Modeling a current source push-pull resonant converter for loosely coupled power transfer systems

According to the poor stability of the output constant current and the control complexity of the existing Inductive Coupled Wireless Power Transmission System, a seriesparallel compensation network is applied to push-pull converter. And the soft switch is realized by configuring the parameters of compensation network, and the constant-current output of the wireless power is realized without additional complex control system. Firstly, analysis of the push-pull converter to achieve the conditions of soft-switching. Secondly, based on the leakage inductance model of the transformer, combined with the Thevenin equivalent theorem, the parameters of the string-and-compensation are designed. Lastly, the push-pull soft-switching inductive coupled power transfer converter is designed and built.The feasibility of theoretical analysis and parameter design method are verified by the experimental results.

Inductive coupled power transfer (ICPT) is an emerging technology that may create new applications for wireless power charging. However, low efficiency is one of the main obstructing factors for promoting this technology. In this paper, a method of resonant frequency optimization based on resonant current calculation at the secondary side of the system is proposed to achieve higher efficiency. In order to research the influences of resonant frequency on system efficiency, the resonant current of the secondary side circuit is calculated, from which the phase shift angle between resonant current and voltage, and the conduction angle of diodes of rectifier can be obtained. Furthermore, a set of simulations are performed to find the optimized resonant frequency relationship between output power and the resonant current amplitude, because the copper loss and core loss of a loosely coupled transformer are all positively associated with resonant current. Finally, a 1.6 kW ICPT system is built and tested to verify the effectiveness of the proposed system. The results prove that the optimized resonant frequency can achieve a system efficiency of 92.5%, when that of a conventional system with a resonant frequency equal to the working frequency is 92%.

To date inductively coupled power transfer (ICPT) systems have already found many practical applications including battery charging pads. In fact, current charging platforms tend to largely support only one- or two-dimensional planar movement in load. This paper proposes a new concept of extending the aspect ratios of the operating power transfer volume of ICPT systems to support arbitrary three dimensional load movements with respect to the primary coils. This is done by use of modern finite element method analysis software to propose the primary and secondary magnetic structures of such an ICPT system. Firstly, two primary magnetic structures are proposed based on contrasting modes of operation and different field directions. This includes a single-phase and multi-phase current model. Next, a secondary magnetic structure is customized to be compatible with both primary structures. The resulting system is shown to produce a 3D power transfer volume for battery cell charging applications.

As battery-electric vehicle technology advances as a viable alternative to internal combustion engine vehicles, consumer acceptance becomes a critical factor for the future of these vehicles, with driving range and vehicle cost being the preeminent parameters of concern. Unique to battery-electric vehicles is the direct inverse relationship between these parameters. Battery pack costs often account for over one half of the vehicle cost, with the vehicle range determined by the capacity (and thus cost) of the battery pack as well. An increase in vehicle range would therefore result in a significant increase in battery pack cost, and vice versa. In addition, the relationship between overall vehicle mass and total range further inversely couples vehicle cost and range. It is apparent then that a fundamental trade-off will always exist between the two parameters, unless an additional factor is added to decouple the direct relationship between them. This paper presents results of an analytical investigation of the aforementioned relationships unique to battery-electric vehicles and proposes inductively coupled power transfer (ICPT) as a potential solution and decoupling method for the vehicle range –1 vehicle cost relationship. The proposed inductively coupled power transfer (ICPT) system was found to be very effective by allowing the battery pack size to be reduced by up to 48%.

This paper presents a new electromagnetic coupling mechanism called pot coil focusing on improving the inductively coupled power transfer (ICPT) system with limited transmission distance and range. Pot coil allows pick-up coil in electromagnetic field to move at larger range and ensure the output power remains unchanged. The contrast for the magnetic flux intensity distribution of pot coil and conventional spiral coil is brought out by using Ansoft Maxwell, a kind of 3D finite element analysis software. The simulation results demonstrate that pot coil increases energy transmission distance and promotes equilibrium of magnetic circuit. Finally, the experiment results prove the validity of the theory analysis.

Based on full-bridge topology, different capacitor compensation circuits of the inductively coupled power transfer (ICPT) system are compared and investigated in this paper. Compensation capacitor on primary side can reduce both switches stress and requirement of the power supply capacity. Compensation capacitor on secondary side can improve system efficiency and power transfer capability. From the reflect impedance analysis, there is no direct effect between the primary series compensation capacitor and the load. System efficiency with secondary compensation capacitor is higher than without it. Switches can realize zero voltage switching when the operating frequency is above the resonant frequency slightly. Finally, simulation results verify the analyses presented in the paper.

Aiming at the influence of coupling coefficient variation on the output voltage of a high-power LCC-S topology inductively coupled power transfer (ICPT) system, a synchronous three-phase triple-parallel Buck converter is used as the voltage adjustment unit. The control method for the three-phase current sharing of synchronous three-phase triple-parallel Buck converter and the constant voltage output ICPT system under the coupling coefficient variation is studied. Firstly, the hybrid model consisting of the circuit averaging model of the three-phase triple-parallel Buck converter and the generalized state-space average model for the LCC-S type ICPT system is established. Then, the control methods for three-phase current sharing of the synchronous three-phase triple-parallel Buck converter and constant voltage output of ICPT system are studied to achieve the multi-objective integrated control of the system. Finally, a 3.3 kW wireless charging system platform is built, the experimental results have verified the effectiveness of the proposed modeling and control method, and demonstrated the stability of the ICPT system.

Inductively Coupled Power Transfer (ICPT) systems are designed to deliver power efficiently from a stationary primary source to movable secondary loads over air gaps via magnetic coupling. Present vehicle chargers are wired. Corrosion of connectors is a very serious problem. Frequent replacement and maintenance are needed for proper operation. For charging different vehicles with different battery voltages we have to modify the charger to suit the battery voltages that will affect the charger efficiency. This work proposes a design for practical electric vehicle charger suitable for any power vehicles (two wheelers, four wheelers, heavy motor). LCPT vehicle chargers are wireless and there is no contact problems and maintenance so it is a maintenance free charger. LCPT can charge different vehicles with different battery voltages without making any changes in the charger so the efficiency does not affect. Only the number of turns of the pickup coil (secondary coil) has to be adjusted at the time of manufacturing of the vehicles. This same concept can be used in traction system by neglecting the battery.

Power electronic resonant converters designed for inductively coupled power transfer (ICPT) applications are normally controlled to switch at zero voltage switching (ZVS) frequencies and operate with minimal quality factor Q for economic and practical reasons. This Letter analyses various resonant frequencies and defines a new minimum bound on Q that ensures ZVS operation.

Infrastructure Cost Issues Related to Inductively Coupled Power Transfer for Electric Vehicles

A study on renewed perspectives of electrified road for wireless power transfer of electric vehicles

In this paper, an analytical solution for a clamped-edge bimorph disk-type piezoelectric transformer with Kirchhoff thin plate theory is proposed. The electromechanical equations for transient motions are first derived, and coupled expressions for mechanical response and voltage output are obtained. For the case of excitation around the first resonant frequency, the resulting equations are further simplified. There are analytical solutions for a mechanical response, voltage, current, and power outputs. According to the analytical model, the output voltage is affected by the inner radius of the input and output electrodes, the radius of the piezoelectric transformer (PT), and the thickness ratio between the lead zirconate titanate (PZT) layer and the substrate. When the inner radius of the input electrode approaches zero (electrode becomes circular shape), it achieves maximum output voltage at the first resonance frequency excitation. On the contrary, when the inner radius of the output electrode approaches zero, the output voltage reaches its minimum value. Voltage ratios remain constant as the disk radius changes, and the first resonance frequency is inversely proportional to the square of the disk radius. The voltage ratio is fixed even with the miniaturization of the PT.

This paper presents a novel design concept for near-field wireless power transfer (WPT) systems that leverages the seamless integration of metamaterials (MTMs) into slotted resonators. This approach enhances magnetic field ( $$\textbf{B}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> </mml:math> ) distribution, strengthens evanescent wave coupling, and hence improves overall WPT performance. An MTM structure exhibiting negative permeability at the operating frequency of 433 MHz was designed and incorporated into a square-slot-based resonator. Electromagnetic (EM) analysis revealed increased current density and subsequently enlarged $$\textbf{B}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> </mml:math> around the resonator. Additionally, impedance matching, key parameter extraction, and equivalent circuit (EC) modeling were performed using the effective J-inverter method. The developed WPT system, with compact dimensions of 30 $$\times$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> 30 $$^{\text {2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mtext>2</mml:mtext> </mml:mmultiscripts> </mml:math> , achieved a power transfer efficiency of 82% at 33 mm. The design was experimentally validated, showing excellent agreement among EM simulations, EC modeling, and measurement results. Finally, performance comparison with other reported systems confirmed the superiority and practical effectiveness of the proposed design in enabling compact and highly efficient WPT systems.

Based on the principle of magnetic coupled resonance theory, the problem of offset, which influences wireless power transfer system transfer characteristic is analyzed. With equivalent circuit theory, the relationship between transfer power, transfer efficiency and charge current with primary and secondary coils' mutual inductance is obtained, and then give the mathematical expression of the offset direction and the mutual inductance. Through Ansoft simulation, analyze the relationship between circular and rectangular coils' X or Y axis and diagonal offset with mutual inductance. Then use Pspice simulation analyze mutual inductance's influence on the system's transfer characteristics. Finally, based on theoretical analysis and software simulation, propose the secondary Buck converter impedance adjustment method, with PI algorithm control Buck converter's duty ratio, when the system offset occurs, the stability of wireless power transfer characteristic can be ensured.

Solar energy is one of the renewable energy that has a large potential in Indonesia. Solar energy can be converted into electrical energy using PV. According to the increasing energy demand in Indonesia and the enactment of the feed-in tariff by the government, it will be easier for the sale and purchase of electricity through the on-grid system. This study discusses the design and implementation of a three-phase grid-connected inverter. This three-phase inverter circuit uses sinusoidal pulse width modulation for input signal (SPWM) is used to input the IR2113 circuit a three-phase inverter driver. SPWM used is also a synchronization method to connect the inverter to the grid. Grid synchronization in this study is equating the phase angle and inverter output frequency to the grid. In this design add DC to DC converter type push-pull converter as a three-phase inverter supply and also as a control to adjust the inverter output voltage to fit the grid. The push-pull converter uses an SG3525 PWM IC generator. The circuit can be adjusted according to the voltage you want to produce. The circuit uses a high-frequency transformer as a step up the voltage. The result of the system design is the PV output voltage is increased by the push-pull converter and then to supply threephase inverter.