Dv/Dt Filter Plus Vpl - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description
Engineering Information
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dv/dt filter plus VPL

The dv/dt filter plus VPL (Voltage Peak Limiter) consists of two components, i.e. a dv/dt reactor and a voltage limiting
network.
The dv/dt reactor achieves the same effect as the motor reactor. In combination with the capacitance of the
connected motor cable and the internal capacitance of the limiting network, it forms an oscillating circuit which limits
the voltage rate of rise dv/dt to values of < 500 V/μs independent from the length of the connected motor cable.
The limiting network basically comprises a diode bridge and is connected to the output of the dv/dt reactor and the
inverter DC link. The diode bridge limits the voltage overshoots at the dv/dt reactor output to approximately the level
of the DC link voltage and thus restricts the peak voltage V
gradient, the voltage conditions at the output of the dv/dt filter and the motor terminals are practically identical.
a) without dv/dt filter
Voltage v(t) at the inverter output and motor terminals
dv/dt filters plus VPL very effectively limit both the voltage rate of rise dv/dt and the peak voltage V
winding to the following values:
•
Voltage rate of rise dv/dt < 500 V/μs
•
Voltage peaks V
•
Voltage peaks V
The use of dv/dt filters plus VPL is thus a suitable method of reducing the voltage stress on the motor winding at line
supply voltages of 500 V to 690 V to such an extent that special insulation in the motor can be dispensed with.
Bearing currents are also reduced significantly. Using these filters therefore allows standard motors with standard
insulation and without insulated bearing to be operated on SINAMICS up to line supply voltages of 690 V. This
applies to both Siemens motors and motors supplied by other manufacturers.
SINAMICS Engineering Manual – May 2008
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(typically) < 1000 V
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(typically) < 1250 V
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on the motor cable. Due to the reduced voltage
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b) with dv/dt filter plus VPL
for V < 575 V
Line
for 660 V < V < 690 V
Line
on the motor
PP