Carrier-based PWM Method Research Articles

Comparative Study of THD Characteristics in Different Cascaded H-Bridge Configurations for Multilevel Multicarrier Modulation

This paper presents a comprehensive comparative study investigating the Total Harmonic Distortion (THD) characteristics of various Cascaded H-Bridge (CHB) configurations utilized in Multilevel Multicarrier Modulation (MMCM) systems. The research examines different CHB topologies, focusing on their impact on THD performance in MMCM applications. Through theoretical analysis and simulation, this study evaluates THD levels under varying operating conditions, including different modulation schemes and switching strategies. A discussion on main topologies of multilevel inverter namely H-bridge, NCP(neutral point clamped),NCP- H and flying capacitor is carried out utilizing carrier based PWM methods. Comparison is done on basis of harmonic component, THD and nu of component used by 3, 5 and7 level cascaded H-bridge topology respectively. To support the result a detailed study is carried out using MATLAB Simulink software. Keywords- Multilevel inverter, PWM, THD, NCP, NCP-H.

Self-aligned hybrid carrier-based PWM for modular multilevel converters

The self-aligned hybrid carrier-based pulse-width modulation (PWM) for modular multilevel converters (MMC) based on decentralized control is proposed in this paper. It is based on parallel cells in a submodule (SM) using self-aligned hybrid carrier-based PWM, which combines the concept of level-shifted carrier-based PWM (LSC-PWM) and phase-shifted carrier-based PWM (PSC-PWM) methods. By implementing a decentralized control system digitally, hybrid carriers align themselves. Each SM interacts with the other SMs and each parallel cell in an SM communicates with the other cells to generate hybrid carriers. The proposed control strategy makes advantage of the redundancy idea by adding or removing a cell in the case of cell malfunction and system reconfiguration. A current balancing method is incorporated into the decentralized control system to ensure current balance among parallel cells in an SM. The simulation results illustrate the effectiveness of the presented control method in piecewise linear electrical circuit simulation (PLECS) software.

Performance Evaluation of SiC-Based Two-Level VSIs with Generalized Carrier-Based PWM Strategies in Motor Drive Applications

Currently, silicon carbide (SiC) MOSFETs are several times higher in cost than the equivalent silicon (Si)-IGBTs; however, the gains in power conversion efficiency, simplification of thermal management, and energy savings in general bring the advantages of lower total cost of ownership. The implementation of discontinuous PWM (DPWM) techniques for controlling the motor drive brings further reductions for the semiconductor switching losses; however, most existing techniques have limited performance on the optimized clamping region, particularly at a low power factor, which is a common operation condition for motor drives employing the widely used V/f control, particularly at partial- or low-load conditions. This paper evaluates the performance of a SiC-based two-level voltage-source inverter (2L-VSI) motor drive operated with generalized carrier-based PWM methods. Theoretical analysis and experimental measurements are conducted in a 2.2 kW heatsink-less 2L-VSI prototype and induction machine, which demonstrates that the minimum switching losses DPWM (MSL-DPWM) is the most favorable solution in practice in terms of the achievable power conversion efficiency and harmonic distortions and also produces the least common-mode current, which is critical in motor drives.

Advanced PWM Techniques for Multi-Level Inverters With a Multi-Level Active CM Noise Filter

Pulsewidth modulation (PWM)-based power electronics inverters are being widely used for various applications, including motor drives. However, the common-mode voltage (CMV) resulting from switching operations in the PWM inverters causes significant performance degradation of the system and can cause potential damage to motors. Since the effects of the CMV can be more severe in wide bandgap (WBG) and high switching frequency-based converter systems, various methods have been proposed to mitigate the CM noise issues. This work presents a multi-level inverter system composed of a multi-level inverter with a proposed multi-level active power filter (APF). For attenuating the CMV in multi-level inverters using multi-carrier-based PWM methods, a novel PWM method is presented for the proposed multi-level APF. The three-phase five-level active-neutral-point-clamped (ANPC) II-type inverter using the apparent switching frequency doubling (ASFD) PWM is used as an example of the multi-level inverters and carrier-based PWM methods to analyze and verify the proposed CMV attenuation method. The APF generates and injects the APF voltage equal to the CMV to attenuate the CM noise accurately. Various key challenges, including the dead-time compensation, are addressed through the proposed advanced PWM techniques to improve the CMV attenuation performance. Simulation and experimental results are provided to verify the comparison and effectiveness of the proposed CMV attenuation method.

A Carrier-Based Discontinuous PWM Method for a Five-Level Flying Capacitor Rectifier With Unbalanced DC-Link Voltages

Unbalanced dc-link voltages occur when five-level flying capacitor (5L-FC) rectifier has dual dc loads of different rated voltages. Compared with traditional continuous pulsewidth modulation (CPWM) strategies, discontinuous PWM (DPWM) methods have more advantages in high-frequency and high-power applications for less commutation and higher efficiency. Therefore, this article proposes a carrier-based DPWM method for 5L-FC rectifiers with unbalanced dc-link voltages. The proposed method is first analyzed in the revised space vector diagram considering unbalanced dc voltages to divide subsectors and find available clamping modes, then it is implemented by applying carrier-based PWM with injecting clamping compensation component, which greatly reduces the implementation complexity. There is a pair of redundant clamping modes with opposite effects on the neutral-point (NP) in each subsector. Thus, the NP voltage can be actively controlled by selecting suitable clamping mode in each subsector. In addition, the allowable ranges of unbalanced voltage degree and unbalanced power degree are investigated in detail. Simulations and experiments verified the effectiveness and performance of the proposed method.

A Generalized Simplified Virtual Vector PWM to Balance the Capacitor Voltages of Multilevel Diode-Clamped Converters

This article presents a generalized simplified virtual vector pulsewidth modulation (SVVPWM) to attain the capacitor voltage balancing of multilevel diode-clamped converter (DCC) for all operational conditions, which is not possible by using conventional space vector pulsewidth modulation (PWM) and carrier-based PWM methods. Virtual vector PWM is a solution presented in the literature to sort out this issue but it becomes more complex for higher level converters. The proposed SVVPWM method is simple and easy to implement for any level converter because it converts the space vector (SV) diagram of any level converter to three-level SV diagram. The SVVPWM assures the natural voltage balancing under steady states and ideal operations. Under dynamic operations, a generalized equation that describes the influence of neutral point currents on dc-link capacitor's voltage has been derived and a general decoupled voltage balancing control for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -level DCC is presented. The proposed modulation method is implemented on five-level and seven-level DCCs to authenticate the effectiveness of decoupled voltage balancing control. Simulation and experimental results demonstrate that the proposed modulation strategy is easy to implement and effectively controls the balance of the capacitor voltages for the whole range of modulation index and load power factor.

A Simple Commutation Method and a Cost-Effective Clamping Circuit for Three-to-Five-Phase Indirect-Matrix Converters

This article presents and analyzes a three-to-five-phase indirect matrix converter (IMC) structure for directly supplying a five-phase static R–L load from a three-phase supply. The IMC topology offers a lower number of switches, a simple commutation procedure and a cost-effective clamping circuit in comparison to the direct matrix converter (DMC). A simple clamping circuit with one ultrafast diode and one small capacitor is proposed to protect the switches of the IMC from overvoltage. The issues of powering up the IMC with the simple clamping circuit is discussed in detail. The instructions for the safe start-up of the IMC with the proposed clamping circuit is introduced based on the simulated and the measured analyses. Moreover, a carrier-based pulse-width-modulation (CBPWM) method is also presented in order to control the switches of the IMC. The presented CBPWM method creates PWM pulses for both the inverter and the rectifier legs by using only one symmetric and triangular carrier signal. Finally, experimental and simulation testing with a five-phase R–L load demonstrate the viability and the efficiency of the introduced CBPWM algorithm for the suggested IMC.

Simulation and dSPACE Hardware Implementation of Carrier based SVPWM for Open-end Induction motor

This paper deals with the implementation of carrier based Space vector pulse width modulated methods (SVPWM) in conjunction with a three phase open end induction motor(OEIM). Among various PWM methods, now a day’s carrier based PWM methods draws more attention due to their easier digital implementation. The main focus of this paper is effortless digital implementation of PWM methods to drive the open end induction motor which is supplied using two dc to ac converters (VSI), using various carrier-based Space vector PWM schemes. MATLAB Simulink platform is used to simulate different carrier based PWM methods for the VSI fed Induction motor. In the present work dSPACE 1104 is used for the digital implementation. The simulation and hardware results which are obtained from various modulation techniques for the proposed model are secure produced by using voltage and current waveforms, FFT analysis, and the most predominantly the THD is slighter. Theoretical and realistic values are corroborating by simulation and experimentation.

A Generic Two-Stage Carried-Based PWM Scheme With Adjustable Switching Patterns for Current Source Converter

Modulation schemes play a key role in effectively driving the current source converter (CSC). Among various modulation schemes, the carrier-based pulse width modulation (CB-PWM) has gained much attention owing to its inherent auto-sequencing process. However, the fixed switching patterns in the existing CB-PWM methods reduce the available degrees of freedom, which imposes underlying restrictions on the performance of a CSC (e.g., to minimize the switching frequency or to reduce the current ripple). To address this issue, an innovative concept of two-stage modulation, which modulates the active and zero current vectors in a switching sequence, respectively, in two stages, is explored in this article. Based on that, this article proposes a generic CB-PWM scheme with adjustable switching patterns for flexibly modulating the CSC. Its mechanism is presented to develop its modulation characteristics. It shows that the proposed PWM scheme can flexibly achieve different modulation objectives by only adjusting the offset voltage in the second stage. Three derivations of the proposed scheme have then been discussed in detail, which can achieve a minimized switching frequency, a reduced dc-link current ripple, or a compromise between them. Representative experimental results have been provided to verify the effectiveness of the proposed modulation scheme.

WITHDRAWN: An experimental approach of DVR for relieving voltage dip and voltage swells

Abstract Based on recent power quality studies, voltage dip and swells in the medium and low voltage distribution grid are regarded as the most frequent form of power quality problems. Their effect is serious on sensitive loads. The effect varies from load disturbances to major economic losses to millions of dollars. Different solutions have been developed to defend sensitive loads against such disturbances, but the most powerful and efficient solution is considered to be the DVR..In this paper, the hardware setup of DVR to relieve the voltage dip and swell has implemented by the use of the micro-controller and control circuit for the H-bridge inverter. The system suggested in the article provided has a limited variety of changing devices that decreases the intricacy of the circuit as well as using the microcontroller (LPC2148) to use a simple control circuit. The multi-level inverters give almost sinusoidal result waveform, the result exists with polished harmonic account and switching losses that are less than the traditional level inverter, and thus smaller filter dimension is needed. Regular cascaded MLI as well as various other current7-level reduced switch topologies making use of carrier-based PWM methods, the performance top quality in terms of THD, and also switching losses of the brand-new MLI compared.

M-Type and CD-Type Carrier Based PWM Methods and Bat Algorithm-Based SHE and SHM for Compact Nine-Level Switched Capacitor Inverter

This paper presents new and efficient modulation techniques applied on the recently introduced compact nine-level switched-capacitor inverter (C9LSCI). The paper also discusses the performance of the inverter under selective harmonic elimination (SHE) and mitigation (SHM) based on the heuristic Bat-Algorithm (BA) technique. Two new modulation techniques employing CD-type carrier waves and M-type carrier waves are proposed, showing a rise in efficiency, an increase in RMS voltage, reduction in capacitor voltage ripple, and a reduction in harmonic distortion (THD). Four recently introduced modulating signals, namely the third harmonic injection, thirty-degree bus clamped PWM (THTDBCPWM), third harmonic injection sixty-degree bus clamped PWM (THSDBCPWM), one pole clamped PWM (OPCPWM). Loss balancing two-pole clamped PWM (LBTPCPWM) are applied to the inverter with the proposed carriers, and a comparative analysis is carried out on different performance parameters. The proposed carriers' efficacy in Alternate Phase Opposition Disposition (APOD), Phase Opposition Disposition (POD), and Phase Disposition (PD) is validated. Further, Bat algorithm (BA) is applied as a heuristic approach to determine the optimum angles for the application of SHE and SHM. The efficacy of all the above techniques on the C9LSCI is verified in MATLAB/Simulink environment and further validated on an experimental setup.

Carrier-based PWM Method for Indirect Matrix Converters based on Space Vector Analysis

In this paper, a novel approach to realize the carrier-based pulse width modulation (CBPWM) method for indirect matrix converter (IMC) is presented. The advantage of the proposed CBPWM method is that only one triangular carrier signal with constant gradient falling and rising edges is used to generate the PWM to the power switches in both the rectifier and the inverter stages of IMC. The analysis of the proposed CBPWM method is based on the space vector approach and the relationship between CBPWM and space vector pulse width modulation (SVPWM) methods is provided. In this paper, four CBPWM methods called: sinusoidal PWM, third harmonic injection PWM, symmetrical PWM and discontinuous PWM are presented. These different CBPWM schemes are established according to the distribution of zero vectors and the switching pattern of the SVPWM method. The comparison of output voltage performance with different CBPWM schemes are investigated. Compared to the conventional method the calculation time of the proposed method is reduced around 50%. Concretely, the calculation time of the SVPWM method is 45 μs, while the calculation time of the proposed method is 22 μs. The experiments have been carried out to show the effectiveness of the proposed method.

Dual-Electric-Port Bidirectional Flux-Modulated Switched Reluctance Machine Drive With Multiple Charging Functions for Electric Vehicle Applications

This article proposes a simplified dual-electric-port drive for a flux-modulated switched reluctance machine (SRM) with flexible charging capability for electric vehicle applications. In the driving mode, the developed flux modulation control can be achieved by directly employing the modular three-leg converter compared to the conventional open-winding topology. The zero-sequence current excitation can be flexibly controlled between the dual port and the number of power switches is also significantly reduced. The corresponding carrier-based pulsewidth modulation method and harmonic current suppression strategy are both developed to improve the machine performance. In the standstill condition, flexible battery charging can be easily achieved by the drive circuit, including both the dc and ac charging, without using any additional passive components and power devices. Then, the current distribution control scheme and power factor correction strategy are further developed for the dc and ac charging, respectively. Compared with existing drive topologies, advanced flux-modulated control and flexible energy control both can be achieved with machine performance improvement and drive cost reduction. Experiments are carried out on a three-phase 12/8 SRM prototype to verify the effectiveness of the proposed SRM drive and control strategies.

Generalized PWM Method for Series-End Winding Motor Drive

Series-end winding motor drive (SWMD) is a novel motor drive with both high dc voltage utilization and zero-axis current control capability, which can replace the role of open-end winding motor drive in different types of ac machines. Three-phase SWMD has advantages of wide speed range, low-cost, high-density, and is easy for multiphase expansion. However, due to the complex vector selection process, the corresponding SVPWM method is computationally complex, especially for the multiphase application. Therefore, the main aim of this article is to propose a generalized carrier-based pulse width modulation method, which serves as the foundation for multiphase expansion of SWMD. By finding a general expression between the leg voltage and the phase voltage in the synchronous rotating framework, the proposed method can generate any desired phase voltage in a multiphase SWMD, whether it is sinusoidal or nonsinusoidal. The feasibility of the proposed drive and method has been verified by three kinds of electrical machines in experiments.

A New Carrier-Based Pulse Width Modulation Scheme with Reduced Output Voltage Total Harmonic Distortion for Multi-Level Inverters

This paper proposes a novel Pulse Width Modulation (PWM) switching technique based on Optimized Carrier Peaks-PWM (OCP-PWM) which can be used to control both single phase and three-phase multilevel inverters. The proposed PWM scheme is designed according to multi-peak selection on carriers a way to define the optimum values for carrier peaks and then minimizing the output voltage Total Harmonic Distortion (), switching frequency (f s), and also switching losses, in comparing with the other carrier-based PWM methods. To examine the performance of the presented PWM scheme, a five-level converter has been employed including six power MOSFETs to produce five level in the output. In comparison with typical PWM switching methods for single-phase inverters, the presented PWM scheme produces low harmonic components in the output voltage. To investigate the reliability of the presented PWM scheme for single-phase five-level converters a 2.5kVA/400 V prototype is carried out by applying a TMS320F28335 digital signal processor.

A modified carrier-based PWM technique for minimization of leakage current in transformer less single-phase grid-tied PV system

This paper discusses the impact of leakage current and its dependency on common mode voltage in transformer less single-phase grid connected photovoltaic (PV) system. Further a new carrier-based PWM method is derived for H bridge single-phase grid-tied PV inverter to minimize leakage current. The proposed modulation strategy is compared with conventional techniques through simulation in MATLAB R2018a. The superiority of the proposed technique is validated in laboratory prototype of a 500 W single-phase grid-tied PV system. The hardware results validate the theoretical findings in appropriate.

Equivalent Phase Current Harmonic Elimination in Quadruple Three-Phase Drives Based on Carrier Phase Shift Method

Multiphase drives are entering the spotlight of the research community for transportation applications with their high power density and the possibility of high fault tolerance. The multi three-phase drive is one of the main types of multiphase drives that allows for the direct adoption of commercial three-phase converters and high control flexibility. The elimination of high-frequency current harmonics will reduce the flux linkage harmonics, torque ripple, vibration and noise in machine drives. Therefore, this work introduces a new method to the modelling of equivalent phase current in multi three-phase drives with the double integral Fourier analysis method. A new carrier-based pulse-width modulation (CPWM) method is introduced to reduce the equivalent phase current harmonics by applying proper carrier phase angle to each subsystem in the multi three-phase drives. The proposed angles of carrier signals are analyzed for quadruple three-phase drives, and the corresponding experimental results confirm the significance of the proposed phase-shifted CPWM method to eliminate the equivalent phase current harmonics.

Comparative analysis of CBPWM methods for two-phase three-leg inverters using zero sequence concept

This paper proposes carrier-based PWM (CBPWM) methods that apply a zero sequence concept in a two-phase three-leg inverter. The total harmonic distortion (THD) and switching losses are analyzed and compared for the five CBPWM methods. The voltage and current THDs decrease when the modulation index (MI) increases in all the PWM methods. The space vector PWM (SVPWM) shows the lowest current THD. The switching losses increase linearly with an increasing MI, and the discontinuous PWM (DPWM) methods have lower switching losses than the continuous PWM (CPWM) methods such as sinusoidal PWM (SPWM) and SVPWM. Simulations and experiments are carried out to verify the performances of the CBPWM methods using a zero sequence concept.

A Generalized Carrier-Overlapped PWM Method for Neutral-Point-Clamped Multilevel Converters

The neutral-point voltage unbalance problem holds back the extensive application of neutral-point-clamped (NPC) multilevel converters with more than three voltage levels in industry. Traditional phase-disposition pulsewidth modulation (PDPWM) or nearest-three-vector (NTV) modulation cannot achieve the voltage balance over the full modulation indexes and load power factors when the voltage level is higher than three. To solve this problem, a novel generalized carrier-based PWM method, named carrier-overlapped PWM (COPWM), for NPC multilevel converters is proposed in this article, which is proven to satisfy the volt-second balance principle. With this modulation method, the average values of all the neutral-point currents are equal to zero in a fundamental period, and therefore, all the dc-link capacitor voltages can be naturally balanced in the ideal and steady-state conditions. In order to simplify its implementation, an equivalent multireference modulation method with only one triangular carrier is also derived. Simulation and experimental results on a five-level diode-clamped inverter are presented to verify the proposed modulation method.

Improvement in DC-Link Utilization With Reduced Current and Torque Deterioration for Five-Phase Drives by Combination of Circulating-Current Filters and Simple Carrier-Based PWM Based on Closed-Form Expressions

Multiphase drives offer important advantages over three-phase ones. With pulsewidth modulation (PWM), zero-sequence and x-y signals can be injected to enhance dc-link utilization (DLU). For example, in five-phase drives, for given dc-link voltage, the fundamental is raised by 23.1%. For sinusoidally distributed windings, although x-y currents increase losses, torque is unaffected. However, no simple carrier-based PWM methods based on closed-form expressions have been presented for this purpose so far. Most importantly, x-y currents may be unacceptably large, due to the small x-y impedance. This is particularly troublesome when high fundamental voltage is needed continuously. Applying square waveform instead of PWM raises the fundamental from 23.1 to 27.3%. Given the square-voltage distortion, filters with large x-y impedance were devised for this approach. However, some square-waveform harmonics map into the torque-producing plane without attenuation, generating torque ripple. This article proposes to use a simple carrier-based PWM method in five-phase drives combined with a circulating-current filter. The x-y voltages, which see large filter impedance, are exploited to achieve a high DLU similar to previous solutions, but without torque ripple or excessive x-y currents. Guidelines are given for designing the filter when used with the presented PWM strategy. Experimental results verify the proposal.