| 摘要 |
PURPOSE:To efficiently control an accurate torque of an induction motor type electric rolling stock by calculating an exciting current according to a measured motor current, and controlling the modulation factor of an inverter in response to a deviation between the exciting current and a specified pattern. CONSTITUTION:Power from a DC power source 1 is converted by a PWM inverter 2 into 3-phase alternating currents of a VVVF, which are supplied to induction motors 31, 32. The rotating frequency fr of the motor 32 is detected, a slip frequency fS calculated by a lip frequency calculator 14 is added to the detected frequency, and applied as a frequency command fI to a PWM modulator 5. An exciting current pattern generator 17 generates an exciting current patterns IOP according to a notch command. An exciting current calculator 18 inputs a detected motor current IM and a slip frequency calculated value fS' and calculates an exciting current I0. A difference DELTAI0 between the pattern IOP and the current I0 is input to a modulation factor calculator, which obtains a modulation factor gamma and applies it as a command value to a PWM modulator 7.
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