Cascadeless cooperative control method and system for Boost PFC converter based on hyperlocal model

Abstract

The present invention relates to a cascadeless cooperative control method and system for a Boost PFC converter based on a hyperlocal model, which solves the problem of static error in the average output voltage compared to the prior art. The present invention includes the following steps: Boost PFC converter data and average filtering processing; establishing a hyperlocal model and performing load current estimation; generating a cascadeless cooperative control duty cycle control law; and cascadeless cooperative control of the Boost PFC converter. The present invention can effectively improve the steady-state control accuracy of the Boost PFC converter output voltage, and has the technical advantages of a simple control structure and strong resistance to load disturbances under sudden changes in load power, thereby comprehensively improving the dynamic control performance and steady-state operation performance of the Boost PFC converter.

Description

Technical Field

[0001] The present invention relates to the technical field of Boost PFC converters, and in particular to a cascade-free cooperative control method and system of a Boost PFC converter based on a super-local model. Background Art

[0002] To meet harmonic requirements for power equipment connected to the grid, as mandated by international standards and grid codes, power factor correction (PFC) converters have garnered significant research attention. Boost PFC converters, due to their compact size, lightweight, high efficiency, and minimal conduction losses, have become the primary circuit topology for implementing power factor correction in medium- and high-power applications. Control strategies for boost PFC circuits are typically based on a dual closed-loop structure, consisting of a low-bandwidth outer voltage loop and a high-bandwidth inner current loop. Traditional boost PFC converter voltage control systems primarily design a PI voltage controller based on the converter's mathematical model. This controller actively reduces bandwidth to limit the passage of double-frequency voltage ripple. However, when the load changes, the low-bandwidth PI voltage control results in a slow dynamic response of the system output voltage, resulting in large overshoots and a long stabilization time. This increases circuit losses and can even damage circuit components.

[0003] To achieve low harmonic distortion in the Boost PFC converter's steady-state input current while ensuring rapid convergence of the output voltage during dynamic operation, Chinese patent CN112350565B employs a cascaded model-free predictive control system to design the control of the outer voltage loop and inner current loop. The outer voltage loop indirectly maintains the converter's output voltage stability by providing a reference value for the inner current loop. However, due to the low bandwidth of the outer voltage control loop, this indirect control of the output voltage affects the overall system's dynamic performance. Boost PFC converters suffer from component conduction voltage drops, resistive losses, and switching losses, leading to poor steady-state control accuracy in the cascaded model-free control system. Furthermore, the control system requires a dual closed-loop cascade control structure, comprising the inner current loop and the outer voltage loop, resulting in a complex control structure.

[0004] Cooperative control, a highly promising control method, boasts a simple control structure and flexible implementation. It can also improve the steady-state accuracy of the system's output voltage by varying the design of macro variables. Due to differences in steady-state control accuracy among different control strategies, cooperative control faces a challenge in manifold design. The control of the input voltage and input current of a boost PFC converter directly impacts system control performance. Therefore, the most classic manifold design is to design the manifold as a linear combination of the output voltage error term and the inductor current error term. Given that boost PFC converters are affected by factors such as component conduction voltage drops, resistor losses, and switching losses in actual operation, cooperative control based on traditional macro variable designs exhibits a static error in the average output voltage. Therefore, an integral term for the output voltage error is added to the traditional macro variable design to eliminate the static error in the average output voltage caused by factors such as component conduction voltage drops, resistor losses, and switching losses. Cascade-free cooperative control can effectively improve the steady-state control accuracy of the boost PFC converter's output voltage. It also offers the technical advantages of a simple control structure and strong resistance to load disturbances under sudden load power fluctuations, comprehensively improving the dynamic control and steady-state performance of boost PFC converters. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems in the prior art such as the complexity of the dual closed-loop cascade control structure using a current inner loop and a voltage outer loop, the low bandwidth of the outer voltage control loop, the indirect control of the output voltage affecting the dynamic performance of the entire system, and the static error in the average output voltage caused by factors such as component conduction voltage drop, resistance loss and switching loss. A cascade-free collaborative control method for a Boost PFC converter based on a super-local model is provided to solve the above problems.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A cascade-free cooperative control method for a Boost PFC converter based on a hyperlocal model comprises the following steps:

[0008] 11) Boost PFC Converter Data and Average Filtering: Obtain the Boost PFC converter parameters, including the boost inductor L, output capacitor C, resistive load R, freewheeling diode D, and power switch S. Establish the average state-space equation for the Boost PFC converter in continuous conduction mode, and use the average filtering module to filter the output voltage double frequency ripple.

[0009] 12) Establishing a hyperlocal model and estimating the load current: Based on the average state space equation of the single-phase Boost PFC converter, the uncertainty part F of the output voltage hyperlocal model is used.v , the uncertain part F of the inductor current hyperlocal model i , reference inductor current amplitude Duty cycle coefficient α i , reference inductor current amplitude coefficient α v , establish a hyperlocal model of the Boost PFC converter output voltage and inductor current; use the load current estimation module to estimate the load current;

[0010] 13) Generation of the Duty Cycle Control Law for Cascadeless Cooperative Control: Based on a hyperlocal model of the Boost PFC converter, macro variables are designed, including the output voltage error term, the inductor current error term, and the output voltage error integral term. Dynamic evolution equations are designed to ensure that the system converges to a manifold. The duty cycle control law for cascadeless cooperative control is generated based on the designed dynamic evolution equations and the duty cycle required for system operation.

[0011] 14) Cascadeless cooperative control of Boost PFC converter: The duty cycle control signal is modulated by the PWM modulation module to obtain the power switch device drive signal s[k] of the kth cycle, and the action of the power switch tube S of the Boost PFC converter is controlled to realize the cascadeless cooperative control of the Boost PFC converter based on the super-local model.

[0012] The Boost PFC converter data and average filtering process comprises the following steps:

[0013] 21) Obtaining Boost PFC converter parameters;

[0014] 22) Use equation (1) to establish the dynamic equation of the inductor current of the single-phase Boost PFC converter operating in continuous conduction mode;

[0015]

[0016] Among them, di L / dt represents the first-order differential of the inductor current; L represents the boost inductor value; v in Indicates input voltage; v o represents the output voltage; d represents the duty cycle control signal of the switch tube S;

[0017] 23) Use equation (2) to establish the output voltage dynamic equation of the single-phase Boost PFC converter operating in continuous conduction mode;

[0018]

[0019] Among them, dv o / dt represents the first-order differential of the output voltage; C represents the output capacitance value; iL represents the inductor current; i o represents the load current; d represents the duty cycle control signal of the switch tube S;

[0020] 24) Use the average filter module to adjust the output voltage v o [k] is averaged; the kth sampling period T is obtained using formula (3) k The average output voltage V o [k];

[0021]

[0022] Among them, V o [mk] represents the average output voltage value at the kth sampling point of the mth output voltage cycle; v o_m k is the output voltage sampling value at the kth sampling point in the mth output voltage cycle; Represents the average voltage value of the sum of the output voltage sampling values ​​at N sampling points in the mth output voltage cycle; V o [(m-1)N] is the average voltage value at the Nth sampling point in the m-1th output voltage cycle; v o_(m-1)k is the output voltage sampling value at the kth sampling point in the m-1th output voltage cycle; N is the number of sampling points in an output voltage cycle set by the user; m is the number of output voltage cycles, m is a positive integer; i is an integer between 1 and N.

[0023] The establishing of the hyperlocal model and the load current estimation comprises the following steps:

[0024] 31) According to model-free control theory, the first-order hyperlocal model of a single-input single-output system is expressed as Equation (4);

[0025]

[0026] Where u and y represent the input and output of the system respectively; α is the scaling factor of the system input; F contains the known and unknown parts of the system;

[0027] 32) Establish a hyperlocal model of the inductor current in a Boost PFC converter;

[0028]

[0029]

[0030] Among them, di L / dt represents the first-order differential of the inductor current; α i represents the duty cycle coefficient; d represents the duty cycle control signal of the switch tube S; F irepresents the known and unknown parts of the inductor current hyperlocal model; C i Represents an adjustable constant parameter; L n is the rated inductance of the input inductor; L represents the boost inductor; v in Indicates input voltage; v o Indicates the output voltage;

[0031] 33) When the switch tube S is turned on, the freewheeling diode does not work; when the switch tube S is turned off, the freewheeling diode works. The freewheeling diode and the inductor current have the following relationship:

[0032]

[0033] 34) Assuming that all signals in the output voltage state equation are averaged to eliminate the impact of the system's double frequency ripple and ignoring internal losses in the system, the average input power and average output power are expressed by the following equations:

[0034]

[0035] Among them, P in Indicates the average input power of the system; V in Indicates the amplitude of the input voltage; Represents the amplitude of the reference inductor current; P o Indicates the average output power of the system; Indicates the amplitude of the reference output voltage; I D represents the average diode current;

[0036] 35) According to the principle of conservation of power P in =P o , derive the average diode current I D The expression is:

[0037]

[0038] Among them, I D represents the average diode current; V in Indicates the amplitude of the input voltage; Indicates the amplitude of the reference output voltage; Indicates the amplitude of the reference inductor current;

[0039] 36) Rearranging the dynamic equation of the output voltage (2), the average state equation of the output voltage is expressed as:

[0040]

[0041] Among them, dv o / dt represents the first-order differential of the output voltage; Vin Indicates the amplitude of the input voltage; C indicates the output capacitance; Indicates the amplitude of the reference output voltage; Represents the amplitude of the reference inductor current; i o Indicates load current;

[0042] 37) Establish a hyperlocal model of the output voltage of the Boost PFC converter;

[0043]

[0044]

[0045] Among them, dv o / dt represents the first-order differential of the output voltage; α v Represents the reference inductor current amplitude coefficient; Indicates the amplitude of the reference inductor current; F v Represents the known and unknown parts of the output voltage; C v Indicates the control gain set to adjust the output voltage; V in Indicates the amplitude of the input voltage; C n is the rated capacitance value of the output capacitor; Indicates the amplitude of the reference output voltage; C indicates the output capacitance; i o Indicates load current;

[0046] 38) Using differential algebraic methods to calculate F i and F v Make an estimate and use and Represents its estimated value, and the expression of formula (13) is obtained

[0047]

[0048] Among them, T s is the control period; T F =n F T s is the sliding window length, n F is a constant and is set to 12; in a shorter sampling interval, it is considered and is a constant, whose differential is approximately 0; v o (τ) represents the output voltage at time τ; i L (τ) represents the inductor current at time τ; d(τ) represents the duty cycle control signal at time τ;

[0049] 39) To quickly generate the reference current amplitude, the complex trapezoidal formula and differential algebraic method are applied to realize the output current i oThe online estimation of the load current is obtained as follows:

[0050]

[0051] in, Represents the estimated value of the load current; T F =n F T s is the sliding window length; C represents the output capacitance; v o (τ) represents the output voltage at time τ; i L (τ) represents the inductor current at time τ; d(τ) represents the duty cycle control signal at time τ.

[0052] The generation of the cascade-free cooperative control duty cycle control law includes the following steps:

[0053] 41) The macro variables of the Boost PFC converter cooperative control system are set as the linear combination of the inductor current error term, the output voltage error term and the integral term of the output voltage error term. The macro variables are designed as shown in formula (15):

[0054]

[0055] Among them, ψ represents the macro variable of the system; i L represents the inductor current; represents the reference inductor current; k1, k2, and k3 represent the control parameters of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively;

[0056] 42) Differentiate the macro variables to obtain the expression of formula (16);

[0057]

[0058] Among them, dψ / dt represents the differential of the macro variable; di L / dt represents the differential of the inductor current; dv o / dt represents the differential of the output voltage; represents the reference output voltage; k1, k2, and k3 represent the control parameters of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively;

[0059] 43) The dynamic evolution equation of the system converging to the manifold is assumed to be as shown in Equation (17):

[0060]

[0061] Where T represents the convergence time constant of the system toward the manifold surface, T>0; Represents the derivative of a macro variable;

[0062] 44) By solving equations (15) to (17), the duty cycle control law of non-cascaded cooperative control is obtained as equation (18);

[0063]

[0064] Where d represents the duty cycle control signal; ψ represents the macro variable; k1, k2, and k3 represent the control parameters of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively; and T represents the convergence time constant of the system toward the manifold surface. represents the estimated value of the uncertain part of the hyperlocal model of the inductor current; represents the estimated value of the uncertain part of the output voltage hyperlocal model; α i Represents the duty cycle coefficient; α v Represents the reference inductor current amplitude coefficient;

[0065] 45) By constraining the duty cycle generated by equation (18), we have:

[0066]

[0067] Wherein, d is the duty cycle control signal of the switch tube S;

[0068] 46) Unlike the cascade control system, the cascade-free control system removes the voltage outer loop, and the reference current amplitude is given by the average power conservation principle:

[0069]

[0070] Among them, p in represents the average input power; p o represents the average output power; Indicates the inductor current reference value amplitude; Indicates the reference output voltage; V in Indicates the amplitude of the input voltage; i o Indicates the load current, load current i o By estimated value Approximate, and estimated Obtained by the load current estimator in Equation (14);

[0071] 47) In order to prove the stability of the cascade-free cooperative control system of the Boost PFC converter, the Lyapunuov function is defined as

[0072]

[0073] Where V represents the Lyapunuov function, and ψ represents the macro variable of the system;

[0074] 48) Take the derivative of V, when Negative timing, meeting the convergence condition;

[0075]

[0076] in, is the differential of the Lyapunuov function;

[0077] Because T>0, ψ 2 >0, so The defined Lyapunuov function satisfies the asymptotic convergence condition, which proves that the proposed cascadeless cooperative control achieves stable operation of the Boost PFC converter system.

[0078] A system for a cascade-free cooperative control method of a Boost PFC converter based on a super-local model, wherein the single-phase Boost PFC converter includes a single-phase Boost PFC converter main circuit and a cascade-free cooperative control system;

[0079] The main circuit of the single-phase Boost PFC converter includes an uncontrolled rectifier bridge circuit and a Boost converter; the Boost converter includes a boost inductor L, a power switch tube S, a freewheeling diode D, an output capacitor C and a resistive load R; one end of the boost inductor L on the input side of the Boost converter is the input end of the Boost converter, and the other end is respectively connected to the anode of the freewheeling diode D and the drain of the power switch tube S; the source of the power switch tube S is grounded, and the gate is connected to the output end of the PWM modulation module in the cascaded model-free predictive control system; the cathode of the freewheeling diode D is connected to 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 across the output capacitor C;

[0080] The cascade-free collaborative control system includes a PWM modulation module, a reference inductor current value generation module, a load current estimation module, and a collaborative control module. The input of the average filter module is connected to the output of the output voltage, and the output is connected to the input of the cascade-free collaborative controller. The output of the PWM modulation module is connected to the gate of the power switch S. The output of the reference current value generation module is connected to the input of the collaborative controller. The input of the collaborative controller is connected to the reference output voltage value, inductor current reference value, output voltage value, and inductor current value specified by the user, and the output is connected to the input of the PWM modulation module.

[0081] Beneficial effects

[0082] The cascade-free collaborative control method and system of the Boost PFC converter based on the super-local model of the present invention can effectively improve the steady-state control accuracy of the output voltage of the Boost PFC converter compared with the existing technology, and has the technical advantages of a simple control structure and strong resistance to load disturbances under sudden changes in load power, comprehensively improving the dynamic control performance and steady-state operation performance of the Boost PFC converter.

[0083] The present invention designs a cascadeless cooperative control system for a Boost PFC converter: (1) An average filter module is used to filter out the double frequency ripple voltage in the output voltage of a single-phase Boost PFC converter to avoid ripple voltage contamination of the reference inductor current amplitude generated, reduce controller calculation delay, and enhance system stability. (2) Based on the established hyperlocal model of the output voltage and inductor current of a single-phase Boost PFC converter operating in continuous conduction mode, a cascadeless cooperative controller is designed to simplify the system control structure and improve the system's robustness and dynamic response speed for output voltage control. (3) By improving the traditional cooperative control macro variable design, the designed macro variable not only includes the output voltage error term and the inductor current error term, but also adds the integral term of the output voltage error, thereby improving the steady-state accuracy of the output voltage of the Boost PFC converter.

[0084] The present invention is based on the establishment of a super-local model of a Boost PFC converter operating in continuous conduction mode, designs macro variables including the output voltage error term, the inductor current error term and the output voltage error integral term of the Boost PFC converter, and then designs a dynamic evolution equation. Through a cascade-free control structure, the coordinated control of the inductor current and the output voltage is achieved. This not only effectively improves the steady-state control accuracy of the Boost PFC converter's output voltage, but also has the technical advantages of a simple control structure and strong load disturbance resistance under sudden load power changes, thereby comprehensively improving the dynamic control performance and steady-state operation performance of the Boost PFC converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 is a method sequence diagram of the present invention;

[0086] Figure 2 It is the control block diagram of Boost PFC converter without cascade cooperative control;

[0087] Figure 3 This is the steady-state simulation waveform of the input voltage and input current of the non-cascaded cooperative control system when the output power is 1000W;

[0088] Figure 4 This is the steady-state simulation waveform of the input voltage and input current of the non-cascaded cooperative control system when the output power is 600W;

[0089] Figure 5 This is the steady-state simulation waveform of the input voltage and input current of the non-cascaded cooperative control system when the output power is 300W;

[0090] Figure 6 This is a dynamic simulation waveform diagram of the output voltage and input current of the cascade-free cooperative control system when the load power steps from 1000W to 500W;

[0091] Figure 7 This is a dynamic simulation waveform diagram of the output voltage and input current of the cascade-free cooperative control system when the load power steps from 500W to 1000W;

[0092] Figure 8 This is the steady-state experimental waveform of the input voltage and input current of the non-cascaded cooperative control system when the load power is 1000w;

[0093] Figure 9 This is the steady-state experimental waveform of the input voltage and input current of the non-cascaded cooperative control system when the load power is 500w;

[0094] Figure 10 This is the dynamic experimental waveform of the output voltage and input current of the cascade-free cooperative control system when the load power steps from 1000W to 500W;

[0095] Figure 11 This is a dynamic simulation waveform diagram of the output voltage and input current of the cascade-free cooperative control system when the load power steps from 500W to 1000W;

[0096] Figure 12 This is a comparison chart of the power factor of the Boost PFC converter under different load powers and different control methods. DETAILED DESCRIPTION

[0097] In order to provide a further understanding and appreciation of the structural features and effects achieved by the present invention, a detailed description is provided with reference to preferred embodiments and accompanying drawings as follows:

[0098] like Figure 1 As shown, the present invention describes a cascade-free cooperative control method for a Boost PFC converter based on a hyperlocal model. By designing macro variables through a cascade-free cooperative control strategy, it uniformly manages inductor current and output error. This method aims to simplify the system control structure and compensate for the insufficient dynamic response performance caused by the cascaded solution where the outer voltage loop indirectly increases the reference value for the inner current loop. The method includes the following steps:

[0099] The first step is to process the Boost PFC converter data and average filtering: obtain the Boost PFC converter parameters, including the boost inductor L, output capacitor C, resistive load R, freewheeling diode D, freewheeling diode D, and power switch device S, establish the average state space equation of the Boost PFC converter in continuous conduction mode, and use the average filtering module to filter the double frequency ripple of the output voltage.

[0100] (1) Obtain the Boost PFC converter parameters.

[0101] (2) Using equation (1), the dynamic equation of the inductor current of the single-phase Boost PFC converter operating in continuous conduction mode is established;

[0102]

[0103] Among them, di L / dt represents the first-order differential of the inductor current; L represents the boost inductor value; v in Indicates input voltage; v o Represents the output voltage; d represents the duty cycle control signal of the switch tube S.

[0104] (3) Using equation (2), the dynamic equation of the output voltage of the single-phase Boost PFC converter operating in continuous conduction mode is established;

[0105]

[0106] Among them, dv o / dt represents the first-order differential of the output voltage; C represents the output capacitance value; i L represents the inductor current; i o represents the load current; d represents the duty cycle control signal of the switch tube S.

[0107] (4) Use the average filter module to adjust the output voltage v o [k] is averaged; the kth sampling period T is obtained using formula (3) k The average output voltage V o [k];

[0108]

[0109] Among them, V o [mk] represents the average output voltage value at the kth sampling point of the mth output voltage cycle; v o_mk is the output voltage sampling value at the kth sampling point in the mth output voltage cycle; Represents the average voltage value of the sum of the output voltage sampling values ​​at N sampling points in the mth output voltage cycle; V o[(m-1)N] is the average voltage value at the Nth sampling point in the m-1th output voltage cycle; v o_(m-1)k is the output voltage sampling value at the kth sampling point in the m-1th output voltage cycle; N is the number of sampling points in an output voltage cycle set by the user; m is the number of output voltage cycles, m is a positive integer; i is an integer between 1 and N.

[0110] The second step is to establish a hyperlocal model and perform load current estimation: Based on the average state space equation of the single-phase Boost PFC converter, the uncertainty part F of the output voltage hyperlocal model is used. v , the uncertain part F of the inductor current hyperlocal model i , reference inductor current amplitude Duty cycle coefficient α i , refer to the inductor current amplitude coefficient α v , establish a super-local model of the Boost PFC converter output voltage and inductor current; use the load current estimation module to estimate the load current.

[0111] (1) According to model-free control theory, the first-order hyperlocal model of the single-input single-output system is expressed as Equation (4);

[0112]

[0113] Where u and y represent the input and output of the system respectively; α is the proportional coefficient of the system input; and F contains the uncertain part of the system.

[0114] (2) Establish a hyperlocal model of the inductor current of the Boost PFC converter;

[0115]

[0116]

[0117] Among them, di L / dt represents the first-order differential of the inductor current; α i represents the duty cycle coefficient; d represents the duty cycle control signal of the switch tube S; F i represents the uncertain part of the inductor current hyperlocal model; C i Indicates the control gain set for the inductor current; L n is the rated inductance of the input inductor; L represents the boost inductor; v in Indicates input voltage; v o Indicates the output voltage.

[0118] (3) When the switch tube S is turned on, the freewheeling diode does not work; when the switch tube S is turned off, the freewheeling diode works. The freewheeling diode and the inductor current have the following relationship:

[0119]

[0120] (4) Assuming that all signals in the output voltage state equation are averaged to eliminate the effect of the system's double frequency ripple and ignoring the internal losses in the system, the average input power and average output power are expressed by the following equations:

[0121]

[0122] Among them, P in Indicates the average input power of the system; V in Indicates the amplitude of the input voltage; Represents the amplitude of the reference inductor current; P o Indicates the average output power of the system; Indicates the reference output voltage amplitude; I D represents the average diode current.

[0123] (5) According to the power conservation principle P in =P o , derive the average diode current I D The expression is:

[0124]

[0125] Among them, I D represents the average diode current; V in Indicates the amplitude of the input voltage; Indicates the reference output voltage amplitude; Indicates the amplitude of the reference inductor current.

[0126] (6) Rearranging the dynamic equation of the output voltage (2), the average state equation of the output voltage is expressed as:

[0127]

[0128] Among them, dv o / dt represents the first-order differential of the output voltage; V in Indicates the amplitude of the input voltage; C indicates the output capacitance; Indicates the reference output voltage amplitude; Represents the amplitude of the reference inductor current; i o Indicates the load current.

[0129] (7) Establish a super-local model of the output voltage of the Boost PFC converter;

[0130]

[0131]

[0132] Among them, dv o / dt represents the first-order differential of the output voltage; α v Represents the reference inductor current amplitude coefficient; Indicates the amplitude of the reference inductor current; F v represents the uncertain part of the output voltage hyperlocal model; C v Indicates the control gain set to adjust the output voltage; V in Indicates the amplitude of the input voltage; C n is the rated capacitance value of the output capacitor; Indicates the amplitude of the reference output voltage; C indicates the output capacitance; i o Indicates the load current.

[0133] (8) Using differential algebraic methods to calculate F i and F v Make an estimate and use and Represents its estimated value, and the expression of formula (13) is obtained

[0134]

[0135] Among them, T s is the control period; T F =n F T s is the sliding window length, n F is a constant and is set to 12; in a shorter sampling interval, it is considered and is a constant, whose differential is approximately 0; v o (τ) represents the output voltage at time τ; i L (τ) represents the inductor current at time τ; d(τ) represents the duty cycle control signal at time τ.

[0136] (9) In order to quickly generate the reference current amplitude, the complex trapezoidal formula and differential algebraic method are applied to realize the output current i o The online estimation of the load current is expressed as follows:

[0137]

[0138] in, Represents the estimated value of the load current; T F =n F T s is the sliding window length; C represents the output capacitance; v o (τ) represents the output voltage at time τ; i L(τ) represents the inductor current at time τ; d(τ) represents the duty cycle control signal at time τ.

[0139] The third step is to generate the duty cycle control law for cascadeless cooperative control: Based on the hyperlocal model of the Boost PFC converter, macrovariable design is carried out, including the output voltage error term, the inductor current error term, and the integral term of the output voltage error. The dynamic evolution equation of the system is designed to converge to the manifold. The duty cycle control law for cascadeless cooperative control is generated based on the dynamic evolution equations involved and the duty cycle required for system operation.

[0140] (1) The macro variables of the Boost PFC converter cooperative control system are set as a linear combination of the inductor current error term, the output voltage error term, and the integral term of the output voltage error term. The macro variables are designed as shown in Equation (15):

[0141]

[0142] Among them, ψ represents the macro variable of the system; i L represents the inductor current; represents the reference inductor current; k1, k2, and k3 represent the control parameter coefficients of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively.

[0143] (2) Differentiating the macro variables yields the expression of formula (16);

[0144]

[0145] Among them, dψ / dt represents the differential of the macro variable; di L / dt represents the differential of the inductor current; dv o / dt represents the differential of the output voltage; represents the reference output voltage; k1, k2, and k3 represent the control parameter coefficients of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively.

[0146] (3) The dynamic evolution equation of the system converging to the manifold is set as shown in Equation (17):

[0147]

[0148] Where T represents the convergence time constant of the system toward the manifold surface, T>0; Represents the derivative of a macro variable.

[0149] (4) By solving equations (15) to (17), the duty cycle control law of non-cascaded cooperative control is obtained as equation (18);

[0150]

[0151] Where d represents the duty cycle control signal; ψ represents the macro variable; k1, k2, and k3 represent the control parameter coefficients of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively; T represents the convergence time constant of the system toward the manifold surface; represents the estimated value of the uncertain part of the hyperlocal model of the inductor current; represents the estimated value of the uncertain part of the hyperlocal model of the output voltage; α i Represents the duty cycle coefficient; α v Represents the reference inductor current amplitude coefficient.

[0152] (5) By constraining the duty cycle generated by equation (18), we have:

[0153]

[0154] Wherein, d is the duty cycle control signal.

[0155] (6) Unlike the cascade control system, the cascade-free control system removes the voltage outer loop, and the reference current amplitude is given by the average power conservation principle:

[0156]

[0157] Among them, p in represents the average input power; p o represents the average output power; Indicates the reference inductor current amplitude; Indicates the reference output voltage; V in Indicates the amplitude of the input voltage; i o Indicates the load current, load current i o By estimated value Approximate, and estimated Obtained by the load current estimator in equation (14).

[0158] (7) To prove the stability of the cascade-free cooperative control system of the Boost PFC converter, define the Lyapunuov function

[0159]

[0160] Where V represents the Lyapunuov function and ψ represents the macro variable of the system.

[0161] (8) Take the derivative of V, when Negative timing, meeting the convergence condition;

[0162]

[0163] in, is the differential of the Lyapunuov function;

[0164] Because T>0, ψ 2 >0, so The defined Lyapunuov function satisfies the asymptotic convergence condition, proving that the proposed cascadeless cooperative control achieves stable operation of the Boost PFC converter system.

[0165] The fourth step is cascade-free cooperative control of the Boost PFC converter: the duty cycle control signal is modulated by the PWM modulation module to obtain the power switch device drive signal s[k] of the kth cycle, and the action of the power switch device S of the Boost PFC converter is controlled to realize the cascade-free cooperative control of the Boost PFC converter based on the super-local model.

[0166] like Figure 2 As shown, a system of a cascadeless cooperative control method of a Boost PFC converter based on a super-local model is also provided herein. The single-phase Boost PFC converter includes a single-phase Boost PFC converter main circuit and a cascadeless cooperative control system.

[0167] The main circuit of the single-phase Boost PFC converter includes an uncontrolled rectifier bridge circuit and a Boost converter. The Boost converter includes a boost inductor L, a power switch device (tube) S, a freewheeling diode D, an output capacitor C and a resistive load R. One end of the boost inductor L on the input side of the Boost converter is the input end of the Boost converter, and the other end is respectively connected to the anode of the freewheeling diode D and the drain of the power switch device S. The source of the power switch device S is grounded, and the gate is connected to the output end of the PWM modulation module in the cascaded model-free predictive control system. The cathode of the freewheeling diode D is connected to 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 to both ends of the output capacitor C.

[0168] The cascade-free collaborative control system includes a PWM modulation module, a reference inductor current value generation module, a load current estimation module, and a collaborative control module. The input of the average filter module is connected to the output of the output voltage, and the output is connected to the input of the model-free predictive voltage controller; the output of the PWM modulation module is connected to the gate of the power switching device S; the output of the reference current value generation module is connected to the input of the collaborative controller; the input of the collaborative controller is connected to the reference output voltage value, inductor current reference value, output voltage value, and inductor current value specified by the user, and the output is connected to the input of the PWM modulation module.

[0169] In order to verify the effectiveness of the control method of the cascade-free cooperative control system described in the present invention, Matlab / Simulink simulation was carried out. The specific process of Matlab / Simulink simulation is as follows:

[0170] Use Matlab / simulink software to build Figure 2 The simulation model of the single-phase Boost PFC converter control system without cascade cooperative control is shown in the figure. The converter main circuit parameters are: load rated power 1000W, AC input voltage 110V / 50Hz, DC output voltage 300V, boost inductor 486μH, output capacitor 990μF, switching frequency 50kHz, n F The data window length n F =12, the number of sampling points N in the average filtering algorithm module is 20.

[0171] The macro variable ψ decays exponentially with the time constant T. After 3T to 4T, the system approaches a manifold, and the system continues to operate on this manifold. The dynamic response time T of the Boost PFC converter is obtained based on the system transient response process. d is about 0.16s, and the range of the time constant T is [T d / 4, T d / 3], so the time constant T is set to 0.04. The macro variable design primarily includes three parameters: the inductor current error coefficient k1, the output voltage error coefficient k2, and the voltage error integral coefficient k3. The coefficient k1 defines the inductor current weighting factor in the macro variable, and its value affects the quality of the inductor current waveform. When the system reaches the manifold surface, its proportionality parameter must balance the output voltage and inductor current control performance. Increasing the relative proportion of the current error coefficient improves the controller's tracking of the inductor current reference value, but results in a larger output voltage tracking error. Increasing the relative proportion of the voltage error coefficient increases the controller's dynamic response to the output voltage, but affects the quality of the inductor current waveform. Increasing the relative proportion of the output voltage error integral coefficient improves the controller's output voltage accuracy when reaching steady-state. After tuning data from multiple simulations and experiments, k1, k2, and k3 were set to 1, 0.4, and 10, respectively.

[0172] The system simulation results through Matlab / Simulink are as follows Figure 3-Figure 12 As shown; where i ac Represents the input current of the converter; i ac ref Represents the reference value of the converter input current; v o Represents the output voltage of the converter. Figure 3 、 Figure 4 and Figure 5The waveforms of the input voltage, input current, and input current reference value for load powers of 1000W, 600W, and 300W under the cascadeless cooperative control scheme are shown. The input current quality has been significantly improved. This is due to the cascadeless cooperative control scheme, which is based on a hyperlocal model design. Algebraic identification techniques are used to estimate the inductor current online, and the power conservation principle is used to generate the inductor current reference value. Due to factors such as actual switching losses and on-state voltage drop, the inductor current reference value cannot be accurately generated, resulting in steady-state errors. The integral term for the output voltage error is added to the traditional macro variable design to further improve the system's steady-state performance.

[0173] Figure 6 The dynamic simulation waveforms of the output voltage and input current of the converter when the load power steps from 1000W to 500W under cascade-free cooperative control are shown; Figure 7 The following diagram shows the dynamic simulation waveforms of the converter's output voltage and input current for a load power step from 500W to 1000W under cascade-free cooperative control. The output voltage recovers quickly and stabilizes quickly. This is due to the unified management of inductor current and output voltage achieved under the cascade-free cooperative control scheme based on a hyperlocal model. This compensates for the limited dynamic response of the traditional cascade control scheme, where the outer voltage loop indirectly provides a reference value for the inner current loop, thereby accelerating the system's dynamic response performance.

[0174] Figure 8 The steady-state experimental waveforms of the input voltage and input current of the non-cascaded cooperative control system are shown when the load power is 1000W; Figure 9 This is the steady-state experimental waveform of the input voltage and input current of the non-cascaded cooperative control system when the load power is 500w; Figure 10 It is a dynamic experimental waveform diagram showing the output voltage and input current of the cascade-free cooperative control system when the load power steps from 1000W to 500W; Figure 11 Figure 3 shows the dynamic experimental waveforms of the output voltage and input current of the cascadeless cooperative control system when the load power steps from 500W to 1000W. The experimental results are consistent with the simulation results, confirming that the proposed cascadeless cooperative control scheme based on the hyperlocal model has high control accuracy and convergence speed, while taking into account both the steady-state and dynamic control performance of the Boost PFC converter system.

[0175] Figure 12 The power factor of the Boost PFC converter input current under different control schemes is shown. This clearly shows that the cascadeless cooperative control scheme is overall superior to the cascaded model-free control and PI control schemes. In particular, the cascadeless cooperative control significantly improves the input current power factor and optimizes the current quality of the Boost converter input current at low power load output.

[0176] In summary, the proposed cascade-free cooperative control scheme based on the hyperlocal model can take into account both the system dynamic control performance and steady-state operation performance.

[0177] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A cascade-free cooperative control method for a Boost PFC converter based on a hyperlocal model, characterized in that: The following steps are involved: 11) Boost PFC Converter Data and Average Filtering: Obtain the Boost PFC converter parameters, including the boost inductor L, output capacitor C, resistive load R, freewheeling diode D, and power switch S. Establish the average state-space equation for the Boost PFC converter in continuous conduction mode, and use the average filtering module to filter the output voltage double frequency ripple. 12) Establish a hyperlocal model and perform load current estimation: Based on the average state space equation of the single-phase Boost PFC converter, the uncertainty part Fv of the output voltage hyperlocal model, the uncertainty part Fi of the inductor current hyperlocal model, and the reference inductor current amplitude are used to estimate the load current. Duty cycle coefficient α i , reference inductor current amplitude coefficient α v , establish a hyperlocal model of the output voltage and inductor current of the Boost PFC converter; Among them, di L / dt represents the first-order differential of the inductor current; α i represents the duty cycle coefficient; d represents the duty cycle control signal of the switch tube S; F i represents the known and unknown parts of the inductor current hyperlocal model; C i Represents an adjustable constant parameter; L n is the rated inductance of the input inductor; L represents the boost inductor; v in Indicates input voltage; v o Indicates the output voltage; Establish a hyperlocal model of the output voltage of the Boost PFC converter; Among them, dv o / dt represents the first-order differential of the output voltage; α v Represents the reference inductor current amplitude coefficient; Indicates the amplitude of the reference inductor current; F v Represents the known and unknown parts of the output voltage; C v Indicates the control gain set to adjust the output voltage; V in Indicates the amplitude of the input voltage; C n is the rated capacitance value of the output capacitor; Indicates the amplitude of the reference output voltage; C indicates the output capacitance; i o Indicates load current; Using a load current estimation module, the load current is estimated; 13) Generation of the Duty Cycle Control Law for Cascadeless Cooperative Control: Based on a hyperlocal model of the Boost PFC converter, macro variables are designed, including the output voltage error term, the inductor current error term, and the output voltage error integral term. Dynamic evolution equations are designed to ensure that the system converges to a manifold. The duty cycle control law for cascadeless cooperative control is generated based on the designed dynamic evolution equations and the duty cycle required for system operation. The macro variables of the Boost PFC converter cooperative control system are set as a linear combination of the inductor current error term, the output voltage error term, and the integral term of the output voltage error term. The macro variables are designed as shown in formula (15): Among them, ψ represents the macro variable of the system; i L represents the inductor current; represents the reference inductor current; k1, k2, and k3 represent the control parameters of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively; The duty cycle control law of non-cascaded cooperative control is obtained as formula (18); Where d represents the duty cycle control signal; ψ represents the macro variable; k1, k2, and k3 represent the control parameters of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively; and T represents the convergence time constant of the system toward the manifold surface. represents the estimated value of the uncertain part of the hyperlocal model of the inductor current; represents the estimated value of the uncertain part of the output voltage hyperlocal model; α i Represents the duty cycle coefficient; α v Represents the reference inductor current amplitude coefficient; 14) Cascadeless cooperative control of Boost PFC converter: The duty cycle control signal is modulated by the PWM modulation module to obtain the power switch device drive signal s[k] of the kth cycle, and the action of the power switch tube S of the Boost PFC converter is controlled to realize the cascadeless cooperative control of the Boost PFC converter based on the super-local model.

2. The cascade-free cooperative control method for Boost PFC converter based on super-local model according to claim 1, characterized in that: The Boost PFC converter data and average filtering process comprises the following steps: 21) Obtaining Boost PFC converter parameters; 22) Use equation (1) to establish the dynamic equation of the inductor current of the single-phase Boost PFC converter operating in continuous conduction mode; Among them, di L / dt represents the first-order differential of the inductor current; L represents the boost inductor value; v in Indicates input voltage; v o represents the output voltage; d represents the duty cycle control signal of the switch tube S; 23) Use equation (2) to establish the output voltage dynamic equation of the single-phase Boost PFC converter operating in continuous conduction mode; Among them, dv o / dt represents the first-order differential of the output voltage; C represents the output capacitance value; i L represents the inductor current; i o represents the load current; d represents the duty cycle control signal of the switch tube S; 24) Use the average filter module to adjust the output voltage v o [k] is averaged; the kth sampling period T is obtained using formula (3) k The average output voltage V o [k]; Among them, V o [mk] represents the average output voltage value at the kth sampling point of the mth output voltage cycle; v o_mk is the output voltage sampling value at the kth sampling point in the mth output voltage cycle; Represents the average voltage value of the sum of the output voltage sampling values ​​at N sampling points in the mth output voltage cycle; V o [(m-1)N] is the average voltage value at the Nth sampling point in the m-1th output voltage cycle; v o_(m-1)k is the output voltage sampling value at the kth sampling point in the m-1th output voltage cycle; N is the number of sampling points in an output voltage cycle set by the user; m is the number of output voltage cycles, m is a positive integer; i is an integer between 1 and N.

3. The cascade-free cooperative control method for Boost PFC converter based on super-local model according to claim 1, characterized in that: The establishing of the hyperlocal model and the load current estimation comprises the following steps: 31) According to model-free control theory, the first-order hyperlocal model of a single-input single-output system is expressed as Equation (4); Where u and y represent the input and output of the system respectively; α is the scaling factor of the system input; F contains the known and unknown parts of the system; 32) Establish a hyperlocal model of the inductor current in a Boost PFC converter; 33) When the switch tube S is turned on, the freewheeling diode does not work; when the switch tube S is turned off, the freewheeling diode works. The freewheeling diode and the inductor current have the following relationship: 34) Assuming that all signals in the output voltage state equation are averaged to eliminate the impact of the system's double frequency ripple and ignoring internal losses in the system, the average input power and average output power are expressed by the following equations: Among them, P in Indicates the average input power of the system; V in Indicates the amplitude of the input voltage; Represents the amplitude of the reference inductor current; P o Indicates the average output power of the system; Indicates the amplitude of the reference output voltage; I D represents the average diode current; 35) According to the principle of conservation of power P in =P o , derive the average diode current I D The expression is: Among them, I D represents the average diode current; V in Indicates the amplitude of the input voltage; Indicates the amplitude of the reference output voltage; Indicates the amplitude of the reference inductor current; 36) Rearranging the dynamic equation of the output voltage (2), the average state equation of the output voltage is expressed as: Among them, dv o / dt represents the first-order differential of the output voltage; V in Indicates the amplitude of the input voltage; C indicates the output capacitance; Indicates the amplitude of the reference output voltage; Represents the amplitude of the reference inductor current; i o Indicates the load current; 37) Establish a hyperlocal model of the output voltage of the Boost PFC converter; 38) Using differential algebraic methods to calculate F i and F v Make an estimate and use and Represents its estimated value, and the expression of formula (13) is obtained Among them, T s is the control period; T F =n F T s is the sliding window length, n F is a constant and is set to 12; in a shorter sampling interval, it is considered and is a constant, whose differential is approximately 0; v o (τ) represents the output voltage at time τ; i L (τ) represents the inductor current at time τ; d(τ) represents the duty cycle control signal at time τ; 39) To quickly generate the reference current amplitude, the complex trapezoidal formula and differential algebraic method are applied to realize the output current i o The online estimation of the load current is obtained as follows: in, Represents the estimated value of the load current; T F =n F T s is the sliding window length; C represents the output capacitance; v o (τ) represents the output voltage at time τ; i L (τ) represents the inductor current at time τ; d(τ) represents the duty cycle control signal at time τ.

4. The cascade-free cooperative control method for Boost PFC converter based on super-local model according to claim 1, characterized in that: The generation of the cascade-free cooperative control duty cycle control law includes the following steps: 41) Setting the macro variables of the Boost PFC converter cooperative control system to a linear combination of the inductor current error term, the output voltage error term, and the integral term of the output voltage error term; 42) Differentiate the macro variables to obtain the expression of formula (16); Among them, dψ / dt represents the differential of the macro variable; di L / dt represents the differential of the inductor current; dv o / dt represents the differential of the output voltage; represents the reference output voltage; k1, k2, and k3 represent the control parameters of the inductor current error term, the output voltage error term, and the output voltage error integral term, respectively; 43) The dynamic evolution equation of the system converging to the manifold is assumed to be as shown in Equation (17): Where T represents the convergence time constant of the system toward the manifold surface, T>0; Represents the derivative of a macro variable; 44) By solving equations (15) to (17), the duty cycle control law of non-cascaded cooperative control is obtained; 45) By constraining the duty cycle generated by equation (18), we have: Wherein, d is the duty cycle control signal of the switch tube S; 46) Unlike the cascade control system, the cascade-free control system removes the voltage outer loop, and the reference current amplitude is given by the average power conservation principle: Among them, p in represents the average input power; p o represents the average output power; Indicates the reference value amplitude of the inductor current; Indicates the reference output voltage; V in Indicates the amplitude of the input voltage; i o Indicates the load current, load current i o By estimated value Approximate, and estimated Obtained by the load current estimator in Equation (14); 47) In order to prove the stability of the cascade-free cooperative control system of the Boost PFC converter, the Lyapunuov function is defined as Where V represents the Lyapunuov function, and ψ represents the macro variable of the system; 48) Take the derivative of V, when Negative timing, meeting the convergence condition; in, is the differential of the Lyapunuov function; Because T>0, ψ 2 >0, so The defined Lyapunuov function satisfies the asymptotic convergence condition, which proves that the proposed cascadeless cooperative control achieves stable operation of the Boost PFC converter system.

5. The system of the cascadeless cooperative control method of Boost PFC converter based on super local model according to claim 1, characterized in that: The single-phase Boost PFC converter includes a single-phase Boost PFC converter main circuit and a cascade-free coordinated control system; The main circuit of the single-phase Boost PFC converter includes an uncontrolled rectifier bridge circuit and a Boost converter; the Boost converter includes a boost inductor L, a power switch tube S, a freewheeling diode D, an output capacitor C and a resistive load R; one end of the boost inductor L on the input side of the Boost converter is the input end of the Boost converter, and the other end is respectively connected to the anode of the freewheeling diode D and the drain of the power switch tube S; the source of the power switch tube S is grounded, and the gate is connected to the output end of the PWM modulation module in the cascaded model-free predictive control system; the cathode of the freewheeling diode D is connected to 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 across the output capacitor C; The cascadeless collaborative control system includes a PWM modulation module, a reference inductor current value generation module, a load current estimation module and a collaborative control module; the input end of the average filter module is connected to the output end of the output voltage, and the output end is connected to the input end of the cascadeless collaborative controller; the output end of the PWM modulation module is connected to the gate of the power switch tube S; the output end of the reference inductor current value generation module is connected to the input end of the collaborative controller; the input end of the collaborative controller is connected to the reference output voltage value, inductor current reference value, output voltage value, and inductor current value given by the user, and the output end is connected to the input end of the PWM modulation module.

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