Carrier Overlapping Pulse Width Modulation Research Articles

Study on Carrier Overlapping PWM Technique for Nine Level Inverter

Multiple voltage level inverters are used widely because of its variable voltage values. More levels implies less total harmonic distortion (THD). Using carrier overlapping pulse width modulation(COPWM) technique, we can reduce THD when compared to other PWM techniques. In this paper, a study on carrier overlapping CO-PWM-A technique is conducted on a flying capacitor half bridge nine level inverter. Also compares with other PWM techniques for different reference signals for finding the features of operation and THD characteristics.

Analysis of Various Carriers Overlapping PWM Strategies for a Single Phase Ternary Multilevel Inverter

<p>Multilevel inverters are used in power conversion system due to improved voltage and current waveforms. This paper presents the comparison of various Carrier Overlapping Pulse Width Modulation (COPWM) Strategies for the three phase Cascaded Multi Level Inverter (CMLI). Various new schemes adopting the constant switching frequency and also variable switching frequency multicarrier control freedom degree combination concepts are developed and simulated for the chosen three phase CMLI. A single phase CMLI is controlled in this paper with Sinusoidal PWM (SPWM) reference along with Carrier Overlapping (CO) techniques and simulation is performed using MATLAB-SIMULINK. The variation of fundamental RMS output voltage and total harmonic distortion is observed for various carrier overlapping techniques. Among the various equal amplitude and unequal amplitude carriers carrier overlapping techniques such as COPWM-A, COPWM-B and COPWM-C, It is observed from Table 4 that all PWM method provides output with relative low distortion for equal amplitude carriers. If equal voltage sources are chosen then the THD will be less in the case of unequal amplitude carriers. But for the unequal voltage sources the THD is more in the case of unequal amplitude carriers. It is observed from simulation results that (Table-5) almost in all the strategies unequal amplitude carriers gives more fundamental RMS values compared to equal amplitude carriers. It is seen from table 6 that peak voltage is more in the case of unequal amplitude carriers compared to equal amplitude carriers. It is observed from the table 7 that dc components are less in both equal and unequal amplitude carriers.</p>

Carrier‐overlapping PWM‐based hybrid current control strategy applied to two‐stage grid‐connected PV inverter

For a wide dc input voltage range of photovoltaic (PV) array, a two-stage grid-connected inverter that allows input voltage regulation is required. This study proposes a topology with time-sharing synchronous modulation in which energy transmission paths, wheeling branches and switching losses for high-frequency switches are optimised to achieve efficiency improvement. The small-signal model of proposed topology is analysed in detail. A hybrid current control strategy based on frequency-amplitude domain analysis is presented. To solve further transitional problem on boost–buck mode switching, the controller uses a carrier-overlapping pulse-width modulation (PWM)-based generator. Then, the effectiveness of the proposed topology and the control strategy under different experimental conditions are verified. Experimental results indicate hybrid current control strategy promotes current waveform quality and the burrs and oscillations in transition between buck mode and boost mode can be reduced.

Asymmetrical Cascaded Multi Level Inverter Using Control Freedom Pulse Width Modulation Techniques

In this paer, the suggested topologies are gained by cascading a full bridge inverter with dissimilar DC sources. This topology has a several new patterns adopting the fixed switching frequency, multicarrier control freedom degree with mixture conceptions are established and simulated for the preferred three-phase cascaded multilevel inverter. In outstanding switching arrangement terminations, there are convinced degrees of freedom to produce the nine level AC output voltages with terminated switching positions for producing altered output voltages. These investigations focus on asymmetrical cascaded multilevel inverter engaging with carrier overlapping pulse width modulation (PWM) topologies. These topologies offer less amount of harmonics present in the output voltage and superior root mean square (RMS) values of the output voltages associated with the traditional sinusoidal pulse width modulation. This research studies carries with it MATLAB/SIMULINK based simulation and experimental results obtained using appropriated prototype to prove the validity of the proposed concept.

Real Time Implementation of Multi Carrier Based PWM Techniques for Single Phase Nine Level Trinary Source CMLI Using dSPACE

Multi carrier based Pulse Width Modulation techniques have been implemented for switching of prototype of single phase trinary source cascaded multilevel inverter in which 9- level output voltage can be achieved with fewest components. Different species of Carrier Overlapping Pulse Width Modulation (COPWM-A, COPWM-B and COPWM –C) strategies along with trapezoidal reference are used. The gating pulses are generated using dSPACE dS1103 Real Time Interface (RTI) hardware and control desk with MATLAB- SIMULINK environment. It is observed that COPWM-A provides relatively lower THD. Relatively higher RMS output voltage for modulation index ma=0.8 to 1 is obtained with COPWM – B. The performance indices used are Total Harmonic Distortion (THD), Root Mean Square (RMS) output voltage, Crest Factor (CF),Form Factor (FF) and Distortion Factor (DF).

Studies on Triangular Reference with Carrier Overlapping Pulse Width Modulation Methods for Diode Clamped Five Level Inverter

Studies on Triangular Reference with Carrier Overlapping Pulse Width Modulation Methods for Diode Clamped Five Level Inverter

Comparative Study on Carrier Overlapping PWM Strategies for Three Phase Five Level Cascaded Inverter

paper presents the comparison of Carrier Overlapping Pulse Width Modulation (COPWM) techniques for the Cascaded Multi Level Inverter (CMLI). A CMLI is controlled in this paper with Sinusoidal PWM (SPWM) reference, Third Harmonic Injection PWM (THI PWM) reference, Sixty degree PWM reference and Stepped wave reference with Carrier Overlapping (CO) techniques. The variation of Total Harmonic Distortion (THD) in the inverter output voltage is observed when the chosen inverter is controlled by SPWM for various modulation indices. Simulation is performed using MATLAB-SIMULINK. It is observed that COPWM-C provides output with relatively low distortion for all strategies. It is also seen that COPWM-A is found to perform better for all strategies since it provides relatively higher fundamental RMS output voltage and in particular highest output is obtained for 60 degree PWM reference. KeywordsCMLI, Stepped, THIPWM, 60 degree PWM, COPWM.

Comparative Study on Carrier Overlapping PWM Strategies for Five Level Diode Clamped Inverter

This paper presents the comparison of Carrier Overlapping Pulse Width Modulation (COPWM) techniques for the Diode clamped Multi Level Inverter (DCMLI). Due to switch combination redundancies, there are certain degrees of freedom to generate the five level AC output voltage. This paper presents the use of Control Freedom Degree (CFD) combination. The effectiveness of the Pulse Width Modulation (PWM) strategies developed using CFD are demonstrated by simulation and experimentation. The results indicate that the multilevel inverter triggered by the developed COPWM-A strategy exhibits reduced harmonics. PWM strategies developed are implemented in real time using dSPACE/Real Time Interface (RTI). The simulation and experimental results closely match with each other validating the strategies presented.