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9 Power Backup System
MITSUBISHI CNC
9 - 2
9.1 Deceleration and Stop Function at Power Failure
The deceleration and stop function at power failure is a function to safely decelerate the servo axes and the spindle
when a power failure occurs. This function prevents a damage on the machine due to an overrun of the servo axes, and
at the same time, realizes a protection against overvoltage for high-speed IPM spindle motors and high-speed DDMs.
9.1.1 Specifications of Stop Method for Deceleration and Stop Function at Power Failure
System
The power backup system is a system to protect the machine and drive units at a power failure. When it is used, stop
methods during some operations are different from those of when it is not used. See below for the stop methods of
<servo system> and <spindle system> when the power backup system is not used ((1) in the tables) and when it is used
((2) in the tables) depending on what is occurring.
< Servo system >
(Note 1) A deceleration and stop operation is carried out in the case of some MDS-D2/DH2-CV alarms. (ALM66, 68 to 6E,
70, 75)
< Spindle system >
(Note 1) A deceleration and stop operation is carried out in the case of some MDS-D2/DH2-CV alarms. (ALM66, 68 to 6E,
70, 75)
CAUTION
The power backup unit (MDS-D/DH-PFU) and regenerative resistor unit (R-UNIT6,7) options are required when using the
deceleration and stop function at power failure.
What is occurring
Servo power
backup setting
Power failure
NC power
down
External
emergency
stop
MDS-D2/DH2-
CV alarm
MDS-D/DH-
PFU
alarm
(Another
axis) Drive
unit alarm
(Its own axis)
Drive unit
deceleration
and stop
alarm
(Its own axis)
Drive unit
dynamic stop
alarm
(1) No power
backup system
Dynamic stop
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Dynamic stop -
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Dynamic stop
(2) Deceleration
and stop function
at power failure
Deceleration
control + PFU
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control + PFU
regeneration
Dynamic stop
in the case of
some alarms
(Note 1)
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Dynamic stop
What is occurring
Servo power
backup setting
Power failure
NC power
down
External
emergency
stop
MDS-D2/DH2-
CV alarm
MDS-D/DH-
PFU
alarm
(Another
axis) Drive
unit alarm
(Its own axis)
Drive unit
deceleration
and stop
alarm
(Its own axis)
Drive unit
dynamic stop
alarm
(1) No power
backup system
Coast to a
stop
Coast to a
stop
Deceleration
control +
Power
regeneration
Coast to a
stop
-
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Coast to a
stop
(2)-1 Deceleration
and stop function
at power failure
*When using IM or
low-speed IPM
motor
Deceleration
control + PFU
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control + PFU
regeneration
Coast to a
stop in the
case of some
alarms (Note
1)
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Coast to a
stop
(2)-2 Deceleration
and stop function
at power failure
*When using high-
speed IPM motor
Deceleration
control + PFU
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control + PFU
regeneration
Coast to a
stop in the
case of some
alarms (Note
1)
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Deceleration
control +
Power
regeneration
Overvoltage
protection
control
(Coast to a
stop from
deceleration
operation only
during high-
speed
rotation)