System and method for regulating an alternator

• US 6,392,577 B1
• Filed: 10/05/1999
• Issued: 05/21/2002
• Est. Priority Date: 10/05/1999
• Status: Expired due to Term

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV), STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Cocetta, Franco, Merlo, Mauro, Swanson, David F.
• Primary Examiner(s): Jeanpierre, Peguy
• Assistant Examiner(s): LAUTURE, JOSEPH J
• Application Number:
  US09/412,534
• Time in Patent Office: 959 Days
• Field of Search: 341/144, 341/155, 322/25, 324/434, 324/433, 320/15, 320/19, 320/39, 320/22, 320/32, 320/14, 363/17, 363/41, 363/98
• US Class Current: 341/144
• CPC Class Codes: H02J 7/2434 with pulse modulation
• CPC Class Codes: H02P 9/30 using semiconductor devices
• 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

A system and method regulates an alternator and includes a circuit for digitally generating a sawtooth waveform. An error amplifier circuit generates a divided down and error amplified alternator system voltage. A comparator circuit receives and compares to each other the digitally generated sawtooth waveform and the error amplified alternator system voltage and has an output to produce an alternator field input signal used for driving the field of an alternator.

Claims

1. A system for regulating an alternator comprising:

a digital-to-analog converter for digitally generating a sawtooth waveform, a down counter having an output connected to said digital-to-analog converter, and a clock that inputs a clock signal to the down counter;

an error amplifier circuit for generating a divided down and error amplified alternator system voltage;

a voltage summing circuit operatively connected to said digital-to-analog converter and error amplifier circuit; and

a comparator circuit operatively connected to said voltage summing circuit and said error amplifier circuit for receiving and comparing to each other the digitally generated sawtooth waveform and the error amplified alternator system voltage and having an output to produce an alternator field input signal used for driving the field of an alternator.

2. A system according to claim 1, wherein said clock is operative to generate about 20 kHz clock signals to said down counter.

3. A system according to claim 1, wherein said circuit for digitally generating a sawtooth waveform, said error amplifier circuit, and said comparator circuit are monolithically formed as a single semiconductor circuit.

4. A system according to claim 1, and further comprising an n-bit latchable down counter operatively connected to said output of said comparator circuit, and a stator prescaler circuit operatively connected to said n-bit latchable down counter.

5. A system according to claim 4, and further comprising a digital comparator operatively connected to said n-bit latchable down counter and operatively connected to said circuit for digitally generating a sawtooth waveform.

6. A system according to claim 4, and further comprising a clock operatively connected to said stator prescaler.

7. A system according to claim 6, wherein said clock is operative to produce about a 300 Hz clock signal to said stator prescaler.

8. A system according to claim 4, wherein said n-bit latchable down counter further comprises an 8-bit latchable down counter.

9. A system for regulating an alternator comprising:

a digital-to-analog converter circuit for digitally generating a sawtooth waveform, said circuit comprising a down counter having an output, a clock operatively connected to said down counter for driving said down counter, and a digital-to-analog converter connected to said output of said down counter;

an error amplifier circuit for generating a divided down and error amplified alternator system voltage;

a voltage summing circuit operatively connected to said digital-to-analog converter and error amplifier circuit;

a comparator operatively connected to said voltage summing circuit and error amplifier circuit for receiving and comparing to each other the digitally generated sawtooth waveform and the error amplified alternator system voltage and having an output;

a clock driven stator prescaler circuit;

an n bit latchable down counter operatively connected to said output of said comparator and said stator pre-scaler circuit; and

a digital comparator having an input connected to said n bit latchable down counter and said output of said down counter for producing at a digital comparator output an alternator field input signal used for driving the field of an alternator.

10. A system according to claim 9, wherein said n bit latchable down counter comprises an 8 bit latchable down counter.

11. A system according to claim 9, and further comprising a clock having a 300 hertz clock signal to said stator prescaler circuit.

12. A system according to claim 9, wherein said clock operatively connected to said down counter is operative to generate about 20 kHz clock signals.

13. A system according to claim 9, wherein said circuit for digitally generating a sawtooth waveform, said error amplifier circuit, said comparator, said clock driven prescaler circuit, said n-bit latchable down counter, and said digital comparator are monolithically formed as a single semiconductor circuit.

14. A system according to claim 9, and further a logic gate for receiving the output of said comparator and a feedback loop of said alternator field input signal.

15. A method of regulating an alternator comprising the steps of:

digitally generating a sawtooth waveform by a digital-to-analog converter connected to a down converter and summing circuit, which is connected to an error amplifier;

comparing the digitally generated sawtooth waveform received from the summing circuit in an analog comparator connected to the summing circuit and the error amplifier with a divided down and error amplified alternator system voltage to produce an alternator field input signal; and

driving the field of an alternator with the alternator field input signal.

16. A method according to claim 15, and further comprising the step of digitally generating the sawtooth waveform within a digital-to-analog converter that is controlled by a down counter and clock signal produced by a clock.

17. A method according to claim 16, wherein said clock is operative for producing about 20 kHz clock signals to said down counter.

18. A method according to claim 16, and further comprising the step of providing the digital-to-analog converter, down counter and clock as a monolithically formed semiconductor circuit.

19. A method according to claim 16, and further comprising the step of providing a downward counting value from 255 to 0.

20. A method according to claim 15, and further comprising the step of turning on the field drive by a system voltage that is below a set point.