Voltage control to maximize the transmission efficiency of a multi‐input and multi‐output wireless power transfer system

Abstract

In multi‐input and multi‐output (MIMO) wireless power transfer (WPT) systems, the destructive interference between multiple transmitters and receivers brings a serious impact on power transmission efficiency. This paper proposes a voltage control strategy to maximize the transmission efficiency of a MIMO WPT system by controlling the amplitude and phase of the transmitter voltages. However, the complexity of the realistic WPT circuit topology and the uncertainty in the related parameters obstruct the establishment of an accurate closed‐form description of the WPT model to optimize the transmission efficiency of the system. In this paper, a simple multi‐port network model is introduced to simulate a MIMO system to avoid the complex circuit topology and a large number of circuit elements. To determine the parameters of the proposed model, a simple yet efficient methodology, by sequentially changing the excitations of the input ports and sampling the responses at the out ports, is proposed. A voltage control methodology to optimize the transmission efficiency of a MIMO wireless power transfer system is finally developed. To validate the proposed model and voltage control methodology, a three‐input and three‐output WPT prototype is designed and fabricated and used as the experimental platform. The performances of the proposed voltage control methodology are compared to both the experimental ones and those without the proposed voltage control methodology.

Compensation of Cross-Coupling in MIMO Inductive Power Transfer Systems

“…This feature makes our scheme practical because relative positions of the coils in an array are usually unchanged, although the two arrays may move during the charging process. Our design is also independent of the source voltages and the loads as in existing methods [29]- [34]. 3) Effectiveness of the proposed scheme will be verified by transfer matrix analysis, followed by full-wave electromagnetic (EM) simulations and experiments.…”

“…Instead of avoiding the cross-coupling, other works have attempted to reduce its impact. Reducing the impact of crosscoupling has been investigated in [29]- [34] by adjusting the system parameters, e.g., resonant capacitors, amplitudes and phases of source voltages accordingly to the load resistances and the transmission distance. However, this adaptive control approach is impractical as the loads and the transmission distance usually vary during charging time, making the control very hassle.…”

“…In addition, (26) and (31) show that the proposed compensation network for either the primary side or the secondary side is decided only by the cross-coupling within each side and is independent of power sources and load resistances. This means that, once the compensation circuits are implemented, there is no need to adjust circuit elements during the charging process as in [29]- [34]. It makes the proposed method more practical because the proposed method does not require hassle controls of the phases of source voltages accordingly to the load resistances.…”

Study on the Coil Position Adaptive Adjustment Control Scheme of Wireless Power Transfer System

“…In order to improve misalignment tolerance of wireless charging during the movement of the electric vehicles, based on the asymmetric coils, an input-parallel output-series topology WPT scheme with modular extension and misalignment tolerance was proposed in Ref. [14]. In order to solve the problem that the transmission efficiency decrease as the misalignment occurs, an anti-misalignment WPT system was proposed by integrating a nonlinear capacitor at the transmitter and introducing a nonlinear inductor at the receiver, and the robustness of the WPT system to coil misalignment was improved [15].…”

Misalignment tolerance improvement and high efficiency design for wireless power transfer system based on DDQ‐DD coil

“…To achieve higher misalignment tolerance and efficiency, various studies have focused on system control, compensation topology, and coil design 3 . System control is typically accomplished by duty control, 4 inverter phase adjustment, 5 and autotuning, 6 but these processes result in increased energy consumption and can be challenging to implement. The compensation network can enhance the power factor and increase the transmission efficiency 7,8 .…”