Method and apparatus for adjusting displacement current in an energy transfer element

摘要

A method includes calculating a number of turns of a shield winding included in an energy transfer element of a power supply, where the calculating is to have a low noise current in an input conductor of the power supply. The method further includes: increasing the number of turns for the shield winding; operating the power supply; and adjusting a value of a shield impedance to substantially reduce the noise current. An apparatus includes a power supply having an energy transfer element and a shield impedance. The energy transfer element includes a shield winding having an end terminated externally to the energy transfer element. The shield impedance is coupled between the externally terminated end of the shield winding and an input conductor of the power supply, where the shield impedance has a non-zero finite impedance value to substantially reduce a noise current in the input conductor.