PFC loop control system and control method thereof

Abstract

The invention discloses a PFC loop control system and a control method thereof. The system comprises a rectification circuit, a modulation circuit and an upper computer. The input end of the rectification circuit is connected with an AC power supply, and the output end of the rectification circuit is connected with the load and the modulation circuit. The input end of the modulation circuit is connected with the rectification circuit and the upper computer. The output end of the modulation circuit is connected with the rectification circuit; the modulation circuit generates a current reference signal according to the actual output voltage and the reference voltage, generates a control signal according to the current reference signal, and adjusts the duty ratio of a PWM signal input to the rectification circuit through the control signal, thereby controlling the output power of the rectification circuit. When the load is in the dynamic switching state, the input current can be stably controlled, it is guaranteed that the alternating current power supply and the load can normally and stably operate, the load and the alternating current power supply are not affected, the power factor of the system is improved, harmonic pollution is reduced, and the voltage regulation characteristic and stability of the control system are improved.

Description

Technical Field

[0001] The present invention relates to the field of loop control technology, and in particular to a PFC loop control system and a control method thereof. Background Art

[0002] Generator sets have long been widely used as the primary source of power for mobile power stations and backup power. However, with the advancement of power electronics technology, switching power supplies have become a common load for generator sets. These nonlinear loads generate significant harmonic currents, leading to harmonics and distortion in the output voltage, thus affecting the generator set's normal power supply.

[0003] Today's switching power supplies are equipped with filters and pre-stage power factor correction (PFC) devices to reduce current harmonics and optimize the power factor (PF). When the load changes suddenly, the PFC device will quickly adjust the input current to stabilize the output voltage.

[0004] However, due to the generator set's poor transient voltage regulation performance, it cannot promptly and accurately adjust its output voltage in the event of sudden load changes, causing large fluctuations in the PFC device's input voltage. These large input voltage fluctuations disrupt the normal operation of the PFC, causing the input current to exceed the normal range, thereby disrupting the normal operation of other electrical equipment on the same grid. Furthermore, input voltage fluctuations distort the current waveform in the modulation circuit, generating a large number of harmonics and significantly increasing the harmonic content of the current. These abnormal currents and high harmonic content can be fed back to the generator set, adversely affecting its control system, windings, and other components, disrupting the generator set's stable operation.

[0005] In the process of implementing the present invention, the inventors discovered that the prior art has at least the following problems: The transient voltage regulation performance of the generator set using PFC device is poor, and when the load suddenly changes, it will affect the stable operation of the electrical equipment and the generator set. Summary of the Invention

[0006] The purpose of the present invention is to provide a PFC loop control system and a control method thereof, so as to solve the technical problem in the prior art that a generator set using a PFC device has poor transient voltage regulation performance, which affects the stable operation of electrical equipment and the generator set when a sudden load change occurs.

[0007] The various technical effects that can be produced by the preferred technical solutions among the various technical solutions provided by the present invention are described in detail below.

[0008] To achieve the above objectives, the present invention provides the following technical solutions: In a first aspect, the present invention provides a PFC loop control system, comprising: a rectifier circuit, a modulation circuit, and a host computer; The input end of the rectifier circuit is connected to an AC power supply, and the output end of the rectifier circuit is connected to a load and the modulation circuit respectively; The input end of the modulation circuit is connected to the rectifier circuit and the host computer respectively, and is used to receive the actual output voltage output by the rectifier circuit and the reference voltage output by the host computer; the output end of the modulation circuit is connected to the rectifier circuit; the modulation circuit generates a current reference signal according to the actual output voltage and the reference voltage, and generates a control signal according to the current reference signal, and adjusts the duty cycle of the PWM signal input to the rectifier circuit through the control signal; The host computer is connected to the rectifier circuit and the modulation circuit respectively, and is used to detect the actual output voltage of the rectifier circuit and the previous actual output voltage, and obtain a voltage difference based on the actual output voltage and the previous actual output voltage; when the voltage difference exceeds a set threshold, the host computer adjusts the reference voltage according to the voltage difference, so that the modulation circuit adjusts the current reference signal to change the duty cycle of the PWM signal input to the rectifier circuit, thereby controlling the output power of the rectifier circuit.

[0009] Optionally, the modulation circuit includes a voltage loop module, a current loop module and a modulation module; The first input end of the voltage loop module is connected to the output end of the rectifier circuit, and is used to receive the actual output voltage of the rectifier circuit; the second input end of the voltage loop module is connected to the host computer, and is used to receive the reference voltage output by the host computer; the output end of the voltage loop module is connected to the input end of the current loop module, and is used to output the current reference signal to the current loop module; The first input end of the current loop module is connected to the output end of the voltage loop module for receiving the current reference signal, and the second input end is used to receive the current output current; the output end of the current loop module is connected to the input end of the modulation module for outputting a control signal; The output end of the modulation module is connected to the rectifier circuit.

[0010] Optionally, the voltage loop module includes a PI-type voltage controller, a first input end of the PI-type voltage controller is connected to the output end of the rectifier circuit, and a second input end is connected to the host computer; the output end of the PI-type voltage controller is used to output a control voltage signal.

[0011] Optionally, the current reference signal received by the current loop module As shown in formula (1): (1) Among them, V EAis the control voltage signal output by the PI type voltage controller, V k is the instantaneous value of the input voltage, is the effective value of the input voltage, and k is the phase A, phase B and phase C of the AC power supply.

[0012] Optionally, the control voltage signal output by the PI type voltage controller is expressed as formula (2): (2) According to formula (2) and the current reference signal , input voltage instantaneous value V k and the effective value of the input voltage The definition of is given by formula (3): (3) Where A is current, V is voltage, and W is power.

[0013] Optionally, the difference between the reference voltage calculated by the host computer and the actual output voltage output by the rectifier circuit As shown in formula (4): (4) in, is the reference voltage, is the actual output voltage; The control voltage signal V output by the PI type voltage controller EA The difference between the reference voltage calculated by the host computer and the actual output voltage output by the rectifier circuit Adjustments are made based on the difference Adjust the control voltage signal V output by the PI type voltage controller EA As shown in formula (5): (5) in, is the proportionality coefficient, is the integration coefficient.

[0014] Optionally, the rectifier circuit includes a filtering module and a rectifier module; the input end of the filtering module is connected to the AC power supply, and the output end is connected to the rectifier module; the input end of the rectifier module is respectively connected to the filtering module and the modulation module, and the output end is connected to the modulation circuit and the load.

[0015] Optionally, the rectifier module is a three-phase full-bridge rectifier module.

[0016] In a second aspect, the present invention further provides a PFC loop control method, comprising: The host computer detects the current actual output voltage and the previous actual output voltage of the rectifier circuit, and calculates the voltage difference between the current actual output voltage and the previous actual output voltage; When the voltage difference is greater than a set threshold, the host computer sets the current actual output voltage as a reference voltage output to the modulation circuit; The modulation circuit is slowly started according to a predetermined step length, the output of the modulation circuit is changed, and the duty cycle of the PWM signal input to the rectifier circuit is adjusted.

[0017] Optionally, the setting step size S t It is expressed by the following formula: Among them, E rrv is the voltage difference between the current actual output voltage and the previous actual output voltage, T rec It is the minimum voltage recovery time.

[0018] Implementing one of the above technical solutions of the present invention has the following advantages or beneficial effects: The PFC loop control system described in this invention can determine the current dynamic load status. The host computer in this embodiment monitors the output voltage of the rectifier circuit and the load dynamics in real time. If the load is in a dynamic switching state, the host computer adjusts the reference voltage input to the modulation circuit in real time, changing the current reference signal output by the modulation circuit. The current reference signal, under the influence of the modulation circuit, generates a control signal. This control signal adjusts the duty cycle of the PWM signal input to the rectifier circuit, ultimately controlling the output power of the rectifier circuit.

[0019] The present invention adjusts the reference voltage input to the modulation circuit and the current reference signal so that the control signal output by the modulation circuit adjusts the rectifier circuit. When the load is in a dynamic switching state, the input current can be smoothly controlled to ensure that the AC power supply and the load can operate normally and stably without affecting the load and the AC power supply, thereby improving the power factor of the system, reducing harmonic pollution, and improving the voltage regulation characteristics and stability of the control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work. In the drawings: Figure 1 This is a schematic diagram of the overall structural connection of a PFC loop control system according to a first embodiment of the present invention; Figure 2 1 is a circuit diagram of a PFC loop control system according to a first embodiment of the present invention; Figure 3 1 is a circuit structure diagram of a PFC loop control system according to a first embodiment of the present invention; Figure 4 This is a flow chart of a PFC loop control method according to a second embodiment of the present invention.

[0021] In the figure: 1. Rectifier circuit; 11. Filter module; 12. Rectifier module; 2. Modulation circuit; 21. Voltage loop module; 22. Current loop module; 23. Modulation module. DETAILED DESCRIPTION

[0022] In order to make the objects, technical solutions and advantages of the present invention clearer, the various exemplary embodiments to be described below will refer to the corresponding drawings, which constitute a part of the exemplary embodiments, in which various exemplary embodiments that may be used to implement the present invention are described. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present disclosure. It should be understood that they are only examples of processes, methods and devices that are consistent with some aspects of the present disclosure as detailed in the appended claims, and other embodiments may also be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and essence of the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", etc. indicate the orientation or position relationship based on the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the elements referred to must have a specific orientation, be constructed and operate in a specific orientation. The terms "first", "second", etc. are only used for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The term "plurality" means two or more. The terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a communication connection, a direct connection, an indirect connection through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0024] In order to illustrate the technical solution of the present invention, a specific embodiment is provided below, in which only the parts related to the embodiment of the present invention are shown.

[0025] Example 1: like Figure 1-3 As shown, the present invention provides a PFC loop control system, comprising: a rectifier circuit 1, a modulation circuit 2, and a host computer; the input end of the rectifier circuit 1 is connected to an AC power supply, and the output end of the rectifier circuit 1 is connected to a load and the modulation circuit 2 respectively; the input end of the modulation circuit 2 is connected to the rectifier circuit 1 and the host computer respectively, for receiving the actual output voltage output by the rectifier circuit 1 and the reference voltage output by the host computer; the output end of the modulation circuit 2 is connected to the rectifier circuit 1; the modulation circuit 2 generates a current reference signal according to the actual output voltage and the reference voltage, and generates a control signal according to the current reference signal, and adjusts the duty cycle of the PWM signal input to the rectifier circuit 1 through the control signal; the host computer is connected to the rectifier circuit 1 and the modulation circuit 2 respectively, and is used to detect the actual output voltage of the rectifier circuit 1 and the previous actual output voltage, and obtain a voltage difference based on the actual output voltage and the previous actual output voltage; when the voltage difference exceeds a set threshold, the host computer adjusts the reference voltage according to the voltage difference, so as to adjust the current reference signal to change the duty cycle of the PWM signal input to the rectifier circuit 1, thereby controlling the output power of the rectifier circuit 1.

[0026] The PFC loop control system described in this embodiment includes a rectifier circuit 1 , a modulation circuit 2 and a host computer.

[0027] Rectifier circuit 1 converts AC power from an AC power source into DC power. Its input is connected to the AC power source to receive AC power. Its output is connected to a load to provide DC power. It also connects to modulation circuit 2 to transmit the converted DC voltage signal (i.e., the actual output voltage) to modulation circuit 2.

[0028] The function of modulation circuit 2 is to receive the actual output voltage output by rectifier circuit 1 and the reference voltage output by the host computer, and generate a current reference signal based on the actual output voltage and the reference voltage, generate a control signal based on the current reference signal, and use the control signal to adjust the duty cycle of the PWM (pulse width modulation) signal input to rectifier circuit 1.

[0029] The host computer's role is to provide a reference voltage for modulation circuit 2. This reference voltage represents the voltage value that the system expects rectifier circuit 1 to output and is a key parameter in modulation circuit 2. Specifically, the host computer also detects the actual output voltage of rectifier circuit 1 and records the previous actual output voltage. By comparing the current actual output voltage with the previous actual output voltage, the host computer calculates the voltage difference between the two, which reflects the change in output voltage. It should be noted that the host computer can be a computer, controller, or other device.

[0030] More specifically, a reference voltage (which can be a voltage threshold) is pre-set in the host computer. During actual operation, the host computer calculates the voltage difference between the actual output voltage and the reference voltage. When the calculated voltage difference exceeds the reference voltage, it indicates that the output voltage variation has exceeded the allowable range and requires adjustment. At this point, the host computer adjusts the reference voltage based on the voltage difference to achieve the purpose of regulating the current reference signal.

[0031] The current reference signal is one of the key signals controlling the operation of rectifier circuit 1. It determines the control signal, which in turn determines the duty cycle of the PWM signal input to rectifier circuit 1. The duty cycle of a PWM signal refers to the ratio of the high-level duration of a pulse signal to the entire cycle. Changing the duty cycle can control the on-time of the switching devices in rectifier circuit 1, thereby changing the input power of rectifier circuit 1 and ultimately controlling the output power of rectifier circuit 1.

[0032] The PFC loop control system described in this embodiment can confirm the current dynamic load status. The host computer in this embodiment can monitor the output voltage of rectifier circuit 1 and the load dynamics in real time. If the load is in a dynamic switching state, the host computer will adjust the reference voltage input to modulation circuit 2 in real time, changing the current reference signal output by modulation circuit 2. The current reference signal is then used by modulation circuit 2 to generate a control signal. This control signal is used to adjust the duty cycle of the PWM signal input to rectifier circuit 1, ultimately controlling the output power of rectifier circuit 1.

[0033] This embodiment adjusts the reference voltage input to the modulation circuit 2 and the current reference signal so that the control signal output by the modulation circuit 2 adjusts the rectifier circuit 1. When the load is in a dynamic switching state, the input current can be smoothly controlled to ensure that the AC power supply and the load can operate normally and stably without affecting the load and the AC power supply, thereby improving the power factor of the system, reducing harmonic pollution, and improving the voltage regulation characteristics and stability of the control system.

[0034] Next, we will combine Figure 1-Figure 3 The PFC loop control system described in this embodiment is described in detail: As an optional implementation, Figure 3As shown, the modulation circuit 2 includes a voltage loop module 21, a current loop module 22 and a modulation module 23; the first input end of the voltage loop module 21 is connected to the output end of the rectifier circuit 1, for receiving the actual output voltage of the rectifier circuit 1; the second input end of the voltage loop module 21 is connected to the host computer, for receiving the reference voltage output by the host computer; the output end of the voltage loop module 21 is connected to the input end of the current loop module 22, for outputting a current reference signal to the current loop module 22; the first input end of the current loop module 22 is connected to the output end of the voltage loop module 21, for receiving the current reference signal, and the second input end is used to receive the current output current; the output end of the current loop module 22 is connected to the input end of the modulation module 23, for outputting a control signal; the output end of the modulation module 23 is connected to the rectifier circuit 1.

[0035] The first input terminal of the voltage loop module 21 is connected to the output terminal of the rectifier circuit 1 to receive the actual output voltage of the rectifier circuit 1. Since the rectifier circuit 1 converts AC power into DC power, its actual output voltage is affected by factors such as input voltage fluctuations and load changes. The voltage loop module 21 uses the actual output voltage obtained from the input terminal as a feedback signal.

[0036] The second input terminal of the voltage loop module 21 is connected to the host computer, and is used to receive the reference voltage sent by the host computer and use the reference voltage as the target value.

[0037] The output terminal of the voltage loop module 21 is connected to the input terminal of the voltage loop module 22. The voltage loop module 21 compares the actual output voltage received at the input terminal with the reference voltage, calculates a current reference signal using a certain control algorithm (such as a PID control algorithm), and outputs the current reference signal to the current loop module 22. The current reference signal is the current required to make the actual output voltage of the rectifier circuit 1 reach the reference voltage.

[0038] The current loop module 22 is a P-type current controller. The first input of the current loop module 22 is connected to the output of the voltage loop module 21 and is used to receive the current reference signal output by the voltage loop. The second input of the current loop module 22 is used to receive the current output current. The current output current is the actual output current output by the rectifier circuit 1 and can be measured by a device such as a current sensor. The output of the current loop module 22 is connected to the input of the modulation module 23. The current loop module 22 compares the received current reference signal with the current output current, calculates a control signal through mobile control (such as a PID control algorithm), and outputs a control signal to the modulation module 23.

[0039] The input end of the modulation module 23 is connected to the output end of the current loop module 22, and is used to receive the control signal output by the current loop module 22. The output end of the modulation module 23 is connected to the rectifier circuit 1. The modulation circuit 2 adjusts the duty cycle of the PWM signal input to the rectifier circuit 1 based on the control signal it receives, changing the on-time of the switch in the rectifier circuit 1, thereby adjusting the output current and voltage of the rectifier circuit 1.

[0040] The modulation circuit 2 is controlled by a dual closed-loop of a voltage loop and a current loop. This embodiment adjusts the reference voltage input to the voltage loop module 21 and the current reference signal input from the voltage loop module 21 to the current loop module 22, and combines this with the current loop to achieve precise control of the output voltage of the rectifier circuit 1, thereby improving the power factor of the system, reducing harmonic pollution, and improving the stability and reliability of the system.

[0041] As an optional embodiment, the voltage loop module 21 includes a PI-type voltage controller, the first input of which is connected to the output of the rectifier circuit 1, and the second input of which is connected to the host computer. The output of the PI-type voltage controller is used to output a control voltage signal. Specifically, the PI-type voltage controller can calculate the output control voltage signal by comparing the deviation between the actual output voltage of the rectifier circuit 1 and the reference voltage output by the host computer using a proportional link and an integral link. The proportional link outputs the control variable in proportion to the size of the deviation and can quickly respond to the deviation. The integral link integrates the deviation and is mainly used to eliminate the steady-state error of the system, so that the actual output voltage can accurately track the reference voltage.

[0042] As an optional embodiment, the current reference signal received by the current loop module 22 is used to As shown in formula (1): (1) Among them, V EA is the control voltage signal output by the PI type voltage controller, V k is the instantaneous value of the input voltage, and k is the phase A, phase B, and phase C of the AC power supply.

[0043] It can be seen that the voltage output by the PI type voltage controller in this embodiment is V EA However, the current reference signal input from the voltage loop module 21 to the current loop module 22 also has two other parameters involved. They are the instantaneous value of the input voltage V k and the effective value of the input voltage .

[0044] Among them, the instantaneous value of the input voltage V kIt refers to the actual magnitude of the voltage at a specific instant, which will change over time. In this embodiment, the instantaneous value of the input voltage can be obtained through an oscilloscope or a data acquisition card.

[0045] Input voltage RMS A physical quantity that measures the magnitude of alternating current from the perspective of thermal effects. For a periodically varying AC voltage, its effective value is the value of the DC voltage when the AC voltage and the DC voltage generate the same amount of heat across the same resistance within one cycle. In this case, it is the effective value of the input voltage.

[0046] In this embodiment, the current reference signal output by the voltage loop module 21 to the current loop module 22 provides a current reference value for the current loop module 22. The current loop module 22 compares this current reference value with the actual output current to determine whether the actual output current is within a normal range, outputs a control signal, and uses the modulation module 23 to adjust the duty cycle of the PWM signal input to the rectifier circuit 1 according to the control signal, thereby achieving precise control and regulation of the rectifier circuit 1, thereby stabilizing the voltage output by the rectifier circuit 1.

[0047] As an optional implementation, the control voltage signal output by the PI type voltage controller is expressed as follows: (2) According to formula (2) and the current reference signal , input voltage instantaneous value V k and the effective value of the input voltage The definition of is: (3) Where A is current, V is voltage, and W is power.

[0048] From the above formulas (2) and (3), we can see that V EA The power information is included in the current reference signal. Therefore, by controlling V EA The increment is used to control the size of the input current mutation, and the current output is adjusted by changing the voltage input power.

[0049] As an optional implementation, the difference between the reference voltage calculated by the host computer and the actual output voltage output by the rectifier circuit 1 is It is expressed by the following formula: (4) in, is the reference voltage, is the actual output voltage; The control voltage signal V output by the PI type voltage controller EA The difference between the reference voltage calculated by the host computer and the actual output voltage output by the rectifier circuit 1 Adjust according to the difference Adjust the control voltage signal V output by the PI type voltage controller EA The formula is as follows: (5) in, is the proportionality coefficient, is the integration coefficient.

[0050] In the PFC voltage loop, due to V ref is constant, so the actual output voltage V is detected O With reference voltage V ref When the phase difference is too large, in order to ensure the stability of the output voltage of the rectifier circuit 1, the voltage loop module 21 will quickly increase the control voltage signal V through the PI type voltage controller. EA , thereby quickly adjusting the current reference signal , for rapid energy replenishment.

[0051] As an optional implementation, Figure 3 As shown, the rectifier circuit 1 includes a filter module 11 and a rectifier module 12; the input end of the filter module 11 is connected to the AC power supply, and the output end is connected to the rectifier module 12; the input end of the rectifier module 12 is respectively connected to the filter module 11 and the modulation module 23, and the output end is connected to the modulation circuit 2 and the load.

[0052] Specifically, the input end of the filter module 11 is connected to the AC power supply and is used to receive AC power from the AC power supply, filter it, and then transmit the processed AC power from the output end to the rectifier module 12. AC power usually contains some clutter and interference signals. The filter module 11 can remove these unnecessary components, making the AC power input to the rectifier module 12 purer, which helps to improve the rectification effect and the stability of subsequent circuits. It should be noted that the filter unit includes an EMI filter and an inductor, and the EMI filter is connected to the rectifier module 12 via the inductor. In the filter module 11, a low-pass filter is also used for filtering and sampling.

[0053] The input end of the rectifier module 12 is also used to receive a signal from the modulation module 23, and can adjust the output parameters of the DC power according to the duty cycle of the PWM signal input to the rectifier circuit 1 for use by the load.

[0054] As an optional embodiment, the rectifier module 12 is a three-phase full-bridge rectifier module 12. Among them, the switching device in the three-phase full-bridge rectifier module 12 is a MOSFET connected in parallel with a diode. In the rectifier circuit 1, when the MOSFET is turned off, the inductor generates a reverse electromotive force. The current in the inductor can form a loop through the diode, releasing energy, ensuring that the MOSFET is not damaged. In this embodiment, it also plays a role in freewheeling protection. At the same time, it can also limit the voltage across the MOSFET to prevent it from being damaged by overvoltage. When the voltage across the MOSFET exceeds the conduction voltage of the diode, the diode turns on, clamping the voltage within a certain range.

[0055] The embodiment is only a special example and does not represent only one way of implementing the present invention.

[0056] Example 2: A PFC loop control method, such as Figure 4 Shown, including: S10, the host computer detects the current actual output voltage and the previous actual output voltage of the rectifier circuit, and calculates the voltage difference between the current actual output voltage and the previous actual output voltage; S20, when the voltage difference is greater than the set threshold, the host computer sets the current actual output voltage as the reference voltage output to the modulation circuit; S30 , causing the modulation circuit to perform a slow start according to a predetermined step length, changing the output of the modulation circuit, and adjusting the duty cycle of the PWM signal input to the rectifier circuit.

[0057] The upper computer in this embodiment can adjust the reference voltage input to the modulation circuit by the voltage difference, and adjust the current reference signal so that the control signal output by the modulation circuit adjusts the rectifier circuit. When the load is in a dynamic switching state, the input current can be smoothly controlled to ensure that the AC power supply and the load can operate normally and stably without affecting the load and the AC power supply, thereby improving the voltage regulation characteristics and stability of the control system.

[0058] Below, according to Figure 3 The PFC loop control method described in this embodiment is described in detail.

[0059] First, step S10 is executed, where the host computer detects the current actual output voltage of the rectifier circuit and the previous actual output voltage, and calculates the voltage difference between the current actual output voltage and the previous actual output voltage. It should be noted that the host computer periodically detects the current actual output voltage to ensure timely and accurate monitoring of the output voltage of the rectifier circuit. The frequency of the periodic detection can be set according to actual needs.

[0060] Specifically, the host computer can monitor the voltage of the rectifier circuit in real time and obtain the current actual output voltage of the rectifier circuit. After obtaining the current actual output voltage, the host computer calculates the difference between the current actual output voltage and the previous actual output voltage to obtain a voltage difference. This voltage difference reflects the change in the output voltage of the rectifier circuit. The host computer analyzes the voltage difference and can quickly determine whether the load state has changed. If the voltage difference is within the set threshold range, it indicates that the load is stable and the system continues to maintain the current operating state. If the voltage difference is greater than the set threshold, step S20 is executed.

[0061] When the voltage difference is greater than a set threshold, step S20 is executed. When the voltage difference is greater than the set threshold, the host computer sets the current actual output voltage as the reference voltage output to the modulation circuit. Specifically, when the voltage difference is greater than the set threshold, it indicates that the output voltage of the rectifier circuit is significantly fluctuating. In this case, to ensure the normal operation of the load and AC power supply, the modulation circuit adjusts the reference voltage based on the current actual output voltage, modulating the input AC power to adjust the output voltage of the rectifier circuit to maintain stability.

[0062] More specifically, the host computer, through precise calculation and judgment, adjusts the actual output voltage to a reference voltage, which is then fed to the modulation circuit for subsequent processing. The modulation circuit, based on this reference voltage, dynamically adjusts the operating state of the rectifier circuit to ensure that the output voltage remains within a preset range, thereby achieving output voltage stability. During this process, the host computer also continuously monitors the output voltage of the rectifier circuit to make further adjustments if necessary.

[0063] Finally, step S30 is executed, causing the modulation circuit to perform a slow start according to a predetermined step size, changing the modulation circuit's output and adjusting the duty cycle of the PWM signal input to the rectifier circuit. Specifically, after setting the current actual output voltage to the reference voltage, the modulation circuit performs a slow start operation according to a predetermined step size. Slow start prevents sudden changes in circuit parameters such as voltage and current, protecting circuit components. During the slow start process, the modulation circuit changes its output, thereby adjusting the duty cycle of the PWM (pulse width modulation) signal input to the rectifier circuit. By adjusting the duty cycle of the PWM signal, the input of the rectifier circuit is changed, thereby regulating the output voltage of the rectifier circuit, making the output voltage more stable and preventing sudden voltage changes that could impact the load and AC power supply.

[0064] Through precise control and adjustment of the above steps, this embodiment enables the entire PFC loop control system to effectively improve the power factor, reduce harmonic pollution, and ensure the stability and reliability of the output voltage.

[0065] As an optional implementation, set the step size S t It is expressed by the following formula: Among them, E rrv is the voltage difference between the current actual output voltage and the previous actual output voltage, T rec It is the minimum voltage recovery time.

[0066] In this embodiment, E rrv It reflects the difference between the current actual output voltage and the previous output voltage. The larger the difference, the greater the fluctuation of the output voltage, and the greater the adjustment force is needed to quickly stabilize the output voltage. rec It is the time required for the voltage to recover from the lowest point to a stable state. The shorter this time is, the faster the system responds and the faster it can adapt to load changes and grid fluctuations.

[0067] More specifically, the step size S is set t The formula comprehensively considers both the voltage difference Errv and the minimum voltage recovery time Trec. By properly setting St, system response speed can be guaranteed while avoiding the impact of excessive regulation. In practical applications, the parameters in the formula can be adjusted appropriately based on the specific system conditions and load characteristics to achieve optimal regulation. By accurately calculating and setting the step size St, the modulation circuit can start slowly according to the predetermined step size, gradually adjusting the duty cycle of the PWM signal, thereby achieving fine regulation of the rectifier circuit's output voltage. This regulation method not only improves the system's power factor and reduces harmonic pollution, but also ensures the stability and reliability of the output voltage, providing high-quality power to the load.

[0068] The foregoing is merely a preferred embodiment of the present invention. Those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the guidance of the present invention, these features and embodiments may be modified to suit specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be within the scope of the present invention.

Claims

1. A PFC loop control system, characterized in that: include: Rectification circuit, modulation circuit and host computer; The input end of the rectifier circuit is connected to an AC power supply, and the output end of the rectifier circuit is connected to a load and the modulation circuit respectively; The input end of the modulation circuit is connected to the rectifier circuit and the host computer respectively, and is used to receive the actual output voltage output by the rectifier circuit and the reference voltage output by the host computer; The output end of the modulation circuit is connected to the rectification circuit; The modulation circuit generates a current reference signal according to the actual output voltage and the reference voltage, and generates a control signal according to the current reference signal, and adjusts the duty cycle of the PWM signal input to the rectifier circuit through the control signal; The host computer is connected to the rectifier circuit and the modulation circuit respectively, and is used to detect the actual output voltage of the rectifier circuit and the previous actual output voltage, and obtain a voltage difference based on the actual output voltage and the previous actual output voltage; when the voltage difference exceeds a set threshold, the host computer adjusts the reference voltage according to the voltage difference, so that the modulation circuit adjusts the current reference signal to change the duty cycle of the PWM signal input to the rectifier circuit, thereby controlling the output power of the rectifier circuit.

2. The PFC loop control system according to claim 1, characterized in that: The modulation circuit includes a voltage loop module, a current loop module and a modulation module; The first input end of the voltage loop module is connected to the output end of the rectifier circuit, and is used to receive the actual output voltage of the rectifier circuit; the second input end of the voltage loop module is connected to the host computer, and is used to receive the reference voltage output by the host computer; the output end of the voltage loop module is connected to the input end of the current loop module, and is used to output the current reference signal to the current loop module; The first input end of the current loop module is connected to the output end of the voltage loop module for receiving the current reference signal, and the second input end is used to receive the current output current; The output end of the current loop module is connected to the input end of the modulation module for outputting a control signal; The output end of the modulation module is connected to the rectifier circuit.

3. The PFC loop control system according to claim 2, characterized in that: The voltage loop module includes a PI type voltage controller, a first input end of the PI type voltage controller is connected to the output end of the rectifier circuit, and a second input end is connected to the host computer; the output end of the PI type voltage controller is used to output a control voltage signal.

4. The PFC loop control system according to claim 3, characterized in that: The current reference signal received by the current loop module As shown in formula (1): （1） Among them, V EA is the control voltage signal output by the PI type voltage controller, V k is the instantaneous value of the input voltage, is the effective value of the input voltage, and k is the phase A, phase B and phase C of the AC power supply.

5. The PFC loop control system according to claim 4, characterized in that: The control voltage signal output by the PI type voltage controller is expressed as formula (2): （2） According to formula (2) and the current reference signal , input voltage instantaneous value V k and the effective value of the input voltage The definition of is given by formula (3): （3） Where A is current, V is voltage, and W is power.

6. The PFC loop control system according to claim 3, characterized in that: The difference between the reference voltage calculated by the host computer and the actual output voltage output by the rectifier circuit As shown in formula (4): （4） in, is the reference voltage, is the actual output voltage; The control voltage signal V output by the PI type voltage controller EA The difference between the reference voltage calculated by the host computer and the actual output voltage output by the rectifier circuit Adjustments are made based on the difference Adjust the control voltage signal V output by the PI type voltage controller EA As shown in formula (5): （5） in, is the proportionality coefficient, is the integration coefficient.

7. The PFC loop control system according to claim 2, characterized in that: The rectifier circuit includes a filter module and a rectifier module; the input end of the filter module is connected to the AC power supply, and the output end is connected to the rectifier module; the input end of the rectifier module is respectively connected to the filter module and the modulation module, and the output end is connected to the modulation circuit and the load.

8. The PFC loop control system according to claim 7, characterized in that: The rectifier module is a three-phase full-bridge rectifier module.

9. A PFC loop control method, characterized in that: include: The host computer detects the current actual output voltage and the previous actual output voltage of the rectifier circuit, and calculates the voltage difference between the current actual output voltage and the previous actual output voltage; When the voltage difference is greater than a set threshold, the host computer sets the current actual output voltage as a reference voltage output to the modulation circuit; The modulation circuit is slowly started according to a predetermined step length, the output of the modulation circuit is changed, and the duty cycle of the PWM signal input to the rectifier circuit is adjusted.

10. The PFC loop control method according to claim 9, wherein: The setting step size S t It is expressed by the following formula: Among them, E rrv is the voltage difference between the current actual output voltage and the previous actual output voltage, T rec It is the minimum voltage recovery time.

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