Constant Current Output Characteristics Research Articles

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.

A CC-Type IPT System Based on S/S/N Three-Coil Structure to Realize Low-Cost and Compact Receiver

The characteristics of load-independent constant current (CC) output and zero phase angle (ZPA) operation are required in many scenarios of inductive power transfer (IPT) applications. However, the existing topologies with CC output characteristics usually need to introduce additional compensation components on the receiving side to compensate for reactive power and achieve the preset function. This not only increases the occupied space of the receiving side, but also increases the cost and weight. Therefore, this study proposes a new IPT system based on an S/S/N three-coil structure. The proposed system can achieve the CC output function and an operation nearly ZPA and zero-voltage switching (ZVS) through flexible parameter design. Moreover, there are no compensation components on the receiving side of the proposed system, which guarantees a low-cost, lightweight, and compact receiver. Firstly, a comprehensive analysis of the proposed S/S/N three-coil structure IPT system that implements CC output characteristics and ZPA operation is provided. Then, the conditions for realizing ZVS are discussed in terms of parameter design and the sensitivity of CC output characteristics to the changes in compensation capacitance parameters. Furthermore, the proposed S/S/N three-coil structure IPT system is compared with previous related studies to reflect its advantages. Finally, the correctness of the theory is verified by simulation and experiment.

A hybrid wireless power system with anti-misalignment and constant current output characteristics

ABSTRACT Aiming at the problem of unstable output voltage and rapid reduction of efficiency caused by coil misalignment in the wireless charging process of wireless chargers, a hybrid wireless power system with anti-misalignment and constant current (CC) output characteristics is proposed. The system uses a high-order compensation network and a four-coil bipolar (BP) coupler to implement high anti-misalignment and CC output characteristic that is decoupled from the load. By inserting a high-order compensation network, the two overlapping coils in the same side of the transmitter and receiver sides of the BP coupler can be effectively decoupled and the design methodology can be simplified. Moreover, by adjusting the inductance value of the transmitter compensation network, the BP coupler can be made available for the occasions with different equivalent mutual inductance (MI) fluctuation requirements. While the receiver coil is suddenly removed, the system has a self-protection function, which can effectively limit the current flowing through the inverter. The design ideas of the coupler and compensation network are also discussed in this paper. Ultimately, a 1-kW experimental prototype is built to validate the proposed scheme.

A Dual-Frequency Dual-Load Multirelay Magnetic Coupling Wireless Power Transfer System Using Shared Power Channel

Aiming at the power supply solution of online monitoring equipment for high-voltage transmission lines, a dual-frequency dual-load multirelay magnetic coupling wireless power transfer (MC-WPT) system using a shared power channel has been proposed. The proposed MC-WPT system provides the selective power distribution for different loads and has the constant current output characteristic. First, a dual-frequency inverter is introduced to provide the ac voltage of two frequencies. The compensation network that includes the band-stop filter can reduce the cross interference of the nontarget frequency from another power channel. Second, the system is modeled and analyzed based on the quadratic eigenvalue problem. Considering the cross-coupling mutual inductance, operating frequencies that make the system have constant current output characteristics are obtained. Finally, three evaluation indices are proposed: average current gain, load-independent index, and average sensitivity index of operating frequencies. Optimized operating frequency is selected according to these evaluation indices. The experimental results verify constant current output characteristics and the selective power distribution of two power channels.

Zero-Voltage Switching Regulation Strategy of Full-Bridge Inverter of Inductive Power Transfer System Decoupled From Output Characteristics

The soft switching of power components in inductive power transfer systems can reduce switching loss and switching stress and decrease electromagnetic interference. However, the realization of soft switching in an inductive power transfer system may change the system's constant voltage and constant current output characteristics. For this reason, in this article, a zero-voltage switching technology based on a full-bridge inverter that is decoupled from the output characteristics of the system is proposed and validated. First, the basic conditions for the full-bridge inverter to achieve zero voltage switching are derived by analyzing the working mode of the full-bridge inverter circuit. Then, the constant current, constant voltage output, and zero phase angle input conditions of a first-order/second-order/third-order compensation structure are studied using the high-order two-port network cascading rule. On this basis, a parameter adjustment strategy for an arbitrary compensation structure is proposed to achieve zero voltage switching without affecting the output. Then analytical verification of the constant current output characteristics of a double-sided inductor-capacitor-capacitor compensation structure is performed as an example. Finally, a MATLAB/Simulink model and a set of 3.3 kW prototypes are established to verify the correctness of the theoretical analysis.

Misalignment‐tolerant integrated IPT systems for tram logistics robots featuring dual‐purpose coupler

This study proposes a misalignment-tolerant integrated inductive power transfer (IPT) system for tram logistics robots and presents an adapted parameter tuning method for the IPT system. A novel dual-purpose coupler, which could undertake the responsibility of power transmission and self-compensation is realised by substituted partially with compensation inductors of inductor–capacitor–capacitor networks, resulting in an integrated and cost-effective system configuration. With the analysis of working principles on the IPT system and considerations of operation conditions on logistics robots, an adapted parameter tuning method is provided to maximise system misalignment tolerance and maintain high efficiency of power transfer. To demonstrate the validity and safety of the proposed system, comparative simulations and security evaluations are conducted by finite element analysis. Besides, the constant-current output characteristic is simulated and proved. Finally, a 60.20 W experimental prototype is built. Results show that the system can operate stably with 87.31% efficiency at well-aligned cases and the power fluctuation is confined below 9% within −120 to 120 mm x-misalignment, −80 to 80 mm y-misalignment, −50 to 12.5 mm z-misalignment, and −30° to 30° rotatory misalignment. It is also verified that the system could operate safely without any secondary side.

An LCC-SP Compensated Inductive Power Transfer System and Design Considerations for Enhancing Misalignment Tolerance

This paper proposes a novel LCC-SP compensation topology for inductive power transfer (IPT) system and its tuning methods to enhance misalignment tolerance. The impedance condition and the constant current output characteristic of the newly proposed topology are analyzed, followed by a detailed derivation of compensation parameters based on the discussion about resonant tank. The realization of zero voltage switching (ZVS) and reactive power demand are discussed by theoretical deduction and numerical simulation. Then, the parameters detuning method to enhance misalignment tolerance is presented and it is found that a stable output current is maintained over a wide misalignment. Compared to traditional compensation topologies, the newly proposed compensation topology provides the advantages of easy achievement of ZVS, high design freedom and high misalignment tolerance. Finally, the IPT prototype with the LCC-SP compensation network is built and tested. The experimental results match well with the calculations, validating the correctness of theoretical analysis.

A Misalignment Tolerant IPT System With Intermediate Coils for Constant-Current Output

Misalignment in an inductive power transfer (IPT) system is inevitable for most of the cases, which leads to system performance degradation due to the variation of system parameters. A novel IPT topology with two intermediate coils, one for primary side and the other for secondary one, is proposed to improve an anti-misalignment characteristic. With the merit of the proposed topology, a constant-current output characteristic is achieved, and the system can operate safely without any secondary side. Then, the parameter design and optimization method of the magnetic coupler with intermediate coils are elaborated to improve misalignment performance. Finally, a 3.4-kW experimental setup is built to verify the feasibility of the proposed method. Experimental results show that the four-coil IPT system can tolerate ±225 mm X- misalignment, −30 to +50 mm Y- misalignment, and −20 to +70 mm Z- misalignment with load varying from 40 to 60 Ω, while the fluctuation of the output current is within ±5%. The system efficiency of the IPT system is from 92.1% up to 96.3% with misalignment and variable load (40–60 Ω).

LCL Resonant Compensation of Movable ICPT Systems with a Multi-load

Compared to LC resonance, LCL resonance has distinct advantages such as a large resonant capability, low voltage and current stresses of the power device, constant voltage or current output characteristics, and fault-tolerance capability. Thus, LCL resonant compensation is employed for a movable Inductive Contactless Power Transfer (ICPT) system with a multi-load in this paper, which achieves constant current output characteristics. Peculiarly, the primary side adopts a much larger compensation inductor than the primary leakage inductor to lower the reactive power, reduce the input current ripple, generate a large current in the primary side, and realize soft-switching. Furthermore, this paper proposes an approximate resonant point for large inductor-ratio LCL resonant compensation through fundamental wave analysis. In addition, the PWM control strategy is used for this system to achieve constant current output characteristics. Finally, an experimental platform is built, whose secondary E-Type coils can ride and move on a primary rail. Simulations and experiments are conducted to verify the effectiveness and accuracy of both the theory and the design method.