Current Compensator for LED Driver With a Long Cable Connecting to the Light Source

It is sometimes unavoidable to place light sources and drivers far apart in large-scale LED lighting installation, where a long cable is used to connect the light source to the LED driver. LED drivers typically deliver pulse width-modulated pulses. The long cable inductance will delay the rate of rise of the current pulses and will also cause negative off-state voltage across the light source. Apart from reducing luminous output, such phenomenon also causes an impact on the life expectancy of the light source. A simple passive current compensator, which is connected between the driver and the light source to mitigate the distortion of the current pulses caused by the cable inductance, is presented. The concept is based on recycling the energy stored in the cable after the end of a current pulse to drive the light source synchronously with the driver at the beginning of the next current pulse, so as to modify the rise time of the current pulses. The topological states and operations of the compensator will be discussed. Simplified design procedure for the compensator will be given. A prototype for a 12 V LED driver to drive LED strips of rated current 4.5 A has been built and evaluated. Experimental results are compared with theoretical predictions.