Carrier-based PWM Research Articles

A Novel Segmented Component Injection Scheme to Minimize the Oscillation of DC-Link Voltage Under Balanced and Unbalanced Conditions for Vienna Rectifier

This paper investigates a Vienna rectifier as a charger for series-connected battery packs. Focusing on carrier-based pulsewidth modulation (CBPWM), the ripple current flowing through the neutral point (NP) results in the voltage oscillation if the loads are resistive. To reduce the ripple of average NP current with mitigated distortion under balanced and unbalanced dc-link voltages conditions, a novel CBPWM with segmented component injection scheme (SCIS) is proposed in this paper. After dc component injection, continuous intervals for optimized component injection and clamping intervals for compensation component injection are identified. Optimized components are calculated originally based on unbalanced factor to make the average NP current zero-size in one switching period. Moreover, unique compensation components generate suitable NP current to shape the sinusoidal input currents according to the circuit analysis. In consequence, the SCIS not only keeps the input current with low-harmonic distortion, but also minimizes the oscillation of dc-link voltage under balanced and unbalanced conditions. In addition, the value of the NP current during the clamping intervals is analyzed under various operating conditions. The effectiveness and the performance of the proposed SCIS are verified by simulation and experiments.

Simulation of Switched Capacitor Inverter Topology with Boost Facility

Simulation of switched capacitor inverter topology with boost facility is presented in this paper. The main merits of this inverter topology with boos facility are highly adaptable for Photo Voltaic (PV) applications. The inverter is capable of boosting up low voltage DC into high voltage DC and then invert it to the required voltage level with a single stage. The switched capacitor inverter has a special extended structure, which minimizes the number of components and devices when compared to the other inverter is switched by the means of level shifting carrier based Pulse Width Modulation (PWM) technique. Further, some of the switches in the topology operate in the low frequency and this resulted in a reduction in switching losses thereby increasing the efficiency. This maintains the capacitor voltages at a balanced level. The simulation results are verified through MATLAB/Simulink.

A Modular Design Approach to Provide Exhaustive Carrier-Based PWM Patterns for Multilevel ANPC Converters

The number of applicable carrier-based pulsewidth modulation (PWM) patterns increases with the growth of output levels in scalable multilevel topologies, such as active-neutral-point-clamped (ANPC) converters. Therefore, it is hard to optimize PWM for such topology, especially with large output levels. In this paper, a simplified and modular carrier-based PWM design approach for multilevel ANPC converters is proposed. Inspired by the decomposition theory, the topology decomposition is introduced in this paper to decompose an N -level ANPC converter into low-level subtopologies. Then, the complete set of applicable PWM patterns is derived based on ANPC operation principles, which makes it possible to optimize the performance based on the various requirements in applications. Meanwhile, the carrier-based PWM is implemented through the utilization of subtopologies with low-level modulation schemes, such that the design process of carrier-based PWM is greatly simplified and modularly realized. Both the complete PWM patterns and PWM design examples with experimental results of several ANPC converters are provided to show the feasibility and modularity of the proposed method.

A Carrier-Based Discontinuous PWM Method With Varying Clamped Area for Vienna Rectifier

The three-level Vienna rectifier is an attractive topology for power factor correction applications. However, for practical high-frequency applications, the nonlinearity caused by snubber circuit and parasitic capacitance of Vienna rectifier's switching device will distort input current. This paper proposes a carrier-based discontinuous space-vector modulation (CB-DSVM) method with varying clamped area for Vienna rectifier in high switching frequency applications. The equivalent circuit of Vienna rectifier considering the nonlinear factors is built and the effect of pulse shaping around current zero-crossing point is investigated. The voltage errors caused by the nonlinearity of switching device will distort terminal voltage, which mainly appears at the zero-crossing time. A DSVM method with the fixed clamped area around the zero-crossing point is proposed to reduce the voltage errors and then the simplified CB-DSVM method with varying clamped area by adding a clamped factor to the judging conditions is further studied, which will reduce low-order harmonics of the CB-DSVM method. Simulations and experiments are carried out in a 600 W Vienna rectifier platform, which demonstrates the validity of the proposed method. Compared with the CB-SVM method, the proposed CB-DSVM method with varying clamped area has comparative neutral-point voltage balancing ability and better input current quality.

Space Vector vs. Sinusoidal Carrier-Based Pulse Width Modulation for a Seven-Phase Voltage Source Inverter

The paper presents an extensive comparison between two pulse width modulation (PWM) control schemes, namely carrier-based and space vector based PWM for a seven-phase voltage source inverter. Sinusoidal carrier-based PWM and space vector PWM techniques are employed to control multiphase power converters supplying variable speed multiphase motor drive systems. Implicit relationships that exist between the two PWM techniques are comprehensively explored; this paper, reveal the underlying relationship between the two PWM techniques in terms of several parameters such as modulating signals and space voltage vectors, modulating signals and space voltage vector sectors, switching pattern of space vector and type of carrier. Furthermore, sharing of zero vectors among different chosen space vectors is elaborated that leads to the formulation of different types of modulation. Digital implementation of the two modulation schemes is elaborated. Simulation results are validated using experimental investigation.

Two-Feeder Dynamic Voltage Restorer for Application in Custom Power Parks

The custom power park (CPP) is a concept that has been developed for the purpose of dealing with power quality problems. The CPP is powered by two independent feeders and consists of different types of custom power devices for compensation (dynamic voltage restorer, DVR) and reconfiguration (static transfer switch, STS). Normally, the loads are fed by the preferred feeder (PF) through the STS. When a fault occurs in the PF, the STS performs a reconfiguration of the feeders and feeds the load with an alternate feeder. In this paper, a two-input DVR based on the matrix converter is proposed to provide stable voltage to the load. Each of the DVR inputs is connected to a different feeder, and the PF powers the load. Thus, the DVR has an operational behavior like the STS when reconfiguring the energy transfer of the two feeders and injects it into the PF to guarantee a stable voltage in the load. The control algorithm in the DVR is performed in the dq reference frame to have a unit power factor in feeders and load. The modulation schemes are based on space vector modulation and modified carrier based pulse width modulation. The efficiency and multifunctionality of the proposed DVR is corroborated by simulations on the MATLAB/Simulink.

Carrier-Based PWM Equivalent to Multilevel Multiphase Space Vector PWM Techniques

The space vector pulsewidth modulation (SVPWM) techniques enhance the performance of multilevel multiphase inverters. With multilevel (three-phase) inverters and with (two-level) multiphase inverters, it is widely accepted that the typical SVPWM strategies have an equivalent carrier-based pulsewidth modulation (CBPWM) counterpart, which produces identical results. However, the conclusions reached in the articles that show these cannot be applied, nor even extended, to SVPWM techniques with more than two levels and three phases. This article shows that the most widely accepted multilevel multiphase SVPWM techniques have a fully equivalent CBPWM counterpart, which consists of a phase disposition pulsewidth modulation with an appropriate zero-sequence injection scheme. Closed-form expressions to calculate the zero sequences are provided. The proposed modulation techniques are simulated and then implemented in a field-programmable gate array, showing that the equivalent CBPWM techniques produce identical results as the original SVPWM ones, but with a significant reduction of hardware requirements. The proposed methodology can be generalized to other multilevel multiphase SVPWM techniques.

Pulse width modulation technique with harmonic injection in the modulating wave and discontinuous frequency modulation for the carrier wave to reduce vibrations in asynchronous machines

A new carrier-based pulse-width modulation (PWM) technique to control power inverters is presented in this study. To generate the output waveform, this technique compares a harmonic-injection modulating wave and a frequency-modulated triangular carrier wave. The instantaneous frequency for the carrier wave is adjusted according to a periodic function synchronised with the fundamental term of the modulating wave. The main motivation for using this technique compared to a classic PWM sinusoidal technique revolves around the reduction of total harmonic distortion, the reduction of the distortion factor and the shift of temporal harmonics to higher frequencies for any modulation frequency order. Experimental results show that it is possible to optimise the time harmonics generated to minimise vibrations produced by an induction motor when it is fed with a DC/AC converter controlled by the proposed control strategy. This is made possible by using a control parameter that modifies the instantaneous frequency of the carrier wave without modifying the number of pulses per period of the modulating wave, i.e. the mean value of the carrier wave frequency. The proposed technique is applied to an open loop-controlled inverter that operates an induction motor, helping to reduce the vibration levels produced.

Dc‐link voltage stability analysis technique for hybrid five‐phase open‐end winding drives

The dc-link voltage stability for a hybrid five-phase open-end winding (OeW) drive operating under carrier-based pulse-width modulation is studied. The drive consists of a five-phase induction machine, supplied using one three-level and one two-level voltage source inverter. This configuration is analysed for the case of isolated dc-link rails, while the dc-link voltage ratio is considered as an additional degree of freedom. It is demonstrated that different dc-link voltage ratios lead to the different overall number of voltage levels across stator windings. Modulation strategies are investigated and their performances are analysed from the dc-link voltages stability point of view. An analytical method for dc-link voltage stability analysis is presented. Results show that the four-level configuration always leads to stable dc-link voltages, regardless of the modulation strategy. On the other hand, if the six-level configuration is combined with modulation strategies that lead to optimal harmonic performance, not all dc-link capacitor voltages will be in the balance depending on the operating conditions.

Space vector PWM algorithm for a three‐level asymmetrical six‐phase motor drive

A space vector pulse-width modulation (SVPWM) algorithm for a three-level asymmetrical six-phase drive based on vector space decomposition (VSD) approach is presented in this paper. A modification in zero plane of the transformation matrix is proposed in order to meet the requirement that the realisation of sinusoidal output phase voltages can be obtained through the chosen output leg voltage space vectors. Furthermore, a method of choosing the switching sequences based on all possible one-level transitions of the leg voltages, i.e. a permutation method, is introduced. The algorithm is then validated experimentally and obtained results show that the developed method successfully achieves the desired fundamental phase voltage, although low order harmonics are present due to uncompensated inverter dead time. Last but not least, the performance of the proposed SVPWM algorithm is compared to several carrier-based PWM algorithms including in-phase disposition with ‘double min-max injection’ (PD-DI). This is a little known type of injection, which is verified to obtain identical performance as the presented multilevel algorithm.

A Novel Modulation Strategy With Unconditional Neutral Point Voltage Balance and Three Switching Actions in One Switching Cycle for Neutral Point Clamped Three-Level Converter

The carrier-based pulsewidth modulation (CBPWM) and virtual space vector pulsewidth modulation (VSVPWM) for neutral point clamped three-level converter are reviewed briefly in this paper. A novel modulation strategy is proposed to maintain unconditional neutral point voltage balance under the full range of power factor and modulation index. The proposed PWM strategy is featured with three switching actions in one switching cycle, which is named 3SNPBPWM hereafter. In 3SNPBPWM, one phase is clamped to a certain level without switching action, and the other two phases have one and two switching actions in one switching cycle (SC), respectively. Moreover, a neutral point voltage recovery algorithm for 3SNPBPWM is also proposed. The performance of 3SNPBPWM is analyzed and compared with CBPWM and VSVPWM in terms of switching loss, waveform quality, and ability of neutral point voltage recovery. Finally, the feasibility and superiority of 3SNPBPWM are verified by experiment.

<italic>N</italic>-Tuple Flying Capacitor Multicell Converter—A Generalized Modular Hybrid Topology

This paper presents a generalized topology for multilevel converters based on flying capacitor multicell structure. The proposed topology consists of two modular high-frequency (HF) and low-frequency (LF) sections or cells. The HF cells consist of flying capacitors and semiconductor switches operating at carrier frequency. The LF cells consist of dc sources and semiconductor switches operating at line frequency and its multiples. The proposed topology can be implemented with arbitrary number HF and LF cells. An important advantage of the proposed topology is its reduced components when compared to other multilevel converter topologies in the same family. Another interesting feature is the relatively low blocking voltage requirement for HF switches, making it an attractive choice for high-power applications. A modulating algorithm is devised to generate the gating pulses for the HF and LF cells using phase-shifted carrier-based pulsewidth modulation. As a particular case, the operation of a 25-level topology is explained by the help of illustrating waveforms. A comprehensive comparative study is presented to illustrate the advantages of the proposed topology in terms of the number of components and other performance criteria. Various simulations are carried out to verify the operation of the proposed topology at different operating conditions. The theoretical analysis is experimentally verified using a scaled-down laboratory setup.

Carrier‐based PWM control strategy for three‐level indirect matrix converter

This article proposes a new carrier-based pulse width modulation (CBPWM) strategy for the control of TLIMC. The duty ratios of the rectifier stage and inverter stage are calculated by the SVPWM method. A carrier is constructed and combined with duty ratios to obtain modulation waves, which are regular and determined by the input voltage and output reference voltage. Then, the modulation waves are compared with the same carrier to obtain pulse signals. The pulse signals are used to produce driving signals of power switches through logic operation. The rectifier stage and inverter stage are controlled by the driving signals to obtain three-phase symmetrical sinusoidal input and output waveforms. The proposed method is identical in output to the original SVPWM method. Finally, simulation and experimental results are provided to verify the feasibility and validity of the proposed method.

Carrier‐based PWM modulation strategy for dual‐output two‐stage matrix converter

In order to solve the complexity of the space vector pulse width modulation (SVPWM) strategy for dual-output two-stage matrix converter (DO-TSMC), this study proposes a carrier-based PWM (CBPWM) strategy. The topology of DO-TSMC is introduced, and the principle of alternating SVPWM between two groups of inverters is analysed. The inverter stage switching modulation sequence is optimized by reasonable selection and distribution of zero vectors. Based on the above analysis, according to the expressions of duty ratios and the carrier, the modulation waves of the rectifier stage and inverter stage are deduced. All the modulation waves are simple and regular, without trigonometric function calculations, and no sector judgments are required. The proposed CBPWM strategy is easily implemented by using only one symmetrical triangular carrier to generate the PWM signals for the rectifier stage and inverter stage. Furthermore, based on this strategy, a modified CBPWM strategy is proposed, which assigns the action time of each inverter according to the proportional coefficient. It can adjust the output voltage range of the two inverters flexibly. Finally, the experimental results are provided to verify the feasibility and validity of the proposed method.

Carrier-Based Digital PWM and Multirate Technique of a Cascaded H-Bridge Converter for Power Electronic Traction Transformers

In the existing technique for power electronic converters with low switching frequency and multiple cells, the sampling frequency is always set at the same value as the control frequency, and the modulating wave in each cell updates itself when its corresponding carrier reaches its peak and valley. In this paper, this implementation scheme is denoted by asymmetrically sampled-pulsewidth modulation (AS-PWM). It is proven that AS-PWM suffers from three defects: further increase of switching frequency is restricted by the available control period and the total cell number; long modulator delay exists and may bring the control system into instability if high crossover frequency is chosen; and spectrum aliasing toward the digital modulating waves may occur and makes the ac input current distorted. Therefore, another implementation scheme of carrier-based digital PWM is recommended in this paper, which is denoted by multisampled PWM (MS-PWM). In MS-PWM, all of the modulating waves update themselves at the same time. The research presented in this paper is based on a power-electronic traction transformer (PETT), which is made up of a cascaded H-bridge converter and several dc/dc converters. For the consideration of scalability, control, and reliability, a star-connected distributed control system is adopted for the PETT equipment. In order to make full use of this distributed hardware, and to improve the control performance with relatively low requirement toward the digital chips, a universal-type multirate structure is proposed in this paper, which is based on the MS-PWM technique. In the proposed structure, the sampling frequency, control frequency, and modulating-wave updating frequency can be separated from the switching frequency, and each of them can be chosen independently according to the practical control demand and the hardware condition. There is no mutual effect between their selections. The influence of the variation of these three frequencies on the control performance is analyzed as well. At last, experimental results based on a five-cell PETT laboratory prototype with a rated power of 30 kW are provided, and all of them verify the effectiveness and correctness of the proposed algorithms.

Realization of 24-Sector SVPWM With New Switching Pattern for Six-Phase Induction Motor Drive

The six-phase asymmetrical induction motors (SPIMs) are employed for high power medium voltage drive due to its attractive features of reduced stator copper loss, lower torque pulsation, higher torque per ampere, and higher reliability. In this paper, analysis of carrier-comparison-based pulse width modulation (PWM) techniques namely sinusoidal PWM and double zero-sequence injection PWM are carried out from a space vector perspective. Furthermore, new space vector pulsewidth modulation (SVPWM) techniques are developed by modifying the switching sequences of carrier-based PWM techniques. A comprehensive analysis of these PWM techniques is carried out in terms of harmonic flux trajectories, squared harmonic flux, and harmonic distortion factor (HDF). As a result, modified SVPWM technique namely 6ΦSVM3 is found superior to aforesaid PWM techniques, which significantly reduces HDF and provides lower current total harmonic distortion (THD). The experimental results of aforementioned PWM techniques are obtained and verified from six phase asymmetrical induction motor fed by dual two-level 3ΦVSIs. This paper is also accompanied by a video file of experimental test setup recorded while 6ΦSVM2 is running on SPIM.

Bidirectional Three-Phase DC–AC Converter With Embedded DC–DC Converter and Carrier-Based PWM Strategy for Wide Voltage Range Applications

A bidirectional three-phase dc–ac converter with embedded dc–dc converter for bidirectional storage interface is proposed in this paper. With the help of the embedded dc–dc converter, the voltage of the storage battery can vary in a wide range. To minimize the power rating and power losses of the embedded dc–dc converter, a simple carrier-based pulsewidth modulation (PWM) strategy with zero-sequence injection is proposed. By adopting the proposed PWM strategy, only a small ratio of total power needs to be processed by the embedded dc–dc converter, while most of the power is only processed by the three-phase dc–ac stage within a single conversion stage. As a result, quasi single-stage power conversion is achieved to improve the conversion efficiency of the overall dc–ac power system. Principles, characteristics, and implementations of the proposed three-phase dc–ac converter and its PWM strategy are analyzed in detail. The feasibility and effectiveness of the proposed solutions are verified with experimental results.

Simplified implementation of SVPWM techniques for a six‐phase machine with reduced current distortion features

In this study, space vector pulse width modulation (SVPWM) methods for six-phase asymmetrical ac drives are discussed including continuous and discontinuous switching sequences. These switching sequences are adapted from the carrier-based PWM techniques. Some additional sequences are also derived which reduce the intricacy of programming algorithm. Total six pulse width modulation (PWM) techniques are selected for simulation and experimentation. The comparative performances of these modulation techniques are studied in terms of harmonic distortion factor (HDF), torque and current ripples and switching losses. Based on study, a new PWM technique termed as 6SVM3-B2 is found that leads to the lowest HDF and current ripple in prototype model.

CARRIER BASED PWM TECHNIQUE AND ADAPTIVE NEURAL NETWORK BASED ROTOR RESISTANCE ESTIMATOR FOR THE PERFORMANCE ENHANCEMENT OF VECTOR CONTROLLED INDUCTION MOTOR DRIVES

In this paper, the carrier based Pulse Width Modulation (PWM) technique and neural network based rotor resistance estimator are proposed for vector controller Induction motor (IM) drives. The popular sine PWM is used for induction motor drive. The popular sine PWM has poor harmonic profile and (DC) utilization. The space vector modulation (SVM) technique overcomes the disadvantages of sine PWM. But SVM is computationally complex. Hence a simple PWM technique namely “carrier based PWM technique” similar to SVM is identified and proposed for vector controlled IM drive. The experimental set up is built up and the performance of carrier based PWM is validated using FPGA processor. The adaptive neural network based rotor resistance estimator in predictive mode is proposed for the vector controlled induction motor drive. The performance enhancement of the drive with carrier based PWM and rotor resistance estimator is comprehensively presented.

Comprehensive analysis of three- and five-phase PUC inverters with harmonic injection modulation techniques

Multiphase power electronic converters are gaining more popularity nowadays. Three-phase system is not enough to produce smooth torque in industrial application. So systems that have more than three phases are gaining popularity due to their smooth torque and more power than the three-phase systems for the same phase voltage and current. Selection of even number of phases is generally avoided because it degrades motor performance due to the coincidence of motor poles with each other. This paper deals with carrier-based pulse width modulation techniques with the third-harmonic and fifth-harmonic injections in three-phase and five-phase five-level packed U-cell (PUC) inverter. Harmonic injection gives improvement in DC bus utilization without going into the overmodulation region. The viability of this concept is verified by MATLAB/Simulink by taking the three-phase and five-phase VSI as an example. The relation between the three-phase and five-phase voltage and power is analyzed and verified mathematically. The PUC inverter comprises the least number of device count, so it can be a good option for multiphase application in industrial drives.