Reverse current source based on RBDT, direct current circuit breaker, circuit breaking equipment and control method

Abstract

The invention belongs to the technical field of semiconductors, and particularly discloses a reverse current source based on RBDT, a direct-current circuit breaker, circuit breaking equipment and a control method. According to the invention, the carrier lifetime of the device RBDT is short, so that the device can be turned off by reducing the time of applying reverse voltage to the two ends of the RBDT, thereby achieving the purpose of quick turn-off. The resonant capacitor in the reverse current source based on the RBDT can be directly charged by a direct current system, an external power supply does not need to be additionally added for charging, and the RBDT direct current circuit breaker topological structure for charging the resonant capacitor can be realized only by the direct current system, so that the function of automatic reclosing can be realized after the fault current of the RBDT is cut off.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and more specifically, to a reverse current source, a DC circuit breaker, a circuit breaker device and a control method based on RBDT. Background Art

[0002] With the development of renewable energy, high-voltage direct current transmission has more advantages than traditional alternating current transmission in long-distance transmission. Since there is no current zero crossing in the DC system, the DC circuit breaker is a very important part of the DC power system. At present, DC circuit breakers can be divided into mechanical DC circuit breakers, solid-state DC circuit breakers and hybrid DC circuit breakers. Existing mechanical circuit breakers provide very low conduction losses, but have problems such as long response time and short life. In addition, mechanical circuit breakers require additional LC resonant circuits to generate current zero crossings, especially in high-voltage systems, which increases the volume and capacity of capacitors. In order to achieve fast response and long life, solid-state circuit breakers and hybrid circuit breakers are more attractive. In these two types of DC circuit breakers, semiconductor devices are used to cut off fault currents.

[0003] Fully controlled power devices have been widely studied and applied, such as silicon IGBTs. Silicon IGBTs can quickly cut off fault currents, but due to limited conduction modulation effects, power efficiency is low. In high-voltage systems, the series and parallel connection of IGBTs will inevitably lead to current and voltage imbalances. With the emergence of wide bandgap semiconductor devices, such as SiC MOSFETs, SiC JFETs, and GaN HEMTs, the blocking voltage of a single device is undoubtedly increased and the conduction loss is reduced. However, the cost is still high and reliability needs to be further improved. Thyristor-type power devices (IGCTs) are promising choices with low conduction losses and high surge current capabilities, but the series voltage balancing problem must also be considered in high-voltage systems.

[0004] Reverse blocking double-terminal solid-state thyristor (RBDT) is another thyristor-like power device. The current rise rate tolerance of RBDT reaches 18kA / μs. As a two-terminal power device, it has good series connection characteristics and does not require a voltage balancing strategy. However, the current DC circuit breaker based on RBDT has a slow shutdown speed, and an additional power supply is required to provide reverse current for RBDT during shutdown, which increases the complexity of the device. With the development of high-voltage DC power systems, requirements are put forward for the fast shutdown and automatic reclosing functions of DC circuit breakers. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a reverse current source, a DC circuit breaker, a circuit breaker device and a control method based on RBDT, aiming to solve the problems that the current DC circuit breaker based on RBDT has a slow shutdown speed, requires an additional power supply to provide reverse current for the RBDT when shutting down, and has a high degree of device complexity and large size.

[0006] To achieve the above-mentioned object, in a first aspect, the present application provides a reverse current source based on RBDT, the reverse current source comprising: a resonant capacitor, a resonant inductor, a resonant resistor and a first RBDT;

[0007] The first RBDT, the resonant inductor and the resonant resistor are connected in series and then connected in parallel with the resonant capacitor;

[0008] The cathode of the first RBDT is connected to the resonant inductor, and the anode is connected to the resonant capacitor;

[0009] The resonant capacitor is used to discharge through the resonant capacitor-first RBDT-resonant inductor-resonant resistor loop after the first RBDT is turned on. After a period of time, the polarity is reversed and a reverse current is provided to the outside.

[0010] Preferably, the resonant capacitor, resonant inductor and resonant resistor satisfy the following underdamping condition:

[0011]

[0012] Among them, R ocs is the resonant resistance, L ocs is the resonant inductor, C ocs is the resonant capacitor.

[0013] Preferably, the turn-off time of the first RBDT is 5 μs to 20 μs.

[0014] To achieve the above-mentioned object, in a second aspect, the present application provides a high-speed DC circuit breaker capable of automatic reclosing based on RBDT, comprising: a second RBDT, a commutation resistor and a reverse current source as described in the first aspect;

[0015] The cathode of the second RBDT is directly connected to one output terminal of the reverse current source, and the anode is connected to the other output terminal of the reverse current source through a commutation resistor;

[0016] The second RBDT is used to conduct the working current when the DC power system is operating normally and to withstand the fault current when a short circuit fault occurs;

[0017] The reverse current source is used to discharge after receiving the trigger signal, and provide a reverse current greater than the maximum fault current to the second RBDT, so as to turn off the second RBDT.

[0018] Preferably, the resistance of the commutation resistor is smaller than the resonant resistor.

[0019] Preferably, a mechanical switch is connected in parallel at both ends of the second RBDT.

[0020] Preferably, the turn-off time of the second RBDT is 5 μs to 20 μs.

[0021] Preferably, the P base concentration of RBDT is 5e15-1e17cm -3 , thickness is 30um~50um.

[0022] It should be noted that by reducing the P-base concentration of the semiconductor switch RBDT and thinning the P-base thickness, a turn-off speed of RBDT of only about 10 microseconds was achieved, solving the problem of slow turn-off speed of thyristor devices, and laying the foundation for the application of RBDT in high-voltage DC systems.

[0023] To achieve the above-mentioned purpose, in a third aspect, the present application provides a control method for a high-speed DC circuit breaker capable of automatic reclosing based on RBDT as described in the second aspect,

[0024] In the case where the mechanical switch is not connected in parallel at both ends of the second RBDT, the control method includes: when the current of the power system is greater than the set threshold current of the DC circuit breaker, applying a dv / dt voltage pulse to the first RBDT to make the resonant circuit start to resonate, and providing a reverse current to the second RBDT to cause the second RBDT to shut down; after the short-circuit fault is eliminated, applying a dv / dt voltage pulse to both ends of the anode and cathode of the second RBDT to turn on the second RBDT;

[0025] For the case where mechanical switches are connected in parallel at both ends of the second RBDT, the control method includes: when the current of the power system is greater than the set threshold current of the DC circuit breaker, a trip command is issued to the mechanical switch to gradually separate the mechanical switch, and a dv / dt voltage pulse is applied to the anode and cathode of the second RBDT to turn on the second RBDT and transfer the fault current; when the mechanical switch forms a sufficient insulation gap, a dv / dt voltage pulse is applied to the first RBDT to start the resonant circuit to resonate, and a reverse current is provided to the second RBDT to cause the second RBDT to shut down; after the short-circuit fault is eliminated, a closing command is issued to the mechanical switch to turn on the mechanical switch.

[0026] To achieve the above-mentioned objectives, in a fourth aspect, the present application provides an RBDT-based high-speed DC circuit breaker with automatic reclosing, comprising: a controller and the RBDT-based high-speed DC circuit breaker with automatic reclosing as described in the second aspect; the controller is used to execute computer instructions to implement the control method as described in the third aspect.

[0027] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0028] (1) The present application proposes a reverse current source based on RBDT. The resonant switch adopts RBDT. When the polarity of the resonant capacitor is reversed, the RBDTc is turned off. Compared with the reverse current source based on thyristor, it has the advantage of high repetition rate.

[0029] (2) The present application proposes a high-speed DC circuit breaker with automatic reclosing based on RBDT. The carrier lifetime of the RBDT device is low, so it can be turned off by reducing the time of applying reverse voltage at both ends of the RBDT, thereby achieving the purpose of rapid shutdown; the resonant capacitor in the reverse current source can be directly charged by the DC system, without the need for an additional external power supply for charging. The RBDT DC circuit breaker topology with resonant capacitor charging can be realized by the DC system alone, thereby realizing the function of automatic reclosing after the RBDT cuts off the fault current. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a circuit diagram of a high-speed solid-state DC circuit breaker with automatic reclosing based on RBDT provided in an embodiment of the present application.

[0031] Figure 2 is a diagram of the fault current removal process of a high-speed solid-state DC circuit breaker capable of automatic reclosing based on RBDT provided in an embodiment of the present application, wherein (a) corresponds to a load R L A removable short-circuit fault occurs. (b) corresponds to the resonant capacitor polarity reversal, (c) corresponds to the reverse current, and (d) corresponds to the load R L The fault current is cut off.

[0032] Figure 3 It is a simulation waveform diagram of a high-speed solid-state DC circuit breaker capable of automatic reclosing based on RBDT provided in an embodiment of the present application.

[0033] Figure 4 This is a simulation comparison chart of different RBDT shutdown rates provided in the embodiments of the present application.

[0034] Figure 5 This is a circuit diagram of a high-speed hybrid DC circuit breaker with automatic reclosing based on RBDT provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0036] like Figure 1As shown, the present application provides a high-speed solid-state DC circuit breaker capable of automatic reclosing based on RBDT, comprising: a semiconductor switch RBDT m , commutation resistance R c And the reverse current source based on RBDT.

[0037] The reverse current source based on RBDT is composed of a resonant capacitor C ocs , resonant inductor L ocs , resonant resistance R ocs and a resonant switch, wherein the resonant switch is a RBDT c . Because C ocs , L ocs , R ocs A resonant current needs to be generated between the three to provide a m Provide reverse current, so these three need to meet the underdamping condition, as shown in formula (1):

[0038]

[0039] like Figure 2 As shown, the specific working process of the solid-state DC circuit breaker is: when the load R L A removable short-circuit fault occurs, and the current flowing through RBDT m The current will gradually increase, such as Figure 2 When the set current threshold is reached, the RBDT c The resonant capacitor is turned on through C ocs -RBDT c -L ocs -R ocs The circuit generates electricity due to the resonant resistance R ocs The condition of formula (1) is satisfied, so the polarity of the resonant capacitor will be reversed after a period of time, such as Figure 2 As shown in (b). At this time, the resonant capacitor will pass through C ocs -RBDT m -R c The circuit is RBDT m Provides reverse current, such as Figure 2 As shown in (c), RBDT m Turn off, load R L The fault current is removed and the polarity of the resonant capacitor is restored to the same polarity as the DC system. Figure 2 (d) As shown. When RBDT m After closing again, the load R L The current on the RBDT is continuously stable at the normal value. If the short circuit fault is not removed, when the RBDT m After closing, the load R LThe current will continue to rise rapidly and exceed the threshold, thus repeating Figure 2 process until the short circuit fault is eliminated.

[0040] Figure 3 RBDT is a semiconductor switch in a high-speed solid-state DC circuit breaker with automatic reclosing based on RBDT. m Voltage (U RBDTm ), semiconductor switch RBDTm current (I RBDTm ), resonant switch RBDT c Current (I RBDTc ) and the resonant capacitor voltage (U Cocs ) of the simulation waveform. Figure 3 As shown, I RBDTc When it starts to drop, the resonant circuit starts to resonate and provides reverse current to RBDTm. m The current (I RBDTm ) gradually decreases to 0, the semiconductor switch RBDT m Voltage (U RBDTm ) and the resonant capacitor voltage (U Cocs ) are gradually restored, verifying that the resonant capacitor does not need an additional power supply to charge it, greatly reducing the size of the DC circuit breaker.

[0041] The RBDT is turned off by forming a reverse voltage at the J3 junction to prevent the N+ region from injecting electrons into the P base region. The reverse voltage is shown in formula (2):

[0042] ΔV=I·R p (2)

[0043] Where I is the reverse current, R p is the P base resistance. Therefore, the larger the P base resistance, the more conducive it is to provide a reverse voltage greater than the J3 junction built-in potential (about 0.7V). By reducing the P base concentration and the thickness of the P base, the purpose of increasing the P base resistance can be achieved, and then the reverse voltage time is shorter, that is, the turn-off time is shorter.

[0044] Preferably, the thickness of the P base region is 30 um to 50 um.

[0045] Preferably, the concentration of the P base region is 5e15-1e17 cm -3 .

[0046] Figure 4 For two different RBDT m The voltage waveform of the upper part is the RBDT with undesigned P base concentration and thickness. m The lower part is the RBDT with designed P base concentration and thickness. m . It can be seen that Figure 4The turn-off time in the above figure is about 35μs. After the concentration and thickness of the P base region of RBDT are designed in this application, RBDT m The turn-off time of RBDT is only about 10μs, which greatly improves the turn-off speed of RBDT, thereby speeding up the speed of DC fault current removal based on RBDT. m The turn-off time is only about 10μs. The shorter the turn-off time, the shorter the resonant period. L and C are proportional to the resonant period, so the resonant capacitor C ocs , resonant inductor L ocs The value of can be reduced, thereby reducing the volume of these three, further reducing the volume of the DC circuit breaker, and saving the cost of the circuit breaker.

[0047] like Figure 5 As shown, the present application provides a high-speed hybrid DC circuit breaker capable of automatic reclosing based on RBDT, and the hybrid DC circuit breaker is suitable for high-voltage power systems. Figure 1 Compared with the above, a mechanical switch S is connected in parallel at both ends of the semiconductor switch branch. m The specific working process is as follows: During normal operation, the mechanical switch is in a closed state, and the RBDT m and RBDT c The switch is in the off state, and the system current flows through the mechanical switch S m ; When the system load fails and the current rises rapidly to the threshold, RBDT m Closed, the mechanical switch opens, thereby transferring the fault current to the RBDT m , when the mechanical switch forms a sufficient insulation gap, RBDT c Closed, C ocs , L ocs , R ocs The resonance of the three is RBDT m Provides reverse current, thereby RBDT m Shut down, thereby cutting off the fault current.

[0048] The RBDT-based high-speed DC circuit breaker with automatic reclosing has self-voltage equalization capability, eliminating the need for additional series voltage equalization measures, thereby reducing the cost of the circuit breaker.

[0049] The DC circuit breaker based on RBDT has a very high current rise rate tolerance capability (>10kA / μs). Such a high current rise rate tolerance ensures that the DC circuit breaker based on RBDT will not be damaged due to the fast rise speed of the fault current in the DC power system.

[0050] The RBDT-based automatic reclosing high-speed DC circuit breaker theoretically has no current cutoff limit. It only needs to provide a reverse voltage for a sufficient time (10 microseconds) to cut off any size of fault current in the DC system. It is simple to operate and has a high upper limit.

[0051] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0052] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0053] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0054] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A reverse current source based on RBDT, characterized in that: The reverse current source includes: a resonant capacitor, a resonant inductor, a resonant resistor and a first RBDT; The first RBDT, the resonant inductor and the resonant resistor are connected in series and then connected in parallel with the resonant capacitor; The cathode of the first RBDT is connected to the resonant inductor, and the anode is connected to the resonant capacitor; The resonant capacitor is used to discharge through the resonant capacitor-first RBDT-resonant inductor-resonant resistor loop after the first RBDT is turned on. After a period of time, the polarity is reversed and a reverse current is provided to the outside.

2. The reverse current source according to claim 1, characterized in that: The resonant capacitor, resonant inductor and resonant resistor satisfy the following underdamping conditions: Among them, R ocs is the resonant resistance, L ocs is the resonant inductor, C ocs is the resonant capacitor.

3. The reverse current source according to claim 1, characterized in that: The turn-off time of the first RBDT is 5 μs to 20 μs.

4. A high-speed DC circuit breaker with automatic reclosing function based on RBDT, characterized in that: include: A second RBDT, a commutation resistor and a reverse current source as claimed in any one of claims 1 to 3; The cathode of the second RBDT is directly connected to one output terminal of the reverse current source, and the anode is connected to the other output terminal of the reverse current source through a commutation resistor; The second RBDT is used to conduct the working current when the DC power system is operating normally and to withstand the fault current when a short circuit fault occurs; The reverse current source is used to discharge after receiving the trigger signal, and provide a reverse current greater than the maximum fault current to the second RBDT, so as to turn off the second RBDT.

5. The DC circuit breaker according to claim 4, characterized in that: The resistance of the commutation resistor is smaller than the resonant resistor.

6. The DC circuit breaker according to claim 4, characterized in that: A mechanical switch is connected in parallel at both ends of the second RBDT.

7. The DC circuit breaker according to claim 4, characterized in that: The turn-off time of the second RBDT is 5 μs to 20 μs.

8. The DC circuit breaker according to claim 4, characterized in that: The P base concentration of RBDT is 5e15~1e17cm -3 , thickness is 30um~50um.

9. A control method for a high-speed DC circuit breaker capable of automatic reclosing based on RBDT according to any one of claims 4 to 8, characterized in that: In the case where the mechanical switch is not connected in parallel at both ends of the second RBDT, the control method includes: when the current of the power system is greater than the set threshold current of the DC circuit breaker, applying a dv / dt voltage pulse to the first RBDT to make the resonant circuit start to resonate, and providing a reverse current to the second RBDT to cause the second RBDT to shut down; after the short-circuit fault is eliminated, applying a dv / dt voltage pulse to both ends of the anode and cathode of the second RBDT to turn on the second RBDT; For the case where mechanical switches are connected in parallel at both ends of the second RBDT, the control method includes: when the current of the power system is greater than the set threshold current of the DC circuit breaker, a trip command is issued to the mechanical switch to gradually separate the mechanical switch, and a dv / dt voltage pulse is applied to the anode and cathode of the second RBDT to turn on the second RBDT and transfer the fault current; when the mechanical switch forms a sufficient insulation gap, a dv / dt voltage pulse is applied to the first RBDT to start the resonant circuit to resonate, and a reverse current is provided to the second RBDT to cause the second RBDT to shut down; after the short-circuit fault is eliminated, a closing command is issued to the mechanical switch to turn on the mechanical switch.

10. A high-speed DC circuit breaker device with automatic reclosing function based on RBDT, characterized in that: include: A controller and an automatically reclosable high-speed DC circuit breaker based on RBDT as claimed in any one of claims 4 to 8; The controller is used to execute computer instructions to implement the control method as claimed in claim 9.

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