Negative impedance converter

About: Negative impedance converter is a research topic. Over the lifetime, 5801 publications have been published within this topic receiving 87636 citations.

A Novel High Step-Up DC–DC Converter With Continuous Input Current Integrating Coupled Inductor for Renewable Energy Applications

Abstract: In this paper, a nonisolated dc–dc converter with high voltage gain is presented. Three diodes, three capacitors, an inductor, and a coupled inductor are employed in the presented converter. Since the inductor is connected to the input, the low input current ripple is achieved, which is important for tracking maximum power point of photovoltaic panels. The voltage stress across switch S is clamped by diode D 1 and capacitor C 1. Therefore, a main switch with low on-resistance RDS (on) can be employed to reduce the conduction loss. Besides, the main switch is turned on under zero current. This reduces the switching loss. The steady-state analysis of the proposed converter is discussed in this paper. Finally, the proposed converter prototype circuit is implemented to justify the validity of the analysis.

Novel Isolated High-Step-Up DC–DC Converter With Voltage Lift

Abstract: A novel two-switch high-step-up isolated converter with voltage lift is proposed in this paper. The proposed isolated converter utilizes a transformer with low turn ratio to achieve high step-up gain. The secondary winding charges two boosting capacitors in parallel as switches during the switch-on period, and two boosting capacitors are discharged in series during the switch-off period. Thus, the converter has high voltage gain with appropriate duty ratio. In addition, by using two clamping diodes and a capacitor on the primary side, leakage energy is recycled, and the voltage spikes of the two active switches are clamped, thereby improving conversion efficiency. Finally, experimental results based on a prototype implemented in the laboratory with an input voltage of 24 V, an output voltage of 200 V, and an output power of 200 W verify the performance of the proposed isolated converter; full-load efficiency is nearly 93%.

Band Gap Control in an Active Elastic Metamaterial With Negative Capacitance Piezoelectric Shunting

Abstract: Elastic metamaterials have been extensively investigated due to their significant effects on controlling propagation of elastic waves. One of the most interesting properties is the generation of band gaps, in which subwavelength elastic waves cannot propagate through. In the study, a new class of active elastic metamaterials with negative capacitance piezoelectric shunting is presented. We first investigated dispersion curves and band gap control of an active mass-in-mass lattice system. The unit cell of the mass-in-mass lattice system consists of the inner masses connected by active linear springs to represent negative capacitance piezoelectric shunting. It was demonstrated that the band gaps can be actively controlled and tuned by varying effective stiffness constant of the linear spring through appropriately selecting the value of negative capacitance. The promising application was then demonstrated in the active elastic metamaterial plate integrated with the negative capacitance shunted piezoelectric patches for band gap control of both the longitudinal and bending waves. It can be found that the location and the extent of the induced band gap of the elastic metamaterial can be effectively tuned by using shunted piezoelectric patch with different values of negative capacitance, especially for extremely low-frequency cases.

Novel High Step-Up DC–DC Converter With Coupled-Inductor and Switched-Capacitor Techniques for a Sustainable Energy System

Abstract: In this paper, a novel high step-up dc-dc converter is proposed for a sustainable energy system. The proposed converter uses coupled-inductor and switched-capacitor techniques. The capacitors are charged in parallel and discharged in series by the coupled inductor to achieve high step-up voltage gain with an appropriate duty ratio. Besides, the voltage stress on the main switch is reduced with a passive clamp circuit; low on-state resistance Rds(on) of the main switch can be adopted to reduce the conduction loss. In addition, the reverse-recovery problem of the diode is alleviated by a coupled inductor. Thus, the efficiency can be further improved. The operating principle and steady-state analyses of voltage gain are discussed in detail. Finally, a prototype circuit with 24-V input voltage, 400-V output voltage, and 200-W output power is implemented in the laboratory to verify the performance of the proposed converter.

Steep-slope Hysteresis-free Negative Capacitance MoS2 Transistors

Abstract: The so-called Boltzmann Tyranny defines the fundamental thermionic limit of the subthreshold slope (SS) of a metal-oxide-semiconductor field-effect transistor (MOSFET) at 60 mV/dec at room temperature and, therefore, precludes the lowering of the supply voltage and the overall power consumption. Adding a ferroelectric negative capacitor to the gate stack of a MOSFET may offer a promising solution to bypassing this fundamental barrier. Meanwhile, two-dimensional (2D) semiconductors, such as atomically thin transition metal dichalcogenides (TMDs) due to their low dielectric constant, and ease of integration in a junctionless transistor topology, offer enhanced electrostatic control of the channel. Here, we combine these two advantages and demonstrate for the first time a molybdenum disulfide (MoS2) 2D steep slope transistor with a ferroelectric hafnium zirconium oxide layer (HZO) in the gate dielectric stack. This device exhibits excellent performance in both on- and off-states, with maximum drain current of 510 {\mu}A/{\mu}m, sub-thermionic subthreshold slope and is essentially hysteresis-free. Negative differential resistance (NDR) was observed at room temperature in the MoS2 negative capacitance field-effect-transistors (NC-FETs) as the result of negative capacitance due to the negative drain-induced-barrier-lowering (DIBL). High on-current induced self-heating effect was also observed and studied.