Step-down circuit and power supply device

Abstract

The present application provides a step-down circuit and a power supply device, wherein the step-down circuit includes a voltage input port, a voltage output port, a first step-down unit, a second step-down unit, and a gating unit. In the charging stage, the gating unit connects the first inductor to the voltage input port, and connects the second inductor to both ends of the first capacitor, and the power supply voltage input to the voltage input port charges the first inductor, the first capacitor, the second inductor, and the second capacitor, and outputs to the voltage output port at the same time; in the discharging stage, the gating unit disconnects the first inductor from the voltage input port, and connects the second inductor to both ends of the second capacitor, the first inductor and the second inductor are discharged, and the first capacitor and the second capacitor are freewheeling to output to the voltage output port; wherein the output voltage of the voltage output port is equal to the voltage difference between both ends of the second capacitor. The present application can effectively reduce the voltage stress of electronic components.

Description

Technical Field

[0001] The present application relates to the technical field of power electronic conversion, and in particular to a step-down circuit and a power supply device having the step-down circuit. Background Art

[0002] At present, various types of power electronic conversion circuits are widely used in various fields. According to their topological structures, they can be divided into buck circuits (BUCK), boost circuits (BOOST), and buck-boost circuits (BUCK-BOOST). Among them, with the development of the economy and society, many electrical equipment requires low-voltage, high-current power supply equipment to power them. Therefore, the AC mains power is usually rectified directly and then needs to pass through a buck circuit with high buck capability to meet the application requirements. However, the electronic components in such buck circuits often need to withstand greater voltage stress. Therefore, how to effectively reduce the voltage stress of the electronic components in the buck circuit has become a problem that needs to be considered. Summary of the invention

[0003] The present application provides a step-down circuit and a power supply device, which can effectively reduce the voltage stress of electronic components in the step-down circuit.

[0004] In a first aspect, a step-down circuit is provided, the step-down circuit comprising a voltage input port, a voltage output port, a first step-down unit, a second step-down unit and a gating unit. The voltage input port is used to input a power supply voltage; the voltage output port comprises a positive output terminal and a negative output terminal; the first step-down unit comprises a first inductor and a first capacitor, the first inductor is connected to the first capacitor, and one end of the first inductor not connected to the first capacitor is selectively connected to the voltage input port, and one end of the first capacitor not connected to the first inductor is connected to the positive output terminal; the second step-down unit comprises a second inductor and a second capacitor, the second inductor is connected to the second capacitor, and the second inductor is selectively connected to both ends of the first capacitor or to both ends of the second capacitor, and the second capacitor is connected between the positive output terminal and the negative output terminal; the gating unit is used to connect or disconnect the first inductor from the voltage input port, and connect the second inductor to both ends of the first capacitor. end or connected to the two ends of the second capacitor; wherein the step-down circuit includes a charging stage and a discharging stage; in the charging stage, the gating unit connects the first inductor to the voltage input port, and connects the second inductor to the two ends of the first capacitor, the power supply voltage input by the voltage input port charges the first inductor, the first capacitor, the second inductor and the second capacitor, and outputs to the voltage output port at the same time; in the discharging stage, the gating unit disconnects the first inductor from the voltage input port, and connects the second inductor to the two ends of the second capacitor, the first inductor and the second inductor are discharged, the first capacitor and the second capacitor are freewheeling, so as to output to the voltage output port; wherein the output voltage of the voltage output port is equal to the voltage difference between the two ends of the second capacitor.

[0005] In a possible implementation, the voltage input port includes a positive input terminal and a negative input terminal, the negative input terminal is connected to the negative output terminal, the positive input terminal is used to input a power supply voltage, the gating unit is used to connect or disconnect the first inductor to the positive input terminal, the end of the first inductor that is not connected to the first capacitor is one end of the first inductor, and the end of the first capacitor that is not connected to the first inductor is the other end of the first capacitor; the gating unit includes a first switch, a second switch, a first diode and a second diode, the first switch is connected between the positive input terminal and one end of the first inductor, the second switch is connected between the other end of the first inductor and one end of the second inductor, the cathode of the first diode is connected to the first switch, the second switch, the cathode of the first diode and the cathode of the first diode. The first and second switches are connected to one end of an inductor, the anode of the first diode is connected to the cathode of the second diode, the second switch and one end of the second inductor, and the anode of the second diode is connected to the cathode input end, the other end of the second capacitor and the cathode output end; wherein the first switch and the second switch are synchronously turned on or off with a certain duty cycle, the first diode and the second diode are unidirectional conducting diodes, and are turned on or off according to the current flow, the first switch, the second switch, the first diode and the second diode cooperate to connect or disconnect the first inductor with the anode input end, and connect the second inductor to the two ends of the first capacitor or to the two ends of the second capacitor, so as to switch the charging stage or the discharging stage of the buck circuit.

[0006] In a possible implementation, in the charging stage, the first switch and the second switch are both turned on, the first diode and the second diode are both turned off, the first inductor is connected to the positive input terminal through the turned-on first switch, and the second inductor is connected to both ends of the first capacitor through the turned-on second switch.

[0007] In a possible implementation, in the discharge stage, the first switch and the second switch are both disconnected, the first diode and the second diode are both turned on, the first inductor is disconnected from the positive input terminal through the disconnected first switch, and the second inductor is connected to both ends of the second capacitor through the turned-on first diode.

[0008] In a possible implementation, in the discharge phase, the voltage across the first switch is equal to the power supply voltage input to the positive input terminal.

[0009] In a possible implementation, the other end of the first inductor is connected to one end of the first capacitor, the other end of the first capacitor is connected to the positive output end, the other end of the second inductor is connected to the other end of the first capacitor, one end of the second capacitor and the positive output end, and the other end of the second capacitor is connected to the negative input end and the negative output end; wherein, in the charging stage, the positive input end charges the first inductor, the first capacitor, the second inductor and the second capacitor through the first switch and the second switch that are turned on, and outputs to the voltage output port at the same time; in the discharging stage, the first inductor is discharged, and a discharge path is formed through the first diode and the second diode that are turned on, so as to simultaneously freewheel the first capacitor and the second capacitor, and the second inductor is discharged, and a discharge path is formed through the second diode that is turned on, so as to freewheel the second capacitor.

[0010] In a possible implementation, the voltage difference across the second capacitor is equal to the product of the square of the on-duty cycle of the first switch and the second switch and the power supply voltage input to the positive input terminal, and the sum of the voltage difference across the first capacitor and the voltage difference across the second capacitor is equal to the product of the on-duty cycle of the first switch and the second switch and the power supply voltage input to the positive input terminal.

[0011] In a possible implementation, the buck circuit further includes a control unit, which is used to output a control signal to control the first switch and the second switch to be turned on or off, and to control the on-duty cycle of the first switch and the second switch by adjusting the duty cycle of the control signal.

[0012] In a possible implementation manner, the voltage input port is a DC voltage input port, and the voltage output port is a DC voltage output port.

[0013] In the second aspect, a power supply device is also provided, and the power supply device includes a step-down circuit. The step-down circuit includes a voltage input port, a voltage output port, a first step-down unit, a second step-down unit, and a gating unit. The voltage input port is used to input a power supply voltage; the voltage output port includes a positive output terminal and a negative output terminal; the first step-down unit includes a first inductor and a first capacitor, the first inductor is connected to the first capacitor, and the end of the first inductor that is not connected to the first capacitor is selectively connected to the voltage input port, and the end of the first capacitor that is not connected to the first inductor is connected to the positive output terminal; the second step-down unit includes a second inductor and a second capacitor, the second inductor is connected to the second capacitor, and the second inductor is selectively connected to the two ends of the first capacitor or to the two ends of the second capacitor, and the second capacitor is connected between the positive output terminal and the negative output terminal; the gating unit is used to connect or disconnect the first inductor from the voltage input port, and connect the second inductor to the two ends of the first capacitor. end or connected to the two ends of the second capacitor; wherein the step-down circuit includes a charging stage and a discharging stage; in the charging stage, the gating unit connects the first inductor to the voltage input port, and connects the second inductor to the two ends of the first capacitor, the power supply voltage input by the voltage input port charges the first inductor, the first capacitor, the second inductor and the second capacitor, and outputs to the voltage output port at the same time; in the discharging stage, the gating unit disconnects the first inductor from the voltage input port, and connects the second inductor to the two ends of the second capacitor, the first inductor and the second inductor are discharged, the first capacitor and the second capacitor are freewheeling, so as to output to the voltage output port; wherein the output voltage of the voltage output port is equal to the voltage difference between the two ends of the second capacitor.

[0014] The step-down circuit and power supply device of the present application are connected to the first capacitor by setting the first inductor of the first step-down unit, and the end of the first inductor not connected to the first capacitor is selectively connected to the voltage input port, the end of the first capacitor not connected to the first inductor is connected to the positive output terminal, and the second inductor of the second step-down unit is connected to the second capacitor, and the second inductor is selectively connected to the two ends of the first capacitor or to the two ends of the first inductor and the first capacitor connected in series, the second capacitor is connected between the positive output terminal and the negative output terminal, and the corresponding connection relationship is switched by setting a selection unit, so that the voltage stress of the electronic components can be effectively reduced while having a high step-down capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0016] Figure 1 FIG. 4 is a circuit diagram of a voltage-reducing circuit in an embodiment of the present application.

[0017] Figure 2 For Figure 1 The schematic diagram of the buck circuit shown is in the charging stage.

[0018] Figure 3 For Figure 1 The circuit diagram of the buck circuit shown is in the discharge stage.

[0019] Figure 4 The step-down circuit in one embodiment of the present application further includes a circuit diagram of a control unit.

[0020] Figure 5 Schematic diagram of waveforms of relevant parameters obtained through simulation of a buck circuit in an embodiment of the present application.

[0021] Figure 6 It is a block diagram of a power supply device in an embodiment of the present application.

[0022] Explanation of the reference numerals: 100, buck circuit, 10, voltage input port, Vin, power supply voltage, Vin+, positive input terminal, Vin-, negative input terminal, 20, voltage output port, Vo, output voltage, Vout+, positive output terminal, Vout-, negative output terminal, 30, first buck unit, L1, first inductor, C1, first capacitor, 40, second buck unit, L2, second inductor, C2, second capacitor, 50, selection unit, S1, first switch, S2, second switch, D1, first diode, D2, second diode, 60, control unit, 1000, power supply device. DETAILED DESCRIPTION

[0023] 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.

[0024] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it 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. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0026] In the description of the embodiments of the present application, it should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0027] In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0028] See also Figure 1 , Figure 1 FIG. 1 is a circuit diagram of a voltage-reducing circuit in an embodiment of the present application. Figure 1As shown, the present application provides a buck circuit 100 , which includes a voltage input port 10 , a voltage output port 20 , a first buck unit 30 , a second buck unit 40 and a gating unit 50 . The voltage input port 10 is used to input the power supply voltage Vin; the voltage output port 20 includes a positive output terminal Vout+ and a negative output terminal Vout-; the first step-down unit 30 includes a first inductor L1 and a first capacitor C1, the first inductor L1 is connected to the first capacitor C1, and the end of the first inductor L1 not connected to the first capacitor C1 is selectively connected to the voltage input port 10, and the end of the first capacitor C1 not connected to the first inductor L1 is connected to the positive output terminal Vout+; the second step-down unit 40 includes a second inductor L2 and a second capacitor C2, the second inductor L2 is connected to the second capacitor C2, and the second inductor L2 is selectively connected to the two ends of the first capacitor C1 or to the two ends of the second capacitor C2, and the second capacitor C2 is connected between the positive output terminal Vout+ and the negative output terminal Vout-; the gating unit 50 is used to connect or disconnect the first inductor L1 to the voltage input port 10, and to connect the second inductor L2 to the positive output terminal Vout+ and the negative output terminal Vout-. The inductor L2 is connected to both ends of the first capacitor C1 or to both ends of the second capacitor C2; wherein, the buck circuit 100 includes a charging stage and a discharging stage; in the charging stage, the gating unit 50 connects the first inductor L1 to the voltage input port 10, and connects the second inductor L2 to both ends of the first capacitor C1, the power supply voltage Vin input by the voltage input port 10 charges the first inductor L1, the first capacitor C1, the second inductor L2 and the second capacitor C2, and outputs to the voltage output port 20 at the same time; in the discharging stage, the gating unit 50 disconnects the first inductor L1 from the voltage input port 10, and connects the second inductor L2 to both ends of the second capacitor C2, the first inductor L1 and the second inductor L2 are discharged, the first capacitor C1 and the second capacitor C2 are freewheeling, so as to output to the voltage output port 20; wherein, the output voltage Vo of the voltage output port 20 is equal to the voltage difference between the two ends of the second capacitor C2.

[0029] Thus, the above-mentioned buck circuit 100 in the present application is connected to the first capacitor C1 by setting the first inductor L1 of the first buck unit 30, and the end of the first inductor L1 not connected to the first capacitor C1 is selectively connected to the voltage input port 10, and the end of the first capacitor C1 not connected to the first inductor L1 is connected to the positive output terminal Vout+, and is connected to the second capacitor C2 by setting the second inductor L2 of the second buck unit 40, and the second inductor L2 is selectively connected to the two ends of the first capacitor C1 or to the two ends of the second capacitor C2, the second capacitor C2 is connected between the positive output terminal Vout+ and the negative output terminal Vout-, and the corresponding connection relationship is switched by setting the selection unit 50, so that the voltage stress of the electronic components can be effectively reduced while having a higher buck capability.

[0030] The second inductor L2 is connected to both ends of the second capacitor C2, that is, connected to both ends of the first inductor L1 and the first capacitor C1 connected in series.

[0031] The second inductor L2 is connected to both ends of the first inductor L1 and the first capacitor C1 connected in series, which means that the first inductor L1 and the first capacitor C1 connected in series are regarded as an integral structure, and both ends of the second inductor L2 are respectively connected to both ends of the integral structure, that is, one end of the second inductor L2 is connected to one end of the first inductor L1 that is not connected to the first capacitor C1, and the other end of the second inductor L2 is connected to one end of the first capacitor C1 that is not connected to the first inductor L1.

[0032] Specifically, through the first inductor L1 and the first capacitor C1 of the first step-down unit 30, the second inductor L2 and the second capacitor C2 of the second step-down unit 40 and the corresponding connection relationship, the output voltage Vo of the voltage output port 20 is equal to the voltage difference across the second capacitor C2. Compared with the power supply voltage Vin input by the voltage input port 10, the output voltage Vo of the voltage output port 20 can be greatly reduced, and at least the voltage stress of the first capacitor C1 can be effectively reduced, that is, at least the voltage difference across the first capacitor C1 can be effectively reduced, so that a capacitor with a lower withstand voltage can be used to meet the same step-down requirement, thereby reducing the volume and cost of the step-down circuit 100, and having better application value.

[0033] In particular, the output voltage Vo of the voltage output port 20 is the voltage difference between the positive output terminal Vout+ and the negative output terminal Vout-. In the charging stage, the power supply voltage Vin input by the voltage input port 10 charges the first inductor L1, the first capacitor C1, the second inductor L2 and the second capacitor C2, and outputs to the positive output terminal Vout+ at the same time; in the discharging stage, the first inductor L1 and the second inductor L2 discharge, and continue the current to the first capacitor C1 and the second capacitor C2 to output to the positive output terminal Vout+.

[0034] It should be noted that the voltage difference across the second capacitor C2 is obtained by subtracting the voltage at the low voltage end of the second capacitor C2 from the voltage at the high voltage end of the second capacitor C2, or is the absolute value of the voltage difference across the second capacitor C2. And the voltage difference across the first capacitor C1 is the voltage at the high voltage end of the first capacitor C1 minus the voltage at the low voltage end of the first capacitor C1, or is the absolute value of the voltage difference across the first capacitor C1.

[0035] like Figure 1As shown, the voltage input port 10 includes a positive input terminal Vin+ and a negative input terminal Vin-, the negative input terminal Vin- is connected to the negative output terminal Vout-, the positive input terminal Vin+ is used to input the power supply voltage Vin, the gating unit 50 is used to connect or disconnect the first inductor L1 with the positive input terminal Vin+, the end of the first inductor L1 not connected to the first capacitor C1 is one end of the first inductor L1, and the end of the first capacitor C1 not connected to the first inductor L1 is the other end of the first capacitor C1; the gating unit 50 includes a first switch S1, a second switch S2, a first diode D1 and a second diode D2, the first switch S1 is connected between the positive input terminal Vin+ and one end of the first inductor L1, the second switch S2 is connected between the other end of the first inductor L1 and one end of the second inductor L2, the cathode of the first diode D1 is The first switch S1 and one end of the first inductor L1 are connected, the anode of the first diode D1 is connected to the cathode of the second diode D2, the second switch S2 and one end of the second inductor L2, and the anode of the second diode D2 is connected to the cathode input terminal Vin-, the other end of the second capacitor C2 and the cathode output terminal Vout-; wherein the first switch S1 and the second switch S2 are synchronously turned on or off with a certain duty cycle, the first diode D1 and the second diode D2 are unidirectional conducting diodes, and according to the current flow, the first switch S1, the second switch S2, the first diode D1 and the second diode D2 cooperate to connect or disconnect the first inductor L1 with the cathode input terminal Vin+, and connect the second inductor L2 to the two ends of the first capacitor C1 or to the two ends of the second capacitor C2, so as to switch the charging stage or the discharging stage of the buck circuit 100.

[0036] Thus, the above-mentioned buck circuit 100 in the present application sets the first switch S1, the second switch S2, the first diode D1, the second diode D2 and the corresponding connection relationship of the selection unit 50, and configures the first switch S1 and the second switch S2 to be synchronously turned on or off with a certain duty cycle. The first diode D1 and the second diode D2 are unidirectional conducting diodes, which are turned on or off according to the current flow. The first switch S1, the second switch S2, the first diode D1 and the second diode D2 can cooperate to connect or disconnect the first inductor L1 with the positive input terminal Vin+, and connect the second inductor L2 to the two ends of the first capacitor C1 or to the two ends of the second capacitor C2, so as to switch the charging stage or the discharging stage of the buck circuit 100.

[0037] Specifically, through the first switch S1, the second switch S2, the first diode D1, the second diode D2 and the corresponding connection relationship of the gating unit 50, the first diode D1 and the second diode D2 are connected in series and jointly bear the positive input terminal Vin+input power supply voltage Vin of the voltage input port 10, which can effectively reduce the voltage stress of the first diode D1 and the second diode D2, that is, can effectively reduce the voltage difference between the two ends of the first diode D1 and the two ends of the second diode D2. Further, compared with other cascade bucks, the voltage pressure of the first diode D1 corresponding to the first capacitor C1 in the buck circuit 100 can be more significantly reduced.

[0038] like Figure 1 As shown, the buck circuit 100 in the present application, according to the volt-second balance principle satisfied by the first inductor L1 during stable operation, can derive the total voltage VC1+VC2=d×Vin after the first capacitor C1 and the second capacitor C2 are connected in series. Similarly, according to the volt-second balance principle satisfied by the second inductor L2 during stable operation, it can be derived that the voltage relationship between the second capacitor C2 and the first capacitor C1 is VC2=VC1×d / (1-d), where VC1 is the voltage difference across the first capacitor C1, VC2 is the voltage difference across the second capacitor C2, and d is the conduction duty cycle of the first switch S1 and the second switch S2. Since the output voltage Vo of the voltage output port 20 is equal to the voltage difference VC2 across the second capacitor C2, and the voltage difference VC2 across the second capacitor C2 is d 2 × Vin, therefore, the output voltage Vo of the voltage output port 20 and the power supply voltage Vin inputted by the voltage input port 10 satisfy the following relational expression: Vo = d 2 × Vin. Thus, it can have a higher voltage reduction capability, and by reducing the on-duty ratio d of the first switch S1 and the second switch S2, the output voltage Vo of the voltage output port 20 becomes smaller, so as to further enhance the voltage reduction capability.

[0039] In one or more embodiments, the first switch S1 and the second switch S2 may be a power field effect transistor (Metal Oxide Semiconductor FET, MOSFET), an insulated gate bipolar transistor (Insulate-Gate Bipolar Transistor, IGBT) or other controllable switch devices. When the first switch S1 and the second switch S2 are both MOSFETs, the first switch S1 and the second switch S2 may be N-type MOSFETs or P-type MOSFETs. The first switch S1 and the second switch S2 are synchronously turned on or off with a certain duty cycle, that is, the switching period, switching frequency and duty cycle of the first switch S1 and the second switch S2 are the same, and they may be synchronously turned on or off.

[0040] In one or more embodiments, the first diode D1 and the second diode D2 may be various types of common diodes, or various types of Zener diodes (ZD), Schottky Barrier Diodes (SBD), Fast Recovery Diodes (FRD), Transient Voltage Suppressors (TVS) or other diodes with unidirectional conduction characteristics. When the current flowing through the first diode D1 flows in the same direction as the unidirectional conduction direction of the first diode D1, the first diode D1 is turned on, and when the current flows in the opposite direction to the unidirectional conduction direction of the first diode D1, the first diode D1 is turned off. When the current flows in the same direction as the unidirectional conduction direction of the second diode D2, the second diode D2 is turned on, and when the current flows in the opposite direction to the unidirectional conduction direction of the second diode D2, the second diode D2 is turned off.

[0041] See also Figure 2 , Figure 2 For Figure 1 The circuit diagram of the buck circuit in the charging stage is shown in FIG. Figure 2 As shown, in the charging stage, the first switch S1 and the second switch S2 are both turned on, the first diode D1 and the second diode D2 are both turned off, the first inductor L1 is connected to the positive input terminal Vin+ through the turned-on first switch S1, and the second inductor L2 is connected to both ends of the first capacitor C1 through the turned-on second switch S2.

[0042] Thus, in the above-mentioned buck circuit 100 in the present application, in the charging stage, by configuring the first switch S1 and the second switch S2 to be turned on, the branch where the first switch S1 and the second switch S2 are located is also turned on, and the conduction direction of the first diode D1 and the second diode D2 is opposite to the current flow direction flowing through them, then the first diode D1 and the second diode D2 are both disconnected, and the branch where the first diode D1 and the second diode D2 are located is also disconnected, so that the first inductor L1 is connected to the positive input terminal Vin+ through the turned-on first switch S1, and the second inductor L2 is connected to the two ends of the first capacitor C1 through the turned-on second switch S2.

[0043] Specifically, Figure 2As shown, in the charging stage, the first switch S1 and the second switch S2 are both turned on, and the current of the buck circuit 100 flows from the positive input terminal Vin+, the first switch S1, the first inductor L1, the first capacitor C1 (the other branch is the second switch S2, the second inductor L2), the second capacitor C2 (the other branch is the positive output terminal Vout+, the negative output terminal Vout-), the negative input terminal Vin- back to the positive input terminal Vin+ to form a current loop in the charging stage. The conduction direction of the first diode D1 and the second diode D2 is opposite to the current flow direction flowing through them, then the first diode D1 and the second diode D2 are disconnected, and the branch where the first diode D1 and the second diode D2 are located is also disconnected. The power supply voltage Vin input at the positive input terminal Vin+ of the voltage input port 10 charges the first inductor L1, the first capacitor C1, the second inductor L2 and the second capacitor C2 through the current loop in the charging stage, and outputs to the positive output terminal Vout+ of the voltage output port 20 at the same time.

[0044] See also Figure 3 , Figure 3 For Figure 1 The circuit diagram of the buck circuit in the discharge stage is shown in FIG. Figure 3 As shown, the first switch S1 and the second switch S2 are both disconnected, the first diode D1 and the second diode D2 are both turned on, the first inductor L1 is disconnected from the positive input terminal Vin+ through the disconnected first switch S1, and the second inductor L2 is connected to both ends of the second capacitor C2 through the turned-on first diode D1.

[0045] Thus, in the above-mentioned buck circuit 100 in the present application, in the discharge stage, by configuring the first switch S1 and the second switch S2 to be disconnected, the branch where the first switch S1 and the second switch S2 are located is also disconnected, and the conduction direction of the first diode D1 and the second diode D2 is the same as the current flow direction flowing through them, then the first diode D1 and the second diode D2 are both turned on, and the branch where the first diode D1 and the second diode D2 are located is also turned on, so that the first inductor L1 is disconnected from the positive input terminal Vin+ through the disconnected first switch S1, and the second inductor L2 is connected to the two ends of the second capacitor C2 through the turned-on first diode D1.

[0046] Specifically, Figure 3As shown, in the discharge stage, the first switch S1 and the second switch S2 are both disconnected, and the current of the buck circuit 100 flows from the first inductor L1, the first capacitor C1, the second capacitor C2 (the other branch is the positive output terminal Vout+, the negative output terminal Vout-), the second diode D2, the first diode D1 back to the first inductor L1, and from the second inductor L2, the second capacitor C2 (the other branch is the positive output terminal Vout+, the negative output terminal Vout-), the second diode D2 back to the second inductor L2, so as to form a current loop in the discharge stage. The conduction direction of the first diode D1 and the second diode D2 is the same as the current flow direction flowing through them, then the first diode D1 and the second diode D2 are turned on, and the branch where the first diode D1 and the second diode D2 are located is also turned on, the first inductor L1 and the second inductor L2 are discharged, and the first capacitor C1 and the second capacitor C2 are freewheeling, so as to output to the voltage output port 20.

[0047] In one or more embodiments, during the discharge phase, the voltage across the first switch S1 is equal to the positive input terminal Vin+the input power supply voltage Vin.

[0048] In one or more embodiments, in the discharge phase, the sum of the voltage difference across the first diode D1 and the voltage difference across the second diode D2 is equal to the positive input terminal Vin+the input power supply voltage Vin.

[0049] Therefore, the above-mentioned buck circuit 100 in the present application, by setting the first diode D1 and the second diode D2 connected in series, jointly withstands the power supply voltage Vin input by the positive input terminal Vin+ of the voltage input port 10, and can effectively reduce the voltage stress of the first diode D1 and the second diode D2, so that a diode with a lower withstand voltage can be used to meet the same voltage reduction requirement, thereby reducing the volume and cost of the buck circuit 100, and having better application value.

[0050] like Figure 1 As shown, the buck circuit 100 in the present application, according to the above, the total voltage VC1+VC2=d×Vin after the first capacitor C1 and the second capacitor C2 are connected in series, then the voltage stresses borne by the first diode D1 and the second diode D2 are (1-d)×Vin and d×Vin respectively. It can be seen that no matter how the conduction duty cycle d of the first switch S1 and the second switch S2 is set, the voltage stress of the first diode D1 and the second diode D2 is small, and the voltage stress of one of the diodes can also be significantly reduced.

[0051] Please refer again Figure 1 , Figure 2 , Figure 3 ,like Figure 1 , Figure 2 , Figure 3As shown, the other end of the first inductor L1 is connected to one end of the first capacitor C1, the other end of the first capacitor C1 is connected to the positive output terminal Vout+, the other end of the second inductor L2 is connected to the other end of the first capacitor C1, one end of the second capacitor C2 and the positive output terminal Vout+, and the other end of the second capacitor C2 is connected to the negative input terminal Vin- and the negative output terminal Vout-; wherein, in the charging stage, the positive input terminal Vin+ charges the first inductor L1, the first capacitor C1, the second inductor L2 and the second capacitor C2 through the turned-on first switch S1 and the second switch S2, and outputs to the voltage output port 20 at the same time; in the discharging stage, the first inductor L1 is discharged, and a discharge path is formed through the turned-on first diode D1 and the second diode D2 to simultaneously freewheel the first capacitor C1 and the second capacitor C2, and the second inductor L2 is discharged, and a discharge path is formed through the turned-on second diode D2 to freewheel the second capacitor C2.

[0052] Thus, the above-mentioned buck circuit 100 in the present application, through the connection relationship between the first inductor L1, the first capacitor C1, the second inductor L2 and the second capacitor C2, can realize that in the charging stage, the positive input terminal Vin+ charges the first inductor L1, the first capacitor C1, the second inductor L2 and the second capacitor C2 through the turned-on first switch S1 and the second switch S2, and outputs to the voltage output port 20 at the same time; and can realize that in the discharging stage, the first inductor L1 is discharged, and a discharge path is formed through the turned-on first diode D1 and the second diode D2 to simultaneously freewheel the first capacitor C1 and the second capacitor C2, and the second inductor L2 is discharged, and a discharge path is formed through the turned-on second diode D2 to freewheel the second capacitor C2.

[0053] In one or more embodiments, the voltage difference across the second capacitor C2 is equal to the product of the square of the on-duty cycle of the first switch S1 and the second switch S2 and the power supply voltage Vin input to the positive input terminal Vin+, and the sum of the voltage difference across the first capacitor C1 and the voltage difference across the second capacitor C2 is equal to the product of the on-duty cycle of the first switch S1 and the second switch S2 and the power supply voltage Vin input to the positive input terminal Vin+.

[0054] Therefore, in the step-down circuit 100 of the present application, according to the above derivation process, the voltage difference VC2 across the second capacitor C2 is d 2 ×Vin, that is, the output voltage Vo of the buck circuit 100, the sum of the voltage difference VC1 across the first capacitor C1 and the voltage difference VC2 across the second capacitor C2 is d×Vin, which can have a higher buck capability, and the output voltage Vo of the voltage output port 20 can be reduced by reducing the conduction duty cycle d of the first switch S1 and the second switch S2, so as to further enhance the buck capability.

[0055] See also Figure 4 , Figure 4 FIG. 1 is a circuit diagram of a voltage reduction circuit in an embodiment of the present application, which further includes a control unit. Figure 4 As shown, the buck circuit 100 further includes a control unit 60, which is used to output a control signal to control the first switch S1 and the second switch S2 to be turned on or off, and to control the on-duty cycle of the first switch S1 and the second switch S2 by adjusting the duty cycle of the control signal.

[0056] Therefore, the above-mentioned buck circuit 100 in the present application sets a control unit 60 and configures the control unit 60 to output a control signal to control the first switch S1 and the second switch S2 to be turned on or off, and configures the control unit 60 to adjust the duty cycle of the control signal to control the on-duty cycle of the first switch S1 and the second switch S2.

[0057] In one or more embodiments, the control unit 60 can be a general-purpose processor such as a central processing unit (CPU), or a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate logic devices, transistor logic devices and other logic control devices, or a microprocessor such as a micro control unit (MCU).

[0058] In one or more embodiments, the control signal may be a pulse width modulation signal (PWM), and the duty cycle of the control signal may be adjusted by adjusting the pulse width of the pulse width modulation signal to control and adjust the conduction duty cycle of the first switch S1 and the second switch S2.

[0059] In one or more embodiments, the voltage input port 10 is a DC voltage input port, and the voltage output port 20 is a DC voltage output port.

[0060] Therefore, the above-mentioned step-down circuit 100 in the present application can convert the DC voltage to output a stepped-down DC voltage to meet the required voltage conversion requirements.

[0061] See also Figure 5 , Figure 5The waveform diagram of the relevant parameters of the buck circuit in an embodiment of the present application obtained by simulation is shown below. When the power supply voltage Vin is 500 volts (V), the first inductor L1 and the second inductor L2 are both 10 microhenry (μH), the first capacitor C1 and the second capacitor C2 are both 220 microfarads (μF), the load connected to the voltage output port 20 is 0.1 ohm (Ω), the frequency of the control signal is 100 kilohertz (kHz), and the duty cycle is set to 0.3, as shown in FIG. Figure 5 As shown, it can be seen that after the step-down circuit 100 is stabilized, the voltage difference VC1 across the first capacitor C1 is about 105V, the voltage difference VC2 across the second capacitor C2 is about 45V, the voltage difference across the first diode D1 alternates between 0 and 350V, and the current iL1 of the first inductor L1 alternates between 100A (A) and 200A, and the current iL2 of the second inductor L2 is close to 450A, which is consistent with the theoretical calculation structure, and effectively verifies that the step-down circuit 100 can effectively reduce the voltage stress of electronic components while having a high step-down capability.

[0062] The step-down circuit 100 of the present application, through the above-mentioned structure, can effectively reduce the voltage stress of electronic components while having a high step-down capability, so that electronic components with lower tolerable voltage can be used to meet the same step-down requirements, thereby reducing the volume and cost of the step-down circuit 100, having better application value, and at the same time being able to transform the DC voltage to output a stepped-down DC voltage to meet the required voltage conversion requirements.

[0063] See also Figure 6 , Figure 6 FIG. 1 is a block diagram of a power supply device in an embodiment of the present application. Figure 6 As shown, the present application further provides a power supply device 1000, and the power supply device 1000 includes the buck circuit 100 in any of the aforementioned embodiments.

[0064] Please refer again Figure 1 ,like Figure 1As shown, the buck circuit 100 includes a voltage input port 10 , a voltage output port 20 , a first buck unit 30 , a second buck unit 40 and a gating unit 50 . The voltage input port 10 is used to input the power supply voltage Vin; the voltage output port 20 includes a positive output terminal Vout+ and a negative output terminal Vout-; the first step-down unit 30 includes a first inductor L1 and a first capacitor C1, the first inductor L1 is connected to the first capacitor C1, and the end of the first inductor L1 not connected to the first capacitor C1 is selectively connected to the voltage input port 10, and the end of the first capacitor C1 not connected to the first inductor L1 is connected to the positive output terminal Vout+; the second step-down unit 40 includes a second inductor L2 and a second capacitor C2, the second inductor L2 is connected to the second capacitor C2, and the second inductor L2 is selectively connected to the two ends of the first capacitor C1 or to the two ends of the second capacitor C2, and the second capacitor C2 is connected between the positive output terminal Vout+ and the negative output terminal Vout-; the gating unit 50 is used to connect or disconnect the first inductor L1 to the voltage input port 10, and to connect the second inductor L2 to the positive output terminal Vout+ and the negative output terminal Vout-. The inductor L2 is connected to both ends of the first capacitor C1 or to both ends of the second capacitor C2; wherein, the buck circuit 100 includes a charging stage and a discharging stage; in the charging stage, the gating unit 50 connects the first inductor L1 to the voltage input port 10, and connects the second inductor L2 to both ends of the first capacitor C1, the power supply voltage Vin input by the voltage input port 10 charges the first inductor L1, the first capacitor C1, the second inductor L2 and the second capacitor C2, and outputs to the voltage output port 20 at the same time; in the discharging stage, the gating unit 50 disconnects the first inductor L1 from the voltage input port 10, and connects the second inductor L2 to both ends of the second capacitor C2, the first inductor L1 and the second inductor L2 are discharged, the first capacitor C1 and the second capacitor C2 are freewheeling, so as to output to the voltage output port 20; wherein, the output voltage Vo of the voltage output port 20 is equal to the voltage difference between the two ends of the second capacitor C2.

[0065] The more specific structure of the buck circuit 100 can refer to the relevant content of the buck circuit 100 in any of the aforementioned embodiments, which will not be described in detail here.

[0066] In one or more embodiments, the power supply device 1000 may further include a voltage source, which is connected to the voltage input port 10 and is used to output a power supply voltage Vin.

[0067] In one or more embodiments, when the voltage output port 20 of the power supply device 1000 is connected to a load, the output voltage Vo of the voltage output port 20 is used to power the load after being stepped down.

[0068] The step-down circuit 100 and the power supply device 1000 of the present application, through the above-mentioned structure, can effectively reduce the voltage stress of electronic components while having a high step-down capability, so that electronic components with lower tolerable voltage can be used to meet the same step-down requirements, thereby reducing the volume and cost of the step-down circuit 100, having better application value, and at the same time being able to transform the DC voltage to output a stepped-down DC voltage to meet the required voltage conversion requirements.

[0069] The above description is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application; in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A step-down circuit, characterized in that: include: Voltage input port, used to input power supply voltage; A voltage output port, including a positive output terminal and a negative output terminal; A first step-down unit, comprising a first inductor and a first capacitor, wherein the first inductor is connected to the first capacitor, and one end of the first inductor not connected to the first capacitor is selectively connected to the voltage input port, and one end of the first capacitor not connected to the first inductor is connected to the positive output terminal; A second step-down unit, comprising a second inductor and a second capacitor, wherein the second inductor is connected to the second capacitor, and the second inductor can be selectively connected to both ends of the first capacitor or to both ends of the second capacitor, and the second capacitor is connected between the positive output terminal and the negative output terminal; a gating unit, configured to connect or disconnect the first inductor from the voltage input port, and connect the second inductor to both ends of the first capacitor or to both ends of the second capacitor; The step-down circuit includes a charging stage and a discharging stage; in the charging stage, the gating unit connects the first inductor to the voltage input port, and connects the second inductor to the two ends of the first capacitor, the power supply voltage input by the voltage input port charges the first inductor, the first capacitor, the second inductor and the second capacitor, and outputs to the voltage output port at the same time; in the discharging stage, the gating unit disconnects the first inductor from the voltage input port, and connects the second inductor to the two ends of the second capacitor, the first inductor and the second inductor are discharged, the first capacitor and the second capacitor are freewheeled, so as to output to the voltage output port; wherein the output voltage of the voltage output port is equal to the voltage difference between the two ends of the second capacitor; The voltage input port includes a positive input terminal and a negative input terminal, the negative input terminal is connected to the negative output terminal, the positive input terminal is used to input a power supply voltage, the gating unit is used to connect or disconnect the first inductor from the positive input terminal, the end of the first inductor that is not connected to the first capacitor is one end of the first inductor, and the end of the first capacitor that is not connected to the first inductor is the other end of the first capacitor; The gating unit includes a first switch, a second switch, a first diode and a second diode, the first switch is connected between the positive input terminal and one end of the first inductor, the second switch is connected between the other end of the first inductor and one end of the second inductor, the cathode of the first diode is connected to the first switch and one end of the first inductor, the anode of the first diode is connected to the cathode of the second diode, the second switch and one end of the second inductor, and the anode of the second diode is connected to the cathode input terminal, the other end of the second capacitor and the cathode output terminal; The first switch and the second switch are synchronously turned on or off with a certain duty cycle, the first diode and the second diode are unidirectional conducting diodes, which are turned on or off according to the current flow, and the first switch, the second switch, the first diode and the second diode cooperate to connect or disconnect the first inductor with the positive input terminal, and connect the second inductor to both ends of the first capacitor or to both ends of the second capacitor, so as to switch the charging stage or the discharging stage of the buck circuit.

2. The step-down circuit according to claim 1, characterized in that: In the charging stage, the first switch and the second switch are both turned on, the first diode and the second diode are both turned off, the first inductor is connected to the positive input terminal through the turned-on first switch, and the second inductor is connected to both ends of the first capacitor through the turned-on second switch.

3. The step-down circuit according to claim 1, characterized in that: In the discharge stage, the first switch and the second switch are both disconnected, the first diode and the second diode are both turned on, the first inductor is disconnected from the positive input terminal through the disconnected first switch, and the second inductor is connected to both ends of the second capacitor through the turned-on second diode.

4. The step-down circuit according to claim 3, characterized in that: In the discharge phase, the voltage across the first switch is equal to the power supply voltage input to the positive input terminal.

5. The step-down circuit according to claim 1, characterized in that: The other end of the first inductor is connected to one end of the first capacitor, the other end of the first capacitor is connected to the positive output terminal, the other end of the second inductor is connected to the other end of the first capacitor, one end of the second capacitor and the positive output terminal, and the other end of the second capacitor is connected to the negative input terminal and the negative output terminal; In the charging stage, the positive input end charges the first inductor, the first capacitor, the second inductor and the second capacitor through the first switch and the second switch that are turned on, and outputs to the voltage output port at the same time; in the discharging stage, the first inductor discharges, and a discharge path is formed through the first diode and the second diode that are turned on, so as to simultaneously freewheel the first capacitor and the second capacitor, and the second inductor discharges, and a discharge path is formed through the second diode that is turned on, so as to freewheel the second capacitor.

6. The step-down circuit according to claim 5, characterized in that: The voltage difference across the second capacitor is equal to the product of the square of the on-duty cycle of the first switch and the second switch and the power supply voltage input to the positive input terminal, and the sum of the voltage difference across the first capacitor and the voltage difference across the second capacitor is equal to the product of the on-duty cycle of the first switch and the second switch and the power supply voltage input to the positive input terminal.

7. The step-down circuit according to claim 1, characterized in that: The buck circuit also includes a control unit, which is used to output a control signal to control the first switch and the second switch to be turned on or off, and to control the on-duty cycle of the first switch and the second switch by adjusting the duty cycle of the control signal.

8. The step-down circuit according to any one of claims 1 to 7, characterized in that: The voltage input port is a DC voltage input port, and the voltage output port is a DC voltage output port.

9. A power supply device, characterized in that: The step-down circuit comprises the step-down circuit described in any one of claims 1 to 8.

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