4.2 Block Diagram
14
Block Diagram
Functional Description
The test bench energy systems of the Heinzinger ERS-series are optimized for bidirectional Operation.
They can either operate as power supplies or sinks that can feed energy back into the grid. This means
that from a technical perspective the output and input of the unit can change. For the sake of clarity,
the manual will always refer to the grid side as input and the DC side as output.
The ERS is constituted from the following functional units.
Potential separation:
The potential separation to the grid and between the two input channels is provided by an isolating
transformer with two isolated secondary coils.
Active Front End:
Each of the two Active Front Ends (AFE) consists of a frequency converter operating at 4 kHz
switching frequency. These each generate an intermediate DC voltage circuit of approx. 715 V. While
the AFE supplies the DC intermediate circuit with energy during source operation of the ERS, it
feeds the energy absorbed at the output of the ERS back into the grid via the transformer during
sink operation.
HTS:
A Multi-Parallel Converter (MPC) serves as a step-up/down converter (German:
H
och-/
T
ief-
setz
s
teller, HTS) in the output stage of the ERS. It consists of four IGBT modules, each forming a
synchronous converter. A following choke serves as energy storage. Each of these elements has
the ability to work either as a step-up converter or a step-down converter depending on the direc-
tion of current, enabling the bidirectional operation of the ERS. A synchronous control distributes
the current over the modules, which allows an increased overall performance. To control the set
values of voltage, current and power, the IGBTs are controlled by a control unit with a pulse-white-
modulated (PWM) signal. A choke and capacitors smooth the output current and voltage.
M
a
in
s
3P
/
4
0
0
V
~
5
0
H
z
control
system
communication
GUI
measurement
isolation
transformer
AFE
active front end
MPC
multi parallel converter
600 V
±600 A
600 V
±600 A
2 single
channels
=
=
=
=
~
=
~
=
Fig. 3 Block diagram ERS-BIC (Output voltage and current may vary)