Active-clamp current-fed push-pull converter for bidirectional power transfer

Abstract

The present disclosure relates to active-clamp current-fed push-pull converters for bidirectional power transfer. An apparatus including a bidirectional power converter circuit. The power converter circuit includes a primary circuit side including a plurality of primary switches, an isolation transformer, and a secondary circuit side separated from the primary circuit side by the isolation transformer. The secondary circuit side includes an inductor, a rectifier circuit coupled to the inductor and configured to receive energy from and provide the energy to the primary circuit side, and a clamp circuit coupled to the inductor and configured to provide a reset voltage to the inductor that prevents inductor current runaway.

Description

Technical Field

[0001] This disclosure relates to an active clamp current-fed push-pull converter for bidirectional power transfer. Background Technology

[0002] Electronic power systems typically consist of one or more power converters controlled by integrated circuits. A power converter receives an electrical input with input amplitude, frequency, and / or phase on the input side and converts the electrical input to an electrical output with amplitude, frequency, and / or phase on the output side. Isolated bidirectional power converters include isolation transformers to electrically isolate the output stage or secondary side of the power converter from the input stage or primary side by arranging the isolation transformer between the primary and secondary sides. For low-voltage to high-voltage conversion, one approach involves a bulky capacitor charger with a few millifarads (mF) of capacitor connected to the inverter input. Another approach is a phase-shifted full-bridge isolated topology for high Vin to low Vout conversion, but it has startup problems for reverse low-voltage to high-voltage applications. Summary of the Invention

[0003] This document generally relates to switching power converters and their operation methods. One example device includes a bidirectional power converter circuit. The power converter circuit includes: a primary circuit side including a plurality of primary switches; an isolation transformer; and a secondary circuit side, separated from the primary circuit side by the isolation transformer. The secondary circuit side includes: an inductor; a rectifier circuit coupled to the inductor and configured to receive energy from and supply energy to the primary circuit side; and a clamping circuit coupled to the inductor and configured to provide a reset voltage to the inductor to prevent runaway inductor current.

[0004] This section is intended to provide an overview of the subject matter of this patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. Detailed descriptions are included to provide further information regarding this patent application. Attached Figure Description

[0005] In accompanying drawings that are not necessarily drawn to scale, the same numbers may describe similar parts in different views. Similar numbers with different letter suffixes may represent different instances of similar components. The accompanying drawings are illustrated in general terms by way of example and not limitation, of the various embodiments discussed in this document.

[0006] Figure 1 This is a circuit diagram of an example of an isolated bidirectional power converter.

[0007] Figure 2 This is a block diagram of another example of an isolated bidirectional power converter.

[0008] Figure 3This is a diagram indicating the high-voltage domain and low-voltage domain of an electric vehicle.

[0009] Figure 4 It is shown Figure 1 The waveform diagram of the power converter circuit in positive operation.

[0010] Figure 5A and 5B It is shown Figure 1 The waveform diagram of the power converter circuit in reverse operation.

[0011] Figure 6 The following is shown for startup in reverse buck mode. Figure 1 The waveform of the power converter circuit is simulated.

[0012] Figure 7 It is used for Figure 6 A schematic diagram of the simulated circuit.

[0013] Figure 8 This is a flowchart illustrating an example of a method for operating a bidirectional power converter circuit. Detailed Implementation

[0014] Figure 3 This is an illustration indicating an electric vehicle with a high-voltage domain (e.g., 400 volts (V) or 800V) and a low-voltage domain (e.g., 12V or 48V). In electric vehicles, a DC-DC bidirectional converter (DC / DC converter) is used to transfer energy from a high-voltage battery pack to a low-voltage lead-acid battery. Because the converter is bidirectional, it can also transfer energy from the low-voltage lead-acid battery to a high-voltage, high-capacity cap on the high-voltage battery pack side, or provide high voltage when the high-voltage battery is not connected or otherwise not present in the circuit.

[0015] Figure 2 This is a circuit diagram of an example isolated bidirectional power converter. The power converter includes a primary circuit side 202, an isolation transformer 204, and a secondary circuit side 206. The primary circuit side 202 is connected to a supply rail with voltage V1, while the secondary circuit side is connected to a supply rail with voltage V2. Typically, V1 (400V-800V) is greater than V2 (12V). The primary circuit side 202 has a phase-shifted full-bridge converter topology and includes capacitor C. HV The secondary circuit side 206 includes a filter capacitor CLV, an inductor L, and a full-wave rectifier circuit, which includes a synchronous rectifier implemented with field-effect transistors (FETs) SR1 and SR2.

[0016] The power converter is bidirectional, capable of converting a higher voltage V1 to a lower voltage V2 in the forward direction and vice versa. However, using a phase-shifted full-bridge topology in the reverse direction to convert a low voltage to a high voltage under certain conditions is not always straightforward. One problem is that at startup, when the high-voltage rail is lower than the low-voltage rail, the inductor L cannot achieve volt-second balance, resulting in runaway inductor current. This runaway inductor current can damage components of the power converter.

[0017] Figure 1 This is a circuit diagram of another example of a power converter. The power converter circuit 300 includes a primary circuit side 302, an isolation transformer 304, and a secondary circuit side 306. Figure 1 The circuit example also includes a clamping circuit 308 connected to the rectifier circuit on the secondary circuit side 306. The clamping circuit 308 provides a reset voltage to the inductor L to prevent runaway inductor current.

[0018] The rectifier circuit turns the first synchronous rectifier SR1 "ON" and the second synchronous rectifier SR2 "OFF" during the first half of the switching cycle, and turns the first synchronous rectifier SR1 "OFF" and the second synchronous rectifier SR2 "ON" during the second half of the switching cycle. The clamping circuit 308 includes clamping switches AC1 and AC2 and a clamping capacitor C. CLAMP1 and C CLAMP2 Each clamping capacitor is coupled to inductor L and clamping switch.

[0019] The clamping switch is a clamping FET. One clamping FET and one clamping capacitor reset the inductor L at half the switching cycle. The drain / source region of the clamping FET is connected to the source / drain region of the SR FET. Another source / drain region of the clamping FET is connected to the clamping capacitor. The clamping FET is turned on only when the SR FET is off. The clamping capacitor helps establish a voltage higher than V2 at the center branch of transformer 304. As a result, the clamping circuit 308 establishes volt-second balance in inductor L.

[0020] The power converter circuit 300 can operate in forward mode in buck mode, where the higher voltage V1 is converted to the lower voltage V2. The power converter circuit can also operate in reverse mode in either boost or buck mode, where the lower voltage V2 is converted to the higher voltage V1 / n (where n is the transformer's turns ratio), or in buck mode, where V2 is greater than V1 / n. Without the clamping circuit 308, the center branch of the transformer 304 would be less than V2 during reverse operation, which would cause the inductor current to run away.

[0021] Figure 4is a diagram showing waveforms of the operation of the power converter circuit 300 in the forward direction. The waveforms include control signals for FETs M1-M4, SR1, SR2, AC1, AC2. The waveform I L is the inductor current. I L the waveform shows the duty cycle (DT S ) of inductor charging. The forward output is

[0022] V2=(2D)(V1) / n,

[0023] where V1 is the input voltage, V2 is the output voltage, n is the transformer turns ratio (n:1:1), and D is the switching duty cycle (0<D<1). When the duty cycle D is equal to 1, the maximum output voltage in the forward step-down mode is

[0024] V 2,MAX is (2 / n)(V1).

[0025] Figure 5 is a diagram showing waveforms of the operation of the power converter circuit 300 in the reverse direction. In the reverse direction, V2 is the input voltage and V1 is the output voltage. When the duty cycle is less than 0.5 (D<0.5), Figure 1 the power converter circuit 300 operates in a reverse step-down mode where V1<V2. The output in the reverse step-down mode is

[0026] V1=(2Dn)(V2).

[0027] When the duty cycle increases to D>0.5, the power converter circuit transitions to a reverse step-up mode where V1>V2 and

[0028] V1=n(V2) / (2(1-D)).

[0029] As previously explained herein, when the V1 voltage is less than the V2 voltage in the reverse step-down mode, without a clamp circuit, the inductor L cannot achieve volt-second balance, and inductor current runaway occurs. Figure 1 the clamp circuit 308 provides active clamping of the inductor current. Figure 5 shows that clamp FET AC1 is turned on after FET SR2 is turned off, and then turned off before FET SR 2 is turned on. FET AC2 is turned on after FET SR1 is turned off, and then turned off just before FET SR1 is turned on. The activation signal of the AC1 / SR2 FET pair is complementary and non-overlapping with the activation signal of the AC2 / SR1 FET pair.

[0030] When the SR FET of the AC / SR FET pair is ON, the inductor current I L increases, and the energy stored in inductor L and clamp capacitors C CLAMP1 and C CLAMP2The energy in the circuit flows from the secondary circuit side 306 to the output V2. When the SR FET is OFF, I L The energy that is reduced and stored in the inductor L flows to the clamping capacitor.

[0031] Figure 6 The waveforms of a circuit simulation of the power converter circuit 300 used for startup in reverse buck mode are shown. Figure 7 This is a circuit diagram used for simulation. From Figure 6 As can be seen from this, the inductor current I L2 The clamping capacitor decreases during the switching between clamping FET AC1 and clamping FET AC2, and does not run away during startup. The clamping capacitor coupled to clamping FET AC1 discharges during a portion of the sampling period when clamping FET AC1 is active. The clamping capacitor coupled to clamping FET AC2 charges just before clamping FET AC1 becomes active. The clamping capacitor coupled to clamping FET AC2 discharges during a portion of the sampling period when clamping FET AC2 is active. The clamping capacitor coupled to clamping FET AC1 charges just before clamping FET AC2 becomes active.

[0032] For the sake of overview, Figure 8 This is a flowchart illustrating an example of a method 800 for operating a bidirectional power converter circuit. The bidirectional power converter circuit can be a push-pull converter, for example... Figure 1 The power converter circuit 300 in the middle. The power converter circuit has a primary circuit side separated from the secondary circuit side by a transformer, and the power converter circuit can operate in the forward direction where energy is transferred from the primary circuit side to the secondary circuit side and in the reverse direction where energy is transferred from the secondary circuit side to the primary circuit side.

[0033] In block 805, the power converter circuit operates in reverse buck mode, where the input voltage on the secondary side is higher than the output voltage on the primary side, and energy is supplied from the secondary-side inductor to the primary side. In block 810, a clamping circuit is used to limit the inductor current on the secondary side. The inductor current flows from the secondary-side inductor to the primary side.

[0034] Clamping the inductor current prevents leakage current from flowing that could damage the circuit. The clamping circuit provides a reset voltage to the inductor when the output voltage of the higher supply rail is lower than the input voltage of the lower supply rail and below the setpoint during converter circuit startup. Active clamping when the output is below the setpoint prevents inductor current loss in a current-feed push-pull converter, enabling bidirectional power transfer without pre-biasing the higher voltage rail during power converter startup. Active clamping can be used to clamp any leakage current spikes in the inductor when the power converter circuit is operating in either forward or reverse mode.

[0035] Additional notes and aspects

[0036] The first aspect (Aspect 1) includes a subject (e.g., a bidirectional power converter circuit), comprising: a primary circuit side including a plurality of primary switches; an isolation transformer; and a secondary circuit side separated from the primary circuit side by the isolation transformer. The secondary circuit side includes: an inductor; a rectifier circuit coupled to the inductor and configured to receive energy from and supply energy to the primary circuit side; and a clamping circuit coupled to the inductor and configured to provide a reset voltage to the inductor to prevent runaway inductor current.

[0037] In aspect 2, the subject matter of aspect 1 may optionally include: a rectifier circuit comprising: a plurality of synchronous rectifier switches; and the clamping circuit comprising a plurality of clamping switches and a plurality of clamping capacitors, wherein each of the plurality of clamping capacitors is coupled to the clamping switches and the inductor, and each clamping switch is coupled to the synchronous rectifier switch.

[0038] In aspect 3, the subject matter of aspect 2 may optionally include: a primary circuit side including a full-bridge converter circuit topology, and the rectifier circuit including a full-wave rectifier circuit topology.

[0039] In aspect 4, the subject matter of one or any combination of aspects 1-3 may optionally include: a power converter circuit configured to operate to convert voltage in a forward mode and a reverse mode, wherein in the forward mode, the input voltage on the primary circuit side is higher than the output voltage on the secondary circuit side, and in the reverse mode, the input voltage on the secondary circuit side is higher or lower than the output voltage on the primary circuit side.

[0040] In aspect 5, the subject matter of aspect 4 may optionally include: the rectifier circuit includes a plurality of synchronous rectifier switches, and the clamping circuit includes at least one clamping capacitor coupled to the inductor; and when the power converter circuit operates in the reverse mode and the input voltage is higher than the output voltage, when the at least one synchronous rectifier switch is turned on, the inductor current increases, and the energy stored in the inductor and the at least one clamping capacitor flows to the primary circuit side; and when the at least one synchronous rectifier switch is turned off, the inductor current decreases, and the energy stored in the inductor flows to the at least one clamping capacitor.

[0041] In aspect 6, the subject matter of one or any combination of aspects 1-5 may optionally include: the rectifier circuit comprising a plurality of synchronous rectifier switches, the clamping circuit comprising a first clamping field-effect transistor (FET) and a second clamping FET, and the plurality of synchronous rectifier switches comprising first and second synchronous rectifier switches. A first source or drain region of the first clamping FET is connected to a first source or drain region of the second clamping FET, a second source or drain region of the first clamping FET is connected to the second synchronous rectifier switch, and a second drain or source region of the second clamping FET is connected to the first synchronous rectifier switch.

[0042] In aspect 7, the subject matter of aspect 6 may optionally include: the clamping circuit includes a first clamping capacitor coupled to the first clamping FET and a second clamping capacitor coupled to the second clamping FET. When the second clamping FET and the second synchronous rectifier switch are off, the first clamping capacitor charges from the inductor, and when the first clamping FET is on, the first clamping capacitor discharges; and when the first clamping FET and the first synchronous rectifier switch are off, the second clamping capacitor charges from the inductor, and when the second clamping FET is on, the second clamping capacitor discharges.

[0043] Aspect 8 includes a subject matter (e.g., a method of operating a bidirectional power converter circuit having a primary circuit side separated from the secondary circuit side by a transformer), or may optionally be combined with one or any combination of aspects 1-7 to include a subject matter comprising: operating the power converter circuit in a reverse buck mode, wherein the input voltage of the secondary circuit side is higher than the output voltage of the primary circuit side, and energy is supplied from an inductor on the secondary circuit side to the primary circuit side; and resetting the voltage of the inductor in the reverse buck mode to prevent runaway inductor current.

[0044] In aspect 9, the subject matter of aspect 8 may optionally include: operating a rectifier circuit having at least one synchronous rectifier switch on the secondary circuit side, and increasing the inductor current when the at least one synchronous rectifier switch is turned on; and decreasing the inductor current and charging the clamping capacitor of the clamping circuit with energy stored in the inductor when the synchronous rectifier switch is turned off.

[0045] In aspects 10 and 9, the subject matter may optionally include: charging the clamping capacitor when a clamping switch coupled to the clamping capacitor is turned on, and discharging the clamping capacitor when the clamping switch is turned off.

[0046] The subject matter of one or any combination of aspects 11, 8-10 may optionally include: operating a rectifier circuit having a second-side rectifier circuit having a first synchronous rectifier field-effect transistor (FET) and a second synchronous rectifier FET, wherein when the first synchronous rectifier FET is turned on, a first clamping capacitor coupled to the inductor is discharged and a second clamping capacitor is charged, and when the second synchronous rectifier FET is turned on, the second clamping capacitor is discharged and the first clamping capacitor is charged.

[0047] In aspect 12, the subject matter of aspect 11 may optionally include: discharging the first clamping circuit when a first clamping FET coupled to the first clamping capacitor is turned on, and discharging the second clamping circuit when a second clamping FET coupled to the second clamping capacitor is turned on. The activation signal of the first clamping FET is complementary to the activation signal of the second synchronous rectifier FET, and the activation signal of the second clamping FET is complementary to the activation signal of the first synchronous rectifier FET.

[0048] The subject matter of one or both of aspects 13, 11 and 12 may optionally include: a full-bridge converter circuit operating on the primary circuit side.

[0049] In aspect 14, the subject matter of one or any combination of aspects 11-13 may optionally include: switching the power converter circuit from reverse buck mode to reverse boost mode by changing the duty cycle of the first synchronous rectifier FET and the second synchronous rectifier FET.

[0050] Aspect 15 includes a subject matter (e.g., a power supply system) or may optionally be combined with one or any combination of aspects 1-14 to include a subject matter comprising a first power rail, a second power rail, and a voltage converter circuit, comprising: a full-bridge converter circuit coupled to the first power rail and including a plurality of main switches; an isolation transformer; an inductor coupled to the isolation transformer; a rectifier circuit; and a clamping circuit. The rectifier circuit is coupled to the second power rail and the inductor and is isolated from the full-bridge converter circuit via the isolation transformer, wherein the rectifier circuit is configured to receive energy from and supply energy to the full-bridge converter circuit. The clamping circuit is coupled to the inductor and is configured to provide a reset voltage to the inductor to prevent runaway inductor current.

[0051] In aspect 16, the subject matter of aspect 15 may optionally include: the rectifier circuit includes a plurality of synchronous rectifier switches, and the clamping circuit includes a plurality of clamping switches and a plurality of clamping capacitors, wherein each of the plurality of clamping capacitors is coupled to the clamping switch and the inductor, and each clamping switch is coupled to the synchronous rectifier switch.

[0052] The subject matter of one or both of aspects 17, 15 and 16 may optionally include: the rectifier circuit includes a full-wave rectifier circuit topology.

[0053] The subject matter of one or any combination of aspects 18, 15-17 may optionally include: the voltage converter circuit being configured to operate to convert voltage in a forward mode and a reverse mode, wherein in the forward mode the voltage of the first power supply rail is higher than the voltage of the second power supply rail, and in the reverse mode the voltage of the second power supply rail is higher or lower than the voltage of the first power supply rail.

[0054] In aspect 19, the subject matter of aspect 18 may optionally include: the rectifier circuit includes a plurality of synchronous rectifier switches, and the clamping circuit includes at least one clamping capacitor coupled to the inductor; and when the voltage converter circuit operates in reverse mode and the voltage of the second power supply rail is higher than the voltage of the first power supply rail, when the at least one synchronous rectifier switch is turned on, the inductor current increases, and the energy stored in the inductor and the energy stored in the at least one clamping capacitor flows to the primary circuit side, and when the at least one synchronous rectifier switch is turned off, the inductor current decreases, and the energy stored in the inductor flows to the at least one clamping capacitor.

[0055] The subject matter of one or any combination of aspects 20, 15-19 may optionally include: the rectifier circuit comprising a plurality of synchronous rectifier switches; and the clamping circuit comprising a first clamping field-effect transistor (FET) and a second clamping FET, and the plurality of synchronous rectifier switches comprising first and second synchronous rectifier switches. A first source or drain region of the first clamping FET is connected to a first source or drain region of the second clamping FET; and a second source or drain region of the first clamping FET is connected to the second synchronous rectifier switch, and a second drain or source region of the second clamping FET is connected to the first synchronous rectifier switch.

[0056] These non-limiting aspects can be combined in any arrangement or combination. The above detailed description includes references to the accompanying drawings, which form part of the detailed description. The drawings illustrate, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” All publications, patents, and patent documents mentioned in this document are incorporated herein by reference in their entirety, as if individually incorporated by reference. In the event of any inconsistency between the usage in this document and the documents merged by reference, the usage in the merged references shall be considered supplementary to this document; in the case of irreconcilable inconsistencies, the usage in this document shall prevail.

[0057] In this document, the terms “a” or “an” are common in patent documents and include one or more, independent of any other instances or uses of “at least one” or “one or more”. Unless otherwise stated, “A or B” includes “A but not B”, “B but not A”, and “A and B”. In the appended claims, the terms “comprising” and “wherein” are used as their plain English equivalents to the corresponding terms “including” and “comprise”. Furthermore, in the following claims, the terms “comprising” and “comprise” are open-ended, meaning that a system, device, article, or method that includes elements other than those listed after the term in a claim is still considered to fall within the scope of that claim. Additionally, in the following claims, the terms “first,” “second,” and “third,” etc., are used merely as labels and are not intended to impose numerical requirements on their objects. Examples of methods described herein may be implemented at least in part by a machine or computer.

[0058] The above description is intended to be illustrative and not restrictive. For example, the examples (or one or more aspects thereof) described above may be used in combination with each other. Other embodiments may be used, for example, by those skilled in the art upon review of the above description. The abstract is provided to comply with 37 CFR § 1.72(b) so that the reader may quickly determine the nature of the technical disclosure. It should be understood that this document is not intended to interpret or limit the scope or meaning of the claims. Furthermore, in the detailed description above, various features may be grouped together to simplify this disclosure. This should not be construed as meaning that any unclaimed disclosed feature is essential to any claim. Rather, the subject matter of the invention may be present in fewer than all features of a particular disclosed embodiment. Therefore, the following claims are hereby incorporated into the detailed description, each claim existing independently as a separate embodiment. The scope of the invention should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A bidirectional power converter circuit, the bidirectional power converter circuit comprising: The primary circuit side includes multiple primary switches connected to the primary side input / output terminals; An isolation transformer consists of a primary winding and a secondary winding; and On the secondary circuit side, the circuit is separated from the primary circuit side and connected to the secondary circuit input / output terminals via the isolation transformer, wherein the secondary circuit side includes: An inductor includes a first terminal connected to the secondary winding and a second terminal connected to the secondary-side input / output terminal; A rectifier circuit, coupled to the inductor and configured to receive energy from the primary circuit side and supply the energy to the primary circuit side, wherein the rectifier circuit includes first and second synchronous rectifier switches; and A clamping circuit, coupled to the inductor and configured to provide a reset voltage to the inductor to prevent runaway inductor current, wherein the clamping circuit includes: First and second clamping capacitors directly connected to the second terminal of the inductor, and first and second clamping switches respectively coupled to the first and second clamping capacitors; The first terminal of the first clamping switch is directly connected to the first terminal of the second clamping switch; The second terminal of the first clamping switch is directly connected to the second synchronous rectifier switch, and the second terminal of the second clamping switch is directly connected to the first synchronous rectifier switch. The first clamping capacitor is coupled to the first clamping switch, and the second clamping capacitor is coupled to the second clamping switch; When the second clamping switch and the second synchronous rectifier switch are open, the first clamping capacitor charges from the inductor, and when the first clamping switch is closed, the first clamping capacitor discharges; and When the first clamping switch and the first synchronous rectifier switch are open, the second clamping capacitor is charged from the inductor, and when the second clamping switch is closed, the second clamping capacitor is discharged.

2. The bidirectional power converter circuit according to claim 1, wherein the primary circuit side includes a full-bridge converter circuit topology, and the rectifier circuit includes a full-wave rectifier circuit topology.

3. The bidirectional power converter circuit of claim 1, wherein the bidirectional power converter circuit is configured to operate to switch voltages in a forward mode and a reverse mode, and in the forward mode, the input voltage on the primary circuit side is higher than the output voltage on the secondary circuit side, and in the reverse mode, the input voltage on the secondary circuit side is higher or lower than the output voltage on the primary circuit side.

4. The bidirectional power converter circuit according to claim 3, When the bidirectional power converter circuit operates in the reverse mode and the input voltage on the secondary circuit side is higher than the output voltage on the primary circuit side, when at least one of the first and second synchronous rectifier switches is turned on, the inductor current increases, and the energy stored in the inductor and at least one of the first and second clamping capacitors flows to the primary circuit side; and when at least one synchronous rectifier switch is turned off, the inductor current decreases, and the energy stored in the inductor flows to the at least one clamping capacitor.

5. The bidirectional power converter circuit according to claim 1, The first clamping switch is a first clamping field-effect transistor (FET), and the second clamping switch is a second clamping FET.

6. A method of operating a bidirectional power converter circuit, the bidirectional power converter circuit having a primary circuit side separated from the secondary circuit side by a transformer, the method comprising: The bidirectional power converter circuit is operated in reverse buck mode, wherein the input voltage on the secondary circuit side is higher than the output voltage on the primary circuit side, and energy is supplied to the primary circuit side from an inductor on the secondary circuit side, wherein the inductor includes a first terminal coupled to the transformer and a second terminal coupled to the input on the secondary circuit side. The rectifier circuit on the secondary circuit side is operated, and the rectifier circuit has a first synchronous rectifier switch and a second synchronous rectifier switch. as well as In the reverse buck mode, the voltage of the inductor is reset to limit the inductor current, thereby preventing the inductor current from running out of control. The current limiting of the inductor includes: charging the first clamping capacitor directly connected to the second terminal of the inductor when the first clamping switch directly connected to the first clamping capacitor is turned on and the second synchronous rectifier switch is turned on; discharging the first clamping capacitor when the first clamping switch is turned off and the first synchronous rectifier switch is turned on; charging the second clamping capacitor directly connected to the second terminal of the inductor when the second clamping switch directly connected to the first and second clamping capacitors is turned on and the second synchronous rectifier switch is turned on; and discharging the second clamping capacitor when the second clamping switch is turned off and the second synchronous rectifier switch is turned on. The activation signal of the first clamping switch is complementary to the activation signal of the second synchronous rectifier switch, and the activation signal of the second clamping switch is complementary to the activation signal of the first synchronous rectifier switch.

7. The method according to claim 6, Limiting the inductor current includes reducing the inductor current and using the energy stored in the inductor to charge one of the first and second clamping capacitors when one of the first and second synchronous rectifier switches is turned off.

8. The method of claim 6, wherein limiting the inductor current further comprises: When one of the first and second clamping switches is turned on, one of the first and second clamping capacitors is charged, and when one of the first and second clamping switches is turned off, one of the first and second clamping capacitors is discharged.

9. The method of claim 6, wherein the first synchronous rectifier switch is a first synchronous rectifier field-effect transistor (FET), and the second synchronous rectifier switch is a second synchronous rectifier FET.

10. The method of claim 9, wherein operating the bidirectional power converter circuit in reverse buck mode includes operating the full-bridge converter circuit on the primary circuit side.

11. The method of claim 9, further comprising switching the bidirectional power converter circuit from reverse buck mode to reverse boost mode by changing the duty cycle of the first synchronous rectifier FET and the second synchronous rectifier FET.

12. A power supply system, the system comprising: First power supply rail and second power supply rail; as well as Voltage converter circuit, including: A full-bridge converter circuit, coupled to the first power supply rail, includes multiple main switches; An isolation transformer, comprising a primary winding and a secondary winding; An inductor, the inductor including a first terminal coupled to the secondary winding of the isolation transformer and a second terminal coupled to the second power supply rail; A rectifier circuit, coupled to the second power supply rail and the inductor, and isolated from the full-bridge converter circuit via the isolation transformer, wherein the rectifier circuit includes a first synchronous rectifier switch and a second synchronous rectifier switch and is configured to receive energy from and supply energy to the full-bridge converter circuit; and A clamping circuit, coupled to the inductor and configured to provide a reset voltage to the inductor to prevent runaway inductor current, wherein the clamping circuit includes: First and second clamping capacitors directly connected to the second terminal of the inductor, and first and second clamping switches respectively coupled to the first and second clamping capacitors; The first terminal of the first clamping switch is directly connected to the first terminal of the second clamping switch; The second terminal of the first clamping switch is directly connected to the second synchronous rectifier switch, and the second terminal of the second clamping switch is directly connected to the first synchronous rectifier switch. The first clamping capacitor is coupled to the first clamping switch, and the second clamping capacitor is coupled to the second clamping switch; When the second clamping switch and the second synchronous rectifier switch are open, the first clamping capacitor charges from the inductor, and when the first clamping switch is closed, the first clamping capacitor discharges; and When the first clamping switch and the first synchronous rectifier switch are open, the second clamping capacitor is charged from the inductor, and when the second clamping switch is closed, the second clamping capacitor is discharged.

13. The system of claim 12, wherein the rectifier circuit comprises a full-wave rectifier circuit topology.

14. The system of claim 12, wherein the voltage converter circuit is configured to operate to convert voltage in a forward mode and a reverse mode, and in the forward mode, the voltage of the first power supply rail is higher than the voltage of the second power supply rail, and in the reverse mode, the voltage of the second power supply rail is higher than or lower than the voltage of the first power supply rail.

15. The system according to claim 14, When the voltage converter circuit operates in reverse mode and the voltage of the second power supply rail is higher than the voltage of the first power supply rail, when at least one of the first and second synchronous rectifier switches is turned on, the inductor current increases, and the energy stored in the inductor and the energy stored in at least one of the first and second clamping capacitors flows to the full-bridge converter circuit. When the at least one synchronous rectifier switch is turned off, the inductor current decreases, and the energy stored in the inductor flows to the at least one clamping capacitor.

16. The system according to claim 12, The first clamping switch is a first clamping field-effect transistor (FET), and the second clamping switch is a second clamping FET.

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