Research and simulation of frequency jitter technique in restraining conducted EMI

Larger amplitude of the harmonic with a concentrated energy spectrum of the input current is the blind side of the traditional PWM-based converter. This paper analyzed the frequency jitter technique and used the sinusoidal, triangular and exponential signal to simulate. And the effects of frequency jitter technique with different slope coefficients triangular signals and different concavity coefficients exponential signals were analyzed. The simulation results show that using triangular signal with the slope coefficient of 0.5 can get a flatter spectrum which has the bigger reduced amplitude. Furthermore, in combination with the UC1524A, triangle signal was used as the modulation signal to reduce the electromagnetic interference produced by buck voltage regulator, which is controlled by the PWM. It shows frequency jitter technique can disperse the energy of the interference. The conducted electromagnetic interference is reduced effectively after using the frequency jitter technique.