Using sigma-delta quantizer based PI for inductive power transfer systems (original) (raw)
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Single-bit modulator for wireless power transfer system
International Journal of Power Electronics and Drive Systems (IJPEDS)
This paper proposes a single-bit ADC system based Proportional and Integral (PI) controller to maintain a desired level of power transfer efficiency in Capacitive Power Transfer (CPT) systems. In this paper, a simple single-bit ADC system i.e., Single-Bit Modulator (SBM) is considered as an alternative to the commonly used multi-bit ADC systems. Unique features of employing SBM are 1) its ability to convert analog signals into single-bit signals and 2) its easy integrability in digital chips with linear variable differential transformers (LVDTs) such as FPGAs. A SBM based PI (SBM-PI) controller is designed to judicially interface with the single-bit output of SBM. The proposed (SBM-PI) controller guarantees less hardware resources, latency and regulates the output voltage to provide the desired power transfer efficiency. The behavior of SBM-PI controller is compared to that of a conventional multi-bit controller, with the results of both controllers being identical. The effectivenes...
Control of an Inductive Power Transfer System Using a Double Coil Structure
Electronics
This paper presents the design of the control of the system using a double DD coil structure. The double DD coil is a layered coil structure that consists of two single DD coils, rotated to each other by 90°. A large-signal and small-signal model of the proposed IPT system are designed for control synthesis. The small-signal model is derived from the large-signal using harmonic approximation and the extended describing functions (EDF). For the small-signal model, voltage and current control schemes were proposed for the purpose of wireless battery charging. The robustness of the control is tested on a small-scale IPT system using double DD coils and resistive load. The results are evaluated at different reference voltages, currents, loads and coupling coefficients.
IEEE Transactions on Industry Applications, 2018
A self-tuning controller for power transfer regulation in inductive power transfer (IPT) systems is proposed in this paper. The controller enables power transfer regulation around a user-defined reference power level. The converter's efficiency is improved by constantly tuning the switching operations to the resonant current, thereby achieving the soft-switching operations reducing the electromagnetic interference (EMI) the power converters. The self-tuning capability makes it ideal for dynamic IPT systems with uncertain loads and fluctuating resonance frequency. High operating frequencies can be achieved using the simplified digital circuit design for the controller, proposed in this paper, which delivers a low total propagation delay. Bidirectional power transfer can be enabled by using the proposed controller on both transmitter as well as receiver sides. In the reverse power flow mode, the primary converter operates as a rectifier and the power transfer is controlled through the secondary converter using the proposed controller. The performance of the proposed controller is analyzed using MATLAB/Simulink, and the results are presented. Finally, the proposed controller is implemented experimentally and its performance is evaluated as a case study on an IPT system. The experimental and simulation results conform to each other and show that the proposed converter can effectively regulate the power transfer with an improved efficiency.
2017
Going wireless has revolutionised handheld and wearable devices today. On comparing battery technology with other aspects of portable device technology, it has been a bottleneck in new innovation of miniaturised electronic devices. In this work, first energy harvesting techniques are discussed followed by wireless power transfer methods. Eventually it is concluded that magnetic resonance inductive power transfer method is most suitable to implement as wireless power transfer method. Then this technique of cordless power transfer is discussed, analysed and implemented assuming BLE as a typical load to be wirelessly powered or charged. In the course of WPT implementation, the modules like inductive link, rectifier and LDO are designed in 90nm CMOS technology. Finally WPT chip is designed and produced. This project concludes with comparison of simulated and measured performance of the WPT chip.
2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), 2017
In multiple receivers wireless power transfer (WPT) systems, it is preferable to retune the resonant frequency of every receiver to the transmitter operating frequency in front of frequency mismatches. This paper discusses a proposal for electronic tuning for WPT receivers by means of a variable active switch-mode inductance. The proposed method benefits from the gyrator concept to emulate a variable inductance. Instead of the conventional approach of linear amplifier based implementation of a gyrator, a switch-mode gyrator circuit is exploited for more efficient operation. Additionally, a PLL-like control is presented to enable self-tuning for the receiver resonant tank. Furthermore, a design-space characterization for the system dynamic behavior has been discussed to show the control robustness and the instabilities (including slow-scale and fast-scale chaotic instabilities) it may undergo.
A Novel Single-switch Phase Controlled Wireless Power Transfer System
Electronics
Battery charging is a fundamental application of Wireless Power Transfer (WPT) systems that requires effective implementation of Constant Current (CC) and Constant Voltage (CV) power conduction modes. DC-DC converters used in WPT systems utilize large inductors and capacitors that increase the size and volume of the system in addition to causing higher DC losses. This work proposes a novel single-switch active rectifier for phase controlled WPT systems that is smaller in volume and weight as compared to conventional WPT topologies. The proposed method simplifies the control scheme using improved Digital Phase Control (DPC) and Analog Phase Control (APC) to realize the CC and CV power transfer modes. Furthermore, it prevents forward voltage losses in Silicon Carbide (SiC) switches and shoot through states with improved switching patterns. Simulation studies and experimental results are added to verify the effectiveness of the proposed methodology.
Embedded systems as programmable square wave generator in wireless power transfer
This study focuses on the design and development of programmable frequency generator using embedded devices that are able to produce square wave signals in the wireless power transfer (WPT) transmitter. We validate the accuracy of the output signal by measuring distance error. We validate that our system can change and sweep the frequency and produce high power by measuring the absorbed power in the load. We conduct the frequency sweep analysis to find optimal frequency and the frequency splitting phenomenon. The experiments show that the system can produce and sweep the square wave signals with less than 1% error. We also find that the frequency splitting occurred when distance among two coils in the range 0.5-6.5 cm and the splitting disappeared when the distance is above 7.5 cm. The frequency splitting shows that the measured optimum frequency differs from the calculation. The difference confirms that the programmable frequency generator is needed to adjust the frequency that can transfer maximum power to the load.
Electronics
For high-power single-transmitter single-receiver wireless power transfer (STSRWPT) systems, the coils suffer from high voltage and current stresses. With increased power requirements, the coils become bottlenecks for power flow. To increase the power level, multiple-transmitter multiple-receiver wireless power transfer (MTMRWPT) systems with parallel circuits are developed that reduce the voltage and current stresses on the coils and improve power-handling capability. Firstly, an improved current distribution (ICD) control strategy is developed to simultaneously achieve high transfer efficiency, balanced current distribution and constant output voltage. Secondly, it is further shown that the ICD control strategy has the advantage that the currents at the transmitter coils are balanced and it reduces the control complexity simultaneously. Thirdly, an asynchronous particle swarm optimization (APSO) algorithm is applied to the ICD control strategy to verify the feasibility of the prop...
Comparative evaluation of control methods for Inductive Power Transfer
2012
Inductive Power Transfer (IPT) has recently been proposed for application with Electric or Hybrid Electric Vehicles (EV/HEV), where a highly efficient system operation is demanded for the highpower transfer. Due to the high requirements on the regulation of the output power and the output voltage, and due to the large variations of the magnetic coupling, the control of these systems is a challenging task. In this paper, the frequency characteristics of a series-parallel compensated IPT system are discussed. Different control methods found in the literature are analyzed and a comparative evaluation of the current and voltage stress in the transmission coils, the resonant capacitors, and the semiconductors in the primary-side inverter is presented. It is shown that the dual control method offers a number of advantages in the controllability and potentially lower losses compared to the frequency control which is commonly used.