A method for switching dual-switch Buck-Boost circuit modes

Abstract

A method for switching the mode of a dual-tube Buck-Boost circuit relates to the field of circuit switching. The purpose of the present invention is to solve the problem of complex switching methods of existing Buck-Boost circuit modes, collect the output voltage of IGBT switch tube S1 and the output voltage of IGBT switch tube S2, and obtain the duty cycle d of IGBT switch tube S1 and S2 respectively. buck and the duty cycle d of the IGBT switch tube S2 boost ; Determine whether 1‑d boost ‑d buck <0, if yes, make the duty cycle d of IGBT switch tube S1 buck =1, and adjust the duty cycle d of the IGBT switch tube S2 according to the voltage reference value and the output voltage of the IGBT switch tube S2 boost , it is in boost mode at this time, if not, the duty cycle of IGBT switch S2 is d boost =0, and adjust the duty cycle d of the IGBT switch tube S1 according to the voltage reference value and the output voltage of the IGBT switch tube S1 buck , which is the buck mode. The present invention is used to smoothly implement buck-boost switching.

Description

Technical Field

[0001] The present invention relates to the field of circuit switching and belongs to circuit mode switching technology. Background Art

[0002] Because the dual-switch buck-boost circuit has a simple operating principle and can achieve buck-boost functionality, it is suitable for control over a wide range of input and output voltages. However, due to its two degrees of freedom, the dual-switch buck-boost circuit has a variety of control strategies, and different modes have different output characteristics, resulting in varying circuit output efficiency. To achieve both buck-boost functionality and improve circuit efficiency, buck-boost mode switching can effectively reduce the significant stress on the inductor current, minimize circuit damage, and lower the requirements for power switching devices. However, achieving mode prediction and smooth switching is a challenge, making it a hot research topic. Currently, there are two main approaches to achieving mode switching: one determines the circuit mode based on the input and output voltages, but this approach is complex to implement and difficult to achieve smooth mode switching. The other approach uses dual modulation waveforms with a single carrier or single modulation waveform with a dual carrier. This approach does achieve smooth mode switching, but to improve waveform quality, it often requires a dual closed-loop control strategy or an input voltage feedforward control strategy, which is complex to implement, especially in digital circuits. Therefore, there is a need to find a smooth mode switching strategy that is simple to control, efficient, and easy to implement. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem of complex switching mode of the existing Buck-Boost circuit, and propose a method for switching the mode of a dual-switch Buck-Boost circuit.

[0004] A method for switching a dual-tube Buck-Boost circuit mode, wherein the dual-tube Buck-Boost circuit includes IGBT switch tubes S1-S2, an inductor I L , diodes D1-D2, resistor R, electrolytic capacitor C and DC power supply u dc ;

[0005] DC power supply dc The positive electrode is connected to the drain of IGBT switch tube S1, and the DC power supply u dc The negative electrode of the diode D1 is connected to the anode of the diode D1, the source of the IGBT switch tube S2, the negative electrode of the electrolytic capacitor C and one end of the resistor R; the cathode of the diode D1 is connected to the source of the IGBT switch tube S1 and the inductor I L One end of the inductor I LThe other end of the diode is connected to the anode of the diode D2 and the drain of the IGBT switch tube S2 at the same time, and the cathode of the diode D2 is connected to the positive electrode of the electrolytic capacitor C and the other end of the resistor R at the same time;

[0006] The method includes the following:

[0007] Step 1: Collect the output voltage of IGBT switch tube S1 and the output voltage of IGBT switch tube S2, and obtain the duty cycle d of IGBT switch tube S1. buck and the duty cycle d of the IGBT switch tube S2 boost ;

[0008] Step 2: Determine whether it is 1-d boost -d buck <0, if yes, go to step 3, if no, go to step 4;

[0009] Step 3: Switch to boost mode, specifically: make the duty cycle of IGBT switch S1 d buck =1, and adjust the duty cycle d of the IGBT switch tube S2 according to the voltage reference value and the output voltage of the IGBT switch tube S2 boost ;

[0010] Step 4: Switch to step-down mode, specifically: make the duty cycle of IGBT switch S2 d boost =0, and adjust the duty cycle d of the IGBT switch tube S1 according to the voltage reference value and the output voltage of the IGBT switch tube S1 buck .

[0011] Preferably, in step 1, a voltage sensor is used to collect the output voltage of the IGBT switch tube S1 and the output voltage of the IGBT switch tube S2.

[0012] Preferably, step 3 further includes: the No. 1 PI controller generates a PWM control signal according to the difference between the voltage reference value and the output voltage of the IGBT switch tube S2, and sends it to the No. 1 driver, and the No. 1 driver adjusts the duty cycle of the IGBT switch tube S2 according to the PWM control signal.

[0013] Preferably, step 4 further includes: the second PI controller generates a PWM control signal according to the difference between the voltage reference value and the output voltage of the IGBT switch tube S1, and sends it to the second driver, and the second driver adjusts the duty cycle of the IGBT switch tube S1 according to the PWM control signal.

[0014] The beneficial effects of the present invention are:

[0015] The present invention mainly focuses on the dual-tube Buck-Boost circuit and designs a new control strategy. While enabling the circuit to have the function of stepping up and down the voltage, it can also realize advanced predictive control and thus achieve smooth mode switching. At the same time, different control parameters are adopted for different modes to achieve better output smoothness, and the switching method of the present invention is simple.

[0016] The present invention adopts two degrees of freedom control. When controlling the boost, one degree of freedom controls the duty cycle d of S1. buck =1, another degree of freedom controls the duty cycle of S2 d boost , when controlling the pressure drop, one degree of freedom controls d boost =0, another degree of freedom controls the duty cycle of S1 d buck ,Due to the advance prediction of the mode, different modes can use different ,adjustment parameters to achieve the optimal output performance and minimize ,circuit power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the schematic diagram of the dual-tube Buck-Boost circuit;

[0018] Figure 2 A control block diagram of a method for switching a dual-switch Buck-Boost circuit mode. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0022] Example:

[0023] Combine Figure 1 and Figure 2 This embodiment describes a method for switching a dual-tube Buck-Boost circuit mode. The dual-tube Buck-Boost circuit includes IGBT switches S1-S2, an inductor I L , diodes D1-D2, resistor R, electrolytic capacitor C and DC power supply u dc ;

[0024] DC power supply dc The positive electrode is connected to the drain of IGBT switch tube S1, and the DC power supply u dc The negative electrode of the diode D1 is connected to the anode of the diode D1, the source of the IGBT switch tube S2, the negative electrode of the electrolytic capacitor C and one end of the resistor R; the cathode of the diode D1 is connected to the source of the IGBT switch tube S1 and the inductor I L One end of the inductor I L The other end of the diode is connected to the anode of the diode D2 and the drain of the IGBT switch tube S2 at the same time, and the cathode of the diode D2 is connected to the positive electrode of the electrolytic capacitor C and the other end of the resistor R at the same time;

[0025] The method includes the following:

[0026] Step 1: Collect the output voltage of IGBT switch tube S1 and the output voltage of IGBT switch tube S2, and obtain the duty cycle d of IGBT switch tube S1. buck and the duty cycle d of the IGBT switch tube S2 boost ;

[0027] Step 2: Determine whether it is 1-d boost -d buck <0, if yes, go to step 3, if no, go to step 4;

[0028] Step 3: Switch to boost mode, specifically: make the duty cycle of IGBT switch S1 d buck =1, and adjust the duty cycle d of the IGBT switch tube S2 according to the voltage reference value and the output voltage of the IGBT switch tube S2 boost ;

[0029] Step 4: Switch to step-down mode, specifically: make the duty cycle of IGBT switch S2 d boost =0, and adjust the duty cycle d of the IGBT switch tube S1 according to the voltage reference value and the output voltage of the IGBT switch tube S1 buck .

[0030] Specifically, according to the technical solution of this embodiment, a control program is formed. First, the duty cycle d of the IGBT switch tube S1 can be easily obtained in the digital circuit. buck and the duty cycle d of the IGBT switch tube S2 boost , according to the formula M = 1-d boost -d buck Perform advanced predictive control. When M<0, d buck =1, the duty cycle d is adjusted by feedback from the voltage reference value and the output voltage of the IGBT switch tube S2 boost , this is the boost mode; when M≥0, d boost=0, the duty cycle d is adjusted by feedback from the voltage reference value and the output voltage of the IGBT switch tube S1 buck , at this time it is buck mode; in boost mode, one set of adjustment parameters is used, and in buck mode, another set of adjustment parameters is used to achieve the optimal output waveform. This control logic only needs to collect the output voltage, and only needs a voltage sensor. The logic can be realized by a programmable control chip such as a single-chip microcomputer. In a control chip such as a single-chip microcomputer, it is easy to obtain the duty cycle feedback value, so no additional duty cycle acquisition circuit is required. Figure 1 The schematic diagram of the dual-tube Buck-Boost circuit is given in the attached Figure 2 Give the control block diagram.

[0031] The components used for collecting voltage are further defined below: In step 1, a voltage sensor is used to collect the output voltage of the IGBT switch tube S1 and the output voltage of the IGBT switch tube S2.

[0032] The following further defines step 3:

[0033] Step 3 also includes: the first PI controller generates a PWM control signal according to the difference between the voltage reference value and the output voltage of the IGBT switch tube S2, and sends it to the first driver. The first driver adjusts the duty cycle of the IGBT switch tube S2 according to the PWM control signal.

[0034] The following further defines step 4:

[0035] Step 4 also includes: the second PI controller generates a PWM control signal according to the difference between the voltage reference value and the output voltage of the IGBT switch tube S1, and sends it to the second driver. The second driver adjusts the duty cycle of the IGBT switch tube S1 according to the PWM control signal.

[0036] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A method for switching a dual-tube Buck-Boost circuit mode, wherein the dual-tube Buck-Boost circuit includes IGBT switches S1-S2, an inductor I L , diodes D1-D2, resistor R, electrolytic capacitor C and DC power supply u dc ; DC power supply dc The positive electrode is connected to the drain of IGBT switch tube S1, and the DC power supply u dc The negative electrode of the diode D1 is connected to the anode of the diode D1, the source of the IGBT switch tube S2, the negative electrode of the electrolytic capacitor C and one end of the resistor R; the cathode of the diode D1 is connected to the source of the IGBT switch tube S1 and the inductor I L One end of the inductor I L The other end of the diode is connected to the anode of the diode D2 and the drain of the IGBT switch tube S2 at the same time, and the cathode of the diode D2 is connected to the positive electrode of the electrolytic capacitor C and the other end of the resistor R at the same time; It is characterized in that The method includes the following: Step 1: Collect the output voltage of IGBT switch tube S1 and the output voltage of IGBT switch tube S2, and obtain the duty cycle d of IGBT switch tube S1. buck and the duty cycle d of the IGBT switch tube S2 boost ; Step 2: Determine whether it is 1-d boost -d buck <0, if yes, go to step 3, if no, go to step 4; Step 3: Switch to boost mode, specifically: make the duty cycle of IGBT switch S1 d buck =1, and adjust the duty cycle d of the IGBT switch tube S2 according to the voltage reference value and the output voltage of the IGBT switch tube S2 boost ; Step 4: Switch to step-down mode, specifically: make the duty cycle of IGBT switch S2 d boost =0, and adjust the duty cycle d of the IGBT switch tube S1 according to the voltage reference value and the output voltage of the IGBT switch tube S1 buck .

2. The method for switching the dual-switch Buck-Boost circuit mode according to claim 1, characterized in that: In step 1, a voltage sensor is used to collect the output voltage of the IGBT switch tube S1 and the output voltage of the IGBT switch tube S2.

3. The method for switching the dual-switch Buck-Boost circuit mode according to claim 1, characterized in that: Step 3 also includes: the first PI controller generates a PWM control signal according to the difference between the voltage reference value and the output voltage of the IGBT switch tube S2, and sends it to the first driver. The first driver adjusts the duty cycle of the IGBT switch tube S2 according to the PWM control signal.

4. The method for switching the dual-switch Buck-Boost circuit mode according to claim 1, wherein: Step 4 also includes: the second PI controller generates a PWM control signal according to the difference between the voltage reference value and the output voltage of the IGBT switch tube S1, and sends it to the second driver. The second driver adjusts the duty cycle of the IGBT switch tube S1 according to the PWM control signal.

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