4.7 Servo Control
C141-E203-01EN 4-19
(3) Stable rotation mode
The SVC calculates a time for one revolution of the spindle motor based on the
PHASE signal. The MPU takes a difference between the current time and a time
for one revolution at 4,200 rpm that the MPU already recognized. Then, the MPU
keeps the rotational speed to 4,200 rpm by charging or discharging the charge
pump for the different time. For example, when the actual rotational speed is
4,000 rpm, the time for one revolution is 15.000 ms. And the time for one
revolution at 4,200 rpm is 14.286 ms. Therefore, the MPU charges the charge
pump for 0.714 ms
×
k (k: constant value). This makes the flowed current into
the motor higher and the rotational speed up. When the actual rotational speed is
faster than 4,200 rpm, the MPU discharges the pump the other way. This control
(charging/discharging) is performed every 1 revolution.
Summary of Contents for MHT2040BH
Page 1: ...C141 E203 01EN MHT2080BH MHT2060BH MHT2040BH DISK DRIVES PRODUCT MANUAL ...
Page 4: ...This page is intentionally left blank ...
Page 8: ...This page is intentionally left blank ...
Page 10: ...This page is intentionally left blank ...
Page 12: ...This page is intentionally left blank ...
Page 38: ...This page is intentionally left blank ...
Page 42: ...This page is intentionally left blank ...
Page 54: ...This page is intentionally left blank ...
Page 74: ...This page is intentionally left blank ...
Page 246: ...This page is intentionally left blank ...
Page 250: ...This page is intentionally left blank ...
Page 260: ...This page is intentionally left blank ...
Page 262: ...This page is intentionally left blank ...
Page 263: ......
Page 264: ......