| 摘要 |
PURPOSE: A lamp ballast with a SEPIC converter is provided to make use of the advantages of the SEPIC converter in an inexpensive way by using an inexpensive micro-controller. CONSTITUTION: An electronic ballast is arranged to operate at the main voltage, and contains an input stage(P). The input stage is designed as a SEPIC converter, and operated in the mode with a discontinuous current profile. A micro-controller(UC) having control intervals of at least as long as 1% of the period of the main frequency, is adopted to control the input stage. The micro-controller samples the output voltage of the input stage from the potential DC and transmits, to a control electrode(G1) of a switch(S1), a signal with a duty ratio that leads to a desired setpoint value for the DC voltage at the potential DC. The potential DC is sampled by the microcontroller at sampling intervals which are at least as long as 1% of the period of the main frequency. Therefore, the control intervals are also at least as long as 1% of the period of the main frequency. |
