US Patent 11258357 EMI reduction in PWM inverters using adaptive frequency modulated carriers

A controller is provided for generating carrier signals for a PWM generator controlling an inverter driving an electric actuator to reduce the EMI level of the inverter. The controller includes an interface configured to connect to the inverter, a memory configured to store a measured electromagnetic-interference (EMI) spectrum, a desired EMI spectrum and an EMI suppression rate program, and a processor. The processor is, in connection with the memory, configured to computing EMI suppression rates for a frequency range, wherein the EMI suppression determined adaptively by the measured EMI spectrum and the desired EMI spectrum, computing sweep duration of discrete frequency, wherein the sweep duration is determined by the EMI suppression rate of the discrete frequency, and a modulator configured to modulate the carrier signals based on the sweep durations of carrier frequencies and to transmit the modulated carrier signals to the PWM generator to generate PWM signals for the inverter.