JVL MAC050 User Manual page 95

3.2
3.2.5 Estimating the peak current from the supply.
The peak current drawn from the DC power supply is dependant on the following pa-
rameters:
- Maximum motor speed.
- Maximum load torque.
- Supply voltage used.
The calculation is done as follows:
Conditions (example)
Maximum speed = 2500 RPM = 262 Radians/sec.
Maximum torque= 0.9 Nm (peak torque) @ MAC140 is used with 300% (full torque)
Supply voltage = 24VDC nominal
Worst case efficiency of the MAC50-141 motors = 0.8 (80%)
Power calculation:
Power = (speed x torque)/efficiency = (262 x 0.9)/0.8 = 295W
Current calculation:
Current at peak torque = power / supply voltage = 295/24 = 12.3Amp.
Please note that the peak current is only at maximum during for example an acceleration
or deceleration. The peak current can be reduced if the "Torque" setting is lowered. The
peak current will decrease proportionally with the Torque setting.
Example: Half torque = half peak current.
The below curve shows how the power and current are behaving as a function of the
motor speed during acceleration, constant speed and deceleration.
Speed
(RPM)
4000
3000
2000
1000
0
Lower current and power since only
friction exist at constant speed
When decreasing speed - power (energy)
will be returned to the supply and cause
a negative current flowing in the supply line.
JVL A/S - User Manual - Integrated Servo Motors MAC050 - 4500
Power Supply
Current and power rises to max
during acceleration. The inertia in
the system need to get up in speed.
Average supply power
Only MAC050 to 141
Supply Supply
Current Power
(A) (W)
+15 +300
+10 +200
+5 +100
0 0 Time
-100
-5
-10 -200
-15 -300
TT1276-02GB
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