Control circuit for a switch unit of a clocked power supply circuit, and resonance converter

The resonance converter according to claimed 1, wherein the auxiliary output is designed to provide an auxiliary signal which is essentially proportional to the output voltage,

• which includes a reference value comparator designed to compare the auxiliary signal with a predefined reference value and to detect reference crossing moments at which the auxiliary signal crosses the predefined reference value, and
• a zero crossing detector designed to detect zero crossing moments at which the current flowing through the switch, or the current flowing from the switch unit to the input of the resonant transformer arrangement, comprises zero crossings,
• and wherein the control circuit is designed to determine a phase shift between the reference crossing moments and the zero crossing moments to detect whether at least one reference crossing moment is present within a predefined time interval, so as to set a phase reference as a function of whether at least one reference crossing moment is present in the predefined time interval, and
• to regulate the operating frequency as a function of a difference between the phase shift and the phase reference.

A resonance converter for providing an output voltage or an output current for a load network based on an energy provided by an energy source, the resonance converter comprising:

• a resonant transformer arrangement having an input for receiving an input-side excitation, an output for providing the output voltage or the output current, and an auxiliary output for transformationally providing an auxiliary signal, the amplitude of which is essentially proportional to the output voltage provided by the resonant transformer arrangement, the amplitude of which is essentially proportional to the output current provided by the resonant transformer arrangement, or the amplitude of which is essentially proportional to a load alternating current flowing through a resonant circuit of the resonant transformer arrangement;
• a switch unit designed to generate the input-side excitation of the resonant transformer arrangement from the energy of the energy source;
• and
• a regulator circuit, the regulator circuit comprising a comparator adapted to receive the auxiliary signal, to compare it with a predefined reference value and to provide comparison information indicating whether the auxiliary signal is larger or smaller than the reference value,
• the regulator circuit further including a switching detector designed to detect whether the comparison information changes its state within a predefined time interval, and
• the regulator circuit being designed to change an operating frequency, the period duration of which determines time intervals between turn-on moments or turn-off moments of the switch unit, from a resonant frequency of the resonant transformer arrangement when the detector detects that the comparison information has changed its state within the predefined time interval, and to change the operating frequency toward the resonant frequency when the detector detects that the comparison information has not changed its state within the predefined time interval.

A control circuit for a switch unit of a clocked power supply circuit, the switch unit being designed to effect input-side excitation of a resonant transformer arrangement, the control circuit comprising:

• an input for receiving an auxiliary signal from the resonant transformer arrangement, the auxiliary signal exhibiting an essentially fixed phase relation to a load alternating current flowing through a resonant circuit of the transformer arrangement;
• a phase detector designed to detect reference crossing moments when the auxiliary signal crosses a predefined reference value;
• a driver controllable to switch the switch unit;
• a synchronizer designed to synchronize a turn-on of the switch unit by the driver with regard to a phase position with the auxiliary signal so as to achieve a turn-on of the switch unit within a predetermined time interval around a zero crossing of a voltage present across the switch unit, or of a current flowing through the switch unit,
• the synchronizer being designed to receive information about the reference crossing moments from the phase detector, and to provide a turn-on signal to the driver with a fixed phase delay at the reference crossing moments, so as to define turn-on moments at which the driver is to turn on the switch unit;
• a detector designed to determine an amplitude information which depends on an amplitude or a mean value of the auxiliary signal;
• and
• a regulator designed to change an operating frequency in dependence on the amplitude information supplied by the detector, and to determine a period duration between turn-off moments at which the driver is to turn off the switch unit as a reciprocal of the operating frequency;
• wherein a voltage rectified at the output load and proportional to the output voltage, or a rectified current proportional to the output current is used via a direct current feedback, such as a galvanically separating optocoupler, to provide a reference value, and thus to regulate the output voltage or the output current, present at the output-side resistive load, to have a constant value.