感应加热电源逆变器锁相环控制电路的研究

感应加热电源中为了提高逆变器工作效率以及扩大负载的适应性,通常采用锁相环电路实现频率跟踪,但普通的锁相环电路存在入锁时间长、启动成功率低和捕捉范围窄的缺点。利用变带宽法改进锁相环频率跟踪电路,实践证明,电源能快速进行频率跟踪,能自动适应负载,工作在谐振状态,启动成功率高。该方法具有较好的推广价值和应用前景。     

高频感应加热电源的数字化研究

为了使功率器件工作在零电压开关(ZVS)状态下,以提高串联谐振式逆变器的输出效率,需要使逆变器的工作频率始终与负载的谐振频率保持同步.介绍了一种基于DSP的数字化高频感应加热电源的设计方案,该电源采用TMS320L F2407A作为控制芯片,通过一种改进的数字锁相环控制策略,采用频率校正和相位校正以实现对电源的输出频率进行实时控制,实验证明此方法设计的逆变电源具有良好的频率跟踪特性,具有一定的应用前景.     

高频感应加热电源PLL—PSM复合控制电路研究

以移相脉宽调制电路和锁相环电路为基础,设计了一种新的电压源供电的串联感应加热负载的PLL—PSM混合控制电路。实验显示其能让逆变器工作在负载固有谐振频率处,同时逆变器能实现输出功率桥内调节。该电路简化了感应加热电源的拓扑结构,对负载具有好的自适应性。     

单闭环控制系统在IGBT中频感应加热电源中的应用

设计一种以CD4046与SG3525A构成的单闭环控制系统,采用PI调节方式对中频感应加热电源进行无相差频率跟踪,并就频率跟踪瞬态性能进行分析,利用闭环调节自动跟踪负载频率。将该系统用于100kW IGBT中频感应加热电源样机中,对电源效率进行数据统计分析,并且与同等级可控硅中频感应加热电源相比较,电效率得到大幅度提高。     

串联谐振高频逆变电源的数字锁相研究

为提高串联谐振式逆变器的输出效率,减小装置功率器件的开关损耗,确保功率器件的零电流开关(ZCS)模式,必须控制逆变器的工作频率始终与负载的谐振频率保持同步.本文针对传统模拟锁相环的缺点,采用基于DSP的数字锁相环(DPLL)对高频逆变电源的工作频率实时控制,使之同步跟踪负载的谐振.通过建立逆变电源锁相环的数学模型,在Z域中对二阶数字锁相环进行稳定性分析和动态设计,给出锁相环的稳定条件.在MATLAB环境下,对DPLL及逆变电源进行了仿真验证.结果表明:数字锁相环的动态分析和设计是合理可行的,用此方法设计的逆变电源具有良好的频率跟踪特性,实现了ZCS软开关.     

电磁感应加热电源的研制

提出了一种新颖的具有负载谐振频率跟踪的感应加热电源的结构;针对加热铁心的温度升高对谐振参数造成的影响,引入了谐振频率跟踪控制,使变换器工作于谐振频率处,减小了开关损耗,并且保证了最大的功率的输出,频率跟踪电路具有简单、可靠、成本低、工程应用价值高的优点。     

IGBT超音频感应加热电源

介绍采用ＩＧＢＴ组成的１００ＫＷ２０ｋＨｚ超音频感应加热电源。该电源采用锁相分频式触发器作整流用闸管触发、并采用负载串联谐振式电压型逆变器，利用锁相技术将逆变器的工作频率锁定于槽路的固有谐振频率，使得本机能始终运行于负载功率因数为１的状态。     

定角控制高频MOSFET串联逆变器频率跟踪

针对采用功率MOSFET的高频串联型逆变电源,在分析其工作状态和传统锁相环对频率跟踪的基础上,提出了一种锁相电路与定角控制相结合的逆变器频率跟踪方法,实验结果表明该方法具有跟踪速度快,跟踪频率准确,保证逆变器始终工作在小感性状态,即逆变器始终工作在功率因数接近1的准谐振状态,从而提高了系统的功率因数,实现了MOSFET的软开关。     

100kW感应加热电源频率跟踪的研究

设计一种由单片机扫描控制的应用于感应加热电源的无相差频率跟踪控制系统,并就频率跟踪瞬态性能进行了重点分析与设计。将该系统用于100kW-2.5kHz IGBT中频串联感应加热电源样机中,使系统跟踪精度更高,电能利用率达到最大。     

半桥型IGBT移相调功感应加热电源

介绍工作频率为３０－６０ｋＨｚ、功率５ｋＷ串联准谐振移相调功感应加热电源的工作原理及实验仿真结果。控制电路采用ＬＥＭ电流传感器和ＣＤ４０４６集成锁相环实现频率跟踪和移相调功，具有电路简单、效率高、体积小和成本低等优点。     

Design and performance analysis of the three-level isolated DC-DC converter with the nanocyrstalline core transformer

In this study, an isolated three-level DC-DC converter is proposed for high power and high conversion ratio applications such as fuel cells. The proposed system consists of a single phase three-level inverter, a medium frequency transformer and a diode rectifier unit. In the proposed system, a DC supply voltage is converted to a medium frequency AC voltage via a three-level inverter instead of the conventional two-level inverter. Since the three-level inverter generates an AC waveform with multiple steps, lower voltage harmonics and lower EMI levels than conventional two-level inverter are achieved. Thus, the three-level inverter provides higher efficiency value. The medium frequency transformer enables high voltage conversion ratio and provides galvanic isolation as well. The output voltage of the medium frequency transformer is converted to the DC voltage and thus the DC-DC conversion is achieved. According to simulation and experimental results, it is seen that the proposed DC-DC converter structure provides higher power density and higher efficiency values than conventional system.     

感应加热电源在注塑机料筒加热上的应用研究

介绍感应加热电源在注塑机料筒加热上的应用,设计一种半桥式串联谐振电路拓扑结构的电磁感应加热电源,通过在一个内直径40mm、外直径100mm的注塑机料筒上实验,得出谐振电容和谐振电感参数的变化与电源输出功率之间的关系。设计1台样机,实验结果表明该电源工作稳定可靠,对进一步研究具有一定的参考价值。     

Analysis and comparative study of pulsating current of fuel cells by inverter load with different power converter topologies

Fuel cells are being increasingly used for stand alone and grid connected systems in wide range of applications due to their high efficiency and low emissions. Because of unregulated nature of fuel cell voltage a power conditioning unit, consisting of DC-DC converter and an inverter, is invariably used as an interface between the fuel cell and the load in a typical fuel cell system for ac applications. Major issues with the use of fuel cells for ac applications are the low frequency pulsating current propagation on to the fuel cell side and dynamic response to various loads during transient conditions. Low frequency pulsating currents are reported to affect reactant utilization, degrade the performance and life of fuel cells. These current ripples can be reduced by filters with passive elements having bulky inductor and capacitor in the dc-link between the fuel cell and the inverter but, it will add to the weight and cost. DC-DC converters of different configurations are being used in the power conditioning unit of fuel cell systems. These converters are operated at high frequencies and the filtering units of these converters have minimal effect on low frequency ripple. But, it is observed that different configurations of power conditioner with same filtering components perform differently for the low frequency current ripple of the inverter load by mitigating the power mismatch between load and source at the DC link. This paper investigates and compares the low frequency current ripple mitigation by cascaded converters with conventional push-pull and also with series connected converters in the power conditioning stage of fuel cell system for ac applications. Parameters such as peak switching currents, the percentage of peak to DC level of low frequency current ripple are analyzed using these conversion topologies in power conditioning unit. The analytical and simulation results related to the study are presented. Key results are verified with experimental work.     

适应电网侧AGC不同控制模式的光伏发电参与电网频率调节

大规模光伏发电并网致使电力系统面临惯量减小与调频能力不足。文章在备用一定有功功率的基础上,提出有功功率-频率下垂控制策略,通过修正逆变器的原有控制结构,实现光伏发电主动参与电网频率一次调节。考虑一次频率调节偏移与越界等问题,提出自适应电网侧AGC不同控制模式(定频率控制模式、定联络线功率控制模式以及联络线功率频率偏差控制模式)的二次频率调节控制策略,进而实现频率的无差调节。最后,基于PSCAD/EMTDC仿真平台验证了控制策略的有效性与可行性。     

含不平衡负载的微电网中三相微源逆变器的VSG控制策略

在离网模式下,微电网中虚拟同步发电机的输出电压易受不平衡负载影响。针对此问题,文章基于一阶全通滤波器(All-Pass Filter,APF)的电压电流正、负序分离方法,利用正序功率和正序电流建立了改进VSG控制模型,改善了VSG输出电压参考。采用比例积分(Proportional Integral,PI)+准比例谐振(Quasi Proportional Resonant,QPR)电压调节器对VSG输出负序电压分量进行控制,论证了PI+QPR调节器抑制负序电压分量的优良性能。最后,仿真结果验证了该控制策略的有效性,该方法有效地改善了三相微源逆变器输出电压的对称性。     

Electric power generation based on variable speed wind turbine under load disturbance

This study was interested in the management of an energy production unit. A variable speed wind turbine (VSWT) was used as a principal source and a supercapacitor (SC) module was used as an energy storage system. Both were connected through a direct current bus. This unit was supplying a three-phase load using an inverter and an inductor and capacitor filter. In order to regulate the direct current bus voltage, the SC storage state was controlled by using a buck-boost converter according to load instructions and wind speed fluctuations. Then, a resonant controller was established to avoid any disturbances and to control the alternating line-to-line voltages of the load which may be unbalanced. This study has shown that the stability of the three-phase voltage source depends on the direct current bus power management and also on the line-to-line voltage control. Simulation results are presented to validate the efficiency of the control strategies used.     

基于SPWM的小型风电逆变系统的建模与仿真研究

以小型风力发电系统为研究对象,重点研究其逆变环节的设计,通过比较分析,主电路选择高频变压器形式,控制电路采用电压瞬时值反馈控制。利用MATLAB/Simulink软件建立了风电逆变系统的电路模型,给出了基于SPWM(Sinusoidal PWM)电压反馈控制的系统设计与仿真。在突加干扰的情况下仿真模型能很快稳定,具有较强的抗干扰能力,仿真结果验证了系统设计的可行性。在此基础上,完成了基于芯片TL494、IR2110和SG3525A的风电逆变控制系统的硬件设计方案。     

Fuzzy logic based DSP controlled servo position control for ultrasonic motor

In this paper, position control of an ultrasonic motor was implemented on the basis of fuzzy reasoning. A digitally controllable two phase serial resonant inverter was developed to drive the ultrasonic motor by using a TMS320F243 digital signal processor. The driving frequency was used as a control input in the position control loop. The position characteristics obtained from the proposed drive and control system were demonstrated and evaluated by experiments. The experimental results verify that the developed position control scheme is highly effective, reliable and applicable for the ultrasonic motor.