Improved Watkins-Johnson topology-based inverter with dual low-side switch and synchronous control strategy

Abstract

Abstract:The full-bridge topology is generally used in the post stage of inverter, to realize dc-ac voltage conversion. Inherent shortcomings of full-bridge such as high-side switch driving, prone to shoot-through and substantial power loss are inevitable. A topological solution is proposed in this letter, by means of improving the original coupledinductor Watkins-Johnson topology into dual low-side switch version and conducting synchronous control. Theoretical analysis and experimental results indicate that the improved topology is capable of generating pure sinusoidal ac output. The merits include ease of driving, low power loss, nonpulsating terminal currents, immunity to shoot-through, simple control strategy and so forth.

Active PFC stage based on synchronous inverse Watkins-Johnson topology

“…The float power switch in original IWJ converter is low-side-ized by using the similar approach proposed in [2].…”

“…Although it possesses advantages of simple circuit structure, low component count, and high frequency at marginal duty cycle [1], shortcomings are inevitable such as difficult-drive high-side power switch, shoot-through issue, and high switch stress. In order to improve the performance of the conventional WJ topology, several approaches have been proposed in the author's previous research [2][3][4] [5], in which the applied range has been extended from inverter to LED constant current driver.…”

Synchronous High Step-Down Ratio Non-Isolated LED Constant Current Driver Based on Improved Watkins-Johnson Topology

“…Different from the dc-dc converter, we concern about the output current instead of the output voltage. Therefore, the output voltage can be decomposed into terms that including output current in (12). The resistance term and the voltage drop term are defined as R and V D for convenient.…”

“…Nevertheless, several shortcomings include drive difficulty of the float switch, high input noise level, and complexity of primary inductor, hampers its applying. In order to overcome limitations of the WJ topology, the author of this paper have been proposed two approaches to improve the original WJ topology in recent previous works [12], [13], to realize dc/ac inverter, which will be collected and re-demonstrated in next section.…”

Single stage high-frequency non-isolated step-up sinusoidal inverter with three ground-side power switches

“…The voltage step-up and down procedure brings about extra loss of efficiency, and the separate control strategy on each stage increases the control complexity. In order to solve these inherent shortcomings, a topological approach is proposed, by cascading and optimizing the structure of the conventional boost and the improved Watkins-Johnson (WJ) topology [17,18]. The merits include: only one control signal is able to realize voltage step-up as well as sinusoidal inversion; three ground-connected power switches render the inverter ease of driving.…”