Head lamp control method and apparatus, with PWM output regulation

摘要

A pulse width modulation control unit for energizing a vehicle head lamp. During daylight operation of a motor vehicle the control unit energizes the head lamp by pulse width modulating the battery output and coupling the modulating output across the head lamp. As battery voltage changes the pulse width modulation is adjusted to maintain power output of the head lamp. An over current condition in a switching transistor is monitored and used to de-activate the pulse width modulation of the head lamp energization.