Optimization of block-floating-point realizations for digital controllers with finite-word-length considerations

The closed-loop stability issue of finite-precision realizations was investigated for digital control-lers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resultingfrom using finite word length (FWL) block-floating-point representation scheme. A block-floating-point FWL closed-loop stability measure was derived which considers both the dynamic range and precision. To facilitate the design of optimal finite-precision controller realizations, a computationally tractable block-floating-point FWL closed-loop stability measure was then introduced and the method of computing the value of this measure for a given controller realization was developed. The optimal controller realization is defined as the solution that maximizes the corresponding measure, and a numerical optimization approach was adopted to solve the resulting optimal realization problem. A numerical example was used to illustrate the design procedure and to compare the optimal controller realization with the initial realization.

Digital close loop control system for current-programmed mode arc welding inverter

A small-signal model of current programmed mode pulse width modulation converter including the equivalent sampling effect is introduced and analyzed. In this model, an addition pole is brought out by the sampling effect in the current loop gain, and it affects dynamic bandwidth and stability of the inner current loop. By selecting the appropriate stability parameter which determines the additional pole and describes the degree of peaking in closed loop transfer function, a control model of current programmed full bridge arc welding inverter with maximum frequency bandwidth and stability can be obtained. Small and large amplitude pulse current outputs are employed in simulations and experiments and results validate the design method.

A multimode digital controller IC for flyback converter with high accuracy primary-side feedback

A digital controller IC for the flyback converter with primary-side feedback is proposed. The controller is used for adapter charger or LED driver applications. To obtain high accuracy for the primary-side feedback, a digital primary-side sensing technology is adopted, which can auto-track the knee point of the primary auxiliary winding voltage. Furthermore, an internal digital compensator eliminates the need for external loop compensation components while achieving excellent line and load regulation. The controller could output both constant voltage and constant current depending on the load current. Pulse width modulation and pulse frequency modulation are used in constant voltage mode while quasi-resonant control is used in constant current mode. The digital controller is validated by using FPGA.

Current Loop Disturbance Suppression for Dual Three Phase Permanent Magnet Synchronous Generators Based on Modified Linear Active Disturbance Rejection Control

A modified four-dimensional linear active disturbance rejection control(LADRC)strategy is proposed for a dual three-phase permanent magnet synchronous generator(DTP-PMSG)system to reduce cross-coupling between the d and q axis currents in the d-q subspace and harmonic currents in the x-y subspace.In the d-q subspace,the proposed strategy uses a model-based LADRC to enhance the decoupling effect between the d and q axes and the disturbance rejection ability against parameter variation.In the x-y subspace,the 5th and 7th harmonic current suppression abilities are improved by using quasi-resonant units parallel to the extended state observer of the traditional LADRC.The proposed modified LADRC strategy improved both the steady-state performance and dynamic response of the DTP-PMSG system.The experimental results demonstrate that the proposed strategy is both feasible and effective.

Analysis and design of DSP-based dual-loop controlled UPS inverters

This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.

Lateral Dynamic Analysis and Motion Control of a Jet Trencher in Ocean Currents

In order to control the lateral motion of a jet trencher which is important for stable trenching operation,the oscillation characteristics of the jet trencher are researched. The jet trencher is simplified into a single degree of freedom model with restoring and damping force. The nonlinear mathematical model of the trencher laterally oscillating in ocean currents is established,and its approximate analytical solution is obtained.Results show that the analytical solution has small differences with numerical solution based on the fourth-order Runge-Kutta method and can effectively describe the underwater oscillation. A double-loop PID controller is designed to control the lateral motion displacement of the trencher to return to the center of the pipeline route which is effective and robust for the propulsion system.

THE DESIGN OF AN ALL-DIGITAL PHASE-LOCKED LOOP WITH LOW JITTER BASED ON ISF ANALYSIS

A low jitter All-Digital Phase-Locked Loop(ADPLL) used as a clock generator is designed.The Digital-Controlled Oscillator(DCO) for this ADPLL is a seven-stage ring oscillator with the delay of each stage changeable.Based on the Impulse Sensitivity Function(ISF) analysis,an effective way is proposed to reduce the ADPLL's jitter by the careful design of the sizes of the inverters used in the DCO with a simple architecture other than a complex one.The ADPLL is implemented in a 0.18μm CMOS process with 1.8V supply voltage,occupies 0.046mm2 of on-chip area.According to the measured results,the ADPLL can operate from 108MHz to 304MHz,and the peak-to-peak jitter is 139ps when the DCO's output frequency is 188MHz.

Loop-Shaping Based Control for Switch Mode DC-DC Power Converters

Renewable energy sources require switching regulators as an interface to a load with high efficiency, small size, proper output regulation, and fast transient response. Moreover, due to the nonlinear behavior and switching nature of DC-DC power electronic converters, there is a need for high-performance control strategies. This work summarized the dynamic behavior for the three basic switch-mode DC-DC power converters operating in continuous conduction mode, i.e. buck, boost, and buck-boost. A controller was designed using loop-shaping based on current-mode control that consists of two feedback loops. A high-gain compensator with wide bandwidth was used in the inner current loop for fast transient response. A proportional-integral controller was used in the outer voltage loop for regulation purposes. A procedure was proposed for the parameters of the controller that ensures closed-loop stability and output voltage regulation. The design-oriented analysis was applied to the three basic switch-mode DC-DC power converters. Experimental results were obtained for a switching regulator with a boost converter of 150 W, which exhibits non-minimum phase behavior. The performance of the controller was tested for voltage regulation by applying large load changes.

某型地面发控点火电流异常分析和电路改进

针对某型地面发控系统在使用过程中出现的点火电流异常问题,采用数学方法研究点火电流与元器件参数的变化规律,发现地面发控点火电流在某些环境下不稳定的根本原因。最后提出一种闭环控制方案,增加电流反馈环节,解决点火电流异常问题。实际应用验证表明,改进后的点火电路能适应更大的点火负载,有效提高了点火的可靠性。

基于大创项目的应用技术开发实践——以数字电源教具设计为例

针对教学环节中的难点和重点内容,基于dsPIC33CK256MP505数字信号控制器芯片,为开发新型的数字电源教具,在降压转换器的电路拓扑结构基础上,利用MplabPowerSmart开发软件,完成了电压控制型数字环路补偿器的设计,实现3P3Z数字补偿器的实时算法功能。

正负脉冲电压驱动的电磁螺纹插装阀动态特性分析

提出了一种基于PWM技术的正负脉冲电压控制策略,用于提高锥阀式电磁螺纹插装阀启闭动态响应速度,使其满足数字液压技术的要求。在分析电磁螺纹插装阀结构和工作原理基础上,建立了电磁螺纹插装阀的数学模型,并在AMESim软件中搭建电磁螺纹插装阀及其测试系统的多物理场耦合建模,研究不同正负脉冲电压持续时间条件下电磁螺纹插装阀线圈电流、阀芯位移、电磁力的变化规律,确定了电磁螺纹插装阀响应速度最快时正负脉冲电压控制策略的最优控制参数。利用半实物仿真系统搭建SCV硬件在环测试实验台,对所提正负脉冲控制策略进行验证。实验表明,与常规电压控制策略相比,当正负脉冲电压控制策略中正负脉冲电压持续时间都为10 ms时,电磁螺纹插装阀的开启时间由30 ms缩短到13.5 ms,其关闭时间由139 ms缩短到14 ms。研究结果为电磁螺纹插装阀的高响应化和数字液压技术的发展提供参考。

抑制采样白噪声干扰的PWM整流器无差拍控制

无差拍控制(DBC)是一种应用于整流器电流内环的预测控制,但该算法对系统参数敏感,当采样受到持续噪声干扰时波形畸变严重。为此,此处提出了一种基于DBC的白噪声抑制算法,实验结果表明,该算法在较大电感参数偏差下能保持稳定,在白噪声干扰下能够显著降低电流畸变率。

双闭环控制的三相电压型PWM整流器的研究

针对传统的不控整流电路中网侧电流谐波很大、晶闸管相控整流电路中深控时网侧功率因数低和闭环控制时动态响应慢等问题,设计出一种引入脉冲宽度调制技术的三相电压型整流器。在完成三相电压型整流器的电压外环电流内环的双闭环控制系统设计的基础上,对其进行了仿真实验。仿真结果表明,与不控或相控整流电路相比,该三相电压型PWM整流电路中,不仅输入电流的谐波大大减小,电能可双向流动,能够实现整流和逆变状态下的单位功率因数运行,还可较好地抑制负载突变时直流侧电压的波动,从而显著提高系统的抗扰能力,真正实现绿色环保和高效节能的高度结合。

面向悬浮光力系统的集成化反馈控制器研究

悬浮光力系统具有高灵敏度、高稳定性和低耗散等特点,有望发展成为新型高性能力学传感器。针对目前悬浮光力系统存在的反馈控制器兼容性差、软硬件成本高、集成度低等问题,提出了一种兼容多种反馈控制模式的软硬件设计方案,并研制了一套高度集成的反馈控制器,在160 mm×170 mm×42 mm的尺寸上集成了六通道模数/数模转换器、滤波器、现场可编程门阵列+微处理器(FPGA+ARM)等功能模块,并且开发了基于数字锁相环和比例积分微分(PID)控制器的控制算法,最终在同一套硬件系统上实现了跨尺度微粒的运动信息采集和反馈控制,以及数十赫兹至亚兆赫兹的感知带宽。实验结果表明,该集成反馈控制器能够实现超高真空(10-6 Pa量级)下亚微米及微米尺度微粒的稳定悬浮和运动控制。在扩展系统感知带宽的同时减小了整体体积,为悬浮光力传感技术的器件化奠定了基础。

基于Kent映射的数字集群动态负载均衡算法研究

由于动态负载均衡是保证数字集群系统正常运行中不可缺少的环节,但其在控制过程中存在易受通信故障等因素的干扰问题,为此提出基于Kent映射的数字集群动态负载均衡算法。通过基于云平台的虚拟机系统采集数字集群的节点连接数、响应时间、动态负载等信息,分析数字集群系统的负载情况。其次构建数字集群资源利用率模型,通过基于Kent映射的灰狼算法对模型求解得到数字集群的资源利用率。最后将资源利用率输入LQR(Linear Quadratic Regulator)控制回路器中,通过控制服务器的迁移实现数字集群的动态负载均衡。实验结果表明,所提算法处理后的数字集群响应时间短、适应度值大、容错能力强。

永磁无刷轮毂电机轮对系统同步工况下的协调控制策略

针对双轮毂电机在负载不平衡工况下转速同步精度不够及同步响应速度不快的问题,该文提出速度环补偿PID交叉耦合同步控制和电流环补偿PID交叉耦合同步控制策略。首先,建立双轮毂电机的数学模型,采用双闭环六步方波控制。基于该模型,采用速度环补偿PID交叉耦合同步控制代替单增益交叉耦合控制器,使转速同步调节精度提升。在两侧电机负载不平衡工况下,用电流环补偿PID交叉耦合控制方法进一步提升转速同步精度,同时加快同步响应速度,并兼顾了转矩精度。仿真和实验验证了所提控制策略的正确性和有效性。

基于频域分析的PMSM双闭环PI控制器整定方法

以永磁同步电机(PMSM)双闭环调速系统为对象,在对其数学模型进行合理简化的基础上,综合考虑了逆变器开关周期、电流和速度滤波等环节的影响,给出了一种在频域进行PI控制器参数设计的整定方法。通过建立双环的数学模型,得到关于开环频域特征量的解析式,根据电流环在中低频段的特性以及转速环中阻尼系数难以精确测定的问题,分析推导了电流环和转速环PI参数简化设计的方法。利用工程经验将闭环时域指标转化开环频域特征量,并结合各类约束条件合理界定其取值范围,由此得到的PI控制器可以兼顾快速性和稳态跟踪能力。仿真和实物实验验证了整定方法的可行性,该方法确立了双环控制器参数与其对应的开环截止频率和相位裕度的解析式,并明确了开环频域特征量与闭环时域指标的关系,具有较强的工程参考和应用价值。

高响应交流永磁伺服系统快速电流环带宽扩展方法

交流永磁伺服控制系统中现有电流采样和脉冲宽度调制(Pulse width modulation,PWM)占空比更新的方法延迟时间较长,在一定程度上会影响电机的电流环带宽和动态特性;针对该问题,建立了电流环闭环系统数学模型,分析了电流环的内部延迟和影响电流环带宽的因素,在此基础上提出了一种通过改进电流采样与PWM更新时间的电流环带宽扩展方法。该方法通过提前PWM占空比更新时机来降低电流采样和PWM占空比更新之间的延迟,减小信号传输滞后,从而扩展电流环系统的闭环带宽,提高系统响应速度。仿真与实验结果表明,相比现有电流采样方法,采用新方法的交流永磁伺服控制系统的电流环具有更宽的带宽和更高的动态响应能力,从而提高了交流伺服系统的动态响应能力和稳态精度。该方法可为交流伺服系统在机器人、高端智能装备等对响应速度和定位精度要求较高领域的应用提供参考。

非线性环路补偿的交错并联BUCK变换器数字控制策略研究

针对氢能燃料电池输出低电压、大电流,不能适用通讯基站电源的问题,设计了一种电力电子交错并联BUCK变换器,同时提出了一种非线性环路补偿的数字控制策略。文中采用两个BUCK电路并联,控制信号为180°两相交错脉冲宽度控制,采用小信号模型建立了电压环、电流环数学模型,控制策略采用电流内环、电压外环双闭环控制。为了控制快准稳,分别对两环路控制策略补偿校正设计,通过环路补偿数字控制策略搭建交错并联BUCK变换器simulink模型,仿真结果表明变换器在输入范围下实现了48 V直流稳定输出,验证了本研究的有效性。

变母线电压的LLC高压电容充电电源设计

提出了一种两级式可变母线电压的高压电容充电电源技术方案,该拓扑在半桥LLC谐振电路的基础上增加了一级图腾柱无桥功率因数校正(PFC)电路,通过改变母线电压来解决传统LLC谐振电源在输出更高电压时,工作频率变化范围过大带来的充电效率下滑的问题。由于图腾柱电路本身具备功率因数校正的功能,该电源设计还拥有能够直接从电网取电而不影响电网电能质量的优势。首先介绍了本电源设计中两部分的电路拓扑和工作原理,采用等效电阻法分析了电容负载下的电源输出特性。针对前级图腾柱电路设计了双环控制器以实现对母线电压和功率因数的控制,针对后级LLC电路提出了比例积分(PI)加低通滤波的恒流控制器以降低高频噪声带来的不利影响。最后通过模型构建与仿真分析,研究了高压电容充电电源3000 V/1 A时的充电特性,验证了本电源技术方案、设计和控制策略的可行性。