阅读说明：本技术 一种多级并联dc-dc变换器 (Multi-stage parallel DC-DC converter ) 是由 王文博 张国旗 于 2020-03-13 设计创作，主要内容包括：一种多级并联DC-DC变换器,包括：输入电源,串联的第一变换单元,第二变换单元,及,与第一变换单元及第二变换单元并联的第三变换单元；所述第一变换单元包括PWM电路,所述第一变换单元电压变化率根据PWM电路中开关占空比确定；所述第二变换单元包括第一半桥LLC谐振电路,所述第一半桥LLC谐振电路包括第一变压器；第二变换单元电压变换率根据所述第一变压器确定；所述第三变换单元包括第二半桥LLC谐振电路,所述第二半桥LLC谐振电路包括第二变压器；第三变换单元电压变换率根据所述第二变压器确定。本发明解决了现有技术的多级DC-DC变换器效率低的技术问题,实现了高转换效率,可控电压幅度、可控单一或多相位结合的输出电压的技术效果。(A multi-stage parallel DC-DC converter comprises an input power supply, a first conversion unit, a second conversion unit and a third conversion unit, wherein the first conversion unit and the second conversion unit are connected in series, the first conversion unit comprises a PWM circuit, the voltage change rate of the first conversion unit is determined according to the switching duty ratio in the PWM circuit, the second conversion unit comprises a first half-bridge LL C resonant circuit, the first half-bridge LL C resonant circuit comprises a first transformer, the voltage change rate of the second conversion unit is determined according to the first transformer, the third conversion unit comprises a second half-bridge LL C resonant circuit, the second half-bridge LL C resonant circuit comprises a second transformer, and the voltage change rate of the third conversion unit is determined according to the second transformer.)

1. A multi-stage parallel DC-DC converter, comprising:

the power supply is input into the power supply,

the first conversion unit, the second conversion unit and the third conversion unit are connected in series, and the third conversion unit is connected with the first conversion unit and the second conversion unit in parallel;

the first conversion unit comprises a PWM circuit, and the voltage change rate of the first conversion unit is determined according to the duty ratio of a switch in the PWM circuit;

the second conversion unit comprises a first half-bridge LL C resonant circuit, the first half-bridge LL C resonant circuit comprises a first transformer, and the voltage conversion rate of the second conversion unit is determined according to the first transformer;

the third converter unit comprises a second half-bridge LL C resonant circuit, the second half-bridge LL C resonant circuit comprises a second transformer, and the voltage conversion rate of the third converter unit is determined according to the second transformer.

2. The multi-stage parallel DC-DC converter according to claim 1, wherein the multi-stage parallel DC-DC converter outputs a voltage V₀The calculation formula of (2) is as follows:

V₀＝V_t1+V_t2

V_t1＝V_in×n₃

V_t2＝V₂×n₂

I_in＝I₁+I₃

wherein, V_inFor inputting the power supply input voltage, V₀For the output voltage, V, of the multi-stage parallel DC-DC converter_t1For the second conversion unit to output a voltage, V_t2For the third conversion unit to output a voltage, V₂For the second conversion unit input voltage, V₃For the third conversion unit input voltage, n₂Is the second conversion unit voltage change rate, n₃The voltage change rate of the third conversion unit, D the turn-on time of the power switch in the first conversion unit, I_inIs the total output current of the input power supply, I₁For the first conversion unit input current, I₃Inputting a current for the first conversion unit;

and controlling the voltage change rate of the multi-stage parallel DC-DC converter by controlling the conduction time D.

3. The multi-stage parallel DC-DC converter according to claim 1, wherein the first converter comprises a first power switch S connected in series₁₁And a second power switch S₁₂First inductor L₁First capacitor C₁The first inductor L₁A first terminal and the first power switch S₁₁And the second power switch S₁₂Is connected to the drain of the first inductor L₁A second terminal and the first capacitor C₁A first terminal connected to the first capacitor C₁A second terminal and the second power switch S₁₂Are connected.

4. The multi-stage parallel DC-DC converter according to claim 1, wherein the third converting unit comprises a third power switch S connected in series_r11And a fourth power switch S_r12A second capacitor C_r1And a first transformer T₁Said second capacitor C_r1First terminal and third power switch S_r11Source and fourth power switch S_r12Is connected to the drain of the first capacitor C, the second capacitor C_r2A second terminal and the first transformer T₁Are connected.

5. The multi-stage parallel DC-DC converter according to claim 1, wherein the second conversion unit comprises a fifth power switch S connected in series_r21And a sixth power switch S_r22Third capacitor C_r2And a second transformer T₂The third electricityContainer C_r2First terminal and fifth power switch S_r21Source and sixth power switch S_r22Is connected to the drain of the third capacitor C_r2A second terminal and the second transformer T₂Are connected.

6. The multi-stage parallel DC-DC converter according to claim 4, wherein the first transformer includes a second inductor L_r1Third magnetizing inductance L_m1A first winding coil, and a second inductor L_r1A first terminal and the second capacitor C_r1Second terminal connected to said second inductor L_r1Second terminal and the third exciting inductance L_m1A first end connected to the first end of the first winding coil, and a third excitation inductor L_m1In parallel with the first winding coil, the third excitation inductor L_m1Which is equivalent to the primary side excitation inductance of the transformer T1.

7. The multi-stage parallel DC-DC converter according to claim 5, wherein the second transformer comprises a fourth inductor L_r2Fifth magnetizing inductance L_m2A second winding coil, and a fourth inductor L_r2A first terminal and the third capacitor C_r2Second terminal connected to said fourth inductor L_r2Second terminal and the fifth magnetizing inductor L_m2A first end connected to the first end of the second winding coil, and a fifth excitation inductor L_m2In parallel with the second winding coil, the third excitation inductor L_m2Which is equivalent to the primary side excitation inductance of the transformer T2.

8. Multi-stage parallel DC-DC converter according to claims 1-7, characterized in that it is controlled by controlling the third power switch S_r11Fourth power switch S_r12Fifth power switch S_r21Sixth power switch S_r22And the switch is synchronously switched on and switched off, and the output voltage of the third conversion unit is controlled to be consistent with the output voltage of the second conversion unit in phase.

9. According to claimThe multi-stage parallel DC-DC converter as claimed in claims 1 to 7, characterized by controlling the first power switch S₁₁Second power switch S₁₂Output voltage regulation is realized; by controlling the third power switch S_r11Fourth power switch S_r12Fifth power switch S_r21Sixth power switch S_r22And delaying the switching phase, controlling the phases of the output voltage of the third conversion unit and the output voltage of the second conversion unit, and obtaining the output voltage of the multi-phase combined multi-stage parallel DC-DC converter.

Technical Field

The invention relates to the field of transformers, in particular to a multistage parallel DC-DC converter.

Background

A conventional DC-DC two-stage converter, as shown in fig. 1, is generally employed. A buck or boost converter as the first converter stage for converting the input voltage V_inStabilized to a constant value V₁As the input voltage of the next converter. The second stage converter provides a step-up or step-down voltage proportional to the isolated core high voltage. The second stage converter is designed to be efficient but unable to regulate voltage. In boosting applications, ACThe staggered configuration is often used to share a large current input as shown in fig. 2. The converters 2 and 3 share a high current input Iin. The functions of the converter 3 and the converter 2 are the same. In the voltage reduction application, the method of parallel connection of the secondary sides is widely adopted, as shown in fig. 3.

In the above DC-DC two-stage converter, the first stage converter is subjected to a larger input current, resulting in a larger power loss and a lower efficiency, and the first stage converter processes the whole input power P_inThe total efficiency of the whole system is η - η₁×η₂Wherein η is the total work efficiency, η₁For first order operating efficiency, η₂The second level of operating efficiency. In general, conventional two-stage or multi-stage converters have a low conversion efficiency and a large loss in the first-stage converter.

Disclosure of Invention

In view of the above technical problems in the prior art, the present invention provides a multi-stage parallel DC-DC converter, comprising:

the power supply is input into the power supply,

the first conversion unit, the second conversion unit and the third conversion unit are connected in series, and the third conversion unit is connected with the first conversion unit and the second conversion unit in parallel;

the first conversion unit comprises a PWM circuit, and the voltage change rate of the first conversion unit is determined according to the duty ratio of a switch in the PWM circuit;

the second conversion unit comprises a first half-bridge LL C resonant circuit, the first half-bridge LL C resonant circuit comprises a first transformer, and the voltage conversion rate of the second conversion unit is determined according to the first transformer;

the third converter unit comprises a second half-bridge LL C resonant circuit, the second half-bridge LL C resonant circuit comprises a second transformer, and the voltage conversion rate of the third converter unit is determined according to the second transformer.

Preferably, the output voltage V of the multi-stage parallel DC-DC converter₀The calculation formula of (2) is as follows:

V₀＝V_t1+V_t2

V_t1＝V_in×n₃

V_t2＝V₂×n₂

I_in＝I₁+I₃

wherein, V_inFor inputting the power supply input voltage, V₀For the output voltage, V, of the multi-stage parallel DC-DC converter_t1For the second conversion unit to output a voltage, V_t2For the third conversion unit to output a voltage, V₂For the second conversion unit input voltage, V₃For the third conversion unit input voltage, n₂Is the second conversion unit voltage change rate, n₃The voltage change rate of the third conversion unit, D the turn-on time of the power switch in the first conversion unit, I_inIs the total output current of the input power supply, I₁For the first conversion unit input current, I₃Inputting a current for the first conversion unit;

and controlling the voltage change rate of the multi-stage parallel DC-DC converter by controlling the conduction time D.

Preferably, the first converter comprises a first power switch S connected in series₁₁And a second power switch S₁₂First inductor L₁First capacitor C₁The first inductor L₁A first terminal and the first power switch S₁₁And the second power switch S₁₂Is connected to the drain of the first inductor L₁A second terminal and the first capacitor C₁A first terminal connected to the first capacitor C₁A second terminal and the second power switch S₁₂Are connected.

Preferably, the third conversion unit comprises a third power switch S connected in series_r11And a fourth power switch S_r12A second capacitor G_riAnd a first transformer T₁Said second capacitor C_r1First terminal and third power switch S_r11Source and fourth power switch S_r12Is connected to the drain of the first capacitor C, the second capacitor C_r2A second terminal and the first transformer T₁Are connected.

Preferably, the second conversion unit comprises a fifth power switch S connected in series_r21And a sixth power switch S_r22Third capacitor C_r2And a second transformer T₂Said third capacitance C_r2First terminal and fifth power switch S_r21Source and sixth power switch S_r22Is connected to the drain of the third capacitor C_r2A second terminal and the second transformer T₂Are connected with each other

Preferably, the first transformer comprises a second inductor L_r1Third magnetizing inductance L_m1A first winding coil, and a second inductor L_r1A first terminal and the second capacitor C_r1Second terminal connected to said second inductor L_r1Second terminal and the third exciting inductance L_m1A first end connected to the first end of the first winding coil, and a third excitation inductor L_m1In parallel with the first winding coil, the third excitation inductor L_m1Which is equivalent to the primary side excitation inductance of the transformer T1.

Preferably, the second transformer comprises a fourth inductor L_r2Fifth magnetizing inductance L_m2A second winding coil, and a fourth inductor L_r2A first terminal and the third capacitor C_r2Second terminal connected to said fourth inductor L_r2Second terminal and the fifth magnetizing inductor L_m2A first end connected to the first end of the second winding coil, and a fifth excitation inductor L_m2In parallel with the second winding coil, the third excitation inductor L_m2Which is equivalent to the primary side excitation inductance of the transformer T2.

Preferably, the third power switch S_r11Fourth power switch S_r12Fifth power switch S_r21Sixth power switch S_r22And the switch is synchronously switched on and switched off, and the output voltage of the third conversion unit is controlled to be consistent with the output voltage of the second conversion unit in phase.

Preferably, by controlling the first power switch S_11，Second power switch S₁₂Output voltage regulation is realized; tong (Chinese character of 'tong')Over-controlling the third power switch S_r11Fourth power switch S_r12Fifth power switch S_r21Sixth power switch S_r22And delaying the switching phase, controlling the phases of the output voltage of the third conversion unit and the output voltage of the second conversion unit, and obtaining the output voltage of the multi-phase combined multi-stage parallel DC-DC converter.

The invention improves the efficiency of the converter by adopting a plurality of converters to share the input power of the input power supply; in addition, the invention can control the voltage amplitude and the output voltage of single or multi-phase combination by controlling the frequency of the power switch of a plurality of transformers as core converters which are connected in parallel.

Drawings

FIG. 1 is a prior art DC-DC converter;

FIG. 2 is a prior art DC-DC converter;

FIG. 3 is a prior art DC-DC converter;

FIG. 4 is a diagram of a two-stage DC-DC converter according to a first embodiment;

fig. 5 is a parameter diagram of the two-stage DC-DC converter provided in the first embodiment at 400V and 600V output voltages.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 scope of the present invention.