Denk, Fabian

Heering, Wolfgang

Heidinger, Michael

Kling, Rainer

Simon, Christoph

KITopen

KIT – Die Forschungsuniversität in der Helmholtz-GemeinschaftLight Technology Institute (LTI)Light, ECG and Plasma TechnologiesPatented, cost-effective current sharing controller integrated in an LED module Michael Heidinger*, Christoph Simon, Fabian Denk, Rainer Kling, Wolfgang HeeringState of the ArtNovel ApproachIntroductionDamping network:40dB / DecadeStability circterium Constant Current SourceMosfet Resistor gain:Averaging Circuit:All measured currents are averaged by all samples and time andfed back as a set value to the constant current sources. Thereby thecurrents are shared and no external mircocontroller needs to specify a limit.Startup Circuit:The circuit has two stable operating points, 0A and matchedcurrent. To reach the second operating point, the startup circuitis required.The startup circuit is temperature compensated as Q1 and Q2 are matched and have the same voltages. D1 produces a voltage offset which is translated by Rstartup to a current.The current pulls the averaging cirucit out of the 0A operatingpoint.Paralleling LEDsLEDs have differend forward voltages andneed to be balanced by a resistor. To achievea decent matching a high resistance isrequired. Therefore high losses occure at theresistors.Goal: Dissipate only energy if the LED current istoo high.Observation: MidPower LED are far more cost-effective and energy saving. (Up to 47% more Lumen per Watt) Task: Drive 144 MidPwr LEDs for 7200 lm.Series wiring:Series wiring is limited to 120V (SELV), thereforemax. 40 LEDs can be used.Low voltage approach:To reduce the voltage of the LED moduleparalleling is required.Constant current paralling controller for mid-power LEDs *michael.heidinger@kit.eduKIT – Die Forschungsuniversität in der Helmholtz-GemeinschaftLight Technology Institute (LTI)Light, ECG and Plasma TechnologiesConstant current paralling controller for mid-power LEDs Patented, cost-effective current sharing controller integrated in an LED module Michael Heidinger*, Christoph Simon, Fabian Denk, Rainer Kling, Wolfgang HeeringA short circuit of one or several LEDs does not compromise the modules functionality.The current is distributed equally. +- 3%The paralleling circuit can be directly implemented on theLEDs Aluminium PCB.Loss source LossesQuiescent losses 90 mW Equalizing losses 302 mW Sensing losses 345 mW Total 737 mW The losses of balancing parallel LEDs are only 1.5%.High Power: 120lm/WMid Power: 180lm/WParalleled MidPower LEDs: 177lm/W47.5%Integration on LED PCBShort Circuit BehaviorString current distributionVoltage Drop over MOSFETLoss SummationSystem EfficiencyPartnersResultsEfficiency gain*michael.heidinger@kit.edu

Constant current paralling controller for mid-power LEDs

https://publikationen.bibliothek.kit.edu/1000083220/14249964

Constant current paralling controller for mid-power LEDs

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