Patent Application
20070013387
This invention relates to the field of electronics. More precisely this invention pertains to detecting faults in multi-phase alternators.
Now referring to
The apparatus 12 comprises a comparing unit 16 comprising an operational amplifier 14. A comparison is performed between a reference signal 18 and a voltage signal provided by a given phase, in this case phase A.
In the case where a fault occurs at phase A, for instance, if phase A goes open circuit, the fault will be detected as the result of the comparison with the reference signal 18 will change. Unfortunately, if a fault occurs at phases B or C, it will remain undetected therefore creating potential electrical hazards.
There is a need for a method and apparatus that will overcome the above-identified drawbacks.
In one of its aspects, the present invention provides a method and apparatus for detecting one or more faults on a multi-phase alternator.
According to an embodiment of the invention, there is provided a method for detecting a fault in a multi-phase alternator. The method comprises providing an indirect measure of at least two of the phases of the multi-phase alternator; comparing the indirect measure of the phases with a reference; and detecting a fault condition using the comparison.
According to another embodiment of the invention, there is provided an apparatus for detecting a fault on a multi-phase alternator. The apparatus comprises a phase sensing unit for monitoring the multi-phase alternator and for reading a signal that indirectly measures at least two of the phases, thereby providing an indirect phase measure signal; and a comparing unit for receiving and comparing the indirect phase measure signal with a given reference signal to provide a comparison result signal indicative of the comparison; the comparison being used to detect the fault.
According to another embodiment of the invention, the apparatus for detecting a fault on a multi-phase alternator comprises a phase sensing unit having a star wound resistor assembly comprising a plurality of resistors, each resistor being connected, at one end, to a corresponding phase of the multi-phase alternator and, at the other end, a common star point from which is read an indirect phase measure signal; and a comparing unit having an operational amplifier receiving the indirect phase measure signal and a reference signal and providing therefrom a comparison result signal indicative of the comparison; the comparison being used to detect the fault.
Further details of these and other aspects of the present invention will be apparent from the detailed description and Figures included below.
Reference is now made to the accompanying Figures depicting aspects of the present invention, in which:
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
Now referring to
The apparatus 22 for detecting one or more faults in a multi-phase alternator 20 comprises a phase sensing unit 24, a comparing unit 26 and a fault detection unit 28. It is to be note that the apparatus 22 may be incorporated in a Electronic Engine Controller (EEC)
More precisely, the phase sensing unit 24 receives a first voltage signal, a second voltage signal and a third voltage signal provided respectively by phase A, phase B and phase C. Using the voltage signals from phases A, B, and C, the phase sensing unit 24 provides an indirect phase measure signal.
The comparing unit 26 receives the indirect phase measure signal provided by the phase sensing unit 24 and a reference signal and performs a comparison to provide a comparison result signal.
The fault detection unit 28 receives the comparison result signal and provides a fault detection signal when a fault is detected.
Now referring to
According to step 30, an indirect measure of at least two of the phases (in another embodiment it is an indirect measure of all the phases) of said multi-phase alternator is provided. Referring back to
Referring to step 32 of
Referring to step 34 of
Referring back to
The fault detection unit 28 provides a fault detection signal. It will be appreciated that in one embodiment, the fault detection signal is only representative of a fault occurring without any further details.
Now referring to
The apparatus 42 comprises a phase sensing unit 44, a comparing unit 46, and a fault detection unit 49.
The phase sensing unit 44 comprises three resistors (i.e., a star wound resistor assembly) which create an artificial star point S. Each resistor is connected to a phase A, B and C of the multi-phase alternator. The value of the resistor is chosen base on at least the fact that it must be between a maximum which is low by comparison with the current drawn by the comparing unit, and a minimum which presents a trivial load on the alternator. In one embodiment, each resistor has a value of 1 kohms. The star point S therefore provides an indirect phase measure signal which comprises a measure of the voltage value of each phase A, B and C. In an embodiment, with no faults present, this voltage is approximately at the potential of the “0 volt DC supply”. When there is an open circuit fault on (say phase A, then this voltage is the mean of phases B and C.
The comparing unit 46 receives the indirect phase measure signal. The comparing unit 46 comprises an operational amplifier 48. The operational amplifier 48 receives the phase measure signal as well as a reference signal which is simply a given fraction between the positive DC supply and the 0 volt DC line obtained using resistances 52 and 54. The operational amplifier 48 compares the received phase measure signal indicative of the measure of each phase as with the reference signal and thereby provides the comparison result signal to the monostable circuit 50 of the failure detection unit 49. Using the comparison result signal, the monostable circuit 50 provides a fault condition signal indicative of a fault condition.
While illustrated in the block diagrams as groups of discrete components communicating with each other via distinct data signal connections, it will be understood by those skilled in the art that the preferred embodiments may be provided by a combination of hardware and software components, with some components being implemented by a given function or operation of a hardware or software system, and many of the data paths illustrated being implemented by data communication within a computer application or operating system. The structure illustrated is thus provided for efficiency of teaching the present preferred embodiment.
The above description is meant to be exemplary only, and one skilled in the art will recognize that further changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.
