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.

Dynamic performance of PWM DC-DC boost converter with input voltage feedforward control

Abstract: Small-signal characteristics are studied for a pulse-width modulated (PWM) boost converter with input voltage feedforward control. The characteristics are valid for the continuous conduction mode (CCM). A small-signal circuit model is used to derive the input-to-output voltage transfer function (audio-susceptibility), the input impedance, and the output impedance. A response of the output voltage to a step change in the input voltage is also computed. The measured Bode plots of the input-to-output voltage transfer function agreed with that predicted theoretically. It is shown that the feedforward control may reduce the magnitude of the input-to-output voltage transfer function by 40 dB. The input resistance of the converter with feedforward control is negative at low frequencies. The output impedance is not affected by feedforward control.

A Dynamic LVRT Solution for Doubly Fed Induction Generators

Abstract: Doubly fed induction generators have become the most common type of wind turbine generators. However, this type of generator is susceptible to grid-side low voltage and short circuits due to existence of a power electronics converter on the rotor side. When a short circuit or voltage sag happens on the grid side, the rotor current of the generator tends to rise, which could cause damage to the rotor converter. Design and implementation of a series converter on the stator side is presented in this paper to limit the current rise in the rotor. This system includes an active AC/DC inverter, three series transformers, and a DC-bus capacitor. To lower the rating of the components and make the system viable for practical solutions, an exponential decaying sinusoidal voltage, instead of a pure sinusoidal voltage, is applied by the converter during short circuit.

Modeling magnetically insulated devices using flow impedance

Abstract: In modern pulsed power systems the electric field stresses at metal surfaces in vacuum transmission lines are so high that negative surfaces are space‐charge‐limited electron emitters. These electrons do not cause unacceptable losses because magnetic fields due to system currents result in net motion parallel to the electrodes. It has been known for several years that a parameter known as flow impedance is useful for describing these flows. Flow impedance is a measure of the separation between the anode and the mean position of the electron cloud, and it will be shown in this paper that in many situations flow impedance depends upon the geometry of the transmission line upstream of the point of interest. It can be remarkably independent of other considerations such as line currents and voltage. For this reason flow impedance is a valuable design parameter. Models of impedance transitions and voltage adders using flow impedance will be developed. Results of these models will be compared to two‐dimensional, time‐dependent, particle‐in‐cell simulations.

Current sensing apparatus and method for a capacitance- sensing device

Abstract: A capacitance-sensing device including a current-to-voltage converter and an analog-to-digital converter is described. A sense element is coupled to an input of the current-to-voltage converter. The current-to-voltage converter is configured to convert current changes in the coupled sense element to an output voltage and to maintain a constant voltage at the input. The analog-to-digital converter is configured to convert the output voltage generated by the current-to-voltage converter to a digital value.