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Jukka Ylppö

Osmo Pasuri

Kari Turunen

A frequency converter assembly including an input for supplying electric power having an input frequency into the frequency converter assembly from a supply network, a direct voltage intermediate circuit having capacitor component, and at least one controllable switch. The switch being electrically positioned between the input and the direct voltage intermediate circuit. The assembly also includes an output for supplying electric power having an output frequency from the frequency converter assembly, and control component arranged to control the at least one controllable switch. The control component provides a recovery function to recover the capacitor component by supplying restricted recovery current from the supply network to the capacitor component through the at least one controllable switch, the control means also prevents supply of electric power from the direct voltage intermediate circuit towards the output during the recovery function.

Frequency converter assembly

A method in a frequency converter provided with a voltage intermediate circuit in connection with interference in a network () to be supplied and a frequency converter (), which comprises a network converter part () and an inverter part () and a DC intermediate circuit () between them. The method comprises steps of controlling the intermediate circuit voltage at the beginning of network interference by limiting the torque on the inverter side, detecting interference in the network voltage, setting a torque reference to a predetermined value in response to the network interference, detecting network voltage recovery, and controlling the torque reference to a normal value in response to the network voltage recovery.

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Helsinki, Finland

Jukka Ylppö