Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

To study the requirements of the power supply in micro-arc oxidation (MAO) of magnesium alloy, many experiments were performed under the DC, unipolar, and ambipolar pulse output modes. Based on the experimental results and electric arc theory, the separate local arc discharge mechanism was put forward. It is considered that magnesium MAO process consists of three stages including anodic oxidation, micro-arc oxidation, and large-arc discharge in turn with increasing source voltage. The MAO film is composed of metal oxides that resulted from numerous discrete local arc discharges, which accumulate the non-equilibrium structure after undergoing sudden heating and cooling cycles. Separate local arc discharge is caused by the process in which the oxygen-based gas is ionized in the conduct channel bearing electric field intensity, changed from insulator to conductor that presents sharp negative resistance effect, and produced partially high temperature to ignite locally metal oxidation. The local arc discharge model is described as four courses: gas created from electrolysis, arc discharge, metals oxidization, and cooling and shrinking of oxides. The purpose of pulse supply is to inhibit the large-arc discharge by intervening proper cooling time, which cannot be actualized by a unipolar pulse mode because of the strong capacitive load characteristics but can be reached by an ambipolar pulse supply because the negative pulse period acts as cooling time. Using a discharge loop to remove the influence of load capacitive, a new type of pulse power supply for MAO is developed, so that the large-arc problem is resolved effectively, the film-forming efficiency is improved, and the pollution of the film and electrolyte caused by negative voltage is avoided.     

Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

To study the requirements of the power supply in micro-arc oxidation (MAO) of magnesium alloy, many experiments were performed under the DC, unipolar, and ambipolar pulse output modes. Based on the experimental results and electric arc theory, the separate local arc discharge mechanism was put forward. It is considered that magnesium MAO process consists of three stages including anodic oxidation, micro-arc oxidation, and large-arc discharge in turn with increasing source voltage. The MAO film is composed of metal oxides that resulted from numerous discrete local arc discharges, which accumulate the non-equilibrium structure after undergoing sudden heating and cooling cycles. Separate local arc discharge is caused by the process in which the oxygen-based gas is ionized in the conduct channel bearing electric field intensity, changed from insulator to conductor that presents sharp negative resistance effect, and produced partially high temperature to ignite locally metal oxidation. The local arc discharge model is described as four courses: gas created from electrolysis, arc discharge, metals oxidization, and cooling and shrinking of oxides. The purpose of pulse supply is to inhibit the large-arc discharge by intervening proper cooling time, which cannot be actualized by a unipolar pulse mode because of the strong capacitive load characteristics but can be reached by an ambipolar pulse supply because the negative pulse period acts as cooling time. Using a discharge loop to remove the influence of load capacitive, a new type of pulse power supply for MAO is developed, so that the large-arc problem is resolved effectively, the film-forming efficiency is improved, and the pollution of the film and electrolyte caused by negative voltage is avoided.     

A high voltage pulse power supply for metal plasma immersion ion implantation and deposition

We describe the design and implementation of a high voltage pulse power supply (pulser) that supports the operation of a repetitively pulsed filtered vacuum arc plasma deposition facility in plasma immersion ion implantation and deposition (Mepiiid) mode. Negative pulses (micropulses) of up to 20 kV in magnitude and 20 A peak current are provided in gated pulse packets (macropulses) over a broad range of possible pulse width and duty cycle. Application of the system consisting of filtered vacuum arc and high voltage pulser is demonstrated by forming diamond-like carbon (DLC) thin films with and without substrate bias provided by the pulser. Significantly enhanced film∕substrate adhesion is observed when the pulser is used to induce interface mixing between the DLC film and the underlying Si substrate.     

光伏发电系统直流串联微弱故障电弧检测方法研究

光伏发电系统直流故障电弧因随机性强、信号微弱、容易受负载突变影响而难以准确检测.根据光伏电池U-I输出特性,文中分析光伏发电系统直流串联微弱故障电弧产生机理,通过搭建光伏发电系统故障电弧模拟实验平台,分析了微弱直流串联故障电弧信号特性;进而提出了一种基于电流小波能量熵特征的检测直流串联微弱故障电弧的方法.该方法先计算电...     

Micro-arc Oxidation Inverter Power Supply Based on the Limited Bipolar Soft-switch Control Method

In order to overcome many limitations of the conventional power supplies, such as ponderosity, big wastage, and simplex output characteristic, a dual-inverter power supply is designed to meet the different requirements of micro-arc oxidation. The main circuit structure and principle of the dual-inverter power supply for micro-arc oxidation is described, the control system and the control adjustment method are also introduced. The dual-inverter technology is adopted in micro-arc oxidation power supply. The limited bipolar control mode is applied in the power inverter circuit for adjusting the voltage, and various voltage waveform can be obtained by controlling the chopper circuit. Meanwhile, the control accuracy and response speed are improved greatly because of the higher inverter frequency. The power supply can output direct current(DC) waveform, DC pulse waveform, symmetry alternating current(AC) waveform, asymmetry AC waveform, and so on. Besides, the parameters such as pulse width, range, frequency, duty cycle can be adjusted. The experimental result shows that the power supply has many advantages, such as stable output, wonderful waveform consistency and obvious advantage in technique, and it can meet the requirements of micro-arc oxidation process fully.     

双极性微弧氧化脉冲电源加工LY12铝合金工艺试验研究

利用自行研制的双极性微弧氧化脉冲电源对LY12铝合金进行了微弧氧化加工试验研究,并对不同形式的脉冲--正脉冲、正负交变脉冲以及正向正弦波脉冲加工生成的氧化陶瓷膜进行了膜厚度和膜硬度的比较.研究发现,同单纯的正向脉冲电源和正向正弦波脉动电源加工的工件相比,用双极性微弧氧化脉冲电源加工的工件氧化陶瓷膜的厚度大,与基体的结合紧密,膜的硬度高,说明双极性微弧氧化脉冲电源具有较好的成膜特性,并对双极性脉冲电源中负脉冲对生成氧化膜的作用机理进行了分析.     

离子渗氮用脉冲电源的研制

本文通过对比,论述了离子渗氮用直流电源的缺点以及脉冲电源在克服相应问题上的优势,研制了100kW离子渗氮用脉冲电源,介绍了其电路原理.此电源具有很大的推广应用价值.     

基于周期平均值外特性的脉冲MIG焊弧长稳定性研究

通过对脉冲熔化极惰性气体保护(Metal inert gas,MIG)焊脉冲平均电流电压变化率的计算,提出脉冲周期平均值外特性曲线,并对弧焊电源脉冲周期平均值外特性曲线和电弧静态性曲线的动态稳定工作点进行详细分析,得出利用脉冲平均值外特性控制脉冲MIG焊的控制策略。同时运用双闭环控制实现了基于弧压反馈的I/I模式控制数字化弧焊电源,此电源能在送丝速度稳定情况下自适应弧长扰动变化,实现脉冲弧焊过程一脉一滴熔滴过渡。通过弧长阶跃试验表明,脉冲弧焊过程中焊丝熔化速度快速跟踪弧长变化,具有良好的弧长动态调节性能,保持弧长动态稳定,即焊接过程稳定,焊缝成形良好,同时验证了分析过程正确性和设计过程的可行性。     

一种新型低功耗小型高压电源

介绍一种新型低功耗小型高压电源，该电源采用全集成化电路设计。由振荡电路产生脉冲方波推动开关电路，采用自举升压电路，提高高压变压器的初级电压。脉冲高压经高压变压器升压整流后，可得到需要的稳定直流高压，对于正高压，在高压升压电路后采用倍压整流，用直接取样反馈方式来凋整输出高压，使高压更趋稳定。该电源具有功耗低、体积小、重量轻、绝缘性能好等特点，而且输出高压连续可凋。电源的正负高压输出值分别为：正高压0～＋50kV、负高压0～-25kV。可用于小功率X光管供电和其他相关科学研究及野外作业。     

A power supply unit for discharging the plasma electron source

A power supply unit for discharging a low-temperature plasma generator based on discharge in the crossed electric and magnetic fields is described. The unit operates in a stationary mode with a preset stabilized (±2%) discharge current of up to 0.5 A and in a pulse mode (up to 20 A), taking into account special features of powering gas discharges.     

压电驱动无针注射器脉冲电源设计

针对压电驱动无针注射对电源的需求,设计了与压电无针注射器配套的脉冲电源,该脉冲电源的驱动控制系统由电池提供12V的直流电压,通过Buck与推挽电路级联电路升压后整流滤波输出0～400V直流可调电压,由反馈电路对输出电压进行校正,最后全桥逆变电路实现输出频率与占空比可调,且输出电压在0～400V随占空比的改变成线性变化的瞬时高压脉冲信号。实验结果表明,该脉冲信号稳定可靠,输出纹波在范围0.5%以内,满足了压电驱动无针注射电源需求。     

交流脉冲式磁控溅射靶极电源的研制

本文介绍了一种中频交流脉冲式磁控溅射靶极电源。该电源采用全桥逆变拓扑电路、PWM控制方式、输出功率叠加的方案，具有快速的过流检测与保护功能。在等离子体负载下进行了抑制弧光放电和空心阴极效应的实验，同低频直流脉冲电源相比，交流脉冲放电对其抑制是非常有效的。这表明该电源作为磁控溅射靶极电源是完全可行的，也为进一步探索交流磁控溅射新工艺提供了可靠的研究设备。     

新型纳秒级探地雷达脉冲源设计

针对超宽带探地雷达脉冲源的要求,提出并验证了一种利用FPGA触发来合成彼此有任意延迟的窄脉冲波形合成方法.研究和实际设计了一种提高脉冲源性能的新型宽范围输入输出的线性直流电源,并利用此电源制成了适用于多种雪崩管为核心的宽范围纳秒级脉冲源,给出了脉冲源各个单元的设计、及雪崩三极管的筛选及老化处理方法.在50 Ω负载上得到了脉宽在2 ～ 50 ns、幅度在20～180 V的多种超宽带窄脉冲,并对多种雪崩管的雪崩性能进行了对比,给出了集电极充电电容与脉冲幅度和宽度的关系.     

自适应型无阻高频脉冲电源的研究

采用双管正激交错并联结构设计输出电流连续可调的DC/DC变换器恒流源，主电路后级电路不用电阻限流，也不用电感限流，而是利用前级DC/DC变换器以及脉冲控制发生电路共同作用来控制后级电路中的加工电流。     

一种大功率直流开关电源的主电路设计

开关电源设计最重要的2部分是主电路和控制电路。根据大功率直流开关电源的设计要求,结合大功率直流开关电源的工作原理、电路的拓扑结构、运行模式的特点及相关技术参数,本文进行性能分析并计算各项参数,通过计算所得的数据结果选择各元器件,设计出各个独立模块,最后组装成大功率直流开关电源的主电路。     

Design and experimental study of a power supply for micro-wire EDM

This paper presents the development and application of a new power supply in micro-wire EDM. A transistor-controlled power supply composed of a low-energy discharge circuit and an iso-frequency pulse control circuit was designed to provide the functions of high frequency and lower energy pulse control. Pulse states are classified as open circuit, normal spark, arc discharge and short circuit by means of the level of gap voltage and associated discharge current. A power supply test revealed that a high current-limiting resistance results in a decrease of discharge current. Peak current decreases with an increase of pulse-control frequency. Experimental results not only demonstrate that the iso-frequency pulse generator can provide low-energy pulses with a frequency of 185 kHz and a discharge current of 0.7 A, they also verify the applicability of the developed power supply in micro-wire EDM.     

短电弧机床数控脉冲电源的研制

介绍了短电弧机床数控脉冲调频电源的设计和研制,提出采用两级调制实现电源输出参数（幅值、频率、占空比）的连续可调,并分别阐述了电源主回路、控制系统、保护系统的设计。电源以DC／DC全桥逆变作为一级调制实现输出脉冲幅值的可调．并联斩波电路作为二级调制实现输出脉冲频率和占空比的可调。实验结果证明电源运行可靠、输出特性良好、抗干扰能力强。     

A solid-state generator with pulsed excitation of the oscillating circuit

A solid-state high-frequency damping oscillation pulse generator based on a pulsed excitation circuit is designed. The frequency of high-frequency oscillations reaches units of megahertz with a pulse repetition rate in the continuous mode of up to 1 kHz. The frequency of output pulses determines the power consumption from the supply mains that does not exceed 700 W. In this case, the peak power of output pulses reaches hundreds of kilowatts with a generator efficiency of up to 65%, if the optimal resistive load is used. The main area of the generator application is the generation of low-temperature atmospheric-pressure plasma.     

ZK-1型多种步进电机驱动电源

步进电机驱动电源的核心是环形脉冲分配器。用EPROM构成环形脉冲分配器，配以外围电路便可构成一台多种步进电机驱动电路，它的主要特点是适用于多种相数的步进电机，可在整步或半步方式下工作。与微机直接连接，接口简单。     

基于PROTEL移相控制高频环节逆变器仿真研究

用Protel 99SE软件建立了高频脉冲交流环节DC/AC逆变器的模型并进行仿真研究,采用单极性移相SPWM控制策略,给出了主要的仿真波形.仿真结果表明,采用单极性移相SPWM控制策略的高频脉冲交流环节DC/AC逆变器是可行的.