TOYODenki VFDB2009 Series, Operation Manual

Page: 33 / 54

32
＝
η
π
π




















＝
π π






















＝
[ ]
From expression (2), braking torque
τ
[N m]required for a slowdown is,
τ ＝
π

＝
π


＝
[N m]
From expression (4), braking torque tauB [N
・
m] required for an inverter is,
τ ＝ τ τ ＝ ＝
[N
・
m]
From expression (5), the instantaneous maximum regeneration power PB [W] at the time of a
slowdown start is,
＝ τ
π
 
＝
π
 
＝
[W]
From expression(6), resistance RDB [
Ω
] of the braking resistor to select,
≦
 
＝
 
＝
[
Ω
]
Since it becomes the above, two-piece series connection is actually selected for resistance of
resistance 15 [
Ω
].
From expression(7), average power PDBR [W] consumed by the selected braking resistor is,
[ ]
＝ ＝ ＝
[W]
Since it becomes the above, the resistance (at this example computation, it is about 400-800 [W]
grade by the two braking resistor sum total) in consideration of a rise in heat of rated apparent power
is selected.
The dosis tplarate of the transistor built in DBunit
From expression (8), when the transistor built in DBunit is set to ON, current IDB[A] which flows into a
transistor becomes below.
[A]
＝
) (
＝

＝
[A]
From figure 5.2, since the permissible current value at the time of the total braking time t= 3 [sec] is
50 [A] in VFDB2009-50, it can check that it is satisfactory by IDB=26.7 [A].
From expression (9), effective alternating current I
DB
(rms)[A] of the whole in consideration of the
period of OFF of the transistor which DB unit builds in is as follows.
( ｍ )
[A]
＝

) (
＝


＝
[A]
From figure 5.2, since a D.C. continuation permissible current value is 12 [A] in VFDB2009-50, it can
check that it is satisfactory by IDB(rms) [A] =1.9 [A].
A set of power generation brake system selected from above and is as follows.
DB unit
：
VFDB2009-50 1 set