Hydrogen vehcile based on a Danish produced PEM fuel cell - Part 2

In static mode, the PEM Fuel Cell Generator operates as an on-off battery, charge system, wheras in dynamic mode the system operates by charging the traction batteries in accordance with the vehicles drive pattern. An IRD Fuel cell stack (PEMFC70_100) and a humidifier was built for the, project's Part 2. The vehicle's fuel cell generator was reconfigured according to the new concept for dynamic operation (Figure 1-1), which involved removal of parts that had become obsolete, and integration of new parts, such as a humidifier for the Fuel Cell stack air supply, and the Fuel cell voltage monitoring system (CVMS), integrated with the IRD FC stack. The humidifier (Type IRD PEM-04-19-00_200) was developed for optimizing the power efficiency of the new Fuel Cell stack installed. A major charge made in the power generator cooling system, is the separation of the water cooling circuit from the air circuit. The DC/DC Step-up converter was modified to the controllabilty required for dynamic operation of the PEM Fuel Cell generator. The Safety and Control System was updated with respect to electrical interface for control of the DCIDC Step-up converter, and the Cell Voltage Measuring System, CVMS. The software of the Electronic Control Unit (ECU) is updated to match the new configuration and functionality of the PEM Fuel Cell generator. Infrastructure of the power generator and the vehicle was changed for adapting it to the new configuration. The vehicle's Hydrogen storage compartment has not been involved in the reconfiguration process. After reconfiguration of the FC Generator for dynamical operation, its safety- and functional performance were verified in two steps - with and without Hydrogen supply connected, operated via the Electronic Control Unit (ECU), to verify the safe operability of the generator With the Control og Safety System and its software, prior to starting dynamic Fuel cell generator testing to its full capacity. Test methods for the PEM Fuel Cell car, reconfigured for dynamic operation, are similar to what is specified for the vehicle with static operation of the fuel cell generator in Ref. 1., 'Slutrapport del I'. Tests were performed in the laboratory and on a closed road, on the IRD Fuel Cells company premises. The Operational Procedures for the PEM vehicle (Section 5) has been updated accordingly With the conversion from static to dynamic operational capability. Testing: Tests were performed in the laboratory, and on a closed road, at the IRD Fuel Cells company premises. Overall Dynamic Test: Performance characteristics of the FC power generator in terms of the Fuel Cell stack voltage, current and the vehicle motor current during a dynamic drive operation (for both acceleration and deceleration sequences) were recorded. The fuel cell responds dynamically on the changes in motor current by increasing its output during acceleration and decreasing it during breaking and deceleration. The fuel cell generator response time has been limited in order to avoid the influence of electronic noise, which would otherwise make the regulation system unstable. Additionally the energy used for accelerating the compressor is limited. Fuel Cell Stack during dynamic load: The FC Cell Voltage Monitoring System (CVMS), with detection of minimum voltage amongst all cells during driving operation, protests the Fuel Cell Generator against permanent damage. Any cell voltage below 0.2 V observed by the CVMS results in a temporary disconnection of the fuel cell stack from the load. The Fuel Cell Generator will be fully recovered during the disconnection if it is due to water accumulation. The CVMS is also an important tool in early detection of possible Hydrogen leakage from a cell in the FC stack. Overall Power Performance: The power needed for operating the balance of plant during driving has been measured by measuring the power needed for operating the compressor. The total power consumption for the remaining components is less than 25W, independent of the load. The compressor Power consumption is also nearly constant. It increases only 20% during acceleration, due to the limitation imposed on the generator response time. The electric efficiency of the fuel cell stack varies as function of the load from 58% at a stack voltage of 50V just charging the battery, down to 49% at 42V during acceleration. The overall efficiency of the fuel cell generator is at the same time nearly constant, 40% during charging of the battery and 38% during acceleration. The project has provided IRD new knowledge and 'hands on' experience with the integration of IRD's fuel cell stack in the vehicle, and the reconfiguration for dynamic operation. Testing of the vehicle with the dynamic operated fuel cell generator has enabled us to see how the system works under practical conditions. Dynamic operation provides higher system efficiency and reduced requirements for the traction battery capacity. Lifetime of the batteries is increased due to prevention or considerable reduction in deep charge/discharge cycles. The new knowledge gained will be utilized in the development of the next generation of automotive and combined heat and power (CHP) fuel cell generators, for which advantages of dynamic operation is enforced through increased fuel cell capacity