The motor with permanent magnets used for field excitation, including the BLDC motor, currently finds numerous applications, particularly in electric vehicle propulsion. These motors are powered by an electrical system called an electronic commutator. It is justified to investigate the efficiency of converting electrical energy into mechanical energy depending on the method of supplying the motor windings. Speed regulation requires changing the average voltage supplied to the motor windings. The average voltage supplied to the motor can be changed in two ways: by pulse width modulation (PWM) implemented on the transistors of the electronic commutator or by using an additional DC/DC converter connected between the power source and the electronic commutator. The article presents a research setup examining the total energy losses in the studied BLDC motor depending on the method of power supply, load torque, and rotational speed.