Leading current or lagging current of an alternator is supplied by a simple structure including short-circuit switch elements. The short-circuit switch elements are connected across output terminals of the alternator three-phase armature windings, and are turned on and off at fixed timings to supply a suitable amount of the leading current to armature windings regardless of the rotational speed. Thus, the leading current can be supplied without phase-leading-capacitors so that the apparatus can be made compact, lightweight and powerful. Even if any of the short-circuit switch elements can not turn off, the battery discharge can be prevented.
An electric machine selectively operates as a generator mode or a motor mode. The electric machine includes a stator core, a multi-phase armature winding, a field coil, a moving core having a plurality of salient poles so as to move relative to the stator core to cross the magnetic field. Field current is supplied to the field coil differently according to operation mode. A portion of the armature winding is short-circuited to form an additional magnetic field that has a phase different from the magnetic field of the field coil. Therefore, the rotary core moves relative to the stator core when the operation mode is in the motor mode.
A low cost, board level, inductor-based charge pump is provided to generate a sufficiently high voltage to drive a power MOSFET 307 having a rotor coil 311 attached on its source side in an automotive alternator voltage regulator. A first BJT transistor 303 of the charge pump receives a clock signal at its base from an application specific integrated circuit (ASIC) 302. The clock signal continuously turns transistor 303 on and off, forcing a current to flow through an inductor 301 connected to a voltage supply terminal. A second BJT transistor 308 receives a gate control signal at its base from the ASIC 302 for turning the second transistor 308 on and off to enable the circuit. In operation when the first transistor 303 is turned off, a slowly decreasing current flows from the inductor 301 to an output node. With the base of the second transistor 308 low to enable the system, the second transistor 308 is turned off and the current flows from the output node through a capacitor 309 to ground. The current charges the capacitor 309 to a higher voltage level than the alternator system voltage Vcc. The voltage across the capacitor 309 is sufficiently high to drive the power MOSFET 307 in an automotive alternator voltage regulator.
A power generation controller for an AC generator detects the state of a battery and an electric load to control the output of the AC generator. A current detector detects a current to be used by an electric load on the vehicle. The controller includes a field current control section, a field current monitor section, and an output control section. The field current control section controls a field current of the AC generator. The field current monitor section monitors a field current duty value which is a controlled state of the field current of the AC generator. The output control section corrects the output of the AC generator according to the field current duty value, monitored by the field current monitor section, and/or the load current value, detected by the current detector.
