Short-circuit protection device, short-circuit protection method for target circuit, and power conversion equipment

Abstract

The present application provides a short-circuit protection device, a short-circuit protection method for a target circuit, and a power conversion device. The short-circuit protection device includes a first detection branch, a second detection branch, and a controller. The first detection branch includes a first sampling resistor and a first sampling capacitor connected in parallel therewith, and the second detection branch includes a second sampling resistor. When the target circuit is in a working state, the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a first difference. The controller obtains a comparison result of the absolute value of the first sampling voltage at both ends of the first sampling resistor and the absolute value of the second sampling voltage at both ends of the second sampling resistor, and when the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, and the second difference is less than the first difference, the target circuit is controlled to stop working. By adopting the present application, the short-circuit fault can be quickly and timely cut off, and effective protection of the target circuit can be achieved, and the applicability is strong.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a short-circuit protection device, a short-circuit protection method for a target circuit, and a power conversion device. Background Art

[0002] Power electronic devices, such as Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET) and Insulated Gate Bipolar Transistor (IGBT), have fast conduction speed, low switching loss, and high energy density, but their withstand voltage and overcurrent capabilities are relatively low. When damaged, the device short-circuits or breaks, which can easily cause system accidents to further expand, limiting their further application. If a short circuit occurs at both ends of an energy source such as a battery or capacitor, a short-term high current will be generated, causing damage to the power electronic device or other sub-components, and in severe cases, even fire or explosion.

[0003] At present, mainly through Figure 1 The short-circuit protection device shown in FIG. 1 is used to implement short-circuit protection for MOSFETs S1 and S2. Figure 1 As shown, the short-circuit protection device includes a resistor R1 connected in series with S1 and an operational amplifier connected to both ends of R1 through resistors R11 and R12 respectively. When S1 and S2 are short-circuited, the voltage across R1 increases with the short-circuit current, and the output voltage Vo of the operational amplifier also increases accordingly. It can be determined whether S1 and S2 have a short-circuit fault by judging whether the output voltage Vo of the operational amplifier reaches a preset output voltage protection value. However, since the above circuit contains an inductor L connected in series with the battery, and the inductance value of L will affect the rising speed of the short-circuit current, the short-circuit protection is not fast enough and has poor applicability. Summary of the invention

[0004] The present application provides a short-circuit protection device, a short-circuit protection method for a target circuit, and a power conversion device, which can quickly and timely cut off the short-circuit fault, achieve effective protection for the target circuit, and have strong applicability.

[0005] In the first aspect, the present application provides a short circuit protection device, which includes a first detection branch, a second detection branch and a controller. The first detection branch is connected in parallel to the first end and the second end of the target circuit, the second detection branch is connected in parallel to the first end and the second end of the target circuit, the first detection branch includes a first sampling resistor and a first sampling capacitor connected in parallel with the first sampling resistor, the second detection branch includes a second sampling resistor, and when the target circuit is in a working state, the difference between the absolute value of the second sampling voltage at both ends of the second sampling resistor and the absolute value of the first sampling voltage at both ends of the first sampling resistor is a first difference. The controller obtains the comparison result of the absolute value of the first sampling voltage at both ends of the first sampling resistor and the absolute value of the second sampling voltage at both ends of the second sampling resistor, and when the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, and the second difference is less than the first difference, the target circuit is controlled to stop working. Since when a short circuit occurs between the first end and the second end of the target circuit, the voltage drop speed at both ends of the target circuit is much faster than the rise speed of the short circuit current, the short circuit fault can be quickly and timely cut off, and effective protection of the target circuit is achieved, and the applicability is strong.

[0006] In combination with the first aspect, in a first possible implementation, the second detection branch further includes a second sampling capacitor, the second sampling capacitor is connected in parallel with the second sampling resistor, and the capacitance value of the second sampling capacitor is less than the capacitance value of the first sampling capacitor. The peak component in the second sampling voltage can be filtered by the second sampling capacitor, which can avoid the situation where the short-circuit protection is falsely triggered due to the downward peak component, improve the accuracy of the short-circuit protection device when performing short-circuit protection, and thus improve the stability of the target circuit and the device (such as power conversion device) where the short-circuit protection device is located when working.

[0007] In combination with the first aspect, in a second possible implementation, the first detection branch includes two resistors connected in series, the two resistors connected in series in the first detection branch also include a third sampling resistor, one end of the third sampling resistor is connected to the first end of the target circuit and one end of the second sampling resistor, and the other end of the first sampling resistor is connected to the second end of the target circuit and the other end of the second sampling resistor. Only three resistors and one capacitor are needed to detect whether a short circuit fault occurs between the two ends of the target circuit, the circuit structure is simple, the circuit cost can be reduced, and the applicability is strong.

[0008] In combination with the first aspect, in a third possible implementation, the second detection branch includes two resistors connected in series, the two resistors connected in series in the second detection branch also include a fourth sampling resistor, the first end of the target circuit is connected to the second end of the target circuit through the fourth sampling resistor and the second sampling resistor, wherein the ratio between the resistance value of the fourth sampling resistor and the resistance value of the second sampling resistor is less than or equal to the ratio between the resistance value of the third sampling resistor and the resistance value of the first sampling resistor, which can ensure that when the target circuit is in a working state, that is, when there is no short circuit fault between the first end and the second end of the target circuit, the second sampling voltage across the second sampling resistor is greater than or equal to the first sampling voltage across the first sampling resistor. Further, after adding the fourth sampling resistor in the second detection branch, the size between the first sampling voltage and the second sampling voltage can be changed according to actual needs by changing the resistance value of the four resistors from the first sampling resistor to the fourth sampling resistor, which has high flexibility.

[0009] In combination with the first aspect, in a fourth possible implementation, the short-circuit protection device further includes a comparator, wherein the first input terminal of the comparator is used to collect the first sampling voltage at both ends of the first sampling resistor, and the second input terminal is used to collect the second sampling voltage at both ends of the second sampling resistor. The output terminal of the comparator is connected to the controller, and is used to output a first level signal when the first sampling voltage is less than the second sampling voltage; and output a second level signal when the first sampling voltage is greater than or equal to the second sampling voltage. The controller obtains the level signal output by the comparator, and controls the target circuit to stop working when the level signal output by the comparator is the second level signal. The comparison result of the first sampling resistor and the second sampling resistor can be obtained by obtaining the level signal output by the comparator, thereby reducing the amount of calculation of the controller and improving the processing efficiency.

[0010] In combination with the first aspect, in a fifth possible implementation, the controller obtains a comparison result of the absolute value of the first sampled voltage at both ends of the first sampling resistor and the absolute value of the second sampled voltage at both ends of the second sampling resistor at a first moment after a preset time period after the difference between the absolute value of the second sampled voltage and the absolute value of the first sampled voltage is the second difference. If the difference between the absolute value of the second sampled voltage and the absolute value of the first sampled voltage is the third difference, and the third difference is less than the first difference, the target circuit is controlled to stop working, thereby avoiding the short-circuit protection from being falsely triggered by a delay, improving the accuracy of the short-circuit protection device when performing short-circuit protection, and thereby improving the stability of the target circuit and the device (such as a power conversion device) where the short-circuit protection device is located when working.

[0011] In combination with the first aspect, in a sixth possible implementation, the target circuit includes a power supply and a switch device or a plurality of switch devices connected in series coupled to both ends of the power supply, and the power supply includes a DC source or a capacitor. By short-circuit protection of the target circuit, the power supply can be prevented from directly short-circuiting and exploding due to a short circuit between both ends of the target circuit, thereby improving the reliability and safety of the device (such as a power conversion device) in which the target circuit is located.

[0012] In combination with the first aspect, in a seventh possible implementation, when the target circuit includes a switching device or a plurality of switching devices connected in series, the switching device in the target circuit can be controlled to be in an off state to control the target circuit to stop working.

[0013] In combination with the first aspect, in an eighth possible implementation, the switching device includes a power tube, a relay, or a contactor.

[0014] In a second aspect, the present application provides a short-circuit protection method for a target circuit, the method comprising: obtaining a comparison result of the absolute value of a first sampling voltage at both ends of a first sampling resistor in a first detection branch and the absolute value of a second sampling voltage at both ends of a second sampling resistor in a second detection branch. Wherein, the first detection branch is connected in parallel to the first end and the second end of the target circuit, the second detection branch is connected in parallel to the first end and the second end of the target circuit, the first detection branch includes a first sampling resistor and a first sampling capacitor connected in parallel with the first sampling resistor, the second detection branch includes a second sampling resistor, and when the target circuit is in a working state, the difference between the absolute value of the second sampling voltage at both ends of the second sampling resistor and the absolute value of the first sampling voltage at both ends of the first sampling resistor is a first difference. Thereafter, when the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, and when the second difference is less than the first difference, the target circuit is controlled to stop working.

[0015] In combination with the second aspect, in a first possible implementation manner, the detection branch further includes a second sampling capacitor, the second sampling capacitor is connected in parallel with the second sampling resistor, and a capacitance value of the second sampling capacitor is smaller than a capacitance value of the first sampling capacitor.

[0016] In combination with the second aspect, in a second possible implementation, the first detection branch includes two resistors connected in series, and the two resistors connected in series in the first detection branch also include a third sampling resistor, one end of the third sampling resistor is connected to the first end of the target circuit and one end of the second sampling resistor, and the other end of the first sampling resistor is connected to the second end of the target circuit and the other end of the second sampling resistor.

[0017] In combination with the second aspect, in a third possible implementation, the second detection branch includes two resistors connected in series, the two resistors connected in series in the second detection branch also include a fourth sampling resistor, and the first end of the target circuit is connected to the second end of the target circuit through the fourth sampling resistor and the second sampling resistor, wherein the ratio between the resistance value of the fourth sampling resistor and the resistance value of the second sampling resistor is less than or equal to the ratio between the resistance value of the third sampling resistor and the resistance value of the first sampling resistor.

[0018] In combination with the second aspect, in a fourth possible implementation, a level signal output by a comparator is obtained, wherein a first input terminal of the comparator is used to collect a first sampling voltage across a first sampling resistor, and a second input terminal is used to collect a second sampling voltage across a second sampling resistor, and the comparator is used to output a first level signal when the first sampling voltage is less than the second sampling voltage; and output a second level signal when the first sampling voltage is greater than or equal to the second sampling voltage. Afterwards, when the level signal output by the comparator is a second level signal, the target circuit is controlled to stop working.

[0019] In combination with the second aspect, in a fifth possible implementation, at a first moment after a preset time period has passed when the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, a comparison result of the absolute value of the first sampling voltage across the first sampling resistor and the absolute value of the second sampling voltage across the second sampling resistor is obtained; if the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a third difference, and the third difference is less than the first difference, the target circuit is controlled to stop working.

[0020] In combination with the second aspect, in a sixth possible implementation, the target circuit includes a power supply and a switching device or a plurality of switching devices connected in series coupled to both ends of the power supply, and the power supply includes a DC source or a capacitor.

[0021] In combination with the second aspect, in a seventh possible implementation, when the target circuit includes a switching device or a plurality of switching devices connected in series, the switching device in the target circuit can be controlled to be in an off state to control the target circuit to stop working.

[0022] In combination with the second aspect, in an eighth possible implementation, the switching device includes a power tube, a relay, or a contactor.

[0023] In a third aspect, the present application provides a power conversion device, which includes a short-circuit protection device and a target circuit provided by any possible implementation method of the first aspect to the first aspect.

[0024] It should be understood that the implementation and beneficial effects of the above-mentioned aspects of the present application can be referenced to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a short-circuit protection device provided by the prior art;

[0026] Figure 2a This is a schematic diagram of an application scenario of the power conversion device provided by the present application;

[0027] Figure 2b is another application scenario schematic diagram of the power conversion device provided by the present application;

[0028] Figure 3 It is a structural schematic diagram of the short-circuit protection device provided by the present application;

[0029] Figure 4 is another structural schematic diagram of the short-circuit protection device provided by the present application;

[0030] Figure 5 It is a schematic diagram of the change process of the first sampling voltage and the second sampling voltage when the two ends of the target circuit provided by the present application are short-circuited;

[0031] Figure 6 is another structural schematic diagram of the short-circuit protection device provided by the present application;

[0032] Figure 7 is another structural schematic diagram of the short-circuit protection device provided by the present application;

[0033] Figure 8 is another structural schematic diagram of the short-circuit protection device provided by the present application;

[0034] Fig. 9 is another structural schematic diagram of the short-circuit protection device provided by the present application;

[0035] Fig.10 It is another structural schematic diagram of the short-circuit protection device provided by the present application;

[0036] Fig.11 It is a flow chart of the short-circuit protection method of the target circuit provided in the present application. DETAILED DESCRIPTION

[0037] The short-circuit protection device provided in the present application is used to implement short-circuit protection for a power supply (such as a DC power supply or a capacitor), and can be arranged outside the device where the power supply that needs short-circuit protection is located, or can be arranged inside the device where the power supply that needs short-circuit protection is located. For example, the short-circuit protection device can be arranged in a power conversion device and connected in parallel with the target circuit in the power conversion device. Among them, the power conversion device includes a frequency converter, a ballast, a power adapter, an inverter, a DC / DC converter, etc., and the target circuit includes a power supply and a switching device coupled to both ends of the power supply or multiple switching devices connected in series. The power conversion device can be applied to electronic equipment power supply scenarios (electronic devices include smart phones, tablet computers, desktop computers, smart speakers, etc.), new energy power supply scenarios (such as photovoltaic power supply scenarios, wind power supply scenarios, etc.) and switch control scenarios (such as battery access and bypass, SVG module bypass control, etc.). The following is an example of an electronic equipment power supply scenario and a photovoltaic power supply scenario.

[0038] See also Figure 2a , Figure 2a Schematic diagram of an application scenario of the power conversion device provided by the present application. In the scenario of power supply of electronic equipment, the power conversion device provided by the present application is suitable for Figure 2a The power adapter shown in the figure has an input end connected to the power grid and an output end connected to the electronic device. The power adapter includes a short-circuit protection device and a target circuit (not shown) connected in parallel with the short-circuit protection device, wherein the short-circuit protection device is used to perform short-circuit protection on the target circuit. When the target circuit in the power adapter does not have a short-circuit fault, the power adapter can first invert the AC voltage (such as 220V) provided by the power grid into a first DC voltage, and then perform a DC conversion on the first DC voltage to obtain a second DC voltage, and output the second DC voltage to the electronic device, thereby realizing power supply to the electronic device. When a short-circuit fault occurs between the two ends of the target circuit, the short-circuit protection device in the power adapter can stop the target circuit from working in time, realize short-circuit protection of the power adapter, and then improve the safety of the power adapter when supplying power to the electronic device, and has strong applicability.

[0039] See also Figure 2b , Figure 2b Schematic diagram of another application scenario of the power conversion device provided by the present application. In the photovoltaic power supply scenario, the power conversion device provided by the present application is suitable for Figure 2bThe DC / DC converter or inverter in the power supply system shown is introduced below by taking the inverter as an example. The power supply system may include a photovoltaic string, a DC / DC converter and an inverter. Each photovoltaic string may include a plurality of photovoltaic modules connected in series and / or in parallel. The input end of the DC / DC converter is connected to the photovoltaic string, and the output end is connected to the input end of the inverter. The inverter includes a short-circuit protection device and a target circuit (not shown) connected in parallel with the short-circuit protection device, wherein the short-circuit protection device is used to perform short-circuit protection on the target circuit. When the target circuit in the inverter does not have a short-circuit fault, the DC / DC converter converts the DC voltage generated by the photovoltaic string connected thereto into a DC power with a preset voltage through a DC conversion, and outputs the DC power to the inverter, and the inverter inverts the DC power output by the DC / DC converter into AC power, thereby realizing power supply to various types of electrical equipment such as AC power grids or AC loads (such as household appliances). When a short circuit fault occurs between the two ends of the target circuit, the short circuit protection device in the inverter can stop the target circuit from working in time, thereby realizing short circuit protection for the inverter, thereby improving the safety of the power supply system and having strong applicability.

[0040] The above is only an example of the application scenarios of the short-circuit protection device provided by the present application, and is not an exhaustive list. The present application does not limit the application scenarios.

[0041] It should be noted that the target circuit can be a circuit composed of any device with a short circuit risk. For example, the target circuit can be a power supply and a switch device coupled to both ends of the power supply or multiple switch devices connected in series. The switch device includes but is not limited to a power tube (such as MOSFET, IGBT, triode, etc.), a relay, and a contactor. The power supply includes but is not limited to a DC power supply (such as a battery) or a capacitor. Exemplarily, when the power supply is a flying capacitor, the target circuit can be a circuit formed by connecting a branch where multiple power tubes are connected in series in a DC conversion circuit inside a multi-level DC converter in parallel with a flying capacitor.

[0042] Combine the following Figures 3 to 10 , taking the target circuit consisting of two MOSFETs connected in series and a DC power supply connected in parallel with the two MOSFETs as an example, the working principle of the short-circuit protection device provided in the present application is illustrated.

[0043] See also Figure 3 , Figure 3 Schematic diagram of a short circuit protection device provided by the present application. Figure 3 As shown, the target circuit 10 is a branch where MOSFETs S1 and S2 are connected in series and a DC power supply V battryThe short-circuit protection device 20 is a circuit formed in parallel, and includes a first detection branch 201, a second detection branch 202 and a controller 203. The first detection branch 201 is connected in parallel to the first end (i.e., the drain of S2) and the second end (i.e., the source of S1) of the target circuit 10, and the first detection branch 201 includes a first sampling resistor R11 and a first sampling capacitor C1 connected in parallel with R11. The second detection branch 202 is connected in parallel to the first end and the second end of the target circuit 10, and the second detection branch 202 includes a second sampling resistor R21, and when the target circuit 10 is in a working state (i.e., S1 and S2 are not short-circuited), the difference between the absolute value of the second sampling voltage at both ends of R21 and the absolute value of the first sampling voltage at both ends of R11 is a first difference.

[0044] In an optional embodiment, the controller 203 obtains a comparison result of the absolute value of the first sampling voltage across R11 and the absolute value of the second sampling voltage across R21, and when the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, it is determined that both S1 and S2 are short-circuited, and S1 and S2 are controlled to be in an off state, wherein the first difference is greater than the second difference.

[0045] It can be understood that when both S1 and S2 are short-circuited, the voltage across the first detection branch 201 and the voltage across the second detection branch 202 are both 0, and the absolute value of the second sampling voltage quickly drops to 0 along with the voltage across the second detection branch 202, while the absolute value of the first sampling voltage remains substantially unchanged due to the presence of C1, that is, whether a short-circuit fault occurs in the target circuit 10 can be determined by determining whether the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage changes. Since when both S1 and S2 are short-circuited, the voltage across the target circuit 10 (i.e., the power supply V battry The absolute value of the voltage across the two ends of the short-circuit current decreases very quickly, much faster than the rising speed of the short-circuit current, so the short-circuit fault can be quickly cut off in time to achieve effective protection of the target circuit 10. In addition, since the short-circuit protection device 20 is connected in parallel with the target circuit 10, even if the power supply V battry There is an inductance between any one of the two ends and the drain of S2 or the source of S1 that affects the rising speed of the short-circuit current. The speed at which the short-circuit protection device 20 performs short-circuit protection on the target circuit 10 is not affected by the inductance and has strong applicability.

[0046] For example, see Figure 4 , Figure 4 is another structural schematic diagram of the short-circuit protection device provided by the present application. Figure 4As shown, the first detection branch 201 includes a first sampling resistor R11, a first sampling capacitor C1 and a third sampling resistor R12, wherein R11 is connected in parallel with C1, R11 is connected in series with R12, and the first end of the target circuit 10 is connected to the second end of the target circuit 10 through R12 and R11 in sequence. The second detection branch 202 is a second sampling resistor R21, and R21 is connected in parallel to the two ends of the target circuit 10. The controller 203 is connected to the gate of S1 and the gate of S2, and is used to output a pulse width modulation (PWM) wave to S1 and S2 to control the working state of S1 and S2.

[0047] Depend on Figure 4 It can be seen from the circuit structure shown that when the target circuit 10 is in working state, that is, when S1 and S2 are not short-circuited, the first sampling voltage across R11 is less than the second sampling voltage across R21, and the first sampling voltage and the second sampling voltage are both greater than 0, that is, the first difference between the second sampling voltage and the first sampling voltage is greater than 0. When S1 and S2 are short-circuited, the voltage across the target circuit 10 drops rapidly, and the second sampling voltage drops to 0 quickly along with the voltage across the target circuit 10, while the first sampling voltage remains basically unchanged due to C1. For easy understanding, please refer to Figure 5 , Figure 5 Schematic diagram of the change process of the first sampling voltage and the second sampling voltage when the target circuit provided by the present application is short-circuited between the two ends. Figure 5 As shown, V10 and V20 are respectively the first sampling voltage at both ends of R11 when S1 and S2 are not short-circuited, V10, and the second sampling voltage at both ends of R21 is V20. When V20 is greater than V10 and greater than 0, when both S1 and S2 are short-circuited, the falling speed of the first sampling voltage V11 is less than the falling speed of the second sampling voltage V21. When V21 drops to less than or equal to V11, the short-circuit protection measure is triggered; when V20 is less than V10 and less than 0, when both S1 and S2 are short-circuited, the rising speed of the first sampling voltage V11 is less than the rising speed of the second sampling voltage V21. When V21 rises to greater than or equal to V11, the short-circuit protection measure is triggered.

[0048] In an optional embodiment, the controller 203 obtains a first sampling voltage across R11 and a second sampling voltage across R21, and when the first sampling voltage is greater than or equal to the second sampling voltage, that is, the second difference between the second sampling voltage and the first sampling voltage is less than or equal to 0, and the first difference is greater than the second difference, indicating that both S1 and S2 are short-circuited, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0049] It can be understood that, since the voltage drop rate at both ends of the target circuit 10 is much faster than the rise rate of the short-circuit current, the target circuit 10 with a short-circuit fault can be quickly and timely cut off to achieve short-circuit protection for the target circuit 10. Moreover, since the target circuit 10 is connected in parallel with the short-circuit protection device 20, the rapidity of the short-circuit protection by the short-circuit protection device 20 will not be affected by the inductance. In addition, the short-circuit protection device 20 in this embodiment only needs three resistors and one capacitor to detect whether a short-circuit fault occurs between the two ends of the target circuit 10, and the circuit structure is simple, which can reduce the circuit cost and has strong applicability.

[0050] In another optional embodiment, the controller 203 obtains the first sampling voltage across R11 and the second sampling voltage across R21, and obtains the first sampling voltage across R11 and the second sampling voltage across R21 at the first moment after the first sampling voltage is greater than or equal to the second sampling voltage (that is, the second difference between the second sampling voltage and the first sampling voltage is less than the first difference) after a preset time. If the first sampling voltage is still greater than or equal to the second sampling voltage at the first moment, that is, the third difference between the second sampling voltage and the first sampling voltage at the first moment is less than or equal to 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0051] In another optional implementation, the controller 203 obtains the first sampling voltage across R11 and the second sampling voltage across R21, and when the first sampling voltage is greater than or equal to the second sampling voltage (that is, the second difference between the second sampling voltage and the first sampling voltage is less than the first difference), the first sampling voltage and the second sampling voltage are filtered by software filtering, and at the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the first sampling voltage across R11 and the second sampling voltage across R21 are obtained. If the first sampling voltage is still greater than or equal to the second sampling voltage at the second moment, that is, the fourth difference between the second sampling voltage and the first sampling voltage at the second moment is less than or equal to 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0052] Understandably, Figure 4 Compared with the corresponding latter two embodiments Figure 4Corresponding to the first embodiment, the short-circuit protection can be prevented from being falsely triggered by delay or filtering, thereby improving the accuracy of the short-circuit protection device 20 when performing short-circuit protection, thereby improving the stability of the target circuit 10 and the equipment where the short-circuit protection device 20 is located during operation.

[0053] It should be noted that when the first sampling voltage and the second sampling voltage are both less than 0, the short-circuit protection device can still achieve short-circuit protection for the target circuit 10:

[0054] When the target circuit 10 is in working state, when the second sampling voltage is less than the first sampling voltage and less than 0, that is, when the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is greater than 0, the controller 203 obtains the first sampling voltage and the second sampling voltage, and when the absolute value of the first sampling voltage is greater than or equal to the absolute value of the second sampling voltage, that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference, indicating that a short circuit occurs in the target circuit 10, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0055] Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 in performing short-circuit protection can be improved by delaying or filtering.

[0056] Specifically, the controller 203 obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21, and obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21 at the first moment after the absolute value of the first sampling voltage is greater than or equal to the absolute value of the second sampling voltage (that is, the second difference is less than the first difference) after a preset time. If the absolute value of the first sampling voltage at the first moment is still greater than or equal to the absolute value of the second sampling voltage, that is, the third difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the first moment is less than or equal to 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, so that the target circuit 10 stops working.

[0057] The controller 203 obtains the first sampling voltage across R11 and the second sampling voltage across R21, and when the absolute value of the first sampling voltage is greater than or equal to the absolute value of the second sampling voltage (that is, the second difference is less than the first difference), filters the first sampling voltage and the second sampling voltage by software filtering, and obtains the first sampling voltage across R11 and the second sampling voltage across R21 at the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed. If the absolute value of the first sampling voltage at the second moment is still greater than or equal to the absolute value of the second sampling voltage, that is, the fourth difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the second moment is less than or equal to 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0058] When the target circuit 10 is in working state, the first sampling voltage is equal to the second sampling voltage, and the first sampling voltage and the second sampling voltage are both less than 0, that is, the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is equal to 0, the controller 203 obtains the first sampling voltage and the second sampling voltage, and when the absolute value of the first sampling voltage is greater than the absolute value of the second sampling voltage, that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference, indicating that a short circuit occurs in the target circuit 10, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0059] Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 in performing short-circuit protection can be improved by delaying or filtering.

[0060] Specifically, the controller 203 obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21, and obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21 at the first moment after the absolute value of the first sampling voltage is greater than the absolute value of the second sampling voltage (that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference) after a preset time. If the absolute value of the first sampling voltage at the first moment is still greater than the absolute value of the second sampling voltage, that is, the third difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the first moment is less than 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, so that the target circuit 10 stops working.

[0061] The controller 203 obtains the first sampling voltage across R11 and the second sampling voltage across R21, and when the absolute value of the first sampling voltage is greater than the absolute value of the second sampling voltage (that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference), the first sampling voltage and the second sampling voltage are filtered by software filtering, and at the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the first sampling voltage across R11 and the second sampling voltage across R21 are obtained. If the absolute value of the first sampling voltage is still greater than the absolute value of the second sampling voltage at the second moment, that is, the fourth difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the second moment is less than 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0062] Further, Figure 4 The second detection branch 202 shown may also include a second sampling capacitor connected in parallel with the second sampling resistor R21. Figure 6 Another structural schematic diagram of the short-circuit protection device is shown in FIG. Figure 6As shown, the second detection branch 202 also includes a second sampling capacitor C2 connected in parallel with R21. Among them, the capacitance value of C2 is smaller than the capacitance value of C1, so that when both S1 and S2 are short-circuited, the falling speed of the first sampling voltage is smaller than the falling speed of the second sampling voltage, thereby ensuring that when both S1 and S2 are short-circuited, the magnitude relationship between the first sampling voltage and the second sampling voltage will be reversed to trigger the short-circuit protection measure. In addition, C2 can filter out the peak component in the second sampling voltage at both ends of R21, which can avoid the situation where the short-circuit protection is falsely triggered due to the downward peak component, thereby improving the accuracy of the short-circuit protection device 20 when performing short-circuit protection, thereby improving the stability of the target circuit 10 and the equipment (such as power conversion equipment) where the short-circuit protection device 20 is located when working. Here, for the specific implementation method of the controller 203 performing short-circuit protection on the target circuit 10 according to the first sampling voltage and the second sampling voltage, please refer to Figure 4 The corresponding descriptions in the corresponding embodiments are not repeated here.

[0063] Further, Figure 6 The short circuit protection device 20 shown also includes a comparator, see Figure 7 Another structural schematic diagram of the short-circuit protection device is shown in FIG. Figure 7 As shown, the short-circuit protection device 20 also includes a comparator P1, the non-phase input terminal of P1 is used to collect the second sampled voltage V21 at both ends of R21, the inverting input terminal is used to collect the first sampled voltage V11 at both ends of R11, and the output terminal is connected to the controller 203, which is used to output a high level signal when V11 is less than V21; when V11 is greater than or equal to V21, it outputs a low level signal. Figure 7 It can be seen from the circuit structure shown that when the target circuit 10 is in the working state, V21 is greater than V11 and greater than 0 (that is, the first difference is greater than 0), so the comparator P1 outputs a high-level signal when the target circuit 10 is in the working state. Optionally, the non-inverting input terminal of the comparator P1 can also be used to collect the first sampled voltage V11 across R11, and the inverting input terminal is used to collect the second sampled voltage V21 across R21, and the present application does not limit this.

[0064] In an optional embodiment, the controller 203 obtains the level signal output by the comparator P1. When the level signal is a low level signal, that is, V21 is less than or equal to V11, that is, the second difference is less than the first difference, indicating that both S1 and S2 are short-circuited, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0065] It can be understood that, since the voltage drop speed at both ends of the target circuit 10 is much faster than the rise speed of the short-circuit current, the target circuit 10 with a short-circuit fault can be quickly and timely cut off to achieve short-circuit protection for the target circuit 10. Moreover, since the target circuit 10 is connected in parallel with the short-circuit protection device 20, the speed of the short-circuit protection by the short-circuit protection device 20 will not be affected by the inductance.

[0066] In another optional embodiment, the controller 203 obtains the level signal output by the comparator P1 at the first moment after a preset time period has passed since the comparator P1 outputs a low level signal. If the level signal is still a low level signal at the first moment, that is, V21 is less than or equal to V11 at the first moment, that is, the third difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0067] In another optional implementation, the controller 203 obtains the level signal output by the comparator P1, and when the level signal is a low level signal, filters the first sampling voltage and the second sampling voltage by software filtering, and obtains the level signal output by the comparator P1 at a second moment after completing the filtering of the first sampling voltage and the second sampling voltage. If the level signal is still a low level signal at the second moment, that is, the second sampling voltage is less than or equal to the first sampling voltage at the second moment, that is, the fourth difference is less than the first difference, indicating that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0068] Understandably, Figure 6 Compared with the corresponding latter two embodiments Figure 6 Corresponding to the first embodiment, the short-circuit protection can be prevented from being falsely triggered by delay or filtering, thereby improving the accuracy of the short-circuit protection device 20 when performing short-circuit protection, and thereby improving the stability of the target circuit 10 and the equipment where the short-circuit protection device 20 is located (such as a power conversion device).

[0069] It should be noted that when the first sampling voltage and the second sampling voltage are both less than 0, the short-circuit protection device can still achieve short-circuit protection for the target circuit 10:

[0070] When the target circuit 10 is in the working state, the comparator P1 outputs a low level signal when the second sampling voltage is less than the first sampling voltage and less than 0, that is, the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is greater than 0. The controller 203 obtains the level signal output by the comparator P1. When the level signal is a high level signal, that is, the first sampling voltage is less than the second sampling voltage and less than 0, that is, the second difference is less than the first difference, indicating that both S1 and S2 are short-circuited, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0071] Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 in performing short-circuit protection can be improved by delaying or filtering.

[0072] Specifically, the controller 203 obtains the level signal output by the comparator P1 at the first moment after a preset time period has passed since the comparator P1 outputs a high level signal. If the level signal at the first moment is still a high level signal, that is, the first sampling voltage is still less than the second sampling voltage and less than 0 at the first moment, that is, the third difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0073] The controller 203 obtains the level signal output by the comparator P1. When the level signal is a high level signal, the first sampling voltage and the second sampling voltage are filtered by software filtering. At the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the level signal output by the comparator P1 is obtained. If the level signal at the second moment is still a high level signal, that is, at the second moment, the first sampling voltage is still less than the second sampling voltage and less than 0, that is, the fourth difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0074] When the target circuit 10 is in working state, the second sampling voltage is equal to the first sampling voltage, and the first sampling voltage and the second sampling voltage are both less than 0, that is, the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is equal to 0, the comparator P1 outputs a low level signal. The controller 203 obtains the level signal output by the comparator P1. When the level signal is a high level signal, that is, the first sampling voltage is less than the second sampling voltage and less than 0, that is, the second difference is less than the first difference, indicating that both S1 and S2 are short-circuited, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state. Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 when performing short-circuit protection can also be improved by delaying or filtering.

[0075] Specifically, the controller 203 obtains the level signal output by the comparator P1 at the first moment after a preset time period has passed since the comparator P1 outputs a high level signal. If the level signal at the first moment is still a high level signal, that is, the first sampling voltage is still less than the second sampling voltage and less than 0 at the first moment, that is, the third difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0076] The controller 203 obtains the level signal output by the comparator P1. When the level signal is a high level signal, the first sampling voltage and the second sampling voltage are filtered by software filtering. At the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the level signal output by the comparator P1 is obtained. If the level signal at the second moment is still a high level signal, that is, at the second moment, the first sampling voltage is still less than the second sampling voltage and less than 0, that is, the fourth difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0077] For example, see Figure 8 , Figure 8 is another structural schematic diagram of the short-circuit protection device provided by the present application. Figure 4As shown, the first detection branch 201 includes a first sampling resistor R11, a first sampling capacitor C1 and a third sampling resistor R12, wherein R11 is connected in parallel with C1, R11 is connected in series with R12, and the first end of the target circuit 10 is connected to the second end of the target circuit 10 through R12 and R11 in sequence. The second detection branch 202 includes two second sampling resistors R21 and fourth sampling resistors R22 connected in series, and the first end of the target circuit 10 is connected to the second end of the target circuit 10 through R22 and R21 in sequence. The ratio between the resistance value of R22 and the resistance value of R21 is less than or equal to the ratio between the resistance value of R12 and the resistance value of R11. The controller 203 is connected to the gate of S1 and the gate of S2, and is used to output a PWM wave with adjustable duty cycle to S1 and S2 to control the working state of S1 and S2.

[0078] Since the ratio between the resistance value of R22 and the resistance value of R21 is less than or equal to the ratio between the resistance value of R12 and the resistance value of R11, it can be obtained that the first sampling voltage across R11 is less than or equal to the second sampling voltage across R21. Figure 8 It can be seen from the circuit structure shown that when the target circuit 10 is in working state, that is, when S1 and S2 are not short-circuited, the first sampling voltage across R11 is less than or equal to the second sampling voltage across R21, and the first sampling voltage and the second sampling voltage are both greater than 0, that is, the first difference between the second sampling voltage and the first sampling voltage is greater than or equal to 0. When S1 and S2 are short-circuited, the voltage across the target circuit 10 drops rapidly, and the second sampling voltage drops to 0 rapidly along with the voltage across the target circuit 10, while the first sampling voltage remains substantially unchanged due to C1.

[0079] In an optional embodiment, when the target circuit 10 is in a working state, the first sampling voltage is equal to the second sampling voltage, that is, the first difference is equal to 0, the controller 203 can obtain the first sampling voltage across R11 and the second sampling voltage across R21, and when the first sampling voltage is greater than the second sampling voltage, that is, the second difference between the second sampling voltage and the first sampling voltage is less than 0, that is, the first difference is greater than the second difference, indicating that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0080] In another optional embodiment, when the target circuit 10 is in a working state, the second sampling voltage is greater than the first sampling voltage, that is, the first difference is greater than 0, the controller 203 can obtain the first sampling voltage across R11 and the second sampling voltage across R21, and when the first sampling voltage is greater than or equal to the second sampling voltage, that is, the second difference between the second sampling voltage and the first sampling voltage is less than or equal to 0, that is, the first difference is greater than the second difference, indicating that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0081] It can be understood that, since the voltage drop rate at both ends of the target circuit 10 is much faster than the rise rate of the short-circuit current, the target circuit 10 with a short-circuit fault can be quickly and timely cut off to achieve short-circuit protection for the target circuit 10. Moreover, since the target circuit 10 is connected in parallel with the short-circuit protection device 20, the rapidity of the short-circuit protection by the short-circuit protection device 20 will not be affected by the inductance. In addition, after adding R22 to the second detection branch 202, the short-circuit protection device 20 in this embodiment can change the size between the first sampling voltage and the second sampling voltage according to actual needs by changing the resistance values ​​of R11, R12, R21 and R22, and has high flexibility.

[0082] In another optional embodiment, when the target circuit 10 is in the working state, the first difference is equal to 0, the controller 203 can obtain the first sampling voltage across R11 and the second sampling voltage across R21, and obtain the first sampling voltage across R11 and the second sampling voltage across R21 at the first moment after the first sampling voltage is greater than the second sampling voltage (that is, the first difference is greater than the second difference) after a preset time. If the first sampling voltage is still greater than the second sampling voltage at the first moment (that is, the third difference between the second sampling voltage and the first sampling voltage at the first moment is less than the first difference), it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, and a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0083] In another optional embodiment, when the target circuit 10 is in the working state, if the first difference is greater than 0, the controller 203 can obtain the first sampling voltage across R11 and the second sampling voltage across R21, and obtain the first sampling voltage across R11 and the second sampling voltage across R21 at the first moment after the first sampling voltage is greater than or equal to the second sampling voltage (that is, the first difference is greater than or equal to the second difference) after a preset time. If the first sampling voltage is still greater than or equal to the second sampling voltage at the first moment (that is, the third difference between the second sampling voltage and the first sampling voltage at the first moment is less than the first difference), it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, and a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0084] In another optional implementation, when the target circuit 10 is in a working state and the first difference is equal to 0, the controller 203 can obtain the first sampling voltage across R11 and the second sampling voltage across R21, and when the first sampling voltage is greater than the second sampling voltage (that is, the first difference is greater than the second difference), the first sampling voltage and the second sampling voltage are filtered by software filtering, and at a second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the first sampling voltage across R11 and the second sampling voltage across R21 are obtained. If the first sampling voltage is still greater than the second sampling voltage at the second moment (that is, the fourth difference between the second sampling voltage and the first sampling voltage at the second moment is less than the first difference), it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, and a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0085] In another optional embodiment, when the target circuit 10 is in working state, when the first difference is greater than 0, the controller 203 can obtain the first sampling voltage across R11 and the second sampling voltage across R21, and when the first sampling voltage is greater than or equal to the second sampling voltage (that is, the first difference is greater than or equal to the second difference), the first sampling voltage and the second sampling voltage are filtered by software filtering, and at the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the first sampling voltage across R11 and the second sampling voltage across R21 are obtained, if the first sampling voltage is still greater than or equal to the second sampling voltage at the second moment (that is, the fourth difference between the second sampling voltage and the first sampling voltage at the second moment is less than the first difference), it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, and a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0086] Understandably, Figure 8Compared with the corresponding latter two embodiments Figure 8 Corresponding to the first embodiment, the short-circuit protection can be prevented from being falsely triggered by delay or filtering, thereby improving the accuracy of the short-circuit protection device 20 when performing short-circuit protection, thereby improving the stability of the target circuit 10 and the equipment where the short-circuit protection device 20 is located during operation.

[0087] It should be noted that when the first sampling voltage and the second sampling voltage are both less than 0, the short-circuit protection device can still achieve short-circuit protection for the target circuit 10:

[0088] When the target circuit 10 is in working state, when the second sampling voltage is less than the first sampling voltage and less than 0, that is, when the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is greater than 0, the controller 203 obtains the first sampling voltage and the second sampling voltage, and when the absolute value of the first sampling voltage is greater than or equal to the absolute value of the second sampling voltage, that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference, indicating that a short circuit occurs in the target circuit 10, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0089] Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 in performing short-circuit protection can be improved by delaying or filtering.

[0090] Specifically, the controller 203 obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21, and obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21 at the first moment after the absolute value of the first sampling voltage is greater than or equal to the absolute value of the second sampling voltage (that is, the second difference is less than the first difference) after a preset time. If the absolute value of the first sampling voltage at the first moment is still greater than or equal to the absolute value of the second sampling voltage, that is, the third difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the first moment is less than or equal to 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, so that the target circuit 10 stops working.

[0091] The controller 203 obtains the first sampling voltage across R11 and the second sampling voltage across R21, and when the absolute value of the first sampling voltage is greater than or equal to the absolute value of the second sampling voltage (that is, the second difference is less than the first difference), filters the first sampling voltage and the second sampling voltage by software filtering, and obtains the first sampling voltage across R11 and the second sampling voltage across R21 at the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed. If the absolute value of the first sampling voltage at the second moment is still greater than or equal to the absolute value of the second sampling voltage, that is, the fourth difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the second moment is less than or equal to 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0092] When the target circuit 10 is in working state, the first sampling voltage is equal to the second sampling voltage, and the first sampling voltage and the second sampling voltage are both less than 0, that is, the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is equal to 0, the controller 203 obtains the first sampling voltage and the second sampling voltage, and when the absolute value of the first sampling voltage is greater than the absolute value of the second sampling voltage, that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference, indicating that a short circuit occurs in the target circuit 10, a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0093] Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 in performing short-circuit protection can be improved by delaying or filtering.

[0094] Specifically, the controller 203 obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21, and obtains the first sampling voltage at both ends of R11 and the second sampling voltage at both ends of R21 at the first moment after the absolute value of the first sampling voltage is greater than the absolute value of the second sampling voltage (that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference) after a preset time. If the absolute value of the first sampling voltage at the first moment is still greater than the absolute value of the second sampling voltage, that is, the third difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the first moment is less than 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, so that the target circuit 10 stops working.

[0095] The controller 203 obtains the first sampling voltage across R11 and the second sampling voltage across R21, and when the absolute value of the first sampling voltage is greater than the absolute value of the second sampling voltage (that is, the second difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is less than the first difference), the first sampling voltage and the second sampling voltage are filtered by software filtering, and at the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the first sampling voltage across R11 and the second sampling voltage across R21 are obtained. If the absolute value of the first sampling voltage is still greater than the absolute value of the second sampling voltage at the second moment, that is, the fourth difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage at the second moment is less than 0, and the first difference is greater than the third difference at this time, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state, thereby stopping the target circuit 10 from working.

[0096] Further, Figure 8 The second detection branch 202 shown may also include a second sampling capacitor connected in parallel with the second sampling resistor R21. Fig. 9 Another structural schematic diagram of the short-circuit protection device is shown in FIG. Fig. 9As shown, the second detection branch 202 also includes a second sampling capacitor C2 connected in parallel with R21. Among them, the capacitance value of C2 is smaller than the capacitance value of C1, so that when both S1 and S2 are short-circuited, the falling speed of the first sampling voltage is smaller than the falling speed of the second sampling voltage, thereby ensuring that when both S1 and S2 are short-circuited, the magnitude relationship between the first sampling voltage and the second sampling voltage will be reversed to trigger the short-circuit protection measure. In addition, C2 can filter out the peak component in the second sampling voltage at both ends of R21, which can avoid the situation where the short-circuit protection is falsely triggered due to the downward peak component, thereby improving the accuracy of the short-circuit protection device 20 when performing short-circuit protection, thereby improving the stability of the target circuit 10 and the equipment where the short-circuit protection device 20 is located when working. Here, for the specific implementation method of the controller 203 performing short-circuit protection on the target circuit 10 according to the first sampling voltage and the second sampling voltage, please refer to Figure 8 The corresponding descriptions in the corresponding embodiments are not repeated here.

[0097] Further, Fig. 9 The short circuit protection device 20 shown also includes a comparator, see Fig.10 Another structural schematic diagram of the short-circuit protection device shown in FIG. Fig.10 As shown, the short-circuit protection device 20 also includes a comparator P1, the non-phase input terminal of P1 is used to collect the first sampled voltage V11 at both ends of R11, the inverting input terminal is used to collect the second sampled voltage V21 at both ends of R21, and the output terminal is connected to the controller 203, which is used to output a high level signal when V11 is greater than or equal to V21; when V11 is less than V21, it outputs a low level signal. Fig.10 It can be seen from the circuit structure shown that by presetting the resistance values ​​of R11, R12, R21 and R22, when the target circuit 10 is in the working state, V21 is greater than V11 and greater than 0 (that is, the first difference is greater than 0), so the comparator P1 outputs a low-level signal when the target circuit 10 is in the working state. Optionally, the non-inverting input terminal of P1 can also be used to collect the second sampled voltage V21 at both ends of R21, and the inverting input terminal is used to collect the first sampled voltage V11 at both ends of R11, and the present application does not limit this.

[0098] In an optional embodiment, the controller 203 obtains the level signal output by the comparator P1. When the level signal is a high level signal, that is, V21 is less than or equal to V11, that is, the second difference is less than the first difference, indicating that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0099] It can be understood that, since the voltage drop speed at both ends of the target circuit 10 is much faster than the rise speed of the short-circuit current, the target circuit 10 with a short-circuit fault can be quickly and timely cut off to achieve short-circuit protection for the target circuit 10. Moreover, since the target circuit 10 is connected in parallel with the short-circuit protection device 20, the speed of the short-circuit protection by the short-circuit protection device 20 will not be affected by the inductance.

[0100] In another optional embodiment, the controller 203 obtains the level signal output by the comparator P1 at the first moment after a preset time period has passed since the comparator P1 outputs a high level signal. If the level signal at the first moment is still a high level signal, that is, V21 is less than or equal to V11 at the first moment, that is, the third difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0101] In another optional implementation, the controller 203 obtains the level signal output by the comparator P1, and when the level signal is a high level signal, filters the first sampling voltage and the second sampling voltage by software filtering, and obtains the level signal output by the comparator P1 at a second moment after completing the filtering of the first sampling voltage and the second sampling voltage. If the level signal at the second moment is still a high level signal, that is, V21 is less than or equal to V11 at the second moment, that is, the fourth difference is less than the first difference, indicating that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0102] Understandably, Fig.10 Compared with the corresponding latter two embodiments Fig.10 Corresponding to the first embodiment, the short-circuit protection can be prevented from being falsely triggered by delay or filtering, thereby improving the accuracy of the short-circuit protection device 20 when performing short-circuit protection, thereby improving the stability of the target circuit 10 and the equipment where the short-circuit protection device 20 is located during operation.

[0103] It should be noted that when the first sampling voltage and the second sampling voltage are both less than 0, the short-circuit protection device can still achieve short-circuit protection for the target circuit 10:

[0104] When the target circuit 10 is in working state, when the second sampling voltage is less than the first sampling voltage and less than 0, that is, when the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is greater than 0, the comparator P1 outputs a high level signal. The controller 203 obtains the level signal output by the comparator P1, and when the level signal is a low level signal, that is, the first sampling voltage is less than the second sampling voltage and less than 0, that is, the second difference is less than the first difference, indicating that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0105] Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 in performing short-circuit protection can be improved by delaying or filtering.

[0106] Specifically, the controller 203 obtains the level signal output by the comparator P1 at the first moment after a preset time period has passed since the comparator P1 outputs a low level signal. If the level signal at the first moment is still a low level signal, that is, the first sampling voltage is still less than the second sampling voltage and less than 0 at the first moment, that is, the third difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0107] The controller 203 obtains the level signal output by the comparator P1. When the level signal is a low level signal, the first sampling voltage and the second sampling voltage are filtered by software filtering. At the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the level signal output by the comparator P1 is obtained. If the level signal at the second moment is still a low level signal, that is, at the second moment, the first sampling voltage is still less than the second sampling voltage and less than 0, that is, the fourth difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0108] When the target circuit 10 is in working state, the second sampling voltage is equal to the first sampling voltage, and the first sampling voltage and the second sampling voltage are both less than 0, that is, the first difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is equal to 0, the comparator P1 outputs a high level signal. The controller 203 obtains the level signal output by the comparator P1, and when the level signal is a low level signal, that is, the first sampling voltage is less than the second sampling voltage and less than 0, that is, the second difference is less than the first difference, indicating that both S1 and S2 are short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0109] Furthermore, in order to avoid the short-circuit protection being triggered by mistake, the accuracy of the short-circuit protection device 20 in performing short-circuit protection can be improved by delaying or filtering.

[0110] Specifically, the controller 203 obtains the level signal output by the comparator P1 at the first moment after a preset time period has passed since the comparator P1 outputs a low level signal. If the level signal at the first moment is still a low level signal, that is, the first sampling voltage is still less than the second sampling voltage and less than 0 at the first moment, that is, the third difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0111] The controller 203 obtains the level signal output by the comparator P1. When the level signal is a low level signal, the first sampling voltage and the second sampling voltage are filtered by software filtering. At the second moment after the filtering of the first sampling voltage and the second sampling voltage is completed, the level signal output by the comparator P1 is obtained. If the level signal at the second moment is still a low level signal, that is, at the second moment, the first sampling voltage is still less than the second sampling voltage and less than 0, that is, the fourth difference is less than the first difference, it means that both S1 and S2 are short-circuited, that is, the target circuit 10 is short-circuited, then a PWM wave with a preset duty cycle is output to the gate of S1 and the gate of S2 respectively, so that S1 and S2 are in the off state.

[0112] See also Fig.11 , Fig.11 The short-circuit protection method for the target circuit provided in the present application is applicable to Figures 3 to 10 The controller 203 in the short-circuit protection device 20 shown. The short-circuit protection method of the target circuit may include the steps of:

[0113] S101, obtaining a comparison result of an absolute value of a first sampling voltage across a first sampling resistor in a first detection branch and an absolute value of a second sampling voltage across a second sampling resistor in a second detection branch.

[0114] Among them, the first detection branch is connected in parallel to the first end and the second end of the target circuit, the second detection branch is connected in parallel to the first end and the second end of the target circuit, the first detection branch includes a first sampling resistor and a first sampling capacitor connected in parallel with the first sampling resistor, the second detection branch includes a second sampling resistor, and when the target circuit is in a working state, the difference between the absolute value of the second sampling voltage across the second sampling resistor and the absolute value of the first sampling voltage across the first sampling resistor is a first difference.

[0115] In an optional implementation, the controller obtains a first sampling voltage across the first sampling resistor and a second sampling voltage across the second sampling resistor, and compares the absolute value of the first sampling voltage with the absolute value of the second sampling voltage to obtain a comparison result of the absolute value of the first sampling voltage and the absolute value of the second sampling voltage.

[0116] In another optional implementation, the controller obtains an electrical signal output by a comparator. The first input terminal of the comparator is used to collect a first sampling voltage across the first sampling resistor, and the second input terminal is used to collect a second sampling voltage across the second sampling resistor, and the comparator is used to output a first level signal when the first sampling voltage is less than the second sampling voltage; and output a second level signal when the first sampling voltage is greater than or equal to the second sampling voltage.

[0117] S102 , when the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, controlling the target circuit to stop operating.

[0118] Among them, the first difference is greater than the second difference, and the target circuit includes a switching device or multiple switching devices connected in series, and the switching device includes a power tube (such as MOSFET, IGBT, triode, etc.), a relay, a contactor, etc.

[0119] In an optional implementation, when the first difference is greater than the second difference, the controller controls each switch device in the target circuit to be in an off state.

[0120] In another optional implementation, when the level signal output by the comparator is a second level signal, the controller controls each switch device in the target circuit to be in an off state.

[0121] In a specific implementation, more operations performed by the controller in the short-circuit protection method of the target circuit provided in this application can be found in Figures 3 to 10The short-circuit protection device 20 shown and the implementation method performed by the controller 203 in its working principle are not described in detail here.

[0122] It should be noted that the controller 203 in the short-circuit protection device 20 provided in the present application can be an existing controller in the target circuit 10 and the equipment where the short-circuit protection device 20 is located (such as a power conversion device), or it can be another controller that is independent of the existing controller in the target circuit 10 and the equipment where the short-circuit protection device 20 is located. The present application does not impose any restrictions on this.

[0123] In the present application, the short-circuit fault can be quickly and timely cut off by a short-circuit protection device connected in parallel with the target circuit, thereby achieving effective protection of the target circuit, and the application is strong.

[0124] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A short circuit protection device, characterized in that: The short circuit protection device comprises a first detection branch, a second detection branch and a controller, wherein: The first detection branch is connected in parallel to a first end and a second end of a target circuit, the second detection branch is connected in parallel to a first end and a second end of the target circuit, the first detection branch includes a first sampling resistor, a third sampling resistor, and a first sampling capacitor connected in parallel with the first sampling resistor, the first sampling resistor and the third sampling resistor are connected in series, the second detection branch includes a second sampling resistor, and when the target circuit is in a working state, a difference between an absolute value of a second sampling voltage across the second sampling resistor and an absolute value of a first sampling voltage across the first sampling resistor is a first difference; The controller is used to obtain a comparison result of an absolute value of a first sampling voltage across the first sampling resistor and an absolute value of a second sampling voltage across the second sampling resistor, and filter the first sampling voltage and the second sampling voltage when the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference; and control the target circuit to stop working when the difference between the absolute value of the filtered second sampling voltage and the absolute value of the filtered first sampling voltage is a fourth difference, wherein the first difference is greater than the second difference and the fourth difference.

2. The short circuit protection device according to claim 1, characterized in that: The second detection branch further includes a second sampling capacitor, which is connected in parallel with the second sampling resistor, and a capacitance value of the second sampling capacitor is smaller than a capacitance value of the first sampling capacitor.

3. The short-circuit protection device according to claim 1 or 2, characterized in that: The second detection branch includes two resistors connected in series, the two resistors in series in the second detection branch also include a fourth sampling resistor, the first end of the target circuit is connected to the second end of the target circuit through the fourth sampling resistor and the second sampling resistor, wherein a ratio between a resistance value of the fourth sampling resistor and a resistance value of the second sampling resistor is less than or equal to a ratio between a resistance value of the third sampling resistor and a resistance value of the first sampling resistor.

4. The short circuit protection device according to any one of claims 1 to 3, characterized in that: The short-circuit protection device further includes a comparator, wherein a first input end of the comparator is used to collect a first sampled voltage across the first sampling resistor, a second input end of the comparator is used to collect a second sampled voltage across the second sampling resistor, and an output end of the comparator is connected to the controller, and is used to output a first level signal when the first sampled voltage is less than the second sampled voltage; When the first sampling voltage is greater than or equal to the second sampling voltage, outputting a second level signal; The controller is used for acquiring the level signal output by the comparator, and controlling the target circuit to stop working when the level signal output by the comparator is the second level signal.

5. The short circuit protection device according to any one of claims 1 to 4, characterized in that: The target circuit includes a power supply and a switch device or a plurality of switch devices connected in series coupled to both ends of the power supply, wherein the power supply includes a direct current source or a capacitor.

6. The short circuit protection device according to claim 5, characterized in that: The controller is used to control the switch device in the target circuit to be in an off state.

7. The short-circuit protection device according to claim 5 or 6, characterized in that: The switching device includes a power tube, a relay or a contactor.

8. A short circuit protection method for a target circuit, characterized in that: The method comprises: Obtaining a comparison result of an absolute value of a first sampling voltage across two ends of a first sampling resistor in a first detection branch and an absolute value of a second sampling voltage across two ends of a second sampling resistor in a second detection branch, wherein the first detection branch is connected in parallel to a first end and a second end of the target circuit, the second detection branch is connected in parallel to a first end and a second end of the target circuit, the first detection branch includes a first sampling resistor, a third sampling resistor, and a first sampling capacitor connected in parallel with the first sampling resistor, the first sampling resistor and the third sampling resistor are connected in series, the second detection branch includes a second sampling resistor, and when the target circuit is in a working state, a difference between an absolute value of a second sampling voltage across two ends of the second sampling resistor and an absolute value of a first sampling voltage across two ends of the first sampling resistor is a first difference; When the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, filtering the first sampling voltage and the second sampling voltage; When the difference between the absolute value of the filtered second sampled voltage and the absolute value of the filtered first sampled voltage is a fourth difference, the target circuit is controlled to stop working, wherein the first difference is greater than the second difference and the fourth difference.

9. The method according to claim 8, characterized in that The detection branch further includes a second sampling capacitor, which is connected in parallel with the second sampling resistor, and a capacitance value of the second sampling capacitor is smaller than a capacitance value of the first sampling capacitor.

10. The method according to claim 8 or 9, characterized in that: The second detection branch includes two resistors connected in series, the two resistors in series in the second detection branch also include a fourth sampling resistor, the first end of the target circuit is connected to the second end of the target circuit through the fourth sampling resistor and the second sampling resistor, wherein a ratio between a resistance value of the fourth sampling resistor and a resistance value of the second sampling resistor is less than or equal to a ratio between a resistance value of the third sampling resistor and a resistance value of the first sampling resistor.

11. The method according to any one of claims 8 to 10, characterized in that: The step of obtaining a comparison result between an absolute value of a first sampling voltage across a first sampling resistor in a first detection branch and an absolute value of a second sampling voltage across a second sampling resistor in a second detection branch includes: Acquire a level signal output by a comparator, wherein a first input terminal of the comparator is used to collect a first sampling voltage across the first sampling resistor, and a second input terminal of the comparator is used to collect a second sampling voltage across the second sampling resistor, and the comparator is used to output a first level signal when the first sampling voltage is less than the second sampling voltage; and output a second level signal when the first sampling voltage is greater than or equal to the second sampling voltage; When the difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference, controlling the target circuit to stop working comprises: When the level signal output by the comparator is the second level signal, the target circuit is controlled to stop working.

12. The method according to any one of claims 8 to 11, characterized in that: The target circuit includes a power supply and a switch device or a plurality of switch devices connected in series coupled to both ends of the power supply, wherein the power supply includes a direct current source or a capacitor.

13. The method according to claim 12, characterized in that The controlling the target circuit to stop working includes: The switch device in the target circuit is controlled to be in an off state.

14. The method according to claim 12 or 13, characterized in that The switching device includes a power tube, a relay or a contactor.

15. A power conversion device, characterized in that: The power conversion device comprises the short-circuit protection device as claimed in any one of claims 1 to 7 and the target circuit.

Images