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1.
朱镇生 《电子技术》1989,16(8):45-45
目前,大多数彩色电视机都是从回扫变压器直接引出脉冲电压加到显像管丝极作为丝极电源,这样做的好处是电路比较简单.由于行输出级的直流电源电压是经过稳压的,这种脉冲电压也是稳定的. 回扫变压器脉冲电压的有效值不能用普通电压表进行测量.本文所述的有效测量方法,是利用简单的小型热敏电阻通过热量比较的方法对丝极电压有效值进行测量. 某47cm彩色电视机采用470NWB22A型显像  相似文献   

2.
为了对电容重复频率且高能量转换效率地充电,开展了全桥串联谐振充电电源的理论设计。通过数值解析的方法获得谐振电感、电容、功率器件耐压与通流、电源功率、脉冲变压器伏秒数等参数,通过数值模拟的方法获得脉冲变压器励磁电感参数,以基于Pspice的全电路仿真验证设计参数的合理性。仿真结果表明为了实现对110 nF电容1 kHz重频充电,在初级电压为1.2 kV和谐振参数为33 kHz时,谐振电感、电容应分别为625 nH,37μF,脉冲变压器伏秒数、励磁电感至少分别应为45 mVs、1 mH,功率器件峰值电流约300 A。  相似文献   

3.
当彩色电视机行回扫变压器在额定工作状态下工作时,在其初级线圈两端输入恒定直流电流,并且使电流方向与行回扫变压器供电电源提供的电流方向保持一致。逐惭增加恒定直流电流到达某一数值时,用示波器可以观察到行回扫变压器初级线圈电流在正向峰值附近出现非线性上升。以行回扫变压器正向峰值电流出现非线性上升临界点为标准,可得出行回扫变压器最大输出功率Pmax与电源电压Vo、电源电流Io、直流叠加电流I及行回扫变压器工作效率η的关系式为Pmax=ηVoIo TsTηVoI。  相似文献   

4.
基于TOP Switch Ⅱ的开关电源设计   总被引:1,自引:0,他引:1  
介绍以TOP227Y为核心制作实验反激式稳压电源的工作原理,通过TL431与光耦PC817闭环反馈来控制TOP控制端电流大小,改变脉冲占空比,使开关电源在负载变化和输入电压变化时能量状态、电路状态的稳定。合理改进变压器设计以及制作工艺,减小开关电源电磁干扰,减小输出电压的纹波含量。  相似文献   

5.
结合机载电子设备低谐波污染的需求,针对机载变频器设备研制三相输入、高功率因数、高可靠的变压整流器.考虑到谐波电流和体积重量的要求,选取18脉冲不对称式自耦变压整流器方案.详细分析了电路的工作原理,忽略直流侧的电流脉动,推导了电路的输出电压和输入电流特性,给出了自耦变压器的设计依据.最后完成了21 kW18脉冲变压整流器的电路参数设计和硬件实验.额定条件下,整流器功率因数为0.996,总谐波电流含量为7.6%,变换效率为0.977.系统总重约为12 kg,其中所设计的R型三相自耦变压器重量为4.45 kg.  相似文献   

6.
杨力  张师斌  赵宁 《电子器件》2015,38(2):312-316
基于UCC28019A设计的功率因数可调单相AC-DC变换电路。MSP430单片机作为其控制核心,使用高精度24bitΣ-Δ型ADC采样,可完成对输入电压有效值、输入电流有效值、有功功率有效值、功率因数等参数的测量。由UCC28019A完成功率因数的校正,通过控制数字移相电路对外围电流反馈信号移相,实现功率因数在0.8~1.0范围内的调整。本设计还可通过对输出电流和电压的监测,实现2.5A过流保护和36V稳压输出的功能。  相似文献   

7.
文中针对非接触能量传输系统,对其松耦合变压器的原副边线圈进行串联补偿(SS补偿)。在该种补偿状态下进一步分析了非接触能量传输系统副边输出电流与原边输入电流、输出电压与输入电压、输出功率与输入电压之间的关系。通过仿真,验证了上述分析的正确性。  相似文献   

8.
LT1615/LT1615-1是一款微功率增强型DC/DC(直流/直流)升压变换器,5个单元电路封装在一个微型片状 SOT贴片器件内。LT1615 芯片设计用于电流限制在 350mA 和输入电压在 1.2~15V 范围的高功率系统;LT1615-1 芯片单个单元则用于电流限制在100mA和扩展输入电压在1~15V范围的低功率系统LT1615/LT1615-1 两种芯片装置,功能作用相似。两个装置无载状态下的静态电流均为 20mA,关闭状态下的电流可低至 0.5mA。采用单触发脉冲方式(而不使用昂贵的变压器)可使电压峰值达36V,经电容器形成高电压输出,直流电压(叠加在输入电压上)可高达34V。…  相似文献   

9.
特点计算:真有效值平均整流值绝对值提供:200mV满度输入范围高输入阻抗:10~(12)Ω低输入偏置电流:最大25pA高转换精度:±0.3mV±0.3%×输入电压有效值转换峰值因数高达5宽电源电压范围:+2.8V,-3.2~±16.5V低功耗:最大电源电流200μA缓冲电压输出AD737不带缓冲电压输出,但可提供电源“待机”方式  相似文献   

10.
特点 ·计算: 真有效值 平均整流值 绝对值 ·提供: 200mV满度输入范围 高输入阻抗:10~(12)Ω 低输入偏置电流:最大25pA 高转换精度:±0.3mV±0.3%×输入电压 有效值转换峰值因数高达5 宽电源电压范围:+2.8V,-3.2~±16.5V 低功耗:最大电源电流200μA 缓冲电压输出  相似文献   

11.
This paper presents a voltage changer optimized to multiply or to divide the input voltage by an integer factor of 2, 3, 4, ..., with a very high efficiency. The paper first introduces a review of the quasi-continuous current transformer converter in a step by step fashion. The last step presents the full bidirectional zero voltage switching (ZVS) converter. The theoretical study demonstrates the way to achieve ZVS operation by only decreasing the value of the transformer magnetizing inductance. ZVS conditions (developed in the paper) lead to an interesting way to control the converter, and a discrete variable frequency control is proposed. Allowing triangular current in the transformer leads to ZVS in the expanse of higher root-mean-square (RMS) current. The evaluation of this current is also carried out in the theoretical study. An experimental implementation shows an efficiency higher than 97.5% and confirms the accuracy of the theoretical study.  相似文献   

12.
Data published for the symmetrical push-pull power converter (SPPPC) show that the matrix transformer and the cross-coupling capacitors in this buck-type topology introduce unusual waveforms and properties. Circuit operation is examined in order to seek a simplified explanation of the published observations. Steady-state performance is analyzed and design equations are developed using state-space averaging. It is found that the SPPPC is equivalent to the conventional push-pull converter with an input filter as far as steady-state behavior and voltage/current ripple are concerned. Despite the presence of the cross-coupling capacitors, the currents in the primary windings in series with the same switch are identical. The RMS current in the primary windings of the SPPPC is lower than that in the conventional push-pull converter  相似文献   

13.
A flyback-type of a transformer-coupled DC/DC power converter supplies a train of current pulses to charge an energy-storage capacitor to a desired high voltage, converting input DC power obtained from a lower voltage DC source. The energy-storage capacitor is charged to a specified voltage within a specified time with minimum peak and RMS currents in the transistor, the rectifier diode, the transformer windings and the DC power source, minimizing the i2R losses. This is done by generating: (1) energy-storage current pulses in the power transistor and the transformer primary winding in which the current increment from the beginning to the end of a pulse is only a small fraction of the final (peak) value; and (2) energy-delivery flyback current pulses in the capacitor and the transformer secondary winding in which the current decrement from the beginning to the end of a pulse is only a small fraction of the initial (peak) value. Recommended methods are: (1) hysteretic current-mode control with current sensing in both transformer windings; (2) peak-current-commanding current-mode control with switching frequency or transistor-nonconducting time varying in a prescribed way during the charging; or (3) valley-current-commanding current-mode control with switching frequency or transistor-conducting time varying in a prescribed way during the charging. Compared with one nonoptimal method, peak currents are reduced by a factor of about 2 and i2R power losses are reduced by a factor of about 1.33  相似文献   

14.
针对目前PV光伏并网发电系统的核心逆变器的现状、结构和控制方法进行了详细的分析,从电网、PV系统及用户的需求出发,指出传统的单级全桥逆变器普遍具有不能处理较宽的输入PV电压,且需要重型工频升压变压器等缺点。在此基础上,本文创新设计并实现了一种基于单级全桥逆变器的并联耦合改进结构。实测证明这种并联耦合反激结构可以有效地减小通过大容量输入电解电容的纹波电流的RMS,从而延长电容的寿命;还可减小输出电流的纹波,从而降低输出电流的THD(谐波失真);还可适应较宽的输入电压,减小交流纹波,减小磁芯,同时可以提供较高的额定输出电流等优点。  相似文献   

15.
The use of buck-derived topologies for unity power factor AC-to-DC applications is limited by their inherent inability to draw current from the line in those intervals, during the line half period, in which the input voltage is lower than the output one. This drawback is overcome in the proposed high-quality rectifier based on the forward topology with secondary-side resonant reset. The employed secondary side reset capacitor is able to provide proper transformer reset by recycling the transformer stored energy to the load and, at the same time, it allows to draw energy from the line even when the input voltage is lower than the output one. Consequently, besides a better utilization of the transformer core (bipolar core excitation), a low distorted input current waveform can be obtained with a power factor close to unity. Experimental results of a 200 W prototype confirm the theoretical expectations.  相似文献   

16.
吴再群 《电子科技》2012,25(9):79-81,84
为了测试光纤电流互感器中由于Faraday效应引起的旋转量,提出了采用锁相放大器处理信号的方法,改进了传统的将交流成分与直流成分相除的方法。系统将采集信号做单端电压输入测试和差分电压输入测试,并比较了单端输入与差分输入的测试效果,定性分析了输出幅值与被测电流的关系。测试结果表明,锁相放大器输出幅值与被测电流具有线l陛关系,且差分输入较单端输入幅值大、线性度好、对外界干扰抑制性强。其成果为进一步研究基于旋光效应的光纤电流互感器的应用奠定了基础。  相似文献   

17.
This paper deals with the performance evaluation of space-vector-modulated matrix power converters under input and output unbalanced conditions. Two control strategies of the input current displacement angle are presented and compared in order to emphasize their influence on the input current harmonic content. The first is based on keeping the input current vector in phase with the input voltage vector. In the second, the input current displacement angle is dynamically modulated as a function of positive- and negative-sequence components of the input voltages. In both cases, the harmonic content and the three-phase RMS value of the input current have been evaluated analytically. The input current harmonic spectrum is quite different for the two control strategies and can be related to the input and output unbalance. It has been verified that, in the usual case of balanced output conditions, using the second method, it is possible to eliminate the harmonic components of the input current. Some numerical simulations are presented to confirm the analytical results  相似文献   

18.
基于结型场效应晶体管(JFET)和双极型晶体管(BJT)兼容工艺,设计了一种低失调高压大电流集成运算放大器。电路输入级采用p沟道JFET (p-JFET)差分对共源共栅结构;中间级以BJT作为放大管,采用复合有源负载结构;输出级采用复合npn达林顿管阵列,与常规推挽输出结构相比,在输出相同电流的情况下,节省了大量芯片面积。基于Cadence Spectre软件对该运算放大器电路进行了仿真分析和优化设计,在±35 V电源供电下,最小负载电阻为6Ω时的电压增益为95 dB,输入失调电压为0.224 5 mV,输入偏置电流为31.34 pA,输入失调电流为3.3 pA,单位增益带宽为9.6 MHz,具有输出9 A峰值大电流能力。  相似文献   

19.
提出了利用电流纹波率设计反激式变压器和判别其导通模式的方法,用该方法导出了反激式变压器从CCM进入DCM模式的数学式,用MATLAB计算并分析了输入电压、负载电流及反射电压对导通模式的影响。设计了一款反激式开关稳压电源,测量了变压器的电流波形。实验表明,测量结果与推导的数学式相符,用电流纹波率设计反激式变压器比传统的波形系数更直观和便于测量。  相似文献   

20.
杨照辉  张菁  梁宝娟 《现代电子技术》2010,33(4):196-197,200
提出一种基于模块串联的适用于高压输入(1kV以上)的DC/DC小功率变流器拓扑,分析其均压均流原理,讨论元器件参数对均压均流的影响。采取模块化设计,利用基本模块在输入侧串联的方法解决直流输入电压高于开关管最高耐压的矛盾。在不增加控制复杂度的前提下,适当选取输入侧串联模块的级数,可使输入电压高到几千伏甚至上万伏。  相似文献   

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