EL DC Instalation and operation manual v13.docx
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The main components of the diagram are the following (from grid side to EUT side):
- Isolation transformer: a 50/60Hz isolation transformer can be provided optionally in
order to isolate the output phases. In this case, an isolation monitor can be integrated
in the converter to detect isolation faults also.
- Input protections: these protections include a thermal-magnetic circuit breaker and
fuses. The connection of the converter input with the grid is done by screw terminals.
Please follow the safety instructions in the Installation section to connect the electronic
load.
- Input EMI filter: an electromagnetic filter is integrated to fulfil electromagnetic
compatibility regulations. The structure of the filter is the same as the one of the output
EMI filter.
- Input LCL filter: the purpose of this filter is to reduce the current distortion at
frequencies equal to or higher than switching frequency and reduce THD.
- Active Rectifier: a three-branch IGBT active front end is integrated in the equipment to
consume/inject a sinusoidal current from/into the grid.
The DC link voltage is set to 800V providing a regulation margin for fast transients at the
output of the electronic load.
The active rectifier has bidirectional power flow capability and the injected reactive
power (grid side) can be defined by the customer.
- DC/AC output converter: it is a three-branch IGBT converter. Its topology is the three
phase inverter and allows the conversion from the DC bus to each of the output AC
phases.
The user can choose between having each phase controlled independently or having the
three of them controlled as a unique phase (sharing the same operation mode and
setpoints).
- Output LCL filter: analogously to the input LCL filter, the filter reduces the current
distortion (caused by switching) at the output of the electronic load.
- Output EMI filter: a high frequency common mode LC filter is used to reduce the
electromagnetic disturbances at the output of the electronic load.
- Output protections: a disconnector is provided to isolate the output from the EUT. Screw
terminals are also integrated to connect the EUT. Please, follow safety instructions in
Installation section to connect them.
2.6. Principle of operation
Below, a technical diagram of the converter is shown:
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