Design of a Current Control System for Generating Various Current Forms

Proton Exchange Membranes (PEM) are electrochemical systems and sensitive to the quality of inputs- current, voltages, and power. In an effort to take advantage of wide bandgap components, the switching frequency of converters is increasing. Although it helps to improve aspects like power density and operational efficiency, it introduces high-frequency current ripples at the output. These high-frequency current ripples impact the operational lifetime of PEM cells. This paper presents the design and operation of a scaled-down, lab-scale current regulator board specifically designed to replicate the high-frequency output signal of a power converter used to supply PEM cells. The board generates a maximum of 10 A current to supply a PEM cell at a ripple frequency of 50 kHz and a ripple factor of up to 150 %. Regulation is achieved by a specially developed current control system that generates the current ripple using a linear MOSFET. The current is measured via a shunt resistor, whereby the controller reacts dynamically to the set point changes and thus generates a rectangular, triangular and sinusoidal current waveform. In addition, the current control enables the impedance measurement of the PEM cell with a DC component of 10 A and a peak value of up to 15 A.