CN112350565B

CN112350565B - Cascade model-free predictive control system based on single-phase Boost PFC converter and control method thereof

Info

Publication number: CN112350565B
Application number: CN202011122859.1A
Authority: CN
Inventors: 李红梅; 顾佳媛; 张恒果; 潘晨; 栾志远
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2020-10-20
Filing date: 2020-10-20
Publication date: 2021-10-15
Anticipated expiration: 2040-10-20
Also published as: CN112350565A

Abstract

The invention relates to a cascade model-free predictive control system based on a single-phase Boost PFC converter and a control method thereof. The single-phase Boost PFC converter comprises a main circuit and a cascade model-free predictive control system, wherein the cascade model-free predictive control system comprises a voltage outer loop control system and a current inner loop control system. According to the invention, the double-frequency ripple voltage in the output voltage of the single-phase Boost PFC converter is filtered by adopting the average filtering module, so that the ripple voltage is prevented from polluting the amplitude of the reference inductive current, and the calculation burden and delay of the controller are reduced; and a model-free prediction voltage controller is also designed for improving the robustness of the voltage outer loop control system to the total disturbance of the output voltage dynamic system and the dynamic response speed of the voltage outer loop control loop. The method can avoid the complex design of the switching of the conduction mode identification and control method, effectively improve the robustness to the parameter change and the internal and external dynamic interference of the single-phase Boost PFC converter, and comprehensively improve the dynamic and steady-state control performance of the single-phase Boost PFC converter in the full-power range operation.

Description

Cascade model-free predictive control system based on single-phase Boost PFC converter and control method thereof

Technical Field

The invention relates to the technical field of Boost PFC converters, in particular to a cascade model-free predictive control system and a control method thereof based on a single-phase Boost PFC converter.

Background

In order to meet the harmonic requirements of international standards and grid guidelines for the access of Power equipment to the grid, Power Factor Correction (PFC) converter-related topology design and control strategies are continuously gaining research attention. The single-phase Boost PFC converter is widely applied to medium and high power occasions due to the advantages of continuous input current, simple driving of a switching tube, small conduction loss and the like. A double closed loop structure formed by cascading a low-bandwidth voltage outer loop and a high-bandwidth current inner loop is mostly applied to control of a single-phase Boost PFC converter. Under the double closed-loop cascade control structure, the voltage outer loop and the current inner loop can be designed independently. The converter operates in a Continuous Conduction Mode (CCM) and a Discontinuous Conduction Mode (DCM) according to the Conduction state of the inductor current in one switching cycle. With the reduction of load power, the inductor current of the Boost PFC converter has a discontinuous phenomenon at the zero crossing point of the input current and is continuous at the peak value of the input current. When the CCM and DCM modes occur simultaneously in one power frequency period, the Boost PFC converter operates in a Mixed Conduction Mode (MCM).

The traditional PFC current control loop is mainly designed into a PI controller based on a mathematical model of a CCM converter, and regulates the input current of the converter to be sinusoidal by generating a duty ratio signal, and the input current and the input voltage have the same phase, so that the current distortion is reduced, and the unit power factor control is realized. Unfortunately, under the medium and light load operation condition, the PI current controller based on the CCM converter mathematical model cannot adapt to the complex nonlinearity caused by the discontinuous conduction mode, so that the input current control performance is reduced, and the input current cannot be completely sinusoidal. In order to inhibit the current harmonic generated when the converter operates in DCM, the duty ratio feedforward control provided on the basis of PI current control can effectively improve the input current control performance under the medium and light load operation condition, but the inherent characteristic of insufficient bandwidth of the PI controller limits the realization of accurate and rapid tracking of the inductive current, and the duty ratio feedforward control is still difficult to obtain satisfactory current control performance. In addition, the PI-based duty ratio feedforward control still has the technical defects of being sensitive to the parameter change of the converter and internal and external disturbance. For this reason, the existing solution needs to firstly identify the operation mode and then design the current prediction controllers in CCM and DCM, respectively. The additional pattern recognition and control scheme design of controller switching in different modes undoubtedly increases the complexity of real-time implementation. The model predictive control is a control method with great potential, has the characteristics of simple and flexible control structure and quick control response, but the sensitivity of the model predictive control depends on a mathematical model of a system, and also has the technical defects of sensitivity to the parameter change of a converter and internal and external disturbance. According to the conservation of input and output power, the voltage control system of the single-phase PFC converter provides a reference inductive current amplitude value for the current control system to stabilize the output voltage. Due to the pulsating input power on the ac side of the converter, the output voltage of the single-phase PFC converter must contain a dc voltage and a double grid frequency ripple voltage. If the double-frequency ripple voltage passes through the voltage control system, the accurate generation of the reference inductive current amplitude is directly influenced, and the input current waveform of the converter is damaged.

Similarly, the conventional PFC voltage control system designs the PI voltage controller based on a mathematical model of the CCM converter, and limits the passing of the double-frequency voltage ripple by taking an active bandwidth reduction measure. However, when the load changes, the PI voltage controller with low bandwidth may cause slow system dynamic response, large overshoot of the output voltage, and long settling time, increase circuit loss, and even damage circuit elements. In order to accurately generate a current reference value, a trap filter is adopted in a PI voltage control loop to filter double-frequency ripple voltage in feedback output voltage, but phase lag introduced by the trap filter can reduce the stability margin of a system and influence the stable operation of the system. Therefore, the extra compensation loop is designed to make up for the time delay of the wave trap, but a control gain item needing to be set is added, and the design complexity is increased. In order to further improve the rapidity of the voltage dynamic control of the PFC converter, the non-linear PI controller is designed in the existing literature, and the bandwidth of the controller is changed according to the tracking error of the output voltage, so that the low harmonic distortion of the input current in a steady state is ensured, and the rapid convergence of the output voltage in a dynamic state is also ensured. Unfortunately, voltage control based on non-linear PI controller design still has technical deficiencies sensitive to converter parameter variations and internal and external disturbances.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a cascade model-free predictive control system based on a single-phase Boost PFC converter and a control method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a cascade model-free predictive control system based on a single-phase Boost PFC converter comprises a single-phase Boost PFC converter main circuit and a cascade model-free predictive control system.

Main circuit package of single-phase Boost PFC converterThe circuit comprises an uncontrolled rectifier bridge circuit and a DC-DC Boost converter. The uncontrolled rectifier bridge circuit includes a diode D1, a diode D2, a diode D3, and a diode D4. The uncontrolled rectifier bridge circuit is used for inputting an alternating current power supply v_acPrimarily rectifying the wave into an steamed bread wave, and inputting the steamed bread wave into a DC-DC Boost converter. The diode D1 is connected with the diode D3 in series, and the intersection point of the diode D1 and the diode D3 is connected with an alternating current input power supply v_acAre connected with each other at one end. The diode D2 is connected with the diode D4 in series, and the intersection point of the diode D2 and the diode D4 is connected with an alternating current input power supply v_acThe other ends are connected. The cathode of the diode D1 and the cathode of the diode D2 are both connected with the input end of the DC-DC Boost converter, and the anodes of the diode D3 and the diode D4 are both grounded.

The DC-DC Boost converter comprises a Boost inductor L, a power switch device S, a freewheeling diode D, an output capacitor C and a resistive load R. The DC-DC Boost converter is used for further rectifying and boosting the steamed bread waves generated by rectifying the uncontrolled rectifier bridge and stabilizing output voltage. One end of a Boost inductor L at the input side of the DC-DC Boost converter is the input end of the DC-DC Boost converter, and the other end of the Boost inductor L is respectively connected with the anode of the freewheeling diode D and the drain of the power switch device S. And the source electrode of the power switch device S is grounded, and the grid electrode of the power switch device S is connected with the output end of a PWM (pulse-width modulation) module in the cascade model-free predictive control system. And the cathode of the freewheeling diode D is connected with one end of the output capacitor C, and the other end of the output capacitor C is grounded. And the resistive load R is connected in parallel at two ends of the output capacitor C.

The cascade model-free predictive control system comprises a voltage outer loop control system and a current inner loop control system. The voltage outer loop control system comprises an output voltage sensor, an average filtering module and a model-free prediction voltage controller. And the output voltage sensor is used for acquiring an actual output voltage signal and providing the actual output voltage signal to the average filtering module. The input end of the output voltage sensor is connected with the cathode of the freewheeling diode D, and the output end of the output voltage sensor is connected with the average filtering module. And the average filtering module is used for reducing the calculation delay, acquiring an average output voltage value and providing the average output voltage value for the model-free prediction voltage controller. The input end of the average filtering module is connected with the output end of the output voltage sensor, and the output end of the average filtering module is connected with the input end of the model-free prediction voltage controller. The model-free prediction voltage controller is used for stabilizing output voltage and providing reference inductance current amplitude for a current inner loop control system. The input end of the model-free prediction voltage controller is connected with a reference output voltage value given by a user, and the output end of the model-free prediction voltage controller is connected with the input end of the reference current generation module.

The current inner loop control system comprises an input voltage sensor, an inductive current sensor, a reference current generation module, a model-free prediction current controller and a PWM modulation module. The input voltage sensor is used for collecting an actual input voltage signal and providing the actual input voltage signal to the reference current generation module. The input terminal of the input voltage sensor is connected to the anode of the diode D1, and the output terminal of the input voltage sensor is connected to the input terminal of the reference current generating module. The reference current generation module is used for generating a reference inductance current value. The output end of the reference current generation module is connected with the input end of the model-free prediction current controller. The inductive current sensor is used for acquiring an actual inductive current signal and providing the actual inductive current signal to the model-free predictive current controller. The input end of the inductive current sensor is connected to a branch circuit between the ground end and the source electrode of the power switch device S, and the output end of the inductive current sensor is connected with the input end of the model-free prediction current controller. The model-free predictive current controller is used for controlling the inductive current by generating the duty ratio of the switching tube S, so that the input current is sinusoidal and has the same phase with the alternating-current input voltage. And the output end of the model-free prediction current controller is connected with the input end of the PWM modulation module. The PWM module is used for generating a driving signal of the switching tube S, and the output end of the PWM module is connected with the grid electrode of the power switching device S.

The invention also relates to a control method of the cascade model-free predictive control system based on the single-phase Boost PFC converter, which comprises the following steps:

(1) and obtaining an average output voltage value by using an average filtering module. According to the k-n_FvOne sampling period

Average output voltage value V of_o[k-n_Fv]To the kth sampling period T_kAverage output voltage value V of_o[k]K-n, th_Fv2 sampling periods

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

Determining the k-th sampling period T_kEstimate of total disturbance part of voltage outer loop control system

Wherein k is a positive integer.

(2) Estimating value of total disturbance part of voltage outer ring control system according to kth sampling period

Reference inductance current amplitude

And a reference inductance current amplitude coefficient alpha_v[k]And establishing a unified super-local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, and carrying out Euler dispersion on the unified super-local model to obtain a dispersion voltage equation.

(3) Carrying out Euler discrete voltage equation according to a unified super-local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, designing a model-free predictive voltage controller, and solving the kth sampling period T by adopting the model-free predictive voltage controller_kReference inductor current amplitude of

The output voltage of the single-phase Boost PFC converter system is stabilized to a rated value.

(4) Adopting a reference current generation module to sample the kth sampling period T_kReference inductor current amplitude value

And an input voltage v_ac[k]Processing to obtain the k sampling period T_kReference inductance current value of

(5) According to the k-n_FiOne sampling period

Of the inductor current i_L[k-n_Fi]To the kth sampling period T_kOf the inductor current i_L[k]K-n, th_Fi2 sampling periods

Duty ratio control signal d [ k-n ]_Fi-2]To the k-2 sampling period T_k-2Duty ratio control signal d [ k-2 ]]To find the kth sampling period T_kEstimate of the total disturbance component of the current inner loop control system

(6) According to the estimated value of the total disturbance part of the current inner loop control system in the kth sampling period

Duty cycle control signal d [ k ]]And duty ratio coefficient alpha_i[k]Establishing a unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes, and carrying out Euler dispersion on the unified super-local model to obtain a dispersion current equation.

(7) According to the unified super-local part of the inductive current of the single-phase Boost PFC converter system under different conduction modesCarrying out Euler discrete current equation by the model, designing a model-free prediction current controller, and solving the kth sampling period T by the model-free prediction current controller_kDuty ratio control signal d [ k ]]。

(8) Using PWM modulation module to sample the kth sampling period T_kDuty ratio control signal d [ k ]]Modulating to obtain the kth sampling period T_kPower switch device driving signal S k]And controlling a power switch device S of the single-phase Boost PFC converter to act so that the inductance current of the single-phase Boost PFC converter tracks the reference inductance current value.

Further, the step (1) utilizes an average filtering module to obtain an average output voltage value. According to the k-n_FvOne sampling period

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

Wherein k is a positive integer; ", which comprises the following steps:

(11) at the k-th sampling period T_kIn the method, the kth sampling period T is obtained by using an output voltage sensor_kIs output voltage v_o[k]。

(12) Using pairs of averaging filter modulesOutput voltage v_o[k]An averaging process is performed. The number of sampling points in one output voltage period set by a user is N, and m is defined as the number of the output voltage periods. When m is equal to 1, namely in the first output voltage period, the average output voltage value of the first N-1 sampling points is equal to the output voltage sampling value because the output voltage sampling value is not enough to calculate the average output voltage value. The average output voltage value of the Nth sampling point is equal to the average voltage value of the sum of the N output voltage sampling values in the first output voltage period; when m is>And 1, superposing the difference value of the output voltage sampling value at the current sampling point of the mth output voltage period and the output voltage sampling value at the current sampling point of the m-1 output voltage period based on the average output voltage value of the nth sampling point of the m-1 output voltage period to obtain the average output voltage value of the previous N-1 sampling points. And the average output voltage value of the Nth sampling point is equal to the average voltage value of the sum of the N output voltage sampling values of the mth output voltage period, and the average output voltage value of the Nth sampling point is used for correcting the accumulated error calculated by the average output voltage values of the previous N-1 sampling points. The average filtering algorithm does not need to sum and average N output voltage sampling values at each output voltage sampling point, can also obtain relatively accurate average output voltage values, reduces the calculation burden of a control system, and reduces the calculation delay by simplifying the average filtering algorithm.

The k sampling period T is obtained by the formula (1)_kAverage output voltage value V of_o[k]；

Wherein, V_o[mk]Represents an average output voltage value at a kth sampling point of an mth output voltage period; v. of_{o_mk}The sampling value of the output voltage at the kth sampling point of the mth output voltage period;

an average voltage value representing the sum of the output voltage sampling values of the N sampling points of the mth output voltage period; v_o[(m-1)N]For m-1 th output powerThe average voltage value of the Nth sampling point of the voltage period; v. of_{o_(m-1)k}The sampling value of the output voltage at the kth sampling point of the (m-1) th output voltage period is obtained; n is the number of sampling points in one output voltage period set by a user; m is the number of output voltage cycles, and m is a positive integer; i is an integer between 1 and N.

(13) At the k-th sampling period T_kIn accordance with the k-n_FvOne sampling period

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

The k sampling period T is obtained by the formula (2)_kEstimate of total disturbance part of voltage outer loop control system

Wherein the content of the first and second substances,

representing the kth sampling period T_kThe estimated value of the total disturbance part of the voltage outer loop control system; n is_FvRepresenting the length of a data window, and taking a positive integer; k is a positive integer; m is k-n_FvInteger between +1 and k (including k-n)_Fv+1 and k); t is_vThe control period of the voltage outer ring control system is shown; alpha is alpha_v[k]Is a reference inductance current amplitude coefficient set by a designer; v_o[m-1]Represents the m-1 th sampling period T_m-1The average output voltage value of (1); v_o[m]Represents the m-th sampling period T_mThe average output voltage value of (1);

represents the m-3 th sampling period T_m-3The reference inductor current amplitude of (a);

represents the m-2 th sampling period T_m-2The reference inductor current amplitude of (a); when m is less than or equal to 0, V_o[m-1]＝V_o[m]0; when m is less than or equal to 2,

further, the estimated value of the total disturbance part of the voltage outer loop control system according to the k sampling period in the step (2)

Reference inductance current amplitude

And a reference inductance current amplitude coefficient alpha_v[k]Establishing a unified super-local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, and carrying out Euler dispersion on the unified super-local model to obtain a dispersion voltage equation; ", which comprises the following steps:

(21) establishing an output voltage dynamic equation of the single-phase Boost PFC converter operating in a continuous conduction mode by adopting a formula (3);

wherein the content of the first and second substances,

represents the first differential of the output voltage; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); i.e. i_o[k]Representing the kth sampling period T_kThe load current of (1); c represents the output capacitance value.

(22) Establishing an output voltage dynamic equation of the single-phase Boost PFC converter in an intermittent conduction mode by adopting a formula (4);

wherein the content of the first and second substances,

represents the first differential of the output voltage; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); i.e. i_o[k]Representing the kth sampling period T_kThe load current of (1); c represents an output capacitance value; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); l represents an input inductance value; r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle.

(23) According to the output voltage dynamic equations under different conduction modes represented by the formulas (3) and (4), the output voltage dynamic equations of the Boost PFC converter can be unified into a formula (5):

wherein the content of the first and second substances,

represents the first differential of the output voltage;

representing the kth sampling period T_kThe nonlinear interference part of the output voltage dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); c represents the output capacitance value.

From the formulae (3), (4) and (5), F_v[k]The nonlinear interference part appearing in the output voltage dynamic equation of the single-phase Boost PFC converter operating in different conduction modes can be uniformly expressed, and can be represented by an equation (6):

wherein the content of the first and second substances,

representing the kth sampling period T_kThe nonlinear interference part of the output voltage dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); i.e. i_o[k]Representing the kth sampling period T_kThe load current of (1); c represents an output capacitance value; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); l represents an input inductance value; r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle. Expression formula

Representing a nonlinear interference part appearing in an output voltage equation when the Boost PFC converter operates in a continuous conduction mode; expression formula

And the nonlinear interference part appearing in the output voltage equation when the Boost PFC converter operates in the discontinuous conduction mode is represented.

(24) Bo represented by the formula (5)The unified output voltage dynamic equation of the ost PFC converter contains frequency doubling voltage ripples, presents nonlinear time-varying characteristics, and is not beneficial to the design of a corresponding output voltage prediction controller, so that the equation (5) is subjected to integral averaging, nonlinear influence brought by the frequency doubling voltage ripples is eliminated, and a unified super-local model of the output voltage of the Boost PFC converter is obtained. Using the kth sampling period T_kEstimate of total disturbance part of voltage outer loop control system

The kth sampling period T_kReference inductor current amplitude of

And a reference inductance current amplitude coefficient alpha_v[k]Establishing a unified super-local model of the output voltage of the Boost PFC converter in different conduction modes by adopting an equation (7):

wherein the content of the first and second substances,

represents the first differential of the average output voltage;

representing the kth sampling period T_kThe estimated value of the total disturbance part of the voltage outer loop control system; alpha is alpha_v[k]Is a reference inductance current amplitude coefficient set by a designer;

representing the kth sampling period T_kThe reference inductor current magnitude of (1).

(25) Euler dispersion is carried out on the unified super-local model of the output voltage of the Boost PFC converter by adopting an equation (8) to obtain a dispersion voltage equation:

wherein, V_o[k+2]Represents the k +2 th sampling period T_k+2The average output voltage value of (1); v_o[k]Representing the kth sampling period T_kThe average output voltage value of (1); t is_vThe control period of the voltage outer ring control system is shown;

Further, the step (3) of performing Euler discrete voltage equation according to the unified super local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, designing a model-free predicted voltage controller, and solving the kth sampling period T by adopting the model-free predicted voltage controller_kReference inductor current amplitude of

Stabilizing the output voltage of the single-phase Boost PFC converter system to a rated value; ", which comprises the following steps:

in order to stabilize the output voltage value, the k +2 sampling period T is adopted_k+2Reference output voltage value of

Instead of the (k + 2) th sampling period T in the formula (8)_k+2Average output voltage V of_o[k+2]The k-th sampling period T is obtained by using the formula (9)_kReference inductor current amplitude of

Wherein the content of the first and second substances,

representing the kth sampling period T_kThe reference inductor current amplitude of (a); t is_vThe control period of the voltage outer ring control system is shown; alpha is alpha_v[k]Is a reference inductance current amplitude coefficient set by a designer;

represents the k +2 th sampling period T_k+2The reference output voltage value of (a); v_o[k]Representing the kth sampling period T_kThe average output voltage value of (1);

representing the kth sampling period T_kThe voltage outer loop controls an estimate of the total disturbance component of the system.

The expression is used to quickly output a stable voltage to a given reference voltage value,

the expression is used for eliminating the total disturbance part existing in the voltage outer loop control system in a feedforward way, and the kth sampling period T is obtained through final calculation_kReference inductor current amplitude of

And the reference current is provided to a reference current generation module.

Further, the step (4) adopts a reference current generation module to perform sampling for the kth sampling period T_kReference inductor current amplitude value

", which comprises the following steps:

at the k-th sampling period T_kIn the method, the kth sampling period T is obtained by using an input voltage sensor_kInput voltage v of_ac[k]. Sampling the kth sampling period T by using a reference current generation module_kInput voltage v of_ac[k]Absolute value processing is carried out, unit sine half-wave is extracted, and the k sampling period T output by the voltage controller is predicted without a model_kReference inductor current amplitude of

Multiplying to obtain the kth sampling period T_kReference inductance current value of

Further, said step (5) "is based on the k-n_FiOne sampling period

", which comprises the following steps:

(51) at the k-th sampling period T_kIn using electricityThe current sensing sensor obtains the kth sampling period T_kOf the inductor current i_L[k]。

(52) At the k-th sampling period T_kIn accordance with the k-n_FiOne sampling period

Duty ratio control signal d [ k-n ]_Fi-2]To the k-2 sampling period T_k-2Duty ratio control signal d [ k-2 ]]Obtaining the kth sampling period T according to equation (10)_kEstimate of the total disturbance component of the current inner loop control system

Wherein the content of the first and second substances,

representing the kth sampling period T_kThe current inner loop control system total disturbance part estimation value; n is_FiRepresenting the length of a data window, and taking a positive integer; k is a positive integer; m is k-n_FiInteger between +1 and k (including k-n)_Fi+1 and k); t is_iThe control period of the current inner loop control system is shown; alpha is alpha_i[k]Is a duty cycle coefficient set by a designer; i.e. i_L[m-1]Represents the m-1 th sampling period T_m-1The inductor current of (1); i.e. i_L[m]Represents the m-th sampling period T_mThe inductor current of (1); d [ m-3 ]]Represents the m-3 th sampling period T_m-3Duty cycle control signal of (1); d [ m-2 ]]Represents the m-2 th sampling period T_m-2Duty cycle control signal of (1); when m is less than or equal to 0, i_L[m-1]＝i_L[m]0; when m is less than or equal to 2, d [ m-3 ]]＝d[m-2]＝0。

Further, said step (6) of controlling the estimated value of the total disturbance part of the system "according to the current inner loop in the k-th sampling period

Duty cycle control signal d [ k ]]And duty ratio coefficient alpha_i[k]Establishing a unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes, and carrying out Euler dispersion on the unified super-local model to obtain a dispersion current equation; ", which comprises the following steps:

(61) an inductance current dynamic equation of the single-phase Boost PFC converter operating in a continuous conduction mode is established by adopting an equation (11):

wherein the content of the first and second substances,

represents the first differential of the inductor current; v. of_o[k]Representing the kth sampling period T_kThe output voltage value of (1); d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); r_LRepresenting an input inductance parasitic resistance value; l represents an input inductance value.

(62) An inductance current dynamic equation of the single-phase Boost PFC converter operating in an intermittent conduction mode is established by adopting an equation (12):

wherein the content of the first and second substances,

represents the first differential of the inductor current; v. of_o[k]Representing the kth sampling period T_kThe output voltage value of (1); d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); l represents an input inductance value; r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle.

(63) According to the inductance current dynamic equations in different conduction modes represented by the equations (11) and (12), the inductance current dynamic equations of the Boost PFC converter can be unified into the equation (13):

wherein the content of the first and second substances,

represents the first differential of the inductor current;

representing the kth sampling period T_kThe non-linear interference part of the inductance current dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; v. of_o[k]Representing the kth sampling period T_kThe output voltage of (1); l represents an input inductance value.

As is apparent from the formulae (11), (12) and (13),

the nonlinear interference part appearing in the inductance current dynamic equation of the single-phase Boost PFC converter operating in different conduction modes can be uniformly expressed, and can be represented by an equation (14):

wherein the content of the first and second substances,

representing the kth sampling period T_kThe non-linear interference part of the inductance current dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); v. of_o[k]Representing the kth sampling period T_kThe output voltage of (1); l represents an input inductance value; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle. Expression formula

Representing a nonlinear interference part appearing in an inductive current equation when the Boost PFC converter operates in a continuous conduction mode; expression formula

And represents the nonlinear interference part in the inductance current equation when the Boost PFC converter operates in the discontinuous conduction mode.

(64) According to the unified inductor current dynamic state of the Boost PFC converter shown in the formula (14), a unified super-local model of the inductor current of the Boost PFC converter can be obtained. Using the kth sampling period T_kEstimate of the total disturbance component of the current inner loop control system

The kth sampling period T_kDuty ratio control signal d [ k ]]And duty ratio coefficient alpha_i[k]Establishing a unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes by adopting a formula (15):

wherein the content of the first and second substances,

represents the first differential of the inductor current;

representing the kth sampling period T_kThe current inner loop control system total disturbance part estimation value; alpha is alpha_i[k]Is a duty cycle coefficient set by a designer; d [ k ]]Representing the kth sampling period T_kThe duty cycle control signal of (1).

(62) Euler dispersion is carried out on a unified super-local model of the inductive current of the single-phase Boost PFC converter system by adopting a formula (16) to obtain a dispersion current equation;

wherein i_L[k+2]Represents the k +2 th sampling period T_k+2The inductor current of (1); i.e. i_L[k]Representing the kth sampling period T_kThe inductor current of (1); t is_iThe control period of the current inner loop control system is shown;

Further, the discrete current equation of Euler dispersion is carried out according to the unified super local model of the inductive current of the single-phase Boost PFC converter system under different conduction modes in the step (7), a model-free predictive current controller is designed, and the model-free predictive current controller is adopted to obtain the kth sampling period T_kDuty ratio control signal d [ k ]](ii) a ", which comprises the following steps:

in order to accurately track the reference inductance current value, the k +2 sampling period T is adopted_k+2Reference inductance current value of

Instead of the (k + 2) th sampling period T in equation (12)_k+2Of the inductor current i_L[k+2]The k-th sampling period T is obtained from the equation (17)_kDuty ratio control signal d [ k ]]；

Wherein d [ k ]]Representing the kth sampling period T_kDuty cycle control signal of (1); t is_iThe control period of the current inner loop control system is shown; alpha is alpha_i[k]Is a duty cycle coefficient set by a designer;

represents the k +2 th sampling period T_k+2The reference inductance current value of (1); i.e. i_L[k]Representing the kth sampling period T_kThe inductor current of (1);

representing the kth sampling period T_kThe inner loop of current control an estimate of the total disturbance component of the system.

According to the technical scheme, the unified super-local model of the single-phase Boost PFC converter operated in different conduction modes is established, the cascade model-free predictive control method is designed, mode identification and control method switching can be avoided, robustness to parameter change and internal and external dynamic interference of the single-phase Boost PFC converter is effectively improved, dynamic and stable state control performance of the single-phase Boost PFC converter in full-power range operation is comprehensively improved, and dynamic response speed of a system control loop is improved.

Drawings

FIG. 1 is a functional block diagram of a control system of the present invention;

FIG. 2 is a flow chart of a method of controlling the present invention;

FIG. 3 is a steady state simulation waveform diagram of the system input current for the cascaded PI control at 20% load rated power;

FIG. 4 is a steady state simulation waveform of system input current for cascaded model-less predictive control at 20% load power rating;

FIG. 5 is a steady state simulation waveform of the system input current for the cascaded PI control at 55% load power rating;

FIG. 6 is a steady state simulation waveform of system input current for cascaded model-less predictive control at 55% load power rating;

FIG. 7 is a steady state simulation waveform of system input current for cascaded model-less predictive control at 85% load rated power;

FIG. 8 is a waveform diagram of the dynamic simulation of the input current and output voltage of the cascaded PI controlled system when the power jumps from 50% load rating to 100% load rating;

FIG. 9 is a waveform diagram of a dynamic simulation of input current and output voltage of a cascaded model-less predictive controlled system when transitioning from 50% load power rating to 100% load power rating;

FIG. 10 is a waveform diagram of the dynamic simulation of the input current and output voltage of the cascaded PI controlled system from 100% load rating to 50% load rating;

FIG. 11 is a waveform diagram of a dynamic simulation of input current and output voltage of a cascaded model-less predictive controlled system when transitioning from 100% load power rating to 50% load power rating;

FIG. 12 is a graph of the total harmonic distortion rate of the input current of a Boost PFC converter for cascade model-less predictive control and cascade PI control;

fig. 13 is a graph of the input current power factor of a Boost PFC converter with cascaded model-less predictive control and cascaded PI control.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

fig. 1 shows a cascaded model-free predictive control system based on a single-phase Boost PFC converter, where the single-phase Boost PFC converter includes a single-phase Boost PFC converter main circuit and the cascaded model-free predictive control system. The main circuit of the single-phase Boost PFC converter comprises an uncontrolled rectifier bridge circuit and a DC-DC BAn oost converter. The uncontrolled rectifier bridge circuit includes a diode D1, a diode D2, a diode D3, and a diode D4. The uncontrolled rectifier bridge circuit is used for inputting an alternating current power supply v_acPrimarily rectifying the wave into an steamed bread wave, and inputting the steamed bread wave into a DC-DC Boost converter. The diode D1 is connected with the diode D3 in series, and the intersection point of the diode D1 and the diode D3 is connected with an alternating current input power supply v_acAre connected with each other at one end. The diode D2 is connected with the diode D4 in series, and the intersection point of the diode D2 and the diode D4 is connected with an alternating current input power supply v_acThe other ends are connected. The cathode of the diode D1 and the cathode of the diode D2 are both connected with the input end of the DC-DC Boost converter, and the anodes of the diode D3 and the diode D4 are both grounded.

The current inner loop control system comprises an input voltage sensor, an inductive current sensor, a reference current generation module, a model-free prediction current controller and a PWM modulation module. The input voltage sensor is used for acquiring an actual input voltage signal and providing the actual input voltage signal to the reference current generation module; the input terminal of the input voltage sensor is connected to the anode of the diode D1, and the output terminal of the input voltage sensor is connected to the input terminal of the reference current generating module. The reference current generation module is used for generating a reference inductance current value; the output end of the reference current generation module is connected with the input end of the model-free prediction current controller. The inductive current sensor is used for acquiring an actual inductive current signal and providing the actual inductive current signal to the model-free predictive current controller. The input end of the inductive current sensor is connected to a branch circuit between the ground end and the source electrode of the power switch device S, and the output end of the inductive current sensor is connected with the input end of the model-free prediction current controller. The model-free predictive current controller is used for controlling the inductive current by generating the duty ratio of the switching tube S, so that the input current is sinusoidal and has the same phase with the alternating-current input voltage, and the output end of the model-free predictive current controller is connected with the input end of the PWM module. The PWM module is used for generating a driving signal of the switching tube S, and the output end of the PWM module is connected with the grid electrode of the power switching device S.

The chinese patent CN109831094B adopts a wave trap to obtain an average output voltage value, which is provided to a subsequent voltage controller, but the wave trap introduces additional phase lag in the voltage outer loop control system, which affects the stability of the voltage outer loop control system. To eliminate this lag, an additional complex compensation algorithm design is required, which is difficult to implement. The average filtering module is adopted to obtain the average output voltage value and provide the average output voltage value for the subsequent voltage controller, and the average filtering module has the advantages of simple algorithm and capability of reducing calculation delay by directly improving the algorithm. When the cascade control system is subjected to external interference such as load change, the control dynamic response is mainly limited by the speed of the dynamic response of the voltage outer ring control module. The PI voltage controller adopted in CN109831094B has the problem of slow dynamic response, and is designed based on an output voltage mathematical model under a stable state and ideal parameters, and its PI gain parameter cannot be adaptively adjusted according to the system conduction mode change and the system parameter change, so that the PI voltage controller may fail to control when confronted with the above changes. The voltage predictive controller is designed based on the super-local voltage model, the predictive control has quick dynamic response, the response speed of the control system can be improved, the super-local voltage model based on the voltage predictive controller is updated in real time along with the change of the system conduction mode and the system parameters, and the sensitive dependence of the predictive control performance on the model accuracy is overcome. Therefore, the model-free prediction voltage controller overcomes the control problem of the traditional PI voltage controller, improves the dynamic response of a voltage outer ring control system, and has excellent control performance under external interferences of system conduction mode change, system parameter change and the like; therefore, the dynamic response speed and the anti-interference capability of the whole cascade control system are finally improved. The cascade model-free predictive control system can avoid the complex design of mode identification and control method switching, effectively improve the robustness to the parameter change and internal and external dynamic interference of the single-phase Boost PFC converter, comprehensively improve the dynamic and steady control performance of the single-phase Boost PFC converter in the full-power range operation, and improve the dynamic response speed of a system control loop.

The working principle of the cascade model-free predictive control system based on the single-phase Boost PFC converter is as follows:

the single-phase Boost PFC converter system is composed of an input power supply v_acAnd supplying power, and obtaining pulsating steamed bread waves through rectification treatment of an uncontrollable diode rectifier bridge. On the power switch device S leadOn time, input power v_acA closed loop is formed by the booster inductor L and the power switch device S, and the booster inductor L stores energy at the moment; the output capacitor C supplies power to the resistive load R, and the output capacitor C discharges at the moment. When the power switch device S is turned off, the input power v_acA closed loop circuit is formed by the input power supply v, the boost inductor L, the fly-wheel diode D, the output capacitor C and the resistive load R_acThe output capacitor C and the resistive load R are supplied with power together with the boost inductor, at the moment, the boost inductor L releases energy, and the output capacitor C stores energy. The method comprises the steps that a power switch device S is controlled to be switched on and off, so that the inductive current of a single-phase Boost PFC converter is controlled to track the reference inductive current value, the unit power factor is realized, and the input current harmonic wave is reduced; the reference inductive current amplitude is generated according to the power conservation principle, and the output voltage is controlled to be stabilized to a given voltage value when the load changes, so that the power factor correction and output voltage stabilization functions of the Boost PFC converter are realized.

The actual output voltage signal is connected with the input end of the output voltage sensor, the output voltage sensor is used for collecting the actual output voltage, the output end of the output voltage sensor is connected with the input end of the average filtering module, the sampled output voltage is input into the average filtering module, the influence of double frequency ripple of the output voltage in the voltage loop is eliminated, and the average output voltage value is obtained. The output end of the average filtering module and the reference output voltage value given by the user are both connected with the input end of the model-free voltage controller, and the average output voltage value and the reference output voltage value are transmitted to the model-free voltage controller.

Model-free predictive voltage controller comprises

A value estimation module and a model-free predictive voltage control algorithm module.

The value estimation module utilizes the average output voltage signal and the reference inductive current amplitude value to carry out operation to generate an estimation value

Model-free predictive voltage control algorithm module utilizing estimated values

And averaging the output voltage signal and the reference output voltage signal to generate a reference inductive current amplitude signal, so that model-free prediction voltage control of the single-phase Boost PFC converter is realized, and the output voltage of the single-phase Boost PFC converter system is stabilized to a rated value.

The method comprises the steps that an actual input voltage signal is connected with an input end of an input voltage sensor, the input voltage sensor is used for collecting the actual input voltage, an output end of the input voltage sensor is connected with an input end of a reference current generation module in a current inner loop control system, a sampled input voltage is input into the reference current generation module, the reference current generation module carries out absolute value operation and unitized operation on the sampled input voltage to obtain a unit sine half-wave sine signal, and the unit sine half-wave sine signal is multiplied by a reference inductance current amplitude signal to obtain a reference inductance current signal. The output end of the reference current generation module is connected with the input end of the model-free prediction current controller, and a reference inductance current signal output by the reference current generation module is input into the model-free prediction current controller. The actual inductive current signal is connected with the input end of the current sensor, the current sensor is used for collecting the actual inductive current, the output end of the current sensor is connected with the input end of the model-free predictive current controller, and the sampled inductive current is input into the model-free predictive current controller.

Model-free predictive current controller comprises

A value estimation module and a model-free predictive current control algorithm module.

The value estimation module utilizes the sampling inductive current signal and the duty ratio control signal to carry out operation to generate an estimation value

Model-free predictive current control algorithm module utilizing estimates

The inductor current signal and the reference inductor current signal are sampled to generate a duty ratio control signal. The output end of the model-free prediction current controller is connected with the input end of the PWM modulation module, and a duty ratio control signal generated by the model-free prediction current controller is input into the PWM modulation module to generate a driving signal of the power switching device. The output end of the PWM modulation module is connected with the grid input end of the power switch device, a driving signal generated by the PWM modulation module is input into the power switch device to drive the power switch device to conduct and shut off, model-free prediction current control of the Boost PFC converter is achieved, and the inductive current of the single-phase Boost PFC converter tracks the reference inductive current value.

As shown in fig. 2, the present invention further relates to a control method of the cascade model-free predictive control system based on the single-phase Boost PFC converter, which includes the following steps:

and S1, the average filtering module is used for obtaining an average output voltage value. According to the k-n_FvOne sampling period

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

Determining the k-th sampling period T_kEstimation of total disturbance part of voltage outer loop control systemValue of

S1 specifically includes the following steps:

s11, in the k sampling period T_kIn the method, the kth sampling period T is obtained by using an output voltage sensor_kIs output voltage v_o[k]。

S12, output voltage v is filtered by utilizing an average filtering module_o[k]An averaging process is performed. The number of sampling points in one output voltage period set by a user is N, and m is defined as the number of output voltage periods. When m is equal to 1, namely in the first output voltage period, the average output voltage value of the first N-1 sampling points is equal to the output voltage sampling value because the output voltage sampling value is not enough to calculate the average output voltage value. The average output voltage value of the Nth sampling point is equal to the average voltage value of the sum of the N output voltage sampling values in the first output voltage period; when m is>And 1, superposing the difference value of the output voltage sampling value at the current sampling point of the mth output voltage period and the output voltage sampling value at the current sampling point of the m-1 output voltage period based on the average output voltage value of the nth sampling point of the m-1 output voltage period to obtain the average output voltage value of the previous N-1 sampling points. And the average output voltage value of the Nth sampling point is equal to the average voltage value of the sum of the N output voltage sampling values of the mth output voltage period, and the average output voltage value of the Nth sampling point is used for correcting the accumulated error calculated by the average output voltage values of the previous N-1 sampling points. The average filtering algorithm does not need to sum and average N output voltage sampling values at each output voltage sampling point, can also obtain relatively accurate average output voltage values, reduces the calculation burden of a control system, and reduces the calculation delay by simplifying the average filtering algorithm. The kth sampling period T can be obtained from equation (1)_kAverage output voltage value V of_o[k]。

Wherein, V_o[mk]Represents the level at the kth sampling point of the mth output voltage cycleAll output voltage values; v. of_{o_mk}The sampling value of the output voltage at the kth sampling point of the mth output voltage period;

an average voltage value representing the sum of the output voltage sampling values of the N sampling points of the mth output voltage period; v_o[(m-1)N]The average voltage value of the Nth sampling point of the m-1 th output voltage period is obtained; v. of_{o_(m-1)k}The sampling value of the output voltage at the kth sampling point of the (m-1) th output voltage period is obtained; n is the number of sampling points in one output voltage period set by a user; m is the number of output voltage cycles, and m is a positive integer; i is an integer between 1 and N.

S13, in the k sampling period T_kIn accordance with the k-n_FvOne sampling period

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

Wherein the content of the first and second substances,

s2, estimating value of total disturbance part of voltage outer loop control system according to k sampling period

Reference inductance current amplitude

And a reference inductance current amplitude coefficient alpha_v[k]And establishing a unified super-local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, and carrying out Euler dispersion on the unified super-local voltage model to obtain a dispersion voltage equation. S2 specifically includes the following steps:

s21, establishing an output voltage dynamic equation of the single-phase Boost PFC converter operating in a continuous conduction mode by adopting an equation (3):

wherein the content of the first and second substances,

S22, establishing an output voltage dynamic equation of the single-phase Boost PFC converter in the discontinuous conduction mode by adopting an equation (4):

wherein the content of the first and second substances,

S23, unifying the output voltage dynamic equations of the Boost PFC converter into equation (5) according to the output voltage dynamic equations in different conduction modes represented by equations (3) and (4):

wherein the content of the first and second substances,

represents the first differential of the output voltage;

As shown in the formulae (3), (4) and (5),

the nonlinear interference part appearing in the output voltage dynamic equation of the Boost PFC converter operating in different conduction modes can be uniformly expressed, and can be represented by an equation (6):

wherein the content of the first and second substances,

The non-linear interference part appearing in the output voltage equation when the Boost PFC converter operates in the discontinuous conduction mode is shown.

And S24, because the Boost PFC converter output voltage unified super-local model expressed by the formula (5) contains frequency-doubled voltage ripples, presents nonlinear time-varying characteristics and is not beneficial to the design of a corresponding output voltage prediction controller, the formula (5) is subjected to integral averaging, nonlinear influence caused by frequency-doubled voltage ripples is eliminated, and the Boost PFC converter output voltage unified super-local model is obtained. Using the kth sampling period T_kEstimate of total disturbance part of voltage outer loop control system

The kth sampling period T_kReference inductor current amplitude of

And a reference inductance current amplitude coefficient alpha_v[k]Establishing a unified super-local model of the output voltage of the Boost PFC converter in different conduction modes, as shown in formula (7):

wherein the content of the first and second substances,

represents the first differential of the average output voltage;

S25, Euler discretization is carried out on the unified super-local model of the voltage of the Boost PFC converter by adopting an equation (7) to obtain a discretization voltage equation:

S3, carrying out Euler discrete voltage equation according to the unified super-local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, designing a model-free predictive voltage controller, and solving the kth sampling period T by adopting the model-free predictive voltage controller_kReference inductor current amplitude of

S3 specifically includes the following steps:

Instead of the (k + 2) th sampling period T in the formula (8)_k+2Output voltage V of_o[k+2]The k-th sampling period T is obtained by using the formula (9)_kReference inductor current amplitude of

Wherein the content of the first and second substances,

And the expression is used for quickly stabilizing the output voltage to a given reference voltage value.

An expression used for eliminating the total disturbance part existing in the voltage outer loop control system in a feedforward way and finally obtaining the kth sampling period T by calculation_kReference inductor current amplitude of

And the reference current is provided to a reference current generation module.

S4, adopting a reference current generation module to sample the kth sampling period T_kReference inductor current amplitude value

Specifically, in the k-th sampling period T_kIn the method, the kth sampling period T is obtained by using an input voltage sensor_kInput voltage v of_ac[k]Using the reference current generation module to sample the kth sampling period T_kInput voltage v of_ac[k]Absolute value processing is carried out, unit sine half-wave is extracted, and the k sampling period T output by the voltage controller is predicted without a model_kReference inductor current amplitude of

S5, according to the k-n_FiOne sampling period

S5 specifically includes the following steps:

s51, in the k sampling period T_kIn the method, the k sampling period T is obtained by using an inductive current sensor_kOf the inductor current i_L[k]。

S52, in the k sampling period T_kIn accordance with the k-n_FiOne sampling period

Wherein the content of the first and second substances,

representing the kth sampling period T_kThe current inner loop control system total disturbance part estimation value; n is_FiRepresenting the length of a data window, and taking a positive integer; k is a positive integer; m is k-n_FiInteger between +1 and k (including k-n)_Fi+1 and k); t is_iThe control period of the current inner loop control system is shown; alpha is alpha_i[k]Is a duty cycle coefficient set by a designer; i.e. i_L[m-1]Represents the m-1 th sampling period T_m-1The inductor current of (1); i.e. i_L[m]Represents the m-th sampling period T_mThe inductor current of (1); d [ m-3 ]]Represents the m-3 thSampling period T_m-3Duty cycle control signal of (1); d [ m-2 ]]Represents the m-2 th sampling period T_m-2Duty cycle control signal of (1); when m is less than or equal to 0, i_L[m-1]＝i_L[m]0; when m is less than or equal to 2, d [ m-3 ]]＝d[m-2]＝0。

S6, controlling the estimation value of the total disturbance part of the system according to the current inner loop in the kth sampling period

Duty cycle control signal d [ k ]]And duty ratio coefficient alpha_i[k]Establishing a unified super-local model of the inductive current of the single-phase Boost PFC converter in different conduction modes, and carrying out Euler dispersion on the unified super-local current model to obtain a dispersion current equation. S6 specifically includes the following steps:

s61, establishing an inductor current dynamic equation of the single-phase Boost PFC converter operating in a continuous conduction mode by adopting the formula (11):

wherein the content of the first and second substances,

S62, establishing an inductance current dynamic equation of the single-phase Boost PFC converter in an intermittent conduction mode by adopting an equation (12):

wherein，

S63, according to the inductor current dynamic equations in different conduction modes represented by equations (11) and (12), the inductor current dynamic equations of the Boost PFC converter can be unified into equation (13):

wherein the content of the first and second substances,

represents the first differential of the inductor current;

As is apparent from the formulae (11), (12) and (13),

wherein the content of the first and second substances,

And S64, obtaining a unified super-local model of the inductive current of the Boost PFC converter according to the unified inductive current dynamic state of the Boost PFC converter shown in the formula (14). Using the kth sampling period T_kEstimate of the total disturbance component of the current inner loop control system

The kth sampling period T_kDuty ratio control signal d [ k ]]And duty ratio coefficient alpha_i[k]Establishing a unified super local current model of the single-phase Boost PFC converter system in different conduction modes by adopting an equation (15):

wherein the content of the first and second substances,

represents the first differential of the inductor current;

S62, Euler discretization is carried out on the unified super-local model of the Boost PFC converter inductive current by adopting a formula (16) to obtain a discretization current equation;

S7, carrying out Euler discrete current equation according to the unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes, designing a model-free predictive current controller, and solving the kth sampling period T by adopting the model-free predictive current controller_kDuty ratio control signal d [ k ]]. S7 specifically includes the following steps:

in order to accurately track the reference inductance current value, the (k + 2) th sampling is adoptedSample period T_k+2Reference inductance current value of

Instead of the (k + 2) th sampling period T in the formula (16)_k+2Of the inductor current i_L[k+2]The k-th sampling period T is obtained by the equation (17)_kDuty ratio control signal d [ k ]]。

Wherein d [ k ]]Representing the kth sampling period T_kDuty cycle control signal of (1); t is_iThe control period of the current inner loop control system is shown; alpha is alpha_i[k]Setting a duty ratio coefficient for a designer;

S8, using PWM modulation module to sample the k-th sampling period T_kDuty ratio control signal d [ k ]]Modulating to obtain the kth sampling period T_kPower switch device driving signal S k]Therefore, the power switching device S of the single-phase Boost PFC converter is controlled to act, and the inductive current control of the single-phase Boost PFC converter is realized. And after the cascade model-free predictive control of the single-phase Boost PFC converter in the kth sampling period is finished, assigning k +1 to k, returning to the step of executing S1, and controlling the next sampling period, thereby realizing the real-time cascade model-free predictive control of the single-phase Boost PFC converter.

Under the cascade control structure, the invention designs the current inner ring and the voltage outer ring independently. Because the linear PI controller has the defects of slow response speed, sensitivity to circuit parameter change, internal and external interference and the like, the traditional PI current controller cannot process complex nonlinearity caused by an intermittent conduction mode, and the input current is seriously distorted. The traditional PI voltage controller cannot respond to the load variation quickly, so that the output voltage is excessively overshot, and the circuit loss is increased. Therefore, in order to improve the quality of input current and improve the response speed of a system, the invention provides a unified super-local model based on a single-phase Boost PFC converter and a control method thereof, and a model-free prediction current controller and a model-free prediction voltage controller are established to improve the dynamic and steady-state performance of the converter in the full power range. The invention provides a Model-Free Predictive Control (MFPC) cascade connection of a single-phase Boost PFC converter, a unified super-local voltage Model (namely the unified super-local Model of the output voltage of the single-phase Boost PFC converter) between a reference inductive current amplitude value and an average output voltage of the converter is established based on the Model-Free Control, a Model-Free Predictive voltage controller of the single-phase Boost PFC converter is designed, an accurate reference inductive current value is provided for a current inner loop, and the output voltage is stabilized; a unified super-local current model (namely a unified super-local model of the inductive current of the single-phase Boost PFC converter) between the duty ratio of the converter and the average inductive current is established based on model-free control, a model-free prediction current controller is designed, a proper duty ratio signal is generated, and the input current power factor is improved. The invention effectively avoids the algorithm design of mode identification and control strategy switching, overcomes the dependence of the controller on system parameters, realizes the control of the inductive current and the output voltage in different conduction modes, reduces the THD of the input current, stabilizes the output voltage and improves the response speed of the whole control system.

In order to verify the effectiveness of the control method of the cascade model-free predictive control system, Matlab/simulink simulation is carried out, and the specific process of the Matlab/simulink simulation is as follows:

a simulation model of a control system of a cascade model-free predictive control single-phase Boost PFC converter shown in FIG. 1 is established through Matlab/simulink software. The parameters of the main circuit of the converter are as follows: load rated power 1000W, AC input voltage 110V/50Hz, DCThe output voltage is 360V, the boost inductor is 500 muH, the output capacitor is 990 muF, the switching frequency is 50kHz, the current inner loop control period is 0.02ms, and the voltage outer loop control period is 0.5 ms. And respectively designing a cascaded PI controller and a cascaded model-free predictive controller based on the same circuit parameters and an average filtering module. In order to give consideration to system stability and dynamic response speed, the bandwidth of a PI current controller of a selected current inner loop control system in the cascade PI control system is 17279rad/s, the phase margin is 45 degrees, and the corresponding control parameter K is_p＝0.0241，K_i109.9707; the bandwidth of a PI voltage controller of the selective voltage outer ring control system is 79rad/s, the phase margin is 45 degrees, and the corresponding control parameter K is_p＝0.2643，K_i19.531. Estimation value of model-free predictive current controller in cascade model-free predictive control system

Length n of the data window_Fi＝12，α_i[k]Is selected as

Model-free predictive voltage controller estimation

Length n of the data window_Fi＝15，α_v[k]Is selected as

V_ac[k]The converter input voltage amplitude is determined. The number of sampling points N in the average filtering module is 20.

The results of the Matlab/simulink system simulation studies are shown in FIGS. 3-13, where i_acRepresenting the input current of the converter, i_ac ^refRepresenting the reference input current, v, of the converter_oRepresenting the output voltage of the converter. When the load runs at 20% rated power, the current conduction mode is MCM, the input current waveform of the cascade PI controlled Boost PFC converter system is shown in FIG. 3, the input current has serious distortion, and the main reason is that the response speed of the PI current controller is not highAnd the PI current control effect is not good enough when the DCM region operates. The input current waveform of the system of the cascade model-free predictive control Boost PFC converter is shown in FIG. 4, and compared with the control effect of the cascade PI control, the distortion condition of the input current of the system of the cascade model-free predictive control is improved, and the reason is that the model-free predictive current controller has quick response speed and effectively controls the current in a DCM operation area. Fig. 5 and 6 show input current waveforms of a system load of the cascade PI control and the cascade model-free predictive control respectively at 55% of rated power, the converter works in CCM, and compared with the cascade PI control, the input current of the system of the cascade model-free predictive control has a better sinusoidal waveform, and the reason for this is that the gain design of the PI current controller is based on an accurate and ideal mathematical model, while the model-free predictive current controller can be adaptive to internal and external interference and parameter variation of the system, and the input current tracking is more accurate. As shown in fig. 7, the input current of the input current waveform of the system load of the cascade model-free predictive control at 85% of rated power realizes good tracking of the reference input current. FIG. 8 shows dynamic waveforms of output voltage and input current of a cascaded PI control system with the load power ramping from 50% rated power to 100% rated power; FIG. 9 shows dynamic waveforms of output voltage and input current of the cascaded predictive control system with the load power ramping from 50% rated power to 100% rated power; fig. 10 and 11 show dynamic waveforms of the cascaded PI control system and the model-free predictive control system, respectively, in which the load power jumps from 100% rated power to 50% rated power. The results show that: when load power jump occurs, compared with a cascade PI control system, the output voltage of the single-phase Boost PFC converter is high in response speed and short in stabilization time, and the main reason is that the model-free prediction voltage controller has high response speed and can effectively control the output voltage in a DCM operation area. Fig. 12 and 13 show the total harmonic distortion and the power factor of the input current of the Boost PFC converter under different load powers and different control methods. Fig. 12 and 13 clearly show that the system control effect of the cascade model-free predictive control system and the control method thereof provided by the invention is better than that of PI control on the whole, especially in low-load power output of the systemWhen the output current is output, the THD value and the PF value of the input current are obviously improved by model-free predictive control, and the quality of the input current of the single-phase Boost PFC converter is obviously optimized. In view of the above, the proposed cascaded model-free predictive control enables the controlled single-phase Boost PFC converter system to have both superior dynamic control performance and steady-state operation performance.

According to the invention, a unified super-local model of the output voltage of the single-phase Boost PFC converter operating in different conduction modes is established, and a model-free predictive voltage controller is designed, so that the robustness of the voltage outer ring control system on the total disturbance of the output voltage dynamic system is improved, and the dynamic response speed of the voltage outer ring control loop is improved. A model-free prediction current controller is designed based on a unified super-local model of the inductive current of the single-phase Boost PFC converter, so that the current control performance of the converter under the medium-light load operation condition can be effectively improved, the input current distortion is reduced, and the steady-state performance of a current inner loop control system is improved. And the voltage outer ring control system is combined with the current inner ring control system to form a cascade model-free predictive control system of the single-phase Boost PFC converter. By establishing the unified super-local model, the complex design of mode identification and control method switching is effectively avoided, the dependence and robustness of a controller on system parameters are overcome, and the dynamic and stable control performance of the single-phase Boost PFC converter in the full-power range operation is comprehensively improved.

The innovation point of the invention is that a voltage outer ring control system is designed: an average filtering module is adopted to filter double-frequency ripple voltage in the output voltage of the single-phase Boost PFC converter, so that the ripple voltage is prevented from polluting the amplitude of the reference inductive current, the calculation delay of a controller is reduced, and the stability of a system is enhanced; and designing a model-free predictive voltage controller based on the established unified super-local model of the output voltage of the single-phase Boost PFC converter operating in different conduction modes, and improving the robustness of the voltage outer ring control system to the total disturbance of the output voltage dynamic system and the dynamic response speed of the voltage outer ring control loop. The method is combined with a current inner-loop control system comprising a model-free prediction current control method to form a cascade model-free prediction control system of the single-phase Boost PFC converter, so that the complex design of conduction mode identification and control method switching can be avoided, the robustness to the change of single-phase Boost PFC conversion parameters and internal and external dynamic interference is effectively improved, and the dynamic control performance of the single-phase Boost PFC converter in the full-power-range operation is comprehensively improved. The average filtering module in step S1 of the present invention is used to obtain the average output voltage value, so as to reduce the calculation delay with a simple algorithm. In step S2, a super-local voltage model is established, the total disturbance part caused by the conduction mode and parameter change of the voltage outer-loop control system is updated and estimated in real time, and the sensitive dependence of the control performance of the controller on the model accuracy is overcome. Step S3 is based on the super-local voltage model, a model-free prediction voltage controller is designed, and the dynamic response and robustness of the voltage outer loop control system are improved. According to the invention, by designing an average filtering module algorithm and a model-free prediction voltage controller, the dynamic response of a voltage outer ring control system is promoted, the robustness of the control system under external interferences such as conduction mode change, system parameter change and the like is enhanced, the dynamic and stable state control performance of the single-phase Boost PFC converter in the full-power range operation is comprehensively improved, and the dynamic response speed of a system control loop is increased.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.

Claims

1. The cascade model-free predictive control system based on the single-phase Boost PFC converter is characterized in that: the single-phase Boost PFC converter comprises a single-phase Boost PFC converter main circuit and a cascade model-free predictive control system;

the single-phase Boost PFC converter main circuit comprises an uncontrolled rectifier bridge circuit and a DC-DC Boost converter; the uncontrolled rectifier bridge circuit comprises a diode D1, a diode D2, a diode D3 and a diode D4; the diode D1 is connected with the diode D3 in series, and the intersection point of the diode D1 and the diode D3 is connected with an alternating current input power supply v_acOne ends of the two are connected; the diode D2 is connected with the diode D4 in series, and the intersection point of the diode D2 and the diode D4 is connected with alternating currentInput power v_acThe other ends of the two are connected; the cathode of the diode D1 and the cathode of the diode D2 are both connected with the input end of the DC-DC Boost converter, and the anodes of the diode D3 and the diode D4 are both grounded; the DC-DC Boost converter comprises a Boost inductor L, a power switch device S, a freewheeling diode D, an output capacitor C and a resistive load R; one end of a Boost inductor L at the input side of the DC-DC Boost converter is the input end of the DC-DC Boost converter, and the other end of the Boost inductor L is respectively connected with the anode of a freewheeling diode D and the drain of a power switch device S; the source electrode of the power switch device S is grounded, and the grid electrode of the power switch device S is connected with the output end of a PWM (pulse-width modulation) module in the cascade model-free predictive control system; the cathode of the freewheeling diode D is connected with one end of the output capacitor C, and the other end of the output capacitor C is grounded; the resistive load R is connected in parallel at two ends of the output capacitor C;

the cascade model-free predictive control system comprises a voltage outer loop control system and a current inner loop control system; the voltage outer ring control system comprises an output voltage sensor, an average filtering module and a model-free prediction voltage controller; the input end of the output voltage sensor is connected with the cathode of the freewheeling diode D, and the output end of the output voltage sensor is connected with the average filtering module; the input end of the average filtering module is connected with the output end of the output voltage sensor, and the output end of the average filtering module is connected with the first input end of the model-free prediction voltage controller; the second input end of the model-free prediction voltage controller is connected with a reference output voltage value given by a user, and the output end of the model-free prediction voltage controller is connected with the first input end of the reference current generation module;

the current inner loop control system comprises an input voltage sensor, an inductive current sensor, a reference current generation module, a model-free prediction current controller and a PWM (pulse width modulation) module; the input end of the input voltage sensor is connected with the anode of the diode D1, and the output end of the input voltage sensor is connected with the second input end of the reference current generation module; the output end of the reference current generation module is connected with the first input end of the model-free prediction current controller; the input end of the inductive current sensor is connected to a branch circuit between the ground end and the source electrode of the power switch device S, and the output end of the inductive current sensor is connected with the second input end of the model-free prediction current controller; the output end of the model-free prediction current controller is connected with the input end of the PWM module; and the output end of the PWM modulation module is connected with the grid electrode of the power switch device S.

2. The control method of the cascade model-free predictive control system based on the single-phase Boost PFC converter according to claim 1, characterized in that: the method comprises the following steps:

(1) obtaining an average output voltage value by using an average filtering module; according to the k-n_FvOne sampling period

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

Wherein k is a positive integer;

Reference inductance current amplitude

And a reference inductance current amplitude coefficient alpha_v[k]Establishing a unified super-local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, and carrying out Euler dispersion on the unified super-local model to obtain a dispersion voltage equation;

Stabilizing the output voltage of the single-phase Boost PFC converter system to a rated value;

(5) According to the k-n_FiOne sampling period

Duty ratio control signal d [ k-n ]_Fi-2]To the k-2 sampling period T_k-2Duty ratio control signal d [ k-2 ]]To find the kth sampling period T_kTotal disturbance part of current inner loop control systemIs estimated value of

Duty cycle control signal d [ k ]]And duty ratio coefficient alpha_i[k]Establishing a unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes, and carrying out Euler dispersion on the unified super-local model to obtain a dispersion current equation;

(7) carrying out Euler discrete current equation according to a unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes, designing a model-free predictive current controller, and solving the kth sampling period T by adopting the model-free predictive current controller_kDuty ratio control signal d [ k ]]；

3. The control method of the cascade model-free predictive control system based on the single-phase Boost PFC converter according to claim 2, characterized in that: the average filtering module is utilized to obtain an average output voltage value in the step (1); according to the k-n_FvOne sampling period

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

Wherein k is a positive integer; ", which comprises the following steps:

(11) at the k-th sampling period T_kIn the method, the kth sampling period T is obtained by using an output voltage sensor_kIs output voltage v_o[k]；

(12) Using an averaging filter module to average the output voltage v_o[k]Carrying out averaging processing; the k sampling period T is obtained by the formula (1)_kAverage output voltage value V of_o[k]；

an average voltage value representing a sum of output voltage sample values at N sample points of an mth output voltage period; v_o[(m-1)N]Is the average voltage value at the Nth sampling point of the m-1 th output voltage period; v. of_{o_(m-1)k}The sampling value of the output voltage at the kth sampling point of the (m-1) th output voltage period is obtained; n is set by the userThe number of sampling points in one output voltage period; m is the number of output voltage cycles, and m is a positive integer; i is an integer between 1 and N;

Reference inductor current amplitude of

To the k-2 sampling period T_k-2Reference inductor current amplitude of

Wherein the content of the first and second substances,

representing the kth sampling period T_kThe estimated value of the total disturbance part of the voltage outer loop control system; n is_FvRepresenting the length of a data window, and taking a positive integer; k is a positive integer; m is k-n_FvBetween +1 and k comprises k-n_FvAn integer of +1 and k; t is_vThe control period of the voltage outer ring control system is shown; alpha is alpha_v[k]To design forThe set reference inductance current amplitude coefficient is obtained; v_o[m-1]Represents the m-1 th sampling period T_m-1The average output voltage value of (1); v_o[m]Represents the m-th sampling period T_mThe average output voltage value of (1);

4. the control method of the cascaded model-free predictive control system based on the single-phase Boost PFC converter according to claim 3, characterized in that: the estimated value of the total disturbance part of the voltage outer loop control system according to the k sampling period in the step (2)

Reference inductance current amplitude

wherein the content of the first and second substances,

represents the first differential of the output voltage; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); i.e. i_o[k]Representing the kth sampling period T_kThe load current of (1); c represents an output capacitance value;

(22) an output voltage dynamic equation of the single-phase Boost PFC converter operating in an intermittent conduction mode is established by adopting an equation (4):

wherein the content of the first and second substances,

represents the first differential of the output voltage; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Representing the kth sampling period T_kThe inductor current of (1); i.e. i_o[k]Representing the kth sampling period T_kThe load current of (1); c represents an output capacitance value; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); l represents an input inductance value; r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle;

(23) according to output voltage dynamic equations in different conduction modes represented by the formulas (3) and (4), the output voltage dynamic equations of the Boost PFC converter are unified by adopting a formula (5):

wherein the content of the first and second substances,

represents the first differential of the output voltage;

representing the kth sampling period T_kThe nonlinear interference part of the output voltage dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); c represents an output capacitance value;

as shown in the formulae (3), (4) and (5),

the nonlinear interference parts appearing in the output voltage dynamic equation of the single-phase Boost PFC converter operating in different conduction modes are uniformly expressed by the following expression (6):

wherein the content of the first and second substances,

representing the kth sampling period T_kThe nonlinear interference part of the output voltage dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); i.e. i_o[k]Representing the kth sampling period T_kThe load current of (1); c represents an output capacitance value; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); l represents an input inductance value; r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle;

indicating that Boost PFC converter is operating in continuous conductionIn the on mode, outputting a nonlinear interference part appearing in a voltage equation;

representing a nonlinear interference part appearing in an output voltage equation when the Boost PFC converter operates in an intermittent conduction mode;

(24) carrying out integral averaging on the formula (5), eliminating nonlinear influence caused by double frequency voltage ripples, and obtaining a unified super-local model of the output voltage of the Boost PFC converter; using the kth sampling period T_kEstimate of total disturbance part of voltage outer loop control system

The kth sampling period T_kReference inductor current amplitude of

wherein the content of the first and second substances,

represents the first differential of the average output voltage;

representing the kth sampling period T_kThe estimated value of the total disturbance part of the voltage outer loop control system; alpha is alpha_v[k]Setting a reference inductance current amplitude coefficient for a designer;

representing the kth sampling period T_kReference inductance ofThe current amplitude;

5. The control method of the cascaded model-free predictive control system based on the single-phase Boost PFC converter according to claim 4, characterized in that: performing Euler discrete voltage equation according to the unified super-local model of the output voltage of the single-phase Boost PFC converter system in different conduction modes, designing a model-free predictive voltage controller, and calculating the kth sampling period T by using the model-free predictive voltage controller_kReference inductor current amplitude of

Instead of the (k + 2) th sampling period T in the formula (8)_k+2Average output voltage V of_o[k+2]And the k-th sampling period T is obtained by using the formula (9)_kReference inductor current amplitude of

Wherein the content of the first and second substances,

representing the kth sampling period T_kThe reference inductor current amplitude of (a); t is_vThe control period of the voltage outer ring control system is shown; alpha is alpha_v[k]Setting a reference inductance current amplitude coefficient for a designer;

representing the kth sampling period T_kThe estimated value of the total disturbance part of the voltage outer loop control system;

the voltage stabilizing circuit is used for rapidly stabilizing an output voltage to a given reference voltage value;

the total disturbance part existing in the voltage outer loop control system is eliminated by feedforward and finally calculatedTo the kth sampling period T_kReference inductor current amplitude of

And the reference current is provided to a reference current generation module.

6. The control method of the cascaded model-free predictive control system based on the single-phase Boost PFC converter according to claim 5, characterized in that: step (4) said "adopt the reference current generation module, to the k sampling period T_kReference inductor current amplitude value

The method specifically comprises the following steps:

at the k-th sampling period T_kIn the method, the kth sampling period T is obtained by using an input voltage sensor_kInput voltage v of_ac[k](ii) a Sampling the kth sampling period T by using a reference current generation module_kInput voltage v of_ac[k]Absolute value operation is carried out, unit sine half-wave is extracted, and the k sampling period T output by the model-free prediction voltage controller is compared with the k sampling period T output by the model-free prediction voltage controller_kReference inductor current amplitude of

7. The control method of the cascaded model-free predictive control system based on the single-phase Boost PFC converter according to claim 6, characterized in that: the root mentioned in step (5)According to the k-n_FiOne sampling period

The method specifically comprises the following steps:

(51) at the k-th sampling period T_kIn the method, the k sampling period T is obtained by using an inductive current sensor_kOf the inductor current i_L[k]；

Duty ratio control signal d [ k-n ]_Fi-2]To the k-2 sampling period T_k-2Duty ratio control signal d [ k-2 ]]The k-th sampling period T is obtained by using the formula (10)_kEstimate of the total disturbance component of the current inner loop control system

Wherein the content of the first and second substances,

representing the kth sampling period T_kThe current inner loop control system total disturbance part estimation value; n is_FiRepresenting the length of a data window, and taking a positive integer; k is a positive integer; m is k-n_FiInteger between +1 and k (including k-n)_Fi+1 and k); t is_iThe control period of the current inner loop control system is shown; alpha is alpha_i[k]Setting a duty ratio coefficient for a designer; i.e. i_L[m-1]Represents the m-1 th sampling period T_m-1The inductor current of (1); i.e. i_L[m]Represents the m-th sampling period T_mThe inductor current of (1); d [ m-3 ]]Represents the m-3 th sampling period T_m-3Duty cycle control signal of (1); d [ m-2 ]]Represents the m-2 th sampling period T_m-2Duty cycle control signal of (1); when m is less than or equal to 0, i_L[m-1]＝i_L[m]0; when m is less than or equal to 2, d [ m-3 ]]＝d[m-2]＝0。

8. The control method of the cascaded model-free predictive control system based on the single-phase Boost PFC converter according to claim 7, characterized in that: said in step (6)' controlling the estimated value of the total disturbance part of the system according to the current inner loop in the k sampling period

(61) establishing an inductor current dynamic equation of the single-phase Boost PFC converter operating in a continuous conduction mode by adopting a formula (11);

wherein the content of the first and second substances,

represents the first differential of the inductor current; v. of_o[k]Representing the kth sampling period T_kThe output voltage value of (1); d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); r_LRepresenting an input inductance parasitic resistance value; l represents an input inductance value;

wherein the content of the first and second substances,

represents the first differential of the inductor current; v. of_o[k]Representing the kth sampling period T_kThe output voltage value of (1); d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Is the kth sampling period T_kThe inductor current of (1); v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); l represents an input inductance value; r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle;

(63) according to the inductance current dynamic equations in different conduction modes represented by the formulas (11) and (12), unifying the inductance current dynamic equation of the Boost PFC converter into a formula (13):

wherein the content of the first and second substances,

represents the first differential of the inductor current;

representing the kth sampling period T_kThe non-linear interference part of the inductance current dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; v. of_o[k]Representing the kth sampling period T_kThe output voltage of (1); l represents an input inductance value;

as is apparent from the formulae (11), (12) and (13),

the nonlinear interference parts appearing in inductance current dynamic equations of the single-phase Boost PFC converter operating in different conduction modes are represented in a unified way and are all represented by the formula (14):

wherein the content of the first and second substances,

representing the kth sampling period T_kThe non-linear interference part of the inductance current dynamic equation under different conduction modes; d [ k ]]Representing the kth sampling period T_kThe duty ratio control signal of the switching tube S; i.e. i_L[k]Representing the kth sampling period T_kThe inductor current of (1); v. of_o[k]Representing the kth sampling period T_kThe output voltage of (1); l represents an input inductance value; v. of_in[k]Representing the kth sampling period T_kThe input voltage value of (1); r_LRepresenting an input inductance parasitic resistance value; t is_swIs one switching cycle;

representing a nonlinear interference part appearing in an inductive current equation when the Boost PFC converter operates in a continuous conduction mode;

representing a nonlinear interference part appearing in an inductive current equation when a Boost PFC converter operates in an intermittent conduction mode;

(64) obtaining a unified super-local model of the inductive current of the Boost PFC converter according to the unified inductive current dynamic of the Boost PFC converter shown in the formula (14); using the kth sampling period T_kEstimate of the total disturbance component of the current inner loop control system

The kth sampling period T_kDuty ratio control signal d [ k ]]And duty ratio coefficient alpha_i[k]Establishing a unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes by adopting a formula (15);

wherein the content of the first and second substances,

represents the first differential of the inductor current;

representing the kth sampling period T_kThe current inner loop control system total disturbance part estimation value; alpha is alpha_i[k]Setting a duty ratio coefficient for a designer; d [ k ]]Representing the kth sampling period T_kDuty cycle control signal of (1);

9. The method of claim 8, wherein the method comprises: performing Euler discrete current equation according to the unified super-local model of the inductive current of the single-phase Boost PFC converter system in different conduction modes, designing a model-free predictive current controller, and solving the kth sampling period T by using the model-free predictive current controller_kDuty ratio control signal d [ k ]](ii) a ", which comprises the following steps:

Instead of the (k + 2) th sampling period T in the formula (16)_k+2Of the inductor current i_L[k+2]And the k-th sampling period T is obtained by using the formula (17)_kDuty ratio control signal d [ k ]]；

representing the kth sampling period T_kThe current inner loop control system total disturbance part estimation value;

the current tracking control circuit is used for controlling the actual inductive current to track the reference inductive current value and realizing the unit power factor;

the method is used for eliminating the total disturbance part existing in the current inner loop control system in a feedforward mode, and finally obtaining the kth sampling period T through calculation_kReference inductor current amplitude of

And the reference current is provided to a reference current generation module.