Robust predictive current control method for synchronous motors based on adaptive synchronous space vector modulation

Abstract

The present invention discloses a robust predictive current control method for a synchronous motor adapted to synchronous space vector modulation, belonging to the field of motor operation control, and comprising the following steps: S1, updating the disturbance voltage estimate at the previous sampling moment; S2, calculating the disturbance voltage estimate at the current sampling moment and predicting the observed value of the synchronous motor stator current at the next sampling moment; S3, calculating the voltage drop of the synchronous motor stator winding at the next sampling moment and calculating the observed value of the disturbance voltage at the next sampling moment; S4, mapping the motor command phase to discrete sampling points preset by the SSVM; S5, aligning the voltage command with the sampling points of the SSVM; S6, generating a voltage command; and S7, obtaining an SSVM pulse. The robust predictive current control method for a synchronous motor adapted to synchronous space vector modulation can adapt to changes in the sampling interval of the SSVM under low carrier ratio operating conditions and has extremely fast current tracking response and phase synchronization speed.

Description

Technical Field

[0001] The present invention relates to the technical field of motor operation control, and in particular to a synchronous motor robust predictive current control method adapted to synchronous space vector modulation. Background Art

[0002] In high-power and high-speed permanent magnet synchronous motor (PMSM) drive systems, inverters typically operate under low-carrier-to-current (CCR) conditions. Synchronous space vector modulation (SSVM) is a well-suited modulation method for these conditions, due to its advantages such as low current harmonics, absence of current ripple at sampling points, and ability to generate drive pulses online and in real time. However, the SSVM sampling interval can vary significantly during dynamic phase synchronization or mode switching. Traditional control strategies, typically designed with a fixed control period, struggle to adapt to these large sampling interval variations. Consequently, SSVM-based control systems suffer from slow phase synchronization and poor current loop dynamic performance.

[0003] Existing solutions often employ complex vector digital current regulators, particularly under low carrier ratio conditions. To maintain system stability margins despite large control delays, the current loop bandwidth is limited to a low level, resulting in a slower system dynamic response. Furthermore, to ensure the inverter can output the symmetrical voltage pulses required by the SSVM during quasi-steady-state operation, the controller's voltage phase must be consistent with the SSVM's preset sampling position. However, during dynamic operation, the controller may arbitrarily adjust the voltage command amplitude and phase as needed to eliminate current tracking errors, potentially leading to deviations between the voltage command phase and the SSVM's preset sampling point.

[0004] To address these issues, existing literature has proposed several control step adjustment methods based on phase-locked loops (PLLs) or error feedforward to achieve phase compensation. However, to avoid adversely affecting the current loop, these methods are often limited in their phase synchronization speed, making them incapable of meeting the requirements for fast dynamic response. Meanwhile, deadbeat predictive current control (DPCC) has attracted considerable attention due to its simple principle and fast dynamic response.

[0005] However, traditional DPCC is sensitive to motor parameters and external disturbances. When motor parameters deviate from their nominal values, steady-state tracking errors can occur. To improve the parameter robustness of DPCC, existing literature widely employs disturbance observers for compensation. However, traditional DPCC and its disturbance compensation observers are typically designed based on a fixed control period. Therefore, when the SSVM requires significant adjustments to the sampling interval to switch modulation modes or eliminate phase errors, the system may experience large current surges, which can affect overall performance. Summary of the Invention

[0006] The purpose of the present invention is to provide a synchronous motor robust predictive current control method adapted to synchronous space vector modulation to solve the above technical problems.

[0007] To achieve the above object, the present invention provides a method for robust predictive current control of a synchronous motor adapted to synchronous space vector modulation, comprising the following steps:

[0008] S1. Estimate the disturbance voltage deviation according to the current observation error at the current sampling moment, and update the disturbance voltage estimation value at the previous sampling moment based on the estimated disturbance voltage deviation;

[0009] S2. Based on the disturbance voltage estimation value at the previous sampling moment obtained in step S1, the disturbance voltage estimation value at the current sampling moment is calculated, and based on the disturbance voltage estimation value at the current sampling moment, the synchronous motor stator current observation value at the next sampling moment is predicted to compensate for the digital delay;

[0010] S3. Based on the synchronous motor stator current observation value at the next sampling moment obtained in step S2, the voltage drop of the synchronous motor stator winding at the next sampling moment is calculated, and based on the disturbance voltage estimation value at the current sampling moment obtained in step S2, the disturbance voltage observation value at the next sampling moment is calculated;

[0011] S4. Based on the voltage drop and disturbance voltage observation values ​​of the synchronous motor stator winding at the next sampling moment obtained in step S3, predict the voltage command phase at the next sampling moment, and calculate the preset sampling position adjacent to the voltage command phase at the next sampling moment, so as to map the motor command phase to the discrete sampling points preset by the SSVM;

[0012] S5. Based on the voltage command phase calculated in step S4 and the preset sampling position, the sampling interval of the control cycle at the next sampling moment is calculated, so that the voltage command is aligned with the sampling point of the SSVM by adjusting the control cycle to avoid phase deviation;

[0013] S6. Generate a voltage command based on the sampling interval of the control cycle at the next sampling moment calculated in step S5;

[0014] S7. Based on the voltage command obtained in step S6, the duty cycle of each basic voltage vector is calculated to obtain the SSVM pulse.

[0015] Preferably, in step S1, the estimation formula of the disturbance voltage deviation is:

[0016]

[0017] Where, represents the disturbance voltage deviation at the k-1 sampling moment; λ1 represents the error feedback gain of the observer; j represents the imaginary unit; represents the sampling interval of k-1 sampling moments; ω e Indicates the electrical speed of the synchronous motor rotor; and represent the current observation errors at the k-1 sampling moment and the current sampling moment k, respectively, and represents the synchronous motor stator current value at the current sampling time k measured by the current sensor, represents the synchronous motor stator current value at the current sampling time k observed by the observer; represents the model parameters of the observer at k-1 sampling moments;

[0018] in,

[0019]

[0020] Where R s Indicates the nominal value of the synchronous motor stator resistance; τ s Indicates the nominal value of the stator time constant of the motor;

[0021] Disturbance voltage estimate The update calculation formula is as follows:

[0022]

[0023] Where, represents the sampling interval of the control cycle of k-2 sampling moments; represents the disturbance voltage observation value at the k-2 sampling time; λ2 represents the integral calculation gain of the disturbance voltage, and 0<λ2<1.

[0024] Preferably, in step S2, the estimated value of the disturbance voltage at the current sampling time k is The calculation formula is as follows:

[0025]

[0026] Synchronous motor stator current observation value The prediction calculation formula is as follows:

[0027]

[0028] Where, are the observer model parameters at the current sampling time k, and represents the back electromotive force at the current sampling time k, and θ r k represents the measured value of the synchronous motor rotor position at the current sampling time k, ψ r represents the permanent magnet flux of the synchronous motor rotor; represents the voltage vector output from the inverter to the stator terminal of the motor at the current sampling time k; Indicates the sampling interval of the control cycle at the current sampling time k.

[0029] Preferably, in step S3, the voltage drop of the synchronous motor stator winding at the k+1 sampling time is The calculation formula is as follows:

[0030]

[0031] The disturbance voltage observation value at sampling time k+1 The calculation formula is as follows:

[0032]

[0033] Preferably, in step S4, the voltage command phase at the k+1 sampling moment is The prediction calculation formula is as follows:

[0034]

[0035] Where N represents the number of sampling points in the [0-60°) sector of the selected synchronous modulation strategy; represents the back electromotive force at the k+1 sampling moment, and

[0036] Preset sampling position r u The calculation formula is as follows:

[0037]

[0038] Wherein, round() indicates rounding to the nearest integer; θ0 indicates the first sampling position of the synchronous modulation strategy in the [0-60°) sector.

[0039] Preferably, the sampling interval of the control cycle described in step S5 is The calculation formula is as follows:

[0040]

[0041] Preferably, the voltage instruction in step S6 The generation formula is as follows:

[0042]

[0043] Where, represents the observer model parameters at k+1 sampling moments; represents the stator current reference value, and Indicates the excitation current command, Indicates the torque current command.

[0044] Preferably, in step S7, the duty cycle calculation formula of each basic voltage vector is as follows:

[0045]

[0046] Where dx and dy represent the duty cycles of the two effective voltage vectors; M represents the modulation ratio, and u dc Indicates the DC bus voltage measurement value; Indicates voltage command The phase angle of the zero vector; d0 represents the duty cycle of the zero vector.

[0047] Therefore, the present invention adopts the above-mentioned method for robust predictive current control of a synchronous motor adapted to synchronous space vector modulation, which has the following beneficial effects:

[0048] 1. Based on predictive control and disturbance compensation mechanism, it can realize fast tracking of current instructions and adapt to the needs of high-speed and high-power scenarios;

[0049] 2. Through the variable step size adjustment strategy, the voltage phase is ensured to be strictly synchronized with the SSVM to avoid harmonic problems caused by phase deviation;

[0050] 3. The disturbance observer is combined with variable step size control to reduce the sensitivity to motor parameters.

[0051] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flow chart of a method for robust predictive current control of a synchronous motor adapted to synchronous space vector modulation according to the present invention;

[0053] Figure 2 This is the experimental test waveform of the traditional deadbeat predictive current control described in the simulation experiment when the sampling step size is suddenly reduced from 500μs to 250μs;

[0054] Figure 3 This is an experimental test waveform diagram of the present invention described in the simulation experiment when the sampling step size is suddenly reduced from 500μs to 250μs;

[0055] Figure 4 This is a stator current harmonic diagram of the present invention under a 5-frequency synchronous space vector modulation strategy described in a simulation experiment;

[0056] Figure 5 This is the experimental test waveform diagram of the traditional vector control described in the simulation experiment when the torque command changes in step;

[0057] Figure 6 This is an experimental test waveform diagram of the present invention described in the simulation experiment when the torque command changes in a step manner;

[0058] Figure 7 The following are simulation test waveforms when the stator inductance of the motor deviates from the nominal value by 20% as described in the simulation experiment; (a) is the simulation test waveform without disturbance compensation; (b) is the simulation test waveform with disturbance compensation enabled;

[0059] Figure 8 These are the simulation test waveforms when the permanent magnet flux of the motor described in the simulation experiment deviates from the nominal value by 10%; (a) is the simulation test waveform without disturbance compensation; (b) is the simulation test waveform with disturbance compensation enabled. DETAILED DESCRIPTION

[0060] In order to make the purposes, technical solutions and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions.

[0061] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0062] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0063] like Figure 1As shown, a synchronous motor robust predictive current control method adapted to synchronous space vector modulation (SSVM) includes the following steps:

[0064] S1. Estimate the disturbance voltage deviation according to the current observation error at the current sampling moment, and update the disturbance voltage estimation value at the previous sampling moment based on the estimated disturbance voltage deviation;

[0065] In step S1, the estimation formula of the disturbance voltage deviation is:

[0066]

[0067] Where, represents the disturbance voltage deviation at the k-1 sampling moment; λ1 represents the error feedback gain of the observer; j represents the imaginary unit; represents the sampling interval of k-1 sampling moments; ω e Indicates the electrical speed of the synchronous motor rotor; and represent the current observation errors at the k-1 sampling moment and the current sampling moment k, respectively, and represents the synchronous motor stator current value at the current sampling time k measured by the current sensor, represents the synchronous motor stator current value at the current sampling time k observed by the observer; represents the model parameters of the observer at k-1 sampling moments;

[0068] in,

[0069]

[0070] Where R s Indicates the nominal value of the synchronous motor stator resistance; τ s Indicates the nominal value of the stator time constant of the motor;

[0071] Disturbance voltage estimate The update calculation formula is as follows:

[0072]

[0073] Where, represents the sampling interval of the control cycle of k-2 sampling moments; represents the disturbance voltage observation value at the k-2 sampling time; λ2 represents the integral calculation gain of the disturbance voltage, and 0<λ2<1.

[0074] S2. Based on the disturbance voltage estimation value at the previous sampling moment obtained in step S1, the disturbance voltage estimation value at the current sampling moment is calculated, and based on the disturbance voltage estimation value at the current sampling moment, the synchronous motor stator current observation value at the next sampling moment is predicted to compensate for the digital delay;

[0075] In step S2, the estimated value of the disturbance voltage at the current sampling time k is The calculation formula is as follows:

[0076]

[0077] Synchronous motor stator current observation value The prediction calculation formula is as follows:

[0078]

[0079] Where, are the observer model parameters at the current sampling time k, and represents the back electromotive force at the current sampling time k, and θ r k represents the measured value of the synchronous motor rotor position at the current sampling time k, ψ r represents the permanent magnet flux of the synchronous motor rotor; represents the voltage vector output from the inverter to the stator terminal of the motor at the current sampling time k; Indicates the sampling interval of the control cycle at the current sampling time k.

[0080] S3. Based on the synchronous motor stator current observation value at the next sampling moment obtained in step S2, the voltage drop of the synchronous motor stator winding at the next sampling moment is calculated, and based on the disturbance voltage estimation value at the current sampling moment obtained in step S2, the disturbance voltage observation value at the next sampling moment is calculated;

[0081] In step S3, the voltage drop of the synchronous motor stator winding at the k+1 sampling time is The calculation formula is as follows:

[0082]

[0083] The disturbance voltage observation value at sampling time k+1 The calculation formula is as follows:

[0084]

[0085] S4. Based on the voltage drop and disturbance voltage observation values ​​of the synchronous motor stator winding at the next sampling moment obtained in step S3, predict the voltage command phase at the next sampling moment, and calculate the preset sampling position adjacent to the voltage command phase at the next sampling moment, so as to map the motor command phase to the discrete sampling points preset by the SSVM;

[0086] In step S4, the voltage command phase at the k+1 sampling time is The prediction calculation formula is as follows:

[0087]

[0088] Where N represents the number of sampling points in the [0-60°) sector of the selected synchronous modulation strategy; represents the back electromotive force at the k+1 sampling moment, and

[0089] Preset sampling position r u The calculation formula is as follows:

[0090]

[0091] Wherein, round() indicates rounding to the nearest integer; θ0 indicates the first sampling position of the synchronous modulation strategy in the [0-60°) sector.

[0092] S5. Based on the voltage command phase calculated in step S4 and the preset sampling position, the sampling interval of the control cycle at the next sampling moment is calculated, so that the voltage command is aligned with the sampling point of the SSVM by adjusting the control cycle to avoid phase deviation;

[0093] The sampling interval of the control cycle described in step S5 The calculation formula is as follows:

[0094]

[0095] S6. Generate a voltage command based on the sampling interval of the control cycle at the next sampling moment calculated in step S5;

[0096] The voltage instruction described in step S6 The generation formula is as follows:

[0097]

[0098] Where, represents the observer model parameters at k+1 sampling moments; represents the stator current reference value, and Indicates the excitation current command, Indicates the torque current command.

[0099] S7. Based on the voltage command obtained in step S6, the duty cycle of each basic voltage vector is calculated to obtain the SSVM pulse.

[0100] In step S7, the duty cycle of each basic voltage vector is calculated as follows:

[0101]

[0102] Where dx and dy represent the duty cycles of the two effective voltage vectors; M represents the modulation ratio, and u dc Indicates the DC bus voltage measurement value; Indicates voltage command The phase angle of the zero vector; d0 represents the duty cycle of the zero vector.

[0103] Simulation experiment

[0104] The method of the present invention is compared with the traditional deadbeat predictive current control method by conducting sampling step mutation experiment, harmonic suppression experiment, torque step response experiment and parameter robustness experiment. The results of the sampling step mutation experiment are as follows: Figure 2 and Figure 3 As shown, it can be seen that the traditional deadbeat predictive current control will cause transient current tracking errors when the sampling step size suddenly changes, while the technical solution of the present invention can still maintain good control performance when the sampling step size suddenly changes.

[0105] The results of harmonic suppression experiments are as follows: Figure 4 As shown, the motor phase voltage waveform is symmetrical in steady state, and the stator current has no obvious fractional and even harmonics, indicating that the technical solution of the present invention can better reproduce the low current harmonic characteristics of synchronous space vector modulation during quasi-steady-state operation.

[0106] The torque step response test results are as follows: Figure 5 and Figure 6 As shown in Figure 2, the traditional vector control takes about 5.8ms and 3.5ms to reach a new steady state when the torque command increases and decreases suddenly, respectively, while the technical solution of the present invention only takes 3.3ms and 1.3ms under the same test conditions. In addition, from the phase synchronization error Δθ u It can be seen that the technical solution of the present invention can eliminate the synchronization error in only 1.4 ms at most, while the traditional vector control takes more than 6 ms under the same test conditions.

[0107] The parameter robustness experimental results are as follows Figure 7 and Figure 8 As shown in the figure, when there is no disturbance compensation, a steady-state error occurs in the current. After disturbance compensation is enabled, the error is significantly suppressed and stable tracking is maintained.

[0108] The above test results verify that the technology of the present invention has faster current tracking response and phase synchronization speed than traditional technical solutions, thereby proving the effectiveness of the present invention.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A robust predictive current control method for a synchronous motor adapted to synchronous space vector modulation, characterized by: The following steps are involved: S1. Estimate the disturbance voltage deviation according to the current observation error at the current sampling moment, and update the disturbance voltage estimation value at the previous sampling moment based on the estimated disturbance voltage deviation; In step S1, the estimation formula of the disturbance voltage deviation is: Where, represents the disturbance voltage deviation at the k-1 sampling moment; λ1 represents the error feedback gain of the observer; j represents the imaginary unit; represents the sampling interval of k-1 sampling moments; ω e Indicates the electrical speed of the synchronous motor rotor; and represent the current observation errors at the k-1 sampling moment and the current sampling moment k, respectively, and represents the synchronous motor stator current value at the current sampling time k measured by the current sensor, represents the synchronous motor stator current value at the current sampling time k observed by the observer; represents the model parameters of the observer at k-1 sampling moments; in, Where R s Indicates the nominal value of the synchronous motor stator resistance; τ s Indicates the nominal value of the stator time constant of the motor; Disturbance voltage estimate The update calculation formula is as follows: Where, represents the sampling interval of the control cycle of k-2 sampling moments; represents the disturbance voltage observation value at the k-2 sampling time; λ2 represents the integral calculation gain of the disturbance voltage, and 0<λ2<1; S2. Based on the disturbance voltage estimation value at the previous sampling moment obtained in step S1, the disturbance voltage estimation value at the current sampling moment is calculated, and based on the disturbance voltage estimation value at the current sampling moment, the synchronous motor stator current observation value at the next sampling moment is predicted to compensate for the digital delay; S3. Based on the synchronous motor stator current observation value at the next sampling moment obtained in step S2, the voltage drop of the synchronous motor stator winding at the next sampling moment is calculated, and based on the disturbance voltage estimation value at the current sampling moment obtained in step S2, the disturbance voltage observation value at the next sampling moment is calculated; S4. Based on the voltage drop and disturbance voltage observation values ​​of the synchronous motor stator winding at the next sampling moment obtained in step S3, predict the voltage command phase at the next sampling moment, and calculate the preset sampling position adjacent to the voltage command phase at the next sampling moment, so as to map the motor command phase to the discrete sampling points preset by the SSVM; S5. Based on the voltage command phase calculated in step S4 and the preset sampling position, the sampling interval of the control cycle at the next sampling moment is calculated, so that the voltage command is aligned with the sampling point of the SSVM by adjusting the control cycle to avoid phase deviation; S6. Generate a voltage command based on the sampling interval of the control cycle at the next sampling moment calculated in step S5; S7. Based on the voltage command obtained in step S6, the duty cycle of each basic voltage vector is calculated to obtain the SSVM pulse.

2. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 1, characterized in that: In step S2, the estimated value of the disturbance voltage at the current sampling time k is The calculation formula is as follows: Synchronous motor stator current observation value The prediction calculation formula is as follows: Where, are the observer model parameters at the current sampling time k, and represents the back electromotive force at the current sampling time k, and θ r k represents the measured value of the synchronous motor rotor position at the current sampling time k, ψ r represents the permanent magnet flux of the synchronous motor rotor; represents the voltage vector output from the inverter to the stator terminal of the motor at the current sampling time k; Indicates the sampling interval of the control cycle at the current sampling time k.

3. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 2, characterized in that: In step S3, the voltage drop of the synchronous motor stator winding at the k+1 sampling time is The calculation formula is as follows: The disturbance voltage observation value at sampling time k+1 The calculation formula is as follows:

4. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 3, characterized in that: In step S4, the voltage command phase at the k+1 sampling time is The prediction calculation formula is as follows: Where N represents the number of sampling points in the [0-60°) sector of the selected synchronous modulation strategy; represents the back electromotive force at the k+1 sampling moment, and Preset sampling position r u The calculation formula is as follows: Wherein, round() indicates rounding to the nearest integer; θ0 indicates the first sampling position of the synchronous modulation strategy in the [0-60°) sector.

5. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 4, characterized in that: The sampling interval of the control cycle described in step S5 The calculation formula is as follows:

6. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 5, characterized in that: The voltage instruction described in step S6 The generation formula is as follows: Where, represents the observer model parameters at k+1 sampling moments; represents the stator current reference value, and Indicates the excitation current command, Indicates the torque current command.

7. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 6, characterized in that: In step S7, the duty cycle of each basic voltage vector is calculated as follows: Where dx and dy represent the duty cycles of the two effective voltage vectors; M represents the modulation ratio, and u dc Indicates the DC bus voltage measurement value; Indicates voltage command The phase angle of the zero vector; d0 represents the duty cycle of the zero vector.

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