Patent ID: 7417408

Claim:
A method for charging capacitors of a direct-voltage intermediate circuit of a frequency converter, the direct-voltage intermediate circuit comprising voltage connections to a voltage supply unit, a charging circuit of the direct-voltage intermediate circuit, comprising a first diode and a second diode connected in series with the first diode and a current-limiting component connected in parallel with the series connection of the diodes, a positive bar and a negative bar of the direct-voltage intermediate circuit, the negative bar being arranged to be divided into a first branch and a second branch between said diodes in such a manner that the cathode of the first diode is connected to the second branch of the negative bar and the anode to the cathode of the second diode and that the anode of the second diode is connected to the negative bar and that the first pole of the current-limiting component is connected in connection with the cathode of the first diode and the second pole in connection with the anode of the second diode, a switch of the charging circuit and a by-pass switch of the charging circuit, the switch of the charging circuit being arranged in the negative bar of the charging circuit between a negative voltage connection and the charging circuit and the first pole of the by-pass switch of the charging circuit being arranged to be connected to the negative bar between the switch of the charging circuit and the negative voltage connection and the second pole of the by-pass switch of the charging circuit being arranged to be connected to the first branch of the negative bar between the charging circuit and the main switches of the capacitors, and capacitors corresponding to inverter parts connectable to the direct-voltage intermediate circuit, the first pole of the capacitors being connected to the positive bar of the direct-voltage intermediate circuit and the second pole being connectable to the first branch of the negative bar by the main switch of the capacitor and to the second branch of the negative bar by the charge switch of the capacitor, the method comprising, during the starting of the direct-voltage intermediate circuit, starting the voltage supply unit, connecting the direct-voltage intermediate circuit to the voltage supply unit, connecting the charging circuit to the voltage supply unit by switching the switch of the charging circuit to a closed position and connecting the capacitors to be charged to the first branch of the negative bar by switching on the main switches of the capacitors to be charged, whereby said capacitors are charged through the main switch of the capacitor, the first diode and the current-limiting component.