Download IPS110 Intelligent Minidrive - User Manual

In order to avoid this situation add a capacitor on the motor supply big enough to absorb the
overall energy flowing back to the supply. The capacitor must be rated to a voltage equal or
bigger than the maximum expected over-voltage and can be sized with the formula:
C≥
2 × EM
2
2
UMAX
− UNOM
where:
UMAX - is the over-voltage protection limit expressed in [V]. You can read this value in the
“Drive Info” dialogue, which can be opened from the “Drive Setup”.
UNOM - is nominal motor supply voltage expressed in [V]. You can read this value in the
“Drive Info” dialogue, which can be opened from the “Drive Setup”.
EM - the overall energy flowing back to the supply in Joules. In case of a rotary motor
and load,
EM can be computed with the formula:
EM =
1
2 R t − t dϖ M T
(JM + JL )ϖM + (mM + mL )g(hinitial - h final ) − 3IM
Ph d
F
2
2
Kinetic energy
Potential energy
Copper losses
Friction losses
where:
JM – total rotor inertia [kgm2]
JL – total load inertia as seen at motor shaft after transmission [kgm2]
ϖM – motor angular speed before deceleration [rad/s]
mM – motor mass [kg] – when motor is moving in a non-horizontal plane
mL – load mass [kg] – when load is moving in a non-horizontal plane
g – gravitational acceleration i.e. 9.8 [m/s2]
hinitial – initial system altitude [m]
hfinal – final system altitude [m]
IM – motor current during deceleration [ARMS/phase]
RPh – motor phase resistance [Ω]
td – time to decelerate [s]
TF – total friction torque as seen at motor shaft [Nm] – includes load and transmission
© Technosoft 2008
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IPS110 Technical Reference