| Until now, all vehicles driven by internal combustion engines have had two separate electrical machines: a dc motor used in the starting process of the vehicle, and a generator (a synchronous alternator) used to provide the battery and electrical loads with the necessary power at a dc voltage via a solid state rectifier.; The main goals of this dissertation is to propose an integral ac/dc drive to replace the two electrical machines of the existing system, and to establish the technical advantage, the economical feasibility of the new system and the design of a gearless, pulleyless and brushless arrangement for a starter/alternator combination.; The technical advantages are presented by weighing the proposed system against the existing one, and then by comparing the different types of electrical machines that can be considered for this application in order to select the most promising type. This turned out to be the induction machine.; The system consists of a squirrel cage induction machine and a power conditioner along with the necessary controllers designed to work in both motoring and generating modes, the machine has its rotor mounted on the periphery of the flywheel. The stator spans only a limited arch of the circumference. The power conditioner is capable of inverting, rectifying, depending on whether it is working as a motor or as a generator, and of providing excitation to the machine.; Presented in this work are the design criteria and the steps for complete design of the machine and complete analysis of the power conditioner. Also described is the control strategy adopted in order that the whole system works satisfactorily first in starting the engine and then changing into the generating mode in order to supply the loads with electrical energy. Moreover, the implementation of the control strategy using a microprocessor based controller is also explained. |
