25kV／2A谐振式恒流式电电源

为１ＭＪ电容器储能系统研制了一台输出电压２５ｋＶ，输出电流２Ａ的恒流充电电源，该电源采用零电流切换非连续全波谐振原理。串联ＬＣ谐振电路由接成全桥形式的４只大功率ＩＧＢＴ驱动，谐振频率固定为８０ｋＨｚ，开关工作频率３０－６５ｋＨｚ可调。谐调产生的非连续正弦形电流经匝比为１：５０的高压变压器升压至２５ｋＶ，经快恢复高压二极管串组成的全桥电路整形为一系列非连续的半正弦状电流脉冲，给１００００μＦ高压电容     

应用于标准光电高温计的多点控温系统设计

为满足功率半导体器件参数测量中对脉冲高压源输出脉冲幅值和宽度的需求,基于Marx发生器原理设计了一脉冲幅值和宽度连续可调的脉冲高压源,用以对功率半导体器件参数的快速测量。该脉冲高压源通过改进Marx发生器基本结构,采用双电源充电模式,减小了脉冲发生器的充电时间;采用同步放电电路,提高了脉冲电压的输出精度;在此基础上,采用快恢复二极管隔离每级Marx电路,降低了充电损耗。通过控制双电源充电电压和放电回路中固态开关导通时间,实现了输出脉冲电压幅值和宽度连续可调。实验结果表明,该脉冲高压源在脉冲幅值0~8000 V和脉冲宽度200~1000 μs之间连续可调,上升时间为35 ns,可满足功率半导体器件参数快速测量的需求。     

高功率脉冲磁控溅射电源的研制

高功率脉冲磁控溅射(HPPMS)因其高离化率而得到广泛关注.高压大电流脉冲电源是实现该技术的重要环节之一.本论文介绍了一种HPPMS电源,该电源由充电电源、斩波输出两部分组成,给出了主电路框图.分析了大电流对斩波开关过电压的影响,采用RC吸收和续流有效地抑制了电压过冲,用所研制的电源进行HPPMS镀膜试验,结果表明电源运行稳定可靠,制备的薄膜表面清洁、致密,其平均表面粗糙度很低.可以预见HPPMS技术将会促进镀膜技术的发展.     

高频高压低温等离子体发生研究北大核心CSCD

针对传统气体放电式等离子体发生器电源效率不高、使用寿命有限等问题,提出了一种零电压软开关高频高压低温等离子体发生方法,并设计了一个高效率低损耗的高频高压低温等离子体发生系统。该系统通过移相全桥软开关控制电路提供控制信号,光耦隔离电路降低强电干扰,在零电压软开关驱动下,经高频谐振升压电路对输入信号升压,实现低温等离子体的稳定发生。实验结果表明,系统工作频率稳定在262kHz,系统能够稳定发生低温等离子体,等离子体束长可达13.1cm,系统工作稳定后,零电压软开关系统的效率为87.4%,与传统直流等离子体发生炬最高77%效率相比,提高了10.4%,实现了驱动管耗的降低和输入电源效率的提升。     

高频高压低温等离子体发生研究

针对传统气体放电式等离子体发生器电源效率不高、使用寿命有限等问题,提出了一种零电压软开关高频高压低温等离子体发生方法,并设计了一个高效率低损耗的高频高压低温等离子体发生系统。该系统通过移相全桥软开关控制电路提供控制信号,光耦隔离电路降低强电干扰,在零电压软开关驱动下,经高频谐振升压电路对输入信号升压,实现低温等离子体的稳定发生。实验结果表明,系统工作频率稳定在262kHz,系统能够稳定发生低温等离子体,等离子体束长可达13.1cm,系统工作稳定后,零电压软开关系统的效率为87.4%,与传统直流等离子体发生炬最高77%效率相比,提高了10.4%,实现了驱动管耗的降低和输入电源效率的提升。     

脉冲射频/40kV高压直接耦合等离子体离子注入电源系统研制

研制的用于等离子体浸没离子注入(PIII)的电源系统采用高压隔离与高频滤波技术,将40 kV高压脉冲电源与13.56 MHz射频电源直接耦合,由单一输出电缆连接到实验靶台上,通过射频与高压脉冲的时序控制,实现了40 kV的高压脉冲与脉冲射频交替输出。工作过程中,通过射频产生等离子体,而后施加高压脉冲获得离子注入,进而实现PIII与沉积。该电源系统的性能指标为:高压脉冲电压幅值10~40 kV,脉冲频率10~1000 Hz,射频脉冲宽度0.01~10 ms,射频与高压间隔0.1~10 ms,高压脉冲功率6 kW,射频脉冲功率1 kW。实验研究表明能够有效的实现PIII。本文将介绍该种新电源的设计思想、电路以及在内凹零部件(如管筒内壁)等离子体离子注入等方面的应用。     

可编程的多波形脉冲低温等离子电源北大核心CSCD

高压脉冲已经运用于许多领域,其中一个就是可以用来产生等离子体电源。脉冲输出参数是脉冲波形、脉冲电压幅度、脉冲频率以及脉冲持续时间等。本文应用现代电力电子技术提出了一种脉冲电路的拓扑结构,通过一定的控制算法可以产生不同的脉冲波形且脉冲幅度可以成倍增加以输出高压脉冲,并开发出了一套可编程的脉冲输出设备以用于生物组织或者材料等的改性加工。电路拓扑采用电容、二极管及开关管配合的方式工作,控制算法由复杂可编程逻辑器件FPGA来实现,通过导通或者关闭开关管来控制电容的充电或者放电以形成脉冲波形。电路拓扑通过Saber仿真软件和实测波形图证实了其可行性。通过单脉冲和多波形脉冲在生物组织上的实验对比,反应了多波形脉冲能够更好的对生物组织进行消融处理。     

可编程的多波形脉冲低温等离子电源

高压脉冲已经运用于许多领域,其中一个就是可以用来产生等离子体电源。脉冲输出参数是脉冲波形、脉冲电压幅度、脉冲频率以及脉冲持续时间等。本文应用现代电力电子技术提出了一种脉冲电路的拓扑结构,通过一定的控制算法可以产生不同的脉冲波形且脉冲幅度可以成倍增加以输出高压脉冲,并开发出了一套可编程的脉冲输出设备以用于生物组织或者材料等的改性加工。电路拓扑采用电容、二极管及开关管配合的方式工作,控制算法由复杂可编程逻辑器件FPGA来实现,通过导通或者关闭开关管来控制电容的充电或者放电以形成脉冲波形。电路拓扑通过Saber仿真软件和实测波形图证实了其可行性。通过单脉冲和多波形脉冲在生物组织上的实验对比,反应了多波形脉冲能够更好的对生物组织进行消融处理。     

叠加型高压重频微秒脉冲电源研究

针对水污染领域的高压脉冲电源存在的输出脉冲质量差、输出脉冲不可调等问题,本文从脉冲电源主电路的整体结构和变压器磁芯优化2个方面进行改进。首先,结构上,前级Buck电路调节输出脉冲电压幅值,后级全桥逆变电路调节输出脉冲的频率和脉宽,由5个模块电路串联产生高压脉冲。其次,升压变压器选择高磁导率和高磁通密度的磁芯,保证输出脉冲质量。研制一台额定功率为3kW的样机,对电源进行单触发和重频试验。试验结果表明,该电源输出脉冲实现了频率、脉宽和电压幅值可调,满足设计指标。     

30kV高压脉冲电源及其废水降解电离试验

根据高压间隙放电的特性,设计了一种频率可调的高压脉冲电源.试验表明,高压脉冲电源输出电压可达30kV,频率范围为10～200Hz,应用于难降解有机废水的高压电离处理及与臭氧协同处理中,取得了较好的效果.     

改善的全桥变流器中谐振电容的研究

在倍流型整流零电压开关脉宽调制全桥变流器中引入一个谐振电容降低了对变压器漏感的限制，实现了在更宽负载范围内零电压开关以及整流二极管无电压振荡的自然整流，本文对改进的零电压开关脉宽调制全桥变流器的工作原理、谐振电容的作用以及谐振电容值的确定进行了分析，并在实验室建立了一个输出功率540W(54V，10A)的变流器进行了验证。     

A Dual-Capacitors Type Energy Recovery Power System for Repetitive Pulsed High Magnetic Fields

As a flexible and convenient tool, a repetitive pulsed high magnetic field (RPHMF) would be employed for scientific research and industrial applications. A novel RPHMF system design adopting a dual-capacitors type energy recovery power system is introduced in this paper. The energy stored in the magnet can be fed back to the capacitor by a choke coil and a resonant capacitor while the energy dissipated in the discharge will be replenished to the capacitor through a high frequency resonant capacitor charging power system (CCPS). The main advantages of the design are as followed: first, the energy feedback make the system more efficient; second, during the whole process there is no reverse voltage on the metalized film capacitors, improving the energy storage capacitors’ service lifetime and reliability remarkably; finally, convenience can be brought to the high frequency CCPS’s application. In this paper, theoretic analysis of RPHMF system is described and an experimental device with a bitter magnet as the load is built to test the design for its verification. A 1.2 Hz, 8 T repetitive pulsed high magnetic field is generated. Experimental results show that there is no reverse voltage on the energy storage capacitors in the whole process. The factors influencing the efficiency and frequency of the system are analyzed in detail.     

Analysis and implementation of an active snubber dc/dc converter with series?parallel connection in primary and secondary sides

An active snubber dc/dc converter to achieve zero voltage switching (ZVS) on power switch is presented. In the proposed converter, the primary windings of two transformers are connected in series so that the primary currents of the two transformers are equal. The secondary sides of the isolated zeta converters are connected in the parallel to share the load current and reduce the current stresses on the secondary windings of the two transformers. A boost type of active snubber is connected in parallel with the main switch to recycle the energy stored in transformer leakage and magnetizing inductors and to limit voltage stress of the main switch. During the transition interval between the active switch and the auxiliary switch, the resonance based on the resonant inductor and the output capacitor of the power switch will allow the switch to turn on at ZVS. The principle of operation, steady-state analysis and design consideration of the proposed converter are provided. Finally, experimental results for a 360 W (12 V/30 A) prototype circuit with 150 kHz switching frequency were given to demonstrate the circuit performance and verify the feasibility of the proposed converter.     

Measurement of 0-1 ml volumes using the procedure ofcapacitive-dependent crystals

In the paper, the use of a differential oscillator sensor structure in a capacitance sensor is presented. Investigations focused on the design and operation analysis of the oscillator differential structure in which the oscillation frequencies of the two oscillators are very close, and on the application analysis of capacitive-dependent crystals. In addition, the excitation of the entire sensor with stochastic test signals has been analyzed by the correlation deconvolution method which is also called the direct digital method (DDM). The compensation of temperature and voltage influences, as well as disturbing noise signals, are included. The area of operation and the uncertainty of the sensor with and without the test signal are given as well. When designing the capacitance sensor, the problems regarding the source of stable oscillation, compensation of temperature, the influence of supply voltage, noise, and A/D and D/A conversion occur in the operation range under 1pF. The pulse width module, which forms pulse-width modulated high-frequency current pulses, is the proposed solution. With these pulses, the capacitor in the integration element is charged or discharged. In this way, we benefit from the fact that the capacitor's voltage increases linearly if it is charging by a constant current. As the charging is affected only by the current pulses which require an adequate current, the disturbing noise signals do not affect the capacitor charging. The correlation determination of the measuring value is primarily important for the determination of end values. Several experiments have been carried out to investigate the method's possible applications. The method is linear in the range of work and ensures the uncertainty in the range below 0.01%. The experimental results of 0-1 ml volume measurements are shown. The volume measurement uncertainty (0-1 ml) Is less than 0.05% (T=15 to 25°C)     

一种新型软开关BUCK变换器

本文提出一种新型软开关BUCK变换器。所提出的变换器具有如下的优点,零电压、零电流导通,零电压关断;不增加开关管的电压电流应力;输出电感电流工作在连续电流模式,其纹波很小;变换器可以工作在固定的频率,采用PWM控制。由于软开关的使用,变换器可以工作在很高的频率,同时其效率也很高。Pspice软件仿真验证了该电路的理论设计和分析。     

Design,real-time modelling,simulation and digital implementation of phase-locked loop-based auto-synchronising current-sourced converter for an induction heating prototype

Induction heating (IH) converters operate just above resonant frequency, at near unity power factor (UPF), to supply power to the targeted work-piece. Some power electronic converter-fed IH systems use power control strategies based on dynamic tracking of the changing resonant frequency as the work-piece gets heated up (since inductance changes). Therefore, the correct in-process determination of the resonant frequency is essential. A method of dynamically detecting the resonant frequency is by calculating the phase-shift between current and voltage continuously during the process. In case of CSI- (and VSI-) fed IH, the phase-shift between voltage and current is zero at resonant frequency. Hence one way of identifying the resonant frequency is by varying the frequency until the phase-shift is zero. For controlling this phase-shift between current and voltage waveforms, most of the controllers use a phase-locked loop (PLL) IC. In this paper, a novel method for the dynamic tracking of resonant frequency is proposed and the practical implementation of the same, using a field-programmable gate array (FPGA) based digital-PLL, is presented. The scheme is first simulated with generated off-line signal samples and then implemented on a real-time model of a CSI-fed IH application. Finally, the digital-PLL logic is implemented on controller hardware and practically tested in a laboratory-made experimental set-up of 2 kW at a nominal frequency of 10 kHz. The switching frequency is auto-synchronising. This fact is practically verified both by varying (i) the geometric dimensions as also (ii) the initial temperature of the work-piece. It is practically observed in the oscillograms that the phase gets locked in few cycles (and hence ensures quick tracking of the dynamically changing resonant frequency for this set-up).     

可编程数字控制精密延时电路设计

设计一种基于斜波式发生器原理可编程数字控制精密延时电路,用恒流源电路充放电和18位的DA转换器分别接入高速比较器的两端,DA转换器预先设定一电压基准,恒流源充电电容达到电压基准,高速比较器开始反转,形成一个触发脉冲信号,然后充电电容通过高速二极管快速放电重新计时。设计成18bit数字控制可编程动态范围2ps的采集时间间隔,提高采集信号的精度和频率。     

Circuit design of an integrable simulated inductor and itsapplications

Gyrator principles are used to design an integrable voltage-controlled simulated inductor with inductance variable from 0.1 to 250000 H or even higher. One of the features of this simulated inductor is that it contains two voltage-controlled current amplifiers with controlling terminals connected in parallel. For a resonant circuit consisting of such a simulated inductor and an external capacitor, the resonant frequency will be linear with the controlling voltage. It can be employed to realize a sine-wave oscillator or filter whose operation frequency is changed linearly with the controlling voltage. In this work a linear voltage-controlled sinusoidal oscillator, which was designed to have an oscillation frequency from several kHz down to 0.01 Hz, is taken as an example to illustrate an application of the simulated inductor. In this case the simulated inductor was made up of discrete components and the oscillator has been employed to provide standard signals for research on differential transformation of physiological spikes in medical science     

A commutation strategy for IGBT-based CSI-fed parallel resonant circuit for induction heating application

A brief study on a commutation strategy for a current source inverter (CSI)-fed parallel resonant circuit, using switches formed by IGBTs with series diodes, is presented in this paper. The dynamic behaviour of the inverter and different strategies for its reliable operation are discussed here considering parasitic inductance and overlap time between CSI switching devices. The dynamic behaviour of the switches decides the upper frequency limit for the application. IGBTs with the series diodes behave as uni-directional current switches with bi-directional voltage blocking capability. This feature should be taken into account to decide on an appropriate switching strategy for this converter configuration.     

A modified circuit topology for inductive pulsed power supply based on HTSPPTs

High temperature superconducting pulsed power transformer (HTSPPT) provides an efficient method for inductive energy storage and current multiplication. The primary inductor of HTSPPT used for energy storage is made of high temperature superconducting coils, and the secondary inductor used for current pulse generation is made of normal conductor coils. In the initial circuit, the secondary inductor generates current pulse by switching out the coupled primary superconducting inductor. However, during the switching period, the leakage flux caused by imperfect coupling and the sudden change in primary current induce a voltage across the opening switch which exceeds the affordability of modern solid-state switches. In previous studies, a half-cycle oscillatory discharge circuit is proposed to mitigate these problems by using a capacitor to recapture the energy in the leakage flux and to slow down the turnoff of current in the primary. However, there are still some problems should be settled. For example, the output pulse cannot be adjusted, the residual energy cannot be recovered and the capacitor branch circuit may have an impact on the charging process. In the paper, a modified discharge circuit topology is introduced to solve these problems. A multi-module system comprising of several HTSPPTs charging in series connection and discharging in parallel is also designed and simulated. This system can be used to power an electromagnetic emission device.