A design method of a permanent magnet synchronous motor speed adaptive flux-weakening controller

Abstract

The application discloses a design method of a permanent magnet synchronous motor speed adaptive field weakening controller, and relates to a design method. The application is used to solve the problem that the existing field weakening controller parameter setting needs trial and error. The steps of the application comprise the following steps: step 1, calculating a q-axis voltage reference value and constructing a q-axis voltage closed loop; step 2, designing different types of speed adaptive voltage regulators for different current loop decoupling methods; and step 3, realizing field weakening control through the regulation of the speed adaptive voltage closed loop. The application belongs to the field of permanent magnet synchronous motor field weakening control technology.

Description

TECHNICAL FIELD

[0001] The application relates to a design method and belongs to the technical field of weak magnetic control of permanent magnet synchronous motors. BACKGROUND

[0002] Double closed-loop control is a basic control framework of a permanent magnet synchronous motor, which is composed of an outer speed loop and an inner current loop, and the core is to control three-phase sinusoidal current into two-phase rotating current through coordinate transformation, and finally output inverter switching signals through space vector pulse width modulation (SVPWM). For a permanent magnet synchronous motor requiring weak magnetic control, a voltage loop is often introduced on the basis of the double closed-loop system, that is, weak magnetic control is performed through voltage vector amplitude feedback. For the current loop and the speed loop, since the closed-loop system is a linear system, the transfer function can be directly written to derive the parameter setting method of the corresponding controller, but for the voltage closed loop, the situation is completely different. Figure 1 A schematic diagram of a voltage amplitude feedback weak magnetic control loop, wherein the reference value u s,ref of the voltage regulator is the radius of the inscribed circle of the SVPWM hexagon voltage constraint. u d and u q represent the d-axis voltage and the q-axis voltage, and the feedback value u s of the voltage vector amplitude is written as:

[0003]

[0004] The voltage closed loop method is an effective way to realize weak magnetic operation of a permanent magnet synchronous motor, and has strong parameter robustness and feasibility. However, the nonlinearity of the voltage closed loop worsens the proportional integral (PI) tuning problem, resulting in the lack of PI tuning standards for the voltage regulator. SUMMARY

[0005] The application is to solve the problem of trial-and-error parameter setting of the existing weak magnetic controller, and further proposes a speed adaptive weak magnetic controller design method for a permanent magnet synchronous motor.

[0006] The technical scheme adopted by the application to solve the above problems is that the steps of the application include:

[0007] Step 1, calculating the q-axis voltage reference value and constructing a q-axis voltage closed loop;

[0008] Step 2, designing different types of speed adaptive voltage regulators for different current loop decoupling methods;

[0009] Step 3, realizing weak magnetic control through the regulating action of the speed adaptive voltage closed loop.

[0010] Further, the q-axis voltage u q is used as the feedback of the proposed voltage closed loop, instead of the voltage vector magnitude u s , the purpose is to put the nonlinear calculation in front, its reference value u q,ref is:

[0011]

[0012] In formula (2), u dc represents the DC bus voltage of the inverter, u d represents the d-axis voltage.

[0013] Further, step 2 specifically includes:

[0014] Step 201, the speed adaptive voltage closed loop regulator for non-integral decoupling is designed;

[0015] Step 202, the speed adaptive voltage closed loop regulator for integral decoupling is designed.

[0016] Further, in step 201, for the non-integral decoupling structure, it is assumed that the actual d-axis current can well follow its reference value, that is, i d = i d,ref ; the q-axis voltage u q,PI output by the current PI regulator and the back electromotive force are regarded as disturbance terms, in the analysis of the voltage closed loop, the feedforward decoupling and the feedback decoupling are treated equally, and the open loop transfer function H v,1 (s) of the voltage loop of the non-integral decoupling is written as:

[0017]

[0018] In formula (3), K p,v represents the proportional coefficient of the voltage regulator, K i,v represents the integral coefficient of the voltage regulator, ω e represents the electrical angular velocity of the motor, and L d represents the d-axis inductance of the permanent magnet synchronous motor.

[0019] If the proportional coefficient K p,v is zero, formula (3) is simplified as a pure integral element, and at this time the voltage closed loop transfer function G v,1 (s) is written in the form of a first-order inertia element:

[0020]

[0021] In formula (4), ω v represents the bandwidth of the voltage loop.

[0022] The application discloses a PI tuning method of a non-integral decoupling speed adaptive voltage closed-loop regulator.

[0023]

[0024] Further, the open-loop transfer function H v,2 (s) of the integral decoupling voltage loop in step 202 is written as:

[0025]

[0026] In formula (6), ω c represents the bandwidth of the current loop, and s represents a complex frequency;

[0027] The closed-loop transfer function G v,2 (s) of the integral decoupling speed adaptive voltage closed-loop regulator is obtained.

[0028]

[0029] G v,2 (s) has two poles, the two poles are arranged on a negative real axis equally, and stability is strictly ensured, and the relationship between K p,v and K i,v is expressed as:

[0030]

[0031] Suppose:

[0032]

[0033] The closed-loop transfer function G v,2 (s) is written as:

[0034]

[0035] In formula (10), ω v ' represents a closed-loop pole frequency, and a real bandwidth ω v of the voltage closed loop is calculated through the following formula:

[0036]

[0037] In formula (11), j represents an imaginary unit, the real voltage closed-loop bandwidth is obtained by solving the above formula:

[0038]

[0039] The PI tuning method of the integral decoupling speed adaptive voltage closed-loop regulator is obtained.

[0040]

[0041] The beneficial effects of the present application are:

[0042] 1. The present application solves the problem of controller parameter setting difficulty caused by the nonlinearity of the voltage closed loop in traditional field-oriented control;

[0043] 2. The present application provides a clear design theory, that is, the voltage regulator parameters should have speed self-adaptive properties; on the other hand, it simplifies the parameter setting process, and only needs to select the closed-loop bandwidth artificially to complete the parameter setting of the voltage regulator;

[0044] 3. The present application replaces the traditional voltage vector amplitude closed-loop feedback with q-axis voltage closed-loop feedback, so that the nonlinearity of the voltage closed loop is preposed;

[0045] 4. The present application constructs different voltage closed-loop control block diagrams according to different current loop decoupling branches, thereby designing different speed self-adaptive parameter setting rules;

[0046] 5. The speed self-adaptive field-oriented controller designed by the present application can realize online PI parameter setting only by inputting the desired bandwidth, thereby solving the problem of parameter setting difficulty caused by the nonlinearity of the traditional voltage closed loop. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a voltage amplitude feedback field-oriented control loop schematic diagram;

[0048] Figure 2 is a speed self-adaptive field-oriented control schematic diagram of a permanent magnet synchronous motor;

[0049] Figure 3 is a classification schematic diagram of a classical decoupling method;

[0050] Figure 4 is a speed self-adaptive voltage closed loop block diagram for non-integral type decoupling;

[0051] Figure 5 is a speed self-adaptive voltage closed loop block diagram for integral type decoupling

[0052] Figure 6 is a Bode plot of the transfer function of the voltage closed loop of the integral type decoupling;

[0053] Figure 7 is a speed step experiment result schematic diagram when the voltage loop bandwidth is 50Hz;

[0054] Figure 7 a is a feedforward decoupling schematic diagram, Figure 7 b is a feedback decoupling schematic diagram, Figure 7 c is an internal model decoupling, Figure 7 d is a deviation decoupling schematic diagram;

[0055] Figure 8is the speed step experiment result schematic diagram when the voltage loop bandwidth is 30Hz;

[0056] Figure 8 a is a feedforward decoupling schematic diagram, Figure 8 b is a feedback decoupling schematic diagram, Figure 8 c is an internal mode decoupling schematic diagram, Figure 8 d is a deviation decoupling schematic diagram;

[0057] Figure 9 is the sudden load experiment result when the voltage loop bandwidth is 50Hz;

[0058] Figure 9 a is a feedforward decoupling schematic diagram, Figure 9 b is a feedback decoupling schematic diagram, Figure 9 c is an internal mode decoupling schematic diagram, Figure 9 d is a deviation decoupling schematic diagram;

[0059] Figure 10 is the sudden load experiment result when the voltage loop bandwidth is 30Hz;

[0060] Figure 10 a is a feedforward decoupling schematic diagram, Figure 10 b is a feedback decoupling schematic diagram, Figure 10 c is an internal mode decoupling schematic diagram, Figure 10 d is a deviation decoupling schematic diagram. DETAILED DESCRIPTION

[0061] Embodiment one: as shown, a permanent magnet synchronous motor speed adaptive field weakening controller design method, the specific steps include: Figure 2

[0062] Step 1, calculate the q-axis voltage reference value and build the q-axis voltage closed loop; q-axis voltage u q is used as the feedback of the proposed voltage closed loop, instead of voltage vector amplitude u s , the purpose is to preposition the nonlinear calculation, and its reference value u q,ref is:

[0063]

[0064] In formula (2), u dc represents the DC bus voltage of the inverter, u d represents the d-axis voltage;

[0065] Step 2, design different types of speed adaptive voltage regulators for different current loop decoupling methods;

[0066] ​Step 201, design a speed-adaptive voltage closed-loop regulator for non-integral decoupling; for the non-integral decoupling structure, it is assumed that the actual d-axis current can well follow its reference value, that is, i d d,ref ; the q-axis voltage u q,PI output by the current PI regulator and the back electromotive force are regarded as disturbance terms, in the analysis of the voltage closed loop, the feedforward decoupling and the feedback decoupling are treated equally, and the open-loop transfer function H v,1 (s) of the voltage loop of the non-integral decoupling is written as:

[0067]

[0068] In formula (3), K p,v represents the proportional coefficient of the voltage regulator, K i,v represents the integral coefficient of the voltage regulator, ω e represents the electrical angular velocity of the motor, and L d represents the d-axis inductance of the permanent magnet synchronous motor.

[0069] If the proportional coefficient K p,v is zero, formula (3) is simplified as a pure integral element, and the voltage closed-loop transfer function G v,1 (s) is written in the form of a first-order inertia element:

[0070]

[0071] In formula (4), ω v represents the bandwidth of the voltage loop.

[0072] A PI tuning method of the speed-adaptive voltage closed-loop regulator of the non-integral decoupling is obtained, and specifically:

[0073]

[0074] Step 202, design a speed-adaptive voltage closed-loop regulator for integral decoupling; the open-loop transfer function H v,2 (s) of the voltage loop of the integral decoupling is written as:

[0075]

[0076] In formula (6), ω c represents the bandwidth of the current loop, and s represents the complex frequency.

[0077] The closed-loop transfer function G v,2 (s) is:

[0078]

[0079] G v,2 ​(s) has two poles, two poles are equally configured on the negative real axis, and strictly guarantee stability, K p,v and K i,v The relationship is expressed as:

[0080]

[0081] Assume:

[0082]

[0083] The closed-loop transfer function G v,2 (s) is written as:

[0084]

[0085] In formula (10), ω v ′ represents the closed-loop pole frequency, and the real bandwidth ω v of the voltage loop is calculated by the following formula:

[0086]

[0087] In formula (11), j represents the imaginary unit, and by solving the above formula, the real voltage loop bandwidth is obtained:

[0088]

[0089] The PI tuning method of the speed-adaptive voltage closed-loop regulator with integral decoupling is obtained:

[0090]

[0091] Step 3, realize the field weakening control through the regulating effect of the speed-adaptive voltage closed-loop;

[0092] The function of the voltage loop is: when the voltage vector amplitude reaches the voltage limit, if the speed needs to be further increased, the d-axis current needs to be reduced, and the field weakening principle is as formula (14):

[0093]

[0094] Among them, as shown in Figure 3 , four classical decoupling methods are divided into two categories according to whether the decoupling branch contains integral: the first category is that the decoupling branch does not contain integral operation, including feedforward decoupling and feedback decoupling; the second category is that the decoupling branch contains integral operation, including internal model decoupling and deviation decoupling;

[0095] The reason for such classification is that the same type of decoupling method has the same structure in the analytical design of the voltage closed loop, so the same type of current decoupling can use the same speed adaptive voltage regulator parameter setting method; different speed adaptive voltage regulators are designed for different decoupling types, and according to the frequency domain analysis, it can be deduced that the PI parameters of the proposed method have speed adaptive characteristics, which is in line with common sense, because as the motor speed increases, the d-axis current change rate of the field weakening controller output will decrease.

[0096] In step 201, for the non-integral type decoupling structure, it is assumed that the actual d-axis current can well follow its reference value, that is, i d d,ref ; the q-axis voltage u q,PI output by the current PI regulator and the back electromotive force are regarded as disturbance terms. Then, in the analysis of the voltage closed loop, the feedforward decoupling and the feedback decoupling are treated equally.

[0097] Experimental results

[0098] The proposed control method is experimentally verified. The actual three-phase permanent magnet synchronous motor is used to verify the experimental platform, the motor rated voltage is 380V, the rated power is 2.2kW, and the current loop bandwidth is 300Hz.

[0099] Figure 7 and Figure 8 The speed step experiment results under different bandwidths and decoupling structures are shown, the speed is expressed in per unit, the base value is 2000r / min (1.0p.u.), and the experiment is carried out in the field weakening region. The experimental results verify the feasibility of the proposed voltage regulator PI setting method, and with the decrease of the bandwidth, the current rapidity and overshoot of the dynamic process will decrease at the same time.

[0100] Figure 9 and Figure 10 The sudden load experiment results under different bandwidths and decoupling structures are shown, the initial speed of the load experiment is 2400r / min (1.2p.u.), and the experiment is also carried out in the field weakening region. According to the experimental results, with the decrease of the bandwidth, the rapidity and overshoot will decrease, the larger the bandwidth, the better the dynamic response to the sudden load, and the experimental results are consistent with the theoretical expectation.

[0101] Through the speed step and sudden load experiments, it is easy to verify the feasibility of the proposed voltage loop PI regulator design method.

[0102] ​The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the technical solution of the present application, can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not deviate from the technical solution of the present application, and is within the spirit and principle of the present application, any simple modification, equivalent replacement and improvement of the above embodiments are still within the protection scope of the technical solution of the present application.

Claims

1. A design method of a permanent magnet synchronous motor speed adaptive flux-weakening controller, characterized in that, The specific steps include: Step 1, calculation axis voltage reference value and construct axis voltage closed loop; q axis voltage u q used as the feedback of the proposed voltage closed loop, instead of the voltage vector amplitude u s The purpose is to put the nonlinear calculation in front, and its reference value u q,ref is: （2）， In equation (2), u dc represents the inverter DC bus voltage, represents shaft voltage; Step 2, design different types of speed adaptive voltage regulators for different current loop decoupling methods; Step 3, realize field weakening control through the regulating effect of the speed adaptive voltage closed loop.

2. The method of claim 1, wherein the method further comprises: Step 2 specifically includes: Step 201, design a speed adaptive voltage closed loop regulator for non-integral type decoupling; Step 202, design a speed adaptive voltage closed loop regulator for integral type decoupling.

3. The method of claim 2, wherein the method further comprises: For non-integral decoupling structure in step 201, it is assumed that: actual d The shaft current can well follow its reference value, i.e. i d = i d,ref ; the current PI regulator output q The shaft voltage u q,PI and back electromotive force are regarded as disturbance terms, in the analysis of the voltage closed loop, feedforward decoupling and feedback decoupling are treated equally, and the open-loop transfer function of the voltage loop of the non-integral decoupling H v,1 ( s ) is written as: （3）， In formula (3), K p,v represents a proportional coefficient of the voltage regulator, K i,v represents an integral coefficient of the voltage regulator, ω e represents an electrical angular velocity of the motor, L d represents a d-axis inductance of the permanent magnet synchronous motor, d axial inductance; If the proportional coefficient K p,v is zero, then equation (3) simplifies to a pure integration term, in which case the voltage closed-loop transfer function G v,1 ( s ) is written in the form of a first-order inertial term: （4）， In equation (4), ω v denotes the bandwidth of the voltage loop; A PI tuning method for a non-integral type decoupled speed adaptive voltage closed loop regulator is obtained, specifically: （5）。 4. The method of claim 2, wherein the method further comprises: The open loop transfer function of the integrator decoupled voltage loop in step 202 H v,2 ( s ) is written as: （6）， In equation (6), ω c denotes the bandwidth of the current loop, denotes the complex frequency; The closed loop transfer function of this is obtained G v,2 ( s ) is: （7）， G v,2 ( s ) have two poles, the two poles are equally configured on the negative real axis, and the stability is strictly guaranteed, K p,v and K i,v The relationship is expressed as: （8）， Assume: （9）， Closed loop transfer function G v,2 ( s ) is written as: （10）， In equation (10), represents the closed-loop pole frequency, the real bandwidth of the voltage loop ω v is calculated by the following equation: （11）， In equation (11), denotes the imaginary unit, and solving the above equation gives the real voltage closed-loop bandwidth: （12）， A PI tuning method for an integral type decoupled speed adaptive voltage closed loop regulator is obtained: （13）。

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