Patent Publication Number: US-2022231499-A1

Title: Fault protection apparatus and photovoltaic power generation system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/141683, filed on Dec. 27, 2021, which claims priority to Chinese Patent Application No. 202110069765.0, filed on Jan. 19, 2021. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This application relates to the field of electric and electronic technologies, and in particular, to a fault protection apparatus and a photovoltaic power generation system. 
     BACKGROUND 
     Fields such as solar power generation, wind power generation, frequency conversion, an uninterruptible power supply (UPS) systems, motor drivers, and new energy vehicles all need an electric energy transducer, also referred to as an inverter, configured to implement conversion from a direct current to an alternating current. A multi-level circuit that can output three or more voltage levels is widely applied and attracts wide attention. In comparison with a two-level circuit, the multi-level circuit that can output three or more voltage levels has advantages, for example, many output levels, a small voltage stress, a small ripple current, and a good harmonic feature. In this way, an output voltage pulse approaches an industrial frequency alternating current voltage, to reduce a volume and a weight of a filter. The multi-level circuit generally uses a semiconductor switch component to implement conversion from a direct current to an alternating current. Atypical three-phase bridge inverter circuit is used as an example. A semiconductor switch transistor of each bridge arm is turned on for a half of a period in a sine period, and bridge arms of the three-phase bridge inverter circuit are alternately turned on and have a conductive angle difference of 120 degrees. An output voltage waveform obtained in this way is approximately a sine wave. 
     In the conventional technologies, a three-level circuit including two direct current voltage sources is widely applied. However, an intermediate node between the two direct current voltage sources in the three-level circuit is directly electrically connected to an intermediate node of a semiconductor switch component. Therefore, when an inverter bridge arm of the semiconductor switch component is faulty, an overvoltage damage is easily caused to the half-bus capacitor. Further, a circuit and a device may be further damaged after the damage is further spread. Consequently, reliability of the circuit is greatly reduced. 
     Therefore, a technical solution needs to be provided for the multi-level circuit, to protect a capacitor bridge arm when a short-circuit fault occurs on the inverter bridge arm, thereby avoiding a circuit failure damage. 
     SUMMARY 
     An objective of this application is to provide a fault protection apparatus and a photovoltaic power generation system, to protect a capacitor bridge arm when a short-circuit fault occurs on an inverter bridge arm, thereby avoiding a circuit failure damage. 
     According to a first aspect, an embodiment of this application provides a photovoltaic power generation system. The photovoltaic power generation system includes a capacitor bridge arm, an inverter bridge arm, and the fault protection apparatus. The capacitor bridge arm includes a positive electrode output port, a negative electrode output port, and a reference output port between the positive electrode output port and the negative electrode output port. The inverter bridge arm includes a positive electrode input port, a negative electrode input port, and a reference input port between the positive electrode input port and the negative electrode input port. The positive electrode input port is connected to the positive electrode output port. The negative electrode input port is connected to the negative electrode output port. The reference input port is connected to the reference output port by using the fault protection apparatus. The fault protection apparatus is turned off based on a magnitude value or a variation of a voltage, or a magnitude value or a variation of a current between the reference input port and the positive electrode input port or the negative electrode input port. 
     In the technical solutions described in the first aspect, a connection relationship between the reference output port and the reference input port may be adjusted through turning on and turning off the fault protection apparatus, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, that the fault protection apparatus is turned off based on the magnitude value or the variation of the voltage between the reference input port and the positive electrode input port or the negative electrode input port includes that when the voltage between the negative electrode input port and the reference input port is less than a first threshold, the fault protection apparatus is turned off; or when the voltage between the positive electrode input port and the reference input port is less than a second threshold, the fault protection apparatus is turned off; or when a decrease rate of the voltage between the negative electrode input port and the reference input port is greater than a third threshold, the fault protection apparatus is turned off; or when a decrease rate of the voltage between the positive electrode input port and the reference input port is greater than a fourth threshold, the fault protection apparatus is turned off. 
     In this way, a connection relationship between the reference output port and the reference input port is adjusted through monitoring the variation of the voltage and controlling the fault protection apparatus to be turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, the fault protection apparatus is further turned off based on a current flowing through the fault protection apparatus. 
     In this way, a connection relationship between the reference output port and the reference input port is adjusted through monitoring the current flowing through the fault protection apparatus and controlling the fault protection apparatus to be turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, the inverter bridge arm further includes at least one semiconductor switch component connected between the reference input port and the positive electrode input port or the negative electrode input port, and the fault protection apparatus is further turned off based on a current flowing through the at least one semiconductor switch component or a voltage applied between a first transmission electrode and a second transmission electrode of the at least one semiconductor switch component. 
     In this way, a connection relationship between the reference output port and the reference input port is adjusted through monitoring a voltage status and a current status of the semiconductor switch component and controlling the fault protection apparatus to be turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, the fault protection apparatus includes a primary circuit breaker, the primary circuit breaker includes a first switch transistor and a second switch transistor, the first switch transistor and the second switch transistor are connected in series in reverse directions between the reference output port and the reference input port, and the fault protection apparatus is turned on and turned off through controlling on/off of the first switch transistor and the second switch transistor. 
     In this way, the fault protection apparatus comprising a circuit break switch is controlled to be turned on and turned off through controlling on/off of the first switch transistor and the second switch transistor. 
     With reference to the first aspect, in an embodiment, the first switch transistor and the second switch transistor are MOSFETs, IGBTs, GTRs, GTOs, HEMTs, MODFETs, 2-DEGFETs, or SDHTs. 
     In this way, various types of switch transistors are used. 
     With reference to the first aspect, in an embodiment, the fault protection apparatus further includes a high impedance component. The high impedance component and the primary circuit breaker are connected in parallel between the reference output port and the reference input port. 
     In this way, a charging/discharging speed of the capacitor bridge arm is slowed down by using the high impedance component. This helps another protection mechanism to react, to improve stability of a system. 
     With reference to the first aspect, in an embodiment, the high impedance component is a thermistor. 
     In this way, a charging/discharging speed of the capacitor bridge arm is slowed down by using the thermistor. This helps another protection mechanism to react, to improve stability of a system. 
     With reference to the first aspect, in an embodiment, the fault protection apparatus further includes a varistor. The varistor and the primary circuit breaker are connected in parallel between the reference output port and the reference input port. 
     In this way, the varistor absorbs energy remaining in the fault protection apparatus in a circuit break process, to prevent an overvoltage damage and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, the fault protection apparatus further includes a high-speed mechanical breaker. The high-speed mechanical breaker, the varistor, and the primary circuit breaker are connected in parallel between the reference output port and the reference input port. The high-speed mechanical breaker is turned on after the first switch transistor and the second switch transistor of the primary circuit breaker are turned on. The high-speed mechanical breaker is turned off before the first switch transistor and the second switch transistor of the primary circuit breaker are turned off. 
     In this way, bypassing processing is performed on the primary circuit breaker through turning on the high-speed mechanical breaker after the switch transistors of the primary circuit breaker are turned on, to reduce a loss through turning on the high-speed mechanical breaker. 
     With reference to the first aspect, in an embodiment, the fault protection apparatus further includes a high-speed mechanical breaker and an auxiliary circuit breaker. The auxiliary circuit breaker includes a third switch transistor and a fourth switch transistor. The third switch transistor and the fourth switch transistor are connected in series in reverse directions, and then are connected in series to the high-speed mechanical breaker between the reference output port and the reference input port. The high-speed mechanical breaker and the auxiliary circuit breaker are connected in series, and then are connected in parallel to the varistor and the primary circuit breaker between the reference output port and the reference input port. The third switch transistor and the fourth switch transistor of the auxiliary circuit breaker and the high-speed mechanical breaker are turned on after the first switch transistor and the second switch transistor of the primary circuit breaker are turned on. The high-speed mechanical breaker is turned off before the first switch transistor and the second switch transistor of the primary circuit breaker are turned off. The third switch transistor and the fourth switch transistor of the auxiliary circuit breaker are turned off before the high-speed mechanical breaker is turned off. 
     In this way, bypassing processing is performed on the primary circuit breaker through turning on the high-speed mechanical breaker and the auxiliary circuit breaker to form a bypass branch after the switch transistors of the primary circuit breaker are turned on, to reduce a loss of a circuit break switch SP. 
     With reference to the first aspect, in an embodiment, the third switch transistor and the fourth switch transistor are MOSFETs, IGBTs, GTRs, GTOs, HEMTs, MODFETs, 2-DEGFETs, or SDHTs. 
     In this way, various types of switch transistors are used. 
     With reference to the first aspect, in an embodiment, the inverter bridge arm includes an ANPC three-level bridge arm. The ANPC three-level bridge arm includes a plurality of semiconductor switch components connected in series between the reference input port and the positive electrode input port, and a plurality of semiconductor switch components connected in series between the reference input port and the negative electrode input port. The fault protection apparatus is further turned off based on a current flowing through each of the plurality of semiconductor switch components or a voltage applied between a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
     In this way, whether a short-circuit fault occurs on the ANPC three-level bridge arm may be determined through monitoring a voltage status and a current status of each of the plurality of semiconductor switch components, and a connection relationship between the reference output port and the reference input port is adjusted in time through controlling the fault protection apparatus to be turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, the inverter bridge arm includes an NPC three-level bridge arm. The NPC three-level bridge arm includes a plurality of semiconductor switch components connected in series between the reference input port and the positive electrode input port, and a plurality of semiconductor switch components connected in series between the reference input port and the negative electrode input port. The fault protection apparatus is further turned off based on a current flowing through each of the plurality of semiconductor switch components or a voltage applied between a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
     In this way, whether a short-circuit fault occurs on the NPC three-level bridge arm may be determined through monitoring a voltage status and a current status of each of the plurality of semiconductor switch components, and a connection relationship between the reference output port and the reference input port is adjusted in time through controlling the fault protection apparatus to be turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, the inverter bridge arm includes a T-type three-level bridge arm. The T-type three-level bridge arm includes a plurality of semiconductor switch components connected in series between the positive electrode input port and the negative electrode input port. The fault protection apparatus is further turned off based on a current flowing through each of the plurality of semiconductor switch components or a voltage applied between a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
     In this way, whether a short-circuit fault occurs on the T-type three-level bridge arm may be determined through monitoring a voltage status and a current status of each of the plurality of semiconductor switch components, and a connection relationship between the reference output port and the reference input port is adjusted in time through controlling the fault protection apparatus to be turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     With reference to the first aspect, in an embodiment, the inverter bridge arm includes a five-level bridge arm. The five-level bridge arm includes a plurality of semiconductor switch components connected in series between the reference input port and the positive electrode input port, and a plurality of semiconductor switch components connected in series between the reference input port and the negative electrode input port. The fault protection apparatus is further turned off based on a current flowing through each of the plurality of semiconductor switch components or a voltage applied between a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
     In this way, whether a short-circuit fault occurs on the five-level bridge arm may be determined through monitoring a voltage status and a current status of each of the plurality of semiconductor switch components, and a connection relationship between the reference output port and the reference input port is adjusted in time through controlling the fault protection apparatus to be turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. 
     According to a second aspect, an embodiment of this application provides a method for controlling a fault protection apparatus. The method is applied to a photovoltaic power generation system. The photovoltaic power generation system includes a capacitor bridge arm, an inverter bridge arm, and the fault protection apparatus. The capacitor bridge arm includes a positive electrode output port, a negative electrode output port, and a reference output port between the positive electrode output port and the negative electrode output port. The inverter bridge arm includes a positive electrode input port, a negative electrode input port, and a reference input port between the positive electrode input port and the negative electrode input port. The positive electrode input port is connected to the positive electrode output port. The negative electrode input port is connected to the negative electrode output port. The reference input port is connected to the reference output port by using the fault protection apparatus. The method includes: controlling the fault protection apparatus to be turned off based on a magnitude value or a variation of a voltage, or a magnitude value or a variation of a current between the reference input port and the positive electrode input port or the negative electrode input port. 
     In the technical solutions described in the second aspect, a connection relationship between the reference output port and the reference input port may be adjusted through turning on and turning off the fault protection apparatus, to avoid an overvoltage damage of a half-bus capacitor and improve reliability of a circuit. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       To describe the technical solutions in embodiments of this application or in the background more clearly, the following describes the accompanying drawings required for describing the embodiments of this application or the background. 
         FIG. 1  is a block diagram of principles of a multi-level circuit including a fault protection apparatus according to an embodiment of this application; 
         FIG. 2  is a block diagram of a structure of a first implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application; 
         FIG. 3  is a block diagram of a structure of a second implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application; 
         FIG. 4  is a block diagram of a structure of a third implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application; 
         FIG. 5  is a block diagram of a structure of a fourth implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application; 
         FIG. 6  is a block diagram of a structure of a fifth implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application; 
         FIG. 7  is a block diagram of principles of an ANPC three-level circuit including a fault protection apparatus according to an embodiment of this application; 
         FIG. 8  is a block diagram of principles of an NPC three-level circuit including a fault protection apparatus according to an embodiment of this application; 
         FIG. 9  is a block diagram of principles of a T-type three-level circuit including a fault protection apparatus according to an embodiment of this application; and 
         FIG. 10  is a block diagram of principles of a five-level circuit including a fault protection apparatus according to an embodiment of this application. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of this application provides a photovoltaic power generation system. The photovoltaic power generation system includes a capacitor bridge arm, an inverter bridge arm, and a fault protection apparatus. The capacitor bridge arm includes a positive electrode output port, a negative electrode output port, and a reference output port between the positive electrode output port and the negative electrode output port. The inverter bridge arm includes a positive electrode input port, a negative electrode input port, and a reference input port between the positive electrode input port and the negative electrode input port. The positive electrode input port is connected to the positive electrode output port. The negative electrode input port is connected to the negative electrode output port. The reference input port is connected to the reference output port by using the fault protection apparatus. The fault protection apparatus is turned off based on a magnitude value or a variation of a voltage, or a magnitude value or a variation of a current between the reference input port and the positive electrode input port or the negative electrode input port. In this way, a connection relationship between the reference output port and the reference input port may be adjusted through turning on and turning off the fault protection apparatus, to avoid an overvoltage damage of a half-bus capacitor and improve reliability of a circuit. 
     This embodiment of this application may be applied to the following application scenarios: solar power generation, wind power generation, a frequency converter, a UPS, a motor driver, a new energy vehicle, or another application scenario in which a multi-level inverter circuit is required. 
     This embodiment of this application may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     To make a person skilled in the art understand the solutions in this application better, the following describes the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. 
       FIG. 1  is a block diagram of principles of a multi-level circuit including a fault protection apparatus according to an embodiment of this application. As shown in  FIG. 1 , the multi-level circuit  100  includes a fault protection apparatus  110 , a capacitor bridge arm  120 , and a multi-level inverter bridge arm  130 . The capacitor bridge arm  120  has three output ports: respectively, a positive electrode output port P, a negative electrode output port N, and a reference output port M. Correspondingly, the multi-level inverter bridge arm  130  has three input ports: respectively, a positive electrode input port P′, a negative electrode input port N′, and a reference input port M′. The positive electrode output port P is connected to the positive electrode input port P′. The negative electrode output port N is connected to the negative electrode input port N′. One end of the fault protection apparatus  110  is connected to the reference output port M, and the other end is connected to the reference input port M′. In this way, a one-to-one connection relationship exists between each output port of the capacitor bridge arm  120  and each input port of the multi-level inverter bridge arm  130 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  110 . It should be understood that a positive electrode and a negative electrode mentioned in this embodiment of this application are merely relative concepts. For ease of description, one port is designated as a positive electrode, and the other port is designated as a negative electrode. This should not be construed as a limitation. 
     Still with reference to  FIG. 1 , the fault protection apparatus  110  includes a circuit break switch SP and a controller  111 . One end of the circuit break switch SP is connected to the reference output port M, and the other end is connected to the reference input port M′. The controller  111  is communicatively connected to the circuit break switch SP, and is configured to control on/off of the circuit break switch SP. When the controller  111  controls the circuit break switch SP to be turned on, the reference output port M is connected to the reference input port M′ by using the circuit break switch SP. When the controller  111  controls the circuit break switch SP to be turned off, the reference output port M cannot be connected to the reference input port M′ due to blocking of the circuit break switch SP. In this way, the connection relationship between the reference output port M and the reference input port M′ may be adjusted by using the controller  111  to control on/off of the circuit break switch SP. A key point of the application is that a circuit breaker protection apparatus, including a circuit break circuit SP or a mechanical bleaker/switch, is connected between a reference port M′ of the capacitor bridge arm and a reference port M of the multi-level inverter bridge arm. A specific structure of the protection apparatus is not critical and should not be the restriction of the present invention. For example, the circuit break switch SP can apply anyone of various common circuit breaker protection implementations and can be with one of traditional structures available in the market. Further details are not described herein again. 
       FIG. 2  is a block diagram of a structure of a first implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application. As shown in  FIG. 2 , the circuit break switch SP includes a primary circuit breaker  212 . The primary circuit breaker  212  includes two semiconductor switch components. Insulated gate bipolar transistors (IGBTs) are used as an example, respectively Q 1  and Q 2 . Herein, Q 1  and Q 2  are connected in series in reverse directions between the reference output port M and the reference input port M′. In other words, an emitter of Q 1  is connected to an emitter of Q 2 , a collector of Q 1  is connected to the reference input port M′, and a collector of Q 2  is connected to the reference output port M. In another implementation, the collector of Q 1  is connected to the collector of Q 2 , the emitter of Q 1  is connected to the reference input port M′, and the emitter of Q 2  is connected to the reference output port M. In these two implementations, locations of Q 1  and Q 2  may also be interchanged. The primary circuit breaker  212  further includes two diodes: T 1  and T 2 . Herein, T 1  and T 2  are respectively in an anti-parallel connection relationship with Q 1  and Q 2 . Specifically, the diode: T 1  corresponds to Q 1 , an anode of T 1  is connected to the emitter of Q 1 , and a cathode of T 1  is connected to the collector of Q 1 ; and the diode: T 2  corresponds to Q 2 , an anode of T 2  is connected to the emitter of Q 2 , and a cathode of T 2  is connected to the collector of Q 2 . In this way, a control mechanism of the circuit break switch SP is implemented by using two insulated gate bipolar transistors: Q 1  and Q 2  connected in series in reverse directions and a pair of diodes: T 1  and T 2  connected in an anti-parallel connection relationship. For example, when the circuit break switch SP receives a control signal indicating to turn on, gate voltages of the IGBTs in the circuit break switch SP can be controlled, to turn on the IGBT and implement a connection between the reference output port M and the reference input port M′. When the circuit break switch SP receives a control signal indicating to turn off, gate voltages of the IGBTs in the circuit break switch SP can be controlled, to turn off the IGBTs and block a connection between the reference output port M and the reference input port M′. By using the control mechanism of the IGBTs, sending the control signal indicating to turn on to the circuit break switch SP may be stopped. Therefore, after the control signal indicating to turn on is not received, the circuit break switch SP may drive the IGBTs to be turned off. In addition, a reverse current/voltage can be suppressed by using the diodes connected to the IGBTs in an anti-parallel connection relationship, to avoid a damage caused due to an excessive reverse current/voltage. 
     Still with reference to  FIG. 2 , it should be understood that the IGBTs shown in  FIG. 2  is merely an example. In some example embodiments, two semiconductor switch components included in the primary circuit breaker  212  are respectively a first switch transistor and a second switch transistor. The first switch transistor and the second switch transistor are connected in series in reverse directions between the reference output port of the capacitor bridge arm and the reference input port of the multi-level inverter bridge arm. The controller controls the circuit break switch to be turned on and turned off through controlling on/off of the first switch transistor and the second switch transistor of the primary circuit breaker. In some example embodiments, the two semiconductor switch components included in the primary circuit breaker  212  may be implemented by using another semiconductor component having similar functions, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET), a giant transistor (GTR), a gate turn-off thyristor (GTO), or another appropriate component. A pair of diodes is correspondingly configured. In some example embodiments, these semiconductor components may also use a high electron mobility transistor (high electron mobility transistor, HEMT), also referred to as a modulation-doped field effect transistor (MODFET), or a two-dimensional electron gas field effect transistor (2-DEGFET), or a selectively-doped heterojunction transistor (SDHT). These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. In other words, the first switch transistor and the second switch transistor are MOSFETs, IGBTs, GTRs, GTOs, HEMTs, MODFETs, 2-DEGFETs, or SDHTs. 
       FIG. 3  is a block diagram of a structure of a second implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application. As shown in  FIG. 3 , the circuit break switch SP includes a primary circuit breaker  312  and a varistor  313 . A structure and a function of the primary circuit breaker  312  are similar to those of the primary circuit breaker  212  shown in  FIG. 2 . Details are not described herein again. The varistor  313  may be based on a metal oxide material. The varistor  313  and the primary circuit breaker  312  are connected in parallel between the reference output port M and the reference input port M′. The varistor  313  has a non-linear volt-ampere feature. The varistor  313  is configured to absorb energy remaining in a circuit break process of the circuit break switch SP, to prevent an overvoltage damage to the primary circuit breaker  312  and improve reliability of a circuit. 
       FIG. 4  is a block diagram of a structure of a third implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application. As shown in  FIG. 4 , the circuit break switch SP includes a primary circuit breaker  412 , a varistor  413 , and a high-speed mechanical breaker  414 . The primary circuit breaker  412 , the varistor  413 , and the high-speed mechanical breaker  414  are all connected in parallel between the reference output port M and the reference input port M′. A structure and a function of the primary circuit breaker  412  are similar to those of the primary circuit breaker  212  shown in  FIG. 2 . Details are not described herein again. A structure and a function of the varistor  413  are similar to those of the varistor  313  shown in  FIG. 3 . Details are not described herein again. The high-speed mechanical breaker  414  is turned on only after IGBTs of the primary circuit breaker  412  are turned on. In other words, after the IGBTs of the primary circuit breaker  412  are turned on, bypassing processing is performed on the primary circuit breaker  412  by using the high-speed mechanical breaker  414  that is turned on, to reduce a loss of the circuit break switch SP by using the high-speed mechanical breaker  414  that is turned on. The high-speed mechanical breaker  414  is turned off before the IGBTs of the primary circuit breaker  412  are turned off, to ensure that the IGBTs of the primary circuit breaker  412  undertake an impact of a current break and avoid an impact caused when the high-speed mechanical breaker  414  undertakes the impact of the current break. 
       FIG. 5  is a block diagram of a structure of a fourth implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application. As shown in  FIG. 5 , the circuit break switch SP includes a primary circuit breaker  512 , a varistor  513 , a high-speed mechanical breaker  514 , and an auxiliary circuit breaker  515 . The high-speed mechanical breaker  514  and the auxiliary circuit breaker  515  are connected in series, and then are connected in parallel to the varistor  513  and the primary circuit breaker  512  between the reference output port M and the reference input port M′. A structure and a function of the primary circuit breaker  512  are similar to those of the primary circuit breaker  212  shown in  FIG. 2 . Details are not described herein again. A structure and a function of the varistor  513  are similar to those of the varistor  313  shown in  FIG. 3 . Details are not described herein again. A structure and a function of the high-speed mechanical breaker  514  are similar to those of the high-speed mechanical breaker  414  shown in  FIG. 4 . Details are not described herein again. The auxiliary circuit breaker  515  includes two semiconductor switch components. IGBTs are used as an example, respectively Q 3  and Q 4 . Herein, Q 3  and Q 4  are connected in series in reverse directions between the reference input port M′ and the high-speed mechanical breaker  514 . In other words, an emitter of Q 3  is connected to an emitter of Q 4 , a collector of Q 3  is connected to the reference input port M′, and a collector of Q 4  is connected to the reference high-speed mechanical breaker  514 . In another implementation, the collector of Q 3  is connected to the collector of Q 4 , the emitter of Q 3  is connected to the reference input port M′, and the emitter of Q 4  is connected to the high-speed mechanical breaker  514 . In these two implementations, locations of Q 3  and Q 4  may also be interchanged. In addition, locations of the high-speed mechanical breaker  514  and the auxiliary circuit breaker  515  may also be interchanged. The auxiliary circuit breaker  515  further includes two diodes: T 3  and T 4 . Herein, T 3  and T 4  are respectively in an anti-parallel connection relationship with Q 3  and Q 4 . Specifically, the diode: T 3  corresponds to Q 3 , an anode of T 3  is connected to the emitter of Q 3 , and a cathode of T 3  is connected to the collector of Q 3 ; the diode: T 4  corresponds to Q 4 , an anode of T 4  is connected to the emitter of Q 4 , and a cathode of T 4  is connected to the collector of Q 4 . The auxiliary circuit breaker  515  and the high-speed mechanical breaker  514  are turned on only after the IGBTs of the primary circuit breaker  512  are turned on. In other words, bypassing processing is performed on the primary circuit breaker  512  through turning on the high-speed mechanical breaker  514  and the auxiliary circuit breaker  515  to form a bypass branch after the IGBTs of the primary circuit breaker  512  are turned on, to reduce a loss of the circuit break switch SP. The high-speed mechanical breaker  514  is turned off before the IGBTs of the primary circuit breaker  512  are turned off. The auxiliary circuit breaker  515  is turned off before the high-speed mechanical breaker  514  is turned off. In this way, based on the operation of turning off the auxiliary circuit breaker  515 , the bypass branch including the high-speed mechanical breaker  514  and the auxiliary circuit breaker  515  is turned off before the IGBTs of the primary circuit breaker  512  are turned off, to ensure that the IGBTs of the primary circuit breaker  512  undertake an impact of a current break and avoid an impact caused when the high-speed mechanical breaker  514  undertakes the impact of the current break. 
     Still with reference to  FIG. 5 , it should be understood that the IGBTs shown in  FIG. 5  are merely an example. In some example embodiments, two semiconductor switch components included in the auxiliary circuit breaker  515  are respectively a third switch transistor and a fourth switch transistor. The third switch transistor and the fourth switch transistor are MOSFETs, IGBTs, GTRs, GTOs, HEMTs, MODFETs, 2-DEGFETs, or SDHTs. 
       FIG. 6  is a block diagram of a structure of a fifth implementation of a circuit break switch SP in the fault protection apparatus shown in  FIG. 1  according to an embodiment of this application. As shown in  FIG. 6 , the circuit break switch SP includes a primary circuit breaker  612  and a thermistor  615 . The thermistor  615  may alternatively be a high impedance component in another type. A structure and a function of the primary circuit breaker  612  are similar to those of the primary circuit breaker  212  shown in  FIG. 2 . Details are not described herein again. The primary circuit breaker  612  and the thermistor  615  are connected in parallel between the reference output port M and the reference input port M′. The thermistor  615  undertakes a short-circuit current after the primary circuit breaker  612  is turned off, and charges and discharges a capacitor bridge arm connected to the circuit break switch SP. In this way, a charging/discharging speed of the capacitor bridge arm is slowed down because the thermistor  615  has a relatively large resistance value and the resistance value further increases at a high temperature. This helps another protection mechanism to react, to improve stability of a system. Likewise, the thermistor  615  may be used in parallel with the second, third, and fourth implementations of the circuit breaker switch SP. Details are not described herein. 
       FIG. 7  is a block diagram of principles of an ANPC three-level circuit including a fault protection apparatus according to an embodiment of this application. As shown in  FIG. 7 , the active neutral point clamped (ANPC) three-level circuit  700  includes a fault protection apparatus  710 , a capacitor bridge arm  720 , and an ANPC three-level bridge arm  730 . The fault protection apparatus  710  includes a circuit break switch SP. The circuit break switch SP shown in  FIG. 7  may correspond to the circuit break switch SP shown in any one of the embodiments in  FIG. 2  to  FIG. 5  or any possible combination or variants of these embodiments. The capacitor bridge arm  720  has three output ports: respectively, a positive electrode output port P, a negative electrode output port N, and a reference output port M. Correspondingly, the ANPC three-level bridge arm  730  has three input ports: respectively, a positive electrode input port P′, a negative electrode input port N′, and a reference input port M′. The ANPC three-level bridge arm  730  further has an external output port O configured to provide an output voltage level for a next-level load or an external network. The positive electrode output port P is connected to the positive electrode input port P′. The negative electrode output port N is connected to the negative electrode input port N′. One end of the fault protection apparatus  710  is connected to the reference output port M, and the other end is connected to the reference input port M′. In this way, a one-to-one connection relationship exists between each output port of the capacitor bridge arm  720  and each input port of the ANPC three-level bridge arm  730 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  710 . It should be understood that a positive electrode and a negative electrode mentioned in this embodiment of this application are merely relative concepts. For ease of description, one port is designated as a positive electrode, and the other port is designated as a negative electrode. This should not be construed as a limitation. 
     Still with reference to  FIG. 7 , the capacitor bridge arm  720  includes two capacitors: C 1  and C 2 . The capacitors: C 1  and C 2  are connected in series between the positive electrode output port P and the negative electrode output port N. An intermediate node between the capacitors: C 1  and C 2  is connected to the reference output port M. The ANPC three-level bridge arm  730  includes a total of six semiconductor switch components, respectively labeled as S 1 , S 2 , S 3 , S 4 , S 5 , and S 6 . It should be understood that each of the semiconductor switch components: S 1 , S 2 , S 3 , S 4 , S 5 , and S 6  included in the ANPC three-level bridge arm  730  is a pair of IGBTs and diodes connected to the IGBTs in an anti-parallel connection relationship. In some example embodiments, these semiconductor switch components may alternatively be implemented by using another semiconductor component having similar functions, for example, a metal-oxide-semiconductor field-effect transistor MOSFET, a giant transistor GTR, a gate turn-off thyristor GTO, or another appropriate component. A pair of diodes is correspondingly configured. In some example embodiments, these semiconductor components may also use a high electron mobility transistor HEMT, also referred to as a modulation-doped field effect transistor MODFET, or a two-dimensional electron gas field effect transistor 2-DEGFET, or a selectively-doped heterojunction transistor SDHT. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     Still with reference to  FIG. 7 , the semiconductor switch components: S 1  and S 2  are connected in series between the positive electrode input port P′ and the reference input port M′, and the semiconductor switch components: S 3  and S 4  are connected in series between the reference input port M′ and the negative electrode input port N′. The semiconductor switch components: S 2  and S 3  are connected. An intermediate node between the semiconductor switch components: S 2  and S 3  is connected to the reference input port M′. The semiconductor switch components: S 5  and S 6  are connected in series, and then are respectively connected to an intermediate node between the semiconductor switch components: S 1  and S 2 , and an intermediate node between the semiconductor switch components: S 3  and S 4 . An intermediate node between the semiconductor switch components: S 5  and S 6  is connected to the external output port O of the ANPC three-level bridge arm  730 . When the semiconductor switch components: S 1  and S 5  are turned on, the external output port O is connected to the positive electrode input port P′ by using a branch including the semiconductor switch components: S 1  and S 5 , and the positive electrode output port P is connected to the positive electrode input port P′. Therefore, a voltage output from the external output port O is a first voltage applied to the positive electrode output port P. When the semiconductor switch components: S 4  and S 6  are turned on, the external output port O is connected to the negative electrode input port N′ by using a branch including the semiconductor switch components: S 4  and S 6 , and the negative electrode output port N is connected to the negative electrode input port N′. Therefore, a voltage output from the external output port O is a second voltage applied to the negative electrode output port N. When the semiconductor switch components: S 2  and S 5  are turned on or when the semiconductor switch components: S 3  and S 6  are turned on, the external output port O is connected to the reference input port M′ by using a branch including the semiconductor switch components: S 2  and S 5  or a branch including the semiconductor switch components: S 3  and S 6 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  710 . Therefore, the voltage output from the external output port O is a third voltage applied to the reference output port M. In this way, through controlling on/off of each semiconductor switch component included in the ANPC three-level bridge arm  730 , the voltage output from the external output port O can be switched among the first voltage applied to the positive electrode output port P, the second voltage applied to the negative electrode output port N, and the third voltage applied to the reference output port M, to implement three-level output. 
     Still with reference to  FIG. 7 , when a short-circuit fault occurs on the semiconductor switch components: S 3  and S 4  at the same time, the negative electrode input port N′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 2  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 . When a symmetrical design is applied to the capacitor bridge arm  720 , the capacitors: C 1  and C 2  each undertake a half of the voltage between the positive electrode output port P and the negative electrode output port N. Therefore, when the voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 , the capacitor C 1  may undertake twice a voltage in a normal design, thereby causing an overvoltage damage. Further, a circuit and a device may be further damaged after the damage is further spread. Consequently, reliability of the circuit is greatly reduced. Similarly, when a short-circuit fault occurs on the semiconductor switch components: S 1  and S 2  at the same time, the positive electrode input port P′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 1  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 2 , thereby causing an overvoltage damage. In this way, the connection relationship between the reference output port M and the reference input port M′ needs to be adjusted through controlling on/off of the circuit break switch SP. Specifically, whether a short-circuit fault occurs on the semiconductor switch component may be determined through monitoring one of the following cases: A voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch components: S 3  and S 4  at the same time. Alternatively, a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch components: S 1  and S 2  at the same time. Alternatively, a decrease rate of a voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch components: S 3  and S 4  at the same time. Alternatively, a decrease rate of a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch components: S 1  and S 2  at the same time. Alternatively, a current flowing from the positive electrode input port P′ to the negative electrode input port N′ and passing through the semiconductor switch component: S 1 , S 2 , S 3 , or S 4  is monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the corresponding semiconductor switch component: S 1 , S 2 , S 3 , or S 4 . Alternatively, a voltage between a collector and an emitter is monitored when the semiconductor switch component: S 1 , S 2 , S 3 , or S 4  is turned on. When the voltage is greater than a specific threshold, it is determined that a short-circuit fault occurs on the corresponding semiconductor switch component: S 1 , S 2 , S 3 , or S 4 . In this way, whether a short-circuit fault occurs on the ANPC three-level bridge arm  730  may be determined through monitoring the foregoing cases, for example, monitoring a voltage and a current of a specific semiconductor switch component, and a connection relationship between the reference output port M and the reference input port M′ is adjusted in time through controlling on/off of the circuit break switch SP, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. In addition, a current flowing through the circuit break switch SP may also be monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the ANPC three-level bridge arm  730 . 
     Still with reference to  FIG. 7 , the ANPC three-level circuit  700  may include a plurality of ANPC three-level bridge arms  730 . Each ANPC three-level bridge arm  730  has the structure shown in  FIG. 7 . Each ANPC three-level bridge arm  730  has three input ports. Input ports of each of the plurality of ANPC three-level bridge arms  730  are connected in parallel to a corresponding positive electrode input port P′, a corresponding negative electrode input port N′, and a corresponding reference input port M′ shown in  FIG. 7 . Therefore, a parallel connection relationship exists among the plurality of ANPC three-level bridge arms  730 . When the plurality of ANPC three-level bridge arms  730  all work normally, the circuit break switch SP of the fault protection apparatus  710  is turned on. When the short-circuit fault occurs on any one of the plurality of ANPC three-level bridge arms  730 , the circuit break switch SP of the fault protection apparatus  710  is turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of the circuit. Whether the short-circuit fault occurs on any one of the plurality of ANPC three-level bridge arms  730  may be determined through monitoring whether one of the foregoing cases occurs on each of the ANPC three-level bridge arms  730 . 
     It should be understood that a controller  711  included in the fault protection apparatus  710  is communicatively connected to the circuit break switch SP, and is configured to control on/off of the circuit break switch SP. The controller  711  may include a corresponding circuit and component to monitor the foregoing cases of the short-circuit fault, or may receive an instruction from the outside by using an interface circuit. In some example embodiments, the controller  711  may be provided separately from the fault protection apparatus  710 , that is, provided as a separate component. In addition to the foregoing cases, another technical means may be further used to determine whether the short-circuit fault occurs on the semiconductor switch component. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     It should be understood that the IGBTs is used as an example for the plurality of semiconductor switch components included in the ANPC three-level bridge arm  730  shown in  FIG. 7 .  FIG. 7  shows examples of a collector and an emitter of each of these semiconductor switch components. When these semiconductor switch components use a semiconductor switch component in another type, for example, a MOSFET, the collector and the emitter are correspondingly replaced with a drain and a source. Therefore, the collector and the emitter shown in  FIG. 7  should be understood as example representations of a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
       FIG. 8  is a block diagram of principles of an NPC three-level circuit including a fault protection apparatus according to an embodiment of this application. As shown in  FIG. 8 , the neutral point clamped (NPC) three-level circuit  800  includes a fault protection apparatus  810 , a capacitor bridge arm  820 , and an NPC three-level bridge arm  830 . The fault protection apparatus  810  includes a circuit break switch SP. The circuit break switch SP shown in  FIG. 8  may correspond to the circuit break switch SP shown in any one of the embodiments in  FIG. 2  to  FIG. 5  or any possible combination or variants of these embodiments. The capacitor bridge arm  820  has three output ports: respectively, a positive electrode output port P, a negative electrode output port N, and a reference output port M. Correspondingly, the NPC three-level bridge arm  830  has three input ports: respectively, a positive electrode input port P′, a negative electrode input port N′, and a reference input port M′. The NPC three-level bridge arm  830  further has an external output port O configured to provide an output voltage level for a next-level load or an external network. The positive electrode output port P is connected to the positive electrode input port P′. The negative electrode output port N is connected to the negative electrode input port N′. One end of the fault protection apparatus  810  is connected to the reference output port M, and the other end is connected to the reference input port M′. In this way, a one-to-one connection relationship exists between each output port of the capacitor bridge arm  820  and each input port of the NPC three-level bridge arm  830 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  810 . It should be understood that a positive electrode and a negative electrode mentioned in this embodiment of this application are merely relative concepts. For ease of description, one port is designated as a positive electrode, and the other port is designated as a negative electrode. This should not be construed as a limitation. 
     Still with reference to  FIG. 8 , the capacitor bridge arm  820  includes two capacitors: C 1  and C 2 . The capacitors: C 1  and C 2  are connected in series between the positive electrode output port P and the negative electrode output port N. An intermediate node between the capacitors: C 1  and C 2  is connected to the reference output port M. The NPC three-level bridge arm  830  includes a total of six semiconductor components, respectively labeled as S 1 , D 2 , D 3 , S 4 , S 5 , and S 6 . The semiconductor components: S 1 , S 4 , S 5 , and S 6  are semiconductor switch components, and the semiconductor components: D 2  and D 3  are diodes. It should be understood that each of the semiconductor switch components: S 1 , S 4 , S 5 , and S 6  included in the NPC three-level bridge arm  830  is a pair of IGBTs and diodes connected to the IGBTs in an anti-parallel connection relationship. In some example embodiments, these semiconductor switch components may alternatively be implemented by using another semiconductor component having similar functions, for example, a MOSFET, a GTR, a GTO, or another appropriate component. A pair of diodes is correspondingly configured. In some example embodiments, these semiconductor components may further use a HEMT, also referred to as a MODFET, or a 2-DEGFET, or an SDHT. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     Still with reference to  FIG. 8 , the semiconductor switch component: S 1  and D 2  are connected in series between the positive electrode input port P′ and the reference input port M′, and the semiconductor switch component: S 4  and D 3  are connected in series between the reference input port M′ and the negative electrode input port N′. The semiconductor components: D 2  and D 3  are connected. An intermediate node between the semiconductor switch components: D 2  and D 3  is connected to the reference input port M′. The semiconductor switch components: S 5  and S 6  are connected in series, and then are respectively connected to an intermediate node between the semiconductor switch component: S 1  and D 2 , and an intermediate node between the semiconductor switch component: S 4  and D 3 . An intermediate node between the semiconductor switch components: S 5  and S 6  is connected to the external output port O of the NPC three-level bridge arm  830 . An anode of the diode: D 2  is connected to the reference input port M′, and a cathode is connected to an emitter of the semiconductor switch component: S 1 . A cathode of the diode: D 3  is connected to the reference input port M′, and an anode is connected to an emitter of the semiconductor switch component: S 4 . The anode of the diode: D 2  is connected to the cathode of the diode: D 3 . When the semiconductor switch components: S 1  and S 5  are turned on, the external output port O is connected to the positive electrode input port P′ by using a branch including the semiconductor switch components: S 1  and S 5 , and the positive electrode output port P is connected to the positive electrode input port P′. Therefore, a voltage output from the external output port O is a first voltage applied to the positive electrode output port P. When the semiconductor switch components: S 4  and S 6  are turned on, the external output port O is connected to the negative electrode input port N′ by using a branch including the semiconductor switch components: S 4  and S 6 , and the negative electrode output port N is connected to the negative electrode input port N′. Therefore, a voltage output from the external output port O is a second voltage applied to the negative electrode output port N. When the semiconductor switch component: S 5  and D 2  are turned on or when the semiconductor switch component: S 6  and D 3  are turned on, the external output port O is connected to the reference input port M′ by using a branch including the semiconductor switch component: S 5  and D 2  or a branch including the semiconductor switch component: S 6  and D 3 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  810 . Therefore, the voltage output from the external output port O is a third voltage applied to the reference output port M. In this way, through controlling on/off of each semiconductor switch component included in the NPC three-level bridge arm  830 , the voltage output from the external output port O can be switched among the first voltage applied to the positive electrode output port P, the second voltage applied to the negative electrode output port N, and the third voltage applied to the reference output port M, to implement three-level output. 
     Still with reference to  FIG. 8 , when a short-circuit fault occurs on the semiconductor switch component: S 4  and D 3  at the same time, the negative electrode input port N′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 2  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 . When a symmetrical design is applied to the capacitor bridge arm  820 , the capacitors: C 1  and C 2  each undertake a half of the voltage between the positive electrode output port P and the negative electrode output port N. Therefore, when the voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 , the capacitor C 1  may undertake twice a voltage in a normal design, thereby causing an overvoltage damage. Further, a circuit and a device may be further damaged after the damage is further spread. Consequently, reliability of the circuit is greatly reduced. Similarly, when a short-circuit fault occurs on the semiconductor switch component: S 1  and D 2  at the same time, the positive electrode input port P′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 1  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 2 , thereby causing an overvoltage damage. In this way, the connection relationship between the reference output port M and the reference input port M′ needs to be adjusted through controlling on/off of the circuit break switch SP. Specifically, whether a short-circuit fault occurs on the semiconductor switch component may be determined through monitoring one of the following cases: A voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch component: S 4  and D 3  at the same time. Alternatively, a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch component: S 1  and D 2  at the same time. Alternatively, a decrease rate of a voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch component: S 4  and D 3  at the same time. Alternatively, a decrease rate of a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch component: S 1  and D 2  at the same time. Alternatively, a current flowing from the positive electrode input port P′ to the negative electrode input port N′ and passing through the semiconductor switch component: S 1  or S 4 , or D 2 , or D 3  is monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the corresponding semiconductor switch component: S 1  or S 4 , or D 2 , or D 3 . Alternatively, a voltage between a collector and an emitter is monitored when the semiconductor switch component: S 1  or S 4  is turned on. When the voltage is greater than a specific threshold, it is determined that a short-circuit fault occurs on the corresponding semiconductor switch component: S 1  or S 4 . In this way, whether a short-circuit fault occurs on the NPC three-level bridge arm  830  may be determined through monitoring the foregoing cases, for example, monitoring a voltage and a current of a specific semiconductor switch component, and a connection relationship between the reference output port M and the reference input port M′ is adjusted in time through controlling on/off of the circuit break switch SP, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. In addition, a current flowing through the circuit break switch SP may also be monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the NPC three-level bridge arm  830 . 
     Still with reference to  FIG. 8 , the NPC three-level circuit  800  may include a plurality of NPC three-level bridge arms  830 . Each NPC three-level bridge arm  830  has the structure shown in  FIG. 8 . Each NPC three-level bridge arm  830  has three input ports. Input ports of each of the plurality of NPC three-level bridge arms  830  are connected in parallel to a corresponding positive electrode input port P′, a corresponding negative electrode input port N′, and a corresponding reference input port M′ shown in  FIG. 8 . Therefore, a parallel connection relationship exists among the plurality of NPC three-level bridge arms  830 . When the plurality of NPC three-level bridge arms  830  all work normally, the circuit break switch SP of the fault protection apparatus  810  is turned on. When the short-circuit fault occurs on any one of the plurality of NPC three-level bridge arms  830 , the circuit break switch SP of the fault protection apparatus  810  is turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of the circuit. Whether the short-circuit fault occurs on any one of the plurality of NPC three-level bridge arms  830  may be determined through monitoring whether one of the foregoing cases occurs on each of the NPC three-level bridge arms  830 . 
     It should be understood that a controller  811  included in the fault protection apparatus  810  is communicatively connected to the circuit break switch SP, and is configured to control on/off of the circuit break switch SP. The controller  811  may include a corresponding circuit and component to monitor the foregoing cases of the short-circuit fault, or may receive an instruction from the outside by using an interface circuit. In some example embodiments, the controller  811  may be provided separately from the fault protection apparatus  810 , that is, provided as a separate component. In addition to the foregoing cases, another technical means may be further used to determine whether the short-circuit fault occurs on the semiconductor switch component. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     It should be understood that the IGBTs are used as an example for the plurality of semiconductor switch components included in the NPC three-level bridge arm  830  shown in  FIG. 8 .  FIG. 8  shows examples of a collector and an emitter of each of these semiconductor switch components. When these semiconductor switch components use a semiconductor switch component in another type, for example, a MOSFET, the collector and the emitter are correspondingly replaced with a drain and a source. Therefore, the collector and the emitter shown in  FIG. 8  should be understood as example representations of a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
       FIG. 9  is a block diagram of principles of a T-type three-level circuit including a fault protection apparatus according to an embodiment of this application. As shown in  FIG. 9 , the T-type three-level circuit  900  includes a fault protection apparatus  910 , a capacitor bridge arm  920 , and a T-type three-level bridge arm  930 . The fault protection apparatus  910  includes a circuit break switch SP. The circuit break switch SP shown in  FIG. 9  may correspond to the circuit break switch SP shown in any one of the embodiments in  FIG. 2  to  FIG. 5  or any possible combination or variants of these embodiments. The capacitor bridge arm  920  has three output ports: respectively, a positive electrode output port P, a negative electrode output port N, and a reference output port M. Correspondingly, the T-type three-level bridge arm  930  has three input ports: respectively, a positive electrode input port P′, a negative electrode input port N′, and a reference input port M′. The T-type three-level bridge arm  930  further has an external output port O configured to provide an output voltage level for a next-level load or an external network. The positive electrode output port P is connected to the positive electrode input port P′. The negative electrode output port N is connected to the negative electrode input port N′. One end of the fault protection apparatus  910  is connected to the reference output port M, and the other end is connected to the reference input port M′. In this way, a one-to-one connection relationship exists between each output port of the capacitor bridge arm  920  and each input port of the T-type three-level bridge arm  930 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  910 . It should be understood that a positive electrode and a negative electrode mentioned in this embodiment of this application are merely relative concepts. For ease of description, one port is designated as a positive electrode, and the other port is designated as a negative electrode. This should not be construed as a limitation. 
     Still with reference to  FIG. 9 , the capacitor bridge arm  920  includes two capacitors: C 1  and C 2 . The capacitors: C 1  and C 2  are connected in series between the positive electrode output port P and the negative electrode output port N. An intermediate node between the capacitors: C 1  and C 2  is connected to the reference output port M. The T-type three-level bridge arm  930  includes a total of four semiconductor switch components, respectively labeled as S 1 , S 2 , S 3 , and S 4 . It should be understood that each of the semiconductor switch components: S 1 , S 2 , S 3 , and S 4  included in the T-type three-level bridge arm  930  is a pair of IGBTs and diodes connected to the IGBTs in an anti-parallel connection relationship. In some example embodiments, these semiconductor switch components may alternatively be implemented by using another semiconductor component having similar functions, for example, a MOSFET, a GTR, a GTO, or another appropriate component. A pair of diodes is correspondingly configured. In some example embodiments, these semiconductor components may further use a HEMT, also referred to as a MODFET, or a 2-DEGFET, or an SDHT. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     Still with reference to  FIG. 9 , the semiconductor switch components: S 1  and S 2  are connected in series between the positive electrode input port P′ and the negative electrode input port N′, and an intermediate node between the semiconductor switch components: S 1  and S 2  is connected to the external output port O. The semiconductor switch components: S 3  and S 4  are connected in series between the reference input port M′ and the external output port O. The semiconductor switch components: S 3  and S 4  are connected in series in reverse directions between the reference input port M′ and the external output port O. In other words, an emitter of S 3  is connected to an emitter of S 4 , a collector of S 3  is connected to the reference input port M′, and a collector of S 4  is connected to the external output port O. In another implementation, locations of S 3  and S 4  may also be interchanged, provided that the emitters of S 3  and S 4  are connected to each other, the collector of one of S 3  and S 4  is connected to the reference input port M′, and the collector of the other one is connected to the external output port O. When the semiconductor switch component: Si is turned on, the external output port O is connected to the positive electrode input port P′ by using a branch including the semiconductor switch component: S 1 , and the positive electrode output port P is connected to the positive electrode input port P′. Therefore, a voltage output from the external output port O is a first voltage applied to the positive electrode output port P. When the semiconductor switch component: S 2  is turned on, the external output port O is connected to the negative electrode input port N′ by using a branch including the semiconductor switch component: S 2 , and the negative electrode output port N is connected to the negative electrode input port N′. Therefore, a voltage output from the external output port O is a second voltage applied to the negative electrode output port N. When the semiconductor switch components: S 3  and S 4  are turned on, the external output port O is connected to the reference input port M′ by using a branch including the semiconductor switch components: S 3  and S 4 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  910 . Therefore, a voltage output from the external output port O is a third voltage applied to the reference output port M. In this way, through controlling on/off of each semiconductor switch component included in the T-type three-level bridge arm  930 , the voltage output from the external output port O can be switched among the first voltage applied to the positive electrode output port P, the second voltage applied to the negative electrode output port N, and the third voltage applied to the reference output port M, to implement three-level output. 
     Still with reference to  FIG. 9 , when a short-circuit fault occurs on the semiconductor switch components: S 2 , S 3 , and S 4  at the same time, the negative electrode input port N′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 2  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 . When a symmetrical design is applied to the capacitor bridge arm  920 , the capacitors: C 1  and C 2  each undertake a half of the voltage between the positive electrode output port P and the negative electrode output port N. Therefore, when the voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 , the capacitor C 1  may undertake twice a voltage in a normal design, thereby causing an overvoltage damage. Further, a circuit and a device may be further damaged after the damage is further spread. Consequently, reliability of the circuit is greatly reduced. Similarly, when a short-circuit fault occurs on the semiconductor switch components: S 1 , S 3 , and S 4  at the same time, the positive electrode input port P′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 1  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 2 , thereby causing an overvoltage damage. In this way, the connection relationship between the reference output port M and the reference input port M′ needs to be adjusted through controlling on/off of the circuit break switch SP. Specifically, whether a short-circuit fault occurs on the semiconductor switch component may be determined through monitoring one of the following cases: A voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch components: S 2 , S 3 , and S 4  at the same time. Alternatively, a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch components: S 1 , S 3 , and S 4  at the same time. Alternatively, a decrease rate of a voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch components: S 2 , S 3 , and S 4  at the same time. Alternatively, a decrease rate of a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch components: S 1 , S 3 , and S 4  at the same time. Alternatively, a current flowing from the positive electrode input port P′ to the negative electrode input port N′ and passing through the semiconductor switch component: S 1  or S 2  is monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the corresponding semiconductor switch component: S 1  or S 2 . Alternatively, a voltage between a collector and an emitter is monitored when the semiconductor switch component: S 1 , S 2 , S 3 , or S 4  is turned on. When the voltage is greater than a specific threshold, it is determined that a short-circuit fault occurs on the corresponding semiconductor switch component: S 1 , S 2 , S 3 , or S 4 . In this way, whether a short-circuit fault occurs on the T-type three-level bridge arm  930  may be determined through monitoring the foregoing cases, for example, monitoring a voltage and a current of a specific semiconductor switch component, and a connection relationship between the reference output port M and the reference input port M′ is adjusted in time through controlling on/off of the circuit break switch SP, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. In addition, a current flowing through the circuit break switch SP may also be monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the T-type three-level bridge arm  930 . 
     Still with reference to  FIG. 9 , the T-type three-level circuit  900  may include a plurality of T-type three-level bridge arms  930 . Each T-type three-level bridge arm  930  has the structure shown in  FIG. 9 . Each T-type three-level bridge arm  930  has three input ports. Input ports of each of the plurality of T-type three-level bridge arms  930  are connected in parallel to a corresponding positive electrode input port P′, a corresponding negative electrode input port N′, and a corresponding reference input port M′ shown in  FIG. 9 . Therefore, a parallel connection relationship exists among the plurality of T-type three-level bridge arms  930 . When the plurality of T-type three-level bridge arms  930  all work normally, the circuit break switch SP of the fault protection apparatus  910  is turned on. When the short-circuit fault occurs on any one of the plurality of T-type three-level bridge arms  930 , the circuit break switch SP of the fault protection apparatus  910  is turned off, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of the circuit. Whether the short-circuit fault occurs on any one of the plurality of T-type three-level bridge arms  930  may be determined through monitoring whether one of the foregoing cases occurs on each of the T-type three-level bridge arms  930 . 
     It should be understood that a controller  911  included in the fault protection apparatus  910  is communicatively connected to the circuit break switch SP, and is configured to control on/off of the circuit break switch SP. The controller  911  may include a corresponding circuit and component to monitor the foregoing cases of the short-circuit fault, or may receive an instruction from the outside by using an interface circuit. In some example embodiments, the controller  911  may be provided separately from the fault protection apparatus  910 , that is, provided as a separate component. In addition to the foregoing cases, another technical means may be further used to determine whether the short-circuit fault occurs on the semiconductor switch component. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     It should be understood that the IGBTs are used as an example for the plurality of semiconductor switch components included in the T-type three-level bridge arm  930  shown in  FIG. 9 .  FIG. 9  shows examples of a collector and an emitter of each of these semiconductor switch components. When these semiconductor switch components use a semiconductor switch component in another type, for example, a MOSFET, the collector and the emitter are correspondingly replaced with a drain and a source. Therefore, the collector and the emitter shown in  FIG. 9  should be understood as example representations of a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
       FIG. 10  is a block diagram of principles of a five-level circuit including a fault protection apparatus according to an embodiment of this application. As shown in  FIG. 10 , the five-level circuit  1000  includes a fault protection apparatus  1010 , a capacitor bridge arm  1020 , and a five-level bridge arm  1030 . The fault protection apparatus  1010  includes a circuit break switch SP. The circuit break switch SP shown in  FIG. 10  may correspond to the circuit break switch SP shown in any one of the embodiments in  FIG. 2  to  FIG. 5  or any possible combination or variants of these embodiments. The capacitor bridge arm  1020  has three output ports: respectively, a positive electrode output port P, a negative electrode output port N, and a reference output port M. Correspondingly, the five-level bridge arm  1030  has three input ports: respectively, a positive electrode input port P′, a negative electrode input port N′, and a reference input port M′. The five-level bridge arm  1030  further has an external output port O configured to provide an output voltage level for a next-level load or an external network. The positive electrode output port P is connected to the positive electrode input port P′. The negative electrode output port N is connected to the negative electrode input port N′. One end of the fault protection apparatus  1010  is connected to the reference output port M, and the other end is connected to the reference input port M′. In this way, a one-to-one connection relationship exists between each output port of the capacitor bridge arm  1020  and each input port of the five-level bridge arm  1030 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  1010 . It should be understood that a positive electrode and a negative electrode mentioned in this embodiment of this application are merely relative concepts. For ease of description, one port is designated as a positive electrode, and the other port is designated as a negative electrode. This should not be construed as a limitation. 
     Still with reference to  FIG. 10 , the capacitor bridge arm  1020  includes two capacitors: C 1  and C 2 . The capacitors: C 1  and C 2  are connected in series between the positive electrode output port P and the negative electrode output port N. An intermediate node between the capacitors: C 1  and C 2  is connected to the reference output port M. The five-level bridge arm  1030  includes a total of eight semiconductor switch components, respectively labeled as S 1 , S 2 , S 3 , S 4 , S 5 , S 6 , S 7 , and S 8 . It should be understood that each of the semiconductor switch components: S 1 , S 2 , S 3 , S 4 , S 5 , S 6 , S 7 , and S 8  included in the five-level bridge arm  1030  is a pair of IGBTs and diodes connected to the IGBTs in an anti-parallel connection relationship. In some example embodiments, these semiconductor switch components may alternatively be implemented by using another semiconductor component having similar functions, for example, a MOSFET, a GTR, a GTO, or another appropriate component. A pair of diodes is correspondingly configured. In some example embodiments, these semiconductor components may further use a HEMT, also referred to as a MODFET, or a 2-DEGFET, or an SDHT. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     Still with reference to  FIG. 10 , the semiconductor switch components: S 1  and S 2  are connected in series between the positive electrode input port P′ and the reference input port M′, and the semiconductor switch components: S 3  and S 4  are connected in series between the reference input port M′ and the negative electrode input port N′. The semiconductor switch components: S 2  and S 3  are connected. An intermediate node between the semiconductor switch components: S 2  and S 3  is connected to the reference input port M′. The semiconductor switch components: S 5  and S 7  are connected in series, and then are respectively connected to an intermediate node between the semiconductor switch components: S 1  and S 2 , and the external output port O of the five-level bridge arm  1030 . The semiconductor switch components: S 6  and S 8  are connected in series, and then are respectively connected to an intermediate node between the semiconductor switch components: S 3  and S 4 , and the external output port O of the five-level bridge arm  1030 . The semiconductor switch components: S 7  and S 8  are connected. An intermediate node between the semiconductor switch components: S 7  and S 8  is connected to the external output port O of the five-level bridge arm  1030 . The semiconductor switch components: S 1 , S 2 , S 3 , and S 4  are connected in series between the positive electrode input port P′ and the negative electrode input port N′. The semiconductor switch components: S 5 , S 7 , S 8 , and S 6  are connected in series between the intermediate node between the semiconductor switch components: S 1  and S 2 , and the intermediate node between the semiconductor switch components: S 3  and S 4 . The five-level bridge arm  1030  further includes two capacitors: Ca and Cb. One end of the capacitor: Ca is connected to an intermediate node between the semiconductor switch components: S 2  and S 5 , and the other end is connected to an intermediate node between the semiconductor switch components: S 3  and S 6 . One end of the capacitor: Cb is connected to an intermediate node between the semiconductor switch components: S 5  and S 7 , and the other end is connected to an intermediate node between the semiconductor switch components: S 6  and S 8 . When the semiconductor switch components: S 1 , S 5 , and S 7  are turned on, the external output port O is connected to the positive electrode input port P′ by using a branch including the semiconductor switch components: S 1 , S 5 , and S 7 , and the positive electrode output port P is connected to the positive electrode input port P′. Therefore, a voltage output from the external output port O is a first voltage applied to the positive electrode output port P. When the semiconductor switch components: S 4 , S 6 , and S 8  are turned on, the external output port O is connected to the negative electrode input port N′ by using a branch including the semiconductor switch components: S 4 , S 6 , and S 8 , and the negative electrode output port N is connected to the negative electrode input port N′. Therefore, a voltage output from the external output port O is a second voltage applied to the negative electrode output port N. When the semiconductor switch components: S 2 , S 5 , and S 7  are turned on or when the semiconductor switch components: S 3 , S 6 , and S 8  are turned on, the external output port O is connected to the reference input port M′ by using a branch including the semiconductor switch components: S 2 , S 5 , and S 7  or a branch including the semiconductor switch components: S 3 , S 6 , and S 8 , and the reference output port M is indirectly connected to the reference input port M′ by using the fault protection apparatus  1010 . Therefore, the voltage output from the external output port O is a third voltage applied to the reference output port M. In this way, through controlling on/off of each semiconductor switch component included in the five-level bridge arm  1030 , the voltage output from the external output port O can be switched among the first voltage applied to the positive electrode output port P, the second voltage applied to the negative electrode output port N, and the third voltage applied to the reference output port M, to implement three-level output. In addition, by using a voltage division branch that may be formed by using the capacitors: Ca and Cb, or with reference to a design of a control signal, output of a fourth level and a fifth level is further provided. These may be implemented based on a conventional technology. Details are not described herein. 
     Still with reference to  FIG. 10 , when a short-circuit fault occurs on the semiconductor switch components: S 3  and S 4  at the same time, the negative electrode input port N′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 2  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 . When a symmetrical design is applied to the capacitor bridge arm  1020 , the capacitors: C 1  and C 2  each undertake a half of the voltage between the positive electrode output port P and the negative electrode output port N. Therefore, when the voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 1 , the capacitor C 1  may undertake twice a voltage in a normal design, thereby causing an overvoltage damage. Further, a circuit and a device may be further damaged after the damage is further spread. Consequently, reliability of the circuit is greatly reduced. Similarly, when a short-circuit fault occurs on the semiconductor switch components: S 1  and S 2  at the same time, the positive electrode input port P′ and the reference input port M′ are connected in a short-circuit manner. If a connection relationship is maintained between the reference output port M and the reference input port M′, the capacitor C 1  is bypassed. In this case, a voltage between the positive electrode output port P and the negative electrode output port N is all applied to the capacitor C 2 , thereby causing an overvoltage damage. In this way, the connection relationship between the reference output port M and the reference input port M′ needs to be adjusted through controlling on/off of the circuit break switch SP. Specifically, whether a short-circuit fault occurs on the semiconductor switch component may be determined through monitoring one of the following cases: A voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch components: S 3  and S 4  at the same time. Alternatively, a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage is less than a specific threshold, it is determined that the short-circuit fault occurs on the semiconductor switch components: Si and S 2  at the same time. Alternatively, a decrease rate of a voltage between the negative electrode input port N′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch components: S 3  and S 4  at the same time. Alternatively, a decrease rate of a voltage between the positive electrode input port P′ and the reference input port M′ is monitored. When the voltage decrease rate is greater than a specific threshold, it is determined that a short-circuit fault occurs on the semiconductor switch components: S 1  and S 2  at the same time. Alternatively, a current flowing from the positive electrode input port P′ to the negative electrode input port N′ and passing through the semiconductor switch component: S 1 , S 2 , S 3 , or S 4  is monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the corresponding semiconductor switch component: S 1 , S 2 , S 3 , or S 4 . Alternatively, a voltage between a collector and an emitter is monitored when the semiconductor switch component: S 1 , S 2 , S 3 , or S 4  is turned on. When the voltage is greater than a specific threshold, it is determined that a short-circuit fault occurs on the corresponding semiconductor switch component: S 1 , S 2 , S 3 , or S 4 . In this way, whether a short-circuit fault occurs on the five-level bridge arm  1030  may be determined through monitoring the foregoing cases, for example, monitoring a voltage and a current of a specific semiconductor switch component, and a connection relationship between the reference output port M and the reference input port M′ is adjusted in time through controlling on/off of the circuit break switch SP, to avoid an overvoltage damage to a half-bus capacitor and improve reliability of a circuit. In addition, a current flowing through the circuit break switch SP may also be monitored. When the current is greater than a specific threshold, it is determined that the short-circuit fault occurs on the five-level bridge arm  1030 . 
     It should be understood that a controller  1011  included in the fault protection apparatus  1010  is communicatively connected to the circuit break switch SP, and is configured to control on/off of the circuit break switch SP. The controller  1011  may include a corresponding circuit and component to monitor the foregoing cases of the short-circuit fault, or may receive an instruction from the outside by using an interface circuit. In some example embodiments, the controller  1011  may be provided separately from the fault protection apparatus  1010 , that is, provided as a separate component. In addition to the foregoing cases, another technical means may be further used to determine whether the short-circuit fault occurs on the semiconductor switch component. These may be adjusted and improved based on a specific application environment. This is not specifically limited herein. 
     It should be understood that the IGBTs are used as an example for the plurality of semiconductor switch components included in the five-level bridge arm  1000  shown in  FIG. 10 .  FIG. 10  shows examples of a collector and an emitter of each of these semiconductor switch components. When these semiconductor switch components use a semiconductor switch component in another type, for example, a MOSFET, the collector and the emitter are correspondingly replaced with a drain and a source. Therefore, the collector and the emitter shown in  FIG. 10  should be understood as example representations of a first transmission electrode and a second transmission electrode of each of the plurality of semiconductor switch components. 
     A specific embodiment provided in this application may be implemented by any one or a combination of hardware, software, firmware, or a solid-state logic circuit, and may be implemented with reference to signal processing, control, and/or a dedicated circuit. The device or the apparatus provided in a specific embodiment of this application may include one or more processors (for example, a microprocessor, a controller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or a field programmable gate array (FPGA)). These processors process various computer executable instructions to control an operation of the device or the apparatus. The device or the apparatus provided in a specific embodiment of this application may include a system bus or a data transmission system that couples all components together. The system bus may include any one of different bus structures or any combination of different bus structures, for example, a memory bus or a memory controller, a peripheral bus, a universal serial bus, and/or a processor or a local bus that uses any one of the plurality of bus structures. The device or apparatus provided in a specific embodiment of this application may be provided separately, may be a part of a system, or may be a part of another device or apparatus. 
     A specific embodiment provided in this application may include a computer-readable storage medium or be in combination with a computer-readable storage medium, for example, one or more storage devices that can provide non-temporary data storage. The computer-readable storage medium/storage device may be configured to store data, a programmer, and/or instructions. The device or apparatus is enabled to implement related operations by using the data, the programmer, and/or the instructions when a processor of the device or apparatus provided in the specific embodiment of this application executes the data, the programmer, and/or the instructions. The computer-readable storage medium/storage device may include one or more of the following features: volatile, non-volatile, dynamic, static, readable/writable, read-only, random access, sequential access, location addressable, file addressable, and content addressable. In one or more example embodiments, the computer-readable storage medium/storage device may be integrated into a device or an apparatus provided in a specific embodiment of this application, or belong to a common system. The computer-readable storage medium/storage device may include an optical storage device, a semiconductor storage device, a magnetic storage device, and/or the like; or may include a random access memory (RAM), a flash memory, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a register, a hard disk, a removable magnetic disk, a recordable and/or rewritable optical disk (CD), a digital versatile disc (DVD), a massive storage device, or an appropriate storage medium in any other form. 
     The foregoing provides specific embodiments of this application. It should be noted that sequential adjustment, combination, and deletion may be performed on the steps in the methods described in the specific embodiments of this application according to an actual requirement. In the foregoing embodiments, the description of each embodiment has respective focuses. For a part that is not described in detail in an embodiment, refer to related descriptions in other embodiments. It may be understood that the structure shown in the accompanying drawings and the embodiments of this application constitutes no specific limitation on the related apparatus or system. In some other embodiments of this application, the related apparatus or system may include more or fewer components than those shown in the specific embodiments and the accompanying drawings; or in the related apparatus or system, some components may be combined, or some components may be split, or components are disposed in different manners. A person skilled in the art understands that various adjustments or changes may be made to operations and details of the method and the device layout recorded in the specific embodiments without departing from the spirit and scope of the specific embodiments of this application; and several improvements and polishing may be further made without departing from the principle of this application. The improvements and polishing shall fall within the protection scope of this application.