Low PWM inverter losses and low current distortion-two conflicting claims settled by Bellman´s dynamic programming

PWM techniques as applied to voltage source inverter-fed induction machines are well established. Even so it can be shown that strictly cutting down the pulse inverters turn-on and turn-off counts during a sampling period does not always lead to minimal switching losses as formerly alleged. Taking care of every single switching and conduction loss whilst maintaining a desired RMS current deviation ends up in a nonlinear extreme value problem. To be more specific: minimizing the expenditure of inverter losses to achieve a desired RMS current deviation is the main objective of the author. Therefore a CAD program utilizing Bellman´s dynamic programming was developed which solves this problem as returns the optimal current trajectory. A novel model follower is employed to track the system along any given pre-calculated trajectory