An Adaptive Slope Compensation Circuit for Peak Current Mode of Boost Switching Power Supply

Based on the analysis of the basic principle of slope compensation, a high-precision adaptive slope compensation circuit for peak current mode boost DC/DC converter is designed. The circuit dynamically detects the input and output voltage of the boost circuit to realize automatic adjustment of the compensation amount with the change of duty ratio, which makes the ramp compensation slope optimized. The design uses a high-precision subtracter to improve the accuracy of slope compensation. While eliminating sub-slope oscillation and improving the stability of boost circuit, the negative impact of compensation on boost circuit is minimized, and the load capacity and transient response speed of boost circuit are guaranteed. The circuit is designed based on SMIC 0.18um CMOS technology, with simple structure, high reliability and easy engineering implementation. Spectre circuit simulator 17.1.0.124 64b simulation results show that the circuit has high compensation accuracy and wide input and output voltage range. When the working voltage is 3.3 V, the compensation slope can be adjusted adaptively under different duty cycles, and the minimum error between the compensation slope and the theoretical optimal compensation slope is only 0.42%.

Residual current compensation for single-phase grounding fault in coal mine power network

The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.

Current Polarity Detection and Current Compensation Strategy for PAC Based Three-Phase ZVS PWM Converter

A novel software implementation for current polarity detection and current compensation is presented. For a three-phase zero-voltage soft-switching （ZVS） PWM converter based on phase and amplitude control （PAC）, when saw-tooth carriers with alternate positive and negative slopes are adopted, the positive or negative slopes are chosen according to the phase current polarity. Since polarity reversal causes current distortion, current at the instant of reversal should be compensated for. Based on the characteristic of unity power factor converter in rectification and regeneration modes, a software implementation for current polarity detection is proposed. Distortion of current zero-crossing caused by using saw-tooth carriers with alternate positive and negative slopes is analyzed, and the relevant compensation method is proposed. Experimental study with a 1.5 kW device shows that phase current has a small harmonic content and power factor is high both in rectification and regeneration modes.

Research on a Fast-Closing Switch Based Fault Current Limiter with Series Compensation

A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors, and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.

Adaptive current compensation with nonlinear disturbance observer for single-sided linear induction motor considering dynamic eddy-effect

An adaptive current compensation control for a single-sided linear induction motor(SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideration of the specially dynamic eddy-effect(DEE) of the SLIM, a instantaneously tracing compensation of m-axis current component was analyzed. Second,adaptive current compensation based on Taylor-discretization algorithm was proposed. Third, an effective kind of nonlinear disturbance observer(NDOB) was employed to estimate and compensate the undesired load vibrations, then the robustness of the control system could be guaranteed. Experimental verification of the feasibility of the proposed method for an SLIM control system was performed, and it showed that the proposed adaptive compensation scheme with NDOB could significantly promote speed dynamical response and minimize speed ripple under the conditions of external load coupled vibrations and unavoidable feedback control variables measured errors, i.e., current and speed.

Symmetric Temperature Compensation for Photoelectric Coupling Current Transducer

The temperature characteristic of sensor probe at high voltage side is analyzed by using a photoelectric coupling current transducer. The principle of symmetric temperature compensation and the main idea of software design are proposed. The method increases measuring precision and has fairly great practicability.

A New CMOS Current Reference with High Order Temperature Compensation

A new high order CMOS temperature compensated current reference is proposed in this paper, which is accomplished by two first order temperature compensation current references. The novel circuit exploits the temperature characteristics of integrated-circuit resistors and gate-source voltage of MOS transistors working in weak inversion. The proposed circuit, designed with a 0.6 Izm standard CMOS technology, gives a good temperature coefficient of 31ppm/℃ [-50-100℃] at a 1.8V supply, and also achieves line regulation of 0.01%/V and-120dB PSR at 1 MHz. Comparing with other presented work, the proposed circuit shows better temperature coefficient and Line regulation.

An Adaptive Response Compensation Technique for the Constant-Current Hot-Wire Anemometer

An adaptive response compensation technique has been proposed to compensate for the response lag of the constant-current hot-wire anemometer (CCA) by taking advantage of digital signal processing technology. First, we have developed a simple response compensation scheme based on a precise theoretical expression for the frequency response of the CCA (Kaifuku et al. 2010, 2011), and verified its effectiveness experimentally for hot-wires of 5 μm, 10 μm and 20 μm in diameter. Then, another novel technique based on a two-sensor probe technique—originally developed for the response compensation of fine-wire thermocouples (Tagawa and Ohta 1997;Tagawa et al. 1998)—has been proposed for estimating thermal time-constants of hot-wires to realize the in-situ response compensation of the CCA. To demonstrate the usefulness of the CCA, we have applied the response compensation schemes to multipoint velocity measure- ment of a turbulent wake flow formed behind a circular cylinder by using a CCA probe consisting of 16 hot-wires, which were driven simultaneously by a very simple constant-current circuit. As a result, the proposed response compensation techniques for the CCA work quite successfully and are capable of improving the response speed of the CCA to obtain reliable measurements comparable to those by the commercially-available constant-temperature hot-wire anemometer (CTA).

A New 1-V Second-Order Temperature-Compensated Current Reference

A new bipolar temperature-compensated current reference is proposed. The first-order temperature compensation is achieved by the idea of self temperature-compensation configuration exploiting the temperature coefficient of a combined resistor. The second-order compensation employs a VBE-tracking thermal-startup technique to obtain improved temperature performance. The proposed circuit can operate down to a 1-V supply. A temperature coefficient of 46.6×10?6/℃ [0, 100℃] at a 1-V supply and a supply regulation of 0.036%/V at 25℃ are achieved. Compared with present works, the proposed circuit shows better results of the temperature coefficient and supply regulation. The current matching issue frequently encountered in current references is also discussed in detail.

基于双补偿下垂—MQPR的直驱式风电机组并网控制

为了实现直驱式永磁风力发电系统安全稳定并网,提出一种基于双补偿下垂与多重准比例谐振(multiple quasi proportional resonance,MQPR)相结合的并网控制策略。该策略源于传统下垂控制,在电压控制环节引入直流电压补偿量,能快速调节直流母线电压达到稳定;在电流控制环节引入电容电流补偿量,能有效减小滤波电容造成的电流误差影响;同时,设计出MQPR控制器替代内环电流的PI控制器,可以滤除系统中多次谐波电流。通过建立仿真模型,与双闭环PI和传统下垂控制策略进行对比,验证所提控制策略的有效性。

一种新型带曲率补偿的带隙基准

针对传统带隙基准存在温度漂移大以及电源抑制比低的问题,提出了一种新型的带曲率补偿的带隙基准电压源。采用基极电流补偿以及曲率补偿技术对传统带隙基准结构进行改进。设计了低失配改进电路、低温漂改进以及启动电路等。利用共源共栅电流镜技术和负反馈网络保证带隙基准输出电压,极大程度降低了运放失调电压对带隙基准电压的干扰,实现了低温漂特性。基于东部高科0.18μm BCD工艺,在Cadence Spectre下进行仿真。仿真结果表明:该带隙基准电路在-40~150℃温度范围内,输入电压为5 V,输出电压稳定在1.192 V;温度系数为4.84×10^(-6)/℃;在低频时电源抑制比为-78 dB。

中国公益林生态补偿制度的历史演进、现实困境与路径探索

梳理中国公益林生态补偿制度的历史演进与实践探索,分析公益林生态补偿制度的现实困境,并提出提升路径的政策建议。结果表明:从历史演进来看,中国公益林生态补偿制度分为起始阶段、探索阶段、推广阶段和深化阶段;从实践来看,公益林生态补偿制度历经了补偿标准调整、分类补偿推广、市场化和多元化生态补偿制度探索;从现实困境来看,公益林生态补偿制度仍存在补偿标准较低、补偿标准单一、补偿资金筹集渠道偏窄、自身造血能力弱等现实困境。应从动态调整补偿标准、分类补偿探索、多元化补偿筹资渠道以及公益林自身经营管理等方向深化改革探索。

基于限流电抗器电压的直流配电网单端量保护

直流配电网故障特性复杂,故障电流上升速度快且峰值大,快速、灵敏的故障识别与线路保护是保障直流配电网安全运行的关键技术之一。为此,针对增设限流电抗器的直流配电网,提出一种利用限流电抗器电压实现高灵敏故障识别的直流配电网单端量保护方案。首先,通过分析含限流电抗器的直流配电网故障特性,明确区内、区外故障时限流电抗器电压的特征差异。其次,研究限流电抗器对故障特性及直流保护的影响机制,提出虚拟补偿策略以增强故障识别的灵敏性。在此基础上,根据线路电压变化率设计保护启动判据,提出基于虚拟补偿的故障识别判据和故障选极判据,并给出完整的保护方案流程。最后,基于PSCAD/EMTDC仿真平台进行大量的仿真测试,结果表明所提保护方案能够实现对直流故障的快速准确判断,无需通信支持,且对过渡电阻、噪声及负荷波动具有较强的耐受能力。

两桥臂交叉解耦不平衡控制策略研究

由于非不平衡控制策略中没有考虑线电压和相电流的相角差,造成三相电网的有功、无功电流无法完全补偿。为了解决这一问题,根据电压电流相角差,推导出单相补偿器中无功参考补偿电流与负载电流的关系,提出一种两桥臂交叉解耦不平衡控制策略,利用多变量滤波器和交叉解耦双复系数滤波器优化锁相环,精确锁定三相不平衡电网的电压频率和相位,对2个单相背靠背变换器的无功电流分别控制,进而利用两桥臂变换器补偿三相不平衡无功。实验结果验证了所提两桥臂交叉解耦不平衡控制策略,可抑制三相有功不平衡及补偿三相不平衡无功,将三相电流的不平衡度从150.0%降低至2.6%,三相电网功率因数从0.257提升至0.997,减少了三相无功补偿器的开关管个数。

考虑MAF延时和前馈补偿的高压直流快速锁相环

同步参考坐标系锁相环是高压直流(high voltage direct current,HVDC)同步触发控制系统中广泛应用的一种窄带宽锁相环,在交流系统故障引起相位跳变情况下,其动态响应缓慢。为增大锁相环的带宽,一种滑动平均滤波器(moving average filter,MAF)被前置于锁相环路,然而MAF本身存在响应延迟,制约了锁相环的同步速度。为了缓解响应延迟问题,文中提出一种考虑MAF延时和前馈补偿的HVDC快速锁相环。首先,利用MAF线性暂态特征预测相位变化,并分别针对故障接入和切除引起的相位跳变问题提出不同的补偿策略;接着,利用不变性原理对锁相环路进行前馈补偿,在负反馈控制和前馈补偿共同构成的复合校正控制系统的作用下,锁相环能够在较小PI参数下实现快速响应;最后,将所提快速锁相环在CIGRE HVDC标准模型和三峡—上海直流工程模型中进行仿真验证。结果表明,该快速锁相环能够有效缓解滤波器响应延迟的制约,缩短失锁时间,进而提高高压直流逆变侧抵御换相失败的能力。

带自适应谐波补偿功能的谐波阻抗控制策略

针对工业园区高比例电力电子负荷接入带来的电能质量问题,提出一种基于APF的带自适应谐波补偿限流功能的谐波阻抗控制策略。谐波阻抗控制策略可以对系统的指令电流进行无差控制并对各谐波分量进行独立控制,自适应谐波补偿限流可以有针对性地进行谐波补偿,两者相结合后可以对选取的各谐波分量进行单独控制,使限流后的谐波补偿效果明显提高。该控制策略在系统容量不超限时在Matlab/Simulink中搭建仿真模型,结果表明,该控制策略响应速度快,治理后的谐波总畸变率为2.91%,减少了27.08%,三相不平衡度为8.52%,减少了16.15%,补偿效果明显。

电网电压三相不平衡时FMSS正负序电流补偿型VSG控制

柔性多状态开关(FMSS)是一种取代传统联络开关应用于现代配电网的新型电力电子设备,能够优化现代配电网分布式电源的消纳和调控。和传统控制算法相比,采用VSG控制的FMSS不受弱电网环境下锁相环性能恶化的影响,在低电网强度下能够向电网提供频率支撑,从而增强系统的稳定性。FMSS作为接入配电网的装置,当电网电压发生三相不平衡现象时,传统VSG控制下的FMSS输出电流、功率会发生明显的波动,并网点的效率会大大降低。针对此问题,以模块化多电平变流器(MMC)结构为基础,在VSG控制策略的基础上引入正负序电流补偿,分别实现不平衡电网下FMSS输出电流、有功功率及无功功率的稳定。最后,通过Matlab/Simulink搭建四端FMSS模型,利用仿真验证所提控制策略的有效性。

基于单相双旋转移相变压器的高速铁路系统负序补偿方法

针对高速铁路供电系统在高压电网引起的负序问题,该文参考旋转潮流控制器(RPFC)和静止无功补偿器(SVG)结构,提出一种基于单相双旋转移相变压器(S-DRPST)的新型负序补偿拓扑。首先,分析S-DRPST的工作原理并建立其稳态电压源模型。其次,在V/x牵引供电系统应用场景下,提出S-DRPST的负序电流补偿方法,即根据供电臂负载功率计算所需补偿电流表达式,进而得到两台S-DRPST输出电压幅值与相位,通过调节移相角大小实现电网侧电流的平衡。在此基础上,对单台S-DRPST移相角控制进行设计,补偿设备投入前利用柔性合环减小对牵引网的冲击,投入后采取移相角协调变速控制,使得移相角在接近设定值时降低转速,同时根据角度偏差协调转速控制,从而抑制输出电压振荡现象。最后,利用Matlab/Simulink软件搭建牵引供电系统进行仿真验证,在合环场景下将S-DRPST柔性投入牵引网,仅a相供电臂带负载的情况下,电压不平衡度从4.81%降低到了0.05%,在计及供电臂制动状态时不同工况的不平衡电压均被控制在0.1%以下,在牵引负载快速连续变化下S-DRPST能及时响应补偿负序电流,结果表明S-DRPST在高速铁路供电系统中具有良好的负序补偿效果。

感应电能传输系统多并联拾取模块电流和输出功率均衡方法

大功率感应电能传输系统通常采用多并联拾取模块结构。然而,多并联拾取模块参数不一致,会导致各个拾取模块的电流和输出功率不均衡,从而降低系统效率,严重时会因模块过流而造成系统故障。为解决该问题,文中提出一种基于并联拾取模块补偿电容器的多并联拾取模块电流和输出功率均衡方法。首先,介绍了传统感应电能传输系统与所提出的感应电能传输系统拓扑的特性。然后,分别分析了互感、拾取线圈自感及内阻对电流分布和系统效率的影响。最后,通过4个并联拾取模块的感应电能传输系统实验平台验证了所提方法的有效性。实验结果表明,采用所提方法时多并联拾取模块的电流和输出功率基本一致,并且相比传统感应电能传输系统,系统效率最高提升了2.21%。

DCM升压型PFC变换器的电流重整形补偿策略

针对不连续导通模式(DCM)下的升压型功率因数矫正(PFC)变换器,对其中的寄生参数致电流失真(PCD)效应进行研究。考虑元器件寄生参数,求解输入电压、输出电压和占空比的全微分方程,得到精确的阻尼型电感电流解析表达式。研究发现,PCD效应会导致很大的电流失真,从而显著降低系统功率因数。为了减小PCD效应,通过在不同条件下推导得到的补偿增益,能将输入电流重整为正弦波。对基于无电流传感的平均电流模式(SACM)控制,提出一种能降低PCD效应的电流重整形补偿策略。该策略对阻尼型电感电流方程进行增益补偿,进而降低电流阻尼导致的PCD效应。最后仿真和实验证明,增益补偿几乎不随负载电阻变化,变换器中的PCD效应和电流重整形策略有效。