Short circuit detection device for rotating electrical machine
A short circuit detection device for a rotating electrical machine includes: a signal processing device including a signal acquisition unit, a signal decomposing unit, a specific frequency component reducing unit, a signal conversion unit, and a short circuit detection unit; and a magnetic detector placed inside a stator, and detects short circuit of a field winding. The signal decomposing unit decomposes a voltage signal from the signal acquisition unit into a plurality of frequency components having different orders. The specific frequency component reducing unit reduces frequency components for odd-number orders and frequency components for even-number orders higher than a threshold less than a fundamental order of a slot harmonic. The signal conversion unit performs conversion to a voltage signal. The short circuit detection unit generates a difference waveform between voltage signals corresponding to magnetic poles, and detects short circuit of the field winding and a short circuit position thereof.
1. A short circuit detection device for a rotating electrical machine, comprising:
a magnetic detector placed so as to be opposed to a field winding provided to a plurality of slots of a rotor of the rotating electrical machine; and
a signal processing device for processing a signal from the magnetic detector,
the short circuit detection device being configured to detect short circuit of the field winding, wherein
the magnetic detector is placed inside a stator provided with a gap from the rotor, and
the signal processing device includes
a signal acquisition circuitry which acquires a voltage signal which is the signal from the magnetic detector,
a signal decomposing circuitry which decomposes the voltage signal acquired by the signal acquisition circuitry, into a plurality of frequency components having different orders,
a specific frequency component reducing circuitry which reduces, among the plurality of frequency components, a frequency component for an odd-number order and a frequency component for an even-number order higher than a threshold which is set to be an order lower than a fundamental order of a slot harmonic which is a harmonic having a correlation with a pitch of the plurality of slots,
a signal conversion circuitry which converts a plurality of frequency components outputted from the specific frequency component reducing circuitry, to a voltage signal, and
a short circuit detection circuitry which
divides the voltage signal converted by the signal conversion circuitry, into voltage signals for respective circumferential-direction angles around the rotor respectively corresponding to a plurality of magnetic poles of the rotor,
generates a difference waveform between the voltage signals corresponding to adjacent magnetic poles among the plurality of magnetic poles, and
on the basis of a shape of the difference waveform, detects short circuit of the field winding, and estimates a position in a circumferential direction around the rotor where the short circuit has occurred,
wherein the magnetic detector is placed inside a slot of the stator.
2. The short circuit detection device for the rotating electrical machine according to claim 1 , wherein
the magnetic detector is a search coil.
3. The short circuit detection device for the rotating electrical machine according to claim 1 , wherein
the magnetic detector is placed at a radial-direction position between a radial-direction position of a tooth end of the stator and a radial-direction position of a multiphase winding surface inside the stator, and in such a range that a distance from the magnetic detector to the radial-direction position of the tooth end becomes smaller as a maximum magnetic flux density at the tooth end of the stator due to rotation of the rotor becomes greater.
4. The short circuit detection device for the rotating electrical machine according to claim 3 , wherein
the magnetic detector is a search coil.
5. The short circuit detection device for the rotating electrical machine according to claim 3 , wherein
the magnetic detector is placed in such a range that a ratio of a radial-direction distance to a position of the magnetic detector relative to a radial-direction distance to the multiphase winding surface, from the tooth end as a reference of a radial-direction position, is within 0 to 100% and is limited by a function of the maximum magnetic flux density.
6. The short circuit detection device for the rotating electrical machine according to claim 5 , wherein
where the maximum magnetic flux density is denoted by xT, the function is represented by the following expression:
801
×
5.9
(
(
1.5
-
x
)
^
(
5.9
)
)
+
3.6
.
7. The short circuit detection device for the rotating electrical machine according to claim 5 , wherein
the magnetic detector is a search coil.
8. The short circuit detection device for the rotating electrical machine according to claim 5 , wherein
the function is set so that the short circuit of the field winding is not erroneously detected, under a condition until a core of the stator is magnetically saturated.
9. The short circuit detection device for the rotating electrical machine according to claim 8 , wherein
where the maximum magnetic flux density is denoted by xT, the function is represented by the following expression:
801
×
5.9
(
(
1.5
-
x
)
^
(
5.9
)
)
+
3.6
.
10. The short circuit detection device for the rotating electrical machine according to claim 8 , wherein
the magnetic detector is a search coil.
11. A short circuit detection device for the rotating electrical machine comprising:
a magnetic detector placed so as to be opposed to a field winding provided to a plurality of slots of a rotor of the rotating electrical machine; and
a signal processing device for processing a signal from the magnetic detector,
the short circuit detection device being configured to detect short circuit of the field winding, wherein
the magnetic detector is placed inside a stator provided with a gap from the rotor, and
the signal processing device includes
a signal acquisition circuitry which acquires a voltage signal which is the signal from the magnetic detector,
a signal decomposing circuitry which decomposes the voltage signal acquired by the signal acquisition circuitry, into a plurality of frequency components having different orders,
a specific frequency component reducing circuitry which reduces, among the plurality of frequency components, a frequency component for an odd-number order and a frequency component for an even-number order higher than a threshold which is set to be an order lower than a fundamental order of a slot harmonic which is a harmonic having a correlation with a pitch of the plurality of slots,
a signal conversion circuitry which converts a plurality of frequency components outputted from the specific frequency component reducing circuitry, to a voltage signal, and
a short circuit detection circuitry which
divides the voltage signal converted by the signal conversion circuitry, into voltage signals for respective circumferential-direction angles around the rotor respectively corresponding to a plurality of magnetic poles of the rotor,
generates a difference waveform between the voltage signals corresponding to adjacent magnetic poles among the plurality of magnetic poles, and
on the basis of a shape of the difference waveform, detects short circuit of the field winding, and estimates a position in a circumferential direction around the rotor where the short circuit has occurred,
wherein
in the stator, a flow path of cooling air is formed in a radial direction, and
the magnetic detector is placed inside the flow path.
12. The short circuit detection device for the rotating electrical machine according to claim 11 , wherein
the magnetic detector is a search coil.
13. The short circuit detection device for the rotating electrical machine according to claim 11 , wherein
the magnetic detector is placed at a radial-direction position between a radial-direction position of a tooth end of the stator and a radial-direction position of a multiphase winding surface inside the stator, and in such a range that a distance from the magnetic detector to the radial-direction position of the tooth end becomes smaller as a maximum magnetic flux density at the tooth end of the stator due to rotation of the rotor becomes greater.
14. The short circuit detection device for the rotating electrical machine according to claim 13 , wherein
the magnetic detector is a search coil.
15. The short circuit detection device for the rotating electrical machine according to claim 13 , wherein
the magnetic detector is placed in such a range that a ratio of a radial-direction distance to a position of the magnetic detector relative to a radial-direction distance to the multiphase winding surface, from the tooth end as a reference of a radial-direction position, is within 0 to 100% and is limited by a function of the maximum magnetic flux density.
16. The short circuit detection device for the rotating electrical machine according to claim 15 , wherein
where the maximum magnetic flux density is denoted by xT, the function is represented by the following expression:
801
×
5.9
(
(
1.5
-
x
)
^
(
5.9
)
)
+
3.6
.
17. The short circuit detection device for the rotating electrical machine according to claim 15 , wherein
the magnetic detector is a search coil.
18. The short circuit detection device for the rotating electrical machine according to claim 15 , wherein
the function is set so that the short circuit of the field winding is not erroneously detected, under a condition until a core of the stator is magnetically saturated.
19. The short circuit detection device for the rotating electrical machine according to claim 18 , wherein
where the maximum magnetic flux density is denoted by xT, the function is represented by the following expression:
801
×
5.9
(
(
1.5
-
x
)
^
(
5.9
)
)
+
3.6
.
20. The short circuit detection device for the rotating electrical machine according to claim 18 , wherein
the magnetic detector is a search coil.