Infineon Technologies Austria Ag

Anders Lind

Kennith Kin Leong

Andrey B Malinin

Marc Fahlenkamp

Eric G Persson

Nico Fontana

Sanjaya Pradhan

Circuits and methods are provided for supplying power to a transformer of a switching DC/DC voltage converter within a power converter. The power converter includes separate nodes that can potentially supply such power. A first of these nodes is coupled, typically directly and with no energy-storing bulk capacitor, to a rectifier that supplies rectified power from an alternating current power source. A second node is also supplied power from the rectifier, but is coupled to a bulk capacitor that can store and supply energy as needed. The techniques disclosed herein use the first node to supply power to the transformer when feasible, and use the second node, and its associated bulk capacitor, to supply power otherwise. In so doing, the energy storage requirements of the bulk capacitor may be reduced, meaning that the capacitance and associated size of the bulk capacitor may be reduced relative to other power converter circuits.

Selection control for transformer winding input in a power converter

Power converter with selective transformer winding input

A circuit includes a bridgeless flyback converter having a primary side electromagnetically coupled to a secondary side by a transformer, the primary side being devoid of a diode bridge rectifier, an input capacitor coupled to the primary side of the bridgeless flyback converter, an output capacitor coupled to the secondary side of the bridgeless flyback converter, an EMI (electromagnetic interference) filter coupled between an AC input and the input capacitor, and a compensation stage coupled in parallel with the output capacitor and including a storage capacitor. The input capacitor has a capacitance such that the compensation stage filters the AC mains frequency ripple of the AC input from the secondary side. The compensation stage is configured to store energy in the storage capacitor and regulate the voltage across the output capacitor. The bridgeless flyback converter is configured to regulate the voltage across the storage capacitor.

Bridgeless flyback converter circuit and method of operating thereof

In one example, a circuit includes a voltage rail, a reference node, a first capacitor, and a capacitor module. The first capacitor is coupled to the voltage rail and to the reference node. The capacitor module includes a second capacitor and a switching unit. The switching unit is configured to operate in a closed state and an open state. The switching unit couples the second capacitor in parallel with the first capacitor in the closed state. The switching unit decouples the second capacitor from the first capacitor in the open state.

Bulk capacitor switching for power converters

In one example, a circuit includes an alternating current (AC) voltage source, a voltage rail, a reference rail, a first capacitor, a second capacitor, and a switching unit. The AC voltage source is configured to supply voltage in a first direction during a first half of a cycle and supply voltage in a second direction during a second half of the cycle. During a first state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the first capacitor. During a second state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the second capacitor.

Voltage doubler with capacitor module for increasing capacitance

In accordance with an embodiment, a method in a voltage converter includes, in each of successive drive cycles, switching on for an on-period a first electronic switch connected in series with a primary winding of a transformer. Before first electronic switch is switched on, the transformer is pre-magnetized for a pre-magnetizing period, where there is a first delay time between an end of the pre-magnetizing period and a beginning of the on-period.

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San Jose, CA, United States of America

Anders Lind