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.

Light emitting diode driver with isolated control circuits

Abstract: A light emitting diode (LED) driver circuit that generates current for driving an LED load includes a voltage converter circuit configured to supply a drive current to the LED load in response to a control signal, a control circuit that generates the control signal, and a bias voltage generating circuit that generates the bias voltage for the control circuit. The bias voltage generating circuit is galvanically isolated from a power supply voltage and from the LED load. The voltage converter circuit regulates a level of the drive current supplied to the LED load in response to the control signal.

An Interleaved Half-Bridge Three-Port Converter With Enhanced Power Transfer Capability Using Three-Leg Rectifier for Renewable Energy Applications

Abstract: In this paper, an interleaved half-bridge (IHB) three-port converter (TPC) is proposed for a renewable power system. The IHB-TPC is used to interface three power ports: 1) one source port; 2) one battery port; and 3) one isolated load port. The proposed IHB-TPC is derived by integrating two half-bridge TPC modules. A parallel configuration is adopted for the primary side of the two half-bridge modules, while a parallel–series configuration is adopted for the secondary side of the two modules. The power can be transferred from the source and the battery to the load within the whole switching cycle with the proposed IHB-TPC. It means there are no additional conduction losses caused by the circulating current or the free-wheeling operation stage. Hence, the voltage gain can be extended, and the output filter can be reduced. Zero-voltage switching is realized for all the four main switches to reduce the switching losses. Two of the three ports can be tightly regulated by adopting pulsewidth modulation plus phase-shift control, while the third port is left unregulated to maintain power balance for the system. The operation principles and the performances of the proposed converter are analyzed in detail. The experimental results are given to verify the feasibility and the effectiveness of the proposed converter.

A new nested neutral point clamped (NNPC) converter for medium-voltage (MV) power conversion

Abstract: In this paper, a new Voltage Source Converter (VSC) for Medium Voltage (MV) applications is presented which can operate over a wide range of voltages (2.4kV-7.2KV) without the need for connecting power semiconductor in series. The operation of the proposed converter is studied and analysed. In order to control the proposed converter, a Space Vector Modulation (SVM) strategy which benefits from the switching state redundancy has been used. This strategy helps to control the output voltage and stabilize voltages of the flying capacitors in the proposed converter. Performance of the converter under different operating conditions is investigated in the MATLAB/Simulink environment.

Intrinsic speed limit of negative capacitance transistors

Abstract: The emergence of negative capacitance as a way to limit power dissipation in CMOS logic transistors has raised the question of response delay of ferroelectric negative capacitance. Latency requirements for digital logic require a response time on the order of 10 ps or less. In this letter, we establish a coherent theoretical framework to analyze the delay between the clock edge at the gate and the response of the semiconductor channel in a ferroelectric negative capacitance transistor. The standard Landau–Khalatnikov equation approximates the slow, diffusive limit of the classical equation of motion. Therefore, using it to predict the response speed is unphysical. After extracting the damping and kinetic inductance from THz spectroscopy data, we simulate the full classical equation of motion and analyze the delay. We find that for doped hafnium oxides, the intrinsic delay is around 270 fs, far less than what is required for digital logic.

A Family of Exponential Step-Down Switched-Capacitor Converters and Their Applications in Two-Stage Converters

Abstract: This paper presents a family of exponential voltage step-down switched-capacitor (ESC) converters. Considering the demand of large-voltage-gain step-down converters in the market, it is difficult to achieve the step-down requirement with good efficiency for a single-stage buck converter. The two-stage converter has been an effective solution for high-voltage-step-down applications. In this paper, making use of the large-voltage-gain conversion property of the ESC converter, a two-stage ESC-buck converter is proposed. A mathematical tool for the accurate calculation of efficiency is developed. The efficiency characteristic of the proposed ESC converter is established. Experimental efficiency measurements are carried out using the ESC converter proposed and two different types of commercially available buck converter ICs. The results show that the efficiency of the ESC-buck converter is higher than that of a single buck converter for large-voltage-gain applications.