Current Source Optimization in AC-DC GTO Thyristor Converters

A digital interface for a three-phase PWM ac-dc GTO converter is described, and a microprocessor-based firing scheme for the PWM control system is proposed. Two modulation strategies, equal pulsewidth modulation (EPWM) and sinusoidal pulsewidth modulation (SPWM), are implemented and their efficiencies of operation considered. Applied as the inner current loop in a dc motor controller with constant-gain proportional-plus-integral (PI) control, a fast response to step reference input changes is obtained. The theoretical responses using an approximate z-transform analysis are used to obtain optimum operational parameters.     

小功率整流控制器的控制策略仿真研究

对三相PWM整流器的控制系统采用了一种较为简单的数学方法来建模,对电压外环电流内环反馈控制算法进行了详细分析,并通过Maflab Simulink环境下进行了系统仿真,对各种扰动电压输出波形、电流内环d轴q轴电流波形以及电流的跟随性能进行了分析,验证了该系统建模、理论分析的有效性。     

Synthesis of zero-impedance converter

A method for synthesizing a system that converts a finite value of an impedance to zero, with an associated finite current and zero voltage, is presented. The synthesis method comprises positive current feedback of an exactly specified nature and value of its transfer function. The stability and dynamics of the system are controlled by an additional voltage loop. The zero-impedance converter is used to synthesize load-independent systems including (switch-mode) power converters and electric motor drive systems incorporating any kind of motor     

A new short-time high-overload BLDC driving system based on electronic flywheel and time-division switching control

Most of the existing (BLDCM) brushless dc motor drive systems are designed with the traditional drive scheme for long-time operation. For short-time and heavy-duty applications, there are problems of energy consumption, large volume, heavyweight and high-cost. In this paper, a new short-time high-overload BLDCM drive system based on "electronic flywheel" and time-division switching control is proposed, which includes three core contents: a crushing chamber based on combined cutter head, an energy storage device based on an "electronic flywheel" and high overload factor BLDC using a new calculation method of capacitance and a speed control system based on time-division switching control of the speed loop and the current loop. To prove the effectiveness of the proposed scheme, a kitchen garbage processor is developed and tested. The results show that the "electronic flywheel" energy storage driving device designed in this paper is able to provide most of the energy required in the heavy-duty driving process. The designed time-division switching control scheme can well meet the control requirements for the short-time heavy load drive of the kitchen waste processor. Compared with the traditional long-time rated load drive scheme, the proposed system has the advantages of energy-saving, small volume, lightweight and low-cost.     

Torque-ripple reduction in PM synchronous motor drives using repetitive current control

The paper deals with the torque-ripple reduction in a permanent magnet synchronous motor (PMSM) drive with distorted back electromotive force. A smooth torque is obtained by tracking a modified current reference which is periodic over one-sixth of the electrical time period in the synchronous reference frame. An accurate tracking involves, however, very high current loop bandwidth, which is usually not achievable with conventional linear controllers. In order to improve current tracking in the presence of periodic reference signals and disturbances, the paper proposes the application of repetitive techniques to the current control in a field-oriented PMSM drive, where the q-axis current reference has been modified to achieve constant torque. The paper investigates the advantages and pitfalls of the method, through a mathematical analysis and an experimental validation obtained on a laboratory prototype. Particular emphasis is placed on the adjustments that have been specifically studied to enhance the overall system performance.     

一种大功率低噪声的智能可调LED驱动设计方法

针对大型LED显示屏驱动中恒流源功率较小、调光不便捷,其开关特性导致的噪声大的问题,提出一种体积小,适用功率大且纹波效果较好的智能优化式恒流LED驱动设计方法。该设计在以往低电流的基础上进行改进,通过运放反馈调节将输出电流的开关特性转换为线性,辅以通断RCD回路(峰值吸收回路)和构建优化式大电流环式PCB布局,能进行光源检测的电流转脉宽式精准调光,输出能够较完善地抑制开关噪声。该设计方法能实现上位机网络远程数字调光,内、外部模拟调光,多路板载级联的智能控制。实验表明:该恒流驱动输出电流可达10A,功率可达370W,输出电流误差小于1%,驱动光源光功率稳定,光照分布均匀,具有较好的纹波效果,稳定可靠。     

Subscriber loop transmission using low operating current light emitting diodes subjected to temperature extremes

A unique edge-emitting LED has been developed that has characteristics particularly attractive for use in loop transmission equipment. At low operating currents of 20-25 mA, sufficient optical power is launched into a Single-mode fiber to transmit data rates typical of the present day loop plant, 1.5-45 Mbit/s. In the system experiments reported here, 45-Mbit/s data was transmitted 12.9 km while operating the LED at a low drive current of 20-mA peak and at temperatures from -20 to +70°C. These experiments and related analyses confirm that the LED offers a reliable, low cost, and easy to use alternative to diode lasers and high drive current LED's in the telephone loop plant.     

Sensorless current mode control-an observer-based technique forDC-DC converters

Sensorless current mode (SCM) control is an observer method that provides the operating benefits of current mode control without current sensing. SCM has significant advantages over both conventional peak and average current-mode control techniques in noise susceptibility and dynamic range in both continuous mode and discontinuous mode. The method supports line and bulk load regulation, and reduces control complexity to a single loop. It also supports conventional two-loop control for tight load regulation. Encompassing one-cycle control as a special case, the general SCM method is a public domain control technique     

A novel vector control scheme for transistor PWM inverter-fedinduction motor drive

A novel vector control scheme for a transistor pulse-width-modulation (PWM)-inverter-fed induction motor drive is presented. The system is based on a current control loop that consists of two independent nonlinear controllers that regulate the DC (field-oriented) components of the stator current vector. Three-level hysteresis comparators are used as current controllers. The outputs of the comparators select the appropriate inverter output voltage vectors via a switching erasable programmable ROM (EPROM) table. The theoretical principle of this method is discussed. Simulation and experimental results that illustrate the operation of the proposed system and performance in comparison with the other known schemes based on two-level hysteresis comparators are presented     

减重支持系统的实现

介绍了康复机器人减重支持系统的构成。利用直线执行器作为支持系统的主要部件,采用H桥驱动直线执行器。利用双闭环反馈控制作为该系统的控制器,其中电流控制器作为内环控制器,速度反馈控制器作为外环控制器,并均采用PID控制器来实现,PID参数采用遗传算法进行整定。同时,利用延迟采样的策略保证了电流控制器参数的正确性。从实际效果上看,双闭环反馈控制基本使减重支持系统达到了恒力输出的要求。     

Optimal soft starting of voltage-controller-fed IM drive based onvoltage across thyristor

AC voltage controllers are used as induction motor starters in fan or pump drives and the crane hoist drives. This paper presents a method of identifying the end of soft start of an AC voltage controller-fed induction motor (IM) drive based on the voltage across the nonconducting thyristor through a dynamic simulation of the whole drive system. A two point current minimization technique is adopted to operate the drive system at the required optimal voltage under all operating conditions. This minimizes the motor losses. Graphic modeling of the whole drive system is done in a modular format using Design Star and dynamic simulation is done using SABER. The dynamic simulation results of the whole drive system are supported with experimental data     

Robust High Bandwidth Discrete-Time Predictive Current Control with Predictive Internal Model—A Unified Approach for Voltage-Source PWM Converters

This paper presents a robust high bandwidth discrete-time predictive current control scheme for voltage-source pulsewidth-modulated (VS-PWM) converters. First, to achieve high bandwidth current control characteristics, a digital predictive current controller with delay compensation is adopted. The compensation method utilizes a current observer with an adaptive internal model for system uncertainties. The predictive nature of both the current observer and the internal model forces the delays elements to be equivalently placed outside the closed loop system. Second, to ensure perfect tracking of the output current in the presence of uncertainties and providing means for attenuating low- and high- frequency system disturbances, the frequency modes of the disturbances to be eliminated should be included in the stable closed loop system. Toward this, an adaptive internal model for the estimated uncertainty dynamics is proposed. To cope with the high bandwidth property of the lump of uncertainties in VS-PWM converter applications, the disturbance slowly varying assumption is relaxed in the proposed controller. The relaxation is achieved by adopting a curbing sliding-mode-based feedback gain vector within the internal model observation system. Comparative evaluation tests were carried out on a grid-connected VS-PWM converter and a direct drive permanent magnet synchronous motor (DD-PMSM) drive system to demonstrate the validity and effectiveness of the proposed control scheme at different operating conditions.     

4～20mA电流环串行通信接口抗干扰研究

介绍了基于4²0 mA电流环串行通信接口的基本原理,创新的使用PCI转UART桥芯片实现了基于CPCI总线的420 mA电流环串行通信接口的基本原理,创新的使用PCI转UART桥芯片实现了基于CPCI总线的4²0 mA电流环串口卡,并给出了某地面测试系统中电流环接口的干扰源及其抗干扰分析。通过改进接收端施密特触发器电路,降低了输出高电平的幅值,减小了系统中干扰信号的尖峰,有效地抑制了噪声;同时,通过选取最佳的负载电阻,提高了光耦饱和度,增强了输出驱动能力。经测试,按这种方法改进后的420 mA电流环串口卡,并给出了某地面测试系统中电流环接口的干扰源及其抗干扰分析。通过改进接收端施密特触发器电路,降低了输出高电平的幅值,减小了系统中干扰信号的尖峰,有效地抑制了噪声;同时,通过选取最佳的负载电阻,提高了光耦饱和度,增强了输出驱动能力。经测试,按这种方法改进后的4²0 mA电流环串行接口电路较好地抑制了通信线束中的电磁串扰,提升了抗干扰能力。     

State-space models and order reduction for DC-DC switchingconverters in discontinuous modes

The state-space modeling and related order reduction problems of switching DC-DC converters operating in discontinuous (D) mode are treated in this paper. A unified discrete-time full-order model is proposed assuming the discontinuous current and voltage mode (DCVM) as a general operation mode from which the discontinuous current mode (DCM), the discontinuous voltage mode (DVM), and continuous made (CM) derive as special cases. Such a model permits a straightforward study of the control-to-output response, in each operation mode. The order reduction of the transfer function is carried out by means of the principal component analysis considering the joint controllability and observability properties of the circuit. It is shown that a proper order reduction can be gained not only in DC mode, as expected, but also in DV and DCV modes. A substantial difference between DC and DV modes is also evidenced in terms of controllability. The frequency analysis and state-space model order reduction for a Cuk converter are proposed to show that the method is free of the limitations affecting other methods of analysis and that its predictions fit experimental measurements     

一种全数字控制的工业激光器驱动电源

介绍了一种全数字控制半导体激光器驱动电源方案.方案采用高速数字信号处理器产生高频率高分辨率的数字调制PWM直接驱动功率回路,完全采用软件实现闭环的控制,结合高精度AD采样,使得输出电流具有高精度、低纹波和高动态响应速度的特点.系统还提供六种保护功能,具有故障锁定及故障自诊断功能,具有数字化的远程通讯接口.     

小角度摆动扫描控制系统的分析与实现

激光测距仪对摆动扫描控制系统提出了特殊的要求(摆动幅度为±0.125°,摆动频率为2～8 Hz)。在对系统进行建模与仿真分析的基础上,针对其中存在光栅码盘位置检测精度低、电机驱动电流小、易受外界干扰等问题,提出了一种新的工程实现方法。首先采用有限转角无刷直流力矩电机作为执行元件和挠性枢轴连接,可以减小力矩波动和机械摩擦;然后通过电学细分的方法提高光栅的分辨率;最后采用电流反馈和速度反馈相结合的PID控制策略提高系统的性能。试验结果表明：此方法可以满足摆动扫描控制系统对低转速、小角度、高精度控制的要求。     

Precise phase control of resonant MOEMS mirrors by comb-drive current feedback

Accurate phase detection and control of nonlinear resonant micro-opto-electro-mechanical system (MOEMS) mirrors are crucial to achieve stable scanning motions and high resolution imaging as needed in precision applications. This paper proposes a precise phase detection method for an electrostatic actuated MOEMS mirror and a novel digital phase locked loop (PLL) that uses an asynchronous logic for high precision driving and immediate phase compensation, while the clock speed is kept low. The phase of the mirror is detected by an amplified current signal, generated by the movement of the comb drive electrodes, transimpedance amplifiers and a simple comparator circuit. An analysis of the proposed detection method reveals that the pointing uncertainty scales with the product of the driving voltage, the curvature of the comb drive capacitance and the angular velocity of the MOEMS mirror at the zero crossing. The developed fast start-up procedure brings the MOEMS mirror to its maximum amplitude within less than 100 ms with a minimum on required prior knowledge of the used device. The low optical pointing uncertainty of 0.3 mdeg obtained in closed loop operation, allows 19000 pixels with a precision of 10 sigma at a scanning frequency of 2 kHz.     

Modeling adjustable-speed drives with long feeders

This paper presents the modeling of different topologies of electric drive systems when the cable that connects the converter to the motor has a significant length. The long feeder together with converter harmonics decrease the performance of the motor. To correctly assess the voltage and the current throughout the drive system, frequency-dependent models for the cable and the motor should be used. A frequency-dependent cable model is necessary for an accurate voltage evaluation while a frequency-dependent motor model responds for accuracy in the current. The models were validated through experimental results carried out on an actual oil platform and from a prototype system. The latter system was used to test the system's performance when very long motor leads (longer than 5 km) are involved     

A new, continuous-time model for current-mode control [powerconvertors]

A current-mode control power convertor model that is accurate at frequencies from DC to half the switching frequency is described for constant-frequency operation. Using a simple pole-zero transfer function, the model is able to predict subharmonic oscillation without the need for discrete-time z-transform models. The accuracy of sampled-data modeling is incorporated into the model by a second-order representation of the sampled-data transfer function which is valid up to half the switching frequency. Predictions of current loop gain; control-to-output; output impedance; and audio susceptibility transfer functions were confirmed with measurements on a buck converter. The audio susceptibility of the buck converter can be nulled with the appropriate value of external ramp. The modeling concentrates on constant-frequency pulse-width modulation (PWM) converters, but the methods can be applied to variable-frequency control and discontinuous conduction mode     

高性能双向DC-DC变换器设计

设计一种由单片机控制的高性能双向DC-DC变换器,摒弃传统变换器升降压电路分开设计的思想,采用升降压为一体的拓扑结构,以5节锂电池为研究背景进行设计。主控芯片采用STC12C5A60S2型单片机,选择带自举功能的半桥驱动器IR2104对MOSFET进行增强型驱动,实现稳定开通与关断。系统可对充、放电的电流与电压进行实时采集和显示,并可通过按键对回路电流进行控制。系统总体结构简单,易于控制,采用同步整流大大提高变换效率,且成本低。样机测试中,电流波动小,电压稳定性高,应用于实验室的小型直流电机驱动电路中,运行效果良好。