Power conversion circuit and power converter using same

Abstract

This invention relates to a power conversion circuit, comprising: a first terminal; a second terminal; a first switching power conversion unit, comprising a first switch and a third switch; a second switching power conversion unit, comprising a second switch and a fourth switch, wherein the third switch is connected in series with the first switch, and the fourth switch is connected in series with the second switch; a flying capacitor; and a magnetic element comprising two first windings and a second winding, wherein the terminals of the two first windings are connected to each other with opposite terminals and connected to the second terminal, wherein one of the first windings is connected in series between the flying capacitor and the second terminal, and the other first winding is connected in series between the second switch and the second terminal, wherein the second winding is connected in series with the flying capacitor and the first winding, and the first terminal of the second winding is the same terminal as the first terminal of one of the first windings, and the turns ratio of the second winding and the two first windings is N:1:1.

Claims

1. A power conversion circuit, comprising: a first terminal including a first positive electrode and a first negative electrode; a second terminal including a second positive electrode and a second negative electrode, wherein the second negative electrode is electrically connected to the first negative electrode; a first switching power conversion unit including a first switch and a third switch connected in series; a second switching power conversion unit including a second switch and a fourth switch connected in series, wherein a first terminal of the first switch is electrically connected to a first terminal of the second switch, a second terminal of the first switch is electrically connected to the first positive electrode, the third switch is connected in series with the first switch, the fourth switch is connected in series with the second switch, a first terminal of the third switch and a first terminal of the fourth switch are electrically connected to the first negative electrode, a second terminal of the fourth switch is electrically connected to a second terminal of the second switch, the first switch, the second switch, the third switch and the fourth switch operate periodically according to a switching cycle, the switching cycle including a duty cycle; A flying capacitor; and a magnetic element comprising two first windings and a second winding, the two first windings and the second winding being electromagnetically coupled to each other, the second ends of the two first windings being opposite terminals and electrically connected to each other and electrically connected to the second positive terminal, one first terminal of one of the first windings being connected in series to a second terminal of a third switch, and one first terminal of the other first winding being electrically connected to the second terminal of a fourth switch and a second terminal of a second switch, the second winding and the flying capacitor being connected in series between the first terminal of the first switch and the first terminal of one of the first windings, the first terminal of the second winding and the first terminal of one of the first windings being same terminals, wherein the turns ratio of the second winding and the two first windings is N:1:1, where N is a positive number; The switching cycle includes two working intervals: a first working interval and a second working interval. In the first working interval, the current flowing through the second winding is equal to the current flowing through one of the first windings. In the second working interval, the current flowing through the second winding is equal to the current flowing through the other first winding.

2. The power conversion circuit as claimed in claim 1, wherein the power conversion circuit is a bidirectional power conversion circuit, the first terminal of the power conversion circuit is an input terminal or an output terminal, and the second terminal of the power conversion circuit is an output terminal or an input terminal.

3. The power conversion circuit as claimed in claim 1, wherein the first end of the second winding is electrically connected to the first end of one of the first windings, and a second end of the second winding is electrically connected to one end of the flying capacitor; or one end of the flying capacitor is electrically connected to the first end of one of the first windings, and the other end of the flying capacitor is electrically connected to the first end of the second winding.

4. The power conversion circuit as claimed in claim 1, wherein the switching state of the first switch is the same as the switching state of the fourth switch, the switching state of the second switch is the same as the switching state of the third switch, and the switching state of the first switch is 180 degrees out of phase with the switching state of the second switch, and the conduction time of the first switch and the second switch is less than or equal to half of the switching cycle and greater than or equal to 0.4 times the switching cycle.

5. The power conversion circuit as claimed in claim 1, wherein the power conversion circuit has an equivalent resonant inductor that resonates with the flying capacitor, and the resulting resonance has a resonant frequency and a resonant period, wherein the switching period of the power conversion circuit is less than or equal to the resonant period, and the switching period is greater than or equal to half of the resonant period.

6. The power conversion circuit as claimed in claim 5, wherein the equivalent resonant inductance is the leakage inductance of the magnetic element and the parasitic inductance of the line; or the equivalent resonant inductance is at least one external inductor connected in series between the first terminal of the first switch and the second positive terminal.

7. The power conversion circuit as claimed in claim 1, wherein the two first windings and the second winding are wound on the same magnetic post of the same magnetic core element, and the coupling coefficient between each pair of the two first windings and the second winding is greater than 0.

9.

8. The power conversion circuit as claimed in claim 1, wherein during the switching cycle, the flying capacitor synchronously stores energy and synchronously transfers the energy to the second terminal of the power conversion circuit as the corresponding switch is turned on and off, and the flying capacitor has a DC voltage, the ratio of the DC voltage to the voltage of the first terminal of the power conversion circuit being between 0.4 and 0.

6.

9. The power conversion circuit as claimed in claim 1, wherein the voltage gain ratio of the voltages at the first terminal and the second terminal of the power conversion circuit is (4-2N):

1.

10. A power conversion circuit, comprising: a first terminal including a first positive terminal and a first negative terminal; a second terminal including a second positive terminal and a second negative terminal, wherein the second negative terminal is electrically connected to the first negative terminal; a first flying capacitor; a second flying capacitor; a first switching power conversion unit including a first switch, a second switch and a third switch, wherein a first terminal of the first switch is electrically connected to the first positive terminal, a second terminal of the second switch is electrically connected to a first terminal of the third switch, and a second terminal of the third switch is electrically connected to the second negative terminal; a second switching power conversion unit including a fourth switch, a fifth switch and a sixth switch, wherein a first terminal of the fourth switch is electrically connected to the first positive terminal, a second terminal of the fifth switch is electrically connected to a first terminal of the sixth switch, and a second terminal of the sixth switch is electrically connected to the second negative terminal, and a second terminal of the fourth switch is electrically connected to a first terminal of the second switch, and a first terminal of the fifth switch is electrically connected to a second terminal of the first switch; The first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch operate periodically according to a switching cycle, which includes a duty cycle; and a magnetic element includes two first windings and two second windings, the two first windings and the two second windings being electromagnetically coupled to each other, the second ends of the two first windings being opposite ends and electrically connected to each other and electrically connected to a second positive terminal, one first end of one of the first windings being electrically connected to the second end of the fifth switch and the first end of the sixth switch, and one first end of the other first winding being electrically connected to the second end of the second switch and the sixth switch. In the first terminal of the three switches, one of the second windings and the second flying capacitor are connected in series between the second terminal of the fourth switch and the second terminal of the fifth switch. The other second winding and the first flying capacitor are connected in series between the second terminals of the first and second switches. One first terminal of one of the second windings is connected to the first terminal of one of the first windings, and the other first terminal is connected to the first terminal of the other first winding. The turns ratio of the two second windings and the two first windings is N:N:1:1, where N is a positive number. The switching cycle includes two working intervals: a first working interval and a second working interval. In the first working interval, the sum of the currents flowing through the two second windings is equal to the current flowing through one of the first windings. In the second working interval, the sum of the currents flowing through the two second windings is equal to the current flowing through the other first winding.

11. The power conversion circuit as claimed in claim 10, wherein the power conversion circuit is a bidirectional power conversion circuit, the first terminal of the power conversion circuit is an input terminal or an output terminal, and the second terminal of the power conversion circuit is an output terminal or an input terminal.

12. The power conversion circuit as claimed in claim 10, wherein a second end of one of the two second windings is electrically connected to the second flying capacitor, and a second end of the other second winding is electrically connected to the first flying capacitor.

13. The power conversion circuit of claim 10, wherein one end of the second flying capacitor is electrically connected to the first end of one of the first windings, the other end of the second flying capacitor is electrically connected to the first end of one of the second windings, and one end of the first flying capacitor is electrically connected to the first end of the other first winding, and the other end of the first flying capacitor is electrically connected to the first end of the other second winding.

14. The power conversion circuit as claimed in claim 10, wherein the switching state of the first switch, the switching state of the second switch and the switching state of the sixth switch are the same, the switching state of the fourth switch and the switching state of the fifth switch are the same as the switching state of the third switch, and the switching state of the first switch and the switching state of the fourth switch are out of phase by 180 degrees, and the conduction time of the first switch and the fourth switch is less than or equal to half of the switching period and greater than or equal to 0.4 times the switching period.

15. The power conversion circuit of claim 10, wherein the power conversion circuit has an equivalent resonant inductor that resonates with the first flying capacitor and the second flying capacitor, the resulting resonance having a resonant frequency and a resonant period, the switching period of the power conversion circuit being less than or equal to the resonant period, and the switching period of the power conversion circuit being greater than or equal to half of the resonant period.

16. The power conversion circuit of claim 15, wherein the equivalent resonant inductance is the leakage inductance of the magnetic element and the parasitic inductance of the line, or the equivalent resonant inductance is at least one external inductor connected in series between the first terminal of the first switch and the second positive terminal.

17. The power conversion circuit as claimed in claim 10, wherein the two first windings and the two second windings are wound on the same magnetic post of the same magnetic core element, and the coupling coefficient between each pair of the two first windings and the two second windings is greater than 0.

9.

18. The power conversion circuit of claim 10, wherein during the switching cycle, the first flying capacitor and the second flying capacitor synchronously store energy and synchronously transfer the energy to the second terminal of the power conversion circuit as the corresponding switch is turned on and off, and both the first flying capacitor and the second flying capacitor have a DC voltage, the ratio of each DC voltage to the voltage of the first terminal of the power conversion circuit being between 0.4 and 0.

6.

19. The power conversion circuit as claimed in claim 10, wherein the voltage gain ratio between the first terminal and the second terminal of the power conversion circuit is (4-2N):

1.

20. A power converter comprising: N power conversion circuits as described in any one of claims 1 to 9, wherein the first terminals of the N power conversion circuits are connected in parallel, and the second terminals of the N power conversion circuits are connected in parallel, wherein when N is greater than 1 and is odd, the N power conversion circuits are controlled by N sets of control signals, each set of control signals being used to control each power conversion circuit, the corresponding control signals in the N sets of control signals being sequentially out of phase by an arbitrary value between [360 / N-20, 360 / N+20] degrees, wherein when N is greater than 1 and is even, the N power conversion circuits are controlled by N / 2 sets of control signals, the nth set of control signals being used to control the nth and N / 2+nth power conversion circuits, the corresponding control signals in the N / 2 sets of control signals being sequentially out of phase by an arbitrary value between [360 / N-20, 360 / N+20] degrees.

21. A power converter comprising: N power conversion circuits as described in any one of claims 10 to 19, the first terminals of the N power conversion circuits being connected in parallel, the second terminals of the N power conversion circuits being connected in parallel, wherein N is greater than 1, the N power conversion circuits being controlled by N sets of control signals, each set of control signals being used to control each power conversion circuit, the corresponding control signals in the N sets of control signals being out of phase by an arbitrary value between [360 / 2N-20, 360 / 2N+20] degrees.

Images