Roberto Retana

Analysis and Detection of Short Circuits in Fractional Horsepower Commutator Machines

An improved mathematical model for transient simulations of commutator machines is presented in this paper. This model can simulate and predict the line current harmonics during healthy and faulty operation conditions. A lumped parameter model that considers every single coil in the stator and rotor as a separate electrical and magnetic circuit is proposed. Self and mutual inductances of the coils are estimated by means of the winding function approach (WFA), accounting for the most relevant space harmonics in the machine air gap. The commutation is modeled by using the real brush width and assuming that the brush-commutator contact resistance is a function uniquely of their contact area, which depends on the armature position. Short circuits between adjacent commutator bars are investigated. It is shown that the model achieves good accuracy, reproducing fairly well the armature current ripple for healthy and faulty operation of the machine.

Optimization loops as method for analysis of boost recuperation systems

The reduction of CO2 emissions and fuel consumption is a continuous challenge towards the optimization of hybrid and electric vehicles. The approach in this paper is to use the claw pole alternator as boost-recuperation-machine (BRM), to realize a mild hybrid electrical vehicle. The investigated parameters are the control strategy and the pulley ratio of the BRM. These parameters are easily adjustable and influence the fuel consumption in the range of several ml/100km. For such minimal fuel savings an appropriate method is needed, which differs fundamentally to full hybrid optimization methods. To assess such small values the State-of-Charge (SOC) in the battery must be kept neutral during a driving cycle. Besides the SOC-neutral driving and a fast convergence behavior is essential. Consequently, several methods for optimization are considered, compared and improved. To improve the optimization progress optimization loops are used to analyze and optimize the system. Finally, the developed method is applied on a boost-recuperation-system (BRS) to minimize the fuel consumption.