A Split-Tapped Interior Permanent Magnet Synchronous Machine Topology for Electric Vehicles Requiring 3-Speed Transmission

A tapped winding interior permanent magnet synchronous machine (IPMSM) is a convenient and effective way to obtain precise multistaged torque-speed (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i>-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ω</i>) characteristics in electric vehicles (EVs). In this article, the existing tapped winding topologies are analyzed in detail, resulting in a series of generalized plots that assess the performance of the motor at different tap positions. Based on this analysis, this article proposes a “split-tapped” (ST)-IPMSM as an EV propulsion system with 3-stage <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i>-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ω</i> characteristic that carries the benefits of the existing tapped topologies while offering a reduced dc bus voltage requirement. Moreover, this topology has the ability to change-over in the field weakening (FW) region, unlike the existing techniques, thus increasing the range of operation and overall efficiency. The topology also offers increased reliability due to the presence of two voltage source inverters (VSIs). The performance of the ST-IPMSM has been validated in simulation by considering a case of a light-duty vehicle intended to operate in urban traffic, and it is found that a 48% reduction of dc bus voltage is possible. Similar conclusions are deduced using an experimental validation on a scaled 2.26 kW ST-IPMSM prototype.