Solid-state AC circuit breaker based on thyristor and control method thereof

Abstract

The present invention discloses a solid-state AC circuit breaker based on a thyristor, and relates to the technical field of circuit breakers. The solid-state AC circuit breaker is mainly divided into a current-carrying path, a current transfer path and an energy absorption circuit, and the current-carrying path is electrically connected to the energy absorption circuit, the current transfer branch and the controller respectively; the controller is electrically connected to the current transfer branch. A power electronic device thyristor and a diode rectifier topology are used in parallel as a current-carrying path, and the current transfer path is composed of a diode rectifier bridge, an absorption capacitor, a discharge resistor, a high-frequency transformer and an inverter. The overvoltage absorption circuit is composed of an overvoltage absorption arrester. The present invention can realize rapid switching on and off of an AC circuit, has a strong breaking capacity, and is low in cost and relatively flexible in control. The thyristor-based solid-state AC circuit breaker control method provided by the present invention has simple operating steps and is easy to control. It has been proven to be very reliable and stable after long-term practical tests.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breakers, and in particular to a thyristor-based solid-state AC circuit breaker and a control method thereof. Background Art

[0002] Circuit breakers can be divided into AC circuit breakers and DC circuit breakers according to the nature of the power supply they interrupt. According to the breaking principle, they can be divided into solid-state circuit breakers based on power electronic devices such as IGBTs, traditional mechanical circuit breakers, and hybrid circuit breakers that combine mechanical switches with power electronic devices.

[0003] Although traditional mechanical circuit breakers have high withstand voltage, good reliability, and low on-state loss, arcs will be generated during the process of breaking the current path, causing wear of the breaking contacts, which is not conducive to maintenance, and the breaking speed is also slow. Therefore, solid-state circuit breakers based on power electronic devices have become a new research trend.

[0004] At present, the breaking capacity of solid-state AC circuit breakers based on thyristors is relatively weak and the control is relatively complex. Summary of the invention

[0005] One of the purposes of the present invention is to provide a solid-state AC circuit breaker based on a thyristor, which can quickly switch on and off the AC circuit, has strong breaking capacity, low cost, and relatively flexible control. To achieve the above purpose, the present invention provides the following solutions:

[0006] A thyristor-based solid-state AC circuit breaker includes a current-carrying path, an energy absorption circuit, a current transfer branch, and a controller;

[0007] The current-carrying path is electrically connected to the energy absorption circuit, the current transfer branch and the controller respectively; the controller is electrically connected to the current transfer branch;

[0008] The current-carrying path is used to provide a current path between the AC power supply and the power-consuming device, and can be controlled on and off by a controller;

[0009] The energy absorption circuit is used to absorb the overvoltage generated during the opening or closing process of the semiconductor power device, and is connected in parallel with the semiconductor power device in the current carrying path;

[0010] The current transfer branch is used to provide the necessary reverse voltage to the current-carrying path when it is necessary to disconnect the current-carrying path so that the current no longer flows through the current-carrying path to achieve the purpose of the current-carrying path; the current transfer branch is also connected in parallel with the semiconductor power device in the current-carrying path;

[0011] The controller is used to control the current transfer branch to generate reverse voltage and the disconnection and recovery operations of the current-carrying path, and the driving signal generated by the controller acts on the current-carrying path and the current transfer branch.

[0012] Preferably, the current-carrying path includes a rectifier bridge composed of diodes connected in parallel with a thyristor, the AC power supply supplies power to the load through the current path of the diode rectifier bridge connected in parallel with the thyristor, and the controller provides a control signal to the thyristor.

[0013] Preferably, the energy absorption circuit is composed of an overvoltage absorption arrester MOV, which is connected in parallel with the current-carrying path and is used to absorb overvoltage occurring when the thyristor is turned on and off.

[0014] Preferably, the current transfer branch includes an absorption capacitor C, a discharge resistor R, a diode rectifier bridge, a transformer Tr and an inverter;

[0015] The discharge resistor R is connected in series with the absorption capacitor C, the diode forms a rectifier bridge in parallel with the discharge resistor R, the two middle points of the rectifier bridge are respectively connected to the two primary taps of the transformer Tr, and the secondary output of the transformer Tr is connected to the inverter; the inverter is provided with power by a battery or a capacitor.

[0016] In order to more flexibly realize the control of the above-mentioned thyristor-based solid-state AC circuit breaker, the present invention also provides a control method of the thyristor-based solid-state AC circuit breaker, comprising the following steps:

[0017] When a short circuit occurs in the AC power supply system or a device needs to be repaired, a trigger command is given to the controller;

[0018] The controller outputs a driving signal of the high-frequency inverter and outputs a fixed high-frequency AC voltage;

[0019] The diode rectifier bridge outputs a cut-off voltage opposite to the conduction direction of the thyristor, turns off the thyristor, disconnects the current path, and the AC path no longer flows through the thyristor, but flows through the discharge resistor and the absorption capacitor in one current direction through the diode rectifier bridge to charge the absorption capacitor;

[0020] The AC voltage output by the high-frequency transformer also charges the absorption capacitor through the diode rectifier bridge;

[0021] The controller stops the inverter's drive signal modulation, and only the AC power of the power supply charges the absorption capacitor.

[0022] When the current-carrying path needs to be reopened to restore power supply, the thyristor is triggered again by the controller to make it conduct. At this time, the voltage on the absorption capacitor will be discharged through the current-carrying path.

[0023] Wait for the next time you need to disconnect the circuit.

[0024] The main advantages of the thyristor-based solid-state AC circuit breaker provided by the present invention are embodied in the following aspects:

[0025] 1. First of all, compared with traditional mechanical AC and DC circuit breakers, solid-state circuit breakers based on power electronic devices and hybrid circuit breakers based on the combination of power electronic devices and mechanical switches have outstanding advantages in action time, arc suppression, maintenance cost, etc.

[0026] 2. The current-carrying path in the first part selects the combination of a diode rectifier bridge and a thyristor. Compared with the fully controlled device IGBT, the research on thyristors is more in-depth, and the withstand voltage effect is better and the cost is lower. At the same time, according to different voltage level applications, several thyristors can be selected in series to improve the overall withstand voltage effect, so it is also suitable for high voltage environments. Since the thyristor series technology is relatively mature, the solid-state AC circuit breaker is more flexible in application and has a lower cost.

[0027] 3. In the current transfer branch, a high-frequency inverter is combined with a high-frequency transformer and a diode rectifier bridge is used to give the thyristor a suitable reverse voltage when the circuit breaker needs to be operated, so it is more convenient to control. At the same time, by setting a reasonable transformer ratio, the ability of the solid-state circuit breaker to shut off the current and restore the current path is optimized, and the breaking speed is also ideal. Compared with other solid-state circuit breakers that use IGBT as the control core, the circuit breaker also has the advantages of small footprint and low technical difficulty.

[0028] The thyristor-based solid-state AC circuit breaker control method provided by the present invention has simple operation steps and is easy to control. Long-term practical tests have proven that it is very reliable and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A structural diagram of a solid-state AC circuit breaker system based on thyristors provided by the present invention;

[0030] Figure 2 The present invention provides a thyristor-based solid-state AC circuit breaker topology. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the implementation mode of the present application clearer, the following will be combined with the implementation mode of the present application. Figure 1~2, the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present application.

[0032] like Figure 1 As shown, a thyristor-based solid-state AC circuit breaker includes a current-carrying path 1, an energy absorption circuit 2, a current transfer branch 3 and a controller 4.

[0033] The current-carrying path 1 is electrically connected to the energy absorption circuit 2 , the current transfer branch 3 and the controller 4 respectively; the controller 4 is electrically connected to the current transfer branch 3 .

[0034] The current-carrying path 1 is used to provide a current path between the AC power supply and the power-consuming device, and can be controlled on and off by the controller 4 .

[0035] The energy absorption circuit 2 is used to absorb the overvoltage generated during the switching on or off of the semiconductor power device, and is connected in parallel with the semiconductor power device in the current-carrying path 1 .

[0036] The current transfer branch 3 is used to provide the necessary reverse voltage to the current carrying path 1 when the current carrying path 1 needs to be disconnected so that the current no longer flows through the current carrying path 1 to achieve the purpose of the current carrying path 1. The current transfer branch 3 is also connected in parallel with the semiconductor power device in the current carrying path 1.

[0037] The controller 4 is used to control the current transfer branch 3 to generate a reverse voltage and to control the disconnection and recovery operations of the current carrying path 1 . The driving signal generated by the controller 4 acts on the current carrying path 1 and the current transfer branch 3 .

[0038] Specifically, Figure 2 As shown, the current-carrying path 1 is formed by connecting the thyristor and the diode rectifier topology in parallel in the power electronic device, that is, the AC power supply supplies power to the load through the current path of the diode rectifier bridge and the thyristor in parallel. The controller 4 provides a control signal to the thyristor. When the thyristor is given an opening signal, the AC voltage can continuously supply the load. When the two ends of the thyristor are subjected to a certain reverse voltage, the thyristor will be turned off, and the AC voltage can no longer supply power to the load. Therefore, the thyristor plays a role in controlling the on and off of the solid-state AC circuit breaker.

[0039] The energy absorption circuit 2 is composed of an overvoltage absorption arrester MOV, which is connected in parallel with the current-carrying path 1 and mainly functions to absorb the overvoltage that occurs when the thyristor is turned on and off.

[0040] The current transfer branch 3 is composed of an absorption capacitor C, a discharge resistor R, a high-frequency diode D5-D8 rectifier bridge, a high-frequency transformer Tr and a high-frequency inverter.

[0041] The current transfer branch 3 is also connected in parallel with the current carrying path 1 and the energy absorption circuit 2. In the current transfer branch 3, the discharge resistor R is connected in series with the absorption capacitor C, and the high-frequency diodes D5-D8 form a rectifier bridge connected in parallel with the discharge resistor R. The two middle points of the rectifier bridge are respectively connected to the two primary taps of the high-frequency transformer Tr, and the secondary output of the high-frequency transformer Tr is connected to the high-frequency inverter. The high-frequency inverter is provided with power by a battery or a capacitor.

[0042] When a short circuit occurs in the AC power supply system or a certain device needs to be repaired, it is necessary to shut down the power supply current path. At this time, the controller 4 triggers the driving signal of the high-frequency inverter, outputs a fixed high-frequency AC voltage, and then outputs a cut-off voltage opposite to the conduction direction of the thyristor through the diode rectifier bridge, so as to achieve the effect of shutting off the thyristor and disconnecting the current path. After disconnection, the AC path no longer flows through the thyristor, but flows through the discharge resistor and the absorption capacitor in a current direction through the diode rectifier bridge. At this time, it can be regarded as a rectification of the AC output voltage, and the absorption capacitor is charged at the same time. On the other hand, the AC voltage output by the high-frequency transformer also charges the capacitor through the diode rectifier bridge. When the modulation of the drive signal of the inverter is stopped, only the AC power supply of the power supply charges the capacitor. When the fault repair is completed and the current-carrying path needs to be turned on again to restore power supply, the thyristor is triggered again to turn it on. At this time, the voltage on the capacitor will be discharged through the current-carrying path. Wait for the next time when the circuit needs to be disconnected.

[0043] The thyristor of the current-carrying path 1 is connected in parallel with the overvoltage absorption arrester MOV in the second part, and the absorption capacitor and the discharge resistor in the current transfer branch of the third part are connected in series and then connected in parallel with the overvoltage absorption arrester MOV in the second part. The diode rectifier bridge is connected in parallel with the discharge resistor, and its input end is the secondary side of the high-frequency transformer Tr, and the primary side is connected to the high-frequency inverter.

[0044] The control of the thyristor-based solid-state AC circuit breaker can be performed by the following method steps, including:

[0045] Step 101: When a short circuit fault occurs in the AC power supply system or a certain device needs to be repaired, a trigger instruction is given to the controller;

[0046] Step 102: The controller outputs a driving signal of the high-frequency inverter, outputting a fixed high-frequency AC voltage;

[0047] Step 103: Outputting a cut-off voltage opposite to the conduction direction of the thyristor through the diode rectifier bridge, turning off the thyristor, disconnecting the current path, and the AC path no longer flows through the thyristor, but flows through the discharge resistor and the absorption capacitor in one current direction through the diode rectifier bridge to charge the absorption capacitor;

[0048] Step 104: The AC voltage output by the high-frequency transformer is also used to charge the absorption capacitor via the diode rectifier bridge;

[0049] Step 105: The controller stops the modulation of the drive signal of the inverter, and at this time, only the AC power of the power supply charges the absorption capacitor;

[0050] Step 106: When the current-carrying path needs to be reopened to restore power supply, the thyristor is triggered again by the controller to be turned on. At this time, the voltage on the absorption capacitor is discharged through the current-carrying path, and then waits for the next time when the circuit needs to be disconnected.

[0051] The main advantages of the thyristor-based solid-state AC circuit breaker provided by the present invention are embodied in the following aspects:

[0052] 1. First of all, compared with traditional mechanical AC and DC circuit breakers, solid-state circuit breakers based on power electronic devices and hybrid circuit breakers based on the combination of power electronic devices and mechanical switches have outstanding advantages in action time, arc suppression, maintenance cost, etc.

[0053] 2. The current-carrying path in the first part selects the combination of a diode rectifier bridge and a thyristor. Compared with the fully controlled device IGBT, the research on thyristors is more in-depth, and the withstand voltage effect is better and the cost is lower. At the same time, according to different voltage level applications, several thyristors can be selected in series to improve the overall withstand voltage effect, so it is also suitable for high voltage environments. Since the thyristor series technology is relatively mature, the solid-state AC circuit breaker is more flexible in application and has a lower cost.

[0054] 3. In the current transfer branch, a high-frequency inverter is combined with a high-frequency transformer and a diode rectifier bridge is used to give the thyristor a suitable reverse voltage when the circuit breaker needs to be operated, so it is more convenient to control. At the same time, by setting a reasonable transformer ratio, the ability of the solid-state circuit breaker to shut off the current and restore the current path is optimized, and the breaking speed is also ideal. Compared with other solid-state circuit breakers that use IGBT as the control core, the circuit breaker also has the advantages of small footprint and low technical difficulty.

[0055] The thyristor-based solid-state AC circuit breaker control method provided by the present invention has simple operation steps and is easy to control. Long-term practical tests have proven that it is very reliable and stable.

Claims

1. A solid-state AC circuit breaker based on a thyristor, characterized in that: It comprises a current-carrying path (1), an energy absorption circuit (2), a current transfer branch (3) and a controller (4); The current-carrying path (1) is electrically connected to the energy absorption circuit (2), the current transfer branch (3) and the controller (4) respectively; the controller (4) is electrically connected to the current transfer branch (3); The current-carrying path (1) is used to provide a current path between the AC power supply and the power-consuming device, and can be controlled on and off by a controller (4); The energy absorption circuit (2) is used to absorb the overvoltage generated during the process of turning on or off the semiconductor power device, and is connected in parallel with the semiconductor power device in the current-carrying path (1); The current transfer branch (3) is used to provide a necessary reverse voltage to the current-carrying path (1) when a disconnection operation is required so that the current no longer flows through the current-carrying path (1) to achieve the purpose of the current-carrying path (1); the current transfer branch (3) is also connected in parallel with the semiconductor power device in the current-carrying path (1); The controller (4) is used to control the current transfer branch (3) to generate a reverse voltage and to control the disconnection and recovery operations of the current carrying path (1). The driving signal generated by the controller (4) acts on the current carrying path (1) and the current transfer branch (3). The current carrying path (1) includes a rectifier bridge formed by a diode connected in parallel with a thyristor, the AC power supply supplies power to the load through the current path formed by the diode rectifier bridge connected in parallel with the thyristor, and the controller (4) provides a control signal to the thyristor. The current transfer branch (3) comprises an absorption capacitor C, a discharge resistor R, diodes (D5-D8), a rectifier bridge, a transformer Tr and an inverter; The discharge resistor R is connected in series with the absorption capacitor C, and the diodes (D5-D8) form a rectifier bridge connected in parallel with the discharge resistor R. The two middle points of the rectifier bridge are respectively connected to the two primary taps of the transformer Tr, and the secondary output of the transformer Tr is connected to the inverter; the inverter is provided with power by a battery or a capacitor; The energy absorption circuit (2) is composed of an overvoltage absorption arrester MOV, which is connected in parallel with the current-carrying path (1) and is used to absorb overvoltage occurring when the thyristor is turned on and off.

2. The control method of the thyristor-based solid-state AC circuit breaker according to claim 1, It is characterized in that The following steps are involved: When a short circuit occurs in the AC power supply system or a device needs to be repaired, a trigger command is given to the controller; The controller outputs a driving signal of the high-frequency inverter and outputs a fixed high-frequency AC voltage; The diode rectifier bridge outputs a cut-off voltage opposite to the conduction direction of the thyristor, turns off the thyristor, disconnects the current path, and the AC path no longer flows through the thyristor, but flows through the discharge resistor and the absorption capacitor in one current direction through the diode rectifier bridge to charge the absorption capacitor; The AC voltage output by the high-frequency transformer also charges the absorption capacitor through the diode rectifier bridge; The controller stops the inverter's drive signal modulation, and only the AC power of the power supply charges the absorption capacitor. When the current-carrying path needs to be reopened to restore power supply, the thyristor is triggered again by the controller to make it conduct. At this time, the voltage on the absorption capacitor will be discharged through the current-carrying path. Wait for the next time you need to disconnect the circuit.

Images