Embedded Current-Sensorless Current Measurement Technique for Switched Mode Power Converters

Current mode control (CMC) techniques for switched mode converters are extensively used as they provide faster dynamic response and tight output voltage regulation. The current mode control technique requires the inductor's current as feedback to the system. However, real-time high-frequency inductor current sensing requires high bandwidth current sensors and high sampling rate analog to digital converters (ADCs). Furthermore, incorporating a current sensor (i.e., sensed resistor, hall sensor) leads to breakage of the path of the circuit and requires additional signal conditioning circuits. To address these challenges, this work evaluates a non-invasive embedded current measurement technique that uses terminal voltage measurement of the converter and an analog comparator connected to the switch node of the converter to reconstruct the inductor current within the digital controller. Nevertheless, this technique necessitates average terminal voltage sensing, hence the voltage can be sampled with low sampling frequency ADCs. Furthermore, the proposed current estimation concept is also applicable to multiport converters with multiple inductors in the circuit. Hence, this technique reduces the requirement for multiple current sensors and high-end ADCs. The proposed theory has been implemented using an FPGA-based digital platform used for controlling the switched mode converters. Moreover, the current estimation technique is validated using a laboratory-scale prototype of a boost converter and integrated dual dc boost multiport converter (IDDBC).