Discharging the DC link

The following application example describes the discharging of the DC link using the StorageDischarger operating mode.

WARNING

Electric shock from a DC link capacity or energy storage unit that has not been fully discharged.
Severe or fatal injuries.
  • Check whether there is any residual voltage and, if necessary, completely discharge the DC link capacity or the energy storage unit as described in the relevant documentation.
  • Observe the safety notes and the documentation of the energy storage unit in use.
Preparation

If a fault message is present, the operating mode cannot be executed.

Possible causes for a fault message in the operating mode:

  • The MDP92A power supply module signals a fault.
  • The connected braking resistor signals a fault via DI 03 (not connected correctly or already too hot).
  • The connected braking resistor has not been configured or has not been configured correctly in MOVISUITE® (e.g. resistance value ≤ 0 Ω or continuous power ≤ 0 kW)
  • The parameters of the braking resistor do not allow for discharging, for example because the continuous power is very low, the voltage is very high, and the resistance value is very small. This would overload the resistor.

 

In this case, identify the cause of the fault and rectify it. Afterwards, set thexReset variable to "TRUE" to reset the fault status. (Also possible in the case of device faults)

Discharge
  • No fault message is present.
  1. To select the StorageDischarger operating mode, set the uiRequestedMode variable to 510" (StorageDischarger) in the IN structure under ModeControl.
  2. Enter a target voltage for the discharge of the DC link via rVoltageSetpoint in the IN structure under ModeStorageDischarge.
  3. Set the xStart variable in the IN structure under ModeStorageDischarge to "TRUE".
    • If the current voltage in the DC link is at least 5 V above the setpoint voltage, the discharging of the DC link is started. To stop discharging, set the xStart variable to "FALSE".
  • If the target voltage was not reached, the xDischargeComplete variable displays the value "TRUE".
  • To restart discharging, the xStart variable must first be set to "FALSE" and then back to "TRUE".