Reduction of harmonic distortion for LED loads
First Claim
1. A solid state light engine adapted to receive an AC input having an input voltage, the solid state light engine comprising:
- a plurality of light emitting diodes (LEDs) arranged in a network adapted to receive a load current based on the input voltage;
wherein the solid state engine is substantially and continuously dimmable without use of a DC power source wherein the frequency of the input voltage is at or between 100 Hz and 400 Hz; and
said network is arranged so that said current exhibits less than 30% total harmonic distortion in response to the input voltage having a substantially sinusoidal waveform.
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Accused Products
Abstract
Apparatus and associated methods reduce harmonic distortion of a excitation current by diverting the excitation current substantially away from a number of LEDs arranged in a series circuit until the current or its associated periodic excitation voltage reaches a predetermined threshold level, and ceasing the current diversion while the excitation current or voltage is substantially above the predetermined threshold level. In an illustrative embodiment, a rectifier may receive an AC (e.g., sinusoidal) voltage and deliver unidirectional current to a string of series-connected LEDs. An effective turn-on threshold voltage of the diode string may be reduced by diverting current around at least one of the diodes in the string while the AC voltage is below a predetermined level. In various examples, selective current diversion within the LED string may extend the input current conduction angle and thereby substantially reduce harmonic distortion for AC LED lighting systems.
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Citations
1 Claim
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1. A solid state light engine adapted to receive an AC input having an input voltage, the solid state light engine comprising:
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a plurality of light emitting diodes (LEDs) arranged in a network adapted to receive a load current based on the input voltage; wherein the solid state engine is substantially and continuously dimmable without use of a DC power source wherein the frequency of the input voltage is at or between 100 Hz and 400 Hz; and
said network is arranged so that said current exhibits less than 30% total harmonic distortion in response to the input voltage having a substantially sinusoidal waveform.
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Specification