Primary side control method for constant voltage/current output of series-none compensated inductive wireless transfer systems

In practical applications, inductive wireless power transfer (IWPT) systems are often required to output a constant voltage or current. However, a change of the load often leads to a change of the output. This paper presents a primary side control method for an IWPT system with the series-none (SN) compensation topology. By using this method, the load, output current, and voltage can be estimated in real time by detecting the output voltage and current of the primary inverter, along with the phase difference between them. This overcomes the disadvantage where the control for a IWPT system requires wireless or wired communication between the primary side and secondary side. Phase shift voltage regulation technology and a PI controller are used to regulate the output voltage or current based on the estimated data. In order to adjust the parameters of the PI controller, a small signal model is established by the generalized state-space averaging (GSSA) method. Finally, simulations and an experimental prototype were established to verify the performance of the primary side control method. The obtained results show that the secondary parameters and variables can be accurately estimated. Under the action of the primary controller, the system can output constant voltage and current values.