Sensorless Current Control of Large-Scale LED Lighting Systems based on SIMO LED Drivers

Most of the state-of-the-art LED drivers employed in lighting applications adopt current control strategies that rely on current sensing resistors. In multi-string LED lighting systems, commonly based on the single inductor multiple output (SIMO) topology, a current sensing resistor is typically inserted in each string, allowing to precisely control the current flowing through each string. This current control approach presents critical drawbacks: 1) the overall energy conversion efficiency is seriously affected by the fairly high number of current sensing resistors; 2) the system complexity is enhanced, as each LED string requires a current control loop; 3) the lifetime of both LEDs and drivers suffers an important depreciation due to the additional power losses incurred by the current sensing resistors. To overcome such drawbacks, this paper proposes a sensorless current control strategy suitable for LED drivers operated at continuous conduction mode (CCM), feeding multi-string LED lighting systems, which obviates the requirement of individual string current control. The proposed control strategy is implemented and validated on a fault-tolerant SIMO LED driver.