Three-phase Voltage Source Inverter System Research Articles

Observer-based adaptive threshold diagnosis method for open-switch faults of voltage source inverters

In this paper, the problem of open-switch faults of a voltage source inverter system is investigated. A new fault diagnosis method based on an observer and an adaptive threshold is proposed. This method only needs to utilize the signals existing in a system without the need for extra hardware circuits. First, an observer is designed on a model of a three-phase voltage source inverter system to estimate currents. Then, an adaptive threshold is designed on fault residuals, dynamics of the currents and variations of the system operating state. Moreover, the dead time and switching delay time are also included in the threshold to consider practical applications. Furthermore, to achieve on-line real-time diagnosis and to improve the reliability of the proposed method, the averages of the current residuals in a current fundamental period are defined as diagnostic variables. Finally, the reliability and effectiveness of the proposed method are verified by simulation and experiment results.

Development and Modelling of Three Phase Inverter for Harmonic Improvement using Sinusoidal Pulse Width Modulation (SPWM) Control Technique

This paper describes the design of a 400 V, three-phase voltage source inverter system using Sinusoidal Pulse Width Modulation (SPWM) control technique. Pulse Width Modulation (PWM) is an internal control technique for inverters. The Sinusoidal Pulse Width Modulation (SPWM) technique is the type of PWM used in this work. The aim is to reduce the harmonic produced by the inverter. Current standards require that total harmonic distortion (THD) be minimal. A three-phase SPWM signal is implemented in order to create an output voltage which is closer to a true sine wave and reduce harmonics. The development and model were implemented using MATLAB Simulink soft-ware and hardware parameters. The addition of a low pass filter circuit aids the achievement of smoother sine waveforms and a reduced THD value of 0.17%. The proposed concept has been validated through experimentally on a laboratory prototype by using DSP TMS320F28335 real-time digital control. The experimental outcomes emphasize the authenticity of the suggested technique in reducing harmonics, which can be promising to power quality improvement.

Border Collision of Three-Phase Voltage-Source Inverter System with Interacting Loads

As a commercial interface, three-phase voltage-source inverters (VSI) are commonly equipped for energy conversion to export DC power from most distributed generation (DG) to the AC utility. Not only do voltage-source converters take charge of converting the power to the loads but support the grid voltage at the point of common connection (PCC) as well, which is dependent on the condition of the grid-connected loads. This paper explores the border collision and its interacting mechanism among the VSI, resistive interacting loads and grids, which manifests as the alternating emergence of the inverting and rectifying operations, where the normal operation is terminated and a new one is assumed. Their mutual effect on the power quality under investigation will cause the circuital stability issue and further deteriorate the voltage regulation capability of VSI by dramatically raising the grid voltage harmonics. It is found in a design-oriented view that the border collision operation will be induced within the unsuitable parameter space with respect to transmission lines of AC grid, resistive loads and internal resistance of VSI. The physical phenomenon is also identified by the theoretical analysis. With numerical simulations for various circuit conditions, the corresponding bifurcation boundaries are collected, where the stability of the system is lost via border collision.

A Novel Finite-Time Settling Control Algorithm Designed for Grid-Connected Three-Phase Inverter With an LCL-Type Filter

In this paper, a cost-effective finite-time settling current control system for a utility-interactive three-phase voltage source inverter system with an inductor–capacitor–inductor (LCL)-type filter is originally designed and developed. The discrete-time system equation of the LCL-type filter is first simply derived in the $\alpha{-}\beta$ stationary reference frame. Then, the finite time of a three-sampling-period settling control algorithm is derived in the form of state feedback, whereas the required numbers of sensors are reduced by introducing an identification algorithm. Moreover, the implementation of the novel control scheme achieves the time-optimum response of a 3-D controlled variable in the LCL-type filter when damping the LC resonance strongly. The effectiveness of the proposed finite-time settling control algorithm is substantially confirmed by the simulation and experimental results of inverter, static synchronous compensator, and rectifier modes of operation.

Implementation of nondeterministic pulsewidth modulation for inverter drives

A single-phase power factor preregulator to improve the power quality in the input side of an ac/dc/ac converter and a random pulsewidth modulation (PWM) to reduce the emitted noise energy and the mechanical vibration for an induction motor drive is proposed. The hysteresis current control (HCC) technique for a voltage source switching mode rectifier (SMR) is adopted. A control scheme is presented such that the line current is driven to follow the reference current which is derived from the dc bus voltage regulator and the output power estimator. A random pulse position technique for a three-phase voltage source inverter system to reduce the noise energy and resonant vibration from ac machine drive is described. By randomly varying the instantaneous pulse position in each switching frequency, the frequency distribution of harmonics is spread in a wide frequency range which results in reduction of torque pulsations in the ac motor drive systems. To investigate the proposed control scheme, experimental tests based on a laboratory prototype were implemented to show the nearly unity power factor at the SMR and reduce the noise energy concentrated at the specific tones.