Patent ID: 7443142

Claim:
An automotive electrical system comprising: a DC bus; a voltage sensor configured to sense a voltage of the DC bus; a current sensor configured to sense a current of the DC bus; an alternator; an active rectifier coupling the alternator to the DC bus, the alternator comprising a plurality of FETs; and a microcontroller coupled to the voltage sensor, the current sensor, and the active rectifier, the microcontroller configured to control switching of the plurality of FETs without reference to a shaft position of the alternator by analyzing the voltage and current of the DC bus wherein the microcontroller switches the plurality of FETs to minimize ripple current on the DC bus by executing instructions corresponding to the method comprising: sensing a first instantaneous current on the DC bus to which the output of the rectifier is connected immediately prior to a switching event; sensing a second instantaneous current on the DC bus to which the output of the rectifier is connected immediately after the switching event; comparing the sensed first instantaneous current to the sensed second instantaneous current to determine whether to increase or decrease the phase of FET switching; decreasing the phase of FET switching if the second instantaneous current is greater than the first instantaneous current; and increasing the phase of FET switching if the second instantaneous current is less than the first instantaneous current.