Coupled power supply inductors for reduced ripple current

摘要

A power supply circuit for producing at least one output which is essentially free from current ripple is disclosed. A chopped DC voltage source is applied to a transformer having a primary coil and at least two secondary coils. The secondary coils provide input voltages to output stages which each include a rectifier diode, a freewheeling diode and an LC filter. The inductors in the LC filter of adjacent output stages are magnetically coupled together. The characteristics of these inductors are selected such that the current ripple through the inductors in all the output stages, other than the first output stage, is essentially zero. Multiple inductors can also be employed in the first output stage with each one being magnetically coupled to the inductor in a different succeeding output stage.PPThese multiple inductors in the first output stage can be combined in series or in parallel. A chained approach to coupling inductors as well as the use of an add-on ripple transformer can also be employed to product at least one essentially ripple-free output.