Synchronous motor robust predictive current control method adaptive to synchronous space vector modulation

Abstract

The invention discloses a synchronous motor robust predictive current control method adaptive to synchronous space vector modulation, and belongs to the field of motor operation control, and the method comprises the following steps: S1, updating a disturbance voltage estimation value at a previous sampling moment; s2, calculating a disturbance voltage estimation value at the current sampling moment, and predicting a stator current observation value of the synchronous motor at the next sampling moment; s3, calculating the voltage drop of the stator winding of the synchronous motor at the next sampling moment, and calculating a disturbance voltage observation value at the next sampling moment; s4, mapping the motor instruction phase to a preset discrete sampling point of the SSVM; s5, enabling the voltage instruction to be aligned with a sampling point of the SSVM; s6, generating a voltage instruction; and S7, obtaining an SSVM pulse. By adopting the robust predictive current control method of the synchronous motor adaptive to the synchronous space vector modulation, the sampling interval change of the SSVM can be adapted under the low-carrier-ratio operation condition, and the current tracking response and the phase synchronization speed are extremely high.

Description

Technical Field

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

[0002] In high-power and high-speed permanent magnet synchronous motor drive systems, the inverter usually operates under low carrier ratio conditions. Under this condition, synchronous space vector modulation (SSVM) has become a very suitable modulation method due to its small current harmonics, no current ripple at sampling points, and the ability to generate drive pulses online in real time. However, during dynamic processes such as phase synchronization or mode switching, the sampling interval of SSVM may change significantly. Traditional control strategies are usually designed based on a fixed control period and are difficult to adapt to such large changes in the sampling interval, resulting in problems such as slow phase synchronization speed and poor dynamic performance of the current loop in SSVM-based control systems.

[0003] Especially under lower carrier ratio conditions, existing solutions mostly adopt complex vector digital current regulators. To maintain the stability margin of the system under large control delays, the bandwidth of the current loop is limited to a low level, which makes the dynamic response speed of the system slow. In addition, to ensure that the inverter can output symmetric voltage pulses required by SSVM during quasi-steady state operation, the voltage phase of the controller must be consistent with the preset sampling position of SSVM. However, during dynamic processes, the controller may arbitrarily adjust the amplitude and phase of the voltage command as needed to eliminate current tracking errors, which may cause a deviation between the voltage command phase and the preset sampling point of SSVM.

[0004] To address the above problems, some control step adjustment methods based on phase-locked loops (PLLs) or error feedforward have been proposed in the existing literature to achieve phase compensation. However, to avoid adverse effects on the current loop, the phase synchronization speed of these methods is usually limited and difficult to meet the requirements of fast dynamic response. On the other hand, deadbeat predictive current control (DPCC) has attracted much attention due to its simple principle and fast dynamic response speed.

[0005] However, traditional DPCC is sensitive to motor parameters and external disturbances. When the motor parameters deviate from the nominal values, it may lead to steady-state tracking errors. To improve the parameter robustness of DPCC, disturbance observers have been widely adopted in the existing literature for compensation. However, traditional DPCC and its disturbance compensation observers are usually designed based on a fixed control period. Therefore, when the SSVM needs to significantly adjust the sampling interval due to switching modulation modes or eliminating phase errors, the system may experience large current shocks, which will affect the overall performance. Summary of the Invention

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

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

[0008] S1. Estimate the disturbance voltage deviation based on the current observation error at the current sampling moment, and update the disturbance voltage estimate at the previous sampling moment based on the estimated disturbance voltage deviation.

[0009] S2. Calculate the disturbance voltage estimate at the current sampling moment based on the disturbance voltage estimate at the previous sampling moment obtained in step S1, and predict the observed value of the synchronous motor stator current at the next sampling moment based on the disturbance voltage estimate at the current sampling moment to compensate for the digital delay.

[0010] S3. Calculate the voltage drop of the synchronous motor stator winding at the next sampling moment based on the observed value of the synchronous motor stator current at the next sampling moment obtained in step S2, and calculate the observed value of the disturbance voltage at the next sampling moment based on the disturbance voltage estimate at the current sampling moment obtained in step S2.

[0011] S4. Predict the voltage command phase at the next sampling moment based on the voltage drop of the synchronous motor stator winding and the observed value of the disturbance voltage at the next sampling moment obtained in step S3, and calculate the preset sampling positions 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. Calculate the sampling interval of the control period at the next sampling moment based on the voltage command phase and the preset sampling positions calculated in step S4, so as to align the voltage command with the sampling points of the SSVM by adjusting the control period and avoid phase deviation.

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

[0014] S7. Calculate the duty cycle of each basic voltage vector based on the voltage command obtained in step S6 to obtain the SSVM pulse.

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

[0016]

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

[0018] Among them,

[0019]

[0020] In the formula, R s represents the nominal value of the synchronous motor stator resistance; τ s represents the nominal value of the motor stator time constant;

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

[0022]

[0023] In the formula, represents the sampling interval of the control cycle at the (k - 2) sampling moment; represents the disturbance voltage observed value at the (k - 2) sampling moment; λ 2 represents the integral calculation gain of the disturbance voltage, and 0 < λ 2 < 1.

[0024] Preferably, in step S2, the disturbance voltage estimated value at the current sampling moment k is calculated as follows:

[0025]

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

[0027]

[0028] Wherein, All represent 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 linkage of the synchronous motor rotor; represents the voltage vector output from the inverter to the motor stator terminal at the current sampling time k; represents the sampling interval of the control period 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 The calculation formula is as follows:

[0030]

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

[0032]

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

[0034]

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

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

[0037]

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

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

[0040]

[0041] Preferably, the voltage command described in step S6 is generated by the following formula:

[0042]

[0043] In the formula, represents the observer model parameters at the (k + 1)-th sampling moment; represents the reference value of the stator current, and represents the field current command, represents the torque current command.

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

[0045]

[0046] In the formula, dx and dy respectively represent the duty cycles of the two effective voltage vectors; M represents the modulation ratio, and u dc represents the measured value of the DC bus voltage; represents the voltage command of the phase angle; d 0 represents the duty cycle of the zero vector.

[0047] Therefore, the present invention adopts the above-mentioned robust predictive current control method for a synchronous motor adapted to synchronous space vector modulation, and the beneficial effects are as follows:

[0048] 1. Based on the predictive control and disturbance compensation mechanism, rapid tracking of the current command is achieved, meeting the requirements 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, avoiding harmonic problems caused by phase deviation;

[0050] 3. The combination of the disturbance observer and the variable step size control reduces the sensitivity to motor parameters.

[0051] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0053] Figure 2Experimental test waveform diagram of the traditional deadbeat predictive current control described in the simulation experiment when the sampling step suddenly decreases from 500 μs to 250 μs;

[0054] Figure 3 Experimental test waveform diagram of the present invention described in the simulation experiment when the sampling step suddenly decreases from 500 μs to 250 μs;

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

[0056] Figure 5 Experimental test waveform diagram of the traditional vector control described in the simulation experiment when the torque command has a step change;

[0057] Figure 6 Experimental test waveform diagram of the present invention described in the simulation experiment when the torque command has a step change;

[0058] Figure 7 Simulation test waveform diagram when the motor stator inductance deviates from the nominal value by 20% in the simulation experiment; among them, (a) is the simulation test waveform diagram without disturbance compensation; (b) is the simulation test waveform diagram with disturbance compensation enabled;

[0059] Figure 8 Simulation test waveform diagram when the motor permanent - magnet flux linkage deviates from the nominal value by 10% in the simulation experiment; (a) is the simulation test waveform diagram without disturbance compensation; (b) is the simulation test waveform diagram with disturbance compensation enabled. Detailed implementation manners

[0060] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following further details the embodiments of the present invention in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the embodiments of the present invention and are not used to limit the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by this application. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end.

[0061] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non - exclusive inclusion. For example, a process, method, system, product or server that includes a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, 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 in conjunction with the accompanying drawings.

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

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

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

[0066]

[0067] In the formula, represents the disturbance voltage deviation at the (k - 1) sampling moment; λ 1 represents the error feedback gain of the observer; j represents the imaginary unit; represents the sampling interval at the (k - 1) sampling moment; ω e represents 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 moment k measured by the current sensor, represents the synchronous motor stator current value at the current sampling moment k observed by the observer; represents the observer model parameter at the (k - 1) sampling moment;

[0068] Among them,

[0069]

[0070] In the formula, R s represents the nominal value of the synchronous motor stator resistance; τ s represents the nominal value of the motor stator time constant;

[0071] The update calculation formula for the disturbance voltage estimate is as follows:

[0072]

[0073] In the formula, represents the sampling interval of the control period at the (k - 2) sampling moment; represents the disturbance voltage observation value at the (k - 2) sampling moment; λ 2 represents the integral calculation gain of the disturbance voltage, and 0 < λ 2 < 1.

[0074] S2. Calculate the estimated value of the disturbance voltage at the current sampling moment based on the estimated value of the disturbance voltage at the previous sampling moment obtained in step S1, and predict the observed value of the synchronous motor stator current at the next sampling moment based on the estimated value of the disturbance voltage at the current sampling moment to compensate for the digital delay;

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

[0076]

[0077] The observed value of the synchronous motor stator current The prediction calculation formula is as follows:

[0078]

[0079] In the formula, All represent the observer model parameters at the current sampling moment k, and Represents the back electromotive force at the current sampling moment k, and θ r k Represents the measured value of the synchronous motor rotor position at the current sampling moment k, ψ r Represents the permanent magnet flux linkage of the synchronous motor rotor; Represents the voltage vector output from the inverter to the motor stator terminal at the current sampling moment k; Represents the sampling interval of the control period at the current sampling moment k.

[0080] S3. Calculate the voltage drop of the synchronous motor stator winding at the next sampling moment based on the observed value of the synchronous motor stator current at the next sampling moment obtained in step S2, and calculate the observed value of the disturbance voltage at the next sampling moment based on the estimated value of the disturbance voltage at the current sampling moment obtained in step S2;

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

[0082]

[0083] The observed value of the disturbance voltage at the sampling moment 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 positions 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)-th sampling moment The prediction calculation formula is as follows:

[0087]

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

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

[0090]

[0091] In the formula, round() represents rounding to the nearest integer; θ 0 represents the first sampling position of the synchronous modulation strategy in the [0 - 60°) sector.

[0092] S5. Based on the voltage command phase and the preset sampling position calculated in step S4, calculate the sampling interval of the control period at the next sampling moment, so as to align the voltage command with the sampling points of the SSVM by adjusting the control period and avoid phase deviation;

[0093] The sampling interval of the control period 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 period at the next sampling moment calculated in step S5;

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

[0097]

[0098] In the formula, represents the observer model parameters at the (k + 1)-th sampling moment; represents the reference value of the stator current, and represents the field current command, represents the torque current command.

[0099] S7. Calculate the duty cycle of each basic voltage vector based on the voltage command obtained in step S6 to obtain the SSVM pulse.

[0100] In step S7, the duty cycle calculation formula for each basic voltage vector is as follows:

[0101]

[0102] In the formula, dx and dy respectively represent the duty cycles of the two effective voltage vectors; M represents the modulation ratio, and u dc represents the measured value of the DC bus voltage; represents the voltage command phase angle; d 0 represents the duty cycle of the zero vector.

[0103] Simulation experiment

[0104] Compare the method of the present invention with the traditional deadbeat predictive current control method to conduct sampling step mutation experiment, harmonic suppression experiment, torque step response experiment and parameter robustness experiment respectively. The results of the sampling step mutation experiment are as Figure 2 and Figure 3 shown. It can be seen that the traditional deadbeat predictive current control will cause transient current tracking error when the sampling step mutates, while the technical solution of the present invention can still maintain good control performance when the sampling step mutates.

[0105] The results of the harmonic suppression experiment are as Figure 4 shown. At steady state, the motor phase voltage waveform is symmetric, and there are no obvious fractional and even harmonics in the stator current, 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 results of the torque step response experiment are as Figure 5 and Figure 6 shown. For the traditional vector control, it takes about 5.8 ms and 3.5 ms respectively to reach the new steady state when the torque command suddenly increases and decreases, while the technical solution of the present invention only needs 3.3 ms and 1.3 ms 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 only needs at most 1.4 ms to eliminate the synchronization error, while the traditional vector control takes more than 6 ms under the same test conditions.

[0107] The results of the parameter robustness experiment are as Figure 7 and Figure 8 shown. When there is no disturbance compensation, a steady-state error appears in the current. After enabling the disturbance compensation, the error is significantly suppressed and stable tracking is maintained.

[0108] The above test results verify that the technology of the present invention has a faster current tracking response and phase synchronization speed compared with the traditional technical solution, thus 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 and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements do not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for robust predictive current control of a synchronous motor adapted to synchronous space vector modulation, characterized in that: 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; S2, based on the disturbance voltage estimation value at the previous sampling moment obtained in step S1, calculate the disturbance voltage estimation value at the current sampling moment, and based on the disturbance voltage estimation value at the current sampling moment, predict the synchronous motor stator current observation value at the next sampling moment, and compensate for the digital delay; S3, based on the synchronous motor stator current observation value at the next sampling moment obtained in step S2, calculate the voltage drop of the synchronous motor stator winding at the next sampling moment, and based on the disturbance voltage estimation value at the current sampling moment obtained in step S2, calculate the disturbance voltage observation value at the next sampling moment; 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 point preset by the SSVM; S5, based on the voltage command phase calculated in step S4 and the preset sampling position, calculate the sampling interval of the control cycle at the next sampling moment, so as to align the voltage command with the sampling point of the SSVM by adjusting the control cycle to avoid phase deviation; S6, generating 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 S1, the estimation formula of the disturbance voltage deviation is: In the formula, represents the disturbance voltage deviation at the k-1 sampling time; λ1 represents the error feedback gain of the observer; j represents the imaginary unit; represents the sampling interval of k-1 sampling time; ω e Indicates the electrical speed of the synchronous motor rotor; and They represent the current observation errors at the k-1 sampling time and the current sampling time 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 time; in, In the formula, 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: In the formula, 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.

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 S2, the estimated value of the disturbance voltage at the current sampling time k is The calculation formula is as follows: Observed value of synchronous motor stator current The prediction calculation formula is as follows: In the formula, Both represent the observer model parameters at the current sampling time k, and represents the back EMF 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.

4. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 3 is 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:

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

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

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: The voltage command described in step S6 The generation formula is as follows: In the formula, represents the observer model parameters at k+1 sampling time; represents the stator current reference value, and Indicates the excitation current command, Indicates the torque current command.

8. The method for robust predictive current control of a synchronous motor using adaptive synchronous space vector modulation according to claim 7, characterized in that: In step S7, the duty cycle calculation formula of each basic voltage vector is 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 measured value of DC bus voltage; Indicates voltage command The phase angle of the zero vector; d0 represents the duty cycle of the zero vector.

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