CN103762841B - A kind of embedded single switch Buck-Boost converter - Google Patents

Abstract

The invention provides an embedded single-switch Buck-Boost converter. The present invention constitutes the main Buck-Boost converter with a DC power supply, a switch tube, a first capacitor, a second inductor, a second diode, a second capacitor and a load; , the first diode and the third diode form an embedded Buck-Boost converter. When the switch tube is turned on, the DC power supply charges the first inductor, the DC power supply and the first capacitor jointly charge the second inductor, and the second capacitor supplies power to the load; when the switch tube is turned off, the first inductor charges the first capacitor , while the second inductor supplies power to the second capacitor and the load. Only one switch tube is used to embed a Buck-Boost converter into another Buck-Boost converter, and the gain can reach D/(1-D) ² .

Description

An Embedded Single-Switch Buck-Boost Converter

technical field

The invention relates to the field of high-gain non-isolated DC-DC converters, in particular to an embedded single-switch Buck-Boost converter.

Background technique

In recent years, high-gain step-up DC-DC converters are widely used in UPS, distributed photovoltaic power generation and battery energy storage systems. At present, high-gain step-up DC-DC converters have switched capacitor type and switched inductor type. The voltage increase is realized by adding switched capacitors or inductors, and the circuit structure is also complicated. In addition, high gain can be achieved through isolation transformers or coupled inductors. However, the leakage inductance of transformers and coupled inductors is difficult to control, which will greatly increase the stress and energy loss of devices. In addition, the embedded DC-DC converter can achieve high gain, which is also very popular. If the basic Buck-Boost converter is embedded in another Buck-Boost converter, a simple high-gain cascaded structure can be obtained. Converter, but how to use a switching tube to achieve high-gain embedded converter is still a difficult problem.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and propose an embedded single-switch Buck-Boost converter.

The technical scheme adopted in the present invention is as follows.

An embedded single-switch Buck-Boost converter, the main Buck-Boost converter is composed of a DC power supply, a switch tube, a first capacitor, a second inductor, a second diode, a second capacitor and a load; The power supply, the switch tube, the first capacitor, the first inductor, the first diode and the third diode form an embedded Buck-Boost converter.

In the above-mentioned embedded single-switch Buck-Boost converter, the positive pole of the DC power supply is connected to the drain pole of the switch tube, the source pole of the switch tube is connected to the negative pole of the first capacitor and one end of the first inductor, and the The other end is connected to the anode of the first diode and the anode of the third diode, the cathode of the first diode is connected to the anode of the first capacitor, the cathode of the second diode, and one end of the second inductor. The other end of the second inductor is connected to the negative pole of the DC power supply, the cathode of the third diode, the positive pole of the second capacitor and one end of the load, and the other end of the load is connected to the anode of the second diode and the negative pole of the second capacitor.

In the above-mentioned embedded single-switch Buck-Boost converter converter, when the switch tube is turned on, the DC power supply charges the first inductor, the DC power supply and the first capacitor jointly charge the second inductor, and at the same time, the second capacitor supplies power to the load; When the switch tube is turned off, the first inductor charges the first capacitor, while the second inductor supplies power to the second capacitor and the load.

The working mode of the above-mentioned converter includes that the current of the first inductor L ₁ and the current of the second inductor L ₂ both work in the continuous conduction mode (L ₂ -CCM mode), and the current of the first inductor L ₁ works in the continuous conduction mode The current of the second inductor L ₂ works in a discontinuous conduction mode (L2-DCM mode).

Compared with the prior art, the present invention has the advantages that only one switch tube is used to realize the embedding of one Buck-Boost converter into another Buck-Boost converter, which greatly simplifies the circuit structure, and the gain can reach D /(1-D) ² , D is the duty cycle of the control signal of the switch tube.

Description of drawings

Fig. 1 is a kind of embedded single switch Buck-Boost converter structural diagram of the present invention;

Fig. 2 is a key current waveform diagram of an embedded single-switch Buck-Boost converter shown in Fig. 1 working in L ₂ -CCM mode;

Fig. 3 is a key current waveform diagram of an embedded single-switch Buck-Boost converter shown in Fig. 1 working in L ₂ -DCM mode;

Figure 4a and Figure 4b are two working modes of an embedded single-switch Buck-Boost converter shown in Figure 1 working in L ₂ -CCM mode;

Fig. 5 is a working mode of an embedded single-switch Buck-Boost converter shown in Fig. 1 working in L ₂ -DCM mode;

Fig. 6 is a simulation waveform diagram of an embedded single-switch Buck-Boost converter shown in Fig. 1 working in L ₂ -CCM mode;

FIG. 7 is a simulation waveform diagram of an embedded single-switch Buck-Boost converter shown in FIG. 1 working in L ₂ -DCM mode.

detailed description

In order to further illustrate the content and characteristics of the present invention, the specific embodiments of the present invention will be described below in conjunction with the accompanying drawings, but the implementation of the present invention is not limited thereto.

Referring to Fig. 1, an embedded single-switch Buck-Boost converter of the present invention consists of a DC power supply V _in , a switch tube Q, a first capacitor C ₁ , a second inductor L ₂ , a second diode D ₂ , a second The two capacitors C _o and the load R form the main Buck-Boost converter; the DC power supply V _in , the switch tube Q, the first capacitor C ₁ , the first inductor L ₁ , the first diode D ₁ and the third diode D ₃ constitutes an embedded Buck-Boost converter, and its gain can reach D/(1-D) ² , where D is the duty ratio of the switch tube control signal.

The anode of the DC power supply _Vin is connected to the drain of the switching tube Q, the source of the switching tube Q is connected to the negative pole of the first capacitor _C1 and _one end of the first inductor L1, and the other end of the _first inductor L1 is connected to the first The anode of the diode D1 and the anode _of the third diode _D3 are connected, the cathode of the first diode D1 is connected to the anode of the _first capacitor _C1 , the cathode of the _second diode D2, and the second inductor _One end of L2 is connected, the other end of the _second inductance L2 is connected to the negative pole of the DC power supply _Vin , the cathode of the third diode _D3 , the positive pole of the second capacitor C _o , and one end of the load R, and the other end of the load R One end is connected with the anode of the _second diode D2 and the cathode of the second capacitor C _o .

The main circuit structure of Fig. 1 is used below, and the specific working principle of the present invention is described in conjunction with Fig. 2 to Fig. 5 .

First consider that the converter works in L ₂ -CCM mode, the key current waveform diagram is shown in Figure 2:

In the stage t ₀ -t ₁ in Figure 2, the switch tube Q is turned on, the first diode D ₁ and the second diode D ₂ are cut off, the third diode D ₃ is turned on, and the DC power supply V _in is passed through the switch tube Q and the third diode _D3 to charge the _first inductor L1, the current i _L1 of the _first inductor L1 rises linearly; the DC power supply V _in and the first capacitor _C1 jointly charge the _second inductor L2 through the switch tube Q , the current i _L2 of the second inductor L ₂ rises linearly, and at the same time, the second capacitor C _o supplies power to the load R, and the current path is shown in Figure 4a.

In the stage t ₁ -t ₂ in Figure 2, the switch tube Q is turned off, the first inductor L ₁ freewheels through the first diode D ₁ , the second inductor L ₂ freewheels through the second diode D ₂ , and the third inductor L 2 freewheels through the second diode D 2 . The diode _D3 is cut off, the _first inductor L1 charges the _first capacitor _C1 through the _first diode D1, the current i _L1 of the first inductor L1 decreases linearly, and the second inductor L2 passes through the _second diode The tube D ₂ supplies power to the second capacitor C _o and the load R at the same time, the current i _L2 of the second inductor L ₂ decreases linearly, and the current path is shown in Fig. 4b.

Considering that the converter works in L ₂ -DCM mode, the key current waveform diagram is shown in Figure 3:

In the stages t ₀ -t ₂ in Fig. 2 and Fig. 3, the working process of the converter is exactly the same. t=t ₃ , the current i _L2 of the second inductor L ₂ drops to zero.

In the _t2 - _t3 stage of Fig. 3, the switching tube Q continues to be turned off, the _second diode D2 and the third diode _D3 are cut off, and the first inductance L1 continues to provide power to the _first inductor L1 through the _first diode D1. A capacitor C ₁ is charged, the current i _L1 of the first inductor L ₁ continues to decrease linearly, and at the same time, the second capacitor C _o supplies power to the load R, and the current path is shown in FIG. 5 .

Figure 6 shows the simulation waveform diagram of the converter working in L ₂ -CCM mode, from top to bottom are the gate control signal v _gQ of the switch, the current i _L1 of the first inductor, and the current i _L2 of the second inductor , the current i _C1 flowing through the first capacitor, and the current i _C2 flowing through the second capacitor. It can be seen from FIG. 6 that the current i _L1 of the first inductor and the current i _L2 of the second inductor are continuous.

Figure 7 shows the simulation waveform diagram of the converter working in L ₂ -DCM mode, from top to bottom are the gate control signal v _gQ of the switch, the current i _L1 of the first inductor, and the current i _Lx of the second inductor , the current i _C1 flowing through the first capacitor, and the current i _C2 flowing through the second capacitor. It can be seen from Fig. 6 that the current i _L1 of the first inductor is continuous, while the current i _L2 of the second inductor is intermittent.

Claims (3)

1. an embedded single switch Buck-Boost converter, is characterized in that: with DC power supply ( v _in ), switching tube ( q), the first electric capacity ( c ₁ ), the second inductance ( l ₂ ), the second diode ( d ₂ ), the second electric capacity ( c _o ) and load ( r) form main One Buck-Boost converter body; With DC power supply ( v _in ), switching tube ( q), the first electric capacity ( c ₁ ), the first inductance ( l ₁ ), the first diode ( d ₁ ) and the 3rd diode ( d ₃ ) form embedding One Buck-Boost converter body; DC power supply ( v _in ) positive pole and switching tube ( q) drain electrode connect, switching tube ( q) source electrode and the first electric capacity ( c ₁ ) negative pole, the first inductance ( l ₁ ) one end connect, the first inductance ( l ₁ ) the other end and the first diode ( d ₁ ) anode, the 3rd diode ( d ₃ ) anode connect, the first diode ( d ₁ ) negative electrode and the first electric capacity ( c ₁ ) positive pole, the second diode ( d ₂ ) negative electrode, the second inductance ( l ₂ ) one end connect, the second inductance ( l ₂ ) the other end and DC power supply ( v _in ) negative pole, the 3rd diode ( d ₃ ) negative electrode, the second electric capacity ( c _o ) positive pole, load ( r) one end connect, load ( r) the other end and the second diode ( d ₂ ) anode, the second electric capacity ( c _o ) negative pole connect.

2. a kind of embedded single switch Buck-Boost converter according to claim 1, is characterized in that: when switching tube ( q) when opening, DC power supply ( v _in ) to the first inductance ( l ₁ ) charging, DC power supply ( v _in ) and the first electric capacity ( c ₁ ) common give the second inductance ( l ₂ ) charging, simultaneously the second electric capacity ( c _o ) to load ( r) power supply; When switching tube ( q) turn off time, the first inductance ( l ₁ ) to the first electric capacity ( c ₁ ) charging, simultaneously the second inductance ( l ₂ ) to the second electric capacity ( c _o ) and load ( r) power supply.

3. a kind of embedded single switch Buck-Boost converter according to claim 1, is characterized in that: the mode of operation of converter comprise the first inductance ( l ₁ ) electric current and the second inductance ( l ₂ ) electric current all work in continuous conduction mode, and the first inductance ( l ₁ ) current work in continuous conduction mode the second inductance ( l ₂ ) current work in discontinuous conduction mode.