FPGA-based improvement of classical current tracking methods for high-frequency power converters

Embedded microprocessors require efficient supply management systems to optimize its power consumption and to enhance their calculation potentials. Typically, the modules performing this function are known as Voltage Regulator Modules (VRMs). It is widely adapted that current-programmed regulation techniques own leveraging skills in the control of this kind of power converters. However, these strategies require a fine inductor-current sensing to achieve accurate results. One critical issue in the inductor-current sensing is the effect of parasitic inductances in the measurement loop. This undesirable effect produces a considerable mismatch between the real inductor-current waveform and the equivalent voltage image captured thanks to the shunt resistance. Further, this unwanted deviation augments as long as the current value is increased. As a result, this problem makes loosely the data obtained. However, today´s commercial digital controllers, like FPGAs¹, can be used to reduce overwhelmingly the aforementioned drawback. The presented work exploits some intrinsic advantages of FPGAs such as its great processing speed and its parallel working mode to overcome this drawback. Therefore, a new digital auto-tuning system is proposed in which this undesirable effect is treated and compensated. The obtained result is a digital signal which avoids the parasitic effect of the inductance in the measurement loop. In the last part of our work, some experimental results, using a FPGA, validate the advantages of the proposed method.