초록 ▼

A high DC voltage power supply includes a three-phase autotransformer and a three-phase full-wave rectifier applied to the usual motor vehicle electrical system of the low DC voltage type. The low three-phase AC voltage of the usual system is transformed by the autotransformer to obtain a high three

A high DC voltage power supply includes a three-phase autotransformer and a three-phase full-wave rectifier applied to the usual motor vehicle electrical system of the low DC voltage type. The low three-phase AC voltage of the usual system is transformed by the autotransformer to obtain a high three-phase AC voltage which is then rectified by the rectifier to provide a high DC voltage. The load energized by the high DC voltage is ungrounded to reduce the voltage available for inadvertent discharge from either load terminal to ground. Switching apparatus is provided for selectively applying the low three-phase AC voltage to the autotransformer only when it is desired to energize the load thereby avoiding at all other times the energy losses that would otherwise be associated with energization of the autotransformer. In one embodiment, the load is windshield heater element and the autotransformer has multiple sets of input taps to provide deice and defog modes of operation, respectively. The tapping of the autotransformer on the input or primary side yields efficiencies in the construction and operation of the autotransformer. In another embodiment, a current transformer is provided for measuring the AC current through one of the input and output leads of the autotransformer as an indication of the DC current through the load thereby to detect an abnormally low load current condition.

대표청구항 ▼

For a motor vehicle electrical system of the type providing a low DC voltage with respect to ground and including a storage battery for providing standby power at the low DC voltage, a motor driven generator for producing a low three-phase AC voltage, and a three-phase rectifier for converting the l

For a motor vehicle electrical system of the type providing a low DC voltage with respect to ground and including a storage battery for providing standby power at the low DC voltage, a motor driven generator for producing a low three-phase AC voltage, and a three-phase rectifier for converting the low three-phase AC voltage to the low DC voltage for charging the battery and supplying various low DC voltage loads, the combination comprising: a three-phase autotransformer of the voltage step-up type for transforming the low three-phase AC voltage put out by the generator to provide a high three-phase AC voltage where the autotransformer is unrelated to the production of the low DC voltage; a three-phase full-wave rectifier for rectifying the high three-phase AC voltage put out by the autotransformer to provide a high DC voltage; and a high DC voltage load having a pair of ungrounded terminals across which the high DC voltage is applied such that with respect to ground the voltage at one terminal of the load is above ground and the voltage at the other terminal of the load is below ground thereby to reduce the voltage available for inadvertent discharge from either terminal of the load to ground by up to approximately one-half the voltage that would otherwise be available for inadvertent discharge from the ungrounded terminal of the load to ground if one terminal of the load was grounded.