Method, device and circuit for evaluating components in a circuit

Abstract

The present invention relates to the field of evaluation of circuit components, and discloses a method, a device and a circuit for evaluating the component parts in a circuit. The method includes: for any one of the six component branches in the circuit, performing evaluation according to the following content, and before the evaluation, the six component branches are in a state of non-conduction in the forward direction: controlling the evaluation component branch to conduct in the forward direction and lasting for a first preset time to charge the evaluation charge and discharge module; controlling the evaluation component branch to be non-conductive in the forward direction and lasting for a second preset time to enable the evaluation charge and discharge module to discharge; obtaining the evaluation parameters of the component to be evaluated; and judging the state of the component to be evaluated according to the obtained evaluation parameters and the preset evaluation parameters, so as to evaluate the component to be evaluated. Thereby, it is realized that the component parts can be evaluated without disassembling the component parts.

Description

Technical Field

[0001] The present invention relates to the field of circuit component evaluation, and in particular to a method and device and a circuit for evaluating components in a circuit. Background Art

[0002] In recent years, the growing energy demand and increasingly scarce energy resources have formed an irreconcilable contradiction. Therefore, more countries have shifted the focus of new energy development to the strategic deployment of renewable energy. Among these renewable energy sources, the most widely used renewable energy is solar energy. In the photovoltaic power generation system, the inverter is an important device for realizing DC to AC power conversion. Its harsh outdoor working environment, AC and DC side disturbances, equipment assembly process and internal electrical and thermal stresses have greatly increased the inverter failure rate. Once a failure occurs, it may cause the entire photovoltaic power generation system to collapse, causing economic losses and even endangering personnel safety. Industrial surveys show that a large part of the failures of photovoltaic power generation systems can be attributed to the failure of grid-connected inverters. The reliability problem of inverters has become a common and urgent practical problem that needs to be solved.

[0003] Industrial statistics show that the power device IGBT used in the inverter is the module most prone to failure in the converter. The working state of the inverter is affected by both the DC side and the AC side power supply, and the failure has obvious coupling. Once the external disturbance is too large and causes the control circuit to be unstable, the power device inside the inverter may be subjected to huge electrical and thermal stress, which will not only cause the device to age quickly, but also burn out in serious cases, causing the grid-connected voltage and current quality to decline and the system to shut down. Therefore, when selecting the power IGBT for photovoltaic grid-connected inverters, it is necessary to evaluate the life and reliability of the IGBT in advance, that is, a power device aging test platform that can simulate the real working conditions of three-phase photovoltaic grid-connected is urgently needed.

[0004] There is no IGBT status monitoring and dynamic parameter extraction technology based on actual three-phase photovoltaic grid-connected inverter working conditions at home and abroad. If you want to extract the dynamic parameters of the IGBT of the three-phase photovoltaic grid-connected inverter, you often need to disassemble the IGBT from the inverter. This method may not only cause damage to the three-phase photovoltaic inverter, but also consumes huge time and labor costs. Summary of the invention

[0005] An object of the embodiments of the present invention is to provide a method, an apparatus and a circuit for evaluating components in a circuit, which can solve or at least partially solve the above-mentioned problems.

[0006] To achieve the above object, on the one hand, the present invention provides a method for evaluating components in a circuit, the method comprising: for any one of the six component branches in the circuit, evaluating according to the following content and the six component branches being in a non-conductive state in the forward direction before evaluation: controlling the evaluated component branch to conduct in the forward direction and continue for a first preset time to charge the evaluation charge and discharge module, wherein the evaluated component branch is the component branch where the evaluated component in the six component branches is located, and the evaluation charge and discharge module is the charge and discharge module connected to the evaluated component branch among the first charge and discharge module, the second charge and discharge module, and the third charge and discharge module, the circuit includes a power supply module, the six component branches, the first charge and discharge module, the second charge and discharge module, the third charge and discharge module, and a switch module, the six component branches are combined in pairs and connected through a first connection point, a second connection point, and a third connection point respectively to be connected in series between both ends of the power supply module, both ends of the first charge and discharge module are respectively connected to the first connection point and the switch module, both ends of the second charge and discharge module are respectively connected to the second connection point and the switch module, both ends of the third charge and discharge module are respectively connected to the third connection point and the switch module, the switch module is located between both ends of the power supply module, each component branch in the six component branches includes at least one of the components, during the forward conduction of the evaluated component branch, the power supply module, the evaluated component branch, the evaluation charge and discharge module, and the switch module form a loop, and the component is an IGBT or a MOSFET; controlling the evaluated component branch to be non-conductive in the forward direction and continue for a second preset time to cause the evaluation charge and discharge module to discharge, wherein during the non-conduction of the evaluated component branch in the forward direction, the switch module, the evaluation charge and discharge module, and the opposite component branch of the evaluated component branch form a loop, and the opposite component branch of the evaluated component branch is the component branch connected to the evaluated component branch; obtaining the evaluation parameters of the evaluated component, wherein the evaluation parameters include rise time, fall time, turn-on delay time, and turn-off delay time; and judging the state of the evaluated component according to the obtained evaluation parameters and preset evaluation parameters to evaluate the evaluated component.

[0007] Optionally, before obtaining the evaluation parameters of the evaluated component, the method further comprises: controlling the evaluated component branch to conduct in the forward direction and continue for a third preset time.

[0008] Optionally, when the six component branches are not in the forward non-conducting state before evaluating the component to be evaluated, the method further includes: controlling the six component branches to be forward non-conducting.

[0009] Optionally, the switch module includes six switch component branches, and the six switch component branches are combined in pairs and connected through a fourth connection point, a fifth connection point, and a sixth connection point respectively to be connected in series between both ends of the power supply module. Both ends of the first charge and discharge module are respectively connected to the first connection point and the fourth connection point. Both ends of the second charge and discharge module are respectively connected to the second connection point and the fifth connection point. Both ends of the third charge and discharge module are respectively connected to the third connection point and the sixth connection point. Each switch component branch in the six switch component branches includes at least one switch component, and the switch component is an IGBT or a MOSFET. Before evaluating the component to be evaluated, controlling the six switch component branches to be forward non-conducting, the method further includes: when evaluating the component to be evaluated, controlling the opposite-side switch component branch to be forward conducting, where the opposite-side switch component branch is the switch component branch in the six switch component branches that is connected to the evaluation charge and discharge module and is located on a different side from the evaluation component branch with respect to the evaluation charge and discharge module.

[0010] Optionally, the component is an IGBT, and the evaluation parameters further include the voltage between the collector and the emitter, the voltage between the gate and the emitter, and the collector current.

[0011] Optionally, when the circuit includes a component branch, controlling the component branch to be forward conducting or forward non-conducting is achieved by applying a pulse to the component in the component branch; and when the circuit includes a switch component branch, controlling the switch component branch to be forward conducting or forward non-conducting is achieved by applying a pulse to the switch component in the switch component branch.

[0012] Correspondingly, another aspect of the embodiments of the present invention provides a device for evaluating the components in a circuit. The device includes: an evaluation module for evaluating any one of the six component branches in the circuit according to the following, and before the evaluation, the six component branches are in a state of non-conduction in the forward direction: controlling the forward conduction of the evaluation component branch for a first preset time to charge the evaluation charge-discharge module, where the evaluation component branch is the component branch where the evaluated component in the six component branches is located, and the evaluation charge-discharge module is the charge-discharge module connected to the evaluation component branch among the first charge-discharge module, the second charge-discharge module, and the third charge-discharge module. The circuit includes a power supply module, the six component branches, the first charge-discharge module, the second charge-discharge module, the third charge-discharge module, and a switch module. The six component branches are combined in pairs and connected through a first connection point, a second connection point, and a third connection point respectively to be connected in series between the two ends of the power supply module. The two ends of the first charge-discharge module are respectively connected to the first connection point and the switch module. The two ends of the second charge-discharge module are respectively connected to the second connection point and the switch module. The two ends of the third charge-discharge module are respectively connected to the third connection point and the switch module. The switch module is located between the two ends of the power supply module. Each component branch in the six component branches includes at least one of the components. During the forward conduction of the evaluation component branch, the power supply module, the evaluation component branch, the evaluation charge-discharge module, and the switch module form a loop. The component is an IGBT or a MOSFET; controlling the forward non-conduction of the evaluation component branch for a second preset time to cause the evaluation charge-discharge module to discharge, where during the forward non-conduction of the evaluation component branch, the switch module, the evaluation charge-discharge module, and the opposite component branch of the evaluation component branch form a loop. The opposite component branch of the evaluation component branch is the component branch connected to the evaluation component branch; obtaining the evaluation parameters of the evaluated component, where the evaluation parameters include rise time, fall time, turn-on delay time, and turn-off delay time; and judging the state of the evaluated component according to the obtained evaluation parameters and preset evaluation parameters to evaluate the evaluated component.

[0013] Optionally, the evaluation module is further configured to: before obtaining the evaluation parameters of the evaluated component, control the forward conduction of the evaluation component branch for a third preset time.

[0014] Optionally, the evaluation module is further configured to: when the six component branches are not in the forward non-conducting state before evaluating the to-be-evaluated component, control the six component branches to be forward non-conducting.

[0015] Optionally, the switch module includes six switch component branches, and the six switch component branches are combined in pairs and connected through a fourth connection point, a fifth connection point, and a sixth connection point respectively to be connected in series between the two ends of the power supply module. The two ends of the first charge and discharge module are respectively connected to the first connection point and the fourth connection point, the two ends of the second charge and discharge module are respectively connected to the second connection point and the fifth connection point, the two ends of the third charge and discharge module are respectively connected to the third connection point and the sixth connection point. Each switch component branch in the six switch component branches includes at least one switch component, and the switch component is an IGBT or a MOSFET. Before evaluating the to-be-evaluated component, control the six switch component branches to be forward non-conducting. The evaluation module is further configured to: when evaluating the to-be-evaluated component, control the opposite switch component branch to be forward conducting, where the opposite switch component branch is the switch component branch in the six switch component branches that is connected to the evaluation charge and discharge module and is located on a different side from the evaluation component branch with respect to the evaluation charge and discharge module.

[0016] Optionally, the component is an IGBT, and the evaluation parameters further include the voltage between the collector and the emitter, the voltage between the gate and the emitter, and the collector current.

[0017] Optionally, when the circuit includes a component branch, the evaluation module controls the component branch to be forward conducting or forward non-conducting by applying a pulse to the component in the component branch; and when the circuit includes a switch component branch, the evaluation module controls the switch component branch to be forward conducting or forward non-conducting by applying a pulse to the switch component in the switch component branch.

[0018] In addition, another aspect of the embodiments of the present invention further provides a circuit, and the circuit includes a component, and the component is evaluated according to the above method.

[0019] Through the above technical solution, by controlling the forward conduction and non - forward conduction of the component branch where the component to be evaluated is located and forming a loop with the switch module to control the charging and discharging of the charge - discharge module, the evaluation parameters of the component can be obtained. According to the obtained evaluation parameters, the state of the component to be evaluated is judged to realize the evaluation of the component to be evaluated. In this way, it is realized that the component can be evaluated without disassembling it, reducing the probability of damaging the component to be evaluated and reducing the time and labor costs. In addition, the evaluation method is simple, reducing the cost. Brief Description of the Drawings

[0020] Figure 1 is a flowchart of a method for evaluating components in a circuit provided by an embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of a circuit provided by another embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of a circuit provided by another embodiment of the present invention;

[0023] Figure 4 is a schematic diagram of a circuit provided by another embodiment of the present invention;

[0024] Figure 5 is a schematic diagram of a circuit provided by another embodiment of the present invention; and

[0025] Figure 6 is a schematic diagram of the applied pulse signal provided by another embodiment of the present invention.

[0026] Description of the Reference Numerals

[0027] 1. First IGBT; 2. Second IGBT; 3. Third IGBT; 4. Fourth IGBT; 5. Fifth IGBT; 6. Sixth IGBT; 7. Seventh IGBT; 8. Eighth IGBT; 9. Ninth IGBT; 10. Tenth IGBT; 11. Eleventh IGBT; 12. Twelfth IGBT; Q1. First main pipe; Q2. Second main pipe; Q3. Third main pipe; Q4. Fourth main pipe; Q5. Fifth main pipe; Q6. Sixth main pipe; Q7. Seventh main pipe; Q8. Eighth main pipe; Q9. Ninth main pipe; Q 10 、Tenth main pipe; Q 11 、Eleventh main pipe; Q 12 、Twelfth main pipe; D1. First free - wheeling diode; D2. Second free - wheeling diode; D3. Third free - wheeling diode; D4. Fourth free - wheeling diode; D5. Fifth free - wheeling diode; D6. Sixth free - wheeling diode; D7. Seventh free - wheeling diode; D8. Eighth free - wheeling diode; D9. Ninth free - wheeling diode; D 10, the tenth freewheeling diode; D 11 , the eleventh freewheeling diode; D 12 , the twelfth freewheeling diode; A, the first capacitor; B, the second capacitor; C, the third capacitor; D, the fourth capacitor; F, the fifth capacitor; G, the sixth capacitor; K, the first connection point; M, the second connection point; N, the third connection point; O, the fourth connection point; P, the fifth connection point; Q, the sixth connection point; U DC , the DC power supply; L1, the first inductor; L2, the second inductor; L3, the third inductor; R, the seventh connection point; S, the eighth connection point; T, the ninth connection point. Specific embodiments

[0028] The following describes in detail the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention.

[0029] One aspect of the embodiments of the present invention provides a method for evaluating the components in a circuit.

[0030] Figure 1 is a flowchart of a method for evaluating the components in a circuit provided by an embodiment of the present invention. As Figure 1 shown, the method includes the following content. It should be noted that the following introduction is described by taking a certain component to be evaluated in one of the six component branches as an example. Any component to be evaluated in the six component branches is evaluated according to the following introduction. In addition, before the evaluation, the six component branches are in a state of non-conduction in the forward direction. Among them, the six component branches described here are the branches where the components are located. Each component branch in the six component branches includes at least one component. Whether the component branch conducts or does not conduct in the forward direction depends on whether the components included in the branch conduct in the forward direction. The component can be an IGBT or a MOSFET. The IGBT or MOSFET includes a main transistor and a freewheeling diode. If the current passes through the IGBT or MOSFET via the main transistor, the IGBT or MOSFET conducts in the forward direction; if the main transistor does not conduct, the IGBT or MOSFET does not conduct in the forward direction. For example, as Figure 2As shown, the IGBT in the inverter side is a component described in the embodiments of the present invention. For the branch where the first IGBT 1 is located, if the current flows through the first IGBT 1 via the first main pipe Q1, then the first IGBT 1 is forward-conducting, and the branch where the first IGBT 1 is located is forward-conducting; if the current flows through the first IGBT 1 via the first freewheeling diode D1 but the first main pipe Q1 is not conducting, then the first IGBT 1 is not forward-conducting. Although the branch where the first IGBT 1 is located can conduct current, the branch where the first IGBT 1 is located is not forward-conducting. For any component branch, when all components in the component branch are forward-conducting, the component branch is forward-conducting; when at least one component in the component branch is not forward-conducting, the component branch is not forward-conducting. In addition, the circuit includes a power supply module, six component branches, a first charge-discharge module, a second charge-discharge module, a third charge-discharge module, and a switch module. The six component branches are combined in pairs and connected through a first connection point, a second connection point, and a third connection point respectively to be connected in series between the two ends of the power supply module. As Figure 2 shown, there are six IGBTs on the inverter side. Each IGBT occupies a component branch. The component branch where the first IGBT 1 is located and the component branch where the fourth IGBT 4 is located are combined and connected in series between the two ends of the DC power supply U through the first connection point K DC ; the component branch where the second IGBT 2 is located and the component branch where the fifth IGBT 5 is located are combined and connected in series between the two ends of the DC power supply U through the second connection point M DC ; the component branch where the third IGBT 3 is located and the component branch where the sixth IGBT 6 is located are combined and connected in series between the two ends of the DC power supply U through the third connection point N DC . The two ends of the first charge-discharge module are respectively connected to the first connection point and the switch module. The two ends of the second charge-discharge module are respectively connected to the second connection point and the switch module. The two ends of the third charge-discharge module are respectively connected to the third connection point and the switch module. The switch module is located between the two ends of the power supply module. Each component branch in the six component branches includes at least one component, and the component can be an IGBT or a MOSFET. In addition, when conducting the evaluation, the power supply module is in the power supply state. Optionally, the power supply module can be a DC power supply. Optionally, the first charge-discharge module and / or the second charge-discharge module and / or the third charge-discharge module can be an inductor. Optionally, a capacitor can also be included in the circuit. The capacitor is connected between the two ends of the power supply module for energy storage; the capacitor and the power supply module are combined together to achieve a stable output power supply. Optionally, the power supply module can obtain electrical energy based on photovoltaic.

[0031] In step S10, control the component branch of the evaluation group to conduct forwardly and continuously for a first preset time to charge the evaluation charge and discharge module. Among them, the component branch of the evaluation group is the component branch where the evaluated component is located among the six component branches, and the evaluation charge and discharge module is the charge and discharge module connected to the component branch of the evaluation group among the first charge and discharge module, the second charge and discharge module, and the third charge and discharge module. For example, as Figure 2 shown, the IGBT in the inverter side is the component described in the embodiment of the present invention. The inverter side includes six IGBTs, and the branch where each IGBT is located is a component branch, and the charge and discharge module is an inductor. If the first IGBT 1 is evaluated, the branch where the first IGBT 1 is located is the component branch of the evaluation group; the first inductor L1 is connected to the branch where the first IGBT 1 is located, so the first inductor L1 is the evaluation charge and discharge module. In addition, during the forward conduction of the component branch of the evaluation group, the power supply module, the component branch of the evaluation group, the evaluation charge and discharge module, and the switch module form a loop. In addition, the first preset time is related to the magnitude of the charging current value preset for the evaluated component and can be set according to the magnitude of the preset charging current value.

[0032] In step S11, control the component branch of the evaluation group not to conduct forwardly and continuously for a second preset time to cause the evaluation charge and discharge module to discharge. Among them, during the non-forward conduction of the component branch of the evaluation group, the switch module, the evaluation charge and discharge module, and the opposite component branch of the component branch of the evaluation group form a loop. The opposite component branch of the component branch of the evaluation group is the component branch connected to the component branch of the evaluation group. As Figure 2 shown, if the first IGBT 1 is evaluated, the branch where the first IGBT 1 is located is the component branch of the evaluation group, and the branch where the fourth IGBT 4 is located is the opposite component branch. In addition, the second preset time is related to the switching frequency of the evaluated component and can be set according to the switching frequency of the evaluated component. In addition, when discharging, the opposite component branch forms a loop with other parts through the freewheeling diode included in its components. As Figure 5 shown, when the fourth IGBT 4 is evaluated and discharging, the component branch where the first IGBT 1 is located is the opposite component branch, and the inductor L1, the switch component branch where the seventh IGBT 7 is located, and the first freewheeling diode D1 form a loop, and the seventh IGBT 7 conducts forwardly.

[0033] In step S12, obtain the evaluation parameters of the evaluated component. Among them, the evaluation parameters include rise time, fall time, turn-on delay time, and turn-off delay time. For example, an oscilloscope can be connected to the evaluated component, and the evaluation parameters can be obtained through the oscilloscope.

[0034] In step S13, based on the obtained evaluation parameters and the preset evaluation parameters, the state of the component to be evaluated is judged to evaluate the component to be evaluated. Specifically, the evaluation parameters include rise time, fall time, turn-on delay time, and turn-off delay time. The preset evaluation parameters set thresholds for each item in the evaluation parameters, that is, the preset evaluation parameters include preset rise time, preset fall time, preset turn-on delay time, and preset turn-off delay time. Judging the state of the component to be evaluated according to the obtained evaluation parameters and the preset evaluation parameters is to compare each item in the evaluation parameters with its corresponding threshold to judge the state of the component to be evaluated. Optionally, judging the state of the component to be evaluated according to the obtained evaluation parameters and the preset evaluation parameters may be that when at least one item in the evaluation parameters does not reach the corresponding preset threshold, the state of the component to be evaluated is judged to be poor.

[0035] Through the above technical solution, by controlling the forward conduction and non-forward conduction of the component branch where the component to be evaluated is located and forming a loop with the switch module to control the charging and discharging of the charging and discharging module, the evaluation parameters of the component can be obtained. According to the obtained evaluation parameters, the state of the component to be evaluated is judged to realize the evaluation of the component to be evaluated. In this way, it is realized that the component can be evaluated without disassembling the component, reducing the probability of damaging the component to be evaluated, and reducing the time and labor costs; in addition, the evaluation method is simple and the cost is reduced.

[0036] Optionally, in the embodiment of the present invention, before obtaining the evaluation parameters of the component to be evaluated, the method further includes: controlling the component branch to be evaluated to conduct forwardly and continuously for a third preset time. The third preset time is related to the switching frequency of the component to be evaluated and can be set according to the switching frequency of the component to be evaluated. By controlling the component branch to be evaluated to conduct forwardly again, double-pulse testing can be realized, which can make the obtained evaluation parameters more accurate; in addition, the reverse recovery current can also be obtained, so that the evaluation parameters can include the reverse recovery current; in addition, when the charging and discharging module is an inductor, the turn-off spike caused by stray inductance can also be obtained, so that the evaluation parameters can include the turn-off spike caused by stray inductance. It should be noted that during the period of controlling the component branch to be evaluated to conduct forwardly again, the power supply module, the component branch to be evaluated, the charging and discharging module to be evaluated, and the switch module form a loop.

[0037] Optionally, in the embodiment of the present invention, when the six component branches are not in the non-forward conduction state before evaluating the component to be evaluated, the method further includes: controlling the six component branches to be non-forward conductive.

[0038] Optionally, in an embodiment of the present invention, the switching module may include six switching component branches. A switching component branch is a branch where a switching component is located. Each of the six switching component branches includes at least one switching component. The switching component may be an IGBT or a MOSFET. The six switching component branches are combined in pairs and connected through a fourth connection point, a fifth connection point, and a sixth connection point respectively to be connected in series between both ends of the power supply module. As Figure 2 shown, the rectifier side is the switching module described in the embodiment of the present invention, the switching component is an IGBT, and there are a total of six IGBTs. Each IGBT occupies a switching component branch. The switching component branch where the seventh IGBT 7 is located and the switching component branch where the tenth IGBT 10 is located are combined and connected in series between both ends of the DC power supply U DC through the fourth connection point O. The switching component branch where the eighth IGBT 8 is located and the switching component branch where the eleventh IGBT 11 is located are combined and connected in series between both ends of the DC power supply U DC through the fifth connection point P. The switching component branch where the ninth IGBT 9 is located and the switching component branch where the twelfth IGBT 12 is located are combined and connected in series between both ends of the DC power supply U DC through the sixth connection point Q. Both ends of the first charge and discharge module are respectively connected to the first connection point and the fourth connection point. Both ends of the second charge and discharge module are respectively connected to the second connection point and the fifth connection point. Both ends of the third charge and discharge module are respectively connected to the third connection point and the sixth connection point. As Figure 2 shown, the first inductor L1 is connected to the first connection point K and the fourth connection point O. The second inductor L2 is connected to the second connection point M and the fifth connection point P. The third inductor L3 is connected to the third connection point N and the sixth connection point Q. Before evaluating the component to be evaluated, control the six switching component branches to be non-conductive in the forward direction. The method further includes: when evaluating the component to be evaluated, control the opposite-side switching component branch to be conductive in the forward direction, where the opposite-side switching component branch is the switching component branch among the six switching component branches that is connected to the evaluation charge and discharge module and is on the different side of the evaluation component branch relative to the evaluation charge and discharge module. In addition, the six switching component branches described in the embodiment of the present invention are the branches where the switching components are located. Each of the six switching component branches may include at least one switching component. The forward conduction and non-conduction of the switching component branch depend on whether the switching component included in the branch is conductive in the forward direction. The switching component may be an IGBT or a MOSFET. The IGBT or MOSFET includes a main tube and a freewheeling diode. If the current passes through the IGBT or MOSFET via the main tube, the IGBT or MOSFET is conductive in the forward direction; if the main tube is non-conductive, the IGBT or MOSFET is non-conductive in the forward direction. For example, as Figure 2As shown, the IGBT in the rectifier side is the switching component described in the embodiments of the present invention. For the branch where the seventh IGBT 7 is located, if the current flows through the seventh IGBT 7 via the seventh main pipe Q7, then the seventh IGBT 7 is forward-conducting, and the switching component branch where the seventh IGBT 7 is located is forward-conducting; if the current flows through the seventh IGBT 7 via the seventh freewheeling diode D7 but the seventh main pipe Q7 is not conducting, then the seventh IGBT 7 is not forward-conducting. Although the switching component branch where the seventh IGBT 7 is located can conduct current, the switching component branch where the seventh IGBT 7 is located is not forward-conducting. For any switching component branch, when all the switching components in the switching component branch are forward-conducting, the switching component branch is forward-conducting; when at least one of the switching components in the switching component branch is not forward-conducting, the switching component branch is not forward-conducting. In addition, as Figure 2 shown, if the first IGBT 1 is evaluated, the branch where the first IGBT 1 is located is the evaluation component branch, and the first inductor L1 is the evaluation charge and discharge module, then the switching component branch where the tenth IGBT 10 is located is the opposite-side switching component branch. In addition, when evaluating the component to be evaluated, the loop for charging and discharging in combination with the switching module forms a loop via the opposite-side switching component branch. For example, during the charging of the evaluation charge and discharge module, the power supply module, the opposite-side switching component branch, the evaluation charge and discharge module, and the evaluation component branch form a loop; during the discharging of the evaluation charge and discharge module, the opposite-side switching component branch, the evaluation charge and discharge module, and the opposite-side component branch form a loop.

[0039] Optionally, in the embodiments of the present invention, the component can be an IGBT, and the evaluation parameters further include the voltage between the collector and the emitter, the voltage between the gate and the emitter, and the collector current.

[0040] Optionally, in the embodiments of the present invention, when the circuit includes a component branch, controlling the component branch to conduct or not conduct in the forward direction is achieved by applying a pulse to the component in the component branch; and when the circuit includes a switch component branch, controlling the switch component branch to conduct or not conduct in the forward direction is achieved by applying a pulse to the switch component in the switch component branch. Specifically, when controlling the component branch where the component is located to conduct or not conduct in the forward direction, it can be achieved by applying a pulse to the component. When there is only one component in the component branch where the component is located, controlling the component branch where the component is located to conduct or not conduct in the forward direction can be achieved by pulse-controlling the forward conduction or non-conduction of this one component. When there are multiple components in the component branch where the component is located, controlling the forward conduction of the component branch can be achieved by pulse-controlling all the components on the component branch to conduct; controlling the forward non-conduction of the component branch can be achieved by pulse-controlling at least one component on the component branch to be non-conductive in the forward direction. In addition, when controlling the switch component branch where the switch component is located to conduct or not conduct in the forward direction, it can be achieved by applying a pulse to the switch component. When there is only one switch component in the switch component branch where the switch component is located, controlling the switch component branch where the switch component is located to conduct or not conduct in the forward direction can be achieved by pulse-controlling the forward conduction or non-conduction of this one switch component. When there are multiple switch components in the switch component branch where the switch component is located, controlling the forward conduction of the switch component branch can be achieved by pulse-controlling all the switch components on the switch component branch to conduct in the forward direction; controlling the forward non-conduction of the switch component branch can be achieved by pulse-controlling at least one switch component on the switch component branch to be non-conductive in the forward direction. Optionally, applying a positive pulse to the component or the switch component can make the component or the switch component conduct in the forward direction; applying a negative pulse to the component or the switch component can make the component or the switch component not conduct in the forward direction. Specifically, for a MOSFET, for an N-channel enhancement-mode MOSFET, applying a positive pulse conducts it in the forward direction, and applying a negative pulse makes it non-conductive in the forward direction; for a P-channel enhancement-mode MOSFET, applying a negative pulse conducts it in the forward direction, and applying a positive pulse makes it non-conductive in the forward direction. For an IGBT, for an NPN-type IGBT, applying a positive pulse conducts it in the forward direction, and applying a negative pulse makes it non-conductive in the forward direction; for a PNP-type IGBT, applying a negative pulse conducts it in the forward direction, and applying a positive pulse makes it non-conductive in the forward direction.

[0041] The following is combined with Figures 2 - 6An exemplary introduction is provided to the method for evaluating the components in a circuit according to the embodiments of the present invention. Among them, in this embodiment, both the component and the switching component are IGBTs, and they are NPN-type IGBTs, and the circuit is in a three-phase photovoltaic grid-connected working condition. It should be noted that in the embodiments of the present invention, the component and the switching component may be the same or different. The power supply module is a DC power supply, and the DC power supply is powered by photovoltaic power. When evaluating, the DC power supply supplies power normally. The circuit includes a voltage stabilizing capacitor and a filtering capacitor. The voltage stabilizing capacitor is combined with the DC power supply to output a stable power supply, and the filtering capacitor is used for filtering. The first charge-discharge module, the second charge-discharge module, and the third charge-discharge module are all inductors. In addition, in this embodiment, the circuit is also a three-level topological structure. As Figure 2 shown, two IGBTs are connected in series between the seventh connection point R and the first connection point K, and these two IGBTs share the same emitter; two IGBTs are connected in series between the eighth connection point S and the second connection point M, and these two IGBTs share the same emitter; two IGBTs are connected in series between the ninth connection point T and the third connection point N, and these two IGBTs share the same emitter. The function of the three-level topology is to reduce the overall stress on the device. Because in terms of requirements, we hope to increase the voltage and reduce the current while maintaining the same power level in the inverter (when the current is reduced, the copper and power device volume required in the design will also be reduced). In the traditional two-level, the switching device in the half-bridge structure bears the full input voltage, while in the three-level, by adding additional switching devices, the voltage stress on the device can be significantly reduced.

[0042] The aging assessment of the device not only needs to assess the change in the static characteristics of the device before and after aging, but also needs to measure the change in the dynamic characteristics of the device before and after aging. However, the existing power device aging tests often stay at power cycling, temperature cycling, and static parameter aging tests. There is no IGBT state monitoring and dynamic parameter extraction technology based on the actual three-phase photovoltaic grid-connected inverter working condition at home and abroad. Based on this, the embodiments of the present invention propose an IGBT reliability assessment technology based on the three-phase photovoltaic grid-connected working condition to more accurately assess the reliability of IGBTs in the three-phase photovoltaic grid-connected inverter system. The IGBT dynamic parameter extraction technology provided by the embodiments of the present invention for the three-phase photovoltaic grid-connected inverter assessment system can not only simulate the actual three-phase photovoltaic grid-connected operation condition (specifically realized by using the rectifier side to simulate the power grid), but also realize the IGBT double-pulse test through circuit control means, avoiding the disassembly of the IGBT. Among them, the circuit for IGBT reliability assessment based on the three-phase photovoltaic grid-connected inverter operation condition can refer to Figure 2 shown.

[0043] Combined with Figure 2Introduce the circuit. The circuit includes the first capacitor A, the second capacitor B, the third capacitor C, the fourth capacitor D, the fifth capacitor F, and the sixth capacitor G. The first capacitor A, the second capacitor B, and the third capacitor C are connected in parallel in the three-phase circuit and are all used for filtering. The fifth capacitor F and the sixth capacitor G are connected in series between the two ends of the DC power supply U DC and are combined with the DC power supply U DC to output a stable power supply; the fourth capacitor D is connected between the two ends of the DC power supply U DC and is also used to be combined with the DC power supply U DC to output a stable power supply. The circuit also includes six component branches and six switch component branches, and each component branch or each switch component branch has only one IGBT. The six component branches, namely the first IGBT 1, the second IGBT 2, the third IGBT 3, the fourth IGBT 4, the fifth IGBT 5, and the sixth IGBT 6, form the inverter side. The six switch component branches, namely the seventh IGBT 7, the eighth IGBT 8, the ninth IGBT 9, the tenth IGBT 10, the eleventh IGBT 11, and the twelfth IGBT 12, form the rectifier side. The first IGBT 1 includes the first main transistor Q1 and the first freewheeling diode D1, the second IGBT 2 includes the second main transistor Q2 and the second freewheeling diode D2, the third IGBT 3 includes the third main transistor Q3 and the third freewheeling diode D3, the fourth IGBT 4 includes the fourth main transistor Q4 and the fourth freewheeling diode D4, the fifth IGBT 5 includes the fifth main transistor Q5 and the fifth freewheeling diode D5, the sixth IGBT 6 includes the sixth main transistor Q6 and the sixth freewheeling diode D6, the seventh IGBT 7 includes the seventh main transistor Q7 and the seventh freewheeling diode D7, the eighth IGBT 8 includes the eighth main transistor Q8 and the eighth freewheeling diode D8, the ninth IGBT 9 includes the ninth main transistor Q9 and the ninth freewheeling diode D9, the tenth IGBT 10 includes the tenth main transistor Q 10 and the tenth freewheeling diode D 10 , the eleventh IGBT 11 includes the eleventh main transistor Q 11 and the eleventh freewheeling diode D 11 , the twelfth IGBT 12 includes the twelfth main transistor Q 12 and the twelfth freewheeling diode D 12 . The component branch where the first IGBT 1 is located and the component branch where the fourth IGBT 4 is located are connected in series between the two ends of the DC power supply U DC , and the component branch where the second IGBT 2 is located and the component branch where the fifth IGBT 5 is located are connected in series between the two ends of the DC power supply U DCBoth ends of; the component branch where the third IGBT 3 is located and the component branch where the sixth IGBT 6 is located are connected in series across the DC power supply U through the third connection point N DC Both ends of. The switch component branch where the seventh IGBT 7 is located and the switch component branch where the tenth IGBT 10 is located are connected in series across the DC power supply U through the fourth connection point O DC Both ends of. The switch component branch where the eighth IGBT 8 is located and the switch component branch where the eleventh IGBT 11 is located are connected in series across the DC power supply U through the fifth connection point P DC Both ends of; the switch component branch where the ninth IGBT 9 is located and the switch component branch where the twelfth IGBT 12 is located are connected in series across the DC power supply U through the sixth connection point Q DCThe component branch where the first IGBT 1 is located and the component branch where the fourth IGBT 4 is located are opposite component branches, and the component branch where the second IGBT 2 is located and the component branch where the fifth IGBT 5 is located are opposite component branches. The component branch where the third IGBT 3 is located and the component branch where the sixth IGBT 6 is located are opposite component branches. The switch component branch where the seventh IGBT 7 is located is the opposite switch component branch when the fourth IGBT 4 is evaluated, the switch component branch where the eighth IGBT 8 is located is the opposite switch component branch when the fifth IGBT 5 is evaluated, the switch component branch where the ninth IGBT 9 is the opposite switch component branch when the sixth IGBT 6 is evaluated, the switch component branch where the tenth IGBT 10 is the opposite switch component branch when the first IGBT 1 is evaluated, the switch component branch where the eleventh IGBT 11 is the opposite switch component branch when the second IGBT 2 is evaluated, and the switch component branch where the twelfth IGBT 12 is the opposite switch component branch when the third IGBT 3 is evaluated. The first inductor L1 is connected between the first connection point K and the fourth connection point O, the second inductor L2 is connected between the second connection point M and the fifth connection point P, and the third inductor L3 is connected between the third connection point N and the sixth connection point Q. In addition, in this embodiment, the forward conduction or forward non-conduction is controlled by applying a pulse voltage to the IGBT. There is only one IGBT in each branch (component branch or switch component branch) where the IGBT is located. Therefore, the forward conduction or forward non-conduction of the IGBT is the forward conduction or forward non-conduction of the branch where it is located; and double pulses are used for evaluation, that is, the IGBT being evaluated undergoes three processes of forward conduction, forward non-conduction and forward conduction again. The evaluation circuit for evaluating the IGBT consists of a T-type three-phase inverter part and a three-phase rectifier part. The DC power supplies on the rectifier side and the inverter side are connected together to realize energy circulation, thereby reducing the power required for the operation of the overall system. The DC power supply on the inverter side only needs to provide the loss power of the overall system, that is, the DC power supply is normally powered. When the IGBT does not need to be evaluated, the entire evaluation circuit simulates the working conditions of three-phase photovoltaic grid-connected through the rectifier side, and the T-type inverter side works under the working conditions of three-phase photovoltaic grid-connected inverter, thereby realizing the aging of the IGBT on the T-type inverter side based on the actual photovoltaic grid-connected working conditions; when the IGBT needs to be evaluated, the IGBT double pulse test is realized by means of circuit control. In this way, not only the simulation of the actual photovoltaic grid-connected working conditions is realized, but also the IGBT double pulse test function before and after aging is compatible, and the dynamic parameters of the IGBT are extracted.

[0044] Taking the fourth IGBT 4 as the object to be measured, the technical solution provided by the embodiment of the present invention will be introduced exemplarily. It should be noted that when evaluating other IGBTs in the inverter side, the following content can be referred to for evaluation.

[0045] To implement the double-pulse test of the IGBT in the inverter side, first, the evaluation system needs to be stopped from the normal working state, and all switching devices are in the off state, that is, controlling all IGBTs not to conduct forward, as Figure 3 .

[0046] When taking the fourth IGBT 4 as the evaluation object, the switching component branch where the seventh IGBT 7 is located is the opposite switching component branch, the component branch where the first IGBT 1 is located is the opposite component branch, and the first inductor L1 is the evaluation charge and discharge module. Pulse voltages as Figure 6 shown are applied to the fourth IGBT 4 and the seventh IGBT 7, and other devices are always in the off state. Among them, applying pulse voltages to the fourth IGBT 4 and the seventh IGBT 7 is actually applying pulse voltages to the fourth main transistor Q4 and the seventh main transistor Q7, and the gate voltages applied to the fourth IGBT 4 and the seventh IGBT 7 are as Figure 6 shown. Among them, a double-pulse gate signal is applied to the fourth IGBT 4; a positive pulse is applied to the seventh IGBT 7, making the seventh IGBT always in the forward conduction state.

[0047] During the time period t0 - t1, positive voltages are applied to the fourth IGBT 4 and the seventh IGBT 7, and the fourth IGBT 4 and the seventh IGBT 7 conduct forward simultaneously, that is, controlling the branches where the fourth IGBT 4 and the seventh IGBT 7 are located to conduct forward. At this time, the DC power supply U DC charges the first inductor L1 through the fourth IGBT 4 and the seventh IGBT 7, and the current path is as Figure 4 shown. Among them, the magnitude of the positive voltage can be set according to the requirements of the device to be measured.

[0048] During the time period t1 - t2, a negative voltage is applied to the fourth IGBT 4, and a positive voltage is applied to the seventh IGBT 7. The fourth IGBT 4 does not conduct forward, and the seventh IGBT 7 conducts forward, that is, controlling the branch where the fourth IGBT 4 is located not to conduct forward, and controlling the branch where the seventh IGBT 7 is located to conduct forward. The current on the first inductor L1 realizes freewheeling through the seventh IGBT 7 and the first freewheeling diode D1, and the freewheeling path is as Figure 5 shown. Among them, the negative voltage (turn-off voltage) can be set according to the requirements of the device to be measured.

[0049] During the time period from t2 to t3, a positive voltage is applied to the fourth IGBT 4 and the seventh IGBT 7, and the fourth IGBT 4 and the seventh IGBT 7 are simultaneously forward-conducted, that is, the branches where the fourth IGBT 4 and the seventh IGBT 7 are located are controlled to be forward-conducted. At this time, the DC power supply U DC charges the first inductor L1 through the fourth IGBT 4 and the seventh IGBT 7, and the current path is as Figure 4 shown.

[0050] The double-pulse test of the first IGBT 4 is realized according to the above method. The dynamic parameters of the IGBT turn-on and turn-off with load (that is, the evaluation parameters described in the embodiments of the present invention) can be extracted at t1 and t2, and the state monitoring of the aged IGBT is realized. Among them, the dynamic parameters mainly extracted by the double-pulse test include rise time, fall time, turn-on delay time, turn-off delay time, voltage Vce between the collector and the emitter, voltage Vge between the gate and the emitter, and collector current Ic. The Vce and Vge are measured by a high-voltage probe, the Ic is measured by a Rogowski coil, the high-voltage probe and the Rogowski coil are connected to an oscilloscope, the fourth IGBT 4 is connected to the oscilloscope, and the oscilloscope is set. The switching time waveform diagram of the fourth IGBT 4 is obtained through the oscilloscope, and Vce, Vge, Ic, rise time, fall time, turn-on delay time, and turn-off delay time are obtained through the oscilloscope. Then, the extracted dynamic parameters are compared with the rated dynamic parameters (preset evaluation parameters) of the DataSheet of the tested fourth IGBT 4 to judge the state of the tested device at this time, and the state monitoring of the aged IGBT is realized, that is, the IGBT is evaluated.

[0051] When evaluating the IGBT on the Figure 2 inverter side, the situation of the IGBT in the branch of the opposite-side switching component, the evaluation charge-discharge module, and the freewheeling diode used during discharging can be seen in Table 1. Among them, the IGBT in the branch of the switching component is used to represent the branch of the switching component in Table 1.

[0052] Table 1

[0053] Evaluation object Evaluation charge and discharge module Branch of the opposite - side switch component Free - wheeling diode used during discharge First IGBT 1 <![CDATA[Inductor L1]]> Tenth IGBT 10 <![CDATA[Fourth freewheeling diode D4]]> Second IGBT 2 <![CDATA[Inductor L2]]> Eleventh IGBT 11 <![CDATA[Fifth freewheeling diode D5]]> Third IGBT 3 <![CDATA[Inductor L3]]> Twelfth IGBT 12 <![CDATA[Sixth freewheeling diode D6]]> Fourth IGBT 4 <![CDATA[Inductor L1]]> Seventh IGBT 7 <![CDATA[First freewheeling diode D1]]> Fifth IGBT 5 <![CDATA[Inductor L2]]> Eighth IGBT 8 <![CDATA[The second freewheeling diode D2]]> Sixth IGBT 6 <![CDATA[Inductor L3]]> Ninth IGBT 9 <![CDATA[Third freewheeling diode D3]]>

[0054] As can be seen from the above, the technical solution provided by the embodiment of the present invention is an IGBT reliability test method based on the actual working conditions of three-phase photovoltaic grid connection, which has the following characteristics: 1) The inverter side adopts a T-type three-level inverter topology to simulate the three-phase photovoltaic grid-connected inverter topology; 2) The rectifier side selects a three-phase synchronous rectification topology structure to realize the simulation of the three-phase photovoltaic grid-connected working conditions; 3) The DC voltage output by the rectifier side is connected in parallel with the DC voltage input by the inverter side to realize energy feedback and reduce the power demand for the DC power supply; 4) The IGBT double-pulse test is realized by coordinately controlling the switching states of the devices on the rectifier side and the inverter side; 5) The filter inductor is used as the freewheeling inductor for the double-pulse test.

[0055] The technical solution provided by the embodiment of the present invention has the following advantages: 1) By adopting the topology structure of a T-type inverter plus three-phase rectification, the simulation of the actual working conditions of three-phase photovoltaic grid-connected inversion is realized. This method is more convenient and has lower costs; 2) Based on the above topology structure, the IGBT double-pulse test without disassembly is realized by controlling the on-states of the devices on the inverter side and the rectifier side. This method can avoid disassembling the IGBT and is easier to implement.

[0056] Correspondingly, another aspect of the embodiments of the present invention provides a device for evaluating the components in a circuit. The device includes: an evaluation module for evaluating any one of the six component branches in the circuit according to the following, and before the evaluation, the six component branches are in a state of non-conduction in the forward direction: controlling the evaluation component branch to conduct in the forward direction and continue for a first preset time to charge the evaluation charge and discharge module, where the evaluation component branch is the component branch where the evaluated component in the six component branches is located, and the evaluation charge and discharge module is the charge and discharge module connected to the evaluation component branch among the first charge and discharge module, the second charge and discharge module, and the third charge and discharge module. The circuit includes a power supply module, six component branches, a first charge and discharge module, a second charge and discharge module, a third charge and discharge module, and a switch module. The six component branches are combined in pairs and connected through a first connection point, a second connection point, and a third connection point respectively to be connected in series between the two ends of the power supply module. The two ends of the first charge and discharge module are respectively connected to the first connection point and the switch module. The two ends of the second charge and discharge module are respectively connected to the second connection point and the switch module. The two ends of the third charge and discharge module are respectively connected to the third connection point and the switch module. The switch module is located between the two ends of the power supply module. Each component branch in the six component branches includes at least one component. During the forward conduction of the evaluation component branch, the power supply module, the evaluation component branch, the evaluation charge and discharge module, and the switch module form a loop, and the component is an IGBT or a MOSFET; controlling the evaluation component branch to be non-conductive in the forward direction and continue for a second preset time to cause the evaluation charge and discharge module to discharge, where during the non-conduction of the evaluation component branch in the forward direction, the switch module, the evaluation charge and discharge module, and the opposite component branch of the evaluation component branch form a loop, and the opposite component branch of the evaluation component branch is the component branch connected to the evaluation component branch; obtaining the evaluation parameters of the evaluated component, where the evaluation parameters include rise time, fall time, turn-on delay time, and turn-off delay time; and judging the state of the evaluated component according to the obtained evaluation parameters and the preset evaluation parameters to evaluate the evaluated component.

[0057] Optionally, in the embodiments of the present invention, the evaluation module is further configured to: before obtaining the evaluation parameters of the evaluated component, control the evaluation component branch to conduct in the forward direction and continue for a third preset time.

[0058] Optionally, in the embodiments of the present invention, the evaluation module is further configured to: in the case where the six component branches are not in a state of non-conduction in the forward direction before evaluating the evaluated component, control the six component branches to be non-conductive in the forward direction.

[0059] Optionally, in the embodiments of the present invention, the switching module includes six switching component branches. The six switching component branches are combined in pairs and connected through the fourth connection point, the fifth connection point, and the sixth connection point respectively to be connected in series between the two ends of the power supply module. The two ends of the first charge-discharge module are respectively connected to the first connection point and the fourth connection point. The two ends of the second charge-discharge module are respectively connected to the second connection point and the fifth connection point. The two ends of the third charge-discharge module are respectively connected to the third connection point and the sixth connection point. Each switching component branch in the six switching component branches includes at least one switching component, and the switching component is an IGBT or a MOSFET. Before evaluating the component to be evaluated, the six switching component branches are controlled to be non-conductive in the forward direction. The evaluation module is further configured to: when evaluating the component to be evaluated, control the opposite-side switching component branch to be conductive in the forward direction, where the opposite-side switching component branch is the switching component branch in the six switching component branches that is connected to the evaluation charge-discharge module and is located on the different side from the evaluation component branch with respect to the evaluation charge-discharge module.

[0060] Optionally, in the embodiments of the present invention, the component is an IGBT, and the evaluation parameters further include the voltage between the collector and the emitter, the voltage between the gate and the emitter, and the collector current.

[0061] Optionally, in the embodiments of the present invention, when the circuit includes a component branch, the evaluation module controls the component branch to be conductive or non-conductive in the forward direction by applying a pulse to the component in the component branch; and when the circuit includes a switching component branch, the evaluation module controls the switching component branch to be conductive or non-conductive in the forward direction by applying a pulse to the switching component in the switching component branch.

[0062] The specific working principle and benefits of the method for evaluating components in a circuit provided by the embodiments of the present invention are similar to those of the device for evaluating components in a circuit provided by the embodiments of the present invention, and will not be elaborated here.

[0063] In addition, on the other hand, the embodiments of the present invention further provide a circuit, which includes a component, and the component is evaluated according to the method described in the above embodiments.

[0064] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any suitable combination of each specific technical feature. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. But these simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for evaluating components in a circuit, characterized in that, The method includes: For any one of the six component branches in the circuit, perform evaluation according to the following, and before the evaluation, the six component branches are in a state of non-conduction in the forward direction: Control the evaluation component branch to conduct in the forward direction and last for a first preset time to charge the evaluation charge and discharge module. Wherein, the evaluation component branch is the component branch where the component to be evaluated in the six component branches is located, and the evaluation charge and discharge module is the charge and discharge module connected to the evaluation component branch among the first charge and discharge module, the second charge and discharge module, and the third charge and discharge module. The circuit includes a power supply module, the six component branches, the first charge and discharge module, the second charge and discharge module, the third charge and discharge module, and a switch module. The six component branches are combined in pairs and connected through a first connection point, a second connection point, and a third connection point respectively to be in series between the two ends of the power supply module. The two ends of the first charge and discharge module are respectively connected to the first connection point and the switch module. The two ends of the second charge and discharge module are respectively connected to the second connection point and the switch module. The two ends of the third charge and discharge module are respectively connected to the third connection point and the switch module. The switch module is located between the two ends of the power supply module. Each component branch in the six component branches includes at least one of the components. During the forward conduction of the evaluation component branch, the power supply module, the evaluation component branch, the evaluation charge and discharge module, and the switch module form a loop. The component is an IGBT or a MOSFET; Control the evaluation component branch to be non-conductive in the forward direction and last for a second preset time to cause the evaluation charge and discharge module to discharge. Wherein, during the non-conduction of the evaluation component branch in the forward direction, the switch module, the evaluation charge and discharge module, and the opposite component branch of the evaluation component branch form a loop. The opposite component branch of the evaluation component branch is the component branch connected to the evaluation component branch; Obtain the evaluation parameters of the component to be evaluated. Wherein, the evaluation parameters include rise time, fall time, turn-on delay time, and turn-off delay time; and Judge the state of the component to be evaluated according to the obtained evaluation parameters and the preset evaluation parameters to evaluate the component to be evaluated.

2. The method according to claim 1, characterized in that, Before obtaining the evaluation parameters of the component to be evaluated, the method further includes: Control the evaluation component branch to conduct in the forward direction and last for a third preset time.

3. The method according to claim 1, characterized in that, In the case where the six component branches are not in a state of non-conduction in the forward direction before evaluating the component to be evaluated, the method further includes: Control the six component branches to be non-conductive in the forward direction.

4. The method according to claim 1, characterized in that, The switch module includes six switch component branches. The six switch component branches are combined in pairs and connected through a fourth connection point, a fifth connection point, and a sixth connection point respectively to be connected in series between both ends of the power supply module. Both ends of the first charge and discharge module are connected to the first connection point and the fourth connection point respectively. Both ends of the second charge and discharge module are connected to the second connection point and the fifth connection point respectively. Both ends of the third charge and discharge module are connected to the third connection point and the sixth connection point respectively. Each switch component branch in the six switch component branches includes at least one switch component. The switch component is an IGBT or a MOSFET. Before evaluating the component to be evaluated, control the six switch component branches to be non-conducting in the forward direction. The method further includes: When evaluating the component to be evaluated, control the opposite-side switch component branch to be conducting in the forward direction, where the opposite-side switch component branch is the switch component branch in the six switch component branches that is connected to the evaluation charge and discharge module and is on the different side of the evaluation charge and discharge module from the evaluation component branch.

5. The method according to claim 1, characterized in that, The component is an IGBT, and the evaluation parameters further include the voltage between the collector and the emitter, the voltage between the gate and the emitter, and the collector current.

6. The method according to claim 4, characterized in that, When the circuit includes a component branch, controlling the component branch to be conducting or non-conducting in the forward direction is achieved by applying a pulse to the component in the component branch; and When the circuit includes a switch component branch, controlling the switch component branch to be conducting or non-conducting in the forward direction is achieved by applying a pulse to the switch component in the switch component branch.

7. A device for evaluating components in a circuit, characterized in that, The device includes: An evaluation module for evaluating any one of the six component branches in the circuit for the component according to the following, and the six component branches are in a non-conducting state in the forward direction before the evaluation: Control the component branch of the evaluation group to conduct forward and continue for a first preset time to charge the evaluation charge and discharge module. Among them, the component branch of the evaluation group is the component branch where the evaluated component is located among the six component branches, and the evaluation charge and discharge module is the charge and discharge module connected to the component branch of the evaluation group among the first charge and discharge module, the second charge and discharge module, and the third charge and discharge module. The circuit includes a power supply module, the six component branches, the first charge and discharge module, the second charge and discharge module, the third charge and discharge module, and a switch module. The six component branches are combined in pairs and connected through a first connection point, a second connection point, and a third connection point respectively to be connected in series between the two ends of the power supply module. The two ends of the first charge and discharge module are respectively connected to the first connection point and the switch module. The two ends of the second charge and discharge module are respectively connected to the second connection point and the switch module. The two ends of the third charge and discharge module are respectively connected to the third connection point and the switch module. The switch module is located between the two ends of the power supply module. Each component branch of the six component branches includes at least one of the components. During the forward conduction of the component branch of the evaluation group, the power supply module, the component branch of the evaluation group, the evaluation charge and discharge module, and the switch module form a loop. The component is an IGBT or a MOSFET; Control the component branch of the evaluation group not to conduct forward and continue for a second preset time to cause the evaluation charge and discharge module to discharge. Among them, during the period when the component branch of the evaluation group does not conduct forward, the switch module, the evaluation charge and discharge module, and the opposite component branch of the component branch of the evaluation group form a loop. The opposite component branch of the component branch of the evaluation group is the component branch connected to the component branch of the evaluation group; Obtain the evaluation parameters of the evaluated component. Among them, the evaluation parameters include rise time, fall time, turn-on delay time, and turn-off delay time; and Judge the state of the evaluated component according to the obtained evaluation parameters and the preset evaluation parameters to evaluate the evaluated component.

8. The device according to claim 7, characterized in that, The evaluation module is further configured to: before obtaining the evaluation parameters of the evaluated component, control the component branch of the evaluation group to conduct forward and continue for a third preset time.

9. The device according to claim 7, characterized in that, The evaluation module is further configured to: control the six component branches not to conduct forward when the six component branches are not in the state of not conducting forward before evaluating the evaluated component.

10. The device according to claim 7, characterized in that, The switch module includes six switch component branches. The six switch component branches are combined in pairs and connected through a fourth connection point, a fifth connection point, and a sixth connection point respectively to be connected in series between both ends of the power supply module. Both ends of the first charge and discharge module are connected to the first connection point and the fourth connection point respectively. Both ends of the second charge and discharge module are connected to the second connection point and the fifth connection point respectively. Both ends of the third charge and discharge module are connected to the third connection point and the sixth connection point respectively. Each switch component branch in the six switch component branches includes at least one switch component. The switch component is an IGBT or a MOSFET. Before evaluating the component to be evaluated, the six switch component branches are controlled to be non-conductive in the forward direction. The evaluation module is further configured to: When evaluating the component to be evaluated, control the opposite-side switch component branch to be conductive in the forward direction, where the opposite-side switch component branch is the switch component branch in the six switch component branches that is connected to the evaluation charge and discharge module and is located on a different side from the evaluation component branch with respect to the evaluation charge and discharge module.

11. The device according to claim 7, characterized in that, The component is an IGBT, and the evaluation parameters further include the voltage between the collector and the emitter, the voltage between the gate and the emitter, and the collector current.

12. The device according to claim 10, characterized in that, When the circuit includes a component branch, the evaluation module controls the component branch to be conductive or non-conductive in the forward direction by applying a pulse to the component in the component branch; and When the circuit includes a switch component branch, the evaluation module controls the switch component branch to be conductive or non-conductive in the forward direction by applying a pulse to the switch component in the switch component branch.

13. A circuit, characterized in that, The circuit includes a component, and the component is evaluated according to the method described in any one of claims 1-6.

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