Switched mode power converters (switched mode power supplies, SMPS) are widely used for power conversion in automotive, industrial, or consumer electronic applications. A flyback converter is a specific type of switched mode voltage converter which includes a transformer with a primary winding and a secondary winding that have opposite winding senses. A first electronic switch is connected in series with the primary winding on a primary side of the power converter, and a rectifier circuit is coupled to the secondary winding on a secondary side of the power converter. The transformer is magnetized when the electronic switch is closed and demagnetized when the electronic switch is opened. Magnetizing the transformer includes storing energy in the transformer, and demagnetizing the transformer includes transferring the stored energy to the secondary winding, the rectifier circuit and a load coupled to the rectifier circuit.
The rectifier circuit may include an active rectifier element, which is often referred to as synchronous rectifier (SR). This active rectifier element includes a second electronic switch which switches on when a voltage across the electronic switch has a first polarity and switches off when the voltage has a second polarity opposite the first polarity. The rectifier circuit may further include a capacitor. Switching on the first electronic on the primary side and the second electronic switch on the secondary side may cause the capacitor to be rapidly discharged, which is highly undesirable as this may damage the power converter.