Parker GVM Series, Technical Manual

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–
18-06-08 PVD3668_GB_GVM_June_2018
3.2.2. Time constants of the motor
3.2.2.1. Electric time constant:
ph ph
ph ph
elec
R
L
_
_


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 GVM210-400-DPW
L
ph_ph
= 0.316 mH or 3.16E-4 H
R
ph_ph
at 25°C = 0.15 Ohm


elec
= 3.16E-4/0.015 = 21 ms
An overall summary of motor time constants is given later.
3.2.2.2. Mechanical time constant:
3
* )
3
* 3 (
* * 5 . 0
*
*
_ _
_
_
_
ph ph ph ph
ph ph
n ph
n ph
mech
Ke Ke
J R
Ke Kt
J R
 

2
_
_
) (
* * 5 . 0
ph ph
ph ph
mech
Ke
J R


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 phase 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
] 1000 / [
_
] / / [
_

rpm V
ph ph
s rad V
ph ph
rms
rms
Ke
Ke

Example:
Motor series GVM210-400-DPW
R
ph_ph
at 25°C = 0.015 Ohm
J = 0.07 kgm²
Ke
ph_ph
[V
rms
/
1000rpm
] = 76.9 [V
rms
/
1000rpm
]

Ke
ph_ph
[V
rms/rad/s
] = 76.9/(2*

*1000/60) = 0.734 [V
rms/rad/s
]


mech
=0.5*0.015*0.07/(0.734²) = 0.97 ms
Remarks: