Voltage regulator

About: Voltage regulator is a research topic. Over the lifetime, 33536 publications have been published within this topic receiving 350859 citations.

Multiloop control method for high-performance microgrid inverter through load voltage and current decoupling with only output voltage feedback

Abstract: This paper proposes a multiloop controller with voltage differential feedback, and with output voltage decoupling and output current decoupling by only using the output voltage feedback. The output voltage differential feedback loop actively damps the output LC filter resonance and thus increases the system stability margin. The decoupling of output voltage and current makes the inner loop equivalent to a first-order system and thus improves the system dynamic response to load disturbance. The pole placement technique has been used here to design the inner loop and outer loop gain, with considering the effect of system control delay. The proposed control scheme possesses very fast dynamic response at load step change and can also achieve good steady-state performance at both linear and nonlinear loads. In addition, it only uses the output voltage as the feedback variable, which reduces the system complexity. The theoretical conclusion has been verified by simulation and experiment results. This method is proved to be an effective solution for voltage control in stand-alone mode of three-phase microgrid inverters.

Line-Interactive Single-Phase Dynamic Voltage Restorer With Novel Sag Detection Algorithm

Abstract: This paper describes the development of a line-interactive single-phase dynamic voltage restorer (DVR) with a novel sag detection algorithm. The developed detection algorithm has a hybrid structure composed of an instantaneous detection part and the root-mean-square (rms) variation detection part. The source voltage passes through the instantaneous sag detection part. If instantaneous sag is detected, the rms variation detector-1 is selected to calculate the rms variation. The rms variation detector-2 is selected when the instantaneous sag occurs under the operation of the rms variation detector-1. The feasibility of proposed algorithm was verified through computer simulations and experimental works with a 3-kVA-rating prototype of line-interactive DVR. The line-interactive DVR with the proposed algorithm can compensate the input voltage sag or interruption within 2.0-ms delay. The developed DVR can be effectively utilized for the sensitive loads, such as a computer, communication device, and automation device.

Stability of DC-link voltage as affected by phase locked loop in VSC when attached to weak grid

Abstract: This paper analyzes DC-link voltage stability as affected by phase locked loop (PLL) in voltage source converters (VSC) when connected to weak grid. PLL has an impact on power transferred to the grid from VSC due to active/reactive power current regulation aligned to PLL reference frame. DC-link voltage, directly related to power flows, is then affected by PLL dynamics. Interactions between PLL and DC-link voltage control are more serious in weak grid where terminal voltage, as input of PLL, becomes susceptible to power flow variations in VSC. In this paper, a system with VSC connected to infinite bus via grid impedance is studied for operating in inverter mode. Deteriorated DC-link voltage small signal stability is presented with quick PLL response as short circuit ratio (SCR) becomes significantly low. It may be possible for PLL to improve the DC-link voltage large signal stability due to its effect on power transfer.

Two wire low voltage dimmer

Abstract: A low voltage two wire dimming circuit comprises a voltage compensating circuit for regulating the RMS value of an AC voltage applied to a load and a correcting circuit for eliminating damaging DC current that may flow through the load. The voltage compensating circuit adjusts the firing angle of an electronic switch disposed in the dimming circuit to compensate for fluctuations in the AC supply voltage. The correcting circuit advances or retards the firing angle during selected half cycles to correct for asymmetries in the AC load voltage waveform caused by excessive DC current. According to the invention, there is also provided a two wire low voltage dimming circuit without voltage compensation but having improved dimming ability at low load currents and improved resistance to the flow of damaging DC currents.

Controlling/driving apparatus for an electrically-driven compressor in a car

Abstract: A controlling/driving apparatus for an electrically-driven compressor of an air conditioner mounted in an automobile. The apparatus comprises a DC-AC converting invertor 4 for converting a DC voltage into a pseudo AC voltage (e.g. a pulse train of positive and negative pulses), a DC voltage detector 7, and a pulse width changing unit 8 for changing the width of each pulse of the pulse train in accordance with the DC voltage detected by the DC voltage detector. Thus, the apparatus enables safe and efficient operation of the compressor with improved electric insulation and durability when large fluctuations in the power source voltage of the compressor occur.