參數資料
型號: L7250
廠商: STMICROELECTRONICS
元件分類: 運動控制電子
英文描述: VOICE COIL MOTOR CONTROLLER, PQFP64
封裝: TQFP-64
文件頁數: 18/46頁
文件大?。?/td> 478K
代理商: L7250
25/46
L7250
Figure 6. Synchronization to Smooth Drive Commutation
2.7.4 Closed Loop Commutation
During closed loop commutation, the motor is driven following the smooth driver wave shape (or the traditional
six step profile). To keep sync, each electrical cycle a winding of the spindle motor (phase U) is tri-stated, for a
programmable (via SPI) window (W), to sense for the ZC occurrence; to mask the current flyback time a mask-
ing time is applied starting from the opened window for a certain number M of samples (settable via SPI). Due
to the fact that the motor winding is driven in voltage mode a control of the phase shift between the applied volt-
age and the Bemf is required in order to optimize the system efficiency (the loss in efficiency is related to the
cosine of the angle between Bemf and current). Via the SPI it is possible to set an appropriate Torque Optimizer
(TO) value based on the application characteristics (Rm, Lm, Speed).
When a ZC is detected the circuit starts scanning the stored smooth drive wave shape (or the traditional six step
profile) from the number of sample pointed by the TO register; the tri-stated window is opened a certain number
of samples before.
In the following table the relation between the TO register contents and the window and masking time position
and duration:
start
stop
window
TO-W
At ZC detection
mask
TO-W
TO-W+M
Set Load Coarse Phase
Write Reg.07H
LoadCP = 1
(*1)
Wait Loop
(300 usec)
START
Sync. To SmoothDrive Commutation
i=0
Wait Rising Edge
of ZC (pin 22)
EXIT
Sync. To Smooth
Drive Commutation
Set Load Coarse Phase
Write Reg.07H
LoadCP = 1
(*2)
NO
i = 2
YES
NO
YES
Set CLCOAST
Write Reg.03H
Spstate[3:0]=0000
Motor Running in
Sine or Six
Set Closed Loop SINE
Write Reg.03H
Spstate[3:0] =0111
Set Closed Loop SIX
Write Reg.03H
Spstate[3:0] =0110
SINE
SIX
(*5)
(*6)
(*7a)
(*7b)
Time Out
Control
NO
START UP
FAILURE
Exit
YES
Set OLCOAST
Write Reg.03H
Spstate[3:0]=0001
Wait Loop
(30 usec)
ZC_SamplingRoutine
BEGIN
ZC_SamplingRoutine
END
Reset Time Out
(*3)
(*4)
Inc i
CALL
ZC_SamplingTime
Routine
CALL
ZC_SamplingTime
Routine
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