WO2023273300A1

WO2023273300A1 - Method and system for smoothly switching modes of buck-boost circuit

Info

Publication number: WO2023273300A1
Application number: PCT/CN2022/071614
Authority: WO
Inventors: 徐彦忠; 沈志峰; 于玮
Original assignee: 易事特集团股份有限公司
Priority date: 2021-06-30
Filing date: 2022-01-12
Publication date: 2023-01-05
Also published as: CN113472199A; CN113472199B

Abstract

A method and system for smoothly switching modes of a buck-boost circuit. The method comprises: acquiring a duty ratio D that is output by a control loop connected to a buck-boost circuit; and providing the duty ratio D to a fourth MOSFET, providing a duty ratio 1-D to a third MOSFET, providing a duty ratio 1+D to a first MOSFET, and providing a duty ratio -D to a second MOSFET, such that the modes of the buck-boost circuit are automatically and smoothly switched. By means of the method and system for smoothly switching modes of a buck-boost circuit that are provided in the present application, value assignment is respectively performed on each MOSFET according to a duty ratio that is output by a control loop, such that adaptive smooth switching between a buck mode, a boost mode and a buck-boost mode can be realized without the need for other conditions, and an output voltage is stable.

Description

Buck-Boost circuit mode smooth switching method and system

technical field

The present application relates to the technical field of Buck-Boost circuits, in particular to a method and system for smooth mode switching of Buck-Boost circuits.

Background technique

The four-switch Buck-boost converter has attracted people's attention since it was proposed due to its advantages such as low switching loss and adjustable output voltage. It has become a DC/DC circuit topology that has been widely used in recent years.

At present, when the four-switch Buck-Boost circuit adopts the traditional control method to switch from the Buck mode and the Boost mode to the Buck-Boost mode, the output voltage will jump at the switching point, and the smooth switching of the three modes cannot be achieved. Moreover, the traditional method uses the condition of the output voltage to determine which mode it is. If the condition is unreasonable, it will cause the three modes to switch back and forth, resulting in a jump in the output voltage.

Therefore, how to provide a new four-switch Buck-Boost circuit control technology is one of the important topics in this field.

The above information is presented as background information only to aid in understanding the present disclosure, and it is not a determination or admission that any of the above might be available as prior art with respect to the present disclosure.

application content

The present application provides a mode smooth switching method and system of a Buck-Boost circuit to solve the deficiencies in the prior art.

In order to achieve the above object, the application provides the following technical solutions:

In the first aspect, the embodiment of the present application provides a mode smooth switching method of a Buck-Boost circuit, the Buck-Boost circuit is a four-switch Buck-Boost circuit, including a power input terminal, a voltage output terminal, a first MOSFET tube, a second Two MOSFET tubes, a third MOSFET tube, a fourth MOSFET tube, a filter inductor, an input filter capacitor and an output filter capacitor, the input end of the first MOSFET tube is connected to the positive pole of the power supply input end, and the input end of the first MOSFET tube is The output end is connected to the input end of the second MOSFET, the output end of the second MOSFET is connected to the negative pole of the power input end, the input end of the third MOSFET is connected to the positive pole of the voltage output end, The output end of the third MOSFET is connected to the input end of the fourth MOSFET, the output end of the fourth MOSFET is connected to the negative pole of the voltage output end, and the filter inductor is connected to the first MOSFET Between the output terminal of the transistor and the output terminal of the third MOSFET tube, the input filter capacitor is connected between the positive pole and the negative pole of the power supply input terminal, and the output filter capacitor is connected between the positive pole and the negative pole of the voltage output terminal Between, the method includes:

Obtain the duty ratio D of the control loop output connected with the Buck-Boost circuit;

Assigning a duty cycle D to the fourth MOSFET, assigning a duty cycle 1-D to the third MOSFET, assigning a duty cycle 1+D to the first MOSFET, and assigning a duty cycle Ratio -D is assigned to the second MOSFET tube, so as to automatically and smoothly switch the mode of the Buck-Boost circuit.

Further, in the mode smooth switching method of the Buck-Boost circuit, the method also includes:

If the dead zone Dead_Time of the third MOSFET satisfies D≤Dead_Time and PreD≤Dead_Time, modify the dead zone Dead_Time of the third MOSFET so that the drive of the third MOSFET transitions smoothly;

Among them, PreD is the duty cycle of the previous beat.

Further, in the mode smooth switching method of the Buck-Boost circuit, the calculation formula when modifying the dead zone Dead_Time of the third MOSFET is Dead_Time=2*D.

If the dead zone Dead_Time of the first MOSFET satisfies -D≤Dead_Time and -PreD≤Dead_Time, modify the dead zone Dead_Time of the first MOSFET so that the driving of the first MOSFET transitions smoothly;

Among them, PreD is the duty cycle of the previous beat.

Further, in the mode smooth switching method of the Buck-Boost circuit, the calculation formula for modifying the dead zone Dead_Time of the first MOSFET is Dead_Time=-2*D.

In the second aspect, an embodiment of the present application provides a mode smooth switching system of a Buck-Boost circuit, the system comprising:

A duty ratio acquisition module, configured to obtain the duty ratio D of the control loop output connected to the Buck-Boost circuit;

The duty ratio given module is used to assign the duty ratio D to the fourth MOSFET, assign the duty ratio 1-D to the third MOSFET, and assign the duty ratio 1+D to the The first MOSFET tube, and assigning the duty ratio -D to the second MOSFET tube realizes automatic and smooth switching of the mode of the Buck-Boost circuit.

Further, in the mode smooth switching system of the Buck-Boost circuit, the system also includes a first modification module:

Among them, PreD is the duty cycle of the previous beat.

Further, in the mode smooth switching system of the Buck-Boost circuit, the calculation formula of the first modifying module when modifying the dead zone Dead_Time of the third MOSFET is Dead_Time=2*D.

Further, in the mode smooth switching system of the Buck-Boost circuit, the system also includes a second modification module:

Among them, PreD is the duty cycle of the previous beat.

Further, in the mode smooth switching system of the Buck-Boost circuit, the calculation formula of the second modifying module when modifying the dead zone Dead_Time of the first MOSFET is Dead_Time=-2*D.

The Buck-Boost circuit mode smooth switching method and system provided in the embodiment of the present application assign values to each MOSFET tube according to the duty cycle output by the control loop, so that Buck mode, Boost mode, Buck-Boost mode, and Buck-Boost mode can be realized without other conditions. Boost mode The adaptive smooth switching of these three modes, and the output voltage is stable.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present application. Those skilled in the art can also obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a circuit schematic diagram of a four-switch Buck-Boost circuit provided in Embodiment 1 of the present application;

FIG. 2 is a schematic flow diagram of a mode smooth switching method for a Buck-Boost circuit provided in Embodiment 1 of the present application;

FIG. 3 is a schematic diagram of functional modules of a Buck-Boost circuit mode smooth switching system provided in Embodiment 2 of the present application.

detailed description

In order to make the purpose, features, and advantages of the application more obvious and understandable, the technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the application. Obviously, the following description The embodiments are only some of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

In the description of this application, it is to be understood that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be an intervening component at the same time. When a component is said to be "set on" another component, it can be set directly on another component or there may be a centered component at the same time.

In addition, the terms "long", "short", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, rather than indicating or implying the referred device Or that the original must have this particular orientation, operate in a particular orientation configuration, and this should not be construed as a limitation of this application.

The technical solution of the present application will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

Embodiment one

In view of the above-mentioned defects existing in the existing Buck-Boost circuit control technology, the applicant actively conducts research and innovation based on years of rich practical experience and professional knowledge in this field, and cooperates with the application of academic theory, hoping to create a solution that can solve the existing problems. The flawed technology in the technology makes the Buck-Boost circuit control technology more practical. Through continuous research, design, and after repeated trial-making samples and improvements, the application with real practical value is finally created.

Please refer to Fig. 2, the embodiment of the present application provides a mode smooth switching method of a Buck-Boost circuit, the Buck-Boost circuit is a four-switch Buck-Boost circuit, as shown in Fig. 1, the four-switch Buck-Boost circuit Including power supply input terminal, voltage output terminal, first MOSFET tube Q1, second MOSFET tube Q2, third MOSFET tube Q3, fourth MOSFET tube Q4, filter inductor L1, input filter capacitor C1 and output filter capacitor C2, the first The input end of a MOSFET Q1 is connected to the positive pole BAT+ of the power supply input end, the output end of the first MOSFET Q1 is connected to the input end of the second MOSFET Q2, and the output end of the second MOSFET Q2 It is connected to the negative pole BAT- of the power input terminal, the input terminal of the third MOSFET Q3 is connected to the positive pole DC+ of the voltage output terminal, and the output terminal of the third MOSFET Q3 is connected to the fourth MOSFET Q4. The input end is connected, the output end of the fourth MOSFET Q4 is connected to the negative pole of the voltage output end DC-, and the filter inductor L1 is connected between the output end of the first MOSFET Q1 and the third MOSFET Between the output terminals of Q3, the input filter capacitor C1 is connected between the positive pole BAT+ and the negative pole BAT- of the power input terminal, and the output filter capacitor C2 is connected between the positive pole DC+ and the negative pole DC- of the voltage output terminal , the method includes:

S101. Obtain a duty cycle D output by a control loop connected to the Buck-Boost circuit.

S102. Assign a duty ratio D to the fourth MOSFET Q4, assign a duty ratio 1-D to the third MOSFET Q3, and assign a duty ratio 1+D to the first MOSFET Q1 , and assign the duty ratio -D to the second MOSFET tube Q2, so as to automatically and smoothly switch the mode of the Buck-Boost circuit.

It should be noted that, in this embodiment, according to the duty ratio D obtained from the final output of the control loop, the duty ratio D is assigned to the fourth MOSFET Q4, 1-D is assigned to the third MOSFET Q3, and 1-D is assigned to the first MOSFET Q4. The tube Q1 is assigned a value of 1+D, and the second MOSFET tube Q2 is assigned a value of -D. By assigning a duty cycle according to this method, the adaptive smooth switching of the three modes of Buck mode, Boost mode, and Buck-Boost mode can be realized, so that there is no It is necessary to switch modes based on the output voltage as a condition, and the output voltage is stable.

In addition, due to the dead zone in the traditional complementary wave transmission method of the upper and lower tubes, it is impossible to obtain a full duty cycle, and this circuit topology requires a full duty cycle when the input and output voltages are equal. If there is a 5% dead zone If the duty cycle can only be 95%, then when the duty cycle is greater than 95%, if the upper tube is constant, its duty cycle will jump directly from 95% to 100%, resulting in the output current when the input and output voltages are close fluctuation. Therefore, in this embodiment, the method also includes:

If the dead zone Dead_Time of the third MOSFET Q3 satisfies D≤Dead_Time and PreD≤Dead_Time, modify the dead zone Dead_Time of the third MOSFET Q3 so that the drive of the third MOSFET Q3 is smoothly transitioned;

Among them, PreD is the duty cycle of the previous beat.

Moreover, the calculation formula when modifying the dead zone Dead_Time of the third MOSFET tube Q3 is Dead_Time=2*D.

Modifying the dead zone Dead_Time of the first MOSFET tube Q1 based on the same theory, that is, in this embodiment, the method further includes:

If the dead zone Dead_Time of the first MOSFET Q1 satisfies -D≤Dead_Time and -PreD≤Dead_Time, then modify the dead zone Dead_Time of the first MOSFET Q1 so that the drive of the first MOSFET Q1 has a smooth transition ;

Among them, PreD is the duty cycle of the previous beat.

Moreover, the calculation formula for modifying the dead zone Dead_Time of the first MOSFET Q1 is Dead_Time=-2*D.

It should be noted that, by modifying the dead zones Dead_Time of the first MOSFET Q1 and the third MOSFET Q3 through the above method, the driving of the first MOSFET Q1 and the third MOSFET Q3 can be smoothly transitioned. There will be a phenomenon that the duty cycle jumps

The mode smooth switching method of the Buck-Boost circuit provided in the embodiment of the present application assigns values to each MOSFET tube according to the duty cycle output by the control loop, so that Buck mode, Boost mode, and Buck-Boost mode can be realized without other conditions These three modes are adaptively switched smoothly, and the output voltage is stable.

Embodiment two

Please refer to FIG. 3 . Embodiment 2 of the present application provides a mode smooth switching system of a Buck-Boost circuit, which is suitable for implementing the method for smooth mode switching of the Buck-Boost circuit provided in the embodiment of the present application. The system specifically includes the following modules:

A duty cycle acquisition module 201, configured to obtain a duty cycle D of a control loop output connected to the Buck-Boost circuit;

The duty ratio given module 202 is used to assign the duty ratio D to the fourth MOSFET, assign the duty ratio 1-D to the third MOSFET, and assign the duty ratio 1+D to the fourth MOSFET. The first MOSFET tube, and the duty ratio -D is assigned to the second MOSFET tube, so as to automatically and smoothly switch the mode of the Buck-Boost circuit.

Preferably, the system also includes a first modification module:

Among them, PreD is the duty cycle of the previous beat.

Preferably, the calculation formula of the first modifying module when modifying the dead zone Dead_Time of the third MOSFET is Dead_Time=2*D.

Preferably, the system also includes a second modification module:

Among them, PreD is the duty cycle of the previous beat.

Preferably, the calculation formula of the second modification module when modifying the dead zone Dead_Time of the first MOSFET is Dead_Time=-2*D.

The mode smooth switching system of the Buck-Boost circuit provided in the embodiment of the present application assigns values to each MOSFET tube according to the duty cycle output by the control loop, so that Buck mode, Boost mode, and Buck-Boost mode can be realized without other conditions These three modes are adaptively switched smoothly, and the output voltage is stable.

The description thus far of the foregoing embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and used in a selected embodiment, even if not specifically shown or described. In many respects, the same elements or features may also be varied. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous details are set forth, such as examples of specific parts, devices and methods, in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and no limitation is intended. As used herein, the singular forms "a" and "the" may be meant to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprising" and "having" are inclusive and thus specify the presence of stated features, integers, steps, operations, elements and/or components, but do not exclude the presence or additional presence of one or more other features , as a whole, steps, operations, elements, components and/or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring performance in the specific order discussed and illustrated, unless an order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be employed.

When an element or layer is referred to as being "on," "bonded to," "connected to," or "coupled to" another element or layer, it can be directly on, or in contact with, another element or layer. An element or layer may be bonded, connected or coupled to another element or layer, and intervening elements or layers may also be present. In contrast, when an element or layer is referred to as being "directly on," "directly engaged with," "directly connected to," or "directly coupled to" another element or layer, there may not be intervening elements or layers in between. Other words used to describe the relationship between elements should be interpreted in a like fashion (eg, "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections are not constrained by these terms. limit. These terms may be only used to distinguish one element, component, region or section from another element, component, region or section. Terms such as the terms "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

Spatial relative terms, such as "inside", "outside", "underneath", "beneath", "below", "above", "upper", etc., may be used herein for convenience of description , to describe the relationship between one element or feature and one or more other elements or features as shown in the figures. Spatially relative terms may be meant to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below" can encompass both an orientation of upward and downward. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and interpreted in terms of the spatially relative descriptions herein.

Claims

A mode smooth switching method of a Buck-Boost circuit, the Buck-Boost circuit is a four-switch Buck-Boost circuit, comprising a power input terminal, a voltage output terminal, a first MOSFET tube, a second MOSFET tube, a third MOSFET tube, A fourth MOSFET tube, a filter inductor, an input filter capacitor and an output filter capacitor, the input end of the first MOSFET tube is connected to the positive pole of the power supply input end, the output end of the first MOSFET tube is connected to the positive pole of the second MOSFET tube connected to the input end of the second MOSFET, the output end of the second MOSFET is connected to the negative pole of the power input end, the input end of the third MOSFET is connected to the positive pole of the voltage output end, and the output end of the third MOSFET connected to the input terminal of the fourth MOSFET tube, the output terminal of the fourth MOSFET tube is connected to the negative pole of the voltage output terminal, and the filter inductor is connected to the output terminal of the first MOSFET tube and the third Between the output terminals of the MOSFET tubes, the input filter capacitor is connected between the positive pole and the negative pole of the power input terminal, and the output filter capacitor is connected between the positive pole and the negative pole of the voltage output terminal, wherein the Methods include:

Obtain the duty ratio D of the control loop output connected with the Buck-Boost circuit;

Give the duty ratio D to the fourth MOSFET, assign the duty ratio 1-D to the third MOSFET, assign the duty ratio 1+D to the first MOSFET, and assign the duty ratio-D For the second MOSFET tube, automatic and smooth switching of the mode of the Buck-Boost circuit is realized.
The mode smooth switching method of Buck-Boost circuit according to claim 1, is characterized in that, described method also comprises:

If the dead zone Dead_Time of the third MOSFET satisfies D≤Dead_Time and PreD≤Dead_Time, modify the dead zone Dead_Time of the third MOSFET so that the drive of the third MOSFET transitions smoothly;

Among them, PreD is the duty cycle of the previous beat.
The mode smooth switching method of the Buck-Boost circuit according to claim 2, characterized in that the calculation formula for modifying the dead zone Dead_Time of the third MOSFET is Dead_Time=2*D.
The mode smooth switching method of Buck-Boost circuit according to claim 1, is characterized in that, described method also comprises:

If the dead zone Dead_Time of the first MOSFET satisfies -D≤Dead_Time and -PreD≤Dead_Time, modify the dead zone Dead_Time of the first MOSFET so that the driving of the first MOSFET transitions smoothly;

Among them, PreD is the duty cycle of the previous beat.
The mode smooth switching method of the Buck-Boost circuit according to claim 4, characterized in that the calculation formula when modifying the dead zone Dead_Time of the first MOSFET tube is Dead_Time=-2*D.
A mode smooth switching system of a Buck-Boost circuit, the system comprising:

A duty ratio acquisition module, configured to obtain the duty ratio D of the control loop output connected to the Buck-Boost circuit;

The duty ratio given module is used to assign the duty ratio D to the fourth MOSFET, assign the duty ratio 1-D to the third MOSFET, and assign the duty ratio 1+D to the first MOSFET tube, and the duty ratio -D is given to the second MOSFET tube to automatically and smoothly switch the mode of the Buck-Boost circuit.
The mode smooth switching system of Buck-Boost circuit according to claim 6, is characterized in that, described system also comprises the first modification module:

If the dead zone Dead_Time of the third MOSFET satisfies D≤Dead_Time and PreD≤Dead_Time, modify the dead zone Dead_Time of the third MOSFET so that the drive of the third MOSFET transitions smoothly;

Among them, PreD is the duty cycle of the previous beat.
The mode smooth switching system of a Buck-Boost circuit according to claim 7, wherein the calculation formula of the first modifying module when modifying the dead zone Dead_Time of the third MOSFET is Dead_Time=2*D.
The mode smooth switching system of Buck-Boost circuit according to claim 6, is characterized in that, described system also comprises the second modification module:

If the dead zone Dead_Time of the first MOSFET satisfies -D≤Dead_Time and -PreD≤Dead_Time, modify the dead zone Dead_Time of the first MOSFET so that the driving of the first MOSFET transitions smoothly;

Among them, PreD is the duty cycle of the previous beat.
The mode smooth switching system of the Buck-Boost circuit according to claim 9, wherein the calculation formula of the second modification module when modifying the dead zone Dead_Time of the first MOSFET tube is Dead_Time=-2*D .