Switch-Mode EMI Cancellation Circuit for Compact Power Converters

The patent replaces the passive mechanical EMI filter system with an active electronic control system. The active EMI filter uses switching elements and controllers to generate canceling signals electronically, eliminating the need for large passive filter components and achieving significant volume reduction while maintaining EMI filtering effectiveness.

The patent changes the operating parameters of the EMI filter by using active switching elements that can dynamically adjust their characteristics. The switching elements operate at specific frequencies and duty cycles to generate canceling signals, allowing the filter to adapt its parameters based on the EMI conditions rather than relying on fixed passive components.

The patent implements periodic switching action through the switching elements that are controlled to operate only when needed. The controller activates the switching elements during power conversion operations and can deactivate them when not required, creating a periodic on-off pattern that reduces overall power consumption compared to continuously operating conventional active filters.

The active EMI filter system monitors its own operational requirements and automatically activates or deactivates based on the power converter's state. The controller detects when power conversion is occurring and enables the EMI filtering function only during those periods, allowing the system to self-regulate its power consumption rather than requiring continuous operation.