Adaptive Load Current Feedforward Control of Pulsed Output Current Converters

Certain DC-DC converter topologies (e.g. boost) are characterized by pulsed output current which translates into a Right-Half-Plane-Zero (RHPZ) in their transfer function. This behavior constrains the achievable closed-loop bandwidth, posing severe limitations to the converter's dynamic performance. In this work, load current feedforward control technique is investigated in order to minimize the RHPZ impact. The proposed solution employs differentiation of the boost converter's output voltage for the estimation of the load current. The level of the estimated feedforward signal is set to the near-optimal theoretical value by employment of an auto-tuning circuitry. The feedforward signal is then combined with the peak current mode control loop. The auto-tuning circuitry makes the approach less dependent on converter's parameters like output capacitance and duty cycle.