EL DC Instalation and operation manual v13.docx
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this means that there is no voltage in the DC link and no voltage/current is applied to the output
of the converter.
The transition from the Standby state is the Enable signal or, in case of errors, a Fault signal. The
Enable signal will bring the State Machine to Precharge and eventually to the Ready state. If an
error is detected the converter will go into Alarm state.
4.2.3. Precharge
The Precharge is an internal transition state between Standby and Ready. During this state the
DC link is gradually charged through resistors until the rated DC link voltage is reached. The
transition will finish successfully as long as, in less than 10 seconds of precharge, the DC link has
reached the specified voltage. Otherwise, the next state will be Alarm.
The Precharge state is only applicable to the grid side converter.
4.2.4. Ready
In the Ready state the converter is ready to operate but no PWM signal is sent to IGBTs. The DC
link is charged to the rectified voltage and there is no voltage/current applied to the outputs.
The transition from Ready state can be the Run signal, the Not enable signal or, in case of errors,
a Fault signal. When a Run signal is received the State Machine will evolve to the Run state.
When a Not enable signal is received the State Machine puts the converter on standby, thus
discharging the DC link capacitors. If a fault is detected the converter goes to Alarm state.
Only on the Ready state the user can change the operation mode between (CC, CI, CP or CV).
4.2.5. Run
In this state, the converter is completely operational. Due to the converter architecture, the grid
side converter (Active Rectifier) will make the transition first while stabilizes the DC link voltage.
After that, the three-phase inverter of the EL will measure the actual EUT voltage levels and will
synchronize with them. Finally, the inverter will start the control algorithms and PWM.
This state can evolve to Standby state when a Not enable signal is received, to Ready state when
a Not run signal is received or to Alarm state if an error condition is detected.
Please, note that, while the EL is in Run state, it is not possible to change the working mode. For
doing this change the state machine to the corresponding mode.
4.2.6. Alarm
In this state, the converter is stopped and kept in a safe condition: the DC link is discharged and
the PWM signals are stopped.
The Alarm state can be reached by any fault detected during the normal operation of the
converter, for instance, an emergency stop activation (see Alarms chapter for further detail).
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