Power supply and method for controlling a power supply

A power supply comprising:

• a transformer comprising a primary intended to be connected to a voltage source and having a leakage inductor, the transformer configured to be traversed by a magnetizing current;
• a magnetizing current regulation circuit configured to switch between:
• a magnetizing state in which the regulation circuit allows the magnetizing current to increase, and
• a demagnetizing state in which the regulation circuit reduces the magnetizing current;
• a device for controlling the regulation circuit and to switch the regulation circuit alternately from the magnetizing state to the demagnetizing state for respectively alternating a magnetization phase and a demagnetization phase, the control device being also configured to prolong the magnetization phase for a magnetization time;
• and
• an output capacitor connected to a secondary of the transformer to form a resonant circuit with the leakage inductor, the voltage between the terminals of the output capacitor corresponding to the output voltage of the power supply,
• the magnetization time and the value of the output capacitor are such that on a resonance portion of the magnetization phase, the output voltage describes a sine wave portion and, starting from an initial value below a median value of the sine wave, passes through said median value.