Electronic system with a method of motor spindle bandwidth estimation and calibration thereof
An apparatus includes: a disk; a spindle motor configured to rotate the disk; and control circuitry with a spindle motor control loop, coupled to the spindle motor, the control circuitry configured to: inject a bandwidth test frequency into the spindle motor control loop, measure an open loop gain of the spindle motor control loop, calculate, using coordinate transformations, an estimated loop bandwidth of the spindle motor control loop based at least on one iteration of the bandwidth test frequency injection and the open loop gain measurement, and generate optimum loop parameters of the spindle motor control loop.
1. An apparatus comprising:
a disk;
a spindle motor configured to rotate the disk; and
control circuitry, including a spindle motor control loop and coupled to the spindle motor, configured to:
inject a bandwidth test frequency into the spindle motor control loop,
measure an open loop gain of the spindle motor control loop,
calculate, using coordinate transformations, an estimated loop bandwidth of the spindle motor control loop based at least on one iteration of the bandwidth test frequency injection and the open loop gain measurement, and
generate optimum loop parameters of the spindle motor control loop.
2. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to store the optimum loop parameters in a memory for calibration of and use by the spindle motor control loop.
3. The apparatus as claimed in claim 2 wherein the control circuitry is further configured to store the optimum loop parameters in a non-volatile memory.
4. The apparatus as claimed in claim 3 wherein the control circuitry is further configured to copy the optimum loop parameters to volatile memory from the non-volatile memory during a power up speed regulation phase.
5. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to calculate the estimated loop bandwidth with a linear interpolation formula including linear polynomials of degree 0.
6. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to screen the spindle motor for an out of specification motor torque constant defect.
7. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to converge to the optimum loop parameters within two control circuitry iteration cycles.
8. The apparatus as claimed in claim 1 wherein control circuitry is further configured to dynamically configure a variable passive device of the spindle motor control loop to regulate spindle speed based on the optimum loop parameters.
9. The apparatus as claimed in claim 1 wherein control circuitry is further configured to dynamically configure a variable passive device of the spindle motor control loop to minimize and control disturbance rejection based on the optimum loop parameters.
10. The apparatus as claimed in claim 1 wherein the control circuitry is further configured to calculate the estimated loop bandwidth according to linear interpolation formula:
OLGain
(
B
)
-
OLGain
(
C
)
1
/
Freq
(
B
)
-
1
/
Freq
(
C
)
=
1
-
OLGain
(
C
)
1
/
BW
-
1
/
Freq
(
C
)
wherein:
OLGain(B) represents a measured open loop gain at a frequency Point B corresponding to an injection bandwidth frequency evaluated in the format of 1/Freq(B) hertz;
OLGain(C) represents a measured open loop gain at a frequency Point C corresponding to another injection bandwidth frequency evaluated in the format of 1/Freq(C) hertz; and
1/BW represents the estimated loop bandwidth value inverted determined with linear interpolation.
11. A method of operating an apparatus, the method comprising:
injecting, with control circuitry, a bandwidth test frequency into a spindle motor control loop;
measuring an open loop gain of the spindle motor control loop;
calculating, using coordinate transformations, an estimated loop bandwidth of the spindle motor control loop based at least on one iteration of the bandwidth test frequency injection and the open loop gain measurement; and
generating optimum loop parameters of the spindle motor control loop.
12. The method as claimed in claim 11 further comprising storing the optimum loop parameters in a memory for calibration of and use by the spindle motor control loop.
13. The method as claimed in claim 12 wherein storing the optimum loop parameters comprises storing the optimum loop parameters in a non-volatile memory.
14. The method as claimed in claim 13 further comprising copying the optimum loop parameters to a volatile memory from the non-volatile memory during a power up speed regulation phase.
15. The method as claimed in claim 13 wherein calculating the estimated loop bandwidth comprises calculating the estimated loop bandwidth with a linear interpolation formula having linear polynomials of degree 0.
16. The method as claimed in claim 13 further comprising screening a spindle motor having an out of specification motor torque constant defect.
17. The method as claimed in claim 13 wherein generating the optimum loop parameters further comprises converging to the optimum loop parameters within two control circuitry iteration cycles.
18. The method as claimed in claim 13 further comprising dynamically configuring a variable passive device of the spindle motor control loop to regulate spindle speed based on the optimum loop parameters.
19. The method as claimed in claim 13 further comprising dynamically configuring a variable passive device of the spindle motor control loop to minimize and control disturbance rejection based on the optimum loop parameters.
20. The method as claimed in claim 13 wherein calculating the estimated loop bandwidth comprises calculating the estimated loop bandwidth according to linear interpolation formula:
OLGain
(
B
)
-
OLGain
(
C
)
1
/
Freq
(
B
)
-
1
/
Freq
(
C
)
=
1
-
OLGain
(
C
)
1
/
BW
-
1
/
Freq
(
C
)
wherein:
OLGain(B) represents a measured open loop gain at a frequency Point B corresponding to an injection bandwidth frequency evaluated in the format of 1/Freq(B) hertz;
OLGain(C) represents a measured open loop gain at a frequency Point C corresponding to another injection bandwidth frequency evaluated in the format of 1/Freq(C) hertz; and
1/BW represents the estimated loop bandwidth value inverted determined with linear interpolation.