CN116780909A

CN116780909A - Voltage conversion circuit and electronic equipment

Info

Publication number: CN116780909A
Application number: CN202311036885.6A
Authority: CN
Inventors: 刘锐; 杨松楠; 陶海
Original assignee: Xidi Microelectronics Group Co ltd
Current assignee: Xidi Microelectronics Group Co ltd
Priority date: 2023-08-17
Filing date: 2023-08-17
Publication date: 2023-09-19
Anticipated expiration: 2043-08-17
Also published as: CN116780909B

Abstract

The application discloses a voltage conversion circuit and electronic equipment, and relates to the technical field of electronic circuits. The voltage conversion circuit comprises a first conversion branch, a second conversion branch and a controller. The first conversion branch is connected with the input power supply and the second conversion branch respectively, and the controller is connected with each switch tube in the first conversion branch and the second conversion branch respectively. The controller is used for controlling the on and off of each switching tube in the first conversion branch circuit so as to generate at least two paths of pulse signals with voltage amplitude which is half of the voltage of the input power supply, and at least two current sources are respectively generated based on the at least two paths of pulse signals to supply current for the second conversion branch circuit. The controller is also used for controlling each switching tube in the second conversion branch to be periodically turned on and turned off so as to generate an output voltage based on the current provided by the at least two current sources. By the mode, the voltage conversion efficiency can be improved.

Description

Voltage conversion circuit and electronic equipment

Technical Field

The present application relates to the field of electronic circuits, and in particular, to a voltage conversion circuit and an electronic device.

Background

Data centers typically employ a 12V bus system. The 12V bus voltage can be obtained in two ways, the first is to generate a 12V dc power from an ac power source and the second is to convert from a 48V bus voltage to a 12V bus voltage. The 12V is then converted to a low voltage, e.g., 0.8V, 1.0V, 1.2V, 1.5V, 1.8V, etc., to power a different system load.

Currently, full bridge LLC type DCDC converters are commonly employed to effect conversion from 48V bus to 12V bus. However, the voltage conversion efficiency of such a full-bridge LLC type DCDC converter is low.

Disclosure of Invention

The application aims to provide a voltage conversion circuit and electronic equipment, which can improve voltage conversion efficiency.

To achieve the above object, in a first aspect, the present application provides a voltage conversion circuit comprising:

the first conversion branch circuit, the second conversion branch circuit and the controller;

the first conversion branch is respectively connected with an input power supply and the second conversion branch, and the controller is respectively connected with each switch tube in the first conversion branch and each switch tube in the second conversion branch;

the controller is used for controlling the on and off of each switching tube in the first conversion branch circuit so as to generate at least two paths of pulse signals with voltage amplitude which is half of the voltage of the input power supply, and generating at least two current sources respectively to supply current for the second conversion branch circuit based on the at least two paths of pulse signals;

the controller is further configured to control each switching tube in the second switching leg to be periodically turned on and off to generate an output voltage based on the currents provided by the at least two current sources.

In an alternative manner, the second conversion branch is a switched capacitor conversion circuit, and the second conversion branch includes at least one current input terminal, one voltage output terminal, one output capacitor, at least three switching tubes, and at least one energy storage capacitor;

controlling the conduction of a part of switching tubes in the second conversion branch circuit in a part of the switching period of the second conversion branch circuit so as to charge the energy storage capacitor through the current input end by the current source;

and in the other part of the switching period of the second conversion branch, controlling the conduction of the other part of the switching tubes in the second conversion branch so as to discharge the energy storage capacitor to the output capacitor through the voltage output end.

In an optional manner, the first conversion branch includes a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a first capacitor, a second capacitor, a first inductor and a second inductor;

the third end of the first switch tube is respectively connected with the first end of the first capacitor and the input power supply, the second end of the first switch tube is respectively connected with the third end of the second switch tube and the first end of the second capacitor, the second end of the second switch tube is respectively connected with the third end of the third switch tube and the first end of the first inductor, the second end of the first inductor is connected with the second switching branch circuit, the second end of the first inductor is the output end of a first current source in the at least two current sources, the second end of the second capacitor is respectively connected with the first end of the second inductor and the third end of the fourth switch tube, the second end of the second inductor is the output end of a second current source in the at least two current sources, and the second end of the first inductor, the second end of the third switch tube and the fourth switching tube are all grounded;

The controller is respectively connected with the first end of the first switching tube, the first end of the second switching tube, the first end of the third switching tube and the first end of the fourth switching tube.

In an optional manner, the second conversion branch includes a fifth switching tube, a sixth switching tube, a seventh switching tube, a third capacitor and a fourth capacitor;

the third end of the fifth switching tube is respectively connected with the first end of the third capacitor, the second end of the first inductor and the second end of the second inductor, the second end of the fifth switching tube is respectively connected with the third end of the sixth switching tube and the first end of the fourth capacitor, the second end of the sixth switching tube is respectively connected with the second end of the third capacitor and the third end of the seventh switching tube, and the second end of the fourth capacitor and the second end of the seventh switching tube are grounded;

the controller is respectively connected with the first end of the fifth switching tube, the first end of the sixth switching tube and the first end of the seventh switching tube;

the first end of the third capacitor is a current input end, the first end of the fourth capacitor is a voltage output end, the fourth capacitor is an output capacitor, and the third capacitor is an energy storage capacitor.

In an optional manner, the second switching branch includes an eighth switching tube, a ninth switching tube, a tenth switching tube, an eleventh switching tube, a twelfth switching tube, a thirteenth switching tube, a fifth capacitor, a sixth capacitor, and a seventh capacitor;

the third end of the eighth switching tube is respectively connected with the first end of the fifth capacitor and the second end of the first inductor, the second end of the eighth switching tube is respectively connected with the third end of the ninth switching tube and the first end of the sixth capacitor, the second end of the ninth switching tube is respectively connected with the second end of the fifth capacitor and the third end of the tenth switching tube, and the second end of the sixth capacitor and the second end of the tenth switching tube are both grounded;

the third end of the eleventh switching tube is respectively connected with the first end of the seventh capacitor and the second end of the second inductor, the second end of the eleventh switching tube is respectively connected with the third end of the twelfth switching tube and the first end of the sixth capacitor, the second end of the twelfth switching tube is respectively connected with the second end of the seventh capacitor and the third end of the thirteenth switching tube, and the second end of the thirteenth switching tube is grounded;

The controller is respectively connected with the first end of the eighth switching tube, the first end of the ninth switching tube, the first end of the tenth switching tube, the first end of the eleventh switching tube, the first end of the twelfth switching tube and the first end of the thirteenth switching tube;

the first end of the fifth capacitor and the first end of the seventh capacitor are both current input ends, the first end of the sixth capacitor is a voltage output end, the sixth capacitor is an output capacitor, and the fifth capacitor and the seventh capacitor are energy storage capacitors.

In an alternative, the controller is further configured to:

in a first time period in one working cycle, controlling the first switching tube, the third switching tube, the eighth switching tube, the tenth switching tube and the twelfth switching tube to be on and controlling other switching tubes to be off;

in a second time period in one working cycle, controlling the third switching tube, the fourth switching tube, the eighth switching tube, the tenth switching tube and the twelfth switching tube to be on and controlling other switching tubes to be off;

in a third time period in one working cycle, controlling the second switching tube, the fourth switching tube, the ninth switching tube, the eleventh switching tube and the thirteenth switching tube to be on, and controlling other switching tubes to be off;

And in a fourth time period in one working cycle, controlling the third switching tube, the fourth switching tube, the ninth switching tube, the eleventh switching tube and the thirteenth switching tube to be turned on and controlling other switching tubes to be turned off.

In an alternative, the controller is further configured to:

in a second time period in one working cycle, controlling the first switching tube, the third switching tube, the ninth switching tube, the eleventh switching tube and the thirteenth switching tube to be on, and controlling other switching tubes to be off;

in a third time period in one working cycle, controlling the third switching tube, the fourth switching tube, the ninth switching tube, the eleventh switching tube and the thirteenth switching tube to be on, and controlling other switching tubes to be off;

in a fourth time period in one working cycle, controlling the second switching tube, the fourth switching tube, the eighth switching tube, the tenth switching tube and the twelfth switching tube to be on and controlling other switching tubes to be off;

In a fifth time period in one working cycle, controlling the second switching tube, the fourth switching tube, the ninth switching tube, the eleventh switching tube and the thirteenth switching tube to be on, and controlling other switching tubes to be off;

and in a sixth time period in one working cycle, controlling the third switching tube, the fourth switching tube, the ninth switching tube, the eleventh switching tube and the thirteenth switching tube to be turned on and controlling other switching tubes to be turned off.

In an alternative, the controller is further configured to:

controlling the combination of the eighth switching tube and the tenth switching tube and the ninth switching tube to be alternately turned on and turned off in a complementary manner;

controlling the combination of the eleventh switching tube and the thirteenth switching tube to be alternately switched on and off with the twelfth switching tube in a complementary mode;

the eighth switching tube and the eleventh switching tube are turned on and off by 180 degrees with the same duty ratio of the second switching branch circuit and the same phase-shifting phase.

In an optional manner, the voltage conversion circuit further comprises M longitudinal extension branches which are sequentially cascaded, wherein each longitudinal extension branch comprises a first extension switch tube, a second extension switch tube, a first extension capacitor and a second extension capacitor, and M is an integer more than or equal to 1;

The second end of a first expansion switching tube in a first longitudinal expansion branch of the M longitudinal expansion branches is connected with the first end of the fifth capacitor, and the second end of a second expansion switching tube in the first longitudinal expansion branch is connected with the first end of the seventh capacitor;

a first end of a first expansion capacitor in the first longitudinal expansion branch is connected with a third end of a first expansion switching tube in the first longitudinal expansion branch, and a first end of a second expansion capacitor in the first longitudinal expansion branch is connected with a third end of a second expansion switching tube in the first longitudinal expansion branch;

a third end of a first expansion switching tube in an Mth longitudinal expansion branch of the M longitudinal expansion branches is connected with a second end of the first inductor, and a third end of a second expansion switching tube in the Mth longitudinal expansion branch is connected with a second end of the second inductor;

the second end of the first expansion capacitor in the odd-numbered longitudinal expansion branch of the M longitudinal expansion branches is connected with the second end of the seventh capacitor, and the second end of the second expansion capacitor in the odd-numbered longitudinal expansion branch of the M longitudinal expansion branches is connected with the second end of the fifth capacitor;

The second end of the first expansion capacitor in the even number of the M longitudinal expansion branches is connected with the second end of the fifth capacitor, and the second end of the second expansion capacitor in the even number of the M longitudinal expansion branches is connected with the second end of the seventh capacitor;

when K is more than 1 and less than or equal to M, the second end of a first expansion switching tube in a Kth longitudinal expansion branch of the M longitudinal expansion branches is connected with the third end of a first expansion switching tube in a (K-1) th longitudinal expansion branch of the M longitudinal expansion branches, and the second end of a second expansion switching tube in the Kth longitudinal expansion branch is connected with the third end of a second expansion switching tube in the (K-1) th longitudinal expansion branch;

the controller is connected with the first ends of the expansion switching tubes in the M longitudinal expansion branches.

In an alternative, the controller is further configured to: the switching tubes in the second switching branch and the longitudinal expansion branch are controlled to be alternately switched on and switched off at a duty ratio of 50%, so that the switching tubes in the second switching branch and the longitudinal expansion branch work in two working states;

Wherein, in a first one of the two operating states, the controller is configured to: controlling a second expansion switching tube in an odd number of the M longitudinal expansion branches, a first expansion switching tube in an even number of the M longitudinal expansion branches, an eighth switching tube, a tenth switching tube and a twelfth switching tube to be conducted, and controlling other switching tubes to be turned off;

in a second of the two operating states, the controller is configured to: and controlling a first expansion switching tube in an odd number of the M longitudinal expansion branches, a second expansion switching tube in an even number of the M longitudinal expansion branches, the ninth switching tube, the eleventh switching tube and the thirteenth switching tube to be switched on, and controlling other switching tubes to be switched off.

In an alternative manner, the first conversion branch further includes a fourteenth switching tube, a fifteenth switching tube, and an eighth capacitor;

the third end of the fourteenth switching tube is connected with the first end of the first capacitor, the second end of the fourteenth switching tube is respectively connected with the third end of the fifteenth switching tube and the first end of the eighth capacitor, the second end of the eighth capacitor is connected with the first end of the first inductor, and the second end of the fifteenth switching tube is connected with the first end of the second inductor;

The controller is respectively connected with the first end of the fourteenth switching tube and the first end of the fifteenth switching tube.

In an alternative, the controller is further configured to:

controlling the combination of the first switching tube, the fifteenth switching tube and the combination of the second switching tube and the fourteenth switching tube to be alternately turned on and turned off by 180 degrees with the same duty ratio in a phase-staggered manner;

controlling the third switching tube to be turned on and off in a complementary mode with the second switching tube;

and controlling the fourth switching tube to be turned on and turned off in a complementary manner with the fifteenth switching tube.

In an alternative, the controller is further configured to:

controlling the first switching tube, the fifteenth switching tube, the second switching tube and the fourteenth switching tube to be alternately turned on and turned off at the same duty ratio by 90 degrees;

controlling the third switching tube to be turned off when the second switching tube or the fourteenth switching tube is turned on, and to be turned on when both the second switching tube and the fourteenth switching tube are turned off;

and controlling the fourth switching tube to be turned off when the first switching tube or the fifteenth switching tube is turned on, and turning on when both the first switching tube and the fifteenth switching tube are turned off.

In an alternative manner, the first conversion branch further includes a sixteenth switching tube, a seventeenth switching tube, and a ninth capacitor;

the third end of the sixteenth switching tube is connected with the first end of the first capacitor, the second end of the sixteenth switching tube is respectively connected with the third end of the seventeenth switching tube and the first end of the ninth capacitor, the second end of the seventeenth switching tube is connected with the first end of the second inductor, and the controller is respectively connected with the first end of the sixteenth switching tube and the first end of the seventeenth switching tube;

the voltage conversion circuit further comprises A transverse expansion branches which are sequentially cascaded, wherein each transverse expansion branch comprises a third expansion switching tube, a fourth expansion switching tube, a fifth expansion switching tube, a sixth expansion switching tube, a seventh expansion switching tube, an eighth expansion switching tube, a third expansion capacitor, a fourth expansion capacitor and a first expansion inductor, and A is an integer which is more than or equal to 1;

the third end of a third expansion switching tube in the transverse expansion branch is connected with the first end of the first capacitor, the second end of the third expansion switching tube in the transverse expansion branch is respectively connected with the third end of a fourth expansion switching tube in the transverse expansion branch and the first end of the third expansion capacitor in the transverse expansion branch, the second end of the fourth expansion switching tube in the transverse expansion branch is respectively connected with the first end of a first expansion inductor in the transverse expansion branch and the third end of a fifth expansion switching tube in the transverse expansion branch, the second end of the first expansion inductor in the transverse expansion branch is respectively connected with the first end of the fourth expansion capacitor in the transverse expansion branch and the third end of a sixth expansion switching tube in the transverse expansion branch, the second end of the sixth expansion switching tube in the transverse expansion branch is respectively connected with the third end of a seventh expansion switching tube in the transverse expansion branch and the first end of the sixth capacitor, and the third end of the fourth expansion switching tube in the transverse expansion branch is respectively connected with the third end of a fourth expansion switching tube in the transverse expansion branch and the fourth end of the transverse expansion tube in the transverse expansion branch;

When a=1, the second end of the third expansion capacitor in the lateral expansion branch is connected with the first end of the first inductor, and the second end of the ninth capacitor is connected with the first end of the first expansion inductor in the lateral expansion branch;

when B is less than or equal to 1 and less than A, the second end of the third expansion capacitor in the B-th lateral expansion branch of the A-th lateral expansion branch is connected with the first end of the first expansion inductor in the (B+1) -th lateral expansion branch of the A-th lateral expansion branch, the second end of the third expansion capacitor in the A-th lateral expansion branch of the A-th lateral expansion branch is connected with the first end of the first inductor, and the second end of the ninth capacitor is connected with the first end of the first expansion inductor in the first lateral expansion branch of the A-th lateral expansion branch.

In an alternative, the controller is further configured to:

when a=1, controlling a combination of the first switching tube and the seventeenth switching tube, a combination of the sixteenth switching tube and the fourth expansion switching tube in the lateral expansion branch, and a combination of the third expansion switching tube and the first switching tube in the lateral expansion branch to be alternately turned on and off with the same duty cycle by 120 degrees;

Controlling the third switching tube to be turned on and off in a manner complementary to the second switching tube, controlling the fourth switching tube to be turned on and off in a manner complementary to the seventeenth switching tube, and controlling the fifth expansion switching tube in the transverse expansion branch to be turned on and off in a manner complementary to the fourth expansion switching tube in the transverse expansion branch;

when B is less than or equal to 1 and less than A, controlling the combination of the first switching tube and the seventeenth switching tube, the combination of the sixteenth switching tube and the fourth switching tube of the first transverse expansion branch of the A transverse expansion branches, the combination of the third switching tube of the B transverse expansion branch of the A transverse expansion branches and the fourth switching tube of the (B+1) th transverse expansion branch of the A transverse expansion branches and the combination of the third switching tube of the A transverse expansion branch of the A transverse expansion branches and the second switching tube to be alternately turned on and off at 360/(2+A) degrees in a staggered phase with the same duty ratio;

and controlling the third switching tube to be turned on and off in a manner complementary to the second switching tube, controlling the fourth switching tube to be turned on and off in a manner complementary to the seventeenth switching tube, and controlling the fifth expansion switching tube in each of the A transverse expansion branches to be turned on and off in a manner complementary to the fourth expansion switching tube in the same transverse expansion branch.

In an alternative, the controller is further configured to:

when a=1, controlling the first switching tube, the seventeenth switching tube, the sixteenth switching tube, the fourth expansion switching tube in the transverse expansion branch, the third expansion switching tube in the transverse expansion branch and the first switching tube to be alternately turned on and turned off at the same duty ratio by 60 degrees;

the third switching tube is controlled to be turned off when the second switching tube or the third expansion switching tube in the transverse expansion branch is turned on, and is controlled to be turned on when the second switching tube and the third expansion switching tube in the transverse expansion branch are turned off;

controlling the fourth switching tube to be turned off when the seventeenth switching tube or the first switching tube is turned on, and to be turned on when the seventeenth switching tube and the first switching tube are turned off;

controlling a fifth expansion switching tube in the transverse expansion branch to be turned off when the sixteenth switching tube or a fourth expansion switching tube in the transverse expansion branch is turned on, and turning on when the sixteenth switching tube and the fourth expansion switching tube in the transverse expansion branch are turned off;

when B is more than or equal to 1 and less than A, the first switching tube, the seventeenth switching tube, the sixteenth switching tube, the third expansion switching tube of each of the A transverse expansion branches, the fourth expansion switching tube of each of the A transverse expansion branches and the second switching tube are controlled to be alternately turned on and off at the same duty ratio by 180/(2+A);

The third switching tube is controlled to be turned off when the second switching tube or the third expansion switching tube in the A-th transverse expansion branch of the A-th transverse expansion branch is turned on, and is controlled to be turned on when the second switching tube and the third expansion switching tube in the A-th transverse expansion branch of the A-th transverse expansion branch are turned off;

controlling a fifth expansion switching tube in a first one of the a lateral expansion branches to be turned off when the sixteenth switching tube or a fourth expansion switching tube in the first one of the a lateral expansion branches is turned on, and turning on when the sixteenth switching tube and the fourth expansion switching tube in the first one of the a lateral expansion branches are turned off;

and controlling a fifth expansion switching tube in the (B+1) th transverse expansion branch of the A transverse expansion branches to be turned off when a third expansion switching tube in the B (B+1) th transverse expansion branch of the A transverse expansion branches or a fourth expansion switching tube in the (B+1) th transverse expansion branch of the A transverse expansion branches is turned on, and turning on when the third expansion switching tube in the B (B) th transverse expansion branch of the A transverse expansion branches and the fourth expansion switching tube in the (B+1) th transverse expansion branch of the A transverse expansion branches are turned off.

In an alternative, the controller is further configured to:

controlling the combination of a sixth expansion switching tube and an eighth expansion switching tube in each of the A transverse expansion branches and a seventh expansion switching tube in the unified transverse expansion branch to be alternately switched on and switched off in a complementary mode;

the eighth switching tube, the eleventh switching tube and the sixth expansion switch in each of the A transverse expansion branches are turned on and off at the switching frequency of the second conversion branch and the same duty ratio phase-shifting 360/(2+A).

In a second aspect, the application provides an electronic device comprising a voltage conversion circuit as described above.

The beneficial effects of the application are as follows: the voltage conversion circuit provided by the application comprises a first conversion branch, a second conversion branch and a controller. The first conversion branch is connected with the input power supply and the second conversion branch respectively, and the controller is connected with each switch tube in the first conversion branch and the second conversion branch respectively. The controller is used for controlling the on and off of each switching tube in the first conversion branch circuit so as to generate at least two paths of pulse signals with voltage amplitude which is half of the voltage of the input power supply, and at least two current sources are respectively generated based on the at least two paths of pulse signals to supply current for the second conversion branch circuit. The controller is also used for controlling each switching tube in the second conversion branch to be periodically turned on and turned off so as to generate an output voltage based on the current provided by the at least two current sources. Compared with the full-bridge LLC type DCDC converter in the related art, the application firstly obtains the pulse signal of half of the voltage of the input power supply, and then can increase the duty ratio of each switching tube when the same power is output so as to reduce the current, thereby improving the voltage conversion efficiency.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.

Fig. 1 is a schematic structural diagram of a full-bridge LLC-type DCDC converter in the related art;

fig. 2 is a schematic diagram of a voltage conversion circuit according to a first embodiment of the present application;

fig. 3 is a schematic circuit diagram of a voltage conversion circuit according to a first embodiment of the present application;

fig. 4 is a schematic circuit diagram of a voltage conversion circuit according to a second embodiment of the present application;

FIG. 5 is a schematic diagram of signals in the voltage converting circuit shown in FIG. 4;

FIG. 6 is an equivalent circuit diagram of the voltage converting circuit shown in FIG. 4;

FIG. 7 is a second equivalent circuit diagram of the voltage converting circuit shown in FIG. 4;

FIG. 8 is a second schematic diagram of signals in the voltage converting circuit shown in FIG. 4;

fig. 9 is a schematic circuit diagram of a voltage conversion circuit according to a third embodiment of the present application;

fig. 10 is a schematic circuit diagram of a voltage conversion circuit according to a fourth embodiment of the present application;

Fig. 11 is a schematic circuit diagram of a voltage conversion circuit according to a fifth embodiment of the present application;

FIG. 12 is a schematic diagram of signals in the voltage converting circuit shown in FIG. 11;

FIG. 13 is a second schematic diagram of signals in the voltage converting circuit shown in FIG. 11;

fig. 14 is a schematic circuit diagram of a voltage conversion circuit according to a sixth embodiment of the present application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Referring to fig. 1, fig. 1 is a schematic diagram illustrating a configuration of a full-bridge LLC type DCDC converter in the related art. As shown in fig. 1, the full-bridge LLC DCDC converter 100 includes an input filter capacitor 101, a first power switch 102, a second power switch 103, a third power switch 104, a fourth power switch 105, an inductor 106, a transformer 107, a first rectifier diode 108, a second rectifier diode 109, and an output filter capacitor 110.

The first power switch 102, the second power switch 103, the third power switch 104 and the fourth power switch 105 form a full-bridge inverter, and convert the voltage of the input power Vin into alternating square wave ac power sources at two ends of the switch node 111 and the switch node 112. The square wave ac voltage has an amplitude equal to the voltage of the input power Vin and a frequency equal to the switching frequency of the full bridge inverter. The introduction of the inductor 106 creates Zero Voltage Switching (ZVS) for the four power switches to reduce switching losses and thereby improve conversion efficiency. The transformer 107 is used to step down the ac voltage to a voltage close to that required at the voltage output terminal Vout. The first rectifier diode 108, the second rectifier diode 109 form a full-wave rectifier circuit together with the secondary winding of the transformer 107, converting the ac voltage at the secondary winding of the transformer 107 into a dc voltage. The output filter capacitor 110 is used for smoothing the rectified voltage at the common node 113 into a dc voltage with smaller ripple to meet the output ripple voltage requirement.

The operation of the full-bridge LLC type DCDC converter 100 is described as follows: during a first period of time in one operating cycle, the first power switch 102 and the fourth power switch 105 are turned on and the second power switch 103 and the third power switch 104 are turned off. The voltage of the input power Vin is applied between the switching node 111 and the switching node 112, with the polarity being positive at the switching node 111 and negative at the switching node 112. Energy is transferred from the input to the output filter capacitor 110 through the first power switch 102, the fourth power switch 105, the inductor 106, the transformer 107, the first rectifier diode 108. A system load connected to the voltage output Vout draws energy from the output filter capacitor 110. During the time period when the first power switch 102 is off and the second power switch 103 is on, the fourth power switch 105 remains on and the third power switch 104 remains off, and the energy transfer stops. During the transition of the first power switch 102 being off and the second power switch 103 being on, the second power switch 103 may achieve ZVS. Once the second power switch 103 is on, the converter enters a second period of time in one operating cycle. During a second period of operation, there is no power transfer between the input power source Vin and the voltage output Vout, and the system load connected at the voltage output Vout is powered by the output capacitor 110. The inductor current 114 is clamped by the second power switch 103 and the third power switch 104. Once the third power switch 104 is on, the fourth power switch 105 is off, and a third period of time in one operating cycle is entered. Since the inductor current 114 remains positive for the second period, this switching transition begins by turning off the fourth power switch 105 and the inductor current 114 charges its drain-source capacitance, resulting in a voltage rise at the switch node 112. Once the voltage at the switch node 112 reaches the voltage of the input power source Vin, the body diode of the third power switch 104 turns on and clamps the voltage at the switch node 112 to the voltage of the input power source Vin. At this time, the third power switch 104 may be turned on with the voltage difference across its drain-to-source terminal being zero. After the switching is completed, the polarities of the voltages at the switch node 111 and the switch node 112 are reversed, the switch node 112 is positive, and the switch node 111 is negative. The reverse voltage causes the inductor current 114 to decrease and reverse its direction, causing the second rectifier diode 109 to conduct. The inductor current 114 stabilizes once it reaches the average current of the system load connected at the voltage output Vout. In a third period of time, power is transferred from the input power source Vin to the output capacitor 110 through the second power switch 103, the third power switch 104, the inductor 106, the transformer 107, the second rectifier diode 109. The system load connected to the voltage output Vout is supplied by the output capacitor 110. At the end of the third time period, the third power switch 104 is turned off and the fourth power switch 105 is turned on. The switching transition begins with turning off the third power switch 104. Since the direction of the inductor current 114 reverses during the third time period, the inductor current 114 charges the drain-source capacitance of the third power switch 104 after the third power switch 104 is turned off and causes the voltage at the switch node 112 to decrease. Once the voltage at the switch node 112 reaches zero volts, the body diode of the fourth power switch 105 turns on and clamps its drain-source voltage to zero. At this point, the fourth power switch 105 may be turned on at zero voltage and the converter enters a fourth period of time in one operating cycle. The first power switch 102 remains in an off state and the second power switch 103 remains in an on state. During this period, there is no power transfer between the input power Vin and the voltage output Vout. The system load connected to the voltage output Vout is supplied by the output capacitor 110. The fourth period of time ends when the first power switch 102 is on and the second power switch 103 is off. The transition starts with turning off the second power switch 103. Since the inductor current 114 is negative, the inductor current 114 charges the drain-source capacitance of the second power switch 103 when the second power switch 103 is turned off, thereby raising the voltage at the switch node 111. Once the voltage at the switch node 111 reaches the voltage of the input power source Vin, the body diode of the first power switch 102 turns on and clamps the voltage of the switch node 111 to the voltage of the input power source Vin. At this time, the first power switch 102 may be turned on at zero voltage. The third power switch 104 remains in an off state and the fourth power switch 105 remains in an on state. By re-entering the first time period in another operating cycle and repeating the switching cycle. This control mode is called PWM control. One disadvantage of PWM control is that there is no energy transfer between the input power source Vin and the voltage output Vout during the second and fourth time periods, but that power dissipation due to the on-resistance of the second and fourth power switches 103, 105 continues to exist due to the inductor current 114. This behavior can reduce efficiency, especially when the system is heavily loaded. To reduce power consumption, the duration of the second and fourth time periods should be reduced as much as possible to meet ZVS transition requirements, resulting in a variable frequency control scheme, i.e., output voltage regulation by changing the switching frequency rather than PWM. In the variable switching frequency control, the duty ratio (on time of the first period and the third period) is maintained at 50%, and the second period and the fourth period become very short switching transition periods.

In a full-bridge LLC type DCDC converter 100, it is typically implemented with discrete vertical structure MOSFET devices and half-bridge MOSFET drivers. Because the voltage of the input power Vin (e.g., 40V to 60V) is high, those vertical structure MOSFET devices and half-bridge MOSFET drivers cannot be integrated into a single silicon device in a cost-effective manner to minimize the effects of PCB layout parasitic parameters due to vertical device process limitations. This discrete implementation limits the switching frequency due to parasitic inductance and resistance from the PCB layout and large gate capacitance of the high voltage vertical structure MOSFET structure. The amount of voltage drop required by the vertical MOSFET devices (typically 80%) results in the first power switch 102, the second power switch 103, the third power switch 104, and the fourth power switch 105 being required to employ a minimum of 75V drain-source voltage. A high voltage rating of the output diode is also required. If the first rectifying diode 108 and the second rectifying diode 109 are replaced with synchronous rectifiers (MOSFETs), the voltage rating of the synchronous rectifiers is equal to or more than twice the voltage of the voltage output terminal Vout. The high gate capacitance and low switching speed of high voltage vertical MOSFET devices limit the switching frequency to 500kHz or less, requiring large magnetic devices. Second, in many applications of servers and data centers, the variable switching frequency approach is not allowed, resulting in lower conversion efficiency. In addition, LLC-type converters require the same switching frequency of the input full-bridge inverter and the output synchronous rectifier, even though the output synchronous rectifier may integrate the output synchronous rectifier of the LLC-type converter with Bipolar CMOS and DMOS (BCD) processes due to a lower nominal voltage, such as when the voltage at the voltage output terminal Vout is 5V or 3.3V. The BCD process provides faster switching rates compared to vertical structure MOSFET devices and does not increase switching losses and device size at lower rated voltages (e.g., less than 12V). If the synchronous rectifier is capable of switching at a higher switching frequency than the input full-bridge inverter, it is advantageous to reduce the need for output capacitance to meet the output ripple voltage requirement, especially when the voltage at the voltage output Vout is low (e.g., 5V or 3.3V), the higher switching frequency can simultaneously reduce the switching losses of the full-bridge inverter.

Based on the above, the embodiment of the application provides a new topological structure, namely the voltage conversion circuit provided by the embodiment of the application. The transformer is omitted, so that occupied area is reduced, and voltage conversion efficiency can be improved.

Referring to fig. 2, fig. 2 is a schematic diagram of a voltage conversion circuit according to an embodiment of the application. As shown in fig. 2, the voltage conversion circuit 200 includes a first conversion branch 201, a second conversion branch 202, and a controller 203.

The first conversion branch 201 is connected to the input power Vin and the second conversion branch 202, respectively. The controller 203 is connected to each of the switching tubes in the first switching leg 201 and the second switching leg 202, respectively, i.e., the controller 203 is connected to each of the switching tubes in the first switching leg 201, and the controller 203 is connected to each of the switching tubes in the second switching leg 202.

Specifically, the controller 203 is configured to control on and off of each switching tube in the first conversion branch 201, so as to generate at least two pulse signals with a voltage amplitude half that of the input power Vin, and generate at least two current sources to provide current for the second conversion branch 202 based on the at least two pulse signals. The controller 203 is further configured to control each switching tube in the second switching leg 202 to be turned on and off periodically to generate an output voltage based on the current provided by the at least two current sources.

As can be seen from the description of fig. 1, in the related art, if the full-bridge LLC type DCDC converter is to achieve a high voltage reduction ratio (e.g., 12V to 1V), the duty ratio of the switching tube is relatively low, and the time for transmitting power is short, which results in a large required current and a relatively low transmission efficiency. In the embodiment of the application, the pulse signal of half of the voltage of the input power supply is obtained first, and then when the same power is output, the duty ratio of each switching tube can be increased to reduce the current, thereby improving the voltage conversion efficiency. In addition, the transformer is omitted in this embodiment to reduce the area occupied by the voltage conversion circuit.

In an embodiment, the second conversion branch 202 is a switched capacitor conversion circuit, and the second conversion branch 202 includes at least one current input terminal, one voltage output terminal, one output capacitor, at least three switching transistors, and at least one energy storage capacitor.

Among them, a Switched-capacitor switching circuit (Switched-Capacitor Converter) is a power switching circuit that performs voltage or current switching by periodically switching the connection and disconnection of a capacitor.

The basic principle of a switched capacitor switching circuit is to control the connection between a capacitor and input and output circuits using switching elements, typically MOSFETs. By alternately charging and discharging the capacitor, up-down conversion of voltage or current can be achieved

In this embodiment, during a portion of the switching cycle of the second switching leg 202, the conduction of a portion of the switching tubes in the second switching leg is controlled to cause the current source to charge the storage capacitor through the current input. In another part of the switching cycle of the second converting branch 202, another part of the switching tubes in the second converting branch are controlled to be conducted, so that the energy storage capacitor discharges to the output capacitor through the voltage output terminal.

Referring to fig. 3, fig. 3 illustrates a first circuit configuration of the voltage conversion circuit 200.

In an embodiment, as shown in fig. 3, the first conversion branch 201 includes a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a first capacitor C1, a second capacitor C2, a first inductor L1 and a second inductor L2.

The third terminal of the first switching tube Q1 is connected to the first terminal of the first capacitor C1 and the input power Vin, respectively. The second end of the first switching tube Q1 is connected to the third end of the second switching tube Q2 and the first end of the second capacitor C2, respectively. The second end of the second switching tube Q2 is connected to the third end of the third switching tube Q3 and the first end of the first inductor L1, respectively. The second end of the first inductance L1 is connected to the second switching leg 202. And the second end of the first inductor L1 is the output end of the first current source of the at least two current sources. The second end of the second capacitor C2 is connected to the first end of the second inductor L2 and the third end of the fourth switching tube Q4, respectively. A second end of the second inductance L2 is connected to the second switching leg 202. And the second end of the second inductor L2 is the output end of the second current source of the at least two current sources. The second end of the first capacitor C1, the second end of the third switching tube Q3, and the second end of the fourth switching tube Q4 are all grounded. The controller 203 is connected to the first end of the first switching tube Q1, the first end of the second switching tube Q2, the first end of the third switching tube Q3, and the first end of the fourth switching tube Q4, respectively.

In an embodiment, the second converting branch 20 includes a fifth switching tube Q5, a sixth switching tube Q6, a seventh switching tube Q7, a third capacitor C3 and a fourth capacitor C4.

The third end of the fifth switching tube Q5 is connected to the first end of the third capacitor C3, the second end of the first inductor L1, and the second end of the second inductor L2, respectively. The second end of the fifth switching tube Q5 is connected to the third end of the sixth switching tube Q6 and the first end of the fourth capacitor C4, respectively. The second end of the sixth switching tube Q6 is connected to the second end of the third capacitor C3 and the third end of the seventh switching tube Q7, respectively. The second end of the fourth capacitor C4 and the second end of the seventh switching tube Q7 are grounded. The controller is connected with the first end of the fifth switching tube Q5, the first end of the sixth switching tube Q6 and the first end of the seventh switching tube Q7 respectively. The first end of the third capacitor C3 is a current input end, the first end of the fourth capacitor C4 is a voltage output end, the fourth capacitor C4 is an output capacitor, and the third capacitor C3 is an energy storage capacitor.

In this embodiment, for the first conversion branch 201, the first switching tube Q1 and the fourth switching tube Q4 are turned on and off in a complementary manner, and the second switching tube Q2 and the third switching tube Q3 are turned on and off in a complementary manner. The control signals of the first switching tube Q1 and the second switching tube Q2 have the same PWM pulse width d×ts, but the phases of the control signals of the first switching tube Q1 and the second switching tube Q2 are opposite. Where D is defined as the duty cycle, i.e. the duty cycle of the on-times of the first switching tube Q1 and the second switching tube Q2 in one switching cycle.

The second conversion leg 202 is implemented as a single-phase switched capacitor converter. The combination of the fifth switching tube Q5 and the seventh switching tube Q7 and the sixth switching tube Q6 are turned on and off in a complementary manner.

Specifically, in the circuit structure shown in fig. 3, the first converting branch 201 is configured to convert the input power Vin into at least two pulse signals with voltage amplitude Vin/2 (i.e., the voltage pulse signals at the first end of the second inductor L2 and the first end of the first inductor L1), so as to generate two current sources represented by two inductor currents (a current flowing through the first inductor L1 and a current flowing through the second inductor L2).

Wherein each switching tube in the first conversion branch 201 works in PWM mode, the PWM signal is regulated based on the voltage of the voltage output terminal Vout and is always less than 50%. This is achieved in particular by adjusting the on-time of the first switching tube Q1 and the second switching tube Q2 to alternately switch the two inductor currents to adjust the voltage at the voltage output terminal Vout to a desired value. The switching transistors in the second switching leg 202 are turned on and off in a complementary manner, and the fixed switching frequency of the switching transistors in the second switching leg 202 is equal to or higher than the switching frequency of the switching transistors in the first switching leg 201.

Moreover, during a part of the switching period of the second converting branch 202, the current on the first inductor L1 and the current on the second inductor L2 together charge the third capacitor C3 (i.e. the energy storage capacitor) through the turned-on sixth switching tube Q6, and during another part of the switching period of the second converting branch 202, the third capacitor C3 (i.e. the energy storage capacitor) discharges to the output capacitor (i.e. the fourth capacitor C4) through the turned-on fifth switching tube Q5 and the turned-on seventh switching tube Q7, so as to convert the two input currents into the voltage of the voltage output terminal Vout. In any embodiment of the present application, a first end of each switching tube (including an extension switching tube) is taken as a gate, a second end is taken as a source, and a third end is taken as a drain.

Referring to fig. 4, fig. 4 illustrates a second circuit configuration of the voltage conversion circuit 200. The first conversion branch 201 in the circuit configuration shown in fig. 4 is identical to that shown in fig. 3.

In an embodiment, as shown in fig. 4, the second converting branch 202 includes an eighth switching tube Q8, a ninth switching tube Q9, a tenth switching tube Q10, an eleventh switching tube Q11, a twelfth switching tube Q12, a thirteenth switching tube Q13, a fifth capacitor C5, a sixth capacitor C6, and a seventh capacitor C7.

The third end of the eighth switching tube Q8 is connected to the first end of the fifth capacitor C5 and the second end of the first inductor L1, respectively. The second end of the eighth switching tube Q8 is connected to the third end of the ninth switching tube Q9 and the first end of the sixth capacitor C6, respectively. The second end of the ninth switching tube Q9 is connected to the second end of the fifth capacitor C5 and the third end of the tenth switching tube Q10, respectively. The second end of the sixth capacitor C6 and the second end of the tenth switching tube Q10 are both grounded GND. The third terminal of the eleventh switching tube Q11 is connected to the first terminal of the seventh capacitor C7 and the second terminal of the second inductor L2, respectively. The second end of the eleventh switching tube Q11 is connected to the third end of the twelfth switching tube Q12 and the first end of the sixth capacitor C6, respectively. The second end of the twelfth switching tube Q12 is connected to the second end of the seventh capacitor C7 and the third end of the thirteenth switching tube Q13, respectively. The second end of the thirteenth switching tube Q13 is grounded. The controller 203 is connected to the first end of the eighth switching tube Q8, the first end of the ninth switching tube Q9, the first end of the tenth switching tube Q10, the first end of the eleventh switching tube Q11, the first end of the twelfth switching tube Q12, and the first end of the thirteenth switching tube Q13, respectively.

The first end of the fifth capacitor C5 and the first end of the seventh capacitor C7 are both current input ends, the first end of the sixth capacitor C6 is a voltage output end, the sixth capacitor C6 is an output capacitor, and the fifth capacitor C5 and the seventh capacitor C7 are energy storage capacitors.

The embodiment of the application also provides a control mode based on the figure 4. Specifically, in one embodiment, the controller 203 is further configured to: in a first time period in one working cycle, the first switching tube Q1, the third switching tube Q3, the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a second time period in one working cycle, the third switching tube Q3, the fourth switching tube Q4, the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a third time period in one working cycle, the second switching tube Q2, the fourth switching tube Q4, the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a fourth period of time in one working cycle, the third switching tube Q3, the fourth switching tube Q4, the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13 are controlled to be turned on, and the other switching tubes are controlled to be turned off.

The above-described operation principle will be described in detail with reference to fig. 5. As shown in fig. 5, the abscissa indicates time. The curve L11 is a control signal for controlling the first switching tube Q1; curve L12 is a control signal for controlling the fourth switching tube Q4; the curve L13 is a control signal for controlling the second switching tube Q2; curve L14 is a control signal for controlling the third switching tube Q3; the curve L15 is a control signal for controlling the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12; the curve L16 is a control signal for controlling the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13; curve L17 is the current flowing through the first inductor L1; curve L18 is the current flowing through the second inductor L2; curve L19 is the voltage at the first end of the second capacitor C2; curve L20 is the voltage at the second end of the second capacitor C2; curve L21 is the voltage at the first end of the first inductor; curve L22 is the voltage at the second end of the first inductor L1; curve L23 is the voltage at the second end of the fifth capacitor C5; curve L24 is the voltage at the first end of the seventh capacitor C7; curve L25 is the voltage at the second end of the seventh capacitor C7.

Wherein the curve L11 is complementary to the curve L12. Curve L13 is complementary to curve L14. The curves L11 and L13 have the same PWM pulse width d×ts and opposite phases, where D is defined as the duty cycle, i.e., the time duty cycle of the T1 period or the T3 period within one switching period. T1=t3=d×ts. In this embodiment, the control signals in the curves L15, L16 run at a duty cycle of 50% and the curve L15 is complementary to the curve L16. The control signals in curves L15, L16 may also be complementary signals at other duty cycles.

Specifically, in the circuit structure shown in fig. 4, the first converting branch 201 is configured to convert the input power Vin into at least two pulse signals with voltage amplitude Vin/2 (i.e., the voltage pulse signals at the first end of the second inductor L2 and the first end of the first inductor L1 shown by the curves L20 and L21), so as to generate two current sources represented by two inductor currents (a current flowing through the first inductor L1 and a current flowing through the second inductor L2). The second conversion branch 202 functions to convert the two current sources into a voltage at the voltage output Vout.

Wherein each switching tube in the first conversion branch 201 operates in a Pulse Width Modulation (PWM) control manner, and the duty cycle of the PWM signal is adjusted based on the voltage of the voltage output terminal Vout and is always less than 50%. Specifically, the current on the two inductors can be controlled by adjusting the on time of the first switching tube Q1 and the second switching tube Q2 to adjust the voltage of the voltage output terminal Vout to a desired value. Each switching tube in the second conversion branch 202 operates at a 50% duty cycle, and the fixed switching frequency of each switching tube in the second conversion branch 202 is equal to or higher than the switching frequency of each switching tube in the first conversion branch 201.

Assuming that the first conversion leg 201, the second conversion leg 202 and operate at the same switching frequency, the operation of the voltage conversion circuit 200 is described as follows: in a first period t1= [ T0, T1] in one working cycle, the first switching tube Q1, the third switching tube Q3, the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12 are turned on, and the other switching tubes are turned off. The second capacitor C2 and the second inductor L2 are charged by the input power Vin through the first switching tube Q1, the twelve switching tube Q12 and the sixth capacitor C6. The voltage at the first end of the seventh capacitor C7 is equal to the voltage at the first end of the sixth capacitor C6 plus the voltage difference across the seventh capacitor C7. The voltage difference across the eleventh switching tube Q11 is equal to the voltage difference across the seventh capacitor C7, and the voltage difference across the thirteenth switching tube Q13 is equal to the voltage of the voltage output terminal Vout. The first inductor L1 discharges through the third switching tube Q3 and the eighth switching tube Q8 to transfer its stored energy to the sixth capacitor C6. The fifth capacitor C5 discharges through the eighth and tenth switching transistors Q8 and Q10 to transfer its stored energy to the sixth capacitor C6. The voltage difference across the ninth switching tube Q9 is equal to the voltage of the voltage output terminal Vout, and the voltage difference across the fifth capacitor C5 is also equal to the voltage of the voltage output terminal Vout, because the fifth capacitor C5 is connected in parallel with the sixth capacitor C6 through the eighth switching tube Q8 and the tenth switching tube Q10. Since the voltage of the first terminal of the second capacitor C2 is clamped at the voltage of the input power Vin by the first switching tube Q1 and the voltage of the first terminal of the first inductor L1 is clamped at the ground by the third switching tube Q3, the voltage difference across the second switching tube Q2 is equal to the voltage of the input power Vin. The voltage difference across the fourth switching tube Q4 is equal to the voltage of the input power Vin minus the voltage difference across the second capacitor C2. Energy is transferred from the input to the sixth capacitance C6 through the first switching tube Q1, the twelfth switching tube Q12, the second inductance L2, the second capacitance C2 and the seventh capacitance C7. The second capacitor C2, the seventh capacitor C7 and the second inductor L2 are charged. The system load connected to the voltage of the voltage output terminal Vout takes power from the sixth capacitor C6.

The period T1 ends. The first switching tube Q1 is turned off and the fourth switching tube Q4 is turned on, and the other switching tubes maintain the switching state in the period T1, and enter the second period T2 in one operation cycle. The period T2 is defined as t2= [ T1, t0+ts/2], where Ts is the switching period. During the period T2, the energy stored in the second inductance L2 is transferred to the sixth capacitance C6 through the fourth switching tube Q4, the twelfth switching tube Q12, and the seventh capacitance C7. The seventh capacitor C7 is continuously charged by the current flowing through the second inductor L2. The voltage at the second end of the second inductor L2 is kept equal to the sum of the voltage difference across the seventh capacitor C7 and the voltage at the voltage output terminal Vout. During T2, there is no energy transfer between the voltage of the input power Vin and the voltage of the voltage output Vout, and the energy stored in the second capacitor C2 remains unchanged.

At the end of the period T2, the second switching tube Q2, the ninth switching tube Q9, the eleventh switching tube Q11, the thirteenth switching tube Q13 are turned on and the third switching tube Q3, the eighth switching tube Q8, the tenth switching tube Q10, the twelfth switching tube Q12 are turned off, and the switching states of the first switching tube Q1 and the fourth switching tube Q4 maintained in the period T2 are thereby entered into the third period T3 in one operation cycle. The period T3 is defined as t3= [ t0+ts/2, T2]. During the period T3, the energy stored in the second capacitor C2 is transferred to the sixth capacitor C6 through the second switching tube Q2, the ninth switching tube Q9, the first inductor L1 and the fifth capacitor C5. The first inductance L1 and the fifth capacitance C5 are charged by the energy stored in the second capacitance C2. The voltage at the first terminal of the fifth capacitor C5 is equal to 2 times the voltage at the voltage output terminal Vout. The voltage at the first end of the first inductor L1 is equal to the voltage difference across the second capacitor C2. The voltage difference across the eighth switching tube Q8 and the tenth switching tube Q10 is equal to the voltage of the voltage output terminal Vout. The voltage difference across the third switching tube Q3 is equal to the voltage difference across the second capacitor C2. The voltage difference across the first switching tube Q1 is equal to the difference between the voltage of the input power Vin and the voltage across the second capacitor C2. The seventh capacitor C7 and the second inductor L2 are discharged by transferring their stored energy to the sixth capacitor C6 through the combination of the eleventh and thirteenth switching transistors Q11 and Q13 and the combination of the eleventh and fourth switching transistors Q11 and Q4, respectively. The voltage at the second end of the second inductor L2 is equal to the voltage at the voltage output end Vout. Therefore, the voltage difference across the seventh capacitance C7 is equal to the output voltage Vout. The voltage difference across the twelfth switching tube Q12 is equal to the output voltage Vout. There is no energy transfer between the input power source Vin and the voltage output Vout.

The period T3 ends with turning off the second switching transistor Q2 and turning on the third switching transistor Q3. And, the remaining switching tubes remain in the switching state for the period T3, and enter a fourth period T4 in one operation cycle. The period T4 is defined as t4= [ T2, t0+ts ]. During the period T4, the energy stored in the second capacitance C2 remains unchanged. The energy stored in the first inductor L1 is transferred to the fifth capacitor C5 and the sixth capacitor C6 through the third switching tube Q3 and the ninth switching tube Q9. The voltage at the second terminal of the first inductor L1 is kept equal to 2 times the voltage at the voltage output terminal Vout. The energy stored in the second inductor L2 and the seventh capacitor C7 is continuously supplied to the sixth capacitor C6 through the combination of the eleventh switching tube Q11 and the fourth switching tube Q4 and the combination of the eleventh switching tube Q11 and the thirteenth switching tube Q13, respectively. The voltage at the second end of the second inductor L2 is equal to the voltage at the voltage output end Vout.

The period T4 ends by turning on the first switching tube Q1, the eighth switching tube Q8, the tenth switching tube Q10, and the twelfth switching tube Q12, and turning off the ninth switching tube Q9, the fourth switching tube Q4, the eleventh switching tube Q11, and the thirteenth switching tube Q13. When the period T4 ends, the voltage conversion circuit 200 starts a new switching cycle.

For the above operation we assume t1=t3 and t2=t4 to keep the voltage difference across the second capacitor C2 constant. Also, it can be concluded from the above description that the voltage difference across the fifth capacitor C5 and the seventh capacitor C7 is equal to the output power Vout. We derive the voltage difference across the second capacitor C2 as follows.

The voltage difference across the second capacitor C2 is between the voltage of the input power Vin and 0V. Suppose the DC voltage on the second capacitor C2 is higher than Vin/2.

In the time period T1, the voltage difference VL2 across the second inductance L2 is:

wherein VC2 is the voltage difference between the two ends of the second capacitor C2.

Similarly, during the period T3, the voltage difference VL1 across the first inductance L1 is:

since VC2 > Vin/2, the value of VL2 is less than the value of VL 1. In the time period T1 and the time period T3, the voltages at the second end of the first inductor L1 and the second end of the second inductor L2 are 2 times the voltage of the voltage output terminal Vout. This means that the first inductance L1 has a higher current change rate than the second inductance L2. Since t1=t3, the current flowing through the first inductor L1 is higher than the current flowing through the second inductor L2. In the falling section of the current flowing through the inductor, it can be seen that the voltages at the second end of the first inductor L1 and the second end of the second inductor L2 are the same, i.e. the current flowing through the first inductor L1 and the current flowing through the second inductor L2 fall to the same amount. Thus, the average value of the current flowing through the first inductor L1 is higher than the average value of the current of the second inductor L2, resulting in a non-zero net charge change of the sixth capacitor C6 during one switching cycle and more discharge of the second capacitor C2 than charge. Thus, the voltage difference across the second capacitor C2 decreases until it is equal to Vin/2. In this case, it is possible to combine equations (1) and (2):

And the net charge change of the second capacitor C2 is zero during one switching cycle, resulting in a constant voltage difference across the second capacitor C2.

From the typical waveforms of the curves L22 and L24, the voltages at the second end of the first inductor L1 and the second end of the second inductor L2 are not constant in one switching period, wherein the voltage in one half of the switching period is 2×vout, and the voltage in the other half of the switching period is Vout. The average voltages of the voltages at the second end of the first inductor L1 and the second end of the second inductor L2 in one switching period are denoted as VL1 AVE and VL2 AVE, respectively:

if the average voltage of the second end of the first inductor L1 and the second end of the second inductor L2 to the ground is replaced by the voltage source voltage Vo given in equation (4), the equivalent circuit diagram can be shown in fig. 6. The relationship between the voltage of the input power Vin and the voltage of the voltage output terminal Vout is:

according to equation (5), the voltage source voltage Vo maximum value is equal to Vin/4 given the input power Vin. Representing Vout as a function of Vin and D, one can obtain:

according to the above equation, the maximum Vout for any given input power Vin is:

for example, when vin=30v, the maximum Vout is equal to 5V.

Referring to fig. 7, fig. 7 illustrates one topology of the circuit configuration shown in fig. 4 that operates at the same switching frequency for both the first conversion leg 201 and the second conversion leg 202. As shown in fig. 7, part (a) in fig. 7 represents an equivalent circuit diagram of the voltage conversion circuit 200 in the period T1; part (b) in fig. 7 shows an equivalent circuit diagram of the voltage conversion circuit 200 in the period T2; part (c) in fig. 7 shows an equivalent circuit diagram of the voltage conversion circuit 200 in the period T3; part (d) in fig. 7 shows an equivalent circuit diagram of the voltage conversion circuit 200 in the period T4.

In the period T1 and the period T2, the fifth capacitor C5 and the sixth capacitor C6 form a capacitor loop. The current flowing through the seventh capacitor C7 is equal to the current flowing through the second inductor L2. In the period T3 and the period T4, the seventh capacitor C7 and the sixth capacitor C6 form a capacitor loop. The current flowing through the fifth capacitor C5 is equal to the current flowing through the first inductor L1. Large inrush currents may occur in the capacitive loop during transitions between topological modes, thereby creating large charge transfer losses. Care is taken with respect to the control signals of the power switches to minimize the inrush current in the capacitor loop during topology mode switching. One approach is to add a certain amount of delay between the control signals of the power switches associated with the capacitive loop to turn on the associated power switches when the instantaneous voltages of the capacitances in the capacitive loop are equal or close enough. These delays may be implemented in an open loop approach, i.e., a fixed amount of delay, or an adaptive approach, i.e., monitoring the capacitor voltage in the capacitor loop to open the associated power switch when the capacitor voltages in the capacitor loop are substantially equal.

The embodiment of the application also provides another control mode based on the figure 4. Specifically, in an embodiment, the controller is further configured to: in a first time period in one working cycle, the first switching tube Q1, the third switching tube Q3, the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a second time period in one working cycle, the first switching tube Q1, the third switching tube Q3, the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a third time period in one working cycle, the third switching tube Q3, the fourth switching tube Q4, the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a fourth time period in one working cycle, the second switching tube Q2, the fourth switching tube Q4, the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a fifth time period in one working cycle, the second switching tube Q2, the fourth switching tube Q4, the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13 are controlled to be turned on, and other switching tubes are controlled to be turned off; in a sixth period of time in one working cycle, the third switching tube Q3, the fourth switching tube Q4, the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13 are controlled to be turned on, and the other switching tubes are controlled to be turned off.

In the control method described above, the signals in the circuit configuration shown in fig. 4 are shown in fig. 8. As shown in fig. 8, the abscissa indicates time. The curve L31 is a control signal for controlling the first switching tube Q1; curve L32 is a control signal for controlling the fourth switching tube Q4; curve L33 is a control signal for controlling the second switching tube Q2; curve L34 is a control signal for controlling the third switching tube Q3; the curve L35 is a control signal for controlling the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12; the curve L36 is a control signal for controlling the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13; curve L37 is the current flowing through the first inductor L1; curve L38 is the current flowing through the second inductor L2; curve L39 is the voltage at the first end of the second capacitor C2; curve L40 is the voltage at the second end of the second capacitor C2; curve L41 is the voltage at the first end of the first inductor; curve L42 is the voltage at the second end of the first inductor L1; curve L43 is the voltage at the second end of the fifth capacitor C5; curve L44 is the voltage at the first end of the seventh capacitor C7; curve L45 is the voltage at the second end of the seventh capacitor C7.

In this embodiment, the switching frequency of the second switching leg 202 is equal to twice the switching frequency of the first switching leg 201. As shown in fig. 8, the voltages at the second end of the first inductor L1 and the second end of the second inductor L2 respectively show Vout and 2×vout twice in one switching cycle of the first conversion branch 201. The period of Vout and 2×vout are the same. Therefore, equation (4) for the voltage average of the second end of the first inductor L1 and the second end of the second inductor L2 is still valid. Equations (5), (6) and (7) apply to the mode of operation given in fig. 8. In practice, as long as the switching frequency of the second conversion branch 202 is M, the switching frequency of the first conversion branch 201 is an integer multiple of M, equations (4) to (7) are established, and the voltage of the voltage output terminal Vout can be adjusted by changing D (the duty ratio of the first conversion branch 201).

Furthermore, in this embodiment, if directed solely to the second switching leg 202, the controller is further configured to: controlling the combination of the eighth switching tube Q8 and the tenth switching tube Q10 and the ninth switching tube Q9 to be alternately switched on and off in a complementary mode; controlling the combination of the eleventh switching tube Q11 and the thirteenth switching tube Q13 and the twelfth switching tube Q12 to be alternately switched on and off in a complementary mode; the eighth switching tube Q8 and the eleventh switching tube Q11 are turned on and off by 180 degrees with the same duty cycle and phase-shifting by the switching frequency of the second switching branch 202.

As can be seen from the above analysis of the circuit shown in fig. 4, the voltage waveform at the first end of the first inductor L1 and the voltage waveform at the first end of the second inductor L2 (the curves L21 and L20 shown in fig. 5, or the curves L41 and L40 shown in fig. 8) are both periodic pulse signals with a magnitude half the voltage (Vin/2) of the input power Vin, and the duty cycle of the two pulse signals is the same but the phases are opposite. The two periodic pulse signals respectively generate two current sources on the second inductor L2 of the first inductor L1 to supply current to the second switching leg 200. For the second converting branch 202, the switching frequency of the switching tube is the same as that of the first converting branch 201 or twice that of the first converting branch 202, the voltage of the voltage output terminal Vout is generated based on the currents provided by the two current sources.

Moreover, regardless of the relationship between the switching frequency of the second conversion branch 202 and the switching frequency of the first conversion branch 201, during a portion of the switching period of the second conversion branch 202, the current on the first inductor L1 charges the fifth capacitor C5 (i.e., the energy storage capacitor) through the turned-on ninth switching transistor Q9, and during another portion of the switching period of the second conversion branch 202, the fifth capacitor C5 (i.e., the energy storage capacitor) discharges to the output capacitor (sixth capacitor C6) through the turned-on eighth switching transistor Q8 and the tenth switching transistor Q10. Likewise, during a portion of the switching cycle of the second switching leg 202, the current on the second inductor L2 charges the seventh capacitor C7 (i.e., the storage capacitor) through the turned-on twelfth switching tube Q12, and during another portion of the switching cycle of the second switching leg 202, the seventh capacitor C7 (i.e., the storage capacitor) discharges to the output capacitor (sixth capacitor C6) through the turned-on eleventh switching tube Q11 and thirteenth switching tube Q13. Thus, the second conversion branch 202 converts the two input currents into a voltage at the voltage output terminal Vout.

In an embodiment, the voltage conversion circuit 200 further includes M longitudinal extension branches cascaded in sequence to achieve a higher voltage reduction ratio, where M is an integer greater than or equal to 1. Referring to fig. 9 and 10 together, fig. 9 shows a circuit structure when M is even, and fig. 10 shows a circuit structure when M is odd.

Specifically, each of the longitudinal extension branches includes a first extension switch tube, a second extension switch tube, a first extension capacitor and a second extension capacitor, for example, the first longitudinal extension branch 20a1 includes a first extension switch tube QA1, a second extension switch tube QB1, a first extension capacitor CA1 and a second extension capacitor CB1. Wherein the second end of the first expansion switching tube QA1 in the first one of the M longitudinal expansion branches 20a1 is connected to the first end of the fifth capacitor C5, and the second end of the second expansion switching tube QB1 in the first one of the longitudinal expansion branches 20a1 is connected to the first end of the seventh capacitor C7. The first end of the first extension capacitor CA1 in the first longitudinal extension branch 20a1 is connected to the third end of the first extension switching tube QA1 in the first longitudinal extension branch 20a1, and the first end of the second extension capacitor CB1 in the first longitudinal extension branch 20a1 is connected to the third end of the second extension switching tube QB1 in the first longitudinal extension branch 20a 1. The third end of the first expansion switching tube QAM in the mth longitudinal expansion branch 20aM of the M longitudinal expansion branches is connected to the second end of the first inductance L1, and the third end of the second expansion switching tube QBM in the mth longitudinal expansion branch 20aM is connected to the second end of the second inductance L2. The second end of the first expansion capacitor in the odd-numbered longitudinal expansion branch of the M longitudinal expansion branches is connected with the second end of the seventh capacitor C7, and the second end of the second expansion capacitor in the odd-numbered longitudinal expansion branch of the M longitudinal expansion branches is connected with the second end of the fifth capacitor C5. The second ends of the first expansion capacitors in the even number of the M longitudinal expansion branches are connected to the second end of the fifth capacitor C5, and the second ends of the second expansion capacitors in the even number of the M longitudinal expansion branches are connected to the second end of the seventh capacitor C7.

When K is more than 1 and less than or equal to M, the second end of the first expansion switching tube in the Kth longitudinal expansion branch of the M longitudinal expansion branches is connected with the third end of the first expansion switching tube in the (K-1) th longitudinal expansion branch of the M longitudinal expansion branches, and the second end of the second expansion switching tube in the Kth longitudinal expansion switching tube is connected with the third end of the second expansion switching tube in the (K-1) th longitudinal expansion branch. For example, when k=2, the second end of the first extension switching tube QA2 in the second one of the M longitudinal extension branches 20a2 is connected to the third end of the first extension switching tube QA1 in the first one of the M longitudinal extension branches 20a1, and the second end of the second extension switching tube QB2 in the second one of the extension branches 20a2 is connected to the third end of the second extension switching tube QB1 in the first one of the longitudinal extension branches 20a 1.

The embodiment of the application also provides a control mode for the switching tubes in the second conversion branch 202 and the M longitudinal extension branches. Specifically, the controller is further configured to: the switching tubes in the second switching leg 202 and the longitudinal extension legs are controlled to be alternately turned on and off at a duty ratio of 50% so that the switching tubes in the second switching leg and the M longitudinal extension legs operate in two operating states. Wherein, in the first of two operating states, the controller is used for: the second expansion switching tube in the odd number of the M longitudinal expansion branches, the first expansion switching tube, the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12 in the even number of the M longitudinal expansion branches are controlled to be conducted, and other switching tubes are controlled to be turned off. In a second of the two operating states, the controller is configured to: the first expansion switching tube in the odd number of the M longitudinal expansion branches, the second expansion switching tube, the ninth switching tube Q9, the eleventh switching tube Q11 and the thirteenth switching tube Q13 in the even number of the M longitudinal expansion branches are controlled to be conducted, and other switching tubes are controlled to be turned off.

In this embodiment, the voltage conversion circuit 200 may also include four time periods T1-T4 similar to that shown in FIG. 5 during one duty cycle. Assuming that the first conversion leg 201 and the second conversion leg 202 share the same switching frequency, the operation of the voltage conversion circuit 200 is described as follows: in the time period T1, the first switching tube Q1, the third switching tube Q3, the second expansion switching tube in the odd number of the M longitudinal expansion branches, the first expansion switching tube, the eighth switching tube Q8, the tenth switching tube Q10 and the twelfth switching tube Q12 in the even number of the M longitudinal expansion branches are turned on, and the rest of the power switches are turned off. The voltage at the second end of the second inductor L2 is equal to (m+2) ×vout. The voltage at the second end of the first inductor L1 is equal to (m+1) ×vout. The voltage at the first end of the second capacitor C2 is equal to Vin and the voltage at the second end of the second capacitor C2 is equal to Vin/2. The voltage at the first end of the first inductor L1 is zero. The second capacitor C2, the second expansion capacitor CBM in the mth longitudinal expansion branch 20aM, and the second inductor L2 are charged by the input power Vin through the first switching tube Q1, the ninth switching tube Q9, and the sixth capacitor C6. Energy is transferred from the input to the sixth capacitance C6. The first expansion capacitor CAM in the mth longitudinal expansion branch 20aM is also discharged through the first expansion switching tube QAM, the twelfth switching tube Q12, the tenth switching tube Q10, and the first expansion capacitor CA (M-1) in the (M-1) th longitudinal expansion branch 20a (M-1) to transfer the energy stored therein to the sixth capacitor C6. The second expansion capacitor CB (M-1) in the (M-1) th longitudinal expansion branch 20a (M-1) discharges through the second expansion switch tube QB (M-1), the tenth switch tube Q10, the twelfth switch tube Q12, and the second expansion capacitor CB (M-2) in the (M-2) th longitudinal expansion branch 20a (M-1) to transfer its stored energy to the sixth capacitor C6. The second extension capacitor CB (M-2) in the (M-2) th longitudinal extension branch 20a (M-2) is charged. The first expansion capacitor CA (M-2) in the (M-2) th longitudinal expansion branch 20a (M-2) discharges through the first expansion switching tube QA (M-2), the twelfth switching tube Q12 and the tenth switching tube Q10 in the (M-2) th longitudinal expansion branch 20a (M-2) to transfer its stored energy to the sixth capacitor C6. During time period T1, the system load across the sixth capacitance C6 draws energy from the sixth capacitance C6.

The period T1 ends by turning off the first switching transistor Q1 and turning on the fourth switching transistor Q4. And, the remaining switching tubes maintain the switching state in the period T1, and enter the second period T2 in one operation cycle. During the period T2, there is no energy transfer between the input power Vin and the voltage output Vout. The energy stored in the second capacitance C2 remains unchanged. The second inductor L2 discharges through the fourth switching tube Q4, the twelfth switching tube Q12 and the second expansion capacitor CBM in the mth longitudinal expansion branch 20aM to transfer its stored energy to the sixth capacitor C6. The voltage at the first end of the second capacitor C2 is equal to Vin/2, and the voltage at the second end of the second capacitor C2 is zero. The charge and discharge states of the rest of the inductors and the flying capacitors and the voltages of the rest of the endpoints are consistent with the T1 interval. The system load connected across the sixth capacitance C6 draws energy from the sixth capacitance C6.

The time period T2 ends by turning on the second switching tube Q2, the ninth switching tube Q9, the eleventh switching tube Q11, the thirteenth switching tube Q13, the first expansion switching tube in the odd-numbered one of the M longitudinal expansion branches, the second expansion switching tube in the even-numbered one of the M longitudinal expansion branches, and turning off the second expansion switching tube in the odd-numbered one of the M longitudinal expansion branches, the first expansion switching tube in the even-numbered one of the M longitudinal expansion branches, the third switching tube Q3, the eighth switching tube Q8, the tenth switching tube Q10, the twelfth switching tube Q12, and enters the time period T3. During the period T3, the energy stored in the second capacitor C2 is discharged through the second switching tube Q2, the ninth switching tube Q9, the fourth switching tube Q4, the first inductor L1, the first expansion capacitor CAM in the mth longitudinal expansion branch 20aM, the stored energy is transferred to the sixth capacitor C6, and the first inductor L1 and the first expansion capacitor CAM in the mth longitudinal expansion branch 20aM are charged. The voltage at the first end of the second capacitor C2 and the first end of the first inductor L1 are equal to Vin/2. The second inductor L2 is continuously discharged through the fourth switching tube Q4, the second expansion switching tube QBM in the mth longitudinal expansion branch 20aM, the ninth switching tube Q9, and the second expansion capacitor CB (M-1) in the (M-1) th longitudinal expansion branch 20a (M-1) to transfer its stored energy to the sixth capacitor C6 and charge the second expansion capacitor CB (M-1) in the (M-1) th longitudinal expansion branch 20a (M-1). The first expansion capacitor CA (M-1) in the (M-1) th longitudinal expansion branch 20a (M-1) charges the second expansion capacitor CB (M-1) in the (M-1) th longitudinal expansion branch 20a (M-1) through the second expansion switching tube QB (M-1) and the thirteenth switching tube Q13 in the (M-1) th longitudinal expansion branch 20a (M-1), and outputs the stored energy to the sixth capacitor C6. The first expansion capacitor CA (M-1) in the (M-1) th longitudinal expansion branch 20a (M-1) transfers the stored energy to the sixth capacitor C6 and charges the first expansion capacitor CA (M-2) in the (M-2) th longitudinal expansion branch 20a (M-2) through the first expansion switch tube QA (M-1), the ninth switch tube Q9, the thirteenth switch tube Q13 and the first expansion capacitor CA (M-2) in the (M-2) th longitudinal expansion branch 20a (M-1). The second extension capacitor CB (M-2) in the (M-2) th longitudinal extension leg 20a (M-2) discharges through the second extension switching tube QB (M-2), … … in the (M-2) th longitudinal extension leg 20a (M-2), the second extension switching tube QB4 in the fourth longitudinal extension leg 20a4, the second extension switching tube QB2 in the second longitudinal extension leg 20a2, the ninth switching tube Q9, the thirteenth switching tube Q13. The fifth capacitor C5 and the seventh capacitor C7 also simultaneously transfer the stored energy to the sixth capacitor C6, and no energy is transferred between the input power Vin and the voltage output terminal Vout. The voltage at the second end of the first inductor L1 is equal to (m+2) Vout and the voltage at the second end of the second inductor L2 is equal to (m+1) Vout. The system load connected across the sixth capacitor C6 draws power from the sixth capacitor C6.

The period T3 ends with turning off the second switching transistor Q2 and turning on the third switching transistor Q3. And, the remaining switching tubes remain in the switching state for the period T3, and enter a fourth period T4 in one operation cycle. During time period T4, there is no energy transfer between the input and the output. The first inductor L1 discharges through the third switching tube Q3, the ninth switching tube Q9, the first expansion capacitor CAM in the mth longitudinal expansion branch 20aM to transfer its stored energy to the sixth capacitor C6 and charges the first expansion capacitor CAM in the mth longitudinal expansion branch 20 aM. The voltage at the first end of the first inductor L1 is zero. The charge and discharge states of the rest of the inductance and the flying capacitor and the voltage of the rest of the terminal points are consistent with the T3 interval. The system load connected across the sixth capacitance C6 continuously draws energy from the sixth capacitance C6. The switching cycle is repeated by re-entering the period T1.

As described above, in the time period T1 and the time period T2, the voltages at the second end of the first inductor L1 and the second end of the second inductor L2 are (m+1) ×vout and (m+2) ×vout, respectively. In the time period T3 and the time period T4, the voltages at the second end of the first inductor L1 and the second end of the second inductor L2 are (m+2) ×vout and (m+1) ×vout, respectively. The average voltage of the second end of the first inductor L1 and the second end of the second inductor L2 is:

The following equation can be obtained by combining equations (5) and (8):

therefore, the output voltage of the voltage conversion circuit 200 at this time is:

the maximum output voltage of the voltage conversion circuit 200 is:

for example, if vin=33v and m=1, vout_max=3.3v, so that a bus voltage of 3.3V can be obtained.

It is noted that the voltage waveform at the first end of the second inductor L2 of the first inductor L1 is maintained as a periodic pulse signal having a magnitude of half the voltage of the input power Vin (Vin/2) regardless of how many longitudinal extension units are added, and the duty cycle of the two pulse signals is the same but the phases are opposite. Two periodic pulse signals respectively generate two current sources on the second inductor L2 of the first inductor L1 to supply current for the second conversion branch 202.

Moreover, regardless of the addition of several longitudinally extending branches in the second switching leg 202, during a portion of the switching cycle of the second switching leg 202, the current on the first inductor L1 charges the fifth capacitor C5 (i.e., the storage capacitor) and discharges the seventh capacitor C7 (i.e., the storage capacitor) to the output capacitor (sixth capacitor C6) by turning on a portion of the switching tube. And during another part of the switching cycle of the second converting branch 202, the current on the second inductor L2 charges the seventh capacitor C7 and discharges the fifth capacitor C5 to the output capacitor (sixth capacitor C6) by turning on another part of the switching tube. Thus, the second conversion branch 202 converts the two input currents into a voltage at the voltage output terminal Vout.

In an embodiment, the first conversion branch 201 further includes a fourteenth switching tube, a fifteenth switching tube, and an eighth capacitor. The third end of the fourteenth switching tube is connected with the first end of the first capacitor. The second end of the fourteenth switching tube is connected with the third end of the fifteenth switching tube and the first end of the eighth capacitor respectively. The second end of the eighth capacitor is connected with the first end of the first inductor. The second end of the fifteenth switching tube is connected with the first end of the second inductor. The controller is connected with the first end of the fourteenth switching tube and the first end of the fifteenth switching tube respectively.

Referring to fig. 11, fig. 11 illustrates adding a fourteenth switching transistor Q14, a fifteenth switching transistor Q15 and an eighth capacitor C8 to the circuit structure shown in fig. 4. Of course, the circuit structures shown in fig. 3, 9 and 10 can be added with the fourteenth switching tube Q14, the fifteenth switching tube Q15 and the eighth capacitor C8, so as to expand the first conversion branch 201 from single phase to double phase.

As shown in fig. 11, the third terminal of the fourteenth switching transistor Q14 is connected to the first terminal of the first capacitor C1. The second end of the fourteenth switching tube Q14 is connected to the third end of the fifteenth switching tube Q15 and the first end of the eighth capacitor C8, respectively. The second end of the eighth capacitor C8 is connected to the first end of the first inductor L1. A second terminal of the fifteenth switching transistor Q15 is connected to a first terminal of the second inductor L2. The controller is connected to the first end of the fourteenth switching tube Q14 and the first end of the fifteenth switching tube Q15, respectively.

The embodiment of the present application further provides a control manner when the first conversion branch 201 further includes the fourteenth switching tube Q14, the fifteenth switching tube Q15 and the eighth capacitor C8. Specifically, the controller is further configured to: controlling the combination of the first switching tube Q1 and the fifteenth switching tube Q15 and the combination of the second switching tube Q2 and the fourteenth switching tube Q14 to be alternately turned on and turned off by 180 degrees in a phase-staggered manner with the same duty ratio; controlling the third switching tube Q3 to be switched on and off in a complementary manner with the second switching tube Q2; the fourth switching transistor Q4 is controlled to be turned on and off in a complementary manner to the fifteenth switching transistor Q15.

The operation of the circuit shown in fig. 11 will be described in detail below with reference to fig. 12. As shown in fig. 12, the abscissa indicates time. The curve L51 is a control signal for controlling the first switching tube Q1 and the fifteenth switching tube Q15; curve L52 is the control signal controlling the fourth switching tube Q4; curve L53 is a control signal for controlling the second switching transistor Q2 and the fourteenth switching transistor Q14; curve L54 is a control signal for controlling the third switching tube Q3; curve L55 is the voltage at the first end of the second capacitor C2; curve L56 is the voltage at the first end of the second inductor L2; curve L57 is the voltage at the first end of the first inductor L1. Wherein the curve L51 is complementary to the curve L52. Curve L53 and curve L54 are complementary.

In particular, the first conversion branch 201 operates in two phases. Assuming that both the first conversion leg 201 and the second conversion leg 202 operate at the same switching frequency, the operation of the voltage conversion circuit 200 shown in fig. 11 is described as follows: likewise, one switching cycle of the voltage conversion circuit 200 has four periods: t1= [ T0, T1, t2= [ T1, t0+ts/2], t3= [ t0+ts/2, T2] and t4= [ T2, t0+ts ]. In the time period T1, the first switching tube Q1, the third switching tube Q3, the eighth switching tube Q8, the tenth switching tube Q10, the fifteenth switching tube Q15, the twelfth switching tube Q12 are turned on, and the remaining power switches are turned off. The second capacitor C2, the seventh capacitor C7 and the second inductor L2 are charged by the input power Vin through the first switching tube Q1, the twelfth switching tube Q12 and the sixth capacitor C6. The eighth capacitor C8 discharges to transfer its stored energy to the second inductor L2, the seventh capacitor C7 and the sixth capacitor C6. The first inductor L1 and the fifth capacitor C5 are discharged through the third switching tube Q3, the eighth switching tube Q8 and the tenth switching tube Q10 to transfer their stored energy to the sixth capacitor C6. During the period T1, energy is transferred between the input power source Vin and the voltage output terminal Vout. The system load connected to the voltage output Vout draws power from the sixth capacitance C6.

The period T1 ends by turning off the first switching tube Q1, the fifteenth switching tube Q15, and turning on the fourth switching tube Q4. And, the remaining switching tubes remain in the switching state for the period T1, and enter the second period T2 in one operation cycle. In the period T2, the first inductor L1 and the fifth capacitor C5 are continuously discharged, and the stored energy is transferred to the sixth capacitor C6 through the third switching tube Q3, the eighth switching tube Q8 and the tenth switching tube Q10. The current of the second inductor L2 continuously charges the sixth capacitor C6 through the seventh capacitor C7, the fourth switching tube Q4 and the twelfth switching tube Q12, and the energy stored in the second capacitor C2 and the eighth capacitor C8 remains unchanged. During the period T2, the input power Vin and the voltage output Vout have no energy transfer. The system load connected to the voltage output Vout takes power from the sixth capacitor C6.

At the end of the period T2, the fourteenth switching tube Q14, the second switching tube Q2, the ninth switching tube Q9, the eleventh switching tube Q11, the thirteenth switching tube Q13 are turned on, and the third switching tube Q3, the eighth switching tube Q8, the tenth switching tube Q10, the twelfth switching tube Q12 are turned off. The first switching tube Q1 and the fourth switching tube Q4 maintain the switching state in the period T2, and enter a third period T3 in one operation cycle. In the period T3, the input power Vin charges the first inductor L1, the eighth capacitor C8, and the fifth capacitor C5 through the fourteenth switching transistor Q14, the ninth switching transistor Q9, and the sixth capacitor C6. During time period T3, energy is transferred from the input power source Vin to the voltage output Vout. The energy stored in the second capacitor C2 is discharged to the first inductor L1, the fifth capacitor C5 and the sixth capacitor C6 through the second switching tube Q2, the ninth switching tube Q9 and the fourth switching tube Q4. The system load connected to the voltage output Vout takes power from the sixth capacitor C6.

The period T3 ends by turning off the fourteenth switching tube Q14, the second switching tube Q2, and turning on the third switching tube Q3. And, the remaining switching tubes remain in the switching state for the period T3, and enter a fourth period T4 in one operation cycle. During the period T4, no power is transferred between the input power Vin and the voltage output Vout. The energy stored in the second capacitor C2 and the eighth capacitor C8 remains unchanged. The energy stored in the first inductor L1 is discharged to the fifth capacitor C5 and the sixth capacitor C6 through the third switching tube Q3 and the ninth switching tube Q9. The energy stored in the second inductor L2 is discharged to the sixth capacitor C6 through the fourth switching tube Q4 and the thirteenth switching tube Q13. The energy stored in the seventh capacitor C7 is discharged to the sixth capacitor C6 through the eleventh and thirteenth switching transistors Q11 and Q13. When T4 ends, the switching cycle repeats.

It should be noted that in the above process energy is transferred between the input power source Vin and the voltage output terminal Vout for two periods of time (T1 and T3) within one switching cycle. Whereas the voltage conversion circuit 200 of fig. 4 has energy transfer between the input power Vin and the voltage output Vout for only one period of time (T1) within one switching cycle. Therefore, such an operation of the voltage conversion circuit 200 shown in fig. 11 can reduce the rms currents of the first switching transistor Q1 and the fourteenth switching transistor Q14 and the rms current of the first capacitor C1. The reduced rms current results in less power dissipation associated with the first switching tube Q1, the fourteenth switching tube Q14 and the first capacitor C1. The voltage conversion circuit 200 of fig. 4 is identical to the rest of the operations of the voltage conversion circuit 200 shown in fig. 11.

The embodiment of the present application further provides another control manner when the first conversion branch 201 is expanded into two phases by adding the fourteenth switching tube Q14, the fifteenth switching tube Q15 and the eighth capacitor C8. Specifically, the controller is further configured to: the first switching tube Q1, the fifteenth switching tube Q15, the second switching tube Q2 and the fourteenth switching tube Q14 are controlled to be alternately turned on and turned off by 90 degrees in a phase-staggered manner with the same duty ratio; the third switching tube Q3 is controlled to be turned off when the second switching tube Q2 or the fourteenth switching tube Q14 is turned on, and turned on when the second switching tube Q2 and the fourteenth switching tube Q14 are both turned off; the fourth switching tube Q4 is controlled to be turned off when the first switching tube Q1 or the fifteenth switching tube Q15 is turned on, and turned on when both the first switching tube Q1 and the fifteenth switching tube Q15 are turned off.

The above control manner of controlling the first switching tube Q1, the fifteenth switching tube Q15, the second switching tube Q2 and the fourteenth switching tube Q14 to be sequentially turned on ensures that only one current path including the second capacitor C2 or the eighth capacitor C8 provides current to the first inductor L1 and the second inductor L2 at the first end of the first inductor L1 and the second end of the second inductor L2, thereby avoiding discharge surge current between capacitors in a plurality of current paths and charge transfer loss caused by the discharge surge current.

The operation principle of the circuit shown in fig. 11 will be described in detail with reference to fig. 13. As shown in fig. 13, the abscissa indicates time. Wherein, the curve L61 is a control signal for controlling the first switching tube Q1; curve L62 is a control signal for controlling the second switching tube Q2; curve L63 is a control signal for controlling the fourteenth switching transistor Q14; curve L64 is a control signal for controlling the fifteenth switching transistor Q15; curve L65 is a control signal for controlling the fourth switching tube Q4; curve L66 is the control signal controlling the third switching tube Q3; curve L67 is the voltage at the first end of the second capacitor C2; curve L68 is the voltage at the first end of the second inductor L2; curve L69 is the voltage at the first end of the first inductor L1.

Specifically, focusing on waveforms of key nodes in the first conversion branch 201, the operation of the voltage conversion circuit 200 shown in fig. 11 under the control method of sequential conduction is described as follows: for ease of discussion, the same four time periods as within the switching period Ts of the voltage conversion circuit 200 in fig. 5 are maintained: t1= [ T0, T1, t2= [ T1, t0+ts/2], t3= [ t0+ts/2, T2] and t4= [ T2, t0+ts ]. In fact, since the control method of sequentially turning on the fourteenth switching transistor Q14 and the fifteenth switching transistor Q15 are controlled to be turned off in the first period Ts, the control method and waveforms of the nodes are identical to those of the single-phase voltage converting circuit shown in fig. 5, and will not be described herein. In the second Ts period (including four periods: period T5, period T6, period T7, and period T8) of the sequential conduction control method, the sequential conduction control method controls the first switching transistor Q1 and the second switching transistor Q2 to remain turned off, and the operation of each switching transistor in the second Ts period is completed by the third switching transistor Q3, the fourth switching transistor Q4, the fourteenth switching transistor Q14, and the fifteenth switching transistor Q15 in a similar manner to the operation of the single-phase voltage conversion circuit shown in fig. 5. Specifically, in the second Ts period, the third switching tube Q3 and the fourth switching tube Q4 are turned on and off in the same control method in the first period, and the fourteenth switching tube Q14 and the fifteenth switching tube Q15 are turned on and off in the same control timing sequence as the first switching tube Q1 and the second switching tube Q2, respectively. After the second Ts period is over, the control method of sequential conduction repeats the control method of the first two Ts periods.

In this way, since the voltage signals generated by the control method of sequential conduction at the first ends of the first inductor L1 and the second inductor L2 are identical to the voltage signals implemented by the control method of the dual-phase circuit structure at the same node, both are periodic voltage pulse signals with the amplitude Vin/2, so that the inductor currents generated by the first conversion branch 201 and input by the two current sources serving as the second conversion branch 202 are also identical. The voltage/current waveforms corresponding to the nodes in the second conversion leg 202 are also the same. The control mode of sequential conduction only avoids the situation that a plurality of current paths simultaneously supply current for the inductor in the original biphase circuit control method while keeping the same output of the first conversion branch 201, and reduces the charge transfer loss between the capacitors in the first conversion branch 201.

It should be noted that in the above-described control method of sequential conduction, the period in which the switching transistors are turned on and off in the first conversion branch 201 is two Ts periods, so that the equivalent switching frequencies of the first switching transistor Q1, the second switching transistor Q2, the fourteenth switching transistor Q14 and the fifteenth switching transistor Q15 are halved, and if the period of the first conversion branch 201 is defined by a long period Tr consisting of two Ts periods, the first switching transistor Q1, the second switching transistor Q2, the fourteenth switching transistor Q14 and the fifteenth switching transistor Q15 are sequentially turned on at 90 degrees of the same duty cycle staggered phase Tr period, and the duty cycle of the corresponding control signal is also smaller than 1/4. In the control method of sequential conduction, the first switching transistor Q1, the second switching transistor Q2, the fourteenth switching transistor Q14, and the fifteenth switching transistor Q15 may be sequentially turned on once in one Tr period in any turn-on order. Since the periodic pulses formed at the first ends of the inductor L1 and the inductor L3 corresponding to the different turn-on sequences are identical.

Moreover, regardless of which of the above two control methods is adopted in the first conversion branch 201, during a portion of the switching cycle of the second conversion branch 202, the current on the first inductor L1 charges the fifth capacitor C5 (i.e., the energy storage capacitor) through the turned-on ninth switching transistor Q9, and during another portion of the switching cycle of the second conversion branch 202, the fifth capacitor C5 (i.e., the energy storage capacitor) discharges to the output capacitor (sixth capacitor C6) through the turned-on eighth switching transistor Q8 and the tenth switching transistor Q10. Likewise, during a portion of the switching cycle of the second switching leg 202, the current on the second inductor L2 charges the seventh capacitor C7 (i.e., the storage capacitor) through the turned-on twelfth switching tube Q12, and during another portion of the switching cycle of the second switching leg 202, the seventh capacitor C7 (i.e., the storage capacitor) discharges to the output capacitor (sixth capacitor C6) through the turned-on eleventh switching tube Q11 and thirteenth switching tube Q13. Thus, the second conversion branch 202 converts the two input currents into a voltage at the voltage output terminal Vout.

The voltage conversion circuit 200 can also implement multi-phase parallel operation to output a larger current by adding a lateral extension branch. In an embodiment, the first converting branch 201 further includes a sixteenth switching tube, a seventeenth switching tube, and a ninth capacitor. The third end of the sixteenth switching tube is connected with the first end of the first capacitor. The second end of the sixteenth switching tube is connected with the third end of the seventeenth switching tube and the first end of the ninth capacitor respectively. The second end of the seventeenth switching tube is connected with the first end of the second inductor. The controller is connected with the first end of the sixteenth switching tube and the first end of the seventeenth switching tube respectively.

The voltage conversion circuit 200 further includes a plurality of cascaded a lateral expansion branches, where each lateral expansion branch includes a third expansion switching tube, a fourth expansion switching tube, a fifth expansion switching tube, a sixth expansion switching tube, a seventh expansion switching tube, an eighth expansion switching tube, a third expansion capacitor, a fourth expansion capacitor, and a first expansion inductor. Wherein A is an integer not less than 1.

The third end of a third expansion switching tube in the transverse expansion branch is connected with the first end of the first capacitor, the second end of the third expansion switching tube in the transverse expansion branch is connected with the third end of a fourth expansion switching tube in the transverse expansion branch and the first end of a third expansion capacitor in the transverse expansion branch, the second end of the fourth expansion switching tube in the transverse expansion branch is connected with the first end of a first expansion inductor in the transverse expansion branch and the third end of a fifth expansion switching tube in the transverse expansion branch, the second end of the first expansion inductor in the transverse expansion branch is connected with the first end of a fourth expansion capacitor in the transverse expansion branch and the third end of a sixth expansion switching tube in the transverse expansion branch, the second end of the sixth expansion switching tube in the transverse expansion branch is connected with the third end of a seventh expansion switching tube in the transverse expansion branch and the first end of a fourth capacitor in the transverse expansion branch, and the second end of a fourth expansion switching tube in the transverse expansion branch are connected with the third end of a fifth expansion switching tube in the transverse expansion branch and the fourth end of a fourth expansion tube in the transverse expansion branch, and the fourth end of a fifth expansion tube in the transverse expansion branch are connected with the fourth end of a fourth expansion tube in the transverse expansion branch respectively.

When a=1, the second end of the third expansion capacitor in the lateral expansion branch is connected to the first end of the first inductor, and the second end of the ninth capacitor is connected to the first end of the first expansion inductor in the lateral expansion branch.

When B is less than or equal to 1 and less than A, the second end of the third expansion capacitor in the B-th lateral expansion branch circuit in the A-th lateral expansion branch circuit is connected with the first end of the first expansion inductor in the (B+1) -th lateral expansion branch circuit in the A-th lateral expansion branch circuit, the second end of the third expansion capacitor in the A-th lateral expansion branch circuit is connected with the first end of the first inductor, and the second end of the ninth capacitor is connected with the first end of the first expansion inductor in the first lateral expansion branch circuit in the A-th lateral expansion branch circuit.

Referring to fig. 14, fig. 14 illustrates a structure in which a sixteenth switching tube, a seventeenth switching tube, a ninth capacitor and a number of lateral expansion branches are added to the circuit structure illustrated in fig. 4.

As shown in fig. 14, the third terminal of the sixteenth switching tube Q16 is connected to the first terminal of the first capacitor C1. The second end of the sixteenth switching tube Q16 is connected to the third end of the seventeenth switching tube Q17 and the first end of the ninth capacitor C9, respectively. A second terminal of the seventeenth switching transistor Q17 is connected to the first terminal of the second inductor L2. The controller is connected to the first end of the sixteenth switching tube Q16 and the first end of the seventeenth switching tube Q17, respectively.

The voltage conversion circuit 200 further includes a number a of laterally extending branches that are cascaded in sequence. The a lateral expansion branches include a first lateral expansion branch 20b1, a second lateral expansion branch 20b2 …, and an a-th lateral expansion branch 20bA. Each transverse expansion branch comprises a third expansion switching tube, a fourth expansion switching tube, a fifth expansion switching tube, a sixth expansion switching tube, a seventh expansion switching tube, an eighth expansion switching tube, a third expansion capacitor, a fourth expansion capacitor and a first expansion inductor. Wherein A is an integer not less than 1. For example, the first lateral expansion branch 20b1 includes a third expansion switching tube QC1, a fourth expansion switching tube QD1, a fifth expansion switching tube QE1, a sixth expansion switching tube QF1, a seventh expansion switching tube QG1, an eighth expansion switching tube QH1, a third expansion capacitor CC1, a fourth expansion capacitor CD1, and a first expansion inductor LC1.

The third end of the third expansion switching tube in the transverse expansion branch is connected with the first end of the first capacitor C1. The second end of the third expansion switching tube in the transverse expansion branch is respectively connected with the third end of the fourth expansion switching tube in the transverse expansion branch and the first end of the third expansion capacitor in the transverse expansion branch. The second end of the fourth expansion switching tube in the transverse expansion branch is respectively connected with the first end of the first expansion inductor in the transverse expansion branch and the third end of the fifth expansion switching tube in the transverse expansion branch. The second end of the first expansion inductor in the transverse expansion branch is respectively connected with the first end of the fourth expansion capacitor in the transverse expansion branch and the third end of the sixth expansion switching tube in the transverse expansion branch. The second end of the sixth expansion switching tube in the transverse expansion branch is respectively connected with the third end of the seventh expansion switching tube in the transverse expansion branch and the first end of the sixth capacitor C6. The second end of the seventh expansion switching tube in the transverse expansion branch is respectively connected with the third end of the eighth expansion switching tube in the transverse expansion branch and the second end of the fourth expansion capacitor in the transverse expansion branch. The second end of the fifth expansion switching tube in the transverse expansion branch is grounded.

Taking the first lateral expansion branch 20b1 as an example, a third end of the third expansion switching tube QC1 in the first lateral expansion branch 20b1 is connected to a first end of the first capacitor C1. The second end of the third expansion switching tube QC1 in the first lateral expansion branch 20b1 is connected to the third end of the fourth expansion switching tube QD1 in the first lateral expansion branch 20b1 and the first end of the third expansion capacitor CC1 in the first lateral expansion branch 20b1, respectively. The second end of the fourth extension switching tube QD1 in the first lateral extension branch 20b1 is connected to the first end of the first extension inductance LC1 in the first lateral extension branch 20b1 and the third end of the fifth extension switching tube QE1 in the first lateral extension branch 20b1, respectively. The second end of the first expansion inductance LC1 in the first lateral expansion branch 20b1 is connected to the first end of the fourth expansion capacitance CD1 in the first lateral expansion branch 20b1 and the third end of the sixth expansion switching tube QF1 in the first lateral expansion branch 20b1, respectively. The second end of the sixth expansion switching tube QF1 in the first lateral expansion branch 20b1 is connected to the third end of the seventh expansion switching tube QG1 in the first lateral expansion branch 20b1 and the first end of the sixth capacitor C6, respectively. The second end of the seventh expansion switching tube QG1 in the first lateral expansion branch 20b1 is connected to the third end of the eighth expansion switching tube QH1 in the first lateral expansion branch 20b1 and the second end of the fourth expansion capacitor CD1 in the first lateral expansion branch 20b1, respectively. The second ends of the fifth expansion switching tubes QE1 of the first lateral expansion branch 20b1 and the second ends of the eighth expansion switching tubes QH1 in the first lateral expansion branch 20b1 are all grounded.

When a=1, the second end of the third extension capacitor CC1 in the first lateral extension branch 20b1 is connected to the first end of the first inductor L1, and the second end of the ninth capacitor C9 is connected to the first end of the first extension inductor LC1 in the first lateral extension branch 20b 1. The laterally expanded voltage conversion circuit is a three-phase voltage conversion circuit.

When B is less than or equal to 1 and less than A, the second end of the third expansion capacitor in the B-th lateral expansion branch circuit in the A-th lateral expansion branch circuit is connected with the first end of the first expansion inductor in the (B+1) -th lateral expansion branch circuit in the A-th lateral expansion branch circuit, the second end of the third expansion capacitor in the A-th lateral expansion branch circuit is connected with the first end of the first inductor L1, and the second end of the ninth capacitor C9 is connected with the first end of the first expansion inductor in the first lateral expansion branch circuit in the A-th lateral expansion branch circuit. Taking b=1 as an example, the second end of the third expansion capacitor CC1 in the first lateral expansion branch 20B1 is connected to the first end of the first expansion inductor LC2 in the second lateral expansion branch 20B2, the second end of the third expansion capacitor CCA in the a-th lateral expansion branch 20bA is connected to the first end of the first inductor L1, and the second end of the ninth capacitor C9 is connected to the first end of the first expansion inductor LC1 in the first lateral expansion branch 20B 1. The laterally expanded voltage conversion circuit is an (a+2) phase voltage conversion circuit.

For the upper half of the circuit structure shown in fig. 14, the upper half includes the first conversion branch 201, the third extension switch tube, the fourth extension switch tube, the fifth extension switch tube, the third extension capacitor and the first extension inductance in each lateral extension branch. The upper half of the circuit configuration shown in fig. 14 constitutes a new multiphase first conversion branch 201. The present application also provides two different ways of controlling the embodiments of the multi-phase first conversion branch 201.

Taking a three-phase voltage conversion circuit (i.e. when a=1) as an example, one control mode specifically comprises the following implementation processes: the controller is further configured to: the combination of the first switching tube Q1 and the seventeenth switching tube Q17, the combination of the sixteenth switching tube Q16 and the fourth expansion switching tube QD1 in the first lateral expansion branch 20b1, and the combination of the third expansion switching tube QC1 and the second switching tube Q2 in the first lateral expansion branch 20b1 are controlled to be alternately turned on and off with the same duty cycle by 120 degrees; the third switching tube Q3 is controlled to be turned on and off in a manner complementary to the second switching tube Q2, the fourth switching tube Q4 is controlled to be turned on and off in a manner complementary to the seventeenth switching tube Q17, and the fifth expansion switching tube QE1 in the first lateral expansion branch 20b1 is controlled to be turned on and off in a manner complementary to the fourth expansion switching tube QDA in the first lateral expansion branch 20b 1.

By the control method, three periodic pulse signals with the amplitude being half of the voltage of the input power Vin (i.e. Vin/2) can be generated at the first end of the first inductor L1, the first end of the second inductor L2 and the first end of the first expansion inductor LC1 in the first transverse expansion branch 20b1, and the three periodic pulse signals are out of phase by 120 degrees. While three periodic pulse signals respectively generate three current sources on the first inductor L1, the second inductor L2 and the extension inductor LC1 in the first lateral extension branch 20b1 to supply current to the three-phase second conversion branch 202. The three-phase second switching leg 202 here comprises the second switching leg 202 in fig. 14 and the fifth extension switching tube QF1 in the first lateral extension leg 20b1, the sixth extension switching tube QG1 in the first lateral extension leg 20b1 and the seventh extension switching tube QH1 in the first lateral extension leg 20b1, and the fourth extension capacitance CD1 in the first lateral extension leg 20b 1. Similar to the previous embodiment, the controller controls the switching transistors in the three-phase second converting branch 202 to be turned on and off periodically to generate the voltage of the voltage output terminal Vout based on the currents provided by the three current sources.

In the (A+2) phase voltage conversion circuit, when 1 is less than or equal to B and less than A, controlling a combination of a first switching tube Q1 and a seventeenth switching tube Q17, a combination of a sixteenth switching tube Q16 and a fourth expansion switching tube QD1 of a first transverse expansion branch 20B1 in A transverse expansion branches, a combination of a third expansion switching tube of a B transverse expansion branch in A transverse expansion branches and a fourth expansion switching tube of a (B+1) th transverse expansion branch in A transverse expansion branches and a combination of a third expansion switching tube QCA and a second switching tube Q2 in A transverse expansion branch 20bA in A transverse expansion branches to be alternately turned on and off at 360/(2+A) degrees in a staggered phase with the same duty ratio; the third switching tube Q3 is controlled to be turned on and off in a manner complementary to the second switching tube Q2, the fourth switching tube Q4 is controlled to be turned on and off in a manner complementary to the seventeenth switching tube Q17, and the fifth expansion switching tube in each of the A transverse expansion branches is controlled to be turned on and off in a manner complementary to the fourth expansion switching tube in the same transverse expansion branch.

By the control method, the first end of the first inductor L1, the first end of the second inductor L2 and the first end of each of the A lateral expansion branches can generate (A+2) periodic pulse signals with the amplitude being half of the voltage of the input power supply Vin (namely Vin/2), and the phase of two adjacent periodic pulse signals in the (A+2) periodic pulse signals is in 360/(2+A) degrees. While a+2 periodic pulse signals respectively generate (a+2) current sources on the first inductor L1, the second inductor L2 and each of the a lateral extension branches to supply current to the second conversion branch 202 of the (a+2) phase. The second switching leg 202 of the (a+2) phase here includes the second switching leg 202 and each of the fifth extension switching tube, sixth extension switching tube, seventh extension switching tube, and fourth extension capacitance of the a lateral extension legs 20b1 in fig. 14. Similar to the previous embodiment, the controller controls the switching transistors in the second switching leg 202 of the (a+2) phase to be periodically turned on and off to generate the voltage at the voltage output terminal Vout based on the currents provided by the three current sources.

Taking a three-phase voltage conversion circuit (i.e. when a=1) as an example, the multiphase voltage conversion circuit shown in fig. 14 may also adopt a control mode of sequential conduction, and the specific implementation process is as follows: the controller is further configured to: the first switching tube Q1, the seventeenth switching tube Q17, the sixteenth switching tube Q16, the fourth expansion switching tube QD1 in the first transverse expansion branch 20b1, the third expansion switching tube QC1 in the first transverse expansion branch 20b1 and the first switching tube Q1 are controlled to be alternately turned on and turned off at the same duty ratio by 60 degrees; the third switching tube Q3 is controlled to be turned off when the second switching tube Q2 or the third expansion switching tube QC1 in the first transverse expansion branch 20b1 is turned on, and turned on when the second switching tube Q2 and the third expansion switching tube QC1 in the first transverse expansion branch 20b1 are both turned off; controlling the fourth switching tube Q4 to be turned off when the seventeenth switching tube Q17 or the first switching tube Q1 is turned on, and turned on when both the seventeenth switching tube Q17 and the first switching tube Q1 are turned off; the fifth extension switching tube QE1 in the first lateral extension branch 20b1 is controlled to be turned off when the sixteenth switching tube Q16 or the fourth extension switching tube QD1 in the first lateral extension branch 20b1 is turned on, and turned on when both the sixteenth switching tube Q16 and the fourth extension switching tube QD1 in the first lateral extension branch 20b1 are turned off.

Similarly, by the above-mentioned control method of sequential conduction, three periodic pulse signals with an amplitude half the voltage of the input power Vin (i.e. Vin/2) can be generated at the first end of the first inductor L1, the first end of the second inductor L2 and the first end of the extension inductor LC1 in the first lateral extension branch 20b1, and the three periodic pulse signals are out of phase by 120 degrees. Therefore, as described above, the control method of sequential conduction has no effect on the output of the three-phase voltage conversion circuit 200, but can reduce the switching loss and the charge transfer loss of the first conversion branch 201 at the time of low current output.

In the (A+2) phase voltage conversion circuit, when B is less than or equal to 1 and less than A, the first switching tube Q1, the seventeenth switching tube Q17, the sixteenth switching tube Q16, the third expansion switching tube in each of the A transverse expansion branches, the fourth expansion switching tube in each of the A transverse expansion branches and the second switching tube Q2 are controlled to be alternately turned on and off at 180/(2+A) degrees of the same duty ratio phase stagger; the third switching tube Q3 is controlled to be turned off when the third expansion switching tube QCA in the A-th transverse expansion branch 20bA in the second switching tube Q2 or the A-th transverse expansion branch is turned on, and turned on when the third expansion switching tube QCA in the A-th transverse expansion branch 20bA in the second switching tube Q2 and the A-th transverse expansion branch is turned off; controlling the fourth switching tube Q4 to be turned off when the seventeenth switching tube Q17 or the first switching tube Q1 is turned on, and turned on when both the seventeenth switching tube Q17 and the first switching tube Q1 are turned off; controlling the fifth expansion switching tube QE1 in the first one of the a lateral expansion branches 20b1 to be turned off when the sixteenth switching tube Q16 or the fourth expansion switching tube QD1 in the first one of the a lateral expansion branches 20b1 is turned on, and to be turned on when both the sixteenth switching tube Q16 and the fourth expansion switching tube QD1 in the first one of the a lateral expansion branches 20b1 are turned off; the fifth expansion switching tube in the (B+1) th transverse expansion branch of the A transverse expansion branches is controlled to be turned off when the third expansion switching tube in the B th transverse expansion branch of the A transverse expansion branches or the fourth expansion switching tube in the (B+1) th transverse expansion branch of the A transverse expansion branches is turned on, and the third expansion switching tube in the B th transverse expansion branch of the A transverse expansion branches and the fourth expansion switching tube in the (B+1) th transverse expansion branch of the A transverse expansion branches are turned off.

Similarly, by the control method, the first end of the first inductor L1, the first end of the second inductor L2 and the first end of each of the a lateral extension branches may generate (a+2) periodic pulse signals with an amplitude being half of the voltage of the input power Vin (i.e. Vin/2), and the two adjacent periodic pulse signals in the (a+2) periodic pulse signals are out of phase 360/(2+A). Therefore, as described above, the control method of sequential conduction has no effect on the output of the three-phase voltage conversion circuit 200, but can reduce the switching loss and the charge transfer loss of the first conversion branch 201 at low current output.

For the lower half of the circuit structure shown in fig. 14, the lower half includes the second conversion branch 202, the sixth extension switching tube, the seventh extension switching tube, the eighth extension switching tube, and the fourth extension capacitor in each lateral extension branch. The embodiment of the application also provides a control mode. The specific implementation process is as follows: the controller is further configured to: controlling the combination of the eighth switching tube Q8 and the tenth switching tube Q10 and the ninth switching tube Q9 to be alternately switched on and off in a complementary mode; controlling the combination of the eleventh switching tube Q11 and the thirteenth switching tube Q13 and the twelfth switching tube Q12 to be alternately switched on and off in a complementary mode; the combination of the sixth expansion switching tube and the eighth expansion switching tube in each of the A transverse expansion branches is controlled to be alternately switched on and switched off in a complementary mode with the seventh expansion switching tube in the same transverse expansion branch. The eighth switching tube Q8, the eleventh switching tube Q11, and the sixth expansion switch in each of the a lateral expansion branches are turned on and off at the switching frequency of the second switching branch 202 and the same duty cycle phase-shifting 360/(2+A). In the circuit structure shown in fig. 14, by adding the lateral extension branch, the first conversion branch 201 with more phases can be obtained in a phase-staggered parallel manner, which is helpful for improving the output current capability of the whole voltage conversion circuit 200 and reducing the output voltage ripple. Moreover, the automatic current sharing of the current on each inductor of the multiphase circuit can be realized through capacitive coupling (comprising a second capacitor C2, a ninth capacitor C9 and a third expansion capacitor in each lateral expansion branch) between each phase circuit and the next phase circuit, and the efficiency improvement is facilitated.

In some embodiments, the switching frequency of the lower half of the circuit structure shown in fig. 14 (i.e., the second switching leg 202 that is multi-phase) is not lower than the switching frequency of the upper half of the circuit structure shown in fig. 14 (i.e., the first switching leg 201 that is multi-phase). In other embodiments, the multiphase second switching leg 202 shown in fig. 14 may operate at a 50% duty cycle, i.e., the on time of each switching tube is the same. In other embodiments, the multiphase second switching leg 202 of fig. 14 may be used to provide a step-down ratio of the voltage conversion circuit 200 by adding a multiphase longitudinal extension leg in the extension method of fig. 9 and 10. The embodiment of the application also provides an electronic device, which comprises the voltage conversion circuit 200 in any embodiment of the application.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the application, the steps may be implemented in any order, and there are many other variations of the different aspects of the application as described above, which are not provided in detail for the sake of brevity; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.

Claims

1. A voltage conversion circuit, comprising:

2. The voltage conversion circuit according to claim 1, wherein the second conversion branch is a switched capacitor conversion circuit and the second conversion branch comprises at least one current input, one voltage output, one output capacitor, at least three switching tubes and at least one energy storage capacitor;

3. The voltage conversion circuit according to claim 1 or 2, wherein the first conversion branch comprises a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a first capacitor, a second capacitor, a first inductor and a second inductor;

4. The voltage conversion circuit according to claim 3, wherein the second conversion branch comprises a fifth switching tube, a sixth switching tube, a seventh switching tube, a third capacitor, and a fourth capacitor;

5. The voltage conversion circuit according to claim 3, wherein the second conversion branch includes an eighth switching tube, a ninth switching tube, a tenth switching tube, an eleventh switching tube, a twelfth switching tube, a thirteenth switching tube, a fifth capacitor, a sixth capacitor, and a seventh capacitor;

6. The voltage conversion circuit of claim 5, wherein the controller is further configured to:

7. The voltage conversion circuit of claim 5, wherein the controller is further configured to:

8. The voltage conversion circuit of claim 5, wherein the controller is further configured to:

9. The voltage conversion circuit according to claim 5, further comprising M longitudinal extension branches connected in series, each longitudinal extension branch comprising a first extension switch tube, a second extension switch tube, a first extension capacitor and a second extension capacitor, wherein M is an integer greater than or equal to 1;

10. The voltage conversion circuit of claim 9, wherein the controller is further configured to: the switching tubes in the second switching branch and the longitudinal expansion branch are controlled to be alternately switched on and switched off at a duty ratio of 50%, so that the switching tubes in the second switching branch and the longitudinal expansion branch work in two working states;

11. The voltage conversion circuit according to claim 5, 6 or 9, wherein the first conversion branch further comprises a fourteenth switching tube, a fifteenth switching tube and an eighth capacitor;

12. The voltage conversion circuit of claim 11, wherein the controller is further configured to:

13. The voltage conversion circuit of claim 11, wherein the controller is further configured to:

14. The voltage conversion circuit of claim 5, wherein the first conversion branch further comprises a sixteenth switching tube, a seventeenth switching tube, and a ninth capacitor;

15. The voltage conversion circuit of claim 14, wherein the controller is further configured to:

16. The voltage conversion circuit of claim 14, wherein the controller is further configured to:

17. The voltage conversion circuit according to any one of claims 14-16, wherein the controller is further configured to:

18. An electronic device comprising a voltage conversion circuit according to any one of claims 1-17.