| 摘要 |
PURPOSE:To suppress torque ripple easily by feeding back positive and negative voltages of a DC voltage source and varying the amplification factor at the amplifying section in a carrier generating section, separately up and down, in proportion to respective voltages. CONSTITUTION:A DC voltage source 1 rectifies 2, 3 a commercial AC voltage and smooths 4, 5 thus providing positive and negative potentials, with respect to a reference potential terminal 6, to terminals 7, 8. The positive and negative potentials are individually detected 26, 27 and amplified at first and second carrier output correcting sections 28, 29 then they are inputted to a carrier generating section 21 in order to amplify the triangular wave ted from a triangular wave generating section 22. A microcomputor 30 generates a sine wave reference wave having frequency being set 19 according to the desired number of revolution of a two-phase induction motor. A comparing section 24 produces a logical product of a modulated wave of the triangular wave and the sine wave thus producing a PWM control signal which is then provided through an inverter section 25 to the transistors 10-13 in the inverter in order to turn ON/OFF the transistors 10-13 and to produce a desired frequency. |
