Abstract:The characteristics of harmonic emission of LED are studied in this paper. The internal structure model of typical LED is established, and its harmonic emission characteristics are simulated, to revealing the harmonic emission mechanism of LED. This paper proposes the concept of harmonic fingerprint, which can represent the harmonic emission characteristics of harmonic source. Demonstration of harmonic fingerprint characteristics by studying the response of passive components to harmonic voltage. In this paper, a test platform is built and the test plan is made to test the harmonic emission characteristics of 8 types of LEDs (with 4 different powers) from 4 brands, the working condition of the LEDs includes single use, series use and parallel use. Based on the test results, harmonic fingerprints of the LEDs are studied. The test results show that 8 LEDs have different harmonic fingerprints, to prove that every equipment has its own special harmonic fingerprint, the equipment with the similar electrical structure has the similar harmonic fingerprints. Generally, LEDs have similar electrical structure, the measured harmonic fingerprints also show similar distribution characteristics. It lays a foundation for obtaining the harmonic emission characteristics of the equipment by analyzing the electrical structure of the equipment with the harmonic fingerprint as the carrier.