Non-isolated unidirectional boost converter and coupled inductor design method thereof

Abstract

The application provides a non-isolated one-way Boost converter and a coupled inductor design method thereof. The converter comprises a coupled inductor unit, a primary winding of the coupled inductor unit serving as an excitation inductor of the converter, and a secondary winding of the coupled inductor unit being connected in series with an auxiliary capacitor to form a passive filter branch. The passive filter branch is connected in parallel with an input power supply. The converter is configured to realize zero-voltage turn-on of the first switch tube or the second switch tube by controlling the alternating on-off of the first switch tube and the second switch tube, so that the current flowing through the excitation inductor flows bidirectionally. The passive filter branch is configured to generate a filter current with a phase opposite to a current ripple component of the excitation inductor through the coupling effect of the coupled inductor unit. The filter current and the current ripple component are superposed to offset the ripple of the input current. The application realizes zero-voltage turn-on of the switch tube and zero input current ripple at the same time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronic converters, and particularly relates to a non-isolated unidirectional Boost type converter and a coupled inductor design method thereof. BACKGROUND

[0002] Under the dual driving of energy crisis and environmental protection demand, hydrogen fuel cells, as a clean and efficient energy conversion device, have attracted widespread attention. However, the output characteristics of fuel cells are relatively soft, and the performance of the power electronic converter connected to the output of the fuel cells has very high requirements. The traditional Boost converter has two main defects: first, the hard switching working mode leads to large switching loss, which limits the improvement of conversion efficiency and switching frequency; second, the input current ripple is large, and the large peak current stress will accelerate the aging of the fuel cell catalyst, seriously shortening its service life.

[0003] To solve the problem of hard switching, existing soft switching technologies often need to add additional auxiliary circuits or complex control strategies, which not only increase the cost and complexity, but also may introduce new losses. To solve the problem of current ripple, the method of increasing passive components (such as inductors and capacitors) is usually used, but this goes against the development trend of miniaturization and high power density of power electronic systems. Therefore, how to realize high efficiency (soft switching) and high power quality (low input ripple) of the converter at the same time without complex auxiliary circuits has become a technical problem to be solved in the field. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a non-isolated unidirectional Boost type converter and a coupled inductor design method thereof, which realizes zero input current ripple while realizing zero voltage turn-on of the switching tube.

[0005] In a first aspect, the present application provides a non-isolated unidirectional Boost type converter, comprising an input power supply, a first switching tube, a second switching tube and an output capacitor, and the converter further comprises:

[0006] a coupled inductor unit, the primary winding of the coupled inductor unit serving as an excitation inductor of the converter, and the secondary winding of the coupled inductor unit being connected in series with an auxiliary capacitor to form a passive filter branch; wherein,

[0007] the passive filter branch is connected in parallel with the input power supply;

[0008] the converter is configured to control the alternating on-off of the first switching tube and the second switching tube, so that the current flowing through the excitation inductor flows in both directions, thereby realizing zero voltage turn-on of the first switching tube or the second switching tube;

[0009] The passive filter branch is configured to generate a filter current opposite in phase to a current ripple component of the excitation inductance through a coupling effect of the coupling inductance unit; and the filter current is superimposed with the current ripple component to cancel the ripple of the input current.

[0010] Optionally, the coupling inductance unit is integrated on the EE-type magnetic core in an interleaved winding structure; wherein the primary winding and the secondary winding are wound on two side columns of the EE-type magnetic core, respectively.

[0011] Optionally, the equivalent cantilever model of the coupling inductance unit comprises the excitation inductance and an ideal transformer in parallel; wherein the secondary side of the ideal transformer is in series with the equivalent leakage inductance; and the passive filter branch is composed of the ideal transformer, the equivalent leakage inductance and the auxiliary capacitor.

[0012] Optionally, the condition for canceling the ripple of the input current is:

[0013] The turns ratio of the ideal transformer satisfies the following relationship with the excitation inductance and the equivalent leakage inductance: ; wherein, represents the inductance value of the equivalent leakage inductance, represents the inductance value of the excitation inductance, represents the turns ratio of the ideal transformer.

[0014] Optionally, the non-isolated one-way Boost converter further comprises a control unit configured to perform digital adaptive frequency modulation, and the control unit is configured to:

[0015] In the dead time, the current of the excitation inductance is used to discharge the junction capacitance of the off switch tube, so that the body diode of the off switch tube is turned on; the off switch tube is the first switch tube or the second switch tube;

[0016] During the conduction of the body diode, the switch tube corresponding to the body diode is turned on to realize zero-voltage turn-on;

[0017] According to the input voltage, the output voltage, the excitation inductance value and the preset inductance current negative peak value, the switching frequency of the next switching period is dynamically calculated and set to ensure that the current of the excitation inductance is negative at the beginning of the dead time.

[0018] Optionally, the expression of the switching frequency is:

[0019]

[0020] wherein, represents the switching frequency, represents the switching period, represents the on time of the switch tube, represents the off time of the switch tube, represents the input voltage, represents the output voltage, represents the negative peak value of the inductance current.

[0021] In a second aspect, the present application provides a coupled inductor design method for the above transformer, comprising:

[0022] determining electrical parameters based on the input and output specifications of the transformer and the condition of canceling the ripple of the input current; the electrical parameters include the values of the turns ratio, the magnetizing inductance and the equivalent leakage inductance;

[0023] calculating the magnetic flux of each magnetic column of the magnetic core according to the magnetic flux superposition principle and the electrical parameters;

[0024] calculating the magnetic resistance of the side column and the middle column of the magnetic core according to the definition of self-inductance and mutual inductance and the magnetic flux;

[0025] calculating the required air gap length of each magnetic column according to the magnetic resistance and the cross-sectional area of the magnetic core;

[0026] calculating the cross-sectional area of the wire and the required window area of the magnetic core according to the effective value of the current and the selected current density, and selecting the appropriate magnetic core type through the AP method to complete the winding of the primary winding and the secondary interleaved winding.

[0027] Optionally, the magnetic flux of each magnetic column of the magnetic core is calculated according to the magnetic flux superposition principle and the electrical parameters, comprising:

[0028] through the calculation formula

[0029]

[0030] the magnetic flux of the first side magnetic column, the second side magnetic column and the middle magnetic column is obtained 、 、 ; wherein, represents the number of turns of the primary winding, represents the number of turns of the secondary interleaved winding, represents the primary current, represents the secondary current, represents the magnetic resistance of the first side magnetic column, represents the magnetic resistance of the second side magnetic column, represents the magnetic resistance of the middle magnetic column.

[0031] Optionally, the cross-sectional area of the wire and the required window area of the magnetic core are calculated according to the effective value of the current and the selected current density, comprising:

[0032] through the calculation formula

[0033]

[0034] the cross-sectional area of the wire is obtained ; wherein, represents the current effective value, represents the current density;

[0035] through the calculation formula

[0036]

[0037] get the magnetic core window area ; represents the utilization coefficient of the magnetic core window area, and the value is 0.2 to 0.3.

[0038] Optionally, the middle magnetic column cross-sectional area is configured as twice the side magnetic column cross-sectional area.

[0039] The present application has at least the following beneficial effects:

[0040] By controlling the alternating on-off of the first switch tube and the second switch tube, the current flowing through the excitation inductance flows in both directions, so that the first switch tube or the second switch tube is opened with zero voltage, the loss of the switching device is significantly reduced, and the overall efficiency of the converter is improved; The passive filter branch based on the coupling inductance can generate a filter current with opposite phase to the current ripple component of the excitation inductance, which can offset the ripple of the input current, greatly reduce the current stress on the fuel cell, and effectively prolong the service life. BRIEF DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used together with embodiments of the present application to explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0042] Figure 1 It is a circuit topology diagram of a traditional synchronous conduction mode Boost converter;

[0043] Figure 2 It is a circuit topology diagram of a non-isolated one-way Boost converter in one embodiment of the present application;

[0044] Figure 3 It is an equivalent cantilever model schematic diagram of a coupling inductance unit in one embodiment of the present application;

[0045] Figure 4 It is a winding structure schematic diagram in one embodiment of the present application;

[0046] Figure 5 It is a magnetic flux distribution schematic diagram of interleaved winding design in one embodiment of the present application;

[0047] Figure 6 It is a flow chart of a coupling inductance design method in one embodiment of the present application;

[0048] Figure 7 This is a schematic diagram of the simulation results of a non-isolated unidirectional Boost converter in one embodiment of this application. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Traditional methods typically employ methods such as Figure 1 The synchronous conduction mode Boost converter shown has a switching transistor ( and At the instants of switching on and off, the voltage and current on the converter exist simultaneously and are not zero, resulting in significant switching losses. These switching losses increase linearly with frequency, limiting the converter's operating frequency. Furthermore, the input current... Completely equal to inductor current The current rises when the switch is turned on and falls when it is turned off, exhibiting a sawtooth wave shape with a high ripple rate. For sensitive power sources like hydrogen fuel cells, the huge current ripple can cause fluctuations in the electrochemical reaction inside the fuel cell, accelerate the aging of the catalyst and proton exchange membrane, and reduce the service life of the hydrogen fuel cell.

[0051] To effectively improve the operating frequency of the converter and extend the service life of the hydrogen fuel cell, this invention provides a non-isolated unidirectional Boost converter and its coupling inductor design method. This method controls the alternating switching of the first and second switching transistors, enabling bidirectional current flow through the magnetizing inductor. This achieves zero-voltage turn-on of either the first or second switching transistor, significantly reducing switching device losses and improving the overall efficiency of the converter. Furthermore, by utilizing a passive filter branch based on the coupling inductor, a filter current with a phase opposite to the current ripple component of the magnetizing inductor can be generated, canceling the input current ripple and greatly reducing the current stress on the fuel cell, effectively extending its service life.

[0052] Example 1

[0053] like Figure 2 As shown, the present invention provides a non-isolated unidirectional boost converter, including an input power supply. First switching transistor Second switching transistor and output capacitor Its innovation lies in the introduction of a coupled inductor unit 21 and a passive filter branch 22.

[0054] Coupled inductor unit 21, whose primary winding serves as the magnetizing inductor of the converter. Directly participate Energy storage and transfer in the circuit; secondary winding and auxiliary capacitor of coupled inductor unit 21 This forms a passive filter branch 22 connected in series; where,

[0055] Passive filter branch 22 and input power supply in parallel;

[0056] The converter is configured to control the first switching transistor Second switching transistor The alternating switching on and off of the magnetizing inductor causes current to flow through it. The current flows bidirectionally, thereby enabling control of the first switching transistor. Or the second switching transistor Zero-voltage turn-on;

[0057] The passive filter branch 22 is configured to generate a connection with the magnetizing inductor through the coupling effect of the coupling inductor unit 21. The filter current is in phase with the current ripple component; the filter current and the current ripple component are superimposed to cancel the ripple of the input current.

[0058] In one feasible implementation, the coupled inductor unit 21 is integrated on an EE-type magnetic core using an interleaved winding structure; wherein the primary winding and the secondary winding are respectively wound on two side posts of the EE-type magnetic core.

[0059] In one feasible implementation, the equivalent cantilever model of the coupled inductor unit 21 is as follows: Figure 3 As shown, it includes parallel magnetizing inductors. and ideal transformer Among them, ideal transformer Secondary side and equivalent leakage inductance Series connection; passive filter branch 22 consists of an ideal transformer Equivalent leakage inductance and auxiliary capacitors The structure is as follows. The conversion relationship between the coupled inductor model and the cantilever model can be expressed as: .in, Indicates the original side's self-perception. Indicates the self-perception of the secondary side. Indicates the mutual inductance between the primary and secondary edges. This represents the coupling coefficient, used to quantify the degree of magnetic coupling between two inductors (or windings).

[0060] In one feasible implementation, the condition for canceling the input current ripple is: an ideal transformer turns ratio and excitation inductance , equivalent leakage inductance satisfy the relationship .

[0061] The derivation process of the condition for canceling the ripple of the input current is described below.

[0062] To ensure that the input current ripple is 0, that is, the AC component of the input current is 0, only the condition needs to be met:

[0063]

[0064] wherein, represents the amount of change of the primary side current per unit time, represents the amount of change of the secondary side current per unit time, represents the amount of change of the input current per unit time, represents the unit time.

[0065] The inductance energy storage formula is: .

[0066] From the inductance energy storage formula and the transformer turns ratio relationship, it can be obtained that: .

[0067] Simplifying it gives: .

[0068] In some other embodiments under the circuits of different transformers corresponding to different working conditions, different values can be selected according to experience, and then values are determined according to . At this time, the input current ripple can be . It should be noted that after adding the passive filter, the primary side inductance current is also affected by the secondary side current. To ensure that the primary side inductance current can still be negatively turned on to achieve the zero voltage turn-on condition, it is necessary to ensure that the equivalent value of the primary side inductance after adding the passive filter satisfies the inductance value selected to achieve the zero voltage turn-on. From the above formula, it can be obtained that: ; at this time, the primary side inductance current satisfies the required condition for realizing the zero voltage turn-on, and the input current ripple is eliminated.

[0069] In the embodiment of the application, the non-isolated unidirectional Boost type converter further comprises a control unit, and the control unit is configured to perform digital adaptive frequency modulation.

[0070] In the dead time, the junction capacitance of the off switch tube is discharged by the current of the excitation inductance , so that the body diode of the off switch tube is turned on; the off switch tube is the first switch tube or the second switch tube ;

[0071] During the conduction of the body diode, the switch tube corresponding to the body diode is turned on to realize zero-voltage turn-on.

[0072] According to the input voltage, the output voltage, the excitation inductance value and the preset negative peak value of the inductance current, the switching frequency of the next switching period is dynamically calculated and set to ensure that the excitation inductance current is negative at the beginning of the dead time.

[0073] Next, taking one complete switching period in the embodiment of the application as an example, the control process of the control unit is described, which specifically includes stages 1 to 4.

[0074] Stage 1, during the dead time before the first switch tube is turned on, the first switch tube and the second switch tube are kept off, and the current of the excitation inductance flows through the first switch tube , discharges the first switch tube through the energy of the excitation inductance , and until the drain-source voltage of the first switch tube drops to zero (at this time, the first switch tube is turned on, and the second switch tube is off), stage 2 is entered.

[0075] Stage 2, the first switch tube is turned on, because in stage 1, the drain-source voltage of the first switch tube has dropped to zero, so the first switch tube realizes zero-voltage turn-on. The voltage across the excitation inductance is the input voltage, and in this stage, the current of the excitation inductance will continuously increase from its minimum value to its maximum value, until the first switch tube is off, and stage 3 is entered.

[0076] Stage 3, the first switch tube is off, and the converter again enters the dead time, the first switch tube and the second switch tube are kept off, and the current of the excitation inductance flows through the second switch tube , and the forward current of the excitation inductance flows through the body diode of the second switch tube to discharge the junction capacitance, until the drain-source voltage of the second switch tube drops to zero (at this time, the second switch tube turn-on, first switch tube If the first switch tube is turned off (i.e., the first switch tube is in the off state), the converter enters phase 4.

[0077] turn-off, second switch tube The first switch tube is turned on during the conduction of the body diode, realizing zero-voltage turn-on. The magnetizing inductor has a voltage across it of the input voltage minus the output voltage, and the current of the magnetizing inductor continuously decreases from its maximum value to its minimum value until the moment when the second switch tube is turned off, at which time the converter enters the next switching period.

[0078] In an embodiment of the present application, after the end of the previous switching period, the control unit dynamically calculates and sets the switching frequency of the next switching period according to the input voltage, the output voltage, the value of the magnetizing inductor, and the preset negative peak value of the inductor current, to ensure that the current of the magnetizing inductor is negative at the beginning of the dead time.

[0079] In one possible implementation, the expression of the switching frequency is as follows:

[0080]

[0081] wherein, f represents the switching frequency, T represents the switching period, Ton represents the turn-on time of the switch tube, Toff represents the turn-off time of the switch tube, Vin represents the input voltage, Vout represents the output voltage, Ipeak represents the negative peak value of the inductor current.

[0082] Embodiment 2

[0083] To optimize the structure of the magnetic core and increase the coupling degree of the primary and secondary windings, the present application further provides a coupling inductor design method for the converter in embodiment 1. Specifically, the present application adopts an interleaved winding design, as shown in Figure 4 . Figure 4 wherein, and A1 and A2 represent the cross-sectional areas of the side magnetic columns and the middle magnetic column, the main winding on the two side magnetic columns is , and the interleaved winding is . For example, the blue line segment represents the primary winding, and the red line segment represents the secondary winding. On the left side magnetic column, the number of turns of the primary winding is , and the number of turns of the secondary winding is . The magnetic flux distribution based on the interleaved winding design provided by the present application is shown in Figure 5 , and it can be seen from Figure 5 that the magnetic flux distribution of the three magnetic columns under the interleaved structure is relatively uniform. ​

[0084] In an embodiment, the flow chart of the coupling inductance design method is shown in FIG. 6, which includes steps 61-65. Figure 6

[0085] In step 61, the electrical parameters are determined based on the input and output specifications of the transformer and the condition of canceling the input current ripple.

[0086] The electrical parameters include the turns ratio, the magnetizing inductance and the equivalent leakage inductance.

[0087] Specifically, the electrical parameters are determined based on the condition of canceling the input current ripple. The electrical parameters are determined to ensure that the zero voltage switching condition is met, i.e., the inductor current can achieve a sufficient negative peak.

[0088] In step 62, the magnetic fluxes of the magnetic columns of the magnetic core are calculated using the electrical parameters according to the magnetic flux superposition principle.

[0089] Specifically, the magnetic fluxes of the first side magnetic column, the second side magnetic column and the middle magnetic column are calculated using the following formulas:

[0090]

[0091] The magnetic fluxes of the first side magnetic column, the second side magnetic column and the middle magnetic column are calculated using the following formulas: wherein Np represents the number of turns of the primary winding, Ns represents the number of turns of the secondary winding, Ip represents the primary current, Is represents the secondary current, R1 represents the magnetic resistance of the first side magnetic column, R2 represents the magnetic resistance of the second side magnetic column, and Rm represents the magnetic resistance of the middle magnetic column.

[0092] In step 63, the magnetic resistances of the side columns and the middle column of the magnetic core are calculated using the magnetic fluxes according to the definitions of self-inductance and mutual inductance.

[0093] Specifically, the magnetic resistances of the side columns and the middle column of the magnetic core are calculated using the definitions of self-inductance and mutual inductance as follows:

[0094]

[0095]

[0096]

[0097] wherein Lp represents the primary self-inductance, Ls represents the secondary self-inductance, and M represents the mutual inductance between the primary and the secondary, with the negative sign indicating the opposite direction. ​​​​​​​​​​​​​

[0098] Step 64, according to the magnetic resistance and the cross-sectional area of the magnetic core, the required air gap length of each magnetic column is calculated.

[0099] It should be noted that the magnetic resistance of the magnetic core itself can be ignored compared with the magnetic resistance of air, so the magnetic resistance of each magnetic column is mainly determined by its air gap:

[0100]

[0101] wherein, represents the permeability of air, represents the air gap length of the first side magnetic column, represents the air gap length of the second side magnetic column, represents the air gap length of the middle magnetic column, represents the cross-sectional area of the side magnetic column, represents the cross-sectional area of the middle magnetic column. In the embodiment of the present application, EE type magnetic core is selected, wherein the cross-sectional area of the magnetic column is configured to be twice the cross-sectional area of the side magnetic column.

[0102] Step 65, according to the effective value of the current and the selected current density, the cross-sectional area of the wire and the required window area of the magnetic core are calculated, and the appropriate magnetic core type is selected by AP method to complete the winding of the primary winding and the secondary interleaved winding.

[0103] wherein, according to the effective value of the current and the selected current density, the cross-sectional area of the wire and the required window area of the magnetic core are calculated, including:

[0104] Through the calculation formula

[0105]

[0106] the cross-sectional area of the wire is obtained ; wherein, represents the effective value of the current, represents the current density;

[0107] Through the calculation formula

[0108]

[0109] the window area of the magnetic core is obtained . wherein, is the utilization coefficient of the window area, usually between 0.2~0.3.

[0110] Based on the above process, the product of the window area and the magnetic core area is obtained, and the value is:

[0111]

[0112] wherein, Indicates the cross-sectional area of the middle magnetic column, which determines how much magnetic flux the magnetic core can accommodate under a given magnetic flux density, Indicates the cross-sectional area of the side magnetic column, Indicates the input voltage of the converter, Indicates the on-duty ratio of the switch tube, Indicates the switching frequency, Indicates the maximum change in magnetic flux density during operation (peak to peak).

[0113] According to the estimated product and the operating frequency of the coupling inductance, select the appropriate material type of the coupling inductance magnetic core. The turns ratio of the coupling inductance can be calculated as follows: The voltage of the secondary side of the coupling inductance is half of the primary side, and the number of turns of the secondary side of the coupling inductance can be obtained.

[0114] Example 3

[0115] In this embodiment, a non-isolated unidirectional Boost type converter is constructed according to the schemes of Example 1 and Example 2, and simulation is performed, and the simulation results are shown in Figure 7 , Figure 7 The blue line in the figure represents the primary side current, the orange line represents the secondary side current, and the pink line represents the input current. It is not difficult to see that the slope of the primary side inductance current and the secondary side inductance current is equal in size and opposite in direction, and the obtained input current realizes zero ripple. The effectiveness of the non-isolated unidirectional Boost type converter provided by the scheme is effectively verified.

[0116] In summary, the non-isolated unidirectional Boost type converter provided by the present application controls the alternating on-off of the first switch tube and the second switch tube, so that the current flowing through the excitation inductance flows in both directions, thereby realizing zero voltage turn-on of the first switch tube or the second switch tube, significantly reducing the loss of the switching device, and improving the overall efficiency of the converter; The passive filter branch based on the coupling inductance can generate a filter current whose phase is opposite to that of the current ripple component of the excitation inductance, which can offset the ripple of the input current, greatly reducing the current stress on the fuel cell and effectively prolonging its service life.

[0117] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary and is not intended to limit the scope of protection of the present application to these examples; under the idea of the present application, the above embodiments or technical features in different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of one or more embodiments of the present application as described above. In order to be brief, they are not provided in detail.

[0118] It is intended that the embodiments of the application herein disclosed meet all the written requirements of the patent statutes and come within the judicial doctrines of equivalents and will not be construed to be limited to the embodiments shown and described and by the keeping within the spirit and scope of the embodiments of the application.

Claims

1. A non-isolated unidirectional boost type converter comprising an input power source, a first switching transistor, a second switching transistor, and an output capacitor, characterized by, The transformer further comprises: The coupling inductor unit has a primary winding serving as an excitation inductor of the transformer, and a secondary winding connected in series with an auxiliary capacitor to form a passive filter branch; The passive filter branch is connected in parallel with the input power supply; The transformer is configured to realize zero-voltage turn-on of the first switch tube or the second switch tube by controlling the alternating on-off of the first switch tube and the second switch tube, so that the current flowing through the excitation inductor flows bidirectionally; The passive filter branch is configured to generate a filter current opposite in phase to a current ripple component of the excitation inductor through the coupling effect of the coupling inductor unit; the filter current and the current ripple component are superimposed to offset the ripple of the input current; the non-isolated one-way Boost type transformer further comprises a control unit configured to perform digital adaptive frequency modulation, and the control unit is configured to: In the dead time, the current of the excitation inductor is used to discharge the junction capacitance of the off switch tube, so that the body diode of the off switch tube is turned on; the off switch tube is the first switch tube or the second switch tube; During the conduction of the body diode, the switch tube corresponding to the body diode is turned on to realize zero-voltage turn-on; According to the input voltage, the output voltage, the excitation inductor value and the preset inductor current negative peak value, the switching frequency of the next switching period is dynamically calculated and set to ensure that the current of the excitation inductor is negative at the beginning of the dead time; the expression of the switching frequency is: wherein, denotes the switching frequency, denotes the switching period, denotes the switch on time, denotes the switch off time, denotes the input voltage, denotes the output voltage, denotes the inductor current negative peak.

2. The non-isolated unidirectional Boost-type converter of claim 1, wherein, The coupling inductor unit adopts an interleaved winding structure integrated on an EE type magnetic core; wherein the primary winding and the secondary winding are wound on two side columns of the EE type magnetic core, respectively.

3. The non-isolated unidirectional Boost-type converter of claim 2, wherein, The equivalent cantilever model of the coupling inductor unit includes an excitation inductor and an ideal transformer in parallel; wherein the secondary side of the ideal transformer is connected in series with an equivalent leakage inductor; the passive filter branch is composed of the ideal transformer, the equivalent leakage inductor and the auxiliary capacitor.

4. The non-isolated unidirectional boost-type converter of claim 3, wherein, The condition for offsetting the ripple of the input current is: The ideal transformer turns ratio and the excitation inductance, the equivalent leakage inductance satisfy the relationship: ; wherein, represents the inductance value of the equivalent leakage inductance, represents the inductance value of the excitation inductance, represents the turns ratio of the ideal transformer.

5. A method for designing a coupled inductor for the transformer of any one of claims 1-4, wherein, It comprises: Determine electrical parameters based on the input and output specifications of the transformer and the condition for offsetting the ripple of the input current; The electrical parameters include the turns ratio, the value of the excitation inductor and the equivalent leakage inductor; According to the magnetic flux superposition principle, the magnetic flux of each magnetic column of the magnetic core is calculated by using the electrical parameters; According to the magnetic flux superposition principle, the magnetic flux of each magnetic column of the magnetic core is calculated by using the electrical parameters, which comprises: Through the calculation formula Obtaining the magnetic flux of the first side magnetic column, the second side magnetic column and the middle magnetic column 、 、 ; wherein, represents the number of turns of the primary winding, represents the number of turns of the secondary interlaced winding, represents the primary current, represents the secondary current, represents the magnetic resistance of the first side magnetic column, represents the magnetic resistance of the second side magnetic column, represents the magnetic resistance of the middle magnetic column; According to the definition of self-inductance and mutual inductance, the magnetic resistance of the side column and the middle column of the magnetic core is calculated by using the magnetic flux; According to the magnetic resistance and the cross-sectional area of the magnetic core, the required air gap length of each magnetic column is calculated; the cross-sectional area of the middle magnetic column is configured to be twice the cross-sectional area of the side magnetic column According to the current effective value and the selected current density, the cross-sectional area of the wire and the required window area of the magnetic core are calculated, and the appropriate magnetic core type is selected by the AP method to complete the winding of the primary winding and the secondary interleaved winding.

6. The coupled inductor design method of a non-isolated unidirectional Boost-type converter according to claim 5, wherein, According to the current effective value and the selected current density, the cross-sectional area of the wire and the required window area of the magnetic core are calculated, which comprises: Through the calculation formula obtaining the cross-sectional area of the conductor wire ; wherein denotes the current effective value, denotes the current density; Through the calculation formula Core window area ; Utilization factor of core window area, 0.2 to 0.3.

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