Alternator regulation circuit having parallel field coil current re-circulation

• US 6,670,792 B1
• Filed: 09/07/2001
• Issued: 12/30/2003
• Est. Priority Date: 09/07/2001
• Status: Expired due to Fees

• Current Assignee: ASBU Holdings, LLC
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Renehan, John F.
• Primary Examiner(s): Ponomarenko, Nicholas
• Assistant Examiner(s): Cuevas, Pedro J.
• Application Number:
  US09/949,262
• Time in Patent Office: 844 Days
• Field of Search: 322/28, 322/25, 322/22, 322/17
• US Class Current: 322/28
• CPC Class Codes: H02J 7/2434 with pulse modulation
• 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 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

Among the embodiments of the present invention is an apparatus that includes an alternator field coil, a driver coupled to the alternator field coil to provide excitation current thereto, and a recirculation circuit coupled to the alternator field coil. The recirculation circuit includes a unidirectional current device and a current sensing device electrically coupled in series. The driver is electrically coupled between a first electrical power supply node and the field coil, and the recirculation circuit is electrically coupled between the driver and a second electrical power supply node.

Claims

1. An apparatus, comprising:

an alternator field coil;

a driver coupled to said alternator field coil to provide an excitation current thereto;

a recirculation circuit coupled to said alternator field coil, said recirculation circuit including a unidirectional current device and a current sensing device electrically coupled in series; and

wherein said driver is electrically coupled between a first electrical power supply node and said field coil, and said recirculation circuit is electrically coupled between said driver and a second electrical power supply node.

2. The apparatus of claim 1, wherein said unidirectional current device includes at least one diode, said current sensing device includes at least one resistor, and said driver includes at least one transistor.

3. The apparatus of claim 1, wherein said recirculation circuit is electrically coupled in parallel with said alternator field coil.

4. The apparatus of claim 1, further comprising circuitry to selectively activate said driver to modulate the excitation current provided to said alternator field coil, said circuitry including a pair of differential inputs coupled across said current sensing device.

5. An apparatus, comprising:

an alternator including a field coil;

a driver to provide excitation current to said field coil; and

a recirculation circuit electrically coupled in parallel with said field coil, said recirculation circuit including a current sensing device electrically coupled in series with a unidirectional current device.

6. The apparatus of claim 5, wherein said unidirectional current device includes at least one diode, said current sensing device includes at least one resistor, and said driver includes at least one transistor.

7. The apparatus of claim 5, wherein said recirculation circuit is electrically coupled to said field coil and said driver by a first electrical node, said recirculation circuit and said field coil are coupled together by a second electrical node, and said second electrical node is common to electrical ground.

8. The apparatus of claim 5, wherein said recirculation circuit is electrically coupled to said field coil and said driver by a first electrical node, said recirculation circuit and said field coil are coupled together by a second electrical node, and said second electrical node is common to an electrical power supply bus different than electrical ground.

9. The apparatus of claim 5, further comprising:

circuitry to sense voltage output by said alternator to regulate operation of said driver as a function of said voltage output; and

a differential amplifier to provide a current level signal, said differential amplifier including a pair of differential inputs coupled across said current sensing device.

10. The apparatus of claim 9, further comprising a control module responsive to the current level signal.

11. An apparatus, comprising:

an alternator including a field coil; and

circuitry including a switching device, a current sensing device, and a unidirectional current device, said unidirectional current device being electrically coupled in series with said current sensing device and being operable to route more electric current through said current sensing device during an inactive state of said switching device than during an active state of said switching device.

12. The apparatus of claim 11, wherein said unidirectional current device includes at least one diode, said current sensing device includes at least one resistor, and said switching device includes at least one transistor.

13. The apparatus of claim 11, further comprising circuitry to sense voltage output by said alternator and regulate operation of said switching device as a function of said voltage and electrical current sensed with said current sensing device.

14. The apparatus of claim 11, wherein said switching device is electrically coupled between an electrical power supply node of said alternator and said field coil, and said switching device conducts more excitation current to said field coil during said active state than during said inactive state.

15. The apparatus of claim 11, wherein said unidirectional current device includes a diode, said current sensing device includes a resistor, and said switching device includes a transistor, said active state corresponds to a conductive condition of said transistor, said inactive state corresponds to a nonconductive condition of said transistor, and further comprising:

an integrated circuit electrically coupled to said resistor and said transistor, said integrated circuit including circuitry to selectively change state of said transistor to modulate excitation current supplied to said field coil and a pair of differential inputs coupled across said resistor to provide a current level signal; and

a control module responsive to the current level signal, said control module being coupled to said integrated circuit.

16. A method, comprising:

providing circuitry including a switching device, a current sensing device, and a unidirectional device;

controlling electrical current flow through an alternator field coil with the circuitry; and

routing more electric current through the unidirectional current device and the current sensing device from the alternator field coil during one state of the switching device than during a different state of the switching device.

17. The method of claim 16, wherein said switching device includes a transistor, and said controlling includes modulating current flow through the field coil in accordance with a signal provided to the transistor, and which further includes:

sensing a voltage level corresponding to a voltage supply output provided with the alternator field coil; and

generating the signal with circuitry responsive to said voltage level.

18. The method of claim 17, wherein the transistor is nonconductive during the one state and the transistor is conductive during the different state.

19. The method of claim 16, wherein said routing includes:

flowing current in a recirculation current path through the alternator field coil, the unidirectional current device, and the current sensing device during the one state of the switching device; and

flowing current in an excitation current path through the switching device and the alternator field coil during the different state of the switching device.

20. A method, comprising:

establishing a first state of a driver to direct electric current flow through an alternator field coil along a first path;

changing the driver from the first state to a second state to route electrical current flowing through the alternator field coil along a second path different than the first path; and

sensing different nonzero levels of an electric current with a current sensing device in the second path that is not included in the first path.

21. The method of claim 20, wherein said establishing includes providing an activation signal to the switching device.

22. The method of claim 20, which includes:

determining a field coil current level signal from said sensing; and

providing the field coil current level signal to a control module.

23. The method of claim 22, wherein said determining includes generating the field coil current level signal with a differential amplifier.

24. The method of claim 20, wherein the current sensing device includes a current sensing resistor and said switching device includes a transistor.

25. The method of claim 24, further comprising providing a diode in the second path to selectively direct current through the current sensing device.

26. The method of claim 24, which further includes determining a peak current through the alternator field coil based on said sensing.