CN113890340B - A single-input high-reliability capacitor-current consistent buck-boost DC-DC converter - Google Patents

Abstract

A single-input high-reliability capacitance-current consistent buck-boost DC-DC converter comprises a direct current input source, a basic buck converter and n gain expansion units. The gain expansion unit is composed of two inductors, two capacitors, a diode and a switching tube, and the input and output gains of the converter can be realized by adjusting the number of the gain expansion units. The converter has the characteristics of simple control and driving circuit, wide input and output voltage regulation range and high reliability, and when any one of the switching tubes in the circuit is damaged, the other circuits can work normally. The converter is suitable for application occasions with large output and input voltage and output voltage variation range and high reliability requirements.

Description

A single-input high-reliability capacitor-current consistent buck-boost DC-DC converter converter

Technical field

The invention relates to a DC-DC converter, in particular to a single-input high-reliability capacitor current consistent Buck-boost DC-DC converter.

Background technique

In applications where both the input and output voltages vary greatly, the input voltage may be higher or lower than the output voltage. Common non-isolated buck-boost DC-DC converters applicable at this time include Buck-Boost, Cuk, Sepic and Zeta circuits. Theoretically, by adjusting the duty cycle D, the input and output gains of these converters can vary from zero to infinity. However, due to the influence of component and circuit parasitic parameters, the voltage boosting capabilities of these converters are greatly limited.

At present, the input and output gain solutions of single-input DC-DC converters are mostly constructed by cascading basic circuits, but the reliability is poor. Therefore, it is of great significance to study a single-input buck-boost DC/DC converter that can achieve high-gain boost and also has high reliability.

Contents of the invention

In order to solve the problem of low reliability of existing non-isolated single-input high-gain DC-DC converters. The present invention proposes a single-input high-reliability capacitor current consistent Buck-boost DC-DC converter based on a basic Buck-boost converter. The converter is composed of a basic Buck-boost converter and several gain expansion units. By adjusting the number of gain expansion units, the input and output gain of the converter can be achieved. The converter has the characteristics of simple control and drive circuit, wide input and output voltage adjustment range, and high reliability; when one switch tube in the converter circuit is damaged, the other circuits can work normally; the converter is suitable for output input voltages and Applications with a relatively large output voltage variation range and high reliability requirements.

The technical solutions adopted by the present invention are:

A single-input high-reliability capacitor current consistent Buck-boost DC-DC converter, which includes: a basic Buck-boost converter and n gain expansion units;

The basic Buck-boost converter includes an inductor L ₁ , a capacitor C ₁ , a power switch S ₁ , and a diode D ₁ ;

The anode of the DC input source u _in is connected to the drain of the power switch S _1. The source of the power switch S ₁ is connected to one end of the inductor L ₁ and the cathode of the diode _D 1. The anode of the diode D ₁ is connected to one end of the capacitor C ₁ and the other end of the capacitor C ₁ and the inductor L. ₁ The other end is connected to the negative pole of the DC input source u _in ;

The first gain expansion unit includes inductors L ₂₁ and L ₂₂ , capacitors C ₂₁ and C ₂₂ , diode D ₂ , and power switch S ₂ ; the drain of power switch S ₂ is connected to the positive pole of DC input source u _in , and the source of power switch S ₂ Connect one end of inductor L ₂₁ and one end of capacitor C ₂₁ respectively. The other end of capacitor C ₂₁ is connected to one end of inductor L ₂₂ and the cathode of diode _D 2. The anode of diode D ₂ is connected to one end of capacitor C _22. The other end of capacitor C ₂₂ is connected to the other end of inductor L ₂₂ . , the other end of the inductor L ₂₁ is connected to the ground terminal;

The second gain expansion unit includes inductors L ₃₁ and L ₃₂ , capacitors C ₃₁ and C ₃₂ , diode D ₃ , and a power switch S ₃ ; the drain of power switch S ₃ is connected to the positive pole of DC input source u _in , and the source of power switch S ₃ The poles are respectively connected to one end of inductor L ₃₁ and one end of capacitor C _{31. The} other end of capacitor C ₃₁ is connected to one end of inductor L ₃₂ and the cathode of diode D 3. The anode of diode D ₃ is connected to one end of capacitor C _32. The other end of capacitor C ₃₂ is connected to the other end of inductor L ₃₂ . One end, the other end of the inductor L ₃₁ is connected to the ground;

……And so on,

The nth gain expansion unit includes inductors L _n+1,1 and L _n+1,2 , capacitors C _n+1,1 and C _n+1,2 , diode D _n+1 , and power switch S _n+1 ;

The drain of the power switch S _n+1 is connected to the positive electrode of the DC input source u _in , and the source of the power switch S _n+1 is connected to one end of the inductor L _n+1,1 , one end of the capacitor C _n+1,1 , and the capacitor C _{n+1, 1} The other end is connected to one end of the inductor L _{n+1 and 2} and the cathode of the diode D _n+1 . The anode of the diode D _n+1 is connected to one end of the capacitor C _{n+1 and 2.} The other end of the capacitor C _{n+1 and 2} is connected to the inductor L _n. The other end of _+1,2 , the other end of the inductor L _n+1,1 is connected to the ground terminal;

The other end of the capacitor C ₁ in the basic Buck-boost converter is connected to one end of the capacitor C ₂₂ in the first gain expansion unit. The connection relationship of each gain expansion unit is as follows:

The other end of the capacitor C ₂₂ in the first gain expansion unit is connected to one end of the capacitor C ₃₂ in the second gain expansion unit, and the other end of the capacitor C ₃₂ in the second gain expansion unit is connected to the capacitor C 32 in the third gain expansion unit. One end of C ₄₂ ,...and by analogy, the other end of the capacitor C _n,2 in the n-1th gain expansion unit is connected to one end of the capacitor C _n+1,2 in the nth gain expansion unit;

The two ends of the load R are respectively connected to one end of the capacitor C ₁ and the other end of the capacitor C _n+1,2 .

The gates of the power switch S _{1 and} the power switches S ₂ , S ₃ ...S _n+1 are all connected to the controller, and their duty cycles can vary between 0 and 1. When any one of the switch tubes is damaged, the entire circuit Can continue to work normally.

The present invention is a single-input high-reliability capacitor current consistent Buck-boost DC-DC converter. The technical effects are as follows:

1). It can achieve voltage boosting and bucking at the same time, and the input and output gain is high. The output capacitors are connected in series and the voltage is equalized. When the inductor current is continuously conducting, the details are as follows:

Voltage input and output gain

The voltage stress of the switching tube is: The voltage stress of the diode is:/>

Voltage across each output capacitor:

Among them: D is the duty cycle.

2) When one of the power switch tubes in the gain expansion unit except the basic Buck-boost converter is damaged, the remaining circuits can work normally.

Description of the drawings

Figure 1 is a schematic diagram of the circuit of the present invention.

Figure 2 is the circuit schematic diagram of a traditional Buck-boost converter.

Figure 3 is a circuit topology diagram when the number of gain expansion units in the present invention is 2.

Figure 4 is a comparison diagram of the input and output gains of the traditional Buck-boost converter when the number of gain expansion units in the present invention is 2.

Figure 5 is a simulation diagram of the output waveform when the input voltage of the present invention is 30V, the gain expansion unit is 2, and D=0.6.

Figure 6 is a simulation diagram of the output waveform when the switching transistor S3 is damaged when the input voltage of the present invention is 30V, the gain expansion unit is 2, and D=0.6.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 3, it is the circuit topology diagram when the number of gain expansion units of the present invention is 2:

A single-input high-reliability capacitor current consistent Buck-boost DC-DC converter. The converter includes: a basic Buck-boost converter and 2 gain expansion units;

The basic Buck-boost converter includes an inductor L ₁ , a capacitor C ₁ , a power switch S ₁ , and a diode D ₁ ;

The anode of the DC input source u _in is connected to the drain of the power switch S _1. The source of the power switch S ₁ is connected to one end of the inductor L ₁ and the cathode of the diode _D 1. The anode of the diode D ₁ is connected to one end of the capacitor C ₁ and the other end of the capacitor C ₁ and the inductor L. ₁ The other end is connected to the negative pole of the DC input source u _in ;

The first gain expansion unit includes inductors L ₂₁ and L ₂₂ , capacitors C ₂₁ and C ₂₂ , diode D ₂ , and power switch S ₂ ; the drain of power switch S ₂ is connected to the positive pole of DC input source u _in , and the source of power switch S ₂ Connect one end of inductor L ₂₁ and one end of capacitor C ₂₁ respectively. The other end of capacitor C ₂₁ is connected to one end of inductor L ₂₂ and the cathode of diode _D 2. The anode of diode D ₂ is connected to one end of capacitor C _22. The other end of capacitor C ₂₂ is connected to the other end of inductor L ₂₂ . , the other end of the inductor L ₂₁ is connected to the ground terminal;

The second gain expansion unit includes inductors L ₃₁ and L ₃₂ , capacitors C ₃₁ and C ₃₂ , diode D ₃ , and a power switch S ₃ ; the drain of power switch S ₃ is connected to the positive pole of DC input source u _in , and the source of power switch S ₃ The poles are respectively connected to one end of inductor L ₃₁ and one end of capacitor C _{31. The other end of capacitor C 31 is} connected to one end of inductor L ₃₂ and the cathode of diode _D 3. The anode of diode D ₃ is connected to one end of capacitor C _32. The other end of capacitor C ₃₂ is connected to the other end of inductor L ₃₂ . One end, the other end of the inductor L ₃₁ is connected to the ground.

The two ends of the load R are connected to one end of the capacitor C ₁ and the other end of the capacitor C ₃₂ respectively.

The gates of power switches S1, S2 and S3 are connected to their controllers, and their duty cycles can vary between 0 and 1. By adjusting the duty cycle, the on-off time of power switches S1, S2 and S3 can be controlled, and the output voltage level can be adjusted according to the voltage balance formula of the inductor.

When the number of gain expansion units is equal to 2 and all inductor currents are continuously conducted, the circuit can be divided into two working states according to the different power switches:

(1): The power switches S ₁ , S ₂ and S ₃ are turned on, and the diodes D ₁ , D ₂ and D ₃ are all turned off. The voltages at the terminals of inductors L ₁ , L ₂₁ , L ₂₂ , L ₃₁ , and L ₃₁ are as follows:

(2): The power switches S ₁ , S ₂ and S ₃ are turned off, and the diodes D ₁ , D ₂ and D ₃ are all turned on. The voltages at the terminals of inductors L ₁ , L ₂₁ , L ₂₂ , L ₃₁ , and L ₃₁ are as follows:

According to the duty cycle of the controller connected to the gates of power switches S1, S2 and S3, the voltage level on each capacitor can be obtained as follows:

Figure 4 is a comparison diagram between the input and output gains of the present invention and the traditional Buck-boost converter when the number of gain expansion units is 2. It can be seen from Figure 4 that when the duty cycle is the same, the gain of the converter proposed by the present invention is three times that of the traditional converter.

Figure 5 is a simulation diagram of the output waveform when the input voltage of the present invention is 30V, the number of gain expansion units is 2, and D=0.6. The simulation verified the feasibility of the present invention.

Figure 6 is a simulation diagram of the output waveform when the switching transistor S3 is damaged when the input voltage of the present invention is 30V, the number of gain expansion units is 2, and D=0.6. The simulation verifies the reliability of the present invention.

Claims (2)

1. A single-input high-reliability capacitance-current consistent type Buck-boost DC-DC converter is characterized in that the converter comprises: a basic Buck-boost converter, n gain expansion units;

the basic Buck-boost converter comprises an inductance L ₁ Capacitance C ₁ Power switch S ₁ Diode D ₁ ；

DC input source u _in Positive electrode connection power switch S ₁ Drain, power switch S ₁ The source electrodes are respectively connected with the inductance L ₁ One end of diode D ₁ Cathode, diode D ₁ Anode connection capacitor C ₁ One end of the capacitor C ₁ Another end, inductance L ₁ The other ends are connected with a direct current input source u _in A negative electrode;

the 1 st gain expansion unit comprises an inductance L ₂₁ 、L ₂₂ Capacitance C ₂₁ 、C ₂₂ Diode D ₂ Power switch S ₂ The method comprises the steps of carrying out a first treatment on the surface of the Power switch S ₂ The drain electrode is connected with a direct current input source u _in Positive pole, power switch S ₂ The source electrodes are respectively connected with the inductance L ₂₁ One end, capacitor C ₂₁ One end of the capacitor C ₂₁ The other end is connected with an inductor L ₂₂ One end of diode D ₂ Cathode, diode D ₂ Anode connection capacitor C ₂₂ One end of the capacitor C ₂₂ The other end is connected with an inductor L ₂₂ Another end, inductance L ₂₁ The other end is connected with a grounding end;

the 2 nd gain expansion unit comprises an inductance L ₃₁ 、L ₃₂ Capacitance C ₃₁ 、C ₃₂ Diode D ₃ A power switch S ₃ The method comprises the steps of carrying out a first treatment on the surface of the Power switch S ₃ The drain electrode is connected with a direct current input source u _in Positive pole, power switch S ₃ The source electrodes are respectively connected with the inductance L ₃₁ One end, capacitor C ₃₁ One end of the capacitor C ₃₁ The other end is connected with an inductor L ₃₂ One end of diode D ₃ Cathode, diode D ₃ Anode connection capacitor C ₃₂ One end of the capacitor C ₃₂ The other end is connected with an inductor L ₃₂ Another end, inductance L ₃₁ The other end is connected with a grounding end;

… … and so on,

the nth gain expansion unit includes an inductance L _n+1,1 、L _n+1,2 Capacitance C _n+1,1 、C _n+1,2 Diode D _n+1 Power switch S _n+1 ；

Power switch S _n+1 The drain electrode is connected with a direct current input source u _in Positive pole, power switch S _n+1 The source electrodes are respectively connected withInductance L _n+1,1 One end, capacitor C _n+1,1 One end of the capacitor C _n+1,1 The other end is connected with an inductor L _n+1,2 One end of diode D _n+1 Cathode, diode D _n+1 Anode connection capacitor C _n+1,2 One end of the capacitor C _n+1,2 The other end is connected with an inductor L _n+1,2 Another end, inductance L _n+1,1 The other end is connected with a grounding end;

capacitor C in basic Buck-boost converter ₁ The other end is connected with a capacitor C in the 1 st gain expansion unit ₂₂ At one end, the connection relation of each gain expansion unit is as follows:

capacitor C in the 1 st gain expansion cell ₂₂ The other end is connected with a capacitor C in the 2 nd gain expansion unit ₃₂ One end, capacitor C in the 2 nd gain expansion unit ₃₂ The other end is connected with a capacitor C in the 3 rd gain expansion unit ₄₂ One end of the capacitor C is … … and so on, and the capacitor C in the n-1 gain expansion unit _n，2 The other end is connected with a capacitor C in the nth gain expansion unit _n+1,2 One end;

the two ends of the load R are respectively connected with the capacitor C ₁ One end, capacitor C _n+1,2 The other end;

when the gain expansion unit is equal to 2, the circuit can be divided into 2 working states according to different power switches when the inductance current is continuously conducted:

(1): power switch S ₁ 、S ₂ S and S ₃ Conduction, diode D ₁ 、D ₂ 、D ₃ All are turned off; inductance L ₁ 、L ₂₁ 、L ₂₂ 、L ₃₁ 、L ₃₁ The terminal voltage is shown as follows:

(2): power switch S ₁ 、S ₂ S and S ₃ Turn-off, diode D ₁ 、D ₂ 、D ₃ All open; inductance L ₁ 、L ₂₁ 、L ₂₂ 、L ₃₁ 、L ₃₁ The terminal voltage is shown as follows:

2. the single-input high-reliability capacitive current consistent-type Buck-boost DC-DC converter of claim 1, wherein: the power switch S ₁ Power switch S ₂ 、S ₃ ……S _n+1 The gates of which are connected to a controller, the duty cycle of which may vary between 0 and 1.