Intermittent boost converter controlled by switching period optimum utilization rate
A boost converter and switching cycle technology, applied in the direction of output power conversion device, AC power input conversion to DC power output, electrical components, etc., can solve the problem of increased conduction loss, switch tube turn-off loss, inductor current peak value and The effective value is large, and the current stress of power devices is aggravated, and the critical inductance value is increased, the peak value and effective value are reduced, and the current stress is reduced.
Inactive Publication Date: 2015-08-12
NANJING UNIV OF SCI & TECH
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Problems solved by technology
[0004] Among them, the current discontinuous mode step-up power factor correction converter has the advantages of zero current turn-on of the switch tube, no reverse recovery of the diode and constant switching frequency, etc., but because it works in the discontinuous mode, the energy transmission does not occupy the entire switching cycle, and its The peak value and effective value of the inductor current are large, as are the switch tubes and diodes. While aggravating the current stress of the power device, it also increases the conduction loss and the turn-off loss of the switch tube, which affects the improvement of efficiency.
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[0027] 1 Working principle of DCM Boost PFC converter
[0028] figure 1 is the main circuit. figure 2 The inductor current waveform when working in DCM is given. image 3 It is the inductor current and its average and peak waveforms within half a power frequency cycle.
[0029] The expression for the input AC voltage is:
[0030] v in =V m sin ωt (1)
[0031] In the power frequency cycle, when the duty ratio D y When it is fixed, assuming that the efficiency of the converter is 100% (the same below), within [0-π], the peak value of the inductor current i in a switching cycle Lb_pk , average value of inductor current i Lb_ave That is, the input current i in , duty cycle D y , Inductor current fall time D R and the power factor PF are respectively
[0032] i Lb _ pk = V m sin ωt ...
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The present invention discloses an intermittent boost converter controlled by a switching period optimum utilization rate. The intermittent boost converter controlled by the switching period optimum utilization rate comprises a main power circuit and a control circuit, the structure of the control circuit is that the input end of a first bleeder circuit is connected with an input voltage sampling point, and the output end is connected with the inverting input end of a subtraction circuit; the input end of a second bleeder circuit is connected with the output voltage anode of the main power circuit, and the output end is connected with the non inverting input end of the subtraction circuit and the second input end of a multiplier separately; the output end of the subtraction circuit is connected with the first input end vx of the multiplier, the inverting input end of an error adjusting circuit is connected with the anode of an output voltage, and the non inverting input end of the error adjusting circuit is connected with a voltage reference signal; the output end of the error adjusting circuit is connected with the third input end of the multiplier, and the output end of the multiplier is connected with the input end of a chip UC3525A. According to the present invention, a critical inductance value is increased, the conversion efficiency is improved, at the same time, the output voltage ripple or output energy storage capacitance is also reduced.
Description
technical field [0001] The invention relates to the technical field of AC-DC converters of electric energy conversion devices, in particular to a discontinuous boost converter adopting optimal utilization rate control of switching cycles. Background technique [0002] A power factor correction (Power Factor Correction, PFC) converter can reduce input current harmonics and improve input power factor, and has been widely used. PFC converters are divided into active and passive methods. Compared with passive methods, the active method has the advantages of high input power factor, small size, and low cost. [0003] Active PFC converters can adopt a variety of circuit extension and control methods, among which Boost PFC converter is one of several commonly used PFC converters. According to whether the inductor current is continuous or not, it can be divided into three operating modes, namely, inductive Current continuous mode (Continuous Current Mode, CCM), inductor current cri...
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IPC IPC(8): H02M7/217H02M1/14
CPCH02M7/2176
Inventor 姚凯李强周旭峰王祎李辉
Owner NANJING UNIV OF SCI & TECH