Patent ID: 8212498

Claim:
A dimming ballast for operating at least one fluorescent lamp, the ballast comprising: an input rectifier operative to receive an AC input and to produce an initial DC output; a DC-DC converter operatively coupled to the input rectifier to receive the initial DC output and to provide a second DC output; a frequency-controlled self-oscillating inverter operatively coupled to DC-DC converter to convert the second DC output to produce an AC signal to power at least one fluorescent lamp; and an inverter control system operatively coupled with the inverter to control the inverter operating frequency, the inverter control system including: a first regulator operative to selectively vary the inverter operating frequency to adjust an output of the inverter based at least partially on a current setpoint value and a sensed lamp current value, and a second regulator operative to selectively vary the inverter operating frequency to adjust the output of the inverter based at least partially on a voltage setpoint value and a sensed AC bus node voltage value.