| 摘要 |
PURPOSE: To drive an induction motor with an optimum admittance constantly and facilitate the high efficiency operation by a method wherein the deviation between an operation admittance and an optimum reference admittance is made to be zero and a voltage adjusting means is compensated in response to voltage ripple after the AC conversion. CONSTITUTION: An optimum reference admittance signal 58a which is outputted from a multiplier 58 is compared with a detected operation admittance signal 44a by a comparator 48 and the deviation between those admittances is integrated by an integrator 50 as a signal Err. The integrated result is supplied to a multiplier 28 as a modulation parameter 50a. The multiplier 28 calculates the product of the modulation parameter 50a and a reference voltage signal VR and the product is outputted as a modulated reference voltage signal VK. The modulated reference voltage signal VK is supplied to a multiplier 32 and a reference voltage signal 26a is modulated. After that, voltage ripple is compensated by the output Er of a DC voltage ripple detector 24. With this constitution, a large capacity smoothing capacitor is not necessary and an input power factor can be improved. |
