Bipolar Modulation Research Articles

Analysis of Control Strategy of Arc Plasma Power Supply Inverter Module

The inverter module serves as a critical component in the conversion of electrical energy within arc plasma power sources, exerting a profound influence on the overall performance and stability of the power supply. Consequently, the meticulous design and precise control of the inverter module are of paramount importance in ensuring the effective operation and application of arc plasma power sources. This paper introduces a dual-closed-loop control system, integrating a voltage outer loop with a current inner loop, as the cornerstone of its inverter module design. It also undertook a comprehensive comparative analysis of various voltage-control strategies, encompassing four control methods (PI, PID, PR, QPR) and two modulation techniques (bipolar modulation and unipolar, carrier-based modulation) under diverse operating conditions. Additionally, simulation experiments were conducted on a prototype 10 kW inverter module using the Matlab/Simulink simulation platform, with evaluation criteria including waveform tracking performance, voltage waveform distortion rate, and steady-state error. The results indicate that in low-frequency operating conditions, the voltage-control strategy employing QPR control plus unipolar, carrier-based modulation, and in high-frequency operating conditions, the voltage-control strategy utilizing PI control plus unipolar, carrier-based modulation exhibited superior waveform tracking performance. The waveform distortion rates were measured at below 0.47% and 4.2%, respectively, aligning perfectly with the stringent standards of IEEE 519. This research provides valuable theoretical support and practical guidance for future engineering endeavors in the field of inverters.

Analysis and control of single‐phase transformerless dual‐frequency grid‐connected inverter

SummaryTo simplify the inverter topology and suppress the leakage current more effectively, a novel transformerless dual‐frequency grid‐connected inverter with a common direct current (DC) bus is proposed. The proposed inverter retains the advantages of the traditional dual‐frequency inverter such as high efficiency and absence of resonance. In the novel topology, the power unit adopts the highly efficient reliable inverter concept (HERIC) topology with a unipolar modulation strategy, and the auxiliary unit adopts the H‐bridge topology with a bipolar modulation strategy. It is verified that the circulating current between the two units can be eliminated in the proposed inverter. The sensitivity of the circulating current is discussed by considering the tolerance of the filter inductances. In the leakage current equivalent circuit, the DC bus of the power unit is connected to the grid through a low‐impedance branch in parallel with the parasitic capacitance. Therefore, the leakage current is effectively suppressed. Finally, the experimental results are provided to verify the performance of the inverter.

A Novel High-Frequency Inverter With ZVT in a Wide Range of Duty Cycles and PFs

This paper presents a wide-range zero-voltage-transition (ZVT) high-frequency single-phase inverter. The proposed inverter consists of a full-bridge inverter and two auxiliary switches that are magnetically coupled to the output filter inductor via an additional winding. The auxiliary circuit provides zero-voltage switching (ZVS) for the full-bridge converter switches, while the auxiliary switches are turned on and off with zero current switching (ZCS). A combination of unipolar and bipolar modulation is used as the modulation technique to ensure soft-switching over a wide range of duty cycles and power factors. The proposed auxiliary circuit has a simple structure and does not require floating gate drives for the auxiliary switches. A 1.5 kW-400 kHz prototype has been developed to verify the theoretical analysis, demonstrating a significant increase in efficiency for both unity and non-unity power factors.

Different non-isolated photovoltaic (PV) inverter topologies can suppress leakage currents

In recent years, due to various environmental protection policies and the popularity of new energy sources, photovoltaic power generation has been strongly encouraged and developed at home and abroad. Suppressing leakage current is a key issue for non-isolated PV grid-connected systems. This paper analyzes various circuit topologies proposed to suppress the leakage current based on the bridge structure. This paper will compare and analyze the representative circuit topologies among them, comparing their circuit diagrams, operating principles, pros and cons, and so on. The leakage current can be effectively suppressed by bipolar modulation, but it will produce great electromagnetic noise and full harmonic distortion, reducing system efficiency. The HERIC circuit has the highest conversion efficiency and the best leakage current suppression effect among the three half-bridge structures and three full-bridge structures summarized in this paper. By summarizing and comparing, future research efficiency will improve when similar problems arise.

Multicolor Bipolar Modulation of Titanium–Chromium Oxide Electrochromic Coatings

Electrochromic (EC) materials offer wide-ranging commercial applications, including smart windows, electrochromic mirrors, and programmable static displays. While many conventional electrochromic applications require the encapsulation of the EC materials and other components inside a sealed cell, there are cases where the color appearance of the object’s surface needs to be durable in atmospheric or aquatic environments. Among the current fabrication methods for EC materials, atomic layer deposition (ALD) remains less explored. In this work, we fill these gaps by employing ALD to grow a (Ti,Cr)Ox film as a new subset of EC coatings that operates in direct contact with aqueous solutions. The protective and bipolar coloration properties of the (Ti,Cr)Ox are achieved by the ALD alloying of TiO2 and CrOx nanocrystals. Intrinsic EC performance showed excellent cycle stability of more than 2000 cycles in aqueous electrolytes of high salinity and high corrosion resistance in pH = 0 acid. Furthermore, multicolor modulation has been achieved via a Fabry–Perot optical cavity design. Microstructural and spectroscopic characterizations combined with finite-difference time-domain (FDTD) modeling allow us to correlate the optical appearance with coating electronic and microstructures. This work showed that this ALD-grown ternary EC coating can also act as a surface protection layer and has unique advantages over other EC materials to achieve balanced performance among color tunability, coloration efficiency, and cycle stability.

Research on offshore DC wind power circuit

This paper studies the offshore DC wind power technology, to explore how to reasonably transmit and use the electrical energy generated by the offshore wind generator, to obtain a more optimized circuit model of offshore DC wind power technology. This paper mainly discusses the process of voltage conversion, inverter, rectification and output of appropriate three-phase AC voltage in the process of ac transmission from HVDC offshore wind turbine. According to the “π” equivalent circuit principle, the paper compares HVDC transmission mode with HVDC transmission mode, and compares the harmonic distortion rate of unipolar modulation and bipolar modulation in pulse width modulation through analog circuit, determines the final circuit model and obtains the simulation result diagram.

Monopolar Fault Reconfiguration of Bipolar Half Bridge Converter for Reliable Load Supply in DC Distribution System

This article proposed the concept of monopolar fault reconfiguration for bipolar dc distribution system realized with Bipolar Half Bridge (BiHB) converter. Monopolar fault reconfiguration oriented from bipolar high voltage direct current (HVdc) transmission grid. For dc distribution, the operation aim is to provide uninterrupted power supply to critical load under monopolar fault. It requires interfacing circuit with fault-tolerant capability as well as control design considering both bipolar and monopolar working mode. The proposed BiHB converter achieves mode switching by reconfiguring the converter switching pattern. Considering both monopolar and bipolar working mode, a bipolar modulation method is proposed for coordinate circuit design. Key influence factors relating to the transient voltage spikes have been identified, including the fault detection delay and the modulation method. Besides, to suppress the voltage spikes caused by monopolar fault, feed-forward compensation is adopted for smooth mode transition. The proposed BiHB converter and control strategy have been comparatively evaluated under fault protection and restoration. Uninterrupted power supply of load has been attained, in validation of the proposed monopolar fault reconfiguration concept.

Tuning Ambipolarity of the Conjugated Polymer Channel Layers of Floating-Gate Free Transistors: From Volatile Memories to Artificial Synapses.

Three-terminal synaptic transistor has drawn significant research interests for neuromorphic computation due to its advantage of facile device integrability. Lately, bulk-heterojunction-based synaptic transistors with bipolar modulation areproposed to exempt the use of an additional floating gate. However, the actual correlation between the channel's ambipolarity, memory characteristic, and synaptic behavior for a floating-gate free transistor has not been investigated yet. Herein, by studying five diketopyrrolopyrrole-benzotriazole dual-acceptor random conjugated polymers, a clear correlation among the hole/electron ratio, the memory retention characteristic, and the synaptic behavior for the polymer channel layer in a floating-gate free transistor is described. It reveals that the polymers with balanced ambipolarity possess better charge trapping capabilities and larger memory windows; however, the high ambipolarity results in higher volatility of the memory characteristics, namely poor memory retention capability. In contrast, the polymer with a reduced ambipolarity possesses an enhanced memory retention capability despite showing a reduced memory window. It isfurther manifested that this enhanced charge retention capability enables the device to present artificial synaptic characteristics. Theresults highlight the importance of the channel's ambipolarity of floating-gate free transistors on the resultant volatile memory characteristics and synaptic behaviors.

Bipolar Modulation of the Ionic Circuit for Generic Organic Photoelectrochemical Transistor Logic and Sensor

AbstractPhotonic (bio)electronic circuits and devices have been an enduring goal in modern photonics and electronics. Organic photoelectrochemical transistor (OPECT) interfacing light with biological world creates a substantial opportunity to this end due to the immense light−bio−matter interplay. Through modulating the invisible ionic circuit of organic electrochemical transistor (OECT) with a bipolar electrode (BPE) accommodating different semiconductor combinations, the unique photonic electronics toward logic and sensor applications are realized. Six combinations of BPEs are produced by the representative n‐type CdS/TiO2 and p‐type BiOI/NiO semiconductors, and the corresponding photonic characteristics and operation rationale are systematically investigated and explained. Designation of opto‐logic circuits and feasibility as a sensory platform are subsequently demonstrated. This work not only represents new photonic bioelectronics but also provides a generic mechanism for the design and development of advanced opto‐logics and bio‐analytics.

A quantitative harmonics analysis approach for sinusoidal pulse‐width‐modulation based Z‐source inverters

The shoot-through (ST) states are essential for the operation of sinusoidal pulse-width-modulation (SPWM) based Z-source inverters. However, the insertion of shoot-through state unavoidably leads to output harmonics which is greatly affected by its distribution, especially for bipolar modulation schemes. With quantitative analysis, this paper investigates the mathematical relationship between the output harmonics and shoot-through states for single-phase Z-source inverters. A modified double-Fourier-transformation-based calculation scheme is proposed to estimate the output harmonics with different shoot-through states insertion methods. Simulations and hardware experiments with a 200 W single-phase Z-source converter under two bipolar modulation control methods verified the accuracy of the proposed theory. The quantitative analysis would be helpful for the design of Z-source converter's control strategy and modulation scheme.

Bipolar modulation of brushless DC motor with integrated control of motoring and regenerative braking

Bipolar modulation of brushless DC motor with integrated control of motoring and regenerative braking

Research on Topology and Control Method of Transformer-Free Dual-Frequency Grid-Connected Inverter

In order to suppress leakage current and improve the efficiency of the transformer-free grid-connected inverter, a novel topology and control method is proposed. The proposed inverter consists of a power inverter unit and an auxiliary converter unit, and the two units are connected by a capacitor on the dc side. The power inverter unit transmits power to the grid at a low switching frequency for reducing power losses. The auxiliary converter unit operates at a high switching frequency, and adopts a feedforward control method to eliminate the grid current switching ripples. The voltage of parasitic capacitance between the photovoltaic array and the ground is stabilized by the auxiliary converter unit with the bipolar modulation scheme, so the leakage current can be suppressed more effectively. A 1-kW prototype was built and tested, and the experimental results are finally presented to show the performance of the proposed inverter.

Effect of load sequence interaction on bond-wire lifetime due to power cycling

Experimental investigations on the effects of load sequence on degradations of bond-wire contacts of Insulated Gate Bipolar Transistors power modules are reported in this paper. Both the junction temperature swing (Delta T_{j}) and the heating duration (t_{ON}) are investigated. First, power cycling tests with single conditions (in Delta T_{j} and t_{ON}), are performed in order to serve as test references. Then, combined power cycling tests with two-level stress conditions have been done sequentially. These tests are carried-out in the two sequences: low stress/high stress (LH) and high stress/low stress (HL) for both Delta T_{j} and t_{ON}. The tests conducted show that a sequencing in Delta T_{j} regardless of the direction “high-low” or “low–high” leads to an acceleration of degradations and so, to shorter lifetimes. This is more pronounced when the difference between the stress levels is large. With regard to the heating duration (t_{ON}), the effect seems insignificant. However, it is necessary to confirm the effect of this last parameter by additional tests.

Optimal Variable Switching Frequency Scheme to Reduce Loss of Single-Phase Grid-Connected Inverter With Unipolar and Bipolar PWM

Reducing the power loss of a converter without increasing its volume or cost in hardware has always been a much sought-after but challenging goal. This article proposes a comprehensive variable switching frequency (VSF) scheme to improve the overall system efficiency while still meeting a given total harmonic distortion (THD) requirement without any hardware changes, achieved only by changes to the controller. In this article, it is analyzed that for the H-bridge inverter, the inductor copper loss and the switch conduction loss are independent of the switching frequency (SF), while the device switching loss and the inductor core loss are functions of the SF. This article aims at weighting the combined switching loss and inductor core loss for both the unipolar and bipolar modulation techniques, with the constraint on the output THD, which, for fixed passive components, is a function of inductor ripple current that in turn depends on the SF. An optimal VSF scheme is devised through rigorous mathematical analysis of the output ripple component and the SF-dependent losses. In each switching cycle, the inductor ripple current is predicted with the circuit parameters, such as duty cycle, switching period, inductance, and dc voltage, and by implementing the VSF scheme, the current ripple is optimally varied such as to satisfy the THD requirement while reducing the SF-dependent losses. A generalized method to design VSF schemes for any topology and specifications is also presented, which would help future users in designing the VSF controller. A 1-kW H-bridge inverter using SiC MOSFETs and powdered iron/ferrite core has been built to validate the theoretical analysis. Both constant SF (CSF) scheme (200 kHz) and optimal VSF scheme with simple controller modification have been implemented in the experimental prototype using DSP TMS320f28335. Compared with the CSF scheme, the optimal VSF scheme shows a significant improvement in the system efficiency at rated power from 94.7% to 95.4% with a corresponding saving of 16.5% in the SF-dependent loss in unipolar modulation and from 95.5% to 96.8% with a corresponding saving of 36.5% in the SF-dependent loss in bipolar modulation.

Solid-State Bipolar Pulsed Power Modulator for High-Efficiency Production of Plasma Activated Water

This article presents a bipolar pulse power modulator for high-efficiency production of plasma activated water (PAW). The proposed modulator is designed based on a power cell structure that has structural advantages of a power loop and control loop. Full-bridge based power cells are designed and 12 cells are connected in series. A power loop transformer is designed to deliver isolated power to all cells simultaneously without additional charging switches. A bipolar control loop structure is designed to supply the isolated power and signals required for 48 discharge switches through a pair of high voltage cables. The specifications of the modulator based on the proposed design produces a maximum output voltage and current of 10 kV/100 A, a pulsed width ranging from 0.6 to 10 μs, a maximum repetition rate of 3 kHz, and an average power of 2 kW. The bipolar modulator is tested under resistive and plasma reactor load conditions. In addition, a comparative experiment on the production efficiency of PAW between the proposed modulator and the existing modulator is performed under the same output power condition. Finally, the nitrate generation efficiency is 3.03 g/kWh, which is 1.7 times higher than the existing modulator.

Performance evaluation and security analysis of ground‐to‐satellite FSO system with CV‐QKD protocol

This study evaluates the performance of a secure ground-to-satellite free-space optical (FSO) system using a bipolar pulse amplitude modulation over modulated gamma fading channel. A closed-form expression is derived for the joint probability of a satellite-based continuous-variable quantum key distribution (CV-QKD) protocol that uses dual-threshold detection. Furthermore, to study the system behaviour, closed-form expressions for quantum bit-error-rate (QBER) and quantum bit-discard rate (QBDR) are given. The accuracy of the proposed derivations is validated using Monte-Carlo simulations and numerical analysis. The dual-threshold range is optimised to satisfy design criteria in terms of QBER and QBDR. Finally, a sufficient selection of transmitter and receiver parameters ensures a guarantee of system security. Additionally, the information capacity is maximised by a scaling coefficient of 0.3 × 10 − 6 .

고전압 양극성 펄스 파워 모듈레이터를 위한 게이트 직렬 구동에 대한 연구

고전압 양극성 펄스 파워 모듈레이터를 위한 게이트 직렬 구동에 대한 연구

Investigation of Power Losses by Various Brushless Motor Modulation Methods in Motor Mode

The paper presents a comparative analysis of different modulation techniques for BLDC motor control in terms of several types of losses in the system inverter – BLDC motor in motor mode. The experimental investigated modulation strategies are: unipolar modulation of upper (PWM-TOP or UT) transistors, a bipolar PWM-ON modulation (PWM-ON-BIP), a symmetrical modulation (PWM-PWM), a vector control and non-modulation mode. A simple equivalent circuit for the BLDC motor is used to calculate different losses and the system efficiency. On the basis of the equivalent circuit for the different modulation techniques, simple design procedures are discussed for the determination the eddy current and mechanical viscous loss, the copper loss, the hysteresis and mechanical friction loss, the voltage-drop loss of the inverter transistor and diode. Loss distribution experimental data for the brushless DT4260 motor when operating with different modulations and load torque are presented. On the basis of the obtained values for the efficiency of the studied modulations, references for use in battery powered devices such as electric vehicles, electric scooters and more are made.

Quasi-phase-matched second-harmonic generation in nonlinear crystals with harmonic modulation of nonlinearity

We propose a new type of nonlinear photonic crystal with the lattice representing a harmonic function of the propagation coordinate. This type of spatial modulation of the quadratic nonlinearity is implemented to enhance the second-harmonic generation (SHG) efficiency. The process resembles that realized in periodic nonlinear photonic crystals with rectangular nonlinearity modulation under quasi-phase-matching. Residual periodic oscillations of the second-harmonic intensity were found. Comparison of the unipolar and bipolar modulations showed that they are equivalent with regard to the oscillations. The SHG efficiency in the harmonic lattices is 1.6 times lower compared with the efficiency corresponding to the quasi-phase-matching in periodic nonlinear photonic crystals with rectangular lattices.

Simulation and Experimental Investigation of Modulation Techniques for BLDC Motor Control

The following paper investigates and analyses the electromagnetic processes in an electrical drive system composed of a power source, a power inverter and a brushless dc (BLDC) motor using known pulse-width modulation (PWM) methods. Investigated modulation techniques are: unipolar modulation of the upper transistors (PWM-TOP) and bottom transistors (PWM-BOT), symmetrical PWM-PWM, modulation type PWM-ON and ON-PWM, and bipolar PWM-ON modulation indicated with PWM-ON-BIP. The voltage source inverter is considered as DC-DC buck power converter, when BLDC is operated in motor mode. On the basis of summarized equivalent circuits, the analytical expressions are received for the electromagnetic processes in the system by the different modulation techniques. The efficiency of the system battery-inverter-machine for each discussed modulation is experimentally investigated and compared. These results are also compared with the efficiency of the BLDC driven with vector control. A MATLAB/SIMULINK model is proposed to implement these modulations and to analyze the obtained results. From this model, the harmonic composition of the phase currents for each modulation is investigated.