An improved hysteresis current controller for reducing switchingfrequency

In this paper, an improved invertor hysteresis current controller is proposed. It coordinates the switching of the three-phase switches in the d-q phase plane. In addition to the current error, information of the current error derivative is further employed so that one can take more advantage of adding the zero voltage vector for reducing the switching frequency. A simple hardware implementation of the improved hysteresis current controller is also proposed such that merits of the conventional hysteresis current controller can still be kept. Theoretical basis and some simulation and experimental results are presented to demonstrate the validity of the improved hysteresis current controller     

Improved hysteresis band current controller

A new hysteresis band current controller for voltage source inverters is presented. This new technique, which has been experimentally verified, is based on the use of a second input current error derivative for the selection of the zero voltage vectors V_0,7 , which greatly reduces the inverter switching frequency     

A novel SVM-based hysteresis current controller

In this paper, a novel space vector modulation (SVM)-based hysteresis current controller (HCC) for squirrel cage induction motors is proposed. This technique utilizes all advantages of the HCC and SVM technique. The controller determines a set of space vectors from a region detector and applies a space vector selected according to the main HCC. A set of space vectors including the zero vector to reduce the number of switchings is determined from the sign of the output frequency and output signals of three comparators with a little larger hysteresis band than that of the main HCC. A simple hardware implementation is proposed and experimental results of the SVM-based HCC are also shown     

Sequential design of hysteresis current controller for three-phaseinverter

In this paper, a novel multivariable hysteresis current controller for three-phase inverters is presented. Hysteresis controllers are intrinsically robust to system parameters, exhibit very high dynamics, and are suitable for simple implementation. The main drawback of the hysteresis controller is a limited control on transistors' switching frequency. Very high switching frequency may result if three independent controllers are used. Multivariable solutions were proposed in the literature to solve the problem. In this paper, it is shown how the use of a sequential design for the multivariable controller can further contribute to transistors' switching frequency reduction, with no significant increase in the hardware implementation complexity. The proposed controller is illustrated and compared with other hysteresis controllers presented in the literature. It ensures a significant reduction of transistors' switching frequency with respect to the other tested controllers, under the same operating conditions. A prototype controller is also presented. The effects of noise captured by current sensors (especially Hall-effect type) on the performance of industrial hysteresis controllers are discussed. It is shown how the sequential design of the controller can also help in solving this critical problem. Experimental results are reported to confirm the quality of the proposed controller. The system stability condition is derived in an appendix     

A fully digital hysteresis current controller for an active power filter

An active power filter is used to eliminate current harmonics produced by nonlinear loads. This paper discusses a fully digital method of controlling a power inverter used to inject the active filter compensating currents into the power system. A digital signal processor performs the harmonic isolation and generates a digital reference current. A hysteresis current controller has been implemented in a field programmable gate array that generates the inverter switching signals using this reference. This reduces the analogue circuitry and enhances the system's immunity to electromagnetic interference. The performance of a small-scale inverter under completely digital control is presented and discussed.     

An improved cosine-mode controller for SCR converters

An improved cosine-mode controller for silicon-controlled rectifier (SCR) power converters is presented. The proposed scheme linearizes the input/output transfer function of SCR power converters. The replacement of monostables by AND gates in the controller eliminates false turn-ons due to bouncing inside analog comparators. Experiments have been performed and satisfactory results are recorded     

An improved LQR-based controller for switching DC-DC converters

A general approach for controlling pulse-width-modulated (PWM) -type switching DC-DC converters digitally using state-feedback techniques and linear optimal control theory is reported. The methodology for redesigning the state estimator is investigated, and a method derived from the general linear-quadratic-regulator (LQR) problem, is proposed. The method is found to offer better transient responses and robustness to uncertainties in plant parameters when compared with the typical eigenvalue-assignment method. Special attention is directed to plant models with possible migrations of the open-loop zeroes across the stability boundary during operation. Results of applying these techniques to a published Cuk converter are reported to illustrate different points of interest     

An error bounded current controller with constant sampling frequency

In this paper, a constantly sampled current controller is proposed such that the controlled current can track the command within a specified error bound to guarantee the desired power quality. The authors further propose a simple two-value inner bound for current error comparison to determine the right time to add the zero-mode control to reduce both the switching frequency and the resulting current error. Moreover, an upper bound of the constant sampling period for the controller to guarantee the desired performance is derived and some design criteria are given for proper coordination among the design parameters. Finally, some simulation and experimental results are given to demonstrate the feasibility of the proposed current controller.     

An improved Prandtl-Ishlinskii model for compensating rate-dependent hysteresis in fast steering mirror system

To solve the rate-dependent hysteresis compensation problem in fast steering mirror (FSM) systems, an improved Prandtl-Ishlinskii (P-I) model is proposed in this paper. The proposed model is formulated by employing a linear density function into the STOP operator. By this way, the proposed model has a relatively simple mathematic format, which can be applied to compensate the rate-dependent hysteresis directly. Adaptive differential evolution algorithm is utilized to obtain the accurate parameters of the proposed model. A fast steering mirror control system is established to demonstrate the validity and feasibility of the improved P-I model. Comparative experiments with different input signals are performed and analyzed, and the results show that the proposed model not only suppresses the rate-dependent hysteresis effectively, but also obtains high tracking precision.     

一种改进的支路漏电流检测方案

直流系统(例如220vdc输出电源系统)支路绝缘下降检测系统中,其使用的漏电流传感器基本都属于闭环式传感器,该传感器有个弊端:一旦现场出现传感器失效的话,更换特别困难。本文提出了一种新的改进方案,具体思路如下:因为高导磁环线圈损坏的概率非常低,绝大部分传感器故障都是其基本电路(运放,方波电路等)的失效导致,采用高导磁环形线圈和基本电路分离措施,把基本电路放置下级采集设备中,万一出现故障,也仅需替换下级采集设备即可,该方案大大减少了支路传感器损坏概率,回避了传感器在线更换困难的难题,与此同时,该改进方案还简化系统接线、降低产品成本。     

An autonomous controller for improved dynamic performance of parallel-connected,single-phase inverters

A new control technique is presented for the parallel connection of distributed generation inverters. The proposed control technique is based on a modification of the power angle droop control method, and uses only locally measured feedback signals. An improvement in transient response is achieved because the real and imaginary components of the output current are used when deriving the power angle droop controller. The method achieves good active and reactive power sharing and minimises circulating current between parallel connected units. Improved transient response is obtained whilst maintaining power sharing precision or output voltage and frequency accuracy. Simulation and experimental results validate that performance is better than that attained with conventional droop-based approaches.     

Variable-band hysteresis current controllers for PWM voltage-sourceinverters

Hysteresis current controllers having fixed bands are used in inverters of high-performance AC drives. The switching frequency of such controllers varies over the fundamental period of the modulating signal. The maximum switching frequency (MSF) of these controllers is high. To limit the MSF within the limit of inverter switches, fixed carrier lockouts are usually incorporated. The incorporation of carrier lockouts causes current distortion, and load currents do not confine within the predetermined band. In this paper, two new controllers are proposed. One is a mixed-mode controller of sinusoidal band added to a fixed band, and the other is an equidistant-band current controller, performances of the proposed controllers are compared with the performances of the conventional fixed-band and sinusoidal-band controllers     

Three-phase switch mode rectifier with hysteresis current control

A three-phase configuration of a switch mode rectifier (SMR) that makes use of continuous conduction waveform of the input supply current is suggested. Continuous conduction is achieved by the hysteresis current control (HCC) technique. This three-phase SMR operates at close to unity power factor and has reduced current stresses on the switching devices because of the continuous nature of input current. The conduction period considered for the rectifier diodes is 180°. Digitally simulated performance results are provided. Selected experimental results demonstrating the SMR operation are also presented     

CMOS current Schmitt trigger with fully adjustable hysteresis

A CMOS current Schmitt trigger whose hysteresis is independent of process parameters, transistor dimensions and power supplies is described. The hysteresis is determined by two currents and is adjustable over the range of the input current. The circuit function can be extended to a two-input current comparator with adjustable hysteresis.<>     

An improved boost PWM soft-single-switched converter with lowvoltage and current stresses

This paper presents an improved regenerative soft turn-on and turn-off snubber applied to a boost pulsewidth-modulated (PWM) converter. The boost soft-single-switched converter proposed, which has only a single active switch, is able to operate with soft switching in a PWM way without high voltage and current stresses. This is achieved by using an auxiliary inductor, which is magnetically coupled with the main inductor of the converter. In order to illustrate the operating principle of this new converter, a detailed study, including simulations as well as experimental results, is carried out. The validity of this new converter is guaranteed by the obtained results     

基于AD8205型高端电流传感器的 PWM电流控制器

高精度大电流控制器有着广泛的应用,但在高共模电压情况下输出电流的检测电路比较复杂.AD8205型高端电流传感器可以简化检测电路,采用AD8205和UC3842电流型PWM控制电路实现PWM可调电流源,电路结构简单可靠,输出电流精度高.     

热插拔控制器构成限流电路

为避免电源在系统出现短路或过载时损坏,常采用限流电路为电源提供保护.针对这种应用,集成电路制造商提供了内置P沟道MOSFET和限流门限可调的芯片,这些芯片大多用于5V系统,将系统的最大电流限制在2A以内,电流精度较低(20%至50%).利用具有电流调节功能的"热插拔控制器"可构成高精度的通用限流电路(图1),外部MOSFET和电流检测电阻使该类芯片可用于3V至12V供电系统,CTIM引脚接地,抑制芯片的双速/双电平检测功能,使芯片处于开启模式.依照下式选择检流电阻、设置限流门限:ILIM=(200mV)/RSENSE(RSENSE 为检流电阻)     

An improved current mode logic latch for high‐speed applications

In this paper, an improved current mode logic (CML) latch design is proposed for high‐speed on‐chip applications. Transceivers use various methods in fast data transmission in wireless/wire‐line application. For an asynchronous transceiver, the improved CML latch is designed using additional NMOS transistors in conventional CML latch which helps to boost the output voltage swing. The proposed low‐power CML latch‐based frequency divider is compatible for higher operating frequency (16 GHz). Next, the delay model is also developed based on small signal equivalent circuit for the analysis of the proposed latch. The output voltage behavior of the proposed latch is analyzed using 180‐nm standard CMOS technology.     

一种集成24位YCbCr(8∶8∶8)硬件加速的LCD控制器

提出一种改进的用于移动多媒体SoC芯片的LCD控制器的设计,它以很低的芯片面积为代价集成了24位YCbCr(8:8:8)硬件加速模块,其色度格式为4:2:0,适用于实时嵌入式视频播放器.对于解码所得24位YCrCb且其色度格式为4:2:0的视频数据,以FPGA实验表明,用本硬件加速后的视频播放速度提高了6%～60%,同时保证了图像的质量.