Sinamics Infeeds And Their Properties; Basic Infeed - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description
Engineering Information

1.6 SINAMICS Infeeds and their properties

SINAMICS Infeeds generate a DC voltage (DC link voltage V
system. This DC voltage is smoothed by DC link capacitors. The Infeeds are integral components of the SINAMICS
G130, G150 and S150 converter units and are available as stand-alone components for of the SINAMICS S120
modular drive system. In the latter case, they are available in Chassis or Cabinet Modules format for two-quadrant
operation (Basic Infeed) or four-quadrant operation (Smart Infeed und Active Infeed).
1.6.1

Basic Infeed

The Basic Infeed is a robust, unregulated Infeed for two-quadrant operation (i.e. the energy always flows from the
supply system to the DC link). This Infeed is not designed to regenerate energy from the DC link back to the supply
system. If regenerative energy is produced for brief periods by the drive, e.g. during braking, it must be converted to
heat by a Braking Module connected to the DC link combined with a braking resistor.
The Basic Infeed consists of a line-commutated, 6-pulse, three-phase rectifier equipped with thyristors or diodes. A
line reactor with a relative short-circuit voltage of 2 % is generally connected on the line side. Further details can be
found in the section "Line reactors" and in the chapters on specific unit types.
The Basic Infeed is an integral component of the power sections of SINAMICS G130 chassis units (with thyristors)
and SINAMICS G150 cabinet units (with thyristors up to outputs of ≤ 2150 kW and with diodes for higher outputs).
The Basic Infeed is also available as a separate Infeed in the modular SINAMICS S120 system in Chassis and
Cabinet Modules format (thyristors at lower outputs and diodes at 900 kW / 400 V and 1500 kW / 500 V-690 V).
SINAMICS S120 Basic Infeed comprising a Basic Line Module with thyristors and a line reactor with v
The Basic Infeed is a line-commutated rectifier which, from the three-phase line voltage V
unregulated, load-dependent DC link voltage V
line voltage value, i.e. V
DCLink
DC link voltage will be V
DCLink
As the DC link voltage is unregulated, line voltage fluctuations cause the DC link voltage to fluctuate correspondingly.
The processes for precharging the connected DC link are very different depending on the device variant used:
In the case of SINAMICS G130 and G150 converters in which the Basic Infeed is an integral component of their
power units, a small precharging rectifier equipped with diodes is connected in parallel with the main rectifier
equipped with thyristors (Exceptions: G150 parallel connections in the output power range from 1750 kW to 2700 kW.
For further information about these units, please refer to chapter "Converter Cabinet Units SINAMICS G150"). If this
arrangement is applied to the voltage at the line side, the DC link is charged by means of the precharging rectifier
and the associated precharging resistors. During this time, the main rectifier is disabled (i.e. the thyristors are not
controlled). As soon as the DC link is charged, the thyristors in the main rectifier are controlled in such a way that
they are triggered at the earliest possible moment. As a result, the thyristor rectifier essentially behaves during
operation in the same way as a diode rectifier. The operational current flows almost entirely via the main rectifier
since it encounters much less resistance than via the parallel-connected precharging rectifier and its precharging
resistors.
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. Under no-load conditions, the DC link is charged to the peak
DCLink
= 1.41 • V When loaded the DC link voltage decreases. When partially loaded the
Line.
≈ 1.35 • V and at full load,
Line
V ≈ 1.32 • V
DCLink
) from the line voltage of the 3-phase AC supply
DCLink
Line.
= 2%
k
produces an
Line,