To achieve a free-positioning wireless power transfer (WPT) system, the output power must be regulated throughout the operation. This paper presents a novel output power control of a WPT system, based on the model predictive control (MPC). The output power is predicted by utilizing the system's mathematical model. The optimal duty cycle for a desired output power is obtained through the minimization of the objective function, which is simple and easy to implement, with no need for gain tuning. The proposed controller is implemented on the primary side, without any measurement or communication devices on the secondary side. This reduces the cost, size, and complexity of the WPT system. The load resistance and mutual inductance identification method is also introduced. It is based on the reflected impedance knowledge, where only the information of primary current is required. Experimental results of the output power step response show better performance compared with conventional Proportional-Integral (PI) control. The proposed controller is experimentally validated on a 200 W kettle. The output power can be kept constant at 200 W while the kettle is laterally moved. With the proposed controller, the kettle can be placed freely up to 7 cm from the align position, which is 63.64% of the primary coil's outer radius.

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This paper presents an inverter topology for a wireless power transfer (WPT) system that is intended to reduce the component counts and complexity of the conventional excitation circuit for multiple transmitter coils. The proposed inverter topology requires only (n+2) power switches, where “n” is the number of transmitter coils. An excitation of a proper transmitter coil pattern with regard to the receiver coil position is determined. The output voltage can be regulated through the primary-side control by adjusting the duty cycles of the inverter switches. A detection method of the receiver coil position is presented using the detection switches on the secondary side. The detection algorithm is based on the reflected impedance knowledge and requires only a current sensor on the primary side. A proper transmitter coil pattern is energized to ensure maximum transfer efficiency throughout the operation. The proposed system is experimentally validated on the created 500-watt WPT multi-coil system. After the receiver coil is placed in a designated area, the proper transmitter coil pattern can be automatically selected and energized. The output voltage can be regulated to a desired value under the typical operation conditions, including load change.

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This paper presents an inverter topology for a static wireless power transfer (SWPT) system that is intended to reduce the component counts and complexity of the conventional excitation circuit for multiple transmitter coils. The proposed inverter topology requires only (n+1) power switches, where ''n'' is the number of transmitter coils. The currents in the transmitter coils can be independently controlled. The output voltage is regulated through the transmitter-side control by adjusting the duty cycle of the inverter switches. A detection method of the receiver coil position is developed by comparing the transmitter currents to the predetermined transmitter coil patterns. The proposed detection method helps decide the proper transmitter selection, which improves the transfer efficiency throughout the operation. An experimental study is performed on the created 500-watt WPT multi-coil system. As the receiver coil is placed in the designated area, the proper transmitter coil pattern can be automatically selected and energized. The output voltage can be regulated to the desired values throughout the operation, regardless of the load condition.INDEX TERMS Inverter topology, multi-transmitter coil, transmitter-side control, output voltage regulation, receiver coil position detection, wireless power transfer.

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