AC-DC converter

An AC-DC converter comprising

• input terminals which are to be connected to the poles of a supply voltage source supplying an alternating voltage and output terminals,
• rectifier means coupled to the input terminals for rectifying the alternating voltage,
• an inductive element coupled to the rectifier means,
• a buffer capacitance coupled to the output terminals,
• a unidirectional element coupled between the inductive element and the buffer capacitance,
• a switching element coupled to the inductive element for controlling a current through the inductive element,
• a control circuit coupled to a control electrode of the switching element for generating a periodic control signal for rendering the switching element alternately conducting and non-conducting at a frequency f, and provided with
• a first circuit part for setting a first time interval t-on during which the switching element is conducting in each period of the control signal, and
• a second circuit part for setting a second time interval t-off during which the switching element is non-conducting in each period of the control signal, characterized in that the second circuit part comprises a third circuit part for setting the second time interval t-off at a value that is equal to the expression
• C2*(C1*t-on+(1+C1)*t-d),
• wherein t-d is a third time interval during which the unidirectional element is conducting in each period of the control signal, and C1 and C2 are parameters which have a constant value during each half period of the alternating voltage, whereby C2>0, C1=>0 and t-off>t-d.