An Outward Research On Dual Buck Half Bridge Inverter

As an important breed of power converters, voltage source PWM inverter (VSI) has been widely used in industrial applications, such as uninterruptible power supplies (UPS), active filters, motor drives and distributed power generators (DG). Further enhancement of voltage source inverter's performances, particularly its power density is of vital importance.Dual buck half bridge inverter (DBI) is a novel inverter topology, which features the property of no shoot-through problem. This makes it preferable in reliability demanding occasions. In addition, the body diodes of the switches in DBI are not involved in the whole working duration, so the reverse recovery problem is mitigated, and the power devices can be separately optimized. This desirable property gives DBI the benefit of a full use of the newest power devices, which results in lower switching loss and thereby the probability of higher switching frequency.However, the voltage stress of DBI is twice of the DC voltage sources, and it is unsuitable for high voltage applications. This thesis first focuses on a diode clamped three-level dual buck half bridge inverter (TLDBI), which is an outward expansion of DBI in high voltage applications. TLDBI not only retains all the merits of DBI, but it has a lower voltage stress of power devices. Meanwhile, harmonic component of bridge output voltage is much lower because it is three-level modulated which is superior to two-level modulation in harmonic performance. Topology configuration theory and a dual band three-level hysteresis current controller are analyzed in detail; simulations and experiments are carried out to confirm its practical performances.At last, a novel single-stage Buck/Boost inverter is proposed based on the half load mode control strategy just as DBI, which still works when the DC link voltage is lower than the AC voltage. The principles of the circuit are explained in detail. The simulation and experiment results both indicate its feasibility.