Method and apparatus for determining the operating condition of generator rotating diodes

• US 20100066400A1
• Filed: 09/15/2008
• Published: 03/18/2010
• Est. Priority Date: 09/15/2008
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Hendrickson, Matthew, Beach, Frederick, Bailey, Bradley
• Granted Patent: US 8,410,739 B2
• Time in Patent Office: Days
• US Class Current: 324/762.70
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 3/0069 relating to the isolation, e.g. ground fault or leak current
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

A controller (500) in an electric drive system is used to determine the operating condition of array of rotating diodes (302B) within a generator (204). During operation, the controller (500) receives a set of generator inputs, a set of machine parameters, and a set of diagnostic values. Next, the controller (500) determines a set of expected operating values corresponding to the set of diagnostic values. The controller (500) then compares the obtained diagnostic values to one or more corresponding expected operating values. If the difference is greater than a threshold, the controller (500) provides a fault indication that one or more of the array of rotating diodes (302B) has malfunctioned.

Claims

1. A method for determining a malfunction condition of rotating diodes within a power generator associated with an electric drive system, the electric drive system including a prime mover disposed to provide an output and a power circuit associated with the power generator, the power generator including a rotating portion containing the rotating diodes coupled with the prime mover output, an input winding disposed to receive an input control signal, and an output winding disposed to provide a generator output, the method comprising:

receiving at a controller a set of generator inputs including the input control signal provided to the generator;

receiving a signal indicative of the output of the prime mover;

determining at least one diagnostic value associated with the output of the power generator based on the input control signal and the signal indicative of the output of the prime mover;

determining at least one expected operating value corresponding to the at least one diagnostic value;

comparing the at least one diagnostic value to the at least one expected operating value to determine a difference value; and

providing an indicator that the rotating diodes within the generator have malfunctioned if a magnitude of the difference value is greater than a threshold.

2. The method of claim 1, wherein the power generator is a multi-phase AC synchronous generator having a rotating input coupled with the prime mover output, an input winding coupled with an output and disposed to receive the input control signal in the form of an excitation signal, an output winding magnetically coupled with the input winding and disposed to provide a multi-phase current to a rectifier circuit coupled with the generator output and associated with the power circuit.

3. The method of claim 2, wherein the at least one diagnostic value is one of a set of diagnostic values including a prime mover output speed, an excitation value developed at the generator input winding, a DC link voltage developed at the power circuit, a DC link current developed at the power circuit, a generator output power value determined as a function of the DC link voltage and the DC link current, a temperature detected at the generator input winding, and a temperature detected at the generator output winding.

4. The method of claim 1, further including identifying that one or more than one of the rotating diodes are malfunctioning.

5. The method of claim 1, wherein the determination of the malfunction condition occurs when the electric drive system is operating in an idle condition.

6. The method of claim 1, further comprising providing the indicator if a variance for a first diagnostic value does not correlate to a variance for a second diagnostic value, wherein the first diagnostic value and the second diagnostic value are associated with a set of diagnostic values.

7. The method of claim 1, wherein the at least one expected operating value is part of a set of expected operating values that is based on an operating environment of the electric drive system.

8. The method of claim 1, further including the step of activating a visual indicator associated with the controller.

9. A controller disposed to monitor an operating condition of an array of rotating diodes within a power generator associated with an electric drive system, the electric drive system including an engine disposed to provide an output and a power circuit connected to the power generator, the power generator including a rotating portion containing the rotating diodes coupled with the output of the prime mover, an input winding disposed to receive an input control signal, and an output winding disposed to provide a generator output, the controller comprising:

an input receiving portion configured to receive a set of diagnostic values relating to engine parameters associated with the engine, generator inputs, and generator outputs;

a determination portion configured to determine an expected power output by the generator based upon at least a portion of the set of diagnostic values;

a calculation portion configured to calculate a value corresponding to an actual power output by the power generator based upon at least a portion of the set of diagnostic values;

a comparison portion configured to compare the value corresponding to the actual power output by the power generator to the expected power output by the power generator and to determine a difference value; and

an indicator portion configured to set a flag when at least one of the array of rotating diodes has malfunctioned.

10. The controller of claim 9, wherein the set of diagnostic values includes:

an engine output speed;

an excitation value developed at the generator input winding;

a DC link voltage developed at the generator output winding; and

a DC link current developed at the generator output winding.

11. The controller of claim 10, wherein the indicator portion is further configured to specify that more than one rotating diode of the array of rotating diodes has malfunctioned.

12. The controller of claim 11, wherein the indicator portion is further configured to set the flag if a difference between a first diagnostic value and a first expected operating value does not correlate to a difference between a second diagnostic value and a second expected operating value, wherein the first diagnostic value and the second diagnostic value are associated with the set of diagnostic values.

13. A power circuit configured to monitor an operating condition of rotating diodes within a generator associated with an electric drive system in a machine, the electric drive system including a prime mover disposed to provide an output coupled with the generator, the power circuit comprising:

a rectifier circuit coupled to the output of the generator;

a DC link coupled to the rectifier circuit having a DC link voltage defined between a first DC rail and a second DC rail; and

a controller configured to receive a set of generator inputs, a set of machine parameters associated with the machine, and a set of diagnostic values associated with the generator, the controller being further configured to determine a set of expected operating values and one or more actual operating values, to compare the set of expected operating values with one or more actual values and to provide a difference, and to set a flag indicating a malfunction condition for one or more rotating diodes when a magnitude of the difference exceeds a threshold.

14. The power circuit of claim 13, wherein the generator is a multi-phase AC synchronous generator having a rotating input coupled with the prime mover output, an input winding coupled with an output and disposed to receive an excitation signal, an output winding magnetically coupled with the input winding and disposed to provide a multi-phase current signal to the rectifier circuit.

15. The power circuit of claim 14, wherein the set of diagnostic values and the set of expected operating values includes:

a prime mover output speed;

an excitation value developed at the generator input winding;

the DC link voltage developed at the first DC rail; and

a DC link current developed at the first DC rail.

16. The power circuit of claim 15, wherein the set of diagnostic values includes phase values associated with a current output developed at the generator output winding.

17. The power circuit of claim 16, wherein the flag identifies one or more of the rotating diodes that have malfunctioned.

18. The power circuit of claim 17, wherein the controller sets the flag if a difference between a first diagnostic value and a first expected operating value does not correlate to a difference between a second diagnostic value a second expected operating value.

19. The power circuit of claim 17, wherein the set of expected operating values is based on an operating environment of the machine.

20. The power circuit of claim 14 further comprising:

an inverter circuit coupled with the DC link;

an output drive coupled with the inverter circuit; and

a retard circuit coupled with the DC link, the inverter circuit, and the output drive and disposed to dissipate retard energy supplied by the output drive through the inverter circuit during a retard mode of operation.