Maxime R. Dubois

Basic Operation Principles and Electrical Conversion Systems of Wind Turbines

Abstract This paper gives an overview of electrical conversion systems for wind turbines. First, the basics of wind energy conversion with wind turbines are reviewed and requirements with respect to the electric system are considered. Next, the three classical conversion systems are described with their strengths and weaknesses: constant speed, variable speed with doubly-fed induction generator and variable speed with direct-drive generator. The applied power electronic converters are shortly addressed. Finally alternative generator systems and trends are discussed. There is a clear trend towards variable speed systems. Doubly-fed induction generator systems are increasingly equipped with grid fault ride through capabilities. For direct-drive turbines, the radial flux permanent-magnet synchronous generator is cheaper and more efficient than the electrically excited synchronous generator. It is expected that the voltage level of generators will increase up to values in the order of 5 kV.

Design and simulation of a fast charging station for PHEV/EV batteries

The importance given to the market integration of PHEV (Plug-in-Hybrid Electric Vehicle) and EV resulted in an increase in the interest for the fast charging technology of such car batteries. The paper reviews work recently conducted in this area and proposes a fast charging station using a flywheel energy storage and a supercapacitor as energy storage devices. Design issues and simulation results for a typical Level III charger are presented.

Power & energy ratings optimization in a fast-charging station for PHEV batteries

The design and simulation of a fast-charging station in steady-state for PHEV batteries has been proposed, which uses the electrical grid as well as two stationary energy storage devices as energy sources to recharge the PHEV battery. The two energy storage devices comprising the fast-charging station are a supercapacitor and a flywheel energy storage. The current paper justifies the selected power and energy ratings of the respective charging station resources in order to charge the PHEV battery with a maximum capacity of 15 kWh from 20% to 95% of its state-of-charge in a maximum duration of 15 minutes. After the charging stage, the storage devices are replenished in a maximum duration of 7.5 minutes. The methodology, results and its application are presented.

Integration of PHEVs and EVs: Experience from Canada

Plug-in hybrid vehicles (PHEVs) and Plug-in Electric Vehicles (PEV) are promoted in many jurisdictions worldwide as a way of reducing reliance on fossil fuels and reducing green house gases. In Canada, most utilities have initiatives in this area, with the aim to assess the impact on their electric grid of the wide scale deployment of these vehicles. There is also a significant interest on the part of international car manufacturers to supply vehicles to the local market, and on the part of equipment manufacturers to develop specialized components for this market. This paper summarizes the Canadian initiatives undertaken by utilities, in collaboration with car manufacturers, and by governments and government laboratories, and other stakeholders.

Energy management & scheduling in a fast charging station for PHEV batteries

The current paper focuses on the energy management in a fast charging station for PHEV batteries; that uses in addition to the grid a flywheel energy storage and a supercapacitor; with main objective to minimize the duration of the battery charging process and the time required to recharge the storage devices afterward. The designed station is capable to recharge PHEV batteries with capacities lower or equal to 15 kWh from a minimum of 20% to a maximum of 95% of the battery state-of-charge in a maximum duration of 15 minutes. After a battery has been charged, a waiting period (during which no cars are allowed at the charging station) of a maximum duration of 7.5 minutes is required. During this period, the storage devices are being recharged to their maximum. A scenario displaying the charging process of two different PHEV batteries is presented with the simulation results.

Losses in an optimized 8-pole radial AMB for Long Term Flywheel Energy Storage

In this paper, we will study the effect of losses (non including losses in the power electronic) of an optimized eight pole radial AMB on the discharge time of a no-load Long Term Flywheel Energy Storage (LTFES). Load capacity is the main parameter of an Active Magnetic Bearings (AMB) design. This parameter has to take into account the external disturbance force which may be constant, synchronous with the rotor angular velocity or completely general. To relatively simplify this study, we restricted the effect of external disturbance to a constant unbalance force only. The latter plays a high part on the size of bearing system. Before optimizing the AMB design, we have built and validated an Excel theoretical model with 2-D Finite Element Method (FEM). Several optimizations have been made in order to seek the minimum of both copper and iron losses we could obtain for a given load capacity. Then, evolution of losses functions of angular velocity speed of rotor has been drawn. Flywheel discharge time has been computed to pass from 9000 rpm to 4500 rpm and evolution of this time versus mass of AMB has been shown for different values of unbalance forces.

Clawpole Transverse Flux Machines with amorphous stator cores

The use of an hybrid stator, made of a combination of Fe-Si laminations and soft magnetic materials (SMC), has been recently proposed to reduce the iron losses occurring in a clawpole transverse flux machine (CTFM). In this paper, we show that a very low-loss magnetic material, the amorphous material, can be easily used as a substitution to the Fe-Si laminations to reduce the losses further. The stator iron losses in a CTFM with amorphous cores are compared to those occurring in a CTFM with Fe-Si cores by experimental tests and finite element simulations. It is found that the use of amorphous cores could increase the machine efficiency and speed range.

A simple insulated thermometric method for the experimental determination of iron losses

In this paper, we present a simple, versatile and cost-effective method for the experimental determination of the no-load iron losses in a PM machine. The proposed technique also enables obtaining the iron loss distribution in the machine. The latter is based on temperature rise measurements on specific locations of an electrical machine where thermal exchanges are minimized. The method principles are described as well as its implementation in a test bench. The method is used to measure the iron losses occurring in the stator of a Clawpole transverse flux machine with hybrid stator with accurate results. The insulated thermometric method is finally used to compare the iron loss reduction offered by the use of two different stator core materials.

A new design method for the clawpole transverse flux machine. Application to the machine no-load flux optimization. Part I: Accurate magnetic model with error compensation

This paper addresses the difficulty of modeling and optimizing transverse flux machines (TFMs). 3D flux line patterns, complex leakage paths and saturation of the magnetic material significantly add to the complexity of building accurate magnetic models to optimize TFMs. Therefore, common TFMs design approaches usually rely on time-consuming finite element analyses, guided by the designers knowledge. In this paper, a new design method is presented and applied to maximize the no-load flux of a Clawpole TFM. An error compensation mechanism combined to an analytical reluctance model is proposed as a solution to overcome inherent inaccuracies of TFM analytical models. It is shown how finite-element derived factors applied to selected reluctances of an analytical model can compensate for the model errors and validate the optimal solution found in a TFM design process, with a limited number of finite element simulations.

A new design method for the clawpole transverse flux machine. Application to the machine no-load flux optimization. Part II: Optimization aspects

This paper addresses the difficulty of modeling and optimizing transverse flux machines (TFMs). 3D flux line patterns, complex leakage paths and saturation of the magnetic material significantly add to the complexity of building accurate magnetic models to optimize TFMs. In this paper, a new design method is presented and applied to maximize the no-load flux of a Clawpole TFM. An error compensation mechanism combined to an analytical reluctance model is proposed as a solution to overcome inherent inaccuracies of TFM analytical models in a design process. As a natural complement to a previous communication focused the model and the error compensation mechanism, this paper investigates the use of this design method in an optimization context.