PFC circuit control method, system and device and readable storage medium

Abstract

The invention discloses a PFC circuit control method, system and device and a readable storage medium. The method comprises the steps of obtaining an output voltage signal of a PFC circuit and an initial reference current signal generated by a voltage outer ring based on the output voltage signal; obtaining a load current disturbance signal by using the output voltage signal and a current signal corresponding to an inductor in the PFC circuit; and obtaining an actual reference current signal of the current inner loop according to the initial reference current signal and the load current disturbance signal. The load of the voltage controller can be reduced, and when the load changes, the feed-forward value can be given quickly, so that the PFC circuit can respond to the load change quickly, and the dynamic response speed is improved.

Description

Technical Field

[0001] The present invention relates to the field of power supply control, and in particular to a PFC circuit control method, system, device and readable storage medium. Background Art

[0002] The control strategy of the front-stage PFC (Power Factor Correction) circuit of traditional industrial power supplies is PI (Proportional-Integral) dual-loop control. The advantage of this control strategy is that it has fewer parameters and is relatively easy to adjust. However, in actual engineering applications, the PFC circuit will inevitably be affected by input voltage fluctuations during rectification and boosting, resulting in a large double power frequency ripple in the output voltage. This double power frequency ripple is collected by the sampling circuit and transmitted to the DSP (Digital Signal Processor) to build a reference current for controlling the PFC circuit. When the DSP tries to build a reference current, the double power frequency ripple introduces additional nonlinearity in the current inner loop, thereby generating high-order harmonic components.

[0003] In order to prevent the double power frequency ripple from further affecting the voltage outer loop, the commonly used control strategy is to reduce the bandwidth of the voltage outer loop. However, reducing the bandwidth slows down the voltage outer loop's response to output voltage fluctuations. When the load suddenly increases or decreases, the PFC circuit cannot quickly compensate for the current fluctuation caused by the load change due to the reduced regulation speed of the voltage outer loop, resulting in large fluctuations in the output voltage, which seriously affects the response performance of the PFC circuit and its subsequent power supply when the load is switched.

[0004] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve at present. Summary of the invention

[0005] The purpose of the present invention is to provide a PFC circuit control method, system, device and readable storage medium, which can reduce the burden of the voltage controller. When the load changes, the feedforward value can be quickly given, so that the PFC circuit can respond quickly to the load change and improve the dynamic response speed.

[0006] In order to solve the above technical problems, the present invention provides a PFC circuit control method, comprising:

[0007] Acquire an output voltage signal of the PFC circuit, and an initial reference current signal generated by a voltage outer loop based on the output voltage signal;

[0008] Obtaining a load current disturbance signal using the output voltage signal and a current signal corresponding to an inductor in the PFC circuit;

[0009] An actual reference current signal of a current inner loop is obtained according to the initial reference current signal and the load current disturbance signal.

[0010] Optionally, the process of obtaining a load current disturbance signal by using the output voltage signal and a current signal corresponding to an inductor in the PFC circuit includes:

[0011] The output voltage signal and a current signal corresponding to the inductance in the PFC circuit are input into a disturbance observer to estimate a load current disturbance signal; the disturbance observer is created based on a mathematical model of the PFC circuit.

[0012] Optionally, the process of inputting the output voltage signal and the current signal corresponding to the inductor in the PFC circuit into a disturbance observer to estimate the load current disturbance signal includes:

[0013] Inputting the output voltage signal into an observation module of a disturbance observer to obtain a prediction signal; the observation module is created based on a filter and an inverse model of the mathematical model;

[0014] Inputting a current signal corresponding to the inductance in the PFC circuit into a first filtering module of the disturbance observer to obtain a filtered current signal; the first filtering module is created based on the filter;

[0015] A load current disturbance signal is obtained according to the prediction signal and the filtered current signal.

[0016] Optionally, the process of obtaining a load current disturbance signal according to the prediction signal and the filtered current signal includes:

[0017] Obtaining an intermediate current disturbance signal according to the filtered current signal and the prediction signal;

[0018] The second filtering module of the disturbance observer is used to filter the double power frequency ripple in the intermediate current disturbance signal to obtain a load current disturbance signal.

[0019] Optionally, the PFC circuit control method further includes:

[0020] Obtaining a mathematical model of the PFC circuit;

[0021] Determining a disturbance observation structure and disturbance observation parameters based on the mathematical model;

[0022] The disturbance observer is created using the disturbance observer structure and the disturbance observer parameters.

[0023] Optionally, the process of determining the disturbance observation structure and the disturbance observation parameters based on the mathematical model includes:

[0024] Obtaining an initial state space equation corresponding to the mathematical model of the PFC circuit;

[0025] Obtaining a disturbance variable equation according to the disturbance variable superimposed on the PFC circuit and the initial state space equation;

[0026] Obtaining a nominal model of the PFC circuit using the disturbance variable equation;

[0027] A disturbance observation structure and disturbance observation parameters are determined based on the nominal model.

[0028] Optionally, the PFC circuit control method further includes:

[0029] Acquiring an actual current signal flowing through an inductor in the PFC circuit;

[0030] Using the actual current signal as a current signal corresponding to the inductor in the PFC circuit;

[0031] or,

[0032] The initial reference current signal is used as a current signal corresponding to the inductor in the PFC circuit.

[0033] In order to solve the above technical problems, the present invention further provides a PFC circuit control system, comprising:

[0034] A first acquisition module, used for acquiring an output voltage signal of the PFC circuit and an initial reference current signal generated by a voltage outer loop based on the output voltage signal;

[0035] A first calculation module, used to obtain a load current disturbance signal by using the output voltage signal and a current signal corresponding to the inductor in the PFC circuit;

[0036] The second calculation module is used to obtain an actual reference current signal of the current inner loop according to the initial reference current signal and the load current disturbance signal.

[0037] In order to solve the above technical problems, the present invention further provides an electronic device, comprising:

[0038] Memory for storing computer programs;

[0039] A processor is used to implement the steps of the PFC circuit control method as described in any one of the above when executing the computer program.

[0040] To solve the above technical problem, the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the PFC circuit control method as described in any one of the above are implemented.

[0041] The present invention provides a PFC circuit control method, which estimates the load current disturbance signal caused by input voltage fluctuation and load change through the output voltage signal of the PFC circuit and the reference current signal output by the voltage outer loop, and uses the estimated load current disturbance signal to feedforward compensate the initial reference current signal output by the voltage outer loop, thereby obtaining the actual reference current signal of the current inner loop. Through feedforward compensation, the load disturbance is directly compensated, so the output of the voltage controller only needs to be fine-tuned, which reduces the burden of the voltage controller. When the load changes, the feedforward value can be quickly given, so that the PFC circuit can respond quickly to the load change, and the dynamic response speed is improved. Due to the feedforward compensation mechanism, the sensitivity of the output voltage of the PFC circuit to input voltage fluctuation and load change is reduced, and the anti-interference ability of the output voltage is enhanced. The present application also provides a PFC circuit control system, an electronic device and a computer-readable storage medium, which have the same beneficial effects as the above-mentioned PFC circuit control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A flow chart of the steps of a PFC circuit control method provided by the present invention;

[0044] Figure 2 A totem pole PFC circuit and control block diagram provided by the present invention;

[0045] Figure 3 A schematic diagram of the structure of a disturbance observer provided by the present invention;

[0046] Figure 4 A control block diagram of a voltage outer loop provided by the present invention;

[0047] Figure 5 A control block diagram of a voltage outer loop after equivalent transformation provided by the present invention;

[0048] Figure 6 A control block diagram of a voltage outer loop after using a disturbance observer provided by the present invention;

[0049] Figure 7 A diagram showing the relationship between bus output voltage and time after using a disturbance observer provided by the present invention;

[0050] Figure 8 A diagram showing the relationship between bus output voltage and time without using a disturbance observer provided by the present invention;

[0051] Fig. 9 A diagram showing the relationship between the output of a voltage controller and time after using a disturbance observer provided by the present invention;

[0052] Fig.10 A diagram showing the relationship between the output and time of a voltage controller provided by the present invention without using a disturbance observer;

[0053] Fig.11 A schematic diagram of the structure of a PFC circuit control system provided by the present invention;

[0054] Fig.12 A schematic diagram of the structure of an electronic device provided by the present invention;

[0055] Fig.13 This is a schematic diagram of the structure of a computer-readable storage medium provided by the present invention. DETAILED DESCRIPTION

[0056] The core of the present invention is to provide a PFC circuit control method, system, device and readable storage medium, which can reduce the burden of the voltage controller. When the load changes, the feedforward value can be quickly given, so that the PFC circuit can respond quickly to the load change, thereby improving the dynamic response speed.

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] First, please refer to Figure 1 , Figure 1 A flow chart of the steps of a PFC circuit control method provided by the present invention, the PFC circuit control method comprising:

[0059] S101: Acquire an output voltage signal of a PFC circuit and an initial reference current signal generated by a voltage outer loop based on the output voltage signal;

[0060] It can be understood that the PFC circuit is usually located between the power supply and the load, and is used to process the AC input voltage from the power supply and provide a stable DC output voltage for the load at the subsequent stage. The PFC circuit can adopt a totem pole structure. The totem pole PFC circuit is mainly used to improve the power factor of power electronic equipment and reduce harmonic pollution. Of course, in addition to the totem pole structure, other topologies can also be used, such as single-phase Boost structure, bridgeless structure, etc. Please refer to Figure 2 , Figure 2 A schematic diagram of a totem pole PFC circuit provided in this embodiment includes an inductor L, four switch tubes, respectively denoted as S1, S2, S3 and S4, a capacitor C and a resistor R L The load consists of output voltage V0, power supply voltage V AC , Kv represents the proportional gain, K I Indicates the integral gain, K vin Represents the input signal gain, V ref Represents the reference voltage signal, Represents a sine wave generator with a frequency of express.

[0061] Since the PFC circuit needs to track the waveform of the input voltage and synchronize its input current with it, the stability of the output voltage can indirectly reflect the fluctuation of the input voltage, and the stability of the output voltage will affect the quality of the load current. For example, a large fluctuation of the output voltage will cause harmonics in the load current. Therefore, this embodiment acquires the output voltage signal of the PFC circuit so as to better analyze the source and characteristics of the load current disturbance in the future, so as to more accurately estimate and compensate for the load current disturbance caused by the input voltage fluctuation and load change.

[0062] Specifically, the output voltage signal of the PFC circuit can be obtained through a voltage sensor to improve accuracy and linearity. Two resistors can be connected in series at the output end of the PFC circuit to form a resistor divider to obtain the output voltage signal of the PFC circuit to reduce costs. The output voltage signal of the PFC circuit can also be indirectly estimated by current measurement. Of course, in addition to the above methods, other methods can also be used, which are not specifically limited in this embodiment.

[0063] In this embodiment, the control of the PFC circuit adopts PI dual-loop control, including a voltage outer loop and a current inner loop. The voltage outer loop is used to maintain the stability of the output voltage of the PFC circuit so that it meets the set reference voltage signal, and the current inner loop is used to make the input current waveform of the PFC circuit track the input voltage waveform, thereby achieving a high power factor. Specifically, the voltage outer loop monitors the output voltage signal of the PFC circuit, compares the output voltage signal with the set reference voltage signal and calculates the error, adjusts the error through the PI controller, and generates an initial reference current signal. It can be understood that the output signal of the voltage outer loop is the set value of the current inner loop. The current inner loop monitors the inductor current signal of the PFC circuit, compares the measured inductor current signal with the current reference signal generated by the voltage outer loop, calculates the error, adjusts the error through the PI controller, and generates a control signal, which is used to control the switching device (such as MOSFET (Metal-Oxide-SemiconductorField-Effect-Transistor, Metal Oxide Semiconductor Field-Effect-Transistor) or IGBT (Insulated Gate Bipolar Transistor, Insulated Gate Bipolar Transistor)) in the PFC circuit.

[0064] S102: Obtain a load current disturbance signal using the output voltage signal and a current signal corresponding to the inductor in the PFC circuit;

[0065] Reference Figure 2 As shown, the PFC circuit includes an inductor. In this embodiment, the current signal corresponding to the inductor is monitored. It can be understood that if the load current disturbance signal is zero or close to zero, it means that the actual current signal of the inductor tracks the reference current well, that is, the PFC circuit works in an ideal state. If the disturbance signal is not 0, it means that the load has changed. Based on this, in this embodiment, the current disturbance signal can be jointly estimated by the current signal corresponding to the inductor and the output voltage signal. The combination of the output voltage signal and the current signal corresponding to the inductor can more accurately reflect the actual working state of the system, can detect load changes more quickly, and make corresponding adjustments, thereby improving the dynamic response speed of the system. In addition, under different load conditions, the change patterns of current and voltage may be different. Jointly estimating the load current disturbance signal can better adapt to these changes and improve the robustness of the system.

[0066] The current signal corresponding to the inductor may be a current signal actually flowing through the inductor or a reference current signal, which may be selected according to actual engineering needs and is not specifically limited in this embodiment.

[0067] S103: Obtaining an actual reference current signal of the current inner loop according to the initial reference current signal and the load current disturbance signal.

[0068] In combination with the above, the initial reference current signal in this embodiment is a voltage appearance based on the output voltage signal of the PFC circuit, and the load current disturbance signal is superimposed on the initial reference current signal to obtain the actual reference current signal of the current inner loop. By inputting the predicted load current disturbance signal as a feedforward signal into the current inner loop, the current reference signal of the current inner loop can be adjusted in advance before the actual load change occurs, thereby compensating for the load disturbance in advance, reducing the fluctuation of the output voltage caused by the load mutation, maintaining the stability of the output voltage, and optimizing the dynamic performance of the entire PFC circuit.

[0069] Furthermore, the actual reference current signal will be sent to the PI controller of the current inner loop. The PI controller will compare the actual current signal of the inductor with the actual reference current signal and adjust the control signal of the switching device based on this error signal to maintain the stability of the output voltage and reduce the harmonics of the input current.

[0070] In this way, the inner current loop can respond quickly to load changes, while the outer voltage loop is responsible for long-term voltage regulation. The two work together to ensure efficient and stable operation of the PFC circuit. This dual-loop control strategy enables the PFC circuit to maintain a high power factor and a stable output voltage under various load conditions.

[0071] It can be seen that in this embodiment, the load current disturbance signal caused by input voltage fluctuation and load change is estimated through the output voltage signal of the PFC circuit and the reference current signal output by the voltage outer loop, and the estimated load current disturbance signal is used to feedforward compensate the initial reference current signal output by the voltage outer loop, thereby obtaining the actual reference current signal of the current inner loop. Through feedforward compensation, the load disturbance is directly compensated, so the output of the voltage controller only needs to be fine-tuned, which reduces the burden of the voltage controller. When the load changes, the feedforward value can be quickly given, so that the PFC circuit can respond quickly to the load change, and the dynamic response speed is improved. Due to the feedforward compensation mechanism, the sensitivity of the output voltage of the PFC circuit to input voltage fluctuation and load change is reduced, and the anti-interference ability of the output voltage is enhanced.

[0072] Based on the above embodiments:

[0073] In an exemplary embodiment, the process of obtaining a load current disturbance signal by using an output voltage signal and a current signal corresponding to an inductor in a PFC circuit includes:

[0074] The output voltage signal and the current signal corresponding to the inductor in the PFC circuit are input into the disturbance observer to estimate the load current disturbance signal; the disturbance observer is created based on the mathematical model of the PFC circuit.

[0075] In this embodiment, in order to more effectively monitor and respond to load changes, a disturbance observer is used to observe the load current. As a key tool to enhance the performance and stability of the control system, the core operating mechanism of the disturbance observer varies with the application scenario. The commonality is that it accurately observes and estimates the disturbance factors inside and outside the system (covering external interference and internal uncertainty), and then incorporates targeted compensation measures into the control logic to effectively weaken or eliminate these disturbance factors. This solution does not rely on a detailed system model, but focuses on dynamic monitoring and real-time adjustment, thereby improving the robustness and adaptability of the system.

[0076] In order to make the disturbance observer better match the actual circuit behavior, the key parameters of the PFC circuit, such as the characteristics of the inductor, capacitor, and switch device, are first obtained. The mathematical model of the PFC circuit is determined based on these key parameters. The mathematical model is used to describe the dynamic behavior of the PFC circuit. Then, the disturbance observer is established using the mathematical model of the PFC circuit, thereby reducing the error in the observer estimation process, improving the accuracy of the control strategy, and more accurately predicting and estimating the disturbance in the PFC circuit. In addition, the mathematical model can describe the dynamic characteristics of the PFC circuit, including the impact of factors such as load changes and switching actions on the system, which is conducive to the disturbance observer providing accurate estimates when the system changes dynamically. The output voltage signal of the PFC circuit and the current signal corresponding to the inductor are used as inputs and input into the disturbance observer designed based on the mathematical model. The disturbance observer estimates and predicts the load current disturbance through these signals, without the need for additional sensors to directly measure the load current disturbance, reducing the design cost and volume of the power supply.

[0077] In an exemplary embodiment, the output voltage signal and the current signal corresponding to the inductor in the PFC circuit are input into the disturbance observer, and the process of estimating the load current disturbance signal includes:

[0078] The output voltage signal is input into the observation module of the disturbance observer to obtain the prediction signal; the observation module is created based on the inverse model of the filter and the mathematical model;

[0079] Inputting a current signal corresponding to the inductor in the PFC circuit into a first filtering module of a disturbance observer to obtain a filtered current signal; the first filtering module is created based on a filter;

[0080] A load current disturbance signal is obtained according to the prediction signal and the filtered current signal.

[0081] In this embodiment, the disturbance observer mainly includes an observation module and a first filtering module. The output voltage signal of the PFC circuit is input into the observation module of the disturbance observer. The observation module contains a filter and an inverse model of the mathematical model, wherein the filter is used to process the signal, and the inverse model is used to predict the state of the system according to the output voltage signal. Through this process, the observation module generates a prediction signal, which reflects the ideal state of the system in the absence of disturbance.

[0082] At the same time, the current signal corresponding to the inductor in the PFC circuit is input into the first filter module of the disturbance observer. The first filter module processes the current signal based on the same filter design (corresponding to the filter in the observation module) to reduce noise and irrelevant high-frequency components and obtain a filtered current signal. By comparing the predicted signal with the actual signal, the disturbance observer can estimate the load current disturbance signal, which facilitates the controller to more accurately adjust the operation of the PFC circuit to compensate for these disturbances.

[0083] Specifically, the predicted signal is subtracted from the filtered current signal to obtain the load current disturbance signal. It can be understood that if the predicted signal is very close to the ideal current signal in the absence of disturbance, then the difference will mainly represent the actual disturbance caused by the load change.

[0084] In an exemplary embodiment, the process of obtaining the load current disturbance signal according to the prediction signal and the filtered current signal includes:

[0085] Obtaining an intermediate current disturbance signal according to the filtered current signal and the prediction signal;

[0086] The second filtering module of the disturbance observer is used to filter the double power frequency ripple in the intermediate current disturbance signal to obtain the load current disturbance signal.

[0087] In this embodiment, the disturbance observer also includes a second filtering module, which subtracts the filtered current signal from the predicted signal through a subtraction operation to obtain an intermediate current disturbance signal. This intermediate signal may contain the real disturbance caused by the load change and other high-frequency noise and ripples that may exist. The second filtering module of the disturbance observer is used to process the intermediate current disturbance signal. Considering that in the PFC circuit, since the input current needs to track the input voltage and shape it, a ripple component of twice the power frequency may be introduced into the current signal. The second filtering module in this embodiment is used to filter out the twice power frequency ripple in the signal and retain the low-frequency component related to the load disturbance. By filtering out the twice power frequency ripple, a more accurate load current disturbance signal can be obtained, which helps to improve the performance of the controller. At the same time, removing unnecessary ripple components can reduce the malfunction of the controller, thereby improving the stability and reliability of the system. It can be understood that the accurate load current disturbance signal enables the PFC circuit to perform power factor correction more effectively, thereby optimizing the overall control effect.

[0088] In an exemplary embodiment, the PFC circuit control method further includes:

[0089] Get the mathematical model of the PFC circuit;

[0090] Determine the disturbance observation structure and disturbance observation parameters based on the mathematical model;

[0091] Create a disturbance observer using the disturbance observer structure and disturbance observer parameters.

[0092] In this embodiment, the topology of the PFC circuit is first determined, including the connection mode of components such as switch devices, inductors, capacitors, etc., and then the state space model of the PFC circuit is established, including modeling of various components of the circuit, such as the current of the inductor, the voltage of the capacitor, etc. Specifically, according to the working principle and load characteristics of the PFC circuit, the state space averaging method is used to obtain the small signal model of the PFC circuit. The small signal model is convenient for analyzing the dynamic characteristics of the circuit when the input voltage or load current changes slightly. It is usually expressed by differential equations or transfer functions. The mathematical model is used to reflect the relationship between the input voltage, load current and internal parameters of the system.

[0093] Select appropriate observer structures, such as Luenberger observer, Kalman filter, etc. These observers can estimate state variables and disturbances according to the input and output of the system. According to the mathematical model and the selected observer structure, calculate or adjust the observer parameters, such as gain matrix, filter coefficient, etc., to ensure that the observer can accurately and quickly observe the changes in load current. After determining the observer structure and parameters, implement them as algorithms, which can be done through programming, such as integrating the disturbance observer into the control system of the PFC circuit on a digital signal processor (DSP) or microcontroller (MCU), so that it can run in real time and estimate the load current disturbance. Specifically, according to the observed disturbance information, introduce corresponding compensation measures in the control strategy. The compensation measures may include adjusting the output of the controller, changing the duty cycle of the PWM (pulse width modulation) signal, etc., to suppress the influence of the disturbance on the load current. The disturbance observer can effectively estimate the load current disturbance in the PFC circuit, thereby improving the performance of the control system, so that the PFC circuit can better cope with load changes and maintain efficient power factor correction.

[0094] Specifically, refer to Figure 3 , Figure 3 is a schematic diagram of a disturbance observer. Through the disturbance observer, the disturbance observation of the system can be obtained as ;

[0095] The control quantity after feeding forward the disturbance observation value is ;

[0096] Combining the above two equations, we can get the final expression of the observed value: ;

[0097] From the final expression of the observed value, it can be seen that the relationship between the observed value of interference and the actual interference and environmental noise is that the first term in the formula can be regarded as the modeling error. Under reasonable conditions, the disturbance observer can realize accurate real-time observation of disturbances. Often does not satisfy causality and is physically unrealizable. In order to ensure the rationality of the design, it is necessary to increase the order of the equation. Considering the reduction of environmental noise and system order, the filter It is often designed in the form of a low-pass filter. At the same time, most disturbances can be regarded as low-frequency signals, and low-pass filters can effectively suppress interference.

[0098] In summary, design The following two items are mainly considered: The filter order must be greater than or equal to the order of the controlled object to ensure feasibility; The higher the cutoff frequency, the more environmental disturbances can be observed. However, many disturbances are not the focus of attention, and it is necessary to select a suitable cutoff frequency according to actual needs. In order to suppress interference by observing interference feedforward, Figure 3 It can be seen that the system output and the controller output , system disturbance and environmental noise The relationship between the variables is ;

[0099] To simplify the analysis, is the modeling error, that is ;

[0100] Combine system output with controller output , system disturbance and environmental noise The relationship between equal variables is simplified to:

[0101] ;

[0102] From the above formula, we can see that When is equal to 1, the system can achieve complete estimation of the disturbance, but the disturbance observer does not satisfy causality. The current inner loop of the PFC circuit can be simplified to a first-order system under low-frequency conditions and the load disturbance can be regarded as a bounded or asymptotically stable interference signal under most working conditions. Designing it as a first-order low-pass filter can not only ensure the accuracy of disturbance observation but also simplify the difficulty of design.

[0103] According to the analysis of the above principles, most of the load disturbances of the power supply are bounded disturbances, which can be It is designed in the form of a first-order low-pass filter. Considering that the output voltage signal to be collected contains twice the industrial frequency ripple, the bandwidth can be set below 100 Hz.

[0104] Reference Figure 4 As shown in the figure, when the inner current loop is stable, the inductor current can completely follow the reference current. Because the bandwidth of the outer voltage loop is low, the entire current loop transfer function can be considered to be 1 at low frequencies. To simplify the analysis process and facilitate understanding, the current loop at low frequencies can be approximately equivalent to a proportional link. Figure 4 Can be transformed into Figure 5 ,from Figure 5It can be seen that when the PFC load is disturbed, the load current disturbance acts on the capacitor to feed back the voltage reference, and the error is sent to the voltage loop controller. Since the adjustment speed is too slow, the output of the voltage loop cannot respond quickly to the change of the load, which also leads to the inductor current reference value cannot be given quickly, the energy of input and output is unbalanced, and indirectly causes the problem of excessive output voltage fluctuation. The feedforward control in this embodiment can weaken or even eliminate the influence of various disturbances on the control system. By feeding the current forward to the output of the voltage controller, a new current reference control signal i is generated. REF , to achieve the effect of quickly compensating the output voltage fluctuation, the control frame after the feedforward of the disturbance observer is as follows Figure 6 shown.

[0105] Figure 4-Figure 6 In, V REF is the reference voltage source, e(s) is the error signal, which may be the difference between the reference voltage and the actual output, K ADC is the gain coefficient of the analog-to-digital converter, Gvc(s) is the transfer function of the controller, d(t) is the load current disturbance signal, Gi_loop(s) is the transfer function of the current inner loop, i REF is the actual reference current signal, i L (s) is the current signal on the inductor, l−d represents the operation of subtracting the interference signal, 1 / SC represents a part of the feedback loop, V0(s) represents the output voltage signal, Q(s) represents the first filter module based on the filter, North(s) represents the second filter module based on the notch filter, represents the inverse model of the mathematical model, and Kv represents the proportionality coefficient.

[0106] At this time, the steady-state value of the circuit reference effective value is almost given by the feedforward, and the output of the current controller is almost 0. When the load changes, the feedforward value is quickly given, which reduces the burden on the voltage controller. The output of the voltage controller only plays a fine-tuning role, ensuring the stability of the output voltage. Load disturbance feedforward increases the speed of the system's dynamic response and strengthens the anti-disturbance ability of the PFC output voltage.

[0107] Based on the above, the disturbance observer and the mathematical model of the system have been designed in the continuous domain. In order to realize the disturbance observation function through the digital signal processor (DSP), it is necessary to discretize the transfer function in the continuous domain and convert it into a differential equation so that the digital controller can recognize and execute it. It is known that the form of the low-pass filter is ,So It can be expressed as ; Where d is the duty cycle signal, C is the value of the bus capacitance, and a is the selected bandwidth parameter.

[0108] Using bilinear transformation, It can be expressed as ,in, is the sampling time.

[0109] As another optional embodiment, the performance of the observer is verified by simulation or experiment, and optimized as needed. The optimization may include adjusting observer parameters, improving algorithm structure, etc. Specifically, the effectiveness and reliability of the observer are verified in the actual PFC circuit system to ensure that the observer can accurately observe the load current and effectively suppress disturbances in the control strategy. It can be understood that due to the diversity of PFC circuits and loads, different PFC circuit types, such as Boost, Buck-Boost, etc., and different load characteristics (such as linear, nonlinear, etc.) may require different mathematical models and observer structures. The above-mentioned specific implementation details may be different. Therefore, in actual applications, it is necessary to design and adjust according to the specific PFC circuit and load characteristics.

[0110] In this embodiment, designing a disturbance observer corresponding to the PFC circuit requires comprehensive consideration of factors such as circuit model, observer structure, parameter selection, implementation method, performance evaluation and practical application. Through reasonable design and optimization, the disturbance observer can effectively estimate the load current disturbance in the PFC circuit, thereby improving the performance of the control system and enabling the PFC circuit to better cope with load changes and maintain efficient power factor correction.

[0111] In an exemplary embodiment, the process of determining the disturbance observation structure and the disturbance observation parameters based on the mathematical model includes:

[0112] Obtaining the initial state space equation corresponding to the mathematical model of the PFC circuit;

[0113] According to the disturbance variable superimposed on the PFC circuit and the initial state space equation, the disturbance variable equation is obtained;

[0114] The nominal model of the PFC circuit is obtained using the disturbance variable equation;

[0115] The disturbance observation structure and disturbance observation parameters are determined based on the nominal model.

[0116] In this embodiment, each component of the PFC circuit is modeled, such as voltage, current, etc., and the state equations of each component are combined to obtain the state space average equation of the entire PFC circuit. Taking the totem pole PFC circuit as an example, its state space average equation can be written as:

[0117] ;

[0118] Then, identify the possible disturbance variables in the PFC circuit, such as input voltage fluctuations, load current changes, etc., and establish a mathematical model of the disturbance variables. For example, use white noise or random processes to describe random disturbances, superimpose the disturbance variables on the initial state space equation, and obtain the disturbance variable equation. Take the uncertainty factors (disturbance variables) in the PFC circuit into account to establish a more comprehensive mathematical model, making the model closer to the actual situation and improving the accuracy and reliability of the model.

[0119] Specifically, the steady-state operating point of the PFC circuit is first determined, that is, the steady-state values ​​of the input voltage, load current and circuit elements. At the steady-state operating point, a disturbance is added to the variables such as the voltage, current or switch state of the circuit elements to obtain the variable expression after the disturbance. The variable expression after the disturbance is substituted into the initial state space equation and separated to obtain an equation containing only the disturbance variable, that is, , perform Laplace transform on the equation containing only the disturbance variable, and obtain the expression of the disturbance variable in the frequency domain ,Using the frequency domain expression of the disturbance variable, the nominal model of PFC can be established, which describes the response of PFC to external disturbances and ignores the influence of the steady-state operating point.

[0120] It can be understood that the nominal model only contains the key variables and parameters that have the greatest impact on the dynamic behavior of the system, which reduces the amount of data in the model, reduces the difficulty of designing the disturbance observer, reduces the design cost, reduces computing resources, and facilitates simulation and testing.

[0121] In an exemplary embodiment, the PFC circuit control method further includes:

[0122] Obtaining the actual current signal flowing through the inductor in the PFC circuit;

[0123] The actual current signal is used as the current signal corresponding to the inductor in the PFC circuit.

[0124] In this embodiment, the actual current signal is directly measured and has high accuracy and reliability. The actual current signal can reflect the dynamic behavior of the PFC system in real time and can more accurately reflect the changes in the load current, thereby improving the accuracy of the disturbance observer estimation. Using the actual current signal as input eliminates the need to design additional circuits, thereby simplifying the system structure.

[0125] In an exemplary embodiment, the PFC circuit control method further includes:

[0126] The initial reference current signal is used as a current signal corresponding to the inductor in the PFC circuit.

[0127] In this embodiment, the reference current signal is filtered and has strong anti-noise interference capability. Even when there is noise in the actual current signal, the robustness of the disturbance observer can be guaranteed. No hardware equipment such as current sensors is required, which reduces the system cost. The reference current signal can be obtained directly from the voltage outer loop without additional signal processing.

[0128] As an optional embodiment, the initial reference current signal or the actual current signal can be selected as the input of the disturbance observer according to the current application scenario. For example, the actual current signal is more suitable for application scenarios with higher accuracy requirements, such as high power density power supply, motor drive, etc. The reference current signal is more suitable for application scenarios with higher cost and robustness requirements, such as general power supply, household appliances, etc. It can be set according to the actual engineering needs, and this embodiment is not specifically limited here.

[0129] Specifically, the simulation was built using PLECS software, and the disturbance observer program was written using the C script module in PLECS. The final simulation effect is as follows: Figure 7-Figure 10 As shown in the figure, it can be seen from the simulation results that when the disturbance observation feedforward without DOB (Disturbance Observer) is added, the bus voltage drops by 19.55V. After adding the feedforward, the voltage drops to 7.82V. Before adding the DOB disturbance observation feedforward, the reference value amplitude of the inductor current is almost determined by the output value of the voltage controller. After the load is switched, it takes 200ms to return to a stable state. The dynamic performance of the voltage loop is poor. After adding the DOB disturbance observation feedforward, the output of the PI controller is close to 0. The inductor current reference value is largely determined by the current feedforward term. The use of DOB disturbance observation feedforward can greatly reduce the burden of the voltage outer loop controller and has a stronger dynamic response capability.

[0130] Second, please refer to Fig.11 The present invention also provides a PFC circuit control system, comprising:

[0131] A first acquisition module 11 is used to acquire an output voltage signal of the PFC circuit and an initial reference current signal generated by a voltage outer loop based on the output voltage signal;

[0132] A first calculation module 12 is used to obtain a load current disturbance signal using the output voltage signal and a current signal corresponding to the inductor in the PFC circuit;

[0133] The second calculation module 13 is used to obtain an actual reference current signal of the current inner loop according to the initial reference current signal and the load current disturbance signal.

[0134] It can be seen that in this embodiment, the load current disturbance signal caused by input voltage fluctuation and load change is estimated through the output voltage signal of the PFC circuit and the reference current signal output by the voltage outer loop, and the estimated load current disturbance signal is used to feedforward compensate the initial reference current signal output by the voltage outer loop, thereby obtaining the actual reference current signal of the current inner loop. Through feedforward compensation, the load disturbance is directly compensated, so the output of the voltage controller only needs to be fine-tuned, which reduces the burden of the voltage controller. When the load changes, the feedforward value can be quickly given, so that the PFC circuit can respond quickly to the load change, and the dynamic response speed is improved. Due to the feedforward compensation mechanism, the sensitivity of the output voltage of the PFC circuit to input voltage fluctuation and load change is reduced, and the anti-interference ability of the output voltage is enhanced.

[0135] In an exemplary embodiment, the process of obtaining a load current disturbance signal by using an output voltage signal and a current signal corresponding to an inductor in a PFC circuit includes:

[0136] The output voltage signal and the current signal corresponding to the inductor in the PFC circuit are input into the disturbance observer to estimate the load current disturbance signal; the disturbance observer is created based on the mathematical model of the PFC circuit.

[0137] In an exemplary embodiment, the output voltage signal and the current signal corresponding to the inductor in the PFC circuit are input into the disturbance observer, and the process of estimating the load current disturbance signal includes:

[0138] The output voltage signal is input into the observation module of the disturbance observer to obtain the prediction signal; the observation module is created based on the inverse model of the filter and the mathematical model;

[0139] Inputting a current signal corresponding to the inductor in the PFC circuit into a first filtering module of a disturbance observer to obtain a filtered current signal; the first filtering module is created based on a filter;

[0140] A load current disturbance signal is obtained according to the prediction signal and the filtered current signal.

[0141] In an exemplary embodiment, the process of obtaining the load current disturbance signal according to the prediction signal and the filtered current signal includes:

[0142] Obtaining an intermediate current disturbance signal according to the filtered current signal and the prediction signal;

[0143] The second filtering module of the disturbance observer is used to filter the double power frequency ripple in the intermediate current disturbance signal to obtain the load current disturbance signal.

[0144] In an exemplary embodiment, the PFC circuit control system further includes:

[0145] A second acquisition module is used to acquire a mathematical model of the PFC circuit;

[0146] A first determination module is used to determine a disturbance observation structure and a disturbance observation parameter based on a mathematical model;

[0147] Create a module for creating a disturbance observer using a disturbance observer structure and disturbance observer parameters.

[0148] In an exemplary embodiment, the process of determining the disturbance observation structure and the disturbance observation parameters based on the mathematical model includes:

[0149] Obtaining the initial state space equation corresponding to the mathematical model of the PFC circuit;

[0150] According to the disturbance variable superimposed on the PFC circuit and the initial state space equation, the disturbance variable equation is obtained;

[0151] The nominal model of the PFC circuit is obtained using the disturbance variable equation;

[0152] The disturbance observation structure and disturbance observation parameters are determined based on the nominal model.

[0153] In an exemplary embodiment, the PFC circuit control system further includes:

[0154] A third acquisition module is used to acquire an actual current signal flowing through the inductor in the PFC circuit;

[0155] A second determination module is used to use the actual current signal as a current signal corresponding to the inductor in the PFC circuit;

[0156] or,

[0157] The third determination module is configured to use the initial reference current signal as a current signal corresponding to the inductor in the PFC circuit.

[0158] Third, please refer to Fig.12 The present invention also provides an electronic device, comprising:

[0159] A memory 21, used for storing computer programs;

[0160] The processor 22 is configured to implement the steps of the PFC circuit control method described in any one of the above embodiments when executing a computer program.

[0161] The electronic device also includes:

[0162] The input interface 23 is connected to the processor 22 via the communication bus 26, and is used to obtain the computer programs, parameters and instructions imported from the outside, and save them in the memory 21 under the control of the processor 22. The input interface can be connected to an input device to receive parameters or instructions manually input by the user. The input device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the terminal housing.

[0163] The display unit 24 is connected to the processor 22 via the communication bus 26 and is used to display the data sent by the processor 22. The display unit can be a liquid crystal display or an electronic ink display.

[0164] The network port 25 is connected to the processor 22 via the communication bus 26, and is used to communicate with various external terminal devices. The communication technology used in the communication connection can be a wired communication technology or a wireless communication technology, such as mobile high-definition link technology, universal serial bus, high-definition multimedia interface, wireless fidelity technology, Bluetooth communication technology, low-power Bluetooth communication technology, communication technology based on IEEE802.11s, etc.

[0165] Fourth, please refer to Fig.13 The present invention further provides a computer-readable storage medium 30, on which a computer program 31 is stored. When the computer program 31 is executed by a processor, the steps of the PFC circuit control method described in any one of the above embodiments are implemented.

[0166] The computer-readable storage medium 30 may include: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store program codes.

[0167] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0168] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A PFC circuit control method, characterized in that: include: Acquire an output voltage signal of the PFC circuit, and an initial reference current signal generated by a voltage outer loop based on the output voltage signal; Obtaining a load current disturbance signal using the output voltage signal and a current signal corresponding to an inductor in the PFC circuit; An actual reference current signal of a current inner loop is obtained according to the initial reference current signal and the load current disturbance signal.

2. The PFC circuit control method according to claim 1, characterized in that: The process of obtaining a load current disturbance signal by using the output voltage signal and a current signal corresponding to the inductor in the PFC circuit includes: The output voltage signal and a current signal corresponding to the inductance in the PFC circuit are input into a disturbance observer to estimate a load current disturbance signal; the disturbance observer is created based on a mathematical model of the PFC circuit.

3. The PFC circuit control method according to claim 2, characterized in that: The process of inputting the output voltage signal and the current signal corresponding to the inductor in the PFC circuit into a disturbance observer to estimate the load current disturbance signal includes: Inputting the output voltage signal into an observation module of a disturbance observer to obtain a prediction signal; the observation module is created based on a filter and an inverse model of the mathematical model; Inputting a current signal corresponding to the inductance in the PFC circuit into a first filtering module of the disturbance observer to obtain a filtered current signal; the first filtering module is created based on the filter; A load current disturbance signal is obtained according to the prediction signal and the filtered current signal.

4. The PFC circuit control method according to claim 3, characterized in that: The process of obtaining the load current disturbance signal according to the prediction signal and the filtered current signal includes: Obtaining an intermediate current disturbance signal according to the filtered current signal and the prediction signal; The second filtering module of the disturbance observer is used to filter the double power frequency ripple in the intermediate current disturbance signal to obtain a load current disturbance signal.

5. The PFC circuit control method according to claim 2, characterized in that: The PFC circuit control method further includes: Obtaining a mathematical model of the PFC circuit; Determining a disturbance observation structure and disturbance observation parameters based on the mathematical model; The disturbance observer is created using the disturbance observer structure and the disturbance observer parameters.

6. The PFC circuit control method according to claim 5, characterized in that: The process of determining the disturbance observation structure and the disturbance observation parameters based on the mathematical model includes: Obtaining an initial state space equation corresponding to the mathematical model of the PFC circuit; Obtaining a disturbance variable equation according to the disturbance variable superimposed on the PFC circuit and the initial state space equation; Obtaining a nominal model of the PFC circuit using the disturbance variable equation; A disturbance observation structure and disturbance observation parameters are determined based on the nominal model.

7. The PFC circuit control method according to any one of claims 1 to 6, characterized in that: The PFC circuit control method further includes: Acquiring an actual current signal flowing through an inductor in the PFC circuit; Using the actual current signal as a current signal corresponding to the inductor in the PFC circuit; or, The initial reference current signal is used as a current signal corresponding to the inductor in the PFC circuit.

8. A PFC circuit control system, characterized in that: include: A first acquisition module, used for acquiring an output voltage signal of the PFC circuit and an initial reference current signal generated by a voltage outer loop based on the output voltage signal; A first calculation module, used to obtain a load current disturbance signal by using the output voltage signal and a current signal corresponding to the inductor in the PFC circuit; The second calculation module is used to obtain an actual reference current signal of the current inner loop according to the initial reference current signal and the load current disturbance signal.

9. An electronic device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the PFC circuit control method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the PFC circuit control method according to any one of claims 1 to 7 are implemented.

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