Voltage-limiting regulator for use with an AC generator having DC-excited fields

• US 6,528,973 B2
• Filed: 01/22/2001
• Issued: 03/04/2003
• Est. Priority Date: 01/22/2001
• Status: Active Grant

• Current Assignee: Robert Fury
• Original Assignee: Robert Fury
• Inventors: Fury, Robert
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): GONZALEZ, JULIO CESAR
• Application Number:
  US09/765,283
• Publication Number:
  US 20020097024A1
• Time in Patent Office: 771 Days
• Field of Search: 322/28, 322/25, 322/15, 322/29
• US Class Current: 322/28
• CPC Class Codes: H02P 9/305 controlling voltage H02P9/302 takes precedence

Abstract

The present invention features a voltage-limiting regulator for use with an AC generator having DC-excited fields. The AC output voltage from the generator is sensed and compared to a fixed reference representative of the sensed difference is amplified and applied to the DC field excitation input of the AC generator. As the DC voltage supplied to the field varies, the AC output voltage from the generator may be held constant under varying load conditions. The voltage-limiting regulator is particularly useful for vehicle-mounted, high power, single phase AC generators.

Claims

1. A voltage-limiting regulator apparatus for use with an AC generator having a DC-excited field, comprising:

a) AC voltage sensing means for sensing a signal representative of said AC output voltage;

b) rectifying means operatively connected to said AC voltage sensing means for receiving said AC sensing signal and generating a DC sense voltage signal representative thereof;

c) reference voltage means operatively connected to said rectifying means for generating a fixed, DC reference voltage from said DC sense voltage signal;

d) comparing means, operatively connected to said reference voltage means, for generating a comparitor output voltage related to the difference between said DC sense voltage and said DC reference voltage; and

e) output transistor means for providing a DC output voltage related to said comparitor output voltage;

whereby a DC output voltage is applied to said AC generator such that an AC output voltage from said AC generator is held substantially constant regardless of the load applied thereto.

2. The voltage-limiting regulator apparatus as recited in claim 1, wherein said AC sensing means comprises at least one from the group:

direct electrical connection to said AC output of said AC generator, and an indirect pickup inductively coupled to said AC output of said AC generator.

3. The voltage-limiting regulator apparatus as recited in claim 2, further comprising clamping means operatively connected to said AC output of said AC generator whereby voltage spikes on said AC output are reduced to a value below a predetermined threshold.

4. The voltage-limiting regulator apparatus as recited in claim 3, wherein said clamping means comprises a varistor.

5. The voltage-limiting regulator apparatus as recited in claim 1, further comprising:

f) isolator means operatively connected between said comparing means and said output transistor means.

6. The voltage-limiting regulator apparatus as recited in claim 5, wherein said isolator means comprises an optical isolator.

7. The voltage-limiting regulator apparatus as recited in claim 1, wherein said AC output voltage is one from the group:

approximately 125 volts and approximately 220 VAC.

8. The voltage-limiting regulator apparatus as recited in claim 7, wherein said AC output voltage is held to within approximately +5 volts.

9. The voltage-limiting regulator apparatus as recited in claim 1, wherein said fixed DC reference voltage signal is an approximately 5 volt DC voltage.

10. The voltage-limiting regulator apparatus as recited in claim 1, wherein said output transistor means comprises at least one MOSFET power transistor.

11. The voltage-limiting regulator apparatus as recited in claim 10, wherein said at least one MOSFET power transistor comprises a pair of cascaded MOSFET power transistors.

12. The voltage-limiting regulator apparatus as recited in claim 10, wherein said output transistor means further comprises a flyback diode to protect said at least one MOSFET power transistor from transient voltage spikes.

13. The voltage-limiting regulator apparatus as recited in claim 10, wherein said DC output voltage is applied to at least one field energization connection on said AC generator.

14. A method for regulating the output of an AC generator having a DC-excited field, the steps comprising:

a) providing an AC generator producing an AC output voltage for driving a load;

b) sensing said AC output voltage and producing an AC sense signal representative thereof;

c) rectifying said AC sense signal to produce a DC sense signal representative thereof and applying said DC sense signal to a first input of a comparitor;

d) providing a constant DC reference voltage to a second input of a comparitor;

e) performing an algebraic comparison of said constant DC reference voltage and said DC sense signal and providing an output voltage signal representative thereof;

f) amplifying said output signal to generate an amplified output signal; and

g) applying said amplified output signal to at least one field excitation input of said AC generator;

where said AC output of said AC generator is held substantially constant when said load attached to said AC output varies.