System for compensating for an output latency in a speed sensor
A speed sensor device includes sensing elements to sense an angle of a moving target and to generate sine and cosine signals in response thereto; a signal condition circuit to process the sine and cosine signals, the processed sine and cosine signals having a phase lag introduced by the signal condition circuit; and a phase lead filter to receive the processed sine and cosine signals and to reduce the phase lag in the processed sine and cosine signals.
1 . A sensor device comprising:
sensing elements to sense an angle of a moving target and to generate sine and cosine signals in response thereto;
a signal condition circuit to process the sine and cosine signals, the processed sine and cosine signals having a phase lag introduced by the signal condition circuit; and
a phase lead filter to receive the processed sine and cosine signals and to reduce the phase lag in the processed sine and cosine signals,
wherein the phase lead filter reduces the phase lag in the processed sine and cosine signals only at frequencies between a first threshold frequency corresponding to a lowest speed of the moving target and a second threshold frequency corresponding to a highest speed of the moving target.
2 . The sensor device as claimed in claim 1 , wherein the phase lead filter reduces the phase lag in the processed sine and cosine signals at frequencies greater than a first threshold frequency, the first threshold frequency corresponding to a lowest speed of the moving target.
3 . The sensor as claimed in claim 2 , wherein the phase lead filter reduces the phase lag in the processed sine and cosine signals at frequencies less than a second threshold frequency, the second threshold frequency corresponding to a highest speed of the moving target.
4 . The sensor device as claimed in claim 1 , wherein the phase lead filter reduces the phase lag in the processed sine and cosine signals at frequencies less than a second threshold frequency corresponding to a highest speed of the moving target and greater than a first threshold frequency corresponding to a lowest speed of the moving target.
5 . The sensor device as claimed in claim 1 , wherein the phase lead filter has a zero followed by a pole.
6 . The sensor device as claimed in claim 5 , wherein the phase lead filter is defined in an analog domain by H(S)=(1+S/Z0)/(1+S/P0), wherein H(S) defines the analog domain of the phase lead filter, S is a complex function in the frequency domain, Z0 represents a zero frequency and P0 represents a pole frequency.
7 . The sensor device as claimed in claim 1 , wherein the signal condition circuit includes amplifiers.
8 . The sensor device as claimed in claim 1 , wherein the sensing elements comprise magnetic field sensing elements to sense the angle of the moving target.
9 . The sensor device as claimed in claim 1 , wherein the signal condition circuit and the phase lead filter are located on a single IC package.
10 . The sensor device as claimed in claim 1 , wherein the signal condition circuit and the phase lead filter are not co-located on a single IC package.
11 . A sensor device comprising:
sensing elements to sense an angle of a moving target and to generate sine and cosine signals in response thereto;
a signal condition circuit to process the sine and cosine signals, the processed sine and cosine signals having a phase lag introduced by the signal condition circuit; and
a phase lead filter to receive the processed sine and cosine signals and to reduce the phase lag in the processed sine and cosine signals,
wherein the phase lead filter reduces the phase lag in the processed sine and cosine signals at frequencies less than or equal to a second threshold frequency corresponding to a highest speed of the moving target and greater than or equal to a first threshold frequency corresponding to a lowest speed of the moving target.
12 . A sensor device comprising:
sensing elements to sense an angle of a moving target and to generate sine and cosine signals in response thereto;
a signal condition circuit to process the sine and cosine signals, the processed sine and cosine signals having a phase lag introduced by the signal condition circuit; and
a phase lead filter to receive the processed sine and cosine signals and to reduce the phase lag in the processed sine and cosine signals,
wherein the phase lead filter has a zero followed by a pole,
wherein the phase lead filter is defined in an analog domain by H(S)=(1+S/Z0)/(1+S/P0).
wherein the phase lead filter is defined in a digital domain by:
H
2
(
s
)
=
1
+
k
0
(
1
-
z
-
1
)
1
+
z
-
1
1
+
k
p
(
1
-
z
-
1
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1
+
z
-
1
=
1
+
z
-
1
+
k
0
(
1
-
z
-
1
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1
+
z
-
1
1
+
z
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1
+
k
p
(
1
-
z
-
1
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1
+
z
-
1
=
(
1
+
k
0
)
+
z
-
1
(
1
-
k
0
)
(
1
+
k
p
)
+
z
-
1
(
1
-
k
p
)
wherein z −1 is a unit delay, T S is a sampling time,
k
0
=
2
z
0
T
S
and
k
p
=
2
p
0
T
S
,
z 0 is a zero frequency and p 0 is a pole frequency.
13 . A method comprising:
(a) generating a sine signal and a cosine signal corresponding to a sensed angle of a moving target;
(b) processing the sine and cosine signals, the processed sine and cosine signals having a phase lag introduced by the processing thereof; and
(c) introducing a phase lead to the processed sine and cosine signals to reduce the phase lag in the processed sine and cosine signals,
wherein the (c) reduces the phase lag in the processed sine and cosine signals at frequencies less than or equal to a second threshold frequency corresponding to a highest speed of the moving target and greater than or equal to a first threshold frequency corresponding to a lowest speed of the moving target.
14 . The method as claimed in claim 13 , wherein the (c) reduces the phase lag in the processed sine and cosine signals using a phase lead filter having a zero followed by a pole.
15 . The method as claimed in claim 13 , wherein the (a) generates a sine signal and a cosine signal corresponding to an angle, sensed by magnetic field sensing elements, of a rotating target.
16 . The method as claimed in claim 14 , wherein the phase lead filter is defined in an analog domain by H(S)=(1S/Z0)/(1+S/P0), wherein H(S) deines the analog domain of the phase lead filer, S is a complex function in the frequency domain, Z0 represents a zero frequency and P0 represents a pole frequency.
17 . A method comprising:
(a) generating a sine signal and a cosine signal corresponding to a sensed angle of a moving target;
(b) processing the sine and cosine signals, the processed sine and cosine signals having a phase lag introduced by the processing thereof; and
(c) introducing a phase lead to the processed sine and cosine signals to reduce the phase lag in the processed sine and cosine signals,
wherein the (c) reduces the phase lag in the processed sine and cosine signals using a phase lead filter having a zero followed by a pole,
wherein the phase lead filter is defined in an analog domain by H(S)=(1+S/Z0)/(1+S/P0), and
wherein the phase lead filter is defined in a digital domain by:
H
2
(
s
)
=
1
+
k
0
(
1
-
z
-
1
)
1
+
z
-
1
1
+
k
p
(
1
-
z
-
1
)
1
+
z
-
1
=
1
+
z
-
1
+
k
0
(
1
-
z
-
1
)
1
+
z
-
1
1
+
z
-
1
+
k
p
(
1
-
z
-
1
)
1
+
z
-
1
=
(
1
+
k
0
)
+
z
-
1
(
1
-
k
0
)
(
1
+
k
p
)
+
z
-
1
(
1
-
k
p
)
wherein z −1 is a unit delay, T S is a sampling time,
k
0
=
2
z
0
T
S
and
k
p
=
2
p
0
T
S
,
z 0 is a zero frequency p 0 is a pole frequency.