A structure and parameter design method of current PI controller for hybrid excitation synchronous motor

Abstract

The present invention discloses a current PI controller structure and parameter calculation method of a hybrid excitation synchronous motor, belonging to the field of hybrid excitation synchronous motors. A coupled PI controller structure with feedforward, the parameters of the controller are adjusted by using the zero-pole cancellation method for the transfer function matrix of the reduced-order hybrid excitation synchronous motor model; the problem that the traditional PI current controller cannot realize the current decoupling control of the hybrid excitation synchronous motor, the model is not fully utilized, and the adjustment performance is poor; the problem that the controller has many parameters to be designed and difficult to adjust is also solved; the hybrid excitation synchronous motor current PI controller based on the present invention can realize the complete decoupling control of the hybrid excitation synchronous motor current, and the parameter design is simple and reliable.

Description

Technical Field

[0001] The invention relates to the field of hybrid excitation synchronous motors, and in particular to a current PI controller structure and a parameter design method for a hybrid excitation synchronous motor. Background Art

[0002] Permanent magnet synchronous motors are widely used in the field of AC drives due to their high power density, high torque density and excellent dynamic performance. However, traditional permanent magnet synchronous motors are limited in their operating area due to difficulties in magnetic field regulation and the risk of permanent magnet demagnetization. Hybrid excitation synchronous motors introduce electrical excitation into traditional permanent magnet synchronous motors, and their magnetic field regulation is convenient and reliable, making them very suitable for wide speed range applications such as aerospace, electric vehicles, etc.

[0003] The dual closed-loop vector control method based on the synchronous rotating coordinate system is widely used in the field of motor drive control. The control response of the current inner loop directly affects the speed regulation performance of the motor drive system. The proportional integral (PI) controller is still the main choice for industrial motor controllers due to its simple structure and easy implementation. The appropriate PI controller parameters determine the current loop regulation performance, and its parameter tuning method has been widely studied. Among them, the zero-pole cancellation method is a PI controller parameter tuning algorithm. It treats the motor back electromotive force as an outer loop disturbance and equates the motor model to a first-order resistive inductive load. After obtaining the closed-loop function of the controller and the controlled motor in series, the PI controller parameters are adjusted by selecting the system bandwidth with the purpose of adjusting the system to a first-order stable system. The design process is simple and effective.

[0004] The traditional PI controller can effectively meet the current regulation requirements of permanent magnet synchronous motors, but it is insufficient for the current regulation capability of high-order, strongly coupled hybrid excitation synchronous motor systems, because it cannot offset the system poles caused by the coupling of armature current and excitation current in the hybrid excitation motor, which leads to poor current regulation and anti-interference performance. At the same time, due to the increase in the dimension of the controlled current of the hybrid excitation synchronous motor, the current controller has many parameters to be designed and is difficult to adjust. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention proposes a current PI controller structure and a parameter design method for a hybrid excitation synchronous motor.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A current PI controller structure of a hybrid excitation synchronous motor, comprising:

[0008] The error e between the reference current and the actual sampling current is output as a voltage given u * , the voltage given by u * :

[0009]

[0010] Among them, u * d ,u * q , Respectively represent the d-axis, q-axis and excitation voltage setting; e d , e q , e f Respectively represent the difference between the d-axis, q-axis and excitation current setting and sampling, A is the error calculation matrix, and D is the feedforward compensation vector;

[0011] The feedforward calculation part D is used to decouple the back EMF disturbance caused by speed fluctuation, and its mathematical expression is as follows:

[0012] D=[-ω e L q i q ω e (ψ f +L d i d +Mi f ) 0] T

[0013] Among them, ω e represents the electrical angular velocity of the synchronous rotating coordinate system, L d , L q , M represents the d-axis, q-axis inductance and hybrid excitation mutual inductance, i d ,i q ,i f Represent the d-axis, q-axis current and excitation current, ψ f represents permanent magnet flux, T is the vector transpose sign;

[0014] Error calculation part A·e's q-axis calculation output u * q Only by e q Direct calculation can be obtained, the d-axis calculation output u * d and excitation voltage calculation output By e d and e f The coupling calculation is performed.

[0015] Optionally, the q-axis calculation output u * q , for input e q Multiplying with the PI controller, the d-axis calculates the output u * d For input e d Multiply the PI controller and the excitation current error ef K pfd The excitation voltage is calculated and output For input e f Multiply the PI controller and the d-axis current error e d K pdf The sum of times; its mathematical form is shown as follows:

[0016]

[0017] Among them, K pd , K pq , K pf Represents the PI controller proportional coefficients of the d-axis, q-axis and excitation current, K id , K iq , K if Represents the PI controller integral coefficients of the d-axis, q-axis and excitation current, K pfd , K pdf They represent the coupling proportional coefficients of the excitation current to the d-axis current and the d-axis current to the excitation current respectively, and s is the Laplace operator.

[0018] A method for calculating parameters of a current PI controller of a hybrid excitation synchronous motor comprises the following steps:

[0019] Step 1: Use the traditional zero-pole cancellation method to complete the q-axis current controller K pq and K iq The design result can be directly obtained from the system target control bandwidth f and motor parameters, and its mathematical form is as follows:

[0020]

[0021] Among them, R s is the armature winding resistance;

[0022] Step 2: Write the motor frequency domain model G, ignoring the back EMF and q-axis voltage equations and only including the d-axis and excitation voltage equations. M The invented PI controller frequency domain model G PI , its mathematical expression is as follows:

[0023]

[0024]

[0025] Among them, i and u represent the current vector output and the voltage vector input of the motor respectively, R f , L f are the field winding resistance and self-inductance respectively;

[0026] Step 3: The PI controller is used in conjunction with the motor model G obtained in step 2. M The series open-loop transfer function matrix G open , its mathematical expression is as follows:

[0027]

[0028] Among them, G 11_open ,G 12_open ,G 21_open ,G 22_open Represent the open-loop transfer function matrix G open The transfer function components at the corresponding positions in ;

[0029] Step 4: Write out the closed-loop transfer function matrix obtained in step 3. Its mathematical expression is as follows:

[0030]

[0031] in:

[0032]

[0033]

[0034]

[0035]

[0036] Step 5: Based on the closed-loop transfer function matrix G obtained in step 4 close , select the appropriate transfer function in the matrix and complete the calculation of the remaining parameters with the goal of tuning the system to a first-order system.

[0037] Optionally, the target transfer function selected in step 5 is G 11 and G 22 , the setting process is as follows:

[0038] Step 5-1, take the first-order system as the tuning target, the system needs to offset two sets of zero poles, and write the target transfer function G accordingly * 11 and G * 22 :

[0039]

[0040]

[0041] Among them, x 1 and x 2 They represent the pole positions of the first-order system of the tuning target;

[0042] Step 5-2, expand the target transfer function G in step 1 * 11 and G * 22 , using the method of undetermined coefficients and G 11 and G 22 Comparison of various coefficients, the comparison results show that A d , A f are the controller parameter tuning coefficient matrices for the d-axis current and the excitation current, respectively. The remaining parameter design should satisfy the following equations:

[0043]

[0044] in:

[0045]

[0046]

[0047] Step 5-3, based on the parameters calculated in step 2, the required bandwidth of the system is selected to complete the design. The result is:

[0048]

[0049] Among them, A -1 d , A -1 f Represents A d , A f The inverse matrix of .

[0050] A computer-readable storage medium stores instructions, which can implement the calculation method when executed.

[0051] Beneficial effects of the present invention:

[0052] Compared with the conventional PI current control of the existing hybrid excitation synchronous motor, the present invention has the following beneficial effects:

[0053] 1. The present invention makes full use of the particularity of the hybrid excitation motor model. The proposed PI controller structure adds a d-axis current and excitation current coupling ratio link, which can achieve complete decoupling of the d-axis current and the excitation current, and improve the dynamic regulation performance of the d-axis current and the excitation current.

[0054] 2. The PI controller proposed in the present invention is combined with feedforward compensation to achieve complete decoupling of the back-EMF term, thereby improving the current loop control performance of the hybrid excitation synchronous motor and the performance of resisting speed fluctuations.

[0055] 3. The parameter tuning method of the PI controller proposed in the present invention aims to tune the target transfer function to a first-order system, selects the target bandwidth to complete the parameter design, and provides a reference for the design of a total of 8 parameters of the proposed controller, solving the problem that the PI current control design of the hybrid excitation synchronous motor has many parameters and is difficult and blind to tune. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention will be further described below in conjunction with the accompanying drawings.

[0057] Figure 1 1. It is a schematic diagram comparing the structure of the excitation synchronous motor PI current controller of the present invention with the structure of the traditional PI controller;

[0058] Figure 2 It is the block diagram of PI current control of hybrid excitation synchronous motor;

[0059] Figure 3 It is a parameter setting process of the hybrid excitation synchronous motor PI current controller of the present invention;

[0060] Figure 4 It is the current response simulation result of the traditional PI current control;

[0061] Figure 5 It is the current response simulation result of the hybrid excitation synchronous motor PI current control of the present invention. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Figure 1 This is a comparison diagram between a hybrid excitation synchronous motor PI current controller structure of the present invention and a traditional PI controller structure. The left figure is a traditional PI current controller, in which the q-axis, d-axis and excitation current control are independent of each other, and the current coupling term is regarded as a disturbance; although the structure is simple, it is difficult to obtain good current decoupling control performance in the hybrid excitation synchronous motor drive system; the right figure is a hybrid excitation synchronous motor PI current controller structure of the present invention, in which the input is the error e between the reference current and the actual sampled current, and the output is the voltage given u * , which is calculated by the sum of the feedforward calculation part D and the error calculation part A·e, and its mathematical form is as follows:

[0064]

[0065] Among them, u* d ,u * q , Respectively represent the d-axis, q-axis and excitation voltage setting; e d , e q , e f Respectively represent the difference between the d-axis, q-axis and excitation current setting and sampling, A is the error calculation matrix, and D is the feedforward compensation vector;

[0066] Feedforward calculation part D

[0067] like Figure 1 As shown in the figure, the feedforward calculation part is used to decouple the back EMF disturbance caused by speed fluctuation, and its mathematical expression is as follows:

[0068] D=[-ω e L q i q ω e (ψ f +L d i d +Mi f ) 0] T

[0069] Among them, ω e represents the electrical angular velocity of the synchronous rotating coordinate system, L d , L q , M represents the d-axis, q-axis inductance and hybrid excitation mutual inductance, i d ,i q ,i f Represent the d-axis, q-axis current and excitation current, ψ f represents permanent magnetic flux linkage;

[0070] Error calculation part A·e,

[0071] like Figure 1 As shown, the q-axis calculates the output u * q For input e q Multiplying with the PI controller, the d-axis calculates the output u * d For input e d Multiply the PI controller and the excitation current error e f K pfd The excitation voltage is calculated and output For input e f Multiply the PI controller and the d-axis current error e d K pdf The sum of times; its mathematical form is shown as follows:

[0072]

[0073] Among them, K pd , K pq , K pf Represents the PI controller proportional coefficients of the d-axis, q-axis and excitation current, K id , K iq , K if Represents the PI controller integral coefficients of the d-axis, q-axis and excitation current, K pfd , K pdf They represent the coupling proportionality coefficients of the excitation current to the d-axis current and the d-axis current to the excitation current, respectively, and s is the Laplace operator

[0074] Figure 2 It is a block diagram of PI current control of hybrid excitation synchronous motor. Compared with the traditional PI vector control link, the present invention is characterized in that the hybrid excitation synchronous motor PI current controller replaces the traditional PI current controller, which is composed of a hybrid excitation synchronous motor, a three-phase inverter, a buck-boost chopper circuit, an SVPWM modulation module, an excitation current PWM generation module, a sampling circuit, a hybrid excitation synchronous motor current PI controller, Clarke coordinate transformation, Park coordinate transformation, and inverse Park coordinate transformation. First, the motor current information is obtained through the sampling circuit, and it and the given current error are sent to the invented PI controller. The dq axis voltage outputted by the hybrid excitation synchronous motor PI current controller is obtained through inverse Park transformation and space voltage vector pulse width modulation to obtain the on-off signal for controlling the power device of the three-phase inverter, and the i f The voltage setting is used to obtain the on-off signal of the buck-boost chopper circuit through the excitation current PWM generation module, and finally drives the hybrid excitation synchronous motor to operate.

[0075] Figure 3 The present invention is a hybrid excitation synchronous motor PI current controller parameter tuning process, the two parameters of the q-axis current PI controller are designed using the traditional zero-pole cancellation method, but the six parameters of the d-axis and excitation current PI controllers are obtained by tuning the transfer function using a reduced-order two-dimensional state space transfer function matrix. The specific steps are as follows:

[0076] Step 1: Use the traditional zero-pole cancellation method to complete the q-axis current controller K pq and K iq The design result can be directly obtained from the system target control bandwidth f and motor parameters, and its mathematical form is as follows:

[0077]

[0078] Among them, R s is the armature winding resistance;

[0079] Step 2: Write the motor frequency domain model G, ignoring the back EMF and q-axis voltage equations and only including the d-axis and excitation voltage equations. M The invented PI controller frequency domain model G PI ; First, the complete mathematical model of the hybrid excitation synchronous motor is as follows:

[0080]

[0081] Ignoring the back EMF and q-axis voltage equation, the motor model considering only the d-axis and excitation voltage equation is:

[0082]

[0083] The reduced-order transfer function matrix of the hybrid excitation synchronous motor and the PI controller transfer function matrix are as follows:

[0084]

[0085]

[0086] Among them, i and u represent the current vector output and the voltage vector input of the motor respectively, R f , L f are the field winding resistance and self-inductance respectively;

[0087] Step 3: Write out the PI controller and the motor model G obtained in step 2 M The series open-loop transfer function matrix G open , its mathematical expression is as follows:

[0088]

[0089] Step 4: Write out the closed-loop transfer function matrix obtained in step 3. Its mathematical expression is as follows:

[0090]

[0091] in:

[0092]

[0093]

[0094]

[0095]

[0096] Step 5: Based on the closed-loop transfer function matrix G obtained in step 4 close , the target transfer function selected is G 11 and G 22, the setting process is as follows:

[0097] Step 5.1, take the first-order system as the tuning target, the system needs to offset two sets of zero poles, and write the target transfer function G accordingly * 11 and G * 22 :

[0098]

[0099]

[0100] Among them, x 1 and x 2 They represent the pole positions of the first-order system of the tuning target;

[0101] Step 5.2, expand the target transfer function G in step 1 * 11 and G * 22 , using the method of undetermined coefficients and G 11 and G 22 Comparing the coefficients, we can find that the remaining parameter design should satisfy the following equations:

[0102]

[0103] in:

[0104]

[0105]

[0106] Step 5.3, according to the parameters calculated in step 2, the required bandwidth of the system is selected to complete the design. The result is:

[0107]

[0108] Among them, A -1 d , A -1 f Represents A d , A f The inverse matrix of

[0109] In order to verify the effectiveness of the hybrid excitation synchronous motor PI current controller and parameter design method proposed in the present invention, a simulation platform based on Simulink was established.

[0110] Figure 4The current control effect of the traditional PI controller in the hybrid excitation synchronous motor system. The motor is running as a generator, and its waveforms show the d-axis current, q-axis current, excitation current and speed respectively. It can be seen from the figure that the d-axis current is adjusted in a step at 0.1s. Due to the coupling between the d-axis current and the excitation current, a disturbance with a peak value of 0.97A is caused at the excitation current, which will produce a large impulse process for the motor when running at high speed. Similarly, the excitation current is adjusted in a step at 0.15s, which causes a disturbance at the d-axis current, and the current peak reaches 3.2A. In addition, the speed is adjusted in a step at 0.2s. It can be seen that due to the coupling of the permanent magnet flux and the dq-axis current, a disturbance of about 0.93A is caused at the q-axis, which lasts for a long time and the current regulation is slow, which will cause fluctuations in the motor output torque. It can be seen that the traditional PI cannot achieve the decoupling of the current control of the hybrid excitation synchronous motor, and the anti-disturbance performance is poor.

[0111] Figure 5 The current control effect of the PI controller of the present invention in the hybrid excitation synchronous motor system is shown. The motor is running for power generation, and its waveforms respectively show the d-axis current, q-axis current, excitation current and speed. It can be seen from the figure that the d-axis current is step-regulated at 0.1s, and the excitation current is maintained at 0.01A with almost no disturbance. Similarly, the excitation current is step-regulated at 0.15s, and the d-axis current is almost unaffected. In addition, the speed is step-regulated at 0.2s. Due to the feedforward compensation link in the proposed controller, the q-axis current disturbance peak is reduced to 0.25A, the duration is short, and the current is adjusted quickly. It can be seen that the hybrid excitation synchronous motor current PI controller of the present invention can achieve complete decoupling of the hybrid excitation synchronous motor current control, with strong anti-interference performance and rapid adjustment. At the same time, it reflects the effectiveness and reliability of the hybrid excitation synchronous motor PI current controller parameter design method of the present invention.

[0112] In some examples of the present invention, a computer-readable storage medium is also involved, which stores instructions. When the instructions are executed, the controller parameter calculation method described in the above embodiment can be implemented. More specifically, the instructions can be a computer-readable language. The above-mentioned computer can be a general-purpose computer device or a special-purpose computer device. In a specific implementation, the computer can be a desktop, a portable computer, a network server, a PDA (Personal Digital Assistant), a mobile phone, a tablet computer, a wireless terminal device, a communication device or an embedded device. The storage medium can be any available medium that can be accessed by the computer or a data storage device such as a server or a data center that includes one or more available media integrated. For example, the storage medium is, for example, but not limited to, a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a digital versatile disc (Digital Versatile Disc, DVD)), or a semiconductor medium (for example, a solid-state drive (SSD)), etc.

[0113] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0114] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A current PI controller for a hybrid excitation synchronous motor, characterized in that: include: The error e between the reference current and the actual sampling current is output as a voltage given u ＊ , the voltage given by u ＊ : Among them, u ＊ d ,u ＊ q ,u ＊ f Respectively represent the d-axis, q-axis and excitation voltage setting; e d , e q , e f Respectively represent the difference between the d-axis, q-axis and excitation current setting and sampling, A is the error calculation matrix, and D is the feedforward compensation vector; The feedforward compensation vector D is used to decouple the back electromotive force disturbance caused by the speed fluctuation, and its mathematical expression is as follows: D=[-ω e L q i q ω e (ψ f +L d i d +Mi f ) 0] T Among them, ω e represents the electrical angular velocity of the synchronous rotating coordinate system, L d , L q , M represents the d-axis, q-axis inductance and hybrid excitation mutual inductance, i d ,i q ,i f Represent the d-axis, q-axis current and excitation current, ψ f represents permanent magnet flux, T is the vector transpose sign; Error calculation part A·e's q-axis calculation output u ＊ q Only by e q Direct calculation can be obtained, the d-axis calculation output u ＊ d And the excitation voltage is calculated to output u ＊ f By e d and e f The coupling calculation is performed.

2. The current PI controller of the hybrid excitation synchronous motor according to claim 1, characterized in that: The q-axis calculation output u ＊ q , for input e q Multiplying with the PI controller, the d-axis calculates the output u ＊ d For input e d Multiply the PI controller and the excitation current error e f K pfd The excitation voltage is calculated and outputted as u ＊ f For input e f Multiply the PI controller and the d-axis current error e d K pdf The sum of times; its mathematical form is shown as follows: Among them, K pd , K pq , K pf Represents the PI controller proportional coefficients of the d-axis, q-axis and excitation current, K id , K iq , K if Represents the PI controller integral coefficients of the d-axis, q-axis and excitation current, K pfd , K pdf They represent the coupling proportional coefficients of the excitation current to the d-axis current and the d-axis current to the excitation current respectively, and s is the Laplace operator.

3. A method for calculating the parameters of a current PI controller of a hybrid excitation synchronous motor, characterized in that: The following steps are involved: Step 1: Use the traditional zero-pole cancellation method to complete the q-axis current controller K pq and K iq The design result can be directly obtained from the system target control bandwidth f and motor parameters, and its mathematical form is as follows: Among them, R s is the armature winding resistance; Step 2: Write the motor frequency domain model G, ignoring the back EMF and q-axis voltage equations and only including the d-axis and excitation voltage equations. M The invented PI controller frequency domain model G PI , its mathematical expression is as follows: Among them, i and u represent the current vector output and the voltage vector input of the motor respectively, R f , L f are the field winding resistance and self-inductance respectively; Step 3: The PI controller is used in conjunction with the motor model G obtained in step 2. M The series open-loop transfer function matrix G open , its mathematical expression is as follows: Among them, G 11_open ,G 12_open ,G 21_open ,G 22_open Represent the open-loop transfer function matrix G open The transfer function components at the corresponding positions in ; Step 4: Write out the closed-loop transfer function matrix obtained in step 3. Its mathematical expression is as follows: in: Step 5: Based on the closed-loop transfer function matrix G obtained in step 4 close , select the appropriate transfer function in the matrix and complete the calculation of the remaining parameters with the goal of tuning the system to a first-order system.

4. The method for calculating the current PI controller parameters of a hybrid excitation synchronous motor according to claim 3, characterized in that: The target transfer function selected in step 5 is G 11 and G 22 , the setting process includes the following steps: Step 5-1, take the first-order system as the tuning target, the system needs to offset two sets of zero poles, and write the target transfer function G accordingly ＊ 11 and G ＊ 22 : Among them, x1 and x2 represent the pole positions of the first-order system of the tuning target; Step 5-2, expand the target transfer function G in step 1 ＊ 11 and G ＊ 22 , using the method of undetermined coefficients and G 11 and G 22 Comparison of various coefficients, the comparison results show that A d , A f The controller parameter tuning coefficient matrices are the d-axis current and the excitation current, respectively. The remaining parameter design should satisfy the following equations: in: Step 5-3, based on the parameters calculated in step 2, the required bandwidth of the system is selected to complete the design. The result is: Among them, A -1 d , A -1 f Represents A d , A f The inverse matrix of .

5. A computer-readable storage medium storing instructions, which, when executed, can implement the calculation method described in claim 3 or 4.

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