![]() ![]() The metal casing of the first set is typically pressed into a heat sink (or welded to the heat sink) for better thermal dissipation. The rectifier is divided in two sets of three diodes. Usually six diodes in a full-bridge configuration are used to rectify the output current. 2 shows the simplified schema of a vehicle generation system. The Lundell alternator is generally characterized by its form factor (a relatively large diameter compared to its length) which facilitates thermal dissipation.įig. In passenger cars the maximum alternator speed (typically 8000 RPM) is about two times more than that of the engine crankshaft (a pulley ratio of 1:2). The alternator is coupled to the combustion motor through a belt. So the choice of pole number is actually based on a compromise between the magnetic losses and alternator power requirements. Unfortunately the magnetic losses will also increase due to the higher electrical frequency. Increasing the number of poles reduces the inductance of the stator winding, and as a result, increases the short circuit current. High power alternators for some applications like buses, trucks or other special vehicles have higher pole numbers (between 14 and 18). The stator has often a single slot per pole and per phase (36 total slots). The number of rotor poles for passenger vehicles is generally fixed at 12 poles. 1 shows a dismantled Lundell alternator (Delcotron 22SI) and its main components. The stator is composed of a slotted laminated iron core and a three-phase overlapped winding, wye or delta connected. The excitation coil is surrounded by two solid iron pole pieces, or claw poles, and is fed via a pair of slip rings and two carbon brushes. It is often named “Lundell” alternator ( Fig. The conventional automotive generator has a claw pole rotor with a single excitation coil wound axially. Today, the great majority of electrical generator systems installed on combustion powered vehicles are based on a three-phase wound-field synchronous machine. Generating system with a Lundell alternator These include the use of reconfigurable windings and replacement of the diode rectifier by different electronic converters such as a synchronous rectifier or an interleaved PWM rectifier will be considered.Ģ. ![]() We also discuss various solutions to increase the output power of Lundell alternators without any geometry modification. First, we present the conventional automotive generating system, its performance and the limitation of modelling methods. ![]() In this context, this chapter focuses on the improvements of Lundell alternators that could represent the best solutions for the short term. Many alternatives are being considered to replace the Lundell alternator such as the salient pole machines, however they require large investments in manufacturing infrastructure. This is a major drawback for its use in modern vehicles requiring an increase in electrical power. However, the efficiency and output power of the Lundell alternators are limited. ![]() After more than 50 years, this system is still the most economic choice in today’s vehicles due to its low manufacturing cost. The availability of affordable power diodes in the beginning of 1960s paved the way for the widespread use of three-phase claw-pole alternators (or Lundell alternators) for the generation of electric power in motor vehicles. Until in the early 1960s, automobiles used a DC generator called dynamo. ![]()
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