PWM Controller Green Mode Transition for Power Loss Reduction

The controller dynamically adjusts the switching frequency based on load conditions. During heavy load, it operates at a higher frequency to meet power demands, while during light load or no load conditions, it automatically reduces the switching frequency to minimize power consumption. This dynamic frequency adjustment resolves the contradiction by making the controller adapt its operation complexity and power usage to actual load requirements rather than maintaining a fixed simple operation mode.

The controller uses parameter changes to manage the transition between normal mode and green mode. Specifically, it monitors the pulse width of drive signals and compares it against a threshold value. When the pulse width falls below the threshold, indicating light load conditions, the controller automatically transitions to green mode with reduced switching frequency. This parameter-based transition mechanism simplifies the circuitry design compared to complex mode-switching circuits, while still achieving effective power consumption reduction.

The controller implements periodic action by accumulating pulse widths over multiple switching cycles in green mode. Instead of maintaining a constant ON time which would limit control flexibility, the controller sums up the pulse widths of multiple individual pulses and compares the accumulated value against a threshold. This periodic accumulation approach allows each individual pulse to be short (reducing switching losses), while the cumulative effect over multiple cycles maintains the necessary total energy transfer, thus preserving control flexibility while achieving efficiency improvements.