Comparison of Class 2a Truck Electric Vehicle Drivetrain Losses for Single- and Two-Speed Gearbox Systems with IPM Traction Machines

Production electric vehicles currently only utilize traction machines paired with a single-speed gearbox. Higher drivetrain efficiency and lower system mass can potentially be achieved by utilizing a two-speed gearbox. Two single-speed gearbox systems are compared to a two-speed gearbox system for a Class 2a electric pickup truck. An interior permanent magnet traction machine is designed using finite element analysis for each case, and each machine is designed to utilize the same traction drive with a phase current limit of 450Arms and nominal bus voltage of 350Vdc. The efficiency map for each machine is presented, and the two-speed gearbox system is shown to be more efficient and achieve greater driving range than the single-speed systems for both constant-speed driving and for various standard drive cycles.