An inertial coupled marine power generator for small boats

This paper proposes a device to harvest energy from the vertical motion of small boats and yachts. The device comprises a sprung mass coupled to an electrical generator through a ball screw. The mathematical equations describing the dynamics of the system are derived. The equations are used to determine the optimum device parameters, namely its mass, spring constant, ball screw lead, within practical constraints. Simulation results are presented to determine the maximum power that can be generated and the optimum load resistance as a function of boat vibration frequency

Comparative studies on the interactions between human serum albumin, bovine serum albumin and cholesterol: ftir and fluorescence spectroscopy

The interaction of the human serum albumin (HSA), bovine serum albumin (BSA) with cholesterol has been investigated. The basic binding interaction was studied by FTIR and fluorescence spectroscopy. From spectral analysis cholesterol showed a strong ability to quench the intrinsic fluorescence of HSA and BSA through a static quenching mechanism. The binding constant (k) between HSA and cholesterol is estimated to be K=2.14 × 103 M-1 at 293 K while between BSA and cholesterol is estimated to be K=.1.12 × 103 M-1 at the same temperature. FTIR spectroscopy with Fourier self-deconvolution technique was used to determine the protein secondary structure and cholesterol binding mechanisms. The observed spectral changes indicate a higher percentage of H-bonding between cholesterol and -helix compared to the percentage of H-bonding to cholesterol and -sheets.This work is supported by the German Research Foundation DFG grant No. DR228/24-

An inertial coupled marine power generator for small boats

This paper proposes a device to harvest energy from the vertical motion of small boats and yachts. The device comprises a sprung mass coupled to an electrical generator through a ball screw. The mathematical equations describing the dynamics of the system are derived. The equations are used to determine the optimum device parameters, namely its mass, spring constant, ball screw lead, within practical constraints. Simulation results are presented to determine the maximum power that can be generated and the optimum load resistance as a function of boat vibration frequency

Microgrid power electronic converters: state of the art and future challenges

This paper presents a review of the state of the art of power electric converters used in microgrids. The paper focuses primarily on grid connected converters. Different topologies and control and modulation strategies for these specific converters are critically reviewed. Moreover, future challenges in respect of these converters are identified along with their potential solutions

Robust repetitive feedback control of a three-phase grid connected inverter

This paper discusses the design of a repetitive feedback controller for a grid-connected two-level three-phase voltagesource inverter connected between a DC source and the grid through an LCL filter. The controller incorporates a classical two loop feedback of the output current and the capacitor current in addition to a repetitive feedback loop. The results show that the proposed technique improves the steady state error and the total harmonic distortion of output current in presence of utility harmonics

Current control of utility-connected two-level and three-level PWM inverters

This paper discusses the design of a digital current controller for three-phase utility-connected 2-level and 3-level PWM inverters with output LCL filters in which the filter capacitors are connected to the dc link rails. The controller has a two-loop feedback structure, with an additional feedforward loop to compensate for utility voltage harmonic disturbance. A detailed analysis of the effect of the controller microprocessor time delay on the stability and transient response of the controller is presented. Analytical and simulation results are presented for both the 2-level and the 3-level inverter systems, demonstrating the effectiveness of the proposed controller in producing good quality current with low THD. The results confirm that using a 3-level inverter has the advantage of halving the current ripple in the filter’s main inductors, at the expense of extra inverter power devices and electronic hardware and software complexity. Experimental results for a 2-level inverter system are also presented

Energy storage systems for unmanned underwater vehicles

The power source of an underwater vehicle is the main component that determines its range of travel and the tasks that it can perform. Until recently, the choice of practical power sources for most applications has been limited to lead?acid and silver?zinc batteries are a well-established technology and are available at low cost. However, they have a low energy density (~25 Wh kg -1). Although silver?zinc batteries have a high energy density (~120 Wh kg -1), they are very expensive, costing 20 times the price of lead?acid. They also have a very short life of 40?1-- cycles compared with 1000 cycles for lead?acid [1].In recent years considerable research and development work has been done on advanced power sources for road electric and hybrid vehicles. This ongoing work is motivated by environmentally driven legislation aiming at reducing the harmful emissions of conventional internal combustion engine vehicles (e.g. [2, 41]).The power source should ideally have a high energy density, high power density (higher charge and discharge rates), low cost, long life, low maintenance, high efficiency and wide operating-temperature range. It should also be safe and recyclable. In addition to these requirements, which are similar to those for a road vehicle, there are additional considerations imposed by working in the underwater environment. Ideally, the power source should be non-gassing and, in the case of batteries, the electrolyte should be spill-proof. the operation of the power source should be independent of depth.This paper presents a review of the features of different types of batteries (primary and secondary) and fuel cells that have been used in autonomous underwater vehicles (AUVs), highlighting their merits and operational and engineering issues that need to be considered when using them. It also presents a survey of potentially promising alternative types of batteries and energy-storage systems including flywheel electromechanical batteries and supercapacitors

Finite element analysis of an axial-gap permanent magnet dc motor

Magnetostatic 2D finite element analysis is used to determine the flux distribution and electromagnetic torque of an axial gap permanent magnet brushed DC motor. The results are compared with experiments and analytical calculations