Simple Pulse Width Modulation Research Articles

Design and Verification of Multiphase Multilevel Traction Inverter

The paper presents the practical design and implementation of a three-level neutral point clamped (TNPC) six-phase inverter rated at 100 kVA. The study initiates with prior work review, whereby most research work done earlier was mainly simulation-based. Based on the simulation results, this paper focuses on the practical aspects of inverter design, such as the development of a power board on an Insulated Metal Substrate, a gate driver board, an interconnect board, and the main control board. An inverter physical prototype has been built and tested at 500 V and 20 kW of output power. The SiC semiconductor technology is the base of the inverter, which represents the main merit of the work. Finally, high power density, compact design, and high efficiency are shown, which are major contributions of the paper. Tests performed proved that the designed converter was operating reliably and efficiently. While a simple Sinusoidal Pulse Width Modulation (SPWM) control algorithm has been implemented, the overall performance of the inverter showed great promise for higher-power applications. Compact and high-efficiency TNPC converters are developed for meeting increasing demands of advanced energy, automotive, and industrial applications.

A unified duty-cycle modulation algorithm for a three-level NPC inverter

In this paper, it is a kind of challenge to simplify the conventional pulse width modulation (PWM) algorithms for a three-level neutral-point-clamped inverter. Thus, the unified duty-cycle modulation (UDM) algorithm is presented. It is more attractive than the carrier-based PWM (CBPWM), space-vector PWM (SVPWM), and unified PWM algorithms with a simpler calculation by utilizing the usefulness of the SVPWM algorithm to synthesize the duty cycles in time-domain and the CBPWM algorithm to synthesize the duty cycles in frequency-domain with the lesser conditions and the blankness of the lookup tables, switching sequence design, and zero-sequence component finding. Besides, it is outstanding with three outcomes: (1) comprehensive mathematical models of the dwell times, (2) permanent mathematical models of the duty cycles in time-domain, and (3) simplified PWM algorithm, which has a better workflow with the reduction of the computation burden. As it is very easy to implement as the sinusoidal PWM technique while its performance is equivalent to the SVPWM algorithm, this makes the proposed UDM algorithm a good candidate to optimize between the performance and the cost. Both the simulation and experimental results can confirm the feasible practicability and performance. The comparison with the conventional algorithms can evidently emphasize the superiority.

A new single modulating and single carrier‐based predictive current control technique for single‐phase quadruple boost multilevel inverter topology

SummaryA new floor function single carrier‐based modulated model predictive current control (F2‐SCM2PC2) technique has been proposed in this paper by considering traditional single‐phase quadruple boost switched capacitor‐based multilevel inverter (QB‐SCMLI) topology. Conventionally, the implementation process of single modulating and single carrier‐based pulse width modulation (PWM) techniques are very much complex and finite control set‐based model predictive control (FCS‐MPC) technique inherently operates with variable switching frequency (VSF) operation, which is not suitable for industrial applications. To alleviate the aforementioned issues, a new generalized closed‐loop F2‐SCM2PC2 technique has been proposed. It consists of a simple PWM implementation process and can easily be integrated with a predictive algorithm, thereby providing a constant switching frequency (CSF) of operation. The particular single modulating and single carrier‐based PWM technique with floor function is also suitable for low and high switching frequency (LSF‐HSF) operations. The validation of floor function‐based PWM technique in open‐loop and closed‐loop F2‐SCM2PC2 techniques has been effectively verified through experimentation on QB‐SCMLI topology with consideration of resistive–inductive load.

A single-phase direct buck-boost AC–AC converter with minimum number of components

In this paper, a single-phase direct pulse width modulation (PWM) buck-boost AC–AC converter is proposed. The proposed converter utilizes a minimum number of semiconductor switches and passive components that decreases the converter power losses and offers high efficiency. It can be operated with simple PWM control and doesn’t require soft-commutation strategies. It does not suffer from input source shoot-through and commutation problems. Moreover, it supplies both continuous input and output currents. The common sharing ground of the input and output gives the proposed converter the feature that it can be utilized for voltage sag and swell compensation. A comparison of the proposed converter performance with similar existing converters is presented. Also, detailed circuit analysis, component design guidelines, and simulation results using the MATLAB/Simulink environment are demonstrated. A laboratory prototype has been built and tested to validate the converter performance and confirm the results obtained by computer simulation.

A Simplified PWM Strategy for Open-Winding Flux Modulated Doubly-Salient Reluctance Motor Drives With Switching Action Minimization

In this article, a simplified pulsewidth modulation (PWM) strategy is proposed for open-winding flux modulated doubly-salient reluctance motor (FMDRM) drives for switching action minimization and common-mode voltage (CMV) reduction. Conventionally, the open-winding converter topology is utilized to achieve the zero-sequence current flow path and dc-biased sinusoidal current excitation for the FMDRM, where the switching actions of power switches are doubled compared to the conventional modular three-phase converter, leading to higher switching losses. Different from the conventional space vector PWM scheme, the reference voltages of converter legs are directly calculated by the reference phase voltages in the proposed PWM scheme. In addition, a rotor-position-based sector division method is proposed to deal with the sector imbalance caused by the distorted back electromotive force (back EMF). Furthermore, different leg voltage clamping methods are respectively developed in odd and even sectors for switching action minimization, which can achieve voltage stress balance and CMV reduction. With the proposed scheme, the switching actions in each switching cycle can be reduced by half, which effectively increases the system efficiency of the FMDRM drive. Experiments are carried out on a three-phase 12/8 FMDRM prototype to verify the effectiveness of the proposed scheme.

Simple Discontinuous Pulse-Width Modulation Scheme for the Loss Reduction of a Dual Inverter Fed an Open-End Winding Induction Motor

This paper presents a simple discontinuous pulse width modulation (DPWM) switching scheme to reduce the switching loss of a single DC-link dual two-level inverter fed an open-end winding (OW) induction motor (IM). The dual inverter system is attractive in many applications due to higher DC-link voltage utilization. Additionally, the OW motor has the potential fault-tolerant capability. However, the use of the dual inverter results in reduced system efficiency due to increased power losses in the inverter. Moreover, an OW motor inherently suffers from a zero-sequence current (ZSC) issue because the open neutral point of the stator windings provides the ZSC path. The ZSC causes negative effects in the system, such as an additional power loss and total harmonic distortion (THD). Thus, this work proposes an optimal DPWM scheme to reduce the inverter loss while suppressing the ZSC. Additionally, this work proposes a strategy to make the average power loss of each inverter equal. The performance of the proposed method is discussed in terms of switching power loss reduction and ZSC suppression. Simulation and experimental results are provided to verify the effectiveness of the proposed DPWM scheme.

High Step-Up Three-Level Soft Switching DC-DC Converter for Photovoltaic Generation Systems

In this paper, a high step-up three-level DC–DC converter with a symmetric structure for PV application is proposed. The converter has high voltage gain. This is achieved due to the use of two high step-up cells and two resonant paths in its structure. The converter has low input current ripples and the voltage stress across all switches is equal to half of the output voltage. The proposed converter uses simple pulse–width modulation (PWM) to trigger the switches. Hence, the proposed converter benefits from a simple structure and control circuit. All semiconductor devices are turned on/off under ZCS conditions. Thus, the switching losses are decreased, and the total efficiency is increased. The converter is implemented and tested through a laboratory prototype. The experimental results verify the theoretical analysis.

THE ANALYSIS OF REDUCTION IN SWITCHING LOSS WITH FEEDFORWARD CONTROL IN GRID-TIED MICRO GRID SYSTEM

This paper proposes the simplified pulse widthmodulation (PWM ) strategy in the bidirectionalac/dc single-phase converter with the feed-forwardcontrol scheme. In this, the number of switching ofthe proposed simplified PWM strategy is reduced toone-fourth to that of the unipolar & bipolar PWM.The feed-forward control scheme is used to achievebetter performance of the ac/dc converter in both therectifier & inverter mode as compared with theconventional dual-loop control scheme. Thesimplified PWM strategy with feed-forward controlscheme has higher efficiency than that of the unipolarPWM & bipolar PWM strategies. Also, the totalharmonic distortion is less in this PWM strategy. Thesimulation & experiments are carried out to verify thevalidity of the proposed PWM strategy & controlscheme. The proposed simplified PWM strategy withthe proposed feedforward control scheme has lowertotal harmonic distortion than the bipolar PWM andhigher efficiency than both unipolar and bipolarPWMs. Furthermore, the proposed simplified PWMoperated in the inverter mode also has largeravailable fundamental output voltage VAB than boththe unipolar and bipolar PWMs. A prototype systemis constructed and the control scheme is implementedusing FPGA Spartan-3E XC3S250E. Both simulationand experimental results verify.

Dual-Transformer-Based Hybrid Phase-Shift PWM DC-DC Converter With Wide ZVZCS Range

This brief proposes a dual-transformer-based hybrid phase-shift full-bridge (PSFB) converter. Instead of adopting auxiliary components, the proposed hybrid PSFB converter widens the zero-voltage switching (ZVS) range with the help of the current generated by additional transformer and additional half-bridge. Unlike the conventional method utilizing auxiliary circuit, the additional transformer and half-bridge can also transmit a large part of the power to reduce the burden on the main transformer. Meanwhile, the circulating current on the primary side can be effectively reduced due to the structure of hybrid bridge, and the additional half-bridge can achieve zero-current switching (ZCS) with reduced switching loss. The proposed converter can obtain a wide ZVZCS range with simple phase-shift pulse width modulation under fixed switching frequency. The operating principle, ZVZCS performance, and parameter design are analyzed in this brief. Finally, a 1 kW experimental prototype was built to verify the effectiveness of the proposed solution.

An efficient and high gain switched-capacitor based multi-level inverter

A new switching-capacitor-based boosting multilevel inverter is described in this paper. A nine-level voltage waveform is produced using 10 switches, one-diode, and two-capacitors. Each fundamental cycle contains numerous occurrences of capacitor voltages being linked in parallel with the source voltage, resulting in self-balancing capacitor voltages. Proposed topology has built in polarity changing ability so no H-bridge is required. This paper describes a simple pulse-width modulation system based on logic gates that maintains power balance among the capacitors. For obtaining the higher voltage gain extended topology of proposed topology is also presented. The prototype’s experimental results are provided for verifying the working and boosting capability by four times of source voltage. A thorough comparison with contemporary topologies demonstrates the cost-effectiveness of the suggested topology, as well as the fact that it is a simpler construction that requires less space and consumption of resources.

A Coupled-Inductor-Based Soft-Switching Noninverting Buck–Boost Converter With Reduced Auxiliary Component Count

This letter proposes a coupled-inductor-based soft-switching noninverting buck–boost converter (NIBBC) with reduced auxiliary component count. Instead of using multiple auxiliary passive components to achieve soft switching, the proposed coupled-inductor-based NIBBC uses the coupled inductor as the main inductor, and the auxiliary current generated by the magnetic coupling effect is used to obtain the soft switching for all switches. With simple pulsewidth modulation under fixed frequency, full-load range zero-voltage switching can be obtained under a wide voltage range. Unlike the conventional method utilizing the coupled inductor only to generate nonactive power, the coupled inductor of the proposed converter also takes participant in the power transmission. Besides, the added diode can achieve zero current turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> that avoids the diode recovery issue. The operating principle, the soft switching, and the parameter designs are analyzed in this letter. Finally, experimental results have verified the effectiveness of the proposed solution.

DESIGN AND DEVELOPMENT OF 51 LEVEL NON MODULAR MULTILEVEL INVERTER TOPOLOGY WITH REDUCED NUMBER OF SWITCHES AND CONDUCTION PATH

In this paper, a 51 level multilevel inverter topology with non modular design is developed, which can be operated in asymmetrical mode with a reduced number of power switches and lesser conduction path. The proposed design has three separated DC sources and eleven active power switches, i.e., ten unidirectional switch and one bidirectional switch. The topology can be used with asymmetrical voltage source configuration to generate fifty one levels. This structure can be cascaded to produce maximum level by a series connection to produce higher voltage levels with less voltage stress on the switches without modifying the topology structure. A detailed Comparison is made with existing topology and recently introduced topologies based on the number of active switches, Separated DC sources, number of gate driver circuits. To prove the presented topology’s superiority, a simple Multicarrier pulse width modulation has been deployed as the switching scheme. Validation on the viability of the proposed topology has been carried out through Matlab/Simulink simulation. KEYWORDS: Non Modular Multilevel Inverter, Reduced Switch.

DESIGN OF MODULAR AND NON MODULAR MULTILEVEL INVERTER TOPOLOGY WITH REDUCED NUMBER OF SWITCHES

In this paper, a new multilevel inverter topology with modular and non modular design is developed, which can be operated both symmetrical and asymmetrical mode with a reduced number of power switches. The proposed design has four separated DC sources and Nine active power switches. The topology can be used with symmetrical and asymmetrical voltage source configuration to generate seventeen and seven voltage levels. This structure can be cascaded to produce maximum level by a series connection to produce higher voltage levels with less voltage stress on the switches without modifying the topology structure. Comparison is made with existing topology and recently introduced topologies based on the number of active switches, Separated DC sources, number of gate driver circuits. To prove the presented topology’s superiority, a simple Multicarrier pulse width modulation has been deployed as the switching scheme. Validation on the viability of the proposed topology has been carried out through Matlab/Simulink simulation. KEYWORDS : Modular, Non Modular Multilevel Inverter, Reduced Switch.

A Simple Virtual-Vector-Based PWM Formulation for Multilevel Three-Phase Neutral-Point-Clamped DC–AC Converters including the Overmodulation Region

Neutral-point-clamped (NPC) power conversion topologies are among the most popular multilevel topologies in current industrial products and in industrial and academic research. The proper operation of multilevel three-phase NPC DC–AC converters requires the use of specific pulse-width modulation (PWM) strategies that maintain the DC-link capacitor voltage balance and concurrently optimize various performance factors such as efficiency and harmonic distortion. Although several such PWM strategies have been proposed in the literature, their formulation is often complex and/or covers only particular cases and operating conditions. This manuscript presents a simple formulation of the original virtual-vector-based PWM, which enables capacitor voltage balance in every switching cycle. The formulation is presented, for the general case, in terms of basic phase voltage modulating signals, with no reference to space vectors, involving any number of levels and for any operating conditions, including the overmodulation region. The equivalence of the presented formulation to the original PWM strategy is demonstrated through simulation under different scenarios and operating conditions. Thus, this manuscript offers in a one-stop source a simple, effective, and comprehensive PWM formulation to operate multilevel three-phase NPC DC–AC converters with any number of levels in any operating condition.

Hybrid Three-Phase Transformer-Based Multilevel Inverter With Reduced Component Count

This paper proposes a novel three-phase transformer-based multilevel inverter (MLI) topology to maximize the output voltage levels for high-power high-voltage applications while reducing component counts as compared to its transformer-based counterparts. The proposed hybrid topology is formed by connecting a three-level T-type module with full H-bridge cells through single-phase transformers. The T-type module is fixed while the full H-bridge cell can be repeated for enlarging the output voltage levels without increasing the voltage stress on switches. Key features of the proposed topology include low part count, capacitor-free, diode-free, voltage boosting, simple control, and modularity. Within the framework, a simple low-frequency pulse width modulation (LFPWM) switching scheme is used to control the output voltage, and the working principle is detailed for seven-, nine-, and N-level operation. The operability and performance of the proposed topology are numerically verified and experimentally validated at different loads. Moreover, its conversion efficiency is experimentally examined. Finally, a comparative study with existing transformer-based MLI circuits is conducted to prove its key merits.

Operation and Design Consideration of an Ultrahigh Step-Up DC–DC Converter Featuring High Power Density

A new dual-coupled inductor (CI) single-switch high step-up dc–dc topology featuring high power density is proposed in this study. Various capacitive power transfer methods, as well as inductive power transfer techniques, are utilized to act as a more efficient power interface between the input and the load. Three ports in the output terminal are employed to distribute the overall output voltage, diminish the voltage ripple in high-voltage gain ratios, and decrease the voltage stress on the port component. In the proposed converter, first, the voltage gain is high in lower duty cycles of the switching. Second, the stored energy of magnetizing and leakage inductances is recycled in both Cls. Third, the switch voltage spikes are alleviated. Fourth, the operation is done with no circulating current. Fifth, low-size passive components are presented. Sixth, high power density is obtained, and the voltage range is widened. Finally, a simple pulsewidth modulation (PWM) utilizing a wide control range is provided. In this study, the steady-state operation is analyzed under both continuous conduction mode (CCM) and discontinuous conduction mode (DCM), and the performance of the converter is evaluated using comparisons with similar works. In addition, the experimental results have been provided to justify the feasibility of the design.

A Simple Two-Stage AC-AC Circuit Topology Employed as High-Frequency Controller for Domestic Induction Heating System

The induction heating process at a domestic level is getting attention nowadays as this power converting topology ensures clean, reliable, flexible, and fast operation. The low input frequency is converted to required regulated high output frequency with indirect and direct power converting approaches. The circuit and control complexity and high conversion losses associated with indirect power converting approaches lower their uses for domestic induction systems. The direct ac-ac power conversion approach is one of the viable solutions for low and medium power level loads, especially for domestic induction heating loads. The circuit complexity, cost, and conversion losses of the direct power converting systems depend on the number of the controlled switching devices as each controlled switch requires one gate driving circuit and one isolated dc supply. Simplified pulse width modulation (PWM) switching control also lower their control effort. Therefore, in this article, a simplified direct ac-ac power converting approach is introduced for a high-frequency domestic induction heating system. Here, the regulation of the high output frequency is achieved by simply cascading the single-phase full-bridge rectifier with a full-bridge inverter with a simple control strategy. The characteristics of the developed topology are validated through simulation results of the Simulink-based platform and practical results of the developed practical setup.

Simple Carrier-Based PWM for Prolonged High DC-Link Utilization for Symmetrical and Asymmetrical $n$-Phase AC Drives

Square voltage waveforms enable high dc-link utilization (DLU) in multiphase ac drives. Circulating-current filters were devised to attenuate the harmonics in no-torque low-impedance subspaces. Nonetheless, the square-wave harmonics that generate torque ripple are not reduced. Recently, it was proposed to combine circulating-current filters with a carrier-based pulsewidth modulation (PWM) method, which injects harmonics in no-torque subspaces (attenuated by the filter) of five-phase motors to achieve high DLU, without harmonics associated with torque ripple. The filter allows prolonged high-DLU operation without overheating. Compared with other PWM techniques capable of high-DLU operation (overmodulation), the one proposed for said filters is especially convenient because of its simplicity. However, it is unclear if this PWM method can be extended to machines of any phase number n and winding arrangement (symmetrical or asymmetrical); and if so, the resulting performance is also unknown. This article extends this simple carrier-based PWM strategy to n-phase drives, and evaluates its behavior in terms of DLU, distortion, and computational burden. Symmetrical and asymmetrical winding arrangements are considered. The improvement in DLU, compared with conventional PWM with zero-sequence injection, is considerable. Current distortion is negligible with a suitable filter. The simplicity over other high-DLU PWM techniques is remarkable. Experimental results are provided.

Ultra-High Step-Up DC-DC Converters Based on Center-Tapped Inductors

In this paper, a new family of ultra-high step-up DC-DC converters based on a center-tapped coupled inductor (CI) is proposed. These single-switch converters employ different inductive and capacitive power transfer techniques by utilizing multi-winding CIs, intermediate capacitor links and simple switched-capacitors to improve the transferred power rate, harvest magnetizing and leakage inductance energies, and enhance power density. Achieving high voltage gain in low duty cycle values enables the proposed converters to operate under wide output voltage ranges; meanwhile, distributing the output voltage on two or three output ports alleviates the voltage stress on output terminal components. Low input current ripple, simple pulse width modulation control, low switch voltage stress and operation without circulating current can be listed as other features. In this paper, the proposed family is introduced, theoretically analyzed and compared with other state-of-the-art researches. Finally, the accuracy of analyses are evaluated with some experimental tests of a 1.25 kW experimental prototype.

Double integral sliding mode control of a boost PEMFC system

In this study, we propose a simple pulse-width modulator based on integral sliding mode controller (PWM-SISMC) to deal with the steady state error (SSE) of a boost converter. The PWM-DISMC is used for the first time to compensate for the SSE of a proton exchange membrane fuel cell (PEM-FC). The PWM-DISMC tracks the reference output of the FC system composed of a 7 kW FC supplying a resistive variable load (24 Ω to 96 Ω) and a DC bus voltage (48 V) using a boost converter. A control signal is then generated and used to adjust the pulse width of the PWM output signal that drives the boost converter switch. The PWM-DISMC is compared to the conventional PWM-SISM using the SimPowerSystems models implemented by MATLAB/Simulink. simulation results show that the proposed PWM-DISMC has better performances, regarding the steady state error of the boost converter, than the performances of the PWM-SISM.