| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce the harmonic wave leakage current to the ground wire of a rotary machine by suppressing approaching of the carrier frequency of an inverter main circuit to the resonance frequency of the stray capacitance of the rotary machine. <P>SOLUTION: In the inverter unit for controlling the drive of the rotary machine, the resonance frequency f<SB>0</SB>of the stray capacitance Cs between the input terminal of the machine and a frame arm is measured in advance. A switching frequency setting algorithm of Fig. 3 is provided in the inverter unit. When the carrier frequency f<SB>c</SB>of an inverter is set, if a set value priority is not selected, the decision result of the setting priority ? (S2) becomes 'no', deciding of f<SB>0</SB>/√2 ≤ set value ≤√2f<SB>0</SB>(S4) is conducted. If its result is 'yes', the deciding of the set value < f<SB>0</SB>(S5) is conducted. In the case of 'yes', the frequency f<SB>c</SB>is shifted sufficiently low to the frequency f<SB>0</SB>√2 than the frequency f<SB>0</SB>. If the result is 'no', the frequency f<SB>c</SB>is shifted sufficiently high to the frequency √2f<SB>0</SB>than the frequency f<SB>0</SB>, and the harmonic wave leakage current flowing to the ground wire is suppressed. <P>COPYRIGHT: (C)2004,JPO |
