Limiting Integral Loop Digital Control for DC–DC Converters Subject to Changes in Load Current and Source Voltage

A new digital control technique is proposed to improve the speed of both load current and source voltage transient responses for dc-dc converters operating in continuous conduction mode (CCM). The key structure of the proposed control technique is a combination of a limiting integral loop and related arithmetic operations to produce the desired switching sequence during transient condition. The limiting integral loop is built as a novel structure for capacitor charge balance operation. In contrast to previous approaches, the proposed control technique is valid for three basic converters: 1) buck; 2) boost; and 3) buck-boost. Moreover, since the transient period is forced to be an integer multiple of the switching cycle, the advantage of fixed switching frequency is inherently provided. Simulation and experimental results from a noninverting synchronous buck-boost converter prototype are given to validate the effectiveness of the proposed solution.