5-25
5-4 Regenerative Resistor Setting
COMMON PARAMETER SETTING
- SV Series User’s Manual -
● When the servo amplifier has a built-in regenerative resistor (750W or more)
When operation of acceleration -> deceleration is performed in an operation period in which speed (min-1) varies
according to 0 -> max. speed -> 0 sequence, permissible frequency of regenerative operation is 15 per minute.
Please perform conversion when speed and ratio of load inertia moment are used, in order to determine whether an
external regenerative resistor is required.
Permissible frequency of regenerative operation can be calculated using the following formula.
Permissible frequency = permissible frequency of individual servo motor/(1+n) x (max. speed/used speed)
2
[times/min]
n :( = J
L
/ J
M
) [kg·m
2
]
J
M
: Rotor inertia moment of servo motor [kg·m
2
]
J
L
: Ratio of load inertia moment converted base on motor axis [kg·m
2
]
■
Calculate required capacity of regenerative resistor based on regenerative energy
When operation of acceleration -> deceleration in the operation period shown below is perfomred, capacity of the
regenerative resistor can be calculated as follows.
*"0.2" in the formula for W
K
is the value when load ratio of the regenerative resistor is 20%.
Unit for each symbol is shown as follows.
E
S
to E
K
: engery /Joule [J]
W
K
: Required capacity of regenerative resistor [W]
J :(= J
M
+J
L
) [kg·m
2
]
n
M
: Speed of servo motor [min
-1
]
T
L
: Load torque [N·m]
t
D
: Deceleration stop time [s]
T : Cycle operation period of servo motor [s]
In the above calculation, if the value of W
K
does not exceed the power that can be handled by built-in regenerative
resistor of the servo amplifier, an external regenerative resistor is not required. If it exceeds the power that can be
Load moment of inertia = 0 (Single motor)
Speed command
Servo motor
rotation speed
Servo motor
occurring torque
(Operation period)
Allowable frequency = 1/T [times/minute]
t
t
Max. rotation speed
Max. torque
Max. torque
Operation condition for regenerative allowable frequency calculation
ˌ
ˌ
ˌ
Regenerative status
T
Step
Calculating item
Symbol
Formula for calculation
1 Calculate the rotating energy of servo system E
S
E
S
= J x n
M
2
/182
2
Calculate consumption energy lost in load
system during deceleration
E
L
E
L
= (π/ 60) n
M
x T
L
x t
D
3
Calculate the energy loss of servo motor
winding resistance
E
M
(Value calculated from the chart for energy loss of the servo
motor winding resistance) x t
D
4
Calculate the energy that can be absorbed by
regenerative resistor
E
C
The value calculated from the chart for the energy that can be
absorbed by the servo amplifier
5
Calculate the energy consumed by regenerative resistor
E
K
E
K
= E
S
－ (E
L
+ E
M
+ E
C
)
6
Calculate the required capacity (W) of regenerative resistor
W
K
W
K
= E
K
/ (0.2 x T)
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