Servotronix CDHD Series - Regenerat Ion Resist or Prot Ect Ion

CDHD Drive Setup
User Manual 121
V
NOM
= 220 Vrm s = 340 VDC
Tim e bet ween decelerat ion = 5 s
Tim e of De ce ler a t ion Calculat ion
t
d
=
J
Mot or
+ J
Load
∙
(
ω
M
)
(T
M
+ T
f
)
=
(0.0006562+ 0.0015) ( 261)
(16 .08+ 2.5)
= 0.03 s
Current During Decele r at ion Calculat ion
I
M
=
J
Mot or
+ J
Load

k
t
∙
ω
1
-ω
2
t
d
=
0.0006562+ 0.0015
1.042
∙
261
0.03
= 18 A
Ener gy Calculation
E
dec
=
1
2
(J
M
+ J
L
)(ω
1
2
-ω
2
2
) =
1
2
(0.0006562+ 0.0015 )(261
2
-0) = 73.44 J
E
motor
= 3I
M
2
∙ (R
M
/ 2) ∙ t
d
= 3 ∙ 18
2
∙
󰇡
1.32
2
󰇢
∙ 0.03 = 19.24 J
E
friction
=
1
2
T
f
(
ω
1
-ω
2
)
t
d
=
1
2
∙ 2.5 ∙ (261 - 0) ∙ 0.03 = 9.78 J
E
M
= E
dec
-E
motor
-E
friction
= 73.44-19.24-9.78 = 44.42 J
E
BUS
=
1
2
C

V
M
2
-V
NOM
2

=
1
2
∙ 0.001120(420
2
-340
2
) = 34.05 J
Since E

> E

, a regeneration resistor is required.
Resist or Specifica t ion Calculat ion
V
B
= K
B
N-

3
I
M
󰇧
R
M
2
󰇨
= 0.0812 2500-

3
18 
󰇧
1.32
2
󰇨
= 182.423 V
R
MAX
=
V
M
2
V
B
I
M

3
=
420
2
182.423 18 

3
= 31.02 Ω
P
AV
=
E
M
-
1
2
C

V
High
2
-V
Low
2

t
cycle
=
44.42-
1
2
0.001120 
󰇡
400
2
-380
2
󰇢
5.03
= 7.1 W
P
PK
=
V
M
2
R
Regen
=
420
2
1.32
= 5686.65 W
5 .9 .3 Rege neration Resistor Prot ect ion
Regene rat ion Resistor Overload Pr ote ction Over view
The regeneration resistor circuitry itself requires overload protection t o ensure
the resistor functions reliably.
The CDHDhas configurable parameters for the protection of the regeneration
resistor. To apply this protection, set the paramet ers as described in t he
following sections.
Use the regenera t ion re sistor protection w it h ca ut ion.
If the motor increases bus voltage, resulting in activation of the protection
m echanism , an over-voltage condition may result.