Neutral-Point Voltage Balancing Method for Three-Phase Three-Level Dual-Active-Bridge Converters

Three-phase three-level dual-active-bridge (3L-DAB3) converters are a potential topology for high-voltage and high-power applications. Neutral-point voltage balancing is complex important issue (3L) circuits. Compared with the single-phase 3L converter, self-balancing capability of 3L-DAB3 limited. To guarantee reliability neutral-point method proposed in this paper. First, principle analyzed. Then, relationship between duty ratio adjustment injected charge described. In order to accurate balance, adopts sign-hysteresis control dead zone. The zone responsible whether activated, guarantees correct direction. only needs sample capacitor voltages, thus avoiding parameter design making it easy implement. transmission power converter not affected during process. has rapid response speed does have problems respect stability. Finally, experiments were conducted on 3.6 kW laboratory prototype. validity performance verified basis simulation experimental results.