Single Sensor-Based Full-Range Voltage Balancing Method for Five-Level DC–DC Converters

Multilevel dc–dc converters typically require many voltage sensors to balance the capacitor voltages. In this article, a single sensor-based full-range voltage balancing method is proposed to reduce the number of voltage detectors for five-level dc–dc converters. First, the basic operation principle of the five-level converter is introduced. Then, the proposed sampling method using only one voltage sensor is modeled to decouple the sampling values, which are used to calculate the four capacitor voltages. In order to overcome the decoupling and sampling failure at 0.5 duty cycle, three duty cycle intervals are divided to apply different sampling and decoupling methods. To ensure the effectiveness in the full working range, the voltage balancing control is proposed by combining the hysteresis comparator and three duty cycle intervals. The limitation of sampling around 0.5 duty cycle, i.e., high inductor current ripple, is also discussed. The main contribution of this study is to reduce the number of voltage sensors, thus reducing the sensor cost and hardware complexity of the five-level dc–dc converter. Finally, a five-level dc–dc converter prototype is constructed to experimentally verify the voltage balancing method based on a single voltage sensor.