Fundamental Principles And System Description; Operating Principle Of Sinamics Converters; General Operating Principle; Pulse Modulation Method - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description

Engineering Information
1 Fundamental Principles and System Description

1.1 Operating principle of SINAMICS converters

1.1.1

General operating principle

The converters in the SINAMICS product range are PWM converters with a voltage-source DC link. At the input side,
the converter consists of a rectifier (shown in the schematic sketch as a thyristor rectifier) which is supplied with a
constant voltage V and a constant frequency f
Line
voltage V , i.e. the DC link voltage, which is smoothed by the DC link capacitors. The 2-level IGBT inverter on
DCLink
the output side converts the DC link voltage to a three-phase system with a variable voltage V
frequency f . This process operates according to the principle of pulse-width modulation PWM. By varying the
Motor
voltage and the frequency, it is possible to vary the speed of the connected three-phase motor continuously and
virtually without losses.
Block diagram of a PWM converter with voltage-source DC link
1.1.2

Pulse modulation method

The power semiconductors of the IGBT inverter (IGBT = Insulated Gate Bipolar Transistor) are high-speed, electronic
switches which connect the converter outputs to the positive or negative pole of the DC link voltage. The duration of
the gating signals in the individual inverter phases and the magnitude of the DC link voltage thus clearly determine
the output voltage and therefore also the voltage at the connected motor.
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Ó Siemens AG
from a three-phase supply. The rectifier produces a constant DC
Line
and variable
Motor