Constant Current Output Research Articles

Multi‐objective optimization of inductive power transfer system with reconfigurable topology for misalignment tolerance

AbstractAt present, most of the analyses or studies about inductive power transfer (IPT) with constant current (CC) output and constant voltage (CV) output are carried out without considering misalignment conditions or different gaps. An IPT system satisfying battery charging demand and anti‐misalignment requirements simultaneously is infrequent. This paper proposes a multi‐objective particle swarm optimization method of IPT reconfigurable topology to realize CC and CV modes at varying resistance conditions and wide coupling ranges. The output characteristics of an inductor–capacitor–capacitor (LCC)–LCC compensation circuit have been explored, and it is found that the secondary‐side compensated capacitors have a greater impact on the output power, which can be used to improve power regulation ability accompanied by coupling varying. Eight optimization compensated parameters of the reconfigurable topology are obtained from the Pareto front to achieve the required CC and CV charging outputs. By switching the compensated capacitors, the selected parameters can make the current and voltage fluctuation less than 9.3% and 7.9%, respectively, during the coupling charging range from 0.3 to 0.22. Moreover, primary zero voltage switching operation is achieved to enable high efficiency. The simulation and the experimental verification are carried out to verify the validity of the proposed method.

A Decoupled Modulation Strategy for Constant Voltage/Current Wireless Charging System Under High Coils Misalignment

ABSTRACTOutput fluctuation and lower transmission efficiency under load and mutual inductance variation are hot concerned in the wireless charging system for power batteries. In this paper, a decoupled tracking strategy is proposed to realize constant voltage (CV) or current (CC) output and high transmission efficiency. The circuit model of series–series compensation network is built, and corresponding transmission characteristics can be derived. First, the load and mutual inductance value can be estimated by measuring the primary electrical information, including the inverter output voltage, current, and the phase error between them. Then load‐independent voltage or current output characteristics under coils misalignment can be maintained by tracking the optimal switching frequency of inverter part. In addition, the value of output voltage or current can be adjusted flexibly for different operation occasions by the employment of pulse‐width modulation. As a result, the load‐independent output characteristics realization and output adjustment can be decoupled. Based on only the primary measuring information, the CV/CC output can be maintained via the proposed hybrid control strategy when the coils misalignment and load variation happen, increasing the robustness of whole wireless power transfer (WPT) system. Furthermore, the soft switching of all power switches in the inverter part can be realized to reduce the switching loss. Compared with previous research, the proposed wireless charging system has a higher power density and a simplified control strategy. Finally, an experimental platform with 60‐V charging voltage and 3.6‐A charging current is built to verify the feasibility of the proposed sys‐tem and control method.

A Reconfigurable IPT System With CC‐CV Output Characteristics and High Misalignment Tolerance

ABSTRACTMisalignment between transmission coils is an inevitable challenge in inductive power transfer (IPT) systems, particularly affecting the constant current (CC) and constant voltage (CV) outputs essential for battery charging. A reconfigurable IPT system with high misalignment tolerance and CC‐CV output characteristics is proposed in this article. The main circuit of the system is composed of a LCC‐LCC and LCC‐S topology with two intermediate coils, and two switches equipped with single unidirectionally blocking MOSFETs are incorporated on the secondary side to transition from CC to CV mode. A comprehensive analysis of the output characteristics for the proposed hybrid topology in both CC and CV modes is provided. Furthermore, the parameter optimization design based on BP coil for wide misalignment tolerance is presented. The experimental results demonstrate that the proposed reconfigurable IPT system can maintain stable CC and CV outputs within 50% lateral and vertical offset (the coupling factor varies from 0.1 to 0.21), when the load varies from 11 to 80 Ω, and the output current and voltage fluctuations remain below 5%.

Extending the design space of minimized VA rating inductive wireless power transfer links operating in restricted sub-resonant frequency region with constant current output

Wireless power transfer systems are typically required to operate under varying geometrical positioning (vertical distance, misalignment) between the transmitter and receiver coils while supporting a load with non-constant characteristics. This creates the need for robust systems that can operate over a range of coupling coefficients under time-varying load. Widespread control methods utilized to support such an operation typically suffer from volt-ampere (VA) over-rating of the inductive wireless power transfer link (IWPTL) transmitter. Sub-resonant frequency control has proven to be an effective solution to this problem, attaining robust operation and minimized transmitter VA rating by utilizing operational frequency as the control variable for system output regulation under above-mentioned constraints. However, allowed operating frequency range is usually restricted in practical applications (e.g. to 79 kHz–90 kHz by SAE J2954 EV charging standard), limiting the misalignment tolerance of sub-resonant control method. Recently, extension of the classical sub-resonant control methodology was proposed in order to overcome this limitation. However, no clear guidelines were given for designing practical IWPTLs operating under extended sub-resonant control. To this end, this work bridges the gap between academical findings and practical applications by establishing generalized guidelines for designing sub-resonant controlled series-series (SS) compensated IWPTL with minimized transmitter VA rating, allowing to maximize misalignment tolerance under given operating frequency and output voltage ranges. The proposed methodology is accurately validated by simulations and experiments, demonstrate close correlation with analytical predictions. Experimental framework reveals that IWPTL operating under extended sub-resonant control methodology attains 50 % increase of tolerable coupling coefficients range compared to a classical system designed to operate under sub-resonant control under identical operating conditions while achieving nearly similar DC-to-DC efficiency.

An Integrated Double-Sided LCC Compensation Based Dual-Frequency Compatible WPT System with Constant-Current Output and ZVS Operation

This article presents an integrated double-sided inductance and double capacitances (DS-LCC) compensation based dual-frequency compatible wireless power transfer (WPT) system. A cascaded single-phase multi-frequency inverter (CSMI) is constructed to generate the independent dual-frequency power transfer signals. In order to achieve the load-independent constant-current output (CCO) at two frequencies, an integrated DS-LCC compensated topology is reconstructed. By configuring the frequency-selective resonating compensation (FSRC) network in the primary side, the power transfer signals at two frequencies can be superimposed into a single transmitting coil, reducing the cost and volume of the system. Furthermore, to implement zero-voltage switching (ZVS) of the CSMI throughout the entire power range, a general parameter design method of the proposed system is also introduced. A 1.5-kW experimental prototype is built to validate the practicability of the presented dual-frequency compatible WPT System. The system can supply power to different loads at two frequencies simultaneously with CCO and ZVS properties. The peak efficiency reaches 91.75% at a 1.2-kW output power.

A Dual Constant Current Output Ports WPT System Based on Integrated Coil Decoupling: Analysis, Design, and Verification

With the high integration of power electronic devices, wireless power transfer (WPT) systems are required to have output characteristics of different specifications that are independent of the load. However, existing methods for realizing dual-output WPT systems have problems such as complex circuits, cumbersome control schemes, low system stability, insufficient system space utilization, and unnecessary cross-coupling. Therefore, in order to solve the above problems, this paper proposes a dual-receiver WPT system with dual constant current (CC) output based on an integrated decoupling coil. In this system, the DD coil is wound vertically in series with the solenoid coil and serves as the first receiving coil to achieve energy transmission in the system. While the solenoid coil is used in the transmitting coil and the second receiving coil, and the coils are perpendicular to each other to achieve natural decoupling. Furthermore, the receiving coils are integrated together on the receiving side ferrite plate. Therefore, there is no cross-coupling interference in the system, which simplifies the system design. Firstly, the natural decoupling characteristics of the magnetic coupler and the coil optimization method are analyzed in detail theoretically. Secondly, a detailed mathematical analysis is performed on the dual CC output characteristics with different specifications that are load-independent and have zero phase angle operation. Again, the zero voltage switching of the inverter can be achieved by changing the compensation component parameters through simulation verification. Finally, a prototype with a rated power of 283 W is constructed for validation purposes. The first receiver delivers a CC output of 3 A, while the second receiver provides a CC output of 4 A, with the DC–DC conversion efficiency reaching a peak of 90.2%. The experimental results confirm the accuracy of the theoretical analysis.

Research and design of multi‐stage multi‐load wireless power supply system for high voltage online monitoring equipment

AbstractMany online monitoring devices in substations are placed at high potential differences from the ground, and it is not possible to supply power to these devices directly from the ground through wires. Placing magnetically coupled structures inside the substation pillar insulators for inductive power transfer is considered a feasible solution, and at this stage of research, systems that add multi‐stage repeating coil structures are mostly used to achieve stable power supply for individual online monitoring devices. However, the monitoring point generally requires multiple devices to monitor together, and the power requirements of different devices are different, so adding multiple repeating coils at the same time will increase the complexity of the system design, which is not conducive to engineering applications. Therefore, this paper designs and optimizes a multi‐stage multi‐load wireless power supply system magnetic coupling structure, using a three‐dimensional hollow solenoid combined with a ferrite core as the system repeating coil structure and an embedded magnetic coupling structure as the receiver end structure to reduce the number of system repeating coils while supplying power to devices with different power requirements. A prototype with a transmission distance of 1.02 m was built in the experiment, and the experimental results showed that the highest transmission efficiency of the system was 44.3% and 39.2% under single load and double load conditions, respectively. As the load resistance increases, the system can achieve constant voltage output under both single‐load and dual‐load operating conditions. Adjusting the number of turns of the receiving coil can change the output characteristics of the system and achieve constant voltage output of different voltage levels or constant current output of different current levels, which can meet the power supply needs of different loads.

Analysis and design of a three‐coil IPT system with independent dual output ports

AbstractIndustrial applications tend to involve a substantial assemblage of electronic devices, and it is imperative to consider diverse charging requirements while charging these devices. This paper proposes a three‐coil single‐input‐and‐dual‐output (SIDO) inductive power transfer (IPT) system to meet the charging requirements of different devices. The system includes two independent output ports, providing constant voltage (CV) output and constant current (CC) output for different loads, respectively. In addition, the zero‐phase angle (ZPA) operation can be achieved, thus avoiding injection of reactive power and improving energy transfer efficiency. Unlike previous related studies, the receiver of the proposed SIDO IPT system only includes one receiving coil to pick up energy, eliminating unnecessary cross‐coupling and complex decoupling circuits in traditional IPT systems with multiple outputs. This study first analyzes the CC/CV output theory of the proposed SIDO IPT system in detail, and designs and optimizes the parameters by establishing an equivalent model. Then, the conditions for achieving zero‐voltage switching (ZVS) operation of the inverter are obtained by analyzing the sensitivity of CC/CV performance to the variation of the compensation capacitors. Finally, a verification experimental prototype with 2.5A CC output and 72 V CV output is established to verify the effectiveness of the proposed IPT system.

A Constant Current Output Method for Low-Voltage and High-Current DWPT Systems Based on Inverse Coupled Current Doubler Rectifier

A Constant Current Output Method for Low-Voltage and High-Current DWPT Systems Based on Inverse Coupled Current Doubler Rectifier

Hybrid dual-mode high-output triboelectric nanogenerator for achieving alternating current/direct current collaborative output

The large-scale practical application of triboelectric nanogenerators (TENGs) mainly depends on the limitations of output performance. On the basis of previous theory, this paper proposes a comprehensive strategy on the coupling of triboelectrification, corona discharge, volume effect, and space volume utilization of charge capture to enhance TENGs’ output. Thereby, a hybrid dual-mode high-output TENG (HDH-TENG) is proposed to efficiently harvest natural mechanical energy through a rotation-driven sliding-TENG (RS-TENG) and a magnetic-driven contact-separation TENG (MC-TENG). The simplified sliding-TENG with the combination of PU foam and vertical-radial electrodes achieves AC/DC collaborative output with charge density of 173.3 and 175.2 µC m−2, respectively. The simplified contact-separation TENG with the PU foam achieves AC output with charge density of 108.8 µC m−2. Furthermore, the integrated RS-TENG and MC-TENG achieve efficient collaborative output of DC with power density of 6.4 W m−2 Hz−1 and AC with power density of 128.6 mW m−2 Hz−1 through persistent directional sliding and contact separation, respectively, where a record-high constant current density output reached 1.9 mA m−2 Hz−1. The HDH-TENG can drive 6575 LEDs and 12 incandescent lamps, and continuously and stably power 52 hygrothermographs. This work further provides a new strategy for charge density enhancement of TENGs.

Three-Coil Wireless Charging System Based on S-PS Topology

To protect the battery, radio energy transmission charging typically uses constant current (CC) charging before switching to constant voltage (CV) charging to enhance battery durability. This paper proposes adding an auxiliary clamp coil to the original circuit topology. The IPT battery charger designed with the auxiliary clamp coil can achieve both constant current (CC) and constant voltage (CV) outputs. The mutual inductance between the auxiliary clamp coil and the primary side coil greatly influences the output performance of the entire IPT system, so the auxiliary clamp coil should not be too large. To solve this problem, an S-S-PS circuit with secondary compensation topology in the secondary coil is proposed. This circuit topology reduces the size of the auxiliary clamp coil, allowing it to be placed in an optimal position. When the constant voltage output critical position is reached, the IPT system can still automatically, continuously, and smoothly switch between CC and CV modes. Consequently, this approach avoids increased cost consumption associated with detecting CC-CV switching thresholds, adding wireless transmission communication modules, real-time control of the power transmitter, and active protection of the circuit during constant current charging. Finally, a 48 V/2.5 A prototype was built to verify that the IPT system has CC-CV conversion functionality.

Fully Integrated Direct Current Triboelectric Nanogenerators Coupled with Charge Pump and Electric Field Enhancing Effect Enabling Improved Output Performance

AbstractDirect‐current triboelectric nanogenerators (DC‐TENGs) arising from electrostatic breakdown have garnered significant attention due to their advantages of rectification‐free operation, constant current output, and high output power density. Previous studies have primarily concentrated on improving its performance through structural design and parameter optimization, neglecting the potential benefits of external charge excitation. Here, a facile and universal strategy coupling charge pump and electric field enhancing effect with DC‐TENG (CE‐DC‐TENG) is proposed to improve the output performance of DC‐TENG. An alternating current TENG is used as the charge pump. A field‐enhancing conductive layer, which is introduced under the main DC‐TENG, is connected with the pump TENG to accumulate the charge and enhance the electric field for electrostatic breakdown. The effectiveness of this method is demonstrated by linear and rotary sliding mode TENGs. Furthermore, a fully integrated rotary sliding mode CE‐DC‐TENG is designed and fabricated, and it exhibits impressive performance with a 13‐fold higher power density of 1.56 W m−2 compared to conventional DC‐TENG. Moreover, it can directly power small electronics or be combined with a designed power management circuit for more efficient energy conversion. This work presents a new design strategy for improving the performance of DC‐TENG and facilitating its practical applications.

Wireless Charging System With Dual Switchable Constant Voltage and Constant Current Outputs Based on Intermediate Coils

Wireless Charging System With Dual Switchable Constant Voltage and Constant Current Outputs Based on Intermediate Coils

Analysis and design of wireless power transfer system with anti-misalignment constant voltage output characteristics

PurposeThis study aims to solve the problem of high output voltage fluctuation and low efficiency caused by the misalignment of the magnetic coupling structure in the wireless charging system for electric vehicles. To address these issues, this paper proposes a dual LCC-S wireless power transfer (WPT) system based on the double-D double-layer quadrature (DDDQ) coil, which can realize the anti-misalignment constant voltage output of the system.Design/methodology/approachFirst, this paper establishes the equivalent circuit of a WPT system based on dual LCC-S compensation topology and analyzes its constant-voltage output characteristics and the relationship between system transmission efficiency and coupling coefficient. 1. Quadruple D (Ahmad et al., 2019) and double-D quadrature pad (DDQP) (Chen et al., 2019) coils have good anti-misalignment in the transverse and longitudinal directions, but the magnetic induction intensity in the center of the coils is weak, making it difficult for the receiving coil to effectively couple to the magnetic field energy. 2. Based on the double-D quadrature (DDQ) structure coil that can eliminate the mutual inductance between coupling coils and cross-coupling, Gong et al. (2022a) proposed a parameter optimized LCC-LC series-parallel hybrid topology circuit, which ensures that the output current fluctuation is controlled within 5% only when the system is misaligned within the 50% range along the X direction, achieving constant current output with anti-misalignment. The magnetic coupling structure’s finite element simulation model is established to analyze the change in magnetic induction intensity and the system’s anti-misalignment characteristics when the coil offsets along the x and y axes. Finally, an experimental prototype is developed to verify the constant voltage output performance and anti-misalignment performance of the system, and the proposed anti-misalignment system is compared with the systems in existing literature, highlighting the advantages of this design.FindingsThe experimental results show that the system can achieve a constant voltage output of 48V under a time-varying load, and the output voltage fluctuates within ±5% of the set value within the range of ±60 mm lateral misalignment and ±72 mm longitudinal misalignment.Originality/valueBased on the dual LCC-S WPT system, the mutual inductance between the same side coils is reduced by adding decoupling coils, and the anti-misalignment characteristics and output power of the system are improved in a certain range. It is aimed at improving the stability of the system output and transmission efficiency.

Optimization stability and performance of the TPS storage ring dipole magnet power supply

This article focuses on the current status of the dipole magnet power supply (DMPS) and improvement in the Taiwan Photon Source (TPS) storage ring. The DMPS provides a stable and precise magnetic field for the storage ring operation. Appropriate wiring methods are employed to minimize magnetic field interference across the entire TPS area to meet the demands of high-energy output and overcome the challenges of operating at high currents. The target energy is set at 850 V and 750 A, utilizing a single-pole switching voltage regulator as a high-precision constant current source output structure. The system incorporates a closed control loop that uses the Direct Current Current Transducer (DCCT) to provide current signal feedback to the system. FPGA (Field-Programmable Gate Array) calculates PID (Proportional-Integral-Derivative) compensation values, generating a 2.1 kHz pulse width modulation (PWM) signal to regulate the output current. At the same time, insulated gate bipolar transistor (IGBT) modules are switching components. However, even after several years of practical operation, the stability and performance of the DMPS in the storage ring still require improvements. To enhance long-term output current stability and address peripheral issues, the current TPS utilizes the Beam Orbit Feedback (FOFB) system to suppress and fine-tune the magnetic field and compensate for the impact of temperature drift on the DMPS's output current. This improvement ensures a more stable circulation of the photon beam within the storage ring. By optimizing the temperature control circuit of the main control card, the long-term output current stability has been successfully enhanced to within ± 10 ppm. Simultaneously, the FOFB system reduces uncertainties in adjusting the X-axis beam position, improving beam stability and quality. Furthermore, relevant protective measures have been implemented to ensure robust system operation. Ultimately, these improvement measures have successfully met TPS's stringent requirements for the DMPS, enabling the synchrotron accelerator light source to operate at higher performance levels and fostering advanced scientific research. The results of these upgrades underscore the success of the power supply enhancements, making significant contributions to the overall improvement of the Taiwan Photon Source facility.

Gyrator-Gain Variable WPT Topology for MC-Unconstrained CC Output Customization Using Simplified Capacitance Tuning

Load-independent constant current (CC) outputs are desirable in many applications of wireless power transfer (WPT). Yet the WPT gain of a conventional system is normally dependent on the magnetic components (MCs) such as coils or inductors, making it difficult to customize the output for interoperability. This paper presents a gain variable WPT topology for CC output customization, which only employs capacitance tuning to provide sufficient freedom in gain regulation. To break the gain limitation of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S-S</i> compensation, which is the simplest with gyrator characteristics for CC output, a capacitive or inductive component is paralleled to the coil as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SP-S</i> or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S-PS</i> compensation. A thorough analysis based on the Y-Δ transform indicates that the gain is restrictively variable with the parallel component. An <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S-CLC</i> -compensated topology without an independent inductor is further proposed to avoid those restrictions with as few additional components as possible. The inductor in the topology, coupled with the transmitter coil and integrated into the receiver coil, extends the gain variable range. A complete design process of the topology is presented to realize efficient WPT and CC output customization with a wide variable-gain range and misalignment tolerance. Analytical and simulation results confirm the effectiveness of the gyrator-gain variation by capacitance tuning. Finally, the performance of the WPT topology is evaluated by experimental results on a scaled-down prototype.

An LC Squared-Compensated Inductive Power Transfer System With Misalignment Tolerance and Constant-Current Output

An <i>LC</i> Squared-Compensated Inductive Power Transfer System With Misalignment Tolerance and Constant-Current Output

Single-Transmitter-Controlled Multiple-Channel Constant Current Outputs for In-Flight Wireless Charging of Drones

This paper proposes a single-transmitter-controlled multiple-channel constant current outputs scheme, which can energize multiple hovering drones over the air simultaneously. As an unmanned and cost-effective solution to extend the cruising range of drones, the multiple-drone in-flight wireless charging has to deal with two key technical challenges, namely the continuous disturbance of multiple mutual inductances ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> ) caused by the hovering attitude of drones, as well as the limit of drone-side payload. Accordingly, this paper adopts the multi-frequency resonating compensation (MFRC) to establish multiple transmission channels and achieves the single-transmitter-controlled multiple-channel constant current outputs based on a communication-free multiple- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> estimation method. The simulated and experimental results are both given in this paper, which shows that the accuracy of the multiple- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> estimation is up to 97% and the steady-state accuracy of the current output control is up to 95%. What is more, the current output control can effectively restrain the output current fluctuation of the battery load under continuous multiple- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> disturbance, indicating that the proposed scheme is feasible to improve the stability and reliability of the multiple-drone in-flight wireless charging system.

A Single-Switch WPT Circuit With Inherent CCO–CVO for Battery Charging

In order to obtain a highly reliable and low-cost wireless charging method. This paper proposes a single-switch wireless power transfer (WPT) circuit with inherent constant current output (CCO) and constant voltage output (CVO) for battery charging. Compared with a full bridge WPT circuit, the structure and control strategy of the proposed circuit is simple. And the shoot-through problem could be avoided in the proposed circuit. In order to realize the inherent CCO-CVO without the wireless communication and extra control circuit, the double-D quadrature (DDQ) coils are used in this paper to remove cross-coupling between coils. And the corresponding compensation network is designed to realize the automatic transition from the CCO to CVO. There are no active control schemes used in the proposed method. The compensation design could enable primary-side protection of over-current against the accidental removal of the secondary side. There is no compensation inductor in the secondary circuit, which reduces the volume and weight of the secondary circuit. Moreover, the transfer gain does not rely on the transformer parameters, and more parameters design freedom can be realized. Finally, the simulation and the experimental verification are carried out to verify the superiority of the proposed circuit.

Increasing tolerable coupling coefficients range of series-series compensated inductive wireless power transfer systems operating in restricted sub-resonant frequency region with constant current output

Frequency control of series-series compensated inductive power transfer links (SS-IWPTL) operated in sub-resonant region while feeding variable voltage-type loads (e.g. batteries) with constant current under uncertain coupling conditions allows to minimize volt-ampere (VA) rating of transmitting-side converter. In such systems, variations of coupling coefficient and load voltage are counteracted by operational frequency adjustment so that primary current magnitude remains nearly unchanged throughout the complete operational range, as opposed to input voltage and phase shift control approaches. In practice, allowable operational frequency band is typically restricted by certain application and/or standard (e.g. SAE J2954). As a result, tolerable load voltage span and coupling coefficients range are also limited. Classical design guidelines impose the resonant frequency of SS-IWPTL to coincide with the upper bound of allowable operational frequency band for operation with the minimum expected coupling coefficient and the lower bound corresponding to operation with the maximum expected coupling coefficient. The paper demonstrates that generalizing this approach by releasing the former constraint adds a degree of freedom, allowing to expand tolerable coupling coefficients range for a given operational frequency band at the expense of slight efficiency deterioration. Analytical relations describing the above-mentioned behavior are established, clearly indicating the arising trade-offs. Simulation and experiments validate the proposed methodology.