signal is as follows:

[0032]

[0033] 20) The current response expression of the three-phase permanent magnet synchronous motor in the stationary coordinate system is as follows:

[0034]

[0035] In the formula, i αβin is the α-β axis component of the stator current after high-frequency voltage is injected; I cp is the amplitude of the positive phase sequence high frequency current component, that is, I cn is the amplitude of the negative phase sequence high frequency current component, that is

[0036]

[0037] Furthermore, the specific method of step 2 is as follows:

[0038] 21) Perform Laplace transform on the motor motion equation as shown below:

[0039] Jsω+Bω=K t i q -T L

[0040] Where J is the motor moment of inertia; ω is the motor speed; B is the viscous damping coefficient; K t is the torque coefficient; T L is the load torque;

[0041] 22) The transfer function of the speed loop is as follows:

[0042]

[0043] 23) Select a low-pass filter of order 1 as shown below:

[0044]

[0045] In the formula, α s is the bandwidth of the filter, and the expression of the speed loop internal model controller is:

[0046]

[0047] 24) The feedback control structure equivalent to the internal model control structure is obtained:

[0048]

[0049] 25) Analogy to common PI controller forms:

[0050] The speed loop internal model controller is equivalent to a PI controller, and the parameters are:

[0051] K P =α s J,K i =α s B

[0052] 26) By adjusting the low-pass filter bandwidth α s One parameter enables motor speed control.

[0053] The beneficial effects of the present invention are:

[0054] 1. The present invention adopts rotating high-frequency voltage signal injection to perform sensorless motor control. It does not need to install and calibrate sensors, which reduces the possibility of sensor failure, simplifies system structure, reduces costs and simplifies installation.

[0055] 2. The present invention improves the speed controller in the magnetic field oriented vector control, introduces the idea of ​​internal model controller to simplify the parameter setting problem, and facilitates the adjustment of controller parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0057] Figure 1 It is a structural block diagram of the control system of the present invention;

[0058] Figure 2 This is the simulation model diagram of the synchronous shaft system high-pass filter;

[0059] Figure 3 This is the simulation model diagram of heterodyne method model;

[0060] Figure 4 This is the simulation model diagram of the rotor position tracking observer;

[0061] Figure 5 It is a simulation model diagram of the present invention;

[0062] Figure 6 It is the simulation curve diagram of the estimated speed and the expected value. DETAILED DESCRIPTION

[0063] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0064] Embodiment 1

[0065] This embodiment provides a sensorless control method for a permanent magnet synchronous motor based on a speed loop internal model control, comprising the following steps:

[0066] Step 1: mathematically model the built-in three-phase permanent magnet synchronous motor under fundamental wave and high-frequency excitation, as follows:

[0067] 11) Establish the fundamental wave mathematical model of the three-phase permanent magnet synchronous motor as shown below:

[0068]

[0069] In the formula, u d is the d-axis component of the stator voltage; R is the stator resistance; i d is the d-axis component of the stator current; is the d-axis component of the stator flux; ω e is the electrical angular velocity; is the q-axis component of the stator flux; uq is the q-axis component of the stator voltage; i q is the q-axis component of the stator current;

[0070] 12) Establish the stator flux equation as follows:

[0071]

[0072] Where, L d is the d-axis inductance component; is the permanent magnet flux; L q is the q-axis inductance component;

[0073] 13) Combining steps 11) and 12), the voltage equation is changed to the following:

[0074]

[0075] 14) Convert to the stationary coordinate system as follows:

[0076]

[0077] In the formula, i α is the α-axis component of the stator current; i β is the β-axis component of the stator current; is the α-axis component of the stator flux; is the β-axis component of the stator flux; L=(L d +L q ) / 2, is the average inductance; ΔL=(L q -L d ) / 2 is the semi-differential inductance;

[0078] 15) In the stationary coordinate system, define the inductance matrix as follows:

[0079]

[0080] In the formula, θ e is the rotor position angle;

[0081] 16) The equations for the three-phase permanent magnet synchronous motor under high frequency excitation are established as follows:

[0082]

[0083] In the formula, u αin is the α-axis component of the stator voltage after high-frequency voltage is injected; u βin is the β-axis component of the stator voltage after high-frequency voltage is injected;

[0084] 17) Assume that the frequency of the injected high-frequency signal is ω in , the amplitude is V in, then the mathematical expression of the injected high-frequency voltage signal is as follows:

[0085]

[0086] In the formula, u αin is the α-axis component of the stator voltage after high-frequency voltage is injected; u βin is the β-axis component of the stator voltage after high-frequency voltage is injected;

[0087] 18) Convert the injected high-frequency voltage signal to the synchronous rotating coordinate system as follows:

[0088]

[0089] 19) In the synchronous rotating coordinate system, the current response equation of the three-phase permanent magnet synchronous motor injected with high-frequency voltage signal is as follows:

[0090]

[0091] 20) The current response expression of the three-phase permanent magnet synchronous motor in the stationary coordinate system is as follows:

[0092]

[0093] In the formula, i αβin is the α-β axis component of the stator current after high-frequency voltage is injected; I cp is the amplitude of the positive phase sequence high frequency current component, that is, I cn is the amplitude of the negative phase sequence high frequency current component, that is

[0094]

[0095] Step 2: Based on the mathematical modeling of step 1, a speed loop internal model controller is designed to control the permanent magnet synchronous motor, as follows:

[0096] 21) Perform Laplace transform on the motor motion equation as shown below:

[0097] Jsω+Bω=K t i q -T L

[0098] Where J is the motor moment of inertia; ω is the motor speed; B is the viscous damping coefficient; K t is the torque coefficient; T L is the load torque;

[0099] 22) The transfer function of the speed loop is as follows:

[0100]

[0101] 23) Select a low-pass filter of order 1 as shown below:

[0102]

[0103] In the formula, α s is the bandwidth of the low-pass filter, and the expression of the speed loop internal model controller is:

[0104]

[0105] 24) The feedback control structure equivalent to the internal model control structure is obtained:

[0106]

[0107] 25) Analogy to common PI controller forms:

[0108] The speed loop internal model controller is equivalent to a PI controller, and the parameters are:

[0109] K P =α s J,K i =α s B

[0110] 26) By adjusting the low-pass filter bandwidth α s One parameter enables motor speed control.

[0111] A normal PI controller requires adjusting two parameters, but now only one parameter needs to be adjusted, which effectively reduces the workload.

[0112] Embodiment 2

[0113] A simulation model was built in the MATLAB / Simulink environment to conduct simulation experiments. The motor parameters in the simulation are: pole pair number p n =2; stator inductance L d =5.2mH,L q =17.4mH; stator resistance R = 0.33Ω; moment of inertia J = 0.008kg·m 2 ; Damping coefficient B = 0.0006N·m·s; DC side voltage is 311V; High frequency voltage signal amplitude V in =30V; frequency f of high frequency voltage signal in =1000Hz; the reference speed is set to 500rpm.

[0114] according to Figure 5 Build a simulation architecture, feedback speed curve as follows Figure 6 As shown by Figure 6It can be seen that the response time is 0.04s, which is short. From the image, it can be seen that the desired speed is tracked quickly and stably, which verifies that the present invention is effective.

[0115] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A sensorless control method for a permanent magnet synchronous motor based on speed loop internal model control, characterized in that: The following steps are involved: Step 1: mathematically model the built-in three-phase permanent magnet synchronous motor under fundamental wave and high frequency excitation; Step 2: Design a speed loop internal model controller to control the permanent magnet synchronous motor.

2. According to claim 1, a sensorless control method for a permanent magnet synchronous motor based on speed loop internal model control is characterized in that: The specific method of step one is as follows: 11) Establish the fundamental wave mathematical model of the three-phase permanent magnet synchronous motor as shown below: In the formula, u d is the d-axis component of the stator voltage; R is the stator resistance; i d is the d-axis component of the stator current; is the d-axis component of the stator flux; ω e is the electrical angular velocity; is the q-axis component of the stator flux; u q is the q-axis component of the stator voltage; i q is the q-axis component of the stator current; 12) Establish the stator flux equation as follows: Where, L d is the d-axis inductance component; is the permanent magnet flux; L q is the q-axis inductance component; 13) Combining steps 11) and 12), the voltage equation is changed to the following: 14) Convert to the stationary coordinate system as follows: In the formula, i α is the α-axis component of the stator current; i β is the β-axis component of the stator current; is the α-axis component of the stator flux; is the β-axis component of the stator flux; L=(L d +L q ) / 2, is the average inductance; ΔL=(L q -L d ) / 2 is the semi-differential inductance; 15) In the stationary coordinate system, define the inductance matrix as follows: In the formula, θ e is the rotor position angle; 16) The equations for the three-phase permanent magnet synchronous motor under high frequency excitation are established as follows: In the formula, u din is the d-axis component of the stator voltage after high-frequency voltage is injected; u qin is the q-axis component of the stator voltage after high-frequency voltage is injected; i din is the d-axis component of the stator current after high-frequency voltage is injected; i qin is the q-axis component of the stator current after high-frequency voltage is injected; 17) Assume that the frequency of the injected high-frequency signal is ω in , the amplitude is V in , then the mathematical expression of the injected high-frequency voltage signal is as follows: In the formula, u αin is the α-axis component of the stator voltage after high-frequency voltage is injected; u βin is the β-axis component of the stator voltage after high-frequency voltage is injected; 18) Convert the injected high-frequency voltage signal to the synchronous rotating coordinate system as follows: 19) In the synchronous rotating coordinate system, the current response equation of the three-phase permanent magnet synchronous motor injected with high-frequency voltage signal is as follows: 20) The current response expression of the three-phase permanent magnet synchronous motor in the stationary coordinate system is as follows: In the formula, i αβin is the α-β axis component of the stator current after high-frequency voltage is injected; I cp is the amplitude of the positive phase sequence high frequency current component, that is I cn is the amplitude of the negative phase sequence high frequency current component, that is 3. The sensorless control method of a permanent magnet synchronous motor based on speed loop internal model control according to claim 1 is characterized in that: The specific method of step 2 is as follows: 21) Perform Laplace transform on the motor motion equation as shown below: Jsω+Bω=K t i q -T L Where J is the motor moment of inertia; ω is the motor speed; B is the viscous damping coefficient; K t is the torque coefficient; T L is the load torque; 22) The transfer function of the speed loop is as follows: 23) Select a low-pass filter of order 1 as shown below: In the formula, α s is the bandwidth of the low-pass filter, and the expression of the speed loop internal model controller is: 24) The feedback control structure equivalent to the internal model control structure is obtained: 25) Analogy to common PI controller forms: The speed loop internal model controller is equivalent to a PI controller, and the parameters are: K P =a s J,K i =a s B 26) By adjusting the low-pass filter bandwidth α s One parameter enables motor speed control.

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