Research on Output Waveform of Generator with Rectifier Load considering Commutation Overlap Angle

The purpose of this paper is to study the influence of the uncontrolled rectifier circuit on the generator’s output waveform when considering the commutation overlap angle. Taking the nonsalient permanent magnet (PM) generator directly connected with the uncontrolled rectifier circuit as an example, the equivalent circuit of the generator with rectifier load is established, and the commutation process of the rectifier circuit is analyzed when the effect of the commutation overlap angle is considered. The output waveforms of generator’s output side are obtained by analytical method, circuit simulation method, field-circuit coupled simulation method, and experimental method. The validity of the analysis methods is demonstrated by comparison. According to the results of analytical analysis, we know the characteristics of the output waveform under the influence of the commutation overlap angle. The existence of the commutation overlap angle will cause the voltage waveform to concave or convex, prolong the conduction time of the winding, and result in phase difference between the voltage waveform and current waveform. The influence of synchronous inductance and extra inductance on the output waveforms and harmonic distortion rate is analyzed. The research of this paper provides a theoretical basis for improving the output waveform of the generator with rectifier load.

A Modified Double-Integral-Sliding-Mode-Controller for a Microgrid System With Uncertainty

Recently infiltration of large scale of microgrid systems into the power grid is recorded. Among these systems, photovoltaic (PV) based microgrid systems are more in demand due to its renewable, pollution free properties and abundantly available fuel. Grid integration of this microgrid system again enhanced its energy efficiency. But, dynamics of this PV based microgrid system is highly nonlinear and uncertain in nature. It suffers from parametric uncertainties. This kind of system can’t be controlled properly by conventional linear controllers. Sliding mode controller (SMC) is capable of controlling this kind of system with ease. However, SMC suffers from its inherent chattering introduction in the system output waveform. To reduce the chattering from the output waveform, there is requirement of some modification in the existing SMC structure dynamics. This paper presents an extended state observer based double integral sliding mode controller (DISMC) for this studied system. By using DISMC, the chattering magnitude is diminished greatly. Parameter uncertainties of the system lead to some unknown control states. These unknown states are identified by the state observer. Therefore, the proposed controller is more efficient in reference tracking, disturbance rejection and robust stability. To test the efficacies of the proposed controller, results of the studied system with this controller are compared with that of H∞ controller.

Performance evaluation of 2.4kVA grid-tie inverter

This paper is focused on experimenting the overall performance of a 2.4kVA direct solar power supply system. The overall aim is to implement a solar power supply system without a battery back-up in order to minimize cost. The objectives include measuring the performance of grid-tie inverter, determine its period of operation under load conditions, to make the use of batteries optional in solar power supply system and minimize initial cost of installation. Various tests (variable load, fixed load and no-load) were carried out for the purpose of analysis. A dual trace digital storage oscilloscope was used to monitor the output waveform of the inverter to observe possible harmonic distortion on the waveform. The inverter takes its input power directly from the solar modules (panels) through the maximum power point tracker (MPPT) charge controller. Each category of test was conducted for at least three days of different weather conditions, to determine how variation in the sun’s intensity (irradiance) affects the operation of the inverter and its output power. Test results show that the inverter performs its function during the day apart from the early hours in the morning and later in the evening of each day, and the loads were powered successfully during the period of test. The output waveform as observed from the oscilloscope is not purely sinusoidal; it is rather a modified sine wave.

Design of a Novel Topology of Transformer-Less Cuk Inverter for Isolated Load Applications

This paper presents a new topology of single-stage inverter to generate quality sinusoidal output waveform without any additional boosting components. The proposed inverter is a combination of back-to-back two Cuk converters and hence, it is named as a cuk inverter. As per the inductor value, it can operate in continuous and discontinuous current mode. The sinusoidal output voltage can be raised or lowered with different duty ratio based on the load requirement. This Cuk inverter reduces the filter requirement in the output circuit. Further, to show the advantage of the proposed topology, a comparative study is carried out with conventional and recent converters in terms of number of switches, LC components and applications. The performance of the proposed topology is analyzed with MATLAB/Simulink tool and implemented as hardware to validate the simulated results.

A Novel Symmetrical Multilevel Inverter with Reduced Switch Count

Multilevel inverters produced lot of interest in academia and industry as they are becoming feasible technology for number of applications. These are considered as the progressing power converter topologies. To generate a quality output waveform with minimum number of switches, reduced switch multilevel inverter topologies has come in focus. This paper introduces a modified symmetrical MLI with reduced component count thereby ensuring the minimum switching losses, reduced total harmonic distortion, Size and installation cost. By proper combination of switches it produces a staircase output waveform with low harmonic distortion. In this paper novel symmetrical inverter topology with reduced component count based on level shift phase opposition and disposition PWM (PODPWM) is proposed. The results are validated using MATLAB/SIMULINK.