{'fraction_non_alphanumeric': 0.034482758620689655, 'fraction_numerical': 0.002554278416347382, 'mean_word_length': 4.764705882352941, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Two-stage metal halide lamp electronic ballast with constant output-power control

A two-stage electronic ballast for metal halide (MH) lamps is presented in this paper. The front-stage is a two-output power factor correction AC-DC flyback converter. The post-stage is a half-bridge inverter, which is used to control lamp power and drives MH lamp with a low-frequency square waveform current to avoid acoustic resonance. In addition, the lamp power of steady state is maintained at a constant level by utilizing the current-sensing level-shifting technique. The proposed topology has the advantages, such as unity power factor, low THD, low cost, and constant output-power. Finally, a laboratory prototype of 35 W MH lamp electronic ballast is implemented to verify the feasibility.