An Improved Digital Control System for LED Grow Lights Used in Indoor Farming

A new digital control strategy is presented for a bridgeless single-stage multi-output AC/DC converter previously proposed as an LED grow light. The proposed control system can regulate the output current flowing through each individual LED string, perform power factor correction at the AC side, and provide zero-voltage-switching characteristics for all power semiconductors. Un-like the previous control strategy, the new method reduces conduction losses associated with transformer windings and power semiconductors by adaptively varying the DC bus voltage. Furthermore, the new control system can result in superior transient response. Experimental results of a 600 W prototype for supplying five LED strings are presented to verify the feasibility and performance of the proposed control system.