Inductive Power System Research Articles

Stabilization of the output characteristics of an inductive power system for equipment in hospital wards

Stabilization of the output characteristics of an inductive power system for equipment in hospital wards

Algorithms for the Design and Optimization of Coil Pairs in Inductive Power Systems for Implants

Algorithms for the Design and Optimization of Coil Pairs in Inductive Power Systems for Implants

A Canonical Filter Theory Approach for the Synthesis of Inductive Wireless Power Systems with Multiple Resonators

A Canonical Filter Theory Approach for the Synthesis of Inductive Wireless Power Systems with Multiple Resonators

Inductively Powered Sensornode Transmitter Based on the Interconnection of a Colpitts and a Parallel Resonant LC Oscillator

An inductively powered passive transmitter architecture for wireless sensornodes is presented in this paper. The intended applications are inductively powered internally illuminated photoreactors. The application range of photoreactors is wide. They are used, e.g., for microalgae cultivation or for photochemistry, just to name two important fields of use. The inductive powering system used to transmit energy to the wireless internal illumination system is to be additionally used to supply the here presented transmitter. The aim of expanding the named internal illuminated photoreactors with wireless sensors is to obtain a better insight into the processes inside it. This will be achieved by measuring essential parameters such as, e.g., the temperature, pH value, or gas concentrations of the medium inside the reactor, which for algal cultivation would be water. Due to the passive architecture of the transmitter electronics, there is no need for batteries, and therefore, no temporal limitations in their operational cycle are given. The data transmission is also implemented using the inductive layer in the low frequency range. The data transmitting coil and the energy receive coil are implemented as one and the same coil in order to avoid interference and unwanted couplings between them, and in order to save weight and space. Additionally, the transmitter works in a two-step alternating cycle: the energy harvesting step, followed by the data transmission step. The measured values are sent using on-off keying. Therefore, a Colpitts oscillator is switched on and off. The circuit is simulated using SPICE simulations and consequentially implemented as a prototype in order to perform practical analyses and measurements. The feasibility of our transmitter is therefore shown with the performed circuit simulations, and practically, by testing our prototype on an internal illuminated laboratory scaled photoreactor.

MIMO INDUCTIVE COUPLING FOR HIGH POWER WIRELESS SYSTEMS

Transmitter component of high power inductive wireless transmission systems for electric busses and trucks should be embedded in the road to ensure a free circulation of vehicles and to ensure a good mechanical resistance of the pavement, in the charging region, similar to the rest of the road. In such application, ferrites cannot be envisaged as magnetic flux concentrators due to their fragility. An adequate solution to replace the ferrites consists in using magnetic concrete as magnetic field concentrator for wireless inductive transmission system. This solution is analyzed in this paper and used for an MIMO (Multiple-Input-Multiple-Output) inductive wireless power system based on Double-D structure coils, for a transferred power of 125 kW, corresponding to the standard project SAE J2954-2, sufficient for an electric bus for 50 persons. The Finite Element analysis carried out in the paper has the objective of determining the useful and parasitic magnetic coupling parameters of the proposed inductive power transfer system

Adaptive Bidirectional Inductive Power and Data Transmission System

For the research of wireless power transfer, loosely coupled inductive power transfer (LCIPT) is one of the widely adopted technologies. There are already various researches focusing on development of high-efficiency LCIPT. However, when the transmission and receiver coils are misaligned, the power transfer efficiency will be significantly dropped. This article considers the change of mutual inductance when two induction coils are misaligned. A fuzzy control approach to solve for this problem by adaptively adjusting operational frequency is introduced. Experiments show that it can reduce the power transferring efficiency drop by 11% when two conduction coils are misaligned up to 50 mm. This research also supports adaptive maximum power transfer using tracking mechanism. Before conducting power transmission, the system can choose G2V or V2G according to the vehicle battery capacity via handshaking communication without the need of radio frequency links. In addition, the phase shift pulsewidth modulation technique is proposed for simultaneous data transmission enabling binary quadrature amplitude modulation for digital signal transmission. Fast over current protection is incorporated for power transfer safety when current overload happens. The transmission frequency of this article is controlled to meet the frequency specified by SAE TIR J2954.

The Effect of Misalignment of Induction Coils on Tissue Heating during Wireless Transcutaneous Energy Transfer

The effect of induction coil misalignment on the heating of surrounding biological tissues was studied for a wireless inductive powering system with 500 mW output power. It was shown that a lateral misalignment of 2-20 mm can cause an increase in the tissue temperature up to 0.4°C compared with the case of coaxial positioning of the coils. Changes in temperature can be caused by a change in power losses in the elements of the system, as well as by displacement of these elements and the mutual influence of their thermal fields.

Application of Magnetic Coupling Resonant Wireless Power Supply in a Torque Online Telemetering System of a Rolling Mill

The torque of the main drive system is one of the most important force and energy parameters of the rolling mill, and the strain type torque online telemetry system is a practical method for measuring torque parameters. The strain gauges and transmitters on the rotating shaft are driven by a high-frequency induction power system. Their installation, debugging, and maintenance are cumbersome, and their very low power transmission efficiency (PTE) has become a challenging problem for online telemetry systems. In this paper, a magnetic coupling resonant wireless power supply method is utilized to replace the high-frequency induction power supply. Through theoretical and experimental research, it is concluded that the magnetically coupled resonant wireless power supply method can realize long-distance power supply, overcoming many shortcomings of the high-frequency induction power supply system. In the laboratory, a maximum PTE of 83.7% is obtained for a transmission distance of 50 mm. Under the influence of environmental factors common for the transmission shaft of a rolling mill, the PTE decreases by 34%, but normal operation of the system can be achieved by adjusting the compensation capacitance. The proposed system provides a guarantee for a long-term stable power supply on the measured axis of a rolling mill torque online telemetry system.

DqSynchronous Reference Frame Model of A Series–Series Tuned Inductive Power Transfer System

A control-oriented circuit model of an inductive power transfer system is needed to design a high-performance controller. In this article, a dq synchronous reference frame model of a series-series tuned resonant inductive power transfer system is proposed. A single-phase dq modeling technique for a resonant converter is used to derive the model. The proposed control-oriented model clearly demonstrates the cross- and mutual-coupling between the state variables of the wireless power transfer system. It is interesting to note that the proposed model is similar to a dq synchronous reference frame model of a three-phase induction motor. The well-known controller design methods, such as proportional-integral controller design, manipulated input decoupling, disturbance input decoupling, state observers, and disturbance observers, etc. can be extended to the inductive power systems with the proposed model. The large- and small-signal responses of the transmitter current versus its input voltage are identified. Considering the frequency response, a new transmitter current controller that has a control bandwidth of 500 Hz is designed to show the validity of the proposed model. The proposed model and the controller are evaluated using simulated and experimental results. The simulated open- and closed-loop frequency responses of the model agree well with the theoretical bode plots of them. Also, the experimental results show that the proportional-integral with feedforward input controller regulates the transmitter current within 1 ms for three conditions: a step change of the reference, a step change of the load, and a step change of the mutual-coupling.

Considerations Regarding the Design of a Minimum Variance Control System for an Induction Generator

This paper presents a comparative analysis regarding a self-tuning minimum variance control system of a double-fed induction generator with load and connected to a power system through a long transmission line. A new complex nonlinear model describing this relationship between the induction generator, electrical consumer, transmission line, and power system is designed and implemented to simulate the controlled plant behavior. Starting from a simplified linear model of this complex plant, obtained through linearization of its nonlinear model around an operating point, the minimum variance control law design is performed by minimizing a cost criterion function. The main goal and also the paper novelty consists of the identification of a minimum order of this linearized model used to design a reduced order control law, which can still provide good control performance.

Coordinated Control of Doubley Fed Induction Generator Virtual Inertia and Power System Oscillation Damping Using Fuzzy Logic

Doubly-fed induction generator (DFIG) based wind turbines with traditional maximum power point tracking (MPPT) control provide no inertia response under system frequency events. Recently, the DFIG wind turbines have been equipped with virtual inertia controller (VIC) for supporting power system frequency stability. However, the conventional VICs with fixed gain have negative effects on inter-area oscillations of regional networks. To cope with this drawback, this paper proposes a novel adaptive VIC to improve both the inter-area oscillations and frequency stability. In the proposed scheme, the gain of VIC is dynamically adjusted using fuzzy logic. The effectiveness and control performance of the adaptive fuzzy VIC is evaluated under different frequency events such as loss of generation, short circuit disturbance with load shedding. The simulation studies are performed on a generic two-area network integrated with a DFIG wind farm and the comparative results are presented between three cases: DFIG without VIC, DFIG with fixed gain VIC, and DFIG with adaptive fuzzy VIC. All the results confirm the proposed fuzzy VIC can improve both the inter-area oscillations and frequency stability.

An Algorithm for Designing AC Generators for Inductive Powering Systems of Batteryless Implants

An algorithm for designing AC generators based on class E amplifiers for inductive powering systems of batteryless implants was proposed. Parameters of three different inductive powering systems were calculated using the suggested algorithm. Each system used a pair of symmetric antennas with inductances of 3.4, 7.29, and 12.27 μH, respectively. The energy transfer efficiency and the output power of the inductive powering system based on class E amplifier were calculated as functions of the axial distance between the transmitter and the receiver for each of the three antenna pairs. The efficiencies of the systems built around antennas with inductances of 3.4 and 7.29 μH were found to be higher than 90% for axial distances in the range from 10 to 25 mm. It was found that the class E amplifier should be tuned at the minimum rather than the medium distance between the antennas.

Simultaneous Inductive Power and Data Transmission System for Smart Applications

Inductive power transfer (IPT) development is a big issue amongst the scientific community but there are only few solutions for communication between the primary and secondary side. This article presents a completely contactless near field system, which can provide power and data simultaneously using one common inductive power link. In this novel approach both transmission channels are designed collaboratively to maximize their performance. Based on these joint system specifications, the requirements for each system are derived, analyzed, simulated and measured. From this measurement the performance of the system is classified. To verify the joint specifications, the mutual interferences are evaluated and the system is compared to the state of the art.

Optimal Integration of Hybrid Supercapacitor and IPT System for a Free-Catenary Tramway

The aim of the paper is the study of an optimal integration of a supercapacitor-based storage system and inductive power transfer system for the free-catenary operation of a tramway. Starting from the definition of the topology of inductive power transfer system, we propose and analyze a design procedure for the pads of the inductive power system. In the second part of the paper, an optimal integration strategy for the correct size of on-board supercapacitors and the power of the inductive energy transfer are proposed. The results obtained by means of numerical simulations are discussed.

Coordinated Supplementary Damping Control of DFIG and PSS to Suppress Inter-Area Oscillations With Optimally Controlled Plant Dynamics

This paper proposes a design method to coordinate dual-channel supplementary damping controllers (SDCs) of doubly-fed induction generators (DFIGs) and power system stabilizers (PSSs) for suppression of inter-area power oscillations. A dynamic performance index is introduced to measure the dynamics of the conventional synchronous generator and DFIG during the damping control process. Hence, the proposed method designing the PSS and SDC is formulated as an optimization problem with the objective function being the sum of weighted performance indexes and the constraints indicating the requirements on the damping of the inter-area modes. Solving the optimization problem can obtain the optimal SDC and PSS, which can meet the required damping results as well as optimize dynamics of the controlled plants. Moreover, by adjusting weights in the objective function, the damping control burden can be flexibly and feasibly allocated between active and reactive power channels of DFIGs or among the damping controllers. Simulations with the modified New England and New York interconnected system prove that the proposed optimization based tuning method can not only robustly coordinate the PSS and SDC to effectively damp inter-area oscillations but also improve the dynamics of controlled plants during the damping control process over different operating conditions.

Methods for Compensation of Coil Misalignment in Systems for Inductive Transcutaneous Power Transfer to Implanted Medical Devices

The problem of variation of the output characteristics (voltage, current, power) of inductive powering systems for implantable medical devices is considered. The variation is primarily caused by relative misalignment of transmitting and receiving coils. A classification of misalignments is proposed. Main approaches to coil misalignment compensation are: mechanical fixation of the coils; evaluation of the relative position of the coils for elimination of misalignment or further tuning of the transmitting part of the system; optimization of the coil geometry providing stability within the given misalignment range; tuning the working frequency of the transmitting part of the system. It is shown that the compensation method should be selected with due regard to the implantable device parameters (first of all, the coil implantation site and the power consumption of the device).

Impact of Ferrite Shield Properties on the Low-Power Inductive Power Transfer

In typical inductive power transfer (IPT) applications, soft magnetic materials are employed in both transmitter and receiver coils as low reluctance paths in order to improve the inductive coupling and support the guidance of magnetic flux. Considering their critical role in the overall performance, this paper investigates the impact of magnetic material properties on the basic features of inductive powering systems. To this end, a group of Ni–Zn and Ni–Cu–Zn spinel ferrite samples with a wide value range of magnetic properties is prepared. The materials are characterized in terms of their structural and magnetic properties, and they are used to build various substrate assemblies for the IPT transmitter (Tx) coil. Conducting Al and Cu sheets and biasing permanent magnets are combined with ferrite disks to simulate common Tx coil designs. This allows the identification of the correlation between the material properties, especially power losses, and the measured power transfer efficiency and shielding effectiveness.

Efficient Wireless Powering of Biomedical Sensor Systems for Multichannel Brain Implants

This paper describes the complete mathematical optimization process of an inductive powering system suitable for the application within implanted biomedical systems. The optimization objectives are thereby size, energy efficiency, and tissue absorption. Within the first step, the influence of the operational frequency on the given quantities is computed by means of finite element simulations, yielding a compromise of power transfer efficiency of the wireless link and acceptable tissue heating in terms of the specific absorption rate. All simulations account for the layered structure of the human head, modeling the dielectric properties with Cole-Cole dispersion effects. In the second step, the relevant coupling and loss effects of the transmission coils are modeled as a function of the geometrical design parameters, enabling a noniterative and comprehensible mathematical derivation of the optimum coil geometry given an external size constraint. Further investigations of the optimum link design also consider high-permeability structures being applied to the primary coil, enhancing the efficiency by means of an increased mutual inductance. Thereby, a final link efficiency of 80% at a coil separation distance of 5 mm and 20% at 20 mm using a 10-mm planar receiving coil can be achieved, contributing to a higher integration density of multichannel brain implanted sensors. Moreover, the given procedure does not only give insight into the optimization of the coil design, but also provides a minimized set of mathematical expressions for designing a highly efficient primary side coil driver and for selecting the components of the secondary side impedance matching. All mathematical models and descriptions have been verified by simulation and concluding measurements.

A wireless implantable micropump for chronic drug infusion against cancer

We present an implantable micropump with a miniature form factor and completely wireless operation that enables chronic drug administration intended for evaluation and development of cancer therapies in freely moving small research animals such as rodents. The low power electrolysis actuator avoids the need for heavy implantable batteries. The infusion system features a class E inductive powering system that provides on-demand activation of the pump as well as remote adjustment of the delivery regimen without animal handling. Micropump performance was demonstrated using a model anti-cancer application in which daily doses of 30μL were supplied for several weeks with less than 6% variation in flow rate within a single pump and less than 8% variation across different pumps. Pumping under different back pressure, viscosity, and temperature conditions were investigated; parameters were chosen so as to mimic in vivo conditions. In benchtop tests under simulated in vivo conditions, micropumps provided consistent and reliable performance over a period of 30 days with less than 4% flow rate variation. The demonstrated prototype has potential to provide a practical solution for remote chronic administration of drugs to ambulatory small animals for research as well as drug discovery and development applications.

Design of an induction system for induction assisted alternating current gas metal arc welding

Recent work on the low heat input and high deposition rate welding process of pulsed alternating current gas metal arc welding (AC-GMAW) has paved the way for the implementation of a cost effective solution for thick plate welding. Intense plasma jets are achieved through a high current and high electrode negative (EN) ratio based pulsed AC-GMAW, which has high negative peak currents in the EN region of the pulse. A distinct arc behavior results in high arc center temperatures and finger penetration, whereas the weak surrounding arc results in a lack of fusion on the joint sides for material thicknesses above 8mm. The controlled induction pre-heating of the joint sides up to the desired depth can help in overcoming this problem. Numerical simulations of the induction source were performed using temperature-dependent material properties to find the optimal induction heating parameters that will result in the desired penetration depth and temperature. Experiments were conducted on a scaled-down induction system to verify the simulation model. Reasonable results were observed, confirming the proposed methodology. A full-scale induction power system needs to be implemented together with the AC-GMAW process to experimentally verify the application of the induction-assisted alternating current gas metal arc welding (IA-ACGMAW) system to thick plate welding, especially to thermally treated high-strength steels.