A switch drive clamping circuit and a switching power supply

Abstract

This invention discloses a switch-driven clamping circuit and a switching power supply. The switch-driven clamping circuit includes an input port, a drive port, a drive unit, a sampling feedback unit, a compensation unit, a fast turn-off unit, and a switching unit. The invention utilizes the fast turn-off unit and the compensation unit to quickly pull down the voltage at the control terminal of the switching device in the switching unit when the drive voltage is low, achieving fast turn-off and effectively reducing turn-off losses. Simultaneously, the sampling feedback unit and the compensation unit can compensate a voltage signal to the control terminal of the switching device in the switching unit when the drive voltage is high, enabling fast turn-on of the switching device and reducing turn-on losses. Furthermore, the invention, through the sampling feedback unit, can also be applied to high-voltage applications with multiple switching units connected in series to achieve series voltage equalization, effectively solving the problem of uneven voltage distribution among switching units due to inconsistent switching unit parameters.

Description

Technical Field

[0001] This invention patent relates to the field of integrated circuit design technology, specifically to a switch drive clamping circuit and a switching power supply. Background Technology

[0002] Currently, most switching power supplies are high-frequency (small size, high efficiency). As power increases, the voltage withstand capability and current handling capacity of switching transistors also increase significantly. However, the market supply of these high-voltage transistors is limited and expensive. A common approach is to connect two low-voltage transistors in series. However, this series connection has drawbacks: differences in transistor parameters can lead to uneven voltage distribution, making the transistor with the higher voltage drop more susceptible to breakdown. This necessitates the addition of external voltage equalization circuits, which are often complex and costly. Furthermore, during turn-on, there is a linear region where the transistor is not fully turned on, resulting in higher drain-source impedance and greater switching losses. Similarly, during turn-off, the gate-source parasitic capacitance prevents the transistor from turning off immediately when the drive level is low, resulting in significant turn-off losses. Both of these losses are major sources of transistor temperature rise, impacting system reliability. Summary of the Invention

[0003] In view of this, the present invention provides a switch drive clamping circuit and a switching power supply to accelerate the turn-off speed of the switching transistor, thereby solving the problem of long turn-off time of the switching transistor.

[0004] The objective of this invention patent is achieved through the following technical solutions:

[0005] In a first aspect, embodiments of the present invention provide a switch-driven clamping circuit, the switch-driven clamping circuit including an input port, a drive port, a drive unit, a sampling feedback unit, a compensation unit, a fast turn-off unit, and a switching unit;

[0006] The input ports are connected to the input port of the sampling feedback unit and the first port of the switching unit, respectively. The drive ports are connected to the input port of the drive unit and the fourth port of the fast shutdown unit, respectively. The output ports of the drive unit are connected to the second port of the switching unit and the first port of the fast shutdown unit, respectively. The output ports of the sampling feedback unit are connected to the input port of the compensation unit and the third port of the fast shutdown unit, respectively. The output port of the compensation unit is connected to the second port of the fast shutdown unit, and the third port of the switching unit is connected to the fifth port of the fast shutdown unit.

[0007] Furthermore, the driving unit includes a first diode and a first resistor. The anode of the first diode is connected to the driving port, the cathode of the first diode is connected to the first end of the first resistor, and the second end of the first resistor is connected to the second port of the switching unit and the first port of the fast turn-off unit, respectively.

[0008] Furthermore, the sampling feedback unit includes a first Zener diode and a second diode. The cathode of the first Zener diode is connected to the input port, the anode of the first Zener diode is connected to the anode of the second diode, and the cathode of the second diode is connected to the input port of the compensation unit and the third port of the fast shutdown unit, respectively.

[0009] Furthermore, the compensation unit includes a third diode, the anode of which is connected to the output port of the sampling feedback unit and the third port of the fast shutdown unit, respectively, and the cathode of which is connected to the second port of the fast shutdown unit.

[0010] Furthermore, the fast power-off unit includes a second resistor, a third resistor, and a first transistor. The drive port is connected to the base of the first transistor via the second resistor. The base of the first transistor is connected to the output of the sampling feedback unit and the input of the compensation unit. The first end of the third resistor is connected to the output of the drive unit and the second port of the switching unit. The second end of the third resistor is connected to the emitter of the first transistor. The collector of the first transistor is connected to the third port of the switching unit.

[0011] Furthermore, the switching unit includes a fourth resistor and a first switching device. The first end of the first switching device is connected to the input port. The second end of the first switching device is connected to the first end of the fourth resistor, the output end of the driving unit, and the first port of the fast shutdown unit, respectively. The third end of the first switching device is connected to the second end of the fourth resistor and the fifth port of the fast shutdown unit, respectively. The third end of the first switching device is connected to a reference ground.

[0012] Furthermore, the first switching device is specifically one of a relay, thyristor, IGBT, transistor, or MOSFET.

[0013] In a second aspect, embodiments of the present invention also provide a switching power supply, which includes the switch drive clamping circuit as described in the first aspect.

[0014] The working principle of this invention will be explained in detail later with reference to specific embodiments, and will not be repeated here. Compared with the prior art, this invention has the following beneficial effects:

[0015] This invention utilizes a fast turn-off unit and a compensation unit to rapidly lower the voltage at the control terminal of the switching device in the switching unit when the driving voltage is low, achieving rapid turn-off and effectively reducing turn-off losses. Simultaneously, the sampling feedback unit and compensation unit can compensate with a voltage signal to the control terminal of the switching device in the switching unit when the driving voltage is high, enabling rapid turn-on of the switching device and reducing turn-on losses. Furthermore, this invention, through the sampling feedback unit, can also be applied to high-voltage applications with multiple switching units connected in series to achieve series voltage equalization, effectively solving the problem of uneven voltage distribution among switching units caused by inconsistent switching unit parameters. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a switch drive clamping circuit structure according to the present invention.

[0017] Figure 2 This is a schematic diagram of a first embodiment of a switch drive clamping circuit according to the present invention.

[0018] Figure 3 This is a schematic diagram of a second embodiment of a switch drive clamping circuit according to the present invention.

[0019] Figure 4 This is a schematic diagram of a third embodiment of a switch drive clamping circuit according to the present invention. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention, and the specific implementation of the invention is not limited thereto. The described embodiments are only a part of the embodiments of the invention, and not all of them. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Based on the described embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0021] refer to Figure 1 The present invention provides a switch drive clamping circuit, which includes an input port Vin, a drive port Drv, a drive unit 101, a sampling feedback unit 102, a compensation unit 103, a fast turn-off unit 104, and a switch unit 105.

[0022] The input port Vin is connected to the input port Vin of the sampling feedback unit 102 and the first port of the switching unit 105, respectively. The drive port Drv is connected to the input port Vin of the drive unit 101 and the fourth port of the fast shutdown unit 104, respectively. The output port of the drive unit 101 is connected to the second port of the switching unit 105 and the first port of the fast shutdown unit 104, respectively. The output port of the sampling feedback unit 102 is connected to the input port Vin of the compensation unit 103 and the third port of the fast shutdown unit 104, respectively. The output port of the compensation unit 103 is connected to the second port of the fast shutdown unit 104, and the third port of the switching unit 105 is connected to the fifth port of the fast shutdown unit 104. The third port of the switching unit 105 is connected to the reference ground. The input port Vin is connected in series with the switching unit 105 to form a series main power branch; the drive port Drv is connected in series with the drive unit 101 and the switching unit 105 to form a drive turn-on branch; the input port Vin is connected in series with the sampling feedback unit 102, the compensation unit 103, and the switching unit 105 to form a clamping branch; the drive port Drv is connected in series with the fast turn-off unit 104, the compensation unit 103, and the switching unit 105 to form a fast turn-off branch.

[0023] In this embodiment, the driving unit 101 transmits the signal from the driving port Drv to the switching unit 105 to control the switching device in the switching unit 105 to turn on and off; the sampling feedback unit 102 clamps the voltage across the switching device to a stable voltage value when the switching device in the switching unit 105 is turned off, preventing the stress across the switching device from exceeding its maximum withstand voltage stress and causing damage; the compensation unit 103 compensates a voltage signal to the gate-source of the switching device before the switching device is fully turned on, accelerating the turn-on of the switching device and enabling it to quickly complete the linear region when the switching device is turned on; the fast turn-off unit rapidly releases the energy of the parasitic capacitance at the gate-source of the switching device when the switching device is turned off, accelerating the turn-off speed of the switching transistor and reducing turn-off losses. This invention can also be used in the field of high-voltage switching device series connection, achieving voltage equalization across the switching devices, solving the problem of inconsistent switching device parameters in the switching unit 105, and improving stability and reliability.

[0024] refer to Figure 2 In one embodiment, the driving unit 101 includes a first diode D1 and a first resistor R1. The anode of the first diode D1 is connected to the driving port Drv, the cathode of the first diode D1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is connected to the second port of the switching unit 105 and the first port of the fast turn-off unit 104, respectively.

[0025] In one embodiment, the sampling feedback unit 102 includes a first Zener diode DZ1 and a second diode D2. The cathode of the first Zener diode DZ1 is connected to the input port Vin, and the anode of the first Zener diode DZ1 is connected to the anode of the second diode D2. The cathode of the second diode D2 is connected to the input port Vin of the compensation unit 103 and the third port of the fast shutdown unit 104, respectively.

[0026] In this embodiment, the first Zener diode DZ1 and the second diode D2 can clamp the peak voltage of the switching device in the switching unit 105 to a fixed voltage when the switching unit 105 is turned off, thereby protecting the switching device from being broken down by the voltage spike at the moment of turn-off and effectively improving the reliability of the present invention.

[0027] In one embodiment, the compensation unit 103 includes a third diode D3. The anode of the third diode D3 is connected to the output port of the sampling feedback unit 102 and the third port of the fast shutdown unit 104, respectively, and the cathode of the third diode D3 is connected to the second port of the fast shutdown unit 104.

[0028] In one embodiment, the fast power-off unit includes a second resistor R2, a third resistor R3, and a first transistor Q1. The drive port Drv is connected to the base of the first transistor Q1 through the second resistor R2. The base of the first transistor Q1 is connected to the output of the sampling feedback unit 102 and the input of the compensation unit 103. The first end of the third resistor R3 is connected to the output of the drive unit 101 and the second port of the switching unit 105. The second end of the third resistor R3 is connected to the emitter of the first transistor Q1. The collector of the first transistor Q1 is connected to the third port of the switching unit 105.

[0029] In one embodiment, the switching unit 105 includes a fourth resistor R4 and a first switching device S1. The first terminal of the first switching device S1 is connected to the input port Vin. The second terminal of the first switching device S1 is connected to the first terminal of the fourth resistor R4, the output terminal of the driving unit 101, and the first port of the fast shutdown unit 104, respectively. The third terminal of the first switching device S1 is connected to the second terminal of the fourth resistor R4 and the fifth port of the fast shutdown unit 104, respectively. The third terminal of the first switching device S1 is connected to the reference ground.

[0030] The first switching device S1 can be one of a relay, thyristor, IGBT, transistor, or MOSFET. In this embodiment, the first switching device S1 is a MOSFET. When the driving voltage is high, before the MOSFET is fully turned on, a portion of the voltage is compensated to the gate of the first switching device S1 through the drain, allowing it to quickly pass through the linear region during turn-on and achieve rapid full turn-on. Simultaneously, when the driving voltage is low, the voltage at the gate of the first switching device S1 can be quickly pulled down to achieve rapid turn-off.

[0031] First Embodiment

[0032] Figure 2 The circuit schematic diagram of the first embodiment of the present invention is shown. The switch drive clamping circuit includes an input port Vin, a drive port Drv, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first diode D1, a second diode D2, a third diode D3, a first Zener diode DZ1, and a first switching device S1; wherein, in this embodiment, the first switching device S1 is a MOSFET.

[0033] The connection relationships are as follows:

[0034] The input port Vin is connected to the drain of the first switching device S1 and the cathode of the first Zener diode DZ1. The anode of the first Zener diode DZ1 is connected to the anode of the second diode D2. The gate of the first switching device S1 is connected to the upper end of the fourth resistor R4, the upper end of the third resistor R3, and one end of the first resistor R1. The other end of the first resistor R1 is connected to the cathode of the first diode D1. The anode of the first diode D1 is connected to the drive port Drv and one end of the second resistor R2. The other end of the second resistor R2 is connected to the cathode of the second diode D2, the anode of the third diode D3, and the base of the first transistor Q1. The lower end of the third resistor R3 is connected to the cathode of the third diode D3 and the emitter of the first transistor Q1. The source of the first switching device S1 is connected to the lower end of the fourth resistor R4 and the collector of the first transistor Q1.

[0035] The working principle of this embodiment is as follows: When the driving signal is low, the first switching device S1 is turned off. At this time, the base of the first transistor Q1 is at a low level, and the emitter of the first transistor Q1 is at a high level. Therefore, the first transistor Q1 is turned on, and the gate-source capacitor discharges rapidly through the third resistor R3, the first transistor Q1, and the second resistor R2. The first switching device S1 is quickly turned off. After the first switching device S1 is turned off, the leakage inductance of the transformer and the parasitic inductance of the line release energy, which will cause a sudden change at the drain-source terminals, generating a large voltage spike. At this time, the drain-source clamping circuit starts to work. The spike voltage is clamped to a fixed potential through the first Zener diode DZ1, the second diode D2, the third diode D3, the third resistor R3, and the fourth resistor R4, protecting the first switching device S1 from being broken down by high voltage, and improving the stability and reliability of the circuit of this invention.

[0036] When the drive signal is high, during the conduction process of the first switching device S1, the drain of the first switching device S1 will compensate a portion of the voltage signal to the gate of the first switching device S1 through the first Zener diode DZ1, the second diode D2, the third diode D3 and the third resistor R3, thereby accelerating the turn-on speed of the first switching device S1 and enabling it to quickly pass through the linear region when the first switching device S1 is turned on, thus improving the stability of the circuit of the present invention.

[0037] Second Embodiment

[0038] Figure 3 This is a circuit schematic diagram of the second embodiment of the present invention. Compared with the first embodiment, the difference is that the two circuits of the first embodiment are connected in series and applied to high voltage input applications.

[0039] The connection relationships are as follows:

[0040] The input port Vin is connected to the drain of the first switching device S1 and the cathode of the first Zener diode DZ1. The anode of the first Zener diode DZ1 is connected to the anode of the second diode D2. The gate of the first switching device S1 is connected to the upper end of the fourth resistor R4, the upper end of the third resistor R3, and one end of the first resistor R1. The other end of the first resistor R1 is connected to the cathode of the first diode D1. The anode of the first diode D1 is connected to the drive port Drv and one end of the second resistor R2. The other end of the second resistor R2 is connected to the cathode of the second diode D2, the anode of the third diode D3, and the base of the first transistor Q1. The lower end of the third resistor R3 is connected to the cathode of the third diode D3 and the emitter of the first transistor Q1. The source of the first switching device S1 is connected to the fourth resistor R4. The lower end of the second switching device is connected to the collector of the first transistor Q1 and the drain of the second switching device S2. The drain of the second switching device S2 is connected to the cathode of the second Zener diode DZ2. The gate of the second switching device S2 is connected to the upper end of the seventh resistor R7 and one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the cathode of the fourth diode D4. The anode of the fourth diode D4 is connected to the drive port Drv and one end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to the cathode of the fifth diode D5, the anode of the sixth diode D6, and the base of the second transistor Q2. The lower end of the seventh resistor R7 is connected to the cathode of the sixth diode D6 and the emitter of the second transistor Q2. The source of the second switching device S2 is connected to the lower end of the eighth resistor R8 and the collector of the second transistor Q2.

[0041] The working principle of this embodiment differs from that of the first embodiment in that it connects the two circuits of the first embodiment in series. It is mainly used in high-voltage input applications where two switching devices are turned on and off simultaneously. During the on and off states, due to differences in the parameters of the two switching devices, one switching device may turn on first and the other later, or there may be uneven voltage distribution after the two switching devices are turned off simultaneously. In this case, the clamping circuit can be used to clamp the switching devices by connecting the first Zener diode DZ1, the second diode D2, the third diode D3, the third resistor R3, the fourth resistor R4, the second Zener diode DZ2, the fifth diode D5, the sixth diode D6, the seventh resistor R7, and the eighth resistor R8. This achieves the effect of equalizing the voltage across the series connection of the switching devices, thereby protecting the switching devices from being damaged by high voltage.

[0042] Third Embodiment

[0043] Figure 3 This is a circuit schematic diagram of the third embodiment of the present invention. In this embodiment, N circuits of the first embodiment are connected in series, thereby further widening the high voltage input range.

[0044] The working principle of this embodiment is basically the same as that of the first embodiment, and will not be repeated here.

[0045] This invention also provides a switching power supply, which includes the switch drive clamping circuit described above.

[0046] It should be noted that for details not disclosed in the switching power supply of this embodiment, please refer to the details disclosed in the switching drive clamping circuit of this embodiment, which will not be repeated here.

[0047] The above are merely embodiments of the present invention. It should be particularly noted that the above embodiments should not be regarded as limitations on the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A switch driving clamping circuit, characterized by: The switch drive clamping circuit includes an input port, a drive port, a drive unit, a sampling feedback unit, a compensation unit, a fast turn-off unit, and a switch unit. The input ports are connected to the input port of the sampling feedback unit and the first port of the switching unit, respectively. The drive ports are connected to the input port of the drive unit and the fourth port of the fast shutdown unit, respectively. The output ports of the drive unit are connected to the second port of the switching unit and the first port of the fast shutdown unit, respectively. The output ports of the sampling feedback unit are connected to the input port of the compensation unit and the third port of the fast shutdown unit, respectively. The output port of the compensation unit is connected to the second port of the fast shutdown unit, and the third port of the switching unit is connected to the fifth port of the fast shutdown unit. The driving unit includes a first diode and a first resistor. The anode of the first diode is connected to the driving port, the cathode of the first diode is connected to the first end of the first resistor, and the second end of the first resistor is connected to the second port of the switching unit and the first port of the fast turn-off unit, respectively. The sampling feedback unit includes a first Zener diode and a second diode. The cathode of the first Zener diode is connected to the input port, the anode of the first Zener diode is connected to the anode of the second diode, and the cathode of the second diode is connected to the input port of the compensation unit and the third port of the fast shutdown unit, respectively. The compensation unit includes a third diode, the anode of which is connected to the output port of the sampling feedback unit and the third port of the fast shutdown unit, respectively, and the cathode of which is connected to the second port of the fast shutdown unit. The fast shutdown unit includes a second resistor, a third resistor, and a first transistor. The drive port is connected to the base of the first transistor through the second resistor. The base of the first transistor is connected to the output of the sampling feedback unit and the input of the compensation unit. The first end of the third resistor is connected to the output of the drive unit and the second port of the switching unit. The second end of the third resistor is connected to the emitter of the first transistor. The collector of the first transistor is connected to the third port of the switching unit. The switching unit includes a fourth resistor and a first switching device. The first end of the first switching device is connected to the input port. The second end of the first switching device is connected to the first end of the fourth resistor, the output end of the driving unit, and the first port of the fast shutdown unit. The third end of the first switching device is connected to the second end of the fourth resistor and the fifth port of the fast shutdown unit. The third end of the first switching device is connected to a reference ground.

2. A clamping circuit for driving a switch according to claim 1, characterized in that: The first switching device is specifically one of a relay, thyristor, IGBT, or MOSFET.

3. A switching power supply, characterized by comprising: Includes the switch drive clamping circuit as described in any one of claims 1 to 2.

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