A current feedforward control method, device and switching power supply

Abstract

This invention relates to a current feedforward control method, device, and switching power supply. The control method includes: acquiring a first voltage signal characterizing the DC bus voltage, a second voltage signal representing the input voltage, a first current signal representing the input current, and a second current signal representing the load current; calculating a current inner loop reference quantity from the voltage outer loop; calculating the current feedforward quantity according to the power balance formula, and combining the fixed coefficient and efficiency in the current feedforward quantity expression into a constant; and setting the current inner loop reference quantity I... Udc and current feedforward quantity I f The superimposed values ​​serve as the reference for the inner current loop, which then adjusts the drive signal of the PFC circuit. It is then determined whether the PFC circuit satisfies |I| under full load. Udc -I f | <Set threshold: If yes, no constant adjustment is needed, control ends; otherwise, if I Udc >I f Then increase the constant and return to the drive signal adjustment step. If I Udc <I f The constant is then reduced and the process returns to the drive signal adjustment step. This invention can reduce the amplitude and duration of DC bus voltage fluctuations when the load changes.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to a current feedforward control method and device and switching power supply. BACKGROUND

[0002] With the rapid development of power electronics industry, PFC circuit has been more and more widely used. The market requirements for performance indicators such as power level and commutation switching time are continuously improved, which indirectly puts forward higher and higher requirements for the dynamic response capability of the load change on the DC side. The traditional double closed-loop control of voltage outer loop and current inner loop cannot meet this requirement well, so some people have proposed to introduce a load current feedforward control strategy based on the traditional double closed-loop control. Based on the power balance principle, the energy required in the load switching process is converted into a current feedforward amount I f , which is superimposed with the current inner loop reference amount I Udc output by the voltage outer loop PI controller to obtain the given value of the current inner loop PI controller, so as to quickly make up for the lack of input and output power and achieve the effect of quickly stabilizing the DC bus voltage U dc .

[0003] The present application has found that the existing calculation method of the current feedforward amount I f is mostly the standard power balance calculation formula. However, this method has the problem of poor dynamic response effect of current feedforward control, which is due to the fact that the efficiency η in this method is different with the input voltage and output load, and the fluctuation of the sampling value and the calculation error of the single-chip microcomputer will also affect the power compensation effect. In the steady-state operation process of the actual circuit, if there is a large gap between the actual required output power and the theoretically calculated output power, the proportion of the voltage inner loop participating in the adjustment in the current feedforward control process will be large. At this time, if the load is dynamically switched, the voltage inner loop cannot be well adjusted, which affects the dynamic response characteristics of the DC bus voltage.

[0004] It should be noted that the information disclosed in the background section is only intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. In particular, the discovery of the above-mentioned prior art problems should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. Without explicit evidence showing that the above-mentioned information has been disclosed before the filing date of the present patent application, the above-mentioned background should not be used to evaluate the novelty and inventiveness of the present application. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to provide a current feedforward control method, device and switching power supply, which ensures that the current feedforward algorithm has better dynamic response characteristics in actual engineering.

[0006] As a first aspect of the present invention, the technical solution of the provided current feedforward control method is as follows:

[0007] A current feedforward control method is applied to a PFC circuit, wherein the current feedforward control method includes the following steps:

[0008] The electrical parameter acquisition step involves acquiring a first voltage signal U, which characterizes the magnitude of the DC bus voltage of the PFC circuit. dc A second voltage signal U characterizing the magnitude of the input voltage of the PFC circuit. in The first current signal I, representing the magnitude of the input current of the PFC circuit. in And a second current signal I that characterizes the magnitude of the load current of the PFC circuit. R ;

[0009] The calculation steps for the current inner loop reference quantity are as follows: the first voltage signal U is calculated from the voltage outer loop. dc The inner current reference value I is calculated by comparing it with the set reference value. udc ;

[0010] The current feedforward calculation steps are based on the first voltage signal U. dc The second voltage signal U in The second current signal I R Calculate the efficiency η of the PFC circuit and the current feedforward I. f The calculation is based on the power balance formula P in =P O ×η, where: P in For the input power of the PFC circuit, P O To determine the output power of the PFC circuit, the current feedforward quantity I is used in this step. f The fixed coefficients in the expression and the efficiency η are combined into a constant k, and the initial value of the constant k is given according to the estimated value of η;

[0011] The drive signal adjustment step involves adjusting the inner current loop reference value I. udc and the current feedforward quantity I f The superimposed current is used as the reference for the inner current loop. The drive signal of the PFC circuit is adjusted through the inner current loop so that the DC bus voltage output by the PFC circuit reaches the desired value.

[0012] The constant k adjustment step determines whether the PFC circuit satisfies |I| under full load. Udc -I f | <Set threshold: If yes, no adjustment of the constant k is needed, and control ends; otherwise, if I Udc >If Then increase the constant k and return to the drive signal adjustment step. If I Udc <I f Then decrease the constant k and return to the drive signal adjustment step.

[0013] Preferably, in the constant k adjustment step, the set threshold is 1.

[0014] Preferably, in the constant k adjustment step, if I Udc >I f Increase the constant K by 0.1 times.

[0015] Preferably, in the constant k adjustment step, if I Udc <I f The constant K is reduced by a factor of 0.1.

[0016] Furthermore, when the PFC circuit is a three-phase PFC circuit, the second voltage signal U in and the first current signal I in It is obtained after DQ transformation.

[0017] Furthermore, when the PFC circuit is a three-phase PFC circuit, the current feedforward amount I... f The expression is as follows:

[0018]

[0019] Preferably, in the drive signal adjustment step, the duty cycle and / or frequency of the drive signal are adjusted so that the DC bus voltage output by the PFC circuit reaches the desired value.

[0020] Furthermore, in the current inner loop reference quantity calculation step, the first PI controller calculates the current inner loop reference quantity I. udc ; and / or in the drive signal conditioning step, the second PI controller adjusts the current inner loop reference value I. udc and the current feedforward quantity I f Perform overlay processing.

[0021] As a second aspect of the present invention, the technical solution of the provided current feedforward control device is as follows:

[0022] A current feedforward control device is applied to a PFC circuit, wherein the current feedforward control device includes the following units:

[0023] The electrical parameter acquisition unit is used to acquire a first voltage signal U that characterizes the magnitude of the DC bus voltage of the PFC circuit. dc A second voltage signal U characterizing the magnitude of the input voltage of the PFC circuit.in a first current signal I in representing the magnitude of the input current of the PFC circuit R ;

[0024] a current inner loop reference quantity calculation unit for calculating a current inner loop reference quantity I dc by comparing the first voltage signal U udc with a set reference value ;

[0025] a current feedforward quantity calculation unit for calculating a current feedforward quantity I dc based on the first voltage signal U in , the second voltage signal U R , the second current signal I f , and the efficiency η of the PFC circuit, the calculation being based on the power balance formula P in = P O × η, where P in is the input power of the PFC circuit and P O is the output power of the PFC circuit, and the fixed coefficient in the expression of the current feedforward quantity I f is combined with the efficiency η into a constant k, and the initial value of the constant k is given according to the estimated value of η;

[0026] a drive signal adjustment unit for superimposing the current inner loop reference quantity I udc and the current feedforward quantity I f to give a reference for the current inner loop, and adjusting the drive signal of the PFC circuit through the current inner loop so that the DC bus voltage output by the PFC circuit reaches the desired value ;

[0027] a constant k adjustment unit for judging whether the condition |I Udc -I f | < set threshold value is met when the PFC circuit is in full load state, and if yes, the size of the constant k does not need to be adjusted, and the control ends; otherwise, if I Udc >I f , the constant k is increased and the drive signal adjustment step is returned to, and if I Udc <I f , the constant k is decreased and the drive signal adjustment step is returned to.

[0028] As a third aspect of the present application, the embodiment of the switching power supply provided is as follows:

[0029] A switching power supply, comprising a PFC circuit controlled by the current feedforward control device according to any one of the second aspect.

[0030] The advantages of this invention over existing technologies are as follows: By adding an adjustable coefficient k to the current feedforward control algorithm, the dynamic response of the DC bus voltage in the PFC circuit is significantly improved compared to the unadjusted scheme. Furthermore, the actual inner-loop reference value I is also adjusted when the PFC circuit is under full load. udc and the calculated current feedforward quantity I f The absolute value of the difference is used as a threshold to determine how to change k, so that k can be quickly adjusted to a suitable value. This embodiment of the invention can optimize the effect of current feedforward control and further reduce the fluctuation amplitude and adjustment time of PFC DC bus voltage during load disturbance. Attached Figure Description

[0031] Figure 1 This is a flowchart of the current feedforward control method proposed in the first embodiment of the present invention;

[0032] Figure 2 This is a flowchart of the current feedforward control device proposed in the second embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of a specific circuit topology and control strategy of the switching power supply in the third embodiment of this invention;

[0034] Figure 4 for Figure 3 When the current feedforward control parameters of the switching power supply are inappropriate, the current feedforward does not participate in the calculation. Udc with I f Waveform;

[0035] Figure 5 for Figure 3 When the current feedforward control parameters of the switching power supply are inappropriate, the current feedforward participates in the calculation. Udc with I f Waveform;

[0036] Figure 6 for Figure 3 When the current feedforward control parameters of the switching power supply are inappropriate, the bus voltage waveform is involved in the calculation when the current feedforward participates in the calculation.

[0037] Figure 7 for Figure 3 When the current feedforward control parameters of the switching power supply are appropriate, the current feedforward does not participate in the calculation. Udc with I f Waveform;

[0038] Figure 8 for Figure 3 When the current feedforward control parameters of the switching power supply are appropriate, the current feedforward participates in the calculation. Udc with I f Waveform;

[0039] Figure 9 For Figure 3 When the switch power supply current feedforward control parameter is appropriate, the bus voltage waveform is participated in operation when the current feedforward participates in operation. DETAILED DESCRIPTION

[0040] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0041] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0042] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so as to describe the embodiments of the present application. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0043] It should be understood that, in the specification, claims and drawings, when describing a step succeeding to another step, the step can directly succeed to the other step, or succeed to the other step through a third step; when describing an element / unit "succeeding" to another element / unit, the element / unit can be "directly connected" to the other element / unit, or "connected" to the other element / unit through a third element / unit.

[0044] The present application designs a current feedforward control strategy and parameter setting method, improves the current feedforward link by using a mathematical equivalent model, and proposes a corresponding control parameter design method to ensure the best dynamic response of the bus.

[0045] First embodiment

[0046] The present embodiment provides a current feedforward control method applied to a PFC circuit, Figure 2 The flow chart of the current feedforward control device proposed in the second embodiment of the present application, wherein the current feedforward control method comprises the following steps:

[0047] In the electrical parameter acquisition step S101, the first voltage signal U, which characterizes the magnitude of the DC bus voltage of the PFC circuit, is acquired. dc The second voltage signal U, representing the magnitude of the input voltage of the PFC circuit. in The first current signal I, representing the magnitude of the input current of the PFC circuit. in And the second current signal I characterizing the load current of the PFC circuit. R ;

[0048] In the current inner loop reference quantity calculation step S102, the first voltage signal U is calculated from the voltage outer loop. dc The inner current reference value I is calculated by comparing it with the set reference value. udc ;

[0049] Current feedforward calculation step S103, based on the first voltage signal U dc Second voltage signal U in Second current signal I R Calculate the efficiency η of the PFC circuit and the current feedforward I. f The calculation is based on the power balance formula P in =P O ×η, where: P in For the input power of the PFC circuit, P O To determine the output power of the PFC circuit, the current feedforward quantity I is used in this step. f The fixed coefficient and efficiency η in the expression are combined into a constant k, and the initial value of constant k is given according to the estimated value of η;

[0050] In the drive signal adjustment step S104, the reference quantity I of the current inner loop is adjusted by the current inner loop. udc and current feedforward quantity I f The superimposed current is used as the reference for the inner current loop. The drive signal of the PFC circuit is adjusted through the inner current loop, so that the DC bus voltage output by the PFC circuit reaches the desired value.

[0051] In constant k adjustment step S105, it is determined whether the PFC circuit satisfies |I_k| under full load. Udc -I f | <Set threshold: If yes, no need to adjust the constant k, control ends; otherwise, if I Udc >I f Then increase the constant k and return to the drive signal adjustment step. If I Udc <I f Then decrease the constant k and return to the drive signal adjustment step.

[0052] In the constant k adjustment step S105: when |I Udc -If |<set threshold, this indicates that the calculated current feedforward amount I f is close to the actual current inner loop reference amount I Udc , the output power required by the PFC and the actual output power are basically equal, meeting the requirements, and there is no need to adjust the size of the constant k, and the control ends; when |I Udc -I f |>set threshold, this indicates that the calculated current feedforward amount I f is far from the actual current inner loop reference amount I Udc , the output power required by the PFC and the actual output power have a large gap, which does not meet the requirements, so the constant k needs to be adjusted.

[0053] The control method of the embodiment increases the adjustable coefficient k in the current feedforward control algorithm. Compared with the scheme without adjustment, the dynamic response process of the DC bus voltage of the PFC circuit is obviously improved. In addition, the absolute value of the difference between the actual current inner loop reference amount I udc and the calculated current feedforward amount I f is used as a threshold to determine the way to change k, so that k can be quickly adjusted to an appropriate value, achieving the effect of optimizing current feedforward control and further reducing the fluctuation amplitude and adjustment time of the PFC DC bus voltage during load disturbance.

[0054] As a specific embodiment, in the constant k adjustment step, the threshold is set to 1.

[0055] As a specific embodiment, in the constant k adjustment step, if I Udc >I f , the constant k is increased by 0.1 times, and then the current feedforward amount calculation step S103 is returned to.

[0056] As a specific embodiment, in the constant k adjustment step, if I Udc <I f , the constant k is decreased by 0.1 times, and then the current feedforward amount calculation step S103 is returned to.

[0057] The PFC circuit to which the current feedforward control method of the embodiment is applied can be a single-phase PFC circuit or a three-phase PFC circuit. As a specific embodiment, when the PFC circuit is a three-phase PFC circuit, the second voltage signal U in and the first current signal I in are obtained after DQ transformation.

[0058] When the PFC circuit is a three-phase PFC circuit, the process of calculating the current feedforward amount according to the power balance formula without considering the efficiency η is as follows:

[0059]

[0060] P out =U dc ×I R

[0061]

[0062] The current feedforward I in the power balance formula after considering efficiency η f The expression is as follows:

[0063]

[0064] After replacing the efficiency η and the fixed coefficient 3 / 2 with a constant k, the current feedforward quantity I f The expression is as follows:

[0065]

[0066] In one specific implementation, during the drive signal adjustment step, the duty cycle and / or frequency of the drive signal are adjusted so that the DC bus voltage output by the PFC circuit reaches the desired value.

[0067] As a specific implementation method, in the current inner loop reference quantity calculation step, the first PI controller calculates the current inner loop reference quantity I. udc ; and / or in the drive signal conditioning step, the second PI controller adjusts the current inner loop reference value I. udc and current feedforward quantity I f Perform overlay processing.

[0068] Second Embodiment

[0069] This embodiment provides a current feedforward control device applied to a PFC circuit. Figure 2 The flowchart below shows the current feedforward control device proposed in the second embodiment of the present invention, wherein the current feedforward control device includes the following units:

[0070] The electrical parameter acquisition unit 100 is used to acquire a first voltage signal U that characterizes the magnitude of the DC bus voltage. dc The second voltage signal U, representing the magnitude of the input voltage of the PFC circuit. in The first current signal I, representing the magnitude of the input current of the PFC circuit. in And the second current signal I characterizing the load current of the PFC circuit. R ;

[0071] The inner current loop reference calculation unit 200 is used to calculate the first voltage signal U from the outer voltage loop. dc The inner current reference value I is calculated by comparing it with the set reference value.udc ;

[0072] The current feedforward amount calculation unit 300 is configured to calculate a current feedforward amount I dc based on a first voltage signal U in , a second voltage signal U R , a second current signal I f , and an efficiency η of the PFC circuit, and the calculation basis is a power balance formula P in = P O × η, wherein P in is an input power of the PFC circuit, and P O is an output power of the PFC circuit. In this step, a fixed coefficient in the expression of the current feedforward amount I f is combined with the efficiency η into a constant k, and the initial value of the constant k is given according to the estimated value of η.

[0073] The drive signal adjustment unit 400 is configured to superimpose the current inner loop reference amount I udc and the current feedforward amount I f after the current inner loop to give a reference of the current inner loop, and adjust the drive signal of the PFC circuit through the current inner loop, so that the DC bus voltage output by the PFC circuit reaches the expected value.

[0074] The constant k adjustment unit 500 is configured to judge whether the PFC circuit is in a full load state and whether |I Udc -I f | < a set threshold value, if yes, there is no need to adjust the size of the constant k, and the control ends; otherwise, if I Udc >I f , the constant k is increased and the drive signal adjustment step is returned, and if I Udc <I f , the constant k is decreased and the drive signal adjustment step is returned.

[0075] The technical means adopted by the control device of the embodiment corresponds to the control method of the first embodiment, has the same beneficial effects, and thus is not described in detail. In addition, the preferred technical means of each step in the control method of the first embodiment or the further improved means can be extended to the corresponding unit of the embodiment, and the embodiment is not described one by one.

[0076] Third embodiment

[0077] The switching power supply provided by the embodiment comprises a PFC circuit, and the PFC circuit is controlled by any one of the current feedforward control devices in the second embodiment.

[0078] The switching power supply of the embodiment can ensure that the current feedforward algorithm has a better dynamic response characteristic because the PFC circuit is controlled by any one of the current feedforward control devices in the second embodiment.

[0079] Figure 3 This is a schematic diagram of a specific circuit topology and control strategy for a switching power supply according to the third embodiment of this invention. The specific implementation steps of current feedforward control are as follows:

[0080] S1: Collect data as follows Figure 3 The grid voltage U shown a U b U c The rectifier-side power inductor current or the grid-side input current i a i b i c . Will U a U b U c and i a i b i c Perform dq transformations to obtain U in_d U in_q and I in_d I in_q Since this invention mainly improves the control of the active power component, it only discusses the control strategy for the d-axis component and does not elaborate on the control strategy for the q-axis component. Therefore, U is used. in U in_d , use I in Indicate I in_q ;

[0081] S2: Based on DC bus voltage U dc Calculate the first PI output value I Udc Based on DC bus voltage U dc Load current I R and AC side input voltage U in Through the conventional power balance formula P in =P0 calculates the current feedforward quantity I f The specific implementation details are as follows:

[0082] Set the DC bus voltage rating with U dc After subtraction, the result is fed into the first PI and then output as I. Udc ;

[0083] The current feedforward is calculated based on the power balance formula. The calculation process has been detailed in the first embodiment. The current feedforward I... f The expression is as follows:

[0084]

[0085] S4: Based on the first PI output value I Udc and inductor current Iin The second PI output value is calculated to control the duty cycle, thereby achieving DC bus voltage regulation control. The specific implementation details are as follows:

[0086] First PI output value I Udc As the inductor current I in Reference value The current feedforward calculated at this time does not participate in the closed-loop control of the loop. The processing after the second PI output is a conventional control method, which will not be elaborated here.

[0087] S5: Determine |I| under full-load steady state Udc -I f | < Check if the set threshold is met. If yes, determine the control parameter k and the step ends; otherwise, if I Udc >I f Then increase k, if I Udc <I f Then decrease k, and return to the previous step in either case.

[0088] To demonstrate the significant effects of the present invention, this embodiment is based on Figure 3 A schematic diagram of a specific switching power supply is provided, along with some experimental results. Firstly, under insufficient feedforward conditions, at a 220Vrms three-phase input full-load steady-state condition, as shown... Figure 4 and Figure 5 As shown ( Figure 4 The medium current is I Udc Waveform; Figure 5 The medium current peak is I Udc Waveform), current feedforward I f When I only participates in loop calculation but not in loop control f with I Udc The phase difference is nearly 8A, then let the current feedforward I f After participating in closed-loop control, the dynamic response waveform of the bus voltage is obtained, such as... Figure 6 As shown; secondly, the situation after the feedforward control parameter k is adjusted to a good state, under a 220Vrms three-phase input full-load steady state, as follows: Figure 7 and Figure 8 As shown ( Figure 7 The current with the largest value near 0s is I. f Waveform; Figure 8 The medium current peak is I Udc Waveform), current feedforward I f When only participating in loop calculation I f with I Udc The phases are basically equal. Then, after letting the feedforward quantity participate in the closed-loop control, the dynamic response waveform of the bus voltage is obtained as follows: Figure 9 As shown.

[0089] The above experimental results show that, compared with the case that the k value is not appropriate and the current feedforward amount is insufficient, the bus output voltage fluctuation amplitude and the regulation time are much smaller in the case that the k value is appropriate.

[0090] The above embodiments of the present application are only examples for illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes and variations can be made by those skilled in the art. Here, all the embodiments cannot be exhausted. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A current feedforward control method applied to a PFC circuit, characterized in that, The current feedforward control method includes the following steps: an electrical parameter acquisition step of acquiring a first voltage signal U representing a size of a DC bus voltage of the PFC circuit dc , a second voltage signal U representing a size of an input voltage of the PFC circuit in , a first current signal I representing a size of an input current of the PFC circuit in , and a second current signal I representing a size of a load current of the PFC circuit R ; a current inner loop reference quantity calculation step, in which the first voltage signal U dc is compared with a set reference value, and a current inner loop reference quantity I udc is calculated a current feedforward quantity calculation step, based on said first voltage signal U dc , said second voltage signal U in , said second current signal I R , the efficiency η of the PFC circuit f , the calculation being based on the power balance equation P in = P O × η, where P in is the input power of the PFC circuit, P O is the output power of the PFC circuit, and the fixed coefficients in the expression of said current feedforward quantity I f and said efficiency η are combined into a constant k, the initial value of constant k being given according to the η estimate. a drive signal adjusting step of adjusting the drive signal of the PFC circuit according to the current inner loop reference quantity I udc and the current feedforward quantity I f superimposed and given as a reference of the current inner loop, the drive signal of the PFC circuit is adjusted through the current inner loop, so that the DC bus voltage output by the PFC circuit reaches the desired value; The constant k is adjusted in the step of adjusting the constant k, judging whether the PFC circuit is in full load state and whether |I Udc - f | < set threshold value: if yes, there is no need to adjust the size of the constant k, and the control ends; otherwise, if I Udc > I f The constant k is increased and the driving signal adjusting step is returned, if I Udc < I f The constant k is decreased and the driving signal adjusting step is returned.

2. The flow feedforward control method of claim 1, wherein: In the constant k adjustment step, the set threshold value is 1.

3. The flow feedforward control method of claim 1, wherein: In the constant k adjusting step, if I Udc > I f the constant k is increased by 0.1 times.

4. The flow feedforward control method of claim 1, wherein: In the constant k adjusting step, if I Udc <I f the constant k is decreased by 0.1 times.

5. The flow feedforward control method of claim 1, wherein: When the PFC circuit is a three-phase PFC circuit, the second voltage signal U in and the first current signal I in is obtained after DQ transformation.

6. The flow feedforward control method of claim 1, wherein: When the PFC circuit is a three-phase PFC circuit, the current feedforward quantity I f is expressed as follows:

7. The flow feedforward control method of claim 1, wherein: In the drive signal adjustment step, the duty ratio and / or the frequency of the drive signal are adjusted so that the DC bus voltage output by the PFC circuit reaches a desired value.

8. The flow feedforward control method of claim 1, wherein: In the current inner loop reference quantity calculation step, the current inner loop reference quantity I is calculated by a first PI controller udc ; and / or in the drive signal adjustment step, the current inner loop reference quantity I udc and the current feedforward quantity I f are superimposed by a second PI controller.

9. A current feedforward control device applied to a PFC circuit, characterized in that, The current feedforward control device includes the following units: An electric parameter acquisition unit is configured to acquire a first voltage signal U representing a DC bus voltage of the PFC circuit dc , a second voltage signal U representing an input voltage of the PFC circuit in , a first current signal I representing an input current of the PFC circuit in , and a second current signal I representing a load current of the PFC circuit R ; a current inner loop reference quantity calculation unit for calculating a current inner loop reference quantity I by comparing the first voltage signal U dc with a set reference value udc ; The current feedforward calculation unit is used to calculate the current based on the first voltage signal U. dc The second voltage signal U in The second current signal I R Calculate the efficiency η of the PFC circuit and the current feedforward I. f The calculation is based on the power balance formula P in =P O ×η, where: P in For the input power of the PFC circuit, P O To determine the output power of the PFC circuit, the current feedforward quantity I is used in this step. f The fixed coefficients in the expression and the efficiency η are combined into a constant k, and the initial value of the constant k is given according to the estimated value of η; a drive signal adjusting unit for adjusting the drive signal of the PFC circuit by the current inner loop according to the current inner loop reference quantity I udc and the current feedforward quantity I f The drive signal of the PFC circuit is adjusted by the current inner loop according to the current inner loop reference quantity I and the current feedforward quantity I after superposition, so that the DC bus voltage output by the PFC circuit reaches the desired value. a constant k adjusting unit for judging whether |I Udc - f | < set threshold value: if yes, there is no need to adjust the size of the constant k, and the control ends; otherwise, if I Udc > I f , the constant k is increased and the driving signal adjusting step is returned to; if I Udc < I f , the constant k is decreased and the driving signal adjusting step is returned to.

10. A switching power supply characterized by comprising: The PFC circuit is controlled by the current feedforward control device of claim 9. The current feedforward control device includes the following units:

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