Two-stage DC-DC converter with partial power regulation function
阅读说明：本技术 一种具有部分功率调节功能的两级dc-dc变换器 (Two-stage DC-DC converter with partial power regulation function ) 是由 王文博 欧阳紫威 张国旗 于 2020-11-03 设计创作，主要内容包括：一种具有部分功率调节功能的两级DC-DC变换器,包括：输入电源；初级变换单元；中间电容单元；谐振变换单元；输出整流单元；负载单元。所述输入电源与所述ACF变换单元相连,所述中间电容单元与所述输入电源、所述ACF变换单元、所述输出整流单元相连,所述负载单元连接到所述输出整流单元的输出端。本发明解决了传统的两级DC-DC变换器效率低的问题,高效高功率密度,能够满足不同的输出电压需求。(A two-stage DC-DC converter with partial power regulation, comprising: inputting a power supply; a primary conversion unit; an intermediate capacitor unit; a resonance conversion unit; an output rectifying unit; a load unit. The input power supply is connected with the ACF conversion unit, the intermediate capacitor unit is connected with the input power supply, the ACF conversion unit and the output rectifying unit, and the load unit is connected to the output end of the output rectifying unit. The invention solves the problem of low efficiency of the traditional two-stage DC-DC converter, has high efficiency and high power density, and can meet different output voltage requirements.)
1. A two-stage DC-DC converter with partial power regulation, comprising:
inputting a power supply;
a primary conversion unit;
an intermediate capacitor unit;
a resonance conversion unit;
an output rectifying unit, a load unit;
the input power supply is connected with the primary conversion unit, the intermediate capacitor unit is connected with the input power supply, the primary conversion unit and the output rectification unit, and the load unit is connected to the output end of the output rectification unit.
2. The method of claim 1The two-stage DC-DC converter with partial power regulation function is characterized in that the output voltage V of the two-stage DC-DC converter with high power density0The calculation formula of (2) is as follows:
G＝n2(1+f(n1，d))
wherein, VinFor inputting the power supply input voltage, VmIs the intermediate bus voltage, VtIs the output voltage of the primary conversion unit, V0For the output voltage of the two-stage DC-DC converter with partial power regulation, n2The rate of change of voltage of LCLC resonant converter, f (n)1D) the rate of change of the voltage of the primary conversion unit, n1D is the duty ratio of the primary conversion unit, and G is the voltage gain of the two-stage DC-DC converter with partial power regulation function.
3. The two-stage DC-DC converter with partial power regulation function according to claim 1, wherein the calculation formula of the total system efficiency of the high power density two-stage DC-DC converter is:
wherein, PtFor the output power of the primary conversion unit to the next stage, PbFor power transfer directly from the input power source to the intermediate capacitive unit, PinTotal input power, η, for the entire converterACFFor the efficiency of the primary conversion unit, etaLCLCIs the efficiency of the resonant cell. RTB is PtAnd PbThe power ratio of (a).
4. A two-stage DC-DC converter with partial power regulation function according to any one of claims 1-3, wherein the primary conversion unit is an ACF circuit including a first capacitor Cr1A first power switch Q1A second power switch Q2A first transformer, a seventh power switch SR, and a first capacitor Cr1First terminal and second power switch Q2Is connected to the drain of the first transformer, has a second terminal connected to a first terminal of the primary side of the first transformer, and has a second terminal of the primary side of the first transformer connected to a second power switch Q2Source electrode of, first power switch Q1Is connected to the drain of the first transformer secondary side, the first terminal of the first transformer secondary side is connected to the drain of the seventh power switch SR, the first power switch Q is connected to the drain of the seventh power switch SR1Source electrode, first capacitor Cr1Is connected to the input power supply.
5. Two-stage DC-DC converter with partial power regulation according to claim 4, characterized in that the capacitive unit comprises a third capacitor CtA fourth capacitor CbA fifth capacitor C1Third capacitor CtFirst of allTerminal, second terminal of the secondary side of the first transformer, and fifth capacitor C1First ends are connected to each other, and a third capacitor CtThe second end, the source of the seventh power switch SR, and the fourth capacitor CbFirst end connected to a fourth capacitor CbSecond terminal and first power switch Q1Source electrode of, fifth capacitor C1The second end is connected.
6. Two-stage DC-DC converter with partial power regulation according to claim 5, characterized in that the resonant cell is an LCLC resonant converter, the resonant cell comprising a third power switch Q3And a fourth power switch Q4The fifth power switch Q5And a sixth power switch Q6A second capacitor Cr2A second transformer, a third power switch Q3Drain of and fifth power switch Q5Drain electrode of (1), third capacitor CtFirst terminal connected to a third power switch Q3Source and fourth power switch Q4Is connected to the drain of the fifth power switch Q5Source and sixth power switch Q6Is connected to the drain of the fourth power switch Q4Source and sixth power switch Q6Source electrode of, fourth capacitor CbA second terminal connected to a second capacitor Cr2First terminal and third power switch Q3Is connected to the first terminal of the primary side of the second transformer, which is connected to the fifth power switch Q5Is connected to the source of (a).
7. Two-stage DC-DC converter with partial power regulation according to claim 1, characterized in that the output rectifying unit comprises a diode D1D2, D3, D4, the first terminal of the secondary side of the second transformer and a diode D1Anode of (2), diode D2Is connected with the second end of the secondary side of the second transformer and a diode D3Anode of (2), diode D4Are all connected with each other, a diode D1Cathode and diode D3Is connected to the cathode of a diode D2Anode and diode D4Is connected to the positive pole of a sixth capacitor C0First terminal and diode D3Is connected with the cathode of the diode D4Is connected to the diode D, the load unit is connected to the diode D3Cathode of (2), diode D4The positive electrode of (1).
8. Two-stage DC-DC converter with partial power regulation according to claim 5, characterized in that the first transformer comprises a first inductance Lr1And an excitation inductor Lm1A primary winding coil, a secondary winding coil, the first excitation inductance Lm1An excitation inductance equivalent to the first primary winding for the first transformer, the first capacitor Cr1Second terminal and first inductor Lr1Is connected to a first terminal of a first inductor Lr1Second terminal and first excitation inductance Lm1Is connected to a first end of a first primary winding, a first excitation inductance Lm1A primary winding coil connected in parallel, a second power switch Q2Source and excitation inductance L ofm1Second terminal of the first primary winding, first power switch Q1Is connected to the first terminal of the first secondary winding and is connected to the drain of the seventh power switch SR.
9. Two-stage DC-DC converter with partial power regulation according to claim 7, characterized in that the second transformer comprises a second inductance Lr2A sixth capacitor CpA second excitation inductance Lm2A second primary winding, a second secondary winding, and a second excitation inductor Lm2A second capacitor C for exciting inductance equivalent to the second primary winding of the second transformerr2Second terminal and second inductor Lr2Is connected to the first terminal of the second inductor Lr2Second terminal and sixth capacitor CpFirst terminal, second excitation inductance Lm2Is connected to the first end of the second primary winding, a sixth capacitor CpA second excitation inductance Lm2A second primary winding and a sixth capacitor CpParallel connection, a sixth capacitor CpSecond end, secondExcitation inductance Lm2Second terminal of the second primary winding, second terminal of the second primary winding and fifth power switch Q5Is connected to the source of (a).
Technical Field
The invention relates to the field of transformers, in particular to a two-stage DC-DC converter with a partial power regulation function.
Background
High levels of dc voltage are widely cited, for example in photovoltaic systems, medical and industrial x-ray and telecommunication equipment and traveling wave tubes. The traditional single-stage converter has a simple circuit structure, and cannot realize electrical isolation and soft switching between signal grounding and power grounding in a wider input voltage range. In conventional two-stage or multi-stage converters, all the input power is processed by the first and second stage converters, and overall, the two-stage or multi-stage converters have low conversion efficiency and large losses in the first stage converter.
Disclosure of Invention
In order to solve the technical problem, the invention provides a two-stage direct current converter structure which adopts partial power regulation and does not increase active or passive components. In the present invention, a two-stage DC-DC converter having a partial power regulation function includes:
inputting a power supply;
a primary conversion unit;
an intermediate capacitor unit;
a resonance conversion unit;
an output rectifying unit, a load unit;
the input power supply is connected with the primary conversion unit, the intermediate capacitor unit is connected with the input power supply, the primary conversion unit and the output rectification unit, and the load unit is connected to the output end of the output rectification unit.
Preferably, the output voltage V of the two-stage DC-DC converter with partial power regulation function0The calculation formula of (2) is as follows:
G＝n2(1+f(n1,d)) (4)
wherein, VinFor inputting the power supply input voltage, VmIs the intermediate bus voltage, VtIs the output voltage of the primary conversion unit, V0For the output voltage of the two-stage DC-DC converter with partial power regulation, n2The rate of change of voltage of LCLC resonant converter, f (n)1D) the rate of change of the voltage of the primary conversion unit, n1To convert into sheets for the first stageThe voltage change rate of the element, d is the duty ratio of the primary conversion unit, and G is the voltage gain of the two-stage DC-DC converter with partial power regulation function.
Preferably, the calculation formula of the total system efficiency of the two-stage DC-DC converter with partial power regulation function is as follows:
wherein, PtOutput power, P, for the primary conversion unit to the next stagebFor power transfer directly from the input power source to the next stage, PinTotal input power, η, for the entire converterACFFor the efficiency of the primary conversion unit, etaLCLCIs the efficiency of the resonant cell. RtbIs PtAnd PbThe power ratio of (a).
Preferably, the primary conversion unit comprises a first capacitor Cr1A first power switch Q1A second power switch Q2A first transformer, a seventh power switch SR, and a first capacitor Cr1First terminal and second power switch Q2Is connected to the drain of the first transformer, has a second terminal connected to a first terminal of the primary side of the first transformer, and has a second terminal of the primary side of the first transformer connected to a second power switch Q2Source electrode of, first power switch Q1Is connected to the drain of the first transformer secondary side, the first terminal of the first transformer secondary side is connected to the drain of the seventh power switch SR, the first power switch Q is connected to the drain of the seventh power switch SR1Source electrode ofA capacitor Cr1The second end of the first switch is connected with an input power supply;
preferably, the intermediate capacitor unit includes a third capacitor Ct, a fourth capacitor Cb, a fifth capacitor C1, and a third capacitor CtA first terminal connected to the second terminal of the secondary side of the first transformer and to the first terminal of a fifth capacitor C1, and a third capacitor CtThe second end, the source of the seventh power switch SR, and the fourth capacitor CbFirst end connected to a fourth capacitor CbSecond terminal and first power switch Q1Source electrode of, fifth capacitor C1The second end is connected;
preferably, the resonant unit is an LCLC resonant converter, and the resonant unit includes a third power switch Q3And a fourth power switch Q4The fifth power switch Q5And a sixth power switch Q6A second capacitor Cr2A second transformer, a third power switch Q3Drain of and fifth power switch Q5Is connected with the first end of a third capacitor Ct, and a third power switch Q3Source and fourth power switch Q4Is connected to the drain of the fifth power switch Q5Source and sixth power switch Q6Is connected to the drain of the fourth power switch Q4Source and sixth power switch Q6Source electrode of, fourth capacitor CbA second terminal connected to a second capacitor Cr2First terminal and third power switch Q3Is connected to the first terminal of the primary side of the second transformer, which is connected to the fifth power switch Q5Is connected to the source of (a);
preferably, the output rectifying unit includes a diode D1、D2、D3、D4The first terminal of the secondary side of the second transformer and the diode D1Anode of (2), diode D2Is connected with the second end of the secondary side of the second transformer and a diode D3Anode of (2), diode D4Are all connected with each other, a diode D1Cathode and diode D3Is connected to the cathode of a diode D2Anode and diode D4Is connected to the positive pole of a sixth capacitor C0First terminal and diode D3Is connected with the cathode of the diode D4Is connected to the diode D, the load unit is connected to the diode D3Cathode of (2), diode D4The positive electrode of (1);
preferably, the first transformer comprises a first inductance Lr1And an excitation inductor Lm1A primary winding coil, a secondary winding coil, the first excitation inductance Lm1An excitation inductance equivalent to the first primary winding for the first transformer, the first capacitor Cr1Second terminal and first inductor Lr1Is connected to a first terminal of a first inductor Lr1Second terminal and first excitation inductance Lm1Is connected to a first end of a first primary winding, a first excitation inductance Lm1A primary winding coil connected in parallel, a second power switch Q2Source and excitation inductance L ofm1Second terminal of the first primary winding, first power switch Q1Is connected with the drain of the seventh power switch SR, and the first end of the first secondary winding is connected with the drain of the seventh power switch SR;
preferably, the second transformer comprises a second inductance Lr2A sixth capacitor CpA second excitation inductance Lm2A second primary winding, a second secondary winding, and a second excitation inductor Lm2A second capacitor C for exciting inductance equivalent to the second primary winding of the second transformerr2Second terminal and second inductor Lr2Is connected to the first terminal of the second inductor Lr2, and the second terminal of the second inductor Lr2 is connected to the sixth capacitor CpFirst terminal, second excitation inductance Lm2Is connected to the first end of the second primary winding, a sixth capacitor CpA second excitation inductance Lm2A second primary winding and a sixth capacitor CpParallel connection, a sixth capacitor CpSecond terminal, second excitation inductance Lm2Second terminal of the second primary winding, second terminal of the second primary winding and fifth power switch Q5Is connected to the source of (a).
Compared with the traditional two-stage direct current converter, the two-stage direct current converter has obvious power loss at the front and rear stages, and the improved two-stage DC-DC converter improves the efficiency of the two-stage direct current converter in a partial power regulation mode. Part of input power is processed by the primary conversion unit to realize the regulation of output voltage, and most of the input power is directly transmitted to a load through the high-frequency efficient second stage, so that galvanic isolation and high boost ratio are provided. The ACF circuit is selected by the primary conversion unit, and the LCLC resonant converter is selected by the secondary conversion unit, so that the rated value of the secondary equipment of the ACF converter can be reduced. When the power processed by the primary conversion unit is relatively small, the system efficiency can be almost the same as that of a single stage, and the system is higher than that of a traditional two-stage structure, so that high power density is realized, and different output voltage requirements can be met.
Drawings
FIG. 1 is a two-stage DC-DC converter with partial power regulation provided in accordance with one embodiment;
FIG. 2 is a power flow analysis diagram of a two-stage DC-DC converter with partial power conditioning provided in accordance with an embodiment;
FIG. 3 is a power distribution diagram;
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.
Example one
The present embodiment provides a two-stage DC-DC converter with partial power regulation, as shown in FIGS. 1-2, comprising
Inputting a power supply;
an ACF conversion unit;
an intermediate capacitor unit;
a resonance conversion unit;
an output rectifying unit;
a load unit.
The input power supply is connected with the ACF conversion unit, the intermediate capacitor unit is connected with the input power supply, the ACF conversion unit and the output rectifying unit, and the load unit is connected to the output end of the output rectifying unit.
The ACF conversion unit includes: a first capacitor Cr1A first power switch Q1A second power switch Q2A first inductor Lr1And an excitation inductor Lm1A primary winding coil, a secondary winding coil and a seventh power switch SR, the first capacitor Cr1First terminal and second power switch Q2Is connected with the drain electrode of the first inductor L, and the second end of the first inductor Lr1Is connected to a first terminal of a first inductor Lr1Second terminal and first excitation inductance Lm1Is connected to a first end of a first primary winding, a first excitation inductance Lm1A primary winding coil connected in parallel, a second power switch Q2Source and excitation inductance L ofm1Second terminal of the first primary winding, first power switch Q1Is connected to the drain of the seventh power switch SR, the first end of the first secondary winding is connected to the drain of the seventh power switch SR, and the first excitation inductance L is connected to the drain of the seventh power switch SRm1Is equivalent to the excitation inductance of the first primary winding for the first transformer.
The intermediate capacitance unit includes: third capacitor CtA fourth capacitor CbA fifth capacitor C1Third capacitor CtA first terminal, a second terminal of the first secondary winding, and a fifth capacitor C1First ends are connected to each other, and a third capacitor CtA second terminal connected to the second terminal of the seventh power switch SR, and a fourth capacitor CbA first terminal and a first capacitor Cr1Second terminal, third capacitor CtIs connected to the second terminal of the fourth capacitor CbSecond terminal and first power switch Q1Source electrode of, fifth capacitor C1The second ends are connected.
The resonant cell is an LCLC resonant converter, comprising: third power switch Q3And a fourth power switch Q4The fifth power switch Q5And a sixth power switch Q6A second capacitor Cr2A second inductor Lr2A sixth capacitor CpA second excitation inductance Lm2A second primary winding, a second secondary winding, and a third power switchQ3Drain of and fifth power switch Q5Drain electrode of (1), third capacitor CtFirst terminal connected to a third power switch Q3Source and fourth power switch Q4Is connected to the drain of the fifth power switch Q5Source and sixth power switch Q6Is connected to the drain of the fourth power switch Q4Source and sixth power switch Q6Source electrode of, fourth capacitor CbA second terminal connected to a second capacitor Cr2First terminal and third power switch Q3Is connected with the second end of the second inductor Lr2Is connected to the first terminal of the second inductor Lr2Second terminal and sixth capacitor CpIs connected to a sixth capacitor CpSecond terminal and fifth power switch Q5Is connected to the source of the second excitation inductor Lm2A second primary winding and a sixth capacitor CpIn parallel, the second excitation inductance Lm2Is equivalent to the excitation inductance of the second primary winding for the second transformer.
The output rectifying unit comprises a diode D1、D2、D3、D4A first end of the second secondary winding and a diode D1Anode of (2), diode D2Are connected with the second end of the second secondary winding and a diode D3Anode of (2), diode D4Are all connected with each other, a diode D1Cathode and diode D3Is connected to the cathode of a diode D2Anode and diode D4Is connected with the anode of the output capacitor, the first end of the output capacitor is connected with the diode D3Is connected with the cathode of the diode D4Is connected to the diode D, the load unit is connected to the diode D3Cathode of (2), diode D4The positive electrode of (1).
Input voltage VinDirectly applied to the fourth capacitor CbTwo terminals, a fourth capacitor CbDirectly connected to the third capacitor CtThe LCLC resonant converter of the second stage is directly connected to the fifth capacitor C1The series input of the LCLC resonant converter is beneficial to reducing the rating of the secondary device of the ACF unit, and the switching frequency of the ACF converterIndependent of the LCLC resonant converter, soft switching and output voltage regulation can be achieved over the entire input voltage range. By controlling the duty ratio of the ACF converter, the output voltage V can be adjustedtIntermediate bus voltage VmCan also be effectively adjusted.
According to the equivalent circuit diagram of power flow analysis shown in FIG. 2, the output voltage V0The calculation formula of (2) is as follows:
G＝n2(1+f(n1，d)) (4)
wherein, VinFor inputting the power supply input voltage, VmIs the intermediate bus voltage, VtIs the output voltage of the ACF unit, V0For the output voltage of the two-stage DC-DC converter with partial power regulation, n2The rate of change of voltage of LCLC resonant converter, f (n)1D) the voltage change rate of the ACF unit, n1D is a duty ratio of the ACF unit, and G is a voltage gain of the two-stage DC-DC converter with partial power regulation function.
As can be seen from the above formula, if n is1And n2Determining, output voltage V0It becomes the voltage change rate f (n) of the ACF unit1D) which is adjustable by the duty cycle of the ACF unit.
The calculation formula of the total efficiency η of the whole system of the two-stage DC-DC converter with partial power regulation function provided by the embodiment is as follows:
wherein, PtFor the output power of the ACF unit to the next stage, PbFor power transfer directly from the input power source to the next stage, PinTotal input power, η, for the entire converterACFIs the efficiency of the ACF unit, ηLCLCIs the efficiency of the resonant cell. RtbIs PtAnd PbThe power ratio of (a).
The two-stage DC-DC converter of the invention is calculated and verified, the circuit parameters are shown in tables 1 and 2, the input voltage is different from 24 to 32V, and the voltage V of the intermediate bus ismIs 36V, when the input voltage changes, the power delivered by the ACF unit changes, and the power distribution is as shown in fig. 3. It can be seen that when VinAt 24V, the ACF unit delivers the maximum power, when VinAt 32V, the ACF unit delivers the minimum power of 48W. It can be seen that a significant portion of the power is transferred directly to the second stage without power processing, while the ACF unit only passes a portion of the input power to effect regulation of its output voltage.
The improved two-stage DC-DC converter does not increase active or passive components, partial input power is processed by the ACF unit, most input power is directly transmitted to the second stage, and the high-frequency efficient LCLC resonant converter processes full input power. The primary conversion unit can be other isolated PWM converters, and when ACF conversion circuit is adopted, the input voltage VinDirectly applied to the fourth capacitor CbTwo endsAnd a fourth capacitance CbDirectly connected to the third capacitor CtIn series, a lower nominal parameter can therefore be selected for the seventh power switch SR. When the power processed by the ACF unit is relatively small, the system efficiency can be almost the same as that of a single-stage structure, the efficiency is higher than that of a traditional two-stage DC-DC structure, and higher power density is realized.
TABLE 1 Electrical parameters
TABLE 2 device parameters
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.