Abstract: A ballast (4) for providing power to a high intensity discharge lamp (8) includes a first sensor (32) and a control subsystem (16). The first sensor (32) generates a first signal indicative of a current level in the ballast (4). The control subsystem (16) computes a real time power level of the ballast (4) based at least upon the first signal, compares the computed real time power level to a specified power level, and modifies a frequency of operation of the ballast (4) in response to the comparison. The first sensor (32) can measure the current level at an output of the ballast (4). The ballast (4) can also include a second sensor (32) that generates a second signal indicative of a voltage output of the ballast (4). The control subsystem (16) can compute the real time power level of the ballast (4) based upon the second signal.

Abstract: A ballast includes a power supply subsystem, a power factor correction circuit, a control subsystem and a half bridge. In one embodiment, the power supply subsystem receives an input line voltage that is within a range of approximately 310-530 volts AC or other suitable ranges. Further, in one embodiment, the power supply subsystem provides a rectified DC output. The power factor correction circuit receives the rectified DC output. In one embodiment, the power factor correction circuit includes a boost converter and a buck converter that produce a selected stable bus voltage that is less than approximately 700 volts DC. The control subsystem outputs control signals based on a digital input. The half bridge receives the bus voltage and the output control signals. Additionally, the half bridge outputs a high frequency signal to a lamp. In one embodiment, the control subsystem includes a microcontroller and a ballast controller.

Abstract: A microprocessor controlled electronic ballast for lighting equipment is described wherein light level control is performed by varying the power provided to the light. Lighting power is adjusted by driving the lamp through a resonant circuit with a variable frequency power signal. The programmable microprocessor controls overall operation including preheating, ignition, and shutdown.