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This paper presents an electronic ballast topology for HID lamps using differential connection of DC/DC converters. The integration of power factor correction, lamp power control and inverter stages results in a single-stage electronic ballast that supplies the lamp with a low frequency symmetrical square voltage waveform, which avoids both the acoustic resonance phenomenon excitation and the lamp...
The LEDtherapy is increasingly becoming important in several health treatment areas, such as biomedical engineering, deontology, physical therapy and dermatology. The biomedical engineering, for example, has been experiencing major advances in the research on the application of LEDs in the treatment of pre-malignant or even malignant skin lesions, rejuvenation treatments, acne, hair loss, skin injuries...
One of the most important advantages in using piezoelectric transformers (PT) is that they operate at high frequencies with a very good efficiency [1], tipically higher than 95%. This paper presents a DC/DC converter based on two piezoelectric transformers which duplicates the output voltage frequency ripple, maintaining the switching frequency. Also, the converter operates at a fixed frequency, and...
One of the major drawbacks of high-ratio step-up transformers is the high value of their secondary side capacitor. This value is reflected at the primary side giving rise to a non-desirable one. There are some converters which include this capacitor in the topology and can cope with it, and even more, they need it. Particularly, in high-voltage applications, we will find transformers with a large...
This paper presents a novel design for double conversion UPS systems that results in higher power density, higher efficiency and more flexible parallelism for higher reliability. This design comprises a three-level circuit topology, a customized power semiconductor module and a cross current sensorless parallel control. The innovative circuit topology results in an UPS with higher efficiency and dramatic...
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