Inverted Sine Carrier Research Articles

Critical analysis of random frequency inverted sine carrier PWM fortification for half-controlled bipolar three-phase inverters

The inverted sine carrier-based pulse width modulation scheme has been acknowledged for fundamental fortification in DC–AC conversion. This paper suggests a randomized inverted sine carrier for the half-controlled PWM switching strategy of a three-phase voltage source inverter to enhance its ability to spread harmonic power. A detailed study of the proposed modulation technique is presented through MATLAB-Simulink, and switching pulses are generated in the ModelSim digital environment. Harmonic analyses and assessments of different performance measures such as power spectrum density, harmonic spread factor, total harmonic distortion and dominating harmonic orders for various modulation indices have been carried out. Simulation and experimental results show that the proposed PWM method can spread harmonic power in output voltage better than the conventional SPWM or SVPWM. For real-time digital implementation, the gating signals are generated using a field-programmable gate array Spartan XC3S500E − 320F device.

Assorted carrier‐variable frequency‐random PWM scheme for voltage source inverter

This study presents an assorted carrier-variable frequency random pulse width modulation (AC-VF-RPWM) method in which a new type of mixed carrier wave is proposed for a three-phase voltage source inverter-fed induction motor drive. This study has focused on the reduction of acoustic noise where a deterministic PWM strategy is replaced with a proposed RPWM. Inverted sine carrier, sine carrier and triangle carrier are used to compare with the reference sinusoidal wave to generate the pulse (lead and lag) positions. The two groups (lead and lag) each with three pulse positions are randomly selected and it aims at dispersing the harmonic voltage over a wide band area. The linear feedback shift register-based random bit generation algorithms are used to select the three pulse positions from the lead and lag groups. In addition, a frequency modulator converts the carriers into a randomised frequency, which will give more potency to the randomisation process. The results of co-simulation and experimental evaluation that the proposed method could provide harmonic power spectra of the voltage and current spreading over a much broader band area, as compared with the conventional schemes. In addition, Xilinx XC3S500E FPGA device synthesis results are presented.

Modeling and Control of Quasi Z-source Cascaded H-bridge Multilevel Inverter for Grid Connected Photovoltaic Systems

This paper presents the modeling and controlling the power of Quasi Z-Source cascaded H-bridge multilevel inverter for grid connected photovoltaic systems. The Quasi Z-Source inverter is an inverter that provides buck / boost output along with DC-AC conversion in a single stage. This topology has numerous advantages which makes it reliable and suitable for PV applications. Due to the impedance network and the cascaded H-bridge structure, it provides high gain, reduced total harmonic distortion (THD) and high reliability in PV systems. In this paper, a five level cascaded H-Bridge Quasi Z-source inverter has been considered for which the impedance network has been designed. Phase Shifted Inverted Sine carrier pulse width modulation has been implemented along with shoot- through control for controlling the switches of the inverter. The closed loop power control scheme has been implemented in two stages. In the PV input side, each string voltage is controlled by adjusting the shoot-through states of the inverter using Independent Maximum Power Point Tracking Control. DC link voltage of each bridge has been balanced by using DC link voltage control. Both of these controlling actions result in the control of grid injected power. A 2kVA PV inverter has been designed and built using MATLAB/SIMULINK and the hardware has been completed for the open loop control. The simulation and open loop hardware results are discussed.

Elucidation of Various PWM techniques for a Modified Multilevel Inverter

<p>This paper focuses on hybrid H-bridge cascaded MLI using two equal dc sources in order to produce a five-level output. The proposed topology reduces the number of dc sources and switching elements. This paper emphasis on various Inverted Sine Carrier PWM (ISCPWM) techniques with equal amplitude and unequal amplitude carriers. The Inverted Sine Carrier Pulse Width Modulation (ISCPWM) technique enhances the fundamental output voltage particularly at lower modulation index ranges with reduction in Total Harmonic Distortion (THD) and switching losses. Simulation is performed using MATLAB-SIMULINK. From the simulation it is observed that Variable Amplitude Inverted Sine Carrier Variable Frequency (VAISCVF) strategy provides output with relatively low distortion for all strategies. It is also seen that Variable Amplitude Inverted Sine Carrier Phase Disposition (VAISCPD) is found to perform better for all strategies since it provides relatively higher fundamental RMS output voltage.</p>

Investigation on Harmonic Spreading Effect of Conventional and Innovative Multi-Level Inverter Control Strategies

The pulse width modulation (PWM) strategy employed in the voltage source inverter (VSI) not only control the magnitude of the output voltage but also the quality. Performance evaluations of such strategies are done in terms of fundamental voltage, total harmonic distortion (THD), switching losses etc. (primary indices) and also in terms of acoustic noise, electromagnetic interference (EMI), harmonic spread factor, distribution of harmonic power etc. (secondary indices). Multilevel inverter (MLI) has become unanimous choice in medium and high power applications due to their superior performance compared to three level inverters. The conventional Sub-Harmonic PWM (SHPWM) scheme and its variations offer the output voltage spectrum with high intensity harmonic components around the switching frequency; it will end with cluster harmonic with high acoustic noise. The first objective of this paper is to investigate harmonic spreading effects of existing multilevel inverter (MLI) strategies. Secondly the developing innovative PWM strategies for MLIs based on modified reference and carrier functions, which were proved for superior the primary indices at three-level VSI. Thorough simulation study of Pulse width modulation strategies such as SHPWM, inverted sine carrier PWM, MWM PWM, third harmonic injection PWM, triplen harmonic injection PWM, analog space vector PWM, trapezoidal PWM and discontinuous PWM for a cascaded multilevel inverter, are presented with results of primary and secondary indices. Hence, the PWM strategies of MLI are evaluated for harmonic spreading effect first time and a guide line for a beginner to select the PWM scheme for MLI fed drive systems is stenciled.

Three Phase Hybrid 7-Level Inverter with 60 Degree PWM Scheme for PV Applications

In this paper, a hybrid multilevel inverter (MLI) with reduced number of components is modelled by deriving its source from solar PV array. The power switches of this MLI are controlled by utilizing the pulses derived by comparing the reference and carrier signal. The reference signal for the modulation process is based on 60 degree PWM. The carriers considered for the modulation process are triangular carrier wave and inverted sine carrier wave arranged in phase Disposition (PD) multicarrier method. The output voltage waveform of this hybrid MLI under consideration is analyzed with different performance parameters like Total Harmonic Distortion (THD), RMS Voltage, DC utilization Rate and harmonic spectrum. The simulation results show that the inverted sine based PD technique is yielding better performance than that of other technique. The above mentioned are examined with the help of MATLAB / SIMULINK.

A New Three Phase Seven Level Asymmetrical Inverter with Hybrid Carrier and Stepped Reference

This paper presents new hybrid modulation strategies for the chosen three phase seven level Asymmetrical Multi Level Inverter (AMLI) with Stepped reference. Performance indicesused are Total Harmonic Distortion (THD), Form Factor(FF),Crest Factor(CF),Root Mean Square(RMS) value of output voltage and DC bus utilization. The combination of inverted sine carrier and triangular carrier is used as hybrid carrier to produce triggering pulses for the power switches used in the proposed three phase seven level AMLI. This paper also investigates the potential of using hybrid carrier with the existing strategies such as Phase Disposition Pule Width Modulation (PDPWM),Phase Opposition Disposition PWM(PODPWM),Alternate Phase Opposition Disposition PWM(APODPWM)and Variable Frequency PWM (VFPWM) techniques for carrier. The simulation is done in MATLAB/SIMULINK and the results are presented for all modulation strategies. It is observed that hybrid PDPWM provides relatively better DC bus utilization and creates relatively less distortion for ma=0.7-1

Switching Frequency Optimal PWM Based Three Phase Hybrid Multilevel Inverter

This paper presents the performance analysis of switching frequency optimal (SFO) pulse width modulation technique for a three phase hybrid multilevel inverter. Three phase hybrid multilevel inverter structure comprises of less number of DC sources, power switches and carriers when compared with cascaded H-bridge multilevel inverter. Triangular carrier and inverted sine carrier arranged in phase disposition (PD) and Alternate phase opposition disposition (APOD) are used as multicarriers for generating the pulses. The parameters chosen for the analysis are fundamental output voltage, DC utilization rate and total harmonic distortion. The result analysis reveals that the inverted sine carrier with PD PWM technique provides high RMS output voltage and DC utilization rate which can be utilized for PV array based inverter fed grid applications.

Inverted sine carrier for fundamental fortification in PWM inverters and FPGA based implementations

This paper deals with a novel natural sampled pulse width modulation (PWM) switching strategy for voltage source inverter through carrier modification. The proposed inverted sine carrier PWM (ISCPWM) method, which uses the conventional sinusoidal reference signal and an inverted sine carrier, has a better spectral quality and a higher fundamental component compared to the conventional sinusoidal PWM (SPWM) without any pulse dropping. The ISCPWM strategy enhances the fundamental output voltage particularly at lower modulation index ranges while keeping the total harmonic distortion (THD) lower without involving changes in device switching losses. The presented mathematical preliminaries for both SPWM and ISCPWM give a conceptual understanding and a comparison of the strategies. The detailed comparison of the harmonic content and fundamental component of the ISCPWM output for different values of modulation index with the results obtained for the SPWM is also presented. Finally, the proposed modulator has been implemented in field programmable gate array (FPGA- Xilinx Spartan 3) and tested with the proto-type inverter.

A Novel PWM for Harmonic Reduction and its Application to ac-dc Converters

The paper describes a novel PWM scheme called inverted-sine PWM (ISPWM) which uses a sinusoidal reference and an inverted-sine carrier. The ISPWM, when applied to a rectifier, has a better harmonic elimination and a higher average output voltage compared to a sine PWM (SPWM). The harmonic content of the ISPWM output for different values of the modulation index is computed and compared with that of a SPWM. The complete circuit for generating the ISPWM control signal for single and three phase ac-dc converters is developed. Experimental waveforms of voltages and currents are presented.