Method for monitoring the state of a power electronics device, computer program and computer-readable medium

Abstract

The invention relates to a method for monitoring the state of a power electronics device (1), in particular a converter, having two or more components (2-6), of which at least one is provided by a semiconductor component (2, 3), characterised in that - an energy efficiency of the power electronics device (1) is determined for at least one observation time, in particular for at least two different observation times, wherein the energy efficiency for the one or the respective observation time is determined on the basis of one or more measurement values captured metrologically for the power electronics device (1), in particular in and / or on the power electronics device (1) and / or at the one or the respective observation time; - the state, in particular an ageing process which has occurred, of the power electronics device (1) is inferred from the energy efficiency determined for the observation time, in particular from the energy efficiencies determined for the two or more observation times. The invention also relates to a computer program and a computer-readable medium.

Description

[0001] Description

[0002] Method for monitoring the state of a power electronic device, computer program and computer-readable medium

[0003] The invention relates to a method for monitoring the state of a power electronic device, in particular a converter, having two or more components, at least one of which is a semiconductor component. Furthermore, the invention relates to a computer program and a computer-readable medium.

[0004] DE 10 2015 225909 A1 discloses a method for detecting aging of a power electronic device comprising at least one semiconductor component, the method comprising the following steps: providing an excitation signal which is designed to cause an at least approximately half-sinusoidal excitation current to flow through the semiconductor component in order to introduce power loss into the semiconductor component; reading in a temperature signal which depicts a temporal profile of the temperature of the semiconductor component; and determining an aging value representing the aging of the power electronic device using the temperature signal.

[0005] Power electronic devices, which can be converters, for example, are subject to various aging processes that can affect safe operation. Power electronic devices typically comprise multiple components, one or more of which are semiconductor devices. The semiconductor components present in power electronic devices are subject to aging through various mechanisms. For example, so-called bond wire lifting, aging of solder connections, or direct copper bonded cracks (DCB cracks) frequently occur within semiconductor devices. These aging mechanisms inevitably lead to the functional failure of the affected semiconductor component(s) and subsequently also of the power electronic device.

[0006] The applicant is aware of various types of condition monitoring of semiconductor components based on the direct measurement of electrical or thermal variables of the semiconductor components. These have proven to be effective in principle. However, there is still a need for alternative condition monitoring methods. It is an object of the present invention to provide an alternative method of the type mentioned above that is comparatively easy to implement and enables reliable condition monitoring.

[0007] This object is achieved by a method for monitoring the state of a power electronic device, in particular a converter, with two or more components, of which at least one is a semiconductor component, characterized in that

[0008] - an energy efficiency of the power electronic device is determined for at least one observation time, in particular for at least two different observation times, wherein the determination of the energy efficiency for the respective observation time is carried out on the basis of one or more measured values ​​recorded for the power electronic device, in particular in and / or on the power electronic device and / or at the respective observation time, and

[0009] - conclusions are drawn about the condition of the power electronic device, in particular about an ageing process that has occurred, from the energy efficiency determined for the time under consideration, in particular from the energy efficiencies determined for the two or more times under consideration.

[0010] In other words, the present invention is based on the fundamental idea of ​​determining the energy efficiency of a power electronic device as a whole and using it for condition assessment and thus condition monitoring. Energy efficiency can be determined at any operating point of the power electronic device, which can also be referred to as a power electronic system. If, based on the inventive evaluation of the energy efficiency of the overall device at one or more observation points, an age-related change in components is observed, appropriate measures can be initiated. For example, at least one warning can be issued and / or maintenance of at least one component can be scheduled.

[0011] One embodiment of the method according to the invention is characterized in that, if the or at least one determined energy efficiency lies below a predetermined threshold value, it is concluded that the power electronic device has aged, in particular that it has an age-related defect. In particular, it can be concluded that at least one component of the power electronic device, preferably at least one semiconductor component thereof, has aged. The predetermined threshold value can, for example, have been derived by calculation and / or previously determined by measurements.

[0012] It should be noted that, alternatively or in addition to a fixed difference threshold, the first derivative of the difference over several points in time can also represent a possible evaluation variable.

[0013] The power electronic device comprises several components, one or more of which are semiconductor components. Purely exemplary of semiconductor components, of which the monitored power electronic device may comprise one or more, are IBGTs (insulated gate bipolar transistors) and / or MOSFETs (metal oxide semiconductor field-effect transistors) and / or diodes. In addition to one or more semiconductor components, the power electronic device will generally comprise further components. Examples of further components of power electronic devices include at least one capacitor, at least one fan, and at least one controller.

[0014] According to the invention, one or more measured values ​​from the power electronic device are used to determine the overall energy efficiency at one or more observation points in time. It should be noted that the metrological recording of the measured values ​​can be a component of the method according to the invention, but does not have to be. For example, existing measured values ​​recorded before the method according to the invention was carried out can also be accessed, in particular measured values ​​that are already available for another purpose and stored at any location. Measuring devices, such as sensors, that are already present as standard in the power electronic devices can be used or have been used to record the measured values.Accordingly, the implementation of the method according to the invention does not require any additional design effort for the power electronic device.

[0015] The measured value(s) are metrologically recorded values ​​of at least one physical quantity, for example at least one electrical quantity and / or at least one thermal quantity of the power electronic device. In particular, they are one or more measured values ​​of one or more physical quantities that relate to the power electronic device as a whole, in other words the entire power electronic device. These can, for example, be current and / or voltage and / or temperature measured values ​​of the power electronic device that are or were recorded on and / or in the power electronic device. In principle, it can be sufficient if only one measured value of a physical quantity is used to determine the energy efficiency at the various observation times.However, it is of course also possible to use measured values ​​from more than one physical quantity to determine energy efficiency at a given point in time, for example a current measured value and a voltage measured value.

[0016] The determination of energy efficiency for the observation point(s) can be carried out, in particular, by determining, for example, calculating, a quantity representing the respective energy efficiency. Purely as an example of a quantity representing the energy efficiency of a power electronic device at a specific point in time, the power loss of the power electronic device at that point in time is mentioned. An age-related change, in particular an increase in power loss over time, corresponds to an age-related decrease or represents an age-related decrease in energy efficiency.

[0017] A value representing energy efficiency can, for example, also be given by a temperature difference, such as the difference between the temperature of the supply and exhaust air of an air-cooled power electronic device or the difference between the inlet and outlet temperatures of a liquid cooling medium for cooling the power electronic device.

[0018] The aging of the semiconductor component(s) of the power electronic device typically leads to a change, particularly increased power loss and temperature in the overall device, in other words, in the overall system. This change, particularly increased power loss, can arise, for example, from an increased internal resistance in a module or component (e.g., due to the loss of bond connections) or from operating the semiconductors at higher temperatures (e.g., due to higher thermal resistance due to solder damage).

[0019] The method according to the invention has proven to be particularly suitable for monitoring the condition of converters. For example, at least one AC / DC converter and / or at least one DC / DC converter and / or at least one DC / AC converter and / or at least one AC / AC converter can be monitored. However, it can also be used for other types of power electronic devices. Solid-state circuit breakers are mentioned purely as an example. While it is generally sufficient to determine the energy efficiency for one observation point in time and use it for the condition assessment, it has proven advantageous to base it on more than one observation point in time.It can thus be provided that the energy efficiency is determined for at least two observation points in time and that the energy efficiencies associated with the different observation points in time are compared with each other, and that the condition, in particular an ageing process that has occurred, of the power electronic device is determined based on the comparison of the energy efficiencies.

[0020] If two different points in time are considered, a change over time becomes observable. The different points in time are different and separated in time.

[0021] It is of course possible, and depending on the application, appropriate, to determine energy efficiency for more than two observation points in time. This can be done repeatedly during the operation of the power electronic device, for example, hourly, daily, weekly, monthly, or at other, arbitrary intervals. Irregular intervals are also possible. Observation or monitoring of energy efficiency over the life cycle of the power electronic device is also possible.

[0022] If more than two observation points are used, it is preferable to compare at least the energy efficiencies of immediately consecutive observation points. This is particularly important in order to be able to draw conclusions about the state or a change in state of the device.

[0023] The comparison of the energy efficiencies of two observation points in time can, for example, include or be carried out by calculating the difference between the energy efficiencies of the two or, in the case of several, two observation points in time.

[0024] If the comparison of the energy efficiencies associated with two or more different observation points in time reveals that the energy efficiency at a second, later observation point in time is or was lower than at a first, earlier observation point in time, it is concluded in an advantageous embodiment that the power electronic device has aged, in particular has an age-related effect, such as a defect. In particular, it can be concluded that at least one component of the power electronic device, preferably at least one semiconductor component thereof, has aged. In this case, it can be based on the fact that the energy efficiency at the second, later observation point in time is or was lower by a predetermined threshold value than at the first, earlier observation point in time.

[0025] It can be provided that, based on the assumption of an age-related change in condition, in particular based on the assumption of an age-related defect, at least one component of the power electronic device is serviced or replaced, or such service or replacement is scheduled. This can prevent unplanned failures and ensure safe operation with a particularly high level of reliability.

[0026] It is preferable that the energy efficiencies associated with the different observation times relate to the same operating points of the power electronic device. In this case, the energy efficiencies exhibit no deviations due to different operating points and are directly comparable. However, it is not mandatory that the same operating points be considered. If they are not the same, an adjustment or evaluation can be carried out, for example, using at least one suitable algorithm, which is expediently based on the properties of the components.

[0027] The recording of the measured values ​​on the basis of which the energy efficiencies are determined for the various points in time is or was carried out in an appropriate manner at the same operating points or for the same operating points.

[0028] Furthermore, it may be assumed that the power electronic device has operated for different periods at the various points in time. It may also be stipulated that one of the points in time is before the power electronic device was first put into operation.

[0029] It has proven particularly suitable if, in the case where energy efficiencies are determined for more than one observation point in time, one of the observation points, specifically the first observation point in time, relates to a non-aged state of the power electronic device. In other words, the energy efficiency is then initially determined for the non-aged state of the power electronic device, with which a comparison can then be made. For example, the first observation point in time can be (near) the end of a production process for the power electronic device. Preferably, a first observation point in time lies a product-specific, defined period after the completion of a production process for the power electronic device.

[0030] Starting from the initial energy efficiency, which is characteristic of the power electronic device in its non-aged state, changes over time, in particular the operating cycle, can be observed in a particularly suitable manner.

[0031] Based on the initial energy efficiency, observed changes can also be particularly well qualified, for example, using at least one suitable algorithm, in order to be able to assign at least one physical aging process to the change(s). This can then also help in identifying the component(s) affected by the aging process(es).

[0032] A particularly advantageous embodiment of the method according to the invention is characterized in that it is determined which component(s) of the power electronic device is / are affected by aging. For this purpose, at least one suitable algorithm can be used, for example.

[0033] Alternatively or additionally, it is possible to use at least one component temperature measurement of at least one component of the power electronic device. Purely by way of example, after the comparison of the energy efficiency of at least two observation points in time has shown that this has deteriorated over time and an age-related effect, in particular an age-related defect, is assumed, temperature measurement values ​​of one or more components of the power electronic device are recorded, considered or used. As a rule, power electronic devices have sensors as standard, by means of which the temperature of individual components is recorded during operation. Component temperature measurement values ​​are therefore usually available anyway, so that no additional effort is required. If, for example,If it turns out that one or more components, in particular one or more semiconductor components, has or have had an elevated temperature, it is preferably assumed that this component or these components have an age-related effect, in particular a defect. Affected components can, for example, have a changed, in particular increased, power loss and thus temperature compared to other, unaffected components. Alternatively or additionally, it is possible for an analysis operation of the power electronic device to be carried out for this purpose. This is expediently carried out after the condition assessment, in particular after the determination or assumption that an age-related effect, in particular a defect, exists in the power electronic device.During analysis, at least one operating parameter of at least one component of the power electronic device is expediently changed in a targeted manner to determine whether this at least one component of the power electronic device is affected by aging, in particular whether it has undergone an aging process that affects energy efficiency. Additional test or operating scenarios can be used to more precisely identify or exclude a component affected by aging. Purely as an example, the switching frequency of a component of the power electronic device embodied as a semiconductor component is specifically changed when an energy efficiency deviation is detected. By raising or lowering the switching frequency, the power loss in the component in question can be increased or reduced.If this change, compared to the changes in other components, is outside a tolerance range, an aging-related defect can be assumed. The maximum permissible change in power loss can be determined by calculation during operation or commissioning. Alternatively or additionally, other operating parameters can also be changed: e.g., the DC link voltage and / or output currents and / or output voltages and / or input voltages and / or input currents and / or the phase shift between current and voltage.

[0034] It is also possible to use the comparison of energy efficiencies to determine the type of aging process that has occurred. For example, at least one suitable algorithm can be used to qualify the change in energy efficiency between two observation points in time and assign it to a specific physical aging process. Then, in conjunction with the type of aging process, it can be determined which component or components of the power electronic device are affected by the aging.

[0035] Based on the inventive comparison of the energy efficiencies of at least two observation points in time, a prediction can also be made as to when a failure of the power electronic system will occur. This prediction can be used for maintenance planning and / or a replacement point in time. To determine the energy efficiencies associated with the respective observation point in time, the input power of the power electronic device at the respective observation point in time can be used, in particular. The input power can be formed from the input current and the input voltage of the power electronic device.

[0036] Alternatively or additionally, the output power of the power electronic device at the respective point in time, in particular formed from the output current and output voltage, can be used to determine the energy efficiency at the respective point in time. If the power electronic device has two or more outputs, the sum of the output lines of the two or more outputs can be used.

[0037] Alternatively or additionally, the intermediate circuit line of the power electronic device at the respective point in time under consideration, in particular formed from the intermediate circuit current and the intermediate circuit voltage, can be used for this purpose.

[0038] In particular, by calculating the differences between these performances, the energy efficiency can be determined for one, two or more points in time.

[0039] Preferably, an input power and an output power are used. Alternatively or additionally, an input power and an intermediate circuit power can also be used. Again alternatively or additionally, an intermediate circuit power and an output power can be used. The difference in the power, e.g., the input power Pin and output power Pout, is a power loss Pv or can be used or viewed as such, e.g., Pin - Pout = Pv. Energy efficiency can be calculated, for example, as the output power divided by the sum of the output power and the power loss, i.e., energy efficiency = Pout / (Pout+Pv).

[0040] The measured value(s) on the basis of which the (respective) energy efficiency is determined can accordingly be given by or include the input current and / or the input voltage of the power electronic device, in particular at the respective time under consideration, and / or the output current and / or the output voltage of the power electronic device, in particular at the respective time under consideration, and / or the intermediate circuit current and / or the intermediate circuit voltage of the power electronic device, in particular at the respective time under consideration.It is also possible for the input power of the power electronic device at the (respective) observation time, and / or the output power of the power electronic device at the (respective) observation time, and / or the intermediate circuit power of the power electronic device at the (respective) observation time to be derived, in particular calculated, from the measured values. For example, the input current and the input voltage of an observation time can be recorded, provided, or used as measured values, and the input power can be calculated from these. In an analogous manner, the output power for the observation time(s) can be calculated from the respective output current and the output voltage, and / or the intermediate circuit power from the intermediate circuit current and the intermediate circuit voltage.The input power and / or output power and / or intermediate circuit power obtained from the measured values ​​for the (respective) point in time under consideration can then be used to obtain, in particular to calculate, the energy efficiencies.

[0041] As noted, thermal quantities or measured values ​​can also be used to determine energy efficiency.

[0042] For example, it can be provided that the power electronic device is cooled by means of a cooling fluid. In this case, the measured values ​​on the basis of which the energy efficiencies are determined for the time(s) under consideration can be given by temperature measured values ​​of the cooling fluid, which are or were measured at two different measuring points located in and / or before and / or after the power electronic device. In this case, the difference between the temperature measured values ​​at the two different temperature measuring points is preferably calculated and used to determine the energy efficiency(ies). A change in such a temperature difference over time indicates a changed, in particular increased power loss and thus lower energy efficiency. It should be noted that the flow rate orThe volume flow must be taken into account. This could, for example, be assumed to be constant, measured, or calculated.

[0043] For example, the temperature of a cooling fluid is or was recorded at or immediately before entering the power electronic device and at or immediately after exiting the power electronic device, and these temperature measurements are used. The cooling fluid can be air, for example, and the temperature measurements used to determine the energy efficiency(ies) for the time(s) under consideration can be provided by temperature measurements of the supply air and the exhaust air.

[0044] Of course, it is also possible that the cooling fluid is liquid and the temperature measurements used to determine the energy efficiency(ies) are given by the inlet and return temperature measurements of the liquid cooling fluid.

[0045] Alternatively or additionally, at least one temperature measured by a module sensor or a module-near temperature sensor of the power electronic device can also be used. A module sensor is understood to be a temperature sensor located in a semiconductor module housing near the power semiconductors (e.g., IGBT). A module-near temperature sensor is located near a semiconductor module (housing). For example, the magnitude of the difference between the temperature of the module sensor or module-near sensor and the supply air or inlet temperature at a specific operating point can then be used to determine increased power loss in the semiconductor (located in the module) compared to a module not subject to aging.

[0046] It has also proven useful to determine losses, particularly power losses, of the power electronic device that are occurring or have occurred at the respective point in time or - in the case of several points in time - at the respective point in time under consideration. A change, such as an increase in losses, such as an increase in the power loss of the device, can be regarded as an indicator of a change, particularly a decrease in energy efficiency. In further development, losses, particularly power losses, that are associated with the respective point in time under consideration can therefore be used to determine the energy efficiency(ies) or can be regarded as the quantity(s) representing the energy efficiency(ies). One can also say that the (respective) energy efficiency is determined via the losses, particularly power losses, that are occurring or have occurred at the respective point in time or points in time under consideration, for example calculated from the measured quantities.

[0047] Often, arrangements with not just one, but several, in particular series- or parallel-connected, power electronic devices, such as converters, are used. It is understood that in this case, it is possible, for example, to monitor only one of the power electronic devices, such as one of the converters, in the manner according to the invention. Alternatively, however, some, such as two or more, or even all power electronic devices, such as converters, of one or more arrangements can of course also be monitored in the manner according to the invention. In other words, the method according to the invention can be carried out for two or more power electronic devices that are part of an arrangement and / or are connected to one another in series or parallel.

[0048] A further subject of the present invention is a computer program comprising program code means which, when executed on at least one computer, cause the at least one computer to perform the steps of the method according to the invention. The computer program can run on at least one arbitrary computer and / or using a cloud. It is also possible for the power electronic device to be monitored to comprise at least one memory in which the computer program according to the invention is stored and at least one processor by means of which it is executed. In other words, the monitoring can then be carried out by the device itself or directly on it.

[0049] The invention also relates to a computer-readable medium comprising instructions which, when executed on at least one computer, cause the at least one computer to perform the steps of the method according to the invention. The computer-readable medium can be, for example, a CD-ROM or DVD, or a USB or flash memory. It should be noted that a computer-readable medium is not exclusively understood to mean a physical medium, but can also be in the form of a data stream and / or a signal representing a data stream, for example.

[0050] For further details of the invention, reference is made to the dependent claims and the description of the following embodiment with reference to the drawing. The drawing shows:

[0051] FIG 1 shows a power electronic device designed as a converter in a purely schematic representation,

[0052] FIG 2 n converters according to FIG 1 in series connection, of which two converters are shown as examples in FIG 2, and

[0053] FIG 3 n converters according to FIG 1 in parallel connection, of which two converters are shown as examples in FIG 2.

[0054] FIG. 1 shows a highly simplified, purely schematic representation of a power electronic device, which in this case is embodied, for example, as a converter 1. This may be an AC / DC converter, a DC / DC converter, a DC / AC converter, or even an AC / AC converter.

[0055] The converter 1 comprises a plurality of components, one or more of which are semiconductor devices. FIG. 1 schematically shows, by way of example, two semiconductor devices 2, 3, a capacitor 4, a fan 5, and a controller 6 of the converter 1. It is understood that the number of components within a converter 1 can, in principle, be any desired number. Two connections 7, 8 of the converter 1 are also shown. It is understood that the converter 1 can have any desired number of additional connections, for example for multi-phase scenarios, intermediate circuit connections, and / or external components, such as braking resistors. The connections are shown only in a highly simplified manner in FIG. 1. For reasons of clarity, the further internal structure, including internal cables, of the converter 1 is also not shown in the purely schematic FIG. 1.

[0056] The converter 1 shown in FIG. 1 has a cooling air duct not further illustrated in the FIG. 1, in particular one or more associated ducts. The cooling air is conveyed through the duct(s) by means of the fan 5. Alternatively or additionally, the converter 1 can also be cooled with a liquid cooling medium, such as water, in which case the converter 1 has an associated cooling circuit (not shown).

[0057] The semiconductor components shown here are an IGBT 2 and a MOSFET 3, although this, including their number, is to be understood purely as an example. For example, alternatively or additionally, at least one semiconductor component designed as a diode and / or one or more semiconductor components of a different type may also be present.

[0058] The semiconductor components 2, 3 are subject to aging due to various mechanisms. For example, bond wire lifting, aging of solder connections, or direct copper bondend cracks (DCB cracks) frequently occur within semiconductor components 2, 3. These aging mechanisms inevitably lead to the functional failure of the affected semiconductor components 2, 3 and subsequently also of the power electronic device 1.

[0059] It is entirely possible for a plurality of power electronic systems, such as the converter 1 shown in FIG. 1, to be used, which are connected in series or in parallel. This is shown by way of example in the schematic FIGS. 2 and 3, of which FIG. 3 shows n converters 1 according to FIG. 1, which are connected in series, and FIG. 3 shows n converters 1 according to FIG. 1, which are connected in parallel. The simplified, schematic FIGS. 2 and 3 each show, by way of example, only two converters 1, which are designated n or n+1 in the FIGS. It is understood that an arrangement comprising more than two power electronic systems, such as converters 1 according to FIG. 1, which are connected in series or in parallel, can also be provided or used. For example, three, four, five, six, seven or more power electronic systems, such as converters 1, can also be present.

[0060] The exemplary embodiment of the method according to the invention described below enables reliable condition monitoring of the converter 1. It is understood that, in the event that two or more converters 1 are present (see FIGS. 2 and 3), two or more, preferably all, converters 1 present can naturally also be monitored in the manner described below. The monitoring of one converter 1 is described below as an example. The steps can be executed by an exemplary embodiment of a computer program according to the invention.

[0061] In this case, the energy efficiency of the converter 1 is determined for several different observation points in time, whereby the determination of the energy efficiencies for the different observation points in time is carried out on the basis of one or more measured values ​​recorded for the converter 1.

[0062] In order to determine the energy efficiency or power loss of a power electronic device 1 at the respective point in time under consideration, the following physical quantities in particular can be used within the scope of the present method.

[0063] Electrical quantities:

[0064] Input power of converter 1 formed from input current and voltage

[0065] - Output power of converter 1 formed from output current and voltage DC link power of converter 1 formed from DC link current and voltage

[0066] Thermal quantities:

[0067] Temperature of the supply air and the exhaust air of the converter 1 ;

[0068] Temperature of the inlet of a liquid cooling medium used to cool the converter 1 and its return temperature

[0069] Temperature of a module sensor or module-near sensor of the converter 1 These quantities can represent measured values ​​that are or were recorded in and / or on the converter 1 at the respective time under consideration, or they can be derived from such measured values ​​in order to then be used for the energy efficiency or power loss determination.

[0070] It should be noted that the metrological recording of one or more of the aforementioned variables can be, but does not have to be, a component of the method according to the invention. For example, existing measured values ​​recorded and stored in the past can also be accessed. Measuring devices, such as sensors, that are already present as standard in the converter 1 can be used or have been used to record the measured values. Implementing the method according to the invention therefore does not require any additional design effort for the converter 1.

[0071] In the example described here, the temperature values ​​of the cooling air, specifically the temperature of the supply air and the exhaust air of converter 1, are used as measured values ​​for determining energy efficiency. Converter 1 has two temperature sensors 9, 10 that can measure the supply and exhaust air temperatures. The difference a is determined, specifically calculated, from the supply and exhaust air temperature values ​​at the respective observation time.

[0072] For convenience, the flow rate or volume flow is also taken into account. These can be assumed to be constant, measured, or calculated.

[0073] A change in the difference between exhaust and supply air over time indicates an increase in power loss and thus corresponds to or represents a decrease in the energy efficiency of the converter 1.

[0074] Alternatively or additionally, the power loss can be calculated from the difference between the output and input-side power. To calculate the input and output power, the corresponding input and output current and voltage values ​​are measured. For an AC input or output, the angle of the fundamental frequency between current and voltage can be conveniently taken into account when calculating active power.

[0075] In the present example, the energy efficiency – specifically the power loss as a parameter representing energy efficiency – is determined for a point in time at which converter 1 or its components, including semiconductor devices 2, 3, were not yet subject to aging. This first point in time, for example, was immediately after the completion of the manufacturing process for converter 1 and before its commissioning at the actual place of use. One could also say that the energy efficiency is recorded for the unaged state of converter 1. For this purpose, converter 1 can be or have been operated in test mode immediately after production in order to obtain measured values ​​for supply and exhaust air.During ongoing, real-life operation of the converter 1 at the actual place of use, the temperature difference is then determined at least once more, preferably several times, based on the measured values ​​for the supply and exhaust air temperatures as the energy efficiency at the respective observation point in time. This can be done repeatedly over the life cycle of the converter 1, as is generally known in the field of condition monitoring. The energy efficiencies determined for the multiple observation points expediently relate to the same operating points of the converter 1, thus ensuring direct comparability.

[0076] From the energy efficiency determined for the observation times, conclusions are drawn about the condition of converter 1, in particular about any aging process that has occurred.

[0077] The energy efficiencies determined during or for ongoing operation can, for example, be compared with the initial energy efficiency of converter 1 in its non-aged state, which has proven particularly useful. For example, the difference is calculated in each case, and if the difference exceeds a specified threshold, it is concluded that converter 1 has aged, in particular, has an age-related defect.

[0078] Alternatively or in addition to a fixed difference threshold, the first derivative of the difference over several points in time can also represent a possible evaluation variable.

[0079] If a change, specifically a decrease in energy efficiency by more than a predetermined value, is taken to indicate the existence of an age-related defect, it is preferably subsequently determined which component or components 2-6 of the converter 1 is or are affected by ageing. For example, the respective efficiency change(s) can be qualified using at least one suitable algorithm in order to be able to assign it to at least one physical ageing process. This can then help in identifying the component(s) 2-6 affected by the ageing process(es). At least one component temperature measurement value of at least one component 2-6 of the converter 1 can also be used. Power electronic devices generally have internal and / or nearby temperature sensors, by means of which the temperature of individual components 2-6 is monitored during operation anyway.In the exemplary embodiment illustrated in FIG. 1, temperature sensors 11, 12 are provided for measuring the temperature of semiconductor components 2, 3. The measured values ​​acquired by these sensors can thus be accessed. If, for example, it is found that a semiconductor component has or has had an elevated temperature—particularly compared to at least one other semiconductor component—it is assumed that (at least) this semiconductor component has an aging-related defect. This may be the case, for example, for MOSFET 3.

[0080] Alternatively or additionally, it is also possible to perform an analysis operation of the converter 1, particularly for the identification of aged components 2-6. For example, at least one operating parameter of at least one component 2-6 is specifically changed to determine whether this at least one component 2-6 is subject to an aging process that affects the energy efficiency of the converter 1. For example, the switching frequency of the MOSFET 3 can be increased.

[0081] Based on the assumption of an aging-related defect, at least one semiconductor component, e.g., MOSFET 3, can be serviced or replaced, or its service or replacement can be scheduled. As a result, particularly reliable and efficient operation of converter 1 is ensured.

[0082] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0083] Regardless of the grammatical gender of a particular term, persons with male, female, or other gender identities are included.

[0084] 1 inverter

[0085] 2 IGBTs 3 MOSFETs

[0086] 4 Capacitor

[0087] 5 fans

[0088] 6 Control

[0089] 7 Connection 8 Connection

[0090] 9 Temperature sensor

[0091] 10 Temperature sensor

[0092] 11 Temperature sensor

[0093] 12 Temperature sensor

Claims

Patent claims 1. A method for monitoring the state of a power electronic device (1), in particular a converter, with two or more components (2-6), at least one of which is a semiconductor component (2, 3), characterized in that - an energy efficiency of the power electronic device (1) is determined for at least one observation time, in particular for at least two different observation times, wherein the determination of the energy efficiency for the respective observation time or times is carried out on the basis of one or more measured values ​​recorded for the power electronic device (1), in particular in and / or on the power electronic device (1) and / or at the respective observation time or times, - the condition of the power electronic device (1), in particular an ageing process that has occurred, is determined from the energy efficiency determined for the time under consideration, in particular from the energy efficiencies determined for the two or more times under consideration.

2. Method according to claim 1, characterized in that in the event that the or at least one determined energy efficiency lies below a predetermined threshold value, it is concluded that the power electronic device (1) has aged, in particular has an age-related defect.

3. Method according to claim 1 or 2, characterized in that the energy efficiency is determined for at least two observation times and the energy efficiencies belonging to the different observation times are compared with one another, and on the basis of the comparison of the energy efficiencies, a conclusion is drawn about the condition, in particular about an ageing process that has occurred, of the power electronic device (1), preferably, wherein on the basis of the comparison of the energy efficiencies, a conclusion is drawn about which type of ageing process has occurred, preferably, wherein the type of ageing process is used to determine which component (2-6) or components (2-6) of the power electronic device (1) is or are affected by the ageing.

4. Method according to claim 3, characterized in that in the event that the comparison of the energy efficiencies belonging to the different observation times shows that the energy efficiency at a second, later observation time is or was lower, in particular by a predetermined threshold value, than at a first, earlier point in time, it is concluded that the power electronic device (1) has aged, in particular has an age-related defect.

5. Method according to claim 3 or 4, characterized in that the determined energy efficiency belonging to the respective observation time(s) relates to the same operating points of the power electronic device (1), and / or that the recording of the measured values ​​on the basis of which the energy efficiencies for the different observation times are determined takes place or took place at the same operating points.

6. Method according to one of claims 3 to 5, characterized in that the power electronic device (1) has completed different operating periods at the different observation times, and / or that one of the observation times is before the first commissioning of the power electronic device (1).

7. Method according to one of the preceding claims, characterized in that it is determined which component (2-6) or components (2-6) of the power electronic device (1) is or are affected by aging, preferably, wherein at least one algorithm is used for this purpose, and / or wherein at least one component temperature measurement value of at least one component (2-6) of the power electronic device (1) is used for this purpose, and / or wherein an analysis operation of the power electronic device (1) is carried out for this purpose, wherein, within the scope of the analysis operation, at least one operating parameter of at least one component (2-6) of the power electronic device (1) is specifically changed in order to determine whether this at least one component (2-6) of the power electronic device (1) is affected by aging,in particular, has been subjected to an ageing process that affects the energy efficiency of the power electronic device.

8. Method according to one of the preceding claims, characterized in that based on the assumption of an age-related change in state, in particular based on the assumption of an age-related defect, at least one component (2-6) of the power electronic device (1) is maintained or replaced or maintenance or replacement is planned.

9. Method according to one of the preceding claims, characterized in that the input power of the power electronic device (1) at the or the respective observation time, and / or the output power of the power electronic device (1) at the or the respective observation time, and / or the intermediate circuit line of the power electronic device (1) at the or the respective observation time.

10. Method according to one of the preceding claims, characterized in that for the determination of the energy efficiency belonging to the respective observation time, the input power of the power electronic device (1) at the respective observation time, in particular formed from input current and input voltage, and / or the output power of the power electronic device (1) at the respective observation time, in particular formed from output current and output voltage, and / or the intermediate circuit line of the power electronic device (1) at the respective observation time, in particular formed from intermediate circuit current and intermediate circuit voltage, are used.

11. The method according to claim 10, characterized in that the measured values ​​on the basis of which the energy efficiency is determined for the or the respective observation time, the input current and / or the input voltage of the power electronic device (1) in particular at the or the respective observation time, and / or the output current and / or the output voltage of the power electronic device (1) in particular at the or the respective observation time, and / or the intermediate circuit current and / or the intermediate circuit voltage of the power electronic device (1) in particular at the or the respective observation time include or are given thereby.

12. Method according to one of the preceding claims, characterized in that the power electronic device (1) is cooled by means of a cooling fluid, preferably, wherein the measured values ​​on the basis of which the energy efficiency is determined for the or the respective observation time are given by temperature measured values ​​of the cooling fluid, which are or were measured at two different measuring points in and / or before and / or after the power electronic device (1), preferably, wherein the difference between the temperature measured values ​​at the two different measuring points is calculated and used to determine the energy efficiency for the or the respective observation time.

13. Method according to claim 12, characterized in that the cooling fluid is air and the temperature measurements on the basis of which the energy efficiency is determined for the respective observation time or times are given by temperature measurements of the supply air and the exhaust air, or the cooling fluid is liquid and the temperature measurements on the basis of which the energy efficiency is determined for the respective observation time or times are given by inlet and return temperature measurements of the liquid cooling fluid.

14. Method according to one of the preceding claims, characterized in that losses, in particular power losses, of the power electronic device occurring or having occurred at the or the respective observation time are determined, in particular, wherein the losses, in particular power losses, are used to determine the energy efficiency for the or the respective observation time or are considered as quantities representing the energy efficiency for the or the respective observation time.

15. A computer program comprising instructions which, when executed on at least one computer, cause the at least one computer to perform the steps of the method according to any one of claims 1 to 14.

16. A computer-readable medium comprising instructions which, when executed on at least one computer, cause the at least one computer to perform the steps of the method of any one of claims 1 to 14.

Images