Novel, technique for sensing inductor current and DC output current of PWM DC-DC converter

A method of sensing inductor and DC output currents of a pulse-with-modulated (PWM) converter is presented. By sensing the currents in the transistors, rectifiers, and capacitors of the converter using current transformers and adding the sensed outputs appropriately, the waveforms of the inductor and DC output currents can be reconstructed accurately with isolation. This method offers the advantages of high bandwidth, clean waveforms at high frequency, practically zero power dissipation, and a simple circuit. This technique is applicable to all PWM power converters in both continuous and discontinuous mode, and is most valuable for the implementation of hysteretic current mode control, PWM conductance control, and output current feedforward. This approach has been experimentally verified for a wide range of current levels, duty cycles, and switching frequencies up to 1.4 MHz