A thorough investigation of a high-gain DC-DC PWM converter employing a modified proportional integral (MPI) controller in combination with a brushless DC motor system (BLDC) is presented in this research. By guaranteeing a steady and overshoot-free 600 V output from a 48 V battery pack, the suggested high-gain DC-DC converter overcomes the difficulties caused by battery voltage fluctuations brought on by a variety of circumstances, including changes in speed of the BLDC motor. An improved version of the conventional PI controller, the MPI controller is primarily used to decrease overshoot without requiring a lot of tuning, thus increasing system stability. A mathematical model of the suggested converter is included in the paper and is verified by simulation results. The results demonstrate that the suggested DC-DC converter and MPI controller successfully maintain a steady output voltage for BLDC motor operation even when the battery voltage drops from 48 V to 42 V and the BLDC motor speed fluctuates between 500 and 1000 RPM, guaranteeing dependable motor operation with reduced oscillations. Additionally, this suggested technology can be applied to fuel cell electric vehicle (FCEV) and electric vehicle (EV) applications.