Voltage-Based Charge Balance Controller Suitable for Both Digital and Analog Implementations

In this paper, a novel voltage-based charge balance control algorithm is presented, which is suitable for both digital and analog implementations for buck converter to achieve near-optimal dynamic performance. First, this paper presents a new derivation of practical charge balance equations based on simplified differential equations. This deviation is applicable to both fast input voltage and load step transients. The final algorithm does not require complex calculations and accurate knowledge of the output filter LC parameter. Second, the proposed voltage-based charge balance controller does not require accurate current sensor or fast analog-to-digital converter. Instead, to detect the critical time instant when the inductor current equals the new load current, a practical extreme voltage detector is introduced to capture the output voltage peak/valley information. Third, this algorithm is simple to be implemented by either low-cost digital signal processing devices (such as microcontroller unit) or analog circuits. Both digital and analog experimental prototypes are built to verify the feasibility and advantages of the new method.