HIL Test Systems for the BMW Hydrogen 7

Orazio Ragonesi, MicroNova AG

"The prospect of generating regenerative hydrogen is a contribution towards sustaining individual mobility for the future."

- Orazio Ragonesi, MicroNova AG

The Challenge:

Developing engine simulators for the BMW Hydrogen 7, a new hybrid vehicle designed to combine the pleasure of driving a BMW with the benefits of practically emission-free mobility.

The Solution:

Using National Instruments software and hardware to design a complete HIL testing environment for engines.

Author(s):

Orazio Ragonesi - MicroNova AG
Franz Dengler - MicroNova AG
Wolfgang Schlüter - BMW Group, Munich

 

The BMW Hydrogen 7 is the world's first premium vehicle with a bi-fueled drive concept. It is currently under development and when complete it will offer a driving experience typical of BMW. The BMW Hydrogen 7 opens the way to mobility practically free of emissions, coupled with the driving experience of a premium car. For software development tasks, set up and safeguarding of the engine control units for the BMW model platform was adapted to the hydrogen requirements and the HIL delivery was improved through the use of industrialized processes. The availability of HIL system solutions first used with the Hydrogen 7 project was also used to improve the HIL supply for other BMW power train projects.

 

 

The First Hydrogen Serial Car

The BMW CleanEnergy hydrogen initiative aims to avoid carbon dioxide emissions by changing from carbon dioxide based fuel, such as gas and diesel, to hydrogen. The prospect of generating regenerative hydrogen is a contribution towards sustaining individual mobility for the future. The combination of a combustion engine and liquid hydrogen is superior to other concepts in terms of production costs but also customer values such as driving dynamics, reliability, and cruising range. Therefore, the BMW Hydrogen 7 is the first premium car with a hydrogen engine.

 

Hydrogen Engine for Sustainable Individual Mobility

With the concept of efficient dynamics for all engines, the BMW group is working to solve the fundamental conflict between higher driving performance and concurrent lower fuel consumption. A further development of this is the BMW CleanEnergy hydrogen initiative. Unlike finite fossil energy sources, hydrogen can be generated in unlimited amounts from renewable energy sources such as solar, water, wind, or biomass. BMW is focusing on the hydrogen powered combustion engine. The speed record of 300 km/h by the hydrogen powered BMW H2R demonstrated the technical potential of this engine concept. The combustion engine can convert energy with hydrogen or with gas and therefore serves as a bridge technology.

 

The BMW Hydrogen 7 has a bi-fueled 12 cylinder V engine that can be powered by hydrogen or by gas. This means that even with the still insufficient hydrogen infrastructure, this car provides the expected performance of a BMW for everyday use

 

The limited number of serial vehicles coincides with the limited number of filling stations for hydrogen. Due to the small amounts of hydrogen needed, hydrogen is converted from conventional energy sources. However, implementing hydrogen engines in serial vehicles creates the demand for a hydrogen supply infrastructure, which in turn creates the demand for hydrogen powered cars. Here, the BMW CleanEnergy initiative is a driving force towards using new energy sources.

 

BMW Hydrogen 7

The BMW Hydrogen 7 corresponds with the current BMW 7. This concept is based on tested and proven technology. The variable suction valve hub and the adjustable inlet or outlet cam shafts on both engine blocks allow unthrottled valvetronic load control. When running on gas the engine uses the gasoline direct injection and when running on hydrogen the car uses an external carburetor. In the hydrogen operating mode the engine has an engine power of 191 kW and a maximum torque of 390 Nm. The advantage of the bi-fueled model is that it can bridge the gaps which currently exist in the supply chain of hydrogen filling stations.

 

Hydrogen, which is highly volatile at normal temperatures, is stored in liquid form in a tank at -250° Celsius in order to achieve a sufficient energy density and cruising range. The hydrogen tank is constructed as a cryo container and its super insulation corresponds to a 17 meter thick styrofoam wall. On its way to the injection valves the hydrogen becomes gaseous in a warming process. A 168 liter tank can store 8 kg of liquid hydrogen that has the energy capacity of 30 liters of gasoline. A hydrogen driven vehicle has a cruising range of 200 kilometers and an additional 500 kilometers can be covered when the car is operated with gas.

 

The tank system has a separate coolant branch. The operating pressure of the tank during drive operations is maintained by the evaporation of hydrogen through heat input. The CleanEnergy tank controller controls this process. This central controller of security-relevant functions also monitors the fueling procedure and the gas concentration, as well as critical tank parameters and reactions to limit values. Further functions of the controller include the management of the on-board supply system, driver information on the system status, and communication with the service center. The controller with its comprehensive redundancy features complies with the SIL3 security level (Software Integrity Level, similar to IEC Norm 61508), which is the highest requirement class in the automobile industry.

 

HIL as a Standard Tool in the BMW Development Process

The development of the controller, the functions, and the application of the BMW Hydrogen 7 have run through the tried and tested BMW serial development process. From the initial concept to the highly dynamic test stand operation, all phases apply model-based development methods. In the context of HIL applications, the continuity of the deployed simulation models is ensured. Using a powerful variant handling the Incremental modeling ensures that the more than 60 HIL test systems efficiently achieve the necessary system accuracy required for the applications. After the successful roll-out of the HIL applications and establishing the procedure, the industrialization of the HIL with the aim of reducing costs and of avoiding being dependant on individual manufacturers is a further focus.

 

HIL Applications

The main focus of HIL usage is still the startup and safeguarding of controllers, program states, and data states. The majority of these applications run as component tests on HIL systems with the focus on one individual controller. Controller (hardware) tests focus on error logging and behavior under electrical loads. However, software development requires a "slim" developing environment in which new controller software can be tested quickly and safely in all operating points. The basic application on the system level is the test of the communication in the controller group; first within a partial system and then in the lab vehicle with all controllers.

 

Even if only base controller functions are tested with these HIL applications, the advancement of controller functions in vehicles requires a higher system accuracy and larger simulation spectrum for these HIL applications. An HIL operation only makes sense if the simulation models correspond with the complex process models of the controllers. Cross-controller functionality on the other hand enforces either combination test stands or complex behavior simulations of further tasks concerning vehicles.

 

Apart from the HIL base applications, which account primarily for the cost effectiveness of HIL systems, the strategic core business of HIL are applications in the functions development and the functional startup of controllers because they enable the basic applications. The developer of new controller functions, new controller hardware, communication technology, sensor technology, and actuator technology uses the HIL tool when development starts.

 

When all information is available, HIL test stands with approved system extensions are used for the automated safety tests that take place later in the development process. In basic applications, the use of HIL is to some extent mandatory, whereas the use of HIL for development and startup is motivated by the shorter development period and fewer engine and vehicle tests. The current development area of HIL applications is the monitoring of application data and the pre-application of functions while increasing the model accuracy.

 

Incremental Modeling Based on the BMW Model Platform

HIL system accuracy necessary for certain HIL applications conflicts with the aim of providing an efficient and fast HIL development environment. In the periodic advancement of controller systems, the individual development steps of controller hardware and software contain integration, startup, and calibration of the functions, succeeded by the fine-tuning. For this first phase a robust startup environment must be readily available. When all the configuration data is provided, HIL can display systems with high accuracy at any time without any problems. However, in early phases accessing consistent configuration parameters in real-time for the model configuration involves quite an effort. But after the first measurements are available, the model accuracy, which can be displayed with a manageable input of resources, increases quickly.

 

The model configuration based on the results of an offline CAE simulation actually leads to higher model accuracy for sub-models. This means the models used on HIL systems can also be used for application tasks. The tradeoff between accuracy in the early phases and the allocation of supplies is still apparent. Therefore, the basic approach of incremental modeling is to only display the system accuracy that is required for the current application. Subsequently, a uniform model structure is used to continuously improve the model configuration in a step function as soon as new data is available in order to meet the accuracy requirements of the application.

 

Efficient Variant Handling for Cross-Project Synergies

A prerequisite for incremental modeling is an efficient variant handling that enables the fast update of simulation models on a number of different HIL test systems. This variant handling together with the configurable model structure are a prerequisite for the use of the uniform model platform for all engine projects. This is one of the main reasons why Simulink was used as the basis for the BMW model platform.

 

The simple integration of a new concept for a hydrogen powered engine demonstrates the efficiency of this concept with which synergies between the various engine projects are developed. Every cross-project use of development methods, control models, and simulation models requires a certain amount of extra effort for the realization of the individual project. The decision whether to integrate a new project in the uniform platform depends on the effort needed for the special development, which then must be sustained in all other projects, rather than the synergy effect between the projects. Therefore the HIL systems for the CleanEnergy controller were kept autonomous, whereas the associated engine controller systems were integrated in the platform. A system allocation for a single project can use the deduced development status of a reference project as a basis. This procedure, which has no impact on the project environment, does not need further adjustment and can therefore be implemented without coordination with the methods allocation. The progress that is achieved in other projects after the development process has started, must be followed up separately. In contrast real synergy does not occur until the integration is complete.

 

Industrialization of HIL Allocation

Although HIL systems have been an inherent part in the BMW development process for many years, it is always a challenge to keep the benefits of the application for serial development in line with the potential of new methods. In pilot projects with various development stages and individual subjects the HIL applications are developed further. The roll out of the methods application aims at establishing the methods in order to make the progress of these development cores effective across projects in the entire development process.

 

The next step entails the determination of the procedures that includes the binding specification of the methods application, and details of the prerequisite for the system allocation with the necessary preparations. In this stage controlling the complexity and basic quality management strategies are the focus.

 

With industrialization, BMW is controlling the methods and processes of HIL allocation so that HIL applications can be implemented area-wide without being dependant on individual system suppliers. Controlling the system includes the integration competence for the entire system and the capability to assign single projects to different suppliers according to the project. This is only possible if the procedures and interfaces are determined in such a way that the different projects can be processed by different suppliers. Of course this can only happen without having to abandon the cross-project synergies and without having to waste too much time for the use of joint project sections.

 

This is not a fundamental contradiction to choosing development partners who provide comprehensive HIL systems in a domain and, if necessary, also operate and provide them to the end-user. Such an assignment is not dominated by the high one-off costs of a supplier change. In fact, the assignment occurs with regard to project-specific technical advantages of the various system solutions and especially with respect to costs in a competitive bidding situation. The continuous usage in the development process requires a constant adjustment of HIL test systems to new projects and the safeguarding of the continuity to the existing systems pool.

 

HIL Test Systems for the CleanEnergy Controller

The specific controllers for the Hydrogen 7 are the engine controllers, which are modified serial controllers for the 12 cylinder Otto motor, and the CleanEnergy controller that is based on the architecture of an engine controller adopted from aircraft construction. The software, classified SIL 3 in compliance with IEC61508, was designed in MATLAB/Simulink. The autocode was generated by an Atena software development environment, which uses TargetLink as the code generator. Internally the controller works entirely on a time basis. The application software does not have interrupt controlled modules, in contrast to engine controllers that calculate extensive software tasks synchronously to the crankshaft position. Therefore software-in-the-loop (SIL) tests can be carried out directly on the module level for all functions.

 

Due to its special status, the CleanEnergy controller is unparalleled to other BMW components with regards to the hardware and the associated simulation models as well as the implemented test scripts. The advantages of a close integration into the development project clearly offsets possible synergies with other projects. Therefore the associated HIL test systems were established following the example of the aviation project at the development partner of the controllers.

 

The CleanEnergy controller is designed as a 2 channel system, from the processors to the actuator control. Depending on the error status of a processor, the channel activation, executed redundantly, decides which activation signal is output or whether the activation is stopped. The communication with other systems occurs over five CAN connections and further serial bus terminals. The power amplifiers of the various valves and other actuators have detailed diagnosis.

 

For development tasks and safeguarding tasks with this controller, several HIL test systems were constructed. The main challenge was integrating the different loads while simultaneously feeding in electrical error signals on all channels. In order to test the controller functions with the extreme values of the electrical properties of the actuating elements, the dummy load was established with different variants of the resistive and inductive load. Atena system solutions using a dSPACE real-time system were implemented for feeding in electrical error signals partially with high currents, and also for the dummy loads and the signal processing. Atena also carried out the development and the model adjustment as well as the construction and operation of the HIL systems.

 

HIL Test Systems for Motor Control

From the start, the concept of the HIL test system for motor control was an integral part of the BMW HIL test facility. The hydrogen-specific tasks concerning the engine were integrated into the BMW model platform which provided an HIL development base, tried and tested in serial development, for the Hydrogen 7 up to the hardware interfaces. Project-specific development efforts had to be undertaken in order to meet the additional demands that the Hydrogen 7 made on the HIL test system. Due to the uniform control of all HIL projects in the engine development, these were used to optimize the HIL allocation for all BMW engine projects.

 

The motor control of the Hydrogen 7 consists of a pair of two master-slave controllers that respectively control one bank of the V-12 motor. For HIL operation of the motor controls, a connection of the vehicle controllers is necessary for the key-immobilizer system as well as the central gateway controller. BMW developed the specific functions of the motor control concerning the hydrogen operation. In the development and safeguard of controller functions at BMW, the HIL process is integrated in the standard procedure in such a way that even in vehicle tests abroad the developers can test and operate modified functions on HIL test systems and can analyze effects found onsite directly with the HIL. The systems are not used in mobile operations.

 

In order to transport the simulator in the trunk of a normal car it is nevertheless necessary that the system is fitted into a 19 inch rack with a maximum of 8 - 9 rack units. Therefore the compact structure was a central demand on this HIL test system. For some time BMW has provided portable systems based on the dSPACE compact simulator and the MidSize-HIL simulator for conventional motors with 8 cylinders and one controller. However, the expansion to 12 cylinders and additional signals for hydrogen operation has pushed the previous configuration to its limit. Processor boards and signal boards that are developed purely for HIL applications require a lot of space. The use of several controllers leads to very complex controller connector cables because the signals flow through external terminals. This has prompted BMW to announce a bid invitation in order to initiate a new concept for compact HIL test systems aimed at lowering the costs for the procurement and operation of HIL tests systems.

 

Hydrogen 7 Specific Demands on HIL Tests Systems

The HIL test system must acquire all interfaces of the involved controllers via input channels and output channels. Because the controller function and not the hardware test is in the focus, no real loads such as injection valves or ignition plugs are installed. Instead, the controller outputs are charged with electrical dummy loads. Only the two throttles can be run in an alternative test with a real load or with an analogical model. Each of the two motor controllers of the Hydrogen 7 comprises all typical signals of a modern 6 cylinder motor with direct injection. They have been expanded by several hydrogen specific signals. The signal generation for 4 adjustable camshafts and 6 knock sensors, as well as the necessity to accurately display the continuous lambda probe in the entire temperature range, highlights the complexity of the HIL system. This applies also for the communication via two CAN interfaces and one BSD interface as well as for the integration of the Simulink based BMW model platform.

 

A HIL structure in a new platform using standard software and hardware components was an alternative to the realization based on dSPACE. Measurement and automation applications use components with internationally standardized interfaces. Based on applications in numerous fields of industry, highly integrated plug-in boards are available for fast signal preprocessing, signal generation, and signal acquisition. Signal densities and signal frequencies tested in aviation and telecommunications technology enable a compact structure of HIL systems. Interfaces for electrical components, which are available from the process control, guarantee that the technology can be implemented for vehicle control of future motors and hybrid engines. Unlike the analog acquisition and output of angle of rotation oriented signals with specific processing circuits, the FPGA (Field Programmable Gate Array) technology allows for a largely free configuration of required interfaces. Therefore the higher quantities, which greatly exceed the HIL systems, together with the technological potential of standard components from the measurement and automation field are a more cost-effective option of HIL test systems.

 

Using a new hardware platform and system software platform for HIL systems requires from the software the integration of the BMW model platform and also an interface for the connection of the test automation software. Because the BMW model platform and the automation software have already been implemented on numerous test systems, the structure incorporates the configuration of the individual test systems. The model platform, which is entirely implemented in Simulink, comprises the component models and the control models as well as the scaling between physical and electrical interface values. These signals can be converted unchanged to the electrically transmitted signal on test systems of different manufacturers, whereas the protocol conversion of the bus communication is specifically integrated in the HIL system software. It must be created in parallel. The same applies to the interfaces of the HIL user software. Because this determines how user friendly a HIL system is, a uniform "Look and Feel" of the handling is important. The BMW engine development exclusively uses the TraceTronic test automation software ECU-Test. The activation of a new HIL platform requires a one-off adjustment of the integration interface. Because all HIL test systems use the BMW model platform and as the test automation only accesses these values, test scripts can be exchanged between the test systems of different HIL suppliers without any restrictions. This is independent of any standardization efforts.

 

HIL Requirements Arising from the Reintegration into the Project Environment

Even though the supplier bears the additional time and effort involved in creating a pilot system and the delivery price reflects the one-off charge for the user, implementing a new system platform is only economically sensible if it can be used for all engine projects without extra engineering costs and in a short period of time. The additional requirements resulting from the multi-project environment do not need to be implemented in the single simulator directly. However the conversion elements must be completely available in the system platform. Therefore the respective HIL supplier must independently prepare test system solutions, which are unrelated to the actual project, for conceivable technical developments in the application environment. Like an engineering partner in the individual project, the HIL supplier uses the available standard components. Moreover, he must start the product development of missing components to avoid extensive engineering efforts for individual solutions later.

 

In order to apply the new generation of HIL simulators promptly on all BMW model Otto motors and diesel engines, dummy loads and signal acquisition solutions for the injection valve control for the various Piezo and magnetic injection systems are essential. A simulation for motors with the BMW High Precision Injection requires, not only for lean burn engines, the crank angle synchronic acquisition of the injection times and the measurement of the activation voltages for the various injection impulses of a combustion cycle. In this case fast signal acquisition and signal preprocessing is imperative. If the signal acquisition and signal preprocessing can be configured, it can be used, for example, to acquire signals in a bus system via an oscilloscope device depending on the model status.

 

The Hydrogen 7 motor was developed in only one vehicle configuration, whereas all other BMW motors are implemented in up to 7 models. Large parts of an HIL test system are determined by the engine controllers with their large numbers of sensor interfaces and actuator interfaces and the necessary dummy loads. In order to test the engine controllers on a HIL system with different vehicle environments, the vehicle specific controllers that are relevant for the engine, such as immobilizer, gateway, and instrument are connected to the HIL via a standardized interface. The sets of vehicle controllers are mounted on a rack and can be easily changed. The same concept determines the implementation of load units on gearbox and combination HIL systems for gearbox controllers. After using the uniform BMW model platform for all HIL applications, this concept further fosters the industrialization of HIL supply and operation. Accessing BMW specific functionality via uniform interfaces is independent of the vendor of the HIL test system. Modules with BMW specific components can be produced and configured centrally and cost effectively, and can be tested on reference systems before being implemented on the various HIL systems.

 

With the diversity of the car models, the diversity of the simulation of the bus communication increases. With networked functions and an increased number of controllers connected to the HIL test systems, the rest-bus simulations are gaining in importance. To some extent they are becoming the most complex tasks of the HIL allocation. An efficient and robust application of HIL systems requires a tool supported generation and update of the rest-bus simulation based on the communication description files (for example, dbc- format for CAN). During the entire development procedure the message catalogs are subject to continuous changes. These changes refer to a large number of messages, which are expected by individual controllers in the HIL system, and that are not dynamically connected to the plant models. In this case it is important that no complex reintegration into the HIL model environment is required when the rest-bus simulation is updated. If the communication basis and the diversity of the messages outnumber the dynamic message contents, BMW implements outsourced rest-bus simulation systems on some HIL test systems. The configuration process of these systems implemented partly for CAN and nearly throughout for FlexRay is adjusted right down to the board network communication of the data base. In these systems an additional CAN connection couples the dynamic messages to the simulation models. As outsourcing the CAN rest-bus simulation does not make sense if the percentage of messages that are coupled dynamically to the model is high, an efficient handling of the rest-bus simulation is imperative on all HIL platforms.

 

Specific communication interfaces, as well as the BSD bus and several LIN buses, which are very common in the automotive industry, are used in the local environment of the actuation controllers. Examples are the SPI protocol, which is used as a fast sensor bus, from the embedded area, or special formats in the area of immobilizer communication. The requirements on the configuration options of LIN buses and CAN buses are similar. The proprietary buses also require a slight adjustment to new communication protocols. If interfaces can be mapped completely via a software configuration, for example, FPGA technology, without specific hardware changes, efficient mapping is simplified.

 

Some applications require a multi-processor structure of the HIL test system due to the system complexity and high bandwidth of the involved components. Therefore all HIL platforms must have the option to couple several computation nodes in a standardized and efficient way.

 

Apart from the HIL applications in which only the engine controllers, as the test units, are connected to the HIL test system, HIL technologies and models are now increasingly being implemented for model supported motor or component test stands. The sub-task, the whole combustion engine, or the actuation elements of a valve train adjustment are operated with real energy fluxes and the associated vehicle operation is simulated realistically for the controller. Applications are reliability tests with realistic environment profiles and detailed applications of the controller functions for components that are difficult to make a model for. For the development of the electrical energy management in various vehicle board networks an HIL test system was established where the controllers and the vehicle batteries were integrated as real parts and were charged with real current profiles. These types of HIL applications often require the parallel implementation of HIL tasks and a fast measurement and control technology.

 

Realization of HIL Test Systems with NovaSim Simulators

The HIL systems for the Hydrogen 7 motor control are based on the NovaSim HIL simulators from NI Gold Alliance Partner MicroNova. MicroNova is a manufacturer and integrator of HIL test systems with experience as an engineering partner for CleanEnergy functions development and software development.

 

The essential structure of these simulators is based on the National Instruments hardware platform on which a real-time computer is connected to various IO boards via a PXI bus. The simulation models are coupled with the hardware via National Instruments LabVIEW software which also enables the simulator operation. The fundamental idea behind the simulator group is to use as many standard components, which are freely available on the market, as possible and to integrate these components in several stages. The PXI bus, which is compatible to the compact PCI bus, is the hardware platform. Several manufacturers offer for this bus hundreds of components that are constantly being enhanced for worldwide use in the measurement and automation technology. Therefore it was no problem to employ more powerful real-time computers for the second generation of hydrogen HILs without modifying the existing simulation software. Reflective-memory boards based on a compact PCI-bus, for example, were used in networked HIL projects for the computer coupling in multi-processor systems. However, newer simulators use the more cost-effective coupling via the Gigabit-Ethernet interface.

 

All hardware standard components are combined by MicroNova with automotive-specific additional components to a standard HIL simulator. The task is not only concerned with project specific engineering. In fact, it is more important to initiate product development for hardware components that are needed as an essential standard part in HIL applications for engine and chassis frame tests, but which cannot be employed in other areas. Examples are signal conditioning boards for the output of lambda probe signals or systems for electrical error simulation which are adjusted to the requirements of engine testing.

 

The software follows the same integration approach: Basis is the LabVIEW software packet with LabVIEW Real-Time, LabVIEW FPGA, and Simulation Interface Toolkit. These software tools which are commonly used, for example, in measurement technology enables the generation of real-time capable code and the respective user interface from Simulink models. MicroNova as system partner extends these components by specific block sets for the interfaces to automotive-specific signals. During the communication of standard vehicle buses such as CAN, LIN, or FlexRay with a HIL activation via specialized hardware boards these block sets contain a Simulink integration and the automated generation of the rest bus simulation. The Python interface for the test automation allows the simple access to all tasks concerning the HIL test system parts.

 

The reconfigurable FPGA hardware can be assigned functionality via graphical programming. The acquisition of motor specific-signals such as ignition and injection activation and the associated generation of crankshaft signals, camshaft signals, and knock signals are based on this technology. The blocks can be integrated directly into the Simulink models, whereas the project-specific adjustment is configured, for example, by specifying the detector wheel profile. The proprietary buses, such as BSD or SPI, are also mapped with block sets onto FPGA. Without the hardware being modified, the HIL system can map new functionality and thus can be adapted to future requirements. This flexibility of the reconfigurable hardware is the basis for a sustainable development of the HIL test systems. However an efficient use is only possible with block sets.

 

The use of reconfigurable FPGA hardware demonstrates that within the interaction of hardware, system software, HIL specific block sets, and project specific system configuration, the interfaces must be interlocked in such a way that the application requirements are met at the best position in the chain. Only then do the advantages of the use of standard components in contrast to proprietary system solutions from one supplier become apparent. Because the standard hardware and software plays an important role, the relevance of the support by the engineering partner National Instruments is evident. Despite an open PXI real-time architecture these standard hardware components are preferential. The continuity and comprehensiveness of the hardware and software components, and the advancement of the HIL-specific extra tasks on product level were the precondition for BMW to use these HIL systems in the engine development.

 

 

System Structure

For the development of the Hydrogen 7 engine control two HIL systems were initially established. After the successful introduction and intensive usage of the systems both for manual and automated tests two further systems were procured for the Hydrogen 7 development process. Figure 10 displays the structure of the system.

 

The power supply for battery simulation is located under the main level with the real-time computer and the signal conditioning. The real-time computer is a PXI system with a 2 GHz controller. With two motor-HIL boards, one CAN board, and an analog-out board the following signal interfaces are available:

  • 3 x 96 = 288 digital inputs or outputs: These can also be used to generate and to acquire pulse-width-modulated (PWM) signals and special signals with angular synchronism (for example, camshaft, injection). Specific serial interfaces such as the BSD or SPI bus are also integrated into the simulator without additional hardware developments.
  • 24 analog inputs, 56 analog outputs
  • 4 CAN interfaces

 

Although the application stipulates a small container size, the high density of the core components facilitates the integration of the wiring between the IO channels and the various controllers in the simulator. Just like larger HIL test systems the project-specific external wiring is constrained to a controller-specific 1:1 connection which displays the various pin allocations of the controller connectors. In order to identify the individual HIL components better, the connection cables for the IO boards and signal conditioning are not installed. As 1:1 connections these standard cables are a component of the project-independent internal wiring of the simulator. The internal signal distribution is located on the top simulator level behind the terminal panel and can be accessed even during the simulation when the cover is open.

 

Conclusion and Perspectives

The HIL application for functions development and safeguard of the Hydrogen 7 motor control was integrated completely in the existing development processes via the BMW HIL model platform. With process specifications and integration competence BMW managed to implement the specific project requirements to use the developed technologies for other engine projects via an industrialization of the HIL allocation.

 

Based on the HIL simulators used for Hydrogen 7 a universal HIL was established for all current BMW engine controllers. Along with these 10 compact systems a combination HIL test system is in use for the controller design for the electrical energy on-board supply system: The possibility to alternatively supply batteries and power electronics with real electric currents exemplifies the merging of HIL, measurement technology, and model supported test stand technology not only in the hybrid area.

 

House of Technology Conference: Hardware-in-the-Loop Simulation; Munich, 27.-28.2.2007

 

Literature

BMW AG: Eine neue Ära der Mobilität beginnt: Der BMW Hydrogen 7, München, 2006

Atena Engineering GmbH: BMW Wasserstoffprojekt, München, 2005

Schlüter, W.: Rollout integrierter Hardware-in-the-Loop Anwendungen, Konferenz: Simulation und Test in der Funktions- und Softwareentwicklung für die Automobilindustrie, Haus der Technik, Expert Verlag, Berlin, 2005,

Schlüter, W., Kvasnicka, P., Kämpf, B.: Model Database for Complex Simulink Models, Model-Based Design Conference, München, 2005

Engelke, M.: HiL gestützter Test von Motorsteuerungssoftware, 3. dSPACEAnwenderkonferenz, Stuttgart, 2002

MATLAB® is a registered trademark of The MathWorks, Inc. Other product and company names listed are trademarks and trade names of their respective companies.

 

Author Information:

Orazio Ragonesi
MicroNova AG
Unterfelding 17
Vierkirchen
Germany
Tel: 49 8139 9300 0
info@micronova.de

Figure 10: Compact HIL Simulator The terminal panel for the controller with the display elements and the signal distribution behind is on the top level.