Minus 35kV Space-Borne Instrument Power Supply

A -35kV power supply has been developed for a plasma experiment on the out-of-ecliptic mission. In addition, an isolation transformer has been developed to provide low voltage power at the -35kV potential. The design features incorporated to produce a spaceflight power supply housed within a 4 × 4 × 2.5 in package are discussed. The supply is powered from an unregulated spacecraft bus and provides a regulated output of -35kV ± 5 percent with less than 0.5 percent ripple over a temperature range -20°C + 60°C. The unit serves as a bias supply with an output current less than 0.5 , ?A. With the supply essentially operating unloaded, 5 percent regulation is achieved by sensing and regulating the first stage of a 12-stage Cockcroft/Walton multiplier. Control of the ac voltage input to the multiplier stack provides the regulation. The isolation transformer utilizes a ferrite u-core with the primary and secondary windings placed on opposite legs for separation. The transformer is encapsulated with the power supply.     

Novel hybrid 12-pulse boost-type rectifier with controlled output voltage

Novel hybrid 12-pulse line interphase transformer (LIT) rectifier systems with integrated single-switch or two-switch boost-type output stage that ensure a constant output voltage independent of mains and load conditions are proposed for supplying actuators of future more electric aircraft. The principle of operation, the dimensioning, and the system control are discussed. The theoretical considerations are experimentally confirmed for a 10 kW laboratory prototype. Finally, the single-and the two-switch system are comparatively evaluated concerning the level of input current ripple, power factor, and overall efficiency.     

AC/DC converter topologies for the Space Station

A new class of AC/DC converter topologies (Type-1 converters) is described, suitable for use in an advanced single-phase sine-wave voltage, high-frequency power distribution system, of the type that was proposed for a 20 kHz Space Station primary electrical power distribution system. The converter comprises a transformer, a resonant network, a current controller, a diode rectifier, and an output filter. The input AC voltage source is converted into a sinusoidal current source using the resonant network. The output of this current source is rectified by the diode rectifier and is controlled by the current controller. The controlled rectified current is then filtered by the output filter to obtain a constant voltage across the load. Three distinct converter topologies, Type-1A, Type-1B, and Type 1-C, are described, and their performance characteristics are presented. All three types have a close-to-unity rated power factor (greater than 0.98), low total harmonic distortion in input current (less than 5%), and high conversion efficiency (greater than 96%)     

双Buck半桥逆变器输入电容电压脉动的分析

双Buck逆变器(DBI)是航空静止变流器(ASIs)的常用拓扑,从双Buck半桥逆变器(DBHBIs)两直流电感中分离出交流电感使得体积、重量进一步减小。在正常工作,尤其是负载短路情况下,双Buck半桥逆变器输入侧电容上的电压产生与输出同频的脉动。以交流电感分立的双Buck半桥逆变器为例,分析了在额定负载、短路、级联工作等情况下输入电容电压脉动的产生原因,给出了该脉动的定量计算方法,并由此得出了输入侧电容容值的选择依据。最后通过仿真和实验,验证了文中分析的正确性。该分析方法同样适用于其他半桥型逆变器拓扑。     

An efficient active ripple filter for use in DC-DC conversion

When low ripple is required from a switched mode dc-dc converter, dissipative active filters offer an alternative to passive LC and coupled inductor filters. Analytical and experimental results are presented for a simple active ripple filter. The filter employs a pair of current transformers as sensors for feedforward and feedback control and two metal-oxide-semiconductor field-effect transistors (MOSFETs) as cancellation current drivers. Measurements demonstrate good ripple attenuation up to 5 MHz, more than 70 dB being obtained at 100 kHz, the switching frequency of a test converter. The overall efficiency was measured as 95%, with room for further improvement. The filter is suitable for input and output smoothing in dc-dc converters for aerospace and other critical applications     

Three-phase rectifiers that apply optimal current injection

A class of current injection based three-phase high power factor rectifiers is proposed. Low distortion of the input currents and high power factor are obtained applying near optimal current injection. The optimal current injection is discussed, and requirements it imposes to the current injection network are derived. A class of simple current injection networks that provide near optimal current injection, consisting of a transformer, two capacitors, and a number of resistors or resistance emulators is proposed. The power processed by the resistors or resistance emulators is shown to be 8.81% of the input power. Design of the current injection network is discussed, and dependence of the input current distortion on capacitance of the applied capacitors is analyzed. Volt-ampere rating of the transformer is shown to be only 0.16% of the input power. Effects caused by the output current ripple are studied, and a method for their compensation is proposed. Analytical results are experimentally verified. Switching resistance emulation is discussed and its feasibility is experimentally demonstrated     

Suitability of pulse train control technique for BIFRED converter

Pulse Train/spl trade/ control scheme is presented and applied to a boost integrated flyback rectifier/energy storage dc-dc (BIFRED) converter operating in discontinuous conduction mode (DCM), which avoids the light-load high-voltage stress problem. In contrast to the conventional control techniques, the principal idea of Pulse Train technique is to regulate the output voltage using a series of high and low energy pulses generated by the current of the inductor. The applicability of the proposed technique to both the input and magnetizing inductances of BIFRED converter is investigated. Analysis of BIFRED converter operating in DCM as well as the output voltage ripple estimation is given. Experimental results on a prototype converter are also presented.     

Analysis of a PWM-resonant converter

When a parallel resonant tank is excited by a bipolar current pulse train a sinusoidal voltage develops across the tank whose amplitude depends on the duty cycle of the pulse train. An isolated secondary can be derived by applying the tank voltage to an isolation transformer whose magnetizing inductance acts as the resonant inductor of the tank circuit. A dc output voltage is obtained after rectification and filtering of the sinusoidal secondary voltage and regulation is achieved by controlling the duty cycle of the pulse train. The sinusoidal nature of the voltage across the isolation transformer alleviates some of the noise problem associated with parasitic capacitances of an isolation transformer when operated with square voltage waveform. In this work the dc and small-signal analysis of the converter is given and an equivalent small-signal circuit model is derived. Experimental results which confirm the validity of the model are presented.     

激光器匹配驱动的色散渐变线分析

论述了采用渐变线阻抗变换器对半导体激光器进行匹配驱动时,当考虑渐变线色散影响情况的分析。给出了色散影响的概念、时域的分析计算方法及对三角形、指数形及切比雪夫渐变线的计算结果和分析。     

输入电压不平衡时的12脉冲自耦变压整流器

在含有较多非线性负载的航空供电系统中常存在三相输入电压不平衡的情况。详细分析了输入不平衡对12脉冲自耦变压整流器(ATRU)的输出电压、输入电流的影响,并提出了采用谐波抑制电抗器(HBR)来抑制谐波电流。分析了工作原理,比较了几种HBR构成方案,研制了一台2kW的演示样机。实验结果表明,谐波抑制电抗器有效抑制了三相输入电压不平衡的影响。     

Fourier theory of jumps applied to converter harmonic analysis

The Fourier theory of jumps (FTJ) is demonstrated as an aid in deriving closed-form analytical equations for converter switching harmonics. The switching waveforms analyzed are the input current and output voltage and current of a three-phase, ac-dc, step-down, dead-band pulsewidth modulated (PWM), unity power factor converter. The input current closed-form harmonic equation is derived for two parallel-connected, interleaved-PWM converters supplying the same load and sharing a common input filter. The equations are compared with PSpice^TM simulations and practical results     

斩控式机场助航灯光恒流调光源的研制

提出了一种PWM斩控式机场助航灯恒流调光源设计方案。应用PWM控制的AC／AC降压变换器,对负载电压进行调节,从而获得高质量和稳定的正弦负载电流。1kVA样机实验结果表明,采用该方案所设计的恒流调光源在输入电压波动和负载变化时均可以实现稳定的正弦负载电流,能够满足民用机场行业标准中对助航灯恒流调光电源的技术要求。     

Self-oscillating DC-to-DC switching converters with transformer characteristics

Fourth-order converters with both input and output filters are analyzed in self-oscillating sliding mode. The boost converter with output filter and the Cuk converter are shown to have stable dynamics and an equilibrium point with transformer characteristics. The analytical predictions are verified by experimental results.     

Buck-flyback DC-DC converter

It is difficult to obtain a large input/output voltage ratio with a DC-DC converter, because the duty factor d may not reach very small values. For the same reason, it is difficult to obtain an output voltage that is adjustable in a large range. A DC-DC converter circuit is proposed that overcomes this limitation by performing a voltage ratio d²/(1-d) in the best operating mode. Circuit operation is analyzed, operating modes are evidenced, and the voltage ratio is deduced in each operating mode as a function of output current, duty factor, and circuit component values. Boundary conditions between different operating modes are obtained; consequently, it is concluded that these conditions do not occur for some operating modes. Component ratings are summarized, to facilitate circuit design. The buck-flyback DC-DC converter is very suitable for low-voltage (e.g. computer) power supplies and for power supplies with the output voltage (adjustable in a large range) supplied from the mains without a mains voltage transformer     

Computer-Aided Design and Graphics Applied to the Study of Inductor-Energy -Storage Dc-to-Dc Electronic Power Converters

A series of nine programs are developed for the design of the inductors of single-winding flyback converters. Three converter types are considered: voltage step-up, current step-up, and voltage step-up/current step-up. For each of the converter types, three pulse modulators are considered: constant frequency, constant transistor on-time, and constant transistor off-time. Computer-graphics displays are used to assist in evaluating characteristics of the various converter-modulator combinations.     

Design and evaluation of a hybrid passive/active ripple filter with voltage injection

Active ripple filters can substantially attenuate power converter ripple, allowing considerable reduction in passive filter component size. Investigated here is a hybrid passive/active filter topology that achieves ripple reduction by injecting a compensating voltage ripple across a series filter element. Both ripple feedforward and feedback are employed. The design of sensor, amplifier, and injector circuitry for this application is explored. The experimental results demonstrate the feasibility and high performance of the new approach, and illustrate its potential benefits. It is demonstrated that the proposed approach is most effective in cases where it is desirable to minimize the amount of capacitance in the filter.     

Fault-tolerance wide voltage conversion gain DC/DC converter for more electric aircraft

In this paper, a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft (MEA) is proposed. The proposed converter consists of a basic Cuk converter module and n expandable units. By adjusting the operation state of the expandable units, the voltage conversion gain of the proposed converter could be regulated, which makes it available for wide voltage conversion applications. Especially, since mutual redundancy can be realized between the basic Cuk converter module and the expandable units, the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter, which reflects the fault tolerance of the converter and significantly improves the reliability of the system. Moreover, the advantages of small input current ripple, automatic current sharing and low voltage stress are also integrated in this converter. The working principle and features of the proposed converter are mainly introduced, and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.     

基于阻尼补偿的直流发电机带恒功率负载系统稳定性分析

提出了一种提高基于阻尼补偿的直流(DC)发电机带恒功率负载(CPL)系统稳定性的方法.依据输入滤波器输出阻抗极大值最小原则对基于阻尼补偿的直流发电机带恒功率负载系统输入滤波器参数进行了最优设计,给出了设计方法和流程.运用Bode图和Nyquist曲线对基于阻尼补偿的直流发电机带恒功率负载系统进行稳定性分析,并与在输出端...     

Flyback Converter Output Voltage Stabilization

The expression of the flyback converter output voltage (output power) is derived as a function of the supply voltage, load resistance, transformer ratios, transistor current gain, and base-circuit resistor value. Switching period and duty cycle are also calculated. A converter circuit is designed having stabilized output voltage, with respect to supply voltage, at constant load. The transistor base current is controlled by the supply voltage, via a nonlinear circuit. This feedforward circuit approximates with logarithmic characteristics the ideal hyperbolic dependence of the transistor base current as a function of the supply voltage. The converter has high performance and low cost. A cheaper circuit variant is presented, in which the high-voltage control transistor was eliminated.