A permanent magnet alternator with increased power capability for hybrid electric vehicle applications

• PMSG with uncontrolled rectifier has limited power and speed range.
• An auxiliary winding sharing the same slots with the main one is proposed.
• Auxiliary winding is able to regulate generator output voltage.
• Wider speed range and increased power capability is achieved.

In this study, a new permanent magnet alternator is proposed in an effort to increase its power capability. The new alternator relies on an auxiliary winding sharing the same slots with the main alternator winding. The main alternator winding is connected to a 12 Volt DC bus through an uncontrolled rectifier. The auxiliary winding, which is called control winding throughout the study, is connected to a 300 Volt DC bus through a DC/AC inverter which enables full control over the winding current. Both main and auxiliary windings have fractional slot concentrated type coils in order to reduce mutual coupling among them. With the proposed structure, it is possible to extend the constant torque region to higher speed, thus enabling greater power output from the machine. Furthermore, the proposed method enables to obtain better voltage regulation by flux strengthening at low speed region where normally it would not be possible due to low back EMF.