Control for a series resonant power converter

摘要

A series resonant power supply for supplying regulated power to an output from an unregulated input voltage. The power supply includes a control circuit. The control circuit causes the on device to be turned off when the resonant current amplitude becomes essentially zero. The control circuit includes a circuit which prevents the turning off of the on device for a predetermined period of time after it has been turned on, even if the resonant current amplitude goes to zero. The control circuit also includes a circuit for determining when any one of a number of undesirable conditions occurs in the input voltage and a further circuit which prevents the turning on of an off device based on load requirements when an undesirable condition has been detected. The control circuit also includes another circuit which causes the power supply to operate at a frequency dependent on load when the load is relatively heavy and at a second much lower frequency when the load is relatively light.