Examination of influence of periodic switching frequency modulation in dc/dc converters on power quality on a load

Hybrid-modulation-based control technique for reduction of output voltage ripples in frequency-modulated switch-mode power converters

“…Note further in the analysis it will be assumed that ( ) is periodic and is modulation frequency. For quite large ∆ , and magnetic components peak currents can increase significantly in DCM in comparison to unmodulated case [16], [17]. Therefore it is important to propose a control technique to reduce peak-to-peak output voltage and peak currents increased due to straightforward application of SFM.…”

“…However the main problem with the use of this technique in conventional DC/DC or AC/DC SMPC is that peak-to-peak output voltage and power stage peak currents (e.g. power inductor or power MOSFET currents) can increase significantly [13] - [16]. Increase in peak-to-peak output voltage of SMPC can be very harmful to electronic equipment powered by the SMPC, but increase in peak currents of power magnetic components can lead to increase in losses and even to saturation of a magnetic core of transformers or inductors.…”

Reduction of Output Voltage Ripples in Frequency Modulated Power Converter

“…Despite the fact that FM has its benefits in reducing EMI, it can increase output voltage ripples significantly [7][8][9][10][11][12][13]. In addition to natural high-frequency (HF) output voltage ripples, FM causes also low-frequency (LF) output voltage ripples which are more problematic than HF ones [8,9].…”

“…In addition to natural high-frequency (HF) output voltage ripples, FM causes also low-frequency (LF) output voltage ripples which are more problematic than HF ones [8,9]. Detailed examination of the effect of FM on the output voltage ripples in SMPC operating in continuous and discontinuous conduction modes (CCM and DCM respectively) was performed mainly in [7,[9][10][11][12][13]. Although the main causes of the increase in the output voltage ripples in CCM are found out in [7,9,10] and expressions to calculate the peak-to-peak output voltage ripples V ofmp-p in closed-loop FM SMPC are derived in [9], closed-form expression for V ofmp-p , which can appreciably simplify analysis of the effect of SMPC and modulating signal parameters on V ofmp-p , is not derived.…”

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.…”