Single phase inverter

While substantial research covers current control and synchronization of grid-connected photovoltaic (PV) inverters, issues concerning control of the PV input voltage deserve more attention, as they equally affect the reliable and stable operation of the system. Hence, this paper analyses the PV voltage regulation in the single-stage single-phase PV inverter. In contrast to previous work, the PV source influence on the input voltage dynamic is analytically formalized, exposing a potential instability when the PV source is operating in its constant current region. A traditional proportional-integral PV voltage controller fails to ensure a consistent and stable voltage regulation. On the other hand, this issue is resolved by the proposed feedback linearization based controller. The new controller is validated on a test setup comprising of a PV source emulating a 1.2 kW PV array, interfaced to a single-phase inverter connected to a grid emulator. Confirming the issues predicted by the theoretical analysis, the experiments subsequently prove two main advantages of the proposed controller. Firstly, PV voltage regulation instability is eliminated when the PV array operates in its constant current region. Secondly, the PV voltage transient behavior is now independent from the operating point of the PV source.

In a single-phase inverter switched using unipolar sine-triangle PWM, two sinusoidal modulating signals of equal amplitude and phase-shifted by 180 degrees are compared against a common triangular carrier to control the switching of the two inverter legs. This paper investigates the injection of a common-mode signal to the two sinusoids. It is shown that the common-mode signal added should comprise of even harmonics only in order to ensure waveform symmetry at the two inverter poles and that no low-frequency harmonic currents flow through the load. This paper identifies a common-mode signal, which results in clamping of each leg for 90 degrees in each half-cycle of the fundamental voltage. While even harmonic injection cannot increase the maximum line-line voltage for a given dc bus voltage, the proposed bus-clamping scheme reduces the inverter switching losses by half. Further, the proposed technique ensures that the losses in all the devices over a line cycle are equal.

Electrical drives have historically relied on electromagnets. As they occupy large space, the size of the machine grows as the rating and torque grows, lowering its energy efficiency. The motor will reverse if the rotor windings are replaced with permanentmagnets. The emergence of superior magnetic materials has resulted in a reduction in motor size. Permanent Magnet Synchronous Motor (PMSM) provides efficient operation, almost negligible maintenance and high power factor. It is possible to design motor from few watts to kilo watt power for applications ranging from fans to electric vehicles. This needs reliable operation of drive, requiring fault tolerant control. The paper discusses fault-tolerant controller for PMSM using Direct Torque Controller (DTC). Applications of fault tolerance keep motor current and torque controlled and permissible within limit. This needs derivation of mathematical model for healthy and fault condition to calculate limiting values of current and speed. Reference current and speed controller has been designed using DTC. Simulations are carried out for varying voltage and load using Mat-Lab Simulink platform. Result shows that motor can be worked satisfactorily with fault.

In this paper, Cerebellar Model Articulation Controller neural network based speed control of induction motor has been presented. The proposed system consists of a neural network controller, a reference model, and an algorithm for changing the NN weights in order that the speed of the drive can track of the reference speed. The rotor flux is estimated by the simplified rotor flux observer on the rotor reference frame and the feedback linearization theory is used to decouple the rotor speed and the flux amplitude. The effectiveness of the proposed CMAC speed estimator is verified by experimental results in various conditions, and the performance of the proposed control system is compared with a new neural algorithm. Accurate tracking response and superior dynamic performance can be obtained using the CMAC NN.

The single phase inverter performance through the unipolar and bipolar strategies has been previously analyzed based on the constant switching frequency pulse width modulation (CSFPWM). However, the confined band variable switching frequency PWM (CB-VSFPWM) is currently proposed as a new variable switching frequency PWM technique through unipolar strategy to facilitate the design of high order filter, to reduce the switching losses, and to reduce the current total harmonics distortion (THD) as well. To evaluate the performance of a single phase inverter based on the CBVSFPWM through bipolar strategy, this paper presents a comparative study of the CB-VSFPWM based inverter performance using the unipolar PWM and the bipolar PWM strategies. The study adopts MATLAB/Simulink to simulate the inverter and to analyze the simulation results in terms of harmonics spectrum, total harmonic distortion (THD), and fundamental components. The analysis of the study results gives an indication about t...

This paper proposes a new technique for a voltage source multilevel inverter (MLI) with reduced switch count, and it creates a smoother sinusoidal output waveform with reduced total harmonic distortion (THD). Therefore, the proposed technique identifies a better position in the list of multilevel converters used for power quality conditioners. Semiconducting devices are added to it if the number of levels increases. In this work, the topology of MLI with reduced number of switches is presented. A new MLI is proposed with lower number of switches and sources in order to achieve higher level. The proposed topology is framed out with the combination of three half bridge and a single H-bridge configuration. Detailed simulation results for 15-level inverter of single and three phase inverters are presented in this paper. Three phase 15-level inverter is developed by employing three isolated different renewable sources and 21 switches.

This paper presents direct control of active and reactive power using grid voltage modulation for single-phase grid-connected photovoltaic inverter. A design of type-1 servo system based on pole-placement method is proposed to control the power flow using a simplified multiple-input multiple-output (MIMO) model of the system. Phase-locked loop (PLL) with a quarter cycle time delay is used to estimate the grid phase angle for the purpose of performing the stationary and synchronous reference frame transformation. Unipolar pulse width modulation (PWM) technique is used to control a single-phase inverter with 2.7 KVA capacity connected to the photovoltaic system. The proposed controller can simply be tuned using minimum number of controller gains to achieve the transient and steady-state performance requirements. The proposed system, was capable of operating for a wide range of solar irradiance levels with a power factor in the range of 0.95 (leading/lagging), for the reactive power compensation purposes.

This  paper  presents  a single-phase  grid-connected  photovoltaic  system  with direct  control  of  active  and  reactive  power  through  a  power  management system  of  a  Photovoltaic  inverter.  The  proposed  control  algorithm  is designed  to  allow  maximum  utilization  of  the  inverter’s  available  KVA capacity  while  maintaining  grid  power  factor  and  current  total  harmonic distortion  (THD)  requirements  within  the  grid  standards.  To  reduce  the complexity  and  improve  the  efficiency  of  the  system,  two  independent  PI controllers  are  implemented  to  control  single-phase  unipolar  PWM  voltage source inverter. One controller is used to control the power angle, and hence the  active  power  flow,  while  the  other  controller  is  used  to  control  the reactive  power,  and  consequently  the  power  factor  by  adjusting  thevoltage modulation  index  of  the  inverter.  The  proposed  system  is  modelled  and simulated  using  MATLAB/Simulink.  The  PV  inverter  has  been  examined while  being  simultaneously  connected  to  grid  and  local  load.  Results obtained  showed  the  ability  of  the  PV  inverter  to  manage  the  active  and reactive power flow at, and below rated levels of solar irradiances; resulting in  an  increased  inverter  utilization  factor,  and  enhanced  power  quality.  The proposed  system,  was  capable  of  operating  at  power  factors  in  the  range  of 0.9  lead  or  lag  for  reactive  power  compensation  purposes  and  delivered  its power at a wide range of solar irradiance variations.

Due to the global environmental concerns, increasing energy demands and developments in renewable energy technologies present a new opportunity to implement renewable energy sources. Wind energy is the most prominent among renewable sources, as it is an inexhaustible resource and its exploitation has thus far been ecologically friendly. The potential amount of wind energy is considerably greater than current worldwide energy demands. Wind energy has been developing more rapidly than the other renewable energy sources for the last few decades. The best way to harvest the wind energy is wind turbines. This paper presents a study on wind energy in the form of a stand-alone and hybrid power generation system used to electrify off-grid locations. The stand-alone wind-diesel system developed here is intended to be used to power a single house or a small community and it also functions as a mini-grid, generating power in places where adequate wind speed is available throughout the year. Ho...

The dead-time is necessary to be inserted between the gates drive pulses of the two power electronic switches in a one leg of any inverter to avoid a short circuit in the leg and the DC supply as well. However, adding the dead-time increases the low order harmonics of the output voltage/current waveform of the inverter. This paper investigates the positive effects of decreasing the pulse width modulation (PWM) drive pulses number per fundamental period on the current low order harmonics. In addition, this paper evaluates the impact of the confined band variable switching frequency pulse width modulation (CB-VSFPWM) technique on inverter performance in terms of dead-time mitigating, and consequenctely lowering the low order harmonics. CB-VSFPWM technique reduces the total harmonic distortion (THD) levels in the inverter output current as well. Theoretical analysis of the CB-VSFPWM effectiveness in reducing the negative effect of the dead-time has explained in this study and confirmed...

The  dead-time  is  necessary  to  be  inserted  between  the  gates  drive  pulses  of the two power electronic switches in a one leg of any inverter to avoid a short circuit in the leg and the DC supply as well. However, adding the dead-time increases the low order harmonics of the output voltage/current waveform of the  inverter.  This  paper  investigates  the  positive  effects  of  decreasing  the pulse width modulation (PWM)drive pulses number per fundamental period on  the  current  low  order  harmonics.  In  addition,  this  paper  evaluates  the impact  of  the confined  band  variable  switching  frequency  pulse  width modulation(CB-VSFPWM)technique  on  inverter  performance  in  terms  of dead-time mitigating, and consequenctelylowering the low order harmonics. CB-VSFPWM technique reduces the total harmonic distortion (THD)levels in  the  inverter  output  current  as  well.  Theoretical  analysis  of  the  CB-VSFPWM effectiveness in reducing the negative effect of the dead-time has explained in this study and confirmed by the MATLAB/Simulink simulation results.