A medium-high voltage bidirectional all-solid-state DC circuit breaker and its high-potential energy supply device

Abstract

The present invention provides a medium- and high-voltage bidirectional all-solid-state DC circuit breaker and a high-potential energy supply device thereof, which have a large current cutting capability and can conduct current in both directions without significantly increasing the system cost. The invention belongs to the field of medium- and high-voltage DC electrical appliances. The invention comprises a mechanical isolating switch, a current limiting inductor, a rated current path branch and a fault current cutting branch. Among them, the rated current path branch and the fault current cutting branch are connected in parallel; the rated current path branch comprises a power electronic switch component and an IGBT component connected in series, the power electronic switch component is formed by connecting several groups of thyristor units in series, and the fault current cutting branch comprises several groups of IGBT units in series. The IGBT unit is a full-bridge bidirectional current-conducting topology structure, which can realize bidirectional current flow and double the fault current conducting capacity. The high-potential energy supply device uses three-phase AC power to convert into a high-frequency and high-voltage DC power supply, which is used to drive and supply power for the IGBT module of the all-solid-state DC circuit breaker, greatly reducing the volume of the energy supply device.

Description

Technical Field

[0001] The present invention belongs to the field of medium and high voltage DC electrical appliances, and in particular relates to a medium and high voltage bidirectional all-solid-state DC circuit breaker and a high potential energy supply device thereof. Background Art

[0002] In the field of DC power distribution such as ships, aircraft, DC power grids, and multi-terminal DC power transmission, voltage source rectifier / inverter devices are often used. Today's DC circuit breakers are mainly divided into mechanical DC circuit breakers, all-solid-state DC circuit breakers, and hybrid DC circuit breakers. Mechanical DC circuit breakers use mechanical switches to cut off DC currents, and have high shutoff capabilities, but they need to create an artificial zero-crossing point, and the arc-extinguishing working point is difficult to accurately grasp, and the repeatability is also poor. In addition, the breaking time requires tens of milliseconds, which is limited by the long mechanical stroke and cannot meet the technical requirements of DC power grids. Hybrid DC circuit breakers combine mechanical switches and power electronic devices, and have the advantages of low conduction loss and no arcing, but their structure is complex, the volume is large, and the fault current removal time is several milliseconds, resulting in a large fault current peak, which is difficult to meet the application requirements of some special industries. All-solid-state DC circuit breakers use high-power semiconductor devices to directly break DC currents, with short breaking time and no arcing, but large conduction loss and high cost.

[0003] In the prior art, the defects of all-solid-state DC circuit breakers, such as large on-state loss and high cost, are addressed. A new all-solid-state DC circuit breaker with low on-state loss, fast shutdown speed, good consistency and voltage balancing effect of series power electronic devices, and reliable absorption of shutdown overvoltage and energy is proposed. For example, the patent authorization announcement number is CN104242265B, and the patent name is a kind of all-solid-state DC circuit breaker for DC distribution network. Its main line structure is that the DC circuit breaker is composed of an auxiliary circuit breaker circuit, a main circuit breaker circuit and an energy absorption circuit in parallel. Among them, the auxiliary circuit breaker circuit includes a thyristor switch unit and a modular fully-controlled device switch unit connected in series; the main circuit breaker circuit includes a plurality of press-fit fully-controlled device switch units, lightning arresters and fuses, and a diode bridge structure is adopted to realize bidirectional current flow; the energy absorption circuit includes at least one lightning arrester. The all-solid-state DC circuit breaker formed by the invention has a novel topology structure, comprehensive functions, low conduction loss during normal operation, can quickly detect the current state and effectively identify the fault, can realize the bidirectional current breaking in the event of a fault, has a high current cut-off level, fast fault clearing speed, good overvoltage and energy absorption effect during the shut-off process, effectively limits the fault current rise rate, and reliably protects the main circuit breaker circuit series valve group and auxiliary circuit breaker circuit full control devices. However, in the case of severe high current faults, the fuse must be used to cut off the fault current to protect the valve group devices from damage. Summary of the invention

[0004] In view of the drawback that the prior art cannot cut off large current faults, the present invention provides a medium- and high-voltage bidirectional all-solid-state DC circuit breaker and a high-potential energy supply device thereof that have large current cutting capability and do not significantly increase system costs and can pass current in both directions.

[0005] According to one aspect of the present invention, a medium- and high-voltage bidirectional all-solid-state DC circuit breaker is provided, comprising a mechanical isolating switch, a current limiting inductor, a rated current path branch and a fault current removal branch, wherein the rated current path branch and the fault current removal branch are connected in parallel; the rated current path branch comprises a power electronic switch component and an IGBT component connected in series, wherein the power electronic switch component is formed by a plurality of groups of thyristor units connected in series, wherein each group of thyristor units is formed by a forward thyristor, a DC voltage balancing branch, a dynamic voltage balancing branch and a reverse thyristor connected in parallel; the IGBT component is formed by a plurality of groups of IGBT units connected in parallel; the fault current removal branch is formed by a plurality of groups of IGBT units connected in series; the IGBT unit comprises a full-bridge IGBT module bidirectional current-carrying branch and an energy absorption branch, wherein the full-bridge IGBT module bidirectional current-carrying branch is connected in parallel with the energy absorption branch, and the bridge arm of the IGBT module bidirectional current-carrying branch is an IGBT module, and both ends of the IGBT module are connected with an RCD protection absorption branch and a DC voltage balancing resistor.

[0006] In the above scheme, the mechanical isolating switch is used to isolate the power supply, disconnect the circuit without load current, and has no arc extinguishing ability. The current limiting inductor is used to suppress transient current, and the faster the change rate of the current, the more obvious the suppression effect. The size of its inductance value depends on the requirements of stable operation of the system. Under normal circumstances, the rated current path branch bears all the load current and is always in the on state. Since the on-state voltage drop of the power electronic switch component and the IGBT component is small, the loss of the DC circuit breaker is low, and it will not affect the overall operation efficiency of the power supply system. Once the main circuit is short-circuited or the fault current increases, the series IGBT unit of the fault current removal branch is immediately triggered to turn on, and then the parallel IGBT unit of the rated current path branch enters the off state, and the current begins to transfer to the fault current removal branch. After the thyristor current of the power electronic switch component drops to zero, the power electronic switch component also enters the off state. Due to the characteristics of the thyristor, the power electronic switch component has the ability to withstand high voltage. The DC voltage balancing branch and the dynamic voltage balancing branch of the thyristor unit are connected in parallel with the thyristor, which slows down the rising speed of the voltage across the thyristor and reduces the device loss. After the fault current is transferred to the fault current removal branch, the series IGBT unit of the fault current removal branch enters the off state. Since the current in the main circuit is large, the energy stored in the current limiting inductor is large, and the arc energy cannot disappear immediately. The energy absorption branch of the series IGBT unit of the fault current removal branch begins to absorb and discharge this energy. The IGBT module is an insulated gate bipolar transistor module, and the design of the bidirectional current-passing branch of the full-bridge IGBT module allows the upper and lower groups of IGBT modules to each bear half of the load current. Therefore, the short-circuit fault breaking current capacity is doubled, and it has a large current removal capability. The RCD protection absorption branch connected at both ends of the IGBT module can slow down the voltage rise speed when the IGBT module is turned off, reduce the turn-off loss, and discharge the residual energy in the system more quickly. The DC voltage-equalizing resistor ensures that the voltage drop at both ends of the IGBT module of each IGBT unit is basically the same, and can help discharge the energy.

[0007] Preferably, the IGBT module is a press-fit IGBT module. Compared with the traditional welded IGBT, the press-fit IGBT uses pressure to achieve thermodynamic and electrical connection and ensures double-sided heat dissipation. The power cycling capability of the press-fit IGBT device is very strong, far superior to the welded IGBT module.

[0008] Preferably, the thyristor assembly includes multiple groups of thyristor units. The more thyristor units are connected in series, the stronger the high-voltage resistance of the thyristor assembly. The on-state resistance of the thyristor switch is very small, mΩ level, the withstand voltage is very high, about 8kV, the turn-off time is short, about one hundredth of the mechanical switch, the fault current removal time is shorter, the short-circuit current peak is smaller, the arc extinguishing energy is greatly reduced, the price is low, and the use of the thyristor assembly as the overcurrent cutoff of the circuit breaker will not significantly increase the system cost.

[0009] Preferably, the energy absorption branch is composed of a DC capacitor and a MOV zinc oxide arrester in parallel. When the residual electric energy in the circuit charges the DC capacitor, if the voltage insulation coordination between the two ends of the DC capacitor is normal, the MOV zinc oxide arrester will be activated to quickly discharge the electric energy and protect the IGBT unit from damage.

[0010] Preferably, the RCD protection absorption branch includes a diode, a resistor, and a DC capacitor, wherein the resistor is connected in parallel with the diode and then in series with the DC capacitor. The RCD protection absorption branch can slow down the voltage rise speed when the IGBT module is turned off, thereby reducing the turn-off loss.

[0011] According to another aspect of the present invention, a high-potential energy supply device is provided, comprising a PMW pulse width modulation rectifier circuit, a filter capacitor, a full-bridge inverter circuit, a resonant capacitor component, a magnetic toroid transformer, a full-bridge rectifier diode component, a high-voltage energy storage filter capacitor, a discharge resistor, and a DC voltage converter; the PMW pulse width modulation rectifier circuit, the filter capacitor, and the full-bridge inverter circuit are connected in parallel in sequence; the PMW pulse width modulation rectifier circuit comprises a three-phase half-bridge circuit composed of an inductor and an IGBT module on the AC side; the bridge arm of the full-bridge inverter circuit is an IGBT module; the output end of the full-bridge inverter circuit is connected to the input end of the resonant capacitor component; the output end of the resonant capacitor component is connected to the primary circuit of the magnetic toroid transformer, and the resonant capacitor component and the leakage inductance of the magnetic toroid transformer form an LCC series-parallel resonant circuit. The secondary circuit of the magnetic toroid transformer is connected to the input end of the full-bridge rectifier diode component, the full-bridge rectifier diode component, the high-voltage energy storage filter capacitor, and the discharge resistor are connected in parallel in sequence, and the output end of the discharge resistor is connected to the DC voltage converter.

[0012] In the above scheme, the PMW pulse width modulation rectifier circuit rectifies the three-phase AC into DC, passes through the filter capacitor, and then passes through the full-bridge inverter circuit, resonates through the resonant capacitor component and the leakage inductance of the magnetic ring transformer, and transforms the high-frequency pulse electric energy on the low-voltage side to the high-voltage side. After rectification by the full-bridge rectifier diode component, a stable high-voltage DC voltage is formed, and then converted into the switch drive power required by the IGBT module through the DC voltage converter. The number of the magnetic ring transformer, the full-bridge rectifier diode component, the high-voltage energy storage filter capacitor, the discharge resistor, and the DC voltage converter is consistent with the number of IGBT modules in the all-solid-state DC circuit breaker. The power supply of the device is three-phase AC, which is separated from the DC power supply through the all-solid-state DC circuit breaker, and is well isolated, and will not be affected by the fault current of the all-solid-state DC circuit breaker, ensuring the stability of the control power supply when the fault current of the solid-state DC circuit breaker occurs; the power supplies after each transformer transformation are independent of each other, and the power supplies for the IGBT module of the all-solid-state DC circuit breaker will not affect each other. The frequency and voltage of the current are increased through the resonant capacitor assembly and the magnetic toroidal transformer. Due to the high-frequency operating frequency, the volume of the high-potential energy supply device is greatly reduced. The LCC series-parallel resonant circuit can realize zero-voltage switching or zero-current switching of the IGBT module, reduce switching losses, increase switching frequency, and avoid technical difficulties such as shutdown overvoltage and "false high" bus voltage caused by hard switching circuits. The discharge resistor connected in parallel with the high-voltage energy storage filter capacitor can discharge the power in the capacitor more quickly when the high-potential energy supply device cuts off the power supply, better protecting the circuit and the safety of the staff.

[0013] Preferably, the magnetic toroidal transformer is a nanocrystalline or manganese-zinc ferrite magnetic toroidal transformer. Such magnetic toroidal transformer can suppress low-frequency interference.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The power electronic switches of the rated current path branches of the all-solid-state DC circuit breaker are composed of thyristors. The fault current removal time is shorter, the short-circuit current peak is smaller, and the arc extinguishing energy is greatly reduced. The thyristors are connected in parallel with a DC balancing circuit and a dynamic DC balancing circuit, which further protects the thyristors from damage.

[0016] The design of the bidirectional current-carrying branch of the full-bridge IGBT module in the all-solid-state DC circuit breaker allows the upper and lower groups of IGBT modules to each bear half of the load current, so the short-circuit fault breaking current capacity is doubled. In addition, each full-bridge IGBT module bidirectional current-carrying branch is connected in parallel with a DC capacitor and an MOV zinc oxide lightning arrester, which can absorb the residual electric energy in the line and discharge it quickly. The RCD protection absorption branch connected at both ends of the IGBT module and the resistor with DC voltage balancing and energy discharge can slow down the voltage rise speed when the IGBT module is turned off, reduce the turn-off loss, and further protect the IGBT module from damage.

[0017] The input power of the high-potential function device is a three-phase AC power supply, which is separated from the DC power supply of the all-solid-state DC circuit breaker. It is well isolated and will not be affected by the fault current of the all-solid-state DC circuit breaker, ensuring the stability of the control power supply when the solid-state DC circuit breaker has a fault current. The power supplies after each transformer transformation are independent of each other, and the power supplies for the IGBT modules of the all-solid-state DC circuit breaker will not affect each other.

[0018] Due to the adoption of high-frequency working frequency, the volume of the high-potential energy supply device is greatly reduced.

[0019] The discharge resistor connected in parallel with the high-voltage energy storage filter capacitor in the high-voltage functional device can discharge the electricity in the capacitor more quickly when the high-voltage energy supply device cuts off the power supply, thereby better protecting the circuit and the safety of the staff. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the topological structure diagram of the all-solid-state DC circuit breaker;

[0021] Figure 2 is the topological structure diagram of the thyristor unit;

[0022] Figure 3 The topological structure diagram of the IGBT module, RCD protection absorption branch, and DC voltage balancing resistor;

[0023] Figure 4 This is a topological structure diagram of a power electronic switch assembly according to Embodiment 2;

[0024] Figure 5 Topological diagram of high potential energy supply device.

[0025] Markings in the figure: 1. Mechanical isolating switch; 2. Current limiting inductor; 3. Rated current path branch; 4. Fault current removal branch; 5. Power electronic switch assembly; 51. Thyristor unit; 52. DC equalizing branch; 53. Dynamic equalizing branch; 6. IGBT assembly; 7. IGBT unit; 8. IGBT module; 9. RCD protection absorption branch; 10. DC equalizing resistor; 11. PMW pulse width modulation rectifier circuit; 12. Full-bridge inverter circuit; 13. LCC series-parallel resonant circuit; 14. Full-bridge rectifier diode assembly; 15. Resonant capacitor assembly; 16. Magnetic ring transformer. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings:

[0027] Example 1

[0028] like Figure 1 , Figure 2 , Figure 3As shown, a medium-high voltage bidirectional all-solid-state DC circuit breaker includes a mechanical isolating switch 1, a current limiting inductor 2, a rated current path branch 3 and a fault current removal branch 4, wherein the rated current path branch 3 and the fault current removal branch 4 are connected in parallel; the mechanical isolating switch 1 is used to isolate the power supply, disconnect the circuit without load current, and has no arc extinguishing capability; the current limiting inductor 2 is used to suppress transient current, and the faster the change rate of the current, the more obvious the suppression effect. The magnitude of its inductance value depends on the requirement of stable operation of the system. The rated current path branch 3 includes a power electronic switch component 5 and an IGBT component 6 connected in series, wherein the power electronic switch component 5 is formed by connecting a plurality of groups of thyristor units 51 in series, wherein each group of thyristor units 51 is formed by connecting a forward thyristor, a DC voltage balancing branch 52, a dynamic voltage balancing branch 53 and a reverse thyristor in parallel; the on-state resistance of the thyristor switch is very small, at the mΩ level, the withstand voltage is very high, about 8kV, the turn-off time is short, about one hundredth of the mechanical switch, the fault current removal time is shorter, the short-circuit current peak is smaller, and the arc extinguishing energy is greatly reduced. The IGBT assembly 6 is formed by connecting multiple groups of IGBT units 7 in parallel; the fault current removal branch 4 is formed by connecting multiple groups of IGBT units 7 in series; the IGBT unit 7 includes a full-bridge IGBT module bidirectional flow branch and an energy absorption branch, the bridge arm of the IGBT module bidirectional flow branch is a crimped IGBT module 8, the IGBT module 8 is an insulated gate bipolar transistor module, and the two ends of the IGBT module 8 are connected with an RCD protection absorption branch 9 and a DC voltage equalizing resistor 10. The RCD protection absorption branch 9 includes a diode, a resistor, and a DC capacitor, and the resistor is connected in parallel with the diode and then connected in series with the DC capacitor. It can slow down the voltage rise speed when the IGBT module 8 is turned off, reduce the turn-off loss, and discharge the residual energy in the system more quickly. The DC voltage equalizing resistor 10 ensures that the voltage drop at both ends of the IGBT module 8 of each IGBT unit 7 is basically the same, and can help discharge the energy. The full-bridge IGBT module bidirectional flow branch is connected in parallel with the energy absorption branch, and the energy absorption branch is composed of a DC capacitor and a MOV zinc oxide lightning arrester in parallel. When the residual electric energy in the line charges the DC capacitor, if the voltage insulation coordination between the two ends of the DC capacitor is level, the MOV zinc oxide arrester will operate to quickly discharge the electric energy and protect the IGBT unit 7 from damage. In addition, the design of the bidirectional current-passing branch of the full-bridge IGBT module can make the upper and lower groups of IGBT modules 8 each bear half of the load current, so the short-circuit fault breaking current capacity is doubled.

[0029] Normally, the rated current path branch 3 bears all the load current and is always in the on state. Since the on-state voltage drop of the power electronic switch component 5 and the IGBT component 6 is small, the loss to the DC circuit breaker is low, and the overall operating efficiency of the power supply system will not be affected. Once a short circuit occurs in the main circuit or the fault current increases, the series IGBT unit 7 of the fault current removal branch 4 is immediately triggered to turn on, and then the parallel IGBT unit 7 of the rated current path branch 3 enters the off state, and the current begins to transfer to the fault current removal branch 4. After the thyristor current of the power electronic switch component 5 drops to zero, the power electronic switch component 5 also enters the off state. Due to the characteristics of the thyristor, the power electronic switch component 5 has the ability to withstand high voltage. The DC voltage balancing branch 52 and the dynamic voltage balancing branch 53 of the thyristor unit 51 are connected in parallel with the thyristor, which slows down the rising speed of the voltage across the thyristor and reduces the device loss. After the fault current is transferred to the fault current cut-off branch 4, the series IGBT unit 7 of the fault current cut-off branch 4 enters the shutdown state. Since the current in the main circuit is large and the energy stored in the current limiting inductor 2 is large, the arc energy cannot disappear immediately. The energy absorption branch of the series IGBT unit 7 of the fault current cut-off branch 4 begins to absorb and discharge this energy.

[0030] Example 2

[0031] like Figure 1 , Figure 2 , Figure 3 , Figure 4As shown, a medium-high voltage bidirectional all-solid-state DC circuit breaker includes a mechanical isolating switch 1, a current limiting inductor 2, a rated current path branch 3 and a fault current removal branch 4, wherein the rated current path branch 3 and the fault current removal branch 4 are connected in parallel; the mechanical isolating switch 1 is used to isolate the power supply and disconnect the circuit without load current, and has no arc extinguishing capability; the current limiting inductor 2 is used to suppress transient current, and the faster the change rate of the current, the more obvious the suppression effect. The value of its inductance depends on the requirements for stable operation of the system. The rated current path branch 3 includes a power electronic switch assembly 5 and an IGBT assembly 6 connected in series. The power electronic switch assembly 5 includes multiple groups of thyristors connected in series and two pairs of diodes connected to the rated current path branch 3. Each group of thyristors is connected in parallel with a DC voltage-equalizing branch 52 and a dynamic voltage-equalizing branch 53. Each pair of diodes is connected in reverse series. The input and output ends of the multiple groups of thyristors connected in series are respectively connected between each pair of diodes of the two pairs of diodes. The two pairs of diodes ensure that the current can flow in both directions. Compared with Example 1, the power electronic switch assembly 5 can reduce half of the thyristor devices, saving costs. The on-state resistance of the thyristor switch is very small, mΩ level, with a very high withstand voltage of about 8kV, a short turn-off time of about one hundredth of that of a mechanical switch, a shorter fault current removal time, a smaller short-circuit current peak, and a greatly reduced arc extinguishing energy. The IGBT assembly 6 includes multiple groups of IGBT units 7 connected in parallel; the fault current removal branch 4 includes multiple groups of IGBT units 7 connected in series; the IGBT unit 7 includes a full-bridge IGBT module bidirectional flow branch and an energy absorption branch, the bridge arm of the IGBT module bidirectional flow branch is a crimped IGBT module 8, the IGBT module 8 is an insulated gate bipolar transistor module, and the two ends of the IGBT module 8 are connected with an RCD protection absorption branch 9 and a DC voltage equalizing resistor 10. The RCD protection absorption branch 9 includes a diode, a resistor, and a DC capacitor, and the resistor is connected in parallel with the diode and then connected in series with the DC capacitor. It can slow down the voltage rise speed when the IGBT module 8 is turned off, reduce the turn-off loss, and discharge the residual energy in the system more quickly. The DC voltage equalizing resistor 10 ensures that the voltage drop at both ends of the IGBT module 8 of each IGBT unit 7 is basically the same, and can help discharge the energy. The full-bridge IGBT module bidirectional flow branch is connected in parallel with the energy absorption branch, and the energy absorption branch includes a DC capacitor and a MOV zinc oxide lightning arrester connected in parallel. When the residual electric energy in the line charges the DC capacitor, if the voltage insulation coordination between the two ends of the DC capacitor is level, the MOV zinc oxide arrester will operate to quickly discharge the electric energy and protect the IGBT unit 7 from damage. In addition, the design of the bidirectional current-passing branch of the full-bridge IGBT module can make the upper and lower groups of IGBT modules 8 each bear half of the load current, so the short-circuit fault breaking current capacity is doubled.

[0032] Normally, the rated current path branch 3 bears all the load current and is always in the on state. Since the on-state voltage drop of the power electronic switch component 5 and the IGBT component 6 is small, the loss to the DC circuit breaker is low, and the overall operating efficiency of the power supply system will not be affected. Once a short circuit occurs in the main circuit or the fault current increases, the series IGBT unit 7 of the fault current removal branch 4 is immediately triggered to turn on, and then the parallel IGBT unit 7 of the rated current path branch 3 enters the off state, and the current begins to transfer to the fault current removal branch 4. After the thyristor current of the power electronic switch component 5 drops to zero, the power electronic switch component 5 also enters the off state. Due to the characteristics of the thyristor, the power electronic switch component 5 has the ability to withstand high voltage. The DC voltage balancing branch 52 and the dynamic voltage balancing branch 53 of the thyristor unit 51 are connected in parallel with the thyristor, which slows down the rising speed of the voltage across the thyristor and reduces the device loss. After the fault current is transferred to the fault current cut-off branch 4, the series IGBT unit 7 of the fault current cut-off branch 4 enters the shutdown state. Since the current in the main circuit is large and the energy stored in the current limiting inductor 2 is large, the arc energy cannot disappear immediately. The energy absorption branch of the series IGBT unit 7 of the fault current cut-off branch 4 begins to absorb and discharge this energy.

[0033] Example 3

[0034] like Figure 5As shown, a high-potential energy supply device includes a PMW pulse width modulation rectifier circuit 11, a filter capacitor, a full-bridge inverter circuit 12, a resonant capacitor component 15, a magnetic ring transformer 16, a full-bridge rectifier diode component 14, a high-voltage energy storage filter capacitor, a discharge resistor, and a DC voltage converter; the power supply of the device is three-phase AC power, which is separately supplied from the DC power supply through the all-solid-state DC circuit breaker, and is well isolated and will not be affected by the fault current of the all-solid-state DC circuit breaker, thereby ensuring the stability of the control power supply when a fault current occurs in the solid-state DC circuit breaker. The PMW pulse width modulation rectifier circuit 11, the filter capacitor and the full-bridge inverter circuit 12 are connected in parallel in sequence; the PMW pulse width modulation rectifier circuit 11 includes a three-phase half-bridge circuit composed of an inductor and an IGBT module on the AC side; the bridge arm of the full-bridge inverter circuit 12 is an IGBT module; the output end of the full-bridge inverter circuit 12 is connected to the input end of the resonant capacitor component 15; the output end of the resonant capacitor component 15 is connected to the primary circuit of the magnetic ring transformer 16, and the leakage inductance of the resonant capacitor component 15 and the magnetic ring transformer 16 form an LCC series-parallel resonant circuit 13. The magnetic ring transformer 16 is a nanocrystalline or manganese-zinc ferrite magnetic ring transformer, and this type of magnetic ring transformer 16 can suppress low-frequency interference. The power supplies after each transformer transformation are independent of each other, and the power supplies that supply power to the IGBT module 8 of the all-solid-state DC circuit breaker will not affect each other. The LCC series-parallel resonant circuit 13 increases the frequency and voltage of the current, which can greatly reduce the volume of the high-potential energy supply device. The LCC series-parallel resonant circuit 13 can realize zero voltage switching or zero current switching of the IGBT module, reduce switching losses, increase switching frequency, and avoid technical problems such as shutdown overvoltage and "virtual high" bus voltage caused by hard switching circuits. The secondary circuit of the magnetic ring transformer 16 is connected to the input end of the full-bridge rectifier diode assembly 14. The full-bridge rectifier diode assembly 14, the high-voltage energy storage filter capacitor, and the discharge resistor are connected in parallel in sequence. When the high-potential energy supply device cuts off the power supply, the discharge resistor can discharge the electricity in the capacitor more quickly, better protecting the circuit and the safety of the staff. The output end of the discharge resistor is connected to the DC voltage converter. The output end of the DC voltage converter provides the switch drive power required by the IGBT module 8 of the all-solid-state DC circuit breaker. The number of the magnetic ring transformer 16, the full-bridge rectifier diode assembly 14, the high-voltage energy storage filter capacitor, the discharge resistor, and the DC voltage converter is consistent with the number of IGBT modules in the all-solid-state DC circuit breaker.

[0035] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A medium- and high-voltage bidirectional all-solid-state DC circuit breaker, comprising a mechanical isolating switch (1), a current-limiting inductor (2), a rated current path branch (3) and a fault current removal branch (4), wherein the rated current path branch (3) and the fault current removal branch (4) are connected in parallel; characterized in that: The rated current path branch (3) comprises a power electronic switch component (5) and an IGBT component (6) connected in series, the power electronic switch component (5) being formed by a plurality of groups of thyristor units (51) connected in series, each group of thyristor units (51) being formed by a forward thyristor, a DC voltage balancing branch (52), a dynamic voltage balancing branch (53) and a reverse thyristor connected in parallel; the IGBT component (6) being formed by a plurality of groups of IGBT units (7) connected in parallel; the fault current removal branch (4) being formed by a plurality of groups of IGBT units (7) connected in series; the IGBT unit (7) comprising a full-bridge IGBT module bidirectional current flow branch and an energy absorption branch, the full-bridge IGBT module bidirectional current flow branch being connected in parallel with the energy absorption branch, the bridge arm of the IGBT module bidirectional current flow branch being an IGBT module (8), and the two ends of the IGBT module (8) being connected with an RCD protection absorption branch (9) and a DC voltage balancing resistor (10); The IGBT module (8) is a press-fit IGBT module; The energy absorption branch is composed of a DC capacitor and a MOV zinc oxide arrester connected in parallel; The RCD protection absorption branch (9) comprises a diode, a resistor, and a DC capacitor. The resistor of the RCD protection absorption branch (9) is connected in parallel with the diode and then in series with the DC capacitor.

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