Simple Rectifier Research Articles

A single current sensor based adaptive step size MPPT control of a small scale variable speed wind energy conversion system

Due to the limited size and lower environmental impact, a small-scale wind energy conversion system (WECS) is a promising alternative for remote locations and residential areas where installing large wind turbines is not feasible. This system employs a permanent magnet synchronous generator (PMSG) as a variable speed wind generator due to its advantages such as high torque density, gearless, and require no external excitation, etc. This article proposes a single load current sensor-based adaptive step size (LCAS) maximum power point extraction (MPPT) method which utilizes the load current information to track the maximum power. This method does not require rotor speed information and knowledge of the turbine parameters. Also, this article uses a simple and cost-effective switch mode rectifier topology (AC–DC and DC–DC boost converters) for the PMSG-based variable speed WECS. The proposed method is validated in a 1.5 kW test rig using an OPAL-RT digital signal controller and also compared with various fixed step size (FSS) MPPT algorithms at various operating conditions. Extensive experimental work has been carried out for the LCAS MPPT method that confirms the tracking efficiency is better and tracking speed is faster along with the improved steady state as well as transient performance.

A Simple 24-Pulse Star Rectifier Combining Two Different Tap Converters

To further improve the harmonic mitigation capability of the double-star rectifier, a simple 24-pulse star rectifier using a conventional tap converter (CTC) and an improved tap converter (ITC) is proposed. The proposed rectifier comprises two double-star rectification units, a CTC, an ITC and an interphase reactor (IPR). The CTC and ITC first expand the double-star rectifiers into 12-pulse rectifiers, and provide a phase shift of 15°, then connect through an IPR to achieve the effect of quadrupling the number of pulses. This configuration solves the problem of limited pulse multiplication capability (pulse multiplication number≤3) of the existing passive tap converter, and upgrades the double-star rectifier to a novel 24-pulse star rectifier. The resulting rectifier shows an approximately sinusoidal input current with the absence of the 5th, 7th, 17th and 19th harmonics. The proposed scheme has the advantages of simple structure, small size, and being economically justified because the proposed scheme does not change the structure of the double-star transformer, and the capacity of CTC and ITC is only 3.49% and 6.29% of the output power, respectively. An experimental prototype with an output power of 1 kW is built to verify the correctness of the theoretical analysis.

Simple-Structure Active Lossless Decoupling Rectifier With Automatic PFC

One of the main challenges is how to prolong the lifetime of converters, and as in most single-phase converters the need for electrolytic capacitors. A simple structure rectifier is proposed with lossless buffer and power factor correction (PFC) abilities. It has the advantages of low cost, fewer auxiliary components, and high conversion efficiency. The active buffer circuit as an auxiliary unit consists of just one capacitor and one switch. It not only makes it possible for the rectifier to operate without electrolytic capacitors but also provides zero voltage switching (ZVS) for the buffer tank. Additionally, a simple control scheme is presented, in which near perfect power factor is obtained. Finally, the operating principles, control methods, and design guidelines are presented in detail, and the feasibility of the proposed converter is verified through a 58-W (48-V/1.2-A) hardware prototype. All the superior performances of the proposed rectifier are verified by the experimental prototype.

Fabrication and output performance of triboelectric nanogenerator from helical structure of biodegradable polylactic acid by 3D printing

In this study, a helical triboelectric nanogenerator (H-TENG) based on the helical structure of biodegradable polylactic acid was designed using 3D printing technology to achieve energy acquisition. When the H-TENG is pressed rhythmically with one hand, the output open-circuit voltage, short-circuit current and charge transfer density can reach 395 V, 28 μA and 36 μC/m2 respectively, which can light 300 LEDs in series. By connecting a simple rectifier and selecting a suitable capacitor, the H-TENG can independently and stably power portable electronic products, such as digital watches and calculators. Especially, as an electronic switch, the device enabled a high current amplification through the Darlington transistor circuit. These results demonstrated the potential applications of the H-TENG in biomechanical energy collection, sensing and human-machine interaction.

Fabrication and experimental study of transformer 400 V with a simple rectifier circuit design

The demand for increased voltage in renewable energy sources is relatively high. This study examines the rapid development of technology considering the use of voltage-increasing transformers. Voltage regulator circuits are generally used to stabilize the output voltage of the rectifier according to the amount of input from the transformer. However, components for high-voltage stabilizer circuits are rare, which becomes an obstacle to the stabilization of the rectifier output. This study aimed to determine the performance of the designed rectifier circuit against a non-center tap step-up direct current (DC) 400 V transformer and compare the measurement results to manual calculations. The research method is a direct comparison between the input and output voltage values of the transformer after going through a rectifier circuit. This experiment was conducted using the repeatability method three to five times for each voltage variation on the transformer. The voltage variations successfully created are 0 to 50, 0 to 100, 0 to 200, and 0 to 400 V. The output test results from the DC transformer and rectifier circuit show linear results and an increase in peak-to-peak voltage data between the transformer and rectifier outputs by 3.8%.

Design and Implementation of a Simple and Low-Cost Rectifier Circuit for Efficient Rectenna Harvesting System at 2.4 GHz Based on Moss Rose Optimization Algorithm

In this paper, a design and implementation of a simple, low cost, efficient rectifier circuit is proposed to eliminate the need for the usual complicated impedance matching network in rectenna harvesting systems. The proposed rectifier circuit consists of a Schottky diode and LC components only. The design is optimized based on the Moss Rose Optimization Algorithm (MROA), which is programmed by using the MATLAB software and then simulated by the Advance Design System (ADS) software. The simulation procedure for finding the rectifier circuit elements using MATLAB is implemented by rewriting the simulation software in C language and utilizing the Mikroelectronica development tool. It is shown that the obtained LC values at 2.4 GHz have offered a minimum value of reflection coefficient (about -38 dB) under stable conditions. The obtained results are compared with some previous works that have used rectenna systems with impedance matching elimination network, and it is found out that the proposed design offer the lowest reflection coefficient.

A 24-Pulse Rectifier With a Passive Auxiliary Current Injection Circuit at DC Side

In this article, a simple series-connected 24-pulse rectifier with a passive auxiliary current injection circuit (ACIC) is proposed. The proposed rectifier consists of a 12-pulse rectifier and an ACIC. The ACIC includes a circulation current forming circuit, an auxiliary single-phase transformer (AST), and an auxiliary single-phase full-bridge rectifier (ASFR). The ASFR extracts alternating square-wave current from the dc side and injects it into the outputs of three-phase rectifier bridges to increase the output state of these bridges. The operating mode of the proposed rectifier is analyzed, and the functional relationship between the input current and turns ratio of AST is established. The AST turns ratio that minimizes the input line current total harmonic distortion (THD) is derived. The voltage and current rating of AST are calculated, and the design method of capacitors C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> in ACIC is given. Under the optimal turns ratio, the ACIC extends the 12- to a 24-pulse rectifier. The resulting 24-pulse rectifier draws near-sinusoidal input currents with less than 5% THD. The AST in ACIC has a very low kilovolt-ampere rating (1.96% <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ), and the current ratings of ASFR are small. The theoretical analyzes are provided and experimentally verified using a 1.7 kW experimental prototype.

A Simple 24-Pulse Rectifier Employing an Auxiliary Pulse-Doubling Circuit

A simple 24-pulse rectifier that provides low-harmonic utility power interface is proposed in this article. The proposed 24-pulse rectifier consists of a 12-pulse rectifier using a zigzag phase-shifting transformer and an auxiliary pulse-doubling circuit (APDC). Two auxiliary diodes in the APDC extract specific rectangular currents from the dc side of the rectifier to modulate and increase the output states of three-phase rectification bridges first, and then the 12-pulse rectifier is extended to a 24-pulse rectifier in accordance with the current relationship between ac and dc sides. The main low-order harmonics, such as 11th and 13th, are reduced markedly from the input line current and the proposed rectifier draws near-sinusoidal input line currents with less than 5% THD from the utility. The maximum current flowing through the two auxiliary diodes in APDC is only 3.4% of the load current and the capacity of APDC is only 3.06% of the output power. Thus, the proposed scheme is inexpensive and easy to implement and has a simple circuit configuration. Theoretical analyses were experimentally verified using a 1.7-kW experimental prototype.

A Simple 18-Pulse Star Rectifier Using Two Passive Auxiliary Circuits at DC Link

In this article, a simple 18-pulse star rectifier using two new passive auxiliary circuits at dc link is proposed for reducing the harmonics content in ac line current. The proposed rectifier combines a double-star rectifier and four-tapped interphase reactor (FTIPR) with four diodes. Passive auxiliary circuits increase the state of the output voltage and current of the double-star rectifier, thereby increasing the pulse number of the load voltage and step number of the input line current. When FTIPR is optimally designed, passive auxiliary circuits convert double-star rectifier to 18-pulse star rectifier. Tap ratios of the FTIPR are determined based on minimum total harmonic distortion (THD) of the input line current and minimum ripple of the output voltage. The proposed rectifier simultaneously reduces ripple of the output voltage and THD of the input line current. A prototype is developed to verify the theoretical analysis through experimental results. Theoretical THD of the input line current is about 10.1%, whereas experimental THD is about 5.44%.

A high rectification efficiency Si0.14Ge0.72Sn0.14-Ge0.82Sn0.18-Ge quantum structure n-MOSFET for 2.45 GHz weak energy microwave wireless energy transmission

The design strategy and efficiency optimization of a Ge-based n-type metal–oxide–semiconductor field-effect transistor (n-MOSFET) with a Si0.14Ge0.72Sn0.14–Ge0.82Sn0.18–Ge quantum structure used for 2.45 GHz weak energy microwave wireless energy transmission is reported. The quantum structure combined with δ-doping technology is used to reduce the scattering of the device and improve its electron mobility; at the same time, the generation of surface channels is suppressed by the Si0.14Ge0.72Sn0.14 cap layer. By adjusting the threshold voltage of the device to 91 mV, setting the device aspect ratio to 1 μm/0.4 μm and adopting a novel diode connection method, the rectification efficiency of the device is improved. With simulation by Silvaco TCAD software, good performance is displayed in the transfer and output characteristics. For a simple half-wave rectifier circuit with a load of 1 pf and 20 kΩ, the rectification efficiency of the device can reach 7.14% at an input power of –10 dBm, which is 4.2 times that of a Si MOSFET (with a threshold voltage of 80 mV) under the same conditions; this device shows a better rectification effect than a Si MOSFET in the range of –30 dBm to 6.9 dBm.

Metamaterial-Integrated High-Gain Rectenna for RF Sensing and Energy Harvesting Applications.

This paper presents a metamaterial (MTM)-integrated high-gain rectenna for RF sensing and energy harvesting applications that operates at 2.45 GHz, an industry, science, medicine (ISM) band. The novel MTM superstrate approach with a three-layered integration method is firstly introduced for rectenna applications. The integrated rectenna consists of three layers, where the first layer is an MTM superstrate consisting of four-by-four MTM unit cell arrays, the second layer a patch antenna, and the third layer a rectifier circuit. By integrating the MTM superstrate on top of the patch antenna, the gain of the antenna is enhanced, owing to its beam focusing capability of the MTM superstrate. This induces the increase of the captured RF power at the rectifier input, resulting in high-output DC power and high entire end-to-end efficiency. A parametric analysis is performed in order to optimize the near-zero property of the MTM unit cell. In addition, the effects of the number of MTM unit cells on the performance of the integrated rectenna are studied. A prototype MTM-integrated rectenna, which is designed on an RO5880 substrate, is fabricated and characterized. The measured gain of the MTM-integrated rectenna is 11.87 dB. It shows a gain improvement of 6.12 dB compared to a counterpart patch antenna without an MTM superstrate and a maximum RF–DC conversion efficiency of 78.9% at an input RF power of 9 dBm. This results in the improvement of the RF–DC efficiency from 39.2% to 78.9% and the increase of the output DC power from 0.7 mW to 6.27 mW (a factor of 8.96 improvements). The demonstrated MTM-integrated rectenna has shown outstanding performance compared to other previously reported work. We emphasize that the demonstrated MTM-integrated rectenna has a low design complexity compared with other work, as the MTM superstrate layer is integrated on top of the simple patch antenna and rectifier circuit. In addition, the number of MTM units can be determined depending on applications. It is highly envisioned that the demonstrated MTM-integrated rectenna will provide new possibilities for practical energy harvesting applications with improved antenna gain and efficiency in various IoT environments.

Design of a Medium Voltage Generator with DC-Cascade for High Power Wind Energy Conversion Systems

This paper shows a new concept to generate medium voltage (MV) in wind power application to avoid an additional transformer. Therefore, the generator must be redesigned with additional constraints and a new topology for the power rectifier system by using multiple low voltage (LV) power rectifiers connected in series and parallel to increase the DC output voltage. The combination of parallel and series connection of rectifiers is further introduced as DC-cascade. With the resulting DC-cascade, medium output voltage is achieved with low voltage rectifiers and without a bulky transformer. This approach to form a DC-cascade reduces the effort required to achieve medium DC voltage with a simple rectifier system. In this context, a suitable DC-cascade control was presented and verified with a laboratory test setup. A gearless synchronous generator, which is highly segmented so that each segment can be connected to its own power rectifier, is investigated. Due to the mixed AC and DC voltage given by the DC-cascade structure, it becomes more demanding to the design of the generator insulation, which influences the copper fill factor and the design of the cooling system. A design strategy for the overall generator design is carried out considering the new boundary conditions.

Simple Adaptive Rectifier with High Efficiency over a Range of 21 dBm Input Power for RF Energy Harvesting Applications

This paper presents a novel simple adaptive and efficient rectifier for Radio Frequency (RF) energy harvesting applications. Traditional rectifiers have maximum RF-DC Power Conversion Efficiency (PCE) over a narrow range of RF input power due to diode breakdown voltage restrictions. The proposed adaptive design helps to extend the PCE over a wider range of RF input power at 2.45GHz using a simple design. Two alternative paths arecontrolled depending on the RF input power level. Low input power levels activate the first path connected to a single rectifier; low power levels make the diode operate below its breakdown voltage and therefore avoiding PCE degradation. High input power levels activate the second path dividing it into three rectifiers. This keeps input power at each rectifier at a low power level to avoid exceeding the diode break down voltage. Simulated PCE of this work is kept above 50% over a range of 21.4 dBm input power from -0.8dBm to 20.6dBm.

A Simple 36-Pulse Diode Rectifier With Hybrid Pulse Multiplication Interphase Reactor at DC Side

A simple and robust 36-pulse diode rectifier which consists of a conventional 12-pulse rectifier and a hybrid pulse multiplication interphase reactor (HPM-IPR) is proposed in this article. The HPM-IPR includes a modified interphase reactor (M-IPR), an auxiliary single-phase full-bridge rectifier (ASFBR), and an auxiliary single-phase full-wave rectifier (ASFWR). The ASFBR is connected in series with the load to modulate the output current of the rectifier bridges directly. The ASFWR is connected in parallel to shape the output current of the rectifier bridges indirectly. The conjoint modulation of ASFWR and ASFBR significantly increases the number of output current states of the rectifier bridge, which in turn extends the conventional 12-pulse operation to 36-pulse operation. The proposed 36-pulse diode rectifier draws near the sinusoidal input line currents with THD less than 5%. The kVA ratings of ASFBR and ASFWR are only 1.1% and 1.8% of the output power of the proposed rectifier, respectively, which indicates that the proposed method is suitable for high-power industrial applications. Since only one ASFWR and one ASFBR are adequate, the proposed scheme is low cost, highly reliable, and simple. The detailed analysis is presented, and some experimental results are provided to verify the proposed method.

Fabry-Perot cavity amplification of near-field thermal rectification

We design a thermal rectifier based on near-field thermal radiation between a p-type lightly doped silicon bulk (p-LDSi) and a Fabry-Perot (F-P) cavity, made of alternating metal films and p-LDSi films on metal substrate. Our results show that the introduction of F-P cavity arouses markedly near-field thermal rectification ratio owing to the selective emittance and absorption. Significantly, the performance of the designed rectifier exceeds the simple rectifier between the p-LDSi substrate and the metal substrate. Meanwhile a good rectification ratio can still be achieved at a large vacuum gap. Furthermore, in order to solve the multidimensional optimization difficulties often encountered in designing thermal rectifier devices, the sequential quadratic programming (SQP) is employed to build the optimal reconstruction scheme by solving the inverse problem for the thermal rectifier. This paper exploits a new lane to improve the performance of thermal rectifiers, and may have wide applications in thermal management of microchip.

BaTiO3 assisted PAN fiber preparation of high performance flexible nanogenerator

Recently, polyacrylonitrile (PAN) fiber films have shown greater advantages over polyvinylidene fluoride (PVDF) in the field of energy harvesting. Adding other substances with high piezoelectric coefficient is worth exploring to further improve the output voltage of PAN. Here, we successfully dispersed high dielectric constant barium titanate in PAN nanofiber films with different dosages using an electrospinning technology. The X-ray diffraction and Fourier transform infrared spectroscopy results indicated that BaTiO3 nanoparticles aid in transforming PAN from a 31-helical conformation to a planar zigzag conformation, thus improving the output voltage of PAN nanofibers significantly and also promoting its mechanical properties. In addition, the human body function monitoring experiment showed a good response current to the rhythm of elbow bending, knee bending, running, and breathing. Besides, when a simple rectifier circuit was applied, the capacitor could be charged to 2 V in less than 2 min and light a commercial LED through repeated tapping.

Energy harvesting wireless sensor for achieving self-powered structural health monitoring system

PurposeOn average, a medium-sized satellite consist of almost 500 sensors where powering these sensors in space in such an unreachable environment is critical. Backing this, a compact energy harvester for powering up distant sensors is discussed here is the purpose of this paper. This is in line with the geostationary satellite-powered using the available electromagnetic energy on the satellite panels in space.Design/methodology/approachThe designed rectenna makes use of a compact wideband receiving antenna operating at the targeted frequency band from 8 to 18 GHz. It also consists of a simple dual diode rectifier topology with a matching circuit, bandpass filter and a resistive load to convert the received radio frequency energy into usable direct current (DC) voltage.FindingsThe rectenna measurement is performed using three different configuration setups. This shows that a maximum DC voltage of 1.8 V and 5-10 mV is harvested from rectifier and rectenna (includes antenna and rectifier) when 20 dBm power is transmitted from the transmitting antenna operating at X and Ku band. This makes the rectenna feasible to power wireless sensors in a structural health monitoring system.Originality/valueThe measurements are performed by considering a real-time environment in space in terms of the distance between the transmitting and receiving antenna, which depends on the far-field of the transmitting antenna in a satellite.

Performance and Analysis of a New Brushless Synchronous Generator for DC Microgrid Application

DC grid is gaining popularity as different renewable energy sources and energy storage elements used to form the microgrid are dc in nature. Moreover, HVdc systems have been found to be advantageous for off-shore wind farms. For such systems located in remote places, maintenance becomes a key issue, which makes the use of brushless generator preferable. Very recently, a new synchronous generator with embedded brushless synchronous exciter has been reported. This work explores the performance of such generators for dc microgrid application. A simple diode rectifier is used to interface the generator to the dc grid. Such uncontrolled rectifier will cause current quality issues. A passive tuned filter can help in mitigating this issue and also assist in improving the voltage regulation by providing reactive power support. A method to select the right filter parameters has been proposed. Simulation results obtained from MATLAB/Simulink and experimental results from a fabricated laboratory prototype have been presented. Both simulation and experimental results reveal the effectiveness of the proposed system.

Diagnosis of Rotor Asymmetries Faults in Induction Machines Using the Rectified Stator Current

Fault diagnosis of induction motors through the analysis of the stator current is increasingly being used in maintenance systems, because it is non-invasive and has low requirements of hardware and software. Nevertheless, its industrial application faces some practical limitations. In particular, the detection of fault harmonics that are very close to the fundamental component is challenging, as in large induction motors working at very low slip, because the leakage of the fundamental can hide the fault components until the damage is severe. Several methods have been proposed to alleviate this problem, although all of them increase noticeably the complexity of the diagnostic system. In this paper, a novel method is proposed, based on the analysis of the rectified motor current. It is shown that its spectrum contains the same fault harmonics as the spectrum of the original current signal, but with a much lower frequency, and free from the fundamental component leakage. Besides, the proposed method is very easy to implement, either by software, using the absolute value of the current samples, or by hardware, using a simple rectifier. The proposed approach is presented theoretically and validated experimentally with the detection of a broken bars fault of a large induction motor.

Effective Utilization of Parallel-Connected Megawatt Three-Level Back-to-Back Power Converters in Variable Speed Pumped Storage Units

Power electronic converter plays a significant role in the hydropower generating systems of both fixed and variable speed types. These converters are used in the form of a simple rectifier for the static dc excitation in the fixed speed system and in the form of the ac excitation (ac–ac or ac–dc–ac) in the variable speed system. The parallel-connected multiple three-level neutral-point-clamped (3L-NPC) megawatt back-to-back (BTB) converters have been adopted in recently commissioned variable speed pumped storage units (VSPSU). For such configurations, reliability and efficiency are considered to be prominent. This article proposes a methodology for effective utilization of a parallel-connected BTB power converter for VSPSU of large capacity by performing the load-dependent activation /deactivation of converters. A vector control strategy for the active and reactive power deliveries of VSPSU is formulated. This article also focusses on the losses and thermal behavior of converters at different speeds of generator in accordance with water head variations. The proposed control system is designed in such a way to decrease overall losses in the power converter system. The effectiveness of the proposed method is explained on a real scale of 250-MW doubly fed induction machine with 5 × 5 MW power converters using MATLAB/PLECS software, and experimental validation is performed through a downscaled 2.2-kW laboratory prototype.