Modified Pulse Width Modulation Technique Research Articles

Self-balanced high gain switched-capacitor boosting inverter with lower cost function

ABSTRACT This paper discusses in detail a new 17-level inverter that employs a switched-capacitor (SC)-based configuration. The proposed SC-based inverters require just a single DC power supply, three capacitors, four diodes and 13 switches. The peak inverse voltage of the proposed 17-level SC-based inverter half-bridge is cut in half when compared to the prior arrangement, which was published not long ago. The blocking voltage is reduced by an order of magnitude as well. Many of the features of the proposed SC-based inverter, such as a high boosting gain factor (G) of eight times, self-balanced capacitor voltage and decreased voltage ripples in capacitors, have been carried over to other SC-based MLIs. The circuit description, working theory, PWM modulation techniques and capacitor voltage ripples are all examined. Finally, the results of the experiments show without a doubt that the proposed SC-based inverter can be made.

Simulation and implementation of a harmonics suppression technique for a single-phase full-bridge converters

ABSTRACT This paper presents a harmonic suppression technique for a single-phase full-bridge converter, and the mathematical principles underlying a modified PWM technique are discussed. To verify the effectiveness of the proposed technique, voltage and current sensor circuits in a single-phase full-bridge converter connected to a digital signal processor controller with an analog-to-digital converter were analyzed experimentally. The output voltage harmonics of the converter were examined, and the frequency spectra of the output voltage were analyzed. Furthermore, a digital control system with a TMS320F2808 digital signal microcontroller was realized. The experimental results verified the effectiveness of the proposed technique in suppressing low-frequency harmonic in a prototype of a converter.

Design of Uninterruptible Power Supply Inverters for Different Modulation Techniques Using Pareto Front for Cost and Efficiency Optimization

This work presents a design for uninterruptible power supply inverters using Pareto front optimization for improved cost and efficiency. Three PWM modulation techniques applied to the full-bridge inverter are analyzed. As a result, the best MOSFET design solution in terms of the cost and efficiency of the inverter is evaluated based on a database with 47 power MOSFETs. Using the Pareto front, the optimal and sub-optimal solutions are compared, considering the three modulation techniques and the characteristics of MOSFETs manufactured for different voltage levels. Thermal and electrical measurements are used to validate the models.

Investigation of ZVS Criteria and Optimization of Switching Loss in a Triple Active Bridge Converter Using Penta-Phase-Shift Modulation

Triple active bridge (TAB) as an isolated multiport dc–dc converter is a promising solution for integrated energy management systems to maintain an efficient power flow between the ports. This article presents the design, modeling, and switching loss optimized phase-duty-controlled PWM modulation scheme of a TAB converter composed of three full-bridge modules and a high-frequency planar transformer. The work aims at the derivation and analysis of the zero-voltage switching (ZVS) conditions for a TAB, where the turn-on switching loss is mitigated along with attaining an improved EMI performance, comprising of reduced noise peaks. Moreover, an optimized five-variable control-based TAB PWM modulation technique is proposed in this article in order to achieve minimized switching loss and the overall system loss for a wide voltage gain and load range. The instantaneous switching currents, responsible for the switching losses at the devices, are derived from the transformer winding current expressions, formulated employing the generalized harmonic approximation (GHA) technique. The various loss minimization techniques and the theoretically obtained criteria for ZVS are experimentally verified using a laboratory-developed prototype of an 800-W TAB converter. With the implementation of the proposed optimal phase-duty control, the experimental results show a nonunity gain light-load efficiency increment up to 10% compared to the conventional phase-shift modulation alone.

Comparative Analysis of Modulation Techniques on the Losses and Thermal Limits of Uninterruptible Power Supply Systems.

This paper presents a comparative analysis of electrical losses and subsequent thermal limits of the inverter of UPSs for small office and home office (SOHO) applications. For this, three PWM modulation techniques applied to the full-bridge converter are considered, with power levels of 100–1000 W and switching frequencies of 30–120 kHz. To validate the electrical and thermal models, a dSapce MicroLabBox equipment was used to implement modulation techniques on a commercial 1000 W UPS, and a Keysight DAQ970A data logger was used for temperature measurements. As a result, the MOSFET temperatures and losses are obtained for the three modulation techniques evaluated, indicating the best scenario for use and its influence on the UPS autonomy time.

Minimization of total harmonic distortion in neutral point clamped multilevel inverter using grey wolf optimizer

<span lang="EN-US">The inverter has been attracting researchers for their application in renewable energy. So far, multilevel inverter is considered as low distortion class, which produces multilevel output voltage imitating a pure sine waveform. However, the needs for free distortion of output voltage have been motivating to improve multilevel pulse width modulation PWM generation method. In this paper, the modified PWM technique is proposed to reduce the voltage total harmonics distortion (THD) of multilevel inverter. This modulation technique is then applied to control a single-phase threelevel neutral point clamped multilevel inverter (NPC-MLI). Grey wolf optimizer (GWO) algorithm is utilized to generate optimal amplitude and phase shift of modified reference signal. The GWO algorithm is then compared with other optimization algorithms such as differential evolution (DE), human psychology optimization (HPO), and particle swarm optimization (PSO) to evaluate their performance in harmonic minimization. The performance of the proposed work is validated through simulation and experimentation on a prototype. The results show that the modified PWM technique optimized with GWO can reduce THD on NPC-MLI output voltage.</span>

Performance Analysis of Multi-Carrier PWM and Space Vector Modulation Techniques for Five-Phase Three-Level Neutral Point Clamped Inverter

In industries, the demand for multi-phase Multi-Level Inverters (MLIs) increases as they have reduced switching loss, Common Mode Voltage (CMV) and voltage stress across switches. The Multi-Carrier PWM (MCPWM) and Space Vector Modulation (SVM) techniques are predominantly used for controlling the inverter. This paper discusses various PWM techniques like PD, POD, APOD, IC, PSC, VFC PWM and SVM (OFV and SVM with Zero CMV) for 5-phase NPC 3L Inverter. Each PWM techniques gives better results in voltage THD/ dc-link balancing/ CMV. The SVM is significant for obtaining better performances in all these aspects. The Optimized Five Vector (OFV) which has 113 vectors is preferred than normal SVM as it has inequality relationship between 5-phase voltages. Though, OFV gives better results in terms of higher output voltage and lower NPF, the CMV is not eliminated. To eliminate CMV, 51 vectors that generates Zero CMV is selected to drive the inverter where output voltage and NPF is also improved. However, due to the presence of x-y components the distortion is present. The vectors are further reduced to 31 where the x-y components are neglected to reduce the distortion is proposed in this paper. The performance of the inverter drive is enhanced by applying proposed SVM with 31 vectors. The NPF, CMV and losses are calculated for all PWM techniques, also the THD performances of an inverter is found for various techniques. The simulation is carried out for all PWM techniques and the results are verified by experimental results.

Quasi-Z-Source Inverters in Renewable Power Systems Modeling

This paper is devoted to in-detail demonstrationand description of the overall functionality and deailed processes in every component of quasi-z-source voltage inverter. Expressions for currents and voltages on all elements of the circuit in standard and "shoot-trough" modes are provided. These ratios demonstrate one of the main technological advantages of the quasi-z-source topology: which is the possibility of the voltage reduction on one of the capacitor that forms the quasi-z-circuitry that led to the overall size and weight reduction of the resulting device and additional reliability increase. Matlab calculations,that are provided in the practical part of the article,fully confirmed the theoretical dependencies. At the same time, obtained practical results of the simulation demonstrated the main advantage of the quasi-impedance topology - the ability to provide a continuous current of the input source without zero pauses. That is additionally confirmed by a graphical representation of transients and the spectrum of the output voltage of the inverter. As the second topic of the article, the problem of the control system operating principle selection was discussed. As it was determined in the process of the previous research and practical modeling of the quasi-z-source inverter, providing a switching of the inverter valves on the frequency that equal to the frequency of the desired output voltage, which for the most of the world’s electrical power systems is equal to 50-60 Hz, is leading to a size and mass increase of the quasi-z-source circuitry, according to its design ratios. Additionally, such component are either not represented in the modern electronic components lineup or providing sufficient energy losses that in some design cases could neglect the voltage boost effect of the quasi-z-source circuitry implementation. To overcome discovered limitations, several PWM control methods were suggested. All of them could be divided into two groups: classic and vector PWM methods. Classic methods are based on combination of the basic PWM modulation techniques that are widely used in conventional full-bridge invertors with the insertion of the “shoot-trough” state activation mode. A model of the control system for the classical approach is offered. It is shown that the method of simple control of the state of "breakdown" is based on the placement of time intervals of the inverter in the state of "breakdown" within the normal period of operation of the bridge inverter. The only difference between the models is the inclusion of an additional constant signal exceeding the amplitude of which the carrier leads to the activation of the “shoot-trough” state.In conclusion the discussion on topic of the classic control methods implementation in up-to-date designs and possibility of its combination with a different modern approaches aimed on a quasi-z-source topology parameters modification are provided.

Harmonics resonance elimination technique using active static compensation circuit

The existence of nonlinear loads produces high distortion and low power factor in the power system that leads to get poor power quality. Resonance problem is occurred due to the power system inductances and the compensation capacitors which increases the harmonic distortion. Therefore, it is necessary to prevent the action of resonance even if conventional or modern methods are built to improve the power system quality. In this paper, active static compensation circuit is proposed and designed to have the features of improving power factor, reducing THD, and eliminating the harmonics resonance effect at the same time with different linear and nonlinear load conditions. These features have been performed based on a modified pulse width modulation technique to drive and control the proposed circuit. The originality designed point of this technique is to have ability to operate the active static compensation circuit as harmonics injector, power factor corrector and resonance eliminator at the same time. Simulation model results illustrate that the proposed circuit is effective for both steady-state and transient operations conditions. The THD of the supply voltage and current at firing angle (α=300) is reduced by 99% and 98.8% respectively. While the power factor is improved to stay around unity.

Carrier-Based Modulated Model Predictive Control Strategy for Three-Phase Two-Level VSIs

The implementation of finite-control-set model predictive control (FCS-MPC) in voltage source inverters (VSIs) can make the system suffer from poor current harmonics performance, which may complicate the design of the required AC filter. To overcome this shortcoming, a carrier-based modulated model predictive control (CB-MMPC) strategy is proposed in this paper. This method enables the utilization of existing PWM modulation techniques with FCS-MPC, where a modulation waveform with zero-sequence signal injection is generated and compared to a triangular carrier wave, while optimizing the selection of the switching states. As it is shown, the studied CB-MMPC strategy not only considerably improves the current total harmonic distortion (THD) but also attains the performance of fast current dynamic response and robustness as the traditional FCS-MPC. Herein, the detailed implementation of the CB-MMPC control strategy is given, while considering its application to the current feedback control loop of a three-phase three-wire two-level VSI modulated at constant switching frequency. Finally, PLECS circuit simulation and a 3-kW VSI prototype are used to verify the superiority and the effectiveness of the presented CB-MMPC strategy. This is also benchmarked to the FCS-MPC and dead-beat based controllers.

Prediction of DC-Link Voltage Switching Ripple in Three-Phase Four-Leg PWM Inverters

This paper presents a thorough prediction of DC-link voltage switching ripples in the three-phase four-leg inverters operating in balanced and unbalanced working conditions. The unbalanced modes examined here employ the highest degree of AC current imbalance while still preserving three-phase operation. This behavior can be found in many grid-connected or standalone grid-forming three-phase converters that supply “heavy” single-phase loads, comprising a recent trend in smart-grid, smart electric vehicle (EV)-charging applications. In this sense, for instance, the smart EV chargers might be employed in conditions when different power is drawn/injected from/to the grid, providing power conditioning services to the latter. The analysis of three-phase four-leg inverters is then extended to single-phase operations typical of home-charging or vehicle-to-home (V2H) applications. Their performances in terms of DC-link voltage switching ripple are demonstrated. Two of the most common carrier-based PWM modulation techniques are employed to drive the three-phase inverter—namely, sinusoidal PWM and centered PWM (carrier-based analogy of the space vector modulation). The derived mathematical expressions of peak-to-peak and RMS values of DC-link voltage switching ripple for balanced and unbalanced conditions are handy for designing the associated DC-link capacitor and estimating the overall efficiency of the converter. Extensive numerical simulations and experimental tests have been performed to validate the presented analytical developments.

Design of a Simplified 7 Level Inverter

In this paper a multi-stage inverter new configuration to growth the quantity of tiers switching voltage the usage of less studied. The proposed inverter includes H-bridge cells in conjunction with an active rectifier and switches. Using PWM modulation technique and collective enter dc supply capacitor series. The validity of the inverter is projected completed using MATLAB software program simulation tools and additionally the applicable theoretical evaluation executed. Capacitor voltage imbalance conquer by way of presenting a modified switching method.

A Review of the EMI Mitigation Techniques in Power Converters

Electrical and electronic technology is being widely deployed which have both beneficial and pervading impacts on day-to-day life. Electromagnetic Interference is the most prominent impact which affect performance of devices. Consequently, dealing with EMI has become a responsibility for engineers and scientists. EMI can emanate from natural and man-made sources. Power converters are the main man-made source, which produce EMI due to its high frequency switching action. To address EMI, electromagnetic compatibilty(EMC) standards are setforth. EMI mitigation measures commonly used are employing filters and electromagnetic shielding devices. Due to various drawbacks pertaining to its exogeneity, other methodologies are put forward to make device adhere to EMC standards. This paper focuses on providing an overview on the state of the art of traditional EMI suppression technologies,the use of chaos theory ,chaos control and spread spectrum techniques to reduce EMI. The paper envisages on PWM modulation techniques to mitigate EMI in power converters by spreading EMI peaks over a wide frequency range to weaken its strength(dB/Hz). These modulation techniques include Chaotic modulation, and Spread spectrum frequency modulation(SSFM).

English

2 ABSTRACT: A PWM technique is used to achieve the low total harmonic distortion (THD) at the output of inverter during the construction of pulses to the converter switches. By using PWM modulation techniques we can minimize harmonics generated by the PWM technique itself. First, we present converter topology characteristics with PWM techniques. Then we describe how a suggested modulation minimizes harmonic generated by switching operation, the inductive nature of the DC source and external point at which the converter is connected. As compared with the previously modulation technique, a suggested modulation achieves the THD is less than 6%.

English

The objective in this paper is to study the operating modes and analysis of the Switched Boost Inverter (SBI). The performance of the proposed SBI is similar to that of Z-Source Inverter (ZSI). In comparison to the ZSI, the present topology results in lower volume and lower cost since it reduces the number of passive component. This feature makes it more suitable for low power applications than ZSI. For the proper operation of the inverter, with special consideration to its operating principle (shoot-through i.e., conduction of two switches on the same leg of the inverter), a modified PWM control strategy is also described in detail. In addition, mathematical relations between various performance parameters under this modified PWM technique have been described in detail. Simulation is carried out using Matlab/Simulink software to verify the theoretical analysis made. This report also presents a laboratory prototype of the Switched boost inverter along with it results.

Comparison of MPC and PI Controller for Grid-Connected Cascade Inverter

The paper describes and compares the dynamic performance of the PI and the MPC controllers used with the one-phase multilevel cascade inverter connected to the grid through an LCL filter. The cascade inverter uses multilevel sinusoidal PWM modulation technique and is controlled in rotating reference frame. The PI controller uses active damping using virtual resistance to damp oscillations of LCL filter. The MPC controller results present its ability to stabilise unstable plants and no additional active damping technique is necessary to stabilise the LCL filter. Both controllers have the same sampling time. DOI: http://dx.doi.org/10.5755/j01.eee.20.6.7266

Trapezoidal PWM with Direct Modulation Technique (TPWM-DM) Using a Low Cost Microcontroller with High Signal Quality for Power Inverters

This paper presents a high signal quality PWM modulation technique for power inverters that can be implemented by means of a low cost microcontroller. The proposed modulation technique is a mixture between generated and calculated techniques that allows the voltage and frequency of the output signal to be modified on line within a broad margin. Moreover, the quality of the signals generated exceeds that of already existing modulation techniques; hence, better performance is achieved in the system as a whole, reducing the size of the filters at the inverter output which represents an important cost reduction. Additionally, the implementation by means of a low cost microcontroller helps to reduce the cost of the final application.

New Hybrid Cascaded Multilevel Inverter

A B S T R A C T This paper proposes a single-phase five-level inverter with a modified pulse width- modulated (PWM) control scheme. The modified pulse width-modulation technique is developed to reduce switching losses. Also, the proposed multilevel inverter can reduce the requirement of power switches compared to a conventional cascaded multilevel inverter. The modes of operation, control signals, and operating principle of the proposed inverter are analyzed. The inverter is capable of producing five levels of output- voltage (Vs, V s/2, 0, − Vs, − Vs/2) from the dc supply voltage. In particular, aspects of total harmonic distortion (THD) for the proposed multilevel converters are discussed. The hybrid cascaded H-Bridge inverter with very low switching losses is ideal for such operations. The behaviour of the inverter has been analyzed with the simulation and experimental results. In this paper a new five level inverter with reduced number of switches is pr oposed and MATLAB/SIMULINK results are presented.

COMPARATIVE STUDY OF HYBRID AND CASCADED H-BRIDGE MULTILEVEL INVERTERS

In this paper comparative study of proposed hybrid multilevel inverter (HMI) operating in modified pul se width modulation (PWM) mode with cascaded H-bridge multilevel inverter (CH MI) is done. Two types of HMIs are proposed with sa me configuration. To control the two HMIs, modified PWM techniques are dfrom sinusoidal pulse width modulation (SPWM ) to reduce the switching losses in the inverter. Matlab/Simulink models are used to study the output of HMI and CHMI.

A Carrier-Based PWM Modulation Technique for Balanced and Unbalanced Reference Voltages in Multiphase Voltage-Source Inverters

The advancement in power electronics has made the use of any number of phases in ac machines possible since with the inverter, any number of phase voltages can be realized as long as the corresponding inverter exists. To supply multiphase drives requires multiphase voltage source inverters (VSIs) whose output voltages depend very much on the methods of generating the pulses to turn on and turn off the inverter devices appropriately. This paper presents an analytical technique for the determination of the expressions for the modulation signals used in the carrier-based sinusoidal and generalized discontinuous pulse width modulation schemes for two-level, five-phase voltage source converters. These expressions can be used for both balanced and unbalanced phase voltages generated by any two-level multiphase inverter, in generating the required reference signals appropriately. An example of a five-phase VSI is presented to illustrate the strategy. Simulation and experimental results are presented in which a close examination shows that both results are similar for the balanced and unbalanced load voltage cases.