Abstract: This review article examines the range of sensors that have been proposed for monitoring wind turbine blade loads for the purpose of active load control over the past decade. Wind turbine active load control requires sensors that are able to detect loads as they occur, in order to enable a prompt actuation of control devices. Loads may be detected based on structural effects or inferred from aerodynamic measurements. This paper is organized into the following sections: wind turbine control, requirements for load monitoring sensors, sensing technologies and field tests of load control. The types of sensors examined in this article include fiber optic sensors, inertial sensors, pressure measurements and remote optical sensing.

Abstract: In order to improve the harmonic reduction ability of 12-pulse rectifier, an active interphase reactor (AIPR) and corresponding auxiliary circuit are often used to produce circulating current resulting in harmonic reduction. This paper analyzes the load adaptability of 12-pulse rectifier with AIPR. The loads are classified into three types, RL -type load, RC -type load, and RLC -type load. Load currents and circulating currents are calculated under different load types. According to the calculation results, the THD of input line current and ripple coefficient of load voltage are also described by figures under RL -type load and RLC -type load. The appropriate amplitude of the circulating current under RL -type load and the LC filter under RLC -type load are presented. Simulation and experimental results validate the theoretical analysis.

Abstract: Simple current mirrors with semiconductor resistive loads suffer from large on-chip area, leakage currents and thermal effects. In this paper, we report the feasibility of using memristive loads as a replacement of semiconductor resistors in simplistic current mirror configuration. We report power, area and total harmonic distribution, and report the corner conditions on resistance tolerances.

Abstract: This paper presents a novel Doherty transmitter architecture based on antenna active load modulation (AALM) to improve the efficiency of array transmitters, where the conventional power combiner is substituted by an antenna array. Different from conventional Doherty architecture, the active load modulation is realized by the mutual coupling between the array elements. To verify the proposed architecture, a power amplifier (PA) prototype is designed and implemented at 2.3 GHz. Experimental results show that the transmitter exhibits a double-peak efficiency profile which is similar to conventional Doherty PA. The prototpye also achieves power gain of 14 dB, saturated output power of 40.5 dBm, and drain efficiency of better than 40%.

Abstract: Cross-coupled differential pairs implement an even-order active frequency multiplier in 90 nm SiGe-BiCMOS. The multiplier core uses asymmetric biasing to realize an even-order transfer function. Wideband (WB) and narrowband doublers built around the active core are proposed, and their relative performance is compared from simulation. Measurement of a WB prototype consisting of the doubler, active load with feedback regulation of bias, and 50 $\Omega$ input and output buffers validates the circuit concepts. Conversion gain (CG) for the WB doubler peaks at low frequency (e.g., 12 dB at 10 GHz) and rolls off to 0 dB at 100 GHz. For 25 GHz output, significant spurs are: $-$ 25 dBc at 12.5 GHz (input tone) and $-$ 28 dBc at 50 GHz (4th harmonic). The 0.37 mm $^{2}$ WB testchip consumes 55.5 mA from a 4.5 V supply.

Abstract: This paper introduces the design and implementation of a programmable AC/DC active load emulator that has the capability to emulate a very wide range of active power with the ability to change the power with small steps to give flexible load emulation. The developed load emulator can mimic the real time active power characteristic of a daily load pattern which can be used in testing power management algorithms. It gives an easy tool to test the performance of the utility grid by emulating different load profiles like random residential loads and electric vehicle charging stations. Furthermore, it can be used in the shipboard power system to emulate pulsated load. A friendly user GUI is developed in LabVIEW to facilitate the control of the load emulator. Actual hardware implementation steps are explained in details. The initial experimental results show the validity of the developed active power emulator and its capability to mimic different load profiles.

Abstract: A preamplifier may include: a common active load suitable for providing output impedance; an output polarity changing unit suitable for changing an output polarity of output nodes; a multi-differential input stage suitable for receiving an input voltage, a coarse ramping voltage, a fine ramping voltage and a common mode voltage, and sampling the common mode voltage and the coarse ramping voltage for amplification operations; and a coupling blocking unit suitable for blocking a coupling between the output nodes and input nodes that are included in the multi-differential input stage.

Abstract: A power system for an electrical system with highly fluctuating loads is powered by one or more power sources that are slow to react to load changes. The power sources are connected to electrical equipment used on the drill rig which provide active load to the generators. One or more load banks may be positioned to provide passive load to the generators to maintain generally constant generator load, while allowing for instant access to power as active load increases. Generators may be run at 100% capacity, a maximum efficient capacity, or at a high enough level to allow for a sufficiently rapid increase in power output. At least one parameter of a drilling operation may be utilized to anticipate load demand changes.

Abstract: This work discusses several extraction procedures for the recently proposed dual input-dual output (DIDO) low pass equivalent behavioral model according to their required excitation signals. These methods are based on passive load pulling and uncontrolled open loop active load pulling but with different type of excitation waveforms. It also addresses the hardware and signal conditioning of the proposed extraction procedures in detail. The performance of the discussed methods are compared based on the datasets extracted from simulation results in ADS. The results show that the use of the active load-pulling can enhance modeling performance.

Abstract: A 2–30 GHz ring mixer with built-in active baluns for vital sign detection application is presented in this paper. This mixer was fabricated in 0.18-µm CMOS process. Two topologies of active baluns are utilized to increase the isolation between the LO and the RF ports to mitigate the dc-offset problem. With bandwidth-enhancement circuit [9] and the active load, the phase errors of both RF and LO baluns are less than 7 degree. The input return loss is better than 10 dB over 20-GHz bandwidth. The measured conversion gain is −18.5 ±2 dB from 2 to 30 GHz at 3-dBm LO power. The input third-order intercept point (IIP3) is 4 dBm at 16GHz. The proposed mixer with built-in active baluns consumes 20 mW dc power within a compact chip size of 0.81 × 0.63 mm2.

Abstract: Under stationary conditions, the optimization of maximum power output and efficiency of thermoelectric generators (TEG) is a well-known subject. Use of a finite-time thermodynamics (FTT) approach to the description of TEGs has demonstrated that there exists a closed feedback effect between the output electrical load value and the entering heat current. From the practical point of view, this effect is strongly evidenced by the use of direct current (DC-to-DC) converters as active loads. Both transient conditions and FTT contribute to a complex landscape of the optimization of the power and efficiencies of a TEG. It has been claimed that the use of inductive load may lead to a strong enhancement of the efficiency, and the frequency response of a TEG as a band-pass filter has also been recently reported. We consider these results using a classical linear Onsager approach of a TEG operating under transient conditions. We show that a trans-admittance may be defined as a coupling element between the input and the output, leading to the observed electric-to-thermal feedback. We discuss recent experiments on a TEG connected to an active load, which is reported to boast an efficiency exceeding the usual stationary DC thermoelectric efficiency.

Abstract: An example method for active load modulation includes determining a modulated portion and an unmodulated portion of a bit. Further, the example method includes during the modulated portion of the bit, holding a phase of a received carrier signal. In addition, the example method includes, during the unmodulated portion of the bit, synchronizing to the received carrier signal.

Abstract: The major disturbance to the launch vehicle during the high dynamic pressure period is inflight winds, and it causes extra aerodynamic load and significant magnitude of bending moment. Load relief system is used to decrease the aerodynamic load by reducing the angle of attack to increase the launching capability. This paper focuses on the load control technology when the launch vehicle passes through the strong wind area. Firstly, by analyzing and simulating the load relief system of the traditional launch vehicles including long march 3A, atlas/centaur, Saturn V, titan III and Ariane 5, this paper points out the advantages and disadvantages of classical passive trajectory correction method and four active load control methods. Besides, the control enhanced and parameterized technology (CEPT) is putted forward from the active disturbance rejection control (ADRC) and load relief cell. On the one hand, the error signal observed by the modified state observer is introduced to compensate the uncertain error signal observed by extended state observer in the ADRC loop; on the other hand, the load relief cell is introduced into the initial control system to enhance the load relief capability; at last, the control law of the CEPT controller is parameterized, a method is given to select the gains in the control law, and the load restriction effect under the combination of CEPT and initial controller is shown. Taking a kind of liquid launch vehicle as an example, and considering the inherent elastic vibration and liquid sloshing, this paper compares the load relief effect under different control architectures motioned above. The simulation result indicates that the CEPT controller expands the range of the parameters, enhances the disturbance rejection capacity for the flight control system, and efficiently improves the load control effect.

Abstract: The utility model relates to a high-speed clock-controlled comparator. The high-speed clock-controlled comparator comprises a pre-amplifying stage circuit and a clock circuit, in the pre-amplifying stage circuit, a transistor M0 is an active load of an input differential pair transistor, the transistor M0 is connected with a differential input stage transistor M4 in series and then connected with a transistor M1 and a differential input stage transistor M5 in parallel, wherein the transistor M1 is the active load of the input differential pair transistor, the transistor M1 and the differential input stage transistor M5 are connected in series; a tail current source transistor M6 is respectively connected with the differential input stage transistor M4 and the differential input stage transistor M5, and a clock control transistor M11 is connected with the tail current source transistor M6 and controlled by the clock circuit. When signals CLK of the clock circuit is a high level, the pre-amplifying circuit operates, and voltage signals in need of comparison at a differential input terminal are acquired; when the signals CLK of the clock circuit is a low level, the clock control transistor M11 is switched off, the pre-amplifying stage circuit does not operate, and the power consumption is reduced; the pre-amplifying stage circuit is controlled to operate in an alternative manner by the clock circuit, and the power consumption of the circuit is reduced.

Abstract: This paper proposes a reactive power control strategy for the active load balancer (ALB) in three-phase four-wire distribution systems. The proposed reactive power control strategy is based on constant DC capacitor voltage control, which is always used in active power line conditioners. Therefore, the proposed reactive power control strategy does not require active, reactive calculation blocks of load currents for the reference source current calculation. Balanced source currents with a predefined power factor can be achieved without unbalanced active and reactive components detection of the load currents. The basic principle of the reactive power control strategy for the ALB is discussed in detail, and then confirmed by digital computer simulation using PSIM software. A prototype experimental model is constructed and tested to validate the feasibility of the proposed control algorithm. Simulation and experimental results demonstrate that balanced source currents with a predefined power factor are achieved in three-phase four-wire distribution systems.

Abstract: The invention discloses an energy storage system based active load multi-target coordination control method. The multi-target comprises regional power grid call wire power sums, user economical benefits and electric power company operation benefits; the weights of operating targets are adjusted by users according to actual needs; by analyzing power supply output in a demand side, the charging state of the energy storage system, user energy-use needs and real-time electricity price, the real-time output of the energy storage system is automatically planned to realize the most optimized multi-target operating overall result. The control steps comprises: data collecting; parameters setting; data screening; step-by-step optimizing; and instruction executing. The control method can give consideration to both of the user benefits and the electric power company benefits, and dramatically improves the economic benefit and the social benefit of the intelligent demand side, and meanwhile, the policy can be used in energy storage capacity planning and investment of the intelligent demand side in the initial period of construction so as to obtain the highest input/output ratio.

Abstract: This paper presents the study of a multi-pole exterior-rotor permanent magnet synchronous machine as a part of a hybrid drive for a small unmanned aircraft. The electric machine is designed to operate in generator or motor mode. Gramme's winding is used in the construction of the analysed machine. The paper covers the load test analysis of the electric machine in generator mode. Motor mode tests are neglected in this given paper. In the real aircraft, the generator output is rectified for supplying the on-board equipment, such as batteries and other electrical devices. Hence, the tests are carried out using active load. Based on test results, the corresponding load and short-circuit characteristic is compiled. In addition, the machine's analytical values of iron and copper losses are determined. Necessity of further study is pointed out.

Abstract: A power conversion system includes a maximum load current controller that is operable to limit a load current For example, in a power conversion system operating in a discontinuous conduction mode (DCM), the maximum load current controller limits the load current by determining an idle period in an active cycle for power switches of the maximum load current controller The maximum load current controller is optionally operable to approximate values for the time idle period that are substantially equal to theoretically calculated values

Abstract: The invention relates to a U-shaped resistor (1), in particular a low-resistance current-measuring resistor (1), comprising a first connection part (2) made of a conductive material having a first current contact surface for conducting an electrical current (I) into the resistor (1), and comprising a second connection part (3) made of a conductive material having a second current contact surface for conducting the current (I) out of the resistor (1), as well as comprising a resistor element (4) made of a resistor material, wherein the resistor element (4) is arranged in the direction of current flow between the first connection part (2) and the second connection part (3), such that the electrical current (I) flows through the electrical resistor (1). The current (I) perpendicularly enters or leaves the connections parts (2, 3) via their outer surfaces. In addition, the voltage taps are attached to the inner side of the U-shaped resistor (1), and contact the connection parts (2, 3) close to the transition to the resistor element (4).

Abstract: The present invention discloses a resistor circuit with temperature coefficient compensation, which comprises a first series resistor composed of a first resistor and a second resistor interconnected in series, and a second parallel resistor composed of a third resistor and a fourth resistor interconnected in series, with the first series resistor and the second parallel resistor interconnected in series, wherein the first resistor and the second resistor respectively have a positive and negative temperature coefficient and make the positive and negative temperature coefficients of the first series resistor offset each other, and the third resistor and the fourth resistor respectively have a positive and negative temperature coefficient and make the positive and negative temperature coefficients of the second parallel resistor offset each other.

Abstract: The invention provides a self-biased ultra wideband low-power-consumption low-noise amplifier (LNA) and belongs to the field of radio frequency integrated circuits The LNA only contains a low-frequency amplifier stage and a high-frequency amplifier stage At the low-frequency amplifier stage of the LNA, an active load is combined with the resistive negative feedback technology to provide bias for a circuit at the same stage and a circuit at a backward stage, self-bias of the overall LNA circuit is achieved, the circuit design is simplified, and circuit power consumption is restrained According to the structural features of the circuit, and high-frequency matching and noise performance of the circuit are optimized by fully utilizing parasitic inductance of bonding wires At the high-frequency amplifier stage, the working frequency range of the LNA is expanded through the inductance peaking technology The LNA can stably work within the frequency range of 02-6 GHz, and gain of 16+/-13 dB, the noise coefficient smaller than 2-8 dB and good input matching are maintained The self-biased ultra wideband low-power-consumption LNA can be applied to receiver front-end chips applied to digital broadcasting, wireless local area networks, ultrashort wave radars and other devices

Abstract: Grid connected photo voltaic system is emerging as reliable and sustainable solution in future renewable energy segment. General structure of solar photovoltaic array (SPVA) consist of PV cell which convert irradiation in to electrical energy and control the flow of converter that energy fed into the grid or load. This paper presents a control scheme for a grid connected voltage source converter (VSC) based on Synchronous reference frame theory (SRFT), Takagi Sugeno fuzzy logic control scheme (TSFLC) is developed to control DC link voltage and regulate it to its reference value. A Complete two stage grid-connected photovoltaic system consisting of PV array, DC to DC Boost converter, MPPT control algorithm, SRFT control scheme for VSC is designed and discussed. On sunny days, the system injects PV generated power to the load, remaining power required by the load will be provided by the grid. Hence SPVA and the grid system together process all the reactive and active load power. If the load requirement is less then PV generation the extra energy is fed to the grid. Simulation results show the validity of the PV system under various load conditions. The array is interfaced to the grid through power conditioning unit (PCU) to change output voltages and currents. The total harmonic distortion for various load conditions falls within two percentage in proposed control scheme.

Abstract: This paper presents a temperature-compensated CMOS current reference with low line regulation current mirror. The circuit is based on a bandgap reference voltage that achieves the temperature compensation of resistor by the negative temperature coefficient (TC) of a high-resistance polysilicon (HR poly) resistor with the positive TC of an n-well resistor. The low line regulation current mirror is implemented by using a negative feedback connected operational amplifier. Prototypes of 1 μA current reference from 0.35 μm CMOS process show a maximum temperature coefficient of 139 ppm/°C for a temperature range of 0---80 °C. The line regulation is reduced to 0.5 %/V for supply voltage of 3.5 to 5.5 V.

Abstract: A method of protecting a speaker from thermal damage includes determining a first load current through a first resistor that is coupled to the speaker. The method also includes converting the first load current to a digital value using a second load current through a second resistor as a reference input. The second resistor is part of a circuit that reduces an effect of a temperature coefficient of resistance of the first resistor. The method also includes comparing the digital value of the first load current to a threshold value. The method further includes, responsive to the first load current being larger than the threshold value, generating an instruction to take an action to protect the speaker.

Abstract: The Icelandic power network has transmission constraints that often lead to inter-area oscillations Although conventional stabilization methods have been applied successfully in the past, there is potential to exploit large industrial loads to enhance system stability during stringent operation conditions This paper analyzes the performance of two damping controllers The controllers can use both synchrophasor signals and local measurements as their inputs Damping is achieved by load modulation generated by a phasor-based oscillation signal Real-Time Software-in-the-Loop testing is performed using Opal-RT's eMEGAsim Real-Time Simulator to derive hardware and computational requirements of a hardware prototype that will be implemented in the future

Abstract: The invention discloses an ultrahigh-frequency radio frequency identification tag chip which at least comprises an ultrahigh-frequency active load modulation circuit, a passive load modulation circuit and a field intensity detection circuit, which are sequentially connected, wherein the ultrahigh-frequency active load modulation circuit comprises a carrier recovery circuit and an active emission circuit; the field intensity detection circuit is used for judging the relative distance between a tag and a reader. According to the ultrahigh-frequency radio frequency identification tag chip, the communication distance of a radio frequency identification system is increased; only the tag is needed to be replaced, the existing tag antenna design and application scenario design are retained to the greatest extent, and the power consumption of the circuits is saved; the ultrahigh-frequency radio frequency identification tag chip has an effect of effectively increasing the communication distance for active and semi-active ultrahigh-frequency radio frequency identification tags.