Andre Charette

Analysis and design of a dual series resonant converter for utility interface

The use of a dual series resonant converter with phase-shifted operation for photovoltaic utility interface is presented. The analysis, sequence of operation and detailed design for a 5 kW system are presented. The inverter operates at a fixed frequency above the resonant frequency in order to reduce the switching losses in the devices. A general purpose Simulation program AT0SEC5 has been used to predict the performance of the converter and experimental results are given confirming the validity of the simulation results.

A quasi-passive modulation circuit improving the current waveform of conventional rectifiers

This paper proposes a new auxiliary modulation circuit to be retrofitted to an existing conventional AC/DC converter to improve line current waveform. The auxiliary circuit modulates the rectifiers DC side current at triple line-frequency and injects a calculated amount of third harmonic current back into its AC side. This circuit takes advantage of DC ripple voltage to generate the modulation current. It consists of mainly passive components and can be easily retrofitted to existing rectifiers. Theoretical analysis, digital simulation results and experimental verification on a 12.5 kW prototype have been presented in this paper.

Modeling and simulation of saturated induction motors

Induction motors play an important role in constant and adjustable speed drives. This paper contributes to the development of a realistic model for an induction machine taking into account the saturation and nonlinearity to compute the energy efficiency of the machine. The authors concentrate on the steady-state analysis of a saturated induction machine and present a methodology for the evaluation of the parameters of a saturated induction machine. The validation of the machine model is presented under steady-state conditions. This work provides a good starting point for the evaluation of steady-state performance of asynchronous machines under saturated and unsaturated operating conditions.

Mathematical Simulation of a Horizontal Flue Ring Furnace

A mathematical model is developed in which the horizontal flue ring furnace is treated as a continuous counterflow heat exchanger. The model integrates the equations of heat transfer between flue gas and solids along the entire length of the furnace, and the heat conduction equations within the solids (bricks, coke and anode). Infiltration and volatiles are treated by appropriate sub-models. Simulation runs are made which succeed in reproducing the operating conditions of the Arvida ring furnaces.

Fluidity Evolution of an Al-10%B4C Metal Matrix Composite

Aluminum boron carbide particulate reinforced composites are advanced materials which have superior mechanical properties, and especially have the capability to capture neutrons. The liquid mixing process is one of the methods to produce economically and effectively the metal matrix composites. However, it was found that the fluidity of the composites was instable during liquid holding and casting. To examine the fluidity evolution over the time, the melt of an Al-10%B4C composite was hold at a constant temperature for a long period, and the fluidity was evaluated by means of a vacuum fluidity test. The microstructure of the fluidity test samples was examined by optical and electron microscopes. It is found that the interfacial reaction products between B4C and Al-matrix play an important role for the deterioration of the composite fluidity.

The effect of stringent boundary conditions on the solution of a transient heat conduction problem

A notation system is proposed for the writing of the finite difference equations related to a conduction heat transfer problem in a composite medium with variable thermal properties. An example is worked out with Euler explicit, Euler implicit and Crank-Nicolson methods. Special care is taken of the conductivity expression and an analysis shows the importance of using mean conductivity values around the nodes especially when stringent Dirichlet boundary conditions are imposed.

Fluid Flow Investigation of Die Cast Tensile Test Bars

The fluid flow of an A356 semi-solid aluminum alloy filling a die consisting of four tensile test bars was investigated. Numerical simulations were carried out by implementing a mathematical model in a finite element software. Additional simulations were also obtained with a physical model in which tomato paste was used as the analogue fluid for the semi-solid aluminum. The modeling results were complemented by a series of experiments where tensile test bars were produced from semi-solid aluminum with a high pressure die casting press. The correspondence observed with the two modeling approaches and the casting experiments is discussed along with the effect the die geometry had on the flow patterns.