Digital Sinusoidal Pulse Width Modulation Research Articles

Generalized Accurate Harmonic Calculation Method Based on Discretized Double Fourier Series to Solve Double-Pulse Phenomenon

Harmonic issues have always been paid attention to in electrical systems, and accurate calculation of the amplitude and phase of each harmonic has become one of the research focuses of scholars. This article develops a generalized harmonic closed-form analytical solution for a single-phase voltage source inverter (VSI) under digital sinusoidal pulse width modulation (DSPWM) and dead-time effects. This article is the first to point out the double-pulse phenomenon that can occur when using a double Fourier series to solve the harmonic spectrum due to the discontinuity of the dead-time effects and half-cycle integrals. Analysis and data comparison shows that this phenomenon can affect the accuracy of harmonic calculations. An discretized double Fourier series method is proposed to solve this phenomenon. Moreover, the problems of missing pulse caused by the modulation under a specific current phase and current zero-crossing are also solved, improving the harmonic calculation's accuracy and generality. Simulation analysis and the results of inverse fast Fourier transform (IFFT) proved the correctness of the optimization method. And the experimental results are obtained on the DSP and SIC platforms, which are in good agreement with the expression calculation results

Metode Sederhana untuk Mengendalikan Inverter 5-Tingkat Berbasis Algoritma ¼ λ

The inverter with low voltage harmonics on the output side is a very interesting topic, and widely studied. One of these solutions is a 5-levels inverter: Dual Buck DC-DC Converter - H Bridge Inverter (DBC-HBI). The inverter control methods based on digital sinusoidal pulse width modulation (DSPWM) are commonly implemented by one or a half of the wavelength algorithm (λ). However, one period could be constructed by combining four algorithms by ¼ λ. In this paper, an algorithm of DSPWM based on a ¼ λ algorithm is investigated. The aim of this research is the simplest control and capacities of memory. Finally, a verification of the proposed method was carried out by the experiment in the laboratory. Based on the laboratory tests: 1 λ algorithm has a simple algorithm, but uses large memory, whereas a ¼ λ algorithm more complicated but uses less memory.

THD Reduction in Distributed Renewables Energy Access through Wind Energy Conversion System Integration under Wind Speed Conditions in Tamaulipas, Mexico

In this article, a technique for the reduction of total harmonic distortion (THD) in distributed renewables energy access (DREA) composed of wind turbines is introduced and tested under the wind speed conditions presented in Tamaulipas, Mexico. The analysis and simulation are delimited by a study case based on wind speeds measured and recorded for one year at two highs in the municipality of Soto La Marina, Tamaulipas, Mexico. From this information, the most probable wind speed and the corresponding turbulence intensity is calculated and applied to a wind energy conversion system (WECS). The WECS is composed of an active front-end (AFE) converter topology using four voltage source converters (VSCs) connected in parallel with a different phase shift angle at the digital sinusoidal pulse width modulation (DSPWM) signals of each VSC. The WECS is formed by the connection of five type-4 wind turbines (WTs). The effectiveness and robustness of the DREA integration are reviewed in the light of a complete mathematical model and corroborated by the simulation results in Matlab-Simulink®. The results evidence a reduction of the THD in grid currents up to four times and which enables the delivery of a power capacity of 10 MVA in the Tamaulipas AC distribution grid that complies with grid code of harmonic distortion production.

Design and digital implementation of power control strategy for grid connected photovoltaic inverter

<p class="Abstract">This paper presents the optimization design and a detailed implementation in FPGA (Field-Programmable Gate Array) of a power control strategy. This strategy is based on the phase shift angle of the inverter output voltage with respect to the grid voltage and DSPWM (Digital Sinusoidal Pulse Width Modulation) patterns “Phase shift angle-DSPWM” for an inverter for photovoltaic system connected to the grid. The proposed control can synchronize a sinusoidal inverter output current with a grid voltage and control the power injected into the grid. Detailed development of a digital controller with lower hardware and computation requirement is proposed. Description on the digital implementation of the A/D converter, the PI compensator, the phase shift and the DPWM, is provided. This digital control exhibit simplicity, reduction of the memory requirements and power calculation for the control. The functional structure of this system with digital control has been validated with simulations and experimental results.</p>

THD Reduction in Wind Energy System Using Type-4 Wind Turbine/PMSG Applying the Active Front-End Converter Parallel Operation

In this paper, the active front-end (AFE) converter topology for the total harmonic distortion (THD) reduction in a wind energy system (WES) is used. A higher THD results in serious pulsations in the wind turbine (WT) output power and several power losses at the WES. The AFE converter topology improves the capability, efficiency, and reliability in the energy conversion devices; by modifying a conventional back-to-back converter, from using a single voltage source converter (VSC) to use pVSC connected in parallel, the AFE converter is generated. The THD reduction is achieved by applying a different phase shift angle at the carrier of digital sinusoidal pulse width modulation (DSPWM) switching signals of each VSC. To verify the functionality of the proposed methodology, the WES simulation in Matlab-Simulink® (Matlab r2015b, Mathworks, Natick, MA, USA) is analyzed, and the experimental laboratory tests using the concept of rapid control prototyping (RCP) and the real-time simulator Opal-RT Technologies® (Montreal, QC, Canada) is achieved. The obtained results show a type-4 WT with a total output power of 6 MVA, generating a THD reduction up to 5.5 times of the total WES current output by Fourier series expansion.

DSPWM multilevel technique of 27-levels based on FPGA for the cascaded DC/AC power converter operation

Summary In this paper, a digital sinusoidal pulse width modulation (DSPWM) multilevel technique of 27-levels based on field programmable gate array (FPGA) is introduced, as an alternative to control of the direct current/alternating current multilevel power converters. The implementation of this technique with an FPGA XC3S500E model is achieved in the Xilinx Spartan-3E FPGA platforms. An experimental prototype is implemented by 3-cascaded H-bridges controlled by the DSPWM multilevel technique, generating high efficiency, low cost, and lower harmonic content. The efficiency of the DSPWM multilevel technique using R, RL, RC, and RLC loads connected to the power network is verified.

Sampling Effect Characterization of Digital SPWM of VSI in Time Domain

This paper characterizes the sampling effect in digital sinusoidal pulse width modulation (SPWM) of voltage source inverter (VSI). The time-domain analysis presented in this paper establishes the relation between the fundamental frequency, carrier frequency, and the sampling frequency at different modulation indices of the SPWM. The analysis investigates the effect of sampling frequency of the digital controller on the output of the VSI. It is shown that the low-frequency harmonic components appear in the frequency spectrum of the VSI output voltage due to sampling. As a result, the output current of digitally controlled VSI is stepped in nature. The double Fourier integral solution of the switched waveform for inner and outer integral limits has been used to derive the expression. The integral solution is obtained using Jacobi-Anger expansions. The generalized results developed in this paper are useful to investigate the sampling effect in high switching frequency DSPWM. The proposed sampling effect has been analyzed for SPWM of single-phase H-bridge inverter. The analytical results are verified using simulation and experimental results. The experimental results have been obtained with the use of field-programmable gate array (FPGA) as a digital controller.

Power control for grid connected applications based on the phase shifting of the inverter output voltage with respect to the grid voltage

In photovoltaic (PV) systems connected to the grid, the main goal is to control the power that the inverter injects into the grid. According to the grid demands, injected power does not only include the control of the active power, but also the control of the injected reactive power. This paper presents, a digital control strategy based on the phase shifting of the inverter output voltage with respect to the grid voltage, in order to control the power factor with a minimum number of Digital Sinusoidal Pulse Width Modulation (DSPWM) patterns and for a wide range of the inverter output current. This proposed method has been described, simulated and validated by experimental results.The proposed control strategy requires few hardware and computational resources. As a result, the inverter implementation is simple, and it becomes an attractive solution for low power grid connected applications.

Possible analogy between the optimal digital pulse width modulation technology and the equivalent optimisation problem

A novel nonlinear searching method, immune algorithm (IA), is presented based on the immune theory in biology. This method is applied to resolve the optimal control problem of the sinusoidal pulse width modulation (SPWM) inverter, and the IA is adopted to find the optimal digital SPWM control sequences. Furthermore, the IA well fits with on-line microprocessor implementation. A single-phase full-bridge inverter is considered, and the optimal digital SPWM control sequences are calculated to minimise total harmonic distortion of output waveform. These digital sequences are used in a simulation system and experiment setup to verify the usefulness of the method.

Digital sinusoidal PWMs for a micro-controller based single-phase inverter, Part 1: Principles of digital sinusoidal PWM generation

Nowadays, Digital Sinusoidal Pulse Width Modulation (DSPWM) is playing a major role in the generation of pure sinusoidal waveforms using micro-controller based inverters (Kawabata, Miyashita and Yamamoto 1991; Herrmann, Langer and Broeck 1993; Ying-Yu 1995; PICREF-1 1997; Shih-Liang, Meng-Yueh, Jin-Yi, Li-Chia and Ying-Y 1999; The Electrical Engineering Handbook 2000; Koutroulis, Chatzakis, Kalaitzakis and Voulgaris 2001; Skvarenina 2002; Pop, Chindris and Dulf 2004; Zhongyi, Mingzhu and Yan 2005). The types of DSPWM that can be generated depend on the micro-controller hardware resources and are therefore limited, but provide performance benefits not possible with an analogue controller. For instance, digital controllers offer a programmable solution and therefore more flexibility, as advanced algorithms and additional features can be added to the system in software instead of hardware (Monti, Santi, Dougal, and Riva 2003; Brush 2005). Digital controllers are also less sensitive to environmental conditions and show precise behaviour compared with their analogue counterparts (Skvarenina 2002). This two-part article looks at the benefits and limitations of three major DSPWMs for a single-phase full-bridge inverter and investigates their performance. In Part 1, the theory of the three major DSPWMs are presented, including mathematical models and simulation results. It looks at the PWM patterns required to generate these DSPWMs and the benefits and limitations of each. To evaluate the proposed mathematical models and simulation results, a 2kVA single-phase full-bridge inverter was developed and the DSPWMs implemented. In Part 2, experimental results from the implementation of the DSPWMs on the prototype 2kVA inverter are presented, which confirms the validity of the proposed analysis in Part 1. Moreover, the performance, including efficiency and losses (switching, conduction, and transformer) of the different DSPWMs implemented on the 2kVA inverter under different loads were examined and recommendations presented.

Digital power factor control and reactive power regulation for grid-connected photovoltaic inverter

The overall efficiency of photovoltaic (PV) systems connected to the grid depends on the efficiency of direct current (DC) of the solar modules to alternate current (AC) inverter conversion. The requirements for inverter connection include: maximum power point, high efficiency, control power injected into the grid, high power factor and low total harmonic distortion of the currents injected into the grid. An approach to power factor control and reactive power regulation for PV systems connected to the grid using field programmable gate array (FPGA) is proposed. According to the grid demands; both the injected active and reactive powers are controlled. In this paper, a new digital control strategy for a single-phase inverter is carried out. This control strategy is based on the phase shift between the inverter output voltage and the grid voltage, and the digital sinusoidal pulse width modulation (DSPWM) patterns, in order to control the power factor for a wide range of the inverter output current and consequently the control and the regulation of the reactive power will be achieved. The advantage of the proposed control strategy is its implementation around simple digital circuits. In this work, a simulation study of this strategy has been realized using Matlab/Simulink and PSIM. In order to validate its performance, this control has been implemented in a FPGA. Experimental tests have been carried out demonstrating the viability of this control in order to control the power factor and the injected power into the grid.

Digital SPWM synthesis for the design of single phase inverters†

This paper presents an all-digital concept for sinusoidal pulse-width modulation (SPWM) generation that uses modern arithmetic algorithms to impose a sinusoidal variation of the switching pulses that control the power transistors of a single-phase inverter, thus improving the linear characteristics of the inverter output signal. The developed modulation strategy is given a mathematical description, which can then be modelled and synthesised on field programmable gate arrays (FPGAs). The only existing harmonics present within the spectrum of the final signal are the multiple of the switching frequency. The order of these harmonics is so high (switching frequency related with output frequency sidebands), that a filter can easily be designed to reject these frequencies. The ability to accurately control the output characteristics of the inverter within 1% and also maintain less than 1% harmonic distortion, demonstrates the feasibility of the digital synthesiser.