Power Factor Correction Circuit Control Method, System and Device

Abstract

The present application discloses a control method, system and device for a power factor correction circuit, relating to the field of electronic power technology. The method includes: determining a target current of any boost conversion unit in the power factor correction circuit based on the actual branch current of any boost conversion unit in the power factor correction circuit, the input voltage and the output voltage of the power factor correction circuit; the actual branch current is the actual input current of the inductor coil in the boost conversion unit; determining the actual decoupling inductance value of any boost conversion unit according to the target current of any boost conversion unit; determining the pulse width modulation duty cycle of any boost conversion unit by using the actual decoupling inductance value of any boost conversion unit; and controlling the conduction and disconnection of the switching tube in any boost conversion unit by using the pulse width modulation duty cycle, so as to optimize the control current loop of the power factor correction circuit and reduce current harmonics.

Description

Technical Field

[0001] This application relates to the field of electronics and power, and particularly to a control method, system and device for a power factor correction circuit. Background Art

[0002] In application fields such as new energy charging systems and variable frequency air conditioning systems, various power factor correction (PFC, Power Factor Corrector) circuits are widely used. Among them, inductors are essential magnetic components in power factor correction circuits. Multiple inductors are used in parallel in power factor correction circuits. Since it is difficult to make the inductor parameters consistent, and the inductance changes non-linearly under the influence of current, frequency, temperature, etc., it is very easy to cause the control current loop of the PFC circuit to jitter, resulting in an increase in the current harmonics of the PFC circuit. Summary of the Invention

[0003] The purpose of this application is to propose a control method, system and device for a power factor correction circuit aiming at the deficiencies of the above-mentioned prior art, and this purpose is achieved through the following technical solutions.

[0004] In the first aspect of this application, a power factor correction circuit control system is proposed. The system includes: a power factor correction circuit, a sampling unit and a controller. The sampling unit is respectively connected to the power factor correction circuit and the controller. The power factor correction circuit includes a plurality of parallel boost conversion units and a magnetic integrated inductor. The magnetic integrated inductor includes winding magnetic columns with the same number as the boost conversion units. Each boost conversion unit corresponds to an inductance coil on one of the winding magnetic columns;

[0005] The sampling unit is used to sample the input voltage, output voltage of the power factor correction circuit, and the actual branch current of any one of the boost conversion units;

[0006] The controller is used to determine the target current of any one of the boost conversion units based on the actual branch current of any one of the boost conversion units in the power factor correction circuit, the input voltage and output voltage of the power factor correction circuit; determine the actual decoupling inductance value of any one of the boost conversion units according to the target current of any one of the boost conversion units; use the actual decoupling inductance value of any one of the boost conversion units to determine the pulse width modulation duty cycle of any one of the boost conversion units; control the on and off of the switching tube in any one of the boost conversion units using the pulse width modulation duty cycle; where the actual branch current is the actual input current of the inductance coil in the boost conversion unit.

[0007] In some embodiments of this application, the magnetic integrated inductor further includes a decoupling magnetic column and two flat magnetic cores;

[0008] A decoupling magnetic column is provided between every two adjacent winding magnetic columns, and the two flat magnetic cores are located at both ends of the winding magnetic columns and the decoupling magnetic column;

[0009] Among them, the magnetic permeability of the decoupling magnetic column is higher than that of the two flat magnetic cores and the winding magnetic columns.

[0010] In some embodiments of the present application, the sampling unit includes:

[0011] An input voltage sampling sub-unit, which is arranged at the input end of the power factor correction circuit and is used to sample the input voltage of the power factor correction circuit;

[0012] An output voltage sampling sub-unit, which is arranged at the output end of the power factor correction circuit and is used to sample the output voltage of the power factor correction circuit;

[0013] A current sampling sub-unit, which is connected to each boost conversion unit and is used to sample the actual branch current of any one of the boost conversion units.

[0014] A second aspect of the present application proposes a power factor correction circuit control method, which is applied to the power factor correction circuit control system described in the first aspect. The method includes:

[0015] Based on the actual branch current of any one boost conversion unit in the power factor correction circuit, the input voltage and the output voltage of the power factor correction circuit, determine the target current of any one boost conversion unit; the actual branch current is the actual input current of the inductor coil in the boost conversion unit;

[0016] According to the target current of any one boost conversion unit, determine the actual decoupling inductance value of any one boost conversion unit;

[0017] Using the actual decoupling inductance value of any one boost conversion unit, determine the pulse width modulation duty cycle of any one boost conversion unit;

[0018] Use the pulse width modulation duty cycle to control the on and off of the switching tube in any one boost conversion unit.

[0019] In some embodiments of the present application, the determining the target current of any one boost conversion unit based on the actual branch current of any one boost conversion unit in the power factor correction circuit, the input voltage and the output voltage of the power factor correction circuit includes:

[0020] According to the input voltage, allocate a target branch current to any one boost conversion unit;

[0021] Determine the current error between the actual branch current and the target branch current of any one of the boost conversion units;

[0022] Obtain the voltage error between the output voltage and the preset target output voltage;

[0023] Use the voltage error, the current error of any one of the boost conversion units, and the actual branch current to determine the target current of any one of the boost conversion units.

[0024] In some embodiments of the present application, the step of allocating a target branch current to any one of the boost conversion units according to the input voltage includes:

[0025] Determine the input current of the power factor correction circuit according to the input voltage;

[0026] Average and allocate the input current according to the number of boost conversion units in the power factor correction circuit to obtain the target branch current of any one of the boost conversion units.

[0027] In some embodiments of the present application, the step of determining the input current of the power factor correction circuit according to the input voltage includes:

[0028] Calculate the voltage phase using the input voltage;

[0029] Obtain the current phase corresponding to the input current of the power factor correction circuit according to the voltage phase;

[0030] Determine the input current using the current phase.

[0031] In some embodiments of the present application, the step of determining the actual decoupling inductance value of any one of the boost conversion units according to the target current of any one of the boost conversion units includes:

[0032] Determine the self-inductance corresponding to the target current according to a preset self-inductance relationship, and determine the mutual inductance corresponding to the target current according to a preset mutual inductance relationship; the self-inductance relationship represents the relationship between current and self-inductance, and the mutual inductance relationship represents the relationship between current and mutual inductance;

[0033] Obtain the actual decoupling inductance value of any one of the boost conversion units using the self-inductance and the mutual inductance.

[0034] In some embodiments of the present application, the step of determining the pulse width modulation duty cycle of any one of the boost conversion units using the actual decoupling inductance value of any one of the boost conversion units includes:

[0035] Determine the inductance charging duration using the actual decoupling inductance value and the target current;

[0036] Determine the pulse width modulation duty ratio of any one of the boost conversion units by using the inductive charging duration.

[0037] The third aspect of the present application provides a power factor correction circuit control device, which is applied to the power factor correction circuit control system described in the first aspect. The device includes:

[0038] A current calculation module, configured to determine the target current of any one of the boost conversion units based on the actual branch current of any one of the boost conversion units in the power factor correction circuit, the input voltage and the output voltage of the power factor correction circuit; the actual branch current is the actual input current of the inductor coil in the boost conversion unit;

[0039] An inductance compensation module, configured to determine the actual decoupling inductance value of any one of the boost conversion units according to the target current of any one of the boost conversion units;

[0040] A duty ratio generation module, configured to determine the pulse width modulation duty ratio of any one of the boost conversion units by using the actual decoupling inductance value of any one of the boost conversion units;

[0041] A control module, configured to control the conduction and disconnection of the switching tube in any one of the boost conversion units by using the pulse width modulation duty ratio.

[0042] Based on the above power factor correction circuit control method, system and device, the technical solution of the present application has the following beneficial effects or advantages:

[0043] Considering that the inductance values of the inductor coils in each path of the magnetic integrated inductor used in the power factor correction circuit are inconsistent and change with the current, therefore, by collecting the actual branch current of any one of the boost conversion units in the power factor correction circuit, as well as the input voltage and the output voltage of the power factor correction circuit, and calculating the target current of any one of the boost conversion units according to the collected parameters, the actual decoupling inductance value of any one of the boost conversion units is determined according to the target current of any one of the boost conversion units, and the pulse width modulation duty ratio for adjusting the on / off of the switching tube in the boost conversion unit is generated by using the actual decoupling inductance value, so as to optimize the control current loop of the power factor correction circuit and reduce current harmonics. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative efforts.

[0045] Figure 1 This is a block diagram of a power factor correction circuit control system shown according to an exemplary embodiment of the present application;

[0046] Figure 2 This is a circuit schematic diagram of a power factor correction circuit control system shown according to an exemplary embodiment of the present application;

[0047] Figure 3 This is a schematic diagram of the structure of a magnetic integrated inductor shown according to an exemplary embodiment of the present application;

[0048] Figure 4 This is a schematic diagram of different current directions of a magnetic integrated inductor shown according to an exemplary embodiment of the present application;

[0049] Figure 5 This is a schematic diagram of an inductor current waveform shown according to an exemplary embodiment of the present application;

[0050] Figure 6 This is a schematic diagram of the implementation process of a power factor correction circuit control method shown according to an exemplary embodiment of the present application;

[0051] Figure 7 This is a schematic diagram of an inductor current waveform after feedback control shown according to an exemplary embodiment of the present application;

[0052] Figure 8 This is a schematic diagram of the equivalent circuit of a magnetic integrated inductor shown according to an exemplary embodiment of the present application;

[0053] Figure 9 This is a self - inductance curve and mutual - inductance curve diagram of a magnetic integrated inductor shown according to an exemplary embodiment of the present application;

[0054] Figure 10 This is a schematic diagram of different connection methods of a magnetic integrated inductor in a power factor correction circuit shown according to an exemplary embodiment of the present application;

[0055] Figure 11 This is a schematic diagram of the structure of a power factor correction circuit control device shown according to an exemplary embodiment of the present application.

[0056] The realization of the purpose, functional features and advantages of the present application will be further described in conjunction with the embodiments with reference to the accompanying drawings. Detailed Embodiments

[0057] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0058] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0059] In addition, the descriptions such as "first" and "second" in the present application are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0060] In the present application, unless otherwise clearly specified and limited, the terms "connected", "fixed", etc. should be understood in a broad sense. For example, "fixed" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0061] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0062] See Figure 1 As shown, the power factor correction circuit control system includes: a power factor correction circuit 10, a sampling unit 20, and a controller 30. The sampling unit 20 is respectively connected to the power factor correction circuit 10 and the controller 30. As Figure 2 As shown in the circuit schematic diagram of the power factor correction circuit control system, the power factor correction circuit 10 includes a plurality of parallel boost conversion units ( Figure 2The figure shows a two-way boost conversion unit, namely a first boost conversion unit 101 and a second boost conversion unit 102), and a magnetically integrated inductor 103. The magnetically integrated inductor 103 includes winding magnetic columns with the same number as the boost conversion units. Each boost conversion unit is connected to an inductor coil on one winding magnetic column. When current passes through the inductor coil, a magnetic field will be generated. Therefore, each winding magnetic column in the magnetically integrated inductor 103 can be regarded as an inductor, that is, the first boost conversion unit 101 is connected to the first inductor L1, and the second boost conversion unit 102 is connected to the second inductor L2.

[0063] It can be seen from Figure 2 that the first boost conversion unit 101 includes a first switching tube Q1 and a first diode D1. The first inductor L1 in the magnetically integrated inductor 103 is connected to the first switching tube Q1 and the first diode D1. The second boost conversion unit 102 includes a second switching tube Q2 and a second diode D2. The second inductor L2 in the magnetically integrated inductor 103 is connected to the second switching tube Q2 and the second diode D2. Among them, the first inductor L1 is charged when the first switching tube Q1 is turned on, and the first inductor L1 discharges to the load and the capacitor C1 through the first diode D1 when the first switching tube Q1 is turned off. The second inductor L2 is charged when the second switching tube Q2 is turned on, and the second inductor L2 discharges to the load and the capacitor C1 through the second diode D2 when the second switching tube Q2 is turned off.

[0064] Thus, in the power factor correction circuit 10, by periodically controlling the conduction and disconnection of the first switching tube Q1 and the second switching tube Q2, the first inductor L1, the second inductor L2, and the capacitor C1 are charged and discharged to realize the output after raising the input voltage of the power factor correction circuit.

[0065] In this embodiment, the sampling unit 20 is used to sample the input voltage, output voltage, and the actual branch current of any boost conversion unit of the power factor correction circuit 10; the controller 30 is used to determine the target current of any boost conversion unit based on the input voltage, output voltage, and the actual branch current of any boost conversion unit, and according to the target current of any boost conversion unit, determine the actual decoupling inductance value of any boost conversion unit, and use the actual decoupling inductance value of any boost conversion unit to determine the pulse width modulation duty cycle of any boost conversion unit, and use the pulse width modulation duty cycle to control the conduction and disconnection of the switching tube in any boost conversion unit.

[0066] In the embodiment of the present application, by using a magnetically integrated inductor in the power factor correction circuit, compared with the traditional power factor correction circuit using multiple independent inductors in parallel, the wiring and volume of magnetic components can be reduced, and the power factor correction circuit can be miniaturized.

[0067] In some embodiments of the present application, such asFigure 2 As shown, the sampling unit 20 may include an input voltage sampling sub-unit 201, an output voltage sampling sub-unit 202, and a current sampling sub-unit 203.

[0068] The input voltage sampling sub-unit 201 is provided at the input end of the power factor correction circuit 10 and is used to sample the input voltage VAC of the power factor correction circuit 10.

[0069] The output voltage sampling sub-unit 202 is provided at the output end of the power factor correction circuit 10 and is used to sample the output voltage VDC of the power factor correction circuit 10.

[0070] The current sampling sub-unit 203 is connected to each boost conversion unit and is used to sample the actual branch current of any one boost conversion unit.

[0071] It should be noted here that the present application does not limit the specific implementation of the input voltage sampling sub-unit 201, the output voltage sampling sub-unit 202, and the current sampling sub-unit 203. Figure 2 The specific implementation of each sub-unit given is only an exemplary illustration.

[0072] As Figure 2 shown, the input voltage sampling sub-unit 201 introduces the voltage at the input end of the power factor correction circuit 10 into the operational amplifier OP3A by using resistors R10 and R11, and the input voltage VAC at the input end of the power factor correction circuit 10 is collected through the operational amplifier OP3A.

[0073] The output voltage sampling sub-unit 202 samples the output voltage VDC at the output end of the power factor correction circuit 10 by using voltage dividing resistors R5, R6, R7, R8, and R9.

[0074] The current sampling sub-unit 203 respectively collects the voltage drops VR1 and VR2 of the resistor R1 and the resistor R2 by using the operational amplifier OP1A and the operational amplifier OP2A, and thus the actual branch currents of the first boost conversion unit 101 and the second boost conversion unit 102 can be calculated from the voltage drops VR1 and VR2.

[0075] In this embodiment, by using three independent input voltage sampling sub-units, output voltage sampling sub-units, and current sampling sub-units in the sampling unit to sample the input voltage, output voltage, and the actual branch current of any one path respectively, they do not affect each other.

[0076] In some embodiments of the present application, such as Figure 3The magnetic integrated inductor shown. The magnetic integrated inductor 103 includes, in addition to the same number of winding magnetic columns as the number of boost conversion units, a decoupling magnetic column and two flat magnetic cores. A decoupling magnetic column is provided between every two adjacent winding magnetic columns, and the two flat magnetic cores are located at both ends of the winding magnetic columns and the decoupling magnetic column. The magnetic permeability of the decoupling magnetic column is higher than that of the two flat magnetic cores and the winding magnetic columns.

[0077] The decoupling magnetic column can be understood as an isolation column, which is used to optimize the magnetic field distribution and provide a low magnetic resistance path for the inductor. It can use high magnetic permeability materials, such as permalloy, ferrite, etc., to minimize the coupling coefficient between inductors and reduce the cross-sectional area of the magnetic circuit.

[0078] The winding magnetic column can be understood as a winding magnetic column, which is used to wind the inductor coil. The winding magnetic column, the decoupling magnetic column, and the flat magnetic core form a closed magnetic circuit of the inductor. Therefore, after a set of inductor coils is wound on the winding magnetic column, it can be regarded as an inductor.

[0079] The winding magnetic column and the two flat magnetic cores can use medium magnetic permeability materials, such as iron-silicon, iron-silicon-aluminum, etc., in order to obtain high anti-saturation ability under large current. The two flat magnetic cores can be understood as the upper flat magnetic core and the lower flat magnetic core of the magnetic integrated inductor.

[0080] Thus, it can be seen that the magnetic permeability of the decoupling magnetic column is higher than that of the winding magnetic column and the flat magnetic core.

[0081] By tightly assembling the winding magnetic column, the decoupling magnetic column, and the two flat magnetic cores, a magnetic integrated inductor is formed.

[0082] It should be noted that the winding magnetic column, the decoupling magnetic column, and the two flat magnetic cores form a closed magnetic circuit, and the number of winding magnetic columns and decoupling magnetic columns is determined by the number of boost conversion units in the power factor correction circuit.

[0083] For example, if the number of boost conversion units in the power factor correction circuit is 2, then 2 winding magnetic columns and 1 decoupling magnetic column are used to form a magnetic integrated inductor, which can be regarded as an inductor with a two-in-one structure. Figure 3 It can be seen that 2 winding magnetic columns can be regarded as two inductors, namely the first inductor L1 and the second inductor L2; if the number of boost conversion units in the power factor correction circuit is 3, then 3 winding magnetic columns and 2 decoupling magnetic columns are used to form a magnetic integrated inductor, which can be regarded as an inductor with a three-in-one structure.

[0084] In this embodiment, the magnetic integrated inductor used in the power factor correction circuit is composed of magnetic permeability materials with different characteristics, that is, high magnetic permeability materials are used on the shared decoupling magnetic column to reduce the cross-sectional area of the magnetic circuit and achieve miniaturization, and on the independent winding magnetic columns, relatively low magnetic permeability materials are used to ensure the anti-saturation ability under high temperature and large current.

[0085] Since the above-mentioned magnetically integrated inductor uses materials with different permeabilities, the inductance of the magnetically integrated inductor will change with current, frequency, temperature, etc., and exhibit obvious non-linear changes. If the inductance is not corrected in real time, it will cause the control current loop of the power factor correction circuit to jitter, increase the input current harmonics, and even cause distortion.

[0086] In addition, if the current directions of the inductance coils are different, the magnetic field distributions will be different. As Figure 4 shown, the magnetic flux generated by the first inductor L1 has two loops: , and the magnetic flux generated by the second inductor L2 has two loops: . When the current directions of the first inductor L1 and the second inductor L2 are the same, the magnetic fluxes generated by the first inductor L1 and the second inductor L2 cancel each other out in the decoupling magnetic column; when the current directions of the first inductor L1 and the second inductor L2 are opposite, the magnetic fluxes generated by the first inductor L1 and the second inductor L2 are enhanced in the same direction in the decoupling magnetic column. Therefore, the maximum magnetic flux that the decoupling magnetic column can withstand is the sum of the maximum magnetic fluxes of the two inductors.

[0087] In an ideal inductor, the first inductor L1 = the second inductor L2. When the current of the first inductor L1 is equal to the current of the second inductor L2, that is when, , that is, when the current directions are opposite, the decoupling magnetic column has to withstand twice the magnetic flux; when the current directions are the same, the magnetic flux of the decoupling magnetic column is zero. However, in practical applications, the inductance parameters of the two inductors are inconsistent and change with current: 1. Differences in materials, processes, etc. result in the inductances of the two inductors not being exactly the same; 2. When the power factor correction circuit is working, the currents of the two inductors are not the same at a certain moment. As Figure 5 shown, in the case where the current directions of the two inductors are the same, it can be seen from the current waveforms of the two inductors that the instantaneous currents of the two inductors are not the same. Due to the changes in the magnetic field and magnetic flux density of the inductors, the harmonics and ripples of the current waveforms increase significantly.

[0088] Therefore, during the operation of the power factor correction circuit, feedback control needs to be added to optimize the current ripple and harmonics.

[0089] Next, the feedback control scheme of the power factor correction circuit will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application.

[0090] Figure 6 FIG. is a schematic flowchart of an embodiment of a control method for a power factor correction circuit according to an exemplary embodiment of the present application. Based on the embodiments shown in the above Figure 1 and Figure 2 , the control method for the power factor correction circuit includes the following steps:

[0091] Step 601: Determine the target current of any boost conversion unit in the power factor correction circuit based on the actual branch current of the boost conversion unit, the input voltage, and the output voltage of the power factor correction circuit.

[0092] Step 602: Determine the actual decoupling inductance value of any boost conversion unit according to the target current of the boost conversion unit.

[0093] Step 603: Determine the pulse width modulation duty cycle of any boost conversion unit by using the actual decoupling inductance value of the boost conversion unit.

[0094] Step 604: Use the pulse width modulation duty cycle to control the conduction and disconnection of the switching tube in any boost conversion unit.

[0095] The actual branch current is the actual input current of the inductor coil in the boost conversion unit, that is, the inductor current, and this actual branch current is equal to the current value sampled by the current sampling sub-unit during the conduction of the switching tube. In the power factor correction circuit, a periodic PWM (Pulse Width Modulation) signal is input to the control end of the switching tube in each boost conversion unit. During the high level period, the switching tube conducts, and during the low level period, the switching tube turns off. As shown above Figure 2 When the first switching tube Q1 conducts, the inductor current flows through the resistor R1, and the current sampling sub-unit detects the voltage drop VR1 across the resistor R1, so as to calculate the branch current of the first boost conversion unit 101 in the current cycle according to the voltage drop VR1; when the second switching tube Q2 conducts, the inductor current flows through the resistor R2, and the current sampling sub-unit detects the voltage drop VR2 across the resistor R2, so as to calculate the branch current of the second boost conversion unit 102 in the current cycle according to the voltage drop VR2. It can be seen that the branch current can be understood as the inductor current of the boost conversion unit in the current cycle.

[0096] The input voltage can be understood as the absolute value of the sinusoidal wave voltage rectified by the rectifier bridge BR1 collected by the input voltage sampling sub-unit.

[0097] The output voltage can be understood as the voltage provided by the power factor correction circuit to the load collected by the output voltage sampling sub-unit, and this output voltage is the voltage after being boosted by the boost conversion unit.

[0098] The target current can be understood as the branch current of the next cycle estimated according to the input voltage, the output voltage, and the branch current in the current cycle.

[0099] The actual decoupling inductance value can be understood as the inductance value after the inductor connected to the boost conversion unit is corrected, that is, the decoupled inductance value.

[0100] The pulse-width modulation duty cycle refers to the time ratio of the high level within one cycle. For example, if the cycle is 2 ms and the pulse-width modulation duty cycle is 0.5, it means that within one cycle, the high level lasts for 1 ms and the low level lasts for 1 ms. This pulse-width modulation duty cycle can be used as the control parameter of the switching tube in the boost conversion unit for the next cycle.

[0101] Use this pulse-width modulation duty cycle to control the conduction and disconnection of the switching tube in any boost conversion unit. The specific method is as follows: Generate a PWM signal according to the pulse-width modulation duty cycle and provide the PWM signal to the control terminal of the switching tube.

[0102] Exemplarily, as Figure 7 shown, when the current directions of the two inductors are the same, after the feedback control of the above steps 601 - 604, it can be seen from the current waveforms of the two inductors that the harmonics and ripples of the current waveforms are significantly improved.

[0103] So far, the above Figure 6 shown control process is completed. Considering that the actual inductance values of the inductance coils in each path of the magnetic integrated inductor used in the power factor correction circuit are not exactly the same and vary with the current, therefore, by collecting the actual branch current of any boost conversion unit in the power factor correction circuit, as well as the input voltage and output voltage of the power factor correction circuit, and calculating the target current of any boost conversion unit based on these collected parameters, thus determining the actual decoupling inductance value of any boost conversion unit according to the target current of any boost conversion unit, and generating a pulse-width modulation duty cycle for adjusting the on-off of the switching tube in the boost conversion unit using the actual decoupling inductance value, to achieve the optimization of the control current loop of the power factor correction circuit and reduce current harmonics.

[0104] In some embodiments of the present application, the above step 601 may include:

[0105] According to the input voltage, allocate a target branch current to any boost conversion unit, determine the current error between the actual branch current and the target branch current of any boost conversion unit, and obtain the voltage error between the output voltage and the preset target output voltage. Then, use the voltage error, the current error of any boost conversion unit, and the actual branch current to determine the target current of any boost conversion unit.

[0106] Among them, since the power factor correction circuit adopts an interleaved parallel control technology, each boost conversion unit plays a role in shunting the input current. According to the actual usage requirements, a certain target branch current will be allocated to any boost conversion unit, and this target branch current is the theoretical target current that the boost conversion unit needs to reach.

[0107] The current error can be understood as the difference between the branch current of the boost conversion unit in the current cycle and the theoretical target current.

[0108] The target output voltage can be understood as the voltage value that the power factor correction circuit needs to stably output to enable the load to operate stably. Therefore, the voltage error represents the difference between the actual output voltage and the target output voltage of the power factor correction circuit.

[0109] It should be noted here that the determination method of the target current for any boost conversion unit can be obtained by using the law of conservation of energy based on the voltage error, current error, and branch current. The specific calculation process is not elaborated in this application.

[0110] In this embodiment, by obtaining the current error of any boost conversion unit and the voltage error of the output voltage of the power factor correction circuit, and then combining the voltage error, current error, and the actual branch current of any boost conversion unit, the target current of any boost conversion unit in the next cycle is estimated to ensure that the current and voltage of the power factor correction circuit reach a balanced state.

[0111] In some embodiments of this application, for allocating the input current to any boost conversion unit according to the input voltage, it may include:

[0112] Determine the input current of the power factor correction circuit according to the input voltage, and then evenly distribute the input current according to the number of boost conversion units in the power factor correction circuit to obtain the target branch current of any boost conversion unit.

[0113] The input current of the power factor correction circuit can be understood as the input terminal current of the power factor correction circuit.

[0114] Since the operating frequencies of all boost conversion units are the same, theoretically, all boost conversion units should evenly split the input current. Therefore, the input current is distributed to the boost conversion units by the average distribution method to ensure the current stress balance of the switching tubes in all boost conversion units.

[0115] In this embodiment, by evenly distributing the input current to all boost conversion units, the currents of all paths are kept balanced, eliminating a part of the current ripple, thereby reducing the ripple of the total circuit current.

[0116] In some embodiments of this application, for determining the input current of the power factor correction circuit according to the input voltage, it may include:

[0117] Calculate the voltage phase using the input voltage, and obtain the corresponding current phase of the input current of the power factor correction circuit according to the voltage phase, so as to determine the input current of the power factor correction circuit using the current phase.

[0118] Among them, the input voltage can be understood as a sinusoidal voltage signal, and the voltage phase refers to the phase shift of the input voltage. In a power factor correction circuit, the input current usually lags behind the input voltage. Since the phase difference between the current and the voltage is determined by the power factor of the power factor correction circuit, the current phase can be obtained using the power factor and the voltage phase, and then the input current can be obtained by combining the input power and the current phase of the power factor correction circuit.

[0119] In this embodiment, the phase of the current is derived from the phase of the input voltage, and then the input current of the power factor correction circuit is calculated using the current phase.

[0120] In some embodiments of the present application, the above step 602 may include:

[0121] Determine the self-inductance value corresponding to the target current according to a preset self-inductance relationship, and determine the mutual-inductance value corresponding to the target current according to a preset mutual-inductance relationship. Then, use the self-inductance value and the mutual-inductance value to obtain the actual decoupling inductance value of any boost conversion unit.

[0122] The self-inductance relationship represents the relationship between the current and the self-inductance, that is, the relationship between the inductance of the magnetic integrated inductor and the current change. The mutual-inductance relationship represents the relationship between the current and the mutual-inductance, that is, the relationship between the mutual-inductance of the magnetic integrated inductor and the current change.

[0123] The self-inductance relationship and the mutual-inductance relationship can be pre-fitted according to the experimental data of the magnetic integrated inductor.

[0124] Taking the above Figure 3 or Figure 4 the two-in-one structure magnetic integrated inductor shown as an example, as Figure 8 shown, when the current directions are the same, the method for measuring the equivalent inductance is: short-circuit BC and measure the inductance between AD, which is the equivalent inductance , when the current directions are opposite, the method for measuring the equivalent inductance is: short-circuit BD and measure the inductance between AC, which is the equivalent inductance . It can be seen that multiple groups of experimental data of current and inductance can be obtained through measurement means, and thus the self-inductance relationship can be fitted according to these experimental data.

[0125] The relationship between the self-inductance voltage of the magnetic integrated inductor, the inductance, and the current is as follows:

[0126]

[0127]

[0128] Based on the above relationship, it can be deduced that when the currents are in the same direction, the equivalent inductance The calculation formula is as follows: (Formula 1); when the current is reversed, the equivalent inductance The calculation formula is as follows: (Formula 2).

[0129] From Formula 1 and Formula 2, the mutual inductance M can be derived as: (Formula 3).

[0130] After obtaining multiple sets of experimental data of current and inductance, the corresponding mutual inductance can be obtained according to Formula 3, and then the mutual inductance relationship formula can be obtained by fitting according to multiple sets of experimental data of current and mutual inductance.

[0131] As Figure 9 shown, through the above measurement means, the self-inductance L-I curve of the first inductor L1 and the self-inductance L-I curve of the second inductor L2 in the magnetic integrated inductor, as well as the mutual inductance L-I curve of the two inductors, can be obtained respectively. The vertical axis represents the inductance, with the unit of μH, and the horizontal axis represents the current, with the unit of A. It can be seen from Figure 9 that the self-inductance of the inductor changes non-linearly with the current, and the changes in the self-inductances of the first inductor L1 and the second inductor L2 are not consistent.

[0132] Under normal circumstances, as Figure 10 shown, in the magnetic integrated inductor, the first inductor L1 and the second inductor L2 can be connected in the current co-directional manner or the current reverse-directional manner in the power factor correction circuit. The relationship of the actual decoupling inductance values of the first inductor L1 and the second inductor L2 is expressed as follows:

[0133]

[0134]

[0135] Among them, when i1 = i2, it can be obtained that:

[0136] When the current is co-directional, the actual decoupling inductance values of the first inductor L1 and the second inductor L2 , ;

[0137] When the current is reversed, the actual decoupling inductance values of the first inductor L1 and the second inductor L2 , .

[0138] It can be seen that by using the self-inductance and mutual inductance, the actual decoupled inductance value of any boost conversion unit is obtained. The specific method is as follows: when the currents are in the same direction, the sum of the self-inductance and mutual inductance is used as the actual decoupled inductance value; when the currents are in the opposite direction, the difference between the self-inductance and mutual inductance is used as the actual decoupled inductance value. This actual decoupled inductance value is the actual inductance after removing the influence of mutual inductance.

[0139] In this embodiment, the self-inductance value and mutual inductance value corresponding to the target current are queried by using the pre-obtained self-inductance relationship and mutual inductance relationship, and then the actual inductance value is calculated according to the self-inductance value and mutual inductance value to eliminate the influence of mutual inductance.

[0140] In some embodiments of the present application, step 603 may include:

[0141] Using the actual decoupled inductance value and the target current, determine the inductance charging duration, and use this inductance charging duration to determine the pulse width modulation duty cycle of any boost conversion unit.

[0142] For each branch in the power factor correction circuit, the inductance value affects the change rate of the current. Usually, a dynamic model is used to describe the inductor current, and the change relationship can be expressed as:

[0143] (Formula 4)

[0144] In the above formula 4, represents the initial current, represents the input voltage, represents the output voltage, represents the actual decoupled inductance value.

[0145] Under steady-state conditions, the change of the inductor current is periodic within a medium cycle. Therefore, the following relationship can be used to calculate the inductance charging duration:

[0146] (Formula 5)

[0147] In the above formula 5, represents the target current.

[0148] The pulse width modulation duty cycle refers to the proportion of the conduction time of the switching tube in the total cycle. Assuming the total cycle is T, the pulse width modulation duty cycle D is:

[0149] (Formula 6)

[0150] In this embodiment, the inductance charging duration is calculated by using the supplemented inductance value and the target current, and then the pulse width modulation duty cycle is obtained according to the inductance charging duration to ensure that the output voltage is maintained at the set value.

[0151] Corresponding to the embodiments of the foregoing power factor correction circuit control method, the present application also provides embodiments of a power factor correction circuit control device.

[0152] Figure 11 FIG. is a schematic structural diagram of a power factor correction circuit control device according to an exemplary embodiment of the present application. Based on the foregoing Figures 1 to 10 shown embodiments, as Figure 11 shown, the power factor correction circuit control device includes:

[0153] A current calculation module 100, configured to determine a target current of any one boost conversion unit in the power factor correction circuit based on an actual branch current of any one boost conversion unit in the power factor correction circuit, an input voltage, and an output voltage of the power factor correction circuit; the actual branch current is an actual input current of an inductor coil in the boost conversion unit;

[0154] An inductor compensation module 110, configured to determine an actual decoupling inductor value of any one boost conversion unit according to the target current of any one boost conversion unit;

[0155] A duty ratio generation module 120, configured to determine a pulse width modulation duty ratio of any one boost conversion unit by using the actual decoupling inductor value of any one boost conversion unit;

[0156] A control module 130, configured to control conduction and disconnection of a switching transistor in any one boost conversion unit by using the pulse width modulation duty ratio.

[0157] The power factor correction circuit control device provided by the embodiments of the present application and the power factor correction circuit control method provided by the embodiments of the present application are based on the same inventive concept and have the same beneficial effects as the methods adopted, run, or implemented by them.

[0158] The foregoing are only preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural transformation made by using the specification and drawings of the present application under the concept of the present application, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present application.

Claims

1. A power factor correction circuit control system, characterized in that: The system comprises: a power factor correction circuit, a sampling unit and a controller, wherein the sampling unit is connected to the power factor correction circuit and the controller respectively, the power factor correction circuit comprises a plurality of boost conversion units and a magnetic integrated inductor connected in parallel, the magnetic integrated inductor comprises a winding magnetic column having the same number as the boost conversion units, and each of the boost conversion units is connected to an inductor coil on the winding magnetic column; The sampling unit is used to sample the input voltage and output voltage of the power factor correction circuit and the actual branch current of any one of the boost conversion units; The controller is used to determine the target current of any boost conversion unit in the power factor correction circuit based on the actual branch current of any boost conversion unit in the power factor correction circuit, the input voltage and the output voltage of the power factor correction circuit; determine the actual decoupling inductance value of any boost conversion unit according to the target current of any boost conversion unit; determine the pulse width modulation duty cycle of any boost conversion unit using the actual decoupling inductance value of any boost conversion unit; and use the pulse width modulation duty cycle to control the conduction and disconnection of the switch tube in any boost conversion unit; wherein the actual branch current is the actual input current of the inductor coil in the boost conversion unit.

2. The system according to claim 1, characterized in that The magnetic integrated inductor also includes a decoupling magnetic column and two planar magnetic cores; A decoupling magnetic column is provided between every two adjacent winding magnetic columns, and the two planar magnetic cores are located at both ends of the winding magnetic column and the decoupling magnetic column; The magnetic permeability of the decoupled magnetic column is higher than the magnetic permeability of the two planar magnetic cores and the wound magnetic column.

3. The system according to claim 1, characterized in that The sampling unit comprises: An input voltage sampling subunit, provided at the input end of the power factor correction circuit, for sampling the input voltage of the power factor correction circuit; An output voltage sampling subunit, provided at the output end of the power factor correction circuit, for sampling the output voltage of the power factor correction circuit; The current sampling subunit is connected to each of the boost conversion units and is used to sample the actual branch current of any of the boost conversion units.

4. A power factor correction circuit control method, characterized in that: Applied to the power factor correction circuit control system according to any one of claims 1 to 3, the method comprising: Determine the target current of any one of the boost conversion units based on the actual branch current of any one of the boost conversion units in the power factor correction circuit, the input voltage and the output voltage of the power factor correction circuit; the actual branch current is the actual input current of the inductor in the boost conversion unit; Determining an actual decoupling inductance value of any one of the boost conversion units according to a target current of any one of the boost conversion units; Determine the pulse width modulation duty cycle of any one of the boost conversion units by using the actual decoupling inductance value of any one of the boost conversion units; The pulse width modulation duty cycle is used to control the on and off of the switch tube in any one of the boost conversion units.

5. The method according to claim 4, characterized in that The step of determining a target current of any one of the boost conversion units in the power factor correction circuit based on an actual branch current of any one of the boost conversion units in the power factor correction circuit, and an input voltage and an output voltage of the power factor correction circuit, comprises: Allocating a target branch current to any one of the boost conversion units according to the input voltage; Determining a current error between an actual branch current and a target branch current of any one of the boost conversion units; Obtaining a voltage error between the output voltage and a preset target output voltage; The target current of any one of the boost conversion units is determined by using the voltage error, the current error of any one of the boost conversion units, and the actual branch current.

6. The method according to claim 5, characterized in that The allocating a target branch current to any one of the boost conversion units according to the input voltage includes: determining an input current of the power factor correction circuit according to the input voltage; According to the number of boost conversion units in the power factor correction circuit, the input current is evenly distributed to obtain a target branch current of any one of the boost conversion units.

7. The method according to claim 6, characterized in that The step of determining the input current of the power factor correction circuit according to the input voltage comprises: calculating a voltage phase using the input voltage; Obtaining a current phase corresponding to an input current of the power factor correction circuit according to the voltage phase; The input current is determined using the current phase.

8. The method according to claim 4, characterized in that The step of determining the actual decoupling inductance value of any one of the boost conversion units according to the target current of any one of the boost conversion units comprises: Determine the self-inductance corresponding to the target current according to a preset self-inductance relationship, and determine the mutual inductance corresponding to the target current according to a preset mutual inductance relationship; the self-inductance relationship represents the relationship between the current and the self-inductance, and the mutual inductance relationship represents the relationship between the current and the mutual inductance; The actual decoupling inductance value of any one of the boost conversion units is obtained by using the self-inductance inductance and the mutual inductance.

9. The method according to claim 4, characterized in that The step of determining the pulse width modulation duty cycle of any one of the boost conversion units by using the actual decoupling inductance value of any one of the boost conversion units comprises: Determining an inductor charging time using the actual decoupling inductance value and the target current; The pulse width modulation duty cycle of any one of the boost conversion units is determined by using the inductor charging time.

10. A power factor correction circuit control device, characterized in that: Applicable to the power factor correction circuit control system according to any one of claims 1 to 3, the device comprising: A current calculation module, used to determine a target current of any boost conversion unit in the power factor correction circuit based on an actual branch current of any boost conversion unit in the power factor correction circuit, an input voltage and an output voltage of the power factor correction circuit; the actual branch current is an actual input current of the inductor in the boost conversion unit; An inductance compensation module, used to determine an actual decoupling inductance value of any one of the boost conversion units according to a target current of any one of the boost conversion units; A duty cycle generating module, used to determine the pulse width modulation duty cycle of any one of the boost conversion units by using the actual decoupling inductance value of any one of the boost conversion units; A control module is used to use the pulse width modulation duty cycle to control the on and off of the switch tube in any one of the boost conversion units.

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