Mutual Inductance Estimation Research Articles

Coordinated Control of Constant Output Voltage and Maximum Efficiency in Wireless Power Transfer Systems

This article presents a coordinated control method used for wireless power transfer (WPT) systems. This method can improve WPT system transmission efficiency while maintaining the constant output voltage. First, the topology of the DC–DC converter is selected and the equivalent circuit model of the WPT system is established. Then, the WPT system characteristics are discussed and the mutual inductance estimation process is presented. Furthermore, the coordinated control method is proposed, where the constant voltage output is achieved by connecting the Buck–Boost converter after the diode rectifier. Meanwhile, the optimal phase shift angle is calculated and sent to the controller to achieve maximum transmission efficiency tracking control, according to the measured load voltage and current. Finally, simulations and experiments are adopted to verify the proposed coordinated control method. The experimental results indicate that the average system transmission efficiency is increased by 1.80% and the efficiency fluctuation is decreased by 2.67% when the system load resistance varies, while the average system transmission efficiency is increased by 1.80%, and the efficiency fluctuation is decreased by 3.14% when the mutual inductance changes. This means the proposed coordinated control method is effective under the conditions of the WPT load and mutual inductance variations.

Mutual Inductance Estimation of SS-IPT System through Time-Domain Modeling and Nonlinear Least Squares

Mutual Inductance Estimation of SS-IPT System through Time-Domain Modeling and Nonlinear Least Squares

A Noncommunication Mutual Inductance Estimation Method for Multiple Transmitters SS-Compensated Dynamic Wireless Power Transfer With Low Calculation Effort

A Noncommunication Mutual Inductance Estimation Method for Multiple Transmitters SS-Compensated Dynamic Wireless Power Transfer With Low Calculation Effort

Novel Design of Multi-DOF Motor Position Estimation Based on Wireless Power Transmission Modeling

In this paper, a multi-coil wireless power transmission model is presented. The model is applied to the multi-degree-of-freedom (multi-DOF) motor rotor position detection system. The wireless power transmission (WPT) system is evenly distributed on the upper part of the rotor, and the receiving coil is placed on the rotor shaft. When the motor rotor rotates along the three motion states of pitch, spin and tilt, the receiving coil and multi-transmit coil will produce angle deviation. The precise mutual inductance estimation method can be used to obtain the rotor position quickly and avoid the complicated finite element calculation. The system can not only realize the pose estimation of the multi-DOF motor, but also provide flexible energy supplement for the manipulator. The WPT position measurement method is used for PID control of multi-DOF motor, and it is compared with the micro-electro-mechanical-system (MEMS) attitude measurement method. The mechanical sliding measurement method of the encoder is taken as a reference. The results show that the position detection method of WPT has high accuracy, and the estimation error is less than 2%.

Power Distribution Control Method in Communication–Free MIMO–WPT Through Load Impedance and Mutual Inductance Estimation

Power Distribution Control Method in Communication–Free MIMO–WPT Through Load Impedance and Mutual Inductance Estimation

Phase-Identification-based Mutual Inductance Estimation Methodology for Modular Wireless Power Transfer Systems

Phase-Identification-based Mutual Inductance Estimation Methodology for Modular Wireless Power Transfer Systems

Rotating-Coordinate-Based Mutual Inductance Estimation for Drone In-Flight Wireless Charging Systems

This article proposes a fast and real-time mutual inductance estimation method for drone in-flight wireless charging systems against the continuous varying of relative position between coupling coils. In previous studies, many efforts have been made to achieve accurate mutual inductance estimation when fixed misalignment occurs in coupling coils. However, the critical challenge for in-flight wireless charging systems is to track variations of mutual inductance caused by continuously changed misalignments between coupling coils, which is rarely explored in previous studies. Accordingly, this article proposes a rotating-coordinate-based mutual inductance estimation method to track the variation of the mutual inductance timely. By applying the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> dynamic model, the proposed estimation method is effectively enhanced in terms of rapidity and implemented simply as well as eliminating wireless communication links. With the salient features of accuracy, rapidity, and real time, it can be an ideal solution against the continuous disturbance of mutual inductance, especially for drone in-flight wireless charging systems. In this article, both simulated and experimental results are given to verify the validity of the proposed rotating-coordinate-based estimation method, wherein the relative error of the mutual inductance estimation is within 1%, and the estimation rapidity is less than 4 ms.

Contactless-Sensor-Based Output Feedback Control With Maximum Efficiency Tracking Technique in Inductive Power Transfer Systems

To maximize the overall efficiency of a series-series inductive power transfer (SSIPT) system, the maximum efficiency tracking (MET) control should be employed. Based on a contactless current sensor which is designed for the mutual inductance estimation and the output voltage feedback, this paper proposes a novel MET control method for the SSIPT system with front-side and load-side converters. In this method, the output voltage of the rectifier on the load side is estimated and used as a control reference on the front side. Moreover, this paper analyzes the small-signal model of the SSIPT system and presents an impedance-based stability criterion. The factors which influence output feedback control are investigated, and a comprehensive control strategy based on the impedance stability criterion is developed. Finally, a 600 W prototype is built to validate the proposed method. MET control is implemented in a wide range of load variations, with a maximum efficiency drop of approximately 2.3% over a 100 mm misalignment. The results show that the proposed scheme significantly improves the robustness and response performance of the SSIPT system.

Mutual Inductance Identification of IPT System Based on Soft-Start Process

Accurate estimation of mutual inductance in wireless power transfer (WPT) system is a prerequisite for accurate identification of load parameters, which is critical in system constant output and efficiency tracking control. In this article, a general load decoupling method for WPT system considering soft-start process and battery initial voltage is proposed. Moreover, a double-sided <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> topology is used to explain how to calculate the boundary conditions of load decoupling. Based on the proposed load decoupling method, a mutual inductance identification method is proposed for WPT system with double-sided <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> topology. Within the frequency range recommended, the unique solution of mutual inductance can be obtained by solving high-ordered equivalent impedance equation. In this case, there is no need to discuss the situation for multiple solutions. Based on the WPT prototype, the effectiveness of the proposed load decoupling method is verified, and parameter sensitivity of the identification method is analyzed in detail. Finally, the proposed method is experimentally verified. Results show that high identification accuracy can be achieved even when the coils are misaligned. Compared with the existing identification methods, the proposed method does not need any additional switches and auxiliary circuits, which reduces the complexity and system cost effectively.

Inductive Power Transfer System With Maximum Efficiency Tracking Control and Real-Time Mutual Inductance Estimation

To design simple and efficient inductive power transfer (IPT) systems, a minimum number of conversion stages and an effective maximum efficiency tracking (MET) are the primary design criteria. The MET control uses a fast mutual inductance estimation (MIE) algorithm to achieve fast tracking of the maximum efficiency point, especially when the variation of the gap distance and misalignment of the magnetic coupler are significant. The feedback control of the MET-MIE IPT system should be designed without a wireless communication channel to improve stability and robustness. In this article, a novel MET-MIE control strategy is proposed for achieving simplicity and high efficiency in IPT systems. Verifications are provided by simulations and experiments. It is shown that maximum efficiency can be tracked with less than 4&#x0025; error in MIE under significant variation of the gap distance and misalignment of the magnetic coupler.

Artificial Neural Network-Based Parameter Identification Method for Wireless Power Transfer Systems

In this paper, a Wireless Power Transfer (WPT) system parameter identification method that combines an artificial neural network and system modeling is presented. During wireless charging, there are two critical parameters; specifically, mutual inductance and load resistance, which change due to the movement of the transmitter/receiver and battery conditions. The identification of these two uncertain parameters is an essential prerequisite for the implementation of feedback control. The proposed method utilizes an Artificial Neural Network (ANN) to acquire a mutual inductance value. A succinct system model is formulated to calculate the load resistance of the remote receiver. The maximum error of the mutual inductance estimation is 2.93%, and the maximum error of the load resistance estimation is 7.4%. Compared to traditional methods, the proposed method provides an alternative way to obtain mutual inductance and load resistance using only primary-side information. Experimental results were provided to validate the effectiveness of the proposed method.

Mutual inductance estimation between rectangular structures magnetic coils with various misalignments for wireless EV charger

Mutual inductance estimation between rectangular structures magnetic coils with various misalignments for wireless EV charger

Mutual inductance estimation between rectangular structures magnetic coils with various misalignments for wireless EV charger

Mutual inductance estimation between rectangular structures magnetic coils with various misalignments for wireless EV charger

Flexible Energy-Transfer Control of Dynamic Wireless Power Transfer System Based On Estimation of Load and Mutual Inductance

Dynamic wireless power transfer (DWPT) technology is gradually making the prospect of charging on road of EVs (electirc vehicles) possible. However, DWPT system should be optimized in many aspects before it can really be utilized on road. For example, the control of energy transfer for a DWPT system is much complicated than a static wireless power transfer (WPT) system since the coupling of transceiving coils changes with the moving of the EV. In this article, an energy transfer control method based on the estimation of the load and mutual inductance of the segmented DWPT system is proposed. The relation between the load and the reflected impedance of the primary side is studied, and the parameters of the secondary-side <i>LCC</i> network are tuned to avoid the two-solution problems in the estimation of the load. Based on the results of estimation, a two-cases controlling strategy is proposed to switch between power-<small>on</small> station and detection station of the DWPT system according the target of energy transferring. A 800-W prototype of four-transmitting-coil dynamic WPT system is built and experiments show that the proposed energy-transfer control is proved to be efficient to regulate the energy and achieve fast response characteristics. Compared with the traditional controlling methods which usually aim to achieve maximum energy transfer, the method in this article can control the transferred energy according to the target value of energy, making the control more flexible without the use of communication.

Mutual inductance estimation of multiple input wireless power transfer for charging stationary vehicles in parking spaces

The electric vehicle (EV) is the future of the modern automotive industry. However, the transmission performance of traditional wireless charging is highly influenced by the misalignment error between the transmitter and the receiver. This paper proposes a maximum power control method for the multiple transmitter coil wireless charging system, which can be used to charge stationary EVs freely and effectively in a wider range. An accurate and reliable mutual inductance estimation method is introduced to estimate M relying on the electric information on the transmitter side only without using empirical formulas and additional communication devices between both sides. Then, the paper proposes a control method, which can maximize the output power in a quite wider range. Experiments and simulations prove that the proposed method has a good performance on charging a receiver coil effectively in a wider range; therefore, it is suitable for charging stationary EVs in the parking space.

Mutual Inductance Estimation of Multiple Input Wireless Power Transfer for Charging Electronic Equipment

The transmission performance of wireless power transfer is highly influenced by the mutual inductance (M) between the transmitter and the receiver. This paper proposes a mutual inductance estimation method for the multiple input coils wireless charging system which can be used in low-power portable devices such as mobile phones. The method can estimate M precisely and reliably without using empirical formulas and additional communication system. It simplifies the estimation process and achieves more accurate values of M under any conditions. Simulations and experimental results prove the proposed method has a good performance on estimating M at any circumstance.

A Wireless Power Transfer System With Dual Switch-Controlled Capacitors for Efficiency Optimization

This article proposes a novel wireless power transfer (WPT) system with switch-controlled capacitor (SCC) where variable capacitance and efficiency optimization are realized. The optimum asymmetrical voltage cancellation (OAVC) control is applied to realize wide-ranging soft-switching operation for the active bridge converters. The pulsewidth of the active bridge inverter regulates the output voltage, and the pulsewidth of the active bridge rectifier optimizes power delivery efficiency. The SCCs in the transmitter and the receiver sides are regulated for the zero-voltage switching operation and the resonant condition, respectively. The online estimation of mutual inductance is carried out to adapt the coupling deviations of the WPT system in real time. A 650-W prototype is built to verify the feasibility of the proposed WPT system and the effectiveness of the OAVC control. The experimental results show quite good performance and efficiency improvement for the WPT system at various loads.

Load and mutual inductance estimation based on phase‐differences for electric vehicle wireless charging system

In this study, a new method to estimate the load and mutual inductance for a wireless charging system (WCS) is presented. Instead of simultaneously using the root mean square and phase angles of related voltages and currents, accurate estimations can be obtained through the phase differences in the primary side. Firstly, the WCS model with dual-side inductor–capacitor–capacitor compensation networks is established, and the reflected impedance is analysed based on the phase differences in the primary side. Then, the estimation calculation of load and mutual inductance is derived according to the reflected impedance. Meanwhile, the output voltage estimation in the primary side is realised based on the estimated values of the load and mutual inductance. Finally, experiments are conducted to verify the effectiveness of the proposed method in the 3.3 kW electric vehicle wireless charging experiment platform. Experimental results show that the estimation errors of the load and mutual inductance are <5 and 3.5%, respectively, and the system output voltage can be effectively estimated based on their estimated results.

Adaptive position alignment for wireless charging system with mutual inductance estimation and P&amp;O algorithms employ only primary‐side electrical parameters

Position alignment between the transmitter and the receiver is vital for wireless charging system (WCS) because misalignment influences system efficiency, power transfer capability, and magnetic field distribution. Based on the primary-side electrical parameters, the mutual inductance estimation and perturbation and observation (P&O) algorithms are proposed to achieve the adaptive position alignment for the inductor-capacitor-inductor-series (LCL-S) compensated WCS through the movable transmitter. Based on the relationship between primary-side active power and mutual inductance, the feedback impedance theory and quadrature transformation (QT) algorithms are proposed to estimate the mutual inductance. Combined with the misalignment characteristic of circular magnetic coupler, the position alignment that is achieved by P&O algorithm and estimated mutual inductance. The simulation and experimental results verify the following conclusions: The mutual inductance estimation is suitable for different magnetic coupler and compensation topologies, and the accuracy of the estimated mutual inductance is suitable for practical applications. Compared with traditional active power method, the QT algorithm that calculates is more suitable for WCS that features high operating frequency. Combined with the proposed algorithms, high-system performance and fully automatic charging are ensured by the adaptive position alignment method.

Power Allocation for Dynamic Dual-Pickup Wireless Charging System of Electric Vehicle

Power allocation is important for dynamic dual-pickup wireless charging system of electric vehicles (EVs). The existing power allocation methods of wireless power transfer technology mainly focus on allocating the power to loads according to the needs with different resonant frequencies. However, the issues of inaccuracy and low power are still not well solved by the existing methods. In addition, the control strategies of existing methods are complex and difficult to implement in practical situations. In this paper, a new power allocation method is proposed, which can dynamically and precisely allocate power to loads. Moreover, the dynamic mutual inductance estimation and the power ratio change between loads are also investigated. In addition, this method has no need to use additional circuits for the receiving coil. Thus, it is convenient to implement in the dual-pickup wireless charging system of EVs. Experimental results have well verified the correctness of the proposed dynamic mutual inductance estimation and power allocation method.