| 摘要 |
A dual-mode system for inexpensively operating electrically powered double-insulated devices (12), such as hand-held power tools and appliances. The system includes a cordless battery pack (14) that supplies the power and current demands of the device (12) in a cordless mode or a non-isolated corded voltage converter (16) that supplies the necessary power and current demands in a physical envelope commensurate in size and interchangeable with that of the battery pack (14). The corded voltage converter (16) is provided with a non-isolated high efficiency power supply that allows the converter (16) to generate the power and current required by the driven device (12). The double insulation of the driven device (12) negates the need for a transformer-isolated voltage converter. Eliminating the power transformer from the converter significantly reduces the cost of the module (16). Additionally, the need for multiple battery packs and fast rechargers is minimized by the availability of a low-cost converter. The voltage converter (16) includes an inrush current limiter (103) and power conditioner for filtering AC or DC input power. The filtered voltage is chopped by a transformerless buck-derived converter. The chopped voltage is rectified and filtered to provide low-voltage DC power to the drive motor of the powered double-insulated device (12).
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