伺服產品
/Servo Products
–
Hardware Manual of 380V 7.5kW Servo Drive II (SPD-32C1-075)
Wiring and Signal (SPD-32C1-075)
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45
Resistor Type
Wirewound
Ripple
Aaluminum-Housed
Characteristics
Heat Dissipation
Poor
Average
Excellent
Operating Power Range
Large (30~20000W)
Large (30~20000W)
Small (40~2000W)
Operating Resistance Range
2~1000
Ω
2~1000
Ω
0.1~10K
Ω
Cost
Low
Average
High
Dimensions
Length X Width X Height
(Unit: mm)
Large
(362 x 70 x 138)
Large
(362 x 70 x 138)
Small
(335 x 76 x 44)
11.6.2
Detailed Selection Guide for Regeneration Resistors
Motors do Negative Work under External Torque Load
Motors generally do positive work while operating, but they may do negative work when the output torque
direction is opposite of the rotation direction. For instance, the motor may output torque to resist the inertia during
braking, or it may experience an external torque load while in torque mode...etc. During those times, the external
force is doing positive work through the motor and transferring that energy to the drive; that is, the motor acts as a
generator. When this happens, the regenerative resistor must quickly dissipate the energy in order to prevent
flooding the DC terminal voltage.
Suppose the external torque load is T
L
and the unit is a percentage of the rated torque (%). The speed at that
instance in time is Wr (rpm). The regenerative resistance power must be greater than the External Torque Power =
T
L
x Rated Torque x (Wr x 2
π
/60).
For example, if the external torque is 50% of rated torque, the speed is 2000 (rpm), and the motor rated torque is
2 (Nm), then the external torque produces a power of 0.5 * 2 * 2000 * 2
π
/ 60
≈
210 W. To be safe, that number is
usually multiplied by a safety factor of around 2 ~ 3, therefore the user needs to select a regenerative resistor of
more than 420W.
Free of External Torque Load
Assuming that the motor moves back and forth, the energy generated by the inertial force during braking will be
poured back into the drive. At this time, the capacitor of the DC bus terminal of the drive is the first buffer to absorb
and reuse the energy. However, the absorption of energy by the capacitor causes the DC bus voltage to rise, so
