Capacitor surge current suppression circuit and method suitable for input voltage abrupt change

Abstract

The invention provides a capacitor surge current suppression circuit and method suitable for input voltage abrupt change, the circuit comprises an energy storage capacitor, a variable resistance circuit, a load and a power supply, the variable resistance circuit and the energy storage capacitor are connected as a whole, and then the variable resistance circuit and the load are connected to the power supply in parallel; a detection resistor is introduced into the variable resistance circuit to construct a threshold triggering mechanism, and when the surge current exceeds a set threshold, the impedance of the variable resistance circuit is dynamically adjusted to effectively suppress the surge current of the capacitor. The circuit is simple, the cost is low, the surge current can be restrained when equipment is powered on for the first time, the high-resistance state can be automatically switched when the input voltage changes suddenly at will, the surge current possibly generated in the follow-up process is continuously restrained, the protection range is remarkably widened, and the reliability and safety of a system under the complex working conditions such as voltage fluctuation are improved.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a capacitor surge current suppression circuit and method suitable for sudden input voltage changes. Background Technology

[0002] When a DC power supply load has a large pulsating power, a large-capacity capacitor is often connected in parallel at the load power supply end to store energy, suppress the disturbance of periodic power fluctuations at the load end to the power supply end, smooth out the pulse power, and achieve the purpose of reducing generator oscillation and improving stability. However, the parallel connection of a large-capacity capacitor will generate inrush current due to the jump in input voltage. That is, when the power supply directly charges the capacitor, the inrush current phenomenon generated due to the capacitor impedance changing from small to large. The generation of inrush current can impact the generator, reduce the reliability and lifespan of the components, and in severe cases, may cause overpower protection.

[0003] The upward surge in input voltage can be categorized into two scenarios: the voltage surge during power-on and the voltage surge during steady-state operation. Traditional solutions primarily address the capacitor inrush current phenomenon caused by the voltage surge during power-on. These solutions construct a surge suppression circuit by connecting a variable resistor in series with the negative terminal of the energy storage capacitor, using a high-resistance current-limiting resistor to reduce the inrush current during startup. While current solutions effectively suppress the inrush current generated by the voltage surge during power-on, under steady-state conditions, because the variable resistor circuit operates at low impedance, a sudden change in input voltage can still result in a significant inrush current generated by the energy storage capacitor. Therefore, existing technologies have significant limitations when addressing the need for capacitor inrush current suppression under various operating conditions. Summary of the Invention

[0004] This application provides a capacitor surge current suppression circuit and method suitable for sudden input voltage changes, which makes up for the shortcomings of the prior art in suppressing steady-state input surge current.

[0005] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0006] According to a first aspect of the embodiments of this application, a capacitor surge current suppression circuit suitable for sudden input voltage changes is provided, including an energy storage capacitor, a variable resistor circuit, a load, and a power supply. The variable resistor circuit and the energy storage capacitor are connected as a whole, and then connected in parallel with the load to the power supply. The variable resistor circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a detection resistor, a first capacitor, a first switching transistor, a second switching transistor, a first Zener diode, and a second Zener diode. The first terminal of the first resistor is connected to the positive terminal of the energy storage capacitor. The second terminal of the first resistor is connected to the first terminal of the second resistor, the negative terminal of the first Zener diode, the first terminal of the first capacitor, the first terminal of the third resistor, and the first terminal of the second switching transistor. The second terminal of the second resistor is connected to the second terminal of the fifth resistor, the second terminal of the second switching transistor, the positive terminal of the second Zener diode, the second terminal of the first capacitor, and the first terminal of the first switching transistor. The second terminal of the third resistor is connected to the control terminal of the first switching transistor. The second terminal of the first switching transistor is connected to the negative terminal of the energy storage capacitor via the detection resistor. The control terminal of the second switching transistor is connected to the positive terminal of the first Zener diode via the fourth resistor. The negative terminal of the first Zener diode is connected to the negative terminal of the energy storage capacitor. The first terminal of the fifth resistor is connected to the negative terminal of the energy storage capacitor. The second terminal of the fifth resistor and the positive terminal of the energy storage capacitor are respectively connected to the two terminals of the power supply.

[0007] In one embodiment of this application, the value of the detection resistor is designed based on the maximum surge current of the circuit and the breakdown voltage of the first Zener diode.

[0008] In one embodiment of this application, the first switch is a MOS transistor, and the first terminal, the second terminal, and the control terminal of the first switch are the source, the drain, and the gate, respectively.

[0009] In one embodiment of this application, the second switching transistor is a bipolar transistor, and the first terminal, the second terminal, and the control terminal of the second switching transistor are the collector, the emitter, and the base, respectively.

[0010] In one embodiment of this application, the resistance value of the detection resistor is less than that of the fifth resistor.

[0011] In one embodiment of this application, the resistance value of the detection resistor is 0.2Ω.

[0012] In one embodiment of this application, the energy storage capacitor has a capacity of 120μF. In one embodiment of this application, the breakdown voltage of the first Zener diode is 3V.

[0013] According to a second aspect of the embodiments of this application, a capacitor surge current suppression method suitable for sudden input voltage changes is provided, implemented based on the capacitor surge current suppression circuit suitable for sudden input voltage changes described in the first aspect, specifically including: When the power supply is powered on, the energy storage capacitor is in a short-circuit state, the voltage across the fifth resistor is equal to the input voltage, the first Zener diode is broken down, and the second switch is driven to turn on, thereby turning off the first switch. As the energy storage capacitor continues to charge, the voltage across the fifth resistor gradually decreases to below the breakdown voltage of the first Zener diode, the second switch is turned off, the power supply charges the first capacitor, thereby turning on the first switch, the fifth resistor is short-circuited, and the energy storage capacitor is connected to the power supply through the detection resistor and the turned-on first switch. During steady-state operation, if the input voltage changes abruptly, a surge current will be generated on the energy storage capacitor. When the surge current rises to the threshold, the voltage across the detection resistor is greater than the breakdown voltage of the first Zener diode, and the first Zener diode breaks down again. The circuit then enters the operating state when the power supply is powered on, and the surge current is suppressed again.

[0014] Compared with existing technologies, the beneficial effects of adopting the above technical solution are as follows: The present invention proposes a capacitor surge current suppression current applicable to sudden input voltage changes. It constructs a threshold triggering mechanism through a detection resistor. When the surge current exceeds a set threshold, the capacitor surge current is effectively suppressed by dynamically adjusting the impedance of the variable resistor circuit. The circuit of the present invention is simple and low-cost. It can not only suppress surge current when the device is initially powered on, but also automatically switch to a high-impedance state when the input voltage changes arbitrarily, continuously suppressing subsequent surge currents that may occur. This significantly broadens the protection range and improves the reliability and safety of the system under complex operating conditions such as voltage fluctuations. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0016] Figure 1 This is a capacitor surge current suppression circuit for input voltage sudden changes, as described in an embodiment of this application.

[0017] Figure 2 The simulation waveform diagram is for the existing scheme.

[0018] Figure 3 This is a simulation waveform diagram of this application. Detailed Implementation

[0019] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar modules or modules having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, the embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0020] To address the problem that existing solutions cannot suppress steady-state input surge current, this application proposes a capacitor surge current suppression circuit suitable for sudden input voltage changes. By adding a low-resistance resistor, capacitor surge current can be suppressed under any sudden input voltage change condition, effectively making up for the shortcomings of existing technologies in suppressing steady-state input surge current.

[0021] Please refer to Figure 1 The capacitor surge current suppression circuit for input voltage surges mainly includes an energy storage capacitor, a variable resistor circuit, a load, and a power supply. The variable resistor circuit and the energy storage capacitor are connected as a whole, and then connected in parallel with the load to the power supply.

[0022] Please continue to refer to Figure 1 The variable resistor circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a detection resistor R6, a first capacitor C1, a first switching transistor Q1, a second switching transistor Q2, a first Zener diode D1, and a second Zener diode D2. The first terminal of the first resistor R1 is connected to the positive terminal of the energy storage capacitor. The second terminal of the first resistor R1 is connected to the first terminal of the second resistor R2, the negative terminal of the first Zener diode D1, the first terminal of the first capacitor C1, the first terminal of the third resistor R3, and the first terminal of the second switching transistor Q2. The second terminal of the second resistor R2 is connected to the second terminal of the fifth resistor R5. The second terminal of the second switching transistor Q2, the positive terminal of the second Zener diode D2, the second terminal of the first capacitor C1, and the first terminal of the first switching transistor Q1 are connected together. The second terminal of the third resistor R3 is connected to the control terminal of the first switching transistor Q1. The second terminal of the first switching transistor Q1 is connected to the negative terminal of the energy storage capacitor via the detection resistor R6. The control terminal of the second switching transistor Q2 is connected to the positive terminal of the first Zener diode D1 via the fourth resistor R4. The negative terminal of the first Zener diode D1 is connected to the negative terminal of the energy storage capacitor. The first terminal of the fifth resistor R5 is connected to the negative terminal of the energy storage capacitor. The second terminal of the fifth resistor R5 and the positive terminal of the energy storage capacitor are respectively connected to the two terminals of the power supply.

[0023] In this embodiment, a detection resistor R6 is introduced to detect changes in capacitor surge current. In response to sudden changes in input voltage during steady-state operation, when the surge current exceeds the set value, the variable resistor circuit can be adjusted to a high resistance state to effectively suppress the rise of surge current.

[0024] It should be noted that in this embodiment, the value of the sensing resistor R6 is designed based on the maximum surge current of the circuit and the breakdown voltage of the first Zener diode. Generally, the value of the sensing resistor R6 is smaller than that of the fifth resistor R5. Assuming the breakdown voltage of the first Zener diode D1 is 3V, the sensing resistor R6 is designed to be 0.2Ω. When the surge current rises to the set value of 15A, the voltage across the sensing resistor R6 rises to 15 × 0.2 = 3V, causing the first Zener diode D1 to break down. Consequently, the second switch Q2 turns on and the first switch Q1 turns off, causing the variable resistor circuit to switch to a high-resistance state. Current flows through the high-resistance fifth resistor R5. After this, the fifth resistor R5 is responsible for the breakdown voltage of the first Zener diode D1, and the sensing resistor R6 no longer participates.

[0025] It should be noted that the first switch Q1 and the second switch Q2 are controllable electronic switching devices, and any suitable semiconductor switching device can be selected, such as a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), or a junction field effect transistor (JFET). In this specification, the first switch Q1 is implemented using a MOSFET, and the second switch Q2 is implemented using a gate transistor.

[0026] In one embodiment, when the first switching transistor Q1 is a MOSFET, its first terminal, second terminal, and control terminal are the source, drain, and gate, respectively. The source of the first switching transistor Q1 is connected to the second terminal of the second resistor R2, the drain of the first switching transistor Q1 is connected to the negative terminal of the energy storage capacitor, and the gate of the first switching transistor Q1 is connected to the second terminal of the third resistor R3.

[0027] In one embodiment, when the second switching transistor Q2 is a bipolar transistor, its first terminal, second terminal, and control terminal are the collector, emitter, and base, respectively. The collector of the second switching transistor Q2 is connected to the second terminal of the first resistor R1, the emitter of the second switching transistor Q2 is connected to the second terminal of the second resistor R2, and the base of the second switching transistor Q2 is connected to the fourth resistor R4.

[0028] To more clearly illustrate the process of the circuit proposed in this embodiment suppressing surge current, the following will be combined with... Figure 1 The working process is explained in detail.

[0029] When the power supply is powered on, the energy storage capacitor is in a short-circuit state, and the voltage across the fifth resistor R5 is equal to the input voltage. This causes the first Zener diode D1 to break down, driving the second switch Q2 to conduct, which in turn shorts the gate and source of the first switch Q1, turning it off. At this time, the power supply charges the capacitor through the fifth resistor R5, effectively suppressing inrush current. As the charging process proceeds, the voltage across the energy storage capacitor continuously rises, and the voltage across the fifth resistor R5 gradually decreases to below the breakdown voltage of the first Zener diode D1. At this point, the second switch Q2 enters the off state due to base drive failure. The power supply charges the first capacitor C1 through the first resistor R1, raising the gate potential of the first switch Q1, causing the first switch Q1 to slowly conduct, thus shorting the fifth resistor R5. Subsequently, the energy storage capacitor is connected to the power supply through the sensing resistor R6 and the conducting first switch Q1.

[0030] During steady-state operation, a sharp jump in input voltage will cause a certain inrush current on the energy storage capacitor. However, when the inrush current rises to a certain level, the voltage across the sensing resistor R6 exceeds the breakdown voltage of the first Zener diode D1, causing D1 to break down again. The subsequent circuit state is consistent with the power supply power-on process. The energy storage capacitor is charged through the fifth resistor R5, suppressing the inrush current. When charging is nearly complete, the first switching transistor Q1 turns on, and the energy storage capacitor is connected to the power supply through a low-resistance circuit.

[0031] Based on the principle of the capacitor surge current suppression circuit in this embodiment, simulation tests were conducted. The energy storage capacitor was set to 120μF, the sensing resistor R6 = 0.2Ω, and the breakdown voltage of the Zener diode D1 was 3V. Upon power-up, the input voltage jumped from 0V to 270V. After entering steady-state operation, the input voltage jumped from 270V to 400V in 0.5 seconds. Figure 2 , Figure 3 The simulation waveforms of the existing solution and the present application are shown respectively. According to the waveforms, when the input voltage jumps from 0V to 270V, both the existing technology and the present invention can effectively suppress the capacitor surge current, and only generate a weak surge current when the capacitor voltage is about to be fully charged.

[0032] After entering steady-state operation, when the input voltage jumps from 270V to 400V at 0.5s, existing technologies, due to their inherent limitations, cannot suppress the capacitor surge current, with a peak surge current of 123.1A. This application, however, constructs a threshold triggering mechanism using a sensing resistor R6. When the surge current exceeds a set value of 15A, the variable resistor circuit switches to a high-resistance state. Figure 3 Simulated waveforms show that the peak surge current is 18.6A, which is basically consistent with the set value and is 85% lower than the existing technology.

[0033] Therefore, it can be seen that the present invention has a good suppression effect on capacitor surge current caused by sudden changes in input voltage.

[0034] It should be noted that, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances. The accompanying drawings in the embodiments are used to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A capacitor surge current suppression circuit suitable for sudden input voltage changes, characterized in that, It includes an energy storage capacitor, a variable resistor circuit, a load, and a power supply. The variable resistor circuit is connected to the energy storage capacitor as a whole, and then connected in parallel with the load to the power supply. The variable resistor circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a detection resistor, a first capacitor, a first switching transistor, a second switching transistor, a first Zener diode, and a second Zener diode. The first terminal of the first resistor is connected to the positive terminal of the energy storage capacitor. The second terminal of the first resistor is connected to the first terminal of the second resistor, the negative terminal of the first Zener diode, the first terminal of the first capacitor, the first terminal of the third resistor, and the first terminal of the second switching transistor. The second terminal of the second resistor is connected to the second terminal of the fifth resistor, the second terminal of the second switching transistor, the positive terminal of the second Zener diode, the second terminal of the first capacitor, and the first terminal of the first switching transistor. The second terminal of the third resistor is connected to the control terminal of the first switching transistor. The second terminal of the first switching transistor is connected to the negative terminal of the energy storage capacitor via the detection resistor. The control terminal of the second switching transistor is connected to the positive terminal of the first Zener diode via the fourth resistor. The negative terminal of the first Zener diode is connected to the negative terminal of the energy storage capacitor. The first terminal of the fifth resistor is connected to the negative terminal of the energy storage capacitor. The second terminal of the fifth resistor and the positive terminal of the energy storage capacitor are respectively connected to the two terminals of the power supply.

2. The capacitor surge current suppression circuit suitable for sudden input voltage changes according to claim 1, characterized in that, The value of the detection resistor is designed based on the maximum surge current of the circuit and the breakdown voltage of the first Zener diode.

3. The capacitor surge current suppression circuit suitable for sudden input voltage changes according to claim 1, characterized in that, The first switching transistor is a MOSFET, and the first terminal, the second terminal, and the control terminal of the first switching transistor are the source, the drain, and the gate, respectively.

4. The capacitor surge current suppression circuit suitable for sudden input voltage changes according to claim 1, characterized in that, The second switching transistor is a bipolar transistor, and its first terminal, second terminal, and control terminal are the collector, emitter, and base, respectively.

5. The capacitor surge current suppression circuit suitable for sudden input voltage changes according to claim 1, characterized in that, The resistance value of the detection resistor is less than that of the fifth resistor.

6. The capacitor surge current suppression circuit suitable for sudden input voltage changes according to claim 1, characterized in that, The resistance of the detection resistor is 0.2Ω.

7. The capacitor surge current suppression circuit suitable for sudden input voltage changes according to claim 1, characterized in that, The energy storage capacitor has a capacity of 120μF.

8. The capacitor surge current suppression circuit suitable for sudden input voltage changes according to claim 1, characterized in that, The breakdown voltage of the first Zener diode is 3V.

9. A method for suppressing capacitor surge currents suitable for sudden changes in input voltage, characterized in that, Based on the capacitor surge current suppression circuit for input voltage sudden changes as described in any one of claims 1 to 8, specifically including: When the power supply is powered on, the energy storage capacitor is in a short-circuit state, the voltage across the fifth resistor is equal to the input voltage, the first Zener diode is broken down, and the second switch is driven to turn on, thereby turning off the first switch. As the energy storage capacitor continues to charge, the voltage across the fifth resistor gradually decreases to below the breakdown voltage of the first Zener diode, the second switch is turned off, the power supply charges the first capacitor, thereby turning on the first switch, the fifth resistor is short-circuited, and the energy storage capacitor is connected to the power supply through the detection resistor and the turned-on first switch. During steady-state operation, if the input voltage changes abruptly, a surge current will be generated on the energy storage capacitor. When the surge current rises to the threshold, the voltage across the detection resistor is greater than the breakdown voltage of the first Zener diode, and the first Zener diode breaks down again. The circuit then enters the operating state when the power supply is powered on, and the surge current is suppressed again.

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