V. J. Brusamarello

Power Transfer With an Inductive Link and Wireless Tuning

This paper presents the analysis of two air-coupled coils used to transfer energy to charge a battery. This battery is used to power an electronic device designed to monitor variables such as impact strength, range of temperature, and humidity associated with the transport of fruits. The device is inside a sealed enclosure that cannot be opened for recharging the battery. The study shows that the coupled coils need to work with a resonance capacitor, at least on the secondary coil. However, the resonance frequency also depends on the coupling factor

A study on inductive power transfer with wireless tuning

k

Analysis and Optimization of an Inductive Power Transfer With a Randomized Method

. Therefore, this work proposes a monitoring system with a closed loop for fine-tuning the resonance frequency of the secondary coil circuit. Before starting charging the battery, the system scans the resonance frequency on the primary coil and measures the output power on the secondary coil looking for the optimal point. This procedure reduces problems of coupling factor variations with positioning of the coils during the battery charging.

Full four capacitor circuit compensation for inductive power transfer

This paper presents the analysis of two loosely coupled coils used to transfer energy to charge a battery. This battery is used to power an electronic device designed to monitor variables such as impact strength, range of temperature and humidity associated with the transport of fruits. The device is inside a sealed enclosure that cannot be opened for recharging the battery. The study shows the loosely coupled coils need to work with a resonance capacitor, at least on the secondary coil. However the resonance frequency also depends on the coupling factor k and the power delivered to the load. Therefore, this work proposes a monitoring system with closed loop for fine-tuning the resonance frequency of the secondary coil circuit. Before starting charging the battery the system scans the resonance frequency on the primary coil and measures the output power on the secondary coil looking for the optimal point. This procedure reduces problems of variation of coupling factor with positioning of the coils.

Parameter Identification and Analysis of Uncertainties in Measurements of Lead–Acid Batteries

This paper introduces the analysis of the efficiency and transferred power of an inductive link circuit with different network configurations of capacitors connected to primary and secondary coils. The best performance for both cited objective functions was observed with two capacitors connected to the input coil and two capacitors connected to the output coil. However, the output equations in this circuit configuration for both efficiency and output power are very complex and a numerical method had to be applied to compute the capacitors values. Since an exhaustive search would be long, some simplifications were assumed to reduce the search space and the processing time. Thus, a search algorithm based on a randomized method was developed and successfully applied. The results for both efficiency and output power of four capacitors configuration were compared with other usual approaches, such as the single and two capacitors compensation. Finally, a basic prototype was built and the theoretical results were validated. Both simulated and experimental results of the four capacitor configuration showed a significant improvement on the efficiency and output power of the inductive link.

Design and characterization of a power transfer inductive link for wireless sensor network nodes

A novel full four capacitor compensation method for inductive power transfer is introduced. To compute the capacitors values, a very simple search algorithm based on Monte Carlo is used. In addiction, some heuristic are used to reduce the size of the search space. The efficiency, output power and power efficiency are compared with some classical approach such as the two capacitors compensation and also with the basic circuit without compensation. The results showed a significant improvement on the efficiency and output power.

Fine Tuning of an Inductive Link Through a Voltage-Controlled Capacitance

This paper is devoted to impedance measurements over the frequency band corresponding to the Randles model of the first order. An estimation technique is proposed to assess the state of charge of a battery using a developed experimental system. Randles parameter identification is carried out based on frequency response. This paper focuses on the analysis of the propagated uncertainty of input variables determining the measurement accuracy of battery parameters.

Efficiency modeling of class-E power oscillators for wireless energy transfer

This paper describes a design of a power transfer inductive link for charging batteries of wireless sensor network nodes. The application physical constraints imposes a maximum size for the coils and demands a design methodology to maximize output power delivered to the load and energy transmission efficiency. This paper presents a complete methodology for designing the coils of wireless power transfer systems applied to rechargeable batteries of wireless sensor network nodes. The design of an inductive link is presented as a case study, in which two planar coils are built in order to validate the proposed method. Moreover, a complete wireless power transfer system is developed for the proposal, including coils, primary power source, capacitor network compensation, and secondary power management, with rectification, filtering, regulation, and battery charge control. The experimental results for working distances between the coils from 1 mm to 10 mm are reported as well as the frequency response of the entire system.

Wireless portable sensor for athletic monitoring

Wireless power transfer is a technique usually based on an inductive link, used for delivering energy to remote devices. The power of different applications ranges from microwatts to hundreds of kilowatts, e.g., in biomedical implants and electric vehicles. The transferred power is highly dependent on the relative position between the inductive link coils. Many studies have been presented considering static or quasi-static conditions, based on a fixed tuned circuit. However, when the coils are not stationary, the inductive link must be dynamically tuned to keep the designed output power. This paper presents a methodology for dynamically tune the inductive link by means of a variable capacitance. A voltage-controlled capacitance using concepts of the negative impedance converter and capacitance multiplier is proposed. The phase angle between the input voltage and current is used as the error signal to control the variable capacitance and keep the output power operating point. The experimental evaluation shows that the proposed methodology can significantly improve the power delivered to the load in comparison to a fixed inductive link.

WirelessHART localization algorithm

Wireless energy transfer is employed in different applications such as recharging of electrical car battery, implanted biosystems and wireless sensor network nodes. In these applications, the efficiency in the energy transfer process is a key issue, requiring careful design and correct device, circuit and system modeling. In this paper, we present accurate expressions for efficiency calculation of class-E power oscillators targeting an inductive link for wireless energy powering. The model includes the influence of the load resistance variations due to changes on the magnetic coupling between the coils of the link. Moreover, we compare the results obtained from the developed model with those obtained from simulation and measurement of a class-E power oscillator operating at 125 kHz.