Multiple LEDs connected in series are driven by DC voltage that is provided by a diode rectifier, the diode rectifier being connected to a three-phase power source and converting the three-phase currents from the three-phase power source into the DC voltage that is used to drive the light emitting diodes. In order to reduce ripple in the DC voltage, the series-connected light emitting diodes can be divided into a first set and a second set, and a first constant current source is provided that drives the first set, and a second constant current source is provided that drives the second set. The first and second constant current sources are both connected across the outputs of the rectifier circuit, and operate to drive the respective sets of light emitting diodes in alternation. The capability for dimming can be provided, as well as back-up single phase operation.