Dynamic test environment for fuel cells From stack to vehicle energy system

Dynamic test environment for fuel cells From stack to vehicle energy system

Dynamic test environment for fuel cells From stack to vehicle energy system Fuel cell electric vehicles (FCEV) are characterized by a drive technology that achieves a higher range than electric vehicles with battery, for example. FCEVs use hydrogen as the fuel source. This is converted into electrical energy in the fuel cell. In addition to the fuel cell itself, fuel cell systems also include additional components for process control. When developing FCEVs, it is necessary to test the fuel cell stack and system as well as the interaction of all components of the vehicle energy system. Solutions for all development stages Scienlab offers customer-specific test environments for simulation of the dynamic processes that occur in real vehicles, also including the fuel cell process. The modularity of the test systems means that they can be adapted at any time to the current development stage of the fuel cell system. A rest vehicle simulation allows sub-components, sub-systems, and the overall system to be tested with real driving cycles under different climatic conditions. The operating software includes test programming, control and evaluation with intelligent analysis tools. Scienlab also implements a safety concept that is customized to meet customer requirements. Fuel cell electric vehicle In a FCEV, the electric energy for the drive system is provided by a fuel cell system. The process gases air and hydrogen used in a proton exchange membrane fuel cell must be conditioned as regards temperature, pressure and moisture content. In addition to the fuel cell stack, the system therefore also contains components for anode and cathode gas conditioning as well as for exhaust-gas treatment and cooling (also referred to overall as balance of plant = BoP). A battery is also required for intermediate storage of the braking energy. This is connected to the high-voltage bus via a DC/DC converter in order to isolate the battery voltage from the highly load-dependent output voltage of the fuel cell. The battery can also supply energy in the event of power peaks and thus level the load profile of the fuel cell within limits, but this involves increased cost, weight and installation space for the DC/DC converter and battery. It is therefore desirable for the fuel cell system to be as dynamic as possible in order to keep the dimensions of the DC/DC converter and battery as small as possible. Development of a fuel cell drive takes place in three stages: Pre-development, system development and system integration. Vehicle energy system with fuel cell Cooling/ventilation Safety system balance of plant Battery DC/DC converter Air Fuel cell Electrical energy Air O Drive system High-voltage bus Inverter Motor 2

Test environment for fuel cell systems Pre-development In the pre-development stage, the fuel cell system is developed together with all associated units (BoP). As part of this process, it is necessary to characterize the fuel cell stack with respect to its dynamic and static properties as well as its lifetime. Influencing variables and process control options (process gas conditioning, purging, cooling, etc.) are investigated and suitable control strategies designed. The components for anode and cathode gas conditioning, exhaust-gas treatment and cooling must be developed and matched to the fuel cell and the component interaction tested. A test bench is required for this purpose that initially makes available all the components required for operation of a fuel cell stack. The components are capable of simulating the dynamics of real driving situations. The test bench also offers a "rapid control prototyping" platform on which control strategies can be designed and tested. All relevant process parameters are measured and logged, whereby the user is supported by a test program and measurement data management function. The modular design allows individual test bench units to be replaced by the customer's own components. All of these functions are embedded in a safety system that manages the risks involved with the hydrogen in particular on different levels and thus ensures safe operation. Test environment for fuel cell stacks Applications Optimization of process control and development of control strategies Aging tests, also taking into account pollutant gases and environmental simulations Dynamic and static characterization of fuel cell stacks and auxiliary units in all typical vehicle operating states (benchmarking) Highlights of the test environment Provision of all auxiliary units with maximum dynamic response, also for process gas conditioning, to permit simulation of real driving dynamics (ABS/ESP/ASR) Rapid control prototyping platform for balance of plant Emulation of the high-voltage vehicle on-board electrical system by the Scienlab Dynamic DC-Emulator (DCE) Advanced test and control software Integration of customer's own auxiliary units possible Pre-development Cooling/ventilation Safety system balance of plant Air Fuel cell rapid control prototyping Air O Electrical energy Dynamic DC-Emulator 3

Highly-dynamic stack testing The Scienlab test bench is capable of simulating the dynamics of real driving situations. For this purpose, the process gases (air and hydrogen) are made available with corresponding dynamic conditioning without overshoot. This represents a great challenge for the high volumetric flow rates required for operation of a fuel cell stack with output powers up to 100 kw. The Scienlab test systems have a response time for regulating the volume flow rate and temperature of the process gases of less than one second over the entire adjustment range. The same applies to the volume flow rate of the coolant, which must also be adapted dynamically to avoid condensation in the fuel cells as a result of load changes. Technical data for stack test Anode gas volume flow rate Cathode gas volume flow rate Pressure (anode, cathode) up to 2,000 l/min up to 7,500 l/min 1... 3.5 bar Humidification 0 100 % Dynamic temperature response of process gases Dynamic volume flow rate response of process gases Dynamic volume flow rate response of coolant Temperature constancy of coolant Electric load with energy recovery -40 C +120 C < 1 s 0 % 90 % < 1 s 0 l/min 250 l/min < 1 s +/- 0.1 K 850 V / 600 A / 180 kw Measuring technology Impedance spectroscopy Cyclic voltammetry Single-cell voltage monitoring 4

Test environment for fuel cell systems System development In the system development stage, fuel cell systems are characterized and parameterized. Function, endurance and approval tests are performed under different climatic conditions. The controller stability as well as the protective and safety functions are verified. Development statuses must be released at the planned times and any returns examined. The test bench for system development simulates the vehicle environment for a fuel cell system. It provides hydrogen, process air, cooling and auxiliary voltage supplies and guarantees exhaust gas disposal. The total instantaneous powers of the inverter input and output of the DC/DC converter are represented dynamically at the electrical output of the fuel cell corresponding to the driving profile. The test bench allows measurement data recording for internal and external variables. The scope and resolution of this recording function can be configured for the respective test case on an event-controlled basis. Test bench automation can be programmed flexibly and thus facilitates complex testing tasks. A higher-level safety system that is independent of the system under test permits safe operation even at extreme operating points. Test environment for fuel cell systems Applications Characterization and parameterization of fuel cell systems, benchmarking Function, endurance and approval tests under different climatic conditions Verification of controller stability, protective and safety mechanisms Release of development statuses Returns analysis Highlights of the test environment Test bench automation Dynamic rest vehicle simulation/rest bus simulation Emulation of the high-voltage vehicle on-board electrical system by the Scienlab Dynamic DC-Emulator (DCE) Parameterizable measured data acquisition corresponding to task Test program and measurement data management Safe operation in the test bench environment also at extreme operating points System development Cooling/ventilation Safety system balance of plant Air Fuel cell rapid control prototyping Air O Electrical energy Dynamic DC-Emulator 5

System integration In the system integration stage, the fuel cell system is integrated in the vehicle environment step-by-step. As part of this process, network tests are carried out with other components in the high-voltage vehicle on-board electrical system. The goal is to release development statuses or test them as part of configuration management. In addition to the operating environment for the fuel cell system, the system integration test bench also includes power emulators that emulate parts of the highvoltage vehicle on-board electrical system as well as a dynamic rest bus simulation function. For example, it is possible to emulate the input power of the inverter with a DC-Emulator in order to investigate the interaction of the DC/DC converter with the battery and fuel cell system in the event of load changes. In this scenario it is also possible to replace the battery by an AC-Emulator so that the battery condition (state of charge, temperature, age, etc.) can be selected by software in order to accelerate testing. The higher-level safety mechanisms guarantee safe operation for this. Test environment for vehicle systems Applications Step-by-step integration of fuel cell systems in the vehicle environment Network tests with other HV components (DC/DC converter, inverter, battery, BMS, etc.) Release of development statuses Configuration management testing Returns analysis Highlights of the test environment Flexibly configurable test cases Virtualization of the vehicle environment by emulators (DC/DC converter, battery, electric machine, vehicle on-board electrical system, charger, power grid) Safe testing even at extreme operating points thanks to higher-level safety systems Efficiency through energy recovery Dynamic rest bus simulation in the HIL environment System integration Cooling/ventilation Safety system balance of plant Air Fuel cell Air O Electrical energy Dynamic DC-Emulator DC/DC converter High-voltage bus Dynamic DC-Emulator 6

What Scienlab has to offer Scienlab offers individual test environments that allow testing of tomorrow's fuel cell electric vehicles today. Numerous corporations, medium-sized companies and research institutes all over the world place their trust in the know-how of Scienlab for development and testing of their products. Test systems for fuel cells and more In addition to realization of test systems for fuel cells, Scienlab employees also work on many other test applications. In the Scienlab laboratory, test systems are produced for a range of industrial products as well as for automotive components used in electric drivetrains. Scienlab is committed to always exceeding the high quality requirements of our customers. Alongside turnkey test environments for fuel cell electric vehicles, Scienlab also develops test systems for energy storage devices, chargers and charging infrastructure, inverters, DC/DC converters and network configurations of several components. In the field of Common Rail technology, Scienlab offers test solutions for the entire development and production process of actuators and fuel injectors. As a development partner and engineering service provider, Scienlab also realizes customer-specific solutions. These include customized battery systems with battery management system, inverters, analog and digital measuring and circuit technology as well as control units in small production series for different automotive and industrial applications. Everything from one source from the idea through to on-site commissioning The employees at Scienlab are the guarantee for individual engineering services of the highest standard: all products are developed and produced at the Bochum location from hardware production and software development through to system acceptance. The company has other locations in Munich and China (Shenyang). Scienlab has a deep understanding of user needs. This is further developed in a continual dialog with customers and forms the basis for products that allow our customers to perform their tasks with maximum efficiency and reliability. The resultant high-end solutions provide our customers with a decisive competitive edge. Scienlab is a problem-solver for its customers and makes it possible to develop innovative technologies to market readiness more quickly. Scienlab is full of ideas, which are realized in new products by the Scienlab team premium solutions to ensure that our customers are always one step ahead. Scienlab works on a partnership basis and attaches high value to long-term business relationships with our customers and partners. Together, we realize successes and technological progress that are reflected in innovative products. The texts, photos, and illustrations contained within this document are protected by copyright laws. Their use, distribution, or duplication is only permitted in agreement with Scienlab electronic systems GmbH. Pictures reproduced by kind permission of ZBT Zentrum für BrennstoffzellenTechnik GmbH. 7

P-BZT-1E-914 Scienlab electronic systems GmbH Lise-Meitner-Allee 27 44801 Bochum Germany phone +49 234 41 75 78 0 fax+49 234 41 75 78 10 web www.scienlab.de mail info@scienlab.de