A hybrid architecture BUCK_DC-DC step-down converter

Abstract

The present invention belongs to the field of integrated circuit technology, and specifically relates to a BUCK_DC‑DC buck converter with a hybrid architecture. The buck converter of the present invention includes 12 power switches, 5 switch capacitors, two switch inductors and one output capacitor, assisted by a control system and a drive system; the present invention utilizes switch capacitors to reduce the voltage pressure of the input voltage on the power switch, while utilizing switch inductors to provide output current capability, and utilizes mode control to realize the conversion of high-voltage input voltage into a low-voltage output with high conversion efficiency, high power density, and strong load capacity. The present invention uses a power switch with a lower withstand voltage to realize high-voltage input conversion, greatly reducing the size of the power switch, reducing the loss of the power switch, and improving its conversion efficiency; the hybrid architecture is adopted, which can greatly reduce the inductance value and improve the power density of the system. The present invention solves the problems faced by traditional half-bridge BUCK_DC‑DC in high-voltage input and low-voltage output, and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and in particular relates to a BUCK_DC-DC step-down converter. Background Art

[0002] The rapid development of new energy vehicles, 5G communications, and data centers has significantly increased demand for high-voltage input, high-conversion-ratio, and high-power-density switching power supplies, such as those with 12V, 24V, and even 48V inputs. Furthermore, continuous advancements in semiconductor manufacturing processes have reduced load power supply voltages to 1V or even below. To bridge the significant voltage gap between the input power rail and the terminal module, high-step-down-ratio buck power converters are crucial.

[0003] Traditional half-bridge buck DC-DC converters have gained widespread adoption due to their simple topology and ease of control, offering immediate benefits in efficiency, switching frequency, and cost. However, the advantages of the traditional half-bridge structure diminish rapidly when the input voltage is significantly greater than the output voltage. First, to achieve a high conversion ratio, the on-time of the half-bridge buck DC-DC converter must be significantly shortened, as this is determined by the ratio of the output voltage to the input voltage. To achieve such a short on-time, the feedback control loop and the drive time of the power transistor must be reduced accordingly. Furthermore, to accommodate rising input voltages, larger power switches must be used to withstand higher device voltages, which inevitably results in longer drive delays. Second, for high step-down ratios, the low-side power switch of a half-bridge buck converter is on for the majority of each switching cycle, significantly increasing its conduction losses. Consequently, its size must be significantly larger than that of the high-side power switch, significantly increasing switching losses and complicating the trade-offs between gate drive, dead-time control, and switching noise control. However, in the half-bridge BUCK_DC-DC step-down converter, when the power input voltage V IN Much higher than the output voltage V OUT First, in order to achieve a large voltage conversion ratio, the high-side power switch on-time t of the half-bridge BUCK_DC-DC buck converter must be greatly shortened, which is related to V OUT / V IN In order to achieve a short on-time, the propagation delay caused by the power transistor, gate driver, and feedback control loop must be reduced accordingly. However, on the other hand, in order to adapt to the increasing V IN , a larger power transistor must be used to maintain a high breakdown voltage, which results in a longer delay. OUT / V INDue to the defined high step-down ratio, the low-voltage side power switch of a half-bridge buck DC-DC step-down converter is on for most of each switching cycle, significantly increasing its conduction losses. Consequently, its size must be significantly larger than that of the high-voltage side, leading to a significant increase in switching losses and further complicating the design trade-offs between gate drive, dead-time control, and switching noise control. Finally, a high switching frequency helps reduce the size of power passive components, particularly inductors, thereby achieving higher power density. However, as the switching frequency increases further, switching losses also increase significantly, placing higher demands on internal control delays and drivers. Summary of the Invention

[0004] An object of the present invention is to provide a BUCK_DC-DC step-down converter with a hybrid architecture to overcome the shortcomings of the prior art.

[0005] The hybrid architecture BUCK_DC-DC step-down converter provided by the present invention includes several power switches, five switched capacitors, and two switched inductors. The present invention utilizes switched capacitors to reduce the voltage pressure of the input voltage on the power switches, while utilizing switched inductors to provide output current capability. Mode control, including but not limited to a voltage mode or current mode based on pulse width control, a voltage mode or current mode based on constant on-time control, or a voltage mode based on ripple control, is utilized to convert a high-voltage input voltage into a low-voltage output with high conversion efficiency, high power density, and strong load capacity.

[0006] The hybrid architecture BUCK_DC-DC step-down converter provided by the present invention specifically includes: twelve power switches, five switch capacitors, two switch inductors, and one output capacitor; assisted by a control system and a drive system; V IN is the input terminal, V OUT is the output terminal, and GND is the ground.

[0007] The input terminal is connected to the drain of the first power switch, and the source of the first power switch is connected to the positive electrode of the first switch capacitor that stores two-thirds of the input voltage, so that the first power switch only needs to withstand one-third of the input voltage pressure;

[0008] The source of the first power switch is connected to the drain of the second power switch, and the source of the second power switch is connected to the positive electrode of the second switch capacitor that stores one-third of the input voltage, so that the second power switch only needs to withstand one-third of the input voltage pressure;

[0009] The source of the second power switch is connected to the drain of the third power switch, and the source of the third power switch is connected to the positive electrode of the third switch capacitor that stores three-twelfths of the input voltage, so that the third power switch only needs to withstand one-twelfth of the input voltage pressure;

[0010] The source of the third power switch is connected to the drains of the fourth power switch, the fifth power switch, and the eighth power switch. The source of the fourth power switch is connected to the negative electrode of the second switch capacitor and the drain of the sixth power switch. The fourth power switch only needs to withstand one-third of the input voltage pressure.

[0011] The source of the fifth power switch is connected to the negative electrode of the first switch capacitor and the drain of the seventh power switch, and it only needs to withstand one-third of the input voltage pressure;

[0012] The sources of the sixth power switch and the seventh power switch are connected to the ground GND, and they only need to withstand one-third of the input voltage pressure;

[0013] The source of the eighth power switch is connected to the positive electrode of the fourth switch capacitor storing two-twelfths of the input voltage and the drain of the ninth power switch, and it only needs to withstand the pressure of one-twelfth of the input voltage;

[0014] The source of the ninth power switch is connected to the drain of the tenth power switch and the positive electrode of the fifth switch capacitor that stores one-twelfth of the input voltage, and the fifth switch capacitor only needs to withstand one-twelfth of the input voltage pressure;

[0015] The source of the tenth power switch is connected to the drain of the twelfth power switch and the input of the second switch inductor, and only needs to withstand one-twelfth of the input voltage pressure;

[0016] The drain of the eleventh power switch is connected to the third switch capacitor, the negative electrode of the fifth switch capacitor and the input stage of the first switch inductor, and only needs to withstand one-twelfth of the input voltage pressure;

[0017] The drain of the twelfth power switch is connected to the negative electrode of the fourth switch capacitor and the input electrode of the second switch inductor, and the source is grounded GND. The twelfth power switch only needs to withstand one-twelfth of the input voltage pressure.

[0018] The output electrodes of the first switching inductor and the second switching inductor are both connected to the positive electrode of the load capacitor to provide charge to the load; the gates of the twelve power switches are connected to the drive system, which drives the power switches separately according to the control system. The control system determines the corresponding power switch control by sampling the input voltage, output voltage and inductor current information, and performs the driving task through the drive system.

[0019] In the present invention, due to the use of five switching capacitors, the inductive freewheeling switches with the largest power loss, namely the eleventh power switch and the twelfth power switch, only need to withstand a voltage pressure of one twelfth of the input voltage. Even when the input voltage reaches 48V or even 60V, only a 5V low-voltage switch is needed, thereby achieving lower conduction loss and switching loss. Because the product of the gate oxide capacitance and the on-resistance per unit area of the low-voltage power switch is much smaller than that of the high-voltage switch, the system conversion efficiency can be effectively improved, especially in applications with a large step-down ratio, such as 48V input to 1V output, or 60V input to 1V output; at the same time, due to the use of a hybrid dual-switch inductor structure, the equivalent switch conduction time of the first to sixth power switches can be increased by up to 12 times, which greatly reduces the requirements for the delay time of the control system and the drive system, and further improves its conversion efficiency and power density.

[0020] The hybrid-architecture buck-dc-dc step-down converter provided by the present invention can use power switches with lower voltage resistance to achieve high-voltage input conversion, thereby significantly reducing the size of the power switches, reducing the driving losses of the power switches, and improving conversion efficiency. Furthermore, due to the hybrid architecture, the voltage of the two inductor input poles is reduced from the input voltage of the traditional half-bridge to one-twelfth of the input voltage. Even at a high-voltage input of 48V or 60V, the inductor freewheeling switches, namely the eleventh and twelfth power switches, can use 5V low-voltage switches, which can greatly reduce the switching and conduction losses of the freewheeling diode. At the same time, the equivalent switching frequency is increased twelvefold, which can significantly reduce the inductance value, thereby improving the power density of the system. This invention solves the problems existing in the traditional half-bridge buck-dc-dc architecture when applied to high step-down ratios and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the hybrid architecture BUCK_DC-DC step-down converter of the present invention.

[0022] Figure 2 This is a schematic diagram of the first phase in a six-phase complete control sequence in a buck converter and a schematic diagram of the first phase in a twelve-phase complete control sequence.

[0023] Figure 3 Schematic diagram of the second, fourth and sixth phases in the complete six-phase control sequence of the buck converter.

[0024] Figure 4 This is a schematic diagram of the third phase in the six-phase complete control sequence of the buck converter and a schematic diagram of the fifth phase in the twelve-phase complete control sequence.

[0025] Figure 5 This is a schematic diagram of the fifth phase in a six-phase complete control sequence of a buck converter and a schematic diagram of the ninth phase in a twelve-phase complete control sequence.

[0026] Figure 6 A schematic diagram of the drive system.

[0027] Figure 7 This is a structural diagram of the control system.

[0028] Figure 8 Schematic diagram of the second, sixth, and tenth phases in the complete twelve-phase control sequence of the buck converter.

[0029] Figure 9 Schematic diagram of the third, seventh, and eleventh phases in the twelve-phase complete control sequence of the buck converter.

[0030] Figure 10 Schematic diagram of the fourth, eighth, and twelfth phases in the twelve-phase complete control sequence of the buck converter. DETAILED DESCRIPTION

[0031] The present invention will be described in more detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, rather than all of the components.

[0032] Many specific details of the present invention, such as control timing and techniques, are described below to provide a clearer understanding of the present invention. However, as will be appreciated by those skilled in the art, the present invention may be implemented without these specific details.

[0033] The structural diagram of the BUCK_DC-DC step-down converter of the hybrid architecture of the present invention is as follows: Figure 1 As shown:

[0034] The buck converter 100 includes twelve power switches with different voltage requirements, five switch capacitors storing different voltages, two identical switch inductors, and an output capacitor; the drive system 200 includes dead-zone control, a level shift circuit, and a drive circuit to achieve fast opening and closing of the twelve power switches; the control system 300 includes output voltage sampling, inductor current sampling, error judgment and comparison, timing generation circuit, etc.

[0035] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the first phase power switch control schematic diagram in the six-phase sequential control, as shown in FIG. Figure 2 As shown, where:

[0036] The first power switch, the fifth power switch, the sixth power switch, the ninth power switch, and the twelfth power switch are turned on; the second power switch, the third power switch, the fourth power switch, the seventh power switch, the eighth power switch, the tenth power switch, and the eleventh power switch are turned off; the input voltage charges the first switch inductor through the first power switch, the first switch capacitor, the fifth power switch, and the third switch capacitor, while the fourth switch capacitor charges the first switch inductor through the ninth power switch and the fifth switch capacitor; and the second inductor switch is discharged through the twelfth power switch.

[0037] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the second, fourth and sixth phase power switch control schematic diagram of the six-phase timing control, as shown in FIG. Figure 3 As shown, where:

[0038] The fifth power switch, the sixth power switch, the eighth power switch, the tenth power switch, and the eleventh power switch are turned on; while the first power switch, the second power switch, the third power switch, the fourth power switch, the fifth power switch, the ninth power switch, and the twelfth power switch are turned off; the third switch capacitor charges the second switch inductor through the eighth power switch and the fourth switch capacitor, while the fifth switch capacitor charges the second switch inductor through the tenth power switch and the eleventh power switch; and the first switch inductor is discharged by freewheeling through the eleventh power switch.

[0039] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the third phase power switch control schematic diagram in the six-phase sequential control, as shown in FIG. Figure 4 As shown, where:

[0040] The second power switch, the fourth power switch, the seventh power switch, the ninth power switch, and the twelfth power switch are turned on; while the first power switch, the third power switch, the fifth power switch, the sixth power switch, the eighth power switch, the tenth power switch, and the eleventh power switch are turned off; the first switch capacitor charges the first switch inductor through the seventh power switch, the second power switch, the second switch capacitor, the fourth power switch, and the third switch capacitor, while the fourth switch capacitor charges the first switch inductor through the ninth power switch and the fifth switch capacitor; and the second switch inductor is discharged through the twelfth power switch.

[0041] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the fifth phase power switch control schematic diagram of the six-phase timing control, as shown in FIG. Figure 5 As shown, where:

[0042] The third power switch, the sixth power switch, the seventh power switch, the ninth power switch, and the twelfth power switch are turned on; the first power switch, the second power switch, the fourth power switch, the fifth power switch, the eighth power switch, the tenth power switch, and the eleventh power switch are turned off; the second switch capacitor charges the first switch inductor through the sixth power switch, the third power switch, and the third switch capacitor, while the fourth power switch capacitor charges the first switch inductor through the ninth power switch and the fifth switch capacitor; and the second switch inductor is discharged in a continuous current manner through the twelfth power switch.

[0043] The structural diagram of the drive system 200 in the present invention is as follows: Figure 6 As shown, the driving system consists of dead zone control, level shifting and driving circuits. Since the driving system is not the focus of the present invention, it is illustrated by a functional frame.

[0044] The structural diagram of the control system 300 in the present invention is as follows: Figure 7 As shown, the control system consists of output voltage sampling, inductor current sampling, error judgment and comparison, and control timing generation. Since the drive system is not the focus of the present invention, it is illustrated by a functional frame.

[0045] For the BUCK_DC-DC step-down converter of the hybrid architecture of the present invention, its twelve-phase control timing is as follows:

[0046] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the first phase power switch control schematic diagram in the twelve-phase sequential control, as shown in FIG. Figure 2 As shown, the switch control sequence and the first phase power switch control in the six-phase sequence control are shown in FIG. Figure 1 Sample.

[0047] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the second, sixth and tenth phase power switch control schematic diagram in the twelve-phase timing control, as shown in FIG. Figure 8 As shown, where:

[0048] The sixth power switch, the seventh power switch, the eighth power switch, and the eleventh power switch are turned on; while the first power switch, the second power switch, the third power switch, the fourth power switch, the fifth power switch, the ninth power switch, the tenth power switch, and the twelfth power switch are turned off; the third switch capacitor charges the second switch inductor through the eleventh power switch, the eighth power switch, and the fourth switch capacitor, while the first switch inductor continues current through the eleventh power switch.

[0049] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the third, seventh and eleventh phase power switch control schematic diagram in the twelve-phase sequential control, as shown in FIG. Figure 9 As shown, where:

[0050] The sixth power switch, the seventh power switch, the eighth power switch, the ninth power switch, and the twelfth power switch are turned on; while the first power switch, the second power switch, the third power switch, the fourth power switch, the fifth power switch, the eighth power switch, the tenth power switch, and the eleventh power switch are turned off; the fourth switch capacitor charges the first switch inductor through the twelfth power switch, the ninth power switch, and the fifth switch capacitor, while the second switch inductor continues current through the twelfth power switch.

[0051] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the schematic diagram of the fourth, eighth and twelfth phase power switch control in the twelve-phase sequential control, as shown in FIG. Figure 10 As shown. Among them:

[0052] The sixth power switch, the seventh power switch, the tenth power switch, and the eleventh power switch are turned on; while the first power switch, the second power switch, the third power switch, the fourth power switch, the fifth power switch, the eighth power switch, the ninth power switch, and the twelfth power switch are turned off; the fifth switch capacitor charges the second switch inductor through the eleventh power switch and the tenth power switch, while the first switch inductor continues current through the eleventh power switch.

[0053] The hybrid architecture BUCK_DC-DC buck converter of the present invention is based on the fifth phase power switch control schematic diagram in the twelve-phase sequential control, as shown in FIG. Figure 4 As shown, the switch control sequence and the third phase power switch control in the six-phase sequence control are shown in FIG. Figure 1 Sample.

[0054] The hybrid architecture BUCK_DC-DC step-down converter of the present invention is based on the ninth phase power switch control schematic diagram in the twelve-phase sequential control, as shown in FIG. Figure 5 Abbreviation, switch control sequence and fifth phase power switch control in six-phase sequence control Figure 1 Sample.

Claims

1. A hybrid architecture BUCK_DC-DC step-down converter, characterized in that: It includes several power switches, five switching capacitors and two switching inductors. The switching capacitors are used to reduce the voltage pressure of the input voltage on the power switches, while the switching inductors are used to provide output current capacity. Utilize mode control, including voltage mode or current mode control based on pulse width control, voltage mode or current mode control based on constant on-time control, or voltage mode control based on ripple control, to achieve conversion of high voltage input voltage to low voltage output with high conversion efficiency, high power density, and strong load capacity; Specifically including: twelve power switches, five switch capacitors, two switch inductors, one output capacitor; assisted by a control system and a drive system; among which: The input terminal is connected to the drain of the first power switch, and the source of the first power switch is connected to the positive electrode of the first switch capacitor that stores two-thirds of the input voltage, so that the first power switch is only subjected to one-third of the input voltage pressure; The source of the first power switch is connected to the drain of the second power switch, and the source of the second power switch is connected to the positive electrode of the second switch capacitor storing one-third of the input voltage, so that the second power switch is only subjected to one-third of the input voltage pressure; The source of the second power switch is connected to the drain of the third power switch, and the source of the third power switch is connected to the positive electrode of the third switch capacitor storing three-twelfths of the input voltage, so that the third power switch is only subjected to one-twelfth of the input voltage pressure; The source of the third power switch is connected to the drains of the fourth power switch, the fifth power switch, and the eighth power switch. The source of the fourth power switch is connected to the negative electrode of the second switch capacitor and the drain of the sixth power switch. The fourth power switch only withstands one-third of the input voltage pressure. The source of the fifth power switch is connected to the negative electrode of the first switch capacitor and the drain of the seventh power switch, and only withstands one-third of the input voltage pressure; The sources of the sixth power switch and the seventh power switch are connected to the ground GND, and only withstand one-third of the input voltage pressure; The source of the eighth power switch is connected to the positive electrode of the fourth switch capacitor storing two-twelfths of the input voltage and the drain of the ninth power switch, and it only withstands the pressure of one-twelfth of the input voltage; The source of the ninth power switch is connected to the drain of the tenth power switch and the positive electrode of the fifth switch capacitor that stores one-twelfth of the input voltage, and the fifth switch capacitor only withstands one-twelfth of the input voltage pressure; The source of the tenth power switch is connected to the drain of the twelfth power switch and the input of the second switch inductor, and only withstands one-twelfth of the input voltage pressure; The drain of the eleventh power switch is connected to the third switch capacitor, the negative electrode of the fifth switch capacitor and the input stage of the first switch inductor, and only withstands one-twelfth of the input voltage pressure; The drain of the twelfth power switch is connected to the negative electrode of the fourth switch capacitor and the input electrode of the second switch inductor, and the source is grounded GND. The twelfth power switch only withstands one-twelfth of the input voltage pressure. The output electrodes of the first switching inductor and the second switching inductor are both connected to the positive electrode of the load capacitor to provide charge to the load.

2. The hybrid architecture BUCK_DC-DC step-down converter according to claim 1, characterized in that: The gates of the twelve power switches are connected to the drive system, which drives the power switches separately according to the control system. The control system determines the corresponding power switch control by sampling the input voltage, output voltage and inductor current information, and performs the driving task through the drive system.

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