Calculate the return energy for each deceleration
)ω - )(ωJ+ (J
2
1
= E
2
2
2
1LMdec
Where:
Edec= Energy returned during deceleration (J or ft·lb)
JM= Rotor inertia (kg·m2 or lb·ft·sec2)
JL = Load inertia (kg·m2 or lb·ft·sec2)
ω1 = Velocity at the beginning of deceleration (rad/s)
ω2 = Velocity at the end of deceleration (rad/s)
Determine the energy consumed by the motor
As the current passes through the motor winding resistance, part of the energy is
dissipated by the motor:
d
t /2)
M
(R
2
M
3l =
motor
E
Where:
Emotor = Energy consumed by motor (J)
RM = Motor resistance (ΩL-L)
IM = Current during deceleration (ARMS/phase)
td = Deceleration time (s)
Determine the energy consumed by the friction
d21ffriction
)tω - (ω T
2
1
= E
Where:
Efriction = Energy consumed by friction (J or ft·lb)
Tf = Friction torque (N·m or lb·ft)
ω1 = Velocity at the beginning of deceleration (rad/s)
ω2 = Velocity at the end of deceleration (rad/s)
td = Deceleration time (s)
Determine the energy consumed by the amplifier
frictionmotordec
E- E- E = E
M
Where:
EM = Total energy consumed by the amplifier (J or ft·lb)
If the energy is less than the energy that the bus module can store, the regenerative
resistor is not needed.
EM should be expressed in joule. The conversion rate from ft·lb to joule is:
1ft·lb=1.356J
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