New constant-frequency multiresonant boost convertor

A new zero-voltage-switching multiresonant boost convertor operating at constant switching frequency is presented. Its output voltage is regulated by controlling the freewheeling period of the resonant inductor. It possesses the advantages of a PWM convertor and frequency-modulated multiresonant convertor. Moreover, by absorbing all major parasitic components in its resonant circuit, parasitic ringing is eliminated.<>     

Single-switch two-output flyback-forward converter operation

A double power converter with fully independent regulated outputs is introduced. The proposed topology results from magnetic integration of flyback and forward power converters. The derived converter shares a single power switch having a single magnetic component. Also, only one standard pulsewidth modulation (PWM) integrated modulator is needed in order to keep independent closed-loop control of both output voltages. The double regulation may be sustained over a wide spread of current loads. Boundaries of full regulation and experimental results are presented     

浅说大功率IGCT变换器的几个问题

本文讨论大功率IGCT变换器的几个问题：三电平变换电路中的箝位电阻的作用；IGCT逆变器的过流保护和短路保护；IGCT变换器的输出容量与开关频率和输出频率的关系；在有源整流器中采用SHEPWM方法生成PWM信号；如何用4．5kV器件构造6．9kV逆变器。     

高可靠DC-DC变换器的设计

应用PWM设计高可靠DC-DC变换器,其开关频率更高,可达1MHz,这样减小了储能元件的尺寸,可采用陶瓷电容器,提高系统的可靠性,降低了成本。分析了Si9114的工作原理,并给出28V输入,5V/5A输出的DC-DC变换器的应用电路。     

Three-phase synchronous PWM for flyback converter with power-factor correction using FPGA ASIC design

The design and development of a synchronous pulsewidth modulation (PWM) generator suitable for the three-phase flyback converter with transformer isolated and power-factor correction using a field-programmable gate array is proposed. The proposed three-phase synchronous PWM makes it possible for the converter to obtain the sinusoidal supply currents with a near-unity power factor. A high-frequency transformer is considered in the design to provide galvanic isolation and serves the dual role of inductor and transformer. Results are provided to demonstrate the effectiveness of the design.     

基于电流型脉宽调制器的自适应反激驱动开关电源的设计

分析了一种采用3844B电流型脉宽调制器控制,实现多路输出的单端反激式大功率IGBT驱动电源。根据控制芯片特性与输出要求给出了详细的电路参数,设计了符合要求的高频变压器,提出改进的反馈控制方法,具有很强的自适应性。实验结果表明,该电源的可靠性更高,稳定性好,输出纹波小,能够适应规定电网电压波动195V到265V的要求,甚至更大的电压波动。     

数字控制PWM/PFM混合型AC-DC开关电源设计

采用数字控制方法,结合脉冲频率调制和脉冲宽度调制的特点,设计了一种采用数字控制初级反馈反激式开关电源。数字化控制技术可实现快速动态响应,严格的输出调节,以及多种PWM/PFM混合控制。最终利用Cyclone 3系列FPGA作为数字控制器进行恒压验证,其结果达到了预期设计要求。     

TRIAC dimmable ballast with power equalization

A two-stage, two-wire TRIAC dimmable electronic ballast for fluorescent lamps is presented in this paper. It is constructed by using a flyback converter as the input power factor corrector to supply a half-bridge series-resonant parallel-loaded inverter to ballast the lamp. The flyback converter is operated in discontinuous conduction mode so that the filtered input current profile is the same as the TRIAC-controlled voltage waveform. The switches in the inverter are switched at a constant frequency slightly higher than the resonant frequency of the resonant tank. Based on the constant average input current characteristics of the inverter, the dimming operation is simply achieved by pulsewidth modulation control of the magnitude of the flyback converter output voltage. No synchronization network is required between the input and output stages. In addition, a linear power equalization scheme is developed so that the dc-link voltage (and hence the lamp power) is in a linear relationship with the firing angle of the TRIAC. The average output voltage of the dimmer controls the equalized flyback converter output voltage. Modeling, analysis, and design of the ballast will be described. A prototype was implemented to verify the experimental measurements with the theoretical predictions.     

Constant frequency PWM capacitor voltage-clamped series resonantpower supply

The authors propose a capacitor-voltage-clamped series-resonant converter, regulated at constant frequency by pulse-width modulation (PWM), that is suitable for an offline isolated multiple output power supply. The principle of operation, theoretical analysis, simulation, design procedure, and design example are provided, along with experimental results. The validity of the theoretical analysis and the main properties of the proposed converter were demonstrated in the laboratory, with the design and construction of an isolated power supply rated at 12 V/16 A and operating at 100 kHz. The proposed technique significantly reduces the RMS value of the current through the transistors, reduces the size of the output filter capacitor, and improves dynamic response     

High-efficiency multiple-output DC-DC conversion for low-voltagesystems

This versatile power converter controller provides dual outputs at a fixed switching frequency and can regulate either output voltage or target system delay (using an external L-C filter). In the voltage regulation mode, the output voltage is monitored with an analog-digital (A/D) converter, and the feedback compensation network is implemented digitally. The generation of the pulsewidth modulation (PWM) signal is done with a hybrid delay line/counter approach, which saves power and area relative to previous implementations. Power devices are included on chip to create the two independently regulated output PWM signals. The key features of this design are its low-power dissipation, reconfigurability, use of either delay or voltage feedback, and multiple outputs     

Pulse Train control technique for flyback converter

Pulse Train/spl trade/ control technique is introduced and applied to flyback converter operating in discontinuous conduction mode (DCM). In contrast to the conventional pulse width modulation (PWM) control scheme, the principal idea of Pulse Train is to achieve output voltage regulation using high and low power pulses. The proposed technique is applicable to any converter operating in DCM. However, this work mainly focuses on flyback topology. In this paper, the main mathematical concept of the new control algorithm is introduced and simulations as well as experimental results are presented.     

一种基于UC2844的单端反激式高频稳压开关电源

本文设计了一种以UC2844电流型PWM控制器控制,多路输出的单端反激式开关电源。根据UC2844的电流控制模式给出以单端反激式拓扑结构和峰值电流PWM技术为基础的设计方法,通过测试得到的信号波形说明了本方法设计出的开关电源可以减小纹波和提高电源效率,保证电压的稳定输出。     

开关电源传导EMI仿真分析

随着电子技术的发展,电磁兼容性的研究越来越受到重视。文章以反激式开关电源为研究对象,分析并建立了MOSFET、变压器等元件的高频模型,利用电容、电感、变压器、MOSFET、功率二极管的高频模型组建了仿真电路。使用OrCAD10．5／PSpice软件模拟仿真,同时对其传导EMI进行了分析并提出了相应的抑制方法,这些工作对开关电源的电磁兼容性设计具有一定的指导作用。     

基于FPGA的高分辨率D／A转换器的实现

为增强FPGA（现场可编程门阵列）对模拟信号的处理能力,扩展FPGA的应用范围,介绍了一种基于FPGA实现高分辨率D／A转换器的技术。利用FPGA内部PLL（锁相环）,提高时钟信号的计数频率,从而提高PWM（脉宽调制）信号的基波频率,通过5阶巴特沃斯低通滤波器,实现14位高分辨率D／A转换器。阐述了PWM实现D／A转换器的理论基础和实际应用注意事项,该方法已用于实际D／A转换器系统,具有精度高、误差小的优点,对于FPGA的实际应用具有一定的指导意义。     

A new microcontroller-based technique for generating variable voltage/frequency sinusoidal PWM signals

This paper presents a flexible and robust microcontroller-based technique for generating the control signals of any sinusoidal pulse width modulation (SPWM) scheme for variable voltage/frequency output. The proposed technique exploits the fully static design of a high-speed microcontroller and generates the PWM control signals by varying the controller's clock, while keeping the number of the algorithm processing states constant. As the experimental results show, the technique can be used for transient-free frequency and/or voltage changes with very good resolution and a wide range of applications.     

H∞ control applied to boost power converters

The controller in a pulse-width-modulation (PWM) power converter has to stabilize the system and guarantee an almost constant output voltage in spite of the perturbations in the input voltage and output load over as large a bandwidth as possible. Boost and flyback power converters have a right-half-plane zero (RHPZ) in their transfer function from the duty cycle to the output voltage, which makes it difficult to achieve the aforementioned goals. Here, the authors propose to design a controller using H^∞ control theory, via the solution of two algebraic Riccati equations. The almost optimal H^∞ controller is of the same order as the converter and has a relatively low DC gain. The closed-loop characteristics of a typical low-power boost power converter with four different control schemes were compared by computer simulation. The H^∞ control was found to be superior in a wide frequency range, while being outperformed by the others at extremely low frequencies. Good agreement was found between simulation results and experimental measurements     

Adaptive off-time control for variable-frequency, soft-switchedflyback converter at light loads

The soft switching of a flyback converter can be achieved by operating the circuit in the critical conduction mode. However, the critical-mode operation at light loads cannot be maintained due to a very high switching frequency and the loss of the output voltage regulation. A control which regulates the output down to the zero load and maintains soft switching at light loads is proposed. The proposed control scheme was implemented in the 380 V/19 V, 65 W flyback DC/DC converter     

单端反激开关电源原理与设计

单端反激开关电源具有输出纹波小、输出稳定、体积小、重量轻、效率高以及具有良好的动态响应性能等许多优点,被广泛应用在小功率开关电源的设计中。UC3842是Unitorde公司推出的电流型脉宽调制器,该调制器单端输出,可以直接驱动双极型功率管或场效应管,适用于无工频变压器的20 W~80 W的小功率开关电源的设计。文中介绍了利用该集成芯片实现的具有双闭环电流(外回路和内回路)反馈系统的单端反激开关电源的原理和设计方法。     

基于UC3842的车用开关电源设计

基于UC3842高性能电流模式PWM芯片,提出一种供电动车无刷直流电机控制模块使用的开关电源设计方案。该设计由电动车的蓄电池供电,采用单端反激式结构,实现48V直流供电,12V的直流输出,具有瞬态响应快、稳定性好、输出电压精度高等优点,能够很好地满足电动车直流电机控制模块的供电需求。     

A robust hysteresis current-controlled PWM inverter for linear PMSMdriven magnetic suspended positioning system

Hysteresis current-controlled pulsewidth modulation (PWM) is very robust but it possesses nonconstant switching frequency, and it is difficult to use for high-performance position servo applications. This paper presents a robust hysteresis current-controlled PWM scheme for a magnetic suspended positioning system driven by an inverter-fed linear permanent-magnet synchronous motor having improved performance in these two areas. In the proposed control scheme, the conventional hysteresis PWM mechanism is augmented by a robust harmonic spectrum-shaping controller. The error signal, which represents the switching frequency deviated from the set one, is detected using a notching filter inverse model. Then, the current command is adjusted by a robust compensation signal. The hysteresis band can be equivalently varied to let the dominant harmonic frequency of inverter output be constant, wherein the frequency can easily be changed by tuning the center frequency of the notch filter. The gating signal of switches is not needed to be sensed for making the proposed control. The constant-frequency control performance yielded by the proposed controller is rather insensitive to the system disturbances and the neutral voltage variation due to isolated Y connection. Through applying the proposed PWM inverter, satisfactory position control requirements can be achieved by properly setting the dominant harmonic frequency according to the electromechanical model of the positioning system