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This paper analyses and compares candidate zero dv/dt half-wave Class-E rectifier topologies for integration into multi-MHz inductive power transfer (IPT) systems. Furthermore, a hybrid Class-E topology comprising advantageous properties from all existing Class-E half-wave zero dv/dt rectifiers is analyzed for the first time. From the analysis, it is shown that the hybrid Class-E rectifier provides...
This paper describes the system concept and initial results for end-to-end energy-autonomous sensor systems using unmanned aerial vehicles (drones) as agents for power delivery to and data gathering from sensing devices. Such systems may be particularly useful for delay tolerant monitoring scenarios, where sensing devices may be deployed in remote, harsh conditions, often with sparse connectivity,...
This paper presents the development of a hybrid Class-E synchronous rectifier for wireless powering of quad-copters through inductive power transfer. A synchronous rectifier relaxes the heatsink requirement for continuous operation as the transistor conduction losses will be lower than the diode conduction losses. This provides an advantage when the weight of the electronics is significant for the...
Recent developments in high frequency inductive wireless power transfer (WPT) mean that the technology has reached a point where powering small autonomous drones has become feasible. Fundamentally, drones can only carry very limited payloads and thus require light-weight WPT receiver solutions. The key to achieving light weight is operating the WPT system at high frequency: this allows both the coils...
Inductive power transfer (IPT) systems are often designed to achieve their highest efficiency at a fixed load value and at a fixed coil separation distance and misalignment. A variation in the position of the coils or the load value tends to drastically affect the efficiency, and therefore makes the designed IPT system not practical for applications that are mobile with variable loading conditions...
In maximal link efficiency IPT design, a fixed AC load value is required. For this reason, matching the value of the input impedance of the rectifier to the optimal AC load is necessary. This paper presents a current driven Class D rectifier with a resistance compression network for 6.78MHz IPT systems, in which the reflected AC load has a minimal variation for a wide range of DC output loads. Experimental...
This paper presents the design and implementation of a voltage driven hybrid Class-E low dv/dt half wave rectifier with focus on high frequency (HF), 3 – 30 MHz, inductive power transfer (IPT). The hybrid rectifier is capable of absorbing the parasitic capacitance of the utlised diode while maintaining the properties of the conventional Class-E rectifier with a series capacitor. The hybrid rectifier...
This paper presents the development and utilisation of a voltage source multi-frequency Class-D inverter in a cost-effective test rig for rectifiers in 6.78 MHz to 13.56 MHz inductive power transfer (IPT) systems without the need of the magnetic link. Apart from the inverter, the rig compromises a tuned receiving (Rx) coil of the IPT system and a rectifier under test. With the inverter emulating a...
For mid-range inductive power transfer (IPT) systems, improving link efficiency entails operating in the multi-MHz region in order to increase coil Q factors. However, designing end-to-end systems at such frequencies poses challenges associated with the efficiency of the power electronics. This paper presents a set of design principles with the aim of achieving maximal DC-to-load efficiency of such...
Two current driven half wave rectifier topologies, Class-D and -E, have been characterised for IPT applications. Both rectifiers utilised SiC Schottcky diodes for high power capability. The Class-D topology has reached efficiencies up to 95% and the Class-E up to 90%. Both topologies achieved their highest efficiencies at high voltage operation as the parasitic capacitances of the SiC diodes were...
Class EF inverters are hybrid inverters that combine the improved switch voltage and current waveforms of Class F and Class F−1 inverters with the efficient switching of Class E inverters. As a result, their switch voltage and current stresses are reduced, and their efficiency, output power and power-output capability can be higher than the Class E inverter. These improved features of Class EF inverters...
This paper presents the integration of a Class-E rectifier into a high frequency semi-resonant inductive power transfer system. The rectifier is used to rectify the 5.56 MHz ac output of the resonant receiving coil. End to end efficiency's exceeding 69 % are demonstrated while transferring 120 W with 30 cm coil spacing. Rectifier topologies were reviewed with their applicability to high frequency...
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