Abstract: An underground mining vehicle has a solid state electronic motor controller for controlling the operation of a brushless D.C. motor. A switching network is connected between a high voltage bus and portions of a stator winding for delivering current to portions of the stator winding. A first transducer produces a first group of feedback signals representative of the position and speed of the rotor. A second transducer produces a second group of feedback signals representative of the current delivered to the motor. A speed control is provided which produces an input signal representative of the desired speed of the vehicle. An electronic circuit, responsive to the input signal, the first group of feedback signals, and the second group of feedback signals, produces control signals. The control signals are input to the switching network to control the application of current to the portions of the stator winding.