| 摘要 |
<p>PURPOSE:To prevent a main circuit from being interrupted unnecessarily by stopping the operation of a phase current unbalance detector when the current flow rate of either of the choppers is minimum or maximum. CONSTITUTION:An operational amplifier 21 inputs a deviation 105 between the average value 103 of currents 101, 102 flowed to main smoothing reactors of choppers and a command pattern 104 of a motor current, and outputs current flow rate commands 106, 107 of the choppers. The commands 106, 107 are added to the difference of the currents 101, 102 outputted from adders B, D to become current flow rate command 110, 111. A comparator 24 outputs a signal 113 to a main circuit interrupter when the output 109 of the adder C becomes higher than the set value. A current flow rate detector 25 detects that either of the choppers is minimum current flow rate or maximum current flow rate, turns a switch 26 OFF and opens the output circuit of the comparator 24.</p> |
