Fault Determination Method and System for Inverter IGBT Module Based on Condition Monitoring

Abstract

The present invention discloses a method and system for fault determination of an inverter IGBT module based on condition monitoring, belonging to the technical field of reliability of core devices of power electronic equipment, including: measuring the output characteristic curve of the inverter IGBT to determine the intersection point current value I int ; implementing a fault monitoring strategy, performing IGBT aging monitoring at the idle time of the IGBT, and performing IGBT fault monitoring at the working time of the IGBT; injecting a test current equal to the intersection point current value into the inverter IGBT to measure the corresponding conduction voltage drop V int and judging the aging failure of the IGBT based on this; detecting the current zero-crossing time T p of the inverter IGBT through a timing algorithm integrated in the inverter controller and judging the fault failure of the IGBT based on this; finally, comprehensively considering the IGBT aging index and the fault index to accurately determine the cause of the IGBT fault.

Description

Technical Field

[0001] The present invention belongs to the technical field of the reliability of core devices of power electronic equipment, and more specifically, relates to a method and system for accurately determining the cause of failure of an inverter IGBT module based on condition monitoring. Background Art

[0002] In recent years, the application fields of inverters have been continuously expanding, such as in solar power generation, electric vehicles, and aerospace power systems. Among them, due to the advantages of large input impedance, small drive power, simple control circuit, small switching loss, and high operating frequency of IGBT power modules compared with other power electronic devices, they have been widely used in inverters. The working conditions in these application fields are harsh and strict requirements are imposed on the reliability of IGBTs.

[0003] Inverter IGBT modules usually work in complex and harsh environments and are prone to failure. The causes of IGBT failures are mainly divided into two categories: one is caused by the inside of the IGBT, that is, the IGBT itself ages and fails, such as the bonding wire breakage and solder layer detachment caused by thermal stress shock; the other is caused by the outside of the IGBT, that is, the IGBT is not aged and the actual failure location lies in other external circuits, such as drive circuit damage, drive signal loss, PCB board failure, etc. IGBT external failures are sudden failures that are difficult to predict and are manifested as immediate failures. IGBT aging failure is a long-term aging failure process, so this process is relatively slow, with predictability and inevitability. However, if no intervention is carried out, it will eventually lead to the failure of the IGBT. If the above failures occur in the IGBT power module, it will inevitably seriously affect or even damage the normal operation of the inverter, and may even cause accidents such as power outages, operation termination, and traffic paralysis, thus bringing huge economic losses.

[0004] Existing fault diagnosis methods can only determine that the IGBT has failed, but cannot distinguish whether the failure is caused by IGBT internal aging or external circuits, which causes great trouble to the maintenance and operation and maintenance of inverter IGBT modules. Summary of the Invention

[0005] In view of the above defects or improvement requirements of the prior art, the present invention proposes a method and system for accurately determining the failure of an inverter IGBT module based on condition monitoring, which can accurately determine the cause of IGBT failure.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided a method for determining the failure of an inverter IGBT module based on condition monitoring, including:

[0007] Measuring the output characteristic curve of the inverter IGBT to determine the intersection current value;

[0008] During the idle time of the IGBT, IGBT aging monitoring is implemented; during the working time of the IGBT, IGBT fault monitoring is implemented.

[0009] When implementing IGBT aging monitoring, a test current equal to the intersection current value is injected into the inverter IGBT, and the corresponding conduction voltage drop is measured. The conduction voltage drop is used as the IGBT aging monitoring parameter, and the conduction voltage drop is compared with the aging threshold to give the corresponding IGBT aging index.

[0010] When implementing IGBT fault monitoring, the current zero-crossing time of the inverter IGBT is detected. The current zero-crossing time is used as the IGBT fault monitoring parameter, and the current zero-crossing time is compared with the fault threshold to give the corresponding IGBT fault index.

[0011] Taking into account the IGBT aging index and the IGBT fault index comprehensively, the cause of the IGBT fault is accurately determined.

[0012] In some optional implementation schemes, the implementation of IGBT aging monitoring during the idle time of the IGBT and the implementation of IGBT fault monitoring during the working time of the IGBT include:

[0013] When the drive signal of the IGBT is at a low level or there is no signal, it is considered the idle time of the IGBT; during the idle time of the IGBT, IGBT aging monitoring is implemented.

[0014] When the drive signal of the IGBT is at a high level, it is considered the working time of the IGBT; during the working time of the IGBT, IGBT fault monitoring is implemented.

[0015] In some optional implementation schemes, the comparison of the conduction voltage drop with the aging threshold to give the corresponding IGBT aging index includes:

[0016] During the process of IGBT aging monitoring, when the conduction voltage drop exceeds the aging threshold, set the IGBT aging index A n to m, otherwise set A n to n, where the aging threshold is obtained by performing aging tests on IGBT modules of the same type after injecting the same magnitude of current.

[0017] In some optional implementation schemes, the comparison of the current zero-crossing time with the fault threshold to give the corresponding IGBT fault index includes:

[0018] During the process of IGBT fault monitoring, when the current zero-crossing time exceeds the fault threshold, set the IGBT fault index F n to p, otherwise set F n to q, where the fault threshold is obtained by testing the inverter of the same type under the same working conditions.

[0019] In some alternative embodiments, comprehensively considering the IGBT aging index and the IGBT fault index to accurately determine the cause of IGBT fault, including:

[0020] When A n = n and F n = q, it is determined that the IGBT module of the inverter has no fault;

[0021] When A n = n and F n = p, it is determined that the fault of the IGBT module of the inverter is external and has nothing to do with the IGBT module itself;

[0022] When A n = m and F n = q, it is determined that the IGBT module of the inverter is in the critical state of aging failure;

[0023] When A n = m and F n = p, it is determined that the fault of the IGBT module of the inverter is internal.

[0024] According to another aspect of the present invention, there is provided a fault determination system for an IGBT module of an inverter based on state monitoring, including:

[0025] A fault monitoring and control module, configured to trigger IGBT aging monitoring at the idle time of the IGBT; and trigger IGBT fault monitoring at the working time of the IGBT;

[0026] An aging monitoring module, configured to inject a test current equal to the intersection current value into the IGBT of the inverter when implementing IGBT aging monitoring, measure the corresponding conduction voltage drop, use the conduction voltage drop as the IGBT aging monitoring parameter, and compare the conduction voltage drop with the aging threshold to give the corresponding IGBT aging index;

[0027] A fault monitoring module, configured to monitor the fault state of the IGBT module, collect the fault monitoring parameter of the current zero-crossing time, and compare the current zero-crossing time with the fault threshold to give the corresponding IGBT fault index;

[0028] An accurate fault judgment module, configured to comprehensively consider the IGBT aging index and the IGBT fault index to accurately determine the cause of IGBT fault.

[0029] In some alternative embodiments, the fault monitoring and control module is configured to determine the idle time of the IGBT when the driving signal of the IGBT is at a low level or there is no signal; implement IGBT aging monitoring at the idle time of the IGBT; determine the working time of the IGBT when the driving signal of the IGBT is at a high level; and implement IGBT fault monitoring at the working time of the IGBT.

[0030] In some alternative embodiments, the aging monitoring module is configured to inject a test current equal to the intersection current value into the inverter IGBT when implementing IGBT aging monitoring, measure the corresponding conduction voltage drop, use the conduction voltage drop as the IGBT aging monitoring parameter, and if the conduction voltage drop exceeds the aging threshold, set the IGBT aging index A n to m, otherwise A n is set to n, where the aging threshold is obtained by performing an aging test after injecting the same magnitude of current into IGBT modules of the same type.

[0031] In some alternative embodiments, the fault monitoring module is configured to monitor the fault status of the IGBT module, collect the fault monitoring parameter of the current zero-crossing time, and if the current zero-crossing time exceeds the fault threshold, set the IGBT fault index F n to p, otherwise F n is set to q, where the fault threshold is obtained by testing the same type of inverter under the same operating conditions.

[0032] In some alternative embodiments, the precise fault judgment module is configured to, when A n = n and F n = q, determine that the inverter IGBT module has no fault; when A n = n and F n = p, determine that the fault of the inverter IGBT module is external and has nothing to do with the IGBT module itself; when A n = m and F n = q, determine that the inverter IGBT module is in the critical state of aging failure; when A n = m and F n = p, determine that the fault of the inverter IGBT module is internal.

[0033] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0034] The present invention determines the intersection current value I int by measuring the output characteristic curve of the inverter IGBT; executes a fault monitoring strategy, implements IGBT aging monitoring at the idle time of the IGBT, implements IGBT fault monitoring at the working time of the IGBT; injects a test current equal to the intersection current value into the inverter IGBT, measures the corresponding conduction voltage drop V int , and determines the aging failure of the IGBT accordingly; detects the current zero-crossing time T p of the inverter IGBT through a drive fault diagnosis algorithm integrated in the inverter controller, and determine the fault failure of the IGBT based on this; finally, comprehensively consider the IGBT aging index and the fault index to accurately determine the cause of the IGBT fault. By comprehensively considering the internal and external factors of the IGBT module on its fault, the specific cause of the IGBT module failure can be accurately identified, that is, whether the fault comes from inside or outside the module. It is convenient to carry out targeted maintenance when the system can be shut down, which is conducive to rapid maintenance and shortening the downtime, and improving the reliability of the inverter. And without affecting the working state of the inverter, the monitoring of the entire life cycle (health, aging, fault) of the IGBT module of the inverter can be realized, and the feasibility of implementation is relatively high. Brief Description of the Drawings

[0035] Figure 1 is a schematic flow chart of a method for determining the fault of an IGBT module of an inverter based on condition monitoring provided by an embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of a system for determining the fault of an IGBT module of an inverter based on condition monitoring provided by an embodiment of the present invention. Detailed Embodiment

[0037] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] As Figure 1 shown is a schematic flow chart of a method for determining the fault of an IGBT module of an inverter based on condition monitoring provided by an embodiment of the present invention, including the following steps:

[0039] S1: Measure the output characteristic curve of the IGBT module of the inverter to determine the intersection current value I int ;

[0040] S2: Execute the fault monitoring strategy. When the IGBT is idle, perform IGBT aging monitoring; when the IGBT is working, perform IGBT fault monitoring;

[0041] In the embodiment of the present invention, step S2 can be implemented in the following manner:

[0042] S2.1: When the driving signal of the IGBT is at a low level V LWhen there is no signal, it is determined as the idle time of the IGBT; during the idle time of the IGBT, IGBT aging monitoring is implemented. Since the designed life of the IGBT module is up to several decades and its aging process is very long, continuous long-term aging monitoring is not conducive to implementation in actual engineering. In addition, the working characteristics of the inverter IGBT itself determine that there are many idle times in the IGBT module (including the time when the IGBT does not work in the redundant working state and the maintenance state). Injecting a test current into it for aging monitoring during the idle time not only meets the observation requirements for the aging state of the IGBT itself, but also does not interfere with the normal operation of the inverter, and it is more economical and feasible.

[0043] S2.2: When the driving signal of the IGBT is at the high level V H it is determined as the working time of the IGBT; during the working time of the IGBT, IGBT fault monitoring is implemented; the zero-crossing time T p of the current of the inverter IGBT module is detected through the diagnostic algorithm integrated in the controller, and the open-circuit fault failure of the IGBT is judged accordingly. This method is integrated into the driver of the inverter itself, without increasing additional hardware costs and without interfering with the working state.

[0044] S3: Inject a test current equal to the intersection current value into the inverter IGBT, and measure its corresponding conduction voltage drop V int as the aging monitoring parameter of the IGBT, and compare it with the aging threshold V a to give the corresponding aging index A n ;

[0045] During the IGBT aging monitoring process, when the aging monitoring parameter V int exceeds the aging threshold V a the IGBT aging index A n is set to 1, otherwise A n is set to 0; it should be noted that the aging threshold V a is obtained in advance by performing an aging test after injecting the same magnitude of current into IGBT modules of the same type.

[0046] S4: Detect the zero-crossing time T p of the current of the inverter IGBT through the diagnostic algorithm integrated in the controller, and use this as the fault monitoring parameter of the IGBT, and compare it with the fault threshold T f to give the corresponding IGBT fault index F n ;

[0047] Among them, the diagnostic algorithm can adopt the algorithm for detecting the zero-crossing time T p of the inverter IGBT in the prior art, and the embodiment of the present invention does not make a unique limitation.

[0048] During the process of IGBT fault monitoring, the fault monitoring parameter T p exceeds the fault threshold T f , set the IGBT fault indicator F n to 1, otherwise set F n to 0; it should be noted that the fault threshold T f is obtained in advance by testing inverters of the same model under the same working conditions.

[0049] S5: Comprehensively consider the IGBT aging index and the fault index to accurately determine the cause of the IGBT fault.

[0050] In the embodiment of the present invention, step S5 can be implemented in the following manner:

[0051] S5.1: When A n = 0 and F n = 0, it is determined that the IGBT module of the inverter has not failed;

[0052] S5.2: When A n = 0 and F n = 1, it is determined that the fault of the IGBT module of the inverter is external, that is, the fault is caused by the failure of the IGBT external drive, PCB board, etc., and has nothing to do with the IGBT module itself;

[0053] S5.3: When A n = 1 and F n = 0, it is determined that the IGBT module of the inverter is in the critical state of aging failure; if it continues to work, a fault will occur soon;

[0054] S5.4: When A n = 1 and F n = 1, it is determined that the fault of the IGBT module of the inverter is internal, that is, the fault is caused by the aging failure of the IGBT itself.

[0055] Among them, the specific values assigned to A n and F n are not limited to 0 or 1, and can also be other values, as long as they correspond to the assignment in the determination process of step S5. The embodiment of the present invention does not make a uniqueness limitation.

[0056] In order to implement the method of the above embodiment, in another embodiment of the present invention, a precise determination system for the fault of the IGBT module of the inverter based on state monitoring is also provided, as Figure 2 shown, the system includes:

[0057] A fault monitoring and control module, which is used to execute the fault monitoring strategy, trigger IGBT aging monitoring at the idle time of the IGBT, and trigger IGBT fault monitoring at the working time of the IGBT;

[0058] An aging monitoring module, which is used to inject a test current equal to the intersection current value into the IGBT of the inverter when implementing IGBT aging monitoring, and measure the corresponding conduction voltage drop V int , and use this as the aging monitoring parameter of the IGBT, and compare it with the aging threshold V a to give the corresponding aging index A n ;

[0059] A fault monitoring module, which is used to monitor the fault status of the IGBT module, collect the fault monitoring parameter current zero-crossing time T p , and compare it with the fault threshold T f to give the corresponding IGBT fault index F n ;

[0060] An accurate fault judgment module, which is used to comprehensively consider the IGBT aging index A n and the fault index F n to accurately determine the cause of the IGBT fault.

[0061] Among them, the specific implementation manners of each module can refer to the description of the method embodiments above, and will not be repeated in this embodiment.

[0062] It should be noted that according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, or two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0063] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for fault determination of an inverter IGBT module based on condition monitoring, characterized in that, it includes: Measuring the output characteristic curve of the inverter IGBT to determine the intersection current value; Implementing IGBT aging monitoring at the idle time of the IGBT; Implementing IGBT fault monitoring at the working time of the IGBT; When implementing IGBT aging monitoring, injecting a test current equal to the intersection current value into the inverter IGBT, measuring its corresponding conduction voltage drop, using the conduction voltage drop as the IGBT aging monitoring parameter, and comparing the conduction voltage drop with the aging threshold to give the corresponding IGBT aging index; When implementing IGBT fault monitoring, detecting the current zero-crossing time of the inverter IGBT, using the current zero-crossing time as the IGBT fault monitoring parameter, and comparing the current zero-crossing time with the fault threshold to give the corresponding IGBT fault index; Comprehensively considering the IGBT aging index and the IGBT fault index to accurately determine the IGBT fault cause; The comparing the conduction voltage drop with the aging threshold to give the corresponding IGBT aging index includes: During the IGBT aging monitoring process, when the conduction voltage drop exceeds the aging threshold, set the IGBT aging index A n to m, otherwise set A n to n, where the aging threshold is obtained through aging tests after injecting the same magnitude of current into IGBT modules of the same model; The comparing the current zero-crossing time with the fault threshold to give the corresponding IGBT fault index includes: During the IGBT fault monitoring process, if the current zero-crossing time exceeds the fault threshold, set the IGBT fault indicator F n to p, otherwise set F n to q, where the fault threshold is obtained by testing inverters of the same model under the same working conditions; The comprehensively considering the IGBT aging index and the IGBT fault index to accurately determine the IGBT fault cause includes: When A n = n and F n = q, it is determined that the inverter IGBT module has not failed; When A n = n and F n = p, it is determined that the fault of the inverter IGBT module is external and has nothing to do with the IGBT module itself; When A n = m and F n = q, it is determined that the inverter IGBT module is in the critical state of aging failure; When A n = m and F n = p, it is determined that the fault of the inverter IGBT module is internal.

2. The method according to claim 1, characterized in that, the implementing IGBT aging monitoring at the idle time of the IGBT; the implementing IGBT fault monitoring at the working time of the IGBT includes: When the driving signal of the IGBT is low level or no signal, it is determined as the idle time of the IGBT; at the idle time of the IGBT, implement IGBT aging monitoring; When the driving signal of the IGBT is high level, it is determined as the working time of the IGBT; at the working time of the IGBT, implement IGBT fault monitoring.

3. A system for fault determination of an inverter IGBT module based on condition monitoring, characterized in that, it includes: A fault monitoring control module for triggering IGBT aging monitoring at the idle time of the IGBT; Triggering IGBT fault monitoring at the working time of the IGBT; An aging monitoring module for injecting a test current equal to the intersection current value into the inverter IGBT when implementing IGBT aging monitoring, measuring its corresponding conduction voltage drop, using the conduction voltage drop as the IGBT aging monitoring parameter, and comparing the conduction voltage drop with the aging threshold to give the corresponding IGBT aging index; A fault monitoring module for monitoring the fault state of the IGBT module, collecting the fault monitoring parameter current zero-crossing time, and comparing the current zero-crossing time with the fault threshold to give the corresponding IGBT fault index; An accurate fault judgment module for comprehensively considering the IGBT aging index and the IGBT fault index to accurately determine the IGBT fault cause; The aging monitoring module is used to inject a test current equal to the intersection current value into the inverter IGBT when implementing IGBT aging monitoring, measure the corresponding conduction voltage drop, and use the conduction voltage drop as the IGBT aging monitoring parameter. If the conduction voltage drop exceeds the aging threshold, set the IGBT aging index to A n set to m, otherwise A n set to n, where the aging threshold is obtained by performing an aging test after injecting the same magnitude of current into IGBT modules of the same type; The fault monitoring module is used to monitor the fault status of the IGBT module, collect the fault monitoring parameter of the current zero-crossing time. If the current zero-crossing time exceeds the fault threshold, set the IGBT fault index F n to p, otherwise set F n to q. The fault threshold is obtained by testing inverters of the same model under the same working conditions; The precise fault judgment module is used to determine that the IGBT module of the inverter has no fault when A n = n and F n = q; when A n = n and F n = p, it is determined that the fault of the IGBT module of the inverter is external and has nothing to do with the IGBT module itself; when A n = m and F n = q, it is determined that the IGBT module of the inverter is in the critical state of aging failure; when A n = m and F n = p, it is determined that the fault of the IGBT module of the inverter is internal.

4. The system according to claim 3, characterized in that, The fault monitoring and control module is used to determine the idle time of the IGBT when the driving signal of the IGBT is at a low level or there is no signal; during the idle time of the IGBT, implement IGBT aging monitoring; when the driving signal of the IGBT is at a high level, determine it as the working time of the IGBT; during the working time of the IGBT, implement IGBT fault monitoring.

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