Main Motor Drive - Toshiba 1550 Service Manual

6.4 Main Motor
6.4.1

Main motor drive

LGC
Wave
rectification
Crystal
Reference frequency
oscillator
(F-MTR-REF)
PLL-OK
MAIN-CW/CCW
Control
MTR-BRK
signal
MAINMTR-ON
(1) LGC outputs a control signal for main motor rotation. (MAIN-CW/CCW: Rotation direction, MAIN-
MTR-ON: Motor rotation command)
(2) The excitation phase switching section excites each phase of the main motor
(3) Hall elements A-C detects rotation position of motor (rotor).
(4) The excitation phase switching section switches the excitation of each phase.
(By repeating (2) through (4), the motor continues to turn.)
(5) An FG pulse is generated by FG pattern attached to the main motor.
(6) The FG pulse and the reference frequency are compared for their phase and speed, and their
differences added to IC3.
(7) Change the switch timing of the excitation phase switching section, according to the signal obtained
at (6) above.
= Control so that the FG pulse and reference frequency are equal
speed (lock-range condition).
(8) As the main motor goes into the lock-range condition, the excitation phase switching section out-
puts a PLL-OK signal to LGC ("L" level).
(9) When MTR-BRK from LGC goes to "L" level, the brake is applied to rotation of the main motor, and
when the MAIN MTR-ON signal becomes "L" level, the main motor stops.
1550/1560 DRIVE
Difference
Phase
comparison
Voltage
detection
Speed
circuit
comparison
Difference
Rotation
control
Lock
protection
circuit
6 - 10
+24V
Excitation
phase
Phase W
switching
+
section
Hall element A
Rotor
position
detection
FG pulse
Phase V
Hall
element B
Phase U
Hall element C
Main motor (M1)
main motor rotates.
main motor rotates at a fixed
Mar. 1998 © TOSHIBA