| 摘要 |
PURPOSE:To suppress output current, when the set frequency is changed or the load varies abruptly, by selecting a voltage vector closest to a vector in reverse direction from an output current vector when the magnitude of the output current vector exceeds over a limit value and feeding the selected voltage vector to a voltage type inverter. CONSTITUTION:A PWM circuit 1 produces a predetermined switching pattern for driving the semiconductor switching element in an inverter INV and performs such control as matching the output voltage from the inverter INV to a voltage command, and each phase current is detected through a current detector 4. A vector in reverse direction from a current vector (i) is considered when phase-U current, for example, exceeds over a limit value under driving of a motor IM, then a closest voltage vector V4 is selected and a switching pattern is employed. By such arrangement, output current can be limited when the set frequency is modified or when the load varies abruptly. |
