The wireless power transfer system of double-sided LCC topology has the characteristics of high-order and nonlinear, which increases the difficulty of controller design. In this paper, a voltage stabilizing closed-loop control system based on the model of generalized state space average (GSSA) and order reduction is proposed. The GSSA model of the system is established, and the small signal model is established according to the nonlinear characteristics of the system; Then, through the balanced order reduction method, the 17th order system is reduced to the 3rd order system; Furthermore a PI controller is designed to ensure the stability of the 6.6kw electric vehicle wireless charging system, output voltage; Finally, by the simulation results of the closed-loop control system, that the transient response time of output voltage is 15ms and the response time of load switching is 14ms, and the effectiveness of the proposed mothed is verified.
In this paper, the control problem for the inductively coupled power transfer (ICPT) system with soft faults and input disturbances is investigated by a observer based fault tolerant control approach. The soft fault estimation method is based on a k-step EF observer, which can effectively decrease the influence of the disturbance produced by soft faults. Furthermore, the fault tolerant controller is realized by applying the dynamic output feedback control (DOFC), which does not need the knowledge of the system state in detail and has more adjustable parameters. Secondly, based on the Lyapunov theorem, some new stability results of the ICPT system under soft faults and input disturbances are obtained. The proposed method for stability analysis considers every variable in the system. After inequality expansion and contraction, all the variables are still preserved. Moreover, the approach shown in this paper can also be applied to other similar systems. Finally, the simulation verification results are listed to indicate the effectiveness and correctness of the proposed fault diagnosis and fault-tolerant control methods.
For medium and high power applications, parallel converters are commonly utilized to boost the power capacity of system. Meanwhile, interleaved operation of pulse width modulation (PWM) is a common and effective method to increase the number of output levels and reduce current ripples. Nevertheless, due to asynchronous switching operation, the problem of circulating current inevitably emerges. To suppress circulating current, this paper aims to analyze the principle of circulating current generation and design the parameters of the inductors for suppression. A 100kW grid-connected system with two T-type inverters parallel connected is built, applying phase opposition disposition (POD) modulation for decreasing circulating current. The LCL filter is designed to achieve low harmonics. Simulation validations are provided to prove the feasibility of the analysis and design.
In recent years, wireless power transfer (WPT) technology has been gradually applied in various fields. In the process of wireless charging, due to the randomness of the position of the secondary side and the randomness of the received power level by the secondary side, the WPT system is required to determine the charging state through information exchange. In this paper, a power and data parallel transfer technology for wireless power transfer based on hybrid electric field coupling and magnetic field coupling is proposed, which effectively utilizes the advantages of magnetic field coupling to easily realize high-power and long-distance wireless power transfer and the advantages of electric field coupling and electric field concentration to improve the system. By using this structure with a single capacitive pole plate to transmit the signal, the data transmission is almost independent of the power magnetic field and the output voltage is controlled by the closed loop of the data transmission channel, allowing for stable power transmission.
In electric vehicle wireless power transfer (EVWPT) systems, misalignment tolerance has always been one of the concerns. This paper proposes an optimization method of EVWPT system misalignment tolerance through coupling mechanism design and circuit topology analysis. Using the mutual inductance complementary characteristics of the compensation coil and the receiving coil, and using the output series topology, the system has good misalignment tolerance performance and constant voltage (CV) output characteristics. Theoretical analysis and simulation results verify the effectiveness of the proposed method, and the system can achieve good load-independent CV output within the range of 50% misalignment.
Switched-capacitor technique has a good application for voltage source circuits. On the other hand, the switched-inductor approach in current source circuits can also produce different possibilities for the output circuit. When the tapped inductor is added to the circuit, it will affect the load side again, and the way to access the circuit is different; it is conversion has an extensive range. This paper introduces the method, in the case where the components remain unchanged and the circuit connection mode changed, to make the output current change during the use of the relevant power circuit. How to calculate and design the power supply circuit you need according to your needs during the use of the appropriate power supply circuit. This circuit can be applied to photovoltaic cell output conversion, current mode motor control, and some energy distribution. It can also be used in electric vehicle (EV) power conversion. The current mode control is especially used for current mode charging of EV charger.
For the space omnidirectional wireless power transmission technology and system, a flat D-core structure is proposed in this paper. By comparing the characteristics of various current soft magnetic materials, a suitable core material is selected. According to the simulated magnetic field distribution characteristics of the core in various attitudes, the receiving coil is designed as the combination of three sets of orthogonal and independent coil structures, and the influence of structural parameters, such as the width and thickness of the core, on the performance of the coupling mechanism is analyzed. Finally, the equivalent mutual inductance between the coupling mechanism proposed in this paper and the existing coupling mechanism with similar structure is analyzed and compared by means of simulation and experiment. The output characteristics of the omnidirectional wireless power transmission system based on the coupling mechanism are tested, and the results show that the equivalent mutual inductance value of the coupling mechanism proposed in this paper is greater than the existing mechanisms under the same conditions.
High-power-factor resonant system is of key importance to improve the transmission efficiency and power of inductive-coupled wireless power transfer system. However, quality factor of resonant circuit is vulnerable to system parameter changes, which causes system detuning. The adaptive-tunning technology solve the detuning problem by rematching the resonance parameters so that the system can always work in the resonant state, ensuring the efficient and high-power transmission of the system. Because of the unique features of wireless power transfer system including isolated transmitter and receiver side, delay of communication, and wide-range parameter variation, there is additional challenges of adaptive-tunning technology compared to its application in traditional converters. This paper firstly introduces the resonance characteristic of wireless power transfer system, then summaries the existing adaptive tunning technologies, including frequency tracking and dynamic compensation. Finally, a summary regarding adaptive tunning of WPT systems are discussed.
Fourier modelings of the inductance of switched reluctance machines have been extensively investigated extensively in the past, but the skills are restricted to the construction of the inductance profile model at a known motor position. This paper gives a presentation of a novel sensorless position estimation method based on online sinusoidal modeling of relative inductance for switched reluctance motors at startup. The background of this method is based on sinusoidal fitting and only very few data points are needed. It is numerically efficient and can provide accurate position information for each phase. There is no special requirement on the inductance profile of the machine, and the magnetic characteristics of the machine are not required. The method is simple and easy to implement. Experimental results have confirmed its validity.
Electric vehicles (EVs) are thriving to alleviate environmental issues. Conventional two-stage onboard charger (OBC) in EV only contains one large-power DC/DC converter to connect the whole battery pack to the inverter. It requires dozens of battery cells to connect in parallel and then in series for charging. Parallel connection causes circulating current among batteries, increasing the loss and safety risk and decreasing the battery life. Aimed at diminishing the circulating current by reducing parallel connections of battery cells, a distributed OBC architecture is proposed in this paper. It contains a bi-directional inverter and numerous paralleled bi-directional low-power DC/DC converters. The batteries are divided into multiple clusters with less paralleled cells to interface with those DC/DC converters, respectively. Furthermore, a novel virtual synchronous machine (VSM) control is proposed for the distributed OBC, enabling the OBC to provide inertia and frequency regulation to the grid and to serve as an emergency power supply in island mode. Compared to the conventional OBC, the distributed OBC under the proposed VSM control achieves higher fault tolerance, better power allocation, less circulating current among batteries, and less current impact on the batteries. Those priorities are finally verified by simulation results.
During the three years of Pandemic Disease, the world of academic teaching has had a substantial change. The usual in-person or face-to-face teaching has been transformed into online teaching. For electrical engineering, the instruction usually includes heavyweight experiments or practical tests; therefore, online teaching faces challenges. A recent electric vehicle course has been proposed in the Master level and the challenge of the course is reported in this paper. The experience that has been encountered is discussed and the proposed method of teaching is described in the paper. Useful experience and learning outcomes are listed. Data are collected before and after the Covid-19 teaching. It is found that online education did not deteriorate the learning outcome.
A method to improve the transmission distance of the wireless power transfer system is proposed using a coupler in which the transmit and receive coils are coplanar double-coil, respectively. Compared with the traditional two-coil coupler, the coupler adds a passive coil on the same plane of the primary side and the secondary side respectively, which does not occupy the power transmission space. The circuit model using series compensation is established. The frequency characteristics and power transfer capability of the system are analyzed. The resonant frequency is optimized. The proposed coupler is found to have stronger coupling and lower coil self-induced voltage than the two-coil system, which is suitable for long-distance wireless power transfer. Finally, a simulation model was built to achieve a transmission distance of 50cm and transmission power of 4kW.
With a number of energy storage converters connected to the grid, transient instabilities about energy storage converters are more likely to appear when some problems happen in the grid. In order to work out the difficult problem about the instability of energy storage converters, this paper proposes an approach of modifying the phase-locked loop (PLL) to improve transient stabilities of energy storage converters, which can increase the quantity of intersections in the system after the grid fails. And then, the influence of the grid voltage drop degree on transient stabilities of energy storage converters are analyzed by drawing the phase diagram of phase difference, the analysis results show that when the parameters of the PLL and line impedance are set reasonably, the more serious the grid voltage drop is., the more likely the energy storage converter is to be unstable. The method proposed in this paper can stabilize the system with no or only one intersection after a fault., and the control method is simple., and the effect is obvious. At last., the simulation proves the accurateness of analysis in the paper.
Hydrogen Proton Exchange Membrane (PEM) fuel cell is considered today as a promising technology for low-carbon transport applications. The successful deployment of fuel cell technology in automotive sector is a key element to reach out the European Union's CO 2 emission goal by 2050. After years of developments by research institutions and enterprises, the automotive fuel cell technology has gradually introduced to the market since 2015. In this keynote, we will explore together the key technologies of modern commercial fuel cell electric vehicles, such as Toyota Mirai 1 and 2, Honda Clarity Fuel Cell, etc. The place of fuel cell technology in our future low-carbon transports and the main challenges will be discussed.
In this paper, a three-dimensional (3-D) rotating magnetic field modulation method based on phase-shift control is proposed to realize omnidirectional wireless power transfer (WPT). The proposed method can realize 3-D omnidirectional WPT when only a planar single-coil receiver is used. In addition, the proposed method does not need to detect the orientation of the receiving coil, complex control, and communication links. Firstly, the magnetic coupler and circuit structure of the system are given, and then the working principle of a generating three-dimensional (3-D) rotating magnetic field is introduced. On this basis, the modulation method of the 3-D rotating magnetic field is given. Finally, the effectiveness of the proposed method to achieve 3-D omnidirectional WPT is verified by simulation. The simulation results show that the pickup power is maintained at 62-77W when the receiver rotates arbitrarily.
This paper proposes a position-insensitive wireless power transfer (WPT) system which can realize zero phase angle (ZPA) and constant voltage (CV) output only by primary variable frequency control. An integrated electromagnetic coupler is introduced, as well as its 3D simulation model and equivalent circuit model. The self-compensating principle of the WPT system is presented, and the condition for achieving ZPA and CV output is given. Through Maxwell simulation, vast amounts of data about capacitances and inductances of the coupler varying with the transfer distance and misalignment distance is obtained. With the obtained data, the artificial neural network (ANN) model based on back propagation algorithm is established for parameter prediction, so as to solve the resonant frequency. Therefore, the switching frequency can automatically follow the change of the transfer distance and misalignment distance of the coupler. When the transfer distance, misalignment distance and load resistance change, the output voltage of the system can keep constant without any DC/DC control circuit or voltage regulation control. Finally, a simulation model is built, which verifies the feasibility and effectiveness of the proposed WPT system.
Due to its high efficiency and energy savings, permanent magnet synchronous motors are frequently utilized in the joints of cooperative robots. Most of these motors are single-stator motors. The predominant issues of the single-stator motor are low torque density and giant torque ripple, which result in inadequate load capability and chattering in the course of operation. This paper proposes a dual-stator motor with a 70 mm outer diameter to solve this problem. The physical model of the dual-stator motor is established for performance analysis and control simulation. The performance analysis of the dual-stator motor, which mainly focuses on the electromagnetic field, is conducted in Ansys Electronics. Simulation of magnetic field oriented control using mathematical model is conducted in Simulink. Under the conditions of 200 rpm (revolutions per minute) and 5 A effective current, the average torque of the motor reaches 4.74 N m, and the torque ripple is only 2.3%. The result proves that the proposed dual-stator motor has larger torque density and smaller torque ripple than the traditional single-stator motor with the same specification. The magnetic field oriented control is used when the motor tracks 200 rpm. The control simulation analysis shows that the overshoot is less than 1%, and the rise time is 0.015 s.
The traditional power equipment material quality control business relies on the work experience of field operators, it fails to form standardized digital information records, and has poor traceability. In order to improve the above problems, this paper designed a digital power material quality control information system based on augmented reality technology, and developed an augmented reality wearable intelligent terminal device based on 5G communication and artificial intelligence technology. This has formed an innovative operation mode of audio and video recording of important work information at business key points and remote interactive support of experts; The professional orientation functions such as spatial ranging, vernier caliper reading recognition and partial discharge characteristic spectrum recognition are realized. Relying on the developed system and device, the digital upgrade, cost reduction and efficiency increase of power equipment manufacturing supervision, inspection and detection business are realized.
A matrix converter (MC) based wireless power transfer (WPT) system for high-speed train is proposed in this paper. The pantographs in conventional traction system are replaced with the transmitting and receiving coils in WPT system. Therefore, the reliability can be increased and the maintenance cost for pantographs will be reduced. Moreover, the DC-link capacitors which are required in conventional two-stage WPT system is eliminated with MC. Therefore, the system reliability and power density can be increased wilt the absence of physically large and heavy aluminum electrolytic capacitors. Finally, a laboratory prototype is designed and experiments are carried out to verify the effectiveness of the proposed MC based WPT system.
Under the weak grid, photovoltaic grid-connected inverter generates a lot of harmonics in the process of inverter, and the stable operation of system is affected by the inherent resonance phenomenon when LCL filter is used for filtering. In this paper, the traditional grid-connected current feedback(TGCCF) control method is firstly studied. At this time, the inherent resonance phenomenon is not effectively suppressed. Furthermore, a control method of inverter-current-feedback active damping (ICFAD) is proposed to effectively suppress the resonance. As there is only one current control, the inhibition effect needs to be improved. Based on this, a control method of inverter-and-capacitor-current-feedback active damping (IACCFAD) is proposed. It is beneficial to enhance the resonance suppression effect, improve robustness and stability of the inverter system, and improve current quality. The correctness of the above conclusions is verified by simulation.
