Special solutions for railway, automotive and transport

""

Power for the fuel cell

In order to raise the fuel cell voltage to battery grid voltage, a highly efficient booster is required in the system. For this purpose, AUTRONIC has developed a customized DC/DC converter with an output power of 900 Watt. The customer is the innovative SIQENS company which uses the new special solution in its new product ECOPORT 800.

Potential industrial application fields for off-grid energy are measuring technology, construction or surveillance in remote regions and places where the access to the public or regular current supply is not guaranteed.

Since 2005 AUTRONIC has gathered experience in the development and production of power supplies for fuel cells. This new project included new requirements concerning development: among other things, an input current of up to 100 A and a high degree of efficiency of up to 96% at an output power of 450 W. This was achieved by the already mentioned polyphase design. In order to obtain a high degree of efficiency, the booster topology works without diodes but exclusively with synchronized MOSFETS. Due to the careful selection of the switching MOSFETS and the chokes, an efficiency degree of 97% could be achieved which exceeded the development target by 1 %.

For customers high efficiency is of highest significance because due to this, less cells are required for the same output power and consequently a lower air flow is necessary to cool the components. The fuel cell technology and the charging technology for batteries require high intelligence to obtain the best possible performance.

For this reason, the converter offers various features:

  • adjustable input current
  • adjustable maximum output voltage
  • measurement of input current and input voltage
  • measurement of the current supplied by the system

Input and output of the values is provided digitally to increase the accuracy and robustness of the entire system. The converters have an early error detection concerning undervoltage, overvoltage, overcurrent and over temperature so that possible faults in the entire system will be detected at once. The integrated error message when the converter goes into the voltage mode is used to operate the fuel cell exactly at the MPP (maximum power point) and to achieve a maximum of performance.

The converter is provided for an input voltage range of 7.0 V to 25.5 V and for a battery voltage of 24 V. The output voltage can be adjusted between 20 V and 32 V. The enable signal is provided to start the converter and to cut the fuel cell System from the power supply.