Three-Phase Inverter Switching Strategy for Partial-Load Loss Reduction

The patent implements periodic action by operating switching elements only during specific intervals rather than continuously. Switching operations are performed periodically only when needed to transition between different space vectors or to maintain the required rms current level, allowing switching elements to remain in static states (fully on or fully off) during intervals when current control requirements are already satisfied by the rotating magnetic field.

The patent extracts and eliminates redundant half-bridge switching operations from the conventional space vector modulation process. By identifying half-bridges whose switching would not contribute to generating the required space vectors or maintaining the rotating magnetic field, the patent removes these unnecessary switching operations, thereby reducing the total number of switching events and associated losses while preserving space vector accuracy for the essential switching operations.

The patent applies partial action by using only the minimum necessary switching operations to achieve the required current characteristics, especially in partial-load operating modes. Instead of continuously applying PWM switching to maintain perfect sinusoidal waveforms, the patent selectively applies switching only when necessary to maintain the required rms current and rotating magnetic field, accepting waveform deviations in exchange for dramatically reduced switching losses that are particularly beneficial during partial-load operation where conventional PWM incurs disproportionate losses.