Inverter Supply Research Articles

HIL Investigation of a Single-Phase Inverter for a Tokamak Non-Axisymmetric In-Vessel Coil Power Supply

HIL Investigation of a Single-Phase Inverter for a Tokamak Non-Axisymmetric In-Vessel Coil Power Supply

To the question of construction of welding inverter sources with a high power factor

Purpose. Design a power-factor-corrected, energy- and cost-efficient switchmode power supply for welding. Methodology. It is proposed to use the principle of direct conversion and to develop the "hybrid" power circuit consisting of a main power path using direct conversion and an auxiliary power path having a converter with an intermediate DC link with relatively low stored energy. Since a load to the welding power supply is the welding arc, its instantaneous power fluctuations during the mains voltage period essentially do not influence the welding process due to the thermal constant of the weld pool molten metal. Effective use of this features of the welding arc allows to optimize the power processing, reduce the amount of energy stored in the reactive elements of the circuit and improve the economical, mass and dimensional parameters of the supplies. Findings. A new power factor corrected switchmode power supply topology is proposed utilizing beforementioned principles of power processing. The algorithm for calculating the switching frequency of supply power switches is given. To confirm the adequacy of the developed provisions, an experimental sample of the power supply was created. Oscillograms of mains voltage and source current consumption and oscillograms in output current limitation mode are obtained. The results of experiments showed that the supply has a power factor > 0.94 in a wide range of powers. Originality. A distinctive feature of the supply is the absence of additional inductive components in the power path, a lower capacitance of the DC-link bulk capacitor and a simplified scheme for limiting its inrush current during initial charging. The supply has an increased open circuit voltage, independent of the mains voltage, which allows for easy arc ignition during manual arc welding. Practical value. Due to the increased power factor, the current drawn from the mains is 30 % to 45 % lower than that of widespread inverter supplies without a power factor corrector. These features allow to simultaneously use more power supply units with the same mains current load, and/or to provide stable welding in conditions of a "weak" mains.

A multi‐objective low‐voltage ride‐through control strategy for three‐phase grid‐interfaced solar power plant during symmetrical and asymmetrical faults†

SummaryThis paper presents a low‐voltage ride‐through capability (LVRT) solution for the photovoltaic (PV) grid‐connected inverters compliant with the Indian grid code. The LVRT strategy ensures the uninterrupted connection of solar energy to the grid, safeguarding against system shutdown in the event of various grid faults. During this time, the inverter supplies reactive power to the utility grid, effectively utilizing converter capacity and aiding the restoration of the voltage profile at the point of common coupling (PCC). The system used in this study involves a two‐stage grid‐interfaced solar PV setup with a boost converter that tracks the maximum power point (MPP) and an inverter that maintains the DC‐link voltage. A modified dynamic braking chopper control (MDBCC) has also been implemented to minimize the DC‐link voltage oscillations during asymmetrical faults while simultaneously injecting the sinusoidal current into the grid. To improve grid synchronization in the presence of unbalanced abnormalities, a modified dual second‐order generalized integrator phase‐locked loop (DSOGI‐PLL) has been employed to track the grid voltage angle precisely. Furthermore, a new control system has been developed in conjunction with the LVRT approach. The suggested system is simulated in MATLAB/Simulink to validate the efficacy of the LVRT control method during symmetrical and asymmetrical faults using a 100‐kW two‐stage grid‐interfaced solar PV facility. Finally, for experimental validation, a real‐time test bench (RTS) OPAL‐RT 4510 is used to implement the setup with its control, and the practical results are compared with the simulation outcomes.

Solar Induction Cooker

There is no available power grid in the rural areas in many countries in South America, Asia and Africa. st places, Fossil fuel or wood is used for cooking. Besides environmental issues, fossil fuel and wood from trees are being depleted at a fast rate. Solar power is available everywhere during day time in all countries. This solar induction cooker uses a solar panel, which gives a variable dc, to charge a battery. The dc from the battery is converted to a high frequency ac voltage by an inverter circuit. This inverter circuit supplies alternating current to a coil on a magnetic core where alternating flux is produced. This alternating flux produces in the magnetic core Eddy current and Hysteresis ‘losses’ inside the magnetic core. In this application, these losses will produce useful heat. A cooking pot placed on the magnetic core will be used for cooking.

Overview on Permanent Magnet Motor Trends and Developments

The extreme environmental issues and the resulting need to save energy have turned attention to the electrification of energy applications. One of the key components involved in energy efficiency improvements is the appropriate conception and manufacturing of electric machines. This paper overviews the electromagnetic analysis governing the behavior of permanent magnets that enable substantial efficiency gains in recent electric machine developments. Particular emphasis is given to modeling the properties and losses developed in permanent magnets in emerging high speed applications. In addition, the investigation of properties and harmonic losses related to ferromagnetic materials constituting the machine magnetic circuits are equally analyzed and discussed. The experimental validation of the implemented methodologies and developed models with respect to the obtained precision is reported. The introduction of mixed numerical techniques based on the finite element method intended to appropriately represent the different physical phenomena encountered is outlined and discussed. Finally, fast and accurate simulation techniques including aggregated lumped parameter models considering harmonic losses associated with inverter supplies are discussed.

Development of a stand-alone photovoltaic (PV) energy system with multi-storage units for sustainable power supply

The sizing of the energy components is essentially designed to prevent outages and ensuring the reliability of the power supply. This paper focuses on the development of a stand-alone photovoltaic/battery/fuel cell power system considering the demand of load, generating power, and effective multi-storage strategy using a probabilistic sizing algorithm. A computer program was developed and used in the design of component sizing configuration of a stand-alone power system that comprises of a photovoltaic generator (PV), battery, water electrolyzer, a storage gas tank, a fuel cell, and an inverter for a reliable power supply. This program manages the energy flow through the various components of a stand-alone PV/battery/fuel cell power system and provide an optimal technical configuration. The optimum system configuration of a residential building with daily power demands of 69 kWh/day energy consumption is composed of PV arrays resulting in total rated power of 15 kW, 16 units of 6 V, 225 Ah battery bank, 5.5 kW fuel cell, 5.5 kW Water Electrolysis, 16.5 kg hydrogen tank, and a 5.5 kW inverter. Based on the simulation results conducted, it was shown that the sizing and development of a stand-alone PV/battery/FC energy system have been achieved with system reliability (loss of power supply equal to zero). This program could be used as a power monitoring and control system for a stand-alone PV/battery/fuel cell power system.

Current-Limiting Strategy for Asymmetric Short-Circuit of Three-Phase Inverter for Continuous Power Supply of Nonfaulty Loads

Current-Limiting Strategy for Asymmetric Short-Circuit of Three-Phase Inverter for Continuous Power Supply of Nonfaulty Loads

Non-Intrusive Efficiency Estimation of Inverter-Fed Induction Motors

The use of inverter supplies over sinusoidal supplies for induction motors is growing considerably. Inverter supplies enable effective and robust control of induction motors in many automated systems. However, this benefit features at the expense of additional harmonic motor losses due to pulse-width modulated (PWM) voltages and currents produced by inverter supplies. The quantification of these additional harmonic losses and the estimation of efficiency in a non-intrusive manner can be quite challenging. This paper proposes a non-intrusive efficiency estimation technique for inverter–fed induction motors that is based on harmonic regression analysis, harmonic equivalent circuit parameter estimation and harmonic loss analysis using limited measured data. The efficiency results from the proposed technique are comparable to those obtained using the IEC 60034-2-3 Standard up to 1% accuracy when tested on three different inverter-fed motors at different loads.

Simulation of the Circulating Bearing Currents for Different Stator Designs of Electric Traction Machines

Pulse–width modulated inverters are commonly used to control electrical drives, generating a common mode voltage and current with high–frequency components that excite the parasitic capacitances within electric machines, such as permanent magnet synchronous machines or induction machines. This results in different types of bearing currents that can shorten the service life of electric machines. One significant type of inverter–induced bearing currents are high–frequency circulating bearing currents. In this context, this work employs finite element analysis and time-domain simulations to determine the common mode current and circulating bearing current for various permanent magnet synchronous machine designs based on the traction machines of commercial electric vehicles with a focus on the stator. The results suggest that the ratio between the circulating bearing current and common mode current is much smaller in permanent magnet synchronous machines for traction applications than previously established in conventional induction machines, with values below 10% for all analyzed designs. A further increase in the robustness of such electric machines to the detrimental effects caused by the inverter supply could be achieved by reducing the parasitic winding–to–stator capacitance or by increasing the stator endwinding leakage inductance.

Tensile properties and microstructure of surface tension transfer (STT) arc welded AA 6061-T6 aluminum alloy joints

The wide usage of 6xxx series aluminium alloys in automobile sector is mainly because of the exceptionally good weldability characteristics and better corrosion resistance. Surface tension transfer (STT) arc welding is one of the variants of gas metal arc welding (GMAW) that has potential features such as low heat input and arc stability with an innovative wire feed system. STT is a modified short-circuiting metal transfer technique that regulates the metal transfer rate using a high-frequency inverter power supply This process is widely used in automobile industry due to its higher welding speed and capability to weld thin sheets without defects like spatter, distortion and burn through. This article reports the welding of thin aluminium 6061 sheets by STT arc welding process and presents the tensile properties of the welded joints. The features of the microstructure are characterized by optical microscopy. The fracture surfaces are being examined by scanning electron microscopy. During the tensile test, the welded joint failed at 12 mm from weld zone. It is evident that failure is generated by softening in (heat affected zone) HAZ region due to the production of β′or β precipitates which are softer and incoherent in nature. The tensile properties of STT welded aluminium alloy joints yielded a better joint efficiency of 71.08 % due to the presence of higher hardness in the welded region. The hardness results signify that the HAZ noted low hardness which is called as softened zone, where the transformation of precipitates or coarsening of grains takes place.

VOT and VFT-Based hybrid digital hysteresis control for UPS inverter

When the digital hysteresis current control (DHCC) strategy is applied to control the uninterruptible power supply (UPS) inverter, here are some issues such as large hysteresis tracking error caused by sampling interval and severe switching frequency swing caused by rapid change rate of inductor current. To address these issues, this paper presents a digital control strategy based on the hybrid digital hysteresis current control (HDHCC) of variable opening time (VOT) and variable falling time (VFT) for UPS inverter. Firstly, the HDHCC structure is established and the working principle of the inverter system is described in detail. Then, the tracking error and switching frequency error of the DHCC are derived. Based on the performance requirement of quasi-constant frequency control of UPS inverter, VOT and VFT control criteria without the dependency of circuit parameters are given. The experimental results demonstrate that the hybrid digital hysteresis control strategy based on VOT and VFT has the advantages of high current tracking accuracy, accurate switching frequency control, small output voltage waveform distortion, and simple implementation.

Operational Diagnostics System for Asymmetric Emergency Modes in Traction Drives with Direct Torque Control

This article presents an analysis of the causes behind the development of asymmetric modes in a traction drive system that features direct torque control (DTC) of a rolling stock with asynchronous traction motors. The development of asymmetric modes in the traction drive system was found to be caused by the asymmetry of the supply voltage system, the asymmetry of the traction motor windings, and transient processes triggered by a change in the inverter supply voltage and variation in the traction motor load. At the same time, the asymmetric modes caused by the asymmetry of the feed voltage system and the windings of the traction motor are the emergency modes. The influence of the asymmetry of the feed voltage system and asymmetry of the windings of traction motor on the starting characteristics of the phase currents and flux linkages of the stator in the steady-state mode was investigated. In these cases, the ratio of the amplitudes of phase currents and flux linkages of the stator of different phases was found to be constant. The effect of a variation in the feed voltage and load acting on the motor shaft on the starting characteristics of phase currents and flux linkages of the stator was investigated in the case of absence of the emergency modes. In these cases, the ratio of the amplitudes of phase currents and flux linkages of the stator of different phases was found to not be constant. The amplitudes of the phase current and stator flux linkage were proposed as criteria for diagnosis and identification of asymmetric emergency modes. An algorithm and a structural scheme have been proposed for the diagnosis of emergency asymmetric modes in the traction drive system with direct torque control. Modifications to the traction drive system with direct torque control are suggested in order to diagnose the presence of faulty asymmetric modes and identify the damaged traction drive element.

UGF-based signature reliability for solar panel k-out-of-n- multiplex systems

PurposeThe purpose of this paper is to evaluate the reliability and signature reliability of solar panel k-out-of-n-multiplex system with the help of universal generating function.Design/methodology/approachEnergy scarcity and global warming issues have become important concerns for humanity in recent decades. To solve these problems, various nations work for renewable energy sources (RESs), including sun, breeze, geothermal, wave, radioactive and biofuels. Solar energy is absorbed by solar panels, referred to as photovoltaic panels, which then transform it into electricity that can be used to power buildings or residences. Remote places can be supplied with electricity using these panels. Solar energy is often generated using a solar panel that is connected to an inverter for power supply. As a result, a converter reliability evaluation is frequently required. This paper presents a study on the reliability analysis of k-out-of-n systems with heterogeneous components. In this research, the universal generating function methodology is used to identify the reliability function and signature reliability of the solar array components. This method is commonly used to assess the tail signature and Barlow-Proschan index with independent and identically distributed components.FindingsThe Barlow-Proschan index, tail signature, signature, expected lifetime, expected cost and minimal signature of independent identically distributed are all computed.Originality/valueThis is the first study of solar panel k-out-of-n-multiplex systems to examine the signature reliability with the help of universal generating function techniques with various measures.

Design of Uninterruptible Power Supply Inverters for Different Modulation Techniques Using Pareto Front for Cost and Efficiency Optimization

This work presents a design for uninterruptible power supply inverters using Pareto front optimization for improved cost and efficiency. Three PWM modulation techniques applied to the full-bridge inverter are analyzed. As a result, the best MOSFET design solution in terms of the cost and efficiency of the inverter is evaluated based on a database with 47 power MOSFETs. Using the Pareto front, the optimal and sub-optimal solutions are compared, considering the three modulation techniques and the characteristics of MOSFETs manufactured for different voltage levels. Thermal and electrical measurements are used to validate the models.

A Novel Control Strategy for Uninterruptible Power Supply Based on Backstepping and Fuzzy Neural Network

This paper proposes a novel control strategy for controlling the uninterruptible power supply (UPS) inverter, which is based on backstepping control theory combined with a fuzzy neural network (FNN). The advantage of backstepping control is that it can decompose a complex system into multiple subsystems, stabilize the control object according to Lyapunov stability theory, and simplify the controller design. However, it requires prior knowledge of multiple system parameters. FNN can approximate arbitrary nonlinear functions and system errors, which can reduce the parameters required for controller design. Hence, Combining the advantages of both methods, a UPS inverter control method with only a few parameters is designed. Then the sliding mode gain is added to compensate for the fuzzy neural network to reduce the chattering when the system operates and ensure the needed power quality. To verify the effectiveness of the proposed control system, the effectiveness of the proposed method is verified by a simulation experiment platform.

Iron Loss Calculation for FSPM Machine With the PWM Inverter Supply Based on General Airgap Field Modulation Theory

In this article, an iron loss for the flux switching permanent magnet machine with the pulsewidth modulation (PWM) inverter supply is calculated based on the general airgap field modulation theory (GAFMT). First, the amplitudes and rotation speeds of the main space harmonics of the airgap magnetic flux density with the supply of PWM harmonics are calculated based on the GAFMT. When calculating the source magnetizing magnetomotive force based on the GAFMT, the equivalent magnetic circuit is applied to calculate the working point of the permanent magnet. Second, each spatial harmonic in the airgap magnetic field is synthesized by an equivalent current layer in the airgap and then is substituted into the 2-D finite element analysis models to calculate the iron losses. Finally, the iron losses calculated by the proposed method with different speeds, loads, and control strategies are compared with the experimental results.

Switching Wave Characteristics Affecting the Life of Type II Machine Turn Insulation

In this article, the impact of the waveform switching frequency (SWF), overshoot (OS), and rise time on the time-to-failure and the endurance of Type II machine insulation is investigated. Reference life curves at 1 and 4 kHz SWF are derived utilizing a unipolar repetitive square-impulse of 15% OS and 300 ns rise time. The effects of the impulse OS and rise time in the ranges of 0%–30% and 400–600 ns are also evaluated and reflected on the established reference life curves. Based on the endurance test results and the reported time-to-failure data, it is evident that the turn insulation is subjected to additional stress factors when energized by an inverter supply as opposed to the stresses exhibited by sinusoidal waves. This indicates an incomparable aging rate between the two types of waveforms, even at similar peak voltages applied, resulting in inadequate use of sinusoidal supply to qualify inverter-fed machines. Moreover, the OS component of the waveform is found to have a substantial impact on the endurance of turn insulation apart from the jump voltage impact, and therefore, is identified as a significant factor influencing the life of turn insulation independent of other factors. Moreover, the reported results of the time-to-failure analysis advocate a nonlinear relationship between the SWF and the life of turn insulation, whereas the waveform rise time is found to have a negligible impact within the considered range in this study.

Design of output filter device of mine-used high-voltage inverter for long-distance power supply

During the long-distance transmission of the Pulse width modulation ( PWM ) signal of the mine-used inverter, the voltage reflection phenomenon leads to a higher peak voltage at the motor end, which accelerates the insulation aging of the motor and reduces the overall reliability of the system. In this paper, ANSYS is used to simulate the electromagnetic field of cable and cable connector and extract the distributed parameters. On this basis, the simulation model of long-distance power supply system of 3300V mine-used high-voltage inverter is established by MATLAB / Simulink, and the harm caused by peak voltage to motor is analyzed. According to the cable length, the number of cable connectors and the power loss of the device, a design scheme of LRC filter device meeting the power supply distance of 3000m is proposed. Simulation and experimental results verify the effectiveness of the filter device.

An Approach for Saving Energy Control of an IM Supplied by the Battery-Powered System Based on Branch-and-Bound Theory

In order to improve the power quality and decrease the consumed power of an induction motor (IM) which supplied by an alternate battery-powered system, an algorithm that can be used to save its energy consumption has been proposed. Control mechanism is to reduce the wasted energy which caused by IMs start-up current based on bounding its optimal starting voltage. Proposed algorithm includes two parts: 1) use Branch and Bound (BB 2) according to the control rule to adjust on-line voltage of the zinc bromine flow battery which is used to feed the IM. Due to proposed approach, the minimum start-up voltage of the battery-powered system can be predicted and by which one the IMs surge current has been suppressed on line. Moreover, the relationship of the output voltage of battery and inverter supply to the load current has been derived by modelling the battery-powered system. Experiments demonstrate that compared with before optimization, amount of energy consumption of the IM supplied by zinc bromine flow battery decreases by 8.5% and corresponding indicator parameters of the power quality can reach the standard IEC TS62749-2015.

Observer-Based Adaptive Control for Single-Phase UPS Inverter Under Nonlinear Load

This article proposed a current-sensorless control scheme for the single-phase uninterruptible power supply (UPS) inverter under nonlinear load. Different from the existing current-sensorless literature, the information of load current can be obtained by the designed adaptive laws. It is meaningful for the system’s security and reliability. Under the assumption that the load is a periodic ideal-independent current source, the Fourier series in trigonometric form is expanded to model the unknown disturbance of load current. The observer-based feedback control rate and update laws are derived to adjust online the Fourier coefficients of the load current modeling. Furthermore, the stability of the system is rigorously analyzed via the Lyapunov approach. Under the same limitation of not using the current sensor, comparative experiments are designed. Simulation and experimental results have verified the effectiveness of the control approaches.