Single-Stage Duty-Controlled Half-Bridge Inverter for Compact Capacitive Power Transfer System

Abstract

Capacitive wireless power transfer (CPT) is becoming a promising alternative to inductive power transfer (IPT) due to low costs and the simplicity of capacitive coupler. This paper presents a new architecture that makes CPT systems even simpler and easier to control. In the proposed scheme, a wide input voltage range is achieved by duty control while the output voltage is inherently load-independent, and this eliminates the need for an extra DC-DC converter. Our system also provides an extended zerovoltage-switching (ZVS) range to deal with both input and load variations. We carried out ZVS analysis for each MOSFET switch and based on this an optimal design was proposed. We implemented a prototype 160 W CPT system based on our design procedure, and its performance was then verified under a universal input voltage with load variations from 200-1000 Ω. A DC-DC efficiency as high as 88.2 % was achieved, showing the value of the proposed topology.INDEX TERMS Asymmetric half-bridge, capacitive wireless power transfer, zero voltage switching.

Research and Application of Capacitive Power Transfer System: A Review

“…A half-bridge inverter is structurally equivalent to replacing the two MOSFETs in a voltage-source full-bridge inverter with two capacitors or inductors. Half-bridge inverters can also be further divided into voltage-mode half-bridge inverters [40,41] and currentmode half-bridge inverters [42], depending on the reactive components included. The voltage-type half-bridge inverter is structurally equivalent to replacing the two MOSFETs on the right side of the full-bridge inverter with two capacitive elements, and its output is only half of the voltage-type full-bridge inverter, so it is generally applicable for small and medium power applications.…”

“…The voltage-type half-bridge inverter is structurally equivalent to replacing the two MOSFETs on the right side of the full-bridge inverter with two capacitive elements, and its output is only half of the voltage-type full-bridge inverter, so it is generally applicable for small and medium power applications. In [41], a CPT system based on a voltage-type half-bridge inverter circuit was designed, which achieved 160 W power transmission, and the efficiency was as high as 88.2%; the current-type half-bridge inverter is structurally equivalent to using two inductive elements. Replacing the upper two MOSFETs in the full-bridge inverter is characterized by soft-switching oscillation that can be achieved through self-excited oscillation without external control signals.…”