Regenerative Energy Absorption; Calculating The Regenerative Energy - Omron R88M-K Series User Manual

4-4 Regenerative Energy Absorption

4-4 Regenerative Energy Absorption

The Servo Drives have internal regeneration process circuitry, which absorbs the regenerative
energy produced during motor deceleration and prevents the DC voltage from increasing. An
overvoltage error occurs, however, if the amount of regenerative energy from the motor is too
large. If this occurs, remedies must be taken to reduce the regenerative energy by changing
operating patterns, or to increase the regeneration process capacity by connecting an External
Regeneration Unit.

Calculating the Regenerative Energy

Horizontal Axis
4
Motor operation
Motor output torque
In the output torque graph, acceleration in the forward direction is shown as positive, and
acceleration in the reverse direction is shown as negative.
The regenerative energy values in each region can be derived from the following equations.
Note: Due to the loss of motor winding resistance and PWM, the actual regenerative energy will be
For
Servo Drive models of 400 W or less), the values Eg
drive's regeneration absorption capacity. (The capacity depends on the model. For details, refer
to the next section.)
For
energy (i.e., Servo Drive models of 500 W or more), the average amount of regeneration Pr (unit:
W) must be calculated, and this value must be lower than the drive's regeneration absorption
capacity. (The capacity depends on the model. For details, refer to the next section.)
4-41
+N
1
N , N : Rotation speed at start of deceleration [r/min]
2
1
Deceleration torque
T , T :
D2
D1
t , t :
Deceleration time
2
1
approx. 90% of the values derived from these equations.
models with internal capacitors used for absorbing regenerative energy (i.e.,
Servo Drive
models with an Internal Regeneration Resistor used for absorbing regenerative
Servo Drive
The average regeneration power (Pr) is the regeneration power produced in 1 cycle of operation [W].
P = ( E + E ) / T[W]
r g 1 g 2
T: Operation cycle [s]
OMNUC G5-series AC Servomotors and Servo Drives User's Manual (with Built-in EtherCAT Communications)
−N
2
T
D1
E E
g1 g1
t
1
T
and Eg
1
T
D2
E E
g2 g2
t
2
[N·m]
[s]
(unit: J) must be lower than the
2