Driving circuit of switching device, and switching power supply

Abstract

To provide a driving circuit of a switching device configured to suppress electromagnetic interference and noise, avoid ringing in the circuit, and reduce the risk of breakdown to the switching device, and a switching power supply.SOLUTION: A driving circuit for a switching device is provided. The driving circuit comprises a pulse width modulation circuit and a waveform conversion circuit. An output terminal of the pulse width modulation circuit is connected to an input terminal of the waveform conversion circuit, and an output terminal of the waveform conversion circuit is connected to a control terminal of the switching device. The waveform conversion circuit comprises a resistor-capacitor series circuit, the pulse width modulation circuit is configured to output a level pulse signal for turning on the switching device, and the resistor-capacitor series circuit is configured to reduce an edge slope of the level pulse signal.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Cross - reference to related applications This application claims priority to Chinese Patent Application No. 202323241429.3, filed with the National Intellectual Property Administration on November 29, 2023, entitled "Switching Power Supply".

[0002] This application relates to a drive circuit, and more specifically to a drive circuit for a switching element and a switching power supply.

Background Art

[0003] In high-speed switching applications, it is necessary to quickly switch a switching element from an off state to an on state, or from an on state to an off state. Due to such a rapid switching process, capacitors, inductances, resistances, etc. inside the switching element of the pa Lamer (e.g., regulation parameters) become important.

[0004] In a general drive circuit for a switching element, the switching element itself of the pa causes electromagnetic interference and noise by generating high-frequency oscillation at the moment of turning on the switching element in high-speed switching applications, forming ringing in the drive waveform, and there is a risk of destroying the switching element with excessive spike voltage.

Summary of the Invention

Means for Solving the Problems

[0005] This application is provided to solve at least one of the above problems. One aspect of this application In this case, a switching power supply is provided. The switching power supply includes a drive circuit for a switching element. The dri The drive circuit is pulse width modulation circuit and a waveform conversion circuit includes. The output end of the pulse width modulation unit is connected to the input end of the waveform conversion circuit, and the output end of the waveform conversion circuit is connected to the control end of the switching element is. The waveform conversion circuit includes a resistor-capacitor series circuit includes The pulse width modulation unit turns on the switching element of the le Outputs a bell pulse signal is configured to, the resistance-capacitor series circuit is the former recorded le Reduce the edge slope of the bell pulse signal is configured as .

[0006] One of the present application example of In, the resistance-capacitor series circuit includes a first resistor and a first capacitor includes , the first end of the first resistor is connected to the output end of the pulse width modulation circuit , the second end of the first resistor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the control end of the switching element.

[0007] One of the present application example of In, The switching power supply includes a second waveform conversion circuit. The second waveform conversion circuit includes a second resistor. The second resistor is a second resistor connected in parallel across both ends of the resistance-capacitor series circuit includes um.

[0008] In one example of the present application, the second resistor is connected in parallel across both ends of the resistor - capacitor series circuit. When the resistor - capacitor series circuit smoothes and delays a high - level pulse signal, a part of the voltage divided by the second voltage drops across the second resistor.

[0009] One of the present application example of In, The switching power supply includes a third waveform conversion circuit. The third waveform conversion circuit includes a discharge circuit. The discharge circuit Connected in parallel across both ends of the first resistor is .

[0010] One of the present application example of In, the discharge circuit includes a first diode and a third resistor includes , the negative terminal of the first diode is connected to the first end of the first resistor, the positive terminal of the first diode is connected to the first end of the third resistor, and the second end of the third resistor is connected to the second end of the first resistor.

[0011] One of the present application example of In, the pulse width modulation circuit is , the Output a second-level pulse signal to turn off the switching element is further configured to , the second-level pulse signal discharges through the discharge circuit, and the level value of the first-level pulse signal is higher than the level value of the second-level pulse signal.

[0012] One of the present applications example of In this case, the input terminal of the pulse width modulation circuit is connected to an external power supply device.

[0013] One of the present applications example of In this case, the output terminal of the switching element is connected to a constant voltage input device, and the ground terminal of the pulse width modulation circuit and the input terminal of the switching element are connected to a ground node.

[0014] One of the present applications example of In this case, the switching element is a metal oxide semiconductor field effect transistor.

[0015] In one example of the present application, the switching element is any one of MOSFET, JFET, and IGBT.

[0016] In one example of the present application, the gate of the switching element functions as a control terminal, and the ground terminal of the pulse - width modulation circuit and the source of the switching element Q0 are connected to a ground node.

[0017] In one example of the present application, the pulse - width modulation circuit is a PWM controller.

[0018] Another aspect of the present application In this case, a switching power supply is provided. The switching power supply includes a drive circuit for the switching element according to any one of the above.

[0019] The present application example of According to the drive circuit for the switching element and the switching power supply according to the present application, a high-level pulse signal is smoothed and delayed by a resistor-capacitor series circuit, and the edge slope of the high-level pulse signal is reduced can be done, and that Thereby, the frequency component of the high-level pulse signal can be reduced, the smooth transition of the drive signal at the control terminal can be ensured, high-frequency oscillation due to an overly high turn-on speed can be avoided, electromagnetic interference and noise can be improved, the formation of ringing in the circuit can be avoided, and the risk of breaking the switching element break can also be reduced.

[0020] The above and other objects, features, and advantages of the present application will become clearer attached by referring to the drawings and explaining the present application example of in more detail.attached The drawings are for providing a further understanding of the present application example of and form a part of the specification, and are for interpreting the present application together with the present application, and are not intended to limit the present application. In the drawings, the same reference numerals generally represent the same components or steps. example of

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0022] In the following description, a large number of specific details are provided in order to understand the present application more thoroughly. However, it is clear to those skilled in the art that the present application can be implemented without one or more of these details. In other instances, some technical features known in the art are not described in order to avoid confusion with the present application.

[0023] It should be noted that the present application can be implemented in various forms and should not be construed as being limited to those provided in this specification. On the contrary, by providing these example done the disclosure is made thorough and complete, and the scope of the present application is fully conveyed to those skilled in the art. In the drawings, for clarity, the sizes and relative sizes of layers and regions may be exaggerated. The same reference numerals consistently represent the same elements. example of

[0024] The terms used in this specification are specific example of ​​This is only for the purpose of explanation and does not limit the present application. As used in this specification, the singular forms "a", "an", and "the" are also intended to include the plural form unless the context clearly dictates otherwise. The terms "comprising" and / or "including" when used in this specification, while determining the presence of features, integers, operations, elements, and / or components, do not preclude the presence or addition of one or more other features, integers, operations, elements, components, and / or groups. As used in this specification, the term "and / or" includes any and all combinations of related items.

[0025] In the drive circuit of a general switching element, due to the parasitic parameters of the switching element itself, in high-speed switching applications, at the moment when the switching element is turned on, its gate voltage rapidly increases, and the charges of the gate-drain capacitor and the gate-source capacitor are rapidly accumulated. In this process, since the voltage and current change rapidly, high-frequency components are generated inside the switching element. Also, it affects the drain inductance and source inductance of the switching element, as well as the inductance between conductors. These inductances, together with the capacitor, form a resonant circuit inside the switching element may occur and generate high-frequency oscillation at the moment of turning on is. These high-frequency oscillations cause rapid changes in voltage and current inside the switching element may occur, and as a result which cause electromagnetic interference and noise, and generate periodic oscillation in the circuit to form ringing is. Furthermore, There is a risk that excessive spike voltage may damage the switching element.

[0026] FIG. 1 is , the a schematic configuration diagram of the drive circuit of the switching element. In FIG. 1, the drive circuit 100 includes a pulse width modulation unit 110 and a resistor R0 includes. The input terminal of the pulse width modulation unit 110 i is connected to an external power supply device is.The output terminal of the pulse width modulation unit 110 is connected to the first terminal of the resistor R0, the second terminal of the resistor R0 is connected to the gate G of the switching element Q0, and the ground terminal of the pulse width modulation unit 110 and the source S of the switching element Q0 are connected to the ground node.

[0027] In this drive circuit 100, it is not appropriate for the pulse signal output from the pulse width modulation unit 110 to directly drive the gate G of the switching element Q0. Since the rise time of the pulse signal may be very short, when turning on the switching element Q0 (e.g., connect) rapid changes in voltage and current are generated instantaneously, causing electromagnetic interference and noise. drive circuit 100 to in periodic vibration is forming ringing may occur. Furthermore When turned off, the switching element Q0 is is subject to interference accidentally and is likely to turn on is made easily, and the off-time of the switching element Q0 is, relatively is long.

[0028] To thoroughly understand the present application, the technical means according to the present application will be described by providing a detailed structure in the following description. The present application example of will be described in detail as follows. In addition to these detailed descriptions, the present application may have other embodiments.

[0029] Hereinafter, with reference to FIG. 2, a drive circuit for a switching element according to one example of aspect of the present application will be described. As shown in FIG. 2, the drive circuit 200 for the switching element (e.g., switching element 260) includes a pulse width modulation unit 210 and a waveform conversion circuit 220 includes. The input terminal of the pulse width modulation unit 210 is connected to an external power supply device is configured to The output terminal of the pulse width modulation unit 210 is connected to the input terminal of the waveform conversion circuit 220, and the output terminal of the waveform conversion circuit 220 is connected to the control terminal of the switching element Q1 is The waveform conversion circuit 220 includes a resistor-capacitor series circuit (also referred to as an RC series circuit) includes, the pulse width modulation unit 210 outputs a first-level pulse signal for turning on the switching element is configured to , the resistor-capacitor series circuit reduces the edge slope (e.g., edge rate) of control (e.g., the first-level pulse signal ) and is configured as such. Controlling the edge slope involves controlling the rate at which a signal transitions between its high - voltage level and low - voltage level. Specifically, it may involve changing the sharpness or steepness of the rising edge and falling edge of a pulse.

[0030] The pulse width modulation unit 210 generates a pulse width modulation (abbreviated as Pulse Width Modulation, PWM) signal configured as one or more electronic component (e.g., timer, resistor, capacitor, diode) includes , adjusts the width of the pulse signal based on the comparison result between the input signal and the clock signal and thereby , and controls is the output signal does .

[0031] In one example, the pulse width modulation unit 210 may be a PWM controller, but is not limited thereto 。1 In one example, the PWM signal output from the pulse width modulation unit 210 is a square wave of high level and low level It can be. High-level and low-level square waves can be with two stable alternating levels composed , generally, one high-level pulse signal and one low-level pulse signal are , forming a waveform similar to a square done The time lengths of the high-level pulse signal and the low-level pulse signal depend on the duty ratio of the square wave can be The high-level pulse signal is called the first-level pulse signal may be , and the low-level pulse signal may also be called the second-level pulse signal resulting in When the PWM signal output from the pulse width modulation unit 210 is a high-level pulse signal, the voltage at the control terminal of the switching element Q1 increases and thereby , and the switching element Q1 turns on done When the PWM signal output from the pulse width modulation unit 210 is a low-level pulse signal, the voltage at the control terminal of the switching element Q1 decreases and thereby , and the switching element Q1 turns off.

[0032] In one example, the pulse width modulation unit 210 outputs a high-level pulse signal done , and the high-level pulse signal passes through an RC series circuit when . Due to the charge and discharge characteristics of the capacitor in the RC series circuit, the high-level pulse signal is is smoothed done and and delayed transformed . thereby The edge slope of the high-level pulse signal is gradually reduced, thereby 、 reducing the frequency components of the high-level pulse signal, ensuring the smooth transition of the drive signal at the control end, avoiding high-frequency oscillation caused by an overly high turn-on speed, avoiding the generation of electromagnetic interference and noise, avoiding the formation of ringing in the circuit, and reducing the risk of damaging the switching element Q1 a .

[0033] Based on this, the present application provides a drive circuit 200 for a switching element that can perform waveform conversion on a PWM signal description . According to the drive circuit 200 of the switching element of the present application, the RC series circuit smooths the high-level pulse signal and and delays transformed , reduces the edge slope of the high-level pulse signal let, thereby , reduces the frequency components of the high-level pulse signal, ensures the smooth transition of the drive signal at the control end, avoids high-frequency oscillation caused by an overly high turn-on speed, improves electromagnetic interference and noise, avoids the formation of ringing in the circuit, and reduces the risk of damaging the switching element Q1 is .

[0034] In one example, the switching element Q1 may be, but is not limited to, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a JFET (Junction Field-Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), etc. Correspondingly, the control terminal may be the gate G of a switching element such as a MOSFET, a JFET, or an IGBT.

[0035] In one example, the input terminal of the pulse width modulation unit 210 is connected to an external power supply device. configured as follows The external power supply device is supplies power to the pulse width modulation unit 210. done , thereby The pulse width modulation unit 210 is outputs a PWM signal. The external power supply device may be, but is not limited to, a power supply, a power supply circuit, etc. battery

[0036] In one example, the output terminal of the switching element Q1 is connected to a constant voltage input device. configured as follows Thereby, after receiving the PWM signal input from the pulse width modulation unit 210, the switching element Q1 uses its own on and off states to stably output a voltage, and is used in application scenarios where it is necessary to stably output a voltage, such as power supply, DC-DC converter, etc. The constant voltage input device may be, but is not limited to, a constant voltage circuit, an electronic component that requires a constant voltage input, etc.

[0037] M For field effect transistors such as OSFET and JFET, the output terminal may be the drain D of the field effect transistor. For IGBT, the collector is the output terminal of the IGBT and bears the conduction. For other types of switching elements, the determination of its output terminal can be similar to the above description and will not be elaborated here.

[0038] In one example, as shown in FIG. 2, the ground terminal of the pulse width modulation unit 210 and the input terminal of the switching element Q1 are connected to the ground node.

[0039] M For field effect transistors such as MOSFETs and JFETs, the output terminal may be the source S of the field effect transistor. For IGBTs, the emitter is the input terminal of the IGBT. For other types of switching elements, the determination of their input terminals can be similar to the above description and will not be elaborated here.

[0040] In one example, as shown in FIG. 2, the resistor-capacitor series circuit includes a first resistor R1 and a first capacitor C1. done The first terminal of the first resistor R1 is connected to the output terminal of the pulse width modulation unit 210, the second terminal of the first resistor R1 is connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is connected to the control terminal of the switching element Q1. The on-branch circuit composed of the first resistor R1 and the first capacitor C1 can provide a maximum transient current.

[0041] Specifically, when the pulse width modulation unit 210 outputs a high-level pulse signal, the first capacitor C1 can perform smoothing and delay processing on the high-level pulse signal to generate a voltage signal with a slow rise. This voltage signal is input from the output terminal of the RC series circuit to the gate G of the switching element Q1 as the drive signal of the gate G of the switching element Q1. Thereby, the edge slope of the high-level pulse signal is gradually changed according to the charge and discharge characteristics of the first capacitor C1, and the on-speed of the switching element Q1 is reduced, so as to avoid high-frequency oscillation in the switching element Q1, effectively reduce the power consumption and noise of the switching element Q1, and improve the stability and efficiency of the drive circuit 200.

[0042] The first resistor R1 can play a role in limiting the current in a resistor-capacitor series circuit. When the pulse width modulation unit 210 outputs a high-level pulse signal, the gate capacitor of the switching element Q1 starts to charge, and by limiting the magnitude of the charging current with the first resistor R1, an excessive current impact on the gate G of the switching element Q1 is avoided, contributing to protecting the switching element Q1 and the drive circuit 200 from excessive current impact and damage.

[0043] In one example, The drive circuit 200 includes a second diameter deformation circuit 230, and the second Waveform conversion circuit circuit is the further includes a second resistor R2 seen, and the second resistor R2 is connected in parallel across both ends of the resistor-capacitor series circuit The on-branch circuit composed of the second resistor R2 can provide a minimum static current.

[0044] Specifically, the first end of the second resistor R2 is respectively connected to the output end of the pulse width modulation unit 210 and connected to the output terminal of the pulse width modulation unit the first end of the first resistor R1 and and the second end of the second resistor R2 is respectively connected to the gate G of the switching element Q1 and connected to the first capacitor the second end of the first capacitor C1 and and is connected thereto.

[0045] Since the second resistor R2 is connected in parallel across both ends of the RC series circuit, when the RC series circuit performs smoothing and delay processing on the high-level pulse signal, due to the voltage division effect of the second resistor R2, part of the voltage is allocated to the second resistor R2, thereby further slowing down the rising and falling speeds of the drive signal of the gate G, further reducing the switching speed of the switching element Q1, and improving the stability and efficiency of the drive circuit 200 can be .

[0046] Also, by connecting the first resistor R1 and the second resistor R2 in parallel, the overall resistance value of the waveform conversion circuit 220 can be reduced, so that a charging current large enough to raise the voltage between the gate G and the source S of the switching element Q1 to a desired value can be provided.

[0047] In one example, the waveform conversion circuit 220equipped with a third waveform conversion circuit 240, and the third waveform feedback circuit 240 Further, a discharge circuit equipped, and the discharge circuit is connected in parallel across both ends of the first resistor R1 When the pulse width modulation unit 210 outputs a low-level pulse signal to turn off the switching element Q1, the low-level pulse signal can be discharged by the discharge circuit.

[0048] In one example, as shown in FIG. 2, the discharge circuit includes a first diode D1 and a third resistor R3, and the negative terminal of the first diode D1 is connected to the output terminal of the pulse width modulation unit 210 connected to the first end of the first resistor R1, the positive terminal of the first diode D1 is connected to the first end of the third resistor R3, and the second end of the third resistor R3 is connected to the second end of the first resistor R1 connected to the first capacitor.

[0049] Specifically, the first diode D1 and the third resistor R3 can constitute a negative voltage rapid discharge circuit. When the switching element Q1 is turned off, the on characteristic of the first diode D1 provides a low-impedance path, which can so, thereby rapidly discharge the capacitor between the gate G and the source S of the switching element Q1, accelerate the switching speed of the switching element Q1, and avoid the risk that the parasitic capacitor and the inductance form a resonant circuit. avoid, thereby reduce the integral sum of the current and voltage superposition regions, effectively shorten the off time, and reduce the off loss. And the negative voltage rapid discharge circuit composed of the first diode D1 and the third resistor R3 and can effectively avoid the situation that the switching element Q1 is turned on erroneously due to external interference.

[0050] Also, the third resistor R3 provides a certain resistance value to the negative voltage discharge circuit done, thereby to avoid the risk of burnout due to excessive current when the pulse width modulation unit 210 is turned off.

[0051] Another aspect of the present application in, the A driving circuit for an itching element A switching power supply is provided .

[0052] The drive circuit of the switching element is realized as the above-described drive circuit 200 of the switching element, and the above description can be referred to, and the description will not be repeated here. not repeated 。

[0053] A switched-mode power supply (SMPS) is a highly efficient power supply device that can convert an input power supply into a stable output power supply, and is commonly found in various electronic devices (such as computers, mobile phone chargers, LED lamps, televisions, etc.) and power systems. Compared with conventional linear power supplies, switching power supplies have high energy conversion efficiency, small volume and weight, and better power adjustment performance.

[0054] The basic operating principle of a switching power supply is to periodically turn on and off a switching element to convert the DC current (DC) or AC current (AC) of the input power supply into a high-frequency pulse signal, The high-frequency pulse signal and then convert it into a stable output voltage or current by components such as filters and transformers.

[0055] As described above , the According to the drive circuit of the switching element and the switching power supply, a resistor-capacitor series circuit is used to smooth and delay the high-level pulse signal, reduce the edge slope of the high-level pulse signal, reduce the frequency components of the high-level pulse signal, ensure the smooth transition of the drive signal at the control end, avoid high-frequency oscillation caused by too high an on speed, improve electromagnetic interference and noise, avoid the formation of ringing in the circuit, and reduce the risk of damaging the switching element.

[0056] Exemplary embodiments have been described in this specification with reference to the accompanying drawings, but the above exemplary exampleIt should be understood that these are merely exemplary and are not intended to limit the scope of the present application. Those skilled in the art can make various changes and modifications to this specification without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as defined by the appended claims.

[0057] Similarly, for the purpose of simplifying the present application and facilitating understanding of one or more of the various applications, in the exemplary example description of the present application, it should be understood that various features of the present application may be grouped together in a single example , figure, or description thereof. However, the method of the present application should not be construed as reflecting the following intention. That is, the present application seeking protection requires more features than those clearly described in each claim. More specifically, as reflected in the corresponding claims, the filing point is that the corresponding technical problem can be solved using fewer features than all the features of a single example disclosure. Therefore, the scope of the claims according to the specific embodiments is hereby clearly incorporated into the specific embodiments, and each claim itself is a separate example of the present application.

[0058] Also, those skilled in the art will understand that some of the examples described in this specification include some features that are not other features but other example features, but different example combinations of features are within the scope of the present application and mean forming different example . For example, in the claims, any example seeking protection can be used in any combination manner.

[0059] Note that the above example does not limit the present application but explains the present application. Those skilled in the art can make alternative examplecan be designed. In the claims, any reference signs in parentheses shall not be construed as limiting the claims. The use of the words first, second, third, etc. does not indicate any order. These words can be construed as names.

Claims

1. A driving circuit for a switching element, A pulse width modulation section and a waveform conversion circuit are included. an output terminal of the pulse width modulation unit is connected to an input terminal of the waveform transformation circuit, and an output terminal of the waveform transformation circuit is connected to a control terminal of the switching element; the waveform conversion circuit includes a resistor-capacitor series circuit, the pulse width modulation unit outputs a first level pulse signal that turns on the switching element, and the resistor-capacitor series circuit lowers an edge slope of the first level pulse signal.

2. 2. The drive circuit of claim 1, wherein the resistor-capacitor series circuit includes a first resistor and a first capacitor, a first end of the first resistor is connected to an output end of the pulse width modulation section, a second end of the first resistor is connected to a first end of the first capacitor, and a second end of the first capacitor is connected to a control end of the switching element.

3. 2. The drive circuit according to claim 1, wherein the waveform conversion circuit further includes a second resistor connected in parallel to both ends of the resistor-capacitor series circuit.

4. 3. The drive circuit according to claim 2, wherein the waveform conversion circuit further includes a discharge circuit connected in parallel across the first resistor.

5. 5. The drive circuit of claim 4, wherein the discharge circuit includes a first diode and a third resistor, a negative terminal of the first diode is connected to a first terminal of the first resistor, a positive terminal of the first diode is connected to a first terminal of the third resistor, and a second terminal of the third resistor is connected to a second terminal of the first resistor.

6. 5. The drive circuit according to claim 4, wherein the pulse width modulation unit further outputs a second level pulse signal that turns off the switching element, the second level pulse signal discharges through the discharge circuit, and a level value of the first level pulse signal is higher than a level value of the second level pulse signal.

7. 2. The driving circuit according to claim 1, wherein an input terminal of the pulse width modulation unit is connected to an external power supply device.

8. 2. The drive circuit according to claim 1, wherein an output terminal of the switching element is connected to a constant voltage input device, and a ground terminal of the pulse width modulation section and an input terminal of the switching element are connected to a ground node.

9. 2. The drive circuit according to claim 1, wherein the switching element is a metal oxide semiconductor field effect transistor.

10. A switching power supply comprising the drive circuit according to any one of claims 1 to 9.

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