Synchronous Pulsewidth Modulation Research Articles

DC Regulation and Loop Gain Analysis of a DC-DC Switch Mode Power Supply: A Case Study on a Synchronous PWM Controlled Buck Converter

This study investigates the DC regulation of a DC-DC buck converter operating with pulse width modulation (PWM), taking into account the internal resistance of the coil and the on-resistance of the switching device. The effect of these parameters on the input/output disturbances is analyzed in continuous-conduction mode under constant frequency voltage mode control. The study also explores the effect on loop gain using the IRU3037 8-pin IC synchronous PWM controlled buck converter. The transfer function of the IRU3037 IC is derived from datasheet values using state-space averaging and AC small signal methods. A Type II compensator is then designed based on the derived transfer function. In addition, the step response characteristics of the open-loop and closed-loop circuits are investigated by time domain analysis.

Comparative Study of Advanced Modulation and Control Schemes for Dual Three-Phase PMSM Drives With Low Switching Frequencies

In this paper, multiple advanced low-switching-frequency modulation and control schemes are investigated for dual three-phase permanent-magnet synchronous motor (PMSM) drives. The modulation schemes under investigation include multisampling space vector modulation (MS-SVM), selective harmonic elimination pulse width modulation (SHEPWM) and synchronous optimal pulse width modulation (SOPWM) while the control schemes include complex vector control, model predictive control (MPC) and flux trajectory control-based model predictive pulse pattern control (MP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C). The difference between three-phase and dual three-phase PMSM drives at low switching frequencies is analyzed. Moreover, an optimal pulse width modulation (PWM)-based MP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C scheme is proposed for the dual three-phase PMSM, where the optimal PWM modulation and MP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C control are combined such that the optimal steady-state and dynamic control performance is achieved among the modulation and control schemes investigated. Experimental results are given to compare and validate the proposed control scheme.

Photovoltaic Power Conversion System Based on Cascaded Inverters with Synchronized Space-Vector Modulation

The paper presents results of investigation of dual-inverter-bases power conversion system with synchronized pulsewidth modulation (PWM) for photovoltaic application. This system topology includes two insulated strings of photovoltaic panels, feeding two standard three-phase inverters, connected to grid by a three-phase transformer with the open winding configuration on primary side. Algorithms of synchronized PWM provide in this case continuous voltage synchronization both in each inverter and in the load. Simulations show a behavior of the systems with low switching frequency, with both continuous and discontinuous versions of synchronized PWM.

Power Conversion Systems with Synchronous Control and Regulation on the Base of Powerful Diode-Clamped Inverters via Pulse Width Modulation

This article provides a brief overview of the development and dissemination of the method of synchronous multi-zone pulse-width modulation (PWM) in relation to the regulation of diode-clamped inverters which are the main executive elements of the medium-power and high-power adjustable speed electric drives. It is shown that the modified schemes and algorithms of synchronous multi-zone PWM, applied for control of diode-clamped inverters, assure providing minimization of the common-mode voltage in systems, as well as continuous synchronization and symmetry of the base phase and linear voltages in drive systems on the base of diode-clamped inverters over the entire control range. There are no even harmonics and subharmonics in the spectra of the phase and line-to-line voltages of three-phase and six-phase drive systems, which helps to reduce losses in systems and increase the efficiency of their operation. As a result of a comparative analysis of the integral spectral characteristics of the main voltage waveforms of adjustable speed drives based on diode-clamped inverters, recommendations are formulated for the rational choice of schemes and algorithms of synchronous multi-zone PWM for the relevant systems and installations, depending on their operating modes.

Active Neutral Point Clamped Three-level Synchronous Space Vector Width Modulation Research

Active neutral point clamped (ANPC) topology is widely studied because it makes loss equalization possible. To reduce the switching frequency of high power traction systems, the multi-mode modulation strategy is used in many modulation methods. To reduce the fluctuation problem when switching between different carrier ratios in multi-mode synchronous space vector pulse width (SSVPWM) modulation algorithm, this paper studies the stator flux under different modes and proposes a multi-mode SSVPWM switching strategy based on the pulse insertion method. In this strategy, the stator flux deviation of two modes before and after the switching point is calculated online and the switch sequence is inserted at the switching time to compensate, and the smooth transition between different modes is realized with experimental verification of validity.

EVOLUTION AND DISSEMINATION OF SPECIALIZED STRATEGIES, METHODS, AND TECHNIQUES OF SYNCHRONOUS PULSEWUDTH MODULATION FOR CONTROL OF VOLT-AGE SOURCE INVERTERS AND INVERTER-BASED SYSTEMS

This publication provides a brief historical overview of the development of methods and techniques of pulsewidth modulation (PWM) for voltage source inverters, published mainly in Ukrainian publishing houses and in Ukrainian periodicals. Accent has been done to review of results of investigation of alternative methods and techniques of synchronous space-vector-based multi-zone PWM for inverters with low switching frequency. In particular, in the mentioned publications, the basic strategies, schemes, and algorithms of synchronous multi-zone modulation have been further developed, modernized, modified, and disseminated in relation to new promising topologies of power conversion systems, including: two-inverter-based electric drives with open-end winding of electrical motor; dual three-phase electric drives of symmetrical and asymmetric types; powerful six-phase systems based on four inverters, and two-inverter-based and three-inverter-based photovoltaic installations with multi-winding transformer. It is shown that the developed schemes and algorithms of synchronous space-vector PWM, applied for control of inverter-based systems, provide continuous synchronization and symmetry of basic voltage waveforms of systems during the whole control range including zone of overmodulation of inverters. It provides minimization of even harmonics and undesirable subharmonics (of the fundamental frequency) in spectra of the basic voltages of systems, leading to reducing of losses in systems and to increasing of its efficiency. Based on a comparative analysis of the integral spectral characteristics of the phase and line voltages of systems, recommendations are formulated for the rational choice of schemes and algorithms of synchronous modulation for the relevant installations, depending on the modes of their operation. References 30, tables 2, figures 25.

Synchronous Optimal PWM With Continuous Switching-to-Fundamental Frequency Ratio

In high-power applications, the synchronous optimal pulse width modulation (SOPWM) serves as a vital modulation method that achieves an excellent tradeoff between the switching losses and the current harmonic. However, the optimized pulse patterns of SOPWM are constrained due to the discrete pulse numbers, which leads to the underutilization of the allowable maximum switching frequency. Therefore, the corresponding current harmonic could not be reduced as low as possible. In response to this issue, the SOPWM with a continuous switching-to-fundamental frequency ratio is proposed in this article. First, the deduction of the traditional pulse patterns is introduced based on the symmetry of the voltage pulse waveform. Then, the principle of the proposed strategy is illustrated in detail, and an overall comparison with traditional SOPWM is given theoretically. With the proposed strategy, a considerable reduction of the current THD is achieved over almost the whole high-speed range, and the losses and efficiency of the system are analyzed by the finite element method (FEM). Finally, theoretical results are verified by simulation and experimental tests.

Optimized Synchronous Pulse Width Modulation Strategy Based on Discontinuous Carriers

This article proposes a new technique called optimized discontinuous carrier pulse width modulation (ODCPWM), whose main objective is to solve the issue of significant output voltage harmonics of conventional synchronous carrier modulation at low carrier wave ratios. Based on the symmetry principle, the fundamental wave period is divided into regions; the carriers in adjacent regions are flipped, and the carrier width is changed symmetrically in each region to generate an unequal-width optimized discontinuous carrier pulse width modulation. In addition, using the weighted total harmonic distortion (WTHD) of the line voltage as an evaluation index, an optimized multi-mode PWM strategy is proposed to satisfy the system to operate stably in the whole speed range. The experimental results verify the effectiveness of the proposed strategy. The results show that ODCPWM proposed in this article can eliminate harmonics and multiples of three harmonics in line voltage harmonics. The VWTHD is lower, which improves the quality of the output waveform and makes the system operation more stable and reliable. The proposed multi-mode PWM strategy is smooth and shock-free during switching.

Open problem: WTHD reduction understanding for a synchronous saw-tooth injection PWM control

Third harmonic injection pulse width modulation (PWM) is a well known inverter control method improving the harmonics quality. Nevertheless this field of research is not closed and recent researches showed that a wide spread of third harmonics injection inside the zero sequence component of a synchronous carrier based PWM improves the voltage harmonics at the output of a three phases two-level inverter.Furthermore, for some specific parameters, this new zero sequence component modulation (ZSCM) seems to converge to a saw-tooth shape. The presented research is the direct continuity of the previous paper on ZSCM [Bourgeade et al. (2021a)].The following work is attached to show a description and advantages of the saw-tooth injection PWM (STIPWM). As STIPWM is very singular in the literature, a mathematical understanding is judged necessary in order to find new PWM properties to stimulate power electronics control research.Then, this paper present to the community the STIPWM problem and an incomplete demonstration which leads to establish a conjecture, following a stimulating explanation will be found.

Synchronous PWM Control With Carrier Wave Phase Shifts for Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors (PMSMs) are utilized in a wide range of applications as high-power-density and highly efficient drive sources. However, a PMSM generates electromagnetic vibration and loss caused by space and time harmonics. In this article, we propose a synchronous pulsewidth modulation control method for shifting the carrier wave phase against the modulation wave phase. As the proposed control matches the vibration frequencies caused by space and time harmonics, the pulsation caused by the space harmonics is canceled out by the pulsation caused by the time harmonics with the phase shift of the carrier wave. Experiments on the proposed control demonstrate that vibration at a specific frequency was reduced by 46% at 7900 rev/min. In addition, to change the carrier phase with small <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current harmonics, magnet eddy-current loss was reduced by shifting the carrier wave phase. The temperature of a magnet was measured in a heat-run test, and the temperature rise of the magnet could be suppressed by 5 K.

GRID-CONNECTED PV SYSTEM EMPLOYING THREE INVERTERS REGULATED BY SYNCHRONOUS SCHEME OF PWM

The paper presents comparative analysis of three versions of the modified scheme of space-vector-based synchronous pulsewidth modulation (PWM), applied for control of three two-level inverters of transformer-based photovoltaic (PV) system, and focused on providing of the symmetry of winding voltage of power transformer during the whole adjustment range. Power supply of inverters is providing by the corresponding three solar strings consisting of a set of PV panels, and the outputs of three inverters are connected specifically with inverter-side windings of multi-winding grid-tired transformer. Results of MATLAB-simulation prove the fact of advanced spectral composition of the winding voltage of triple-inverter-based PV installation regulated by algorithms of synchronous space-vector PWM, assuring potential reduction of losses in these systems. References 10, table 1, figures 9.

Methods and techniques of synchronous multi-zone modulation for the control of power electronic converters

This paper presents a short survey of the results of elaboration and investigation of novel methods, schemes, and algorithms of synchronous multi-zone space-vector modulation of signals in power electronic converters of electrical energy parameters, focused on improvement of operation efficiency of converter-based transport-oriented electric drives and of photovoltaic power conversion systems, which were published mainly in the two-year period 2019–2020. These methods and algorithms of synchronous pulse-width modulation (PWM) allow providing continuous synchronization and symmetries of waveforms of the converters output voltage, with minimization of undesirable sub-harmonics in spectra of voltage and current, and also with minimization of undesirable common-mode voltage in electric transport systems and in photovoltaic systems, which leads to corresponding loss reduction and efficiency increasing of these systems.

A Bidirectional Symmetrical C4LC-DCX Resonant Converter With Power Limitation Capability

To achieve the maximum efficiency of resonant converter under wide voltage conversion gain range, two stage conversion, which adopts the resonant converter operating at resonant frequency to work as a dc–dc transformer (DCX) in isolation stage, is a preferred solution. This article proposes a bidirectional C4LC resonant converter to work as a DCX. The structure of the topology is totally symmetrical, and two auxiliary inductors are used to achieve full load range zero-voltage-switching (ZVS) for all the power switches under bidirectional power flow. Unlike conventional ZVS analysis, the ZVS of the proposed converter is analyzed with considerations of all the switch junction capacitors and load. The clamping diodes are also combined in the topology which can help achieve natural power limitation in case of overload and limit the startup current. Even though four inductors and one transformer are illustrated in the topology, all these magnetic components can be simplified and manufactured with one external inductor and one conventional transformer. Meanwhile, the converter operates at a fixed frequency and adopts the synchronous pulsewidth modulation (PWM) modulation, which can achieve constant voltage gain and automatically change the power direction without synchronous rectifier (SR) current detection. Finally, the experimental results from a 1-kW prototype verify the effectiveness of the proposed converter.

Reduced DC sensor based grid-interactive operation of single-stage solar photovoltaic water pumping system

ABSTRACT The grid-interactive operation of a single-stage solar photovoltaic water pumping system (SPVWPS) requires additional power electronic interface and a number of sensors. This paper realizes the grid-interactive operation of the single-stage SPVWPS with reduced sensor and without adding to the cost of the grid-interface converter. The single-phase grid is connected directly with the SPVWPS and the three-phase inverter is controlled as a single-phase grid-interactive inverter. The motor winding inductance is utilized as a current filter. This arrangement functions as a photovoltaic-static synchronous compensator (PV-STATCOM) with voltage-oriented current control by feeding the peak solar photovoltaic (SPV) power to the grid and supporting the reactive power to alleviate steady-state grid voltage variations. The modified adaptive second-order generalized integrator (SOGI) is utilized for effective grid-angle estimation under the presence of DC-bias in the input signal. The modified perturb and observed maximum power point tracking (MPPT) technique is implemented using grid-side quantities, which curtails the requirement of the SPV current sensor. Extensive experiments are performed on the developed prototype under the variable atmospheric and the variable grid voltage conditions. The presented grid-interactive SPVWPS is realized with single power electronics device and three sensors. The cost of power electronics interface is reduced in presented single-stage grid-interactive SPVWPS by 22% compared to two-stage grid-interactive SPVWPS. Abbreviations: FLL: Frequency Looked Loop; PFC: Power Factor Correction; FFT: Fast Fourier Transform; PV: Photovoltaic; SPVWPS: Solar Photovoltaic Water Pumping System; MPPT: Maximum Power Point Tracking; P & O: Perturb and Observe; SPV: Solar Photovoltaic; OSG: Orthogonal Signal Generator; PWM: Pulse Width Modulation; SOGI: Second-order Generalized Integrator; PEC: Power Electronic Converter; RMS: Root Mean Square; VSI: Voltage Source Inverter; PF: Power Factor; RMF: Rotating Magnetic Field; VSC: Voltage Source Converter; PI: Proportional Integral; SySPWM: Synchronous Sine Pulse Width Modulation

Variable Switching Frequency Control-Based Six-Step Operation Method of a Traction Inverter for Driving an Interior Permanent Magnet Synchronous Motor for a Railroad Car

Most railroad cars employ a natural ventilation cooling method. For this reason, severe problems occur in the control devices for the railroad cars due to the heat generated by the high-power switching loss. Therefore, the traction inverter for the railroad car requires a control method that can reduce the switching loss. In this paper, we propose a control method for an interior permanent magnet synchronous motor in consideration of the driving conditions of the railroad cars. The proposed method combines a variable switching frequency-based synchronous pulse width modulation control method, a flux-weakening control method that considers the maximum voltage modulation index, and an optimized over-modulation method. Through the proposed method, the utilization rate of the DC-link voltage can be maximized while lowering the switching frequency of the traction inverter as much as possible, and the high-performance current control can be performed in the entire speed region of the railroad car. The validity and effectiveness of the proposed method are verified by the simulation results and the experimental results.

FPGA based synchronous multi-channel PWM generator for humanoid robot

In this paper, synchronous multi-channel pulse width modulation (PWM) generator for driving servo motors of humanoid robot was proposed. In an application, the humanoid robot requires smooth and beautiful movement, therefore the PWM signal for each servo motor must be synchronized. Since microcontroller (slave) has no enough channels to generate synchronous PWMs for 32 servo motors, field programmable gate array (FPGA) was used as slave for the humanoid robot. The FPGA was controlled by microcontroller (master) using serial communication. Simulation results show the system can perform serial communication, synchronize, and convert data well. The system can also generate PWM simultaneously with accurate duty cycle and fix period of 20ms.

Si/SiC hybrid 5-level active NPC inverter for electric aircraft propulsion drive applications

Medium voltage DC(MVDC) system is considered as a promising technology to improve the efficiency and power density of electric aircraft propulsion(EAP) drives. To adapt to the MVDC voltage level and achieve high drive performance, a five-level active neutral point clamped(5L-ANPC) inverter consisting of three-level ANPC and flying capacitor circuits is investigated, which possesses higher voltage capability, lower output harmonics, as well as mitigated dv/dt and common-mode voltage. To fulfill the requirements of high-speed operation and pursue further enhanced efficiency and power density of the inverter for the next-generation EAP drives, Silicon Carbide(SiC) semiconductor devices are considered for implementing the 5L-ANPC inverter. However, the large commutation loops associated with certain switching states of the inverter lessen the benefits of configuring all the switches as SiC devices. As a result, a hybrid Si/SiC 5L-ANPC inverter is developed with a synchronous optimal pulse(SOP) width modulation strategy for controlling the switches in cell 2 and finite-control-set model predictive controller(FCS-MPC) for those in cell 3 of the inverter. Consequently, in the proposed topology, the SiC devices are merely used for the high-frequency switches in cell 3 and the rest of the low-frequency switches are configured with Si IGBTs. This Si/SiC hybrid ANPC inverter concurrently provides high efficiency and low implementation cost at high-speed operation mode. Simulation and experimental results are provided to verify the effectiveness of the proposed hybrid inverter.

Multipurpose battery‐assisted solar water pumping system for off‐grid applications: design and development

Providing basic human needs like water and household electricity is a challenging task at remote locations. To support both needs, this study presents the development of a multipurpose battery-assisted solar water pumping system (SWPS). The system consists of only two power electronics converter, viz., bidirectional DC–DC converter, and three-phase voltage source inverter (VSI). The detailed control system is presented, where the DC–DC converter controls the battery power and also ensures the maximum utilisation of stand-alone solar photovoltaic source. In pumping operation, the VSI is operated as a variable frequency motor drive and rotates an induction motor (IM) at the rated power to deliver rated water discharge. In power supply operation, the household electrical load is connected between the mid-point of DC-bus and the star point of an IM winding. The VSI, along with motor inductance, realises the single-phase inverter, which is controlled with synchronous sine pulse-width modulation to deliver single-phase output. The motor does not rotate during this operation and the motor winding acts as a current filter. This multipurpose SWPS assures rated water discharge during the irrigation period and availability of electrical power in the remaining period. A prototype is developed and extensive experiments are performed to investigate system performances.

Development of grid‐interactive inverter utilising induction motor driven photovoltaic water pumping system

The stand-alone solar photovoltaic water pumping system (SPVWPS) remains idle for a significant period of time, when irrigation is not required and when sun is not available. Due to this large idle period, the effective utilisation of SPVWPS assets, i.e. solar photovoltaic array, power electronics converter, and motor, is poor. This study presents an approach to increase the effective utilisation of SPVWPS under the aforementioned idle period. It is proposed to interface the grid with SPVWPS without adding extra power electronic interface. An innovative integrated photovoltaic inverter is constructed using existing SPVWPS components. The inverter enables the transfer of active power and exchange of reactive power with the grid during an idle period of SPVWPS. The three legs of the voltage source inverter (VSI) are interleaved with motor windings. The VSI switches are controlled with synchronous pulse width modulation to force a cophasal current in the motor windings. This accompanies a net motor torque to zero under grid-interactive operation. Hence, the three-phase VSI operates as a single-phase grid synchronise converter, and the motor windings are used as filter inductance. The control system is presented to establish grid-interactive functionality. A prototype is developed to verify system performance. The control system is implemented using the ARM Cortex-M4 microcontroller.

Analysis and Transition Techniques for a Bidirectional DC–DC Converter

This article proposes two new pulsewidth modulation (PWM) schemes, namely, asynchronous PWM scheme (APS) and synchronous PWM scheme (SPS), for a nonisolated fourth-order bidirectional dc-dc converter (FOBDC), which are implemented to achieve a smooth start-up operation and mode transition to reverse the direction of power flow. The presented FOBDC is reported already in the literature as a unidirectional boost converter, the functionality of which is modified in this work, to enable bidirectional power flow. The FOBDC can operate in either discharging (Mode-I) or charging (Mode-II) mode. The overshoot/undershoot of inductor currents in the FOBDC occur during converter start-up operation in either of the modes and while transitioning modes (from charging to discharging and vice-versa). To eliminate the overshoot/undershoot of inductor current, two effective transition techniques are developed for smooth start-up operation and mode transition, thereby reducing the delay time significantly. The FOBDC is modeled using the state-space modeling technique, and duty ratio-to-inductor current transfer function is derived, which is validated for resistive load and battery load. Two different compensators are designed for these two transfer functions to achieve an average current-mode control (ACMC) during the charging and discharging modes of operation. The performance of the compensators is evaluated by introducing perturbations. A 12-48-V FOBDC converter, controlled by these PWM techniques with the aforementioned features, is designed, analyzed, and experimentally verified for low-power applications.