CN108054918B

CN108054918B - Control method, control circuit and system of four-tube BUCK-BOOST circuit

Info

Publication number: CN108054918B
Application number: CN201711154589.0A
Authority: CN
Inventors: 王俊琦; 谌海涛; 叶刚
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2017-11-20
Filing date: 2017-11-20
Publication date: 2020-04-03
Anticipated expiration: 2037-11-20
Also published as: CN108054918A; WO2019095771A1

Abstract

The embodiment of the application discloses a control method, a control circuit and a system of a four-pipe BUCK-BOOST circuit, which are used for realizing the switching of the working modes of the four-pipe BUCK-BOOST circuit by changing a modulation mode on the premise of not additionally increasing a hardware circuit, thereby achieving the purpose of improving the overall working efficiency of the circuit. The method in the embodiment of the application comprises the following steps: acquiring an actual output voltage value of the four-tube BUCK-BOOST circuit; when the circuit is in a rated load state and the actual output voltage value overshoots, the circuit is adjusted to a phase-shifting control mode, and in the phase-shifting control mode, the phase-shifting angle between Q4 and Q1 is increased, so that the output current is reduced; in the phase-shifting control mode, if the actual output voltage value overshoots with the further reduction of the output current, the circuit is adjusted to the width-adjusting control mode, and in the width-adjusting control mode, the duty ratios of Q1 and Q3 are reduced in an equal proportion, so that the output current is reduced.

Description

Control method, control circuit and system of four-tube BUCK-BOOST circuit

Technical Field

The application relates to the field of BUCK-BOOST circuits, in particular to a control method, a control circuit and a system of a four-tube BUCK-BOOST circuit.

Background

DC/DC converters are electronic devices that convert one DC voltage to another DC voltage. The four-pipe BUCK-BOOST circuit is a DC/DC circuit topology widely used in recent years, and the circuit structure thereof is shown in fig. 1. Wherein, Q1-Q4 are power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs), Lo is a filter inductor, Cin is an input capacitor, and Co is an output filter capacitor. The control strategy of the circuit is flexible, and four MOSFET tubes can be combined to form a plurality of Pulse Width Modulation (PWM) modulation strategies.

The technical scheme adopted by the prior art is as follows: in the method, an inductor current critical conduction mode (BCM) + an inductor current discontinuous mode (DCM) and two modulation control modes are simultaneously adopted, and on the basis of the four-transistor BUCK-BOOST circuit shown in fig. 1, as shown in fig. 2A and fig. 2B, when a heavy load is output, the circuit operates in the BCM mode and operates according to the PWM modulation mode shown in fig. 2A: t 0-t 3 are a complete switching period, and two MOS tubes of the same bridge arm are conducted in a complementary mode. The initial times of the periods Q1 and Q4 are turned on, the end times of the periods Q2 and Q3 are turned off simultaneously, and the inductive current is continuous in critical mode, namely, the inductive current is turned on in the next period immediately after the zero crossing at the time t 3. As the load decreases, the operating frequency of the circuit increases linearly, and after reaching a defined maximum frequency, the operating frequency no longer changes, and then the circuit enters into DCM mode and operates according to the PWM modulation scheme shown in fig. 2B: t 0-t 4 are a complete switching period, and two MOS tubes of the same bridge arm are conducted in a complementary mode. Compared with the BCM mode, at the time of t3, the inductor current crosses zero, then Q3 turns off, Q4 turns on, and Q2 and Q4 are increased at the stage of t3 to t4 while the conduction mode is on, so that the inductor current is clamped. At the end of a cycle when Q2 is off, Q1 is then on, a new duty cycle is started, and the circuit repeats itself. The purpose of regulating the voltage transmission ratio of the converter and controlling the output voltage is achieved by controlling the duty ratio of Q1 and Q4.

However, in the existing technical solution, additional detection and control circuits are required to be added to realize the switching between the BCM and DCM, which results in complex control and increased circuit cost.

Disclosure of Invention

The embodiment of the application provides a control method, a control circuit and a system of a four-pipe BUCK-BOOST circuit, which are used for realizing the switching of the working modes of the four-pipe BUCK-BOOST circuit by changing a modulation mode on the premise of not additionally increasing a hardware circuit, thereby achieving the purpose of improving the overall working efficiency of the circuit.

A first aspect of the embodiments of the present application provides a control method for a four-transistor BUCK-BOOST circuit, where the four-transistor BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs, Q1, Q2, Q3, and Q4, Q1 and Q2 are complementary conduction, Q3 and Q4 are complementary conduction, an input terminal of Q1 is connected to an anode of an input power supply, an output terminal of Q2 is connected to a cathode of the power input terminal, an output terminal of Q4 is connected to a cathode of the voltage output terminal, an input terminal of Q3 is connected to an anode of the voltage output terminal, including: acquiring an actual output voltage value of the four-tube BUCK-BOOST circuit; when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, adjusting the four-tube BUCK-BOOST circuit to a phase-shifting control mode, wherein the rated load state indicates that the four-tube BUCK-BOOST circuit is in a full-load state for working, and in the phase-shifting control mode, a phase-shifting angle between the Q4 and the Q1 is increased, so that the output current is reduced; note that, the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current; in the phase-shifting control mode, if the actual output voltage value overshoots, the four-tube BUCK-BOOST circuit is adjusted to a width modulation control mode, and in the width modulation control mode, the duty ratios of the Q1 and the Q3 are reduced in an equal proportion, so that the output current is reduced; the duty ratios of the Q1 and the Q3 are in a positive correlation with the current value of the output current by a multiple of equal proportion change. In the embodiment of the application, a hardware circuit is not additionally arranged, and the four-tube BUCK-BOOST circuit can always work in a light load/no-load state when the load is reduced only by changing a modulation mode and taking a phase shift angle and a duty ratio as control quantities, so that the switching of the working mode of the four-tube BUCK-BOOST circuit is realized, and the aim of improving the overall working efficiency of the circuit is fulfilled.

In a possible design, in a first implementation manner of the first aspect of the embodiment of the present application, the adjusting the four-pipe BUCK-BOOST circuit to the phase shift control mode when the four-pipe BUCK-BOOST circuit is in the rated load state and the actual output voltage value overshoots includes: when the four-tube BUCK-BOOST circuit is in the rated load state, judging whether the difference value between the actual output voltage value and the rated output voltage value is larger than a preset value or not; and if so, determining the actual output voltage value overshoot, and adjusting the four-tube BUCK-BOOST circuit to a phase-shifting control mode. In the implementation mode, the mode of judging whether the actual output voltage value overshoots is refined, so that the steps of the embodiment of the application are more perfect.

In a possible design, in a second implementation manner of the first aspect of the embodiment of the present application, the adjusting the four-pipe BUCK-BOOST circuit to the phase shift control mode includes: increasing the phase shift angle of the Q4 and the Q1 at a preset first rate such that the difference between the actual output voltage value and the nominal output voltage value is less than the preset value. In the implementation mode, how to adjust the circuit to the phase-shift control mode is refined, and the implementation modes of the embodiment of the application are increased.

In a possible design, in a third implementation manner of the first aspect of the embodiment of the present application, in the phase shift control mode, if the actual output voltage value overshoots, adjusting the four-transistor BUCK-BOOST circuit to the width modulation control mode includes: when the phase shift angle reaches the maximum value and the actual voltage output value overshoots, the four-tube BUCK-BOOST circuit finishes the phase shift control mode and is adjusted to the width modulation control mode; when the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is the value of the duty ratio of the Q2; when the output voltage of the four-tube BUCK-BOOST circuit is smaller than the input voltage, the maximum value is the value of the duty ratio of the Q4. In this implementation manner, a specific value of the maximum value that the phase shift angle can reach under different buck-boost conditions and a trigger condition for switching from the phase shift control mode to the width modulation control mode are described, so that the logic of the embodiment of the present application is enhanced.

In a possible design, in a fourth implementation manner of the first aspect of the embodiment of the present application, the adjusting the four-pipe BUCK-BOOST circuit to the width-modulation control mode includes: proportionally reducing the duty cycle of the Q1 and the duty cycle of the Q3 at a preset second rate such that an error between the actual output voltage value and the nominal output voltage value is less than the preset value. In the implementation mode, how to adjust the circuit to the width modulation control mode is refined, and the implementation modes of the embodiment of the application are increased.

In a possible design, in a fifth implementation manner of the first aspect of the embodiment of the present application, a calculation formula of a voltage transfer ratio of the four-pipe BUCK-BOOST circuit is:

the P is used for representing the voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used for representing the duty cycle of the Q1, the DQ2 is used for representing the duty cycle of the Q2, the DQ3 is used for representing the duty cycle of the Q3, and the DQ4 is used for representing the duty cycle of the Q4. In the implementation mode, a specific calculation formula of the voltage transmission ratio in the circuit is refined, so that the operability of the embodiment of the application is stronger.

In a possible design, in a sixth implementation manner of the first aspect of the embodiment of the present application, when the four-transistor BUCK-BOOST circuit is in the rated load state, the four-transistor BUCK-BOOST circuit adopts a full-load inductor current critical continuous BCM modulation control mode. In this implementation manner, the operating mode adopted by the circuit when the circuit is in the rated load state is described, so that the content of the embodiment of the present application is richer and is easy to implement.

A second aspect of an embodiment of the present application provides a control circuit for controlling a four-transistor BUCK-BOOST circuit, where the four-transistor BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs: q1, Q2, Q3 and Q4, wherein the Q1 and the Q2 are complementarily turned on, the Q3 and the Q4 are complementarily turned on, an input terminal of the Q1 is connected with an anode of the input power supply, an output terminal of the Q2 is connected with a cathode of the power supply input terminal, an output terminal of the Q4 is connected with a cathode of the voltage output terminal, an input terminal of the Q3 is connected with an anode of the voltage output terminal, and the control circuit comprises a voltage detection circuit and a pulse width modulation PWM control circuit, and comprises: the voltage detection circuit is used for acquiring the actual output voltage value of the four-tube BUCK-BOOST circuit; the PWM control circuit is used for receiving the actual output voltage value detected by the voltage detection circuit and determining that when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, a first control signal in a phase-shifting modulation mode is output to the four-tube BUCK-BOOST circuit so as to control the four-tube BUCK-BOOST circuit to work in a phase-shifting control mode, the rated load state indicates that the four-tube BUCK-BOOST circuit is in a full load state, and in the phase-shifting control mode, a phase-shifting angle between the Q4 and the Q1 is increased, so that the output current is reduced; the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current; in the phase-shift control mode, the PWM control circuit is further configured to receive an actual output voltage value detected by the voltage detection circuit, and determine that if the actual output voltage value overshoots, a second control signal in a width modulation control mode is output to the four-transistor BUCK-BOOST circuit to control the four-transistor BUCK-BOOST circuit to operate in the width modulation control mode, in which duty ratios of the Q1 and the Q3 are reduced in equal proportion, so that the output current is reduced; the duty ratios of the Q1 and the Q3 are in a positive correlation with the current value of the output current by a multiple of equal proportion change. In the embodiment of the application, a hardware circuit is not additionally arranged, and the four-tube BUCK-BOOST circuit can always work in a light load/no-load state when the load is reduced only by changing a modulation mode and taking a phase shift angle and a duty ratio as control quantities, so that the switching of the working mode of the four-tube BUCK-BOOST circuit is realized, and the aim of improving the overall working efficiency of the circuit is fulfilled.

In one possible design, in a first implementation manner of the second aspect of the embodiment of the present application, the PWM control circuit includes a first comparison circuit and a first adjustment circuit, and includes: the first comparison circuit is used for receiving an actual voltage output value output by the voltage detection circuit when the four-tube BUCK-BOOST circuit is in the rated load state, and judging whether a difference value between the actual output voltage value and the rated output voltage value is larger than a preset value or not; if yes, outputting a first trigger signal to the first adjusting circuit; the first adjusting circuit is configured to receive the first trigger signal output by the first comparing circuit, and output the first control signal to the four-transistor BUCK-BOOST circuit according to the first trigger signal, so as to control the four-transistor BUCK-BOOST circuit to operate in a phase-shift control mode. In the implementation mode, the mode of judging whether the actual output voltage value overshoots is refined, so that the steps of the embodiment of the application are more perfect.

In a possible design, in a second implementation form of the second aspect of the embodiment of the present application, the first control signal is used to instruct the four-pipe BUCK-BOOST circuit to increase the phase shift angle of the Q4 and the Q1 at a preset first rate, so that the difference between the actual output voltage value and the nominal output voltage value is smaller than the preset value. In the implementation mode, how to adjust the circuit to the phase-shift control mode is refined, and the implementation modes of the embodiment of the application are increased.

In a possible design, in a third implementation manner of the second aspect of the embodiment of the present application, the PWM control circuit includes a second comparing circuit and a second adjusting circuit,

the second comparison circuit is used for receiving an actual voltage output value output by the voltage detection circuit when the four-tube BUCK-BOOST circuit works in the phase-shifting control mode; if the second comparison circuit determines that the phase shift angle reaches the maximum value according to the actual voltage output value and the actual voltage output value overshoots, a second trigger signal is output to the second adjusting circuit; the second adjusting circuit is configured to receive the second trigger signal output by the second comparing circuit, and output the second control signal to the four-transistor BUCK-BOOST circuit according to the second trigger signal, so as to control the four-transistor BUCK-BOOST circuit to end the phase shift control mode and adjust to the width modulation control mode; when the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is the value of the duty ratio of the Q2; when the output voltage of the four-tube BUCK-BOOST circuit is smaller than the input voltage, the maximum value is the value of the duty ratio of the Q4. In this implementation manner, a specific value of the maximum value that the phase shift angle can reach under different buck-boost conditions and a trigger condition for switching from the phase shift control mode to the width modulation control mode are described, so that the logic of the embodiment of the present application is enhanced.

In a possible design, in a fourth implementation manner of the second aspect of the embodiment of the present application, the second control signal is configured to instruct the four-pipe BUCK-BOOST circuit to reduce the duty cycle of the Q1 and the duty cycle of the Q3 proportionally at a preset second rate, so that an error between the actual output voltage value and the rated output voltage value is smaller than the preset value. In the implementation mode, how to adjust the circuit to the width modulation control mode is refined, and the implementation modes of the embodiment of the application are increased.

In a possible design, in a fifth implementation manner of the second aspect of the embodiment of the present application, a calculation formula of the voltage transfer ratio of the four-pipe BUCK-BOOST circuit is:

In a possible design, in a sixth implementation manner of the second aspect of the embodiment of the present application, when the four-transistor BUCK-BOOST circuit is in the rated load state, the four-transistor BUCK-BOOST circuit adopts a full-load inductor current critical continuous BCM modulation control mode. In this implementation manner, the operating mode adopted by the circuit when the circuit is in the rated load state is described, so that the content of the embodiment of the present application is richer and is easy to implement.

A third aspect of the embodiments of the present application provides a control system of a four-transistor BUCK-BOOST circuit, where the four-transistor BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs Q1, Q2, Q3, and Q4, Q1 and Q2 are complementary conduction, Q3 and Q4 are complementary conduction, an input terminal of Q1 is connected to an anode of an input power source, an output terminal of Q2 is connected to a cathode of the power input terminal, an output terminal of Q4 is connected to a cathode of the voltage output terminal, an input terminal of Q3 is connected to an anode of the voltage output terminal, including: the acquisition module is used for acquiring the actual output voltage value of the four-tube BUCK-BOOST circuit; a mode selection module, configured to adjust the four-transistor BUCK-BOOST circuit to a phase shift control mode when the four-transistor BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, in which a phase shift angle between the Q4 and the Q1 is increased so that an output current is decreased; the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current; the mode selection module is further configured to adjust the four-transistor BUCK-BOOST circuit to a width modulation control mode in the phase shift control mode if the actual output voltage value overshoots, and in the width modulation control mode, duty ratios of the Q1 and the Q3 are reduced in an equal proportion, so that the output current is reduced; the duty ratios of the Q1 and the Q3 are in a positive correlation with the current value of the output current by a multiple of equal proportion change.

In a possible design, in a first implementation manner of the third aspect of the embodiment of the present application, the mode selection module specifically includes: the judging unit is used for judging whether the difference value between the actual output voltage value and the rated output voltage value is larger than a preset value or not when the four-tube BUCK-BOOST circuit is in a rated load state; and if so, the first adjusting unit is used for adjusting the four-tube BUCK-BOOST circuit to a phase-shifting control mode. In the implementation mode, the mode of judging whether the actual output voltage value overshoots is refined, so that the steps of the embodiment of the application are more perfect.

In a possible design, in a second implementation manner of the third aspect of the embodiment of the present application, the first adjusting unit is specifically configured to:

increasing the phase shift angle of the Q4 and the Q1 at a preset first rate such that the difference between the actual output voltage value and the nominal output voltage value is less than the preset value. In the implementation mode, how to adjust the circuit to the phase-shift control mode is refined, and the implementation modes of the embodiment of the application are increased.

In a possible design, in a third implementation manner of the third aspect of the embodiment of the present application, the mode selection module specifically includes:

the second adjusting unit is used for ending the phase shift control mode and adjusting the four-tube BUCK-BOOST circuit to the width modulation control mode when the phase shift angle reaches the maximum value and the actual voltage output value overshoots;

when the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is the value of the duty ratio of the Q2;

when the output voltage of the four-tube BUCK-BOOST circuit is smaller than the input voltage, the maximum value is the value of the duty ratio of the Q4. In this implementation manner, a specific value of the maximum value that the phase shift angle can reach under different buck-boost conditions and a trigger condition for switching from the phase shift control mode to the width modulation control mode are described, so that the logic of the embodiment of the present application is enhanced.

In a possible design, in a fourth implementation manner of the third aspect of the embodiment of the present application, the second adjusting unit is specifically configured to:

proportionally reducing the duty cycle of the Q1 and the duty cycle of the Q3 at a preset second rate such that an error between the actual output voltage value and the nominal output voltage value is less than the preset value. In the implementation mode, how to adjust the circuit to the width modulation control mode is refined, and the implementation modes of the embodiment of the application are increased.

In a possible design, in a fifth implementation manner of the third aspect of the embodiment of the present application, a calculation formula of a voltage transfer ratio of the four-pipe BUCK-BOOST circuit is:

In a possible design, in a sixth implementation manner of the third aspect of the embodiment of the present application, when the four-transistor BUCK-BOOST circuit is in the rated load state, the four-transistor BUCK-BOOST circuit adopts a full-load inductor current critical continuous BCM modulation control mode. In this implementation manner, the operating mode adopted by the circuit when the circuit is in the rated load state is described, so that the content of the embodiment of the present application is richer and is easy to implement.

A fourth aspect of the present application provides a chip apparatus, where the chip system includes a processor and a memory, and the memory includes instructions, and the processor can execute the instructions stored in the memory to cause the chip apparatus to perform the method according to the first aspect.

A fifth aspect of the present application provides a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the method of the above-described aspects.

A sixth aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of the above aspects.

According to the technical scheme, the embodiment of the application has the following advantages: detecting the actual output voltage value of the four-tube BUCK-BOOST circuit; when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, adjusting the four-tube BUCK-BOOST circuit to a phase-shifting control mode, wherein in the phase-shifting control mode, a phase-shifting angle between the Q4 and the Q1 is increased; in the phase-shifting control mode, if the actual output voltage value overshoots, the four-tube BUCK-BOOST circuit is adjusted to a width modulation control mode, and in the width modulation control mode, the duty ratios of the Q1 and the Q3 are reduced in an equal proportion. In the embodiment of the application, a hardware circuit is not additionally arranged, and the four-tube BUCK-BOOST circuit can always work in a light load/no-load state when the load is reduced only by changing a modulation mode and taking a phase shift angle and a duty ratio as control quantities, so that the switching of the working mode of the four-tube BUCK-BOOST circuit is realized, and the aim of improving the overall working efficiency of the circuit is fulfilled.

Drawings

FIG. 1 is a diagram of a conventional BUCK-BOOST circuit;

fig. 2A is a diagram of a conventional BCM modulation control scheme;

FIG. 2B is a diagram of a conventional DCM modulation control scheme;

FIG. 3 is a schematic flowchart of a possible control method for a four-pipe BUCK-BOOST circuit according to an embodiment of the present disclosure;

fig. 4 is a diagram of a possible boost state BCM modulation control scheme provided by the embodiment of the present application;

FIG. 5 is a diagram illustrating a possible boost phase shift control scheme according to an embodiment of the present disclosure;

FIG. 6 is a diagram illustrating a possible boost dynamic bandwidth control scheme according to an embodiment of the present disclosure;

fig. 7 is a diagram of a possible buck BCM modulation control scheme according to an embodiment of the present application;

FIG. 8 is a diagram illustrating a possible step-down phase shift control scheme according to an embodiment of the present disclosure;

FIG. 9 is a diagram illustrating a possible step-down bandwidth control scheme according to an embodiment of the present disclosure;

fig. 10 is a schematic structural diagram of a possible control circuit according to an embodiment of the present disclosure;

fig. 11 is a schematic structural diagram of a possible control system of a four-pipe BUCK-BOOST circuit according to an embodiment of the present disclosure.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The general traditional four-tube BUCK-BOOST circuit control scheme can be divided into: BUCK, BUCK-BOOST and BOOST, wherein as shown in figure 1, BUCK mode: q3 remains on, Q4 remains off, and Q1 and Q2 are alternately on; BUCK-BOOST mode: q1 and Q2 are alternately turned on, and Q3 and Q4 are alternately turned on; BOOST mode: q1 remains on, Q2 remains off, and Q3 and Q4 are alternately on. In each period, the circuit only works in one working mode, and when the input voltage is greater than the expected output voltage, the circuit works in a BUCK mode; when the input voltage is close to the expected output voltage, the circuit works in a BUCK-BOOST mode; when the input voltage is less than the desired output voltage, the circuit operates in a BOOST mode.

In addition, the four-transistor BUCK-BOOST circuit has the characteristic of flexible control strategy, and four MOS transistors Q1, Q2, Q3 and Q4 can be combined to form a plurality of Pulse Width Modulation (PWM) strategies. In the prior art, the following PWM strategy may be employed:

① Continuous Conduction Mode (CCM), in which the inductor current never reaches 0 in a switching period, it can also be understood that the inductor never "resets", i.e. the inductor flux never returns to 0 in the switching period, and when the MOS transistor is closed, the current still flows in the coil.

② BCM mode + Forced Continuous Conduction Mode (FCCM), in which the controller monitors the inductor current and immediately closes the power switch upon detecting that the current is equal to 0, the controller always has equal inductor current "reset" to activate the switch, if the inductor current is high and the cut-off slope is fairly flat, the switching period is extended, FCCM mode, since the low level MOS transistor is bidirectionally conductive, when the current on the inductor is 0, the current of the inductor reverses, the MOS transistor synchronous follow current does not cut off, also is continuously conducting mode, so is FCCM mode.

③ BCM mode + DCM mode, in DCM mode, the inductive current is always 0 in one switching period, which means the inductance is properly reset, that is, the inductive current is 0 when the MOS tube is closed, when the four-tube BUCK-BOOST circuit adopts BCM mode + FCCM mode, if the output is overloaded, the circuit works in BCM modulation control mode, the working frequency of the circuit linearly increases along with the decrease of the output load, when the working frequency does not change after reaching the limited maximum frequency, the circuit enters DCM mode and works according to the PWM modulation mode shown in FIG. 2B.

In view of this, the present application provides a control method for a four-transistor BUCK-BOOST circuit, which is used to implement high efficiency of the BUCK-BOOST circuit in a full load range on the premise of not additionally adding a hardware circuit.

Referring to fig. 3, a flowchart of a method for controlling a four-transistor BUCK-BOOST circuit provided in the present application is shown, where the method includes:

301. acquiring an actual output voltage value of the four-tube BUCK-BOOST circuit;

based on the circuit structure diagram of the four-tube BUCK-BOOST circuit shown in fig. 1, the four-tube BUCK-BOOST circuit receives an input voltage Vin and outputs a stable output voltage signal Vout after power conversion, and the four-tube BUCK-BOOST circuit includes: the filter inductor Lo, a first MOS transistor Q1 coupled between the input voltage Vin and the first end of the inductor Lo, a second MOS transistor Q2 coupled between the first end of the inductor Lo and the ground, a third MOS transistor Q3 coupled between the second end of the inductor Lo and the regulated output voltage Vout, and a fourth MOS transistor Q4 coupled between the second end of the inductor Lo and the ground. Wherein Cin is an input filter capacitor and Co is an output filter capacitor.

In the working process of the circuit, the actual output voltage value of the four-tube BUCK-BOOST circuit, namely the value of the actual output voltage signal Vout output after power conversion is obtained, and then the difference value between the actual output voltage value and the rated output voltage value is compared.

302. When the four-tube BUCK-BOOST circuit is in a rated load state, judging whether the difference value between the actual output voltage value and the rated output voltage value is larger than a preset value or not; if yes, go to step 303; if not, go to step 304;

it should be noted that the circuit carrying capability may have the following situations: no-load, light load, heavy load, and full load. The light load means that the load rate is below a first threshold value within a load range of the circuit, compared with the full load, and in practical applications, the first threshold value may be 30% or 50%, and the load rate of the circuit during heavy load may be in a range, for example, 75% to 95%. When the four-transistor BUCK-BOOST circuit is in a rated load state, the circuit operates in a BCM mode, ZVS turn-on of all MOS transistors is realized, heavy load efficiency is high, and the circuit is suitable for a high-power output occasion, wherein in the present application, the rated load state can represent a full load state and/or a heavy load state, and it is understood that in a load of a constant-voltage source, a load is light when a resistance is large, and as the resistance is gradually increased, a total current is gradually decreased when a voltage is stable, and thus a voltage of the resistance is gradually increased, for example, in one circuit, V is (R1+ R2) I, and if V is not changed, R2 is increased, I is decreased, so R1I is decreased, and R2I is V-R1I is increased. Therefore, as the output current gradually decreases, there is a case where the actual output voltage value overshoots, that is, exceeds the rated output voltage value, so that it is determined whether the difference between the actual output voltage value and the rated output voltage value is greater than the preset value, if so, it is determined that the actual output voltage value overshoots, and step 303 is executed; if not, the actual output voltage value is considered to satisfy the condition of the rated output voltage value to be output, and step 304 is executed. It should be noted that, in practical applications, there are various ways to determine the overshoot of the actual output voltage value of the four-transistor BUCK-BOOST circuit, except that whether the difference between the actual output voltage value and the rated output voltage value is greater than a preset value or not, the difference between the actual output voltage value and the rated output voltage value can also be determined, and if the difference is greater than a first preset value, the actual output voltage value is considered to be overshot, and step 303 is executed; if the difference rate is smaller than the first preset value, the actual output voltage value is considered to satisfy the condition of the rated output voltage value to be output, and step 304 is executed. Therefore, the specific manner of determining whether the actual output voltage value overshoots is not limited in this application.

303. Adjusting the four-tube BUCK-BOOST circuit to a phase-shifting control mode;

when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, the four-tube BUCK-BOOST circuit is adjusted to a phase shift control mode, in the phase shift control mode, the phase shift angle between Q4 and Q1 shown in fig. 1 is increased, wherein the value of the phase shift angle between Q4 and Q1 is in an inverse correlation relation with the current value of the output current, namely the value of the phase shift angle between Q4 and Q1 enables the output current to be reduced, and the actual output voltage value is maintained constant, namely the overshoot of the actual output voltage value is eliminated. The adjustment of the circuit to the phase shift control mode may be to increase the phase shift angles of Q4 and Q1 at a preset first rate, or to gradually increase the phase shift angle between Q4 and Q1 in other ways to maintain the stability of the actual output voltage value, so the application is not limited thereto.

304. Maintaining the four-pipe BUCK-BOOST circuit in a BCM mode;

when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value does not overshoot, the working mode of the four-tube BUCK-BOOST circuit is unchanged, namely the four-tube BUCK-BOOST circuit is maintained in the BCM mode.

305. In a phase-shifting control mode, judging whether the difference value between the actual output voltage value and the rated output voltage value is greater than a preset value or not; if yes, go to step 306; if not, go to step 307;

it can be understood that, in the phase shift control mode, the phase shift angle between Q4 and Q1 is continuously increased, the output current can be gradually decreased to maintain the actual output voltage constant, however, when the phase shift angle between Q4 and Q1 reaches the maximum value, if the output current is further decreased and the phase shift angle between Q4 and Q1 can not be increased, the actual voltage output value may still overshoot, so that it is determined whether the difference between the actual output voltage value and the rated output voltage value is greater than the predetermined value, if so, the actual output voltage value is considered to overshoot, and step 306 is executed; if not, the actual output voltage value is considered to satisfy the condition of the rated output voltage value to be output, and step 307 is executed. Similar to step 302, in practical applications, there are various ways to determine the overshoot of the actual output voltage value of the four-transistor BUCK-BOOST circuit, and details thereof are not repeated here.

It should be noted that the preset value in step 302 and the preset value in step 305 may be the same value or different values, and are not limited herein.

In addition, the four-tube BUCK-BOOST circuit is a BUCK/BOOST hybrid circuit, and when the four-tube BUCK-BOOST circuit is in a BOOST state, namely the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value of the phase shift angle between Q4 and Q1 is the value of the duty ratio of Q2; when the four-tube BUCK-BOOST circuit is in the BUCK state, i.e., the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value of the phase shift angle between Q4 and Q1 is the value of the duty cycle of Q4.

306. Ending the phase-shifting control mode of the four-tube BUCK-BOOST circuit and adjusting the four-tube BUCK-BOOST circuit to a width modulation control mode;

when the phase shift angle between the Q4 and the Q1 reaches the maximum value and the actual voltage output value overshoots, the four-tube BUCK-BOOST circuit finishes the phase shift control mode and is adjusted to the width modulation control mode, under the width modulation control mode, the duty ratios of the Q1 and the Q3 are reduced in an equal proportion mode, wherein the multiples of the equal proportion change of the duty ratios of the Q1 and the Q3 are in positive correlation with the current value of the output current, so that the duty ratios of the Q1 and the Q3 are reduced in an equal proportion mode, the output current is reduced, the actual output voltage value is maintained to be constant, and the overshoot condition is eliminated. The adjustment of the circuit to the phase shift control mode may be to reduce the duty ratios of Q1 and Q3 at the preset second rate in an equal proportion, or to reduce the duty ratios of Q1 and Q3 in a stepwise manner, so as to maintain the stability of the actual output voltage value, which is not limited in this application.

307. The four-pipe BUCK-BOOST circuit is maintained in a phase shift control mode.

When the four-tube BUCK-BOOST circuit is in the phase-shifting control mode and the actual output voltage value is not overshot, the working mode of the four-tube BUCK-BOOST circuit is not changed, namely the four-tube BUCK-BOOST circuit is maintained in the phase-shifting control mode.

For the sake of understanding, the embodiments of the present application will be described below with reference to specific examples, which respectively include a: the four tubes BUCK-BOOST are in a boosting state and B: the four tubes of BUCK-BOOST are in a decompression state, and are detailed as follows:

a: the four-tube BUCK-BOOST is in a boosting state

A Boost Buck-Boost converter with 30V input voltage, 60V output voltage and 15A rated output current is taken as an example.

When the circuit is fully loaded and output, the circuit works according to a BCM modulation control mode, as shown in FIG. 4, the waveform of the boost full load BCM modulation control mode is shown, wherein t 0-t 3 is a complete working period, at the time of t0, Q1 and Q4 are simultaneously conducted, and the inductor current IL is linearly increased; at time t1, Q4 is turned off, and the inductor current IL reaches the peak current I1; then, in a time period from t1 to t2, Q1 and Q3 are simultaneously conducted, the inductive current is linearly reduced, Q1 is turned off at t2, and the inductive current IL is reduced to I2; and then in a time period from t2 to t3, Q3 and Q2 are simultaneously conducted, the inductance current IL is linearly reduced, the inductance current IL crosses zero at t3, and at the moment, Q3 and Q2 are simultaneously turned off, so that one working cycle is ended. The input voltage Vin of the circuit is 30V, the output voltage is 60V, and the required voltage transfer ratio is 2, wherein the calculation formula of the voltage transfer ratio of the four-tube BUCK-BOOST circuit is as follows:

the P is used for representing the voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used for representing the duty cycle of the Q1, the DQ2 is used for representing the duty cycle of the Q2, the DQ3 is used for representing the duty cycle of the Q3, and the DQ4 is used for representing the duty cycle of the Q4. The duty ratio DQ1 of Q1 may be 0.8, the duty ratio DQ4 of Q4 may be 0.6, and the voltage transfer ratio P of the circuit may be DQ1/(1-DQ4) 2, and since the duty ratios of Q2 and Q3 are complementary to the duty ratios of Q1 and Q4, respectively, the duty ratio DQ2 of Q2 may be 0.2, and the duty ratio DQ3 of Q3 may be 0.6 (the influence of the dead zone is ignored in this application). The inductance is set as follows: l ═ 1.12uH, the switching frequency was: the peak current I1 ═ 64.3A, (Vin × DQ4)/(L × fs) ═ 64.3A, I2 ═ I1+ ((Vin-Vo) × (DQ1-DQ4))/(L × fs) ═ 42.9A, and the output current Io ═ 0.5 × (I1+ I2) × (DQ1-DQ4) +0.5 × I2 × DQ2 were calculated by the formula, and the duty ratio and I1 and I2 were substituted to obtain the output current Io ═ 15A, which agrees with the set output current value.

When the output current is reduced, the circuit starts phase shift control, the duty ratio of each MOS tube is maintained to be unchanged, the purpose of adjusting the output current is achieved by adjusting the phase of the starting time of the duty ratios of Q1 and Q4, and the maximum phase shift angle is achieved when Q1 and Q3 are turned off simultaneously. FIG. 5 shows the waveform when the phase shift angle Da reaches the maximum value, i.e. the duty ratio value of Q2 is 0.2, t 0-t 3 is a complete working cycle, and Q1 and Q4 are simultaneously conducted at time t0, so that the inductance current linearly increases; at time Q4, which is t1, the inductor current reaches the peak current I1; then in a time period from t1 to t2, Q1 and Q3 are simultaneously conducted, the inductive current linearly decreases, the inductive current crosses zero at the time of t2, Q1 and Q3 are simultaneously turned off, in a time period from t2 to t3, Q2 and Q4 are simultaneously conducted, the inductive clamp is short-circuited, the inductive current is kept at 0A and does not change, and then the next new switching period is started along with the turning-on of Q1. Because the duty ratio of each MOS tube is kept unchanged, the voltage transmission ratio is kept unchanged, and the output voltage is kept unchanged at 60V. Compared with the inductor current in fig. 4, the current waveform at this time changes, the inductance L is maintained to be 1.12uH, the switching frequency fs is 250kHz, I1 (Vin x (DQ4-Da))/(L × fs) — 42.9A is obtained by calculation according to a formula, where Da is the maximum value of the phase shift angle, when the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the value of Da is the value of the duty ratio DQ2 of Q2, and the output current Io is 0.5 × I1 × DQ3 to be 8.58A. It can be seen that as the load is reduced, the phase shift angle between Q4 and Q1 is correspondingly increased, so that the output current can be reduced, and the voltage transmission ratio is maintained unchanged, thereby ensuring that the output voltage is constant.

With the further reduction of the output current, since the load current can not be reduced by increasing the phase shift angle, the width modulation control mode is entered, the duty ratio of the Q1 and the Q3 is reduced proportionally, and the voltage transmission ratio is maintained unchanged on the basis of reducing the load current. Taking the waveform shown in fig. 6 as an example, the duty ratio DQ1 of Q1 is reduced from the previous 0.8 to 0.6, and in order to maintain the voltage transfer ratio at 2, the duty ratio DQ3 of Q3 is correspondingly adjusted to 0.3, and Q2 and Q4 are still in complementary conduction with Q1 and Q3, respectively, so that the duty ratios DQ2 and DQ4 of Q2 and Q4 are correspondingly increased to 0.4 and 0.7, respectively. t 0-t 3 are a complete working cycle, Q1 and Q4 are simultaneously conducted at the time of t0, and the inductance current is linearly increased; at time Q4, which is t1, the inductor current reaches the peak current I1; then in a time period from t1 to t2, Q1 and Q3 are simultaneously conducted, the inductive current linearly decreases, the inductive current crosses zero at the time of t2, Q1 and Q3 are simultaneously turned off, in a time period from t2 to t3, Q2 and Q4 are simultaneously conducted, the inductive clamp is short-circuited, the inductive current is kept at 0A and does not change, and then the next new switching period is started along with the turning-on of Q1. The inductance is maintained at 1.12uH, the switching frequency is 250kHz, and the peak current I1 ═ (Vin × (DQ1-DQ3))/(L × fs) ═ 32.1A and the output current Io ═ 0.5 × I1 × DQ3 ═ 4.82A are calculated. Therefore, with the further reduction of the load, the phase shift control is switched to the width modulation control, so that the output current can be further reduced, the voltage transmission ratio is kept unchanged, and the output voltage is ensured to be constant.

B: the four-tube BUCK-BOOST is in a voltage reduction state

Take a Buck-Boost converter with 60V input voltage Vin, 30V output voltage Vo and 15A rated output current as an example.

When the circuit is fully loaded and output, the circuit works according to a BCM modulation control mode, as shown in FIG. 7, the waveform of the voltage reduction full-load BCM modulation control mode is shown, t 0-t 3 is a complete working period, Q1 and Q4 are simultaneously conducted at the time of t0, and the inductance current is linearly increased; at time t1, Q4 is turned off, and the inductor current reaches I2; then, in a time period from t1 to t2, Q1 and Q3 are simultaneously conducted, the inductive current is linearly increased, Q1 is turned off at the time of t2, and the inductive current reaches the peak current I1; and then in a time period from t2 to t3, Q3 and Q2 are simultaneously conducted, the inductive current linearly decreases, the inductive current crosses zero at t3, and Q3 and Q2 are simultaneously turned off, so that one working cycle is ended. The circuit input voltage 60V, the output voltage 30V, the required voltage transfer ratio is 0.5, the duty ratio DQ1 of Q1 can be 0.4, the duty ratio DQ4 of Q4 is 0.2, the voltage transfer ratio of the circuit at this time is DQ1/(1-DQ4) is 0.5, and the duty ratios of Q2 and Q3 are respectively complementary to the duty ratios of Q1 and Q4, so the duty ratio DQ2 of Q2 is 0.6, and the duty ratio DQ3 of Q3 is 0.8 (the influence of dead zones is ignored in this application). The inductance is set to be L-1.12 uH, and the switching frequency is as follows: fs is 500kHz, I2 ═ 21.4A, (Vin × DQ4)/(L × fs) ═ 21.4A, I1 ═ I2+ ((Vin-Vo) × (DQ1-DQ4))/(L × fs) ═ 32.1A, and output current ═ 0.5 × (I1+ I2) × (DQ1-DQ4) +0.5 × I1 × DQ2 were obtained by calculation, and DQ1, DQ4, I1, and I2 were substituted into the calculated output current value of 15A, which agrees with the set output current value.

When the output current is reduced, the circuit starts phase shift control, the duty ratio of each MOS tube is maintained to be unchanged, the purpose of adjusting the output current is achieved by adjusting the phase of the starting time of the duty ratio of Q1 and Q4, and the maximum phase shift angle is achieved when Q1 and Q3 are simultaneously turned on. FIG. 8 shows the waveform when the phase shift angle Da reaches the maximum value, i.e. the duty ratio value of Q4 is 0.2, t 0-t 3 is a complete working cycle, and Q1 and Q3 are simultaneously conducted at time t0, so that the inductance current linearly increases; at time Q1, which is t1, the inductor current reaches the peak current I1; then in a time period from t1 to t2, Q2 and Q3 are simultaneously conducted, the inductive current linearly decreases, the inductive current crosses zero at the time of t2, Q3 is turned off at the time, in a time period from t2 to t3, Q2 and Q4 are simultaneously conducted, the inductive clamp is short-circuited, the inductive current is kept at 0A and does not change, and then the next new switching period is started along with the simultaneous turn-on of Q1 and Q3. Because the duty ratio of each MOS tube is kept unchanged, the voltage transmission ratio is kept unchanged, and the output voltage is kept unchanged at 30V. Compared with the inductor current in fig. 7, the current waveform at this time changes, and the maintained inductance value is: l ═ 1.12uH, the switching frequency was: fs is 500kHz constant, I1 ═ ((Vin-Vo) × (DQ1-DQ4+ Da))/(L × fs) ═ 21.4A, and output current Io ═ 0.5 × I1 × DQ3 ═ 8.56A were calculated. It can be seen that as the load is reduced, the phase shift angle between Q4 and Q1 is correspondingly increased, so that the output current can be reduced, and the voltage transmission ratio is maintained unchanged, thereby ensuring that the output voltage is constant.

With the further reduction of the output current, since the load current can not be reduced by increasing the phase shift angle, the width modulation control mode is entered, the duty ratio of the Q1 and the Q3 is reduced proportionally, and the voltage transmission ratio is maintained unchanged on the basis of reducing the load current. Taking the waveform shown in fig. 9 as an example, the duty ratio DQ1 of Q1 is reduced from 0.4 to 0.2, and in order to maintain the voltage transfer ratio to be 0.5, the duty ratio DQ3 of Q3 is correspondingly adjusted to 0.4, and Q2 and Q4 still maintain complementary conduction with Q1 and Q3, respectively, so that the duty ratios DQ2 and DQ4 of Q2 and Q4 are correspondingly increased to 0.8 and 0.6, respectively. t 0-t 3 are a complete working cycle, Q1 and Q3 are simultaneously conducted at the time of t0, and the inductance current is linearly increased; at time Q1, which is t1, the inductor current reaches the peak current I1; then, in a time period from t1 to t2, Q2 and Q3 are simultaneously conducted, the inductive current linearly decreases, the inductive current crosses zero at the time of t2, Q3 is turned off at the time, in a time period from t2 to t3, Q2 and Q4 are simultaneously conducted, the inductive clamp is short-circuited, the inductive current is kept at 0A and does not change, and then, the next new switching period is started along with the turning-on of Q1 and Q3. The inductance was maintained at 1.12uH, the switching frequency was set at 500kHz, and the value of I1 ═ ((Vin-Vo) × DQ1)/(L × fs) ═ 10.7A, and the value of output current Io was 0.5 × I1 × DQ3 ═ 2.14A by calculation. Therefore, with the further reduction of the load, the phase shift control is switched to the width modulation control, so that the output current can be further reduced, the voltage transmission ratio is kept unchanged, and the output voltage is ensured to be constant.

It can be seen from the above that, in the embodiment of the present application, when the device is fully loaded or heavily loaded, the BCM modulation control mode is adopted, and the switching timing of the MOS transistor in one cycle is as follows: q1 and Q4 are conducted → Q1 and Q3 are conducted → Q2 and Q3 are conducted, so that ZVS of all MOS tubes is realized, and high-efficiency heavy load is ensured; with the reduction of the load, firstly entering a phase-shifting control mode (adjusting the phase shift of the Q4 and the Q1 at the turn-on moment), enabling the circuit to enter a DCM state until Q1 and Q3 are turned off (a boost mode)/turned on (a buck mode) at the same moment, reaching the maximum phase-shifting angle, and finishing the phase-shifting control; with the further reduction of the load, ending the phase-shifting control mode, entering the width modulation control mode, reducing the duty ratio of Q1 and Q3 in equal proportion, maintaining the voltage transmission ratio of the converter constant, and simultaneously increasing the duty ratio of Q2 and Q4 to maintain the switching frequency unchanged, so that the phase-shifting control and the width modulation control are combined, the BUCK-BOOST circuit works in a BCM state in a full-load mode, and can work in a DCM state all the time when the load is reduced, the full-load range is high-efficiency is ensured, and the ZVS characteristic of the circuit is not influenced and the heavy-load efficiency can be ensured; and 2, the light load works in a DCM mode, negative circulation does not exist, the efficiency is optimized, and the full load range efficiency is high; 3. no extra hardware circuit is added, the phase shift angle and the duty ratio are used as control quantities, and the control strategy is simple and efficient; 4. the switching frequency is constant and does not change with the change of the load, and the design of the EMI filter is simplified.

The control method of the four-pipe BUCK-BOOST circuit in the embodiment of the present application is described above, the control circuit provided in the embodiment of the present application is described below, the control circuit is used for controlling a four-tube BUCK-BOOST circuit, the four-tube BUCK-BOOST circuit comprises a power supply input end, a voltage output end and four power MOSFETs Q1-Q4, the Q1 and the Q2 are complementarily conducting, the Q3 and the Q4 are complementarily conducting, the input end of the Q1 is connected with the anode of the input power supply, the output end of the Q2 is connected with the negative pole of the power supply input end, the output end of the Q4 is connected with the negative pole of the voltage output end, the input terminal of the Q3 is connected to the positive electrode of the voltage output terminal, referring to fig. 10, which is a schematic structural diagram of a possible control circuit provided in the embodiment of the present application, the control circuit comprises a voltage detection circuit 1001 and a PWM control circuit 1002;

the voltage detection circuit 1001 is configured to obtain an actual output voltage value of the four-tube BUCK-BOOST circuit;

the PWM control circuit 1002 is configured to receive the actual output voltage value detected by the voltage detection circuit, and determine that when the four-transistor BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, a first control signal in a phase-shift modulation mode is output to the four-transistor BUCK-BOOST circuit to control the four-transistor BUCK-BOOST circuit to operate in a phase-shift control mode, where a phase-shift angle between the Q4 and the Q1 is increased, so that an output current is decreased; the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current;

in the phase shift control mode, the PWM control circuit 1002 is further configured to receive the actual output voltage value obtained by the voltage detection circuit 1001, and when it is determined that the actual output voltage value overshoots, output a second control signal in a width modulation control mode to the four-transistor BUCK-BOOST circuit to control the four-transistor BUCK-BOOST circuit to operate in the width modulation control mode, where duty ratios of the Q1 and the Q3 are reduced in an equal proportion, so that the output current is reduced; the duty ratios of the Q1 and the Q3 are in a positive correlation with the current value of the output current by a multiple of equal proportion change.

Optionally, the PWM control circuit 1002 may specifically include a first comparison circuit 10021 and a first adjustment circuit 10022, which includes:

the first comparing circuit 10021, when the four-transistor BUCK-BOOST circuit is in a rated load state, is configured to receive an actual voltage output value output by the voltage detecting circuit 1001, and determine whether a difference between the actual output voltage value and the rated output voltage value is greater than a preset value; if yes, a first trigger signal is output to the first adjusting circuit 10022;

the first adjusting circuit 10022 is configured to receive the first trigger signal output by the first comparing circuit 10021, and output the first control signal to the four-transistor BUCK-BOOST circuit according to the first trigger signal, so as to control the four-transistor BUCK-BOOST circuit to operate in a phase-shifting control mode.

Optionally, the PWM control circuit 1002 may specifically include a second comparing circuit 10023 and a second adjusting circuit 10024,

the second comparing circuit 10023, configured to receive an actual voltage output value output by the voltage detecting circuit 1001 when the four-transistor BUCK-BOOST circuit operates in the phase shift control mode; if the second comparing circuit 10023 determines that the phase shift angle reaches the maximum value according to the actual voltage output value and the actual voltage output value overshoots, it outputs a second trigger signal to the second adjusting circuit 10024;

the second adjusting circuit 10024 is configured to receive the second trigger signal output by the second comparing circuit 10023, and output the second control signal to the four-transistor BUCK-BOOST circuit according to the second trigger signal, so as to control the four-transistor BUCK-BOOST circuit to end the phase shift control mode and adjust to the width modulation control mode;

when the output voltage of the four-tube BUCK-BOOST circuit is smaller than the input voltage, the maximum value is the value of the duty ratio of the Q4.

The embodiment of the present application further provides a control system of a four-transistor BUCK-BOOST circuit, where the four-transistor BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs Q1-Q4, the Q1 and the Q2 are complementarily turned on, the Q3 and the Q4 are complementarily turned on, the input terminal of the Q1 is connected to the positive electrode of the input power supply, the output terminal of the Q2 is connected to the negative electrode of the power input terminal, the output terminal of the Q4 is connected to the negative electrode of the voltage output terminal, the input terminal of the Q3 is connected to the positive electrode of the voltage output terminal, please refer to fig. 11, which is a schematic structural diagram of a possible reference control system provided in the embodiment of the present application, and includes:

an obtaining module 1101, configured to obtain an actual output voltage value of the four-pipe BUCK-BOOST circuit;

a mode selection module 1102, configured to adjust the four-transistor BUCK-BOOST circuit to a phase shift control mode when the four-transistor BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, in which a phase shift angle between the Q4 and the Q1 is increased so that an output current is decreased; the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current;

the mode selection module 1102 is further configured to adjust the four-transistor BUCK-BOOST circuit to a width modulation control mode in the phase shift control mode if the actual output voltage value overshoots, where duty ratios of the Q1 and the Q3 are reduced in an equal proportion so that the output current is reduced in the width modulation control mode; the duty ratios of the Q1 and the Q3 are in a positive correlation with the current value of the output current by a multiple of equal proportion change.

Optionally, the mode selecting module 1102 specifically includes a determining unit 11021 and a first adjusting unit 11022:

a determining unit 11021, configured to determine whether a difference between the actual output voltage value and the rated output voltage value is greater than a preset value when the four-transistor BUCK-BOOST circuit is in a rated load state;

the first adjusting unit 11022, if yes, is used to adjust the four-pipe BUCK-BOOST circuit to the phase shift control mode.

Optionally, the first adjusting unit 11022 is specifically configured to:

increasing the phase shift angle of the Q4 and the Q1 at a preset first rate such that the difference between the actual output voltage value and the nominal output voltage value is less than the preset value.

Optionally, the mode selecting module 1102 may specifically include: the second adjusting unit 11023 is provided with a second adjusting unit,

a second adjusting unit 11023, configured to end the phase shift control mode and adjust the four-transistor BUCK-BOOST circuit to the width modulation control mode when the phase shift angle reaches a maximum value and the actual voltage output value overshoots;

Optionally, the second adjusting unit 11023 is specifically configured to:

proportionally reducing the duty cycle of the Q1 and the duty cycle of the Q3 at a preset second rate such that an error between the actual output voltage value and the nominal output voltage value is less than the preset value.

An embodiment of the present application further provides a chip apparatus, where the chip apparatus includes: a processor, a communication unit, and a memory. The memory includes instructions that the processor executes to cause the chip arrangement to implement the steps performed by the control circuitry in the embodiment shown in fig. 3, described above. The processor may be various types of processors. The communication unit, which may be, for example, an input/output interface, a pin or a circuit, etc., includes a system bus. Optionally, the chip further includes a memory, which may be a memory inside the chip device, such as a register, a cache, a Random Access Memory (RAM), an EEPROM, or a FLASH; the memory may also be a memory located outside the chip device, which may be various types of memory. The processor is coupled to the memory and is operable to execute the instructions stored in the memory to cause the chip arrangement to perform the steps performed by the control circuit in the embodiment illustrated in fig. 3 and described above.

The Processor according to various embodiments of the present Application may be a Central Processing Unit (CPU), a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The processor 780 may implement or execute the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a DSP and a microprocessor, or the like. Alternatively, the processor may include one or more processing units.

The Memory according to various embodiments of the present disclosure may include a volatile Memory, such as a Random Access Memory (RAM), a non-volatile dynamic Random access Memory (NVRAM), a Phase Change Random access Memory (PRAM), a Magnetoresistive Random Access Memory (MRAM), a non-volatile Memory, such as at least one magnetic Disk Memory device, a Read-Only Memory (ROM), an electrically erasable Programmable Read-Only Memory (EEPROM), a flash Memory device, such as a NAND flash Memory or a NAND flash Memory (flash Memory), a semiconductor device, such as a solid state Disk (solid state Disk, SSD), and the like.

The terms "first" and "second" in the description and claims of the embodiments of the present application and the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In the various embodiments of the present application described above, all or part of the implementation may be implemented by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable medium to another, for example, from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk), among others. The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A control method of a four-transistor BUCK-BOOST circuit comprises a power supply input end, a voltage output end and four power MOSFETs: a power MOSFET Q1, a power MOSFET Q2, a power MOSFET Q3 and a power MOSFET Q4, wherein said power MOSFET Q1 and said power MOSFET Q2 are complementarily conducting, said power MOSFET Q3 and said power MOSFET Q4 are complementarily conducting, an input terminal of said power MOSFET Q1 is connected to a positive terminal of said input power, an output terminal of said power MOSFET Q2 is connected to a negative terminal of said power input terminal, an output terminal of said power MOSFET Q4 is connected to a negative terminal of said voltage output terminal, and an input terminal of said power MOSFET Q3 is connected to a positive terminal of said voltage output terminal, wherein said control method comprises:

acquiring an actual output voltage value of the four-tube BUCK-BOOST circuit;

when the four-transistor BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, adjusting the four-transistor BUCK-BOOST circuit to a phase-shifting control mode, wherein the rated load state represents that the four-transistor BUCK-BOOST circuit is in a full-load state, and in the phase-shifting control mode, a phase-shifting angle between the power MOSFET Q4 and the power MOSFET Q1 is increased, so that the output current is reduced; the value of the phase shift angle between said power MOSFET Q4 and said power MOSFET Q1 is inversely related to the current value of said output current;

in the phase-shifting control mode, if the actual output voltage value overshoots, the four-tube BUCK-BOOST circuit is adjusted to a width modulation control mode, and in the width modulation control mode, the duty ratios of the power MOSFET Q1 and the power MOSFET Q3 are reduced in an equal proportion, so that the output current is reduced; the duty ratios of the power MOSFET Q1 and the power MOSFET Q3 are in a positive correlation with the current value of the output current by a multiple of proportional change.

2. The method of claim 1, wherein adjusting the four-pipe BUCK-BOOST circuit to the phase shift control mode when the four-pipe BUCK-BOOST circuit is in the nominal load state and the actual output voltage value overshoots comprises:

when the four-tube BUCK-BOOST circuit is in the rated load state, judging whether the difference value between the actual output voltage value and the rated output voltage value is larger than a preset value or not;

and if so, determining the actual output voltage value overshoot, and adjusting the four-tube BUCK-BOOST circuit to a phase-shifting control mode.

3. The control method of claim 2, wherein said adjusting said four-pipe BUCK-BOOST circuit to a phase shift control mode comprises:

increasing the phase shift angle between the power MOSFET Q4 and the power MOSFET Q1 at a preset first rate such that the difference between the actual output voltage value and the nominal output voltage value is less than the preset value.

4. The method of claim 1, wherein adjusting the four-transistor BUCK-BOOST circuit to a width modulation control mode if the actual output voltage value overshoots in the phase shift control mode comprises:

when the phase shift angle reaches the maximum value and the actual output voltage value overshoots, the four-tube BUCK-BOOST circuit finishes the phase shift control mode and is adjusted to the width modulation control mode;

when the output voltage of the four-tube BUCK-BOOST circuit is larger than the input voltage, the maximum value is the value of the duty ratio of the power MOSFET Q2;

when the output voltage of the four-tube BUCK-BOOST circuit is smaller than the input voltage, the maximum value is the value of the duty ratio of the power MOSFET Q4.

5. The control method of claim 4, wherein adjusting the four-pipe BUCK-BOOST circuit to a bandwidth-modulated control mode comprises:

the duty cycle of the power MOSFET Q1 and the duty cycle of the power MOSFET Q3 are proportionally reduced at a preset second rate such that the error between the actual output voltage value and the nominal output voltage value is less than a preset value.

6. The control method according to any one of claims 1 to 5, wherein the voltage transfer ratio of the four-pipe BUCK-BOOST circuit is calculated by the formula:

the P is used for representing the voltage transmission ratio of the four-tube BUCK-BOOST circuit, and the D is used for_Q1For indicating the duty cycle of the power MOSFET Q1, D_Q2For indicating the duty cycle of the power MOSFET Q2, D_Q3For indicating the duty cycle of the power MOSFET Q3, D_Q4For indicating the duty cycle of the power MOSFET Q4.

7. The control method of claim 1, wherein the four-transistor BUCK-BOOST circuit employs a full-load inductor current critical continuous BCM modulation control mode when the four-transistor BUCK-BOOST circuit is in the nominal load state.

8. A control circuit for controlling a four-transistor BUCK-BOOST circuit, the four-transistor BUCK-BOOST circuit comprising a power input terminal, a voltage output terminal, and four power MOSFETs: a power MOSFET Q1, a power MOSFET Q2, a power MOSFET Q3 and a power MOSFET Q4, wherein the power MOSFET Q1 and the power MOSFET Q2 are complementarily conductive, the power MOSFET Q3 and the power MOSFET Q4 are complementarily conductive, an input terminal of the power MOSFET Q1 is connected to a positive terminal of the input power, an output terminal of the power MOSFET Q2 is connected to a negative terminal of the input power, an output terminal of the power MOSFET Q4 is connected to a negative terminal of the voltage output, and an input terminal of the power MOSFET Q3 is connected to a positive terminal of the voltage output, wherein the control circuit includes a voltage detection circuit and a pulse width modulation PWM control circuit, and the control circuit includes:

the voltage detection circuit is used for acquiring the actual output voltage value of the four-tube BUCK-BOOST circuit;

the PWM control circuit is configured to receive the actual output voltage value detected by the voltage detection circuit, and determine that when the four-transistor BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots, a first control signal in a phase-shift modulation mode is output to the four-transistor BUCK-BOOST circuit to control the four-transistor BUCK-BOOST circuit to operate in a phase-shift control mode, where the rated load state indicates that the four-transistor BUCK-BOOST circuit is in a full load state, and in the phase-shift control mode, a phase-shift angle between the power MOSFET Q4 and the power MOSFET Q1 is increased, so that an output current is decreased; the value of the phase shift angle between the power MOSFET Q4 and the power MOSFET Q1 is inversely related to the current value of the output current;

in the phase-shift control mode, the PWM control circuit is further configured to receive an actual output voltage value detected by the voltage detection circuit, and determine that if the actual output voltage value overshoots, a second control signal in a width modulation control mode is output to the four-transistor BUCK-BOOST circuit to control the four-transistor BUCK-BOOST circuit to operate in the width modulation control mode, in which duty ratios of the power MOSFET Q1 and the power MOSFET Q3 are proportionally reduced to reduce the output current; the duty ratios of the power MOSFET Q1 and the power MOSFET Q3 are in a positive correlation with the current value of the output current by a multiple of proportional change.

9. The control circuit of claim 8, wherein the PWM control circuit comprises a first comparison circuit and a first adjustment circuit, comprising:

the first comparison circuit is used for receiving an actual output voltage value output by the voltage detection circuit when the four-tube BUCK-BOOST circuit is in the rated load state, and judging whether a difference value between the actual output voltage value and the rated output voltage value is larger than a preset value or not; if yes, outputting a first trigger signal to the first adjusting circuit;

the first adjusting circuit is configured to receive the first trigger signal output by the first comparing circuit, and output the first control signal to the four-transistor BUCK-BOOST circuit according to the first trigger signal, so as to control the four-transistor BUCK-BOOST circuit to operate in a phase-shift control mode.

10. The control circuit of claim 9 wherein the first control signal is used to instruct the four-transistor BUCK-BOOST circuit to increase the phase shift angle between the power MOSFET Q4 and the power MOSFET Q1 at a preset first rate such that the difference between the actual output voltage value and the nominal output voltage value is less than the preset value.

11. The control circuit of claim 8, wherein the PWM control circuit comprises a second comparison circuit and a second adjustment circuit,

the second comparison circuit is used for receiving the actual output voltage value output by the voltage detection circuit when the four-tube BUCK-BOOST circuit works in the phase-shifting control mode; if the second comparison circuit determines that the phase shift angle reaches the maximum value according to the actual output voltage value and the actual output voltage value overshoots, a second trigger signal is output to the second adjusting circuit;

the second adjusting circuit is configured to receive the second trigger signal output by the second comparing circuit, and output the second control signal to the four-transistor BUCK-BOOST circuit according to the second trigger signal, so as to control the four-transistor BUCK-BOOST circuit to end the phase shift control mode and adjust to the width modulation control mode;

12. The control circuit of claim 11 wherein the second control signal is used to instruct the four-transistor BUCK-BOOST circuit to proportionally reduce the duty cycle of the power MOSFET Q1 and the duty cycle of the power MOSFET Q3 at a preset second rate such that the error between the actual output voltage value and the nominal output voltage value is less than a preset value.

13. The control circuit according to any one of claims 8 to 12, wherein the voltage transfer ratio of the four-pipe BUCK-BOOST circuit is calculated by the formula:

the P is used for representing the voltage transmission ratio of the four-tube BUCK-BOOST circuit, and the D is used for_Q1For representingDuty cycle of the power MOSFET Q1, D_Q2For indicating the duty cycle of the power MOSFET Q2, D_Q3For indicating the duty cycle of the power MOSFET Q3, D_Q4For indicating the duty cycle of the power MOSFET Q4.

14. The control circuit of claim 8, wherein the four-transistor BUCK-BOOST circuit employs a full-load inductor current critical continuous BCM modulation control mode when the four-transistor BUCK-BOOST circuit is in the nominal load state.

15. A control system of a four-transistor BUCK-BOOST circuit, the four-transistor BUCK-BOOST circuit comprises a power input end, a voltage output end and four power MOSFETs: a power MOSFET Q1, a power MOSFET Q2, a power MOSFET Q3 and a power MOSFET Q4, wherein said power MOSFET Q1 and said power MOSFET Q2 are complementarily conducting, said power MOSFET Q3 and said power MOSFET Q4 are complementarily conducting, an input terminal of said power MOSFET Q1 is connected to a positive terminal of said input power supply, an output terminal of said power MOSFET Q2 is connected to a negative terminal of said power supply input terminal, an output terminal of said power MOSFET Q4 is connected to a negative terminal of said voltage output terminal, and an input terminal of said power MOSFET Q3 is connected to a positive terminal of said voltage output terminal, wherein said control system comprises:

the acquisition module is used for acquiring the actual output voltage value of the four-tube BUCK-BOOST circuit;

a mode selection module for adjusting the four-transistor BUCK-BOOST circuit to a phase shift control mode in which a phase shift angle between the power MOSFET Q4 and the power MOSFET Q1 is increased such that an output current is reduced when the four-transistor BUCK-BOOST circuit is in a rated load state and the actual output voltage value overshoots; the value of the phase shift angle between the power MOSFET Q4 and the power MOSFET Q1 is inversely related to the current value of the output current;

the mode selection module is further configured to adjust the four-transistor BUCK-BOOST circuit to a width modulation control mode if the actual output voltage value overshoots in the phase shift control mode, and in the width modulation control mode, duty ratios of the power MOSFET Q1 and the power MOSFET Q3 are reduced in an equal proportion, so that the output current is reduced; the duty ratio of the power MOSFET Q1 and the power MOSFET Q3 is in a positive correlation with the current value of the output current by a multiple of equal proportional change.

16. The control system of claim 15, wherein the mode selection module specifically comprises:

the judging unit is used for judging whether the difference value between the actual output voltage value and the rated output voltage value is larger than a preset value or not when the four-tube BUCK-BOOST circuit is in a rated load state;

and if so, the first adjusting unit is used for adjusting the four-tube BUCK-BOOST circuit to a phase-shifting control mode.

17. The control system according to claim 16, wherein the first adjusting unit is specifically configured to:

18. The control system of claim 15, wherein the mode selection module specifically comprises:

the second adjusting unit is used for ending the phase shift control mode and adjusting the four-tube BUCK-BOOST circuit to the width modulation control mode when the phase shift angle reaches the maximum value and the actual output voltage value overshoots;

19. The control system according to claim 18, wherein the second adjustment unit is specifically configured to:

20. The control system according to any one of claims 15 to 19, wherein the voltage transfer ratio of the four-pipe BUCK-BOOST circuit is calculated by the formula:

21. The control system of claim 15, wherein the four-pipe BUCK-BOOST circuit employs a full-load inductor current critical continuous BCM modulation control mode when the four-pipe BUCK-BOOST circuit is in the nominal load state.

22. A chip apparatus, comprising:

a processor and a memory;

the memory includes instructions that are executed by the processor to cause the chip arrangement to implement the method of any one of claims 1 to 7.

23. A computer-readable storage medium comprising instructions which, when executed on a computer, cause the computer to perform the method of any one of claims 1 to 7.