Power conversion apparatus, discharge lamp ballast and headlight ballast

Power conversion apparatus, comprising:

• a converter circuit comprising a magnetic device for power conversion and a switching device, the converter circuit being configured:
• (a) to supply the magnetic device with an electric current from a power supply to store energy in the magnetic device when the switching device is turned on in accordance with a high frequency signal;
• (b) to discharge the energy stored in the magnetic device when the switching device is turned off in accordance with the high frequency signal;
• (c) and thereby to convert power from the power supply into direct current power;
• and
• a control circuit configured to supply the high frequency signal to the converter circuit,
• wherein the power conversion apparatus further comprises:
• a simulation circuit configured to produce a simulation signal which simulates state or change of magnetic flux of the magnetic device;
• and
• a sense circuit configured to produce a signal which corresponds to one of input or output of the converter circuit and is superposed on the simulation signal to form a superposed signal,
• wherein the control circuit defines an on-period of the high frequency signal based on the superposed signal.