Method and Circuit For Driving Light-Emitting Diodes From Three-Phase Power Source

摘要

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.

主权项

1. Light emitting diode (LED) drive circuitry, comprising:
a rectifier comprising three inputs adapted for connection to a three-phase power source to respectively receive three-phase currents from said three-phase power source; said rectifier comprising a plurality of diodes connected to rectify said three-phase currents to produce a DC voltage across two outputs of said rectifier; a plurality of LEDs connected in series across said two outputs of said rectifier, and driven by said DC voltage produced by said rectifier at said two outputs, the plurality of LEDs including a first set, comprising multiple LEDs connected in series, and a second set, comprising at least one LED, said first set and said second set being connected in series to a first of said two outputs of said rectifier; a first constant current source connected to a second of said two outputs of said rectifier and across said first set, said first constant current source including a first transistor having a control electrode; a second constant current source connected to said second of said two outputs of said rectifier and across said second set, said second constant current source including a second transistor having a control electrode; and a further transistor connected in series to said first transistor between said two outputs of said rectifier and in series to said second transistor between said two outputs of said rectifier, said further transistor being configured to turn off said first transistor while said second transistor is conducting.