Pulse Width Modulation Control Strategy Research Articles

Analysis and Control of Current-Fed Integrated Dual-DC Boost Converter Topology

This article introduces a dual-input single-output dc–dc power electronic converter topology to interface two independent sources into a common output. The proposed converter is denoted as integrated dual-dc boost converter (IDDBC), and this topology provides step-up conversions for both inputs using three controllable switches. Due to its architecture, IDDBC can be adapted to provide uninterrupted power (realizing a dispatchable system) even if any one of the two input sources are unavailable or has significant output power variation. The steady-state analysis, modeling, and design of the converter are presented, and a pulsewidth-modulation control scheme is proposed. The closed-loop control system for the converter consists of voltage-mode control for output and current-mode control for one-source input current. The behavior of converter operation is validated through experimentation on a digital-signal-processor-based laboratory prototype.

Optimized Harmonic Reduction PWM based Control Technique for Three-Phase quasi Z-Source Inverter

This paper proposes an optimized harmonic reduction pulse width modulation (HRPWM) control strategy for three-phase quasi Z-source inverter (qZSI). In traditional sinusoidal or space vector pulse width modulation techniques, the flexibility in adjustment of individual switching angles is not possible and thus, these techniques are not optimum choices for low switching frequency operations of high/medium power qZSI. In the proposed technique, adjustments of switching angles of HRPWM waveform are possible to achieve optimum performance. The optimum performance is targeted as maximization of boosting factor and simultaneous minimization of weighted total harmonic distortion (WTHD) at the output voltage of qZSI. The hybrid particle swarm optimization gravitational search algorithm (PSOGSA) is used for computation of optimum switching angles of suggested HRPWM waveform at various modulation indices. The obtained WTHDs up to 49th order harmonics and boosting factors of optimized HRPWM methodology are compared with that of the maximum boost control (MBC) technique for qZSI to justify superior performances of the suggested method in low switching frequency range. The proposed concept has been verified via simulation study. The experimentation (qZSI controlled by microcontroller) validates the working of optimized HRPWM based qZSI which agrees with software results.

Selected harmonic elimination‐derived multi‐frequency pulse width modulation control strategy for multi‐load MCR WPT system with single transmitting coil

Magnetically coupled resonant wireless power transfer (MCR WPT) has become the research focus in recent years because of its safety, simplicity and high efficiency. In multi-load applications, the ‘one-to-one’ charging scenario is difficult to meet the requirement of load diversity, and the development of the ‘one-to-many’ charging has become increasingly important. In this study, a multi-load MCR WPT system with single transmitting coil and multiple receiving coils was investigated. To discriminate the loads for targeted power distribution, each receiving coil cascaded by the load is designed to operate at an individual frequency. For this purpose, a single-phase full-bridge inverter and a multi-frequency pulse width modulation (MFPWM) control strategy were used to generate a multi-frequency mixed excitation voltage that servers as the input of the single transmitting coil. In view of the different voltage features, two control modes defined as the unipolar and the bipolar modes were presented, and the characteristics of these two modes were analysed. To further reduce the harmonic content in the voltage waveform, a phase-shifted MFPWM control strategy was proposed, and the design guideline of the phase-shifted angle was given. Finally, a dual-load MCR WPT system was taken as an example for the experimental verification, which confirms the correctness and effectiveness of the proposed control strategies.

Analysis of Z-Source Inverter fed Asynchronous Motor for Electric Vehicle Applications

ELECTRIC VEHICLES are first introduced in 19th century but at the beginning, performance of electric vehicles is very poor in efficiency, speed, cost, controlling the vehicle. During this period IC engines plays major active role in transportation and even if the electric vehicles are having the above mentioned drawbacks, but extensively used in electric locomotives and various applications. There is a gradual incising the cost of petroleum products again the research looking back into electric vehicles. But the fast development of power electronics and the battery management system and the reduced size of battery push forward towards the progress of electric vehicles. Due to the drastic improvement in power electronics region the controlling of electric vehicles are become easy and the charging time also reduced drastically. In conventional Voltage and current source inverters, a voltage stress across the power switches is a biggest concern to improve the system efficiency. To limit the drawbacks of classical converters, in this work an impedance source inverter fed asynchronous motor is proposed. In turn control the electric vehicle operation both in accelerating and decelerating periods. The proposed inverter controlled various pulse width modulation control strategies and corresponding Total harmonic distortion analyzed. The DC link Voltage regulation, stator and rotor currents, torque and speed of the proposed asynchronous motor drive performance for the designed EV setup have been investigated through MAT LAB simulation.

A SVPWM Control Strategy for Capacitor Voltage Balancing of Flying Capacitor Based 4-Level NPC Inverter

A Space Vector Pulse Width Modulation (SVPWM) control strategy is implemented for capacitor voltage balancing of Flying Capacitor (FC) based 4-level Neutral Point Clamped (NPC) inverter. This flying capacitor based 4-level NPC inverter is developed for medium voltage and high power applications. This system includes 6 power switching devices, 2 clamping diodes and 2 flying capacitors per leg. The flying capacitors ensure to operate inverter normally and all the switching devices share the voltage stresses in identical manner. Also it controls the voltage across each capacitor and maintained at Vdc/3 times of applied dc voltage. The proposed SVPWM method takes advantage of utilizing redundancy switching states to control and balance the voltage across the capacitor using nearest switching state vector selection method. Moreover, this system provides reduced total harmonic distortion (THD), and minimized voltage stress. The control technique is implemented without using any look-up tables or effective logic tables or trigonometric functions. The simulation and experimental results of this proposed verified are verified using Matlab-simulink and FPGA controller respectively.

Multi‐frequency averaging (MFA) model of a generic electric vehicle powertrain suitable under variable frequency of averaging developed for remote operability

Geographically distributed hardware-in-the-loop (HIL) testing has the potential to allow hybrid vehicle powertrain components (battery, motor drive, and engine) to be developed at geographically remote locations but tested concurrently and coupled. Inter-location internet communication links can allow non-ideal behaviour observed in a physical component in one location (e.g. an electrical drive) to be imposed on another physical component elsewhere (e.g. an ICE), and vice-versa. A key challenge is how to represent the behaviour of a remote, physical component under testing in a local HIL environment. Internet communications are too slow and unreliable to transmit waveforms in real-time and so one solution is to use a local ‘slave’ model whose behaviour and parameters are tuned based on observations at the remote location. This study proposes a multi-frequency averaging (MFA) slave model of an electric motor drive system for use in this application; it addresses a weakness in previously published work by extending the MFA model to variable frequency operation. The model was benchmarked against experimental operation (and its equivalent simulation model) in open-loop and closed-loop space vector pulse-width modulation control strategy, fixed and variable frequency operation. Results show significant reconciliation of model and experiment.

Resonant LLC DC–DC Converter Employing Fixed Switching Frequency Based on Dual-Transformer With Wide Input-Voltage Range

In this article, a dual-transformer-based LLC resonant converter is proposed, which is a hybrid combination of a full-bridge and half-bridge LLC circuits. The output voltage is regulated through fixed-frequency phase-shift pulsewidth modulation control scheme, whereas the switching frequency is equal to the resonant frequency, which helps to design the magnetic components. The turns-ratio design of the two transformers is analyzed by the current stress and power distribution of both transformers with two different cases. The proposed converter is capable of realizing soft switching over wide input-voltage and whole load range. Finally, a prototype converter of 1 kW is built and the experiments are conducted under wide input-voltage and full load range. The experimental results show that the proposed converter can achieve high efficiency throughout the full load range.

SVPWM control strategy for a three phase five level dual inverter fed open-end winding induction motor

A Space Vector Pulse Width Modulation (SVPWM) control strategy is proposed for a three phase five level dual inverter fed open-end winding induction motor. This system includes 2 three level Neutral Point Clamped (NPC) inverters, which is supplied by two isolated dc power supplies. The conventional SVPWM has more complexity in reference vector identification and switching time calculation. The reference vector for proposed five level SVPWM scheme is tracked using three level voltage vector and offset voltage, where 5-level hexagonal region is divided into seven 3-level hexagonal regions. The proposed SVPWM leads to reduce the complexity in switching time calculation, Total Harmonic Distortion (THD) reduction, Minimization of Common Mode Voltage (CMV) and low voltage stresses across the switching devices. Also this system estimate the phase current of the five level dual inverter fed open-end winding induction motor. The results obtained using simulation and hardware are compared and verified using Digital Signal Processor.

Dual PWM Control for High Step-Down DC-DC Converters

The conventional step-down dc–dc converters under the single pulsewidth modulation (PWM) control scheme may not provide enough step-down voltage conversion capabilities with considering the minimum on -time and the switching frequency of the power switch. In order to overcome this difficulty, a dual PWM control scheme for designing the high step-down dc–dc converter is proposed in this article. Both high-frequency and low-frequency PWM waveform generators are utilized in synthesizing the dual PWM control of buck converters. The resulting PWM waveform will lead to various switching cycles, and five operating modes of the buck converter, which can be defined accordingly. The operation principle of the proposed converter and its small-signal switched model are presented in detail. One salient feature of the proposed design is that if the duty cycle of the high-frequency PWM is exactly equal to that of the low-frequency PWM, by exploring the volt–second balance condition, the voltage gain can be expressed as the quadratic formula of the duty cycle of the PWM signal when power switches are operated under the continuous conduction mode. Thus, a high step-down conversion ratio and significant reductions of the inductor current ripple can be ensured simultaneously. Since no modifications of the conventional circuit topology are made, the proposed scheme is very cost-effective. Simulation studies and hardware prototype circuit implementations are conducted to validate the proposed design with satisfactory performance.

Performance Optimization for Closed Loop Control Strategies towards Simplified Model of a PMSM Drive by Comparing with Different Classical and Fuzzy Intelligent Controllers

In this proposed work, a substantial comparative performance optimisation has been established between the PI, lead, lead-lag and fuzzy logic controllers towards the closed loop control strategies of a simplified permanent magnet synchronous motor (PMSM) drive. By the introduction of sinusoidal pulse width modulation (PWM) control strategy, it is expected that the nature of armature current would be nearly sinusoidal and generated torque ripples will be lesser. In this proposed structure of a PMSM drive, the speed reference has been incorporated with a speed controller to fortify that the exact speed of the proposed motor match with the base speed with null speed error. The overall structure of the PMSM drive is separated into two loop control structure, inner current loop and outer speed loop. All the necessary performance indices of the proposed PMSM drive system are tested in a MATLAB/Simulink environment. Moreover, the performance of a fuzzy logic speed controlled PMSM drive as compared to all classical controllers provides better dynamic as well as steady state performance with reduced torque ripples. Therefore, the entire performance of the proposed simplified PMSM drive in closed loop control strategy is executed and efficacy of controllers is resolved under various operating conditions. Hence, the superiority of intelligent speed controller (fuzzy logic controller) for this proposed PMSM drive model over all classical controllers is validated and optimised for high performance applications. Finally, an auto-tuning control strategy for the fuzzy intelligent speed controller is also proposed for optimal operation of the drive system.

Pv-Fc Systems Fed Multilevel Inverter by Employing Pi Controller

This paper presented a seven level Photovoltaic (PV) solar cell system & Fuel cell designed in support of grid connected network by employing Pulse Width Modulation control scheme. The input power source comprises of PV source & Fuel cell. Modified MPPT algorithm (P&O) is use just before take out the maximum control from Photo voltaic system. The structure of the circuit is multi modular towards convert dc input voltages to dc output voltages among low rate devices at low duty cycle. A Proportional Integrate controller is to be implementing for multilevel inverter operating & closed loop analysis is done. One reference signal is to be impossible to tell apart to each other by means of an balance equivalent towards the triangular signal are used to make PWM signals intended for the switch. In the Proposed system will be verified during MATLAB/Simulink. The tentative result is compared among the predictable distinct phase seven level grids connected with Pulse Width Modulation generator.

Power Quality Performance Evaluation of Multilevel Inverter With Reduced Switching Devices and Minimum Standing Voltage

Multilevel inverters (MLIs) have been extensively employed to improve the power quality of the photovoltaic (PV) systems. However, the need for large number of components, higher standing voltage, and high harmonic content in the output of a conventional MLI greatly affects the system efficiency. Asymmetrical MLIs have been therefore developed as a suitable alternative to address these issues. This article aims at developing such a hybrid asymmetrical structure suitable for PV application that has a high level per component ratio and minimum standing voltage. The proposed MLI is assembled using a reduced switch H-bridge-based (RSHB) MLI structure with n asymmetrical repeating units and different level doubling circuit (LDC) combinations. The two dc sources used in the repeating units are in the ratio of 1: n voltage ratio, and using n such units, the proposed MLI structures, i.e., PS1 and PS2 can synthesize 4 n + 5 and 4 n + 7 levels, respectively, at the output instead of 2 n + 3 levels with only RSHB MLI. Comparative analysis reveals that both PS1 and PS2 have fewer switches, low standing voltage, less power loss, and lower cost. A 3.9-kW standalone solar PV system is considered for performance evaluation of the PS1 structure applying both the selective harmonic elimination and carrier-based pulsewidth modulation control schemes. In light of this, dc-link voltage balancing and self-voltage balancing mechanism of the LDC are warranted. Extensive simulation of the proposed MLI is performed in MATLAB/Simulink platform under a change in modulation index, sudden load change, frequency change, and step change in solar insolation. Furthermore, theoretical and simulation findings are validated experimentally by performing similar tests on a prototype of the proposed 17-level MLI.

Neutral-Point Potential Balancing Control Strategy for Three-Level ANPC Converter Using SHEPWM Scheme

A selective harmonic elimination pulse width modulation (SHEPWM) control strategy is proposed to balance the neutral-point potential (NP) of a three-level active neutral-point-clamped (ANPC) converter. In this strategy, the chaotic ant colony algorithm (ACA) is adopted to solve the SHEPWM nonlinear equations, which does not require presetting the initial values of solutions and can get multiple solutions in the same modulation index. The influence of different solutions corresponding to the SHEPWM switching states on the NP is different, namely, some make the NP increase and others make the NP decrease. Therefore, the NP balancing can be effectively controlled by choosing appropriate solutions in different fundamental periods. The simulation and experimental results further verify the feasibility and effectiveness of the control strategy.

New modulation scheme and voltage balancing control of modular multilevel converters for modern electric ships

The distinctive features such as fault-tolerability, modularity, power and voltage scalability have propelled modular multilevel converters (MMCs) as one of the emerging power converter topologies for marine applications. Pulse-width modulation (PWM) schemes are widely used to control the MMCs due to their good control capability and ability to operate at higher switching frequencies. However, the required number of carriers for gating signal generation drastically increases with the submodule count per arm in an MMC. Moreover, these carriers should be accurately synchronised with each other to generate high power quality waveforms. However, it is hard to establish accurate synchronisation between these carriers due to the sampling issues, memory limitations, and computational delays. In addition, the MMC demands reconfiguration of PWM carriers and control strategy for voltage scalability and retrofit applications. To avoid these issues, a simple PWM scheme using one carrier is proposed in this study. The main advantage of the proposed scheme is an easy extension to the n -level MMC with a wide range of output voltage levels. The effectiveness of the proposed PWM scheme along with the capacitor voltage balancing control is demonstrated through detailed simulations and verified experimentally under steady-state and dynamic conditions.

SiC‐based active quasi‐Z‐source inverter with improved PWM control strategy

In this study, an improved pulse width modulation (PWM) scheme was proposed for an active quasi-Z source inverter (AqZSI). Compared to the quasi-Z-source inverter (qZSI), the AqZSI with improved PWM strategy can operate in a wide range of input voltage with higher efficiency. Furthermore, the AqZSI can operate with a higher modulation index, a lower inductor current stress, and a reduced shoot-through current. A procedure flowchart is presented for the optimal selection of the shoot-through duty cycle, the switching ratio of the additional switch, and the modulation index for AqZSI. Moreover, some comparative results between the AqZSI, qZSI and conventional two-stage inverter with a boost DC–DC converter are shown in detail. Finally, 1.2 kVA SiC-based three-phase inverter prototypes are built to verify the agreement between theory and measurement.

A New Primary PWM Control Strategy for CCM Synchronous Rectification Flyback Converter

A new primary PWM (pulsewidth modulation) control strategy for continuous conduction mode (CCM) synchronous rectification (SR) flyback converter is proposed in this letter. The PWM signal for the primary switch has been divided into two pulses in a switching period (dual-pulse PWM, DP-PWM). The first pulse is a fixed narrow pulse, which is used to turn off the SR, whereas the second pulse is a regulated pulse for output voltage regulation. With the proposed DP-PWM control scheme, the shoot-through currents exist on both the primary side and secondary side of the CCM SR flyback converter can be effectively reduced. Meanwhile, the efficiency has been improved obviously. Detailed theoretical analysis has been presented and verified by a 12 V/2.5 A CCM flyback experimental prototype.

Bridge modular switched‐capacitor DC‐DC converter with soft switching operation and multilevel voltage‐gain range

A bridge modular switched‐capacitor (BMSC) DC‐DC converter with soft switching operation and multilevel voltage‐gain range is proposed in this article. It is mainly composed of an interleaved booster and a switched‐capacitor circuit. The symmetrical interleaved structure is applied in the interleaved booster to obtain the ripple‐free of the input current, and the interleaved pulse width modulation control scheme is employed to achieve zero‐voltage‐switching operation of all power switches. The BMSC is employed in the switched‐capacitor circuit to achieve high step‐up gain without having to use a transformer with a high turns ratio, and it can be expanded to obtain a multilevel voltage‐gain range. In addition, the zero‐current‐switching operation of rectifier diodes can be obtained when the resonant frequency is above the operating frequency of the interleaved booster. A 400‐W prototype converter was constructed with an input voltage of 25 V. The analyses are validated by the simulation and experimental results. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Enhancement of System Stability Based on PWFM

In this paper, a pulse width and frequency modulation (PWFM) control strategy is presented, which combines the one-comparator counter-based pulse width modulation (PWM) control with pulse frequency modulation (PFM) control to increase pseudo-1-bit resolution under constant-frequency operation. Accordingly, system stability will be enhanced significantly. As compared with the traditional counter-based PWM control, there is no difference in off-chip circuit complexity except a slight change in on-chip hardware. Finally, a prototype circuit is used to verify the proposed control concept by some experimental results with no limit cycle oscillation.

Modular control with carrier auto‐interleaving and capacitor‐voltage balancing for MMCs

In this study, a new control method dedicated to modular multilevel converters (MMCs) is proposed. The approach is based on local communication between the individual controls of each submodule (SM). The local values of the capacitor voltages and the carrier-phase angles are shared between immediate neighbours achieving balancing of their capacitor voltages, and an automatic interleaving of the pulse-width modulation (PWM) signals. Using an inter-cell communication strategy, the number of required data exchanges with a centralised controller is greatly reduced. This method works for any number of SMs present in the converter and provides an integrated dynamic reconfiguration capability to enable or disable SMs during operation, without any additional consideration for the control-algorithm's implementation. Such a capability is not offered by classical MMC control methods using either PWM or nearest-level control strategies. Higher stability, robustness and larger bandwidth of the proposed method are first demonstrated through real-time simulation. The auto-interleaving of the PWM carriers and the capacitor-voltage balancing, provide fast responses and adequate accuracy. Experimental results are provided using a 600 V/3 kW/18 cells single-phase MMC demonstrator confirming the simulation results, and the advantages of this SM control strategy.

Fault-Tolerant SVPWM Control Strategy for Five-Phase PMSM under Single-Phase Open-Circuit Fault

Because five-phase permanent magnet synchronous motor (PMSM) has fault-tolerant capability, it is widely used in the applications with high reliability requirements, such as electric vehicles (EVs) and hybrid vehicles. Effective fault-tolerant control strategies can promote the development of these fields. In this paper, a space vector pulse width modulation (SVPWM) control strategy for five-phase PMSM under single-phase open-circuit fault is newly proposed. This strategy adopts two methods which are based on the principles of minimum copper loss and equal amplitudes of currents to generate reference voltage vectors. Then, they are synthesized in the reconstructed fundamental α-β plane and the harmonic y-axis to reach the control goals. The efficiency of the proposed strategy is validated by simulation. And the results show that this strategy greatly improves the reliability of the five-phase PMSM drive system and meets the strict requirements of the reliability of EVs.