Research on Parallel Interleaved Inverters with Discontinuous Space-Vector Modulation

Parallel converter can significantly increase the capacity of the converter and improve the power quality of AC side, but the circulation which can lead to high switching loss and even damage the devices will easily exist in the direct parallel converters. In this paper, the average model of parallel interleaved inverters system to analyze the circulation current is shown, and the cross current is relevant to DC-bus voltage and the overlap time of zero vectors in the switching period. Based on this observation, a discontinuous space vector modulation without using zero vectors (000) is eliminate and suppress the zero-sequence current to entire system. Finally, the effectiveness of modulation strategy is verified by the simulations in this paper.

Achievable secrecy rate of bit-interleaved coded modulation schemes

We study the impact of various modulation mapping strategies and signal constellation shapes on the se- crecy rates achievable with bit-interleaved coded modulation （BICM） schemes. Transmission over an ergodic Rayleigh fading channel is assumed throughout this work. Various constellations and mapping techniques are considered in this work to maximize the capacity difference between the main channel and the eavesdropper channel, rather than to opti- mize the capacity of both channels. We show that in terms of achievable secrecy rate, Gray and Quasi-Gray mappings only perform Well at low SNR but outperformed by other mapping techniques when SNR increases. The proper design of signal mapping can significantly enhance the achievable secrecy rate in BICM schemes. It is indicated that the key parameter to the secrecy rate of a BICM system is the distance spectrum of Euclidean distances for mappings.

QSM-IDM -A novel quadrature spatial modulation based on interleaving division multiplexing for multiple antenna system

Quadrature Spatial Modulation (QSM) is a high spectral efficiency Multiple-Input Multiple Output (MIMO) technique used to improve the spectral efficiency of wireless communication systems. The main concept of QSM is to extend the spatial constellation of the conventional Spatial Modulation (SM) in both the in-phase and quadrature components of the data symbol. In this paper, because QSM-based on Interleaxdng Division Multiplexing (IDM) has not been introduced in the literature as a multiple antenna system, we introduced a novel scheme, called QSM system based on Interleaving Division Multiplexing (QSM-IDM). The antenna sets are also applied to a spreader, before being used to assign an antenna number for information transmission. Analysis and simulations for a flat fading channel show that the proposed QSM-IDM method significantly outperforms the original QSM system with the same data rate, while maintaining a relatively acceptable complexity. The obtained simulation results show that the conducted analysis yields significant improvements for the accuracy of the proposed scheme, with satisfactory complexity.

Iterative Demodulation and Decoding Scheme with 16 QAM

Iterative demodulation and decoding scheme is analyzed and modulation labeling is considered to be one of the crucial factors to this scheme. By analyzing the existent mapping design criterion, four aspects are found as the key techniques for choosing a label mapping. Based on this discovery, a novel mapping design criteflon is proposed and two label mappings are searched according to it. Simulation results show that the performance of BICM-ID using the novel mappings is better than the former ones. The extrinsic information transfer （EXIT） chart is introduced and it is used to evaluate the proposed mapping design criteria.

Study on the Optimized Demodulation and Decoding of the BICM-ID system coded with LDPC

The demodulation and decoding solution commonly used in the bit interleaving code modulation and the LDPC coded demodulation and decoding system of the iterative decoding （BICM-ID） is to report the soft information output from the decoder of the receiver to the demodulator as priori information for completing the decoding. However, this will give rise to the reduction of the minimum Euclidean distances between codes, so that the performances of the system decline under non-fading Gaussian channel. According to this problem, an optimized iterative demodulation decoding solution is proposed and also is analyzed using simulation. The result shows that this solution can improve the demodulation and decoding performances of LDPC coded modulation and demodulation system.

Path Weight Complementary Convolutional Code for Type-Ⅱ Bit-Interleaved Coded Modulation Hybrid ARQ System

Bit-interleaved coded modulation (BICM) is suitable to bandwidth-efficient communication systems. Hybrid automatic repeat request (HARQ) can provide more reliability to high-speed wireless data transmission. A new path weight complementary convolutional (PWCC) code used in the type-Ⅱ BICM-HARQ system is proposed. The PWCC code is composed of the original code and the complimentary code. The path in trellis with large hamming weight of the complimentary code is designed to compensate for the path in trellis with small hamming weight of the original code. Hence, both of the original code and the complimentary code can achieve the performance of the good code criterion of corresponding code rate. The throughput efficiency of the BICM-HARQ system wit PWCC code is higher than repeat code system, a little higher than puncture code system in low signal-to-noise ratio (SNR) values and much higher than puncture code system, the same as repeat code system in high SNR values. These results are confirmed by the simulation.

复方斑蝥胶囊联合旋转容积调强技术对头颈部放疗生存期及血清XRCC1、XRCC3mRNA水平的影响

目的探究复方斑蝥胶囊联合旋转容积调强技术对头颈部放疗患者生存期及血清X线修复交错互补基因1(X-ray Repair Cross Complementing 1,XRCC1)、X线修复交错互补基因3(X-ray Repair Cross Complementing 3,XRCC3)信使核糖核酸(Messenger RNA,mRNA)水平的影响。方法选取2019年6月—2021年7月医院收治的头颈部肿瘤患者97例作为研究对象,根据治疗方法不同进行分组,对照组(48例)采用旋转容积调强技术结合放疗治疗,联合组(49例)在对照组基础上加用复方斑蝥胶囊治疗。观察比较临床疗效、中医证候积分、血清XRCC1及XRCC3mRNA水平、生存期、不良反应。结果联合组客观缓解率高于对照组(P<0.05),但疾病控制率与对照组比较差异无统计学意义(P>0.05)。联合组自汗、恶心呕吐、神疲乏力、食欲差、失眠、头晕眼花等得分低于对照组(P<0.05)。联合组血清XRCC1、XRCC3水平及外周血XRCC1、XRCC3 mRNA表达均低于对照组(P<0.05)。联合组无进展生存期和总生存期均高于对照组(P<0.05)。联合组不良反应发生率(34.69%,17/49)低于对照组不良反应发生率(72.92%,35/48)(P<0.05)。结论复方斑蝥胶囊联合旋转容积调强技术能改善头颈部放疗患者肿瘤客观缓解率,缓解临床症状,降低血清XRCC1、XRCC3mRNA水平,减少不良反应。

超高温随钻测量系统中的电源技术

超高温随钻测量仪器要求井下供电电源具备可靠性高、抗高温、体积小等特点,目前国内尚无成熟产品。介绍了一种井下稳压电源模块的设计方案,该电源基于非隔离型直流变换器交错并联BUCK拓扑,以CISSOID公司的CHT-MAGMA高温脉宽调制器作为主控芯片,采用推挽驱动器对脉宽调制(Pulse-Width Modulation,PWM)逻辑电平进行功率放大,再经脉冲变压器实现了功率管隔离驱动,确保两路交错驱动脉冲能够驱动MOS(Metal-Oxide Semiconductor)管可靠导通与截止,实现高效电源变换。结果表明,该电源模块的转换效率在全温度范围内达86%以上,能够较好地满足随钻仪器在井下超高温环境下的供电要求。

基于四路串联谐振变换单元的涡流制动励磁电源在高速列车上的应用研究

涡流制动相比目前动车组上普遍采用的轮轨黏着制动在高速区段具有一定优势,成为动车组新技术的研究方向之一。涡流制动励磁电源是涡流制动系统的重要组成部分,对涡流制动控制和系统性能具有重要作用。文中对一种适用于高速列车的基于四路串联谐振变换单元的励磁电源进行了研究,具有较高的可靠性和可控性,并且采用软开关技术,在功率密度和系统效率方面具有一定优势。

Optimizing an interleaved p-n junction to reduce energy dissipation in silicon slow-light modulators

Reducing power dissipation in electro-optic modulators is a key step for widespread application of silicon photonics to optical communication.In this work,we design Mach–Zehnder modulators in the silicon-on-insulator platform,which make use of slow light in a waveguide grating and of a reverse-biased p-n junction with interleaved contacts along the waveguide axis.After optimizing the junction parameters,we discuss the full simulation of the modulator in order to find a proper trade-off among various figures of merit,such as modulation efficiency,insertion loss,cutoff frequency,optical modulation amplitude,and dissipated energy per bit.Comparison with conventional structures(with lateral p-n junction and/or in rib waveguides without slow light)highlights the importance of combining slow light with the interleaved p-n junction,thanks to the increased overlap between the travelling optical wave and the depletion regions.As a surprising result,the modulator performance is improved over an optical bandwidth that is much wider than the slow-light bandwidth.

制氢整流电源背靠背对拖实验方案的研究

针对传统的能量消耗型制氢电源测试平台存在效率低下和成本高昂的问题,提出一种新型的制氢整流电源背靠背对拖实验方案。该方案通过两组制氢电源背靠背的方式进行带载运行,制定详细的电源侧和负载侧控制策略,旨在提升动态响应性能,并解决负载侧电源功率等级、工作电压和电流范围不匹配的问题。通过对单机和四单元并联整机的对拖实验验证,证实所提出实验方案的有效性和可行性,为制氢整流电源的优化设计和性能评估提供新的思路与技术支持。该研究对于提高制氢系统的整体性能和降低运行成本具有重要意义。

非隔离三电平变换器中分压电容均压的一种方法

在非隔离三电平变换器中,分压电容必须是均压的,以保证开关管电压应力相等。在实际应用中,由于控制电路和/或驱动电路有差异,开关管的导通时间不完全相等,使得分压电容不均压,这样开关管电压应力不相等。为了解决这个问题,该文提出一种均压方法,它通过调整开关管的导通时间,确保分压电容均压,论文最后给出实验结果,以验证本方法的有效性。

输入输出共地的三电平变换器

三电平直流变换器不仅可以降低开关管的电压应力,同时还可以大大减小储能电感和电容。但是6种不隔离的三电平变换器的输入输出不共地,其应用范围受到限制。该文引入隔直电容的概念,对这6种不隔离的三电平变换器进行改进,使其输入与输出共地,同时保留其所有优点:①开关管电压应力只有其原型电路的一半;②储能电感和电容可以大大减小。该文以Buck三电平变换器为例进行分析和实验验证。

一种Boost型宽电压范围输入LLC谐振变换器

传统的桥式LLC谐振变换器不适合宽电压范围输入,且其输入电流断续。为此提出了一种新型的Boost型LLC谐振变换器。通过集成两个交错并联的Boost电感,不仅可以拓宽LLC变换器的增益范围,而且可以显著减小输入电流的纹波,因此该变换器适合用在光伏、燃料电池等可再生能源发电系统中。与传统的脉冲频率调制控制相比,该变换器采用定频脉冲宽度调制控制,励磁电感和Boost电感对变换器的增益特性影响很小,可以简化谐振参数的设计,同时定频控制也有利于磁性元器件和滤波电路的设计。首先介绍了该变换器的工作原理;然后通过时域分析,对该变换器的增益特性进行了深入研究;之后对变换器的ZVS软开关条件进行了详细的分析;最后建立了一台120~240 V输入、24 V/25 A输出的实验样机,实验结果验证了变换器的实用性及理论分析的正确性。

基于混合控制式交错并联LLC谐振变换器的充电模块研制

为了解决当前电动汽车充电模块效率低、功率小的缺点,提出了一种基于混合控制式交错并联LLC谐振技术的非车载式电动汽车充电模块整体设计方案。所述方案输入侧为VIENNA电路,输出侧为交错并联LLC谐振DC/DC变换器。采用交错并联技术减小输出电流纹波,提高充电模块输出功率的同时,采用移相变频混合控制策略,使得谐振变换器工作在较窄的频率范围之内,因此降低了磁性元器件设计难度,提高了充电模块的转换效率以及功率密度。给出了充电模块整体电路拓扑设计、各模块工作原理以及控制策略,研制了20kW原理样机,与纯变频式交错并联LLC谐振变换器充电模块的对比分析验证了所述方法的可行性。

双输入Buck变换器的交错双沿调制方法

在多种新能源联合供电系统中,采用多输入直流变换器代替多个单输入直流变换器,能够简化电路结构,降低系统成本。首先分析了双输入Buck变换器的输入输出关系,它只决定于两只开关管的占空比,而与驱动信号的相位无关。然后分析了两只开关管的驱动信号之间的相位差与电感电流纹波的关系,采用交错双沿调制方法,使得电感电流纹波最小,由此可以提高变换器的动态响应速度和功率密度。搭建了一个400W的原理样机,实验结果验证了交错双沿调制方法的有效性。

基于移相补偿的全桥LLC谐振变换器交错并联技术

LLC谐振变换器具有高频化、高效率和高功率密度的优点,近年来已被广泛应用。但由于电路本身的特点,输出电流纹波较大,需要多个输出滤波电容并联,这给系统的体积和应用场所带来了一定的限制。为解决这个问题,可采用交错并联技术,但是谐振元件参数存在的偏差,使得LLC谐振变换器并联时输出电流无法均分。为此提出一种适用于全桥LLC谐振变换器交错并联的均流控制方案,输出电压由脉冲频率调制(PFM)控制,因谐振元件参数偏差引起的负载不均流,由移相调制(PSM)补偿,并根据移相角的大小,动态调节两路LLC谐振变换器之间的交错角,进一步减小输出电流的纹波。在理论分析的基础上,设计并制作一台实验样机,实验结果验证了提出方法的可行性和有效性。

Buck三电平变换器

提出一种Buck三电平变换器 ,该变换器中开关管的电压应力为输入电压的一半 ,采用交错控制方式 ,可以大大减小输出滤波器的大小 ,详细分析Buck三电平变换器的工作原理 ,分析该变换器的输入输出特性 ,讨论主要参数的设计 ,提出一种使输入分压电容电压均衡的方法 ,并进行实验验证。

一种新颖的升压型电压调整器—两相交错并联耦合电感BOOST变换器

单体蓄电池的使用寿命高于串联使用的蓄电池组,但是单体蓄电池普遍存在电压偏低的问题。针对这一问题选用一种新型的升压电路结构,即两相交错并联耦合电感BOOST变换器,通过改变耦合电感匝比来获得不同的输出电压。在传统两相交错并联BOOST变换器中,当输入输出电压增益较高时,电路的占空比调节范围较小。通过采用耦合电感的方法可以扩展电路的占空比,但由于漏感能量的存在会造成开关管上较大的电压尖峰。该文提出一种在两相交错并联耦合电感结构的变换器中利用相邻相开关管作为钳位管的方法,该方法只需增加一个电容元件即可实现电路的有源钳位功能。理论分析和实验结果均表明该变换器对抑制开关管电压尖峰有很好的效果。

基于交错断续空间矢量调制的并联PWM变流器控制策略

并联PWM变流器可以显著增大变流器的容量并提高交流侧的电能质量,但是变流器的直接并联容易在其内部产生环流,从而导致变流器损耗增加甚至开关器件损坏。本文以三相PWM整流器并联系统为例给出了环流的数学模型,该环流是一个存在于零轴的带直流偏移量的环流。针对环流问题,本文通过建立并联系统的小信号模型分析确定了零序电流环的设计,并采用了交错断续空间矢量调制方法来消除和抑制其对整个系统的影响。通过该方法,环流可以用dq轴分量表示,并通过功率因数校正(PFC)电路的电流环加以抑制。最后的仿真和实验验证了本文控制策略的有效性。