The present invention is an electric powered landing gear system for semi-truck trailers using an electric motor supplied by the available voltage in the trailer via a motor controller. The system automates raising and lowering the landing gear. The system comprises a shaft motorized system operated by a 3-phase motor, a DC-to-AC motor controller, and a set of sprockets-and-chain mechanism. The electric motor implements a 3-phase winding and a brushless structure that requires no maintenance compared to direct current motors. The trailer provides the power for the electric motor through the motor controller. The motor controller comprises a digital electronic processor that implements an algorithm to optimize a sensorless control approach providing a variable speed and torque for the motor, and hence to the landing gear system, therefore simplifying the landing gears to a single speed from dual (or multi) speed/gear ratio. The motor controller implements a protection feature that limits over-currents when the landing gear legs are engaged to the ground or retracted to their static position, or when a fault occurs.