SYSTEM AND METHOD FOR CONTROLLING LOAD DUMP VOLTAGE OF A SYNCHRONOUS MACHINE
First Claim
1. For use in an automobile electrical system having an alternator drivingly connected to a vehicle engine, the alternator having a polyphase output winding producing a polyphase output in the form of a polyphase alternator voltage for each phase, a load dump apparatus for varying the output of the alternator comprising:
- a control bridge adapted to be coupled to said polyphase output winding and having a pair of direct voltage output terminals, said control bridge including a first switchable element and a second switchable element for each corresponding phase winding, said first switchable element comprising at least one of a rectifier, a silicon control rectifier, a field effect transistor and a TRIAC, and said first and second switchable elements being connected in series across the output of the bridge and having a common input note adapted to be connected to the corresponding phase winding, each controllable in accordance with a respective conduction signal applied thereto, a controller for generating a plurality of conduction signals, said conduction signals being applied to said first and second switchable elements for controlling the conduction thereof under normal operating condition and for controlling the switchable elements under an over voltage condition; and
wherein the normal operating condition occurs when the output voltage of each phase winding is up to a selected limit and the over-voltage condition occurs when the output voltage of any phase winding exceeds 14 volts, the conduction of the first switching element for a phase being on for a time when the corresponding phase voltage is above 14 volts.
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Abstract
In an automobile electrical system having an alternator drivingly connected to a vehicle engine the alternator has a polyphase output winding 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 coupled to the polyphase output winding and having a pair of direct voltage output terminals. The bridge has lower and upper switchable elements for each corresponding phase winding, the switchable elements are forward biased and 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 applied thereto. A controller 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 over-voltage limit.
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Citations
18 Claims
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1. For use in an automobile electrical system having an alternator drivingly connected to a vehicle engine, the alternator having a polyphase output winding producing a polyphase output in the form of a polyphase alternator voltage for each phase, a load dump apparatus for varying the output of the alternator comprising:
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a control bridge adapted to be coupled to said polyphase output winding and having a pair of direct voltage output terminals, said control bridge including a first switchable element and a second switchable element for each corresponding phase winding, said first switchable element comprising at least one of a rectifier, a silicon control rectifier, a field effect transistor and a TRIAC, and said first and second switchable elements being connected in series across the output of the bridge and having a common input note adapted to be connected to the corresponding phase winding, each controllable in accordance with a respective conduction signal applied thereto, a controller for generating a plurality of conduction signals, said conduction signals being applied to said first and second switchable elements for controlling the conduction thereof under normal operating condition and for controlling the switchable elements under an over voltage condition; and
wherein the normal operating condition occurs when the output voltage of each phase winding is up to a selected limit and the over-voltage condition occurs when the output voltage of any phase winding exceeds 14 volts, the conduction of the first switching element for a phase being on for a time when the corresponding phase voltage is above 14 volts. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. In an electrical system having an alternator having a field winding, a polyphase output winding for producing a polyphase output in the form of a polyphase alternating voltage and a bridge having a direct current output, including a first and second series connected switchable elements for each phase coupled across the output and coupled to each corresponding phase winding at a neutral point therebetween, a method for varying the output of the alternator comprising the steps of:
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generating a plurality of conduction signals for each corresponding phase of the polyphase alternating voltage;
sensing the voltage in each phase winding of the polyphase output winding;
applying the conduction signals to the switchable elements of the bridge;
comparing the output voltage with a selected voltage limit; and
adjusting the conduction timing of the conduction signals for only the first switchable elements and the current in the field winding so as to reduce the voltage for the phase below the voltage limit. - View Dependent Claims (16, 17, 18)
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Specification