Solid-state circuit breaker

Abstract

The solid-state circuit breaker comprises a first switch, a second switch, a first capacitor and a first diode, the first end of the first switch is connected to the positive electrode of an input end, the second end of the first switch is connected to the first end of the second switch, the second end of the second switch is connected to the positive electrode of an output end, and the first capacitor is connected to the first diode. The first end of the first capacitor is connected with the first end of the second switch, the second end of the first capacitor is connected to the negative electrode of the input end, the cathode of the first diode is connected with the second end of the second switch, and the anode of the first diode is connected with the negative electrode of the output end.

Description

Technical Field

[0001] The present disclosure relates to a device for bidirectional direct current solid-state short-circuit protection, and more particularly, to a solid-state circuit breaker suitable for direct current systems and used for bidirectional short-circuit protection. Background Art

[0002] With the development of power electronics technology, solid-state circuit breakers are increasingly used in power systems. However, short-circuit faults in DC systems pose a serious threat to the safety of equipment and personnel, and have a serious impact on the stable operation of the power system, requiring the distribution system branch protection switches to respond and cut off the faulty branches at a time scale of microseconds (us). However, in traditional solid-state circuit breakers, the upstream current is large at the moment of short circuit, making it difficult to achieve selectivity. In addition, in traditional solid-state circuit breakers, after the main circuit switch device is disconnected, the line inductance energy has no freewheeling circuit, and the superposition of the induced voltage and the input voltage often causes overstress of the main circuit switch device. Therefore, the existing technology still needs to be improved and enhanced. Utility Model Content

[0003] In view of the shortcomings of the above-mentioned prior art, the present disclosure relates to a device for bidirectional DC solid-state short-circuit protection, so as to provide a solid-state circuit breaker for bidirectional short-circuit protection for a DC system with fast response speed and high reliability, so as to protect the circuit from overload and short-circuit faults and ensure the safe operation of the circuit.

[0004] According to an embodiment of the utility model, a solid-state circuit breaker is provided, which includes a first switch, a second switch, a first capacitor, and a first diode, wherein the first end of the first switch is connected to the positive pole of the input terminal, the second end of the first switch is connected to the first end of the second switch, the second end of the second switch is connected to the positive pole of the output terminal, the first end of the first capacitor is connected to the first end of the second switch, the second end of the first capacitor is connected to the negative pole of the input terminal, the cathode of the first diode is connected to the second end of the second switch, and the anode of the first diode is connected to the negative pole of the output terminal.

[0005] According to an embodiment of the utility model, the solid-state circuit breaker further includes a transient voltage suppressor (TVS) and a second diode, wherein the transient voltage suppressor is connected in parallel with the first capacitor, the second diode is connected in parallel with the second switch and the cathode of the second diode is connected to the first end of the second switch, and the anode of the second diode is connected to the second end of the second switch.

[0006] According to an embodiment of the utility model, the solid-state circuit breaker further comprises a first overcurrent protection device and a second overcurrent protection device, wherein the first overcurrent protection device is connected in series with the first capacitor, and the second overcurrent protection device is connected in series with the first diode.

[0007] According to an embodiment of the utility model, the solid-state circuit breaker also includes a first inductor and a second inductor, wherein the first inductor is connected in series between the positive pole of the input terminal and a node where the first end of the second switch is connected to the first end of the first capacitor, and the second inductor is connected in series between a node where the second end of the second switch is connected to the first end of the first inductor and the positive pole of the output terminal.

[0008] According to an embodiment of the utility model, a solid-state circuit breaker is provided, which adopts power electronic devices as solid-state circuit breaker devices, and quickly disconnects the main circuit within microseconds when the main circuit is overloaded or short-circuited; at the moment of short-circuit, the internal capacitor of the circuit breaker discharges to the short-circuited load to provide short-circuit energy, thereby ensuring that the upstream main circuit current changes in a small range or remains basically unchanged at the moment of output short-circuit, which is conducive to selective protection; and the circuit breaker has a built-in freewheeling circuit. After the main switch device is disconnected, the circuit is disconnected at this time, and the line inductance energy can be absorbed by the load or by the internal capacitor of the circuit breaker, which is conducive to reducing the stress of the main switch device and extending the life of the device, thereby reducing losses; in addition, the combination of the main switch device and the intelligent mechanical switch is conducive to cost saving; and such a circuit breaker design can realize bidirectional short-circuit protection suitable for DC systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The aspects, features and advantages of the present disclosure will become clearer and easier to understand through the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0010] Figure 1 A circuit structure schematic diagram of a solid-state circuit breaker according to the utility model is shown;

[0011] Figure 2 A schematic diagram showing the circuit structure of the protection logic for output side short circuit of the solid-state circuit breaker according to the utility model; and

[0012] Figure 3 A schematic diagram of the circuit structure of the protection logic for input side short circuit of the solid-state circuit breaker according to the utility model is shown. DETAILED DESCRIPTION

[0013] The present invention will be described in detail below with reference to exemplary embodiments of the present invention. However, the present invention is not limited to the embodiments described herein, and can be implemented in many different forms. The described embodiments are only intended to make the present disclosure thorough and complete, and to fully convey the concept of the present invention to those skilled in the art. The features of the various embodiments described can be combined or replaced with each other, unless explicitly excluded or should be excluded according to the context.

[0014] In the embodiments of the present invention, unless otherwise explicitly stated, "connected" or "connected" does not mean "directly connected" or "directly in contact", but only requires electrical connection. In addition, "first", "second", etc. or similar expressions in this article are only used for description and distinction purposes, and do not indicate any priority or ranking, and cannot be understood as indicating or implying the relative importance of the corresponding components, nor do they represent whether the parameter values ​​described are the same or different.

[0015] Figure 1 A circuit structure schematic diagram of a solid-state circuit breaker according to the utility model is shown.

[0016] like Figure 1 As shown, the solid-state circuit breaker includes an intelligent mechanical switch S1, a main switch device Q1, a power inductor L1, a power inductor L2, a transient voltage suppressor TVS, a capacitor C1, a diode D1, a diode D2, a fuse Fuse1, and a fuse Fuse2, and wherein P1 and N1 are DC input terminals, which are respectively an input positive electrode and an input negative electrode, and P2 and N2 are DC output terminals, which are respectively an output positive electrode and an output negative electrode, and the output terminals P2 and N2 can be connected to loads (such as EMC circuits, X capacitors, Y capacitors, etc.).

[0017] According to the embodiment of the utility model, as shown in the figure, the intelligent mechanical switch S1 is connected in series to the positive electrode of the input side, and can be opened and closed manually or automatically by disconnecting the main circuit contact through an electric control command. The intelligent mechanical switch S1 is an electrical device with a certain overcurrent capability; the power inductor L1 and the power inductor L2 are respectively connected in series with the positive electrode of the input side and the positive electrode of the output side to limit the current rise (such as the instantaneous current of the main circuit); the main switch device Q1 is connected in series between the positive input and the power inductor L1 as a circuit breaker protection device, Figure 1The main switch device Q1 shown in the figure is implemented by an additional anti-parallel diode such as a metal oxide semiconductor field effect transistor (MOSFET). This is because the parasitic anti-parallel diode of the MOSFET has a very weak overcurrent capacity. An additional anti-parallel diode is required under input short circuit conditions and output surge voltage conditions to ensure that the instantaneous current can be reversely charged to the capacitor C1 or the transient voltage suppressor TVS, otherwise the instantaneous large current will burn out the parasitic anti-parallel diode of the MOSFET. Optionally, the main switch device Q1 can also be a power electronic switch device such as an insulated gate bipolar transistor (IGBT); capacitor C1, series Between the positive and negative electrodes, specifically, connected in series between the drain of the main switch device Q1 and the negative input electrode. According to an embodiment of the present invention, at the moment when the capacitor C1 is short-circuited on the output side (i.e., short-circuited between P2 and N2), the capacitor C1 quickly discharges to provide a short-circuit current, which is conducive to the realization of selective protection. At the same time, after the main switch device Q1 reaches the tripping threshold and is turned off, the energy of the upper cable (i.e., the energy on the input side) can flow to the capacitor C1; the diode D1 is connected in series between the positive and negative electrodes of the output port. Specifically, the cathode of the diode D1 is connected to the source of the main switch device Q1, and the anode of the diode D1 is connected to the N line. According to the embodiment of the present invention, For example, when the output side is short-circuited (i.e., short-circuited between P2 and N2) and the main switch device Q1 reaches the tripping threshold and is turned off, the diode D1 provides a freewheeling circuit for the inductive energy of the downstream cable (i.e., the output side energy), that is, the inductive energy of the downstream line can be freewheeled to the load through the diode D1, and optionally, the diode D1 can also be replaced by a thyristor (SCR), and the output positive and negative reverse connection protection and the short-circuit fault to the ground under specific working conditions can be realized; the transient voltage suppressor TVS is connected in parallel at both ends of the capacitor C1 to protect the main switch device Q1 and other power electronic devices from damage by excessive voltage. When the circuit When an overvoltage or spike voltage occurs in the circuit, the transient voltage suppressor TVS can respond quickly and clamp the voltage at a safe level, thereby protecting the related electronic devices from damage. According to the embodiment of the utility model, the transient voltage suppressor TVS can prevent the capacitor C1 voltage from being too high when the input side surges. The transient voltage suppressor TVS can also protect the main switch device Q1, such as preventing the voltage borne by the main switch device Q1 from exceeding its maximum operating voltage. In order to achieve more effective protection, the selection of the transient voltage suppressor TVS model can be selected according to the maximum operating voltage and current of the power electronic device to be protected. According to the embodiment of the utility model, an overcurrent protection device (such as fuse Fuse1 and fuse Fuse2) is arranged, wherein the fuse Fuse1 is connected in series with the capacitor C1, which can be used to prevent the input from being continuously short-circuited due to the failure of TVS or C1, and the fuse Fuse2 is connected in series with the diode D1 to prevent the current from being overcurrent caused by the reverse connection of the output.

[0018] Optionally, the diode D2 is connected in parallel with the main switch device Q1 to prevent the main switch device Q1 from having insufficient overcurrent capacity, especially insufficient instantaneous overcurrent capacity under surge conditions.

[0019] like Figure 1 In the circuit of the solid-state circuit breaker shown, when the circuit operates normally, power is supplied normally between P1 and N1 on the input side, switches S1 and Q1 are closed in sequence, and the load operates normally.

[0020] Figure 2 The figure shows a circuit structure diagram of the protection logic of the output side short circuit of the solid-state circuit breaker according to the utility model. Figure 2 The circuit diagram (a) in FIG. 1 shows the situation when a short circuit occurs between P2 and N2 on the output side and the main switch device Q1 is not disconnected at the moment of the short circuit. Figure 2 The circuit schematic diagram (b) in FIG. 1 shows a situation in which a short circuit occurs between P2 and N2 on the output side and the main switch device Q1 is disconnected immediately after the short circuit.

[0021] According to the embodiment of the utility model, when a short circuit occurs between the output side P2 and N2, the main switch device Q1 has not been disconnected at the moment of the short circuit. At this time, the intelligent mechanical switch S1 is in a closed state, the output side voltage drops instantly, and the capacitor C1 is Figure 2 The dotted arrow in the circuit schematic (a) shows that the path through Fuse1, main switch device Q1, and inductor L2 discharges to the output side, and the output current increases sharply. At this time, the current flowing through the main switch device Q1 also increases sharply. The voltage across the main switch device Q1 decreases after the capacitor C1 discharges, while the input side current remains basically unchanged. In other words, when the output side is short-circuited, the upstream (input side) current will not increase due to the downstream short circuit (output side short circuit) and cause the upstream protection device to trip. According to the embodiment of the utility model, it is ensured that the upstream main current changes in the range of a small or basically unchanged at the moment of output short circuit, so that only the faulty part is disconnected without affecting the operation of other normal parts, reducing the fault range and facilitating selective protection.

[0022] According to the embodiment of the present utility model, continue to refer to Figure 2 The circuit diagram (a) in FIG. 1 is provided with a test point at the main switch device Q1. When the output current is detected to increase to the tripping threshold of the main switch device Q1, as shown in FIG. Figure 2 As shown in the circuit diagram (b), the main switch device Q1 is turned off ( Figure 2 The “X” in the figure shows that the main switch device Q1 is disconnected at this time), but the intelligent mechanical switch S1 remains closed at this time, and the downstream inductor and cable energy are as follows Figure 2 As shown in the circuit schematic diagram (b), the dotted arrow in FIG. 1 forms a freewheeling loop through the diode D1, Fuse2, inductor L2, and load (not shown); the upstream inductor and cable energy are as shown in FIG. Figure 2 The dashed arrow in the circuit diagram (b) in FIG. 1 forms a freewheeling loop through the inductor L1, Fuse1, and inductor C1. According to the embodiment of the utility model, at the moment of short circuit on the output side, after the main switch device Q1 is turned off, the overstress problem of the main circuit switch device formed by the superposition of the induced voltage and the input voltage can be avoided through such two freewheeling loops, thereby extending the life of the device and reducing the loss.

[0023] Figure 3 A schematic diagram of the circuit structure of the protection logic for input side short circuit of the solid-state circuit breaker according to the utility model is shown.

[0024] According to the embodiment of the utility model, when a short circuit occurs between the input sides P1 and N1, the energy on the output side (i.e., the load) will be instantly fed back to the short-circuit point on the input side. However, since the main switch device Q1 is a unidirectional switch, if a switch device Q2 connected in parallel with the main switch device Q1 is provided to realize the function of a bidirectional switch, this will increase the cost. Moreover, the load energy is usually relatively small, so a microsecond-level shut-off speed is usually not required. The method of controlling the intelligent mechanical switch S1 to cooperate with the main switch device Q1 through an electronic control command can achieve bidirectional (input side, output side) circuit short-circuit protection while reducing costs, thereby improving reliability and stability.

[0025] According to an embodiment of the utility model, optionally, a detection point is set at the intelligent mechanical switch S1, and when a short circuit occurs between the input sides P1 and N1, the intelligent mechanical switch S1 is disconnected by an electric control command ( Figure 2 The "X" in the figure indicates that the intelligent mechanical switch S1 is disconnected at this time). After the intelligent mechanical switch S1 is disconnected, the residual energy on the output side is as follows: Figure 3 The loop formed by the inductor L2, the main switch device Q1, and the inductor C1 as shown by the dotted arrow shown in the figure is continuously flowing, and optionally, the loop formed by the inductor L2, the main switch device Q1, the main switch device Q1 or the diode D2 and the inductor C1 is continuously flowing, thereby reducing the impact on the output side.

[0026] It should be noted that, for the sake of clarity and conciseness, only the parts related to the embodiments of the present utility model are shown in the drawings, but those skilled in the art should understand that the devices or components shown in the drawings may include other necessary units.

[0027] The block diagrams of circuits, devices, apparatuses, equipment, and systems involved in the present utility model are only illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these circuits, devices, apparatuses, equipment, and systems may be connected, arranged, and configured in any manner as long as the desired purpose can be achieved. The numbers involved in the present utility model are merely illustrative.

[0028] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0029] Those skilled in the art should understand that the above-mentioned specific embodiments are merely examples and not limitations, and various modifications, combinations, partial combinations and replacements may be made to the embodiments of the present disclosure according to design requirements and other factors. As long as they are within the scope of the attached claims or their equivalents, they belong to the scope of rights to be protected by the present disclosure.

Claims

1. A solid-state circuit breaker, characterized in that: comprising a first switch, a second switch, a first capacitor, and a first diode, The first end of the first switch is connected to the positive electrode of the input terminal, the second end of the first switch is connected to the first end of the second switch, the second end of the second switch is connected to the positive electrode of the output terminal, the first end of the first capacitor is connected to the first end of the second switch, the second end of the first capacitor is connected to the negative electrode of the input terminal, the cathode of the first diode is connected to the second end of the second switch, and the anode of the first diode is connected to the negative electrode of the output terminal.

2. The solid-state circuit breaker according to claim 1, characterized in that: Also included is a transient voltage suppressor and a second diode, The transient voltage suppressor is connected in parallel with the first capacitor, the second diode is connected in parallel with the second switch, the cathode of the second diode is connected to the first end of the second switch, and the anode of the second diode is connected to the second end of the second switch.

3. The solid-state circuit breaker according to claim 2, characterized in that: Also includes a first overcurrent protection device and a second overcurrent protection device, The first overcurrent protection device is connected in series with the first capacitor, and the second overcurrent protection device is connected in series with the first diode.

4. The solid-state circuit breaker according to claim 3, characterized in that: Also includes a first inductor and a second inductor, The first inductor is connected in series between the positive electrode of the input terminal and a node where the first end of the second switch and the first end of the first capacitor are connected, and the second inductor is connected in series between a node where the second end of the second switch and the first end of the first inductor are connected and the positive electrode of the output terminal.

5. The solid-state circuit breaker according to claim 1, characterized in that: The first switch is an intelligent mechanical switch, which is configured to disconnect the main circuit contact through an electric control command and has a current breaking capability. The second switch is a metal oxide semiconductor field effect transistor MOSFET anti-parallel diode or an insulated gate bipolar transistor IGBT.

6. The solid-state circuit breaker according to claim 1, characterized in that: The first diode can also be replaced by a thyristor.

7. The solid-state circuit breaker according to claim 3, characterized in that: The first overcurrent protection device and the second overcurrent protection device are fuses.

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