Solid-state dc circuit breaker and control method thereof

Abstract

A solid-state DC circuit breaker and its control method are disclosed. The solid-state DC circuit breaker includes a first switch connected to a main line and a switching assembly. The switching assembly includes a second switch, a semiconductor power switch, and a control module for controlling the semiconductor power switch. The second switch and the semiconductor power switch are connected in series and in parallel across the first switch. When the circuit breaker trips, the first switch opens before the second switch. After the control module detects that the first switch has changed from closed to open, before the second switch opens, the control module drives the semiconductor power switch to conduct first and then cut off. This invention provides a solid-state DC circuit breaker and its control method. The control module enables the semiconductor power switch to conduct for a short time, which helps to extinguish the electric arc and reduce the damage of the arc to the equipment. It also has the advantages of small size and low cost.

Description

Technical Field

[0001] This invention relates to DC circuit breakers, and more specifically to a solid-state DC circuit breaker and its control method. Background Technology

[0002] During the switching process of a DC switch, a DC arc will be generated. This arc current does not exceed zero in time and is non-periodic, making it more difficult to extinguish than an AC arc. Existing pure solid-state circuit breakers, such as those from Atom Power and ABB, can effectively solve the technical problem of DC interruption. However, long-term operation leads to high equipment temperature, large power loss, and high cost. While some hybrid solid-state circuit breakers can turn on the semiconductor power device before the mechanical switch opens and turn it off when the mechanical switch is fully open, thus achieving DC interruption through the semiconductor power device, this method requires the semiconductor power device to withstand short-circuit current for a certain period of time, resulting in high cost and large size of the semiconductor power device used. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-cost, small-sized, and highly reliable solid-state DC circuit breaker and its control method.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A solid-state DC circuit breaker includes a first switch connected to a main line and a switch assembly. The switch assembly includes a second switch, a semiconductor power switch, and a control module for controlling the semiconductor power switch. The second switch and the semiconductor power switch are connected in series and in parallel across the first switch. When the circuit breaker trips, the first switch opens before the second switch. After the control module detects that the first switch has changed from closed to open, before the second switch opens, the control module drives the semiconductor power switch to turn on and then off.

[0006] Furthermore, when the circuit breaker trips, the circuit breaker's operating mechanism synchronously drives the first and second switches to operate, causing the first and second switches to disconnect sequentially.

[0007] Furthermore, the control module determines the first switch from closed to open by monitoring the position of the first switch, and / or whether the first switch generates an electric arc, and / or the main line current, and / or the voltage of the semiconductor power switch.

[0008] Furthermore, the switching assembly also includes a power supply circuit connected in parallel across the semiconductor power switch, which converts the voltage across the semiconductor switching element into operating power.

[0009] Furthermore, the switching assembly also includes a voltage detection circuit connected in parallel across the semiconductor power switch, the voltage detection circuit being connected to the control module for feedback of the voltage of the semiconductor power switch.

[0010] Furthermore, the switch assembly also includes a third switch and a mechanical triggering circuit connected to the control module. When the first switch is turned off, the third switch can trigger the mechanical triggering circuit, and the control module monitors the position of the first switch through the mechanical triggering circuit.

[0011] Furthermore, an arc detection circuit is also connected to the main line. The arc detection circuit is connected to the control module to provide feedback on whether an arc has been generated.

[0012] Furthermore, a current detection circuit is also connected to the main line, and the current detection circuit is connected to the control module to provide feedback on the current signal of the main line.

[0013] Furthermore, when the circuit breaker is closed, both the first and second switches are closed, while the semiconductor power switch remains off.

[0014] A control method for a solid-state DC circuit breaker is disclosed. The solid-state DC circuit breaker includes a switching assembly and a first switch connected to a main line. The switching assembly includes a second switch, a semiconductor power switch, and a control module for controlling the semiconductor power switch. The second switch and the semiconductor power switch are connected in series and in parallel across the first switch. When the circuit breaker trips, the first switch trips before the second switch trips. After the first switch trips but before the second switch trips, the semiconductor power switch is turned on and then off. In this invention, a solid-state DC circuit breaker and its control method are disclosed. When the circuit breaker trips, the first and second switches trip sequentially. After the first switch trips and arcs, but before the second switch trips, the control module briefly turns on the semiconductor power switch to eliminate the arc generated when the first switch trips, thereby reducing the damage to the first switch when tripping DC power. Furthermore, because the semiconductor power switch has an extremely short trip time, the power it needs to carry is lower than that of a pure solid-state circuit breaker and also lower than the power carried by the semiconductor switching elements in existing hybrid solid-state DC circuit breakers. Therefore, it has the advantages of small size and low cost.

[0015] In addition, a power supply circuit is connected in parallel across the semiconductor power switch. The power supply circuit converts the arc voltage or load voltage across the semiconductor power switch into a working power supply, which can provide working power for the control module, current detection circuit, voltage detection circuit, surge absorption device, and arc detection circuit.

[0016] In addition, when the first switch opens and arcs, a signal is fed back to the control module. The feedback signal can be one or more of the following: the position signal of the first switch, the voltage signal of the semiconductor power switch, the main line current signal, and whether the first switch generates an arc signal. The control methods are diverse and have a wide range of applications. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a solid-state DC circuit breaker according to the present invention;

[0018] Figure 2 This is a schematic diagram of the timing characteristics of a solid-state DC circuit breaker according to the present invention. Detailed Implementation

[0019] The following embodiments, in conjunction with the accompanying drawings, further illustrate specific implementations of a solid-state DC circuit breaker and its control method according to the present invention. The solid-state DC circuit breaker and its control method of the present invention are not limited to the descriptions in the following embodiments.

[0020] A solid-state DC circuit breaker includes a first switch K1 connected to a main line. The switching assembly includes a second switch K2, a semiconductor power switch Q, and a control module for controlling the semiconductor power switch Q. The second switch K2 and the semiconductor power switch Q are connected in series and in parallel across the first switch K1. When the circuit breaker trips, the first switch K1 opens before the second switch K2. After the control module detects that the first switch K1 has changed from closed to open, before the second switch K2 opens, the control module drives the semiconductor power switch Q to conduct for a period of time and then cuts off. Finally, the second switch K2 opens.

[0021] This invention discloses a solid-state DC circuit breaker and its control method. When the circuit breaker trips, the first switch K1 and the second switch K2 are driven to disconnect sequentially. After the first switch K1 disconnects and the arc is ignited, and before the second switch K2 disconnects, the control module briefly turns on the semiconductor power switch Q, thereby eliminating the arc generated when the first switch K1 disconnects, thus reducing the damage to the first switch K1 caused by the arc when disconnecting DC power. In addition, since the conduction time of the semiconductor power switch Q is extremely short, the power that the semiconductor power switch Q needs to carry is lower than that of a pure solid-state circuit breaker, and also lower than the power carried by the semiconductor switching element in the existing hybrid solid-state DC circuit breaker. Therefore, it has the advantages of small size and low cost.

[0022] When the solid-state DC circuit breaker is closed, both the first switch K1 and the second switch K2 are closed, and the semiconductor power switch Q remains off. At this time, the closed first switch K1 keeps the main line connected, and no current flows through the series-connected second switch K2 and semiconductor power switch Q, allowing the electrical equipment connected to the main line to operate normally. When the circuit breaker is opened (including normal opening and opening due to line fault), the first switch K1 opens and an arc is generated. The control module drives the semiconductor power switch Q to conduct for a short period of time before the second switch opens. At this time, the arc is extinguished by the line controlled by the semiconductor power switch Q and the second switch K2. Subsequently, the second switch K2 opens, the first switch K1 opens, the semiconductor power switch Q is off, and no current flows through the main line. Normal closing can be performed after normal closing or after the fault is cleared.

[0023] When the first switch K1 is opened and an arc is initiated, the control module controls the semiconductor power switch Q according to the received feedback signal. The feedback signal can be the position signal of the first switch K1, the voltage signal of the semiconductor power switch Q, the current signal of the main line, and the signal indicating whether the first switch K1 generates an arc. Multiple feedback signals can be used individually or in combination of any two or more, resulting in diverse control methods and greater applicability.

[0024] Preferably, the first switch K1 and the second switch K2 are synchronously driven by the same actuating mechanism in the circuit breaker. The first switch K1 and the second switch K2 are positioned within different travel ranges of the actuating mechanism. For example, the first switch K1 is positioned at the beginning of the travel range of the actuating mechanism, and the second switch K2 is positioned at the end of the travel range of the actuating mechanism. The circuit breaker's operating mechanism can serve as one of the actuating mechanisms. During normal opening and closing of the circuit breaker, the operating mechanism drives the first switch K1 to open or close. When a fault occurs in the main line, such as a short circuit, the circuit breaker's thermal trip mechanism triggers the operating mechanism to actuate the first switch K1 and the second switch K2, but it is necessary to ensure that the first switch K1 opens first.

[0025] In addition, the sequential opening of the first switch K1 and the second switch K2 can be driven stepwise by two different actuating mechanisms. For example, the first switch K1 can be driven by an actuating mechanism in the circuit breaker, such as an operating mechanism, and the second switch K2 can be set within the operating stroke of the first switch K1. In this way, the first switch K1 can act as an actuating mechanism to drive the second switch K2. After the actuating mechanism drives the first switch K1 to open, when the first switch K1 moves to the stroke position corresponding to the second switch K2, the second switch K2 is triggered to open.

[0026] Combination Figure 1 , 2An embodiment of a first solid-state DC circuit breaker and its control method is provided. The solid-state DC circuit breaker includes an operating mechanism connected to a main circuit and a first switch K1. The first switch K1 and the operating mechanism are connected in series between the input and output terminals of the main circuit. In this embodiment, a thermal trip mechanism can trigger the operating mechanism, which acts as the operating mechanism, causing the operating mechanism to trip and drive the first switch K1 and the second switch K2 to open. A switch assembly is connected in parallel across the first switch K1. The switch assembly has the functions of isolation and carrying a certain power. The switch assembly includes a second switch K2, a semiconductor power switch Q, a voltage detection circuit, a power supply circuit, and a control module. The second switch K2 is connected in series with the semiconductor power switch Q. The power supply circuit and the voltage detection circuit are both connected in parallel across the semiconductor power switch Q. The power supply circuit supplies power to the voltage detection circuit and the control module. The voltage detection device detects the voltage across the semiconductor power switch Q and can transmit a voltage signal to the control module. The control module includes a logic control circuit and a drive circuit. The logic control circuit is connected to the voltage detection circuit, and the drive circuit is connected to the semiconductor power switch Q. The logic control circuit obtains the feedback voltage signal of the semiconductor power switch Q through the voltage detection circuit.

[0027] The operating mechanism can drive the first switch K1 and the second switch K2 to operate synchronously, and drive the first switch K1 and the second switch K2 to close. When closing, it is preferable that the second switch K2 and the first switch K1 can close sequentially or synchronously. The operating mechanism can also drive the first switch K1 and the second switch K2 to open. When opening, the first switch K1 opens before the second switch K2. When the circuit breaker is closed, the first switch K1 and the second switch K2 are in the closed state, and the semiconductor power switch Q is in the off state. At this time, the main line is working normally. When the circuit breaker is opened, both the first switch K1 and the second switch K2 are driven synchronously by the operating mechanism, but the first switch K1 opens first, and the second switch K2 opens after a period of time. During this period, the voltage across the semiconductor power switch Q increases. The logic control circuit of the control module obtains the voltage signal at this time through the voltage detection circuit, and judges that the conduction condition is met based on the received and processed voltage signal. The logic control circuit outputs a control signal through the drive circuit to make the semiconductor power switch Q conduct first and then cut off within a certain period of time. When the semiconductor power switch is conducting, it can extinguish the arc generated by the first switch K1. Finally, the second switch K2 opens, and the main line between the input terminal and the output terminal is disconnected. Figure 2 As shown, the control module drives the semiconductor power switch Q to first turn on and then turn off within a time T. The time T is less than the time interval between the first switch K1 and the second switch K2 being turned off. The on-time of the semiconductor power switch Q is determined by the logic control circuit. The logic control circuit has a control function on the semiconductor power switch Q and is used to control the on and off times of the semiconductor power switch Q. The on-time can be preset.

[0028] In this embodiment of the solid-state DC circuit breaker, the control module determines the first switch K1 from closed to open by monitoring the voltage of the semiconductor power switch Q. After the first switch K1 is opened and before the second switch K2 is opened, the semiconductor power switch Q is controlled to be turned on and then turned off in a short period of time. This can not only eliminate the arc and reduce the damage of the arc to the first switch K1, but also make the power required by the semiconductor power switch Q low, which has the advantages of small size and low cost.

[0029] Simultaneously, when the first switch K1 is disconnected under load, and before the semiconductor power switch Q is driven to conduct by the control module (i.e., in the off-state before conduction), an arc voltage is generated on the two poles of the semiconductor power switch Q that carry power. The power supply circuit is connected in parallel to the two poles of the semiconductor power switch Q that carry power to convert the voltage generated by the arc to the electrical energy required by other circuits. When the semiconductor power switch Q is in the off-state after conduction, the arc of the first switch K1 dissipates. Since the second switch K2 is not yet disconnected, there is a load voltage on the two poles of the semiconductor power switch Q that carry power. The power supply circuit is connected in parallel to the two poles of the semiconductor power switch Q that carry power to convert the load voltage to the electrical energy required by other circuits. In this embodiment, the power supply circuit supplies power to the control module and the voltage detection circuit. Of course, a power supply circuit can also be omitted, and the control module and the voltage detection circuit can be powered by an external power source.

[0030] Preferably, a surge absorption device is connected in parallel across the semiconductor power switch Q. The surge absorption device is also powered by the power supply circuit and is used to conduct current shunting to prevent sudden surges from damaging the equipment in the circuit.

[0031] In this embodiment, the logic control circuit can be an MCU, a microprocessor, or a single-chip microcomputer, or it can be a hardware circuit including a comparator; the first switch K1 and the second switch K2 are both mechanical switches; the semiconductor power switch Q can be a silicon-based power device such as an IGBT or MOSFET, or a SiC-based MOSFET or JFET, or a GaN-based MOSFET, or other forms of semiconductor power devices; the surge absorption device can be a varistor, a transient suppression diode, a discharge tube, or other single devices or combinations thereof.

[0032] Combination Figure 1 , 2An embodiment of a second solid-state DC circuit breaker and its control method is provided. The solid-state DC circuit breaker is the same as the first embodiment, including a thermal trip mechanism connected in series between the input terminal and the output terminal and a first switch K1. A switching assembly capable of carrying a certain power is connected in parallel across the two ends of the first switch K1. The switching assembly includes a second switch K2 and a semiconductor power switch Q connected in series, and a control module for controlling the semiconductor power switch Q. The first switch K1 and the second switch K2 are driven synchronously by the same actuating mechanism but are disconnected sequentially. The control module controls the semiconductor power switch Q to conduct for a short time during the time interval between the sequential disconnection of the first switch K1 and the second switch K2.

[0033] Unlike the first embodiment, the control module determines the change of the first switch K1 from closed to open by monitoring the position of the first switch K1. The switch assembly also includes a third switch K3 and a mechanical trigger circuit. The third switch K3, the second switch K2, and the semiconductor power switch Q are connected in series. When the first switch K1 is open, the third switch K3 is triggered. The mechanical trigger circuit is connected to the control module and is triggered by the third switch K3. Preferably, the third switch K3 is a microswitch and is installed within the operating stroke of the first switch K1. The third switch K3 has a position information that can detect the opening process of the first switch K1 and feeds the signal back to the control module through the mechanical trigger circuit. The control module includes a logic control circuit and a drive circuit. The logic control circuit is connected to the mechanical trigger circuit to obtain the signal that feeds back the position of the first switch K1. The drive circuit is connected to the semiconductor power switch Q and, under the control of the logic control circuit, drives the semiconductor power switch Q to first conduct and then cut off within time T. Figure 2 As shown, time T is less than the time interval between the opening of the first switch K1 and the second switch K2.

[0034] The solid-state DC circuit breaker in this embodiment detects the position of the first switch K1 and causes the control module to drive the semiconductor power switch Q to conduct and then cut off in a short time. This not only eliminates the arc and reduces the damage of the arc to the first switch K1, but also reduces the power that the semiconductor power switch Q needs to carry, resulting in advantages such as small size and low cost.

[0035] Combination Figure 1 , 2 An embodiment of a third solid-state DC circuit breaker and its control method is provided. The solid-state DC circuit breaker is the same as the first embodiment, including a thermal trip mechanism connected in series between the input terminal and the output terminal and a first switch K1. The same switching components as in the first embodiment are connected in parallel across the two ends of the first switch K1. After the first switch K1 is opened and arcing occurs, and before the second switch K2 is opened, the semiconductor power switch Q is controlled and the control module is turned on for a short time to extinguish the arc when the first switch K1 is opened.

[0036] Unlike the first embodiment, the control module determines the opening / closing of the first switch K1 by monitoring the main line current. The control module controls the switching of the semiconductor power switch Q based on the current signal in the main line. A current detection circuit is connected in series on the main line between the input and output terminals; preferably, the current detection circuit is a current transformer connected in series on the main line. When a large current passes through the thermal trip mechanism, the first switch K1 is driven to open. The current detection circuit transmits the acquired current signal to the control module. At this time, the logic control circuit in the control module determines that there is a large current in the main line, meeting the conduction condition. For example, when the current value exceeds a predetermined threshold, the drive circuit controls the semiconductor power switch Q to complete the action of first turning on and then turning off before the second switch K2 opens. Preferably, the semiconductor power switch Q completes the action within time T, which is less than the time interval between the opening of the first switch K1 and the second switch K2.

[0037] The solid-state DC circuit breaker in this embodiment detects the current signal in the main circuit and drives the control module to turn the semiconductor power switch Q on and off in a short time. This can eliminate the arc and reduce the damage of the arc to the first switch K1. It also reduces the power that the semiconductor power switch Q needs to carry, and has the advantages of small size and low cost.

[0038] Combination Figure 1 , 2 An embodiment of a fourth solid-state DC circuit breaker and its control method is provided. The solid-state DC circuit breaker is the same as the first embodiment, including a thermal trip mechanism connected in series between the input terminal and the output terminal and a first switch K1. A switch assembly identical to that in the first embodiment is connected in parallel across the two ends of the first switch K1. The first switch K1 and the second switch K2 of the switch assembly are both driven synchronously by the same actuating mechanism. During the time interval between the first switch K1 and the second switch K2 being turned off, the control module controls the semiconductor power switch Q to be turned on for a short time to extinguish the arc generated when the first switch K1 is turned off.

[0039] Unlike the first embodiment, the control module determines whether the first switch K1 changes from closed to open by monitoring whether an electric arc is generated. The control module controls the switching on and off of the semiconductor power switch Q based on the feedback arc signal. An arc detection circuit is connected in series on the main line between the input and output terminals. When the first switch K1 opens and an arc is generated, the arc detection circuit acquires the arc signal and transmits it to the control module. At this time, the logic control circuit in the control module determines that the conduction condition is met, and controls the semiconductor power switch Q to conduct briefly before the second switch K2 opens, and then turn off. Preferably, the semiconductor power switch Q completes its action within time T, which is less than the time interval between the opening of the first switch K1 and the second switch K2.

[0040] In this embodiment of the solid-state DC circuit breaker, the control module obtains the presence of an arc through an arc detection circuit, and controls the semiconductor power switch Q to first turn on and then turn off in a short time. This not only eliminates the arc and reduces the damage of the arc to the first switch K1, but also reduces the power that the semiconductor power switch Q needs to carry, thus having the advantages of small size and low cost.

[0041] In the second, third, and fourth embodiments, a power supply circuit and a surge absorption device can also be connected in parallel across the two ends of the semiconductor power switch Q. The working principle of the power supply circuit and the surge absorption device is the same as that of the first embodiment. The power supply circuit can supply power to the mechanical trigger circuit, the current detection circuit, and the arc detection circuit, respectively.

[0042] In this application, any two or more of the above four embodiments can be combined. Figure 1 , 2 These are four embodiments combined together.

[0043] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A solid-state DC circuit breaker, comprising a first switch (K1) connected to a main line, characterized in that: It also includes a switching assembly, which includes a second switch (K2), a semiconductor power switch (Q), and a control module for controlling the semiconductor power switch (Q). The second switch (K2) and the semiconductor power switch (Q) are connected in series and connected in parallel across the first switch (K1). When the circuit breaker is closed, both the first switch (K1) and the second switch (K2) are in the closed state, and the semiconductor power switch (Q) remains in the off state. When the circuit breaker is tripped, the first switch (K1) is tripped before the second switch (K2). After the control module detects that the first switch (K1) has changed from closed to open, before the second switch (K2) is tripped, the control module drives the semiconductor power switch (Q) to conduct first and then cut off, so that the arc generated when the first switch (K1) is tripped disappears.

2. A solid-state DC circuit breaker according to claim 1, characterized in that: When the circuit breaker trips, the circuit breaker's operating mechanism synchronously drives the first switch (K1) and the second switch (K2) to operate, causing the first switch (K1) and the second switch (K2) to disconnect one after the other.

3. A solid-state DC circuit breaker according to claim 1, characterized in that: The control module determines whether the first switch (K1) changes from closed to open by monitoring the position of the first switch (K1), and / or whether the first switch (K1) generates an electric arc, and / or the main line current, and / or the voltage of the semiconductor power switch (Q).

4. A solid-state DC circuit breaker according to claim 1, characterized in that: The switching assembly also includes a power supply circuit connected in parallel across the semiconductor power switch (Q), which converts the voltage across the semiconductor switching element into operating power.

5. A solid-state DC circuit breaker according to any one of claims 1-4, characterized in that: The switching assembly also includes a voltage detection circuit connected in parallel across the semiconductor power switch (Q), which is connected to the control module to provide feedback on the voltage of the semiconductor power switch (Q).

6. A solid-state DC circuit breaker according to any one of claims 1-4, characterized in that: The switching assembly also includes a third switch (K3) and a mechanical triggering circuit connected to the control module. When the first switch (K1) is turned off, the third switch (K3) can trigger the mechanical triggering circuit. The control module monitors the position of the first switch (K1) through the mechanical triggering circuit.

7. A solid-state DC circuit breaker according to any one of claims 1-4, characterized in that: An arc detection circuit is also connected to the main line. The arc detection circuit is connected to the control module to provide feedback on whether an arc has been generated.

8. A solid-state DC circuit breaker according to any one of claims 1-4, characterized in that: A current detection circuit is also connected to the main line. The current detection circuit is connected to the control module to provide feedback on the current signal of the main line.

9. A control method for a solid-state DC circuit breaker, the solid-state DC circuit breaker comprising a switching assembly and a first switch (K1) connected to a main line, the switching assembly comprising a second switch (K2), a semiconductor power switch (Q), and a control module for controlling the semiconductor power switch (Q), wherein the second switch (K2) and the semiconductor power switch (Q) connected in series are connected in parallel across the first switch (K1), characterized in that: When the circuit breaker trips, the first switch (K1) is opened before the second switch (K2), and the semiconductor power switch (Q) is turned on and then turned off after the first switch (K1) is opened and before the second switch (K2) is opened.

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