Power factor correction circuit control method, system and device

Abstract

The invention discloses a power factor correction circuit control method, system and device, and relates to the technical field of electronic power, and the method comprises the steps: calculating the actual branch current of any boost conversion unit in a power factor correction circuit, and the input voltage and output voltage of the power factor correction circuit; determining a target current of any boost conversion unit; the actual branch current is the actual input current of an inductance coil in the boost conversion unit; determining an 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 ratio of any boost conversion unit by using the actual decoupling inductance value of any boost conversion unit; and the pulse width modulation duty ratio is used to control on and off of a switch tube in any boost conversion unit, so that optimization of a control current loop of the power factor correction circuit is realized, and current harmonics are reduced.

Description

Technical Field

[0001] The present application relates to the field of electronic power, and in particular to a power factor correction circuit control method, system and device. Background Art

[0002] Various power factor correction (PFC) circuits are widely used in application fields such as new energy charging systems and variable frequency air conditioning systems. Among them, inductors are essential magnetic components for power factor correction circuits. Power factor correction circuits use multiple inductors in parallel. Since it is difficult to make the inductor parameters consistent and the inductance changes nonlinearly due to the influence of current, frequency, temperature, etc., it is 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 the present application is to propose a power factor correction circuit control method, system and device to address the deficiencies of the above-mentioned prior art, and this purpose is achieved through the following technical solutions.

[0004] The first aspect of the present application provides a power factor correction circuit control system, the system comprising: a power factor correction circuit, a sampling unit and a controller, the sampling unit being connected to the power factor correction circuit and the controller respectively, the power factor correction circuit comprising a plurality of boost conversion units and a magnetic integrated inductor connected in parallel, the magnetic integrated inductor comprising the same number of winding magnetic columns as the boost conversion units, each of the boost conversion units correspondingly 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.

[0005] In some embodiments of the present application, the magnetic integrated inductor further 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.

[0006] In some embodiments of the present application, the sampling unit includes: 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.

[0007] The second aspect of the present application provides a power factor correction circuit control method, which is applied to the power factor correction circuit control system described in the first aspect, and the method includes: 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.

[0008] In some embodiments of the present application, determining the target current of any one of the boost conversion units in the power factor correction circuit 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 includes: 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.

[0009] In some embodiments of the present application, 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.

[0010] In some embodiments of the present application, determining the input current of the power factor correction circuit according to the input voltage includes: 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.

[0011] In some embodiments of the present application, 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: 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.

[0012] 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 by using the actual decoupling inductance value of any one of the boost conversion units includes: 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.

[0013] A 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, and the device includes: 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.

[0014] 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: Taking into account that the inductance of each inductor coil in the magnetic integrated inductor used in the power factor correction circuit is inconsistent and changes with the current, 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 are collected, and the target current of any boost conversion unit is calculated based on the collected parameters, so as to determine the actual decoupling inductance value of any boost conversion unit according to the target current of any boost conversion unit, and use the actual decoupling inductance value to generate a pulse width modulation duty cycle for adjusting the on and off of the switch tube in the boost conversion unit, thereby optimizing the control current loop of the power factor correction circuit and reducing current harmonics. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0016] Figure 1 This is a block diagram of a power factor correction circuit control system according to an exemplary embodiment of the present application; Figure 2 This is a circuit diagram of a power factor correction circuit control system according to an exemplary embodiment of the present application; Figure 3 This is a schematic diagram of a magnetic integrated inductor structure according to an exemplary embodiment of the present application; Figure 4 This is a schematic diagram of different current directions of a magnetic integrated inductor according to an exemplary embodiment of the present application; Figure 5 A schematic diagram of an inductor current waveform according to an exemplary embodiment of the present application is shown; Figure 6This is a schematic flow chart of an embodiment of a power factor correction circuit control method according to an exemplary embodiment of the present application; Figure 7 This is a schematic diagram of an inductor current waveform after feedback control according to an exemplary embodiment of the present application; Figure 8 This is a schematic diagram of an equivalent circuit of a magnetic integrated inductor according to an exemplary embodiment of the present application; Fig. 9 A self-inductance curve and a mutual inductance curve of a magnetic integrated inductor according to an exemplary embodiment of the present application are shown; Fig.10 This is a schematic diagram of different connection methods of a magnetic integrated inductor in a power factor correction circuit according to an exemplary embodiment of the present application; Fig.11 This is a schematic diagram of the structure of a power factor correction circuit control device according to an exemplary embodiment of the present application.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0020] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0021] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0022] 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 fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0023] See also 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, and the sampling unit 20 is connected to the power factor correction circuit 10 and the controller 30 respectively. Figure 2 The power factor correction circuit control system circuit schematic diagram shown in FIG. 1 includes a plurality of boost conversion units connected in parallel ( Figure 2 2 boost conversion units, namely a first boost conversion unit 101 and a second boost conversion unit 102) and a magnetic integrated inductor 103 are shown. The magnetic integrated inductor 103 includes winding magnetic columns of the same number as the boost conversion units. Each boost conversion unit is connected to an inductor coil on a winding magnetic column. Current passing through the inductor coil will generate a magnetic field. Therefore, each winding magnetic column in the magnetic integrated inductor 103 can be regarded as an inductor, namely, 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.

[0024] Depend on Figure 2 It can be seen that the first boost conversion unit 101 includes a first switch tube Q1 and a first diode D1, the first inductor L1 in the magnetic integrated inductor 103 is connected to the first switch tube Q1 and the first diode D1, and the second boost conversion unit 102 includes a second switch tube Q2 and a second diode D2, and the second inductor L2 in the magnetic integrated inductor 103 is connected to the second switch tube Q2 and the second diode D2. Among them, the first inductor L1 is charged when the first switch tube Q1 is turned on, and the first inductor L1 is discharged to the load and the capacitor C1 through the first diode D1 when the first switch tube Q1 is turned off, and the second inductor L2 is charged when the second switch tube Q2 is turned on, and the second inductor L2 is discharged to the load and the capacitor C1 through the second diode D2 when the second switch tube Q2 is turned off.

[0025] It can be seen that the power factor correction circuit 10 periodically controls the on and off of the first switch tube Q1 and the second switch tube Q2 to charge and discharge the first inductor L1 and the second inductor L2 and the capacitor C1, so as to increase the input voltage of the power factor correction circuit and then output it.

[0026] In this embodiment, the sampling unit 20 is used to sample the input voltage, the 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, the output voltage and the actual branch current of any boost conversion unit, and determine the actual decoupling inductance value of any boost conversion unit according to the target current of any boost conversion unit, and 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.

[0027] In an embodiment of the present application, by using a magnetic integrated inductor in a power factor correction circuit, compared with a traditional power factor correction circuit that uses multiple independent inductors in parallel, the wiring and volume of the magnetic components can be reduced, and the power factor correction circuit can be miniaturized.

[0028] In some embodiments of the present application, Figure 2 As shown, the sampling unit 20 may include an input voltage sampling subunit 201 , an output voltage sampling subunit 202 , and a current sampling subunit 203 .

[0029] The input voltage sampling subunit 201 is disposed 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 .

[0030] The output voltage sampling subunit 202 is disposed 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 .

[0031] The current sampling subunit 203 is connected to each boost conversion unit and is used to sample the actual branch current of any boost conversion unit.

[0032] It should be noted that the present application does not limit the specific implementation of the input voltage sampling subunit 201, the output voltage sampling subunit 202, and the current sampling subunit 203. Figure 2 The specific implementation of each sub-unit given in the description is only an exemplary description.

[0033] like Figure 2As shown, the input voltage sampling subunit 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 collects the input voltage VAC at the input end of the power factor correction circuit 10 through the operational amplifier OP3A.

[0034] The output voltage sampling subunit 202 samples the output voltage VDC at the output end of the power factor correction circuit 10 by using the voltage dividing resistors R5 , R6 , R7 , R8 , and R9 .

[0035] The current sampling subunit 203 uses operational amplifier OP1A and operational amplifier OP2A to respectively collect voltage drops VR1 and VR2 of resistors R1 and R2, so that 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.

[0036] In this embodiment, three independent input voltage sampling subunits, output voltage sampling subunits and current sampling subunits are used in the sampling unit to respectively sample the input voltage, the output voltage and the actual branch current of any path without affecting each other.

[0037] In some embodiments of the present application, Figure 3 The magnetic integrated inductor shown, the magnetic integrated inductor 103, in addition to including the same number of winding magnetic columns as the boost conversion unit, 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 columns and the decoupling magnetic columns, and the magnetic permeability of the decoupling magnetic column is higher than the magnetic permeability of the two planar magnetic cores and the winding magnetic column.

[0038] Decoupling magnetic columns can be understood as isolation columns, which are used to optimize the magnetic field distribution and provide a low magnetic resistance channel for the inductor. High magnetic permeability materials such as iron-nickel-molybdenum and ferrite can be used to minimize the coupling coefficient between inductors and reduce the cross-sectional area of ​​the magnetic circuit.

[0039] The wound magnetic column can be understood as a wound magnetic column, which is used to wind the inductor coil. The wound magnetic column, the decoupling magnetic column, and the flat magnetic core constitute the closed magnetic circuit of the inductor. Therefore, after a group of inductor coils are wound on the wound magnetic column, it can be regarded as an inductor. The wound magnetic column and the two planar magnetic cores can use medium magnetic permeability materials, such as iron silicon and sendust, so as to obtain high anti-saturation capability under large current. The two planar magnetic cores can be understood as the upper planar magnetic core and the lower planar magnetic core of the magnetic integrated inductor.

[0040] It can be seen that the magnetic permeability of the decoupled magnetic column is higher than that of the wound magnetic column and the flat magnetic core.

[0041] A magnetic integrated inductor is formed by closely assembling a wound magnetic column, a decoupled magnetic column and two planar magnetic cores.

[0042] It should be noted that the winding magnetic column, the decoupling magnetic column and the two planar magnetic cores form a closed magnetic circuit, and the number of the winding magnetic column and the decoupling magnetic column is determined by the number of boost conversion units in the power factor correction circuit.

[0043] For example, if the number of boost conversion units in the power factor correction circuit is 2, then the magnetic integrated inductor composed of 2 winding magnetic columns and 1 decoupling magnetic column can be regarded as a two-in-one structure inductor. Figure 3 It can be seen that the two wound 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 the magnetic integrated inductor composed of three wound magnetic columns and two decoupling magnetic columns can be regarded as a three-in-one structure inductor.

[0044] In this embodiment, the magnetic integrated inductor used in the power factor correction circuit is composed of a combination of magnetic permeability materials with different characteristics, that is, high magnetic permeability materials are used on the common decoupling magnetic columns to reduce the cross-sectional area of ​​the magnetic circuit to achieve miniaturization, and relatively low magnetic permeability materials are used on independent winding magnetic columns to ensure anti-saturation capabilities under high temperature and high current.

[0045] Since the above-mentioned magnetic integrated inductor uses materials with different magnetic permeabilities, the inductance of the magnetic integrated inductor will change with the current, frequency, temperature, etc., and will show obvious nonlinear 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.

[0046] In addition, the magnetic field distribution will be different if the current direction of the inductor is different, such as Figure 4 As shown, the magnetic flux generated by the first inductor L1 has two loops: , 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 flux generated by the first inductor L1 and the second inductor L2 are reversely offset in the decoupling magnetic column; when the current directions of the first inductor L1 and the second inductor L2 are opposite, the magnetic flux generated by the first inductor L1 and the second inductor L2 are enhanced in the same direction in the decoupling magnetic column, so the maximum magnetic flux that the decoupling magnetic column can withstand is the sum of the maximum magnetic fluxes of the two inductors.

[0047] 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, hour, That is, when the current direction is opposite, the decoupling magnetic column has to bear twice the magnetic flux; when the current direction is the same, the magnetic flux of the decoupling magnetic column is zero. However, in actual applications, the inductance parameters of the two inductors are inconsistent and change with the current: 1. Differences in materials, processes, etc. cause the inductance of the two inductors to be not exactly the same; 2. When the power factor correction circuit is working, the currents of the two inductors are not the same at an instant, such as Figure 5 As shown in the figure, when 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 waveform are significantly increased.

[0048] Therefore, during the operation of the power factor correction circuit, feedback control needs to be added to optimize the current ripple and harmonics.

[0049] The feedback control scheme of the power factor correction circuit will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0050] Figure 6 This is a schematic diagram of an embodiment of a power factor correction circuit control method according to an exemplary embodiment of the present application, combined with the above Figure 1 and Figure 2 Based on the embodiment shown, the power factor correction circuit control method includes the following steps: Step 601: determining a target current of any boost conversion unit in a power factor correction circuit based on an actual branch current of the boost conversion unit, an input voltage and an output voltage of the power factor correction circuit; Step 602: determining an actual decoupling inductance value of any one of the boost conversion units according to a target current of the any one of the boost conversion units; Step 603: Determine the pulse width modulation duty cycle of any one of the boost conversion units by using the actual decoupling inductance value of the any one of the boost conversion units; Step 604: 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.

[0051] The actual branch current is the actual input current of the inductor coil in the boost converter unit, that is, the inductor current. The actual branch current is equal to the current value sampled by the current sampling subunit during the on-time of the switch tube. In the power factor correction circuit, the control end of the switch tube in each boost converter unit inputs a periodic PWM (Pulse Width Modulation) signal. During the high level period, the switch tube is turned on, and during the low level period, the switch tube is turned off, as mentioned above. Figure 2As shown, during the conduction period of the first switch tube Q1, the inductor current flows through the resistor R1, and the current sampling subunit detects the voltage drop VR1 of the resistor R1, thereby calculating the branch current of the first boost conversion unit 101 in the current cycle according to the voltage drop VR1; during the conduction period of the second switch tube Q2, the inductor current flows through the resistor R2, and the current sampling subunit detects the voltage drop VR2 of the resistor R2, thereby calculating 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.

[0052] The input voltage can be understood as the absolute value of the sinusoidal voltage collected by the input voltage sampling subunit after being rectified by the rectifier bridge BR1.

[0053] The output voltage can be understood as the voltage collected by the output voltage sampling subunit and provided to the load by the power factor correction circuit. The output voltage is the voltage after being boosted by the boost conversion unit.

[0054] The target current can be understood as the branch current of the next cycle estimated based on the input voltage, the output voltage, and the branch current of the current cycle.

[0055] The actual decoupling inductance value can be understood as the corrected inductance of the inductor connected to the boost conversion unit, that is, the decoupling inductance value.

[0056] The PWM duty cycle refers to the proportion of time that the high level occupies in one cycle. For example, if the cycle is 2ms and the PWM duty cycle is 0.5, it means that in one cycle, the high level lasts for 1 ms and the low level lasts for 1 ms. The PWM duty cycle can be used as a control parameter for the switch tube in the boost converter unit in the next cycle.

[0057] 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, specifically in the following manner: a PWM signal is generated according to the pulse width modulation duty cycle, and the PWM signal is provided to the control end of the switch tube.

[0058] For example, Figure 7 As shown, when the current directions of the two inductors are the same, after the feedback control of the above steps 601 to 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.

[0059] At this point, the above Figure 6The control process shown takes into account that the actual inductance of each inductor coil in the magnetic integrated inductor used in the power factor correction circuit is not exactly the same and changes with the current. Therefore, 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 are collected, and the target current of any boost conversion unit is calculated based on these collected parameters, so as to determine the actual decoupling inductance value of any boost conversion unit based on the target current of any boost conversion unit, and use the actual decoupling inductance value to generate a pulse width modulation duty cycle for adjusting the on and off of the switch tube in the boost conversion unit, thereby optimizing the control current loop of the power factor correction circuit and reducing current harmonics.

[0060] In some embodiments of the present application, the above step 601 may include: According to the input voltage, a target branch current is allocated to any boost conversion unit, a current error between an actual branch current of any boost conversion unit and the target branch current is determined, and a voltage error between an output voltage and a preset target output voltage is obtained. Then, the target current of any boost conversion unit is determined using the voltage error, the current error of any boost conversion unit and the actual branch current.

[0061] Among them, since the power factor correction circuit adopts the staggered parallel control technology, each boost conversion unit has a shunt effect on the input current. According to actual usage requirements, any boost conversion unit will be allocated a certain target branch current, which is the theoretical target current that the boost conversion unit needs to achieve.

[0062] 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.

[0063] The target output voltage can be understood as the voltage value that the power factor correction circuit needs to stably output so that the load can operate stably. Therefore, the voltage error represents the difference between the actual output voltage of the power factor correction circuit and the target output voltage.

[0064] It should be noted here that the target current of any boost conversion unit can be determined by using the law of conservation of energy based on the voltage error, current error and branch current, and the specific calculation process will not be described in detail in this application.

[0065] 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, the target current of any boost conversion unit in the next cycle is estimated by combining the voltage error, current error and the actual branch current of any boost conversion unit to ensure that the current and voltage of the power factor correction circuit reach a balanced state.

[0066] In some embodiments of the present application, allocating input current to any boost conversion unit according to input voltage may include: The input current of the power factor correction circuit is determined according to the input voltage, and then the input current is evenly distributed 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.

[0067] The input current of the power factor correction circuit can be understood as the input terminal current of the power factor correction circuit.

[0068] Since the operating frequency of each boost conversion unit is consistent, in theory, each boost conversion unit should divide the input current evenly. Therefore, the input current is distributed to the boost conversion unit in an average distribution manner to ensure that the current stress of the switch tube in each boost conversion unit is balanced.

[0069] In this embodiment, the input current is evenly distributed to each boost conversion unit, so that the currents of each path are kept balanced and a part of the current ripple is eliminated, thereby reducing the ripple of the total current of the circuit.

[0070] In some embodiments of the present application, determining the input current of the power factor correction circuit according to the input voltage may include: The voltage phase is calculated using the input voltage, and the current phase corresponding to the input current of the power factor correction circuit is obtained according to the voltage phase, so that the input current of the power factor correction circuit is determined using the current phase.

[0071] Among them, the input voltage can be understood as a sinusoidal voltage signal, and the voltage phase refers to the phase offset of the input voltage. In the power factor correction circuit, the input current usually lags behind the input voltage. Since the phase difference between current and voltage is determined by the power factor of the power factor correction circuit, the power factor and voltage phase can be used to obtain the current phase, and then the input current can be obtained by combining the input power and current phase of the power factor correction circuit.

[0072] 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.

[0073] In some embodiments of the present application, the above step 602 may include: The self-inductance inductance corresponding to the target current is determined according to the preset self-inductance relationship, and the mutual inductance inductance corresponding to the target current is determined according to the preset mutual inductance relationship, and then the actual decoupling inductance value of any boost conversion unit is obtained by using the self-inductance inductance and the mutual inductance.

[0074] The self-inductance relationship expresses the relationship between current and self-inductance, that is, the relationship between the inductance of the magnetic integrated inductor and the change of current. The mutual inductance relationship expresses the relationship between current and mutual inductance, that is, the relationship between the mutual inductance of the magnetic integrated inductor and the change of current.

[0075] The self-inductance relation and the mutual inductance relation can be fitted in advance based on the experimental data of the magnetic integrated inductor.

[0076] With the above Figure 3 or Figure 4 Take the two-in-one magnetic integrated inductor shown in the figure as an example. Figure 8 As shown in the figure, when the current direction is the same, the method to measure the equivalent inductance is: short-circuit BC and measure the inductance at both ends of AD, which is the equivalent inductance. When the current direction is opposite, the method to measure the equivalent inductance is: short-circuit BD and measure the inductance at both ends of AC, which is the equivalent inductance It can be seen that multiple sets of experimental data of current and inductance can be obtained through measurement means, and the self-inductance relationship can be fitted based on these experimental data.

[0077] The relationship between the self-inductance voltage, inductance and current of the magnetic integrated inductor is as follows:

[0078]

[0079] 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: (Formula 1); When the current is reversed, the equivalent inductance The calculation formula is: (Formula 2).

[0080] From formula 1 and formula 2, it can be deduced that the mutual inductance M is: (Formula 3).

[0081] After obtaining multiple sets of experimental data on current and inductance, the corresponding mutual inductance can be obtained according to Formula 3, and thus the mutual inductance relationship can be obtained by fitting according to the experimental data on multiple sets of current and mutual inductance.

[0082] like Fig. 9 As shown, the self-inductance LI curve of the first inductor L1 and the self-inductance LI curve of the second inductor L2 in the magnetic integrated inductor can be obtained by the above measurement means, as well as the mutual inductance LI curve of the two inductors. The vertical axis represents the inductance, in μH, and the horizontal axis represents the current, in A. Fig. 9It can be seen that the self-inductance of the inductor changes nonlinearly with the current, and the changes in the inductance of the first inductor L1 and the second inductor L2 are not consistent.

[0083] Usually, if Fig.10 As shown, the first inductor L1 and the second inductor L2 in the magnetic integrated inductor can be connected in the power factor correction circuit in the same current direction or in the opposite current direction. The relationship between the actual decoupling inductance values ​​of the first inductor L1 and the second inductor L2 is expressed as follows:

[0084]

[0085] Among them, when i1 = i2, we can get: When the currents are in the same direction, the actual decoupling inductance values ​​of the first inductor L1 and the second inductor L2 are , ; When the current is reversed, the actual decoupling inductance of the first inductor L1 and the second inductor L2 , .

[0086] It can be seen that the actual decoupling inductance value of any boost conversion unit can be obtained by using the self-inductance inductance and the mutual inductance. The specific method is: when the current is in the same direction, the sum of the self-inductance inductance and the mutual inductance is used as the actual decoupling inductance value; when the current is in the opposite direction, the difference between the self-inductance inductance and the mutual inductance is used as the actual decoupling inductance value. The actual decoupling inductance value is the actual inductance after removing the influence of the mutual inductance.

[0087] In this embodiment, the self-inductance value and the mutual inductance value corresponding to the target current are queried by using the pre-obtained self-inductance relationship and the mutual inductance relationship, and then the actual inductance value is calculated according to the self-inductance value and the mutual inductance value to eliminate the influence of the mutual inductance.

[0088] In some embodiments of the present application, the above step 603 may include: The actual decoupling inductance value and the target current are used to determine the inductor charging time, and the inductor charging time is used to determine the pulse width modulation duty cycle of any boost conversion unit.

[0089] For each branch in the power factor correction circuit, the inductance value affects the rate of change of the current. A dynamic model is usually used to describe the inductor current. The change relationship can be expressed as: (Formula 4) In the above formula 4, represents the initial current, Indicates the input voltage, Indicates the output voltage, Indicates the actual decoupling inductance value.

[0090] Under steady-state conditions, the change of inductor current is periodic within a megacycle, so the inductor charging time can be calculated using the following relationship: (Formula 5) In the above formula 5, Indicates the target current.

[0091] The pulse width modulation duty cycle refers to the proportion of the switch tube conduction time to the total cycle. Assuming the total cycle is T, the pulse width modulation duty cycle D is: (Formula 6) In this embodiment, the inductor charging time is calculated by using the supplemented inductance value and the target current, so that the pulse width modulation duty cycle is obtained according to the inductor charging time to ensure that the output voltage is maintained at a set value.

[0092] Corresponding to the above-mentioned embodiment of the power factor correction circuit control method, the present application also provides an embodiment of a power factor correction circuit control device.

[0093] Fig.11 This is a schematic diagram of a power factor correction circuit control device according to an exemplary embodiment of the present application. Figures 1 to 10 Based on the embodiment shown, Fig.11 As shown, the power factor correction circuit control device includes: The current calculation module 100 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; the actual branch current is the actual input current of the inductor in the boost conversion unit; An inductance compensation module 110, configured to determine an actual decoupling inductance value of any of the boost conversion units according to a target current of any of the boost conversion units; A duty cycle generating module 120, configured to determine a pulse width modulation duty cycle of any one of the boost conversion units by using an actual decoupling inductance value of any one of the boost conversion units; The control module 130 is used to control the on and off of the switch tube in any one of the boost conversion units by using the pulse width modulation duty cycle.

[0094] The power factor correction circuit control device provided in the embodiment of the present application and the power factor correction circuit control method provided in the embodiment of the present application are based on the same inventive concept and have the same beneficial effects as the methods adopted, operated or implemented therein.

[0095] The above description is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. All equivalent structural changes made based on the concept of the present application and the contents of the present application description and drawings, or direct / indirect application in other related technical fields are 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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