Vienna rectifier control algorithm and system based on real-time parameter dynamic adjustment

Abstract

The invention discloses a Vienna rectifier control algorithm and system based on real-time parameter dynamic adjustment. Belongs to the technical field of power electronic converter control. The method comprises the following steps: S1, acquiring three-phase voltage, load current and direct-current bus voltage of a power grid in real time; s2, judging whether an open-phase fault occurs or not according to the three-phase voltage; s3, if the open phase does not exist, PI controller parameters of a current loop are dynamically adjusted based on the ratio of the load current to the rated current; meanwhile, feedforward compensation is carried out on a direct-current voltage reference value based on power grid voltage fluctuation; and S4, generating a control signal to drive the Vienna rectifier based on the dynamically adjusted parameters or the fault-tolerant control mode under the open phase. According to the method, the problems that traditional fixed parameter PI control is poor in dynamic response and weak in anti-interference capability and shutdown must be carried out under an open-phase fault are effectively solved, and the stability and the reliability of the Vienna rectifier in a wide load range and under a non-ideal power grid condition are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of power electronic converter control technology, and in particular to a Vienna rectifier control algorithm and system based on real-time parameter dynamic adjustment. Background Technology

[0002] Vienna rectifiers, with their three-phase, three-level topology, offer advantages such as high power factor, low total harmonic distortion (THD), and high efficiency, making them widely used in new energy power generation, electric vehicle charging, and data center power supply. However, traditional control methods have the following drawbacks:

[0003] Fixed parameter PI control: The proportional (Kp) and integral (Ki) coefficients tuned using the Ziegler-Nichols method cannot adapt to sudden load changes or grid voltage fluctuations, resulting in slow dynamic response or overshoot.

[0004] Hysteresis control limitations: Although it can suppress switching losses, when the hysteresis bandwidth is fixed, it is easy to cause current harmonic bounce under heavy load or light load conditions.

[0005] Inadequate handling of phase loss faults: Conventional three-phase control methods require shutdown protection when a phase is lost in the power grid, which reduces system reliability.

[0006] Existing current limiting control methods achieve overload protection through upper and lower current thresholds, but do not solve the problem of parameter adaptation; while sliding mode active disturbance rejection control improves robustness, it relies on an extended state observer, which increases computational complexity. Summary of the Invention

[0007] To address the existing problems, this invention provides a Vienna rectifier control algorithm and system based on real-time dynamic parameter adjustment, the specific solution of which is as follows:

[0008] A Vienna rectifier control method based on real-time parameter dynamic adjustment includes the following steps:

[0009] S1, Data Acquisition: Real-time acquisition of the three-phase input voltage, load current, and DC bus voltage of the power grid;

[0010] S2, Phase loss judgment: Determine whether a phase loss fault has occurred in the power grid based on the three-phase input voltage; if a phase loss fault is determined to have occurred, trigger the phase loss flag bit and switch to single-phase SVPWM mode; if no phase loss is determined, execute the dynamic parameter calculation in step S3.

[0011] S3, Dynamic Parameter Calculation:

[0012] Based on the ratio of the load current to a preset rated load current, the proportional parameter Kp and integral parameter Ki of the current loop PI controller are dynamically calculated; at the same time, based on the difference between the average value of the three-phase input voltage and a preset rated grid voltage, the DC voltage reference value is fed forward to obtain the compensated voltage reference value.

[0013] S4, Control signal generation: Based on the dynamic parameters calculated by S3 and the compensated voltage reference value, or based on the phase loss fault-tolerant control strategy triggered when S2 determines that a phase is missing, a PWM control signal is generated to drive the Vienna rectifier.

[0014] Preferably, in step S2, determining whether a phase loss fault has occurred in the power grid specifically involves: calculating the effective value of the voltage of each phase in the three-phase input voltage; if the effective value of any phase voltage is lower than a preset voltage threshold, a phase loss fault is determined to have occurred, and at this time, the phase loss flag is triggered, switching to single-phase SVPWM mode.

[0015] Preferably, the parameters of the current loop PI controller are dynamically calculated in step S3 using the following formula:

[0016] float load_ratio = fabs(I_load / I_nominal);

[0017] Kp = Kp0 + delta_Kp * load_ratio;

[0018] Ki = Ki0 + delta_Ki * load_ratio;

[0019] Where fabs(*) is the absolute value function, load_ratio is the load ratio, Kp0 and Ki0 are preset reference PI parameters, ΔKp and ΔKi are preset adjustment coefficients, I_load is the real-time acquired load current, and I_nominal is the preset rated load current.

[0020] Preferably, in step S3, the DC voltage reference value is fed forward compensated, specifically through the following formula:

[0021] float delta_Vgrid = V_grid_avg - V_grid_nominal;

[0022] V_ref = V_dc_setpoint + kv * delta_Vgrid;

[0023] Where delta_Vgrid is the grid voltage deviation value, V_ref is the compensated voltage reference value, V_dc_setpoint is the preset DC voltage setting value, kv is the preset feedforward coefficient, V_grid_avg is the average value of the three-phase input voltage, and V_grid_nominal is the preset rated grid voltage.

[0024] Preferably, in S4, when S2 determines that a phase loss fault has occurred, the triggered phase loss fault-tolerant control strategy is as follows: switch the control mode of the Vienna rectifier from three-phase space vector pulse width modulation to single-phase space vector pulse width modulation (SVPWM) mode, and reconstruct the current reference value based on the positive-sequence component of the grid voltage separated by the positive-sequence phase-locked loop.

[0025] Preferably, when generating the PWM control signal in S4, an improved sliding mode controller is used as the current loop controller. The sliding surface function of the improved sliding mode controller is: s = e + c * ∫e dt, where e = i_ref - i_actual is the current error, i_ref is the current reference value, i_actual is the actual sampled current, and c is the sliding mode coefficient. The control quantity of the improved sliding mode controller is adjusted by the exponential reaching law s˙ = -ε * sgn(s) - k * s, where ε and k are constants greater than zero. The voltage loop output is used as the current loop reference value after low-pass filtering.

[0026] Preferably, during the control operation in S4, an anti-saturation limit is applied to the integral term of the current loop PI controller, and the limit formula is:

[0027] ;

[0028] Where ntegral is the integral term for the current period, I max This is the preset maximum allowable current.

[0029] The present invention also discloses a Vienna rectifier control system for implementing any of the methods described above, comprising:

[0030] The sensor array is used to collect the three-phase input voltage, load current, and DC bus voltage of the power grid.

[0031] A microcontroller, connected to the sensor group, is configured to execute steps S1 to S4;

[0032] A drive circuit, connected to the microcontroller, is used to drive the power switching transistors of the Vienna rectifier according to the PWM control signal generated by the microcontroller.

[0033] Preferably, the driving circuit provides a dead time when generating PWM signals to drive the upper and lower switches of the same bridge arm, wherein the dead time t dead It is 200 nanoseconds.

[0034] Preferably, the microcontroller is a digital signal processor or a system-on-a-chip that includes an FPGA.

[0035] The beneficial effects of this invention are as follows:

[0036] 1. Strong dynamic performance and adaptability: By establishing a real-time mapping relationship between PI parameters and load current, the controller gain can be automatically adjusted with load changes, effectively solving the problems of slow dynamic response and large overshoot of fixed parameter PI control when the load changes suddenly, and realizing fast and stable dynamic response across the entire load range.

[0037] 2. Improved anti-interference capability: Introducing grid voltage feedforward compensation into the voltage loop can actively suppress the interference of grid voltage fluctuations on DC bus voltage, thereby improving the robustness and steady-state accuracy of the system.

[0038] 3. High reliability and fault tolerance: The innovative phase loss fault detection and fault-tolerant control strategy enables the rectifier to automatically switch to single-phase SVPWM mode to continue stable operation without shutting down when a single phase of the power grid is missing, which greatly improves the power supply reliability and continuity of the system in harsh power grid environments.

[0039] 4. Balance between control performance and computational efficiency: By adopting an improved sliding mode control combined with dynamic PI parameters, high performance is ensured while avoiding complex structures such as extended state observers. The algorithm has a small computational load and is easy to implement on general-purpose digital signal processors, thus reducing hardware costs.

[0040] 5. High operational safety: By introducing an anti-integral saturation mechanism and hardware dead time settings, the system effectively prevents controller saturation failure and power transistor shoot-through risks, ensuring long-term stable and reliable operation. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] This invention proposes a Vienna rectifier control algorithm based on real-time parameter dynamic adjustment. By real-time acquisition of grid voltage, load current, and DC bus voltage, combined with an adaptive control strategy, the following technical breakthroughs are achieved:

[0045] 1. Dynamic parameter adjustment mechanism:

[0046] Establish the mapping relationship between the current loop PI parameters and the load current:

[0047]

[0048] Among them, K p0 K i0 As the reference parameter, ΔK p ΔK i I is the adjustment coefficient. nominal This is the rated load current.

[0049] The voltage loop employs feedforward compensation to reduce grid voltage fluctuations ΔV. grid Introducing reference value calculations:

[0050] V ref =V dc *+k v ⋅ΔV grid ; where k v V is the feedforward coefficient. dc * Sets the DC voltage.

[0051] 2. Phase loss fault tolerance control:

[0052] When a phase loss is detected, the system switches to single-phase space vector pulse width modulation (SVPWM) mode to decouple the three-phase input into two-phase line voltage control, thereby maintaining stable DC output.

[0053] The positive-sequence component of the grid voltage is separated by a positive-sequence phase-locked loop (PLL), and the reference current is reconstructed.

[0054]

[0055] 3. Anti-integral saturation mechanism:

[0056] Introducing an integral term limit:

[0057]

[0058] Among them, I max This is the maximum allowable current.

[0059] Specifically, this invention discloses a Vienna rectifier control method based on real-time parameter dynamic adjustment, such as... Figure 1 This includes the following steps:

[0060] S1, Data Acquisition: Real-time acquisition of the three-phase input voltage, load current, and DC bus voltage of the power grid;

[0061] S2, Phase loss judgment: Determine whether a phase loss fault has occurred in the power grid based on the three-phase input voltage; specifically, calculate the effective value of each phase voltage in the three-phase input voltage, and if the effective value of any phase voltage is lower than a preset voltage threshold, then a phase loss fault is determined to have occurred.

[0062] If a phase loss fault is detected, the phase loss flag is triggered and the system switches to single-phase SVPWM mode. If no phase loss is detected, the dynamic parameter calculation in step S3 is executed. Specifically, in step S2, the system determines whether a phase loss fault has occurred in the power grid by triggering the phase loss flag and switching to single-phase SVPWM mode.

[0063] S3, Dynamic Parameter Calculation:

[0064] Based on the ratio of the load current to a preset rated load current, the proportional parameter Kp and integral parameter Ki of the current loop PI controller are dynamically calculated; at the same time, based on the difference between the average value of the three-phase input voltage and a preset rated grid voltage, the DC voltage reference value is fed forward to obtain the compensated voltage reference value.

[0065] Specifically, the parameters of the current loop PI controller are dynamically calculated in S3 using the following formula:

[0066] float load_ratio = fabs(I_load / I_nominal);

[0067] Kp = Kp0 + delta_Kp * load_ratio;

[0068] Ki = Ki0 + delta_Ki * load_ratio;

[0069] Where fabs(*) is the absolute value function, load_ratio is the load ratio, Kp0 and Ki0 are preset reference PI parameters, ΔKp and ΔKi are preset adjustment coefficients, I_load is the real-time acquired load current, and I_nominal is the preset rated load current.

[0070] In addition, feedforward compensation is performed on the DC voltage reference value, specifically through the following formula:

[0071] float delta_Vgrid = V_grid_avg - V_grid_nominal;

[0072] V_ref = V_dc_setpoint + kv * delta_Vgrid;

[0073] Where delta_Vgrid is the grid voltage deviation value, V_ref is the compensated voltage reference value, V_dc_setpoint is the preset DC voltage setting value, kv is the preset feedforward coefficient, V_grid_avg is the average value of the three-phase input voltage, and V_grid_nominal is the preset rated grid voltage.

[0074] S4, Control signal generation: Based on the dynamic parameters calculated by S3 and the compensated voltage reference value, or based on the phase loss fault-tolerant control strategy triggered when S2 determines that a phase is missing, a PWM control signal is generated to drive the Vienna rectifier.

[0075] Specifically, when S2 determines that a phase loss fault has occurred, the triggered phase loss fault-tolerant control strategy is as follows: the control mode of the Vienna rectifier is switched from three-phase space vector pulse width modulation to single-phase space vector pulse width modulation (SVPWM) mode, and the current reference value is reconstructed based on the positive-sequence component of the grid voltage separated by the positive-sequence phase-locked loop. .

[0076] When generating the PWM control signal, an improved sliding mode controller is used as the current loop controller. The sliding surface function of the improved sliding mode controller is: s = e + c * ∫e dt, where e = i_ref - i_actual is the current error, i_ref is the current reference value, i_actual is the actual sampled current, and c is the sliding mode coefficient. The control quantity of the improved sliding mode controller is adjusted by the exponential reaching law s˙ = -ε *sgn(s) - k * s, where ε and k are constants greater than zero. The voltage loop output is low-pass filtered and used as the current loop reference value.

[0077] During the control operation, an anti-saturation limit is applied to the integral term of the current loop PI controller. The limit formula is as follows:

[0078] ;

[0079] Where ntegral is the integral term for the current period, I max This is the preset maximum allowable current.

[0080] The present invention also discloses a Vienna rectifier control system for implementing any of the methods described above, comprising:

[0081] The sensor array is used to collect the three-phase input voltage, load current, and DC bus voltage of the power grid.

[0082] A microcontroller, connected to the sensor group, is configured to perform steps S1 to S4; the microcontroller is specifically a digital signal processor or a system-on-a-chip containing an FPGA.

[0083] A drive circuit, connected to the microcontroller, is used to drive the power switching transistors of the Vienna rectifier according to the PWM control signal generated by the microcontroller.

[0084] The driving circuit sets a dead time when generating PWM signals to drive the upper and lower switches of the same bridge arm. The dead time t dead It is 200 nanoseconds.

[0085] Example:

[0086] I. Hardware Configuration of the Invention

[0087] Microcontroller: TI C2000 series DSP is selected, integrating a 12-bit ADC module (sampling rate 1MSPS) and an enhanced PWM module (resolution 16-bit).

[0088] Sensor: A Hall effect current sensor (such as LEM LAH 50-P) and a voltage divider network are used to achieve ±1% accuracy sampling.

[0089] Power devices: Infineon CoolMOS™ C7 series MOSFETs are selected, with a withstand voltage of 1200V and an on-resistance of RDS(on) = 45mΩ.

[0090] II. Software Implementation of the Invention

[0091] 1. Initialization:

[0092] void Init_Controller(void) { ADC_Init(ADC_SampleRate_1MSPS); PWM_Init(PWM_Resolution_16Bit, PWM_DeadTime_200ns); PLL_Init(PLL_Bandwidth_100Hz); }

[0093] 2. Main control loop (execution cycle 100μs):

[0094] void Control_Loop(void) { / / Data collection float Va = ADC_Read(PHASE_A); float Vb = ADC_Read(PHASE_B); float Vc = ADC_Read(PHASE_C); float Iload = ADC_Read(LOAD_CURRENT); float Vdc = ADC_Read(DC_BUS); / / Phase loss detection if (Va < V_THRESHOLD || Vb < V_THRESHOLD || Vc < V_THRESHOLD) { Set_ControlMode(SINGLE_PHASE_SVPWM); } else { Set_ControlMode(THREE_PHASE_SLIDING_MODE); } / / Dynamic parameter calculation float load_ratio = fabs(Iload / I_NOMINAL); float Kp = KP0 + DELTA_KP * load_ratio; float Ki = KI0 + DELTA_KI * load_ratio; / / Control algorithm execution float Iref = Voltage_Loop(Vdc, V_REF); float DutyCycle = Current_Loop(Iref, Iload, Kp, Ki); / / PWM output PWM_SetDutyCycle(DutyCycle); }

[0095] III. Experimental Verification of the Invention

[0096] Tests were conducted under conditions of an 800V DC bus and a 50kW load.

[0097] Dynamic response: When a sudden load is applied, the DC voltage recovery time is ≤2ms and the overshoot is <3%.

[0098] Efficiency: Full-load efficiency reaches 97.6%, which is 1.2% higher than traditional PI control.

[0099] Harmonic suppression: Input current THD < 3.8%, meeting IEEE 519 standard.

[0100] This invention effectively solves the problems of poor dynamic response, weak anti-disturbance capability, and the necessity of shutdown under phase loss faults in traditional fixed parameter PI control by introducing dynamic parameter adjustment with adaptive load current, grid voltage feedforward, and phase loss fault-tolerant control. It significantly improves the stability and reliability of Vienna rectifiers under wide load range and non-ideal grid conditions.

[0101] Those skilled in the art will further appreciate that the various logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generalized in their functional form. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in different ways for each specific application, but such implementation decisions should not be construed as departing from the scope of the invention.

[0102] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor such that the processor can read and write information to / from the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and storage medium may reside as discrete components in the user terminal.

[0103] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Vienna rectifier control method based on real-time parameter dynamic adjustment, characterized in that, Includes the following steps: S1, Data Acquisition: Real-time acquisition of the three-phase input voltage, load current, and DC bus voltage of the power grid; S2, Phase loss judgment: Determine whether a phase loss fault has occurred in the power grid based on the three-phase input voltage; if a phase loss fault is determined to have occurred, trigger the phase loss flag bit and switch to single-phase SVPWM mode; if no phase loss is determined, execute the dynamic parameter calculation in step S3. S3, Dynamic Parameter Calculation: Based on the ratio of the load current to a preset rated load current, the proportional parameter Kp and integral parameter Ki of the current loop PI controller are dynamically calculated; at the same time, based on the difference between the average value of the three-phase input voltage and a preset rated grid voltage, the DC voltage reference value is fed forward to obtain the compensated voltage reference value. S4, Control signal generation: Based on the dynamic parameters calculated by S3 and the compensated voltage reference value, or based on the phase loss fault-tolerant control strategy triggered when S2 determines that a phase is missing, a PWM control signal is generated to drive the Vienna rectifier.

2. The method according to claim 1, characterized in that, In step S2, determining whether a phase loss fault has occurred in the power grid involves: calculating the effective value of each phase voltage in the three-phase input voltage; if the effective value of any phase voltage is lower than a preset voltage threshold, a phase loss fault is determined to have occurred, and the phase loss flag is triggered, switching to single-phase SVPWM mode.

3. The method according to claim 1, characterized in that, The parameters of the current loop PI controller are dynamically calculated in S3, specifically through the following formula: float load_ratio = fabs(I_load / I_nominal); Kp = Kp0 + delta_Kp * load_ratio; Ki = Ki0 + delta_Ki * load_ratio; Where fabs(*) is the absolute value function, load_ratio is the load ratio, Kp0 and Ki0 are preset reference PI parameters, ΔKp and ΔKi are preset adjustment coefficients, I_load is the real-time acquired load current, and I_nominal is the preset rated load current.

4. The method according to claim 1, characterized in that, In step S3, the DC voltage reference value is fed forward compensation, which is specifically achieved through the following formula: float delta_Vgrid = V_grid_avg - V_grid_nominal; V_ref = V_dc_setpoint + kv * delta_Vgrid; Where delta_Vgrid is the grid voltage deviation value, V_ref is the compensated voltage reference value, V_dc_setpoint is the preset DC voltage setting value, kv is the preset feedforward coefficient, V_grid_avg is the average value of the three-phase input voltage, and V_grid_nominal is the preset rated grid voltage.

5. The method according to claim 1 or 2, characterized in that, In S4, when S2 determines that a phase loss fault has occurred, the phase loss fault-tolerant control strategy triggered is to switch the control mode of the Vienna rectifier from three-phase space vector pulse width modulation to single-phase space vector pulse width modulation (SVPWM) mode, and reconstruct the current reference value based on the positive sequence component of the grid voltage separated by the positive and negative sequence phase-locked loop.

6. The method according to claim 1, characterized in that, When generating the PWM control signal in S4, an improved sliding mode controller is used as the current loop controller. The sliding surface function of the improved sliding mode controller is: s = e + c * ∫edt, where e = i_ref - i_actual is the current error, i_ref is the current reference value, i_actual is the actual sampled current, and c is the sliding mode coefficient. The control quantity of the improved sliding mode controller is adjusted by the exponential reaching law s˙ = -ε * sgn(s) - k * s, where ε and k are constants greater than zero. The voltage loop output is used as the current loop reference value after low-pass filtering.

7. The method according to claim 6, characterized in that, During the control operation of S4, an anti-saturation limit is applied to the integral term of the current loop PI controller. The limit formula is as follows: ； Where ntegral is the integral term for the current period, I max This is the preset maximum allowable current.

8. A Vienna rectifier control system for implementing the method of any one of claims 1-7, characterized in that, include: The sensor array is used to collect the three-phase input voltage, load current, and DC bus voltage of the power grid. A microcontroller, connected to the sensor group, is configured to execute steps S1 to S4; A drive circuit, connected to the microcontroller, is used to drive the power switching transistors of the Vienna rectifier according to the PWM control signal generated by the microcontroller.

9. The system according to claim 8, characterized in that, The driving circuit sets a dead time when generating PWM signals to drive the upper and lower switches of the same bridge arm. The dead time t dead It is 200 nanoseconds.

10. The system according to claim 8, characterized in that, The microcontroller is specifically a digital signal processor or a system-on-a-chip that includes an FPGA.

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