Selection Criteria - Mitsubishi Electric FR-E700EX Manual

Sensorless PM motors selection example

(1) Selection criteria

Configurations
Sensorless
PM motor
Gear ratio 5 : 8
Motor speed

1 30000
V
0

N = =
0
1/n 16
P
B
 Acceleration/deceleration time constant
t = t = t -
psa psd 0
V
0
settling time. Here it is assumed as 0.15 s.
t :
s
 Operating pattern
Speed
(r/min)
3000
0
0.1
t
psa
t 1.0
0
1 cycle
(2) Selecting rotary motor
 Load torque (converted into the motor shaft)
Travel distance per motor revolution
1
S = 
= 10 (mm)
P
B
n
WgS
T = = 0.23 (N·m)
L


3

2 10
Load moment of inertia (converted into the motor shaft)

Moving part
-3
S10
= W  (
J
L1
2
Ball screw
L
B
 D
J =
L2
32
Gear (motor shaft)
L
G
 D
J =
L3
32
Gear (load shaft)
L
G
 D
J =
L4
32
All load moment of inertia (converted into the motor shaft)
J =J +J +J +J =1.87(10
L L1 L2 L3 L4
15
Feed speed of moving part
Feed length per cycle
Positioning time
V
0
Number of feed times
(Operating cycle
Reduction ratio
Moving part mass
Drive system efficiency
Friction coefficient
Ball screw lead
8

= 3000 (r/min)
5
- t = 0.1(s)
s
/60
0.1 0.15
t t
psd s
t 1.5
f
2
-4 2
) = 1.52 (10
kg·m )
1 2
4  ( -4
) = 0.24 (10
kg·m
B
n
4 -4 2
= 0.03 (10
kg·m )
G1
1 2
4  ( -4
) = 0.08 (10
kg·m
G2
n
-4 2
kg·m )
V = 30000 (mm/min)
0
= 375 (mm)
t = within 1 (s)
0
40 times/min
t = 1.5 (s))
f
1/n = 5/8
W = 60 (kg)
= 0.8
= 0.2
P = 16 (mm)
B
 Select a motor
Selection criteria
Load torque Rated torque of motor
Moment of inertia of all loads J
J : Recommended load to motor inertia ratio
R
Select the following motor to meet the criteria above.
MM-GKR23 (rated torque: 0.64 (N·m), max. torque: 1.3 (N·m),
moment of inertia: 0.19 (10
 Acceleration/deceleration torque
Torque required during acceleration
(J /+J
L
T =
Ma
9.5510
:
J moment of inertia of motor
M
Torque required during deceleration
+J
(J
Time (s)
L
T = -
Md
9.5510
Torque required during acceleration/deceleration must be equal to or lower than the max. torque of
the motor.
 Continuous effective load torque
2
T t
Ma psa
T =
rms
t = t - t - t
c 0 s
Continuous effective load torque must be equal to or lower than the rated torque of the motor.
 The continuous effective load torque for operation of MM-GKR13 at low speed
(750r/min or lower) must be equal to or less than 90% of the rated torque.
 Torque pattern
Torque
(N m)
1.03
2
)
0.23
0
0.1
-0.30
 Result
Based on the above, select the following.
2
)
Sensorless PM motor MM-GKR23
Drive unit FR-E720EX-0.2K
(The software for capacity selection will be provided at free of
charge.)(To be available soon.)
D = ball screw diameter
B
L = ball screw length
B
D = gear diameter
G1
(motor shaft)
D = gear diameter
G2
(load shaft)
L = gear tooth thickness
G
 = density of ball screw
material and gear material
 Moment of inertia of motor
R
-4 2
kg·m ))
)N
M 0
+ T = 1.03 (N·m)
L
4
t
psa
)N
M 0
+ T = -0.30 (N·m)
L
4
t
psd
2 2
+ T t + T t
L c Md psd
= 0.32 (N m)
t
f
- t
psa psd
0.65 0.1 0.15
1.5
20 (mm)
500 (mm)
25 (mm)
40 (mm)
10 (mm)
3
0.0078 (kg/cm )
Time(s)