A Maximum Efficiency Point Tracking System for Wireless Powering of Biomedical Implants

Stoecklin, Sebastian; Volk, Tobias; Yousaf, Adnan; Reindl, Leonhard M.

doi:10.1016/j.proeng.2015.08.666

Cited by 8 publications

(5 citation statements)

References 3 publications

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“…An additional DC/DC converter has been used at the transmitter of the WPT system to adjust the output power. However, it increases the complexity of the WPT system and reduces the efficiency and robustness 9,10 . The phase‐shift modulation strategy has been used in Cui et al 11 to adjust the output power by changing the phase‐shift angle.…”

Section: Introductionmentioning

confidence: 99%

“…However, it increases the complexity of the WPT system and reduces the efficiency and robustness. 9,10 The phase-shift modulation strategy has been used in Cui et al 11 to adjust the output power by changing the phase-shift angle. However, when the phase-shift angle is large, the conditions for the inverter to achieve soft switching become worse, and hard switching often occurs, reducing the system efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Research on dual‐frequency modulation strategy of wireless power transfer system

Tang

Wang

Shi

et al. 2022

Circuit Theory & Apps

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Compared with traditional wired power transmission, wireless power transfer(WPT) has fully exhibited its key advantages of better safety and convenience, stronger reliability and electrical isolation, and less maintenance. Although the phase-shift modulation strategy has been widely used in various WPT applications, it has certain limitations in terms of high-frequency hardswitching, which increases the power loss of the WPT system during voltage regulation. To achieve efficient operation over a wide range of load power, this paper proposes a dual-frequency modulation strategy for the WPT system. The advantages of the dual-frequency modulation strategy are the simple modulation logic and the lower switching loss. It maintains the optimal load impedance during constant voltage output and improves the overall efficiency of the system. For validation, we designed the control circuit and wrote the control program and built the experimental prototype of the WPT system to carry out the phase-shift modulation experiment and the dual-frequency modulation experiment, respectively. The experimental results show that the soft switching range and efficiency of the WPT system under the dual-frequency modulation strategy are better. At the rated output power, the efficiency of the WPT system under dual-frequency modulation strategy is 89.75%. The feasibility of the dual-frequency modulation strategy has been confirmed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Research on dual‐frequency modulation strategy of wireless power transfer system

Tang

Wang

Shi

et al. 2022

Circuit Theory & Apps

View full text Add to dashboard Cite

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“…However, the concepts do not hold for nonlinear class E and Greinacher rectifier stages, which are commonly applied in miniaturized systems with higher operational frequencies (

). We published a similar concept based on maintaining a certain voltage transfer function [ 24 ]: here, the optimal load resistance

is determined from a look-up table after the measurement of the mutual inductance

and correspondingly established by adjusting the rectifier output voltage with an input-controlled DC/DC converter on the secondary side of the link. However, the measurement cycle of

leads to a momentary interruption of the power supply, a second DC/DC converter stage is required for voltage regulation and power feedback is not intrinsically implemented in this concept.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Power Feedback and Maximum Efficiency Point Tracking for Miniaturized RF Wireless Power Transfer Systems

Stoecklin

Yousaf

Gidion

et al. 2021

Sensors

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Near-field interfaces with miniaturized coil systems and low output power levels, such as applied in biomedical sensor systems, can suffer from severe efficiency degradation due to dynamic impedance mismatches, reducing battery life of the power transmitter unit and requiring to increase the level of electromagnetic emission. Moreover, the stability of weakly-coupled power transfer systems is generally limited by transient changes in coil alignment and load power consumption. Hence, a central research question in the domain of wireless power transfer is how to realize an adaptive impedance matching system under the constraints of a simultaneous power feedback to increase the system’s efficiency and stability, while maintaining circuit characteristics such as small size, low power consumption and fast reaction times. This paper presents a novel approach based on a two-stage control loop implemented in the primary-side reader unit, which uses a digital PI controller to maintain the rectifier output voltage for power feedback and an on-top perturb-and-observe controller configuring the setpoint of the voltage controller to maximize efficiency. The paper mathematically analyzes the AC and DC transfer characteristics of a resonant inductive link to design the reactive AC matching network, the digital voltage controller and ultimately the DC-domain impedance matching algorithm. It was found that static reactive L networks result in suitable efficiency levels for coils with sufficiently high quality factor even without adaptive tuning of operational frequency or reactive components. Furthermore, the regulated output voltage of the rectifier is a direct measure of the DC load impedance when using a regular DC/DC converter to supply the load circuits, so that this quantity can be tuned to maximize efficiency. A prototype implementation demonstrates the algorithms in a 40.68 MHz inductive link with load power levels from 10 to 100 mW and tuning time constants of 300 ms, while allowing for a simplified receiver with a footprint smaller than 200 mm2 and a self-consumption below 1 mW. Hence, the presented concepts enable adaptive impedance matching with favorable characteristics for low-energy sensor systems, i.e., minimized footprint, power level and reaction time.

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“…Some maximum efficiency point tracking (MEPT) methods for single-receiver IPT systems have been proposed [16]. A boost converter is employed in the secondary side to control the input voltage of the rectifier to maintain high efficiency in [17]. A DC/DC converter either on the primary side or the secondary side is applied to search for the maximum efficiency point by adjusting the duty cycle in [18,19].…”

Section: Introductionmentioning

confidence: 99%

A Maximum Efficiency Point Tracking Control Scheme Based on Different Cross Coupling of Dual-Receiver Inductive Power Transfer System

Liu

Yue

et al. 2017

Energies

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Abstract:One of the most promising inductive power transfer applications is the wireless power supply for locomotives which may cancel the need for pantographs. In order to meet the dynamic and high power demands of wireless power supplies for locomotives, a relatively long transmitter track and multiple receivers are usually adopted. However, during the dynamic charging, the mutual inductances between the transmitter and receivers vary and the load of the locomotives also changes randomly, which dramatically affects the system efficiency. A maximum efficiency point tracking control scheme is proposed to improve the system efficiency against the variation of the load and the mutual inductances between the transmitter and receivers while considering the cross coupling between receivers. Firstly, a detailed theoretical analysis on dual receivers is carried out. Then a control scheme with three control loops is proposed to regulate the receiver currents to be the same, to regulate the output voltage and to search for the maximum efficiency point. Finally, a 2 kW prototype is established to validate the performance of the proposed method. The overall system efficiency (DC-DC efficiency) reaches 90.6% at rated power and is improved by 5.8% with the proposed method under light load compared with the traditional constant output voltage control method.

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A Maximum Efficiency Point Tracking System for Wireless Powering of Biomedical Implants

Cited by 8 publications

References 3 publications

Research on dual‐frequency modulation strategy of wireless power transfer system

Research on dual‐frequency modulation strategy of wireless power transfer system

Simultaneous Power Feedback and Maximum Efficiency Point Tracking for Miniaturized RF Wireless Power Transfer Systems

A Maximum Efficiency Point Tracking Control Scheme Based on Different Cross Coupling of Dual-Receiver Inductive Power Transfer System

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