阅读说明：本技术 开关管保护电路以及驱动电路 (Switch tube protection circuit and driving circuit ) 是由 张敏 刘丽刚 林锰津 王科 黄锦彦 于 2021-08-31 设计创作，主要内容包括：本申请涉及一种开关管保护电路以及驱动电路,开关管保护电路包括积分回路、控制开关、稳压管D3和二极管D4,积分回路连接控制信号输入端、稳压管D3的阴极和二极管D4的阳极,稳压管D3的阳极连接控制开关的控制端,二极管D4的阴极连接开关管的第一端；控制开关的第一端连接开关管的控制端,控制开关的第二端接地；积分回路用于拉低控制开关的控制端电位,并在开关管过流时拉升控制开关的控制端电位,使控制开关导通,从而将开关管截止,达到过流保护的目的。相对于传统的开关管保护方式,不会受制于芯片的限制而影响响应速度,提高了保护及时性,降低了烧毁后级芯片或电路的风险。(The application relates to a switch tube protection circuit and a driving circuit, wherein the switch tube protection circuit comprises an integral loop, a control switch, a voltage regulator tube D3 and a diode D4, the integral loop is connected with a control signal input end, the cathode of the voltage regulator tube D3 and the anode of the diode D4, the anode of the voltage regulator tube D3 is connected with the control end of the control switch, and the cathode of the diode D4 is connected with the first end of a switch tube; the first end of the control switch is connected with the control end of the switch tube, and the second end of the control switch is grounded; the integral loop is used for pulling down the control end potential of the control switch and pulling up the control end potential of the control switch when the switch tube is in overcurrent so as to switch on the control switch, thereby cutting off the switch tube and achieving the purpose of overcurrent protection. Compared with the traditional switch tube protection mode, the protection device has the advantages that the response speed cannot be influenced by the limitation of the chip, the protection timeliness is improved, and the risk of burning back-stage chips or circuits is reduced.)

1. A switch tube protection circuit is characterized by comprising an integral loop, a control switch, a voltage regulator tube D3 and a diode D4, wherein the integral loop is connected with a control signal input end, the cathode of the voltage regulator tube D3 and the anode of the diode D4, the anode of the voltage regulator tube D3 is connected with the control end of the control switch, and the cathode of the diode D4 is connected with the first end of a switch tube; the first end of the control switch is connected with the control end of the switch tube, and the second end of the control switch is grounded; the integral loop is used for pulling down the control end potential of the control switch and pulling up the control end potential of the control switch when the switch tube is in overcurrent so as to enable the control switch to be conducted.

2. The switch tube protection circuit according to claim 1, wherein the integrating loop comprises a resistor R1 and a capacitor C1, the resistor R1 and the capacitor C1 are connected in series, a common end of the resistor R1 is connected with a cathode of the voltage regulator tube D3 and an anode of the diode D4, the other end of the resistor R1 is connected with a control signal input end, and the other end of the capacitor C1 is grounded.

3. The switch tube protection circuit according to claim 2, further comprising a diode D1, wherein the diode D1 is connected in parallel with the resistor R1, and an anode of the diode D1 is connected to a common terminal of the resistor R1 and the capacitor C1.

4. The switch tube protection circuit according to claim 2, further comprising a diode D2, wherein a common terminal of the resistor R1 and the capacitor C1 is connected to the regulator tube D3 through the diode D2, and a cathode of the diode D2 is connected to a cathode of the regulator tube D3.

5. The switch tube protection circuit according to claim 1, further comprising a resistor R2, wherein one end of the resistor R2 is connected to the control signal input terminal, and the other end of the resistor R2 is connected to the control terminal of the switch tube.

6. The switch tube protection circuit according to claim 1, further comprising a resistor R3, wherein one end of the resistor R3 is connected to the control terminal of the control switch, and the other end of the resistor R3 is grounded.

7. The switch tube protection circuit according to any one of claims 1-6, further comprising a display circuit connected to the first end of the switch tube.

8. The switch tube protection circuit according to any one of claims 1-6, further comprising an alarm circuit connected to the first terminal of the control switch.

9. The switching tube protection circuit according to any one of claims 1-6, wherein the switching tube is a MOS tube, and the control switch is a triode.

10. A driver circuit comprising a switching tube and a switching tube protection circuit as claimed in any one of claims 1 to 9.

Technical Field

The present application relates to the field of protection circuits, and in particular, to a switching tube protection circuit and a driving circuit.

Background

In a common control circuit and a switching power supply circuit, a PWM chip protection pin signal is usually input to perform overvoltage or overcurrent protection on a high-power semiconductor device such as a switching tube. The traditional switch tube protection mode is limited by the self parameters of the chip and the like, the response speed is slow, the action is slow, and the current which is increased too fast to short circuit possibly has the risk of untimely protection and burning of a rear-stage chip or circuit.

Disclosure of Invention

Therefore, it is necessary to provide a switching tube protection circuit and a driving circuit to solve the problem that the protection of the conventional switching tube is not timely, so as to achieve the effect of improving the timeliness of the protection.

A switch tube protection circuit comprises an integral loop, a control switch, a voltage regulator tube D3 and a diode D4, wherein the integral loop is connected with a control signal input end, the cathode of the voltage regulator tube D3 and the anode of the diode D4, the anode of the voltage regulator tube D3 is connected with the control end of the control switch, and the cathode of the diode D4 is connected with the first end of a switch tube; the first end of the control switch is connected with the control end of the switch tube, and the second end of the control switch is grounded; the integral loop is used for pulling down the control end potential of the control switch and pulling up the control end potential of the control switch when the switch tube is in overcurrent so as to enable the control switch to be conducted.

In one embodiment, the integration loop comprises a resistor R1 and a capacitor C1, the resistor R1 and the capacitor C1 are connected in series, a common end of the resistor R1 is connected with the cathode of the voltage regulator tube D3 and the anode of the diode D4, the other end of the resistor R1 is connected with a control signal input end, and the other end of the capacitor C1 is grounded.

In one embodiment, the switch tube protection circuit further includes a diode D1, the diode D1 is connected in parallel with the resistor R1, and an anode of the diode D1 is connected to a common terminal of the resistor R1 and the capacitor C1.

In one embodiment, the switch tube protection circuit further includes a diode D2, the common terminal of the resistor R1 and the capacitor C1 is connected to the voltage regulator tube D3 through the diode D2, and the cathode of the diode D2 is connected to the cathode of the voltage regulator tube D3.

In one embodiment, the switch tube protection circuit further includes a resistor R2, one end of the resistor R2 is connected to the control signal input terminal, and the other end of the resistor R2 is connected to the control terminal of the switch tube.

In one embodiment, the switch tube protection circuit further includes a resistor R3, one end of the resistor R3 is connected to the control terminal of the control switch, and the other end of the resistor R3 is grounded.

In one embodiment, the switch tube protection circuit further comprises a display circuit connected to the first end of the switch tube.

In one embodiment, the switch tube protection circuit further comprises an alarm circuit connected to the first terminal of the control switch.

In one embodiment, the switch tube is an MOS tube, and the control switch is a triode.

A circuit device comprises a switch tube and the switch tube protection circuit.

When the switch tube works normally, the integrating loop pulls down the control end potential of the control switch to prevent the control switch from being switched on by mistake. When the switch tube is over-current, the integral loop pulls up the control end potential of the control switch to turn on the control switch, so that the switch tube is cut off to achieve the purpose of over-current protection. Compared with the traditional switch tube protection mode, the protection device has the advantages that the response speed cannot be influenced by the limitation of the chip, the protection timeliness is improved, and the risk of burning back-stage chips or circuits is reduced.

Drawings

FIG. 1 is a schematic diagram of a protection circuit of a switching tube according to an embodiment;

FIG. 2 is a schematic diagram of driving waveforms during normal operation of the circuit according to an embodiment;

fig. 3 is a schematic diagram of driving waveforms during overcurrent protection of the circuit according to an embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be connected to the other element through intervening elements. The "connection" in the following embodiments is understood as "electrical connection", "communication connection", or the like if the connected circuits, modules, units, or the like have electrical signals or data transmission therebetween.

As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, the terminology used in this specification includes any and all combinations of the associated listed items.

In one embodiment, a switch tube protection circuit is provided, and the switch tube can be a MOS tube or a triode, and can also be other high-power semiconductor switching devices. As shown in fig. 1, the switching tube protection circuit includes an integrating loop 110, a control switch Q1, a voltage regulator tube D3 and a diode D4, the integrating loop 110 is connected to the control signal input end, the cathode of the voltage regulator tube D3 and the anode of the diode D4, the anode of the voltage regulator tube D3 is connected to the control end of the control switch Q1, and the cathode of the diode D4 is connected to the first end of the switching tube Q2; the first end of the control switch Q1 is connected with the control end of the switch tube Q2, and the second end of the control switch Q1 is grounded; the integrating loop 110 is used to pull down the control terminal of the control switch Q1, and pull up the control terminal of the control switch Q1 when the switch Q2 is overcurrent, so that the control switch Q1 is turned on.

The types of the control switch Q1 and the switching tube Q2 are not exclusive, for example, the control switch Q1 may be a triode, and the switching tube Q2 may be a MOS transistor, in this embodiment, the control switch Q1 is an NPN-type triode, with a base as a control terminal, a collector as a first terminal, and an emitter as a second terminal. Further, the switching transistor Q2 is an N-channel MOS transistor, and has a gate as a control terminal, a drain as a first terminal, and a source as a second terminal. The type of the diode D4 is not exclusive, and in the present embodiment, the diode D4 is a schottky high-voltage ultrafast recovery diode. During normal operation, the integrating loop 110 pulls down the control terminal voltage of the control switch Q1 immediately before the switching transistor Q2 is turned on, so as to prevent the control switch Q1 from being turned on by mistake. When the switching tube Q2 is overcurrent, after a short integration delay through the integration loop 110, the control end potential of the control switch Q1 is pulled up, so that the control switch Q1 is turned on, and the switching tube Q2 is turned off, thereby achieving the purpose of overcurrent protection.

It is understood that the specific structure of the integration circuit 110 is not exclusive, and in one embodiment, the integration circuit 110 includes a resistor R1 and a capacitor C1, the resistor R1 and the capacitor C1 are connected in series, a common terminal of the resistor R1 and the capacitor C1 is connected to the cathode of the zener diode D3 and the anode of the diode D4, the other terminal of the resistor R1 is connected to the control signal input terminal, and the other terminal of the capacitor C1 is grounded. Specifically, as shown in fig. 1, the resistor R1 and the capacitor C1 are connected in series and then connected to two ends of the control signal input, so as to receive the control signal Ui. Taking the control switch Q1 as a triode and the switch Q2 as a MOS transistor as an example, when the circuit normally works, in the initial short time of the forward driving pulse, the voltage at the point a is clamped at a lower potential due to the existence of the resistor R1 and the capacitor C1, the voltage regulator D3 is cut off, and the triode is in a cut-off state. The input control signal Ui is almost completely applied to the MOS transistor and rapidly charges the input capacitor C1. With the increase of the gate-source voltage Ugs of the MOS tube, the MOS tube is switched on, and the voltage between a drain electrode and a source electrode is reduced. The diode D4 is conducted in forward bias, the voltage at the point A is clamped, and the voltage regulator tube D3 and the triode are continuously and reliably cut off due to reverse bias.

When the MOS transistor is over-current, the drain voltage Uds rises rapidly, the diode D4 is reverse biased to cut off, and the voltage at point a begins to rise. When the voltage rises to be higher than the sum of the gate value voltage Uth of the voltage regulator tube D3 and the triode, the MOS tube is conducted, the grid potential is pulled down to be close to 0V, so that the MOS tube is reliably turned off, the circuit current is cut off, and the circuit can be protected within 0.1us when the overcurrent is detected.

When the switch tube Q2 normally works, the integrating loop 110 pulls down the control end potential of the control switch Q1, and prevents the control switch Q1 from being turned on by mistake. When the switching tube Q2 is overcurrent, the integrating loop 110 pulls up the control end potential of the control switch Q1, so that the control switch Q1 is turned on, and the switching tube Q2 is cut off, thereby achieving the purpose of overcurrent protection. Compared with the traditional switch tube protection mode, the protection device has the advantages that the response speed cannot be influenced by the limitation of the chip, the protection timeliness is improved, and the risk of burning back-stage chips or circuits is reduced.

In one embodiment, the switch tube protection circuit further comprises a diode D1, the diode D1 is connected in parallel with the resistor R1, and an anode of the diode D1 is connected to a common terminal of the resistor R1 and the capacitor C1. Diode D1 functions as a discharge in preparation for the integration delay before the next turn-on.

In one embodiment, the switch tube protection circuit further comprises a diode D2, the common terminal of the resistor R1 and the capacitor C1 is connected with the voltage regulator D3 through a diode D2, and the cathode of the diode D2 is connected with the cathode of the voltage regulator D3. The specific type of the diode D2 is not exclusive, and in the present embodiment, the diode D2 is a low-voltage ultrafast recovery schottky diode. Further, in an embodiment, the switch tube protection circuit further includes a resistor R2, one end of the resistor R2 is connected to the control signal input terminal, and the other end of the resistor R2 is connected to the control terminal of the switch tube Q2.

In addition, in one embodiment, the switch tube protection circuit further includes a resistor R3, one end of the resistor R3 is connected to the control terminal of the control switch Q1, and the other end of the resistor R3 is grounded. Similarly, taking the switching transistor Q2 as a MOS transistor as an example, the resistor R3 is used for suppressing the gate high-frequency oscillation of the MOS transistor, thereby protecting the MOS transistor.

In one embodiment, the switch tube protection circuit further includes a display circuit D connected to the first end of the switch tube Q2, and the display circuit D is used for real-time detection and monitoring of the circuit. Specifically, the display circuit D can display the relevant parameters such as voltage and current. The display circuit D can comprise a parameter acquisition unit and a display unit, and further can comprise a storage unit. The parameter acquisition unit is connected with the first end of the switching tube Q2, the display unit and the storage unit, and the storage unit is used for storing parameters. Further, in one embodiment, the switch tube protection circuit further includes an alarm circuit B connected to the first terminal of the control switch Q1. When the circuit is over-current, the alarm circuit B sends out an alarm signal in time.

In one embodiment, the switching tube protection circuit can also comprise a display circuit D and an alarm circuit B, when an abnormal circuit enters a protection state, the alarm circuit B gives an alarm indication, and the display circuit D displays the current on the MOS tube at the moment to monitor the circuit state in real time; when the circuit normally operates, the alarm circuit is not triggered, the display circuit D displays operating current and voltage parameters, the circuit gives an alarm once during operation, and the display circuit D stores once, so that the safety and the reliability of the circuit are further ensured.

In one embodiment, a circuit device is also provided, which comprises a switch tube and the switch tube protection circuit. The circuit device can be suitable for a control circuit and a switching power supply circuit, and the switching tube can be an MOS tube or a triode and can also be other high-power semiconductor switching devices.

Specifically, as shown in fig. 1, the switching tube protection circuit includes an integrating loop 110, a control switch Q1, a voltage regulator tube D3 and a diode D4, the integrating loop 110 is connected to the control signal input end, the cathode of the voltage regulator tube D3 and the anode of the diode D4, the anode of the voltage regulator tube D3 is connected to the control end of the control switch Q1, and the cathode of the diode D4 is connected to the first end of the switching tube Q2; the first end of the control switch Q1 is connected with the control end of the switch tube Q2, and the second end of the control switch Q1 is grounded; the integrating loop 110 is used to pull down the control terminal of the control switch Q1, and pull up the control terminal of the control switch Q1 when the switch Q2 is overcurrent, so that the control switch Q1 is turned on.

The control switch Q1 and the switch Q2 are not exclusive, for example, the control switch Q1 may be a transistor, and the switch Q2 may be a MOS transistor, in this embodiment, the control switch Q1 is an NPN transistor, with a base as a control terminal, a collector as a first terminal, and an emitter as a second terminal. Further, the switching transistor Q2 is an N-channel MOS transistor, and has a gate as a control terminal, a drain as a first terminal, and a source as a second terminal. The type of the diode D4 is not exclusive, and in the present embodiment, the diode D4 is a schottky high-voltage ultrafast recovery diode. During normal operation, the integrating loop 110 pulls down the control terminal voltage of the control switch Q1 immediately before the switching transistor Q2 is turned on, so as to prevent the control switch Q1 from being turned on by mistake. When the switching tube Q2 is overcurrent, after a short integration delay through the integration loop 110, the control end potential of the control switch Q1 is pulled up, so that the control switch Q1 is turned on, and the switching tube Q2 is turned off, thereby achieving the purpose of overcurrent protection.

In one embodiment, the integrating loop 110 includes a resistor R1 and a capacitor C1, the resistor R1 and the capacitor C1 are connected in series, a common terminal of the resistor R1 and the capacitor C1 is connected to a cathode of the voltage regulator D3 and an anode of the diode D4, the other end of the resistor R1 is connected to the control signal input terminal, and the other end of the capacitor C1 is grounded. Specifically, as shown in fig. 1, the resistor R1 and the capacitor C1 are connected in series and then connected to two ends of the control signal input, so as to receive the control signal Ui. Taking the control switch Q1 as a triode and the switch Q2 as a MOS transistor as an example, when the circuit normally works, in the initial short time of the forward driving pulse, the voltage at the point a is clamped at a lower potential due to the existence of the resistor R1 and the capacitor C1, the voltage regulator D3 is cut off, and the triode is in a cut-off state. The input control signal Ui is almost completely applied to the MOS transistor and rapidly charges the input capacitor C1. With the increase of the gate-source voltage Ugs of the MOS tube, the MOS tube is switched on, and the voltage between a drain electrode and a source electrode is reduced. The diode D4 is conducted in forward bias, the voltage at the point A is clamped, and the voltage regulator tube D3 and the triode are continuously and reliably cut off due to reverse bias.

When the MOS transistor is over-current, the drain voltage Uds rises rapidly, the diode D4 is reverse biased to cut off, and the voltage at point a begins to rise. When the voltage rises to be higher than the sum of the gate value voltage Uth of the voltage regulator tube D3 and the triode, the MOS tube is conducted, the grid potential is pulled down to be close to 0V, so that the MOS tube is reliably turned off, the circuit current is cut off, and the circuit can be protected within 0.1us when the overcurrent is detected.

In one embodiment, the switch tube protection circuit further comprises a diode D1, the diode D1 is connected in parallel with the resistor R1, and an anode of the diode D1 is connected to a common terminal of the resistor R1 and the capacitor C1. Diode D1 functions as a discharge in preparation for the integration delay before the next turn-on.

In one embodiment, the switch tube protection circuit further comprises a diode D2, the common terminal of the resistor R1 and the capacitor C1 is connected with the voltage regulator D3 through a diode D2, and the cathode of the diode D2 is connected with the cathode of the voltage regulator D3. In this embodiment, the diode D2 is a low-voltage ultrafast recovery schottky diode. Further, in an embodiment, the switch tube protection circuit further includes a resistor R2, one end of the resistor R2 is connected to the control signal input terminal, and the other end of the resistor R2 is connected to the control terminal of the switch tube Q2.

In one embodiment, the switch tube protection circuit further includes a resistor R3, one end of the resistor R3 is connected to the control terminal of the control switch Q1, and the other end of the resistor R3 is grounded. Similarly, taking the switching transistor Q2 as a MOS transistor as an example, the resistor R3 is used for suppressing the gate high-frequency oscillation of the MOS transistor, thereby protecting the MOS transistor.

In one embodiment, the switch tube protection circuit further includes a display circuit D connected to the first end of the switch tube Q2, and the display circuit D is used for real-time detection and monitoring of the circuit. Specifically, the display circuit D can display the relevant parameters such as voltage and current. Further, in one embodiment, the switch tube protection circuit further includes an alarm circuit B connected to the first terminal of the control switch Q1. When the circuit is over-current, the alarm circuit B sends out an alarm signal in time.

In one embodiment, the switching tube protection circuit can also comprise a display circuit D and an alarm circuit B, when an abnormal circuit enters a protection state, the alarm circuit B gives an alarm indication, and the display circuit D displays the current on the MOS tube at the moment to monitor the circuit state in real time; when the circuit normally operates, the alarm circuit is not triggered, the display circuit D displays operating current and voltage parameters, the circuit gives an alarm once during operation, and the display circuit D stores once, so that the safety and the reliability of the circuit are further ensured.

In order to better understand the protection circuit and the driving circuit of the switching tube, the following detailed explanation is provided with reference to specific embodiments.

With the rapid development of power electronics, the switching speed of high-power semiconductor devices acting on switching devices is required to be faster and faster, and the application range is wider. The application designs a be suitable for the higher drive of MOSFET pipe high-power reliability and protection circuit, and the advantage of full play MOSFET pipe realizes high-power circuit drive, has fast-speed drive coupling and fault response speed, improves and detects the overcurrent fault and makes the protection action rapidly, and the interference killing feature is strong, simple structure, and the adjustment parameter is easy, low cost.

Specifically, the application provides a high-power driving and current display protection circuit which comprises an MOS (metal oxide semiconductor) tube, a triode, an ultrafast recovery diode, an integrating circuit and an alarm display circuit. The MOSFET is selected to meet the requirement of a high-power driving circuit; the triode is selected to perform overcurrent protection on the MOS tube, so that the reliability and the safety of the circuit are improved; the selection of the integrating circuit and the ultrafast recovery diode can realize overcurrent detection and protection quickly. And designing an alarm and display module circuit according to the circuit characteristics to carry out real-time monitoring and record and store data. The circuit meets the driving requirement of a high-power circuit, detects an overcurrent signal at a high speed, improves the detection protection efficiency, and reduces the risk of false triggering or delayed detection. The circuit has high reliability and low cost.

As shown in FIG. 1, in the circuit, a diode D1 is connected in series with a capacitor C1 and connected to two ends of input of a control signal, the cathode of a diode D1 and the upper end of a resistor R1 are converged into the left end of the resistor R2, and the right end of a resistor R2 and the collector of a triode Q1 are connected to a gate G of a MOS (metal oxide semiconductor) tube. The lower end of the resistor R1 is connected with the anode of the Schottky diode D4 and the anode of the diode D2, and the cathode of the diode D2 is connected with the cathode of the voltage stabilizing diode D3. The anode of the zener diode D3 and the upper end of the resistor R3 are connected to the base of the transistor Q1. The resistor R3 and the capacitor C1 are grounded together with the emitter of the transistor Q1. The cathode of the schottky diode D4 is connected to the drain of the MOS transistor. An alarm circuit B is arranged at the position of the triode Q1, when the abnormal circuit enters a protection state, the alarm circuit B gives an alarm indication, and a display circuit D displays the current on the MOS tube at the moment, so that the circuit state is monitored in real time; when the circuit normally operates, the alarm circuit B is not triggered, the display circuit D displays operating current and voltage parameters, the circuit gives an alarm once during operation, and the display circuit D stores once, so that the safety and the reliability of the circuit are further ensured.

When the circuit normally works, in the initial short time of the forward driving pulse, the voltage at the point A is clamped at a lower potential due to the existence of the resistor R1 and the capacitor C1, the zener diode D3 is cut off, and the triode Q1 is in a cut-off state. The input control signal Ui is almost completely applied to the MOS transistor Q2 and rapidly charges the input capacitor C1. As the gate-source voltage Ugs of the MOS transistor Q2 increases, the MOS transistor Q2 turns on, and the drain-source voltage decreases. The schottky diode D4 is forward biased to turn on, the voltage at point a is clamped, and the zener diode D3 and the transistor Q1 continue to reliably turn off due to reverse bias. The diode D1 is used for discharging and preparing for integral delay before the next turn-on; the resistor R3 is used for inhibiting the high-frequency oscillation of the grid and protecting the MOSFET tube.

Fig. 2 is a driving waveform diagram of the circuit in normal operation, and fig. 3 is a driving waveform diagram of the circuit in overcurrent protection. When the MOSFET tube is over-current, the drain voltage Uds rises rapidly, the schottky diode D4 is reverse biased off, and the voltage at point a begins to rise. When the voltage rises to be higher than the sum of the gate voltage Uth of the voltage regulator tube D3 and the triode Q1, the MOS tube Q2 is turned on, the gate potential is pulled down to be close to 0V, so that the MOS tube Q2 is reliably turned off, the circuit current is cut off, the overcurrent is detected, and the circuit is protected within 0.1us, as shown in fig. 3.

The integrating loop formed by the resistor R1 and the capacitor C1 mainly has the following functions: when the MOSFET normally works, the potential of the point A is pulled down at the moment before the MOSFET is switched on, and the transistor Q1 is prevented from being switched on by mistake; when overcurrent occurs, the potential of the point A is raised to the switching-on voltage of the triode Q1 through short integral time delay, the triode Q1 is conducted, and the voltage G point of the grid electrode is clamped. The MOS transistor Q2 is cut off, thereby achieving the purpose of overcurrent protection.

And the display circuit D and the alarm circuit B are designed for carrying out real-time detection and monitoring on the circuits. When the circuit works normally, the display circuit displays relevant parameters such as voltage, current and the like; when the circuit is over-current, the alarm circuit B sends out an alarm signal in time, the display circuit D displays the current and voltage data of the MOS tube during over-current, the protection times in the whole test period are recorded, and the reasonability and the reliability of the circuit design are further confirmed.

In fig. 1, a diode D4 is a schottky high-voltage ultrafast recovery diode, a diode D2 is a low-voltage ultrafast recovery type schottky diode, and the influence of a charge displacement current formed by a large junction capacitor in a voltage regulator tube D3 on a triode Q1 can be eliminated.

According to the high-power driving and current display protection circuit, the MOSFET is selected as a core device to build a driving circuit, and the requirement of the circuit on high power can be met. Meanwhile, a combination mode of a triode matched with an MOSFET and an ultrafast recovery diode and a charging and discharging circuit is selected, so that high-speed overcurrent protection is realized, the protection response is timely, and the reliability is high. And relevant parameters are displayed through an external display and alarm circuit, so that real-time monitoring is performed.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.