| 摘要 |
1509452 Frequency changing SIEMENS AG 17 March 1975 [29 March 1974 22 Jan 1975 3 March 1975] 50187/77 Divided out of 1509451 Heading H2F Each of a combination of an odd number m of frequency changers or inverters, connected in an m-phase star, is controlled by a trapezoidal voltage waveform obtained by three alternative methods. In Fig. 1 (not shown) the trapezoidal voltages are derived by adding third (and possibly ninth) harmonics to three-phase sinusoidal voltages. In Fig. 2 (not shown) automatic gain controlled limiters are used. Figs. 3 and 5 (not shown) relate to arrangements of limiters, multipliers and a square rooter for producing the three-phase trapezoidal voltages. |
