Modelling of multi-megawatt wind turbines for EMI and EMS investigations by a topological approach
Todays installed multi-megawatt wind turbines (WT) form highly diverse system due to very complex control devices. Thus, special attention has to be paid to the electromagnetic compatibility (EMC) of the wind turbine. This contribution deals with different electromagnetic interference (EMI) and susceptibility (EMS) effects within the wind turbine. A well-known susceptibility problem of constructions and buildings with large vertical dimensions is the threat situation due to lightning phenomena. On the one hand, the high amplitude of the lightning current effects destructions of infrastructure directly. On the other hand, the transient electromagnetic fields caused by this lightning current could lead to disturbances as well as destructions of electronic devices inside the wind turbine. Furthermore, common-mode currents ¡cm on the power lines between the generator and the frequency converter will cause EMI effects during the normal operation mode. These I cms lead to radiated emissions to the WT's environment as well as to transient disturbing fields inside the WT, which might interfere with the control unit (CU) and the condition monitoring system (CMS). These issues will be investigated in this contribution. Therefore, the electromagnetic topology (EMT) will be applied to the wind turbine. The EMT delivers useful information in order to increase the WT's susceptibility and ensure a high degree of availability.
EM Interferences between Power Converters and FM Radio Services on Vehicles of Security Authorities
This paper deals with the investigation of EM interferences between the FM radio services and a power converter installed on a special purpose vehicle of the fire department. While sporadic interference signals cannot be observed reliably with conventional EMC measurements, real time spectrum measurements are used for the identification of the interference source as well as the coupling path. The investigation finally point out, that a power converter is responsible for the EM interferences radiated by an additional onboard power system. Since the interferences cover a frequency range up to 80 MHz, they are received by the 4 m band antenna and thus disturb the FM radio service due to front door coupling. Furthermore, other radio devices near the command vehicle (e.g. a handheld radio set) will be also disturbed.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.