Use Cases 
Comprehensively analyzing fuel cell drives using measurement technology
When people talk about hydrogen-powered vehicles, they usually mean a fuel cell drive. This generates the electricity required to drive the electric motor directly in the vehicle from the hydrogen tank. Although the chemical reaction occurs with just a few substances, certain conditions must be met for an ideal result. These include the temperature as well as the quality of the reaction components supplied. Comprehensive measurements – some of them requiring high-voltage safety – must be carried out to ensure that the fuel cell drive can be operated as efficiently and safely as possible.
The transition to electrified mobility is considered one of the main measures for more environmentally friendly transportation of people and goods. In most cases, the electric motor is powered by electrical energy provided stored in a battery. However, this concept reaches its limits in certain contexts. Therefore, there is an increasing shift to fuel cell-powered mobility.
Measurement task
Acquisition of many measured values on the fuel cell stack.
For an ideal supply of electricity to the vehicle, the energy from the chemical reaction must be optimally utilized in a wide variety of driving situations and under changing environmental conditions. In addition to the temperature of the hydrogen and the supplied air, humidity, pressure and flow rate also play an important role. Also, some of the measurements must be performed in a high-voltage safe manner due to the high system voltages of electric drives.
The fuel cell drive is a technically complex system with many components. In this example, the focus will be on the metrological investigation of the fuel cell system. In the hydrogen/anode pathway, the conditions of the hydrogen supply to the system are examined. This includes the pressure, the flow rate and, as a result, the quantity of liquid hydrogen over the period under consideration. This is measured using suitable sensors in the supply line from the tank to the circulation blower and at the dosing valve. The measured values are recorded with an AD measurement module and transmitted via CAN bus. The power consumption of the circulation fan is also measured using an LEM sensor package and another ECAT AD module. Thanks to its high cut-off frequency of up to 200 kilohertz, the LEM current transformer is also suitable for reliably detecting possible high-frequency interference in the vehicle electrical system – with a very high measurement accuracy. The ECAT AD measurement module provides the correspondingly high sampling frequency of up to 1 MHz per channel. IEPE accelerometers and an ECAT AD module for data acquisition are installed at this point to determine the mechanical loads caused by vibrations in the hydrogen supply line in real operation. Both measured values are transmitted via EtherCAT®.
In the air or cathode path, corresponding components such as the electric air compressor are usually operated with high-voltage voltage. To protect users and devices, the necessary measurements must be taken using HV-safe measurement technology. Ideal air conditions for the chemical reaction are essential, especially when it comes to the performance of the fuel cell. Therefore, the air pressure and humidity are measured with HV AD modules and analog pressure and humidity sensors, and the temperature of the air is measured with thermocouples (type K) and HV TH modules. The HV measurement modules, which are specially designed for use with high system voltages, provide the sensor supply voltages for the sensors – just like their standard variants – but also galvanically isolate both the supply voltage and the measurement signals. This means that standard sensors can be used safely in a high-voltage environment. For the power consumption of the electric air compressor, current and voltage are recorded directly with the HV Split Breakout Modules and transmitted via EtherCAT®.
The electrical power consumption in the cooling system is also measured in this way with additional HV Split Breakout Modules. As temperatures in the coolant must be acquired very precisely, temperature changes in the coolant are measured with HV safety at eight measurement points using PT1000 resistance sensors. The combination of high-voltage-safe and compact PT elements with fast response times and the HV PT measurement modules from CSM specially developed for PT sensors ensures high-precision temperature measurement under high-voltage conditions with an accuracy of approx. 0.3 Kelvin. To check the fluctuation of the coolant, additional measurement data from pressure sensors placed in the coolant is acquired with an HV AD module. An HV Breakout Module 1.2 is also used to measure current and voltage in the HV electrical path to evaluate the performance and efficiency of the drive in the further analysis.
To analyze the data, the measured values from the CAN and EtherCAT® measurement chains are bundled, time-synchronized and transmitted via XCP-Gateways to a measurement computer for analysis. The XCP-Gateways act as protocol converters that can be used to channel large data streams from many measurement modules onto a time basis. In this way, all relevant measurement data is available for measurement data acquisition in a single data stream. With software solutions from the Vector CSM E-Mobility Measurement System, the measured data can be mathematically evaluated, graphically displayed and checked with regard to the respective criteria. As customized software for CAN and EtherCAT® measurement modules from CSM, vMeasure can be used to directly perform various analyses, such as calculating efficiency and other relevant variables for evaluating performance. Overall, the comprehensive data acquisition of a wide range of physical variables offers the opportunity for versatile investigations, for example to identify correlations between electrical, thermal, chemical and digital ECU data.
vMeasure, developed by Vector Informatik, is an easy-to-use software tool for the acquisition and analysis of measurement data that can be used in combination with all CAN- and EtherCAT®-based CSM measurement modules. CSMconfig was integrated directly to ensure swift configuration.
Swift configuration of measurement chains: CSMconfig is the reliable configuration software for all CAN and EtherCAT® based measurement modules from CSM. The clearly arranged and easy-to-use user interface allows an easy setting of all measurement parameters. This helps speeding up the measurement setup considerably.