A new carrier-based discontinuous PWM modulation methodology for four-leg voltage source inverters

In this work, a new carrier-based pulse width modulation (CPWM) scheme is built for three-to-three phase indirect matrix converter (IMC). In the existing CPWM schemes, the control schemes of the source side converter of the IMC are developed based on either sector based complex calculations or over-modulation operation to obtain the required performance. In the new CPWM scheme, the simplified modulation equations for the source side converter of the IMC are proposed which provide the required performance without resorting to the sector based duty cycle calculations or over-modulation operation. The source and load side converter stages of the IMC are modulated with the standard CPWM principles of the conventional inverter and rectifier topologies in the present work. This work also compares the new CPWM scheme with the SVPWM scheme based on the mathematical calculations which proves that the new CPWM scheme requires less mathematical operations as compared to SVPWM scheme. The simulation and experimental results for both modulation schemes are presented which proves that the new CPWM scheme provides the equivalent input and output performances to those of the SVPWM scheme. The control devices DSP (TMS320F28335) and FPGA (Spartan-6) are used to implement the CPWM and SVPWM schemes.

In this paper, a new carrier-based pulse width modulation (CBPWM) strategy combined the unipolar and dipolar modulations, is proposed for single-phase three-level rectifiers. The modulation rules are presented in detail. And the proposed CBPWM method can satisfy volt-second balancing principle in the whole modulation index region through compensation. When the normalized modulation signal is in the range from -0.5 to 0.5, it presents the dipolar modulation characteristics, and the main high-order harmonics caused by the proposed CBPWM distribute around quadruple the switching frequency. When the normalized modulation signal is greater than 0.5 or less than -0.5, it presents the unipolar modulation characteristics, the main high-order harmonics caused by the proposed strategy, distribute around double the switching frequency. Therefore, the main high-order harmonics caused by the novel modulation strategy, distribute around double and quadruple the switching frequency in the whole modulation index region. The proposed modulation strategy has the advantages of the fewer high-order harmonics and the requirement of one carrier signal, compared with the traditional unipolar CBPWM. The experimental results verify the feasibility and effectiveness of the proposed novel CBPWM strategy.

This paper studies the relations of space-vector modulation (SVM) and carrier-based pulse-width modulation (PWM) for multilevel inverter. The PWMs' generation of SVM can be achieved by carrier-based PWM scheme, but the modulated wave of SVM is acquired by vectors' calculations and switching-states' selection. Based on different selection of redundant switching-states, there are many types of SVM modulated waves, some of which can function equivalently through proper selection of common-mode injections in the case of carrier-based PWM, the others have more freedoms in switching-states' selection than carrier-based PWM. Selection of more switching-states in SVM is propitious to optimize the output voltage, balance the dc power and so on. Then an improved PWM scheme is proposed based on the modulation waves of three-level SVM, which reserves the main advantages of SVM, and can be achieved easily. Finally, a five-level test circuit is built to verify this PWM scheme.

Continuous and discontinuous pulse-width modulation (PWM) schemes and a novel space vector modulation methodology are proposed in this paper for four-leg DC-AC inverters. Using a space vector definition that includes the zero sequence voltage component and partitioning the feasible sixteen modes into two separate sets-one set having zero sequence voltages with positive magnitudes and the other set with the zero sequence voltages with negative magnitudes-the novel space vector implementation technique is determined as also the discontinuous carrier based PWM scheme. For the continuous carrier based PWM scheme, the indeterminate defining output voltage equations expressed in terms of the existence functions of the switching devices are solved using an optimization technique. The modulation schemes determined are shown by experimental results to synthesis any desirable balanced or unbalanced three-phase voltage sets when operating in the linear modulation region.

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.

As an advanced power electronic topology, the three-level dual output converter combines three-level technology with dual output characteristics, which has significant advantages in industrial, energy and transportation applications. Achieving capacitor voltage balance and improving dc bus voltage utilization are the key technologies in the application of three-level dual output converter, but it is challenging to satisfy both of them at the same time. In this paper, the optimal carrier-based pulse width modulation (CBPWM) strategies are proposed to address the above problems. By analyzing the effects of three different zero-sequence voltages on the midpoint voltage of the voltage-divider capacitor, two optimized CBPWM strategies based on the injection of different zero-sequence voltages are proposed, which can effectively improve the dc bus voltage utilization. Based on the above different zero-sequence voltages injection strategies, the capacitor voltage balancing method is proposed to control the average midpoint current, which can realize the capacitor voltage balance within different modulation ranges of two sets of outputs. Finally, the effectiveness of the proposed modulation strategy is verified through experiments.

A new switching scheme, which combines conventional space vector modulation (SVM) and carrier-based pulse width modulation (CBPWM), is proposed for a three-phase four-leg voltage source inverter (VSI). The proposed algorithm is simpler than conventional three-dimensional space vector modulation (3-D SVM) and easy in implementation in a real-time DSP system, it avoids the selection of a prism and tetrahedron in a 3-D SVM, therefore alleviates the computation burden of the DSP. Also, the concept of near-state pulse width modulation (NSPWM) method, which is used in a three-phase three-leg inverter to reduce the common mode voltage (CMV) noises, can be adopted in this algorithm so as to reduce the common mode voltage for a three-phase four-leg VSI. The feasibility of the proposed modulation technique is verified by both computer simulation and experimental results.

Two generalized discontinuous carrier-based pulse-width modulation (GDPWM) methodologies for three-phase current source converters (CSC) are developed based on the classical space vector method and the carrier-based generalized discontinuous modulation scheme for voltage source converters (VSC). With feasible operation in both the linear and overmodulation regions, they provide the known advantages of the discontinuous carrier-based modulation in voltage source converters-reduced switching loss and reduced effective switching frequency especially in the overmodulation region. These modulation schemes are implemented for a current source inverter from which experimental results are presented to verify concepts and theory.

This paper proposes a carrier-based pulse-width modulation (CBPWM) scheme for N independent three-phase loads using the general (3N+3)-switch converter. The proposed topology is derived from the nine-switch converter which is gaining considerable interest from researchers because it costs less due to its reduced number of active switches. The structure and limitations of the converter are elaborated; its modulation scheme is formulated in this paper. The generalized neutral voltages for the converter is derived for the first time and used as the offset voltages required by this type of topology to decouple the converter's N outputs. The proposed algorithm is validated by both theoretical simulation and experimental results using the 9-switch and 12-switch topologies as case studies.

In this paper, a feedforward proportional carrier-based pulsewidth modulation (PWM) is proposed for the dc link control of the single-phase cascaded H-bridge multilevel photovoltaic inverter. The conventional carrier-based PWM techniques, such as the phase-shifted PWM and the level-shifted PWM, require multiple individual dc voltage controllers for the individual maximum power point tracking (MPPT). Thus, the control structure and the controllers' designs are quite complex. Several noncarrier-based PWM techniques, such as the feedforward space vector modulation, the sorting-algorithm-based modulation, and the lookup table-based modulation, have the capability of individual dc voltage regulation. Although these noncarrier-based PWM techniques require only one total dc voltage controller in the outer voltage loop, the implementations of them are much more complicated than those of the carrier-based PWM techniques. In this paper, with the proposed feedforward proportional carrier-based PWM, each individual modulation signal is directly generated by multiplying the current loop controller's output and the modulation signal's feedforward proportional factor. With the feedforward PWM and the total dc voltage control, the individual dc voltage regulation is achieved. This carrier-based PWM combines the strengths of both the traditional carrier-based PWM and the noncarrier-based PWM. It is not only easy for implementation, but also requires only one total dc voltage controller in the outer voltage loop. The detailed description, derivation, and analysis of this modulation are included in this paper. In addition, the simulations and experiments demonstrate the performance of the dc link control and the individual MPPT using the proposed PWM and the control strategy.

This paper proposes the simplified pulse width modulation (PWM) strategy in the bidirectional ac/dc single-phase converter with the feed-forward control scheme. In this, the number of switching of the proposed simplified PWM strategy is reduced to one-fourth to that of the unipolar & bipolar PWM. The feed-forward control scheme is used to achieve better performance of the ac/dc converter in both the rectifier & inverter mode as compared with the conventional dual-loop control scheme. The simplified PWM strategy with feed-forward control scheme has higher efficiency than that of the unipolar PWM & bipolar PWM strategies. Also, the total harmonic distortion is less in this PWM strategy. The simulation & experiments are carried out to verify the validity of the proposed PWM strategy & control scheme.

The latest trend in modern industrial application is the use of variable voltage supply to the AC drives from a three phase voltage source inverter (VSI). Different types of Pulse Width Modulation (PWM) scheme are used to modulate output voltage of VSI. The most commonly used PWM schemes for three-phase VSI are carrier-based sinusoidal PWM and Hybrid Space Vector PWM (HSVPWM). Researchers adequately prefer the use of HSVPWM because of their easier digital realization and better dc bus utilization. The advantages of HSVPWM are reduction of total harmonic distortion, improvement in output voltage and reduction of torque ripple in induction motor drives. This paper provides a comprehensive literature review on different topologies of HSVPWM. These includes Advanced Bus Clamped SVPWM (ABCSVPWM), Neutral Point Clamped SVPWM (NPCSVPWM) and Diode Clamped SVPWM (DCSVPWM).

PurposeThis paper aims to propose Hidden Converter (H-Converter) combined with dual port 3Ø inverter for energy storage application to produce wide range of voltage. Some of the application required wide range of voltages, but problem from E-chopper is either boost or buck mode of operations, both modes are not possible. To overcome this drawback, H-Converter is combined with dual port 3Ø inverter controlled by carrier-based pulse width modulation (CB-PWM) technique is added with zero sequence injection.Design/methodology/approachHidden converter is a bidirectional DC-DC chopper used to convert fixed DC to variable DC and vice versa in both buck and boost modes of operations. Dual port inverter is combined with hidden DC-DC converter can produce wide range of voltages.FindingsThe bidirectional DC-AC converter requires less power for processing and consumes less power losses by using modest carrier built- pulse width modulation scheme through proposed zero structure addition.Originality/valueBy using this proposed strategy H-Converter can produce wide range of voltage in both the sides and mostly power is processed in the 3Ø inverter with a one stage conversion with less power loss. As a result, with one stage power conversion has more efficiency because of less power loss. This proposed converter has designed by analysis, and the real time result is tested in an experiment.

This paper proposes a modified modulating signal-based pulse width modulation (PWM) scheme for a neutral point clamped (NPC) inverter-based induction motor drive (IMD) for enhancing the power quality of solar photovoltaic (PV) fed water-pumping systems. During the previous several decades, the use of sustainable source-based power generation systems has benefited water pumps in household life, irrigation-based activities, and industrial sectors, especially in areas where the electric grid is less available. A critical concern has long been the power quality, speed, and torque of an induction motor used in solar PV-powered water pumping. This paper focuses on the improvement of power quality performance by minimizing total harmonic distortions (THDs), switching losses and conduction losses, and torque ripples in the induction motor driving the PV-fed water pump by using a modified PWM scheme that generates symmetrical and balanced gate driving signals for the NPC inverter employed in the IMD. The IMD with the suggested PWM switching strategy has been tested in all feasible induction motor operating situations. To demonstrate the effectiveness of the suggested PWM scheme, a performance comparison of the proposed PWM scheme with conventional PWM schemes is performed, and also the IMD with the suggested PWM switching strategy is tested in all feasible induction motor operating situations using the MATLAB/Simulink platform. A reduced scale prototype has also been built and tested in laboratory to validate the performance of the proposed PWM technique.

Pulse width modulation (PWM) strategies for the control of asymmetrical six-phase drives have been widely studied since the beginning of this century. Carrier-based and different space vector PWM algorithms have been developed and evaluated. Nevertheless, there are still some challenges that require research work in this field. This paper deals with this topic, and introduces three space vector techniques. The methods are based in a recently developed scheme that combines the nearest two medium and two large size voltage vectors to synthesise the reference vector. The schemes enable either sinusoidal or multifrequency output voltage operation modes. Theoretical derivation supported by closed-loop tests demonstrate the viability and potential of the proposal.