| 摘要 |
PROBLEM TO BE SOLVED: To increase the precision of current balance compensation operation by making a minimum current value calculated from the current values of individual inverters connected in parallel a reference value, comparing this with the current value of each inverter, and shortening the width of a firing pulse for an inverter having a larger current value. SOLUTION: A DC power source 1 is converted into an AC power source by inverters 10, 20 connected in parallel, and the power converting switching elements of each inverters 10, 20 operate simultaneously by firing pulses outputted by a common drive apparatus 3, when an induction motor 2 is driven. Here, current detectors 11, 21 monitor the output currents of individual inverters 10, 20, and a minimum value calculator 5 calculates the minimum value of individual output currents. Then each drive signal controlling quantity computing apparatuses 12, 22 computes a control quantity of a firing pulse width for shortening the firing pulse width of an inverter 10 (or 20) whose output current value current value is larger than this minimum value, and each firing pulse controllers 13, 23 arbitrarily controls the pulse width of a common firing pulse and makes each output current balanced by this firing pulse width controlling quantity. |
