Small Signal Model for Peak Current Controlled Coupled SIDO Buck Converters

This paper proposes a complete small-signal model (SSM) for peak current-mode (PCM) controlled coupled inductor single-input dual-output (CI-SIDO) buck converter. The complete SSM is obtained by combining the current modulator SSM with the converter SSM. In PCM control, the current modulator is an essential part responsible for generating the duty cycle. The current modulator is formed with the combination of the comparator and SR flip-flop. The SSM of the current modulators is developed by deriving the expressions of duty cycles in terms of reference control voltages, sensed inductor currents and input voltage. The proposed SSM is relevant for designing the outer loop and predicting instability, dynamic characteristic of the complete system. MATLAB simulation and experimental results support the proposed model’s accuracy in predicting steady-state and dynamic characteristics. The accuracy of the proposed model in predicting the steady-state and dynamic characteristic is confirm using MATLAB simulation and experimental results.

I. Introduction

Many portable devices like digital camera, mobile phones, laptops, etc. consists of many sub-modules with different functionalities and each sub-modules demand different supply voltage level to operate. The power management unit (PMU) of these portable devices cater to the requirement from one single battery source. The conventional implementation of PMU in these devices consists of multiple single-input single-output (SISO) converters, which results in large volume, high cost, reduced reliability and low efficiency. As a consequence, the best alternative to multiple SISO converters is a single-input multi-output (SIMO) converter. SIMO converters of various types have been proposed aiming to meet miniaturization and better efficiency in the literature [1]–[7]. This paper focuses on single input dual output (SIDO) buck converter utilizing coupled inductor and termed as CI-SIDO buck converter.