Short circuit protection circuit

Abstract

The embodiment of the utility model provides a short-circuit protection circuit, and the circuit comprises a sampling resistor which is connected to a main loop, and the parasitic inductance of the sampling resistor can generate an induction signal based on the current in the main loop; the clamping circuit is connected to the sampling resistor and clamps the voltage of the sensing signal to a first threshold voltage so as to provide a clamping signal; the first compensation rectification circuit is connected to the first output end of the clamping circuit, the second compensation rectification circuit is connected to the second output end of the clamping circuit, and the first compensation rectification circuit and the second compensation rectification circuit can carry out power factor compensation and rectification on the clamping signal. The clamping signal is converted into an intermediate signal with a predetermined waveform; and the output circuit is connected to the first compensation rectification circuit and the second compensation rectification circuit so as to receive the intermediate signal, and can generate an output signal under the condition that the voltage of the intermediate signal is greater than a second threshold voltage so as to indicate that the main loop is short-circuited.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of electrical equipment, and more particularly to a short-circuit protection circuit. Background Art

[0002] In AC power supply scenarios, or DC power supply scenarios with inverters and rectification, when a short circuit occurs, the direction of the short-circuit current is uncertain. Precision resistors are typically used to convert the short-circuit current into a voltage for signal processing. However, regardless of the package type, precision resistors inevitably have leads or parasitic inductance. During surges or short circuits, large currents flow through the sampling resistors. The transient voltage generated by these parasitic inductances can affect the detection accuracy of circuit sampling and even cause overvoltage damage to the device. Utility Model Content

[0003] An object of the present disclosure is to provide a short circuit protection circuit to at least partially solve the above problems.

[0004] In a first aspect of the present disclosure, a short-circuit protection circuit is provided, comprising: a sampling resistor connected to a main circuit to be protected, the parasitic inductance of the sampling resistor being capable of generating an induction signal based on the current in the main circuit; a clamping circuit connected to both ends of the sampling resistor and configured to clamp the voltage of the induction signal to a first threshold voltage to provide a clamping signal; a first compensation rectifier circuit and a second compensation rectifier circuit, the first compensation rectifier circuit being connected to a first output end of the clamping circuit, the second compensation rectifier circuit being connected to a second output end of the clamping circuit, the first compensation rectifier circuit and the second compensation rectifier circuit being capable of performing power factor compensation and rectification on the clamping signal to convert the clamping signal into an intermediate signal having a predetermined waveform; and an output circuit connected to the first compensation rectifier circuit and the second compensation rectifier circuit to receive the intermediate signal and, when the voltage of the intermediate signal is greater than a second threshold voltage, being capable of generating an output signal to indicate that a short circuit has occurred in the main circuit, wherein the second threshold voltage is greater than the first threshold voltage.

[0005] In an embodiment of the present disclosure, a sampling resistor is used to detect short-circuit current in the main circuit in real time. A clamping circuit is then used to clamp the voltage of the sensing signal generated by the sampling resistor to a first threshold voltage to prevent overvoltage damage to the device. A first compensating rectifier circuit and a second compensating rectifier circuit are then used to convert the clamped signal into an intermediate signal with a predetermined waveform. When the voltage of the intermediate signal exceeds a second threshold voltage, an output circuit is used to generate an output signal to indicate a short circuit in the main circuit. This approach allows for both accurate short-circuit current detection and reliable protection of components in the circuit.

[0006] In some embodiments, the clamping circuit includes: a first resistor, a first end of which is connected to the first end of the sampling resistor; a second resistor, a first end of which is connected to the second end of the sampling resistor; a first capacitor, one end of which is connected to ground and the other end of which is connected to the second end of the first resistor; a second capacitor, one end of which is connected to ground and the other end of which is connected to the second end of the second resistor; a third capacitor, one end of which is connected to a node between the first resistor and the first capacitor and the other end of which is connected to a node between the second resistor and the second capacitor; a first diode, an anode of which is connected to a node between the first resistor and the first capacitor and a cathode of which is connected to a node between the second resistor and the second capacitor; and a second diode, an anode of which is connected to a node between the second resistor and the first diode and a cathode of which is connected to a node between the first resistor and the first diode.

[0007] In some embodiments, the first compensation rectifier circuit includes: a third resistor, whose first end is connected to the cathode of the second diode; a fourth resistor, whose first end is connected to the anode of the second diode; a first operational amplifier, whose positive input is connected to the second end of the third resistor and whose negative input is connected to the second end of the fourth resistor; a fifth resistor, whose first end is connected to the node between the first operational amplifier and the third resistor and whose second end is connected to ground; a fourth capacitor, the fourth capacitor and the fifth resistor are connected in parallel; a third diode, whose anode is connected to the node between the first operational amplifier and the fourth resistor and whose cathode is connected to the output of the first operational amplifier; a fourth diode, whose anode is connected to the node between the first operational amplifier and the third diode; a sixth resistor, whose first end is connected to the node between the fourth resistor and the third diode and whose second end is connected to the cathode of the fourth diode; and a fifth capacitor, the fifth capacitor and the sixth resistor are connected in parallel.

[0008] In some embodiments, the first compensation rectifier circuit further includes: a seventh resistor, a first end of which is connected to a node between the fourth diode and the sixth resistor; a sixth capacitor, one end of which is connected to the second end of the seventh resistor and the other end is connected to ground.

[0009] In some embodiments, the second compensation rectifier circuit includes: an eighth resistor, a first end of which is connected to the anode of the second diode; a ninth resistor, a first end of which is connected to the cathode of the second diode; a second operational amplifier, a positive input of which is connected to the second end of the eighth resistor and a negative input of which is connected to the second end of the ninth resistor; a tenth resistor, a first end of which is connected to the node between the second operational amplifier and the eighth resistor and a second end of which is connected to ground; a seventh capacitor, the seventh capacitor and the tenth resistor are connected in parallel; a fifth diode, anode of which is connected to the node between the second operational amplifier and the ninth resistor and a cathode of which is connected to the output of the second operational amplifier; a sixth diode, anode of which is connected to the node between the second operational amplifier and the fifth diode; an eleventh resistor, a first end of which is connected to the node between the ninth resistor and the fifth diode and a second end of which is connected to the cathode of the sixth diode; and an eighth capacitor, the eighth capacitor and the eleventh resistor are connected in parallel.

[0010] In some embodiments, the second compensation rectifier circuit further includes: a twelfth resistor, a first end of which is connected to a node between the sixth diode and the eleventh resistor; a ninth capacitor, one end of which is connected to the second end of the twelfth resistor and the other end is connected to ground.

[0011] In some embodiments, the short-circuit protection circuit further includes a power supply to provide power input to the first compensation rectifier circuit, the second compensation rectifier circuit, and the output circuit.

[0012] In some embodiments, the output circuit includes: a thirteenth resistor, a first end of which is connected to a power supply; a fourteenth resistor, a first end of which is connected to the second end of the thirteenth resistor and a second end of which is connected to ground; a first comparison circuit, a first input end of which is connected to the first compensation rectifier circuit and a second input end of which is connected to a node between the thirteenth resistor and the fourteenth resistor; and a second comparison circuit, a first input end of which is connected to the second compensation rectifier circuit and a second input end of which is connected to a node between the thirteenth resistor and the fourteenth resistor.

[0013] In some embodiments, the first comparison circuit includes: a third operational amplifier, whose positive input terminal is connected to the first compensation rectifier circuit and whose negative input terminal is connected to the node between the thirteenth resistor and the fourteenth resistor; a seventh diode, whose anode is connected to the output terminal of the third operational amplifier; a fifteenth resistor, whose first end is connected to the cathode of the seventh diode and whose second end is connected to the node between the third operational amplifier and the first compensation rectifier circuit; and an eighth diode, whose anode is connected to the node between the third operational amplifier and the seventh diode.

[0014] In some embodiments, the second comparison circuit includes: a fourth operational amplifier, whose positive input is connected to the second compensation rectifier circuit and whose negative input is connected to the node between the thirteenth resistor and the fourteenth resistor; a ninth diode, whose anode is connected to the output of the fourth operational amplifier; a sixteenth resistor, whose first end is connected to the cathode of the eighth diode and whose second end is connected to the node between the fourth operational amplifier and the second compensation rectifier circuit; and a tenth diode, whose anode is connected to the node between the fourth operational amplifier and the ninth diode and whose cathode is connected to the cathode of the eighth diode.

[0015] In some embodiments, the output circuit further includes a seventeenth resistor having a first end connected to a node between the eighth diode and the tenth diode and a second end connected to ground.

[0016] It should be understood that the content described in this content section is not intended to limit the key features or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, wherein:

[0018] Figure 1 A circuit diagram of a short circuit protection circuit according to an embodiment of the present disclosure is shown;

[0019] Figure 2 shows a waveform diagram of signal changes at multiple nodes in a short-circuit protection circuit under overvoltage protection according to an embodiment of the present disclosure;

[0020] Figure 3 shows a waveform diagram of signal changes at multiple nodes in a short-circuit protection circuit during a compensation rectification process according to an embodiment of the present disclosure; and

[0021] Figure 4 A waveform diagram of signal changes at multiple nodes in a short-circuit protection circuit under short-circuit protection according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0023] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "one example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or identical objects.

[0024] As described above, in AC power supply scenarios, or in DC power supply scenarios with inverter and rectification, when a short circuit occurs, the direction of the short circuit current is uncertain. Usually, a precision resistor is used to convert the short circuit current into a voltage for signal processing. However, no matter what kind of package the precision resistor is, there are inevitably leads or parasitic inductances. When there is a surge or short circuit, a large current will flow through the sampling resistor. The instantaneous voltage generated by these parasitic inductances will affect the detection accuracy of the circuit sampling and may even cause overvoltage damage to the device. In the following, we will combine Figures 1 to 4 The principles of the present disclosure are described.

[0025] Figure 1 FIG. 1 shows a circuit diagram of a short circuit protection circuit 100 according to an embodiment of the present disclosure. Figure 1 As shown, the short-circuit protection circuit 100 generally includes a sampling resistor 101, a clamping circuit 110, a first compensating rectifier circuit 120, a second compensating rectifier circuit 130, and an output circuit 140. The sampling resistor 101 is connected to the main circuit 200 to be protected. The parasitic inductance 102 of the sampling resistor 101 can generate a sensing signal based on the current in the main circuit 200.

[0026] The clamping circuit 110 is connected to both ends of the sampling resistor 101 and is configured to clamp the voltage of the induced signal to a first threshold voltage to provide a clamping signal. The first compensating rectifier circuit 120 and the second compensating rectifier circuit 130 are respectively connected to the first output terminal and the second output terminal of the clamping circuit. The first compensating rectifier circuit 120 and the second compensating rectifier circuit 130 are capable of performing power factor compensation and rectification on the clamping signal to convert the clamping signal into an intermediate signal having a predetermined waveform. The output circuit 140 is connected to the first compensating rectifier circuit 120 and the second compensating rectifier circuit 130 to receive the intermediate signal and, when the voltage of the intermediate signal is greater than the second threshold voltage, is capable of generating an output signal to indicate a short circuit in the main circuit.

[0027] In one embodiment, the main circuit 200 may include a MOS transistor for short-circuit protection. For example, assuming the short-circuit current cutoff threshold is 1000 amperes (A) and the MOS transistor's cutoff time is 100 nanoseconds (ns), the rate of change of the current over time, di / dt, when the MOS transistor is turned off is 10A / ns. Assuming the sampling resistor 101 has a resistance of 250 microohms (μΩ) and the parasitic inductance 102 of the sampling resistor 101 is 1 nanohenry (nH), the voltage of the induced signal can be calculated using the following formula:

[0028] Vlr=Lr*di / dt=1nH*10A / ns=10V

[0029] Wherein, Vlr represents the voltage of the induced signal, and Lr represents the parasitic inductance 102 .

[0030] Figure 2 The following diagrams illustrate signal waveforms of multiple nodes in a short-circuit protection circuit 100 under overvoltage protection according to an embodiment of the present disclosure. Chart 1 shows a diagram of short-circuit current variation in the main loop 200 according to an embodiment of the present disclosure, Chart 2 shows a diagram of voltage variation of the induced signal according to an embodiment of the present disclosure, and Chart 3 shows a diagram of voltage variation of the clamping signal according to an embodiment of the present disclosure.

[0031] like Figure 2 As shown in Figures 1 and 2, a large short-circuit current can cause a large instantaneous voltage to be generated in the parasitic inductance 102 of the sampling resistor 101, which can easily affect the accuracy of short-circuit current detection and damage electronic components. Therefore, it is necessary to use the clamping circuit 110 to limit the voltage of the sensing signal to provide overvoltage protection for electronic components.

[0032] In one embodiment, Figure 1 As shown, the clamping circuit 110 includes a first resistor 111, a second resistor 112, a first capacitor 113, a second capacitor 114, a third capacitor 115, a first diode 116, and a second diode 117. A first end of the first resistor 111 is connected to a first end of the sampling resistor 101. A first end of the second resistor 112 is connected to a second end of the sampling resistor 101. The first resistor 111 and the second resistor 112 can limit the current of the sensing signal to minimize the energy of the sensing signal.

[0033] Continue to refer Figure 1 , one end of the first capacitor 113 is connected to the ground and the other end is connected to the second end of the first resistor 111. One end of the second capacitor 114 is connected to the ground and the other end is connected to the second end of the second resistor 112. One end of the third capacitor 115 is connected to the node between the first resistor 111 and the first capacitor 113 and the other end is connected to the node between the second resistor 112 and the second capacitor 114.

[0034] In one embodiment, the first capacitor 113 and the second capacitor 114 can be common-mode capacitors, and the third capacitor 115 can be a differential-mode capacitor to filter the induced signal. It should be understood that based on the teachings of this disclosure, those skilled in the art can conceive of other devices to implement the above-mentioned filtering function, and these implementations fall within the scope of this disclosure.

[0035] Continue to refer Figure 1 The anode of the first diode 116 is connected to the node between the first resistor 111 and the first capacitor 113, and the cathode is connected to the node between the second resistor 112 and the second capacitor 114. The anode of the second diode 117 is connected to the node between the second resistor 112 and the first diode 116, and the cathode is connected to the node between the first resistor 111 and the first diode 116.

[0036] like Figure 2 As shown in Figure 3, the forward voltage drop of the diode is used for clamping protection, which can clamp the voltage of the sensing signal to a first threshold voltage (e.g., -1.2V or 1.2V) to provide a clamping signal with a lower voltage amplitude, thereby preventing the voltage of the sensing signal from damaging electronic components.

[0037] In one embodiment, Figure 1 As shown, the first compensation rectifier circuit 120 includes a third resistor 121, a fourth resistor 122, a fifth resistor 124, a fourth capacitor 125, a third diode 126, a fourth diode 127, a sixth resistor 128, a fifth capacitor 129, a seventh resistor 1210, and a sixth capacitor 1211. A first end of the third resistor 121 is connected to the cathode of the second diode 117. A first end of the fourth resistor 122 is connected to the anode of the second diode 117. The third resistor 121 and the fourth resistor 122 can limit the current of the clamp signal.

[0038] The positive input terminal of the first operational amplifier 123 is connected to the second terminal of the third resistor 121, and the negative input terminal is connected to the second terminal of the fourth resistor 122. The first end of the fifth resistor 124 is connected to the node between the first operational amplifier 123 and the third resistor 121, and the second end is connected to ground. The fourth capacitor 125 and the fifth resistor 124 are connected in parallel. The anode of the third diode 126 is connected to the node between the first operational amplifier 123 and the fourth resistor 122, and the cathode is connected to the output terminal of the first operational amplifier 123. The anode of the fourth diode 127 is connected to the node between the first operational amplifier 123 and the third diode 126. The first end of the sixth resistor 128 is connected to the node between the fourth resistor 122 and the third diode 126, and the second end thereof is connected to the cathode of the fourth diode 127. The fifth capacitor 129 and the sixth resistor 128 are connected in parallel.

[0039] In one embodiment, the fourth capacitor 125 and the fifth capacitor 129 can perform power factor compensation on the clamped signal. For example, the fourth capacitor 125 and the fifth capacitor 129 can use the same capacitance, denoted as C1. The fifth resistor 124 and the sixth resistor 128 can have the same resistance value, denoted as R1. Assuming that the resistance of the sampling resistor is Rsamp, the capacitance of the fourth capacitor 125 and the fifth capacitor 129 can be determined by the following formula:

[0040] C1=Lr / (Rsamp / R1)

[0041] Continue to refer Figure 1 The first end of the seventh resistor 1210 is connected to the node between the fourth diode 127 and the sixth resistor 128. One end of the sixth capacitor 1211 is connected to the second end of the seventh resistor 1210, and the other end is connected to ground. The filter circuit formed by the seventh resistor 1210 and the sixth capacitor 1211 can further filter the clamped signal.

[0042] In one embodiment, Figure 1 As shown, the second compensation rectifier circuit 130 includes an eighth resistor 131, a ninth resistor 132, a second operational amplifier 133, a tenth resistor 134, a seventh capacitor, a fifth diode 136, a sixth diode 137, an eleventh resistor 138, an eighth capacitor 139, a twelfth resistor 1310, and a ninth capacitor 1311. A first end of the eighth resistor 131 is connected to the anode of the second diode 117. A first end of the ninth resistor 132 is connected to the cathode of the second diode 117. The eighth resistor 131 and the ninth resistor 132 can limit the current of the clamp signal.

[0043] The positive input terminal of the second operational amplifier 133 is connected to the second end of the eighth resistor 131 and the negative input terminal is connected to the second end of the ninth resistor 132. The first end of the tenth resistor 134 is connected to the node between the second operational amplifier 133 and the eighth resistor 131 and the second end thereof is connected to ground. The seventh capacitor 135 and the tenth resistor 134 are connected in parallel. The anode of the fifth diode 136 is connected to the node between the second operational amplifier 133 and the ninth resistor 132 and the cathode thereof is connected to the output terminal of the second operational amplifier 133. The anode of the sixth diode 137 is connected to the node between the second operational amplifier 133 and the fifth diode 136. The first end of the eleventh resistor 138 is connected to the node between the ninth resistor 132 and the fifth diode 136 and the second end thereof is connected to the cathode of the sixth diode 137. The eighth capacitor 139 and the eleventh resistor 138 are connected in parallel.

[0044] In one embodiment, the seventh capacitor 135 and the eighth capacitor 139 can perform power factor compensation on the clamped signal. For example, the seventh capacitor 135 and the eighth capacitor 139 can use the same capacitance, denoted as C2. The tenth resistor 134 and the eleventh resistor 138 can have the same resistance value, denoted as R2. Assuming that the resistance of the sampling resistor is Rsamp, the capacitance of the fourth capacitor 125 and the fifth capacitor 129 can be determined by the following formula:

[0045] C2=Lr / (Rsamp / R2)

[0046] In one embodiment, the capacitances of the fourth capacitor 125, the fifth capacitor 129, the seventh capacitor 135, and the eighth capacitor 139 can be the same. The resistances of the fifth resistor 124, the sixth resistor 128, the tenth resistor 134, and the eleventh resistor 138 can be the same. It should be understood that the values ​​of the above-mentioned capacitors and resistors can be determined according to actual working requirements and are not limited in this disclosure.

[0047] Continue to refer Figure 1 The first end of the twelfth resistor 1310 is connected to the node between the sixth diode 137 and the eleventh resistor 138. One end of the ninth capacitor 1311 is connected to the second end of the twelfth resistor 1310, and the other end is connected to ground. The filter circuit formed by the twelfth resistor 1310 and the ninth capacitor 1311 can further filter the clamped signal.

[0048] In one embodiment, the short circuit protection circuit 100 further includes a power supply 150 to provide power input to the first compensating rectifier circuit 120, the second compensating rectifier circuit 130, and the output circuit 140. The power supply 150 may be, for example, an AC power supply.

[0049] In one embodiment, first operational amplifier 123 and second operational amplifier 133 can be dual-powered operational amplifiers. The operational amplifier circuit formed by first operational amplifier 123 and second operational amplifier 133 can precisely rectify the clamped signal to convert the short-circuit waveforms of the positive and negative power supplies into a rectified waveform of a single power supply, thereby generating an intermediate signal.

[0050] Figure 3 The following diagrams illustrate signal waveforms of multiple nodes in a short-circuit protection circuit 100 during a compensation rectification process according to an embodiment of the present disclosure. Chart 4 shows a voltage variation diagram across the sampling resistor 101 according to an embodiment of the present disclosure, and Chart 5 shows a current variation diagram of the short-circuit current and a voltage variation diagram of the intermediate signal according to an embodiment of the present disclosure.

[0051] In one embodiment, Figure 3As shown in Figure 4, at the starting position, the voltage across the sampling resistor 101 is elevated due to the presence of parasitic inductance 102, representing an error introduced by the parasitic inductance. Therefore, reactive compensation is required for the sampled signal using the capacitors in the first compensation rectifier circuit 120 and the second compensation rectifier circuit 130 to obtain a more accurate sampled signal.

[0052] In one embodiment, Figure 3 As shown in Figure 5, curve 501 represents the short-circuit current curve, and curve 502 represents the intermediate signal curve after compensation and rectification. It is easy to see that the curve of the intermediate signal after processing by the first compensation and rectification circuit 120 and the second compensation and rectification circuit 130 substantially coincides with the short-circuit current curve over a certain period of time. The bend in curve 502 represents the short-circuit trigger threshold. When the short-circuit current reaches the preset threshold, curve 502 is pulled high by the output circuit 140 connected to the back end. The operating principle of the output circuit 140 will be described in detail below.

[0053] Re-reference Figure 1 In one embodiment, the output circuit 140 includes a thirteenth resistor 141, a fourteenth resistor 142, a first comparison circuit 143, and a second comparison circuit 144. A first end of the thirteenth resistor 141 is connected to the power supply 150. A first end of the fourteenth resistor 142 is connected to the second end of the thirteenth resistor 141 and a second end thereof is connected to ground. A first input end of the first comparison circuit 143 is connected to the first compensation rectifier circuit 120 and a second input end is connected to a node between the thirteenth resistor 141 and the fourteenth resistor 142. A first input end of the second comparison circuit 144 is connected to the second compensation rectifier circuit 130 and a second input end is connected to a node between the thirteenth resistor 141 and the fourteenth resistor 142. In one embodiment, the resistance values ​​of the thirteenth resistor 141 and the fourteenth resistor 142 can be determined according to a desired short circuit trigger threshold.

[0054] In one embodiment, the first comparison circuit 143 includes a third operational amplifier 1431, a seventh diode 1432, a fifteenth resistor 1433, and an eighth diode 1434. The positive input terminal of the third operational amplifier 1431 is connected to the first compensation rectifier circuit 120, and the negative input terminal thereof is connected to the node between the thirteenth resistor 141 and the fourteenth resistor 142. The anode of the seventh diode 1432 is connected to the output terminal of the third operational amplifier 1431. The first end of the fifteenth resistor 1433 is connected to the cathode of the seventh diode 1432, and the second end thereof is connected to the node between the third operational amplifier 1431 and the first compensation rectifier circuit 120. The anode of the eighth diode 1434 is connected to the node between the third operational amplifier 1431 and the seventh diode 1432.

[0055] In one embodiment, the second comparison circuit 144 includes a fourth operational amplifier 1441, a ninth diode 1442, a sixteenth resistor 1443, and a tenth diode 1444. The positive input terminal of the fourth operational amplifier 1441 is connected to the second compensation rectifier circuit 130, and the negative input terminal thereof is connected to the node between the thirteenth resistor 141 and the fourteenth resistor 142. The anode of the ninth diode 1442 is connected to the output terminal of the fourth operational amplifier 1441. The first end of the sixteenth resistor 1443 is connected to the cathode of the eighth diode 1442, and the second end thereof is connected to the node between the fourth operational amplifier 1441 and the second compensation rectifier circuit 130. The anode of the tenth diode 1444 is connected to the node between the fourth operational amplifier 1441 and the ninth diode 1442, and the cathode thereof is connected to the cathode of the eighth diode 1434.

[0056] In one embodiment, the negative input terminals of the third operational amplifier 1431 and the fourth operational amplifier 1441 can receive the voltage of the circuit where the thirteenth resistor 141 and the fourteenth resistor 142 are located, and use this voltage as a reference voltage. The positive input terminals of the third operational amplifier 1431 and the fourth operational amplifier 1441 can receive the intermediate signal and compare the voltage of the intermediate signal with the reference voltage. The reference voltage can be equal to the second threshold voltage (e.g., 2.5V).

[0057] Figure 4 The following diagrams illustrate signal waveforms of multiple nodes in the short-circuit protection circuit 100 under short-circuit protection according to an embodiment of the present disclosure. Chart 6 shows a voltage variation diagram of an intermediate signal and a schematic diagram of a second threshold voltage according to an embodiment of the present disclosure, and Chart 7 shows a voltage variation diagram of an output signal according to an embodiment of the present disclosure.

[0058] In one embodiment, Figure 4 As shown in Figure 6, curve 601 represents the variation curve of the intermediate signal, and line 602 represents the horizontal line of the second threshold voltage. As can be seen, when curve 601 passes through line 602, it begins to bend, indicating that the short-circuit triggering threshold has been reached, and curve 502 will be pulled higher.

[0059] In one embodiment, Figure 4 As shown in Graph 7, when the voltage of the intermediate signal is greater than the second threshold voltage, first comparison circuit 143 or second comparison circuit 144 generates an output signal with a certain voltage amplitude. Otherwise, as shown in the first half of curve 701, the output of first comparison circuit 143 or second comparison circuit 144 is zero, and short-circuit protection circuit 100 is in a standby state.

[0060] In one embodiment, the first comparison circuit 143 and the second comparison circuit 144 may employ positive feedback latching. It should be noted that the positive feedback comparison voltage must always be greater than the reference voltage; otherwise, when the current commutates, the outputs of the first comparison circuit 143 and the second comparison circuit 144 may be unlocked.

[0061] Taking the first comparison circuit 143 as an example, assuming that the resistance values ​​of the first resistor 111, the fourth resistor 122, the sixth resistor 128, the seventh resistor 1210, the fifteenth resistor 1433, the thirteenth resistor 141, and the fourteenth resistor 142 are R111, R122, R128, R1210, R1433, R141, and R142, respectively, it is necessary to ensure that R1433 / (R111+R122+R128+R1210)>R141 / R142. The second comparison circuit 144 is similar and will not be further described here.

[0062] In one embodiment, the output circuit 140 further includes a seventeenth resistor 145. A first end of the seventeenth resistor 145 is connected to a node between the eighth diode 1434 and the tenth diode 1444, and a second end thereof is connected to ground to provide a stable output signal.

[0063] By employing an output circuit comprised of two comparator circuits, a signal can be latched and output after a short circuit is detected, indicating that a short circuit has occurred in the main circuit 200. In one embodiment, the output signal can serve as an input to a component such as a driver chip, for example, to promptly shut down the driver circuit. It can also serve as an input signal to an indicator light, indicating that the main circuit 200 needs to be shut down. It should be understood that, based on the teachings of this disclosure, those skilled in the art may conceive of other devices that implement the aforementioned functions, and such implementations fall within the scope of this disclosure.

[0064] While various embodiments of the present disclosure have been described above, the above descriptions are illustrative, non-exhaustive, and not intended to be limiting of the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable other persons skilled in the art to understand the embodiments disclosed herein.

Claims

1. A short circuit protection circuit (100), characterized in that: include: A sampling resistor (101) is connected to a main circuit (200) to be protected, wherein a parasitic inductance (102) of the sampling resistor (101) is capable of generating an induction signal based on a current in the main circuit (200); a clamping circuit (110), connected to both ends of the sampling resistor (101), and configured to clamp the voltage of the sensing signal to a first threshold voltage to provide a clamping signal; a first compensating rectifier circuit (120) and a second compensating rectifier circuit (130), wherein the first compensating rectifier circuit (120) is connected to the first output end of the clamping circuit (110), and the second compensating rectifier circuit (130) is connected to the second output end of the clamping circuit (110), and the first compensating rectifier circuit (120) and the second compensating rectifier circuit (130) are capable of performing power factor compensation and rectification on the clamping signal to convert the clamping signal into an intermediate signal having a predetermined waveform; as well as An output circuit (140) is connected to the first compensating rectifier circuit (120) and the second compensating rectifier circuit (130) to receive the intermediate signal and to generate an output signal when the voltage of the intermediate signal is greater than a second threshold voltage to indicate that a short circuit has occurred in the main loop (200), wherein the second threshold voltage is greater than the first threshold voltage.

2. The short-circuit protection circuit (100) according to claim 1, characterized in that: The clamping circuit (110) comprises: a first resistor (111), a first end of which is connected to the first end of the sampling resistor (101); a second resistor (112), a first end of which is connected to the second end of the sampling resistor (101); a first capacitor (113), one end of which is connected to the ground and the other end of which is connected to the second end of the first resistor (111); a second capacitor (114) having one end connected to ground and the other end connected to the second end of the second resistor (112); a third capacitor (115), one end of which is connected to a node between the first resistor (111) and the first capacitor (113) and the other end of which is connected to a node between the second resistor (112) and the second capacitor (114); a first diode (116) having an anode connected to a node between the first resistor (111) and the first capacitor (113) and a cathode connected to a node between the second resistor (112) and the second capacitor (114); and A second diode (117) has an anode connected to a node between the second resistor (112) and the first diode (116) and a cathode connected to a node between the first resistor (111) and the first diode (116).

3. The short-circuit protection circuit (100) according to claim 2, characterized in that: The first compensation rectifier circuit (120) comprises: a third resistor (121), a first end of which is connected to the cathode of the second diode (117); a fourth resistor (122), a first end of which is connected to the anode of the second diode (117); a first operational amplifier (123), a positive input terminal of which is connected to the second terminal of the third resistor (121) and a negative input terminal of which is connected to the second terminal of the fourth resistor (122); a fifth resistor (124) having a first end connected to a node between the first operational amplifier (123) and the third resistor (121) and a second end connected to ground; a fourth capacitor (125), wherein the fourth capacitor (125) and the fifth resistor (124) are connected in parallel; a third diode (126) having an anode connected to a node between the first operational amplifier (123) and the fourth resistor (122) and a cathode connected to an output terminal of the first operational amplifier (123); a fourth diode (127) having an anode connected to a node between the first operational amplifier (123) and the third diode (126); a sixth resistor (128) having a first end connected to a node between the fourth resistor (122) and the third diode (126) and a second end connected to a cathode of the fourth diode (127); and A fifth capacitor (129), wherein the fifth capacitor (129) and the sixth resistor (128) are connected in parallel.

4. The short-circuit protection circuit (100) according to claim 3, characterized in that: The first compensation rectifier circuit (120) further includes: a seventh resistor (1210), a first end of which is connected to a node between the fourth diode (127) and the sixth resistor (128); A sixth capacitor (1211) has one end connected to the second end of the seventh resistor (1210) and the other end connected to the ground.

5. The short-circuit protection circuit (100) according to claim 2, characterized in that: The second compensation rectifier circuit (130) comprises: an eighth resistor (131), a first end of which is connected to the anode of the second diode (117); a ninth resistor (132), a first end of which is connected to the cathode of the second diode (117); a second operational amplifier (133), a positive input terminal of which is connected to the second terminal of the eighth resistor (131) and a negative input terminal of which is connected to the second terminal of the ninth resistor (132); a tenth resistor (134), a first end of which is connected to a node between the second operational amplifier (133) and the eighth resistor (131) and a second end of which is connected to ground; a seventh capacitor (135), the seventh capacitor (135) and the tenth resistor (134) being connected in parallel; a fifth diode (136) having an anode connected to a node between the second operational amplifier (133) and the ninth resistor (132) and a cathode connected to an output terminal of the second operational amplifier (133); a sixth diode (137) having an anode connected to a node between the second operational amplifier (133) and the fifth diode (136); an eleventh resistor (138) having a first end connected to a node between the ninth resistor (132) and the fifth diode (136) and a second end connected to a cathode of the sixth diode (137); and An eighth capacitor (139), wherein the eighth capacitor (139) and the eleventh resistor (138) are connected in parallel.

6. The short-circuit protection circuit (100) according to claim 5, characterized in that: The second compensation rectifier circuit (130) further includes: a twelfth resistor (1310), a first end of which is connected to a node between the sixth diode (137) and the eleventh resistor (138); A ninth capacitor (1311) has one end connected to the second end of the twelfth resistor (1310) and the other end connected to the ground.

7. The short-circuit protection circuit (100) according to claim 1, characterized in that: The short-circuit protection circuit (100) further includes a power supply (150) for providing power input to the first compensating rectifier circuit (120), the second compensating rectifier circuit (130) and the output circuit (140).

8. The short-circuit protection circuit (100) according to claim 7, characterized in that: The output circuit (140) comprises: a thirteenth resistor (141), a first end of which is connected to the power source (150); a fourteenth resistor (142), a first end of which is connected to the second end of the thirteenth resistor (141) and a second end of which is connected to ground; a first comparison circuit (143) having a first input terminal connected to the first compensation rectifier circuit (120) and a second input terminal connected to a node between the thirteenth resistor (141) and the fourteenth resistor (142); and A second comparison circuit (144) has a first input terminal connected to the second compensation rectifier circuit (130) and a second input terminal connected to a node between the thirteenth resistor (141) and the fourteenth resistor (142).

9. The short-circuit protection circuit (100) according to claim 8, characterized in that: The first comparison circuit (143) comprises: a third operational amplifier (1431), a positive input terminal of which is connected to the first compensation rectifier circuit (120) and a negative input terminal of which is connected to a node between the thirteenth resistor (141) and the fourteenth resistor (142); a seventh diode (1432), an anode of which is connected to the output terminal of the third operational amplifier (1431); a fifteenth resistor (1433), a first end of which is connected to the cathode of the seventh diode (1432) and a second end of which is connected to a node between the third operational amplifier (1431) and the first compensation rectifier circuit (120); and An eighth diode (1434) has an anode connected to a node between the third operational amplifier (1431) and the seventh diode (1432).

10. The short-circuit protection circuit (100) according to claim 9, characterized in that: The second comparison circuit (144) comprises: a fourth operational amplifier (1441), a positive input terminal of which is connected to the second compensation rectifier circuit (130) and a negative input terminal of which is connected to a node between the thirteenth resistor (141) and the fourteenth resistor (142); a ninth diode (1442), the anode of which is connected to the output terminal of the fourth operational amplifier (1441); a sixteenth resistor (1443), a first end of which is connected to the cathode of the eighth diode (1442) and a second end of which is connected to a node between the fourth operational amplifier (1441) and the second compensation rectifier circuit (130); and A tenth diode (1444) has its anode connected to the node between the fourth operational amplifier (1441) and the ninth diode (1442) and its cathode connected to the cathode of the eighth diode (1434).

11. The short-circuit protection circuit (100) according to claim 10, characterized in that: The output circuit (140) further includes a seventeenth resistor (145) having a first end connected to a node between the eighth diode (1434) and the tenth diode (1444) and a second end connected to ground.

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