Electronic ballast having current waveform control within the half wave

A method of providing power to a light source, said method comprising:

• receiving a reference waveform signal indicative of a reference waveform from a waveform generator at a controller of a ballast;
• receiving a current signal indicative of a current through the light source at the controller;
• generating an output level signal indicative of an output level at the controller wherein the output level is a function of the received reference waveform signal and the received current signal and wherein the controller provides the output level signal at least twice within each period of the reference waveform;
• controlling power from an amplifier of the ballast to the light source as a function of the received output level signal;
• and wherein the amplifier is responsive to the output level signal to vary the power to the light source at least twice within each period of the reference waveform.

A ballast controller for providing an output level signal to an amplifier, said amplifier providing varying power to a light source as a function of the output level signal, said controller comprising:

• a supervisory processor for:
• receiving input from a user;
• receiving information indicative of an operating state of the light source;
• providing an operating parameter as a function of the operating state of the light source;
• and
• providing a reference waveform selection to a waveform generator as a function of the operating state of the light source, wherein the supervisory processor provides a first reference waveform selection to the waveform generator during a first operating state of the light source and a second reference waveform selection to the waveform generator during a second operating state of the light source, wherein said first reference waveform selection is different from said second reference waveform selection;
• and
• a gate level controller for:
• receiving the operating parameter from the supervisory processor;
• receiving a reference waveform signal from the waveform generator, wherein the reference waveform signal is indicative of a selected one of a plurality of reference waveforms corresponding to the provided reference waveform selection;
• receiving a current signal from a current sensor;
• and
• providing the output level to the amplifier as a function of the operating parameter, the reference waveform signal, and the current signal, wherein the gate level controller adjusts the output level signal at least twice within a period of the selected reference waveform.