Method and device for detecting failure of excitation circuit of polyphase alternator

• US 8,618,829 B2
• Filed: 11/27/2007
• Issued: 12/31/2013
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: Valeo Equipements Electriques Moteur (Valeo SE)
• Original Assignee: Valeo Equipements Electriques Moteur (Valeo SE)
• Inventors: Pierret, Jean-Marie, Masson, Philippe
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): CLARKE, ADAM S
• Application Number:
  US12/515,666
• Publication Number:
  US 20120161810A1
• Time in Patent Office: 2,226 Days
• Field of Search: 324/765.01, 324/500, 324/503, 324/509, 324/522, 324/537, 324/545, 324/546, 322/99, 361/18, 361/93.1
• US Class Current: 324/765.01
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G01R 31/346 Testing of armature or field windings
• CPC Class Codes: G01R 31/54 Testing for continuity
• CPC Class Codes: H02P 9/305 controlling voltage H02P9/302 takes precedence

Abstract

The method of detecting the failure of the excitation circuit of a polyphase alternator controlled by a regulator comprises the following steps: a) electrical information (Iexc) is continuously taken from the excitation circuit (1); b) the electrical information taken in step a) is continuously compared with a predetermined threshold value (Iref); c) a logic state (LT) is continuously determined according to the result of the comparison made in step b); and d) if the logic state (LT) determined in step c) persists for a time at least equal to a predetermined delay time (6), an electrical continuity fault of said excitation circuit is signalled. This method is particularly suitable for machines having a rotor equipped with permanent magnets or having a high remanence of the magnetic circuit of the rotor.

Claims

1. A method for detecting the failure of an excitation circuit of a polyphase alternator controlled by a regulator, said method comprising the following steps:

a) continuously taking electrical information (Iexc;

Von) other than a phase signal from said excitation circuit;

b) continuously comparing said electrical information taken in step a) with a predetermined threshold value (Iref, Vref);

c) continuously determining a logic state (LT) according to the result of the comparison made in step b); and

d) signalling an electrical continuity fault of said excitation circuit if said logic state (LT) determined in step c) persists for a time at least equal to a predetermined delay time (6);

said electrical information taken being an excitation current (Iexc) and said predetermined threshold value being a predetermined reference current (Iref).

2. The method according to claim 1, wherein the polyphase alternator has a rotor with permanent magnets or a rotor having a high remanence of a magnetic circuit thereof, and wherein said electrical continuity fault is only signalled if, as a supplementary condition, a command is detected in said regulator to supply a maximum current (Imax) to said excitation circuit.

3. A device for detecting the failure of an excitation circuit of a polyphase alternator according to claim 1, said excitation circuit comprising:

a first switching transistor (2) mounted in series with a field winding (1) of said alternator at the terminals of a supply voltage source (UB); and

a second transistor (10) mounted in series with a reference current source (11) at the terminals of said supply voltage source (UB);

said second transistor (10) serving to mirror the current from said first switching transistor (2), and delivering a testing current (Iexc/n) proportional to said excitation current (Iexc) present in said first transistor.

4. The device for detecting the failure of an excitation circuit of a polyphase alternator according to claim 3, wherein said device also includes a resistor (8) and a first peak-clipping diode (9) in series shunted to the terminals of said field winding (1), a second peak-clipping diode (12) shunted to the terminals of said reference current source (11), and a gate (6, 7, 13, 14) generating said logic state (LT) as a function of first and second logic levels present at the terminals of the first and second peak-clipping diodes (9, 12) respectively.

5. The device according to claim 4, wherein said gate (6, 7, 13, 14) for generating said logic state contains a delay circuit (6).

6. A polyphase alternator comprising a device for detecting the failure of the excitation circuit according to claim 3.

7. An alternator-starter comprising a device for detecting the failure of the excitation circuit according to claim 3.

8. A method for detecting the failure of an excitation circuit of a polyphase alternator controlled by a regulator said method comprising the following steps:

e) continuously taking electrical information (Iexc;

Von) other than a phase signal from said excitation circuit;

f) continuously comparing said electrical information taken in step a) with a predetermined threshold value (Iref, Vref);

g) continuously determining a logic state (LT) according to the result of the comparison made in step b); and

h) signalling an electrical continuity fault of said excitation circuit if said logic state (LT) determined in step c) persists for a time at least equal to a predetermined delay time (6);

said electrical information taken being a breakdown voltage (Von) of a switching transistor (2) of said excitation circuit and said threshold value being a predetermined reference voltage (Vref).

9. A device for detecting the failure of an excitation circuit of a polyphase alternator suited to the implementation of the method according to claim 8, said excitation circuit comprising a switching transistor (2) mounted in series with a field winding (1) of said alternator at the terminals of a supply voltage source (UB), said device including:

a voltage comparator (15);

a first input of said voltage comparator (15) being connected to a first terminal common to said field winding (1) and to said switching transistor (2); and

a second input of said voltage comparator (15) being connected by means of a reference voltage source (16) to a second terminal common to said switching transistor (2) and to said supply voltage (UB);

an output of said voltage comparator (15) being connected to a gate (6, 7) for generating said logic state (LT).