Method and system for detecting fault of parallel coil type permanent magnet motor
Disclosed are a method and system for detecting a fault of a parallel coil type permanent magnet motor. This method includes driving a parallel coil type motor on the basis of a pre-defined current reference value, detecting a phase current vector of the motor, and calculating a current compensation value for removing a negative sequence component of the motor on the basis of the phase current vector.
1. A system for detecting a fault of a parallel coil type permanent magnet motor, the system comprising:
a parallel coil type motor;
a current sensor configured to detect a phase current of the motor;
a compensation current calculator configured to calculate a current compensation value for a negative sequence component generated in the motor on the basis of a current vector detected by the current sensor;
a positive sequence current controller configured to generate a control signal for an inverter control by using the current compensation value and also using a current reference value provided from a control system;
a negative sequence current controller configured to generate a signal for removing the negative sequence component by using both the current compensation value and the current reference value, and then to provide the signal to the positive sequence current controller;
an inverter configured to generate a motor operation signal according to the control signal;
a fault detector configured to detect a faulty phase and a degree of a fault by using the output of the negative sequence current controller and a fault model considering both flux variation in a specific slot of a specific phase of the motor having a fault and induced flux variations in other slots of the same phase; and
the control system configured to provide the current reference value to which the faulty phase and the degree of fault have been applied.
2. The system of claim 1 , wherein the compensation current calculator is further configured to convert a 3-phase current into a 2-phase synchronous reference frame, and then to calculate a voltage compensation value for compensating for a negative sequence component.
3. The system of claim 1 , wherein a resistance component R p of the fault model is
R
p
=
[
x
PR
2
+
R
f
0
0
0
-
R
f
0
PR
P
-
2
0
0
0
0
0
R
0
0
0
0
0
R
0
-
R
f
0
0
0
(
1
-
x
)
PR
2
+
R
f
]
,
and inductance L p of the fault model is
L
p
=
[
P
2
L
m
1
-
γ
x
2
+
P
2
x
2
L
l
-
x
γ
P
P
-
2
L
m
1
-
γ
-
xL
m
2
-
xL
m
2
P
2
L
m
1
-
γ
x
(
1
-
x
)
+
P
2
x
(
1
-
x
)
L
l
-
x
γ
P
L
m
1
-
γ
P
-
2
PL
m
P
-
2
(
1
+
2
γ
(
1
-
γ
)
(
P
-
2
)
)
+
P
P
-
2
L
l
-
L
m
2
-
L
m
2
-
(
1
-
x
)
γ
P
2
L
m
1
-
γ
P
/
2
-
1
-
xL
m
2
-
L
m
2
L
m
-
L
m
2
-
(
1
-
x
)
L
m
2
-
xL
m
2
-
L
m
2
-
L
m
2
L
m
-
(
1
-
x
)
L
m
2
P
2
L
m
1
-
γ
x
(
1
-
x
)
+
P
2
x
(
1
-
x
)
L
l
-
(
1
-
x
)
γ
P
P
-
2
L
m
1
-
γ
-
(
1
-
x
)
L
m
2
-
(
1
-
x
)
L
m
2
P
2
L
m
1
-
γ
(
1
-
x
)
2
+
P
2
(
1
-
x
)
2
L
l
]
wherein P is a pole number, P/2 is a pole pair number, L m and L l respectively denote self inductance and leakage inductance of each phase when the motor is in a normal state, R is a phase resistance component, x is a ratio of a coil having no fault to a faulty pole, γ is a coupling factor of remaining pole pairs equal to a specific phase in a slot of the specific phase, and R f is a contact resistance component.
4. The system of claim 3 , wherein the fault detector is further configured to filter the output of the negative sequence current controller and to calculate the faulty phase and the degree of fault by using a voltage value based on the filtered signal and the fault model.
5. The system of claim 4 , wherein a fault current i f caused by inter-turn short circuit is i f =β 1 sin θ+β 2 cos θ,
wherein
β
1
=
(
c
-
a
ω
2
)
(
g
2
-
e
2
ω
2
)
+
b
ω
2
(
f
2
-
d
2
2
ω
)
(
c
-
a
ω
2
)
2
+
(
b
ω
)
2
and
β
2
=
(
c
-
a
ω
2
)
(
f
2
-
d
2
2
ω
)
ω
-
b
ω
(
g
2
-
e
2
ω
2
)
(
c
-
a
ω
2
)
2
+
(
b
ω
)
2
,
wherein
a
=
(
L
p
55
(
L
p
11
-
2
L
p
21
+
L
p
22
)
-
(
L
p
15
-
L
p
25
)
(
L
p
51
-
L
p
52
)
)
b
=
(
R
p
55
(
L
p
11
-
2
L
p
21
+
L
p
22
)
+
L
p
55
(
R
p
11
+
R
p
22
)
-
R
p
51
(
L
p
15
-
L
p
25
)
+
R
p
15
(
L
p
51
-
L
p
52
)
)
c
=
R
p
55
(
R
p
11
+
R
p
22
)
+
R
p
15
2
d
1
=
(
L
p
55
(
-
L
p
12
+
L
p
22
)
+
L
p
52
(
L
p
15
-
L
p
25
)
)
I
d
ω
e
1
=
[
(
-
R
p
55
L
p
12
+
R
p
55
L
p
22
+
L
p
55
R
p
22
-
R
p
15
L
p
52
)
I
d
ω
+
(
L
p
55
(
-
L
p
13
+
L
p
23
+
L
p
12
-
L
p
22
)
+
(
L
p
15
-
L
p
25
)
(
L
p
53
-
L
p
52
)
I
q
)
]
f
1
=
[
(
R
p
55
(
-
L
p
13
+
L
p
23
+
L
p
12
-
L
p
22
)
-
L
p
55
R
p
22
+
R
p
15
(
L
p
52
-
L
p
53
)
)
I
q
+
[
L
p
55
ω
(
L
p
23
-
L
p
13
)
+
R
p
55
R
p
22
1
ω
+
(
L
p
15
-
L
p
25
)
L
p
53
ω
]
I
d
+
(
L
p
55
+
L
p
15
-
L
p
25
)
ωΨ
m
(
x
-
1
)
]
g
1
=
(
R
p
55
ω
(
L
p
23
-
L
p
13
)
-
R
p
15
L
p
53
ω
)
I
d
-
R
p
55
R
p
22
I
q
+
(
R
p
55
-
R
p
15
)
ωΨ
m
(
x
-
1
)
d
2
=
(
(
-
a
12
+
a
22
)
a
51
+
(
a
11
-
a
12
)
a
52
)
I
d
ω
e
2
=
[
(
(
-
a
12
+
a
22
)
b
51
+
b
22
a
51
+
a
52
b
11
)
I
d
ω
+
(
(
-
a
13
+
a
23
+
a
12
-
a
22
)
a
51
-
(
-
a
13
+
a
23
-
a
12
+
a
11
)
a
52
-
a
53
(
-
a
11
+
2
a
21
-
a
22
)
)
I
q
]
f
2
=
[
(
b
51
b
22
1
ω
+
ω
(
a
23
-
a
13
)
(
a
51
-
a
52
)
-
a
53
ω
(
(
-
a
11
+
2
a
21
-
a
22
)
)
I
d
+
(
b
51
(
-
a
13
+
a
23
+
a
12
-
a
22
)
+
(
-
a
51
+
a
53
)
b
22
+
(
a
53
-
a
52
)
b
11
)
I
q
+
(
a
51
-
a
52
+
a
11
-
2
a
21
+
a
22
)
ω
Ψ
m
(
x
-
1
)
g
2
=
(
ω
(
a
23
-
a
13
)
b
51
+
a
53
ω
(
b
11
+
b
22
)
)
I
d
+
(
-
b
22
b
51
)
I
q
+
(
b
51
+
b
11
+
b
22
)
ωΨ
m
(
x
-
1
)
wherein the voltage value is
[
vd
-
vq
-
]
=
1
3
[
(
I
d
(
R
22
-
R
p
33
)
+
I
q
(
-
ω
L
p
22
+
2
ω
L
p
23
-
2
ω
L
p
34
+
ω
L
p
33
)
+
α
1
(
ω
L
p
21
-
ω
L
p
22
-
ω
L
p
31
+
ω
L
p
32
)
+
α
2
(
-
R
p
22
)
+
β
1
(
ω
L
p
25
-
ω
L
p
35
)
)
(
I
d
(
-
ω
L
p
22
+
2
ω
L
p
23
-
ω
L
p
34
1
2
+
ω
L
p
33
)
+
I
q
(
-
R
p
22
+
R
p
33
)
+
α
1
(
-
R
p
22
)
+
α
2
(
-
ω
L
p
21
+
ω
L
p
22
+
ω
L
p
31
-
ω
L
p
32
)
+
β
2
(
-
ω
L
p
25
+
ω
L
p
35
)
)
]
.
6. A method for detecting a fault of a parallel coil type permanent magnet motor, the method comprising the steps of:
driving a parallel coil type motor on the basis of a pre-defined current reference value;
detecting a phase current vector of the motor;
calculating a current compensation value for removing a negative sequence component of the motor on the basis of the phase current vector;
providing the current compensation value to a negative sequence current controller;
calculating a faulty phase and a degree of fault of the parallel coil type motor by using the output of the negative sequence current controller and a fault model considering both flux variation in a specific slot of a specific phase of the parallel coil type motor and induced flux variations in other slots of the same phase when the parallel coil type motor has a fault; and
applying a current reference value to which the calculated faulty phase and degree of fault have been applied.
7. The method of claim 6 , wherein the step of calculating the faulty phase and degree of fault is performed on the basis of a voltage value obtained by filtering the output of the negative sequence current controller using a low pass filter.
8. The method of claim 7 , wherein the step of applying the current reference value includes restricting generation of overcurrent by controlling a velocity and phase current of the motor on the basis of the faulty phase and degree of fault.