Control method and system for permanent magnet synchronous motor system powered by current source inverter

Abstract

This invention discloses a control method and system for a current-source inverter-powered permanent magnet synchronous motor (PMSM) system, belonging to the field of PMSM control. Utilizing the state variable information of the PMSM system control system sampled at time k, the discrete state-space equation of the dq-axis current-source inverter-powered PMSM system is established. A filter capacitor voltage estimator is designed to obtain the estimated value of the filter capacitor voltage. A feedback-integral controller is designed to solve for the dq-axis inverter output current control command. The three optimal current vectors closest to the inverter output current control command are selected, and the optimal current vector and optimal duty cycle are calculated. The optimal switching pulse sequence is then applied to the switching transistors of the current-source inverter to achieve current control of the current-source inverter-powered PMSM system. This method offers high control accuracy and fast dynamic response.

Description

Technical Field

[0001] This invention relates to a control method and system for a current source inverter-powered permanent magnet synchronous motor system, and relates to the field of motor control. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are high-performance AC motors with compact structures and high power density, widely used in aerospace, new energy vehicles, and robotics industries. Conventional PMSM drive systems employ a voltage source inverter topology, with a large-capacity capacitor connected in parallel on the DC side of the inverter as a voltage regulator. Failure of this capacitor can easily lead to a short circuit. Another mainstream inverter topology is the current source inverter, which uses a large-capacity inductor connected in series on the DC side to achieve constant current and provides excellent short-circuit protection to prevent damage to the motor. Therefore, current source inverter-powered PMSM systems have promising application prospects. Since the output-side filter capacitor of the current source inverter and the motor stator inductance constitute a second-order capacitive-inductor (CL) filter, it can naturally filter out high-order harmonics. However, if the filter capacitor and the motor stator inductance are mismatched, the second-order CL filter may cause resonance problems, leading to system instability.

[0003] Currently, to address the CL resonance instability problem in permanent magnet synchronous motor (PMSM) systems powered by current source inverters, existing methods primarily employ damping control strategies, including passive damping and active damping control. Passive damping uses physical resistors connected in series or parallel within the circuit to suppress CL resonance, but this increases power loss and reduces system efficiency. Active damping adds one or more state variables to the damping control loop to suppress CL resonance spikes. Traditional control methods often employ a multi-loop proportional-integral (PI) cascaded control architecture with capacitor voltage feedback to achieve current control and resonance damping, but this requires the introduction of additional cross-coupling compensation loops for decoupling. This presents a contradiction between high steady-state performance and fast dynamic response, making it difficult to meet the high dynamic response requirements of PMSMs. Furthermore, traditional control methods require sampling multiple capacitor voltages and stator currents, resulting in a large number of sensors and high hardware costs, significantly hindering their engineering applications.

[0004] The prior art disclosed in CN118944520A describes a control method for a permanent magnet synchronous motor system with an LC filter. This invention calculates the cutoff frequency of the LC low-pass filter for the permanent magnet synchronous motor based on the inductance and capacitance values ​​of the pre-selected LC low-pass filter. Then, based on the cutoff frequency, appropriate software band-stop filter parameters are selected to filter out the resonant current on the inverter output current. The inverter output current after filtering is approximately equal to the phase current of the motor. This is then incorporated into the motor model calculation. The motor control mathematical model adopts a current model. Because the inverter output voltage is generated through PWM modulation but without output voltage sampling, the current model has relatively low requirements for output voltage accuracy, resulting in lower control precision and response speed. Summary of the Invention

[0005] To address the limitations of existing technologies, this invention provides a control method and system for a current-source inverter-powered permanent magnet synchronous motor (PMSM) system. By establishing the discrete-space state equations of the current-source inverter-powered PMSM system, a high-gain capacitor voltage estimator and an inverter output current control command based on stator current reference tracking error feedback-integral control are designed. The optimal current vector closest to the inverter output current control command is selected, and the optimal duty cycle that can track the inverter output current control command error-free within one sampling period is calculated. An optimal vector sequence is generated to achieve current control. This invention is simple to implement, offers high control freedom, effectively improves the accuracy, stability, and dynamic response speed of current control, and reduces hardware costs.

[0006] To achieve the above technical objectives, the present invention provides a control method for a current source inverter-powered permanent magnet synchronous motor system, comprising the following steps:

[0007] S1. Use sensors to sample the state variable information of the permanent magnet synchronous motor system powered by the current source inverter at time k, and convert it into dq axis state variable information through Park transformation.

[0008] S2. Based on the dq axis state variable information and the zero-order hold discretization method, establish the discrete state space equation of the permanent magnet synchronous motor system powered by the current source inverter, and construct a filter capacitor voltage estimator based on the high-gain feedback estimation principle to calculate the estimated value of the filter capacitor voltage.

[0009] S3. Based on the estimated value of the filter capacitor voltage and the dq axis state variable information, construct the inverter output current control command based on multivariable feedback-integral control;

[0010] S4. Obtain the spatial position angle of the inverter output current control command, and select the three optimal current vectors closest to the inverter output current control command.

[0011] S5. Based on the principle that the inverter output current control command tracking error is zero within a sampling period, the optimal action time corresponding to the three optimal current vectors is calculated.

[0012] S6. Generate an optimal vector sequence based on the three optimal current vectors and their optimal action time, and apply it to the switching transistors of the current source inverter to achieve high-precision, high-dynamic response, and strong-stability current control for the permanent magnet synchronous motor system powered by the current source inverter.

[0013] Furthermore, the current-source inverter-powered permanent magnet synchronous motor system includes sequentially connected DC power supplies V dc DC bus inductance L d The system consists of a three-phase current source inverter, a filter capacitor C, and a permanent magnet synchronous motor. The system's state variables, including the three-phase inverter output current i, are sampled at time k using sensors. f,abc The stator current i of the permanent magnet synchronous motor s,abc The encoder is used to calculate the electrical angle θ of the permanent magnet synchronous motor rotor in real time. e and electric angular velocity ω e The speed loop uses a proportional-integral (PI) controller, and the parameters of the speed loop are tuned according to the type II system; the rotor electrical angular velocity is referenced to ω. e,ref With feedback ω e The error is used as the input to the speed loop PI regulator to generate the stator current reference value. The sampled three-phase state variable information is transformed into dq-axis state variable information using the Park transform: inverter output current. and stator current , where i fd and i fq These are the d-axis and q-axis components of the inverter output current, i sd and i sq These are the d-axis and q-axis components of the stator current.

[0014] Furthermore, the discrete state-space equations of the current-source inverter-powered permanent magnet synchronous motor system, established based on the dq-axis state variable information and the zero-order hold discretization method, are as follows:

[0015] ;

[0016] The coefficient matrices are represented as follows:

[0017] ;

[0018] ;

[0019] In the formula, This represents the state matrix consisting of the filter capacitor voltage and the stator current at time k+1. This represents the state matrix consisting of the filter capacitor voltage and the stator current at time k. Let A be the inverter output current matrix at time k; d B d D d It is the coefficient matrix of the discrete state-space equations obtained by the zero-order hold discretization method, where A, B, and D are the coefficient matrices of the corresponding continuous state equations; e is the base of the natural logarithm, and T... s The sampling period is This represents the state x of a continuous system at time k when discretized. k State x at time k+1 k+1 The transition matrix, Represents the input transformation integral matrix; ω e Here, C represents the electric angular velocity of the motor, C represents the filter capacitor, L represents the stator inductance of the motor, and ψ represents the electric angular velocity of the motor. f ω represents the flux linkage of the permanent magnet in the motor. e ψ f Represents the back electromotive force of the motor;

[0020] Based on the discrete state-space equations and utilizing the high-gain feedback estimation principle, a filter capacitor voltage estimator is designed as follows:

[0021] ;

[0022] In the formula, This represents the state estimation matrix composed of the estimated values ​​of the filter capacitor voltage and the stator current at time k+1. This represents the state estimation matrix composed of the estimated values ​​of the filter capacitor voltage and the stator current at time k. Here is the gain matrix of the filter capacitor voltage estimator, where l1 and l2 are chosen as the sampling frequency f. s =1 / T s To obtain high-gain feedback on the voltage estimation error of the filter capacitor.

[0023] Furthermore, based on the estimated value of the filter capacitor voltage obtained from the filter capacitor voltage estimator and the dq-axis state variable information, an inverter output current control command based on multivariable feedback-integral control is constructed. This command includes two parts: multivariable feedback control for suppressing resonance and integral control for eliminating steady-state error. The specific expressions are as follows:

[0024] ;

[0025] Among them, the stator current reference tracking error integral variable Represented as:

[0026] ;

[0027] In the formula, i f,ref (k) represents the inverter output current control command at time k. This represents the multivariable feedback state matrix composed of the estimated value of the filter capacitor voltage, the sampled value of the stator current, and the sampled value of the inverter output current at time k. For multivariable feedback gain matrix, Let k be the integral gain matrix, where k c k represents the feedback gain estimated by the filter capacitor voltage. s k represents the stator current feedback gain. i k represents the inverter output current feedback gain. I The integral gain representing the stator current reference error is selected using the pole placement method; i i (k) represents the stator current reference tracking error integral variable at time k, i i (k-1) represents the integral variable of the stator current reference tracking error at time k-1, i s,ref (k) represents the reference value of the stator current at time k.

[0028] Furthermore, the spatial position angle δ is obtained based on the inverter output current control command as follows:

[0029] ;

[0030] In the formula, i fα,ref (k) and i fαβ,ref (k) represent the inverter output current control command i f,ref (k) The α-axis and β-axis components obtained by the inverse dq transform;

[0031] According to the inverter output current control command i f,ref (k) spatial position angle δ, choose distance i f,ref (k) The two nearest non-zero current vectors and one zero current vector are taken as the three optimal current vectors.

[0032] Furthermore, based on the principle that the inverter output current control command tracking error is zero within one sampling period, the following equation is obtained:

[0033] ;

[0034] The optimal action times corresponding to the three optimal current vectors are calculated from the above formula as follows:

[0035] ;

[0036] in,

[0037] ;

[0038] In the formula, t i t j t0 and t0 represent non-zero vectors I and I, respectively. i Non-zero vector I j And the duration of action of the zero vector I0, i d,ref and i q,ref These represent the d-axis and q-axis components of the inverter output current control command, respectively. i,d and I i,q Representing non-zero vectors I respectively i The d-axis and q-axis components, I j,d and I j,q Representing non-zero vectors I respectively j The d-axis and q-axis components, I 0,d and I 0,q Let x represent the d-axis component and q-axis component of the zero vector I0, respectively. i and x j They represent the current vector I respectively. i The d-axis and q-axis components of the error in the inverter output current control command are tracked. i and y j They represent the current vector I respectively. j The d-axis and q-axis components of the inverter output current control command error are tracked, where x0 and y0 represent the current vector I0 and the d-axis and q-axis components of the inverter output current control command error, respectively.

[0039] Furthermore, the optimal vector sequence generated based on the three optimal current vectors and their optimal application times is as follows:

[0040] ;

[0041] In the formula, I seq It is the optimal vector sequence, which is obtained by applying three optimal current vectors in sequence according to the non-zero and zero current vectors;

[0042] By applying the optimal vector sequence to the switching transistors of the current source inverter, high-precision, high-dynamic-response, and highly stable current control is achieved for the permanent magnet synchronous motor system powered by the current source inverter.

[0043] A control system for a current source inverter-powered permanent magnet synchronous motor system includes a sensor unit, a Park conversion unit, a filter capacitor voltage estimator, a multivariable feedback-integral control unit, three optimal current appropriate selection units, an optimal action time calculation unit, and an optimal appropriate sequence unit.

[0044] The sensor unit is used to sample the state variable information of the current source inverter-powered permanent magnet synchronous motor system at time k;

[0045] The Park transformation unit is used to convert state variable information into dq axis state variable information through the Park transformation.

[0046] A filter capacitor voltage estimator is used to calculate the estimated value of the filter capacitor voltage.

[0047] Multivariable feedback-integral control unit, used for multivariable feedback control to suppress resonance, and integral control to eliminate steady-state error;

[0048] The three optimal current vector selection units obtain the two non-zero current vectors and one zero current vector closest to the inverter output current control command as the three optimal current vectors based on the spatial position angle of the inverter output current control command.

[0049] The optimal action time calculation unit calculates the optimal action time corresponding to the three optimal current vectors based on the principle that the inverter output current control command tracking error is zero within one sampling period.

[0050] The optimal vector sequence unit is used to generate an optimal vector sequence based on three optimal current vectors and their optimal application time.

[0051] A computer device includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute a current control method for a current source inverter-powered permanent magnet synchronous motor system.

[0052] A computer-readable storage medium storing a computer program adapted to be loaded and executed by a processor for a current control method of a current source inverter-powered permanent magnet synchronous motor system.

[0053] Beneficial Effects: This invention improves the current control accuracy and stability of synchronous motor systems powered by current source inverters by solving for the inverter output current control command based on the control of three variables: the output current of the current source inverter, the voltage of the filter capacitor, and the stator current of the motor. Furthermore, this invention calculates the current vector action time based on the principle that the tracking error of the inverter output current control command is zero within one sampling period, enabling the inverter output current to track the control command within one sampling period, thus achieving a faster dynamic response. In addition, the implementation of this invention only requires sampling the stator current and the output current of the current source inverter, without needing to sample the filter capacitor voltage, reducing the use of voltage sensors and significantly lowering hardware costs. Attached Figure Description

[0054] Figure 1This is a schematic diagram of the control method for a current source inverter-powered permanent magnet synchronous motor system according to the present invention.

[0055] Figure 2 The steady-state waveforms of capacitor voltage and stator current under the current control method of the embodiment of the present invention are shown.

[0056] Figure 3 This is a schematic diagram of the steady-state harmonic spectrum of the stator current corresponding to the method in the embodiment of the present invention;

[0057] Figure 4 The steady-state waveforms of capacitor voltage and stator current under the traditional multi-loop PI control method with capacitor voltage feedback are shown.

[0058] Figure 5 This is a schematic diagram of the steady-state harmonic spectrum of the stator current corresponding to the multi-loop PI control method using traditional capacitor voltage feedback;

[0059] Figure 6 The dynamic response waveform of the dq-axis stator current under the current control method provided by the present invention;

[0060] Figure 7 The image shows the dynamic response waveform of the dq-axis stator current under the traditional capacitor voltage feedback multi-loop PI control method. Detailed Implementation

[0061] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0062] like Figure 1 As shown, in the current source inverter-powered permanent magnet synchronous motor system of the present invention, the DC input power supply voltage is output as a constant current through an inductor, and then converted into an AC current square wave signal by a three-phase current source inverter. After being filtered by an output capacitor, the signal is connected to the permanent magnet synchronous motor.

[0063] Figure 1 In the middle, V dc L represents the DC input power supply voltage. d This represents the DC-side inductance, with L and C representing the motor stator inductance and the inverter output-side filter capacitor, respectively. The inverter output current is collected sequentially. Three-phase stator current of permanent magnet synchronous motor and the electric angle of rotation of the motor θ e The information, d / dt, represents the derivative element used to calculate the rotor's electric angular velocity ω. e Using Park transformation and the electrical rotation angle θ of the motor e The sampled three-phase state variable information i f,abc and i s,abc Transformed into dq-axis state variable information: Inverter output current and stator current The estimated value of the filter capacitor voltage is calculated as input to the filter capacitor voltage estimator. The speed loop uses a proportional-integral (PI) controller, and the parameters of the speed loop are tuned according to the type II system; the rotor electrical angular velocity is referenced to ω. e,ref With feedback ω e The error is used as the input to the speed loop PI regulator to generate the stator current reference value. The inner loop employs a multivariable feedback-integral controller, using the stator current reference value... Inverter output current Stator current and capacitor voltage estimate As its input, the inverter output current control command i is generated. f,ref (k); The optimal vector sequence is generated after optimal vector selection and optimal action time calculation and applied to the three-phase current source inverter.

[0064] A control method for a current-source inverter-powered permanent magnet synchronous motor system specifically includes the following steps:

[0065] Step 1: Sample the state variable information of the permanent magnet synchronous motor system powered by the current source inverter: three-phase inverter output current i f,abc The stator current i of the permanent magnet synchronous motor s,abc The encoder is used to calculate the electrical angle θ of the permanent magnet synchronous motor rotor in real time. e and electric angular velocity ω e The speed loop uses a proportional-integral (PI) controller, and the parameters of the speed loop are tuned according to the type II system; the rotor electrical angular velocity is referenced to ω. e,ref With feedback ω e The error is used as the input to the speed loop PI regulator to generate the stator current reference value. The sampled three-phase state variable information is transformed into dq-axis state variable information using the Park transform: inverter output current. and stator current , where i fd and i fq These are the d-axis and q-axis components of the inverter output current, i sd and i sq These are the d-axis and q-axis components of the stator current.

[0066] Step 2: Based on the sampled state variable information, the discrete state-space equations of the current source inverter-powered permanent magnet synchronous motor system are established using the zero-order hold discretization method as follows:

[0067] ;

[0068] The coefficient matrices are represented as follows:

[0069] ;

[0070] ;

[0071] In the formula, This represents the state matrix consisting of the filter capacitor voltage and the stator current at time k+1. This represents the state matrix consisting of the filter capacitor voltage and the stator current at time k. Let A be the inverter output current matrix at time k; d B d D d It is the coefficient matrix of the discrete state-space equations obtained by the zero-order hold discretization method, where A, B, and D are the coefficient matrices of the corresponding continuous state equations; e is the base of the natural logarithm, and T... s The sampling period is This represents the state x of a continuous system at time k when discretized. k State x at time k+1 k+1 The transition matrix, Represents the input transformation integral matrix; ω e Here, C represents the electric angular velocity of the motor, C represents the filter capacitor, L represents the stator inductance of the motor, and ψ represents the electric angular velocity of the motor. f ω represents the flux linkage of the permanent magnet in the motor. e ψ f Represents the back electromotive force of the motor;

[0072] Secondly, based on the discrete state-space equations and utilizing the high-gain feedback estimation principle, a filter capacitor voltage estimator is designed as follows:

[0073] ;

[0074] In the formula, This represents the state estimation matrix composed of the estimated values ​​of the filter capacitor voltage and the stator current at time k+1. This represents the state estimation matrix composed of the estimated values ​​of the filter capacitor voltage and the stator current at time k. Here is the gain matrix of the filter capacitor voltage estimator, where l1 and l2 are chosen as the sampling frequency f. s =1 / T s To obtain high-gain feedback on the estimation error of the filter capacitor voltage, the estimator obtains the estimated value of the capacitor voltage by sampling the stator current information, and corrects the model by feeding back the stator current output error, thereby achieving an asymptotic estimation of the internal state of the system.

[0075] Step 3: Calculate the inverter output current control command based on the estimated value of the filter capacitor voltage and the sampled state variable information;

[0076] Design an inverter output current control command based on multivariable feedback-integral control, comprising two parts: multivariable feedback control for suppressing resonance and integral control for eliminating steady-state error. The specific expression is as follows:

[0077] ;

[0078] Among them, the stator current reference tracking error integral variable Represented as:

[0079] ;

[0080] In the formula, i f,ref (k) represents the inverter output current control command at time k. This represents the multivariable feedback state matrix composed of the estimated value of the filter capacitor voltage, the sampled value of the stator current, and the sampled value of the inverter output current at time k. For multivariable feedback gain matrix, Let k be the integral gain matrix. c k represents the feedback gain estimated by the filter capacitor voltage. s k represents the stator current feedback gain. i k represents the inverter output current feedback gain. I The integral gain representing the stator current reference error is selected using the pole placement method; i i (k) represents the stator current reference tracking error integral variable at time k, i i (k-1) represents the integral variable of the stator current reference tracking error at time k-1, i s,ref (k) represents the reference value of the stator current at time k.

[0081] Step 4: Transform the inverter output current control command into the αβ coordinate system and select the three current vectors closest to the control command as the optimal current vectors;

[0082] The spatial position angle δ of the inverter output current control command is calculated as follows:

[0083] ;

[0084] In the formula, i fα,ref and i fαβ,ref These represent the inverter output current control command i. f,ref (k) The α-axis and β-axis components obtained by the inverse dq transform;

[0085] According to the inverter output current control command if,ref (k) spatial position angle δ, choose distance i f,ref (k) The two most recent non-zero current vectors and one zero current vector are taken as the three optimal current vectors, and the specific correspondence is shown in Table 1:

[0086] Table 1

[0087] ,

[0088] In the table, and (i and j∈{1, 2, 3, 4, 5, 6}) represent two non-zero current vectors of the current source inverter. This represents a zero-current vector for a current-source inverter.

[0089] Step 5: Achieve zero-error tracking of the inverter output current to the inverter output current control command within one sampling period, and calculate the optimal action time corresponding to the current vector;

[0090] Based on the principle that the inverter output current control command tracking error is zero within one sampling period, the following equation can be obtained:

[0091] ;

[0092] The optimal action time corresponding to the three optimal current vectors can be calculated from the above formula as follows:

[0093] ;

[0094] in,

[0095] ;

[0096] In the formula, t i t j t0 and t0 represent two non-zero vectors I, respectively. i I j And the action time of a zero vector I0, i d,ref and i q,ref These represent the d-axis and q-axis components of the inverter output current control command, respectively. i,d and I i,q Representing non-zero vectors I respectively i The d-axis and q-axis components, I j,d and I j,q Representing non-zero vectors I respectively j The d-axis and q-axis components, I 0,d and I 0,q Let x represent the d-axis component and q-axis component of the zero vector I0, respectively.i and x j They represent the current vector I respectively. i The d-axis and q-axis components of the error in the inverter output current control command are tracked. i and y j They represent the current vector I respectively. j The d-axis and q-axis components of the inverter output current control command error are tracked, where x0 and y0 represent the current vector I0 and the d-axis and q-axis components of the inverter output current control command error, respectively.

[0097] Step 6: The optimal vector sequence generated based on the three optimal current vectors and their optimal application times is as follows:

[0098] ;

[0099] In the formula, I seq It is the optimal vector sequence, which is obtained by applying three optimal current vectors in sequence according to the non-zero and zero current vectors;

[0100] By applying the optimal vector sequence to the switching transistors of the current source inverter, high-precision, high-dynamic-response, and highly stable current control can be achieved for the permanent magnet synchronous motor system powered by the current source inverter.

[0101] To verify the current control method for a current source inverter-powered permanent magnet synchronous motor system provided by the present invention, the method provided by the present invention was applied to a current source inverter-powered permanent magnet synchronous motor, and the system parameters are given in Table 2.

[0102] Table 2

[0103] .

[0104] Figure 2 The steady-state waveforms of capacitor voltage and stator current under the current control method provided by this invention are shown. Figure 3 This is a schematic diagram of the corresponding stator current steady-state harmonic spectrum; Figure 4 The image shows the steady-state waveforms of capacitor voltage and stator current under a traditional multi-loop PI control method with capacitor voltage feedback. Figure 5 This is a schematic diagram of the corresponding stator current steady-state harmonic spectrum. The speed reference is set at 1000 rpm, and the motor is operating under rated load. From Figure 2 and Figure 4 As can be seen, the stator current and capacitor voltage waveforms are close to sine waves, exhibiting excellent steady-state performance and no resonant oscillation phenomenon, indicating that this method can also achieve good resonance suppression effect; from Figure 3 and Figure 5As can be seen, compared with the traditional multi-loop PI control method based on capacitor voltage feedback, the method provided by this invention has a relatively small total harmonic distortion (THD) of the stator current, and the percentage of harmonics near the resonant frequency relative to the fundamental frequency is reduced by 0.4%. This is because the method of this invention controls the stator current, inverter output current, and filter capacitor voltage, thus possessing higher current control accuracy and stronger stability. Therefore, the current control method provided by this invention can effectively suppress resonance and improve steady-state performance.

[0105] Figure 6 The diagram shows the dynamic response waveform of the dq-axis stator current under the current control method provided by this invention. Figure 7 This is a dynamic response waveform of the stator current on the dq axis using a traditional capacitor voltage feedback multi-loop PI control method. The motor is set to operate under rated load, with an initial speed of 500 rpm. The speed increases from 500 rpm to 1000 rpm in 0.2 seconds, and decreases from 1000 rpm to 500 rpm in 0.3 seconds. (Comparison) Figure 6 and Figure 7 It is known that the dynamic response time of the current control method provided by this invention is approximately 1 ms, while the dynamic response time of the traditional capacitor voltage feedback multi-loop PI method is approximately 3 ms. Comparatively, the method of this invention has a higher dynamic response speed because it can achieve zero-error tracking of the inverter output current control command within one sampling period. Therefore, the current control method provided by this invention possesses a high dynamic response speed, and at the same time, the ripple of the dq-axis stator current is smaller, which further proves that the steady-state control accuracy of the method of this invention is higher.

Claims

1. A control method for a current-source inverter-powered permanent magnet synchronous motor system, characterized in that, Includes the following steps: S1. Use sensors to sample the state variable information of the permanent magnet synchronous motor system at time k, and convert it into dq axis state variable information through Park transformation; S2. Based on the dq axis state variable information and the zero-order hold discretization method, establish the discrete state space equation of the permanent magnet synchronous motor system powered by the current source inverter, and construct a filter capacitor voltage estimator based on the high-gain feedback estimation principle to calculate the estimated value of the filter capacitor voltage. S3. Based on the estimated value of the filter capacitor voltage and the dq axis state variable information, construct the inverter output current control command based on multivariable feedback-integral control; S4. Obtain the spatial position angle of the inverter output current control command, and select the three optimal current vectors closest to the inverter output current control command. S5. Based on the principle that the inverter output current control command tracking error is zero within a sampling period, the optimal action time corresponding to the three optimal current vectors is calculated. S6. Generate an optimal vector sequence based on the three optimal current vectors and their optimal action time, and apply it to the switching transistor of the current source inverter to achieve high-precision, high-dynamic response and strong stability current control for the permanent magnet synchronous motor system powered by the current source inverter. A current-source inverter-powered permanent magnet synchronous motor system includes a DC power supply V connected in sequence. dc DC bus inductance L d The system consists of a three-phase current source inverter, a filter capacitor C, and a permanent magnet synchronous motor. The system's state variables, including the three-phase inverter output current i, are sampled at time k using sensors. f,abc The stator current i of the permanent magnet synchronous motor s,abc The encoder is used to calculate the electrical angle θ of the permanent magnet synchronous motor rotor in real time. e and electric angular velocity ω e The speed loop uses a proportional-integral (PI) controller, and the parameters of the speed loop are tuned according to the type II system; the rotor electrical angular velocity is referenced to ω. e,ref With feedback ω e The error is used as the input to the speed loop PI regulator to generate the stator current reference value. The sampled three-phase state variable information is transformed into dq-axis state variable information using the Park transform: inverter output current. and stator current , where i fd and i fq These are the d-axis and q-axis components of the inverter output current, i sd and i sq These are the d-axis and q-axis components of the stator current; The key feature is that the discrete state-space equations of the current-source inverter-powered permanent magnet synchronous motor system, established based on the dq-axis state variable information and the zero-order hold discretization method, are as follows: ； The coefficient matrices are represented as follows: ； ； In the formula, This represents the state matrix consisting of the filter capacitor voltage and the stator current at time k+1. This represents the state matrix consisting of the filter capacitor voltage and the stator current at time k. Let A be the inverter output current matrix at time k; d B d D d It is the coefficient matrix of the discrete state-space equations obtained by the zero-order hold discretization method, where A, B, and D are the coefficient matrices of the corresponding continuous state equations; e is the base of the natural logarithm, and T... s The sampling period is This represents the state x of a continuous system at time k when discretized. k State x at time k+1 k+1 The transition matrix, Represents the input transformation integral matrix; ω e Here, C represents the electric angular velocity of the motor, C represents the filter capacitor, L represents the stator inductance of the motor, and ψ represents the electric angular velocity of the motor. f ω represents the flux linkage of the permanent magnet in the motor. e ψ f Represents the back electromotive force of the motor; Based on the discrete state-space equations and utilizing the high-gain feedback estimation principle, a filter capacitor voltage estimator is designed as follows: ； In the formula, This represents the state estimation matrix composed of the estimated values ​​of the filter capacitor voltage and the stator current at time k+1. This represents the state estimation matrix composed of the estimated values ​​of the filter capacitor voltage and the stator current at time k. Here is the gain matrix of the filter capacitor voltage estimator, where l1 and l2 are chosen as the sampling frequency f. s =1 / T s To obtain high-gain feedback on the voltage estimation error of the filter capacitor.

2. The control method for a current source inverter-powered permanent magnet synchronous motor system according to claim 1, characterized in that, Based on the estimated value of the filter capacitor voltage obtained from the filter capacitor voltage estimator and the dq axis state variable information, an inverter output current control command based on multivariable feedback-integral control is constructed. This command includes two parts: multivariable feedback control for suppressing resonance and integral control for eliminating steady-state error. The specific expression is as follows: ； Among them, the stator current reference tracking error integral variable Represented as: ； In the formula, i f,ref (k) represents the inverter output current control command at time k. This represents the multivariable feedback state matrix composed of the estimated value of the filter capacitor voltage, the sampled value of the stator current, and the sampled value of the inverter output current at time k. For multivariable feedback gain matrix, Let k be the integral gain matrix, where k c k represents the feedback gain estimated by the filter capacitor voltage. s k represents the stator current feedback gain. i k represents the inverter output current feedback gain. I The integral gain representing the stator current reference error is selected using the pole placement method; i i (k) represents the stator current reference tracking error integral variable at time k, i i (k-1) represents the integral variable of the stator current reference tracking error at time k-1, i s,ref (k) represents the reference value of the stator current at time k.

3. The control method for a current source inverter-powered permanent magnet synchronous motor system according to claim 2, characterized in that, The spatial position angle δ is obtained based on the inverter output current control command as follows: ； In the formula, i fα,ref (k) and i fαβ,ref (k) represent the inverter output current control command i f,ref (k) The α-axis and β-axis components obtained by the inverse dq transform; According to the inverter output current control command i f,ref (k) spatial position angle δ, choose distance i f,ref (k) The two nearest non-zero current vectors and one zero current vector are taken as the three optimal current vectors.

4. The control method for a current source inverter-powered permanent magnet synchronous motor system according to claim 3, characterized in that, Based on the principle that the inverter output current control command tracking error is zero within one sampling period, the following equation is obtained: ； The optimal action times corresponding to the three optimal current vectors are calculated from the above formula as follows: ； in, ； In the formula, t i t j t0 and t0 represent non-zero vectors I and I, respectively. i Non-zero vector I j And the duration of action of the zero vector I0, i d,ref and i q,ref These represent the d-axis and q-axis components of the inverter output current control command, respectively. i,d and I i,q Representing non-zero vectors I respectively i The d-axis and q-axis components, I j,d and I j,q Representing non-zero vectors I respectively j The d-axis and q-axis components, I 0,d and I 0,q Let x represent the d-axis component and q-axis component of the zero vector I0, respectively. i and x j They represent the current vector I respectively. i The d-axis and q-axis components of the error in the inverter output current control command are tracked. i and y j They represent the current vector I respectively. j The d-axis and q-axis components of the inverter output current control command error are tracked, where x0 and y0 represent the current vector I0 and the d-axis and q-axis components of the inverter output current control command error, respectively.

5. The control method for a current source inverter-powered permanent magnet synchronous motor system according to claim 4, characterized in that, The optimal vector sequence generated based on the three optimal current vectors and their optimal application times is as follows: ； In the formula, I seq It is the optimal vector sequence, which is obtained by applying three optimal current vectors in sequence according to the non-zero and zero current vectors; By applying the optimal vector sequence to the switching transistors of the current source inverter, high-precision, high-dynamic-response, and highly stable current control is achieved for the permanent magnet synchronous motor system powered by the current source inverter.

6. A control system for a current source inverter-powered permanent magnet synchronous motor system, characterized in that: It includes a sensor unit, a Park transformation unit, a filter capacitor voltage estimator, a multivariable feedback-integral control unit, three optimal current appropriate selection units, an optimal action time calculation unit, and an optimal appropriate sequence unit; The sensor unit is used to sample the state variable information of the current source inverter-powered permanent magnet synchronous motor system at time k; The Park transformation unit is used to convert state variable information into dq axis state variable information through the Park transformation. A filter capacitor voltage estimator is used to calculate the estimated value of the filter capacitor voltage. Multivariable feedback-integral control unit, used for multivariable feedback control to suppress resonance, and integral control to eliminate steady-state error; The three optimal current vector selection units obtain the two non-zero current vectors and one zero current vector closest to the inverter output current control command as the three optimal current vectors based on the spatial position angle of the inverter output current control command. The optimal action time calculation unit calculates the optimal action time corresponding to the three optimal current vectors based on the principle that the inverter output current control command tracking error is zero within one sampling period. The optimal vector sequence unit is used to generate an optimal vector sequence based on three optimal current vectors and their optimal application time.

7. A computer device, characterized in that, It includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute the control method for a current source inverter-powered permanent magnet synchronous motor system as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program adapted to be loaded by a processor and executed by the control method for a current source inverter-powered permanent magnet synchronous motor system according to any one of claims 1-5.

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