# Online Inductance Monitoring Based on Dynamic Characteristics and ESR Effect Compensation for Buck Converter Without Current Sensor

## TL;DR

This paper introduces a cost-effective method to monitor inductance in buck converters without using a current sensor, improving control performance and reliability.

## Contribution

A novel online inductance monitoring method is proposed that compensates for ESR effects without requiring a current sensor.

## Key findings

- An inductance calculation model is derived using dynamic characteristics and charge balance principles.
- The proposed method compensates for ESR effects, ensuring reliable inductance monitoring accuracy.
- Simulation and experimental results validate the effectiveness of the method in digital SCM-controlled buck converters.

## Abstract

Inductor parameter variations often affect the control performance of digital current mode (CM)-controlled buck converters as their high performance relies on accurate converter modeling. However, recent studies have shown that reliably monitoring inductance with current sensors and high-frequency sampling greatly increases the overall cost of this process. To address this issue, an online inductance monitoring method without a current sensor is proposed in this study. First, an inductance calculation model is derived by applying the dynamic characteristics of a buck converter with inductor volt-second and capacitor charge balance principles. The model’s accuracy is guaranteed by considering inductor current switching ripple characteristics. Nevertheless, output capacitor equivalent series resistance (ESR) can degrade the accuracy of the proposed calculation model. Thus, to enhance the tolerance of the inductance calculation model to capacitor ESR, the ESR effect on inductance monitoring is investigated. With the proposed capacitor ESR estimation method, inductance monitoring achieves reliable accuracy, even for a buck converter with high capacitor ESR. The effectiveness of the proposed method is verified by simulations and experiments on a buck converter with digital sensorless current mode (SCM) control.