A Dynamic Wide-Bandwidth Compensation for Non-Inverting Buck-Boost Converter

Abstract

A non-inverting buck-boost converter is a converter which produces a positive output voltage that is either larger or smaller than the input voltage. This type of converter finds use in various applications in general and mobile application in particular. However, there are some problems that limit the performance of the converter. First, the non-minimum phase characteristic in boost mode makes it hard to compensate the converter with high bandwidth. Therefore, the compensation network is usually designed with small bandwidth to ensure the stability of the system. Thus, the system response over a range of input, output voltage is unacceptable in some applications. In addition, the converter is commonly compensated and optimized for some specific values of input, output voltage. As a result, the stability of the converter is only guaranteed at this particular operating condition and the circuit probably become unstable when the operating condition such as input, output voltages and load current change. In this paper a dynamic compensation technique that optimizes the controller under various input, output voltage, load current conditions is presented which improve bandwidth and transient response of the converter. The theory and simulation show the effectiveness of the approach.