LC resonance suppression push-pull circuit and full-bridge circuit
Patent Information
- Application Number
- CN202510159023.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2025-05-23
AI Technical Summary
In power electronic circuits, high-frequency switching devices such as MOSFETs are turned on and off due to LC resonance caused by junction capacitors and PCB wiring inductors, resulting in unsatisfactory output waveform, accompanied by severe oscillation, affecting subsequent PWM modulation and final output quality.
By connecting the LC resonance suppression device in a push-pull circuit, specifically a series resistor between the drain and the high-level terminal of the MOSFET, and a series resistor between the source and the ground terminal, to block or weaken the energy source of the LC resonance.
It effectively suppresses LC resonance phenomenon, improves the quality of output electrical energy, reduces output burrs, and avoids device damage and electrical equipment failures caused by burrs.
Smart Images
Figure CN120033960A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a resonance suppression push-pull circuit and a full-bridge circuit, belonging to the technical field of power electronics. Background Art
[0002] In power electronic circuits, high-frequency switching devices are usually used for power modulation. For example, four high-frequency switching tubes are used as the main devices to form a full-bridge circuit during DC-DC or inverter conversion. The high-frequency switching device requires a corresponding drive module to turn on or off the switching device. The drive module is generally composed of a corresponding drive chip, and the switching device generally uses power electronic power switching devices such as MOSFET or IGBT.
[0003] In controlling the on and off of MOSFET, the ideal model is that the control source outputs a high level to immediately turn on the MOSFET, or outputs a low level to immediately turn off the MOSFET. However, in actual MOSFET devices, there is junction capacitance, that is, there is a capacitance response between the three pins of MOSFET, G (gate), D (drain), and S (source), which is called junction capacitance. The junction capacitance exists between GS / DS / DG, and the PCB wiring connecting the control source to the MOSFET drive circuit will introduce inductance effects. Under the influence of these capacitive inductance effects, the waveforms when the MOSFET is actually turned on and off are very unsatisfactory, and are accompanied by strong LC resonance.
[0004] like Figure 1 In the push-pull circuit of the upper and lower bridge arms shown in the figure, the control source outputs a pair of complementary PWM signals (with dead zones) to drive a pair of push-pull MOSFETs of the upper and lower bridge arms. Ideally, the waveform at the output point should be a 90V square wave. In fact, the output waveform is not an ideal square wave, but a waveform with severe oscillation. There is a severe oscillation phenomenon at the rising or falling edge of the square wave. This oscillation will have a serious impact on the subsequent PWM modulation. Whether it is used for inverter or DC-DC isolated conversion circuits, such oscillation often makes the final output very unsatisfactory. However, in power electronic circuits, this oscillation is indeed ubiquitous, causing serious failure of product design.
[0005] The source of this oscillation is the LC resonance caused by the MOSFET junction capacitance and the PCB wiring inductance. The equivalent circuit is as follows: Figure 2As shown in the figure, when Q1 is turned off and Q2 is turned on immediately, there is actually a junction capacitance C between the GD of Q1, and there is a certain inductance effect in the PCB wiring between the 90V positive pole and Q1 and Q2, which is equivalent to forming a discharge loop between 90V and -8V, with C and the PCB wiring inductance connected in series in the middle, forming an LC resonant oscillation in an instant, which is formed in the process of the output square wave jumping from 0V to 90V. Similarly, there will be symmetrical oscillation when the output square wave jumps from 90V to 0V. Summary of the invention
[0006] In view of the above-mentioned defects of the prior art, the task of the present invention is to provide an LC resonance suppression push-pull circuit, the purpose of which is to avoid the oscillation problem that occurs during the rising edge or falling edge jump process. Another task of the present invention is to provide a full-bridge circuit that can suppress the oscillation generated during the rising edge or falling edge jump process.
[0007] The technical solution of the present invention is as follows: an LC resonance suppression push-pull circuit, comprising a first power electronic power switch device and a second power electronic power switch device connected in a push-pull form, the gates of the first power electronic power switch device and the second power electronic power switch device are respectively connected to a control circuit, the control circuit comprises a driving chip, the output end of the driving chip is the output end of the control circuit for controlling the first power electronic power switch device and the second power electronic power switch device, a first LC resonance suppression device is connected in series between the drain of the first power electronic power switch device and the high level end of the circuit, and a second LC resonance suppression device is connected in series between the source of the second power electronic power switch device and the ground end of the circuit.
[0008] Furthermore, the first LC resonance suppression component and the second LC resonance suppression component are resistors.
[0009] Furthermore, the resistance is no greater than 100 ohms.
[0010] Furthermore, a third LC resonance suppression device is connected in series between the ground pin of the driving chip in the control circuit connected to the second power electronic power switch device and the low-level end of the circuit, and the first LC resonance suppression device, the second LC resonance suppression device and the third LC resonance suppression device are Schottky diodes.
[0011] Furthermore, the first power electronic power switch device and the second power electronic power switch device are MOSFET tubes.
[0012] Another technical solution of the present invention is a full-bridge circuit, comprising two of the aforementioned LC resonance suppression push-pull circuits.
[0013] Furthermore, the two LC resonance suppression push-pull circuits share a first LC resonance suppression component and a second LC resonance suppression component.
[0014] The advantages of the present invention compared with the prior art are: The present invention can suppress or block the energy source of LC resonance by adding an LC resonance suppression device, and when the power electronic power switch device is in high-frequency switching, the LC resonance is immediately stopped or weakened, which greatly improves the quality of output power and is also conducive to improving output burrs, and can avoid problems such as damage to electrical equipment due to burr breakdown of devices. At the same time, the circuit structure is simple, easy to implement, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 This is a push-pull circuit diagram of the prior art.
[0016] Figure 2 It is the LC resonance equivalent path diagram of the push-pull circuit in the prior art.
[0017] Figure 3 This is the LC resonance suppression push-pull circuit diagram of Example 1.
[0018] Figure 4 This is a schematic diagram of a full-bridge circuit formed by the LC resonance suppression push-pull circuit of Example 1.
[0019] Figure 5 This is the LC resonance suppression push-pull circuit diagram of Example 2.
[0020] Figure 6 This is a schematic diagram of a full-bridge circuit formed by the LC resonance suppression push-pull circuit of Example 2. DETAILED DESCRIPTION
[0021] The present invention will be further described below in conjunction with the embodiments, but are not intended to limit the present invention.
[0022] Example 1, please combine Figure 3 As shown, the LC resonance suppression push-pull circuit of this embodiment includes a first power electronic power switch device and a second power electronic power switch device connected in a push-pull form, wherein the first power electronic power switch device is a first MOSFET tube Q3, and the second power electronic power switch device is a second MOSFET tube Q4. In some embodiments, an IGBT can be used as a power electronic power switch device.
[0023] A first resistor R1 is connected in series between the drain of the first MOSFET tube Q3 and the high level end of the circuit, and the first resistor R1 serves as a first LC resonance suppression device. A source of the first MOSFET tube Q3 is connected to a drain of the second MOSFET tube Q4, and a second resistor R2 is connected in series between the source of the second MOSFET tube Q4 and the ground end of the circuit, and the second resistor R2 serves as a second LC resonance suppression device.
[0024] The gates of the first MOSFET tube Q3 and the second MOSFET tube Q4 are respectively connected to the control circuit 100, which includes a driver chip O. The control signal output by the MCU is isolated by an optical coupler and then connected to the positive pin of the driver chip O through the third resistor R3 as a control signal source. The control signal source is connected to the negative pin of the driver chip O through the fourth resistor R4 and the light-emitting diode L1 connected in series. The first capacitor C1 is connected between the positive pin and the negative pin of the driver chip O, and the negative pin of the driver chip O is grounded. The power pin of the driver chip O is connected to +15V, the ground pin of the driver chip O is connected to -8V, and the second capacitor C2 is connected between the power pin and the ground pin of the driver chip O. The output pin of the driver chip O is connected to the gate of the power electronic power switch device through the fifth resistor R5 as the output end of the control circuit 100.
[0025] Please combine Figure 4 As shown, a full-bridge circuit is formed by two LC resonance suppression push-pull circuits of this embodiment, and the control circuits of the two LC resonance suppression push-pull circuits are not shown. The drain of the first power electronic power switch device Q3_1 in the first LC resonance suppression push-pull circuit and the drain of the first power electronic power switch device Q3_2 in the second LC resonance suppression push-pull circuit are connected together to form a first common point A. The first resistor R1_1 in the first LC resonance suppression push-pull circuit is set between the first common point A and the drain of the first power electronic power switch device Q3_1 in the first LC resonance suppression push-pull circuit, and the first resistor R1_2 in the second LC resonance suppression push-pull circuit is set between the first common point A and the drain of the first power electronic power switch device Q3_2 in the second LC resonance suppression push-pull circuit. The first common point A is connected to the high-level end of the circuit.
[0026] The source of the second power electronic power switch device Q4_1 in the first LC resonance suppression push-pull circuit and the source of the second power electronic power switch device Q4_2 in the second LC resonance suppression push-pull circuit are connected together to form a second common point B. The second resistor R2_1 in the first LC resonance suppression push-pull circuit is arranged between the second common point B and the source of the second power electronic power switch device Q4_1 in the first LC resonance suppression push-pull circuit, and the second resistor R2_2 in the second LC resonance suppression push-pull circuit is arranged between the second common point B and the source of the second power electronic power switch device Q4_1 in the second LC resonance suppression push-pull circuit. The second common point B is connected to the circuit ground terminal.
[0027] It is easy to understand that in the above full-bridge circuit, the first resistor R1_1, R1_2 and the second resistor R2_1, R2_2 are respectively set in the two LC resonance suppression push-pull circuits. In some embodiments, the two LC resonance suppression push-pull circuits can also share the first resistor R1 and the second resistor R2, that is, the first resistor R1 is set between the first common point A and the high level end of the circuit, and the second resistor R2 is set between the second common point B and the ground end of the circuit.
[0028] This embodiment uses a resistor (first resistor R1 and second resistor R2) in series with the positive and negative poles of the main circuit to quickly consume the energy of LC resonance, which can achieve a good effect of suppressing LC resonance. In addition, the resistance of the first resistor R1 and the second resistor R2 cannot be too large (too large will affect the signal output, resulting in output signal deletion), generally less than 100 ohms. Since the first resistor R1 and the second resistor R2 are connected in series, the circuit of this embodiment is suitable for occasions with low output power. If the power is large, there will be a large voltage drop when the output current passes through the first resistor R1 and the second resistor R2, affecting the output voltage.
[0029] Example 2, please combine Figure 5 As shown, the LC resonance suppression push-pull circuit of this embodiment includes a first power electronic power switch device and a second power electronic power switch device connected in a push-pull form, wherein the first power electronic power switch device is a first MOSFET tube Q5, the second power electronic power switch device is a second MOSFET tube Q6, a first Schottky diode D1 is connected in series between the drain of the first MOSFET tube Q5 and the high level end of the circuit, and the first Schottky diode D1 serves as a first LC resonance suppression device. The source of the first MOSFET tube Q5 is connected to the drain of the second MOSFET tube Q6, a second Schottky diode D2 is connected in series between the source of the second MOSFET tube Q6 and the ground end of the circuit, and the second Schottky diode D2 serves as a second LC resonance suppression device.
[0030] The gates of the first MOSFET tube Q5 and the second MOSFET tube Q6 are respectively connected to the control circuit 200, and the control circuit 200 includes a driver chip O. The control signal output by the MCU is isolated by an optical coupler and is connected to the positive pin of the driver chip O through the third resistor R3 as a control signal source. The control signal source is connected to the negative pin of the driver chip O through the fourth resistor R4 and the light-emitting diode L1 connected in series. The first capacitor C1 is connected between the positive pin and the negative pin of the driver chip O, and the negative pin of the driver chip O is grounded. The power pin of the driver chip O is connected to +15V, the ground pin of the driver chip O is connected to -8V, and the second capacitor C2 is connected between the power pin and the ground pin of the driver chip O. The output pin of the driver chip O is connected to the gate of the power electronic power switch device through the fifth resistor R5 as the output end of the control circuit 200. In the control circuit 200 connected to the second power electronic power switch device, a third Schottky diode D3 is connected in series between the connection point between the ground pin of the driver chip O and the second capacitor C2 and -8V, and the third Schottky diode D3 serves as a second LC resonance suppression device.
[0031] Please combine Figure 6 As shown, a full-bridge circuit is formed by two LC resonance suppression push-pull circuits of the present embodiment, and the control circuits of the two LC resonance suppression push-pull circuits are not shown. The drain of the first power electronic power switch device Q5_1 in the first LC resonance suppression push-pull circuit and the drain of the first power electronic power switch device Q5_2 in the second LC resonance suppression push-pull circuit are connected together to form a first common point A'. The first Schottky diode D1 in the first LC resonance suppression push-pull circuit and the second LC resonance suppression push-pull circuit are shared, and the first common point A' is connected to the high level end of the circuit through the first Schottky diode D1.
[0032] The source of the second power electronic power switch device Q6_1 in the first LC resonance suppression push-pull circuit and the source of the second power electronic power switch device Q6_2 in the second LC resonance suppression push-pull circuit are connected together to form a second common point B', the second Schottky diode D2 in the first LC resonance suppression push-pull circuit and the second LC resonance suppression push-pull circuit are shared, and the second common point B' is connected to the circuit ground terminal through the second Schottky diode D2.
[0033] In this embodiment, the first Schottky diode D1, the second Schottky diode D2, and the third Schottky diode D3 are connected in series to prevent reverse current flow. Since LC resonance is an oscillation process, that is, its current is bidirectional, the energy of the current passing through LC can flow from the positive electrode to the negative electrode, and can also flow in the opposite direction. The multiple Schottky diodes D1, D2, and D3 connected in series can stop this bidirectional flow of energy and make it flow in only one direction, that is, the direction of the resonant current is blocked and its rebound backflow is stopped. This embodiment can be applied to occasions with relatively large power.
Claims
1. An LC resonance suppression push-pull circuit, characterized in that: It includes a first power electronic power switch device and a second power electronic power switch device connected in a push-pull form, the gates of the first power electronic power switch device and the second power electronic power switch device are respectively connected to a control circuit, the control circuit includes a driving chip, the output end of the driving chip is the output end of the control circuit for controlling the first power electronic power switch device and the second power electronic power switch device, a first LC resonance suppression device is connected in series between the drain of the first power electronic power switch device and the high level end of the circuit, and a second LC resonance suppression device is connected in series between the source of the second power electronic power switch device and the ground end of the circuit.
2. The LC resonance suppression push-pull circuit according to claim 1, characterized in that: The first LC resonance suppression component and the second LC resonance suppression component are resistors.
3. The LC resonance suppression push-pull circuit according to claim 2, characterized in that: The resistance is no greater than 100 ohms.
4. The LC resonance suppression push-pull circuit according to claim 1, characterized in that: A third LC resonance suppression device is connected in series between the ground pin of the driving chip in the control circuit connected to the second power electronic power switch device and the low-level end of the circuit, and the first LC resonance suppression device, the second LC resonance suppression device and the third LC resonance suppression device are Schottky diodes.
5. The LC resonance suppression push-pull circuit according to claim 1, characterized in that: The first power electronic power switch device and the second power electronic power switch device are MOSFET tubes.
6. A full-bridge circuit, characterized in that: The invention comprises two LC resonance suppression push-pull circuits as claimed in any one of claims 1 to 5.
7. The full-bridge circuit according to claim 6, characterized in that: The two LC resonance suppression push-pull circuits share a first LC resonance suppression component and a second LC resonance suppression component.