| 摘要 |
<P>PROBLEM TO BE SOLVED: To protect a converter circuit when an asymmetric phase voltage occurs in an AC voltage network connected to the converter circuit. <P>SOLUTION: The converter circuit has a converter unit 1, equipped with a plurality of controllable power semiconductor switches, and the converter unit 1 is connected on an AC-voltage side, to an AC-voltage network 2 and is controlled by a control signal S. For protecting the converter circuit, when an asymmetric phase voltage occurs in the AC-voltage network connected to the converter circuit, phase voltages (U<SB>Na</SB>, U<SB>Nb</SB>, U<SB>Nc</SB>) in the AC-voltage network are calculated. Negative sequence strength of the phase voltage is calculated, and Park and Clark transformation strength of phase voltage is calculated; and when the negative sequence strength of the phase voltage exceeds a value that can be set; or if the Park and Clark transformation strength of the phase voltage drops beyond the value that can be set, the controllable power semiconductor switch will be locked by a control signal. <P>COPYRIGHT: (C)2008,JPO&INPIT |
