| 摘要 |
In an automobile electrical system (10) having an alternator (12) drivingly connected to a vehicle engine (36) the alternator has a polyphase output winding (14) producing a polyphase output in the form of a polyphase alternator voltage for each phase. A load dump apparatus and method for varying the output of the alternator employs a bridge (16) coupled to the polyphase output winding and having a pair of direct voltage output terminals. The bridge has lower and upper switchable elements (80L-80U, 82L-82U, 84U-84L) for each corresponding phase winding, the switchable elements are connected in series across the output of the bridge and have a common or neutral input note connected to the corresponding phase winding. Each switchable element is controllable in accordance with a respective conduction signal (a-aN, b-bN, c-cN) applied thereto. A controller (32-34) produces a plurality of conduction signals, which are applied to the switchable elements for controlling the conduction thereof for controlling the conduction timing for each of the lower switchable elements to render them conductive when the output voltage of the corresponding phase winding is above a selected overvoltage limit. |
