CN110492750A - A kind of high step-down ratio DC/DC converter - Google Patents
A kind of high step-down ratio DC/DC converter Download PDFInfo
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- CN110492750A CN110492750A CN201910611754.3A CN201910611754A CN110492750A CN 110492750 A CN110492750 A CN 110492750A CN 201910611754 A CN201910611754 A CN 201910611754A CN 110492750 A CN110492750 A CN 110492750A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
A kind of high step-down ratio DC/DC converter of the invention is related to a kind of voltage changer, it is to overcome system capacity needs in existing DC/DC converter to be transmitted twice, system effectiveness is lower, and problem of the Buck circuit work under hard switching state, including LLC circuit and Buck circuit, and the input side of LLC circuit is connected with the input side of Buck circuit, the outlet side of LLC circuit is in parallel with the outlet side of Buck circuit；The working frequency of LLC circuit is fixed and is worked at best operating point；Buck circuit is resonance Buck converter, which works under closed loop mode, for carrying out closed-loop control to output voltage.
Description
Technical field
The present invention relates to a kind of voltage changers, and in particular to using the buck converter of LLC circuit and Buck circuit.
Background technique
With direct-current micro-grid, the continuous development of new energy system and data center's power supply system, high step-down ratio DC/DC
The demand of converter increasingly increases.Existing high step-down ratio circuit generally uses two-stage type structure, with data center's power supply system
For, two-stage circuit is respectively completed 48V and turns the voltage adjustment that 12V and 12V turns 1.8V.Two-stage circuit can guarantee every grade of circuit list
Solely control, and the voltage transmission of every grade of circuit is than in more moderate range.
But the major defect of two-stage system is that system capacity needs to be transmitted twice, system effectiveness is lower.And two
In grade system, rear class system often uses Buck circuit of the work under hard switching state.And to solve the above-mentioned problems, single-stage
High step-down ratio circuit is gradually proposed.The single-stage that the LLC circuit that 48V turns 1.8V can be realized energy is transmitted, but the LLC circuit
The turn ratio on middle transformer primary pair side is more, needs to increase the cost of system using multi-layer PCB board.The number of turns more simultaneously
It will increase the leakage inductance etc. of interlayer sneak parameter and former secondary side.
Therefore, the complexity of system design and implementation is significantly increased using the LLC circuit with larger turn ratio,
It is unfavorable for lifting system efficiency and power density.Simultaneously in the adjustment process of output voltage, LLC circuit deviates rated operation point
Afterwards, efficiency will be substantially reduced.
Summary of the invention
The purpose of the invention is to overcome system capacity needs in existing DC/DC converter to be transmitted twice, system
The problem that efficiency is lower and the work of Buck circuit is under hard switching state, provides a kind of high step-down ratio DC/DC converter.
A kind of high step-down ratio DC/DC converter of the invention, including LLC circuit and Buck circuit, and the input of LLC circuit
Side is connected with the input side of Buck circuit, and the outlet side of LLC circuit is in parallel with the outlet side of Buck circuit；
The working frequency of LLC circuit is fixed and is worked at best operating point；
Buck circuit be resonance Buck converter, the Buck circuit work under closed loop mode, for output voltage into
Row closed-loop control；
Buck circuit includes MOS switch pipe S3, MOS switch pipe S4, MOS switch pipe S5, resonant capacitance C2With the first transformation
Device；
MOS switch pipe S3Current input terminal connect with the input side of LLC circuit, MOS switch pipe S3Current output terminal with
MOS switch pipe S4Current input terminal electrical connection, MOS switch pipe S4Current output terminal ground connection；
The primary side winding of first transformer is connected with the different name end of vice-side winding, and with MOS switch pipe S5Electric current it is defeated
Enter end electrical connection, MOS switch pipe S5Current output terminal ground connection；
The leakage inductance of first transformer is equivalent to resonant inductance Lr2, the primary side inductance of the first transformer is equivalent to magnetizing inductance
Lm2, magnetizing inductance Lm2It is in parallel with the primary side winding of the first transformer；
Resonant capacitance C2One end and MOS switch pipe S3Current output terminal electrical connection, resonant capacitance C2The other end with
Resonant inductance Lr2With magnetizing inductance Lm2It is followed in series to form resonant cavity；
Output end of the vice-side winding of first transformer as Buck circuit；
MOS switch pipe S4With MOS switch pipe S5It simultaneously turns on or turns off, MOS switch pipe S3With MOS switch pipe S4Or MOS is opened
Close pipe S5Complementation conducting, and there are dead times.
The beneficial effects of the present invention are:
1, the present invention constructs high step-down ratio DC/DC converter, the input of two circuits using LLC circuit and resonance Buck converter
Side series connection, outlet side are in parallel.Mode is not being controlled in wherein LLC circuit work, realizes the voltage change ratio of fixed gain；Buck circuit work
Make to can be realized the closed-loop control of output voltage in closed loop control mode；
2, using resonance Buck converter, switching tube is enable to work under Sofe Switch state, while used resonance
Buck converter can realize high decompression ratio characteristic by series capacitance and coupling inductance under non-extreme duty cycle condition.
Detailed description of the invention
Fig. 1 is a kind of circuit topological structure schematic diagram of high step-down ratio DC/DC converter of the invention；
Fig. 2 is a kind of output voltage waveform of high step-down ratio DC/DC converter of the invention；
Fig. 3 is a kind of input voltage waveform figure of high step-down ratio DC/DC converter of the invention；
Fig. 4 is the diode current waveform diagram of the first transformer secondary winding positioned at LLC circuit；Wherein iD1For rectification two
Pole pipe D1Electric current, iD2For rectifier diode D2Electric current；
Fig. 5 is the cavity voltage and current waveform figure of LLC circuit；Wherein, Vds2For cavity voltage, ilr1For resonant cavity
Electric current；
Fig. 6 is LLC circuit and Buck circuit output current waveform diagram；Wherein, io1For LLC circuit output current, io2For
Buck circuit output current；
Fig. 7 be include Closed Loop Control Unit high step-down ratio DC/DC converter electrical module structure chart.
Specific embodiment
Specific embodiment 1: a kind of high step-down ratio DC/DC converter of present embodiment, including LLC circuit 1 with
Buck circuit 2, and the input side of LLC circuit 1 is connected with the input side of Buck circuit 2, outlet side and the Buck electricity of LLC circuit 1
The outlet side on road 2 is in parallel；
The working frequency of LLC circuit 1 is fixed and is worked at best operating point；
Buck circuit 2 is resonance Buck converter, which works under closed loop mode, for output voltage
Carry out closed-loop control；
Buck circuit 2 includes MOS switch pipe S3, MOS switch pipe S4, MOS switch pipe S5, resonant capacitance C2With the first transformation
Device；
MOS switch pipe S3Current input terminal connect with the input side of LLC circuit 1, MOS switch pipe S3Current output terminal
With MOS switch pipe S4Current input terminal electrical connection, MOS switch pipe S4Current output terminal ground connection；
The primary side winding of first transformer is connected with the different name end of vice-side winding, and with MOS switch pipe S5Electric current it is defeated
Enter end electrical connection, MOS switch pipe S5Current output terminal ground connection；
The leakage inductance of first transformer is equivalent to resonant inductance Lr2, the primary side inductance of the first transformer is equivalent to magnetizing inductance
Lm2, magnetizing inductance Lm2It is in parallel with the primary side winding of the first transformer；
Resonant capacitance C2One end and MOS switch pipe S3Current output terminal electrical connection, resonant capacitance C2The other end with
Resonant inductance Lr2With magnetizing inductance Lm2It is followed in series to form resonant cavity；
Output end of the vice-side winding of first transformer as Buck circuit 2；
MOS switch pipe S4With MOS switch pipe S5It simultaneously turns on or turns off, MOS switch pipe S3With MOS switch pipe S4Or MOS is opened
Close pipe S5Complementation conducting, and there are dead times.
Specifically, the topology of this high step-down ratio DC/DC converter is made of LLC circuit 1 and decompression Buck circuit 2, wherein
LLC circuit 1 is not control LLC converter, and decompression Buck circuit 2 is resonance Buck converter.The input side of the two converters is adopted
With cascaded structure, outlet side uses parallel-connection structure.
As shown in Figure 1, VinFor DC voltage source, input capacitance C is additionally provided in 2 periphery of Buck circuitin2, output capacitance Co2
With resistance Ro,
Input capacitance Cin2Both ends respectively with MOS switch pipe S3Current input terminal and MOS switch pipe S4Electric current output
End electrical connection, i.e., with MOS switch pipe S3With MOS switch pipe S4The circuit in parallel of composition.
Output capacitance Co2With resistance RoIt is in parallel with the outlet side of Buck circuit 2, i.e., with this high step-down ratio DC/DC converter
Outlet side it is in parallel.
First transformer includes a primary coil and a secondary coil, the Same Name of Ends position of primary coil and secondary coil
In the same side, the leakage inductance of first transformer is equivalent to and the concatenated resonant inductance L in primary coil one endr2, the first transformer
Primary side inductance is equivalent to the primary side winding shunt excitation inductance L with the first transformerm2, and the other end of primary side winding and secondary sideline
One end series connection (i.e. the different name end series connection of primary coil and secondary coil) of circle, and the other end of secondary coil is as Buck circuit
2 output end.
Resonant capacitance C2The other end connect with one end of the primary coil of the first transformer, be equivalent to resonant capacitance C2's
The other end and resonant inductance Lr2With magnetizing inductance Lm2It is sequentially connected in series, and constitutes resonant cavity.
As shown in Figure 1, resonant inductance Lr1With resonant inductance Lr2The respectively leakage inductance of the first transformer and the second transformer.
And respectively with resonant capacitance C1With resonant capacitance C2Form resonant network.N1And N2Respectively indicate the turn ratio and N of transformer1>>
N2。
Wherein, LLC circuit 1 is responsible for the power to the load transmitting overwhelming majority, and its working frequency is fixed, and in this way may be used
To guarantee that the work of LLC circuit 1 at best operating point, has optimum efficiency.
And Buck circuit 2 can realize output voltage stabilization by closed-loop control in than wider input voltage range.
Output power and efficiency are lower compared with LLC circuit 1, therefore will not generate to the efficiency of high step-down ratio DC/DC converter entirety
Large effect.
For Buck circuit 2, MOS switch pipe S4With MOS switch pipe S5It is switched on or off simultaneously, and MOS switch pipe S3With
MOS switch pipe S4Or MOS switch pipe S5Complementation conducting, and there are certain dead times.Due to being added in resonant capacitance C2Both ends electricity
The DC component of pressure is significantly larger than its AC compounent, therefore under the conditions of Simplified analysis, resonant capacitance C2Both end voltage can be seen
Doing is constant.Simultaneously to resonant inductance Lr2With magnetizing inductance Lm2Using voltage-second balance principle.Buck electricity under stable situation can be obtained
Shown in the DC voltage gain expression formula such as formula (1) on road 2.
Wherein, Vin2For the input voltage of Buck circuit 2, VoFor output voltage, N2For the second transformer turn ratio, D MOS
Switching tube S1Conducting dutycycle.
Due to resonant inductance Lr2Much smaller than magnetizing inductance Lm2, work as Lr2<<LmWhen, (1) formula can simplify are as follows:
And then it obtains:
Most preferred embodiment, the present embodiment are the further explanations to specific embodiment one, in the present embodiment, LLC circuit 1
Including inversion unit, resonant element, the second transformer and output rectification unit；
Inversion unit, as the input terminal of LLC circuit 1, the DC inverter for that will input is alternating current；
Resonant element, for realizing the Sofe Switch of MOS switch pipe in LLC circuit 1；
Second transformer, for realizing the voltage change ratio of fixed gain；
Output rectification unit is rectified as the output end of LLC circuit 1 for the output electric current to the second transformer
And export output voltage.
Most preferred embodiment, the present embodiment are the further explanations to specific embodiment one, in the present embodiment, inversion unit
Including MOS switch pipe S1With MOS switch pipe S2, resonant element includes resonant capacitance C1, output rectification unit includes rectifier diode
D1With rectifier diode D2；
MOS switch pipe S1Current output terminal and MOS switch pipe S2Current input terminal electrical connection；
The leakage inductance of second transformer is equivalent to resonant inductance Lr1, resonant inductance Lr1With the primary side winding of the second transformer
One end series connection, the other end of the primary side winding of the second transformer and MOS switch pipe S2Current output terminal electrical connection；Second
The primary side inductance of transformer is equivalent to magnetizing inductance Lm1, magnetizing inductance Lm1It is in parallel with the primary side winding of the second transformer；
Resonant capacitance C1One end and MOS switch pipe S1Current output terminal electrical connection, the other end with successively with resonance electricity
Feel Lr1With magnetizing inductance Lm1Resonant cavity in series；
Second transformer is the identical centre-tapped transformer of secondary side the number of turns, the both ends of the vice-side winding of second transformer
Respectively with rectifier diode D1Anode and rectifier diode D2Anode electrical connection, rectifier diode D1Cathode and rectification
Diode D2Cathode be used as 1 output end of LLC circuit；The centre cap of the vice-side winding of second transformer is grounded；
MOS switch pipe S1With MOS switch pipe S2Complementation conducting, duty ratio 50%, and there are dead times.
Specifically, the periphery of LLC circuit 1 is additionally provided with input capacitance Cin1With output capacitance Co1, input capacitance Cin1Both ends
Respectively with MOS switch pipe S1Current input terminal and MOS switch pipe S2Current output terminal electrical connection, i.e., with MOS switch pipe S1
With MOS switch pipe S2The circuit in parallel of composition.
Output capacitance Co1It is in parallel with the outlet side of LLC circuit 1, the outlet side of LLC circuit 1 simultaneously also with resistance RoIt is in parallel.
As shown in Figure 1, for LLC circuit 1, MOS switch pipe S1With MOS switch pipe S2Complementation is connected and duty ratio is fixed as
50%, and there are certain dead times.When circuit work in resonant frequency point, input and output voltage relationship such as formula
(4) shown in.
Vin1=2N1Vo (4)
Wherein Vin1For the input voltage of LLC circuit 1, VoFor output voltage, N1For the second transformer turn ratio.
Since LLC circuit 1 is connected with the input side of Buck circuit 2, the input of the two circuits is flowed through
Electric current is identical, therefore the ratio between input power of the two circuits is equal to input voltage ratio.As shown in formula (5).
The gross efficiency expression formula that high step-down ratio DC/DC converter can be obtained by relation above formula is as follows.
Wherein η1And η2The respectively efficiency of LLC circuit 1 and Buck circuit 2, works as N1>>N2When, the input voltage of LLC circuit
The significantly larger than input voltage of Buck circuit 2 can guarantee that LLC circuit 1 provides the output power of the overwhelming majority to load in this way,
Therefore the efficiency of high step-down ratio DC/DC converter entirety can be promoted.
Most preferred embodiment, the present embodiment are the further explanations to specific embodiment one, in the present embodiment, MOS switch
Pipe S1With MOS switch pipe S2Working frequency be 1MHz.
Specifically, as shown in Figure 1, setting MOS switch pipe S in the present embodiment1With MOS switch pipe S2Working frequency is 1MHz,
Using the second transformer leakage inductance as resonant inductance Lr1, with resonant capacitance C1Resonant cavity is constituted together.In order to transport LLC circuit 1
Row needs to design resonant parameter and makes near high step-down ratio DC/DC converter resonant frequency of operation point in best operating point, guarantees
Most input powers are transferred to load by LLC circuit 1, while being located at the MOS switch pipe of the second transformer primary winding
And there is Sofe Switch characteristic positioned at the diode of the second transformer secondary winding.Improve the effect of high step-down ratio DC/DC converter
Rate and power density.According to before principle analysis and Input and Output Indexes, relevant design parameter such as the following table 1 of LLC circuit 1
It is shown.
1 LLC circuit resonance parameter of table
| Element | Parameter |
| Resonant capacitance C1 | 3.6nF |
| Resonant inductance Lr1 | 7uF |
| Magnetizing inductance Lm1 | 60uF |
| Filter capacitor Co1 | 100uF |
Most preferred embodiment, the present embodiment are the further explanations to specific embodiment one, in the present embodiment, MOS switch
Pipe S3, MOS switch pipe S4With MOS switch pipe S5Working frequency be 2MHz, and MOS switch pipe S3Conducting dutycycle be 25%.
Specifically, as shown in Figure 1, the present embodiment is according between voltage gain and duty ratio for 2 part of Buck circuit
Relationship determines MOS switch pipe S in a rated operation3, MOS switch pipe S4With MOS switch pipe S5Working frequency be 2MHz,
MOS switch pipe S3Conducting dutycycle be 25%, MOS switch pipe S4With MOS switch pipe S5With MOS switch pipe S3Complementation conducting.Tool
The parameter design value of body is as shown in table 2.
2 resonance Buck unit resonant parameter of table
| Element | Parameter |
| Resonant capacitance C2 | 188nF |
| Resonant inductance Lr2 | 30nF |
| Magnetizing inductance Lm2 | 250nF |
| Filter capacitor Co2 | 100uF |
This high step-down ratio DC/DC converter can realize the high step-down ratio output of 48V/1V, rated output power 20W.LLC
The second transformer turn ratio in circuit 1 is 20:1, and the first transformer turn ratio in Buck circuit 2 is 1:1.It determines simultaneously
The MOS switch pipe S of Buck circuit 2 under nominal working conditions3Conducting dutycycle be 25%.Then have:
I.e. 1 input voltage of LLC circuit is 40V, and 2 input voltage of Buck circuit is 8V, and simulation result is as shown in Fig. 2~Fig. 6.
It can be seen that output voltage is 1V from Fig. 2 and Fig. 3, intrinsic standoff ratio is inputted close to 5.It is almost the same with theory analysis.
The diode of second transformer secondary winding realizes that ZCS (Zero Current Switch) closes in LLC circuit 1 as can be seen from Figure 4 and Figure 5
Disconnected, the MOS switch pipe of primary side winding realizes ZVS (zero voltage switch) conducting.Switching loss is reduced, high step-down ratio is improved
The efficiency and power density of DC/DC converter.It is about 16.8A according to the average output current that LLC circuit 1 is calculated in Fig. 6,
The average output current of Buck circuit 2 is about 3.2A, illustrates the function of the high step-down ratio DC/DC converter overwhelming majority of the present embodiment
Rate is transferred to load by LLC circuit 1.
Most preferred embodiment, the present embodiment are the further explanations to specific embodiment one, further include closing in the present embodiment
Ring control unit 3；The Closed Loop Control Unit 3 includes sample circuit 4, A/D conversion circuit 5 and PID control circuit 6；
Sample circuit 4 for acquiring the output voltage of high step-down ratio DC/DC converter, and exports feedback voltage signal
Vfdb；
A/D conversion circuit 5, for feedback voltage signal VfdbCarry out analog-to-digital conversion；
PID control circuit 6, for according to the feedback voltage signal V after analog-to-digital conversionfdbAnd reference signal VrefIt calculates
To pwm control signal；
Pwm control signal, for controlling MOS switch pipe S3, MOS switch pipe S4With MOS switch pipe S5Turn-on and turn-off.
Specifically, as shown in fig. 7, for the high step-down ratio DC/DC converter in the present embodiment including Closed Loop Control Unit 3
Electrical module structure chart.Since actual input voltage is fluctuation, the present invention uses independent closed loop control for Buck circuit 2
Unit 3 processed adjusts the conducting dutycycle of MOS switch pipe, so that output voltage stabilization.Actual output voltage signal is as sampling electricity
The input on road 4, the output of sample circuit 4 are a feedback voltage signal Vfdb, DSP (including A/D conversion circuit 5 and PID control circuit
6) to VfdbPID control link is sent into after sampling filter.Corresponding pwm signal control control MOS switch pipe is exported after calculating
S3, MOS switch pipe S4With MOS switch pipe S5On-off.So that output voltage can track given reference signal Vref。
Above-mentioned, N1>>N2, wherein N1For the turn ratio of the second transformer, N2For the turn ratio of the first transformer.
Claims (7)
1. a kind of high step-down ratio DC/DC converter, which is characterized in that including LLC circuit (1) and Buck circuit (2), and LLC is electric
The input side on road (1) is connected with the input side of Buck circuit (2), the outlet side of LLC circuit (1) and the output of Buck circuit (2)
Side is in parallel；
The working frequency of the LLC circuit (1) is fixed and is worked at best operating point；
The Buck circuit (2) is resonance Buck converter, which works under closed loop mode, for output
Voltage carries out closed-loop control；
Buck circuit (2) includes MOS switch pipe S3, MOS switch pipe S4, MOS switch pipe S5, resonant capacitance C2With the first transformer；
MOS switch pipe S3Current input terminal connect with the input side of LLC circuit (1), MOS switch pipe S3Current output terminal with
MOS switch pipe S4Current input terminal electrical connection, MOS switch pipe S4Current output terminal ground connection；
The primary side winding of first transformer is connected with the different name end of vice-side winding, and with MOS switch pipe S5Current input terminal electricity
Gas connection, MOS switch pipe S5Current output terminal ground connection；
The leakage inductance of first transformer is equivalent to resonant inductance Lr2, the primary side inductance of the first transformer is equivalent to magnetizing inductance Lm2, should
Magnetizing inductance Lm2It is in parallel with the primary side winding of the first transformer；
Resonant capacitance C2One end and MOS switch pipe S3Current output terminal electrical connection, resonant capacitance C2The other end and resonance
Inductance Lr2With magnetizing inductance Lm2It is followed in series to form resonant cavity；
Output end of the vice-side winding of first transformer as Buck circuit (2)；
MOS switch pipe S4With MOS switch pipe S5It simultaneously turns on or turns off, MOS switch pipe S3With MOS switch pipe S4Or MOS switch pipe
S5Complementation conducting, and there are dead times.
2. a kind of high step-down ratio DC/DC converter according to claim 1, which is characterized in that
LLC circuit (1) includes inversion unit, resonant element, the second transformer and output rectification unit；
Inversion unit, as the input terminal of LLC circuit (1), the DC inverter for that will input is alternating current；
Resonant element, for realizing the Sofe Switch of MOS switch pipe in LLC circuit (1)；
Second transformer, for realizing the voltage change ratio of fixed gain；
Output rectification unit is rectified simultaneously as the output end of LLC circuit (1) for the output electric current to the second transformer
Export output voltage.
3. a kind of high step-down ratio DC/DC converter according to claim 2, which is characterized in that
Inversion unit includes MOS switch pipe S1With MOS switch pipe S2, resonant element includes resonant capacitance C1, export rectification unit packet
Include rectifier diode D1With rectifier diode D2；
MOS switch pipe S1Current output terminal and MOS switch pipe S2Current input terminal electrical connection；
The leakage inductance of second transformer is equivalent to resonant inductance Lr1, resonant inductance Lr1With one end of the primary side winding of the second transformer
Series connection, the other end and MOS switch pipe S of the primary side winding of the second transformer2Current output terminal electrical connection；Second transformer
Primary side inductance be equivalent to magnetizing inductance Lm1, magnetizing inductance Lm1It is in parallel with the primary side winding of the second transformer；
Resonant capacitance C1One end and MOS switch pipe S1Current output terminal electrical connection, the other end with successively with resonant inductance Lr1
With magnetizing inductance Lm1Resonant cavity in series；
Second transformer is the identical centre-tapped transformer of secondary side the number of turns, the both ends difference of the vice-side winding of second transformer
With rectifier diode D1Anode and rectifier diode D2Anode electrical connection, rectifier diode D1Cathode and rectification two poles
Pipe D2Cathode be used as LLC circuit (1) output end；The centre cap of the vice-side winding of second transformer is grounded；
MOS switch pipe S1With MOS switch pipe S2Complementation conducting, duty ratio 50%, and there are dead times.
4. a kind of high step-down ratio DC/DC converter according to claim 3, which is characterized in that MOS switch pipe S1It is opened with MOS
Close pipe S2Working frequency be 1MHz.
5. a kind of high step-down ratio DC/DC converter according to claim 1,2,3 or 4, which is characterized in that MOS switch pipe
S3, MOS switch pipe S4With MOS switch pipe S5Working frequency be 2MHz, and MOS switch pipe S3Conducting dutycycle be 25%.
6. a kind of high step-down ratio DC/DC converter according to claim 5, which is characterized in that further include closed-loop control list
First (3)；The Closed Loop Control Unit (3) includes sample circuit (4), A/D conversion circuit (5) and PID control circuit (6)；
The sample circuit (4) for acquiring the output voltage of the high step-down ratio DC/DC converter, and exports feedback voltage
Signal Vfdb；
The A/D conversion circuit (5), for the feedback voltage signal VfdbCarry out analog-to-digital conversion；
The PID control circuit (6), for according to the feedback voltage signal V after analog-to-digital conversionfdbAnd reference signal VrefIt calculates
Obtain pwm control signal；
The pwm control signal, for controlling MOS switch pipe S3, MOS switch pipe S4With MOS switch pipe S5Turn-on and turn-off.
7. a kind of high step-down ratio DC/DC converter according to claim 2,3,4 or 6, which is characterized in that N1>>N2,
In, N1For the turn ratio of the second transformer, N2For the turn ratio of the first transformer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201910611754.3A CN110492750A (en) | 2019-07-08 | 2019-07-08 | A kind of high step-down ratio DC/DC converter |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910611754.3A CN110492750A (en) | 2019-07-08 | 2019-07-08 | A kind of high step-down ratio DC/DC converter |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7872886B2 (en) * | 2008-02-20 | 2011-01-18 | Virginia Tech Intellectual Properties, Inc. | Quasi-parallel voltage regulator |
| CN109980934A (en) * | 2019-04-17 | 2019-07-05 | 哈尔滨工业大学 | The two-way DC/DC converter of the high no-load voltage ratio of high frequency based on coupling inductance |
-
2019
- 2019-07-08 CN CN201910611754.3A patent/CN110492750A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7872886B2 (en) * | 2008-02-20 | 2011-01-18 | Virginia Tech Intellectual Properties, Inc. | Quasi-parallel voltage regulator |
| CN109980934A (en) * | 2019-04-17 | 2019-07-05 | 哈尔滨工业大学 | The two-way DC/DC converter of the high no-load voltage ratio of high frequency based on coupling inductance |
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