The investigation on the AC to DC voltage multiplier

This paper investigates the topic of voltage multiplication, which converts a low AC voltage source to a high DC voltage source. Several designs are evaluated, such as the voltage doubler, the voltage tripler, and the voltage quadrupler. It is discovered that the input frequency and the capacitance do not affect the output voltage. This design can be extended to any integer multiples of the input voltage.

Compact and High-Efficiency Rectenna for Wireless Power-Harvesting Applications

A compact, single-layer microstrip rectenna for dedicated far-field RF wireless power-harvesting applications is presented. The proposed rectenna circuit configurations including multiband triple L-Arms patch antenna with diamond slot ground are designed to resonate at 10, 13, 17, and 26 GHz with 10 dB impedance bandwidths of 0.67, 0.8, 2.45, and 4.3 GHz, respectively. Two rectifier designs have been fabricated and compared, a half wave rectifier with a shunted Schottky diode and a voltage doubler rectifier. The measured and simulated maximum conversion efficiencies of the rectifier using the shunted diode half-wave rectifier are 41%, and 34%, respectively, for 300 Ω load resistance, whereas they amount to 50% and 43%, respectively, for voltage doubler rectifier with 650 Ω load resistance. Compared to the shunted rectifier circuit, it is significant to note that the voltage doubler rectifier circuit has higher efficiency. Both rectifier’s circuits presented are tuned for a center frequency of 10 GHz and implemented using 0.81 mm thick Rogers (RO4003c) substrate. The overall size of the antenna is 16.5 × 16.5 mm2, and the shunted rectifier is only 13.3 × 8.2 mm2 and 19.7 × 7.4 mm2 for the voltage doubler rectifier. The antenna is designed and simulated using the CST Microwave Studio Suite (Computer Simulation Technology), while the complete rectenna is simulated using Agilent’s ADS tool with good agreement for both simulation and measurements.

Current-Fed Bidirectional DC-DC Converter Topology for Wireless Charging System Electrical Vehicle Applications

This paper compares the efficiency of a modified wireless power transfer (WPT) system with a current-fed dual-active half-bridge converter topology and a complete bridge converter topology for a current-fed resonate compensation network with current sharing and voltage doubler. Full-bridge topologies are widely used in current WPT structures. The C-C-L resonate compensation networks for dual-active half-bridge converter and full-bridge converter topologies are built in this paper on both the transmitter and receiver sides. Due to higher voltage stress around inverter switches, series-parallel (S-P) tanks are not recommended for current-fed topologies because they are not ideal for medium power applications. A series capacitor is connected to reduce the reactive power absorbed by the loosely coupled coil. As a consequence, the C-C-L network is used as a compensation network. Dual-active half-bridge topology is chosen over full-bridge topology due to the system’s component count and overall cost. Soft-switching of the devices is obtained for the load current. The entire system is modelled, and the effects are analysed using MATLAB simulation.

Analysis and design of diode physical limit bandwidth efficient rectification circuit for maximum flat efficiency, wide impedance, and efficiency bandwidths

Generally, a conventional voltage doubler circuit possesses a large variation of its input impedance over the bandwidth, which results in limited bandwidth and low RF-dc conversion efficiency. A basic aspect for designing wideband voltage doubler rectifiers is the use of complex matching circuits to achieve decade and octave impedance and RF-dc conversion efficiency bandwidths. Still, the reported techniques till now have been accompanied by a large fluctuation of the RF-dc conversion efficiency over the operating bandwidth. In this paper, we propose a novel rectification circuit with minimal inter-stage matching that consists of a single short-circuit stub and a virtual battery, which contributes negligible losses and overcomes these existing problems. Consequently, the proposed rectifier circuit achieves a diode physical-limit-bandwidth efficient rectification. In other words, the rectification bandwidth, as well as the peak efficiency, are controlled by the length of the stub and the physical limitation of the diodes.

Design of a High Step-Up DC-DC Converter with Voltage Doubler and Tripler Circuits for Photovoltaic Systems

In this paper, a high step-up DC-DC interleaved boost converter is proposed for renewable sources with low voltages such as photovoltaic module and fuel cell. The proposed converter uses interleaving method with an additional voltage doubler and tripler circuit. In the proposed converter, the inductor at all phases is operated to gain high voltage through voltage doubler and tripler circuit capacitors with suitable duty cycle. The proposed topology operates in six switching states in one period. The steady-state analysis and operating principle are examined comprehensively which shows numerous improvements over the traditional boost converter. These improvements are high-voltage gain and low-voltage stress across switches. The proposed DC-DC interleaved boost converter has a gain/conversion ratio four times that of the conventional interleaved boost converter and four times less-voltage stress across the main switches. Simulation has been done in Matlab Simulink on a 70% duty cycle, and results are compared with conventional interleaved boost converter. For an input voltage of 15 volts, the proposed converter is able to generate an output voltage of 200 volts at 70% duty cycle with a voltage stress of 50 volts across main switches, whereas traditional interleaved boost converter generates 200 volts from same input voltage at 92.5% duty cycle with voltage stress of 200 volts across switches. From simulation results, it is clear that the proposed converter has better performance as compared to conventional interleaved boost converter for same design parameters.

Levitation Characteristics Analysis of a Diamagnetically Stabilized Levitation Structure

A diamagnetically stabilized levitation structure is composed of a floating magnet, diamagnetic material, and a lifting magnet. The floating magnet is freely levitated between two diamagnetic plates without any external energy input. In this paper, the levitation characteristics of a floating magnet were firstly studied through simulation. Three different levitation states were found by adjusting the gap between the two diamagnetic plates, namely symmetric monostable levitation, bistable levitation, and asymmetric monostable levitation. Then, according to experimental comparison, it was found that the stability of the symmetric monostable levitation system is better than that of the other two. Lastly, the maximum moving space that allows the symmetric monostable levitation state is investigated by Taguchi method. The key factors affecting the maximum gap were determined as the structure parameters of the floating magnet and the thickness of highly oriented pyrolytic graphite (HOPG) sheets. According to the optimal parameters, work performance was obtained by an experiment with an energy harvester based on the diamagnetic levitation structure. The effective value of voltage is 250.69 mV and the power is 86.8 μW. An LED light is successfully lit on when the output voltage is boosted with a Cockcroft–Walton cascade voltage doubler circuit. This work offers an effective method to choose appropriate parameters for a diamagnetically stabilized levitation structure.

Diode physical-limit-bandwidth efficient rectification

Generally, a conventional voltage doubler circuit possesses a large variation of its input impedance over the bandwidth, which results in limited bandwidth and low RF-dc conversion efficiency. A basic aspect for designing wideband voltage doubler rectifiers is the use of complex matching circuits to achieve decade and octave impedance and RF-dc conversion efficiency bandwidths. Still, the reported techniques till now have been accompanied by a large fluctuation of the RF-dc conversion efficiency over the operating bandwidth. In this paper, we propose a novel rectification circuit with minimal inter-stage matching that consists of a single short-circuit stub and a virtual battery, which contributes negligible losses and overcomes these existing problems. Consequently, the proposed rectifier circuit achieves a diode physical-limit-bandwidth efficient rectification. In other words, the rectification bandwidth, as well as the peak efficiency, are controlled by the length of the stub and the physical limitation of the diodes.