A Hybrid DC Solid-State Circuit Breaker

Abstract

The present invention discloses a hybrid DC solid-state circuit breaker. A branch formed by connecting the contacts of a mechanical switch K2 in series with a power electronic device Q1 is connected in parallel with the contacts of a main load-bearing mechanical switch K1. When the contacts of the mechanical switch K1 are switched on and off, the current flows through the parallel branch, and there is no arc during the on / off operation of the contacts of the mechanical switch K1, realizing arc-free on / off of the circuit breaker. The power supply end and the load end are separated by the contacts of the mechanical switch K1, the mechanical switch K2, and the mechanical switch K3, realizing the high withstand voltage capacity of the circuit breaker. When the circuit breaker is conducting, the power supply current passes through the closed contacts of the mechanical switch K1, and the resistance of the closed contacts is very low. The heat generated when the current flows through the hybrid circuit breaker can achieve the heat dissipation purpose through natural cooling, without adding a special heat dissipation device to the power electronic device, realizing the ability to withstand large currents. By detecting the voltage and current at the power supply end of the circuit breaker, if a fault occurs, the circuit breaker can be quickly turned off.

Description

Technical Field

[0001] The present invention relates to the field of DC solid state circuit breakers, and more particularly, to a hybrid DC solid state circuit breaker. Background Art

[0002] With the continuous development of DC microgrids, their application scope has also been continuously expanded. Therefore, higher requirements have been put forward for the steady-state operation and safety protection of DC microgrids. Circuit breakers are an important device to ensure the steady-state operation of power systems, and DC circuit breakers also play an important role in DC power transmission protection, providing a strong guarantee for the reliable operation of DC systems.

[0003] Currently, DC circuit breakers are mainly divided into pure mechanical DC circuit breakers that use traditional mechanical switches for opening and closing and all-solid-state circuit breakers that use power electronic devices (SCR, IGBT) for opening and closing. Pure mechanical DC circuit breakers have advantages such as stable conduction and strong load-carrying capacity. However, with the improvement of users' requirements for power quality, its disadvantages have become more and more prominent. When disconnecting the load, an arc is often generated, resulting in easy burning of its contacts, and the opening time of mechanical circuit breakers is long, making it difficult to meet the quick-acting requirements for fault current interruption in some cases. All-solid-state circuit breakers use pure power electronic devices for operation and can interrupt faults in only dozens of microseconds, meeting the requirements of rapid response. However, the voltage and current withstand capabilities of power electronic devices are limited, and the on-state loss is also very large. How to integrate the advantages of pure mechanical and all-solid-state DC circuit breakers is a research hotspot in DC circuit breakers. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a hybrid DC solid state circuit breaker with fast opening, no arc, high voltage withstand, and high current withstand capabilities, including: mechanical switches K1, K2, K3, power electronic device Q1, and a control circuit; the control circuit controls the on and off of mechanical switches K1, K2, K3, and power electronic device Q1; the contacts of mechanical switch K2 are connected in series with power electronic device Q1 to form a branch, and are connected in parallel with the contacts of mechanical switch K1;

[0005] When the hybrid DC solid state circuit breaker needs to connect the load, the control circuit first controls the contacts of mechanical switch K2 and mechanical switch K3 to close, then controls power electronic device Q1 to conduct, and then controls the contacts of mechanical switch K1 to close. After the contacts of mechanical switch K1 are completely closed, it controls power electronic device Q1 to disconnect, completing the process of the hybrid DC solid state circuit breaker connecting the load;

[0006] When the hybrid DC solid-state circuit breaker needs to disconnect the load under load, the control circuit first controls the power electronic device Q1 to conduct, and then disconnects the contacts of the mechanical switch K1. At this time, the current flows through the parallel branch, and the contacts of the mechanical switch K1 are disconnected without arc. After the contacts of the mechanical switch K1 are completely disconnected, then control the power electronic device Q1 to disconnect. At this time, the current in the circuit is interrupted, and the generated overvoltage is absorbed by the surge protection module. Finally, control the contacts of the mechanical switch K2 and the mechanical switch K3 to disconnect, completing the process of the hybrid circuit breaker disconnecting the load.

[0007] Optionally, a freewheeling diode is connected in parallel at the load end of the hybrid DC solid-state circuit breaker to provide a freewheeling path for the inductive load when the hybrid DC solid-state circuit breaker is disconnected.

[0008] Optionally, the power electronic device Q1 is a thyristor, MOS transistor, IGBT or SiC device.

[0009] Optionally, the surge protection module is a varistor.

[0010] Optionally, the surge protection module is a transient suppression diode.

[0011] Optionally, the surge protection module is a series connection of a discharge tube and a varistor voltage.

[0012] Optionally, the hybrid DC solid-state circuit breaker further includes a voltage detection module. The voltage detection module is connected in parallel at the power supply end of the circuit breaker, detects the input voltage by a series connection of multiple resistors and a Hall voltage transformer, and performs overvoltage and undervoltage protection on the hybrid DC solid-state circuit breaker through the control circuit.

[0013] Optionally, the hybrid DC solid-state circuit breaker further includes a current detection module, which is connected in series at the rear end of the line where the branch formed by the series connection of the contacts of the mechanical switch K2 and the power electronic device Q1 is connected in parallel with the contacts of the main load-bearing mechanical switch K1. The current flowing through the circuit breaker is detected by a Hall current transformer, and overcurrent protection is performed on the hybrid DC solid-state circuit breaker through a control circuit. Thus, the hybrid DC solid-state circuit breaker proposed by the present invention combines the advantages of pure mechanical and pure solid-state DC circuit breakers. A branch formed by the series connection of the contacts of the mechanical switch K2 and the power electronic device Q1 is connected in parallel with the contacts of the main load-bearing mechanical switch K1. When the contacts of the mechanical switch K1 are switched on and off, the current flows through the parallel branch, and there is no arc when the contacts of the mechanical switch K1 are switched on and off, realizing arc-free switching of the circuit breaker; the power supply end and the load end are separated by the contacts of the mechanical switch K1, the mechanical switch K2, and the mechanical switch K3, realizing the high voltage withstand capacity of the circuit breaker; when the circuit breaker is conducting, the power supply current passes through the closed contacts of the mechanical switch K1, and the closed contact resistance is very low. The heat generated when the current flows through the hybrid circuit breaker can achieve the heat dissipation purpose through natural cooling, and there is no need to add a special heat dissipation device to the power electronic device, realizing the ability to withstand large currents; by detecting the voltage and current at the power supply end of the circuit breaker, if a fault occurs, the circuit breaker is quickly turned off. Brief Description of the Drawings

[0014] The exemplary embodiments of the present invention can be more fully understood by referring to the following drawings:

[0015] Figure 1 is a structural diagram of a hybrid DC solid-state circuit breaker provided by an exemplary embodiment of the present invention. Detailed Embodiments

[0016] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments of the present invention. It should be understood that the present invention is not limited by the exemplary embodiments described herein.

[0017] It should be noted that: unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0018] Figure 1 shows a structural diagram of the hybrid DC solid-state circuit breaker provided by the present invention. As Figure 1 shown, the hybrid DC solid-state circuit breaker includes: a mechanical switch K1, a mechanical switch K2, a mechanical switch K3, a power electronic device Q1, and a control circuit; the control circuit controls the on and off of the mechanical switch K1, the mechanical switch K2, the mechanical switch K3, and the power electronic device Q1; the contacts of the mechanical switch K2 and the power electronic device Q1 are connected in series to form a branch, and are connected in parallel with the contacts of the mechanical switch K1;

[0019] When the hybrid DC solid-state circuit breaker needs to connect the load, the control circuit first controls the contacts of mechanical switch K2 and mechanical switch K3 to close, then controls the power electronic device Q1 to conduct, and then controls the contacts of mechanical switch K1 to close. After the contacts of mechanical switch K1 are fully closed, the control circuit controls the power electronic device Q1 to disconnect, completing the process of the hybrid DC solid-state circuit breaker connecting the load;

[0020] When the hybrid DC solid-state circuit breaker needs to disconnect the load under load, the control circuit first controls the power electronic device Q1 to conduct, and then disconnects the contacts of mechanical switch K1. At this time, the current flows through the parallel branch, and the contacts of mechanical switch K1 are disconnected without arc. After the contacts of mechanical switch K1 are fully disconnected, the control circuit then controls the power electronic device Q1 to disconnect. At this time, the current in the circuit is interrupted, and the overvoltage generated is absorbed by the surge protection module. Finally, the control circuit controls the contacts of mechanical switch K2 and mechanical switch K3 to disconnect, completing the process of the hybrid circuit breaker disconnecting the load.

[0021] In the embodiment of the present invention, the contacts of mechanical switch K1 are connected to the power supply and the load. Since the contact resistance is very low, the heat generated when the current flows through the hybrid circuit breaker can achieve the heat dissipation purpose through natural cooling, and there is no need to add a special heat dissipation device to the power electronic device.

[0022] Optionally, a freewheeling diode is connected in parallel at the load end of the hybrid DC solid-state circuit breaker to provide a freewheeling path for the inductive load when the hybrid DC solid-state circuit breaker is disconnected.

[0023] Optionally, the power electronic device Q1 is a thyristor, MOS transistor, IGBT or SiC device.

[0024] Optionally, the surge protection module is a varistor.

[0025] Optionally, the surge protection module is a transient voltage suppressor diode.

[0026] Optionally, the surge protection module is a series connection of a discharge tube and a varistor voltage.

[0027] Optionally, the hybrid DC solid-state circuit breaker further includes a voltage detection module. The voltage detection module is connected in parallel at the power supply end of the circuit breaker, detects the input voltage by a series connection of multiple resistors and a Hall voltage transformer, and performs overvoltage and undervoltage protection on the hybrid DC solid-state circuit breaker through the control circuit.

[0028] Optionally, the hybrid DC solid-state circuit breaker further includes a current detection module. The current detection module is connected in series at the rear end of the line where the branch formed by the series connection of the contacts of mechanical switch K2 and the power electronic device Q1 is connected in parallel with the main load-bearing contacts of mechanical switch K1, detects the current flowing through the circuit breaker by a Hall current transformer, and performs overcurrent protection on the hybrid DC solid-state circuit breaker through the control circuit.

[0029] In the embodiment of the present invention, the mechanical switch contact is connected in series with a power electronic device to form a branch that is connected in parallel with the main load-bearing mechanical switch contact; the main load-bearing mechanical switch contact is connected to the power supply end of the circuit breaker and the negative end of the load end; a freewheeling diode is connected in parallel at the load end; a current detection module is connected in series in the main circuit; a voltage detection module is connected in parallel at the power supply end of the circuit breaker.

[0030] Thus, the hybrid DC solid-state circuit breaker proposed by the present invention combines the advantages of pure mechanical and pure solid-state DC circuit breakers. A branch is formed by connecting the contact of the mechanical switch K2 in series with the power electronic device Q1 and is connected in parallel with the contact of the main load-bearing mechanical switch K1. When the contact of the mechanical switch K1 is turned on and off, the current flows through the parallel branch, and there is no arc during the on-off of the contact of the mechanical switch K1, realizing arc-free on-off of the circuit breaker. The power supply end and the load end are separated by the contacts of the mechanical switches K1, K2, and K3, realizing the high voltage withstand capacity of the circuit breaker. When the circuit breaker is conducting, the power supply current passes through the closed contact of the mechanical switch K1, and the resistance of the closed contact is very low. The heat generated when the current flows through the hybrid circuit breaker can achieve the heat dissipation purpose through natural cooling, and there is no need to add a special heat dissipation device to the power electronic device, realizing the ability to withstand large currents. By detecting the voltage and current at the power supply end of the circuit breaker, if a fault occurs, the circuit breaker can be quickly turned off.

[0031] The above description has been given for purposes of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A hybrid DC solid-state circuit breaker, characterized in that, Including: Mechanical switches K1, K2, K3, a power electronic device Q1, and a control circuit; the control circuit controls the turning on and off of the mechanical switches K1, K2, K3, and the power electronic device Q1; the contacts of the mechanical switch K2 are connected in series with the power electronic device Q1 to form a branch, and are connected in parallel with the contacts of the mechanical switch K1. When the hybrid DC solid-state circuit breaker needs to connect the load, the control circuit first controls the contacts of the mechanical switch K2 and the mechanical switch K3 to close, then controls the power electronic device Q1 to conduct, and then controls the contacts of the mechanical switch K1 to close. After the contacts of the mechanical switch K1 are fully closed, the control circuit controls the power electronic device Q1 to turn off, completing the process of the hybrid DC solid-state circuit breaker connecting the load. When the hybrid DC solid-state circuit breaker needs to disconnect the load with load, the control circuit first controls the power electronic device Q1 to conduct, and then disconnects the contacts of the mechanical switch K1. At this time, the current flows through the parallel branch, and the contacts of the mechanical switch K1 are disconnected without arc. After the contacts of the mechanical switch K1 are fully disconnected, then the control circuit controls the power electronic device Q1 to turn off. At this time, the current in the circuit is interrupted, and the overvoltage generated is absorbed by the surge protection module. Finally, the control circuit controls the contacts of the mechanical switch K2 and the mechanical switch K3 to disconnect, completing the process of the hybrid circuit breaker disconnecting the load. A freewheeling diode is connected in parallel at the load end of the hybrid DC solid-state circuit breaker to provide a freewheeling path for the inductive load when the hybrid DC solid-state circuit breaker is disconnected. It also includes a voltage detection module. The voltage detection module is connected in parallel at the power supply end of the circuit breaker, detects the input voltage by connecting multiple resistors in series with a Hall voltage transformer, and performs overvoltage or undervoltage protection on the hybrid DC solid-state circuit breaker through the control circuit. It also includes a current detection module. The current detection module is connected in series at the rear end of the line where the branch formed by the series connection of the contacts of the mechanical switch K2 and the power electronic device Q1 is connected in parallel with the main load-bearing contacts of the mechanical switch K1, detects the current flowing through the circuit breaker by a Hall current transformer, and performs overcurrent protection on the hybrid DC solid-state circuit breaker through the control circuit.

2. The hybrid DC solid-state circuit breaker according to claim 1, wherein The power electronic device Q1 is a MOS transistor or an IGBT.

3. The hybrid DC solid-state circuit breaker according to claim 1, characterized in that, The power electronic device Q1 is a thyristor.

4. The hybrid DC solid-state circuit breaker according to claim 1, wherein The power electronic device Q1 is a SiC device.

5. The hybrid DC solid-state circuit breaker according to claim 1, wherein The surge protection module is a varistor.

6. The hybrid DC solid-state circuit breaker according to claim 1, wherein The surge protection module is a transient voltage suppressor diode.

7. The hybrid DC solid-state circuit breaker according to claim 1, wherein, The surge protection module is a series connection of a discharge tube and a varistor voltage.

Images