Schaltung zur stufenlosen direkten oder indirekten Variation des durch einen von einer Netz-Gleich- oder -Wechselspannung oder einer beliebigen Kombination derselben betriebenen Verbraucher fließenden Gleich- und/oder Wechselstroms

摘要

The circuit connects the supply network to the load (10) and contains a low pass filter (12) which achieves a continuous input current, and a coil (14) in series with or part of the load. A first a.c. switch (16) is in parallel with the load and coil, and a second a.c. switch (32) is driven at a frequency higher than the supply frequency and connected in series with the load. A controller (34) detects the a.c. or d.c. load current directly or indirectly, has an input for a desired a.c. or d.c. load current and drives the second switch with a suitable switching frequency and duty cycle to achieve the desired load current.