Electrical circuit for providing a reduced average voltage
First Claim
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1. An electrical system comprising:
- a direct current (DC) voltage source providing a first voltage;
an alternating current (AC) starter-alternator mechanism configured for warm cranking an engine and converting rotational energy from the engine into an AC current;
a starter mechanism, rated at a second voltage which is lower than the first voltage, for cold cranking the engine; and
a circuit coupled to the voltage source for;
providing the second voltage to the starter mechanism in response to a switch closing; and
in response to the switch opening, ceasing to provide the second voltage to the starter mechanism;
transferring energy from the DC voltage source to the AC starter-alternator mechanism; and
converting the AC current, converted from the engine by the starter-alternator, to a DC current in order to charge the voltage source.
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Abstract
Systems and methods of the invention may utilize integrated starter-alternator (ISA) electronics to drive a conventional DC starter coupled to a start-stop ISA system providing a voltage higher than that at which the starter is rated. The DC starter may cold crank an internal combustion engine, while a poly-phase starter alternator warn cranks the engine and converts mechanical energy to an AC current. The AC current may be converted to a DC current to provide charging functions. A reduced average voltage is provided to the DC starter and an adjustable-frequency alternating current may be provided to the starter alternator.
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Citations
42 Claims
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1. An electrical system comprising:
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a direct current (DC) voltage source providing a first voltage;
an alternating current (AC) starter-alternator mechanism configured for warm cranking an engine and converting rotational energy from the engine into an AC current;
a starter mechanism, rated at a second voltage which is lower than the first voltage, for cold cranking the engine; and
a circuit coupled to the voltage source for;
providing the second voltage to the starter mechanism in response to a switch closing; and
in response to the switch opening, ceasing to provide the second voltage to the starter mechanism;
transferring energy from the DC voltage source to the AC starter-alternator mechanism; and
converting the AC current, converted from the engine by the starter-alternator, to a DC current in order to charge the voltage source.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An electrical circuit comprising:
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at least one switching device coupled to a direct current (DC) voltage source providing a first voltage;
a first terminal set coupled to a switch, the first terminal set comprising at least one terminal coupled to the at least one switching device; and
a second terminal set coupled to an AC load having at least one phase, the second terminal set comprising at least one terminal coupled to the at least one switching device, wherein the at least one switching device is pulsed in response to the switch closing, thereby providing, via the first terminal set, a reduced average voltage from the DC voltage source to a DC device; and
wherein the at least one switch, in response to the switch opening, provides via the second terminal set, energy from the DC voltage source to the AC load.- View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An electrical system comprising:
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a voltage source providing a first voltage;
an electrical device requiring a second voltage lower than the first voltage;
an alternating current.(AC) machine, having at least one phase, for converting rotational energy from an engine into an AC current;
a circuit coupled to the voltage source, the AC machine, and a switch;
wherein the circuit;
causes, in response to the switch closing, a reduced average voltage substantially equivalent to the second voltage to be provided from the voltage source to the electrical device; and
in response to the switch opening, causes energy to be transferred from the voltage source to the AC machine and enables the voltage source to be charged via the AC current.
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32. In a system having a voltage source providing a first voltage, a starter motor rated at a second voltage lower than the first voltage, a starter-alternator device, and an engine including a throttle and a clutch, a method comprising the steps of:
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providing, in response to a user-controlled switch closing, a reduced average voltage substantially equal to the second voltage to the starter motor from the voltage source;
starting the engine via the starter motor;
providing, in response to the user controlled switch opening, the first voltage to the starter-alternator device from the voltage source;
charging the voltage source from the engine via the starter-alternator device;
stopping the engine after a predetermined period of time;
re-starting the engine via the starter-alternator device in response to a change in position of the throttle or clutch. - View Dependent Claims (33, 34, 35)
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36. In a system having a voltage source supplying a first voltage, a DC device, and AC load having a plurality of phases, a method comprising the steps of:
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providing a reduced average voltage from;
the voltage source to the DC device in response to a switch closing, wherein the reduced average voltage is lower than the first voltage; and
transferring a plurality of voltages substantially equal in magnitude, each displaced by a phase angle, to the AC load from the voltage source in response to the switch opening. - View Dependent Claims (37, 38, 39, 40, 41, 42)
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Specification