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The use of alternating current machines of a simple construction with the squirrel cage rotor or the soft iron salient pole rotor as a car generator allows to increase a reliability of a generator and the maximum rotor rotation frequency as well in comparison with synchronous machines. The main feature of a car generator operation is a wide range of a rotation frequency change (five or six times). The use of alternating current machines aforementioned with the capacitor excitation is impossible, because it requires a capacitance value change in a wide range. In the paper presented the rotor excitation by passing current impulses through the stator winding over necessary periods of time is considered. The possibility of such an excitation is confirmed by the experiment. The single-phase generator with external rotor excitation is analysed on the basis of a digital model.

This generator is a new simplified design version of an alternator with DC stator excitation that was published by the authors in the SAE 2003 and SAE 2004 World Congresses. [7, 8] In automotive applications, this type of electrical machine may be useful for regular cars, hybrid and fuel cell electrical vehicles with an electrical power source system of 12 VDC, 24, and higher. Brushless car alternators with DC stator excitation have less rotor inertia because the excitation windings are located in the stator. Smaller rotor inertia eliminates drive belt slippage. This generator is more reliable in view of the absence of contact rings and graphite brushes in a rotor circuit, which exist in a standard claw-pole alternator [9]. The laminated salient pole rotor of the alternator is very simple in construction and has low cost of production. The two-phase alternator is simpler than the three-phase, as it has only two output windings instead of three.