Epson DFX-9000 - Page 90

Epson DFX-9000 Revision B
Operating Principles Circuit operation 83
SP Motor drive circuit
The SP motor is a DC brushless motor. A dedicated brushless motor
control IC is used to control the speed and position. The position of the
SP motor is controlled using encoder pulse counts, and the speed is
controlled using Proportional, Integral, Derivative (PID) and closed-
loop control. The following shows a detailed block diagram and timing
chart of the SP motor drive circuit.
Figure 2-27. SP motor drive circuit block diagram
SP motor control signal definitions
 CR_C[1:3] is a Hall-effect sensor input signal. When the motor is in
an IN+ > IN- state, the signal is high, and the reverse state is low.
 M_CWCCW is a normal/reverse rotation input signal that
determines the direction of the Carrier unit.
 M_STSP is a start/stop control signal. When the signal is low, the
motor starts driving. When the signal is high, the motor stops
driving.
 M_BRAKE is a brake input signal. When the signal is low, the
motor is braked. When the signal is high, the motor rotates normally.
 PWMIN is a pulse input signal (M_TIM1), and its output is
controlled based on the duty levels. When the signal input is low, the
pulse output turns “ON”. When the input is high, the pulse output
turns “OFF”.
 UH, UV, UW are PWM output signals that are controlled based on
the duty levels. UH, UV, UW are normally controlled in a saturated
state.
 RF is an output current detection terminal. The output current is
determined according to the detected resistance (Iout=0.5/Rf).
 PWM frequency is determined according to the capacity of an
external capacitor. It is set to approximately 20 kHz. The frequency
can be determined by calculation using Fpwm=1/(45000*C).
Figure 2-28. Timing Chart
ASIC
Power Unit
M_CWCCW
M_STSP
M_BRAKE
PWMIN
UL
UH
VL
VH
WL
WH
SP MOTOR
Current detection
section
+42V
CR_C[1:3]
(RF)
M_TIM1
SP Motor
Driver
INLK SW ASY
Fuse
(125 V, 8 A)
MOSFET
(U phase)
MOSFET
(V phase)
MOSFET
(W phase)
IN1
IN2
IN3
UH
VH
WH
UL
VL
WL
indicates PWM output.