Control Electronic Unit Research Articles

Electrochemical Sensor for Power Control of a Micro Fuel Cell

Micro fuel cells can be used for autonomous energy systems are used for surveillance, wireless communication nodes and other power needs where there is no access to grid electricity. For small power levels (e.g. 10 W) a battery or supercapacitor pack is often used. For long runtimes there is, however, a need for a large battery. The idea of this autonomous system is to reduce the battery/supercap package and instead use a photovoltaic during the day to charge up the batteries. The fuel cell contributes in the event of bad weather conditions when the photovoltaic is unable to deliver enough energy for several days. The energy system comprises a battery package for storage of electrical energy, a photovoltaic module which delivers electricity to the battery pack, a fuel cell for backup delivery of electricity, and a power control electronics unit which transfers the power to the load. The simplified fuel cell system consists of a hydrogen storage tank (pressurized hydrogen or metal hydride), a pressure regulation valve, a control valve, and a fuel cell stack. Thanks to that the battery pack can handle load variations the fuel cell system can be adapted to run at a constant gas flow level. Thereby, the control valve can be reduced to an on-off valve, which means that simplified the fuel cell system can compete with the cost for batteries. This work will analyse how the voltage from an external fuel cell (short circuited over a resitor and fed by the hydrogen exhaust) can be used to control the power draw of the stack. The sensitivity to hydrogen flow variation, start-up and shut-down procedures will be investigated.

Three-Beam Triangulating Sensor

The new high precision triangulating sensor for measuring distance and/or inclination angle with high temperature stability for a wide range of technical and technological applications is proposed. The corresponding measurement algorithm is considered and hardware allowing its implementation is developed. The preferable embodiment of three beam triangulating sensor comprises three laser radiation sources, CCD- array based image sensor including optical system, and control electronic unit.

Development of a compact laser-based single photon ionization time-of-flight mass spectrometer

We have developed a compact, laser-based, single photon ionization time-of-flight mass spectrometer (SPI-TOF-MS) for on-line monitoring of trace organic species. To obtain the mass spectrum, we use a nearly fragmentation-free SPI technique with 10.5 eV (118 nm) vacuum ultraviolet laser pulses generated by frequency tripling of the third harmonic of an Nd:YAG laser. The instrument can be operated in a linear TOF-MS mode or a reflectron TOF-MS mode in the coaxial design. We designed ion optics to optimize detection sensitivity and mass resolution. For data acquisition, the instrument is controlled using LabVIEW control software. The total power requirement for the vacuum unit, control electronics unit, ion optics, and detection system is approximately 100 W. We achieve a detection limit of parts per billion by volume (ppbv) for on-line trace analysis of several organic compounds. A mass resolution of 800 at about 100 amu is obtained for reflectron TOF-MS mode in a 0.35 m long instrument. The application of on-line monitoring of diesel engine exhaust was demonstrated.

Active vibration control of large optical space structures

The paper describes techniques for designing and implementing active damping systems for large optical support structures. Each step in the design process is illustrated with results from the Advanced Composites with Embedded Sensors and Actuators (ACESA) vibration control system. The system is installed on a space based laser structural simulator at the Air Force Research Laboratory's Advanced Space Structure Research Experiments facility. The ACESA system consists of three large tubular active members; embedded bad zirconate-titanate (PZTs) wafers in each strut, which allows control of deformation axially and in two bending planes; 400 V drive electronics for each active member; and a nine-channel, digitally programmable, analogue control electronics unit. Design begins with the determination of the critical modes through a gain factor analysis. Actuators are located through modal strain energy analysis. Using piezostructural analysis methods, sensing and actuation functions are included in the open- and closed-loop dynamic simulations. The simulation includes local strain feedthrough effects through a static correction. Damping is applied to all modes in the frequency range up to 100 Hz, with fundamental modes achieving 20% damping, two orders of magnitude greater than the intrinsic damping level. The actuator PZTs used for active damping were also experimentally shunted with resistive elements in an attempt to introduce passive damping, although the effect was barely measurable. This demonstrates that active damping gives three orders of magnitude better performance than a passive resistive shunt in a controlled comparison.