Journal articles: 'APF control'

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MADANI, Hamid, Mohammad Ali MALBOOBI, Kioomars BAKHSHKELARESTAGHI, and Agnieszka STOKLOSA. "Biological and Chemical Phosphorus Fertilizers Effect on Yield and P Accumulation in Rapeseed (Brassica napus L.)." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 40, no. 2 (November 5, 2012): 210. http://dx.doi.org/10.15835/nbha4026079.

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A field experiment was conducted for investigation of different phosphorus fertilizer sources and their importance in rapeseed farms on 2007 at Arak, Iran. Ammonium phosphate fertilizer with 50% P2O5 (APF) was as chemical phosphorus sources with 3 rates of application and Phosphor solublizing bacteria (PSB) was as biological phosphorus surcease in 4 levels. Experiment was factorial arrangement in randomized complete block design with 3 replications. APF levels were control (AP0), 125kg/ha APF (AP1) and 250kg/ha (AP2) application and PSB levels were, control (PSB0), PSB at sowing time only (PSB1), PSB as top dress fertilizer after over wintering only (PSB2) and PSB at dual fertilizing in sowing time and also after over wintering (PSB3). The statistical analyses were showed that the PSB3 treatment was a great treatment for increasing seed yield. The heist rate of seed yield was recorded at 9.9t/ha under dual fertilizing in sowing time and after rosette over wintering stage. The interaction effects of phosphorus solublizing bacteria and ammonium phosphate fertilizer application had not significant effect on plant height, biomass yield, number of silique per plant, seed oil percent and seed yield. Interaction effects of phosphorus solublizing bacteria and ammonium phosphate fertilizer application were significant for plant tissues phosphorus content.

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Cao, Xudong, Shaozhe Zhou, Jingze Li, and Shaohua Zhang. "A DC Voltage Control Strategy for Active Power Filter." Open Electrical & Electronic Engineering Journal 10, no. 1 (December 30, 2016): 166–80. http://dx.doi.org/10.2174/1874129001610010166.

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Active Power Filter (APF) is capable of changing the size and frequency of harmonics as well as changes in reactive power compensation. It is important to control the stability of the DC-link capacitor voltage stability for it. For DC voltage controls of APF, there are two important achievements. First, it is indicated that the control of DC voltage directly affects the compensation performance of APF. Second, the value of DC voltage influences the power loss of APF. This paper firstly introduces the design of the DC voltage controller. Then the relationship between DC voltage and the power loss as well as the compensation performance of APF is analyzed. Finally, a new control scheme with a droop controller is developed to regulate DC voltage.

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Ma, You Jie, Jian Zhao, and Xue Song Zhou. "Control Methods of Active Power Filter." Advanced Materials Research 317-319 (August 2011): 2342–45. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.2342.

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Active power filter (APF) is an important device to compensate harmonic and reactive current in power system control method adopted has a great influence on its performance. The paper introduces several control methods used by APF, including the deadbeat control, single-cycle control, space vector control and so on. After comparing and analyzing their individual advantages and disadvantages, some improvements for APF performance are proposed.

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Fei, Juntao, Shenglei Zhang, and Jian Zhou. "Adaptive Sliding Mode Control of Single-Phase Shunt Active Power Filter." Mathematical Problems in Engineering 2012 (2012): 1–22. http://dx.doi.org/10.1155/2012/809187.

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This paper presents a thorough study of the adaptive sliding mode technique with application to single-phase shunt active power filter (APF). Based on the basic principle of single-phase shunt APF, the approximate dynamic model is derived. A model reference adaptive sliding mode control algorithm is proposed to implement the harmonic compensation for the single-phase shunt APF. This method will use the tracking error of harmonic and APF current as the control input and adopt the tracking error of reference model and APF output as the control objects of adaptive sliding mode. In the reference current track loop, a novel adaptive sliding mode controller is implemented to tracking the reference currents, thus improving harmonic treating performance. Simulation results demonstrate the satisfactory control performance and rapid compensation ability of the proposed control approach under different conditions of the nonlinear load current distortion and the mutation load, respectively.

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Fei, Juntao, and Shixi Hou. "Adaptive Fuzzy Control with Supervisory Compensator for Three-Phase Active Power Filter." Journal of Applied Mathematics 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/654937.

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An adaptive fuzzy control system with supervisory controller is proposed to improve dynamic performance of three-phase active power filter (APF). The proposed adaptive fuzzy controller for APF does not build an accurate mathematical model but approximates the nonlinear characteristics of APF using fuzzy approximation. The adaptive law based on the Lyapunov analysis can adaptively adjust the fuzzy rules; therefore the asymptotical stability of the adaptive fuzzy control system can be guaranteed. Simulation results demonstrate that the APF control system has excellent dynamic performance such as small current tracking error, reduced total harmonic distortion (THD) index, strong robustness in the presence of parameters variation, and nonlinear load.

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Zhang, Yong Feng, Xin Gong Cheng, Xi Ju Zong, Qing Qing Miu, Xiao Hong Chen, Yan Liang Wang, and Gang Chen. "The Switched Control of Single Phase Active Power Filter." Advanced Materials Research 383-390 (November 2011): 7515–20. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.7515.

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This paper proposes a novel control approach for single phase active power filter (APF) based on switched system theory, since the switching performance of APF. The switched model of APF is established by means of switching function. On this basis, the switched system error model is obtained. After that, a quadratic Lyapunov function is design to determine the switched control law. The switched control can make the switched system asymptotically stable and compensate the distorted current caused by the nonlinear load current. The effectiveness and rationality of the proposed approach is confirmed by the simulation result compared with the linear voltage control approach.

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Cao, Xudong, Kun Dong, and Xueliang Wei. "An Improved Control Method Based on Source Current Sampled for Shunt Active Power Filters." Energies 13, no. 6 (March 17, 2020): 1405. http://dx.doi.org/10.3390/en13061405.

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Active power filters (APFs) are dynamic power electronic devices that suppress harmonics and reactive power. To simplify the detection and extraction of traditional APF harmonics and reactive current, this paper proposes a direct source current control based on a three-phase three-wire shunt APF. The compensation principle and control method of the source current are analyzed systematically. The currents can be controlled without static errors by a proportional-integral (PI) controller in d-q rotating coordinates. Therefore, the compensation accuracy and dynamic performance of the system can be improved by the control strategy. Moreover, considering the grid voltage fluctuations, a droop regulator is proposed to address the impact of DC-link voltages on APF power losses and compensation performance. The regulator is combined with a traditional voltage outer loop PI control to achieve a comprehensive optimization between the power loss and compensation performance of the APF system. Finally, the inner current loop and the outer voltage loop form a double closed-loop cascade PI control structure to achieve the control effect of the APF. Simulation and experimental results verified the validity and feasibility of the APF control approach.

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Wang, Yu, Yuewu Wang, Si-Zhe Chen, Guidong Zhang, and Yun Zhang. "A Simplified Minimum DC-Link Voltage Control Strategy for Shunt Active Power Filters." Energies 11, no. 9 (September 12, 2018): 2407. http://dx.doi.org/10.3390/en11092407.

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The active power filter (APF) is a popular electrical device to eliminate harmonics in power systems. The rational design and effective control of DC-link capacitor voltage are important for implementing APF functions. In this study, the influences from the DC-link voltage on the APF compensating current characteristic and compensation performance are analyzed, and the reason to maintain DC-link voltage at a minimum value is investigated. On this basis, a simplified minimum DC-link voltage control strategy for APF is proposed. Compared with the existing DC-link voltage control strategies, the minimum DC-link voltage value in proposed strategy is only determined by the grid voltage and modulation ratio, reducing the calculation burden and the implementation difficulty in application, avoiding the interference from external parameters on the compensation effect. Additionally, the reference DC-link voltage varies at different values according to the grid voltage and modulation ratio. A shunt APF prototype is established and the experimental results verify the correctness and effectiveness of the analysis and proposed strategy.

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Francia, Piergiorgio, Carlo Ferri Marini, Leonardo Bocchi, Barbara Piccini, Giuseppe Seghieri, Ario Federici, Sonia Toni, and Francesco Lucertini. "The Assessment of Ankle Range-of-Motion and Its Relationship with Overall Muscle Strength in a Cross-Section of Soccer Players." Sports 11, no. 1 (January 5, 2023): 12. http://dx.doi.org/10.3390/sports11010012.

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Soccer (football) practice can induce a limitation of ankle range of motion (ROM) that is a possible risk factor for injury and other negative consequences over time. The main objective of this research was to investigate the effects of soccer practice on ankle ROM throughout the entire period of a sports career of soccer players (SP). Furthermore, the relationship between ankle ROM and muscle strength in SP of different ages was studied. A total of 204 SP (range 6.7–45.1 years) and 87 controls (range: 7.5–45.2 years) matched for age, body mass index (BMI), and gender, were assessed. Ankle ROM in both plantar flexion (APF) and dorsiflexion (ADF) in addition to handgrip strength (HGS) were evaluated using an inclinometer and the Jamar hydraulic hand dynamometer, respectively. The comparison between SP and control groups showed a significant reduction in ankle ROM of both APF (26.3 ± 7.2° vs. 32.6 ± 7.4°; d = −0.90; p < 0.001) and ADF (95.5 ± 15.6° vs. 105.5 ± 15.8°; d = −0.66; p < 0.001). In SP, the results of the ANOVAs test indicate that age had a significant effect on ADF (F = 4.352, p = 0.038, partial eta-squared (ηp2) = 0.015) but not on APF (F = 0.430, p = 0.746, ηp2 = 0.001). Moreover, considering only the SP, a weak inverse correlation between ADF and HGS group ADF was found (rs = −0.27; p < 0.001). Factors such as the non-linear trend of growth in young SP could hinder the definition of the relationship between ankle ROM, age, and muscle strength. However, the appropriate consideration of age and muscle strength could facilitate the management of ankle ROM in PF of different ages.

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Liu, Baolian, Zujun Ding, Huanyu Zhao, and Defei Jin. "Active Power Filter DC Bus Voltage Piecewise Reaching Law Variable Structure Control." Journal of Applied Mathematics 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/835720.

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The DC bus voltage stability control is one key technology to ensure that Active Power Filter (APF) operates stably. The external disturbances such as power grid and load fluctuation and the system parameters changing may affect the stability of APF DC bus voltage and the normal operation of APF. The mathematical model of DC bus voltage is established according to power balance principle and a DC bus voltage piecewise reaching law variable structure control algorithm is proposed to solve the above problem, and the design method is given. The simulation and experiment results proved that the proposed variable structure control algorithm can eliminate the chattering problem existing in traditional variable structure control effectively, is insensitive to system disturbance, and has good robustness and fast dynamic response speed and stable DC bus voltage with small fluctuation. The above advantages ensure the compensation effect of APF.

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Lin, Yu Qing, Mao Fa Gong, Hui Ting Ge, Bing Qian Liu, and Ning Xia Yang. "Comprehensive Compensation System Based on CS-APF and SVC." Applied Mechanics and Materials 635-637 (September 2014): 1418–21. http://dx.doi.org/10.4028/www.scientific.net/amm.635-637.1418.

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A unified control method of comprehensive compensation system based on CS- APF and SVC is introduced in this paper. SVC is composed of thyristor controlled reactor (TCR) and fixed capacitor (FC). For the CS- APF control, a feedforward control for harmonic compensation of SVC and load is applied. The CS- APF is enabled to optimize the var compensation performance of SVC. Finally, the simulation results show that the system can effectively compensate reactive power and eliminate harmonic currents.

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Adel, Mohamed, and Tarek Kandil. "Assessment of Direct and Indirect Current Control Techniques Applied to Active Power Filters." Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) 13, no. 8 (December 3, 2020): 1256–65. http://dx.doi.org/10.2174/2352096513999200710143353.

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Background: In this paper, an assessment of active power filter (APF) performance is presented under direct and indirect current control schemes through on-line compensation theory. Methods: Conventional Direct Current Control (DCC) measures both load current and filter current beside source and DC-link voltages, while Indirect Current Control (ICC) measures only source current beside voltage measurements. Both DCC and ICC control algorithms are implemented using 80C196KC low-cost microcontroller. Results: The performance parameters of APF are compared under two methods, and it is assigned that ICC gives a better performance with lower cost due to reduced number of sensors. The DC-link output voltage is controlled through simple PI-controller, and the PWM switching signals required by APF power circuit is obtained by hysteresis current controller. Conclusion: The comparative simulation and experimental results exhibit that performance of APF due to ICC scheme is superior than DCC one.

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Zhang, Sui, Wei Su, Yu Ku Qiao, Dong Dong Wang, and Ji Luo. "Simulation Study on Single-Phase Parallel Type of APF Double Loop Control Technique." Applied Mechanics and Materials 623 (August 2014): 187–94. http://dx.doi.org/10.4028/www.scientific.net/amm.623.187.

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This paper begins with analyzing the hazard of system harmonics and proposing the effectiveness of active power filter (APF) in harmonic wave inhibition. Against the background of single-phase parallel type of APF, its working principle is introduced and its mathematical model is built. Next, analyzed in details is the single-phase parallel type of APF double loop control system based on outer voltage loop and inner current loop, with the specific design procedure of PI control parameters of outer voltage loop and inner current loop presented. Finally, through MATLAB simulation, the designed system control parameters undergo verification. The simulation result indicates such single-phase parallel type of APF based on the double loop PI controller with outer voltage loop and inner current loop can ensure stability of the DC bus voltage and make effective compensation for harmonics over the mid-and low-frequency bands.

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Guo, Chen, Cun Bing Gui, and Jian Huang. "A Blend Control Scheme of Active Power Filter Based on Harmonic Voltage." Advanced Materials Research 268-270 (July 2011): 434–39. http://dx.doi.org/10.4028/www.scientific.net/amr.268-270.434.

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This paper proposes a blend control scheme of APF based on harmonic voltage to solve the problem that load current detection APF cannot change the harmonic impedance in distribution system. In addition, based on the relationship between the rated volt-ampere of APF and the load volt-ampere, the conductance value could automatic adjustment. Computer simulation and laboratory system are designed and constructed to verify the validity and effectiveness of the shunt active filter equipped with the blend control. The shunt active filter with blend control not only can compensate the nonlinear load harmonic current but also can help to damp the harmonic voltage in distribution system.

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Shen, Hong, Fan Yang, Ahmed Abu-Siada, and Zhao Liu. "A New Control Strategy for Active Power Filter." Energies 12, no. 21 (October 27, 2019): 4099. http://dx.doi.org/10.3390/en12214099.

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The significant increase in electronic devices has resulted in serious harmonic pollutions in electricity grids. In addition, due to the resonance of the system capacitance and inductance, the harmonic current may be amplified dramatically when it goes through the transmission line which is harmful to the normal operation of electrical equipment. To suppress the voltage and current harmonics resonance, many control strategies of active power filter (APF) are proposed. Nevertheless, these strategies cannot attenuate the amplified harmonic voltage and current due to resonance. In this paper, the harmonic propagation characteristics are investigated on a long transmission line and a new control strategy called VI-APF based on current-controlled and voltage-controlled current sources connected in parallel is presented. According to the simulation results, the proposed control strategy can suppress the total harmonic distortion to a low level. Finally, the effectiveness of VI-APF is demonstrated through the simulation on the IEEE 33-bus distribution system.

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Wang, Ji Dong, and Mei Cui Qin. "Microgrid Harmonic Suppression Method Based on One Cycle Controlled Active Power Filter." Applied Mechanics and Materials 347-350 (August 2013): 1445–49. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1445.

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With widely research and application of microgrid, the effect of the harmonic problems becomes not be ignored. This paper applies one cycle controlled active power filter (APF) to suppress harmonic in microgrid. Compared with traditional methods, one cycle controlled APF omits the harmonic detecting circuit and greatly simplifies the system structure. The one cycle control method in this paper, combining with space vector control, divides the frequency cycle into three control sextants, which simplifies the controller further. This paper builds the model of one cycle controlled APF and microgrid model including wind power system and photovoltaic systems. Then make simulation analysis about microgrid harmonic suppression. Simulation results show that one cycle controlled APF has a good compensation effect in microgrid harmonic suppression.

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Peng, Jin Jie, and Xiao Ping Fan. "Control Strategy for Fault-Tolerant Paralleling Active Power Filter." Advanced Materials Research 655-657 (January 2013): 1566–70. http://dx.doi.org/10.4028/www.scientific.net/amr.655-657.1566.

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A control strategy for a fault-tolerant paralleling active power filter was proposed. The structure and running models of the fault-tolerant paralleling active power filter were given. When the inverter of APF had fault in some phase, the fault structure of the inverter was analyzed. Its fault-tolerant structure was three-phase four-switch. The bridge composed of two capacitors replaced the fault phase for the inverter based on three-phase four-switch. It was important to stay stable for inverter DC-side. The method to stabilize the DC-side voltage was proposed. The controlling strategy for APF working on both normal state and fault state was proposed. The simulating results showed that harmonic currents were suppressed by the fault-tolerant paralleling APF whether working on normal state or fault state. The DC-side voltage stayed stable and the system has high reliability.

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Chelli, Z., R. Toufouti, A. Omeiri, and S. Saad. "Hysteresis Control for Shunt Active Power Filter under Unbalanced Three-Phase Load Conditions." Journal of Electrical and Computer Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/391040.

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This paper focuses on a four-wire shunt active power filter (APF) control scheme proposed to improve the performance of the APF. This filter is used to compensate harmonic distortion in three-phase four-wire systems. Several harmonic suppression techniques have been widely proposed and applied to minimize harmonic effects. The proposed control scheme can compensate harmonics and reactive power of the nonlinear loads simultaneously. This approach is compared to the conventional shunt APF reference compensation strategy. The developed algorithm is validated by simulation tests using MATLAB Simulink. The obtained results have demonstrated the effectiveness of the proposed scheme and confirmed the theoretical developments for balanced and unbalanced nonlinear loads.

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Wang, Yun Liang, and Xiao Feng Yu. "An Optimal Design of PI Control in the Application of Active Power Filter." Applied Mechanics and Materials 385-386 (August 2013): 1220–23. http://dx.doi.org/10.4028/www.scientific.net/amm.385-386.1220.

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This paper mainly introduces an optimal design of PI control based on compensation to eliminating the interference and improving the performance of the system. With the mathematic model of shunt APF in d-p rotating coordinate, simulation indicates that there is a period disturbing signal in the current closed loop of shunt APF based on the conventional PI control, which obviously impacts on the current tracking performance of the system. So a new PI control based on compensation is put forward. Through the simulation in the platform of Matlab/Simulink, it turns out that this method can improve the current tracking performance of APF and stable performance of the system.

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Jamuna, P., and S. Ramesh. "Experimental Validation of Impedance Source Network Based Active Power Filter for Interconnection of PV System into Grid." Journal of Circuits, Systems and Computers 27, no. 14 (August 23, 2018): 1850215. http://dx.doi.org/10.1142/s0218126618502158.

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This paper proposes a Solar Photovoltaic (SPV) interfaced Impedance Source Inverter (ZSI) based shunt Active Power Filter (APF) for compensation of power quality events such as current harmonics, voltage interruption and reactive power burden. The instantaneous reactive power theories with Fuzzy Logic Controller (FLC) based DC link voltage regulator is used to estimate the reference current signal and control the operation of the SPV interfaced shunt APF. Maximum Power Point Tracking (MPPT) algorithm is also employed to obtain the optimum maximum power point. The response of the SPV interfaced ZSI-shunt APF for mitigation of current harmonic distortions and reactive power compensation are investigated and compared with SPV interfaced Voltage Source Inverter (VSI) based shunt APF. The proposed SPV interfaced shunt APF employed with the FLC-based instantaneous reactive power theory control algorithm offers long lasting compensation against current-based distortions and reactive power requirements. The performance of the SPV interfaced ZSI based shunt APF has been verified by the simulation and experimental study. These results confirm the practicability of the proposed system in various load conditions with effective harmonic mitigation capability.

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Wang, Yu Feng, Guang Ye Liu, Xiao Guo Lv, and Zhong Chu Wang. "The Simulation of APF Based on Three-Phase VSI." Applied Mechanics and Materials 397-400 (September 2013): 1901–5. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.1901.

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In order to restrain harmonic pollution of power grid, the structure and control strategy of APF was researched. The structural parameters and method of direct current control of the most widely used APF with three-phase VSI was discussed. Decoupling control of active and reactive current on the dq plane was realized by dq transforming. Harmonic of load current was detected by Ip-Iq algorithm based on the instantaneous reactive power theory. Double closed-loop control was applied and PWM drive signals of IGBT were got through comparison of triangle wave and modulation wave. The simulation results demonstrate that the kind of control method make APF good dynamic response and static compensation.

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Hao, Meng, Xucheng Huang, Xianglu Ma, Xiaoshan Yao, Huihuang Mao, Li Ran, Cao Ke, and Panpeng Sheng. "Harmonic Compensation of APF Three-phase Three-line System Based on Quasi-PR Control." Journal of Physics: Conference Series 2404, no. 1 (December 1, 2022): 012011. http://dx.doi.org/10.1088/1742-6596/2404/1/012011.

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Abstract The Active power filter (APF) plays an important role in reducing the harmonic distortion rate of grid current and improving grid stability. However, the APF based on traditional methods such as deadbeat control and hysteresis control has poor tracking accuracy for the load harmonic current, and it is difficult to achieve efficient compensation. In this regard, this paper proposes a current inner loop quasi-proportional resonant (PR) control method to achieve fast-tracking of the compensation current and high control precision. Then, according to the equivalent mathematical model of the three-phase APF in the continuous domain, the parameters of the quasi-PR control method are designed. Finally, the effectiveness of the proposed method is verified by simulation.

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Ding, Zujun, Lutao Liu, and Baolian Liu. "Modeling Analysis of DC Magnetic Bias of Iron Core Reactor of APF." Mathematical Problems in Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/150129.

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As one of the main power devices of active power filter (APF), iron core reactor DC magnetic bias would affect the performance of APF. Based on the study of DC magnetic bias mechanism of APF iron core reactor, the data model was established in this paper. The performance of APF device impacted by iron core reactor DC magnetic bias was analysed through the simulation in different DC current conditions, and optimization scheme was proposed to reduce DC magnetic bias to improve working performance of APF. To reduce DC magnetic bias, main circuit parameters and control characteristics were uniform, and reluctance of iron core was increased. Results of the simulations and experiments validated that the improved method could restrain reactor DC magnetic bias to reduce even harmonic current in APF output current, which could greatly optimize APF performance.

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Ou, Zuoyuan, Yingpin Wang, Chang Su, Yi Qu, Hongyan Peng, and Xuguang Hao. "Precise model of LC active power filter and feedback linearization control." Journal of Physics: Conference Series 2232, no. 1 (May 1, 2022): 012012. http://dx.doi.org/10.1088/1742-6596/2232/1/012012.

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Abstract The problems of regulating power quality are more prevalent. In general, Active power filter(APF) is one of the best solution. But the influence of load impedance and grid impedance were widely ignored by a great number of papers, supposed the load voltage is constant and modeling in APF singly, which can’t describe the system accurately. Firstly,there are build an accurate model, including LC APF, load and grid impedance. Secondly, applying feedback linearization and proportional resonant differentiation (FL-PRD) control in inner current loop. Then analyze the influence of load and grid impedance. Once more,checked the accuracy of builded accurate model by Simulink and experiment. Eventually, compare mentioned algorithm in the paper with classical proportional resonant (PR) controller. The results show that it is rather important to set up an accurate model and the proposed algorithm gets a perfect capacity.

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Hou, Wen Bao, and De Lu Li. "Research on Predictive Current Control for Three-Level Four-Leg APF." Advanced Materials Research 1049-1050 (October 2014): 767–70. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.767.

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Taking three-level four-leg active power filter (APF) as research object, this paper establishes the corresponding mathematical model. In addition, the paper establishes the Matlab model based on predictive current control strategy, and then the theoretical analysis and simulation research are conducted. The simulation and experimental results show that the APF with predictive current control strategy can compensate harmonic current and neutral current well and make the two capacitors voltage balance effectively.

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Li, Lan Fang, Wei Ming Guo, Bai Yu Xu, and Ming Ma. "Takagi-Sugeno Fuzzy Control and Lyapunov-Based Stability Control of the Single-Phase Shunt Active Power Filter." Applied Mechanics and Materials 433-435 (October 2013): 1206–9. http://dx.doi.org/10.4028/www.scientific.net/amm.433-435.1206.

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In allusion to the difficulty of achieving accurate mathematical model of active power filter (APF), the Takagi-Sugeno (TS) fuzzy control is led into DC voltage control of APF. To solve the problem of control system stability, the control approach based on Lyapunov stability theory is applied to the current control. Both methods can ensure the control accuracy and stability. By means of adaptive fuzzy neural system in Matlab/Simulink the parameters of TS fuzzy controller are optimized and experiments are performed. Results show that under the time-varying load and variation of power system parameters both robustness and control accuracy of the control system can be ensured by the proposed control method.

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Keay, Susan, Francoise Seillier-Moiseiwitsch, Chen-Ou Zhang, Toby C. Chai, and Jialu Zhang. "Changes in human bladder epithelial cell gene expression associated with interstitial cystitis or antiproliferative factor treatment." Physiological Genomics 14, no. 2 (July 7, 2003): 107–15. http://dx.doi.org/10.1152/physiolgenomics.00055.2003.

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Explanted bladder epithelial cells from patients with interstitial cystitis (IC) have been shown to differ from explanted control cells in several ways, including production of an antiproliferative factor (APF), altered production of certain epithelial growth factors, and rate of proliferation. To better understand the role of the APF in abnormal bladder epithelial cell proliferation in IC, we studied gene expression patterns in normal bladder epithelial cells treated with APF vs. mock APF and compared them to expression patterns in IC vs. normal cells using microarray analysis. Oligo-dT-primed total cellular RNA was labeled with [33P]dCTP and hybridized to GeneFilter GF211 microarray membranes (Research Genetics) containing cDNA for 3,964 human genes. Thirteen genes that function in epithelial cell proliferation or differentiation were consistently differentially expressed in both IC (compared with control) and APF-treated (compared with mock APF-treated) normal bladder epithelial cells. The general pattern of gene expression in IC and APF-treated cells suggested a less proliferative phenotype, with increased expression of E-cadherin, phosphoribosylpyrophosphate synthetase-associated protein 39, and SWI/SNF complex 170-kDa subunit, and decreased expression of vimentin, α2-integrin, α1-catenin, cyclin D1, and jun N-terminal kinase 1; these findings were confirmed for the structural gene products (E-cadherin, vimentin, α2-integrin, and α-catenin) by immunohistochemistry. These results are compatible with the previously noted decreased proliferation rate of IC and APF-treated normal cells, and indicate that the mechanism whereby APF inhibits cell proliferation may involve both downregulation of genes that stimulate cell proliferation along with upregulation of genes that inhibit cell growth.

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Wang, Shaobo, Fen Lin, Tiancheng Wang, Youqun Zhao, Liguo Zang, and Yaoji Deng. "Autonomous Vehicle Path Planning Based on Driver Characteristics Identification and Improved Artificial Potential Field." Actuators 11, no. 2 (February 8, 2022): 52. http://dx.doi.org/10.3390/act11020052.

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Different driving styles should be considered in path planning for autonomous vehicles that are travelling alongside other traditional vehicles in the same traffic scene. Based on the drivers’ characteristics and artificial potential field (APF), an improved local path planning algorithm is proposed in this paper. A large amount of driver data are collected through tests and classified by the K-means algorithm. A Keras neural network model is trained by using the above data. APF is combined with driver characteristic identification. The distances between the vehicle and obstacle are normalized. The repulsive potential field functions are designed according to different driver characteristics and road boundaries. The designed local path planning method can adapt to different surrounding manual driving vehicles. The proposed human-like decision path planning method is compared with the traditional APF planning method. Simulation tests of an individual driver and various drivers with different characteristics in overtaking scenes are carried out. The simulation results show that the curves of human-like decision-making path planning method are more reasonable than those of the traditional APF path planning method; the proposed method can carry out more effective path planning for autonomous vehicles according to the different driving styles of surrounding manual vehicles.

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Li, Lan Fang, Hong Geng Yang, Wei Ming Guo, Ya Mei Liu, Fang Wei Xu, and Wei Gong. "Nonlinear Lyapunov-Based Stable Control Method of the Single-Phase Shunt Active Power Filter." Advanced Materials Research 354-355 (October 2011): 1390–93. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.1390.

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This paper proposes a nonlinear Lyapunov-based control method of the single-phase shunt active power filter (APF). The system is modeled firstly and then the compensated current of the APF is calculated. The energetic like Lyapunov function is constructed and the control output is determined through ensuring the differential of the Lyapunov function negative, which grantee the convergence of the APF system. Considering that the time-varying load may cause greater fluctuations in DC voltage, an average value is used to calculate the control output. A globally stable control is possible and it is insensitive to the parameter uncertainties and robustness to the disturbances. Simulation results are obtained using Matlab/ Simulink. These results verify the correct operation of the proposed control method.

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30

Xie, Xi Feng, and Li Ling Zheng. "Design of Single-Phase Active Power Filter." Applied Mechanics and Materials 329 (June 2013): 421–25. http://dx.doi.org/10.4028/www.scientific.net/amm.329.421.

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Aiming at the features of complexity, poor real-time and Low-accuracy of single-phase Active Power Filter (APF), and the problem of impossible parallel computation in the traditional DSP software realization, new design method of APF Based on FPGA is proposed, This paper focuses on the study of the harmonic current detecting method and improves control method of compensate current, it builds an experimental platform with FPGA EP1C12Q240C8 as the controller, the experimental results all support the effectiveness and correctness of the control methods and design methods of APF.

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31

Panpean, Chakrit, Kongpol Areerak, Phonsit Santiprapan, Kongpan Areerak, and Seang Shen Yeoh. "Harmonic Mitigation in Electric Railway Systems Using Improved Model Predictive Control." Energies 14, no. 7 (April 5, 2021): 2012. http://dx.doi.org/10.3390/en14072012.

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An electric multiple unit (EMU) high-speed train is the dynamic load that degrades the power quality in an electric railway system. Therefore, a power quality improvement system using an active power filter (APF) must be considered. Due to the oscillating load current in the dynamic load condition, a fast and accurate harmonic current-tracking performance is required. As such, this paper proposes the design of a model predictive control (MPC) since the minimization of cost function in the MPC process can suitably determine APF switching states. The design technique of MPC is based on the APF mathematical model. This controller was designed to compensate the time delay in the digital control. Moreover, the synchronous detection (SD) method applied the reference current calculations, as shown in this paper. To verify the proposed MPC, the overall control of APF was implemented on a eZdsp F28335 board by using the hardware-in-the-loop technique. The testing results indicated that the proposed MPC can provide a fast and accurate harmonic current-tracking response compared with the proportional-integral controller. In the load changing condition, the MPC was still effective in providing a good result after compensation. The percentage of total harmonic distortion, the percentage current unbalance factor, and the power factor would also be kept within the IEEE Standard 519 and IEEE Standard 1459.

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32

Lin, Hai Yan, Hai Liu, and Yin Zhao Wang. "Design of Hardware Based on Control Circuit of APF." Applied Mechanics and Materials 148-149 (December 2011): 353–56. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.353.

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In this paper, we focus on the hardware design of control circuit based on shunt active power filter (APF). It described the AD transformation module, DSP data processing module, CPLD logic control module, man-machine interaction module and asynchronous communication module. As the core controller, TMS320C5416 digital signal processor (DSP) controls this peripheral assistant circuit to complete data acquisition, harmonic detection and output of control signal. Finally, we design the layout and routing of the control circuit.

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33

Senguttuvan, S., and M. Vijayakumar. "Solar Photovoltaic System Interfaced Shunt Active Power Filter for Enhancement of Power Quality in Three-Phase Distribution System." Journal of Circuits, Systems and Computers 27, no. 11 (June 6, 2018): 1850166. http://dx.doi.org/10.1142/s0218126618501669.

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This paper presents a solar photovoltaic (SPV) interfaced shunt active power filter (APF), which is certainly one of the utmost effective custom power devices, which mitigates the long duration current harmonics and compensates the reactive power. The shunt APF consists of the parallel connected voltage source inverter (VSI) and storage capacitor which is connected in the DC link. The compensation ability of the APF is mainly inspired by the control technique which is used to estimate the reference source current signal. Furthermore, the controller chooses the number of devices required and measurement practices; thus, it determines the corresponding costs. The fuzzy logic controller (FLC)-based second order generalized integrator (SOGI) is employed to estimate the reference source current of the shunt APF. The presented control scheme does not require voltage associated information and sensors, because it utilizes the details concerning the VSI and load currents. The shunt APF uses the solar photovoltaic (SPV) system with an auxiliary energy storage unit to deliver the required active power to the electric grid and affords the uninterrupted compensation. The performance analysis has been carried out with different load and voltage conditions through the simulation by using the MATLAB/Simulink. The experimental prototype was developed to confirm the usefulness of the PV integrated shunt APF with FLC-based SOGI control scheme.

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34

Jaffar, Hairol, and Naziha Ahmad Azli. "Cross-Connected Source Multilevel Inverter for Active Power Filtering Using Unified Constant-Frequency Integration Control." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 1 (March 1, 2017): 117. http://dx.doi.org/10.11591/ijpeds.v8.i1.pp117-124.

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This paper proposes an Active Power Filter (APF) system which utilizes a five-level nonconventional Cross-Connected Source Multilevel Inverter (CCSMI) with a modified Unified Constant-Frequency Integration (UCI) control. The CCSMI consists of six power switches which can produce five output voltage levels. With the use of the CCSMI, the parts count is reduced with equivalent or better performance compared to the use of conventional multilevel inverters. The capability of the proposed system is tested using three types of nonlinear loads with different characteristics. The APF system is simulated under steady-state condition using MATLAB/Simulink. The results obtained show improvement in the supply current Total Harmonic Distortion (THD) with room for enhancement, using the proposed APF system.

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Li, Zhi Yong, Yu Xun Luo, and Ling Fei Shen. "Modified Direct Power Control for LCL-APF without Harmonic Current Detection." Applied Mechanics and Materials 433-435 (October 2013): 1210–17. http://dx.doi.org/10.4028/www.scientific.net/amm.433-435.1210.

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The active power filter with LCL filter (LCL-APF) possesses the advantages of wide bandwidth of compensation and a small amount of switching ripples. A direct power control (DPC) method of LCL-APF without harmonic current detection technology is proposed. Not only the complex detection of load harmonic current and compensation harmonic current is omitted, but also the total rate of harmonic distortion of grid side is reduced from 27.7% to 1.12%. To overcome the disadvantages of resonance caused by three-order LCL filter, the power of active power damping is added in the power controller. Thus, the dynamic control performance of LCL-APF is improved, as stable waveforms of grid current and power after 0.04s proved. Meanwhile, a modified DPC control loop is formed. Simulation results prove that the proposed method is correct and feasible. In view of the fact that it is rapid and accurate, especially the power level of 150kW, so it is suitable for the distributed generation system.

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36

Al-Gahtani, Saad F., and R. M. Nelms. "Performance of a Shunt Active Power Filter for Unbalanced Conditions Using Only Current Measurements." Energies 14, no. 2 (January 12, 2021): 397. http://dx.doi.org/10.3390/en14020397.

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Shunt active power filters (APFs) are used to address power quality issues such as harmonic distortion and power system imbalance. Many control systems for shunt APFs demand measurements of voltages and currents for the determination of instantaneous real and reactive power signals. From these signals, the reference currents of the shunt APF are calculated. A method of control for the APF shunt that only measures currents is proposed in this paper. The control method includes a modified technique to extract the positive and negative sequence components in the time domain. The reference currents in the shunt APF are calculated by the negative sequence components of the measured currents. Simulation and experimental results confirm the efficiency of this control scheme under ideal and non-ideal conditions.

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37

Yang, Longyue, Tian Cao, Huapeng Chen, Xinwei Dong, and Shuyuan Zhang. "Robust Control and Optimization Method for Single-Phase Grid-Connected Inverters Based on All-Pass-Filter Phase-Locked Loop in Weak Grid." Energies 15, no. 19 (October 6, 2022): 7355. http://dx.doi.org/10.3390/en15197355.

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In a distributed generation system, the all-pass-filter phase-locked loop (APF-PLL) is a commonly used method for grid synchronization. However, the coupling effect between APF-PLL and current control loop increases the risk of oscillation instability for the inverter in the weak grid. At present, there are few effective methods to solve the adverse effect of APF-PLL on the inverter-grid interconnection system in the weak grid. Therefore, a small-signal impedance model of the inverter considering the dual d-q frame brought by APF-PLL is first established. Then the reason for the inverter instability caused by APF-PLL in the weak grid is analyzed. Subsequently, an impedance reshaping method based on a modified first-order filter PLL with a complex coefficient filter (CCF-MFOF-PLL) and its parameter optimization design method are proposed. Finally, the experimental results verify that the proposed method widens the stable range of the inverter and ensures the stable operation of the inverter even with the large grid impedance.

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Pei, Xing Hua, Xin Gong Cheng, Xi Ju Zong, and Wen Dou. "Modeling and State Feedback Control of Three-Phase Active Power Filter on Switched System." Applied Mechanics and Materials 278-280 (January 2013): 1477–81. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.1477.

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Three-phase active power filter (APF) is a typical switched affine system for the action of the power switch. The conventional method of modeling was based on the linear system theory. In this paper, a novel control procedure for the three-phase APF based on the switched affine system and quadratic stability is proposed. Firstly, the three-phase APF is built as switched affine system model. Based on the sufficient condition for quadratic stability of convex combination, the common Lyapunov function is selected. Then, the switched rules can be defined to assess quadratic stability of the switched system, thus realizing the control of the compensation current and the DC side voltage. Finally, simulation results have good agreement with the theory analysis, and demonstrate the validity of this approach.

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39

Fang, Yunmei, and Juntao Fei. "Adaptive Backstepping Current Control of Active Power Filter Using Neural Compensator." Mathematical Problems in Engineering 2019 (May 16, 2019): 1–9. http://dx.doi.org/10.1155/2019/5130738.

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A backstepping-based adaptive controller with neural compensator is designed for harmonic suppression in a three-phase active power filter (APF). The fundamental rule of backstepping method is to take some state variables as “virtual controls” and then design intermediate controller. An adaptive neural controller using radial basis function (RBF) is derived to estimate the APF system nonlinearity and strengthen the current’s tracking property and power grid quality. Simulations studies indicate the proposed backstepping-based adaptive neural controller has good current tracking behavior and increased power quality.

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40

Liu, Dong, Baojin Li, Songtao Huang, Linguo Liu, Haozhe Wang, and Yukai Huang. "An Improved Frequency-Adaptive Virtual Variable Sampling-Based Repetitive Control for an Active Power Filter." Energies 15, no. 19 (October 1, 2022): 7227. http://dx.doi.org/10.3390/en15197227.

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To eliminate the harmonics caused by nonlinear loads, repetitive controllers are widely applied as current controllers for active power filters (APF). In practice, a variation in grid frequency leads to the appearance of a fractional-order delay filter. As a result, the resonant frequency of the repetitive controller will deviate from the fundamental frequency and the controller cannot compensate for harmonics accurately. To solve this problem, an improved frequency-adaptive repetitive controller based on virtual variable sampling (IMFA-VVS-RC) for APF is proposed in this paper. To enhance the system stability margin, the proposed RC introduces an infinite impulse response (IIR) low-pass filter. The proposed RC has a high stability margin at high frequencies due to the low gain of the IIR low-pass filter in the region above the cutoff frequency. In this way, the influence of model uncertainty and parameter uncertainty on system stability are reduced at high frequencies. At the same time, compared with the conventional repetitive controller (CRC), the proposed RC for APF has a better harmonic suppression ability when the frequency varies. Experiments have verified the effectiveness of the scheme adopted for APF.

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41

Chai, Jin Peng, and Zheng Song Qiu. "A Comparative Study between p-Aminobenzensulfonate-Phenol-Formaldehyde Condensate and Sulfomethylated Phenolic Resin as Drilling Mud Fluid Loss Reducer." Advanced Materials Research 1081 (December 2014): 31–37. http://dx.doi.org/10.4028/www.scientific.net/amr.1081.31.

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The p-aminobenzensulfonate-phenol-formaldehyde (APF) condensate is synthesized and characterized by FTIR and TGA analyses. Its properties as drilling mud fluid loss reducer are studied with respect to fluid loss and particle size distribution. In addition, the effect of salt on properties of APF condensate was discussed. Test results show that the APF condensate not only possesses higher thermal stability than sulfomethylated phenolic resin (SMP), a commercial drilling mud additive, but also achieves good property of fluid loss control by reducing the permeability of filter cake; the fluid-loss controlling properties of APF condensate dropped with the increase of concentrations of NaCl.

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42

Kowalczyk, W., M. Michałek, and K. Kozłowski. "Trajectory tracking control with obstacle avoidance capability for unicycle-like mobile robot." Bulletin of the Polish Academy of Sciences: Technical Sciences 60, no. 3 (December 1, 2012): 537–46. http://dx.doi.org/10.2478/v10175-012-0066-x.

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Abstract In this paper the trajectory tracking control algorithm with obstacle avoidance capability is presented. As a robot gets into a neighborhood of the obstacle, the collision avoidance behavior is turned on. It is implemented using the artificial potential function (APF) that increases to infinity as the robot approaches a boundary of the obstacle. This feature guarantees collision avoidance. As avoidance behavior is active only in the neighborhood of the obstacle it does not affect the motion when there is no risk of the collision. Authors show that trajectory of the robot converges to desired one when a robot is out of the APF area. Due to a local characteristic of the APF, the implementation of the algorithm of the robot that uses only on-board sensors is possible. The stability proof is presented for both a near obstacle and obstacle-free areas. Effectiveness of the algorithm is illustrated with experiments on a real robot in an environment with static circle-shaped obstacles.

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Yang, Jie, Ke Yi Zhang, Xin Ming Wang, Cheng Long Hao, and Tao Wei. "UAV Formation Control Based on the Improved APF." Advanced Materials Research 933 (May 2014): 358–64. http://dx.doi.org/10.4028/www.scientific.net/amr.933.358.

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Malfunction such as target non-reach ability, local minimum pole and oscillation happens when traditional APF is applied to route planning. This paper proposes an improved APF model, considering the relative distance between the UAV and the target, the relative distance between the lead craft and the wing craft and the safety. We ensure the point of target to be the global minimum point in the entire potential fieldtarget non-reach ability caused by the threat and target point being too close are solved by adopting the modified repulsive potential function; planning failure in which UAVs falling into local minimum point is solved by adopting random fluctuation method; considering the oscillation of traditional potential field, the obstacle link method is proposed. The results of the simulation indicate the single UAV simulation route after obstacles overall planning, track route of UAV formation and formation route with obstacles with turning angle constraints. Requirements of Formation control and formation obstacle avoidance have been well satisfied.

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44

Xueliang Wei. "Shunt APF Based on Current Loop Repetitive Control." Journal of Convergence Information Technology 5, no. 4 (June 30, 2010): 29–37. http://dx.doi.org/10.4156/jcit.vol5.issue4.4.

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Gui, Cun Bing, Chen Guo, and Zhong Ren Chen. "The Summarization and Prospection of APF Control Means." Advanced Materials Research 317-319 (August 2011): 1318–21. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.1318.

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It make a detailed description and instruction with the control condition of the Active Power Filter, at the same time , it also make a comparison with the advantage and the shortcoming one by one , at the end, make a prospection with the developing tendency and research keys.

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46

Li, Xiangshun, and Jianghua Lu. "Control for the Three-Phase Four-Wire Four-Leg APF Based on SVPWM and Average Current Method." Active and Passive Electronic Components 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/528360.

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A novel control method is proposed for the three-phase four-wire four-leg active power filter (APF) to realize the accurate and real-time compensation of harmonic of power system, which combines space vector pulse width modulation (SVPWM) with triangle modulation strategy. Firstly, the basic principle of the APF is briefly described. Then the harmonic and reactive currents are derived by the instantaneous reactive power theory. Finally simulation and experiment are built to verify the validity and effectiveness of the proposed method. The simulation results show that the response time for compensation is about 0.025 sec and the total harmonic distortion (THD) of the source current of phaseAis reduced from 33.38% before compensation to 3.05% with APF.

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Nicola, Marcel, Claudiu-Ionel Nicola, Dumitru Sacerdoțianu, and Adrian Vintilă. "Comparative Performance of UPQC Control System Based on PI-GWO, Fractional Order Controllers, and Reinforcement Learning Agent." Electronics 12, no. 3 (January 17, 2023): 494. http://dx.doi.org/10.3390/electronics12030494.

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In this paper, based on a benchmark on the performance of a Unified Power Quality Conditioner (UPQC), the improvement of this performance is presented comparatively by using Proportional Integrator (PI)-type controllers optimized by a Grey Wolf Optimization (GWO) computational intelligence method, fractional order (FO)-type controllers based on differential and integral fractional calculus, and a PI-type controller in tandem with a Reinforcement Learning—Twin-Delayed Deep Deterministic Policy Gradient (RL-TD3) agent. The main components of the UPQC are a series active filter and an Active Parallel Filter (APF) coupled to a common DC intermediate circuit. The active series filter provides the voltage reference for the APF, which in turn corrects both the harmonic content introduced by the load and the VDC voltage in the DC intermediate circuit. The UPQC performance is improved by using the types of controllers listed above in the APF structure. The main performance indicators of the UPQC-APF control system for the controllers listed above are: stationary error, voltage ripple, and fractal dimension (DF) of the VDC voltage in the DC intermediate circuit. Results are also presented on the improvement of both current and voltage Total harmonic distortion (THD) in the case of, respectively, a linear and nonlinear load highly polluting in terms of harmonic content. Numerical simulations performed in a MATLAB/Simulink environment demonstrate superior performance of UPQC-APF control system when using PI with RL-TD3 agent and FO-type controller compared to classical PI controllers.

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48

Fernández, Constanza E., Livia Maria Andaló Tenuta, Altair Antoninha Del Bel Cury, Diego Figueiredo Nóbrega, and Jaime Aparecido Cury. "Effect of 5,000 ppm Fluoride Dentifrice or 1,100 ppm Fluoride Dentifrice Combined with Acidulated Phosphate Fluoride on Caries Lesion Inhibition and Repair." Caries Research 51, no. 3 (2017): 179–87. http://dx.doi.org/10.1159/000453624.

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High fluoride dentifrice (FD; 5,000 ppm F) has been recommended to arrest root dentine lesions and to control enamel caries in high-risk patients. Also, standard FD (1,100 ppm F) in combination with professional fluoride application has been recommended to control dentine caries, but the effect of this combination on enamel has been considered modest. Considering the lack of evaluation comparing the use of 5,000 ppm FD (5,000-FD) versus acidulated phosphate fluoride (APF) application combined with 1,100 ppm FD (1,100-FD) on the inhibition and repair of caries lesions in both enamel and dentine, we conducted this in situ, double-blind, crossover study of 3 phases of 14 days. In each phase, 18 volunteers wore palatal appliances containing enamel and root dentine specimens, either sound or carious, to evaluate the effect of the treatments on the inhibition or repair of caries lesions, respectively. The treatments were non-FD (negative control), 5,000-FD, or 1 APF gel application on dental specimens combined with 1,100-FD used twice per day (APF + 1,100-FD). The reduction of demineralization and enhancement of remineralization were assessed by surface and cross-sectional hardness. Fluoride concentration was determined on dental specimens and on the formed biofilm. For enamel, APF + 1,100-FD and 5,000-FD did not differ regarding the inhibition of demineralization and repair of caries lesions. However, for dentine the difference between these treatments was inconclusive because while APF + 1,100-FD was more effective than 5,000-FD in caries lesion reduction and repair, 5,000-FD was more effective than APF + 1,100-FD in the reduction of surface demineralization. Therefore, the findings show that the combination of APF + 1,100-FD is as effective as 5,000-FD in enamel inhibition of demineralization and enhancement of remineralization.

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Chinelatti, Michelle Alexandra, Camila Tirapelli, Silmara Aparecida Milori Corona, Renato Goulart Jasinevicius, Oscar Peitl, Edgar Dutra Zanotto, and Fernanda de Carvalho Panzeri Pires-de-Souza. "Effect of a Bioactive Glass Ceramic on the Control of Enamel and Dentin Erosion Lesions." Brazilian Dental Journal 28, no. 4 (August 2017): 489–97. http://dx.doi.org/10.1590/0103-6440201601524.

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Abstract This study evaluated the effect of a bioactive glass ceramic for the control of erosion and caries lesions. Fragments (n=10) of bovine enamel and root dentin received daily application of different treatments (Biosilicate; Acidulated Phosphate Fluoride- APF; Untreated - control) during the performance of erosive cycles. Surfaces were analyzed with 3D optical profilometry to quantify the superficial loss in four periods (1, 7, 14 and 21 days), as well as the lesion depth with confocal laser scanning microscopy. For caries progression assessment, initial Knoop microhardness was measured on enamel bovine fragments. Initial carious lesions were developed and specimens were divided into three groups (n=10), according to the daily topical application (Biosilicate; APF; no application - control), during the de-remineralization cycles for 14 days. Final microhardness was obtained to calculate the change of surface microhardness. Subsurface demineralization was analyzed using cross-sectional microhardness (depths 10, 30, 50, 70, 90, 110 and 220 µm). Data were tested using ANOVA and Tukey’s test (a=5%). Results of erosive evaluation showed that Biosilicate promoted the lowest (p<0.05) values of surface loss, regardless of time, for both enamel and dentin; APF promoted lower (p<0.05) surface loss than control; analyzing different periods of time, APF did not show difference (p>0.05) between 14 and 21 days of demineralization. Results of enamel caries assessment showed that Biosilicate resulted in higher (p<0.05) surface and subsurface microhardness than both APF and control-applications. It may be concluded that Biosilicate application showed a higher potential to reduce surface loss and development of erosion and caries lesions.

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Wang, Yun Liang, and Qi Liang Guo. "Hysteresis Current Control Technique Based on Space Vector Modulation for Active Power Filter." Applied Mechanics and Materials 385-386 (August 2013): 1224–28. http://dx.doi.org/10.4028/www.scientific.net/amm.385-386.1224.

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In this paper, the hysteresis current control (HCC) technique based on space vector modulation (SVM) for active power filter (APF) is proposed. The switching control algorithms of the HCC based SVM manage to generate compensated current according to the reference current. Harmonics extraction is calculated for the power compensation based on the instantaneous active and reactive power theorem in time domain. A closed loop control system is carried out and the APF manages to generate better compensated harmonics currents to the power grid.

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Journal articles on the topic 'APF control'

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