| 摘要 |
PURPOSE:To improve the responsiveness of a current by decreasing a carrrier frequency in a range of a small current command to reduce the insensitive band of a current. CONSTITUTION:A triangular carrier signal generator of PWM inverter has a triangular signal generator having a comparator 21, an operational amplifier 22, resistors 27, 28 and a capacitor 29, and a window comparator having comparators 24, 25, an inverter 26 and an analog switch 23 (parallel with a resistor 27) are added thereto. Thus, when a current command Ia falls within a preset range of -DELTAV<Ia<DELTA V, the output of the window comparator becomes a low level and the output of the inverter 26 becomes a high level to turn ON the switch 23, thereby shortcircuiting the resistor 27. Thus, the period of the output (carrier signal) of the amplifier 22 increases (becomes a low frequency), thereby reducing the insensitive band of the current controlled in the pulse width. |
