Systems and method for boosting output of an alternator

• US 20060164046A1
• Filed: 03/27/2006
• Published: 07/27/2006
• Est. Priority Date: 08/18/2004
• Status: Active Grant

• Current Assignee: Temic Automotive of North America, Incorporated (Continental AG)
• Original Assignee: Temic Automotive of North America, Incorporated (Continental AG)
• Inventors: O'Gorman, Patrick A., Stephens, Dennis L.
• Granted Patent: US 7,193,395 B2
• Time in Patent Office: Days
• US Class Current: 322/28
• CPC Class Codes: H02J 7/24 using discharge tubes or semiconductor devices
• CPC Class Codes: H02P 2101/45 for motor vehicles, e.g. car alternators
• CPC Class Codes: H02P 2209/01 Motors with neutral point connected to the power supply
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Disclosed herein are two techniques, neutral point switching and field voltage boost, that will increase the output of today'"'"'s 12 volt automotive electrical systems in vehicle idle conditions solely by the addition of circuitry. Neutral point switching enables the flow of a third harmonic current, which does not normally flow at low speeds, but only at high speed. Boosting the field voltages can be obtained by integrating a field voltage boost circuit and voltage regulator to increase the field voltage, and consequently the field current, above the level obtained from the battery. Furthermore, the transient response of the alternator to a change in load is improved by temporarily increasing the field voltage above the level needed to sustain the load. These two techniques are compatible, and thus may be implemented together, or may be implemented independently. No changes to a standard alternator are required to accommodate the proposed additional circuitry.

Claims

1. An automotive electrical system comprising:

a storage battery having a positive terminal connected to a positive bus and a negative terminal connected to a negative bus;

an alternator having its output connected to a rectifier bank, wherein the output terminals of the rectifier bank are connected to the positive bus and the negative bus;

a voltage regulator configured to control a field current of the alternator in response to the voltage between the positive bus and the negative bus; and

a neutral switch comprising a first switching device and a second switching device, wherein the first switching device is connected between a neutral terminal of the alternator and the positive bus and wherein the second switching device is connected between the neutral terminal of the alternator and the negative bus, the neutral switch being configured to allow third harmonic current generated by the alternator to flow to one or more loads connected between the positive bus and the negative bus.

2. The automotive electrical system of claim 1 wherein the switching devices are controlled by a square wave out of phase with the third harmonic voltage on the neutral conductor.

3. The automotive electrical system of claim 2 wherein the phase difference between the square wave and the third harmonic voltage is controlled such that the maximum power is extracted from the 3_rd harmonic component.

4. The automotive electrical system of claim 2 wherein the phase difference between the square wave and the third harmonic voltage is modulated to produce a required current.

5. The automotive electrical system of claim 1 wherein the switching devices are controlled by a PWM waveform to produce a required current.

6. The automotive electrical system of claim 1 further comprising a buck converter connected between the positive bus and a second positive bus such that the buck converter controls the voltage of the first positive bus to effect charging of the battery, and wherein the first switching device is connected between the alternator neutral terminal and the second positive bus.

7. The automotive electrical system of claim 6 further comprising a second buck converter connected between the negative bus and a second negative bus such that the buck converter reduces the voltage of the second negative bus relative to the negative bus and wherein the second switching device is connected between the alternator neutral terminal and the second negative bus.

8. A method of increasing the output current of an alternator in an automotive electrical system, the method comprising:

providing a switched current path between a neutral terminal of the alternator and at least one bus of the automotive electrical system;

operating at least one switch corresponding to the switched current path to allow third harmonic current to flow from the neutral terminal of the alternator to the at least one bus at an idle condition.

9. The method of claim 8 further comprising:

providing an electronic power converter between the at least one bus and a second bus of the automotive electrical system, wherein a storage battery is connected to the second bus; and

operating the electronic power converter to control the voltage on the second bus for battery charging and allowing the voltage on the at least one bus to increase to supply greater current to a load.

10. The method of claim 8 further comprising:

providing a second electronic power converter having an input connected to the automotive electrical system and an output connected to a field winding of an alternator; and

operating the second electronic power converter to boost a voltage applied to the field winding.

11. The method of claim 10 wherein the second electronic power converter is controlled in response to at least one parameter selected from the group consisting of battery current and voltage regulator duty cycle.