Design considerations on the low-voltage mosfet applications to wheelchair drive systems

The paper deals with the application of MOSFETs, as switching devices, in a low-voltage power converter, which is devoted to an electric-driven wheelchair. The characteristics of the MOSFETs have a major impact on the whole performances of the drive system. The used devices are out of the traditional cell-structure MOSFETs, and they present interesting characteristics due to the advanced design rules typical of the VLSI processes. These MOSFETs can carry current up to 150 A, with a breakdown voltage in the range 20 V-50 V. The paper starts with the description of some technological issues. In particular, the paper focuses on the innovations and the improved performances in comparison to those of standard devices. Laboratory tests are carried out aiming to characterize the device looking for the specific application in a full bridge inverter. Finally, considerations and design criteria, in order to reduce the total power losses in the actual AC motor drive for wheelchair applications, are presented.