CN-122001191-A - Fixed time switching control method and system for Boost PFC converter without phase-locked loop

CN122001191ACN 122001191 ACN122001191 ACN 122001191ACN-122001191-A

Abstract

The invention discloses a method and a system for controlling fixed time switching of a Boost PFC converter without a phase-locked loop, and belongs to the technical field of power electronic control. Aiming at the problems of slow dynamic response of a phase-locked loop, large influence of initial value on convergence time of an observer and poor load abrupt change robustness in the traditional PFC control, the invention provides a composite control architecture based on a switching linear system. The method comprises the steps of firstly establishing a Boost PFC switching linear model containing parallel load disturbance components, estimating load step disturbance in real time by using an extended state observer, introducing a nonlinear fixed time observer, rapidly decoupling the amplitude and the phase of input voltage within preset time irrelevant to an initial value to replace a traditional phase-locked loop, and finally designing a switching control law based on Lyapunov stability. According to the invention, through the cooperative design of the observer and the controller, the rapid locking of the voltage fluctuation of the power grid and the no-static-difference compensation of the load abrupt change are realized, and the dynamic quality and the power factor of the converter are obviously improved.

Inventors

YANG KAIKAI
ZHANG GUIDONG
MA WENJIE
WU LIHAO

Assignees

广东工业大学

Dates

Publication Date: 20260508
Application Date: 20260127

Claims (5)

1. The control method for the fixed time switching of the Boost PFC converter without the phase-locked loop is characterized by comprising the following steps of: Step S1, constructing a switching linear system model of a Boost PFC converter, defining a state variable, and establishing an expansion state space equation containing a load disturbance component aiming at load change; step S2, designing a load switching disturbance observer, ensuring convergence of an observation error by using a Lyapunov function, and observing step disturbance of load current in real time; Step S3, designing a fixed time observer of the amplitude and the phase of the input voltage, constructing the observer by utilizing a sign function and a nonlinear gain term based on the sine characteristic of the input voltage, and ensuring that the estimation errors of the amplitude and the phase of the voltage are converged to zero in the fixed time; And S4, designing a nonlinear switching controller, setting a current reference value according to an expected power factor correction target, and constructing a switching law based on Lyapunov stability by combining the observed values of the steps S2 and S3 to control the on and off of a Boost PFC converter switching tube.
2. The method according to claim 1, wherein in step S1, the switching linear system model state variable x is defined as Wherein the inductor current i L , the output voltage V o and the rectifying side input voltage V in , the derivative of the state vector when the switching tube is on is , The derivative of the state vector when the switching tube is turned off is Wherein A 1 、A 2 is a system matrix determined by L, C, R L and load equivalent parameters, and a system output matrix System disturbance observation matrix , Is the observed quantity of system load disturbance.
3. The method according to claim 1, wherein in step S2, the method for constructing the load switching disturbance observer is as follows: S1, assuming that load disturbance changes in a step mode, namely the disturbance derivative is zero; S2, constructing an observer state equation, and correcting a disturbance estimated value by utilizing error feedback of a system measured value and an observed value; S3, selecting a quadratic Lyapunov function to prove the stability of the observer, and determining an observer gain matrix by solving a linear matrix inequality.
4. The method according to claim 1, wherein in step S4, the step of the design method of the switching controller is: S1, defining an inductor current reference value In phase with the input voltage V in ; S2, defining error variables Reference track for system state and inductance current A difference between; s3, selecting a Lyapunov function V containing an error variable; s4, designing a switching law So that the derivative of the Lyapunov function Thereby ensuring that the system state tracks the reference track.
5. The Boost PFC converter fixed time switching control system without the phase-locked loop is characterized by comprising a signal acquisition module, an observer module, a controller module, a driving circuit and a power switching tube, wherein the signal acquisition module is used for acquiring an inductive current i L , an output voltage V o and an input voltage signal V in , the observer module is internally provided with a load switching disturbance observer, a fixed time input voltage observer and a switching control algorithm and is used for outputting disturbance estimated values and voltage parameters, the controller module is used for receiving acquisition signals and observed values, executing the switching control law and outputting PWM driving signals, and the driving circuit is used for driving the power switching tube in the Boost circuit.

Description

Fixed time switching control method and system for Boost PFC converter without phase-locked loop Technical Field The invention relates to a high-performance control technology of a power electronic converter, in particular to a fixed time switching control method which is applied to a Boost Power Factor Correction (PFC) converter and has the characteristics of fast anti-interference capability and no phase-locked loop. Background With the complexity of the power grid environment, a Boost PFC converter is used as front-end rectifying equipment and faces more severe control requirements. The existing control technology mainly has the following three core bottlenecks: 1. depending on the phase-locked loop (PLL), conventional control requires that the grid phase be acquired by the PLL. However, a PLL is essentially a closed loop feedback system, has inherent dynamic hysteresis, and is prone to current distortion due to phase detection errors when the grid voltage is distorted or unbalanced. 2. Uncertainty of observer convergence speed existing state observers are based on progressive convergence (e.g. Luenberger observer) or finite time convergence. While finite time observers can theoretically converge within a finite time, their convergence time is strongly dependent on the magnitude of the initial error. When the system starts or encounters large grid fluctuations, the convergence time may be too long, resulting in control failure. 3. The load jump is slow to recover, and the response of the traditional double closed loop control to the load jump mainly depends on PI regulation of a voltage ring, so that the output voltage tends to generate larger drop or overshoot at the moment of load jump. Therefore, developing a control method that has no convergence time related to the initial value, does not need PLL, and can actively compensate for load disturbance is a key to breaking through the existing PFC performance bottleneck. Disclosure of Invention The invention aims to provide a Boost PFC converter switching control method and system based on a fixed time observer, which solve the problems of low convergence speed and weak disturbance rejection of the observer in the prior art. In order to achieve the above purpose, the present invention provides the following technical solutions: The proposed control method for the fixed time switching of the Boost PFC converter without the phase-locked loop comprises the following steps: Step S1, constructing a switching linear system model of a Boost PFC converter, defining a state variable, and establishing an expansion state space equation containing a load disturbance component aiming at load change; step S2, designing a load switching disturbance observer, ensuring convergence of an observation error by using a Lyapunov function, and observing step disturbance of load current in real time; Step S3, designing a fixed time observer of the amplitude and the phase of the input voltage, constructing the observer by utilizing a sign function and a nonlinear gain term based on the sine characteristic of the input voltage, and ensuring that the estimation errors of the amplitude and the phase of the voltage are converged to zero in the fixed time; And S4, designing a switching controller, setting a current reference value according to a desired power factor correction target, and combining the observed values of the steps S2 and S3 to construct a switching law based on Lyapunov stability so as to control the on and off of a Boost PFC converter switching tube. In step S1, the switching linear system model satisfies the inductor current i L, the output voltage V o and the rectifying side input voltage V in, defining a state vectorThe derivative of the state vector when the switch tube is on is , The derivative of the state vector when the switching tube is turned off is Wherein A 1、A2 is a system matrix determined by L, C, R L and load equivalent parameters, and a system output matrixSystem disturbance observation matrix,Is the observed quantity of system load disturbance. In step S2, the method for constructing the load switching disturbance observer includes: assuming that the load disturbance varies in a step-like manner, i.e. the disturbance derivative is zero State variablesMeasurable, therefore load-switching disturbance observer is as follows: Wherein: switching the gain of the disturbance observer for the load, in the disturbance term As follows: in step S3, the method for constructing the phase observer of the voltage amplitude at fixed time includes: the input voltage being a sinusoidal signal, frequency Knowing the same grid frequency, then to guarantee the control effect, the amplitude and phase of the input voltage need to be observed, modeled as follows: Wherein: is a sign of a function of the input voltage signal, Is thatIs used for the purpose of determining the derivative of (c),Is the magnitude of the input voltage. The fixed time observer was designed as fo