METHOD FOR ACTIVE SHORT-CIRCUIT CONTROL OF AN ELECTRICAL SEMICONDUCTOR POWER INVERTER, CONTROL, SEMICONDUCTOR POWER INVERTER, SYSTEM AND COMPUTER PROGRAM PRODUCT

Abstract

A method for active short-circuit control of a semiconductor power inverter (1), comprising three electrical switches (4) on a high-side (14) and three electrical switches (4) on a low-side (15) connected to an electric rotating machine (3), comprising: determining a characteristic parameter of a current designed to occur during an active short-circuit event between the electric rotating machine (3) and the semiconductor power inverter (1); controlling the electrical switches (4) of the high-side (14) and / or the electrical switches (4) of the low-side (15) according to the characteristic parameter of the current, such that the current of the active short-circuit event is directed through the electrical switches (4) of the high-side (14) or the electrical switches (4) of the low-side (15).Furthermore, a controller, a semiconductor power inverter, a system and a computer program product are provided.

Description

The present disclosure relates to a method for active short-circuit control of a semiconductor power inverter, a controller, a semiconductor power inverter, a system, and a computer program product.During operation of a typical motor inverter, a gate unit provides gate-source signals for operation of power semiconductor elements included in the typical motor inverter. Gate signals are switched between two predefined values used to turn on or turn off the respective power semiconductor elements.During operation, a failure may occur in which control of the motor is not possible due to a failure of a general system including control, electronics, feedback, etc. A classic approach is to turn on the power semiconductor elements with the predefined values. In this way, a rotational energy of the motor at the time of occurrence of the fault is converted into heat at the power semiconductor elements. This heat is typically dissipated from a cooling system of the typical motor inverter.Embodiments of the disclosure relate to a method that is particularly reliable. A further embodiment relates to a controller which is designed to carry out such a method, to a system comprising an inverter and such a controller, and to a computer program product and a computer-readable storage medium.This is achieved by the subject matter of the independent claims. Further embodiments will become apparent from the dependent claims and the following description.A method for active short-circuit control of a semiconductor power inverter will be described. The semiconductor power inverter includes high-side electrical switches and low-side electrical switches connected to an electric rotating machine.The electric rotating machine is, for example, an electric motor and / or an electric generator configured to rotate about a rotational axis. For example, the electric motor is configured to be driven with alternating current (AC) power. For example, the electric generator is configured to generate an alternating current (AC) power. For example, the semiconductor power inverter is configured to convert a direct current (DC) power from a power source into an AC power for the electric motor and / or to convert an AC power from the electric generator into a DC power. The energy source is, for example, an accumulator which is designed to store and output electrical energy. The energy source may be part of an electric vehicle.In particular, the semiconductor power inverter includes three electrical switches on the high side and three electrical switches on the low side. The semiconductor power inverter includes a first electrical switch, a second electrical switch, a third electrical switch, a fourth electrical switch, a fifth electrical switch, and a sixth electrical switch. Alternatively, the semiconductor power inverter may have a different number of electrical switches and / or the electrical switches may have a different topology.In particular, each of the electrical switches comprises at least one power semiconductor device. The power semiconductor device includes at least one of a metal oxide semiconductor field effect transistor, MOSFET, an insulated gate bipolar transistor, IGBT, a gate commutated thyristor, IGCT, and an antiparallel diode. When the power semiconductor device includes the MOSFET or the IGBT or the IGCT and the anti-parallel diode, the anti-parallel diode is formed in anti-parallel with the active switching element, i.e., the MOSFET, the IGBT, or the IGCT.The MOSFET includes, for example, a source terminal, a drain terminal, and a gate terminal. The MOSFET is configured to control a flow of a typical current between the source terminal and the drain terminal by controlling a voltage applied to the gate terminal.The IGBT includes, for example, an emitter terminal, a collector terminal, and a gate terminal. The IGBT is configured to control a flow of a typical current between the emitter terminal and the collector terminal by controlling a voltage applied to the gate terminal. The IGCT includes, for example, an anode terminal, a cathode terminal, and a gate terminal. The IGCT is configured to control a flow of a typical current between the anode terminal and the cathode terminal by controlling a voltage applied to the gate terminal.For example, the first electrical switch is connected to the fourth electrical switch via a first bridge node, the second electrical switch is connected to the fifth electrical switch via a second bridge node, and the third electrical switch is connected to the sixth electrical switch via a third bridge node. A cathode side of the first electrical switch, of the second electrical switch and of the third electrical switch is respectively facing away from the bridge node. A cathode side of each of the third electrical switch, the fourth electrical switch, and the sixth electrical switch faces the bridge node. The first electrical switch, the second electrical switch, and the third electrical switch form the high-side switches on the high-side, and the third electrical switch, the fourth electrical switch, and the sixth electrical switch form the low-side switches on the low-side.The electric rotating machine includes, for example, a first phase line, a second phase line, and a third phase line. Each bridge node is electrically conductively connected to exactly one of the phase lines.In particular, the semiconductor power inverter is configured to control the rotating machine according to a state of the electric switches, i.e., turning on and off the electric switches. The semiconductor power inverter is configured to control the rotating machine according to a normal mode when there is no failure event.According to an embodiment of the method, a characteristic parameter of a current configured to occur during an active short circuit event between the electric rotating machine and the semiconductor power inverter is determined.The active short circuit event may be a general failure, an emergency stop event, and / or any event that may cause the semiconductor power inverter to unexpectedly terminate the normal mode of the rotating machine as the rotating machine rotates. During control of the electric rotating machine by the semiconductor power inverter, for example, the active short circuit event may occur in which control of the electric rotating machine is not possible due to a fault in a general system including a controller, electronics, feedback, etc. connected to the semiconductor power inverter and / or the electric rotating machine.When such an active short-circuit event occurs while the electric rotating machine is rotating and the semiconductor power inverter stops controlling the electric rotating machine, the semiconductor power inverter enters the active short-circuit mode. In this case, a rotational energy of the electric rotating machine flows in the form of the current through the semiconductor power inverter and either starts charging an intermediate circuit capacitor or flows to a power source, e.g. the accumulator.In particular, the characteristic parameter of the current is characteristic of a peak of the current between the semiconductor power inverter and the electric rotating machine during the active short circuit event. For example, the peak of current from the semiconductor power inverter to the electric rotating machine and / or from the electric rotating machine to the semiconductor power inverter occurs during the active short circuit event.For example, the characteristic parameter of the current during an active short circuit event may be predetermined for a future active short circuit event. That is, the characteristic parameter may be precomputed before the current short circuit event actually occurs.According to the embodiment, the high-side electrical switches and / or the low-side electrical switches are controlled according to the characteristic parameter of the current such that the current of the active short-circuit event is conducted through the high-side electrical switches or the low-side electrical switches. The high-side electrical switches and the low-side electrical switches are controlled according to a certain polarity of the peak of the current, for example.In particular, the peak of the current occurring during the active short circuit event is conducted through the respective electrical switches, i.e. respective body diodes of the MOSFETs, respective reverse MOSFET channels or respective anti-parallel diodes of the respective electrical switches, according to the polarity of the peak.In particular, the electronic switches that are turned on during the active short-circuit event are not activated randomly, but depend on the peak of the current, in particular an unexpected current, of the active short-circuit event. The peak of the current is conducted to the body diode of the MOSFET, the reverse MOSFET channel, or the anti-parallel diode, which can maintain more current during the active short circuit event.For example, the inverse diode of the MOSFET has more surge current capability than the forward direction. Thus, by diverting the peak of the current during the active short circuit event, as suggested, through all high side electrical switches or all low side electrical switches, the capability of the active short circuit current can be significantly increased.For example, the process is carried out in the order given. In particular, the determination of the characteristic parameter of the current occurring during the active short-circuit event can take place before, and / or when the active short-circuit event occurs.Advantageously, performing the method described herein allows the semiconductor power inverter to maintain more short circuit current, which results in, in particular, a greater margin for application current, a lesser number of electrical switches required to maintain the same amount of current, lower cost of the semiconductor power inverter, and increased reliability and durability.Such a method is advantageously implemented in semiconductor power inverters included in automotive applications. For example, an electric vehicle may be equipped with such a semiconductor power inverter configured to perform such a method described herein.According to a further embodiment of the method, if the characteristic parameter of the current is represented by a peak of the current and the peak of the current is characteristic of a positive current value, the electrical switches of the high-side are controlled in such a way that they block the current and the electrical switches of the low-side are controlled in such a way that they transmit the current. The peak of the current is characteristic of a maximum current flowing through the circuit during the active short circuit event.The respective electrical switch is configured to block current when the electrical switch is in an off state, i.e., turned off, and the respective electrical switch is configured to transmit current when the electrical switch is in an on state, i.e., turned on. In particular, the electrical switch is in the on state or in the off state depending on the respective gate voltage applied to the gate terminal of the respective electrical switch.For example, the peak current of the active short circuit event has the positive current value characteristic of a positive direction or a negative current value characteristic of a negative direction. The current of the active short circuit event has a positive direction when the current flows from the semiconductor power inverter to the electric rotating machine. The current of the active short circuit event has a negative direction when the current flows from the electric rotating machine to the semiconductor power inverter.When the peak of the current in the positive direction occurs on at least one of the three phase lines, the high-side electric switches of the semiconductor power inverter are turned off, and the low-side electric switches of the semiconductor power inverter are turned on. In particular, the high-side electrical switches are turned off at a negative voltage at the gate terminal, and the low-side electrical switches are turned on at a positive voltage at the gate terminal.According to another embodiment of the method, if the characteristic parameter of the current is represented by a peak of the current and the peak of the current is characteristic of a negative current value, the electrical switches of the high-side are controlled in such a way that they transmit the current, and the electrical switches of the low-side are controlled in such a way that they block the current.When the peak of the current in the negative direction occurs on at least one of the three phase lines, the low-side electric switches of the semiconductor power inverter are turned off, and the high-side electric switches of the semiconductor power inverter are turned on. In particular, the low-side electrical switches are turned off at a negative voltage at the gate terminal, and the high-side electrical switches are turned on at a positive voltage at the gate terminal.For example, the voltage supplied to the gate terminals for switching the respective electrical switch on and off is manufacturer-dependent. That is, a magnitude of the voltage may be individually predetermined according to the electric switches used.According to a further embodiment of the method, the characteristic parameter of the current is determined based on a model of the electric rotating machine.For example, the model is represented by a d-q model. In particular, the d-q model of the electric rotating machine is characteristic of a mathematical model representing a rotational behavior of an electric three-phase machine in a rotating reference system. For example, in the d-q model, a d-axis current and a q-axis current are determined. In particular, the d-axis current and the q-axis current are dependent on parameters of components of the electric rotating machine, such as resistances of the components, inductances of the components, rotor flux positions and / or operating conditions of the components. The currents on the three phase lines, in particular each current on each of the three phase lines, can be determined as a function of the d-axis current and the q-axis current.For example, the peak of the current, which in particular has the positive current value or the negative current value, during the active short circuit event is precomputed based on the d-q model.For example, the characteristic parameter of the current is determined based on a look-up table of parameters depending on the electric rotating machine model and actual parameters of the electric rotating machine. For example, the look-up table includes multiple different sets of parameters of the components of the electric rotating machine to which the respective peak of the current is associated. In particular, by a comparison between the look-up table and the actual parameters during the active short circuit event, the peak of the current, i.e. the positive current value or the negative current value, in particular on each of the three phase lines, can be determined.According to a further embodiment of the method, the characteristic parameter of the stream is determined based on a real-time calculation. For example, the d-axis current and the q-axis current and the resulting currents for each of the three phase lines during operation of the electric rotating machine may be calculated based on the d-q model.According to a further embodiment of the method, the characteristic parameter of the current is determined based on a measurement value of the semiconductor power inverter.For example, the current flowing during the active short circuit event is monitored by a sensing device. In this case, the detection device may determine the characteristic parameter directly by measuring.According to a further embodiment of the method, the current is controlled such that it is alternately transmitted through the electrical switches of the high side and through the electrical switches of the low side. In particular, the electrical switches of the high side and the electrical switches of the low side are alternately switched on and off in good time.For example, the high-side electrical switches are turned off for a first period of time and the low-side electrical switches are turned on for a second period of time immediately after the first period of time. Alternatively, the high-side electrical switches are turned on for a first period of time and the low-side electrical switches are turned off for a second period of time immediately after the first period of time.In particular, the first time period and the second time period are repeated alternately over time. The first time period and the second time period may have the same length or are different from each other. In particular, a duration of the first time period and the second time period may be predefined and / or actively calculated during the active short circuit event.According to another embodiment of the method, an initial current transfer is controlled to be performed by the high-side electrical switches or by the low-side electrical switches corresponding to a peak value. The peak value is characteristic of, for example, the positive current value or the negative current value of the peak of the current during the active short circuit event. In particular, the initial current transfer is represented by the current transferred during the initial first time interval.When the peak is positive, the initial current transfer through the low-side electrical switches is performed so that the high-side electrical switches are controlled to block the current and the low-side electrical switches are controlled to transfer the current.When the peak value is negative, the initial current transfer is performed by the high-side electric switches, so that the low-side electric switches are controlled to block the current, and the high-side electric switches are controlled to transfer the current.According to a further embodiment of the method, the current comprises three phases. Specifically, the three phases are formed of a first phase provided for the first phase line, a second phase provided for the second phase line, and a third phase provided for the third phase line. That is, the current flowing during the active short circuit event is provided on all of the three phase lines.According to a further embodiment of the method, all of the phases are transmitted by all of the electrical switches of the high side or all of the electrical switches of the low side. In particular, all high-side electronic switches are turned on or off during the active short circuit event. In particular, all of the low-side electronic switches are turned on or off during the active short circuit event.According to a further embodiment of the method, the peak of the current corresponds to one of the phases.A further embodiment relates to a controller for active short-circuit control of a semiconductor power inverter, which is designed in particular for carrying out the method described here above. Therefore, the features described in connection with the controller also apply to the method and vice versa.Another embodiment relates to a semiconductor power inverter for active short circuit control, including in particular the controller described hereinabove. Therefore, the features described in connection with the semiconductor power inverter also apply to the control and vice versa.Another embodiment relates to a system for active short-circuit control of a semiconductor power inverter, including in particular the controller and the semiconductor power inverter described hereinabove. Thus, the features described in connection with the controller and the semiconductor power inverter also apply to the controller and vice versa.According to an embodiment, the system further comprises an electric rotating machine connected to the semiconductor power inverter. In particular, the electric rotating machine is in particular an electric motor and / or an electric generator which is designed to rotate about an axis of rotation.Another embodiment relates to a computer program product comprising instructions that, when the computer program is executed by a processor, cause the computer program to perform the method described herein above. In particular, the computer program product can be implemented as a hardware controller, software controller and / or firmware controller or combinations thereof.According to an embodiment of the computer program product, means and / or the controller described hereinabove for executing the computer program product are physically implemented in the system described hereinabove.According to one embodiment, the computer program product is a volatile data file that must be introduced via a data interface into the system and / or controller described hereinabove.A further embodiment relates to a computer-readable storage medium in which the computer program product described above is stored.The accompanying figures are provided to provide a better understanding. In the figures, elements having the same structure and / or functionality may be denoted by the same reference numerals. It is understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. FIG. 1 schematically shows a flow chart of a method for active short-circuit control of a semiconductor power inverter according to an embodiment. FIG. 2 schematically shows a system according to an embodiment. FIG. 3 schematically shows a response to the active short circuit.FIGS. 4 and 5 each schematically show a system according to an exemplary embodiment.Method step S 1 according to the embodiment of FIG. 1 comprises a determination of a characteristic parameter of a current configured to occur during an active short circuit event between an electric rotating machine 3 and a semiconductor power inverter 1.Specifically, the semiconductor power inverter 1 is configured to control an electric rotating machine 3 during a normal control mode. That is, all the components electrically connected to the semiconductor power inverter 1 normally function during the normal control mode. However, an active short-circuit event may occur in which control of the electric rotating machine 3 is not possible due to a failure in any of the components electrically connected to the semiconductor power inverter 1, i.e., a general system.When the active short-circuit event occurs, the semiconductor power inverter 1 can no longer control the electric rotating machine 3. Specifically, the semiconductor power inverter 1 switches from an active short-circuit mode different from the normal mode. For example, the semiconductor power inverter 1 shifts to the active short-circuit mode depending on a current threshold value. The current threshold is characteristic of a current value at which the semiconductor power inverter 1 is in the normal mode. That is, when the current exceeds the current threshold, the semiconductor power inverter 1 shifts to the active short-circuit mode.The electric rotating machine 3 is still rotating during the active short circuit event, thereby generating electric power that is supplied to the semiconductor power inverter 1 in the form of a current. Specifically, the current is supplied to each of the three phase lines connecting the electric rotating machine 3 and the semiconductor power inverter 1, as shown in FIG. 3.In particular, a peak of the current, which is the characteristic parameter of the current, is determined during the active short circuit event in the active short circuit mode. Specifically, it is determined whether the peak of the current has a positive current value or a negative current value. The determination of the characteristic parameter of the current may be performed according to a model of the electric rotating machine 3 before the actual short-circuit event. That is, a manufacturer may provide information that the peak of the current has the positive current value or the negative current value. Alternatively, the peak of the current, in particular its polarity, can be determined by a comparison with a look-up table based on a real-time calculation or based on a measurement value of the inverter 1.In short, in step S 1, the characteristic parameter of the current is determined, e.g., it is determined whether the peak of the current has a positive current value or a negative current value during the active short-circuit event.The semiconductor power inverter 1 includes three electrical switches 4 on a high side 14 and three electrical switches 4 on a low side 15 connected to the electric rotating machine, as will be described in detail in FIG. 2.When determining the characteristic parameter of the current during the active short-circuit event, in a method step S 2 the electrical switches 4 of the high side 14 and / or the electrical switches 4 of the low side 15 are controlled in accordance with the characteristic parameter of the current.When the peak of the current has a positive current value, the electric switches 4 of the high side 14 are controlled to block the current, and the electric switches 4 of the low side 15 are controlled to transmit the current.When the peak of the current has a negative current value, the electric switches 4 of the high side 14 are controlled to transmit the current, and the electric switches 4 of the low side 15 are controlled to block the current.That is, according to the polarity of the current occurring during the active short circuit event, the current is conducted through body diodes of MOSFETs of the respective electrical switches 4, the reverse MOSFET channels of the respective electrical switches 4, or the anti-parallel diodes of the respective electrical switches 4.The system 16 according to the embodiment of FIG. 2 includes a semiconductor power inverter 1 positioned on and electrically connected to a power source 2, which is, for example, an accumulator, and an electric rotating machine 3.The semiconductor power inverter 1 comprises a first electrical switch 5, a second electrical switch 6 and a third electrical switch 7, which form the switches of the high side 14, and a fourth electrical switch 8, a fifth electrical switch 9 and a sixth electrical switch 10, which form the switches of the low side 15.Each of the electric switches 4 includes a MOSFET. Each of the electrical switches 4 may further include an anti-parallel diode.The first electrical switch 5 and the fourth electrical switch 8 are connected via a first bridge node 11, the second electrical switch 6 is connected via a second bridge node 12 to the fifth electrical switch 9, and the third electrical switch 7 is connected via a third bridge node 13 to the sixth electrical switch 10. Cathode sides of the switches of the high side 14 face away from the bridge nodes, and cathode sides of the switches of the low side 15 face towards the bridge nodes.The electric rotating machine 3 is a three-phase electric machine 3 connected to the semiconductor power inverter 1 through a first phase line, a second phase line, and a third phase line. The first phase line is connected to the first bridge node 11, the second phase line is connected to the second bridge node 12, and the third phase line is connected to the third bridge node 13.The current occurring on the first phase line, the second phase line, and the third phase line as a transient response to the active short circuit event is exemplarily shown in the diagram of FIG. 3. The y-axis corresponds to a transient current in amperes and the x-axis corresponds to a time in seconds.For example, the current occurring between the first bridge node 11 and the electric rotating machine 3 is the current C 11, the current occurring between the second bridge node 12 and the electric rotating machine 3 is the current C 12, and the current occurring between the third bridge node 13 and the electric rotating machine 3 is the current C 13.In this example, the current peak of the current during the active short circuit event is determined to be the current C 12 occurring between the second bridge node 12 and the electric rotating machine 3. Further, the peak value is determined to be positive.The example diagrams of FIGS. 4 and 5 show a surge current capability of an electrical switch comprising a SiC MOSFET with respect to a reverse direction running from the source to the drain in a MOSFET body diode and with respect to a forward direction running from the drain to the source in a MOSFET channel. The reverse direction shown in FIG. 4 may maintain more current, e.g., about 3.2 kA, with about the same energy, e.g., about 120 J, as the forward direction shown in FIG. 5, e.g., about 2.3 kA.The left y-axis corresponds to a transient current in amps, the right y-axis corresponds to a pulse energy in J, and the x-axis corresponds to a time in seconds.In particular, the transient current is characteristic of a half sinusoidal current pulse supplied to the power semiconductor device by a power source, e.g. a current source. The current has an increased current peak with each pulse, and a state of the power semiconductor device is evaluated after each pulse. The test ends when the power semiconductor device is destroyed. FIGS. 4 and 5 relate to such a test in which they show the most recently successful pulse before the power semiconductor device is destroyed, and therefore represent the surge current capability of the power semiconductor device.Reference numerals denote reference numerals1 Semiconductor power inverter 2 Energy source 3 Electric rotating machine 4 Electric switch 5 First electric switch 6 Second electric switch 7 Third electric switch 8 Fourth electric switch 9 Fifth electric switch 10 Sixth electric switch 11 First bridge node 12 Second bridge node 13 Third bridge node 14 High-side 15 Low-side 16 System S 1..S 2 Method steps P Peak C 11..C 12 Current

Claims

Method for active short-circuit control of a semiconductor power inverter (1) comprising electrical switches (4) on a high side (14) and electrical switches (4) on a low side (15) connected to an electric rotating machine (3), comprising - determining a characteristic parameter of a current configured to occur between the electric rotating machine (3) and the semiconductor power inverter (1) during an active short-circuit event, - controlling the electrical switches (4) of the high side (14) and / or the electrical switches (4) of the low side (15) according to the characteristic parameter of the current, such that - the current of the active short-circuit event is conducted through the electrical switches (4) of the high side (14) or the electrical switches (4) of the low side (15).Method according to claim 1, wherein: - if the characteristic parameter of the current is represented by a peak of the current and the peak of the current is characteristic of a positive current value, - the electrical switches (4) of the high side (14) are controlled to block the current, and - the electrical switches (4) of the low side (15) are controlled to transmit the current.Method according to claim 1, wherein - if the characteristic parameter of the current is represented by a peak of the current and the peak of the current is characteristic of a negative current value, - the electrical switches (4) of the high side (14) are controlled to transfer the current, and - the electrical switches (4) of the low side (15) are controlled to block the current.Method according to any one of claims 1 to 3, wherein - the characteristic parameter of the current is determined based on a model of the electric rotating machine (3).Method according to one of claims 1 to 4, wherein - the characteristic parameter of the stream is determined based on a real-time calculation.Method according to one of Claims 1 to 5, wherein - the characteristic parameter of the current is determined on the basis of a measurement value of the semiconductor power inverter (1).Method according to one of claims 1 to 6, wherein - the current is controlled in such a way that it is alternately transmitted through the electrical switches (4) of the high side (14) and through the electrical switches (4) of the low side (15).Method according to claim 7, wherein: - an initial current transfer is controlled to be performed by the electrical switches (4) of the high side (14) or by the electrical switches (4) of the low side (15) according to a peak value.Method according to one of claims 1 to 8, wherein - the current comprises three phases, and - all of the phases are transmitted through all of the electrical switches (4) of the high side (14) or all of the electrical switches (4) of the low side (15).The method of claim 9, wherein: - the peak of the current corresponds to one of the phases.A controller for active short circuit control of a semiconductor power inverter (1), the controller being configured to perform the method of any one of claims 1 to 10.A semiconductor power inverter (1) for active short circuit control, comprising: - the controller according to claim 11.A system (16) for active short-circuit control of a semiconductor power inverter (1) comprising: - the controller according to claim 11, - the semiconductor power inverter (1) according to claim 12, and - an electric rotating machine (3) connected to the semiconductor power inverter (1).A computer program product comprising instructions which, when the computer program is executed by a processor, cause the computer program to carry out the method of any one of claims 1 to 10.The computer program product of claim 14, wherein means and / or the controller of claim 11 for executing the computer program product is / are physically implemented in the system (16) of claim 13.The computer program product of claims 13 and 14, wherein the computer program product is a volatile data file to be introduced into the system (16) and / or the controller via a data interface.A computer readable storage medium storing the computer program product of claims 14 to 16.

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