Synchronous switch-mode active electromagnetic interference cancellation circuit and method

A method to filter EMI of a power converter or electric circuit, the power converter or electric circuit comprising a first set of switching elements and a first inductor or capacitor configured to perform a power conversion or switching task, the method comprising:

• applying an input source voltage to the first inductor or capacitor of the power converter or electric circuit, the first inductor or capacitor have a voltage rating equal to or greater than the applied input source voltage;
• controlling, via circuitry or instructions, switching operations of a second set of switching elements of a switch-mode active electromagnetic interference cancellation circuit to operatively apply an opposite alternating voltage or current at a second inductor that is coupled to the first inductor or capacitor of the first set of switching elements through a second capacitor to cancel high-frequency ripples flowing through (i) the first inductor or capacitor and (ii) associated with switching of the first set of switching elements, said second capacitor further coupled to an output of the switch-mode active electromagnetic interference cancellation circuit wherein the switch-mode active electromagnetic interference cancellation circuit has an output voltage less than the input source voltage, the second inductor having a voltage rating equal to or greater than the output voltage of the switch-mode active electromagnetic interference cancellation circuit and less than the voltage rating of the first capacitor or inductor, wherein the second capacitor isolates and protects the second inductor and the switch-mode active electromagnetic interference cancellation circuit from the input source voltage, and
• wherein the switching operations of the second set of switching elements are at a frequency range outside a defined-EMI or pre-defined range.

A method to filter EMI of a power converter or electric circuit, the power converter or electric circuit comprising a first set of switching elements and a first inductor or capacitor configured to perform a power conversion task, the method comprising:

• applying an input source voltage to the first inductor or capacitor of the power converter or electric circuit, the first inductor or capacitor have a voltage rating equal to or greater than the applied input source voltage;
• controlling, via circuitry or instructions, switching operations of the first set of switching elements to perform the power conversion task;
• controlling, via circuitry or instructions, switching operations of a second set of switching elements of a switch-mode active electromagnetic interference cancellation circuit to operatively apply an opposite alternating voltage or current at a second inductor that is coupled to an input of the first set of switching elements through a second capacitor to cancel high-frequency ripples flowing through a first inductor of the power converter, said second inductor further coupled to an output from the switch-mode active electromagnetic interference cancellation circuit, the second inductor having a voltage rating equal to or greater than the output voltage rating of the switch-mode active electromagnetic interference cancellation circuit and less than the voltage rating of the first capacitor or inductor, wherein the second capacitor isolates and protects the second inductor and the switch-mode active electromagnetic interference cancellation circuit from the input source voltage;
• and
• adjusting the controlling of the switching operations of the second set of switching elements based on the controlling of the switching operations of the first set of switching elements.