Power supply circuit and pre-charge control method
By using a duty cycle control signal to dynamically adjust the pre-charge rate in the switching power supply circuit, the problem of inrush current at startup is solved, and the power supply circuit can operate stably under a large range of input voltage variations, thereby reducing cost and complexity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ZTE CORP
- Filing Date
- 2026-01-21
- Publication Date
- 2026-07-30
AI Technical Summary
In existing technology, when a large-capacity clamping capacitor is configured for the active clamping absorption circuit in a switching power supply circuit, the inrush current at startup can cause damage to the switching transistor and overcurrent faults. In addition, the additional pre-charging circuit increases cost and complexity and cannot adapt to the inrush current problem when the input voltage varies widely.
By applying a control signal with a duty cycle in the switch control module, the pre-charge rate is dynamically adjusted to achieve pre-charging of the clamping capacitor, avoiding the need for an additional pre-charge circuit and adapting to stable operation when the input voltage varies widely.
It reduces the voltage stress on the switching transistors and clamping capacitors, improves the reliability and stability of the power supply circuit, and reduces the complexity and cost of the circuit structure.
Smart Images
Figure CN2026073860_30072026_PF_FP_ABST
Abstract
Description
Power supply circuit and pre-charge control method
[0001] Cross-reference to related applications
[0002] This application claims priority to Chinese Patent Application No. 202510121907.1, filed with the Chinese Patent Office on January 24, 2025, the entire contents of which are incorporated herein by reference. Technical Field
[0003] This disclosure relates to, but is not limited to, the field of circuit technology. Background Technology
[0004] Switching power supply circuits play a crucial role in electronic systems. The switching circuit itself is the core component of a switching power supply. To alleviate the voltage stress on the switching transistors, snubber circuits are typically added across the transistors. Active clamping snubber circuits can effectively absorb excessive voltage fluctuations and convert them into controllable energy, thus protecting the switching transistors from damage caused by transient high voltages.
[0005] To effectively absorb voltage stress and ensure the safe operation of the power supply circuit, a large-capacity clamping capacitor is required for the active clamping snubber circuit. To prevent overcurrent faults in the active clamping snubber circuit caused by the inrush current at startup, a pre-charge circuit and power supply are typically added. However, this approach has several drawbacks. First, it requires additional components to construct the pre-charge circuit, increasing cost and complexity of the power supply circuit structure. Second, it may result in incomplete pre-charging. Summary of the Invention
[0006] This disclosure provides a power supply circuit and a pre-charge control method for the power supply circuit.
[0007] In a first aspect, embodiments of this disclosure provide a power supply circuit, including: a switching circuit module, an active clamping circuit module, and a switching control module. The switching circuit module includes a first switching device, an input voltage is applied to the input terminal of the switching circuit module, and the output terminal of the switching circuit module is connected to the input terminal of the active clamping circuit module. The active clamping circuit module includes a clamping capacitor, and the output voltage of the switching circuit module is used to charge the clamping capacitor. The switching control module is connected to the control terminal of the first switching device. During a pre-charging phase, the switching control module applies a first control signal having a first duty cycle to the first switching device to control the speed at which the output voltage of the switching circuit module pre-charges the clamping capacitor. The pre-charging phase is a phase for pre-charging the clamping capacitor, during which the voltage of the clamping capacitor rises from 0 to the output voltage of the switching circuit module.
[0008] Secondly, embodiments of this disclosure provide a pre-charging control method for a power supply circuit. The power supply circuit includes a switching circuit module, an active clamping circuit module, and a switching control module. The switching circuit module includes a first switching device, an input voltage is applied to the input terminal of the switching circuit module, and the output terminal of the switching circuit module is connected to the input terminal of the active clamping circuit module. The active clamping circuit module includes a clamping capacitor, and the output voltage of the switching circuit module is used to charge the clamping capacitor. The switching control module is connected to the control terminal of the first switching device. The method includes: in a pre-charging phase, the switching control module applies a first control signal having a first duty cycle to the first switching device to control the speed at which the output voltage of the switching circuit module pre-charges the clamping capacitor. The pre-charging phase is a phase for pre-charging the clamping capacitor, during which the voltage of the clamping capacitor rises from 0 to the output voltage of the switching circuit module. Attached Figure Description
[0009] In the accompanying drawings of the embodiments disclosed herein:
[0010] Figure 1 shows a schematic block diagram of a power supply circuit according to an embodiment of the present disclosure;
[0011] Figure 2 shows a schematic diagram of the charging control principle of the power supply circuit according to an embodiment of the present disclosure;
[0012] Figure 3 shows a schematic diagram of a first control signal having a first duty cycle and a pre-charge voltage according to an embodiment of the present disclosure;
[0013] Figure 4 shows a schematic block diagram of a power supply circuit applied to a full-bridge converter (FBC) according to an embodiment of the present disclosure;
[0014] Figure 5 shows a schematic block diagram of a power supply circuit according to an embodiment of the present disclosure applied to a full-wave rectifier converter circuit;
[0015] Figure 6 shows examples of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure;
[0016] Figure 7 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure;
[0017] Figure 8 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure;
[0018] Figure 9 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure;
[0019] Figure 10 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure;
[0020] Figure 11 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure;
[0021] Figure 12 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure;
[0022] Figure 13 shows a schematic block diagram of a power supply circuit applied to a buck converter according to an embodiment of the present disclosure;
[0023] Figure 14 shows a flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure;
[0024] Figure 15 shows another flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure;
[0025] Figure 16 shows another flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure;
[0026] Figure 17 shows another flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure. Detailed Implementation
[0027] To enable those skilled in the art to better understand the technical solutions of this disclosure, the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.
[0028] The present disclosure will be described more fully below with reference to the accompanying drawings; however, the embodiments shown may be embodied in different forms, and the present disclosure should not be construed as limited to the embodiments set forth below. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will enable those skilled in the art to fully understand the scope of the disclosure.
[0029] The accompanying drawings of the embodiments disclosed herein are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the detailed embodiments to explain this disclosure and do not constitute a limitation thereof. The above and other features and advantages will become more apparent to those skilled in the art from the description of the detailed embodiments with reference to the accompanying drawings.
[0030] This disclosure may be described with reference to plan and / or cross-sectional views using the ideal schematic diagrams of this disclosure. Therefore, the example illustrations may be modified according to manufacturing techniques and / or tolerances.
[0031] Where there is no conflict, the various embodiments of this disclosure and the features thereof in the embodiments may be combined with each other.
[0032] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. The term "and / or" as used in this disclosure includes any and all combinations of one or more of the associated enumerated entries. The singular forms "a" and "the" as used in this disclosure are also intended to include the plural forms, unless the context clearly indicates otherwise. The terms "comprising," "made of," etc., as used in this disclosure specify the presence of the stated feature, integral, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.
[0033] Unless otherwise specified, all terms used in this disclosure (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so specified in this disclosure.
[0034] This disclosure is not limited to the embodiments shown in the accompanying drawings, but includes modifications to the configuration based on the manufacturing process. Therefore, the areas illustrated in the drawings are schematic, and the shapes of the areas shown illustrate specific shapes of those areas, but are not intended to be limiting.
[0035] Switching power supply circuits play a crucial role in electronic systems. The switching circuit itself is the core component of a switching power supply. To alleviate the voltage stress on the switching transistors, snubber circuits are typically added across the transistors. Active clamping snubber circuits can effectively absorb excessive voltage fluctuations and convert them into controllable energy, thus protecting the switching transistors from damage caused by transient high voltages.
[0036] In extreme scenarios such as lightning strikes or electrostatic interference, a large-capacity clamping capacitor is required for the active clamping snubber circuit to effectively absorb voltage stress and ensure the safe operation of the power supply circuit. However, at the initial moment of power supply circuit startup, since the voltage of the clamping capacitor is zero in the initial state, the entire voltage output from the rectifier circuit in the switching power supply circuit will be directly applied to the clamping capacitor. This instantaneous surge current not only significantly increases the voltage stress on the switching transistor (which may further lead to damage to the switching transistor due to overload), but may also trigger overcurrent faults in the clamping switch of the active clamping snubber circuit, and in severe cases, may even cause the switching device to burn out. The existence of these problems significantly reduces the reliability and stability of the entire power supply circuit.
[0037] To address the aforementioned issues, an additional pre-charge circuit and power supply are typically added to the active clamping snubber circuit. By adding this extra circuit and power supply, the voltage across the clamping capacitor can be pre-charged from zero to a certain voltage (approximately the voltage of the additional power supply) before the power supply circuit starts up. In this way, the voltage applied to the clamping capacitor during power supply circuit startup is no longer the output voltage of the rectifier circuit, but rather the difference between the rectifier circuit's output voltage and the clamping capacitor's pre-charge voltage, thereby reducing the inrush current and voltage stress on the switching transistor during startup. However, this approach has several drawbacks. First, it requires additional components to construct the pre-charge circuit, increasing cost and complexity of the power supply circuit. Second, it may lead to incomplete pre-charge. This is because the pre-charge voltage of the clamping capacitor depends on the additional power supply voltage, which is a fixed value and has no direct correlation with the rectifier circuit's output voltage. When the input voltage varies over a wide range, a significant voltage difference remains between the rectifier circuit's output voltage and the clamping capacitor's pre-charge voltage, resulting in a large inrush current for the clamping capacitor. Therefore, this approach is not suitable for input voltages with a wide range of variations. In particular, when the input voltage changes rapidly (such as from lightning strikes, static electricity, or other abnormal interference), the clamping capacitor withstands a larger surge current, resulting in a larger voltage difference in traditional pre-charging schemes, which affects circuit reliability.
[0038] This disclosure provides a power supply circuit and a pre-charge control method for the power supply circuit. By applying a control signal with a duty cycle to the switching device, pre-charging of the active clamping circuit can be achieved without setting up an additional pre-charge circuit and power supply, thus reducing costs. This pre-charge method ensures that the pre-charge rate is controllable and that the power supply circuit can operate stably even with a large range of input voltage variations.
[0039] Figure 1 shows a schematic block diagram of a power supply circuit according to an embodiment of the present disclosure.
[0040] As shown in FIG1, the power supply circuit according to an embodiment of the present disclosure includes a switching circuit module 110, an active clamping circuit module 120, and a switching control module 130.
[0041] Switching circuit module 110 includes first switching devices (e.g., switching devices Q11 and Q12), and input voltage V. in The voltage V is applied to the input terminal of the switching circuit module 110, and the output terminal of the switching circuit module 110 is connected to the input terminal of the active clamping circuit module 120. The active clamping circuit module 120 includes clamping capacitors (e.g., clamping capacitors C1 to Cn), and the output voltage V of the switching circuit module 110 is... out_sUsed to charge the clamping capacitor. The switch control module 130 is connected to the control terminal of the first switching device. During the pre-charging phase, the switch control module 130 applies a first control signal with a first duty cycle to the first switching device to control the output voltage V of the switch circuit module 110. out_s The speed at which the clamping capacitor is pre-charged.
[0042] In this disclosure, the pre-charge phase is a phase for pre-charging the clamping capacitor, during which the voltage of the clamping capacitor rises from 0 to the output voltage of the switching circuit module 110.
[0043] According to embodiments of this disclosure, the active clamping circuit module 120 may further include a second switching device (e.g., clamping switches Q1 to Qn) connected in series with the clamping capacitor, and the switch control module 130 is connected to the control terminal of the second switching device.
[0044] As shown in FIG1, the power supply circuit according to the embodiment of the present disclosure may include a switching circuit module 110 composed of a parasitic inductance L1 generated by the leakage inductance of the transformer and the wiring, and switching devices Q11 and Q12, an active clamping circuit module 120 composed of a clamping capacitor and a clamping switch, and a switching control module 130 for controlling the on and off of the switching devices.
[0045] Figure 2 shows a schematic diagram of the charging control principle of the power supply circuit according to an embodiment of the present disclosure.
[0046] As shown in Figure 2, clamping capacitors C1 to Cn are connected in series with the parasitic inductance L1. Therefore, the charging current Ic on the clamping capacitors can be equal to the current IL flowing through the parasitic inductance L1, i.e., Ic = IL. Furthermore, the current IL flowing through the parasitic inductance L1 can be calculated using the following formula: IL = (V n -V cn )*dt / L1
[0047] Among them, V n V represents the voltage applied to the parasitic inductance L1. cn dt is the charging voltage across the clamping capacitor, L1 is the charging hold time, and L1 is the inductance value of parasitic inductance generated by the transformer leakage inductance and wiring. The relationship between the charging hold time dt and the period T of the control signal output by the switch control module 130 can be expressed by the following formula:
[0048] dt=D*T
[0049] Where D is the duty cycle of the control signal.
[0050] Therefore, during the pre-charging phase, the pre-charging hold time of the parasitic inductor L1 can be controlled by adjusting the first duty cycle of the first control signal, thereby controlling the current flowing through the parasitic inductor L1 and adjusting the pre-charging current of the clamping capacitor, i.e., controlling the pre-charging speed of the clamping capacitor. Thus, the pre-charging hold time can be dynamically adjusted by controlling the duty cycle of the control signal output by the control module to control the magnitude of the pre-charging current, achieving the purpose of pre-charging the clamping capacitor at a predetermined rate.
[0051] Figure 3 shows a schematic diagram of a first control signal having a first duty cycle and a pre-charge voltage according to an embodiment of the present disclosure.
[0052] As shown in Figure 3, during the pre-charging phase before power-on (i.e., the phase from time T0 to T1), the switch control module 130 can apply a first control signal with a small first duty cycle to the control terminal of the switching device of the switch circuit module 110, thereby controlling the pre-charging rate of the clamping capacitor to be small.
[0053] According to embodiments of this disclosure, the first duty cycle of the first control signal can be determined based on the capacitance of the clamping capacitor and the inrush current threshold of the clamping switch (i.e., the second switching device). When the input voltage V in When the voltage V in the switching circuit changes, n This will also change accordingly, so the pre-charge voltage of the clamping capacitor can automatically adapt to this change.
[0054] After a period of time, when the voltage across the clamping capacitor reaches or approaches the output voltage V of the rectifier circuit... out_s When this time, it indicates that the clamping capacitor has completed the pre-charging process.
[0055] According to the power supply circuit of this disclosure, the function of pre-charging the clamping capacitor is realized by reusing components in the power supply circuit, eliminating the need for an additional pre-charging circuit and power supply, reducing cost and simplifying the structure of the power supply circuit. Based on a single power supply, the pre-charging rate is controlled by adjusting the duty cycle of the control signal output by the switch control module, and it can adapt to a wide range of input voltage variations.
[0056] The power supply circuit according to the embodiments of this disclosure can be applied to power conversion systems such as AC-DC power converters and DC-DC power converters, including but not limited to full-bridge converters (FBC), half-bridge converters (HBC), forward converters, push-pull converters, flyback converters, and various buck converter, boost converter, and buck-boost converter topologies.
[0057] Figure 4 shows a schematic block diagram of a power supply circuit applied to an FBC according to an embodiment of the present disclosure.
[0058] According to an embodiment of this disclosure, as shown in FIG4, the power supply circuit further includes a filter circuit module 140. An active clamping circuit module 120 is connected between the switching circuit module 110 and the filter circuit module 140. In the output phase following the pre-charging phase, the output voltage V of the power supply circuit is output via the filter circuit module 140. out .
[0059] According to an embodiment of this disclosure, as shown in FIG4, the switching circuit module 110 includes a transformer T1, and the first switching devices include a first switching device group Q11 to Q14 and a second switching device group Q21 to Q24. The first switching device group Q11 to Q14 constitutes a first bridge circuit, and the input voltage V in The voltage is applied to the primary side of transformer T1 via the first bridge circuit. The second switching device group Q21 to Q24 constitutes the second bridge circuit, and the secondary side of transformer T1 provides the output voltage of switching circuit module 110 to active clamping circuit module 120 via the second bridge circuit. The active clamping circuit module includes clamping capacitor C. clamp and clamping capacitor C clamp Serial-connected clamping switch Q clamp The output voltage of the switching circuit module 110 is used to clamp the capacitor C. clamp Charging is performed. The switch control module 130 is connected to the control terminal of each switch device. During the pre-charging phase, the switch control module 130 applies a first control signal with a first duty cycle to the first switch device group Q11 to Q14.
[0060] In the switching circuit module 110 shown in Figure 4, the first bridge circuit composed of the first switching device group Q11 to Q14 is used to convert DC to AC, the second bridge circuit composed of the second switching device group Q21 to Q24 is used to rectify AC to DC, the transformer T1 is used for AC voltage transformation and isolation, and the parasitic inductance L1 is generated by the leakage inductance and wiring of the transformer T1.
[0061] Figure 5 shows a schematic block diagram of a power supply circuit applied to a full-wave rectifier converter circuit according to an embodiment of the present disclosure.
[0062] Compared to the embodiment shown in FIG. 4, in the embodiment shown in FIG. 5, the first switching device includes a first switching device group Q11 to Q14 and a second switching device group Q31 to Q32. The second switching device group Q31 to Q32 constitutes a full-wave rectifier circuit, and the secondary side of the transformer T1 provides the output voltage of the switching circuit module 110 to the active clamping circuit module 120 via the full-wave rectifier circuit.
[0063] Figure 6 shows examples of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure.
[0064] According to an embodiment of this disclosure, as shown in FIG6, during the pre-charging phase, the switch control module 130 applies a first control signal having a first duty cycle to the first switching device (e.g., the first switching device group Q11 to Q14 shown in FIGS. 4 and 5). During the pre-charging phase, the clamping capacitor C... clamp The charging voltage V on cn The output voltage of the switching circuit module 110 can be controlled to increase to or near its range. During the pre-charging process, the output voltage V of the power supply circuit is not established. out Applying a first control signal to the first switching device can clamp the capacitor C. clamp The pre-charging process, and the clamping switch Q clamp It can be in the off state. When the clamping capacitor C clamp After the pre-charging is complete, the output voltage V of the power supply circuit can be gradually established. out This achieves the desired output voltage.
[0065] According to an embodiment of this disclosure, as shown in FIG6, in the output phase following the pre-charging phase, the switch control module 130 can send a signal to the second switching device (i.e., the clamping switch Q). clamp Apply a second control signal with a second duty cycle.
[0066] According to an embodiment of the present disclosure, as shown in FIG6, in the output phase after the pre-charging phase, the switch control module 130 may also apply a third control signal with a third duty cycle to the first switching device (e.g., the first switching device group Q11 to Q14 shown in FIG4 and FIG5).
[0067] Referring to Figures 4 to 6, before the power supply circuit starts, the switch control module 130 sends a first control signal with a small first duty cycle to control the on and off states of switches Q11 to Q14, thereby inverting the DC power into AC power with a small duty cycle. The inverted AC power is transmitted through transformer T1 and the parasitic inductance L1 generated by the leakage inductance of transformer T1 and its wiring. The voltage at one end of the parasitic inductance L1 can be determined based on the input voltage V. in The value is calculated from the turns ratio N of transformer T1, i.e., V n =V in / N, the other end of the parasitic inductance L1 is the clamping capacitor C. clamp The charging voltage V on cn This process enables the clamping capacitor C in the active clamping circuit module 120 to be clamped. clamp Pre-charge. When the clamping capacitor C clamp The charging voltage V on cn Approaching or equal to V in When / N, the pre-charging process is complete.
[0068] It should be noted that in practical applications, the clamping capacitor C can be used as a reference. clamp The capacity and clamping switch Q clamp The first duty cycle of the first control signal can be adjusted by parameters such as the maximum tolerable inrush current (i.e., the inrush current threshold) or the maximum inrush voltage during the pre-charge phase. For example, the minimum pulse width can be about 50 ns, and the pre-charge duration can be about 100 uS, corresponding to about 20 cycles.
[0069] According to embodiments of this disclosure, the first control signal may include one pulse width or may include multiple pulse widths. The pulse width of the first control signal may have a constant value, or it may have a value that varies within a certain range; for example, the pulse width of the first control signal may gradually increase.
[0070] Figure 7 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure.
[0071] In the example of Figure 6, during the pre-charging phase, the switch control module 130 does not apply a control signal to the second group of switching devices. Unlike the example of Figure 6, as shown in Figure 7, according to an embodiment of this disclosure, during the pre-charging phase, the switch control module 130 may apply a fourth control signal with a fourth duty cycle to the second group of switching devices (e.g., the second group of switching devices Q21 to Q24 shown in Figure 4 or the second group of switching devices Q31 to Q32 shown in Figure 5).
[0072] As shown in Figure 7, during the pre-charging stage, the fourth control signal can be synchronized with the first control signal, or the fourth control signal can be complementary to the first control signal. That is, the control methods of the switching transistors (Q11 to Q14) in the first switching device group and the switching transistors (Q21 to Q24 or Q31 to Q32) in the second switching device group can be in various forms, as long as the pre-charging needs are met.
[0073] According to embodiments of this disclosure, as shown in Figures 6 and 7, in the output phase following the pre-charging phase, the switch control module 130 may apply a third control signal with a third duty cycle to the first switch device group (e.g., the first switch device groups Q11 to Q14 shown in Figures 4 and 5), and apply a fifth control signal with a fifth duty cycle to the second switch device group (e.g., the second switch device groups Q21 to Q24 shown in Figure 4 or the second switch device groups Q31 to Q32 shown in Figure 5).
[0074] In the examples of Figures 6 and 7, the control signals applied to the first group of switching devices (i.e., the first control signal and the third control signal) are also referred to as the main switch control signals, and the control signals applied to the second group of switching devices (i.e., the fourth control signal and the fifth control signal) are also referred to as the synchronous switch control signals.
[0075] Figure 8 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure.
[0076] Unlike the example in Figure 6, in the example in Figure 8, the clamping capacitor C... clamp After the pre-charging is completed and after the first delay (i.e., after time T1), the switch control module 130 begins to send a signal to the clamp switch Q. clamp Applying a second control signal with a second duty cycle can also achieve the clamping of capacitor C. clamp Pre-charge.
[0077] Figure 9 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure.
[0078] Unlike the example in Figure 7, in the example in Figure 9, during the pre-charging phase, the switch control module 130 can send a signal to the clamping switch Q.clamp Applying a second control signal with a second duty cycle can also achieve the clamping of capacitor C. clamp Pre-charge.
[0079] Figure 10 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure.
[0080] Unlike the example in Figure 6, in the example in Figure 10, the output power supply circuit outputs a first output voltage during the output phase and a second output voltage during the pre-charge phase, with the second output voltage being lower than the first output voltage. Specifically, the pre-charge phase may include a first time period (i.e., T0 to T01) and a second time period (i.e., T01 to T1). By controlling the first duty cycle of the first control signal, the output voltage V of the power supply circuit can be established starting from the first time period. out And at time T01, the output voltage V of the power supply circuit is made... out A second output voltage with a lower than desired output voltage subsequently causes the output voltage V of the power supply circuit to be lower than the desired output voltage from time T01 to time T1 when the pre-charge is completed (i.e., the second time period). out Maintaining the second output voltage also allows for clamping capacitor C. clamp Pre-charge.
[0081] Figure 11 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure.
[0082] Unlike the example in Figure 7, in the example in Figure 11, the output power supply circuit outputs a first output voltage during the output phase and a second output voltage during the pre-charge phase, with the second output voltage being lower than the first output voltage. Specifically, the pre-charge phase may include a first time period (i.e., T0 to T01), a second time period (i.e., T01 to T02), and a third time period (i.e., T02 to T1). By controlling the first duty cycle of the first control signal, the output voltage V of the power supply circuit can be established starting from the first time period. out And at time T01, the output voltage V of the power supply circuit is made... out A second output voltage, which is less than the desired output voltage, causes the output voltage V of the power supply circuit to be less than the desired output voltage during the period from time T01 to time T02 before the pre-charge is completed (i.e., the second time period). out Maintaining the second output voltage, and starting at time T02, gradually establishing the output voltage V of the power supply circuit based on the second output voltage. out The clamping capacitor C can also be achieved until the voltage rises to the first output voltage. clamp Pre-charge.
[0083] Figure 12 shows another example of various control signals output by the switch control module in a power supply circuit according to an embodiment of the present disclosure.
[0084] Unlike the example in Figure 11, in the example in Figure 12, the switch control module 130 begins to move the clamping switch Q before the pre-charge is completed (i.e., the pre-charge phase portion before time T1). clamp Applying a second control signal with a second duty cycle can also achieve the clamping of capacitor C. clamp Pre-charge.
[0085] Figure 13 shows a schematic block diagram of a power supply circuit applied to a BUCK converter according to an embodiment of the present disclosure.
[0086] According to an embodiment of this disclosure, as shown in FIG13, the first switching device includes a main switching device Q41 and a freewheeling switching device Q42. When the main switching device Q41 is turned on, the freewheeling switching device Q42 is turned off, and the output voltage of the switching circuit module 110 is provided to the active clamping circuit module 120 via the main switching device Q41; when the main switching device Q41 is turned off, the freewheeling switching device Q42 is turned on, and the output voltage of the switching circuit module 110 is provided to the active clamping circuit module 120 via the freewheeling switching device Q42. The active clamping circuit module includes a clamping capacitor C. clamp (shown as C3 in the diagram) and clamping capacitor C clamp Serial-connected clamping switch Q clamp (Q9 is shown in the diagram). The output voltage of the switching circuit module 110 is used to clamp the capacitor C. clamp Charging is performed. The switch control module 130 is connected to the control terminals of each switching device. During the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the main switching device Q41 and a fourth control signal with a fourth duty cycle to the freewheeling switching device Q42.
[0087] It should be understood that the power supply circuit according to the embodiments of this disclosure can be applied to circuits with various topologies and is not limited to the specific circuit form shown. Those skilled in the art can modify the technical concept of this disclosure for specific practical applications to implement the technical solutions of this disclosure, and this disclosure aims to protect all such modified implementations.
[0088] According to the power supply circuit of this disclosure embodiment, before the power supply circuit is started, a small charging current can be generated by a control signal with a small duty cycle to charge the clamping capacitor. The entire power supply circuit is started after the voltage of the clamping capacitor has stabilized. When the power supply circuit is started, a pre-charge voltage has been applied across the clamping capacitor, which can significantly reduce the instantaneous inrush current that the clamping capacitor needs to withstand, and reduce the voltage stress on the switching transistor in the switching circuit and the current stress on the active clamping branch.
[0089] This disclosure also provides a pre-charge control method for a power supply circuit, wherein the power supply circuit can be a power supply circuit according to various embodiments of this disclosure.
[0090] Figure 14 shows a flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure.
[0091] As shown in FIG14, the pre-charge control method of the power supply circuit according to an embodiment of the present disclosure includes step S110.
[0092] In step S110, during the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first switching device to control the speed at which the output voltage of the switch circuit module pre-charges the clamping capacitor.
[0093] In this disclosure, the pre-charge phase is a phase for pre-charging the clamping capacitor, during which the voltage of the clamping capacitor rises from 0 to the output voltage of the switching circuit module 110.
[0094] Figure 15 shows another flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure.
[0095] As shown in Figure 15, the pre-charge control method of the power supply circuit according to an embodiment of the present disclosure may further include step S120.
[0096] In step S120, during the output phase following the pre-charging phase, the switch control module applies a second control signal with a second duty cycle to the second switching device.
[0097] According to an embodiment of this disclosure, referring to FIG8, after the pre-charging of the clamping capacitor is completed and after a first delay, the switch control module begins to apply a second control signal to the second switching device.
[0098] According to embodiments of this disclosure, referring to Figures 9 and 12, during all or part of the pre-charging phase, the switch control module applies a second control signal to the second switching device.
[0099] Figure 16 shows another flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure.
[0100] As shown in FIG16, before step S110, the pre-charge control method of the power supply circuit according to the embodiment of the present disclosure may further include step S100.
[0101] In step S100, the first duty cycle is determined based on the capacitance of the clamping capacitor and the inrush current threshold of the second switching device.
[0102] According to embodiments of this disclosure, the first control signal may include one pulse width or may include multiple pulse widths. The pulse width of the first control signal may have a constant value, or it may have a value that varies within a certain range; for example, the pulse width of the first control signal may gradually increase.
[0103] Figure 17 shows another flowchart of a pre-charge control method for a power supply circuit according to an embodiment of the present disclosure.
[0104] As shown in FIG17, the pre-charge control method of the power supply circuit according to the embodiment of the present disclosure may further include step S130.
[0105] In step S130, during the output phase following the pre-charging phase, the switch control module applies a third control signal with a third duty cycle to the first switching device.
[0106] According to embodiments of this disclosure, the switching circuit module includes a transformer, and the first switching device includes a first switching device group and a second switching device group (see FIG. 4). The first switching device group constitutes a first bridge circuit, and the input voltage is applied to the primary side of the transformer via the first bridge circuit. The second switching device group constitutes a second bridge circuit, and the secondary side of the transformer provides the output voltage of the switching circuit module to the active clamping circuit module via the second bridge circuit.
[0107] According to an embodiment of the present disclosure, in the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first switching device (i.e., step S110) including: in the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first group of switching devices.
[0108] The pre-charge control method according to an embodiment of the present disclosure may further include: during the pre-charge phase, the switch control module applies a fourth control signal having a fourth duty cycle to the second switch device group.
[0109] The pre-charge control method according to embodiments of the present disclosure may further include: in the output stage after the pre-charge stage, the switch control module applies a third control signal having a third duty cycle to the first switch device group and applies a fifth control signal having a fifth duty cycle to the second switch device group.
[0110] According to embodiments of this disclosure, the first switching device includes a main switching device and a freewheeling switching device (see FIG13). When the main switching device is turned on, the freewheeling switching device is turned off, and the output voltage of the switching circuit module is provided to the active clamping circuit module via the main switching device; when the main switching device is turned off, the freewheeling switching device is turned on, and the output voltage of the switching circuit module is provided to the active clamping circuit module via the freewheeling switching device.
[0111] According to an embodiment of the present disclosure, in the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first switching device (i.e., step S110) including: in the pre-charging phase, the switch control module applies the first control signal with a first duty cycle to the main switching device.
[0112] The pre-charge control method according to embodiments of the present disclosure may further include: during the pre-charge phase, the switch control module applies a fourth control signal having a fourth duty cycle to the freewheeling switch device.
[0113] The pre-charge control method according to embodiments of the present disclosure may further include: in the output stage after the pre-charge stage, the switch control module applies a third control signal with a third duty cycle to the main switch device and applies a fifth control signal with a fifth duty cycle to the freewheeling switch device.
[0114] The pre-charge control method for the power supply circuit according to the embodiments of the present disclosure can be used to control the pre-charge of the clamping capacitor in the power supply circuit according to the various embodiments of the present disclosure, and obtain the corresponding technical effects, which will not be elaborated here.
[0115] This disclosure has disclosed exemplary embodiments, and although specific terminology has been used, it is for general illustrative purposes only and should not be construed as limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of this disclosure as set forth by the appended claims.
Claims
1. A power supply circuit, comprising: The module includes a switching circuit module, an active clamping circuit module, and a switching control module. The switching circuit module includes a first switching device, an input voltage is applied to the input terminal of the switching circuit module, and the output terminal of the switching circuit module is connected to the input terminal of the active clamping circuit module. The active clamping circuit module includes a clamping capacitor, and the output voltage of the switching circuit module is used to charge the clamping capacitor. The switch control module is connected to the control terminal of the first switch device. In the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first switch device to control the speed at which the output voltage of the switch circuit module pre-charges the clamping capacitor. The pre-charging phase is a phase in which the voltage of the clamping capacitor rises from 0 to the output voltage of the switch circuit module.
2. The power supply circuit according to claim 1, wherein, The active clamping circuit module also includes a second switching device connected in series with the clamping capacitor. The switch control module is connected to the control terminal of the second switch device. In the output phase following the pre-charging phase, the switch control module applies a second control signal with a second duty cycle to the second switch device.
3. The power supply circuit according to claim 2, wherein, After the pre-charging of the clamping capacitor is completed and after a first delay, the switch control module begins to apply the second control signal to the second switching device.
4. The power supply circuit according to claim 2, wherein, During all or part of the pre-charging phase, the switch control module applies the second control signal to the second switching device.
5. The power supply circuit according to claim 2, wherein, The first duty cycle is determined based on the capacitance of the clamping capacitor and the inrush current threshold of the second switching device.
6. The power supply circuit according to claim 1, wherein, The switching circuit module further includes a transformer, and the first switching device includes a first switching device group and a second switching device group. The first group of switching devices forms a first bridge circuit, and the input voltage is applied to the primary side of the transformer via the first bridge circuit. The second group of switching devices constitutes a second bridge circuit or a full-wave rectifier circuit, and the secondary side of the transformer provides the output voltage of the switching circuit module to the active clamping circuit module via the second bridge circuit or the full-wave rectifier circuit. During the pre-charging phase, the switch control module applies a first control signal with the first duty cycle to the first switch device group.
7. The power supply circuit according to claim 6, wherein, During the pre-charging phase, the switch control module applies a fourth control signal with a fourth duty cycle to the second group of switching devices.
8. The power supply circuit according to claim 6 or 7, wherein, In the output phase following the pre-charging phase, the switch control module applies a third control signal with a third duty cycle to the first switch device group and a fifth control signal with a fifth duty cycle to the second switch device group.
9. The power supply circuit according to claim 1, wherein, The first switching device includes a main switching device and a freewheeling switching device. When the main switching device is turned on, the freewheeling switch is turned off, and the output voltage of the switching circuit module is supplied to the active clamping circuit module via the main switching device. When the main switching device is off, the freewheeling switch is on, and the output voltage of the switching circuit module is supplied to the active clamping circuit module via the freewheeling switch. During the pre-charging phase, the switch control module applies a first control signal with the first duty cycle to the main switch device and a fourth control signal with the fourth duty cycle to the freewheeling switch device.
10. The power supply circuit according to claim 9, wherein, In the output phase following the pre-charging phase, the switch control module applies a third control signal with a third duty cycle to the main switch device and a fifth control signal with a fifth duty cycle to the freewheeling switch device.
11. The power supply circuit according to claim 1 further includes a filter circuit module, wherein, The active clamping circuit module is connected between the switching circuit module and the filtering circuit module, and outputs the first output voltage of the power supply circuit via the filtering circuit module during the output phase after the pre-charging phase.
12. The power supply circuit according to claim 11, wherein, During the pre-charging phase, a second output voltage of the power supply circuit is output via the filter circuit module, and the second output voltage is less than the first output voltage.
13. The power supply circuit according to claim 12, wherein, The pre-charging phase includes a first time period and a second time period. During the first time period, the output voltage of the power supply circuit rises from 0 to the second output voltage. During the second time period, the output voltage of the power supply circuit remains at the second output voltage.
14. The power supply circuit according to claim 12, wherein, The pre-charging phase includes a first time period, a second time period, and a third time period. During the first time period, the output voltage of the power supply circuit rises from 0 to the second output voltage. During the second time period, the output voltage of the power supply circuit remains at the second output voltage. During the third time period, the output of the power supply circuit starts to rise from the second output voltage and rises to the first output voltage during the output phase.
15. A pre-charge control method for a power supply circuit, the power supply circuit comprising: The system comprises a switching circuit module, an active clamping circuit module, and a switching control module. The switching circuit module includes a first switching device. An input voltage is applied to the input terminal of the switching circuit module, and the output terminal of the switching circuit module is connected to the input terminal of the active clamping circuit module. The active clamping circuit module includes a clamping capacitor, and the output voltage of the switching circuit module is used to charge the clamping capacitor. The switching control module is connected to the control terminal of the first switching device. The method includes: During the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first switch device to control the speed at which the output voltage of the switch circuit module pre-charges the clamping capacitor. The pre-charging phase is a phase in which the voltage of the clamping capacitor rises from 0 to the output voltage of the switch circuit module.
16. The pre-charge control method according to claim 15, wherein, The active clamping circuit module further includes a second switching device connected in series with the clamping capacitor. The switch control module is connected to the control terminal of the second switching device. Before the switch control module applies a first control signal with a first duty cycle to the first switching device, the method further includes: The first duty cycle is determined based on the capacitance of the clamping capacitor and the inrush current threshold of the second switching device.
17. The pre-charge control method according to claim 16, further comprising: In the output phase following the pre-charging phase, the switch control module applies a second control signal with a second duty cycle to the second switching device.
18. The pre-charge control method according to claim 17, wherein, After the pre-charging of the clamping capacitor is completed and after a first delay, the switch control module begins to apply the second control signal to the second switching device.
19. The pre-charge control method according to claim 17, further comprising: During all or part of the pre-charging phase, the switch control module applies the second control signal to the second switching device.
20. The pre-charge control method according to claim 15, wherein, The switching circuit module further includes a transformer, and the first switching device includes a first switching device group and a second switching device group. The first group of switching devices forms a first bridge circuit, and the input voltage is applied to the primary side of the transformer via the first bridge circuit. The second group of switching devices constitutes a second bridge circuit or a full-wave rectifier circuit, and the secondary side of the transformer provides the output voltage of the switching circuit module to the active clamping circuit module via the second bridge circuit or the full-wave rectifier circuit. During the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first switching device, including: During the pre-charging phase, the switch control module applies the first control signal having the first duty cycle to the first switch device group.
21. The pre-charge control method according to claim 20, further comprising: During the pre-charging phase, the switch control module applies a fourth control signal with a fourth duty cycle to the second group of switching devices.
22. The pre-charge control method according to claim 20 or 21, further comprising: In the output phase following the pre-charging phase, the switch control module applies a third control signal with a third duty cycle to the first switch device group and a fifth control signal with a fifth duty cycle to the second switch device group.
23. The pre-charge control method according to claim 15, wherein, The first switching device includes a main switching device and a freewheeling switching device. When the main switching device is turned on, the freewheeling switch is turned off, and the output voltage of the switching circuit module is supplied to the active clamping circuit module via the main switching device. When the main switching device is off, the freewheeling switch is on, and the output voltage of the switching circuit module is supplied to the active clamping circuit module via the freewheeling switch. During the pre-charging phase, the switch control module applies a first control signal with a first duty cycle to the first switching device, including: During the pre-charging phase, the switch control module applies a first control signal with the first duty cycle to the main switch device. The method further includes: During the pre-charging phase, the switch control module applies a fourth control signal with a fourth duty cycle to the freewheeling switch device.
24. The pre-charge control method according to claim 23, further comprising: In the output phase following the pre-charging phase, the switch control module applies a third control signal with a third duty cycle to the main switch device and a fifth control signal with a fifth duty cycle to the freewheeling switch device.