Modulation Inverter Research Articles

Error Calibration of Current Reconstruction Considering Noncentral Sampling for OW-PMSM Drive With Single Current Sensor

In this article, a novel current error calibration scheme considering noncentral sampling is proposed for an open winding permanent magnet synchronous motor (OW-PMSM) drive with a single current sensor. To realize the current reconstruction using a single current sensor, the durations of measurement vectors need to last long enough. Besides, the pulsewidth modulation (PWM) of the dual inverters is complicated, where the switching signals of two inverters need to be calculated simultaneously. Hence, the modified PWM strategy is developed to simplify the PWM procedure and extend the duration of measurement vectors. Nevertheless, the sampling error exists, because the bus current samplings take place sequentially at the measurement vectors instead of simultaneously at the central point. This will lead to a significant error in the reconstructed current, degrading the operation performance. Therefore, an online current calibration scheme is proposed to compensate for the current sampling error, which requires neither observer nor offline measurement to obtain the back electromotive force (back EMF). With the proposed calibration strategy, the precision of the reconstructed current can be significantly improved. Experiments are performed on an OW-PMSM drive to verify the effectiveness of the proposed strategy.

A Novel Four-Leg Inverter Topology for Dual Three-Phase PMSM

This article proposes a novel four-leg inverter topology to drive the dual three-phase permanent magnet synchronous motor (DTP-PMSM) with 180° phase shifting. Without access to the midpoint of dc bus capacitors, the proposed four-leg inverter can not only drive the DTP-PMSM with the same torque capability as the conventional six-leg inverter but also avoid the voltage fluctuations of the capacitors in the conventional four-leg inverter. Then, two kinds of pulsewidth modulation methods are given and compared for the proposed topology. The first one is the direct extension of the space vector modulation (SVM) of the four-switch inverter, denoted as SVM1, and the second one is to construct space voltage vectors utilizing almost all the switching states of the four-leg inverter, denoted as SVM2. Experimental results verify the feasibility of the proposed four-leg inverter topology and demonstrate the better harmonic performance of SVM2 compared with SVM1.

Research of a High Voltage Generator for Medical Diagnostic X-ray Equipment

A kind of designing scheme of high voltage generator for medical diagnostic X-ray equipment is proposed. A X-ray HV generator, which has output voltage from 60kV to 160kV and tube current from 1mA to 10mA, is developed successfully by applying the technology of LC series resonant soft-switching, high voltage doubling and rectifying, full bridge inverter and pulse width modulation. The topologic structure and simulating result are listed detailed, including high frequency inverter circuit, doubling and rectifying circuit and the controlling system. At last, the experimental data and waveform of the X-ray high voltage generator are presented, verifying the validity of the design scheme.

Iron loss evaluation method for SiFe sheet material under PWM inverter excitation

This study proposed an iron loss evaluation method for SiFe sheet material under high-frequency current ripple caused by pulse width modulation (PWM) inverter switching. The PWM inverter switching results in dynamic minor loops on the BH plane, leading to iron loss. Furthermore, in magnetic material with wide major loops, such as SiFe sheet material, the iron loss caused by one dynamic minor loop differs based on the flux density bias difference even for the same magnetic field bias. A previous study reported an iron loss calculation error because the conventional iron loss calculation method neglected the iron loss of the flux density bias characteristic in the same magnetic field bias. Therefore, we modified the previously developed iron loss measurement system to collect the iron loss of the flux density bias characteristic and proposed an iron loss calculation method for SiFe sheet material.

A novel power balance control scheme for cascaded H-bridge multilevel converters with battery energy storage

Battery energy stored quasi-Z source cascaded H-bridge based photovoltaic power generation system combines advantages of quasi-z-source inverter, cascaded H-bridge, and battery energy storage system. However, the battery state of charge imbalance between the cascaded H-bridge inverter modules would reduce the system's performance and efficiency and potentially cause the system to fail. An integrated control technique of adaptive state of charge balancing based on gain scheduling and three-phase power balance of third harmonic injection based on fundamental frequency whole zero sequences is suggested for the quasi-Z source cascaded H-bridge battery storage system. Based on the mathematical relationship between the instantaneous state of charge of battery energy stored quasi-z-source cascaded H-bridge and the voltage reference value, this method updates the proportional controller gain in each sampling period. It combines the third harmonic injection method based on the fundamental frequency zero sequence to select the optimal modulation ratio Mn. Rapid state of charge balancing is accomplished without overmodulation while increasing the power balance range and decreasing DC link voltage swings. The simulation results validate the method's usefulness. The simulation results validate the proposed control method for ensuring power distribution between each phase and achieving a balanced state of charge of the battery energy stored quasi-Z source cascaded H-bridge photovoltaic system's battery energy storage.

Locally-symplectic neural networks for learning volume-preserving dynamics

We propose locally-symplectic neural networks LocSympNets for learning the flow of phase volume-preserving dynamics. The construction of LocSympNets stems from the theorem of the local Hamiltonian description of the divergence-free vector field and the splitting methods based on symplectic integrators. Symplectic gradient modules of the recently proposed symplecticity-preserving neural networks SympNets are used to construct invertible locally-symplectic modules, which compositions result in volume-preserving neural networks LocSympNets. To further preserve properties of the flow of a dynamical system LocSympNets are extended to symmetric locally-symplectic neural networks SymLocSympNets, such that the inverse of SymLocSympNets is equal to the feed-forward propagation of SymLocSympNets with the negative time step, which is a general property of the flow of a dynamical system. LocSympNets and SymLocSympNets are studied numerically considering learning linear and nonlinear volume-preserving dynamics. In particular, we demonstrate learning of linear traveling wave solutions to the semi-discretized advection equation, periodic trajectories of the Euler equations of the motion of a free rigid body, and quasi-periodic solutions of the charged particle motion in an electromagnetic field. LocSympNets and SymLocSympNets can learn linear and nonlinear dynamics to a high degree of accuracy even when random noise is added to the training data. In all numerical experiments, SymLocSympNets have produced smaller errors in long-time predictions compared to the LocSympNets. When learning a single trajectory of the rigid body dynamics locally-symplectic neural networks can learn both quadratic invariants of the system with absolute relative errors below 1%. In addition, SymLocSympNets produce qualitatively good long-time predictions, when the learning of the whole system from randomly sampled data is considered. LocSympNets and SymLocSympNets can produce accurate short-time predictions of quasi-periodic solutions, which is illustrated in the example of the charged particle motion in an electromagnetic field.

On invertible modules and generalized bilinear forms

We construct invertible modules (as invertible linear spaces of matrices with an additional structure) and find a bijective correspondence between nondegenerate generalized bilinear forms and the invertible modules.

Power Factor Correction Modulated Wireless Power Transfer System With Series-Series Compensation

Power factor correction (PFC) is usually realized with a boost converter in a traditional power converter. This paper introduces a PFC modulated WPT method which can realize PFC function through phase-shift modulation of the primary-side inverter of a series-series (SS) WPT system. A close-loop control method of the phase-shift modulated system is also proposed for practical implementations. Without using a PFC converter, the structure of a WPT system can be simplified. Theoretical analysis and experimental results are provided to verify the idea.

Indirect Vector Control of Linear Induction Motors Using Space Vector Pulse Width Modulation

Vector control schemes have recently been used to drive linear induction motors (LIM) in high-performance applications. This trend promotes the development of precise and efficient control schemes for individual motors. This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation (SVPWM) inverters. The framework under consideration is developed in four stages. To begin, MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamic model. The research presents a modified SVPWM inverter control scheme. By tuning the proportional-integral (PI) controller with a transfer function, optimized values for the PI controller are derived. All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme. The reference speed values were chosen to evaluate the performance of the respective system, and the developed system’s response was verified using various data sets. For the low-speed range, a reference value of 10 m/s is used, while a reference value of 100 m/s is used for the high-speed range. The speed output response indicates that the motor reached reference speed in a matter of seconds, as the delay time is between 8 and 10 s. The maximum amplitude of thrust achieved is less than 400 N, demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple. Due to the controlled speed range, the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.

Integration of solar and wind energy systems with PI and PID controller

Because of the rising worry about global warming and the depletion of fossil fuel supplies, many individuals are looking into sustainable energy alternatives to protect the environment for future generations. Because of the situation of our deteriorating globe, eco-friendly items are more in demand than ever. The outcomes of using PI and PID controllers in solar and wind integration are compared in this research. This investigation contains a boost converter, an inverter, a converter, and three induction motors. Wind and solar energy are transformed to DC voltage, then to AC voltage via an inverter, and ultimately to a three-phase induction motor. The boost converter receives output from the wind energy conversion system (WECS). The solar output is routed to the three-phase complete converter. Sinusoidal pulse width modulation used in generating trigger pulses to the inverter. The output of the boost converter is fed into the common dc link by the three phase Sinusoidal pulse width modulation (SPWM) inverter, which converts its dc input to three phase AC output. This system's behaviour is examined using MATLAB Simulink.

Modified Dual Mode Transmission Gate Diffusion Input Logic for Improving Energy Efficiency

This paper presents a modified energy-efficient Dual Mode Transmission Gate Diffusion Input (DMTGDI) design and is termed as M-DMTGDI. A contention issue in dynamic mode operation of existing DMTGDI design and DMPL design is identified and illustrated through mathematical formulation and simulations. To resolve this concern, the pre-charge/pre-discharge transistor in existing DMTGDI design is replaced by dual mode inverter in the proposal. The functional verification and performance comparison of NAND, NOR, XOR gates and 1-bit full adder based on proposed M-DMTGDI is carried out using 90 nm BSIM4 model card for bulk CMOS using Symica DE tool. The performance of the circuits is evaluated in terms of power, delay and Power Delay Product (PDP) in both static and dynamic modes. The variation of PDP with the ratio of the time the circuit is designed to run in dynamic mode against static mode is also investigated to analyze the energy efficiency of the M-DMTGDI design. The proposed approach offers maximum PDP reduction of 33.52%, 99.39% and 96.61% for 2-input gates as compared to their footed DML, DMPL and DMTGDI counterparts, respectively. The reduction in PDP is quite significant in 1-bit full adder circuit where the corresponding values are 94.18%, 99.41% and 99.79%, respectively.

MODELLING AND SIMULATION OF THREE-PHASE FOUR-SWITCH VOLTAGE SOURCE INVERTER WITH SPACE VECTOR MODULATION

The three-phase six-switches voltage source inverter is usually used for industrial motor control and renewable energy systems. However, in order to decrease to size and cost of the drive systems, the three-phase four-switch voltage source inverter has been applied to low-cost motor control and renewable energy system. The fundamental concepts and principles of the three-phase four-switch voltage source inverter are discussed. The mathematical model and space vector modulation of the three-phase four-switch voltage source inverter are proposed. The work is demonstrated by simulation results.

Smart Switching Power Supply System for Evaporative Air Coolers

The energy consumption by residential air conditioners could cost about half of the total energy consumption of the building. A combination of conventional and renewable energy is still an emerging technology. Therefore, using solar photovoltaic panels to provide electricity to the air conditioner is a substantial application. This research shows the possibility of using photovoltaic panels as a power source for air conditioners in a sequence exchange with the conventional grid. A smart switching system has been offered to organize the power supply between the grid and solar panels. The photovoltaic panels have been connected to the conditioner across a power inverter module for adopting a reliable and accurate quantity of power supply to the conditioner unit. The smart switching system provides an intelligent connection between the solar power source and the grid, ensuring an uninterrupted electricity supply between the two power sources.

Improvement of power quality parameters using modulated-unified power quality conditioner and switched-inductor boost converter by the optimization techniques for a hybrid AC/DC microgrid

This study aims to improve the quality of operation parameters of the stand-alone hybrid microgrids (HMGs). The proposed module for the AC microgrid (ACMG) is a modulated-unified power quality conditioner (M-UPQC). Furthermore, the suggested component for the DC microgrid (DCMG) is a switched-inductor boost converter module (S-IBCM). The M-UPQC control method is based on inverter modules and the system resonant features. The aim of S-IBCM applied is to improve DC microgrid (DCMG) efficiency. In this paper, the research challenge consists of two sections: first, adjusting the control parameters of M-UPQC by the black hole optimization (BHO), Harris hawk optimization (HHO), and grasshopper optimization algorithm (GOA) techniques, respectively; second, presenting a new design of the BC module called S-IBCM to increase DCMG efficiency. The programmed multi-objective functions (MOFs) for M-UPQC contain the harmonic parameters. Finally, according to output results, the performance conditions for ACMG and DCMG divisions achieve significantly improved by the proposed modules adopted. Furthermore, the performance of the M-UPQC operating under static and dynamic disturbances is tested through an experimental setup.

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

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

Investigation of Electromagnetic Losses Considering Current Harmonics in High-Speed Permanent Magnet Synchronous Motor

This paper presents a characteristic analysis and experimental verification for predicting the electromagnetic losses in high-speed permanent magnet synchronous motors. To predict the operating characteristics (such as speed and input current), dynamic modeling is conducted that combines models for the space vector pulse width modulation (SVPWM) inverter and high-speed permanent magnet synchronous motor (HPMSM). By applying the predicted harmonic currents to the electromagnetic analysis, DC and AC copper losses of the stator winding, and eddy current loss of the rotor sleeve and rotor permanent magnet, are comprehensively analyzed using the finite element (FE) method. In particular, by analyzing the magnetic field behavior of magnetic flux density according to harmonics, a core loss analysis technique was presented. The validity of the hybrid analysis, which combines the stator copper loss and rotor eddy current loss derived from the FE analysis and the proposed core loss analysis, was verified through comparison with the experimental results under various operating conditions. Compared with the experimental results, the error of total losses using the hybrid analysis with a sinusoidal current was about 47.39%, and total losses using the hybrid analysis with a harmonic current was significantly improved to within 3.7%.

A Novel Multigain Single-Stage Grid-Connected Inverter With Asynchronous Switching for Intra-Inverter Circulating Current Elimination

At present, the single stage inverters are popular in integrating large-scale solar farms with distribution networks that demand higher dc bus voltage. The elevated dc potentials would degrade the reliability of the solar panels and inverter modules. In this work, the multiboost solar inverter topologies of three variants are presented for grid-connected applications. Since the proposed topologies aim to achieve higher voltage boost at ac side with reduced dc bus potential, it is required to use asynchronous switching strategies, unlike parallel inverter configurations. Although the proposed topologies are advantageous in-terms of improved reliability of solar panels and inverter modules, but instantaneous characteristic impedance imbalance due to asynchronous switching provokes circulating current within the inverter modules. Since the circulating current is undesirable concerning power quality and thermal aspects, in this work, the method of instantaneous impedance balance is ensured with the specially designed switching algorithm for proposed topologies. The eliminated instantaneous circulating current provides the flexibility of operating all inverter modules with the common dc bus. The proposed high gain boost configurations and switching methodologies are demonstrated on hardware prototype by pumping 2.4-kW power to the grid.

Coordinate Compression Strategy of Resistance and Reactance for MHz-Range Inverter System

This article proposes a coordinate impedance compression strategy for high frequency inverter systems. Based on a two parallel inverter structure, the strategy adopts two methodologies: 1) a passive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> network to adjust the current and voltage seen by each inverter module, and 2) an active modulation of the inverter input voltage and output voltage phase to adjust the load current distribution. For the proposed strategy, the resistance and reactance can be compressed coordinately, which can help the inverter to operate in high efficiency load range. The Half-Bridge Class D inverter is taken as an example to be analyzed. A 10-MHz prototype is built and the experimental results verify the correctness and feasibility of the proposed strategy.

Improved Weak Grids Synchronization Unit for Passivity Enhancement of Grid-Connected Inverter

The weak grids may be unstable due to the negative resistance behavior of the grid-connected inverter (GCI) caused by the synchronization unit with the phase-locked loop (PLL). This article proposes a passivity enhancement method to attain the positive output resistance of GCI in the qq channel. Initially, the impedance decomposition is utilized to reveal the reason for the negative output resistance brought by PLL. Secondly, with decomposed impedance, a novel PLL by adding a prefilter and an impedance phase regulator with a normalized amplitude to the input of traditional synchronous reference frame PLL (SRF-PLL) is proposed. Afterward, the effect of the critical system parameters and GCI operating conditions on the GCI’s passivity is discussed based on the established small-signal impedance model. Theoretical analysis manifests that the proposed PLL does not affect the system’s stability under rectifier mode and brings the passivity of GCI’s output impedance in the qq channel in broad system parameters under inverter mode. Lastly, the experiments are implemented, verifying that using the proposed PLL, the instability caused by the intersection between grid and GCI impedances is removed due to the passivity, and the system can operate at 1.0 per unit (pu) active power reference under the very-weak-grid conditions.

A New Type of Three-Phase Asymmetric-LCL Power Filter for Grid-Tied Voltage Source Inverter With Step-Up Transformer

Power filters have been widely used to suppress switching harmonics caused by the modulation of grid-connected inverters. In order to save the total inductance and cost and reduce the volume, different power filters were proposed for the three-phase three-wire grid-connected voltage source inverter. However, in industrial applications, due to the consideration of production cost, the difficulties caused by the deviation of actual parameters have to be addressed. In this article, we propose a new three-phase three-wire power filter with a simple structure, almost the smallest total inductance, and strong resistance to the adverse effects of parameter shifts. The parameters of the proposed filter and the design of the grid-connected system controller are introduced in detail. When studying the influence of parameter offset, a comparison between different types of notch power filters is also given. Simulation and experimental results on a 380 V/50 Hz/6 kW three-phase inverter prototype verify the performance of the proposed power filter.