An improved control technique of switching frequency modulated power factor correctors for low THD and high power factor

Effects of Switching Frequency Modulation on Input Power Quality of Boost Power Factor Correction Converter

“…However the inductor is assumed to be linear. In order to take into account real power MOSFET and its control circuit (including PWM) turn-on switching delays (t don ) and turn-of switching delays (t doff ) (which in fact can have major influence on low-frequency content of switching-frequency modulated dc/dc power converetrs voltages [16], [19], [32]- [33]), turn-on and turn-off delay blocks consisting of two "Transport Delay" blocks, logic operators AND and OR are added to the model ( Figure 3). Using that blocks we can independently enter t don and t doff values.…”

“…[10] - [15]. In fact, the spread-spectrum technique has become very popular technique for SMPS EMI reduction in the scientific community owing to its good EMI reduction potential along with easiness of implementation and adding little or no additional cost to SMPS [12], [14], [16] - [19]. Spreading the spectrum of SMPS voltages and currents and EMI noise reduction ( Figure 1) can be achieved by modulating one of the pulse-width-modulated (PWM) control signal parameters such as the pulse position [20], duty ratio [21], or frequency [22].…”

“…Similarly to other EMI reduction techniques, SFM also has some disadvantages: it can increase output voltage and input current ripples of SMPS, as well as worsen the PQ of PFC converters and resonant inverters for induction heating appliances [16], [19], [22]- [28]. Figure 1.…”

“…PFC converters are designed to operate in DCM for low-power applications, but in CCM for mid-or high-power applications. A comrehensive study of the effect of SFM on the PQ of flyback PFC converters operating in DCM was presented in [16]. An improved control method to reduce the THD of input current and improve PF of DCM PFC converters with SFM was proposed in [16].…”

“…A comrehensive study of the effect of SFM on the PQ of flyback PFC converters operating in DCM was presented in [16]. An improved control method to reduce the THD of input current and improve PF of DCM PFC converters with SFM was proposed in [16]. Despite the fact, that the effect of SFM on PQ of PFC converters operating in DCM is examined very well, there are only few [22], [23] considering the effect of SFM on the PQ of PFC converters operating in CCM.…”