TOYODenki VFDB2009 Series, Руководство по эксплуатации

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Figure 6.3 VFDB2009-200 Short-time current characteristic
6.2 Selection of braking resistor
Braking resistor is selected from the calculation result of the maximum braking power. The maximum
braking power shows the maximum regeneration energy which can be processed by current of DB unit and
Braking resistor, and required braking power is calculated from load torque and motor speed.
When the braking operation is done with the inverter, it is regenerated to the inverter, the machine energy.
When the object of the moment of inertia that rotates with rotational speed N1(min -1 ) decelerates to
rotational speed N2(min -1 ) with braking time t(sec), the regeneration energy E(J) and a necessary deceleration
Braking torque
τ
(N
･
m) are shown by the next expression.
Regenation energy
：
[ ]
＝ η
π
π




















(1)
Braking torque
：τ
[
ｍ
]
＝
π

(2)
However, [
ｋｇ ｍ
]
＝
(3)
(GD 2 : Flywheel effect (
㎏ ･㎡
) ,
η
M
: Motor efficiency )
Here, necessary braking torque for inverter
τ
B
(N
･
m) subtracts load torque
τ
L(N
･
m) from braking torque
τ
(N
･
m) necessary for the deceleration and is shown by the next expression.
τ
[
ｍ
]
＝ τ τ ＝ τ
π

(4)
In addition, maximum regenerative power P
B
(W) becomes the next expression momentarily when
beginning to decelerate at this time.
[ ]
＝ τ
π
 
(5)
Next, braking resistance DBR is selected. To do condition DBR such as the maximum regeneration electric
VFDB2009-200N
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
1 10 100 1000 10000
動作時間 T ｓｅｃ
電流 I
D
B
DB使用率= % 自然冷却
DB使用率= % 強制風冷
連続
連続
VFDB2009-200N
VFDB2009-200F
DB use rate = 10%(at natural cooling)
DB use rate = 10%(cooling by fun)
Continues 120A
Continues 58A
D
B
c
u
rr
e
n
t
Braking time