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Operating Manual dryve D1, ST-, DC-, EC/BLDC-Motor Control System - V2.4
5.4.8.2 Braking Resistor dimensioning for custom motors
The Braking Resistor value and power rating are determined according to the following formulas.
NOTE
The minimal resistance with 48 V at X1.1 is
1,7 Ω and 0,8 Ω with 24 V.
If a lower resistance is used the error E02
“Motor Overcurrent” will be executed right after DI 7 “Enable“ is set.
Resistance
Basic value to determine the Braking Resistor
𝑃
𝑚𝑎𝑥 𝑏𝑟𝑎𝑘𝑒
=
𝑛
𝑚𝑎𝑥
∗ 𝑀
𝑚𝑎𝑥
9,55
P
max brake
Maximal produced motor braking power in watt [W]
ɳ
max
Maximal motor speed in revolutions per minute [min
-1
]
(dependent on Load Voltage at X1.1)
M
max
Maximal motor torque (M
peak
) in newton meter [Nm]
9,55
Constant to determine the mechanical power from corresponding numerical value equation divided by 1000
Example:
𝑃
𝑀𝑜𝑡𝑜𝑟 𝑚𝑎𝑥
=
3000 min
−1
∗ 3 𝑁𝑚
9,55
= 942,4 𝑊
Determination Resistance Value
𝑅
𝐵𝑟𝑎𝑘𝑒
=
𝑈
𝐵𝑟𝑎𝑘𝑒 𝑉𝑜𝑙𝑡𝑎𝑔𝑒
²
𝑃
max 𝑏𝑟𝑎𝑘𝑒
R
Brake
Optimal Brake Resistor value in O
hm [Ω]
U
Brake Voltage
Braking Voltage threshold to activate the Braking Resistor in volt [V]
– see
Braking Voltage Setting (S.41)
P
Motor max
Maximal produced motor braking power in watt [W]
Example:
𝑅
𝐵𝑟𝑎𝑘𝑒
=
51 𝑉
2
942,4 𝑊
= 2,76 𝛺
In case of a result not fitting to a standard value
it’s recommended to use the very next smaller or bigger resistance with the
smallest value delta. With a result of
2,76 Ω the next smaller and bigger available standard values are 2,7 Ω and 3,3 Ω. In this
case the recommended value is
2,7 Ω.
Power
Basic value to determine the needed power dissipation (if not mentioned in data sheet)
𝑃
𝑛𝑜𝑚 𝑏𝑟𝑎𝑘𝑒
=
𝑛
𝑚𝑎𝑥
∗ 𝑀
𝑛𝑜𝑚
9,55
P
nom brake
Nominal produced motor braking power in watt [W]
(typically identical to nominal motor power)
ɳ
max
Maximal motor speed in revolutions per minute [min
-1
]
(dependent on Load Voltage at X1.1))
M
nom
Nominal motor torque (M
rated
) in newton meter [Nm]
9,55
Constant to determine the mechanical power from corresponding numerical value equation divided by 1000
Example:
𝑃
𝑛𝑜𝑚 𝑏𝑟𝑎𝑘𝑒
=
3000 min
−1
∗ 1 𝑁𝑚
9,55
= 314,1 𝑊
