Test system for an electric powertrain

Abstract

Test system (10) for carrying out a test operation and recording an operating behavior of an electric drive train and an on-board network of a vehicle, comprising: a power input (2) for receiving an externally provided DC input power which is fed into the test system (10); a battery emulator module (3) for emulating a traction battery in the drive train, the battery emulator module (3) comprising: a controllable DC / DC converter (31) for converting the DC input power fed into the test system (10) into a DC output power of the emulated traction battery, and an emulation control device (32) for generating and outputting control signals for the DC output power to the DC / DC converter, wherein the control signals are generated as a function of emulation parameters stored in a model from at least one internal resistance and a state of charge of the emulated traction battery; a motor module (4) for receiving and converting a drive power of a traction motor in the drive train; and an inverter test object (5) for converting a DC output power of the emulated traction battery into a multi-phase AC output power for the motor module (4); characterized in that the test system (10) further comprises an on-board network emulator module (6) for emulating an on-board network connected to the drive train, wherein the on-board network emulator module (6) comprises: a substantially real-time capable interface (7) connected between the on-board network emulator module (6) and the motor module (4) for transmitting parameters of a position angle of a motor rotor from the motor module (4), a controllable power electronics circuit (61) for imposing amplitudes on a voltage and current supply of a power output of the on-board network emulator module (6) to the inverter test object (5), in accordance with an impedance of the emulated on-board network, and an emulation control device (62) for generating and outputting control signals for an impedance behavior of the emulated vehicle electrical system to the power electronics circuit (61), wherein the control signals are generated as a function of a harmonic model stored in a memory and the position angle transmitted from the motor module (4) to the vehicle electrical system emulator module (6) via the interface (7).

Description

The present invention relates to a test system for carrying out a test operation and detecting an operating behavior of an electric drive train and of an on-board power supply system of a vehicle.The test system is used in product development for components in an electric drive train and components of a DC on-board power supply system which is electrically connected to the drive train.Constructions of test stands for testing test specimens are known, in particular with respect to an inverter for transforming a drive power and controlling phase currents of an electric traction motor, in which components such as a traction battery are replaced by a battery emulator. Such battery emulators primarily map a power output and output voltage of the emulated battery on a power output to the inverter test object as a function of a virtual state of charge (SOC) or an internal resistance of the battery. In practice, however, there are numerous further influences on a power input at an inverter for an electric drive, to which a regulation of the power conversion and activation of an inverter should react or which determine the functionality of the test object. Documents DE 10 2021 121 188 A1 and CN 1 10 737 207 A are known here from the prior art, for example.For example, in response to harmonics of the electric drive, influences in the sense of an oscillating circuit occur on the upstream electric drive train and consumers in the vehicle electrical system connected thereto, in a retroactive manner via the inverter, for the occurrence of which a regulation of the inverter and also any other component connected to the vehicle electrical system can be optimized. In electrically motorized vehicles, the power consumption of the drive takes up such a large load proportion in the total power to be fed in through a battery store that an impedance of the battery store and, in particular, the multiplicity of other loads on a DC bus of the on-board power supply system and an impedance of the conductors lying therebetween are relevant for a regulation behavior of the inverter in test operation, and the realistic mapping thereof is desirable.It is an object of the invention to provide a technique in a test stand for testing an inverter, which makes it possible to more realistically map an impedance and thus occurring resonances of the upstream electric drive train and on-board power supply system to the power consumption of the inverter test object. Furthermore, it is an object of the invention that interferences which arise as a result of interactions of a plurality of consumers, i.e. subscribers on the DC bus, are realistically simulated without these further subscribers having to be present in real form in the test system. A more specific object of the invention is to map an influence and a reaction of harmonics of a drive frequency of the electric drive on the emulated on-board power supply system.The above objects are achieved by a test system having the features of claim 1.The test system according to the invention serves for carrying out a test operation and detecting an operating behavior of an electric drive train and of an on-board power supply system of a vehicle. For this purpose, the test system comprises a power input, a battery emulator module, a motor emulator module, an inverter test object and an on-board power system emulator module according to the invention.The power input is provided for receiving an externally provided DC input power that is fed into the test system. The battery emulator module emulates a traction battery in the drive train and for this purpose comprises: a controllable DC / DC converter for converting a DC input power fed into the test system into a DC output power of the emulated traction battery, and an emulation control device for generating and outputting control signals for the DC output power to the DC / DC converter, wherein the control signals are generated from at least one internal resistance and one state of charge of the emulated traction battery as a function of emulation parameters stored in a model.The motor module receives a drive power of a traction motor and converts it into the drive train. The inverter DUT converts a DC output power of the emulated traction battery to a polyphase AC output power for the motor module.According to the invention, the test system has, in particular, an on-board power system emulator module which emulates an on-board power system which is connected to the drive train. For this purpose, the vehicle electrical system emulator module comprises an interface which is capable of substantially real time and is signal-connected between the vehicle electrical system emulator module and the motor module for the parameter transmission of a position angle of a motor rotor from the motor module. A controllable power electronics circuit applies amplitudes to a voltage and current supply of a power output of the on-board electrical system emulator module to the inverter test object, in accordance with an impedance of the emulated on-board electrical system.An emulation control device outputs control signals for an impedance behavior of the emulated on-board power system to the power electronics circuit. The control signals are generated in this case as a function of a harmonic model stored in a model and the position angle transmitted from the motor module via the interface to the on-board electrical system emulator module.In the present disclosure, the term emulation, in particular in contrast to a simulation, is defined as follows: a simulation reproduces a basic behavior of a system having a predetermined configuration in a virtual environment. Emulation also simulates behavior and interaction of all the involved hardware and software features of the system that result in the result that the simulation outputs or would arise in real terms. Thus, with approximately the same system behavior, it is possible to exchange real system components by emulated duplicates of the real system components within the system and to combine them with one another.The invention thus provides for the first time for an emulation of a complex impedance behavior which is reproducible, in-phase and adaptable by means of a test system and is excited by harmonics of the test object or other peripheral devices. The emulation at an interface to an inverter test object corresponds for the first time to an operating behavior with equivalent resonant circuits made of components and conductors of a real on-board power supply system, in feedback to a position angle of a motor rotor of the electric drive and excited harmonics on other devices connected to the on-board power supply system.Furthermore, the invention provides for the first time, in a test stand design, for example, a circuit-related implementation of a modulated application of voltage and current supply fluctuations based on a stored harmonic model by means of a power electronic circuit of an oscillating circuit, in a power pass to the inverter test object, corresponding to said emulation. The vehicle electrical system emulator module can take into account additional harmonic models, for example from other consumers on a DC bus, in the case of angle synchronization or in the correct phase at the emulation of the vehicle electrical system.A considerable advantage of the invention is that it is possible to carry out a testing of inverters in a more realistic system environment, which can also depict considerable impedance effects and interactions, as are typically transferred to the other consumers of an on-board power supply system in drives.In this context, a further advantage of the invention results for the product development of inverters for electric drives, since their regulation with the aid of test cycles on such improved test stands, to fluctuations of a voltage and current supply resulting on the input side from impedance effects in an on-board power supply, can be functionally sensitized and accordingly optimized.According to an advantageous aspect of the invention, the motor module can also be replaced by a motor emulator module for emulation of a traction motor in the drive train, wherein the motor emulator module comprises: a controllable power electronics circuit for implementing a characteristic power consumption of the emulated traction motor; and an emulation control device for generating and outputting control signals for the power consumption to be implemented to the power electronics circuit, wherein the control signals are output from a design, a dimensioning, a drive load and / or the position angle of the motor rotor of the emulated traction motor as a function of at least one emulation parameter stored in a model. Thus, the largest power consumer can also be mapped within the scope of emulation.According to an alternative advantageous aspect of the invention, the motor module can have an electric traction motor for absorbing power in the drive train, having a sensor for detecting the position angle of the motor rotor of the traction motor. Thus, a system environment as realistic as possible is provided for the inverter test object with an interface to a real system component.According to an advantageous aspect of the invention, a circuit of the on-board electrical system emulator module and a circuit of the battery emulator module, in particular a control circuit, can be integrated with one another. Thus, control tasks, signal generation, parameters, memories, and a power circuit may be sharedAccording to an advantageous aspect of the invention, a filter circuit for frequency filtering can also be provided in the test system, which is arranged between the emulated traction battery and the inverter test object in the on-board power supply system. Thus, further control-technology conditions for implementing the emulation can be applied in terms of circuitry to a power output to the inverter test object.According to an advantageous aspect of the invention, the test system can furthermore have an AC power sensor for detecting polyphase AC power output by the inverter test object to the motor module, and the interface which is capable of substantially real time can transmit a power signal which the AC power sensor generates as a function of the detected AC power to the on-board power system emulator module. Thus, a signal feedback for generating the emulated impedance behavior in response to the electric drive can be shortened by means of a detection thereof.According to an advantageous aspect of the invention based thereon, a pilot control module for generating and outputting pilot control signals for the impedance behavior of the emulated on-board electrical system to the power electronics circuit of the on-board electrical system emulator module can be provided in the test system, wherein the pilot control signals are generated as a function of the AC output power detected by the AC power sensor, which is output by the inverter test object to the motor module. Thus, a pilot control, which is connected to the shortened signal feedback, for improved generation of the emulated impedance behavior can be realized.According to an advantageous aspect of the invention, an auxiliary unit emulator module for generating and outputting control signals for a vibration pattern of a DC auxiliary unit to the power electronics circuit of the on-board power system emulator module can furthermore be provided in the test system, wherein the control signals are generated as a function of parameters stored in a model which represent a reaction of a DC auxiliary unit to harmonics in the on-board power system. The parameters stored in the model are functions or ratios of amplitudes and frequencies of a resonant oscillation in relation to amplitudes and frequencies of an exciter oscillation. Thus, the emulation of the on-board power supply system can be improved since resonant circuit effects are also depicted which occur as a function of further DC loads and which are influenced by the power consumption of the electric drive from the on-board power supply system.According to an advantageous aspect of the invention, the battery emulation module and the on-board power system emulator module can be provided by a multilevel converter device clocked at high frequency. Thus, a circuit configuration of the test system is simplified.Further advantages, features and details of the invention are evident from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. It shows schematically: FIG. 1 is a schematic block diagram of a test system according to an embodiment of the invention; FIG. 2 is a functional block diagram illustrating emulated system components by a test system according to an embodiment of the invention; and FIG. 3 shows a functional block diagram for the comparative representation of the emulated or only simulated system components by a test system in the prior art.FIG. 1 shows a structure of a test system 10 for carrying out an emulated test operation, in which an inverter 5 is tested as a real component while further components of an electrical drive train are emulated.The stationary test system 10 shown in FIG. 1 is fed from a supply network which has, for example, an alternating or three-phase current with a voltage of 400 V. The mains current is converted by an upstream AC / DC converter 1 into a direct current with a predetermined system voltage and fed to a DC power input 2 of the test system 10. Alternatively, a sufficiently powerful DC network can likewise be available in the environment of a test laboratory, from which the predetermined system voltage at the power input 2 is fed into the test system 10.A battery emulator module 3 includes a DC / DC converter 31 that converts the system voltage to a simulated traction battery traction voltage of, e.g., 400V or 800V, and an emulation controller 32 that controls the DC / DC converter 31. Thus, for example, voltage fluctuations during load changes or a voltage decrease as a function of a state of charge are emulated. The battery emulator module 3 has at least two outputs with at least one positive and one negative potential which are provided for a power supply of the inverter 5 to be tested, wherein alternatively a plurality of outputs can likewise be provided in a so-called multilevel configuration. A filter circuit 8 is connected between a power output stage of the battery emulator 3 and the inverter 5, said filter circuit comprising, for example, 2nd order and 4th order filters for frequency filtering.For power consumption from the inverter 5, a motor module 4 is provided in the test system 10. The motor module 4 is driven by the inverter and converts a driving power according to a required driving load.In the embodiment shown in FIG. 1, the motor module 4 is designed as a motor emulation module 40 which comprises a power electronics circuit 41 which implements as loads a characteristic power consumption of a traction motor and an emulation control device 42 which controls the power electronics circuit 41. Alternatively, the motor module 4 can be designed as a real electric motor, in particular a traction motor dimensioned according to the application. Emulation control device 42 outputs a position angle of a motor rotor of the emulated or real traction motor via a real-time capable interface 7 to an on-board power system emulator module 6. Furthermore, an AC power sensor 43 is connected upstream of the motor module 4, which detects a polyphase AC power on the input side, which is output by the inverter 5 to the motor module 4. The real-time interface 7 also transmits a power signal of the AC power detected at the motor module 4 to the on-board power system emulator module 6.The vehicle electrical system emulator module 6 influences the power supply from the emulated traction battery by means of a power electronic circuit 61 in order to depict impedances and resonant circuit effects which occur in a vehicle electrical system. The power electronic circuit 62 is controlled by an emulation control device 61 of the on-board power system emulator module 6. For this purpose, amplitudes of a voltage fluctuation and current fluctuation are impressed on the power outputs of the battery emulator 3 in accordance with an emulated impedance behavior. The emulated on-board power supply system reproduces an impedance behavior of the battery and a conductor structure of the drive train mounted upstream, which is caused in response to harmonic frequencies from a power consumption of the motor module 4 in a retroactive manner via the inverter 5 in the on-board power supply system mounted upstream. Since the position angle of the motor rotor of the emulated or real traction motor of the motor module 4 is a decisive operating parameter for the harmonics and for the generation of an emulated impedance behavior of the on-board power supply system that responds thereto, the on-board power supply system emulator module 6 is signal-connected to the motor module 4 via the interface 7 capable of real time for the transmission of the position angle. During emulation of the on-board power supply system, an actual impedance of filters and of a wiring system is also taken into account, so that a real emulated behavior of the on-board power supply system is present at a terminal of inverter 5.Further, the on-board power system emulator module 6 acquires, from the AC power sensor 43 of the motor module 4 via the same interface 7, information on the polyphase AC output power output output from the inverter 5 and received in the motor module 4. The vehicle electrical system emulator module 6 generates a pilot control as a function of the detected polyphase AC output power by the emulation control device 62, in particular by a pilot control module 63 integrated therein. The pilot module 63 generates control signals for the power electronics circuit 61 for imposing the emulated impedance response using a shorter feedback loop than via the parameter of the position angle of the motor rotor.Furthermore, the on-board power supply system emulator module 6 comprises an auxiliary unit emulator module 64, which is integrated in particular with the emulation control device 62, for generating control signals for emulated resonant circuit effects which are caused in response to harmonic frequencies at DC loads such as auxiliary units in the on-board power supply system. For this purpose, the position angle provided via the interface 7 and the harmonics from stored models are again included in the emulation of the impedance behavior, wherein the response of the emulated auxiliary units is impressed on the power outputs to the inverter 5 by means of the power electronics circuit 61 of the on-board power system emulator module 6. Optionally, for this impression, further power electronics can be provided, which is configured in the form of a rib emulator.The on-board power supply system emulator module 6 and the battery emulator module 3 are integrally formed with respect to hardware and software and are realized by a multilevel converter clocked at high frequency. Given a suitable specification and a sufficient bandwidth of the multilevel converter, the 2nd order filter in the filter circuit 8 is omitted, wherein in this case a design of a limit frequency is significantly above the frequencies to be emulated.FIG. 2 shows, in a functionally summarized manner, the completed mapping of components of the emulated on-board power supply system, which is emulated in the test system 10 by the on-board power supply system emulator module 6 in a realistic manner for the purpose of testing and product development of inverters 5. This is clear in a comparison with FIG. 3, which represents the prior art, and in which only emulation of the battery and, if appropriate, of the motor has hitherto been carried out.The realistic mapping of components by an emulated on-board power supply system, which takes into account impedance or resonant circuit effects of the conductors and components of the on-board power supply system in response to the harmonics generated from the drive, is based on the feedback of the position angle of the motor rotor, and preferably also a direct feedback of information about the AC power which is fed in at the motor module 4 from the inverter 5, stored models of an impedance behavior, and a generation of control signals based thereon by the emulation control device 62 for the power electronics circuit 61, which finally applies the emulated impedance behavior of the on-board power supply system to the current and voltage supply to the inverter test object as a technical effect.As described, in an alternative embodiment, a traction motor may be provided as a real component in place of the motor emulator module 40 in the test system 10. In this case, the AC power sensor 43 is disposed between the inverter 5 and the traction motor to detect the polyphase AC output power of the inverter 5. A rotor position detection is likewise attached to the traction motor in order to transmit, in addition to the power, also the required position angle via the interface 7 to the on-board electrical system emulator module 6 or the pilot control module 64 integrated therein.The above explanations of the embodiments describe the present invention exclusively within the scope of examples. Of course, individual features of the embodiments can be freely combined with one another, insofar as technically expedient, without departing from the scope of the present invention.List of reference characters1 AC / DC converter 2 power input 3 battery emulator module 4 motor module 5 inverter 6 on-board power supply emulator module 7 interface 8 filter circuitry 10 test system 31 DC / DC converter 32 emulation control device 40 motor emulator module 41 power electronics circuit 42 emulation control device 43 AC power sensor 61 power electronics circuit 62 emulation control device 63 pilot module 64 auxiliary unit emulator module

Claims

Test system (10) for carrying out a test operation and detecting an operating behavior of an electric drive train and of an on-board power supply system of a vehicle, having: a power input (2) for receiving an externally provided DC input power which is fed into the test system (10); a battery emulator module (3) for emulation of a traction battery in the drive train, the battery emulator module (3) comprising: a controllable DC / DC converter (31) for converting the DC input power fed into the test system (10) into a DC output power of the emulated traction battery, and an emulation control device (32) for generating and outputting control signals for the DC output power to the DC / DC converter, wherein the control signals are generated from at least an internal resistance and a state of charge of the emulated traction battery as a function of emulation parameters stored in a model; a motor module (4) for receiving and converting a drive power of a traction motor in the drive train; and an inverter test specimen (5) for converting a DC output power of the emulated traction battery into a polyphase AC output power for the motor module (4); characterized in that the test system (10) also has an on-board power system emulator module (6) for emulation of an on-board power system which is connected to the drive train, wherein the on-board power system emulator module (6) comprises: a substantially real-time-capable interface (7) which is connected between the on-board power system emulator module (6) and the motor module (4), for parameter transmission of a position angle of a motor rotor from the motor module (4), a controllable power electronics circuit (61) for imparting amplitudes to a voltage and current supply of a power output of the on-board power system emulator module (6) to the inverter test specimen (5), in accordance with an impedance of the emulated on-board power supply system, and an emulation control device (62) for generating and outputting control signals for an impedance behavior of the emulated on-board power supply system to the power electronics circuit (61), wherein the control signals are generated as a function of a harmonic model stored in a memory and the position angle transmitted from the motor module (4) via the interface (7) to the on-board power supply system emulator module (6).Test system (10) according to Claim 1, wherein the motor module (4) has a motor emulator module (40) for emulation of a traction motor in the drive train, wherein the motor emulator module (40) comprises: a controllable power electronics circuit (41) for implementing a characteristic power consumption of the emulated traction motor; and an emulation control device (42) for generating and outputting control signals for the power consumption to be implemented to the power electronics circuit (41), wherein the control signals are generated as a function of at least one emulation parameter, which is stored in a model, from a design, a dimensioning, a drive load and / or the position angle of the motor rotor of the emulated traction motor.Test system (10) according to Claim 1, wherein the motor module (4) has an electric traction motor for absorbing power in the drive train, having a sensor for detecting the position angle of the motor rotor of the traction motor.Test system (10) according to one of the preceding claims, wherein a circuit of the on-board power supply emulator module (6) and a circuit of the battery emulator module (3), in particular a circuit of the respective emulation control devices (62, 32), are integrated with one another.Test system (10) according to one of the preceding claims, further comprising a filter circuit (8) for frequency filtering, which is arranged between the battery emulator module (3) and the inverter test object (5) in the on-board power supply system.Test system (10) according to one of the preceding claims, further comprising an AC power sensor (43) for detecting polyphase AC power output by the inverter test object (5) to the motor module (4), wherein the substantially real-time capable interface (7) transmits a power signal which the AC power sensor (43) generates as a function of the detected AC power to the on-board power system emulator module (6).Test system (10) according to Claim 6, further comprising a pilot control module (63) for generating and outputting pilot control signals for the impedance behavior of the emulated on-board power supply system to the power electronics circuit (61) of the on-board power supply system emulator module (6), wherein the pilot control signals are generated as a function of the AC output power which is detected by the AC power sensor (43) and is output by the inverter test object (5) to the motor module (4).Test system (10) according to one of the preceding claims, further comprising an auxiliary unit emulator module (64) for generating and outputting control signals for an oscillation pattern of a DC auxiliary unit to the power electronics circuit (61) of the on-board power system emulator module (6), wherein the control signals are generated as a function of parameters stored in a model which represent a reaction of a DC auxiliary unit to harmonics in the on-board power system.Test system (10) according to one of the preceding claims, wherein the battery emulator module (3) and the on-board power system emulator module (6) are provided by a multilevel converter device clocked at high frequency.

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