PLC Based Test Platform for Wind Turbine Gearbox

PLC Based Test Platform for Wind Turbine Gearbox

Abstarct:
Wind turbine gearbox is one of the most important and most expensive components of wind turbine. Once installed, it is difficult to repair. Therefore, it needs effective experiments during its design and production to meet the strict quality requirements. The test platform adopts Closure Design, which enables it to experiment two gearbox products at the same time.And thanks to the closed-loop design, the experiments are energy conservation. It's able to learn the running condition and operating parameters in real time. It can also intelligently control each system of the entire test platform, which including lubrication system, loading system, frequency converter, motor and other equipments. Besides, alarming when a problem occurs in the test platform is one function of the test platform.

Author: Zou Xinyu
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Fundamental Aspects of Near-Field Coupling Small Antennas for Wireless Power Transfer

Fundamental Aspects of Near-Field Coupling Small Antennas for Wireless Power Transfer

Abstract:
A physical limitation on the power transfer efficiency between two electrically small antennas in the near-field range is presented. By using a Z-parameter which describes the interaction between two antennas for spherical modes in connection with antenna parameters, the maximum power transfer efficiency and the optimum load impedance are shown as functions of the distance between two antennas, the radiation efficiency and the input impedance of the isolated antenna. The theory is verified by a simulation with a small helical antenna, which generates and modes, simultaneously.

Author:Jaechun Lee; Sangwook Nam;
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Dead-Time Elimination for Voltage Source Inverters

Dead-Time Elimination for Voltage Source Inverters

Abstract: A novel dead-time elimination method is presented in this paper for voltage source inverters. This method is based on decomposing of a generic phase-leg into two basic switching cells, which are configured with a controllable switch in series with
an uncontrollable diode. Therefore, dead-time is not needed. In comparison to using expensive current sensors, this method precisely determines the load current direction by detecting which anti-parallel diode conducts in a phase-leg. A low-cost diode-conduction detector is developed to measure the operating state of the anti-parallel diode. In comparison with complicated compensators, this method features simple logic and flexible implementation. This method significantly reduces the output distortion and regains the output RMS value. The principle of the proposed deadtime elimination method is described in detail. Simulation and experimental
results are given to demonstrate the validity and features of this new method.
Index Terms—Dead-time, gate drive, harmonic, phase-leg,
pulsewidth modulation (PWM) control.

Author: Lihua Chen and Fang Zheng Peng,
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