TECHNIQUE FOR SENSING INDUCTOR AND DC OUTPUT CURRENTS OF PWM DC-DC CONVERTER

The design, analysis and trade-offs of a novel method to sense the inductor and de output currents of PWM converters are presented. By sensing and adding appropriately the currents in the transistor, rectifier and capacitors of a converter using current transformers, the waveforms of inductor and de output currents can be reconstructed accurately while maintaining isolation; This method offers high bandwidth, clean waveform, practically zero power dissipation and simple circuit. The technique is applicable to all PWM converters in both continuous and discontinuous modes, and is most suitable for the implementation of current mode control schemes like hysteretic, PWM conductance control, and output current feedforward. This approach has been experimentally verified at a wide range of current levels, duty cycles, and switching frequencies up to 1.4 MHz.