Development of Electric Impact Driver Integrated with Inductively Coupled Wireless Power Transfer

Abstract

This study focuses on the development of an electric impact driver integrated with inductively coupled wireless power transfer. As it is important for impact drivers to be light weight, a control method of wireless power transfer that does not require a DC converter is proposed for the inductively coupled wireless power transfer between the impact driver and battery pack. Specifically, the dead time of the inverter deployed on the primary side of the wireless power transfer is controlled based on the primary current via the algorithm for the proposed control method. In order to verify the effectiveness of the proposed control method, operating simulations of wireless power transfer are conducted using a circuit simulator. The results confirm that the proposed control method can effectively control the wireless power transfer in an electric impact driver. In particular, the proposed method prevents output over-voltage and primary over-current. Based on the numerical findings, a prototype electric impact driver integrated with wireless power transfer is assembled. The proposed control method is applied to the wireless power transfer controller. Furthermore, screw-tightening and idling tests are conducted using the prototype. The results show that the screw-tightening and idling operations can be successfully performed by the prototype without failure. This study contributes to the development of electric impact drivers integrated with wireless power transfer technology as well as to the realization of new waterproof electric impact drivers that can be operated at construction sites even during rainy weather.