Parker EY Series - Time Constants of the Motor

30 – Pvd3675_Gb_Ey_Septembre_2017
3.2.6. Time constants of the motor
3.2.6.1. Electric time constant :
phph
phph
elec
R
L
_
_
= τ
With following values given in the motor data sheet
L
ph_ph
inductance of the motor phase to phase [H],
R
ph_ph
resistance of the motor phase to phase at 25°C [Ohm].
Example:
Motor series EY630EAK
L
ph_ph
= 7.26 mH or 7.26.10
-3
H
R
ph_ph
at 25°C = 0.674 Ohm
 σ
elec
= 7.26.10
-3
/0.674 = 10.8 ms
An overall summary of motor time constants is given a little further.
3.2.6.2. Mechanical time constant :
3
*)
3
*
3(
**
5
.0
*
*
__
_
_
_
ph
phphph
phph
nph
n
ph
mech
KeKe
JR
KeKt
JR
== τ
2
_
_
)(
**5.0
phph
phph
mech
Ke
JR
=
τ
With following values obtained from the motor data sheet:
R
ph_ph
resistance of the motor phase to phase at 25°C [Ohm],
J inertia of the rotor [kgm²],
Ke
ph_ph
back emf coefficient phase to phase [V
rms
/
rad/s
].
The coefficient Ke
ph_ph
in the formula above is given in [V
rms
/rad/s].
To calculate this coefficient from the datasheet, use the following relation:
60
1000**2
]1-tr.min1000/[
_
]//[
_
π
rms
rms
V
phph
sradV
phph
Ke
Ke
=
Example :
Motor series EY630EAK
R
ph_ph
at 25°C = 0.674 Ohm
J = 147.10
-5
kgm²
Ke
ph_ph
[V
rms
/
1000
. 
−1
] = 73 [V
rms
/
1000
. 
−1
]
 Ke
ph_ph
[V
rms/rad/s
] = 73/(2*π*1000/60) = 0.697 [V
rms/rad/s
]
 σ
mech
=0.5*0.674*147.10
-5
/(0.697²) = 1.02 ms