A boundary voltage control (BVC) strategy suitable for single-phase current-source inverters has been proposed to achieve zero current switching (ZCS) by dynamically adjusting the resonant capacitor voltage, and this control strategy has low requirements for DC side current ripple, which can effectively reduce the DC side inductance value. Therefore, this control method can reduce circuit losses and decrease the size of the inverter. In this article, the working principle and conditions for achieving ZCS are analyzed by combining BVC and bipolar modulation strategy; Based on the principle of area equivalence, a quantitative model of DC side inductor current and output current is established, revealing the mechanism of the impact of second harmonic current ripple on output harmonics. The optimization design criteria for DC side inductance parameters are derived, and the reasons for the decrease in inductance value are analyzed. On this basis, a three loop grid-connected control strategy based on BVC is proposed. Finally, based on theoretical analysis, simulation and experimental research are conducted. The simulation and experimental results have verified the feasibility of the proposed BVC strategy.

The voltage produced by photovoltaic (PV) modules is much lower than grid voltage, and it is difficult for the traditional boost grid-connected inverters to provide sufficient voltage gain for single PV module. Furthermore, leakage current can cause current harmonic distortion and potential safety risks. In order to solve these problems, a common-ground inverter with high voltage gain is proposed in this paper. The proposed inverter is based on the Cuk converter. A coupled-inductor and an intermediate capacitor are connected in series to enhance the boost capability. Bipolar output is achieved by constructing two paths from the intermediate capacitor to the load. The common- ground structure can significantly suppress leakage current. In addition, the turn ratios of the coupled- inductor can be changed to achieve different range of voltage gain. The working principle and modulation strategy of the proposed inverter are analyzed in this paper. Finally, a 300W prototype was built for experiment. The flexibility of the proposed inverter was verified through simulation and experimentation.

该文提出一种单相单级式非隔离型逆变器,主要通过对Sepic电路进行对称设计后再与H桥电路级联,其不但可抑制漏电流,且可实现升降压逆变.该逆变器的电感、电容参数均较小,拓扑中非电解电容,且其调制方式简单易实现,适用于中小功率的光伏逆变系统.该文首先介绍新型逆变器的拓扑结构和工作原理,其中详细分析系统共模回路抑制漏电流的原理;其次,根据中间电感电流流动方式不同,采用不同调制方法,通过公式对其升降压能力进行分析,并对拓扑中电感、电容参数进行设计;最后,完成仿真和实验验证,其结果与理论分析一致.

This paper presents a general control method for suppressing leakage current. Without the addition of passive devices and switching tubes, the amplitude and effective value of leakage current can be reduced by direct control of common mode current, so that it can meet the relevant standards. The method is based on the traditional single-phase voltage bridge inverter to verify the effect of common-mode control on its leakage current suppression. The working principle, control method and modulation strategy are described in detail. On this basis, the simulation and experiment of open-loop and grid-connected control of full-bridge inverter are completed. The results are good and in agreement with the theoretical analysis.

According to the structure and characteristics of a three-phase cascaded H-bridge (CHB) of a high-power multilevel converter, the problem of DC side voltage imbalance in practical applications and the disadvantage where the complexity of the traditional centralized control voltage equalization scheme increases rapidly with an increase of the number of modules both need to be solved. In addition, with the characteristic that distributed control is conducive to the expansion of the system to high-power and multi-module cascade, a new quasi-distributed equalization control strategy is proposed in this paper. The new equalization control strategy combines the traditional closed-loop control with the modulation ratio correction method. On the basis of the traditional closed-loop control, an equalization control module is added to realize a balanced output of the DC side voltage. The control of the equalization control module is simple and flexible, and the complexity of the overall control algorithm is independent of the number of modules. Finally, the correctness and reliability of the control method are verified by experiments.

该文给出一种能抑制共模电流的单级单相Buck-Boost光伏逆变器,该逆变器是通过将H桥逆变器与Buck-Boost斩波电路级联以及对相关的元件进行复用并对电路进行简化得到的,可同时实现升降压以适应宽输入范围的直流侧电压,无电解电容应用且具备有效抑制漏电流的能力,保证系统的可靠性和安全性,非常适用于中小功率光伏系统.此外,利用一种基于调制波重构的非线性调制策略,能显著降低直流侧储能电感大小,有效提高功率密度,实现均衡升降压.详述其工作原理,通过共模分析验证其能对阴阳两极漏电流实现有效抑制以及新型调制策略下可实现均衡升降压控制.在理论分析基础上,完成逆变器并网控制的仿真和实验,结果与理论分析相契合.

漏电流问题是限制非隔离型光伏逆变器广泛使用的关键因素之一.为解决该问题,提出一种可应用于光伏系统的新型三相Buck-Boost逆变器.首先介绍该逆变器的拓扑结构和工作原理,然后推导该拓扑在任意开关时刻共模电压的表达式,从而研究正弦脉宽调制(SPWM)和系统共模电压及漏电流之间的关系,并通过数学模型分析逆变器的升降压能力.最后通过实验平台对上述方案进行验证,实验结果证明了上述方案的有效性和可行性.

理工类专业课程开展课程思政教学设计需要深入研究技术知识与思政素材的结合点,针对不同素材采取不同的教学方法,以达到自然契合的实践目标.本文以"磁性元件设计"课程为例,对理工类专业课的课程思政教学,进行了探讨和设计.

Aiming at the key problems of the existing nonisolated photovoltaic (PV) inverter, such as the common mode (CM) leakage current, the voltage up and down ability, and the service life restricted by the electrolytic capacitor, a novel single-stage common-ground zeta-based inverter with nonelectrolytic capacitor is proposed in this article. The proposed inverter is based on zeta dc converter and has the inherent voltage conversion characteristics of zeta converter, which makes it more suitable for PV system with wide input voltage fluctuation range. In addition, common-ground structure is adopted in this inverter, which can shorten the parasitic capacitor of the PV array to the ground. Therefore, it can effectively suppress the CM leakage current, reduce the shutdown frequency of the PV system, and improve the utilization rate of solar energy. Moreover, the proposed inverter does not contain electrolytic capacitors, which avoids the problem of high maintenance cost due to the short service life and high equivalent series resistance of electrolytic capacitors. First, the topology of the proposed inverter is given, and the modulation and operating principle are analyzed. Second, the passive components are analyzed. Finally, a 1 kW prototype is built for experimental verification. The experimental results verify the correctness of the theoretical analysis and simulation.

该文提出一种新型飞跨电容型多电平逆变器,该逆变器由Zeta变换器进行演变推导而得,具有可升降压、电容可自均压、钳位器件少、拓扑延展性好等优点,克服了传统多电平逆变器在应用方面的局限性.该文首先介绍该逆变器的工作原理,并采用单极性载波相移调制策略,在不提高载波频率的基础上提高其等效开关频率,降低输出电压的总谐波畸变率.此外,对Zeta五电平逆变器的开关器件电压应力、电容自均压的实现、升降压能力和拓扑延展性能方面进行分析.所提逆变器采用PR调节器对其进行闭环控制,通过仿真对其可行性进行验证,且在理论分析和仿真证明的基础上,对Zeta五电平逆变器搭建一台实验样机,实验结果验证该理论分析及仿真结果的正确性,以及该逆变器具有良好的动静态性能.

The isolated dual active bridge DC/DC converter is widely used in power electronic conversion systems due to its security, scalability, and easily realized soft switching. Meanwhile, interleaved technology is also widely used in high current conversion applications due to its low current ripple. Current sharing characteristics are analyzed in detail in this paper based on the topology characteristics of an interleaved low current ripple isolated DC/DC converter. At the same time, under dynamic conditions, the altering trend of the current deviation ratio and the relationship between the current deviation rate and the phase-shifted angle are revealed by small signal modeling. In addition, a single-zero double-pole compensation control method in the current loop is proposed. Finally, an experimental 670 W prototype is built to verify the correctness of the theoretical analysis and the effectiveness of the proposed method.

为了克服传统多电平逆变器不能升降压的缺点,将Z源阻抗网络引入传统单相全桥中点钳位型(NPC)逆变器.通过对Z源型单相全桥NPC逆变器工作原理的详细分析,采用单相多电平空间矢量调制方法,将直通状态导入冗余矢量,对冗余矢量进行合理组合后可实现逆变器的中点电位自平衡和升降压输出.在理论分析的基础上,对Z源型单相全桥NPC逆变器进行仿真和实验,结果证明了拓扑结构的优越性及调制策略的可行性.

传统的电流型逆变器直流侧电感取值较大,应用于中小功率系统时有一定的局限性.针对这个问题,该文对直流电感进行分析,最终得出电感值与电感电流间的关系.在此基础上,提出基于面积等效原理的非线性载波调制策略,当直流侧采用较小的电感时,仍能保证交流侧输出电流质量较高,有效解决了单相电流型逆变器应用于中小功率系统时电感过大的问题.在上述分析的基础上,搭建相应的实验平台,验证了理论与仿真的正确性.

提出一种新型单级非隔离Buck-Boost逆变器.为使输入电压与调制波之间呈线性关系,采用一种新型的非线性PWM策略.该逆变器具有平衡的升降压能力,适用于光伏系统等输入电压宽范围波动的场合;此外该逆变器所用开关器件较少,仅需一个感值较小的电感作为储能元件,无需电解电容,并具有体积小、成本低、效率高、短路及断路保护简单等优点.首先对该逆变器的工作原理进行分析,确定其调制策略,然后建立其数学模型,设计闭环调节器,最后进行仿真和实验验证.通过分析仿真和实验结果,表明该逆变器具有升降压能力,适用于输入电压宽范围变化的场合.

提出一种新型单级非隔离型双Cuk逆变器,此逆变器在输出并联型组合式逆变器构造方式的基础上进行一部分改进,使得该逆变器既保留了Cuk电路的升降压特性,同时电路中的电感电容数量减少了1倍,因此逆变器系统的体积大大减小.该逆变器以非电解电容作为储能及滤波元件,具有可靠性高,使用寿命长等优点.该文根据Cuk电路的非线性特性采用了NPWM(非线性PWM)调制方式,既保证逆变器能够输出良好的正弦电压波形,同时使电路的输入输出关系线性化,降低了系统闭环控制的复杂性.仿真和实验结果证明了该新型逆变器拓扑的正确性和可行性.

该文提出一种单级三相Cuk三电平逆变器.该逆变器由Cuk飞跨电容型三电平DC-DC变换器进行三相拓展而构成.借助于Cuk变换器可升降压的工作特性,该逆变器具备实现升降压逆变的能力,同时兼顾三电平逆变器在中高功率应用场合中的优势.此外,本文采用载波相移调制方式,实现了飞跨电容的电压自平衡.首先介绍该逆变器的拓扑结构与调制方式,然后分析该逆变器在载波相移调制方式下的工作模式与工作特性,并在此基础上推导电路稳态数学关系与输入输出电压增益.最终确定电压闭环的控制策略,并通过仿真与实验结果验证该逆变器可实现单级升降压,且输出电压增益范围宽,适合应用于可再生能源发电领域.

提出了一种并联补偿控制策略,应用于功率解耦型无电解电容功率因数校正(PFC)电路,实现了去除电解电容、提高使用寿命和可靠性的目的。首先以升压型双向Buck/Boost变换器作为功率解耦电路,提出了基于固定占空比的并联补偿控制策略,并对其补偿特性进行了分析。而后在定占空比控制策略基础上提出了一种并联补偿控制策略,该控制策略相比较于传统的控制策略,结构简单、实现容易,而且响应速度快,系统调整时间短,负载电压纹波对负载功率变化不敏感,可实现无传感器的低成本功率解耦。为了进一步减小功率器件耐压,将降压型双向Buck/Boost变换器引入功率解耦方案,应用该文所提出的控制策略进行控制,同样实现了PFC电路去除电解电容的目的。最后对该文所提出的并联补偿控制策略进行仿真和实验研究,结果验证了该控制策略的有效性。

传统的电压型逆变器只能实现降压逆变,且使用电解电容,体积大、可靠性低,应用于新能源发电系统等领域时具有很大的局限性.提出一种新型无电解电容的单级非隔离逆变器拓扑,该逆变器由2个改进型Zeta电路组合而成,所含开关器件及无源器件数量较少,以容值较小的非电解电容作为中间储能元件,具有体积小、可靠性高、使用寿命长的优点.分析新型逆变器的工作原理,推导得出中间储能电容电压公式及逆变器增益;建立该逆变器数学模型,设计闭环调节器,并进行仿真验证;在理论分析和仿真实验的基础上,对新型无电解电容的单级Zeta逆变器搭建实验样机,实验结果证明,该逆变器具有良好的动静态性能.

为了适应宽范围输出电压的应用场合,文中提出一种新型三相Zeta无电解电容整流器。该整流器是将三相电流型脉宽调制（pulse width modulation,PWM）整流器与Zeta电路集成,并将开关管复用得来的,因此继承了电流型PWM整流器和Zeta电路的优点。该整流器在可实现单级升降压的同时,还无须短路保护,无需电解电容和大储能电感,因此具有较高的功率密度和可靠性及较长的使用寿命。介绍该整流器的拓扑结构,分析其基本工作原理,推导其稳态数学模型并得到稳态电压增益。最后,进行仿真和试验。仿真和实验结果验证了理论分析的正确性。

针对中小功率光伏发电系统中电压源型逆变器不能升降压运行、直流侧需要大容量电解电容的问题,提出一种新型无电解电容单级Buck-Boost逆变器.该逆变器具有升降压能力,不仅电路本身不含电解电容,而且其抵抗输入侧低频脉动的能力强,有利于减小输入侧滤波电容值,从而实现整个系统无电解电容化.该逆变器具有成本低、使用寿命长、可靠性高、短路及断路保护简单等优点,符合中小功率光伏发电系统的要求.该文首先介绍该逆变器的工作原理,然后建立其数学模型,并设计闭环调节器.在理论分析的基础上,进行仿真和实验验证,仿真和实验结果证明了理论分析的正确性.