Passive balanced transient variable inductor structure of Buck converter

Abstract

The invention discloses a passive balanced transient variable inductor structure of a Buck converter, and aims to improve the dynamic response capability of the converter in a low-voltage large-current scene. The structure comprises a left magnetic column and a right magnetic column which are symmetrically arranged, a central column with an air gap, a main winding and an auxiliary winding, and a passive energy storage network consisting of a diode, an energy storage capacitor, an inductor and a bleeder resistor. When the load suddenly increases, the energy storage network generates pulsating current to excite the magnetic resistance of the left and right magnetic columns to increase, the inductance value is transiently reduced, and the dynamic response speed of the Buck converter is improved; and the inductance recovers the rated value after the load shedding is finished. Through the reverse winding design of the main winding and the auxiliary winding, the magnetic flux density balance of the left and right magnetic columns is ensured, and the magnetic core utilization rate is obviously improved. Compared with a traditional fixed inductor scheme, the method does not need active control, can remarkably shorten the voltage adjustment time, has the advantages of high frequency and high power density, and is suitable for scenes with strict dynamic performance requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic converters, in particular to a Buck converter passive balanced transient variable inductor structure. Background Art

[0002] In the field of power electronic converters, Buck converters are widely used in low-voltage, high-current scenarios such as cluster servers, digital product adapters, and CPU power supplies due to their simple structure and high efficiency. In these scenarios, the load current of electrical equipment often exhibits rapid and sudden changes, requiring Buck converters to have extremely strong dynamic response capabilities to avoid large fluctuations in output voltage or even power outages. However, traditional Buck converters generally use inductors with fixed inductance values, whose inductance characteristics cannot be dynamically adjusted with load changes. Output voltage can only be regulated through a single PWM control strategy, resulting in limited dynamic response speed. When the load suddenly increases, the inductive reactance of the fixed inductor hinders the rapid increase in current, resulting in a large drop in output voltage and a long adjustment time, making it difficult to meet the stringent power supply stability and speed requirements of modern electronic equipment.

[0003] The application of existing variable inductor technology in Buck converters is still in the exploratory stage. A typical solution is the self-excited, non-decoupled, balanced variable inductor, which adjusts the magnetic resistance by winding the core's center leg and controlling the air gap shape. However, this solution has significant drawbacks: First, the nonlinear magnetic resistance characteristics of the center leg air gap are difficult to accurately model, resulting in a limited inductance adjustment range and insufficient stability. Second, a single winding design cannot achieve balanced control of the magnetic flux density across each leg of the core, easily causing local core saturation, reducing core utilization and potentially leading to sudden changes in inductance or abnormal losses. Furthermore, such solutions typically rely on complex active control strategies to drive inductance adjustment, increasing circuit complexity and cost, and making them incompatible with the design trend towards higher frequencies and higher power densities.

[0004] With the development of technologies such as cloud computing and artificial intelligence, low-voltage, high-current scenarios are placing higher demands on the dynamic performance of Buck converters. Not only must output voltage adjustment time be shortened to microseconds during sudden load changes, but core volume optimization and energy conversion efficiency must also be balanced. The limitations of traditional fixed inductor solutions and existing variable inductor technologies are becoming increasingly prominent. A new structure that eliminates the need for active control, achieves core flux balancing, and allows for transient inductance adjustment is urgently needed to overcome the technical bottlenecks in Buck converter dynamic response and overall performance. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art. The present invention proposes a passive balanced transient variable inductor structure for a Buck converter. By designing the main winding and the auxiliary winding in reverse, the magnetic flux density of the left and right magnetic columns is balanced, thereby significantly improving the utilization rate of the magnetic core.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A Buck converter passive balanced transient variable inductor structure, characterized by comprising:

[0008] The magnetic core structure includes a left magnetic column, a right magnetic column, two center columns, an upper magnetic plate and a lower magnetic plate, wherein the left and right magnetic columns have no air gaps and the center column has an air gap;

[0009] The main windings are respectively wound on the central column, with the same winding direction and opposite to the auxiliary windings;

[0010] Auxiliary windings are respectively wound around the left and right magnetic poles, with the same winding direction and the same number of turns;

[0011] The energy storage network is composed of a diode, an energy storage capacitor, an inductor and a discharge resistor. The auxiliary winding is connected in series and connected to the energy storage network to generate a pulsating current to adjust the magnetic resistance when the load suddenly increases.

[0012] Furthermore, the main winding is wound counterclockwise, the auxiliary winding is wound clockwise, and the magnetic flux density of the left and right magnetic columns remains consistent.

[0013] Furthermore, in the energy storage network, the anode of the diode is connected to the input terminal of the auxiliary winding, the cathode is connected in series with the energy storage capacitor and inductor, and then to ground. A bleeder resistor is connected in parallel with the energy storage capacitor to release the capacitor energy and restore the capacitor voltage to a steady-state value after load shedding. The output terminal is connected to the input terminal of the auxiliary winding; the output terminal of the auxiliary winding is connected to the inductor. The input terminal of the main winding is connected to the source of the switching tube, and the output terminal is connected to the input terminal of the main winding; the output terminal of the main winding is connected to the anode of the buck output capacitor.

[0014] Furthermore, the air gap lengths of the central columns are the same and the cross-sectional areas are equal; the cross-sectional areas of the left and right magnetic columns are equal, and the cross-sectional areas of the upper and lower magnetic plates are equal.

[0015] Furthermore, the inductance of the inductor is smaller than the Buck inductance corresponding to the main winding, and the current generated by the inductor is smaller than the Buck inductor current.

[0016] Furthermore, the left and right magnetic columns and the upper and lower magnetic plates of the magnetic core constitute an auxiliary magnetic circuit. The magnetic flux path of the main winding passes through the air gap of the center column, and the magnetic flux path of the auxiliary winding only passes through the left and right magnetic columns and the upper and lower magnetic plates without air gaps, so as to adjust the magnetic resistance by changing the magnetic permeability.

[0017] Furthermore, the pulsating current generated by the energy storage network is a linearly rising current of fixed magnitude, which exists only in the loading period after the Buck converter load suddenly increases. After the loading is completed, the current returns to zero, achieving transient reduction and recovery of the inductance value.

[0018] Furthermore, the discharge resistor provides an energy discharge path for the energy storage capacitor, ensuring that after each load shedding, the capacitor voltage returns to a steady-state voltage, preparing for the next load shedding response.

[0019] Furthermore, the function of the inductor is to make the pulse current rise linearly when the energy storage capacitor is discharged, so as to stably adjust the magnetic flux density of the left and right magnetic columns.

[0020] Compared with the prior art, the present invention adopts the above technical solution and has the following beneficial effects:

[0021] (1) The present invention proposes a passive balanced transient variable inductance structure for a Buck converter. When the load is cut, the output current IAUX of the energy storage network saturates the magnetic circuit around the core, reducing the inductance, thereby greatly improving the dynamic response speed of the Buck converter.

[0022] (2) The magnetic flux density of the left and right magnetic columns is always balanced, which improves the utilization rate of the magnetic core and significantly increases the inductance variation range.

[0023] (3) The inductance is adaptively reduced when the Buck converter switches to a heavy load, and the inductance value returns to the rated value after the load is cut off. While improving the dynamic response speed, the output ripple and efficiency under heavy load are guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a passive balanced transient variable inductor Buck converter proposed by the present invention;

[0025] Figure 2 This is the magnetic circuit diagram of the Buck variable inductor structure used in the present invention;

[0026] Figure 3 This is a schematic diagram of the Buck variable inductor structure used in the present invention;

[0027] Figure 4 This is the ANSYS simulation model diagram of the Buck variable inductor structure used in the present invention;

[0028] Figure 5 This is the ANSYS Twin Builder external circuit simulation model diagram of the Buck variable inductor structure used in the present invention;

[0029] Figure 6 1 is a graph showing the inductance variation of the auxiliary windings MAIN1 and MAIN2 according to an embodiment of the present invention;

[0030] Figure 7 This is a load shedding output voltage waveform diagram in an embodiment of the present invention;

[0031] Figure 8 2 is a diagram showing the magnetic flux density distribution of the left and right columns of the Buck variable inductor structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] A Buck converter passive balanced transient variable inductor structure, the structural diagram of which is shown in FIG. Figure 1 As shown, it is characterized by comprising:

[0034] A magnetic core structure comprising a left magnetic column (l_AUX1), a right magnetic column (l_AUX2), two center columns (l_M1, l_M2), an upper magnetic plate (l_UP), and a lower magnetic plate (l_DOWN), wherein the left and right magnetic columns have no air gaps, and the center column has an air gap (l_g);

[0035] Main windings (MAIN1, MAIN2), respectively wound on the central column, with the same winding direction and opposite to the auxiliary winding;

[0036] Auxiliary windings (AUX1, AUX2) are respectively wound around the left and right magnetic poles, with the same winding direction and the same number of turns;

[0037] The energy storage network is composed of a diode (D1), an energy storage capacitor (C1), an inductor (L1) and a bleeder resistor (R1). The auxiliary winding is connected in series and connected to the energy storage network to generate a pulsating current (IAUX) to adjust the magnetic resistance when the load suddenly increases.

[0038] Furthermore, the main windings (MAIN1, MAIN2) are wound counterclockwise, the auxiliary windings (AUX1, AUX2) are wound clockwise, and the magnetic flux densities of the left and right magnetic columns (l_AUX1, l_AUX2) remain consistent.

[0039] The magnetic circuit diagram is as follows Figure 2 shown.

[0040] Furthermore, in the energy storage network, the anode of the diode (D1) is connected to the input terminal of the auxiliary winding (AUX1), and the cathode is connected in series with the energy storage capacitor (C1) and the inductor (L1) and then grounded. The discharge resistor (R1) is connected in parallel with the energy storage capacitor (C1) to release the capacitor energy and restore the capacitor voltage to a steady-state value (VC1s) after the load is cut off; the output terminal is connected to the input terminal of the auxiliary winding (AUX2); the output terminal of the auxiliary winding (AUX2) is connected to the inductor (L1). The input terminal of the main winding (MAIN1) is connected to the source of the switch tube (Q1), and the output terminal is connected to the input terminal of the main winding (MAIN2); the output terminal of the main winding (MAIN2) is connected to the anode of the Buck output capacitor. Figure 3 shown.

[0041] Furthermore, the air gap length (l_g) of the central column (l_M1, l_M2) is the same, and the cross-sectional area (A_MAIN1, A_MAIN2) is equal; the cross-sectional area (A_AUX1, A_AUX2) of the left and right magnetic columns is equal, and the cross-sectional area (A_UP, A_DOWN) of the upper and lower magnetic plates is equal.

[0042] Furthermore, the number of turns (N_edge) of the auxiliary winding (AUX1, AUX2) and the number of turns (N_MAIN1, N_MAIN2) of the main winding (MAIN1, MAIN2) are both 16 turns, and the inductance value of the inductor (L1) is smaller than the Buck inductance value corresponding to the main winding, and the current generated by it is smaller than the Buck inductor current.

[0043] Furthermore, the left and right magnetic columns (l_AUX1, l_AUX2) of the magnetic core and the upper and lower magnetic plates (l_UP, l_DOWN) constitute an auxiliary magnetic circuit. The magnetic flux path of the main winding passes through the air gap of the center column, and the magnetic flux path of the auxiliary winding only passes through the left and right magnetic columns and upper and lower magnetic plates without air gaps, so as to adjust the magnetic resistance by changing the magnetic permeability.

[0044] Furthermore, the pulsating current (IAUX) generated by the energy storage network is a linearly rising current of fixed magnitude, which exists only in the loading period after the Buck converter load suddenly increases. After the loading is completed, the current returns to zero, achieving transient reduction and recovery of the inductance value.

[0045] Furthermore, the discharge resistor (R1) provides an energy discharge path for the energy storage capacitor (C1), ensuring that after each load shedding, the voltage of the capacitor C1 returns to the steady-state voltage (VC1s) to prepare for the next load shedding response.

[0046] Furthermore, the inductor (L1) functions to linearly increase the pulse current (IAUX) when the energy storage capacitor (C1) is discharged, so as to stably adjust the magnetic flux density of the left and right magnetic columns.

[0047] Example: In order to verify the validity of the present invention, a simulation is performed with a set of Buck operating parameters in Table 1 and the variable inductor structure parameters in Table 2.

[0048] Table 1 Buck operating parameters

[0049]

[0050]

[0051] Table 2 Self-excited balanced Buck variable inductor structure parameters

[0052]

[0053] ANSYS is used to build a self-excited balanced Buck variable inductance structure simulation model proposed in this invention, such as Figure 3 As shown; use ANSYS Twin Builder to build an external circuit model, as shown Figure 4 As shown; ANSYS Twin Builder external circuit simulation model is as follows Figure 5 shown.

[0054] When the output power of the Bcuk converter jumps from 50W to 100W, the inductance change curves of the auxiliary windings AUX1, AUX2, MAIN1, and MAIN2 of the Buck variable inductance structure adopted by the present invention are as follows: Figure 6 shown.

[0055] The Buck inductance before load shedding is calculated as follows:

[0056] L f =2m1

[0057] The Buck inductance after load shedding is calculated as follows:

[0058] L f =2m4

[0059] The Buck inductance value before load shedding is 30.2μH. At the moment of load shedding, the Buck inductance value follows I AUX After the load is cut off, the Buck inductor value recovers to 30.2μH.

[0060] Under the same electrical parameters, the fixed inductance Buck converter and the Buck variable inductance structure used in the present invention are shown in the following figure: Figure 7 shown.

[0061] After load shedding, the voltage adjustment time of the Buck converter with variable inductance is 700 μs, while the voltage adjustment time of the fixed inductance Buck converter is 2000 μs. Therefore, the method proposed in this invention effectively improves the dynamic performance of the Buck converter.

[0062] The Buck variable inductor structure proposed by the present invention has the following distribution of magnetic flux density on the left and right columns: Figure 8 shown.

[0063] It can be seen that the magnetic flux density deviation between the left and right magnetic columns is controlled within 1%, which effectively improves the utilization rate of the magnetic core.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Buck converter passive balanced transient variable inductor structure, characterized in that: include: The magnetic core structure includes a left magnetic column, a right magnetic column, two center columns, an upper magnetic plate and a lower magnetic plate, wherein the left and right magnetic columns have no air gaps and the center column has an air gap; The main windings are respectively wound on the central column, with the same winding direction and opposite to the auxiliary windings; Auxiliary windings are respectively wound around the left and right magnetic poles, with the same winding direction and the same number of turns; The energy storage network is composed of a diode, an energy storage capacitor, an inductor and a discharge resistor. The auxiliary winding is connected in series and connected to the energy storage network to generate a pulsating current to adjust the magnetic resistance when the load suddenly increases.

2. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: The main winding is wound counterclockwise, the auxiliary winding is wound clockwise, and the magnetic flux density of the left and right magnetic columns remains consistent.

3. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: In the energy storage network, the anode of the diode is connected to the input terminal of the auxiliary winding, the cathode is connected in series with the energy storage capacitor and the inductor and then to ground, and the bleeder resistor is connected in parallel with the energy storage capacitor to release the capacitor energy after the load shedding is completed and to restore the capacitor voltage to a steady-state value; The output terminal is connected to the auxiliary winding input terminal; The auxiliary winding output terminal is connected to the inductor, the main winding input terminal is connected to the source of the switch tube, and the output terminal is connected to the main winding input terminal; The main winding output terminal is connected to the anode of the Buck output capacitor.

4. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: The air gap lengths of the central columns are the same and the cross-sectional areas are equal; the cross-sectional areas of the left and right magnetic columns are equal, and the cross-sectional areas of the upper and lower magnetic plates are equal.

5. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: The inductance of the inductor is smaller than the Buck inductance corresponding to the main winding, and the current generated by the inductor is smaller than the Buck inductor current.

6. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: The left and right magnetic columns and the upper and lower magnetic plates of the magnetic core form an auxiliary magnetic circuit. The magnetic flux path of the main winding passes through the air gap of the center column, and the magnetic flux path of the auxiliary winding only passes through the left and right magnetic columns and the upper and lower magnetic plates without air gaps, so as to adjust the magnetic resistance by changing the magnetic permeability.

7. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: The pulsating current generated by the energy storage network is a linearly rising current of fixed magnitude, which exists only during the loading period after the Buck converter load suddenly increases. After the loading is completed, the current returns to zero, achieving a transient reduction and recovery of the inductance value.

8. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: The function of the discharge resistor is to provide an energy discharge path for the energy storage capacitor, ensuring that after each load shedding, the capacitor voltage returns to a steady-state voltage to prepare for the next load shedding response.

9. The Buck converter passive balanced transient variable inductor structure according to claim 1, characterized in that: The function of the inductor is to make the pulse current rise linearly when the energy storage capacitor is discharged, so as to stably adjust the magnetic flux density of the left and right magnetic columns.

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