Wireless High-Power Transmission

The research work "Drahtlose Energieübertragung für hohe Leistungen" aims to optimize inductive power transfer systems by increasing the power density, optimizing the efficiency and reducing the design effort. First, a new type of reactive power compensation is used to reduce the losses in the inductive power transmission and in the inverter. Second, a planar structure is designed, which includes not only an efficient planar coil but also a powerful cooling.

The aim of the novel reactive power compensation is to compensate the reactive power produced by the inductive power transfer. This is made possible by a magnetically coupled resonant circuit that is integrated in the structure. This results in lower coil and inverter losses.

A design with planar coils is used for the construction. On the one hand, it provides powerful cooling due to a large-area thermal connection between the coils and the cooling system. On the other hand, the planar coils ensure high power transfer in a wide range of frequency and power.

The use of the novel reactive power compensation with the planar design results in a

• compact structure,
• high power density,
• high power transfer and
• high efficiency.

In addition, no external passive components (external compensation circuit) are required to operate this inductive power transfer with an inverter in an efficient operating range.

More information can be found in the literature [1].

Fig 1: Electrical equivalent circuit of the novel inductive power transfer. It shows a four-coil structure, which consists of two main und two compensation coils.

Fig.2: Sketch of the new inductive power transfer with planar coil design. The coil design consists of two equal sides, each with a large area magnetic coupling of the compensation coil to the main coil und a large area of ​​heat dissipation to the cooling system.

Fig.3: Main und compensation coil integrated on a two-layer-PCB with exemplary SMD- capacitor for the resonant (compensation) circuit: round design (left) and compressed design (right)

Fig. 4: Thermal measurement of a planar coil at 4,5kW (power transfer) und 150kHz (operating frequency). The planar coil diameter is 150mm and the air-gap is 30mm.