Method and device for determining the power loss of a semiconductor structure element of an inverter

Abstract

The invention relates to a method for determining the loss power of a semiconductor structure element of an inverter, wherein for each half-bridge of the inverter a current phase current is received or detected, the current switching signal and / or the current switching time for actuating the controllable semiconductor structure element of the half-bridge are received by a regulating device, the forward loss power of the semiconductor structure element is determined from the phase current, the corresponding duty cycle and the corresponding current-voltage characteristic curve, taking into account the phase current direction, the switching loss power of the semiconductor structure element is determined from the turn-on energy, the turn-off energy and the reverse recovery energy and the number of turn-on processes and the number of turn-off processes, taking into account the phase current direction, and wherein the total loss power of the semiconductor structure element is determined and provided from the determined forward loss power and the determined switching loss power, and wherein the determination of the loss power takes place at the regulating pace of the regulating device of the inverter. The invention also relates to a device.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for determining the power loss of semiconductor structural elements in an inverter. Background Technology

[0002] Inverters, especially traction inverters, are used in electric vehicles. The power module with a three-phase four-quadrant regulator composed of IGBTs or MOSFETs is a core component in such traction inverters. This component needs protection from damage, primarily by preventing the occurrence of critical temperatures. The temperature of the semiconductor structural elements required for temperature monitoring and protection (barrier layers) can only be measured directly at the corresponding power semiconductor at a very high technical cost.

[0003] One solution is to determine the (barrier layer) temperature based on a model, for example, used in inverter control to estimate the (barrier layer) temperature. It is necessary to develop a model that is as accurate as possible and works at all operating points of the traction inverter. This requires considering the use of different modulation and control methods (SVPWM, DPWM, block synchronization, ...) and operating states such as "active short circuit" or "no-load operation" in drive regulation.

[0004] The model implemented in inverter control should operate as independently as possible from drive regulation and should also reflect the asymmetric load on the power semiconductors. The input values ​​for such a model used to determine the (barrier) temperature are particularly the power losses of the individual semiconductor structural elements.

[0005] Methods and systems for modeling the temperature characteristics of components in a system (e.g., a power module for a hybrid vehicle or electric vehicle) are known from US 2009 / 0319115 A1. A power loss value is calculated for each component in the system. A first filter is applied to the power loss value associated with a selected component to determine its estimated temperature. A cross-coupling temperature is estimated for each of the adjacent components next to the selected component, such that other filters are applied to each of the power loss values ​​for the adjacent components. The estimated temperature of the selected component and the estimated cross-coupling temperature for each of the adjacent components can then be added to estimate the operating temperature for the selected component. Furthermore, system operation can be adapted when the determined operating temperature for the selected component exceeds a threshold. Summary of the Invention

[0006] The object of the present invention is to provide a method and apparatus for determining the power loss of semiconductor structural elements of an inverter, which can improve the determination of power loss.

[0007] According to the present invention, this objective is achieved by a method for determining the power loss of semiconductor structural elements of an inverter and an apparatus for determining the power loss of semiconductor structural elements of an inverter. Advantageous embodiments of the present invention are derived according to the present invention.

[0008] In particular, a method for determining the power loss of semiconductor structural elements, especially rectifier units, of an inverter is available, wherein, for each half-bridge of the inverter: - Receive or detect the current phase current. - The inverter's regulation unit receives current switching signals and / or switching times for controlling the controllable semiconductor structural elements of the half-bridge. - Taking into account the direction of the phase current, the forward power loss of the semiconductor structure elements of the half-bridge is determined from the phase current, the corresponding duty cycle, and the corresponding current-voltage characteristic curve. - Taking into account the direction of phase current, the switching power loss of a semiconductor element is determined by the turn-on energy, turn-off energy, reverse recovery energy, and the number of turn-on and turn-off processes. The total power loss of the semiconductor structure elements of the half-bridge is determined and provided by the determined forward power loss and the determined switching power loss, wherein the power loss is determined by the regulation cycle of the inverter's regulation device.

[0009] Furthermore, an apparatus for determining the power loss of semiconductor structural elements, particularly rectifier units, in an inverter is provided, comprising an input device, a computing device, and an output device. The input device is configured to receive, for each half-bridge, the current detected phase current and current switching signal and / or switching time of the controllable semiconductor structural elements for controlling the half-bridge, from the inverter's regulating device. The computing device is configured to determine, for each half-bridge, the forward power loss of the semiconductor structural elements of the half-bridge, considering the direction of the phase current, from the phase current, the corresponding duty cycle, and the corresponding current-voltage characteristic curve; and for each half-bridge, the switching power loss of the semiconductor structural elements, considering the direction of the phase current, from the turn-on energy, turn-off energy, reverse recovery energy, the number of turn-on processes, and the number of turn-off processes. The total power loss of the semiconductor structural elements of the half-bridge is determined from the determined forward power loss and the determined switching power loss, and the power loss determination is performed according to the regulating cycle of the inverter's regulating device. The output device is configured to provide the determined total power loss of the semiconductor structural elements of the half-bridge.

[0010] This method and apparatus make it possible to determine the power loss of the semiconductor structural elements of the inverter's half-bridge independently of the modulation and control methods (e.g., SVPWM, DPWM, block synchronization, etc.). Furthermore, this method and apparatus can determine the power loss even during operating states such as "active short circuit" (where the controllable semiconductor structural elements (i.e., semiconductor switches, especially IGBTs or MOSFETs) on the low-voltage or high-voltage side of all phases are electrically connected and the motor terminals are short-circuited) and "no-load operation" (where the controllable semiconductor structural elements are disconnected or non-conductively connected (the inverter then operates as a rectifier)).

[0011] The power loss of each half-bridge semiconductor element (transistor and diode) in the inverter is determined. The semiconductor elements are specifically configured as rectifier units with a corresponding number of half-bridges and three-phase (or two-phase, six-phase, etc.) four-quadrant regulators, which, for example, feed power to a traction drive motor. One basic idea is to determine the power loss based on the regulating cycle of the inverter's (current) regulating device. This allows the power loss for each cycle of the regulating cycle to be determined and provided. For each half-bridge, the current value of the phase current is received or detected. This detection can be part of the method. This detection is particularly performed by means of a suitable sensing device. Furthermore, the inverter's (current) regulating device receives the current switching signals, particularly pulse width modulation (PWM) control signals, and / or switching times for controlling the controllable semiconductor elements (i.e., transistors) of the half-bridge. The total power loss of each semiconductor element includes forward power loss and switching power loss. The forward power loss of the semiconductor elements in a half-bridge is determined, taking into account the direction of the phase current, from the phase current, the corresponding duty cycle, and the corresponding current-voltage characteristic curve. The situation is particularly differentiated depending on the direction of the phase current. The switching power loss of the semiconductor elements is determined, taking into account the direction of the phase current, from the turn-on energy, turn-off energy, reverse recovery energy, and the number of turn-on and turn-off processes. Specifically, the number of times the elements are turned on and off per regulation cycle is determined using a switching signal and / or switching time, so that the corresponding switching power loss can be determined based on the corresponding quantities and values ​​of the turn-on energy, turn-off energy, and reverse recovery energy. The total power loss of the semiconductor elements in the half-bridge is determined and provided from the determined forward power loss and the determined switching power loss. Specifically, for each semiconductor element in each half-bridge, a value for the corresponding total power loss is provided, particularly as an output, for example, as an analog or digital signal.

[0012] The advantage of this method and apparatus is that the power loss can be determined independently of the modulation method or changes in the modulation method. In particular, neither averaging nor a completely known modulation method is required. Therefore, this method and apparatus can be used flexibly and reliably.

[0013] Inverters are particularly used for traction inverters that drive motors in vehicles, such as electric or hybrid vehicles. These inverters convert direct current (DC) into multiphase alternating current (AC). The inverters typically include a half-bridge configuration. Each half-bridge typically includes one high-side transistor and one low-side transistor. Furthermore, the half-bridge typically includes diodes connected in anti-parallel to the corresponding transistors. In particular, the inverter includes three half-bridges and provides three phases. However, other topologies can also be configured in principle, such as a six-half-bridge configuration to provide six phases, etc.

[0014] The regulating cycle specifically refers to the number of times (frequency) the switching signal (or switching time) is provided in the form of a pulse width modulation (PWM) pulse pattern, which is adapted to the inverter. In particular, the regulating cycle represents the cycle of a time-discrete (current) regulating device. The duration of the regulating period is thus kept constant; that is, the set switching signal (or switching time) or the PWM pulse pattern pre-given by the regulating device is not changed. The regulating cycle does not specifically represent the switching frequency of the transistor. The regulating period does not specifically represent the switching time or switching duration of the half-bridge transistor.

[0015] Duty cycle specifically describes the proportion of the settling period (or settling period duration) during which the transistor is forward-biased (i.e., during which the transistor conducts). The duty cycle is specifically a quotient of the on-time and the settling period.

[0016] Turn-on energy, especially the energy dissipated when a transistor is turned on or conducting. Turn-off energy, especially the energy dissipated when a transistor is turned off or blocked. Reverse recovery energy, especially the energy dissipated when a diode is switched from a conducting state (forward direction) to a blocking state (blocking direction). Energy can be obtained from the datasheet of the semiconductor structure element or determined empirically and / or through simulation.

[0017] The components of the device, particularly the computing device, can be configured individually or in combination as a combination of hardware and software, for example, as program code implemented on a microcontroller or microprocessor. Alternatively, the components can be configured individually or in combination as application-specific integrated circuits (ASICs) and / or field-programmable gate arrays (FPGAs). Input and output devices can be configured, in particular, as interfaces. The device can be constructed, in particular, independently of an inverter, inverter control unit, or inverter regulation unit. However, the device can also be part of an inverter, inverter control unit, or regulation unit.

[0018] In the following implementation, it is specifically assumed that the half-bridge has two transistors (high voltage side and low voltage side) and two diodes (high voltage side and low voltage side).

[0019] If an IGBT (Insulated-Gate Bipolar Transistor) is used as a transistor, the forward power loss for the transistor on the high-voltage side (index "HS") and the low-voltage side (index "LS") is... and It can be determined using the following formula: Current-voltage characteristic curve with IGBT Phase current And duty cycle. or Current-voltage characteristic curve Depends on phase current and the corresponding (barrier layer) temperature .

[0020] The forward power loss of the diode connected in reverse parallel to the IGBT is correspondingly... and The following formula can be used to determine this: Current-voltage characteristic curve with diode It depends on the phase current. and the corresponding (barrier layer) temperature .

[0021] If a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) is used as a transistor, the forward power loss of the transistor on both the high-voltage and low-voltage sides is... and The following formula can be used to determine this: The forward power loss of the diode connected in reverse parallel to the MOSFET can be determined using the formula already explained above.

[0022] Switching loss power of transistors and The following formula can be used to determine this: Number of processes with connection Number of disconnection processes Adjustment cycle duration Connecting to energy Connect to energy Especially depends on the phase current The corresponding (barrier layer) temperature and intermediate circuit voltage and disconnect energy disconnect energy Especially, it also depends on the phase current. The corresponding (barrier layer) temperature and intermediate circuit voltage .

[0023] By reverse energy recovery The determined switching power loss of the reverse parallel diode (which depends particularly on the phase current) The corresponding (barrier layer) temperature and intermediate circuit voltage The following formula can be used to determine this: The total power loss of a semiconductor structural element is thus derived as the sum of the power losses of each individual element: In one embodiment, the duty cycle is determined separately for each semiconductor element. This improves the accuracy in determining power loss. Typically, the duty cycle of one of the two transistors (high-side or low-side) in a half-bridge is determined by subtracting the duty cycle of the other transistor (low-side or high-side) from a value of 1 (or 100%). This simplification, however, leads to inaccuracies and distortions in the determined power loss. In particular, in this embodiment, the duty cycle of the transistor (and subsequently the diode) is determined accordingly independently of the duty cycle of the corresponding other transistor. If the duty cycle of the high-side transistor is, for example, 0.8 or 80%, the duty cycle of the low-side transistor is typically set to 1 - 0.8 = 0.2 (or 100% - 80% = 20%). However, the fact that the transistors are not precisely turned on simultaneously is neglected here because a gap is provided between the turn-on times for safety reasons, so that the two transistors are not simultaneously conducting at any given time. This implementation takes this into account, so in the example mentioned, the duty cycle is determined based on the actual switching time with values ​​of, for example, 0.8 (high voltage side) and 0.18 (low voltage side) to account for the time during which the transistor is not conductively turned on (= 0.02 or 2% of the adjustment cycle duration).

[0024] In one embodiment, the current-voltage characteristic curve is configured to depend on temperature. This allows for more accurate calculation of power loss. The current-voltage characteristic curve can be established, for example, using values ​​provided by the semiconductor component manufacturer, or determined empirically and / or by means of simulation.

[0025] In one embodiment, signal edges in the switching signal are identified and evaluated to determine the corresponding duty cycle and / or the number of on and / or off processes. This makes it possible to determine the switching power loss based on the actual switching processes that occur. In other words, the switching power loss can be determined independently of knowledge of the specific modulation scheme based on the actual switching processes. By identifying and evaluating the switch edges, the on and off processes can be directly counted. If when the on and off processes occur during the adjustment period is known, the duty cycle can also be directly determined. The switch edges, or their timing within the adjustment period, are identified, for example, by means of a threshold comparison. Here, it can be configured to confirm whether the threshold is exceeded or fallen below, so that the on or off processes can be directly inferred.

[0026] In one embodiment, the turn-on energy and / or turn-off energy and / or reverse recovery energy are determined from a family of characteristic curves, in which the corresponding values ​​depend on the phase current and intermediate circuit voltage. Thus, the determination of switching power loss can be improved, and in particular, more realistically. The family of characteristic curves is typically available from manufacturers of semiconductor structural components. The family of characteristic curves can be generated empirically and / or through simulation.

[0027] In an improved embodiment, the family of characteristic curves is configured to depend on temperature. This allows temperature dependence to be considered when determining switching power losses, resulting in a more accurate and precise determination of the switching power losses.

[0028] In one embodiment, the determined total power loss is supplied to a temperature model, from which the temperature is estimated and provided for each element in the semiconductor structure. The temperature model is, for example, a thermal network comprising four Foster chains. The estimated temperature for the (barrier layer) of the semiconductor structure is then used as an input value in determining the power loss. Thus, the determined power loss and the determined (barrier layer) temperature influence or couple with each other (higher power loss leads to higher temperature, which in turn leads to even higher power loss, etc.). Furthermore, based on the determined temperature, the regulation strategy of the inverter's (current) regulation device can be altered.

[0029] In one embodiment, the phase current detection time is synchronized with the regulation cycle. Since the regulating device can only affect the motor via the switched-on inverter, it is pointless to subject it to (time-discrete) inverter regulation more frequently than the inverter can be switched on and off. Therefore, only one value of the phase current is necessary for each regulation cycle. This embodiment allows for efficient phase current detection. Specifically, it can be configured so that the corresponding phase current is always detected at some point in the middle of the regulation cycle.

[0030] Further features of the device design are derived from the description of the method design. Here, the advantages of the device are correspondingly the same as those in the method design.

[0031] Furthermore, a means of transport is also provided, including at least one device according to one of the described embodiments. This means of transport is particularly a motor vehicle. However, in principle, this means of transport can also be other land, rail, water, air, or space vehicles. Attached Figure Description

[0032] The present invention will now be further described with reference to the accompanying drawings, based on preferred embodiments. Wherein: Figure 1 A schematic illustration shows one embodiment of a device for determining the power loss of semiconductor structural elements in an inverter; Figure 2a Exemplary current-voltage characteristic curves of IGBTs at different temperatures are shown; Figure 2b Exemplary current-voltage characteristic curves of bipolar transistors at different temperatures are shown; Figure 3 a-3f shows an example of a switching signal that may occur during the adjustment period for displaying the method and apparatus; Figure 4 This shows an exemplary family of temperature-dependent characteristic curves for the switching energy; Figure 5 A schematic illustration shows an exemplary state that may occur in a half-bridge with two IGBT transistors and corresponding diodes connected in reverse parallel thereto. Figure 6a A schematic diagram showing the current-voltage characteristic curve (forward direction) of an IGBT transistor; Figure 6b A schematic diagram showing the current-voltage characteristic curve (forward direction) of a diode; Figure 7 A schematic illustration shows an exemplary state that may occur in a half-bridge with two MOSFET transistors and corresponding diodes connected in reverse parallel thereto. Figure 8a A schematic diagram showing the current-voltage characteristic curve (forward direction) of a MOSFET transistor; Figure 8b A schematic diagram showing the current-voltage characteristic curve (blocking direction) of a MOSFET transistor; Figure 8c A schematic diagram showing the current-voltage characteristic curve (forward direction) of a diode; Figure 9 A schematic flowchart of one embodiment of a method for determining the power loss of semiconductor structural elements in an inverter is shown. Detailed Implementation

[0033] exist Figure 1 The diagram shows the power loss P of the inverter 40 and the semiconductor structural elements 42 used to determine the inverter 40. T,HS , P D,HS , P T,LS , P D,LSA schematic illustration of the traction drive 51 of a vehicle 50 in one embodiment of the device 1. The inverter 40 includes a (current) regulating device 41 and a semiconductor structural element 42. The device 1 operates in parallel with the (current) regulating device 41, which controls the semiconductor structural element 42 of the inverter 40 and provides for the switching time t during which the switchable semiconductor structural element 42 (i.e., transistor) and the drive circuit (not shown) are turned on. U , t V , t W The semiconductor structural element 42 is specifically configured as a rectifier unit with a corresponding number of half-bridges, consisting of a three-phase (or two-phase, six-phase, etc.) four-quadrant regulator, which feeds power to the motor 52 of the traction drive 51.

[0034] Device 1 is shown as part of inverter 40, but it can also be used separately. Device 1 is particularly arranged in vehicle 50 and is used thereto to determine the power loss P of the semiconductor structural element 42 of the (traction) inverter 40 of vehicle 50. T,HS , P D,HS , P T,LS , P D,LS .

[0035] Apparatus 1 specifically implements the method described in this disclosure. Apparatus 1 includes an input device 2, a computing device 3, and an output device 4. The input device 2 and the output device 4 are configured, for example, as an interface. The computing device 3 includes, for example, a microprocessor on which program code for implementing the measures of the method described in this disclosure is implemented; and includes a memory in which the program code and data are stored.

[0036] Input device 2 is configured to receive the currently detected phase current i from the (current) regulation device 41 of inverter 40 for each half-bridge. U i V i W and the current switching signal and / or switching time t of the controllable semiconductor structure element 42 used to control the half-bridge. U , t V , t W In addition, receiving device 2 receives the intermediate circuit voltage U of the intermediate circuit 43 of inverter 40. DC .

[0037] Receiving device 2 can receive the temperature T of semiconductor structural element 42 from, for example, a temperature model 44 provided and implemented by a module (not shown) configured for this purpose. T,HS , T T,LS , T D,HS , T D,LS The value of .

[0038] The computing device 3 is configured to consider the phase current i for each half-bridge. U i V i W In the case of the direction of the phase current i U i V i W The forward power loss of semiconductor element 42 in the half-bridge is determined based on the corresponding duty cycle and the corresponding current-voltage characteristic curve. Furthermore, the computing device 3, for each half-bridge, considers the phase current i... U i V i W In the case of forward direction, the switching power of semiconductor element 42 is determined based on the on-state energy, off-state energy, reverse recovery energy, and the number of on-state and off-state processes. Based on the determined forward power and the determined switching power, the calculation device 3 determines the total power loss P of the semiconductor element 42 of the half-bridge. T,HS , P D,HS , P T,LS ,P D,LS Here, the determination of power loss is performed according to the adjustment cycle of the inverter 40's adjustment device; that is, the power loss is determined in each adjustment cycle T. S It is determined once. The current-voltage characteristic curve is, for example, stored in the memory of computing device 3.

[0039] The computing device 3 determines the power loss from the corresponding current value using the formula previously described in the overview.

[0040] Output device 4 is configured to provide a defined total power loss P of the semiconductor structure element 42 of the half-bridge. T,HS ,P D,HS , P T,LS , P D,LS For a three-phase inverter with phases U, V, and W and three half-bridges (such as in...) Figure 1 As illustrated in the example, a total of 3 x 4 = 12 values ​​are thus provided for the total power loss P in (phase U, V, W). T,HS , P D,HS , P T,LS ,P D,LS In particular, the supply includes outputs as analog or digital signals.

[0041] In particular, the total power loss P T,HS , P D,HS , P T,LS , P D,LS It is supplied to the temperature module 44, in which the total power loss P is controlled. T,HS , P D,HS, P T,LS , P D,LS The starting point is to estimate and provide the (barrier layer) temperature T based on the temperature model for each semiconductor structural element 42. T,HS , T D,HS , T T,LS , T D,LS (For each of the half-bridges in phases U, V, and W, there are a total of 12 values). Here, the coolant volume flow ΔV / Δt and the coolant temperature T are... Cool and initial temperature T init These can be considered. When the current-voltage characteristic curve depends on temperature, these estimated (barrier layer) temperatures T... T,HS , T D,HS , T T,LS ,T D,LS This is specifically supplied to device 1 as an input value. It can be configured to determine a corresponding duty cycle for each semiconductor structural element 42. In particular, the respective, and correspondingly other, independent duty cycles for the corresponding high-side transistor and corresponding low-side transistor of each half-bridge are determined and used when determining the forward power loss.

[0042] It can be set so that the current-voltage characteristic curve 10 depends on the temperature. Figure 2a and 2b An example is shown for IGBT ( Figure 2a ) and diodes ( Figure 2b The current-voltage characteristic curve 10 (in the forward direction) is shown. Here, the collector current IC is shown as the collector-emitter voltage V in the case of a gate-emitter voltage of 15V. CE function ( Figure 2a Alternatively, the forward current IF can be used as the forward voltage V. F The function is given by the current-voltage characteristic curve 10, which allows the relevant voltage to be determined from the current phase current.

[0043] It can be configured to identify and evaluate signal edges 31, 32 in the switching signal 30 in order to determine the corresponding duty cycle and / or the number of on and / or off processes. For this purpose, the switching signal is supplied to the device 1 by the (current) regulating device 41. For illustrative purposes, in Figure 3 a-3f shows some of the switching signal 30 during the adjustment period T. S (Or the duration of the adjustment cycle) situations that may occur.

[0044] exist Figure 3 In case a, the signal state throughout the entire adjustment period T SThe transistor is active ("1"), meaning it is always in a conductive state. The number of on and off cycles is zero. The duty cycle is 1, or 100%. Figure 3 b shows the opposite situation, where the signal state is in the adjustment period T. S The transistor is not activated ("0"), meaning it is always in a non-conductive state. Here, the number of on and off cycles is also zero.

[0045] exist Figure 3 In c, the switching signal is in the adjustment period T S The process involves switching between activation and deactivation. A rising signal edge 31 and a falling signal edge 32 occur. The number of on and off processes is correspondingly equal to 1. Figure 3 Figure d shows the reverse process, in which the switching signal 30 is in the adjustment period T. S The process involves the device being initially deactivated and then switched to activation. Here, the number of connection and disconnection processes is also equal to 1. Figure 3 c and Figure 3 The duty cycles of d are complementary to each other and sum to 1 or 100%.

[0046] exist Figure 3 In e, the switching signal 30 is in the adjustment period T S During the process, it is switched to active, thus making the number of connected processes equal to 1 and the number of disconnected processes equal to 0. Figure 3 In the case of f, it is the opposite; here, the switching signal 30 is in the adjustment period T. S During the process, it is switched to inactive, so that the number of connected processes is equal to 0 and the number of disconnected processes is equal to 1. Figure 3 e and Figure 3 The duty cycles of f are complementary to each other and sum to 1 or 100%.

[0047] It can be configured to determine the turn-on energy and / or turn-off energy and / or reverse recovery energy based on the family of characteristic curves 11, where the corresponding values ​​in the family of characteristic curves depend on the phase current I. Ph (In this embodiment, i is in unit A) U i V i W , Figure 1 ) and intermediate circuit voltage U DC (In units of V) is used for storage. An example of this family of characteristic curves 11 is illustrated in... Figure 4 For connecting energy E on (in mJ) is displayed. Here, it can be specifically set so that the characteristic curve family 11 depends on temperature. For the on-state energy E... onFor characteristic curve family 11, this is exemplarily shown for three temperatures. For temperatures in between or outside of these temperatures, these values ​​can be interpolated, extrapolated, or held at the last value (sheared). The corresponding characteristic curve family 11 is used for disconnect energy and reverse recovery energy.

[0048] It can be configured to detect phase current i U i V i W ( Figure 1 The detection time is synchronized with the adjustment rhythm.

[0049] Figure 5 Examples are shown for six cases I to VI of the possible states in a half-bridge with two transistors THS, TLS (especially IGBT) and correspondingly anti-parallel diodes DHS, DLS (transistors and diodes are only shown in case I for clarity). Here, cases I to VI correspond to the differences listed earlier in the overview description for IGBT in the formulas.

[0050] In case I, the high-voltage side transistor THS is conductive, the low-voltage side transistor TLS is non-conductive, and the phase current I... Ph > 0. The current, as shown, is delivered via the high-side transistor THS and follows a current-voltage characteristic curve, which is schematically shown in Figure 6a The text is displayed in the middle (see also...). Figure 2a ).

[0051] In case II, the high-voltage side transistor THS is conductive, the low-voltage side transistor TLS is non-conductive, and the phase current I... Ph < 0. The current is achieved via the high-voltage side diode DHS as shown and follows the diode's current-voltage characteristic curve, which is schematically shown in Figure 6b The text is displayed in the middle (see also...). Figure 2b ).

[0052] In case III, the high-voltage side transistor THS is not conductive, while the low-voltage side transistor TLS is conductive and the phase current I... Ph < 0. The current flows through the low-voltage side crystal T as shown. LS It achieves and follows the current-voltage characteristic curve, which is schematically shown in Figure 6a The text is displayed in the middle (see also...). Figure 2a ).

[0053] In case IV, the high-voltage side transistor THS is not conducting, while the low-voltage side transistor TLS is conducting and the phase current I... Ph> 0. The current is achieved via the low-side diode DLS as shown and follows the diode's current-voltage characteristic curve, which is schematically shown in Figure 6b (in the positive direction) is displayed (see also) Figure 2b ).

[0054] In case V, not only the high-side transistor THS but also the low-side transistor TLS is non-conductive and the phase current I... Ph < 0. The current is achieved via the high-voltage side diode DHS as shown and follows the diode's current-voltage characteristic curve, which is schematically shown in Figure 6b The center (positive direction) is displayed (see also...) Figure 2b ).

[0055] In case VI, not only the high-side transistor THS but also the low-side transistor TLS is non-conductive and the phase current I... Ph >0. The current is achieved via the low-side diode DLS as shown and follows the diode's current-voltage characteristic curve, which is schematically shown in... Figure 6b The center (positive direction) is displayed (see also...) Figure 2b ).

[0056] exist Figure 7 The corresponding cases for MOSFETs are shown below. Cases I through VI are, in principle, similar to those for IGBTs. Cases II and IV differ because current (as schematically shown) flows not only through diodes DHS and DLS but also through transistors THS and TLS. It is important to note that transistors THS and TLS are in a non-conductive state in cases II and IV, thus the current-voltage characteristic curves are not in the positive direction. Figure 8a See also Figure 2a However, it must be considered in the direction of obstruction, which is illustrated in... Figure 8b The full characteristic curve is shown in the third quadrant.

[0057] exist Figure 9 The diagram shows a schematic flowchart of a method for determining the power loss of semiconductor structural elements in an inverter.

[0058] In measure 100, for each half-bridge of the inverter, the current phase current is received or detected.

[0059] In measure 101, the inverter's (current) regulation device receives the current switching signals and / or switching times for controlling the controllable semiconductor structural elements of the half-bridge.

[0060] In measure 102, the forward power loss of each semiconductor element of the half-bridge is determined from the phase current, the corresponding duty cycle, and the corresponding current-voltage characteristic curve, taking into account the direction of the phase current.

[0061] In measure 103, the switching power loss of each semiconductor element of the half-bridge is determined by considering the direction of the phase current, based on the turn-on energy, turn-off energy, reverse recovery energy, and the number of turn-on processes and the number of turn-off processes.

[0062] In measure 104, the total power loss of the semiconductor structure elements of the half-bridge is determined and provided by the determined forward power loss and the determined switching power loss.

[0063] Measures 102 and 103 can also be performed in reverse order or simultaneously.

[0064] Here, the power loss is determined by the adjustment cycle of the inverter's regulation device, so that measures 100-104 are repeated with each regulation cycle.

[0065] Specifically, measure 105 is configured to supply the determined total power loss of each semiconductor structural element of the inverter's half-bridge to a temperature model, which estimates the (barrier layer) temperature of the semiconductor structural elements based on the determined total power loss. The estimated value can then be taken into account when determining the power loss, particularly through temperature-dependent characteristic curves and a family of characteristic curves (see formulas in the overview description).

[0066] It can be configured to determine the corresponding duty cycle for each semiconductor structural element.

[0067] It can be configured to identify and evaluate signal edges in the switching signal in order to determine the corresponding duty cycle and / or the number of on and / or off processes.

[0068] It can be configured to determine the turn-on energy and / or turn-off energy and / or reverse recovery energy based on a family of characteristic curves, where the corresponding values ​​depend on the phase current and intermediate circuit voltage being stored. Further, it can be improved to configure the family of characteristic curves to depend on temperature.

[0069] It can be configured so that the detection time and the adjustment cycle are synchronized when detecting phase current.

[0070] List of reference numerals in the attached diagram: 1 device 2 Input devices 3. Computing equipment 4 Output devices 10 Current-voltage characteristic curve 11. Family of Characteristic Curves 30 Switch signal 31. Rising Edge (Connection Process) 32 Falling edge (disconnection process) 40 Inverter 41 Adjustment device 42 Semiconductor structural elements 43 Intermediate Circuit 44 Temperature Model 50 means of transportation 51 Traction Drive 52 motors Measures of the 100-105 method E on Connect to energy IC collector current I Ph Phase current (common) i U i V i W Phase current M engine rated torque M3~ Motor with three circuits P T,HS Total power loss (high-voltage side transistor) P T,LS Total power loss (low-side transistor) P D,HS Total power loss (high voltage side diode) P D,LS Total power loss (low-side diode) t U , t V , t W Switching time THS transistor (high voltage side) TLS transistor (low-voltage side) DHS diode (high voltage side) DLS diode (low voltage side) T T,HS (Barrier layer) temperature (high-voltage side transistor) T D,HS (Barrier layer) Temperature (High-voltage side diode) T T,LS (Barrier layer) Temperature (Low-side transistor) T D,HS (Barrier layer) Temperature (Low-side diode) T S Adjustment period (n duration) UDC intermediate circuit voltage V CE Collector-emitter voltage V F Forward voltage U phase V phase W phase Rotor position angle Rotor angular velocity ΔV / Δt Volumetric flow (coolant) T Cool Coolant temperature T init Initial temperature.

Claims

1. A method for determining the power loss (P) of a semiconductor structural element (42) of an inverter (40). T,HS , P T,LS , P D,HS ,P D,LS The method, in which, For each half-bridge of the inverter (40): - Receive or detect the current phase current (I Ph i U i V i W ), - The inverter (40) receives, via its regulating device (41), the current switching signal and / or switching time (t) of the controllable semiconductor structural elements (42) for manipulating the half-bridge. U , t V , t W ), -Considering the phase current (I) Ph i U i V i W In the case of the direction of the phase current (I), Ph i U i V i W The forward power loss of the semiconductor structure element (42) of the half-bridge is determined based on the corresponding duty cycle and the corresponding current-voltage characteristic curve (10). -Considering the phase current (I) Ph i U i V i W In the case of the direction of ) by the energy (E) on The switching loss power of the semiconductor structural element (42) is determined based on the number of disconnection energy and reverse recovery energy and the number of connection and disconnection processes; and The total power loss (P) of the semiconductor structure element (42) of the half-bridge is determined and provided by the determined forward power loss and the determined switching power loss. T,HS , P T,LS , P D,HS , P D,LS ), and wherein the determination of the power loss is performed by adjusting the cycle of the regulating device (41) of the inverter (40).

2. The method according to claim 1, characterized in that, The corresponding duty cycle is determined for each semiconductor structural element (42).

3. The method according to any one of the preceding claims, characterized in that, The current-voltage characteristic curve (10) depends on the temperature.

4. The method according to claim 1 or 2, characterized in that, In order to determine the corresponding duty cycle and / or the number of on and / or off processes, the signal edges (31, 32) in the switch signal (30) are identified and evaluated.

5. The method according to claim 1 or 2, characterized in that, The on-state energy (E) is determined starting from the family of characteristic curves. on The values ​​of the disconnection energy and / or the reverse recovery energy in the family of characteristic curves depend on the phase current (I) and / or the disconnection energy and / or the reverse recovery energy, respectively. Ph i U i V i W ) and intermediate circuit voltage (U DC ) is stored.

6. The method according to claim 5, characterized in that, The family of characteristic curves (11) depends on temperature.

7. The method according to claim 1 or 2, characterized in that, The determined total power loss (P) T,HS ,P T,LS ,P D,HS , P D,LS The temperature is supplied to the temperature model (44), wherein the temperature (T) for each of the semiconductor structural elements (42) is estimated and provided from the temperature model (44). T,HS , T D,HS , T T,LS , T D,HS ).

8. The method according to claim 1 or 2, characterized in that, In detecting the phase current (I) Ph i U i V i W The detection time is synchronized with the adjustment rhythm.

9. A method for determining the power loss (P) of a semiconductor structural element (42) of an inverter (40). T,HS , P T,LS , P D,HS ,P D,LS The apparatus (1) includes: Input device (2), Computing device (3), and Output device (4), The input device (2) is configured to receive, for each half-bridge, the currently detected phase current (Ig) of the controllable semiconductor structure element (42) for manipulating the half-bridge by the regulating device (41) of the inverter (40). Ph i U i V i W ) and the current switching signal and / or switching time (t) U , t V , t W ), The computing device (3) is configured to consider the phase current (I) for each half-bridge. Ph i U i V i W In the case of the direction of the phase current (I), Ph i U i V i W The forward power loss of the semiconductor structure element (42) of the half-bridge is determined based on the corresponding duty cycle and the corresponding current-voltage characteristic curve (10). For each half-bridge, considering the phase current (I) Ph i U i V i W In the case of the direction of ) by the energy (E) on The switching power loss of the semiconductor structural element (42) is determined based on the number of disconnection energy, reverse recovery energy, and connection processes, and the number of disconnection processes. The total power loss (P) of the semiconductor structure element (42) of the half-bridge is determined by the determined forward power loss and the determined switching power loss. T,HS , P T,LS , P D,HS , P D,LS ), And the power loss (P) T,HS , P T,LS , P D,HS , P D,LS The determination of ) is performed by the adjustment cycle of the adjustment device (41) of the inverter (40). The output device (4) is configured to provide the determined total power loss (P) of the semiconductor structure element (42) of the half-bridge. T,HS , P T,LS , P D,HS , P D,LS ).

10. A means of transport (50) comprising at least one device (1) according to claim 9.

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