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

摘要

Example methods include calculating a first number of turns of a shield winding included in an energy transfer element of a power supply. A first number of turns of the shield winding is calculated for the power supply to have a low noise current in an input conductor of the power supply. The method then includes increasing the first number of turns to a second number of turns. The power supply is then operated, which generates a first voltage waveform of a voltage between the input conductor and an output conductor of the power supply. An impedance is then inserted between the shield winding and the input conductor. The noise current is reduced by adjusting a value of the impedance until a second voltage waveform of the voltage between the input conductor and the output conductor reverses polarity to be the opposite of a polarity of the first voltage waveform.