CN-115864815-B - Bridgeless Sepic PFC converter based on switch inductance capacitance

Abstract

The bridgeless Sepic PFC converter based on the switched inductance and the capacitance mainly comprises a switching tube S 1 ~S 3 , a diode D 1 ~D 4 , an inductance L 1 ~L 5 , and capacitances C 1 、C 2 and C o . The diode D 3 、D 4 , the capacitor C 2 and the inductor L 4 、L 5 form a switched inductor-capacitor structure. Compared with the traditional Sepic PFC converter, the converter disclosed by the invention has the advantages that the voltage gain is D/2 (1-D), the voltage-reducing gain is improved, and the voltage of the output end is stable under the condition of high voltage-reducing ratio. By adopting the bridgeless structure, lower on-state loss can be realized. The original output diode is replaced by a switch inductance capacitance structure, so that output current is continuous, and filtering of output is facilitated. And all the switching tubes are grounded, so that the control is convenient to realize. The converter has rich practical value.

Inventors

• MA HUI
• ZENG BIN
• YAO JUNWEI
• FAN LIPING
• XIE QIONGYAO
• HE QI
• CHENG JIANGZHOU
• HUANG YUEHUA

Assignees

• 三峡大学

Dates

Publication Date

20260508

Application Date

20221107

Claims (4)

1. 1. The bridge-free Sepic PFC converter with the switch inductance and the capacitor comprises an alternating current power supply u s , a switch tube S 1 ~S 3 , a diode D 1 ~D 4 , an inductor L 1 ~L 5 and a capacitor C 1 、C 2 、C o , and is characterized in that: One side of an alternating current power supply u s is respectively connected with the drain electrode of the switching tube S 3 and one end of an inductor L 1 , and the other end of the inductor L 1 is connected with the anode of a diode D 1 ; The other side of the alternating current power supply u s is respectively connected with the drain electrode of the switching tube S 2 and one end of the inductor L 2 , and the other end of the inductor L 2 is connected with the anode of the diode D 2 ; The anode of the capacitor C 1 is connected with the cathode of the diode D 1 , the cathode of the diode D 2 and the drain of the switching tube S 1 respectively; One end of the inductor L 3 is respectively connected with the cathode of the capacitor C 1 , the anode of the diode D 3 and one end of the inductor L 4 ; the other end of the inductor L 3 is respectively connected with the source electrode of the switching tube S 1 , the source electrode of the switching tube S 2 , the source electrode of the switching tube S 3 and the cathode of the output capacitor C o ; The other end of the inductor L 4 is respectively connected with the cathode of the capacitor C 2 and the anode of the diode D 4 ; The positive electrode of the capacitor C 2 is respectively connected with the cathode of the diode D 3 and one end of the inductor L 5 , and the other end of the inductor L 5 is respectively connected with the positive electrode of the diode D 4 and the positive electrode of the output capacitor C o ; The output capacitor C o is connected with the load R L in parallel; the converter comprises the following four working modes: The first working mode is that the circuit works in a positive half period of an alternating current power supply u s , a switching tube S 1 and a switching tube S 2 are switched on, a switching tube S 3 is switched off, a diode D 1 is positively biased on, and other diodes are reversely cut off, the alternating current power supply u s charges an inductor L 1 , a capacitor C 1 discharges to charge an inductor L 3 , the current of the inductor L 1 、L 3 linearly rises, the inductors L 4 and L 5 discharge to an output capacitor C o and a load through a capacitor C 2 , and the current of the inductors L 4 and L 5 linearly drops; The second working mode is that the circuit works in the positive half period of the alternating current power supply u s , the switching tube S 2 is switched on, the switching tube S 1 、S 3 is switched off, the diode D 1 、D 3 、D 4 is positively biased on, and the other diodes are reversely switched off, the process capacitor C 1 、C 2 is charged, and the inductor L 1 、L 3 discharges to the inductor L 4 、L 5 , the load and the output capacitor C o ; The third working mode is that the circuit works in a negative half period of an alternating current power supply u s , a switching tube S 1 and a switching tube S 3 are switched on, a switching tube S 2 is switched off, a diode D 2 is positively biased on, and other diodes are reversely cut off, the alternating current power supply u s charges an inductor L 2 , a capacitor C 1 discharges to charge an inductor L 3 , the current of the inductor L 2 、L 3 linearly rises, the inductors L 4 and L 5 discharge to an output capacitor C o and a load through a capacitor C 2 , and the currents of the inductors L 4 and L 5 linearly fall; The circuit works in a negative half period of an alternating current power supply u s , a switching tube S 3 is switched on, a switching tube S 1 、S 2 is switched off, a diode D 2 、D 3 、D 4 is positively biased on, other diodes are reversely switched off, a process capacitor C 1 、C 2 is charged, and an inductor L 2 、L 3 discharges to an inductor L 4 、L 5 , a load and an output capacitor C o .
2. 2. The bridge-less Sepic PFC converter according to claim 1, wherein said capacitor C 2 , inductor L 4 、L 5 , and diode D 3 、D 4 form a switched-inductor capacitor unit.
3. 3. The bridge-less Sepic PFC converter according to claim 1, wherein said converter has a common ground for switching transistors S 1 、S 2 、S 3 and power switching transistor S 1 、S 2 、S 3 is an insulated gate bipolar transistor IGBT, an integrated gate commutated thyristor IGCT, or a power field effect transistor MOSFET.
4. 4. The bridge-less, switched-inductor, capacitor-Sepic PFC converter of claim 1, wherein the converter voltage gain is D/2 (1-D).

Description

Bridgeless Sepic PFC converter based on switch inductance capacitance Technical Field The invention relates to the technical field of power electronic converters, in particular to a bridgeless Sepic PFC converter based on a switched inductor and a capacitor. Background With the rapid expansion of consumer electronics and electric vehicle markets, the demand for various power adapters has also grown dramatically. Because the power adapter generally needs to meet the input of the full voltage range (AC 85-265V), the low direct current voltage is output, and the wider input voltage range makes the optimal design of the converter difficult. For simple design, a two-stage circuit consisting of a front-stage PFC and a rear-stage DC-DC is generally adopted. But such a two-stage circuit is not efficient. The traditional Sepic PFC converter can easily realize the buck-boost function, and is suitable for a wide input voltage range. Is one of the topologies widely employed in power adapters. Compared with the two-stage structure adopted by the topology, the Sepic PFC converter greatly reduces the number of components, has inductance at the input end and continuous input current, improves the efficiency and the power factor of the converter, reduces the total harmonic distortion degree and reduces the conduction loss. However, when the high voltage reduction ratio is realized, the on ratio of the switching device is very low, the efficiency is reduced due to serious reverse recovery problem of the switching tube, and the inherent turn-on and turn-off time delay characteristic of the switching device limits the improvement of the working frequency of the converter. Therefore, it is necessary to design a circuit capable of solving the above-described problems. Disclosure of Invention The method aims to solve the problems that the efficiency is low, the output current is discontinuous and the duty ratio range is not large in the buck mode due to the fact that the existing Sepic PFC. The invention provides a bridge-free Sepic PFC converter based on a switch inductance capacitor, which replaces an output diode in an original Sepic PFC converter with a switch inductance capacitor unit comprising 5 elements. Compared with the traditional Sepic PFC converter, the converter improves the step-down gain, and the voltage of the output end is stable under the condition of high step-down ratio. The technical scheme adopted by the invention is as follows: The bridgeless Sepic PFC converter based on switched inductance and capacitance comprises an alternating current power supply u s, a switching tube S 1～S3, a diode D 1～D4, an inductance L 1～L5, a capacitance C 1、C2、Co, One side of an alternating current power supply u s is respectively connected with the drain electrode of the switching tube S 3 and one end of an inductor L 1, and the other end of the inductor L 1 is connected with the anode of a diode D 1; The other side of the alternating current power supply u s is respectively connected with the drain electrode of the switching tube S 2 and one end of the inductor L 2, and the other end of the inductor L 2 is connected with the anode of the diode D 2; The anode of the capacitor C 1 is connected with the cathode of the diode D 1, the cathode of the diode D 2 and the drain of the switching tube S 1 respectively; One end of the inductor L 3 is respectively connected with the cathode of the capacitor C 1, the anode of the diode D 3 and one end of the inductor L 4; the other end of the inductor L 3 is respectively connected with the source electrode of the switching tube S 1, the source electrode of the switching tube S 2, the source electrode of the switching tube S 3 and the cathode of the output capacitor C o; The other end of the inductor L 4 is respectively connected with the cathode of the capacitor C 2 and the anode of the diode D 4; The positive electrode of the capacitor C 2 is respectively connected with the cathode of the diode D 3 and one end of the inductor L 5, and the other end of the inductor L 5 is respectively connected with the positive electrode of the diode D 4 and the positive electrode of the output capacitor C o; The output capacitor C o is connected in parallel with the load R L. In the converter, the capacitor C 2, the inductor L 4、L5 and the diode D 3、D4 form a switched inductor capacitor unit. In the converter, the switching transistor S 1、S2、S3 is grounded, and the power switching transistor S 1、S2、S3 is an insulated gate bipolar transistor IGBT, an integrated gate commutated thyristor IGCT, or a power field effect transistor MOSFET. The converter voltage gain is D/2 (1-D). The converter has the following four working modes in CCM mode: In the first working mode, the circuit works in the positive half cycle of the alternating current power supply u s, the switching tubes S 1 and S 2 are turned on, and the switching tube S 3 is turned off. Diode D 1 is forward biased on and the remaining diodes are reverse