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.
