HEIDENHAIN iTNC 530 HSCI - Series Reactor

1012 HEIDENHAIN Technical Manual iTNC 530 HSCI
Series reactor Reasons for using a series reactor:
Asynchronous motor
 Minimum leakage inductance of drive
The total leakage inductance L
Total
of the drive is formed from the leakage
inductance of the motor L
LeakMotor
and the inductance of the series reactor
L
Reactor
L
Total
=L
LeakMotor
+L
Reactor
with:
• XStr1: Stator leakage reactance (see XStr1 in motor.mot) [mΩ]
• XStr2: Rotor leakage reactance (see XStr2 in motor.mot) [mΩ]
• fN: Rated frequency of the motor (see F-N in motor.mot) [Hz]
•L
LeakMotor
: Leakage inductance of the motor [µH]
The total leakage inductance L
Total
must not fall below a specified minimum
value. This also depends on the PWM frequency fPWM, the magnetizing
current I0 of the motor, and the DC-link voltage UZ, and is calculated as
follows:
For I0 < 26 A:
For I0 ≥ 26 A:
•L
Total
: Total leakage inductance of the drive [µH]
This way the value for the series reactor can be determined as:
LReactor = LTotal - LLeakMotor
If the result is a negative value, HEIDENHAIN does not require the use of a
series reactor. It is possible, however, that there are other reasons for using a
series reactor, such as the motor manufacturer's specifications.
 Impermissible temperature of the bearings
High harmonic losses in the rotor lead to excessively high bearing
temperatures. One possible remedy, besides increasing the PWM frequency,
is the use of a series reactor. Here there is no universally valid formula.
The amount of inductance results from the measurement of the bearing
temperature.
 Limitation of dU/dt
Because of the strain placed on the motor insulation, the motor manufacturer
can prescribe the use of a series reactor. The strain placed on the motor
insulation results from the voltage build-up dU/dt at the inverter output.
For HEIDENHAIN inverters the voltage build-up is dU/dt = 6000 V/µs.
L
LeakMotor
X
Str1
X
Str2
+()1000
⋅
2 π f
N
⋅⋅
---------------------------------------------------------------
=
L
Total
700 µH 5000 Hz U
Z
⋅⋅
f
PWM
600⋅
---------------------------------------------------------
=
L
Total
700 µH 5000 Hz U
Z
26 A⋅⋅⋅
600 I
0
f⋅⋅
PWM
--------------------------------------------------------------------------
=