CN211981753U - LLC digital control system - Google Patents
LLC digital control system Download PDFInfo
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- CN211981753U CN211981753U CN202021122494.8U CN202021122494U CN211981753U CN 211981753 U CN211981753 U CN 211981753U CN 202021122494 U CN202021122494 U CN 202021122494U CN 211981753 U CN211981753 U CN 211981753U
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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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Abstract
The utility model provides a LLC digital control system, including input capacitance Cin, input capacitance Cin ' S positive pole is connected with first former limit switch tube Q1 ' S D end, input capacitance Cin ' S negative pole is connected with second former limit switch tube Q2 ' S S end, be connected with resonant inductor Lr ' S one end between first former limit switch tube Q1 ' S S end and the second former limit switch tube Q2 ' S D end, resonant inductor Lr ' S the other end is connected with the one end of transformer Lm input, the other end of transformer Lm input is connected with resonant capacitor Cr ' S one end, resonant capacitor Cr ' S the other end with second former limit switch tube Q2 ' S S end is connected, and the control scheme of LLC adopts frequency conversion + change duty cycle control scheme in this system.
Description
Technical Field
The utility model relates to a converter field especially relates to a LLC digital control system.
Background
The LLC frequency conversion control has the disadvantage that as the switching frequency rises, the LLC (LLC series resonant converter) topology, when the switching frequency exceeds the resonant frequency, its output current will become continuous, so the efficiency and reverse recovery of the output power tube will increase the switching stress of the power tube, and at the same time, because the current is continuous, the soft switching effect of the input power tube will also be worsened, thus increasing the loss of the whole machine; with the rise of the switching frequency, when the switching frequency exceeds the resonant frequency, the continuous rise of the switching frequency also causes the increase of the driving loss, so that the soft switching effect is greatly reduced, and the loss of the whole machine is also increased.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to the not enough of above-mentioned prior art, provide an LLC digital control system, prevented that the LLC module from getting into the work of step-down area, guarantee the soft switching characteristic of input power tube.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model provides a LLC digital control system, including input capacitance Cin, input capacitance Cin ' S positive pole is connected with first former limit switch tube Q1 ' S D end, input capacitance Cin ' S negative pole is connected with second former limit switch tube Q2 ' S S end, be connected with resonant inductor Lr ' S one end between first former limit switch tube Q1 ' S S end and the second former limit switch tube Q2 ' S D end, resonant inductor Lr ' S the other end is connected with the one end of transformer Lm input, the other end of transformer Lm input is connected with resonant capacitor Cr ' S one end, resonant capacitor Cr ' S the other end with second former limit switch tube Q2 ' S S end is connected.
Further, a center tap of an output end of the resonant inductor Lr is connected to one end of the output capacitor Cout, and the other end of the output capacitor Cout is connected to one end of the third rectifier switch Q3 and one end of the fourth rectifier switch Q4.
Further, the third rectifying switch tube Q3 and the fourth rectifying switch tube Q4 are connected in parallel.
Further, the other end of the third rectifying switch Q3 is connected to one end of the output terminal of the transformer Lm, and the other end of the fourth rectifying switch Q4 is connected to the other end of the output terminal of the transformer Lm.
Further, still include DSC master control circuit and output voltage sampling circuit, output voltage sampling circuit inputs LLC main power circuit's voltage sampling value DSC master control circuit, DSC master control circuit receives the voltage sampling value, controls LLC main power circuit's output.
The utility model has the advantages that: the LLC control scheme in the system adopts a frequency conversion and duty ratio change control scheme;
selecting LLC to work in a boosting area, and designing a switching frequency to be close to but not more than a resonant frequency;
because the LLC input voltage range is relatively narrow, in order to meet the full input voltage range, when the switching frequency will be gradually increased from the lowest switching frequency of the software design to the resonant frequency according to the control of the digital loop as the input voltage increases, but when the input voltage exceeds the designed maximum switching frequency, the input voltage continues to increase, if the switching frequency is not increased, the output voltage will also increase as the input voltage increases, at this time, in order to prevent the increase of the output voltage, the switching frequency is changed from the frequency conversion control mode to the variable duty ratio control, so as to limit the increase of the output voltage, thereby maintaining the stability of the output voltage;
since the switching frequency is limited to be lower than the resonance frequency, the driving loss is limited;
because the switching frequency is limited to be lower than the resonant frequency, the LLC module is prevented from entering a voltage reduction region to work, and the soft switching characteristic of the input end power tube can be ensured.
Drawings
Fig. 1 is a circuit diagram of an LLC digital control system of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.
Referring to fig. 1, an LLC digital control system includes an input capacitor Cin, an anode of the input capacitor Cin is connected to a D-end of a first primary-side switching tube Q1, a cathode of the input capacitor Cin is connected to an S-end of a second primary-side switching tube Q2, an S-end of the first primary-side switching tube Q1 and a D-end of the second primary-side switching tube Q2 are connected to one end of a resonant inductor Lr, another end of the resonant inductor Lr is connected to one end of an input end of a transformer Lm, another end of the input end of the transformer Lm is connected to one end of a resonant capacitor Cr, and another end of the resonant capacitor Cr is connected to an S-end of the second primary-side switching tube Q2.
The center tap of the output end of the resonant inductor Lr is connected with one end of an output capacitor Cout, and the other end of the output capacitor Cout is connected with one end of a third rectifier switch tube Q3 and one end of a fourth rectifier switch tube Q4.
The third rectifying switch tube Q3 and the fourth rectifying switch tube Q4 are connected in parallel.
The other end of the third rectifying switch tube Q3 is connected with one end of the output end of the transformer Lm, and the other end of the fourth rectifying switch tube Q4 is connected with the other end of the output end of the transformer Lm.
The digital controller DSC (digital controller, dsPIC33EP64GS506) main control circuit 1 and the output voltage sampling circuit 2 are further included, the output voltage sampling circuit 2 inputs the voltage sampling value of the LLC main power circuit into the DSC main control circuit 1, and the DSC main control circuit receives the voltage sampling value and controls the output of the LLC main power circuit.
The DSC main control circuit is responsible for sampling the output voltage and carrying out internal calculation according to the sampled output voltage to obtain a PFM driving signal, thereby controlling the output of the LLC main power circuit.
And the output voltage sampling circuit is used for inputting the output voltage sampling value of the LLC into the DSC main control circuit.
The output voltage sampling circuit 2 is formed by connecting two resistors in series
Internal calculation, using loop calculation, 2P2Z, 3P3Z or PID algorithm
The system adopts a variable frequency controlled LLC main power circuit.
Usually, the LLC main power circuit adopts frequency conversion control, and when the input voltage is relatively high and the output load is no-load, the output voltage is higher than the normal output voltage due to its own characteristics. And the system can solve the problem well.
Working frequency fs of LLC main power circuit<Resonance frequency fr of LLC resonance circuit
I.e. the LLC main power circuit only operates in the boost region of the LLC.
If the input voltage becomes high or the load is reduced, the output voltage becomes high, and the operating frequency fs needs to be increased to reduce the output voltage, and when fs is equal to the resonant frequency fr, if the output voltage is increased, the switching frequency is not changed, but the switching duty ratio is adjusted, and the purpose of reducing the output voltage is achieved by reducing the switching duty ratio.
If the input voltage becomes low or the load increases, this will result in a low output voltage, at which point if the operating frequency fs is in a variable duty cycle mode, i.e. fs ═ fr, the increase in the output voltage is achieved by increasing the duty cycle.
If the input voltage becomes low, or the load increases, this will result in a low output voltage, at which point if the operating frequency fs is in the frequency conversion mode, i.e. fs < fr, the operation fs is continued to be reduced to achieve a rise in the output voltage.
The drive of the output synchronous rectifier tube is only switched on during the resonance period of the primary side Lr and Cr, and is not switched on in the rest time. By doing so, a good anti-backflow effect can be achieved.
The system scheme has the advantages that:
the working frequency is always less than or equal to the resonant frequency, so that the switching loss and the driving loss of the switching tube are less than those of a normal LLC circuit;
the working frequency is always less than or equal to the resonant frequency, so that the LLC can work in a boosting area, soft switching is realized on the primary side, and the efficiency is improved.
The working frequency is always less than or equal to the resonant frequency, so that the LLC can work in a boosting area, and the secondary side can realize soft switching.
The working frequency is always less than or equal to the resonant frequency, the LLC works in the boosting area, the secondary side can prevent the reverse flow of the output current, and the drive can be turned off after the resonance is finished, so that the reverse flow of the output current is prevented.
The above-mentioned embodiments only express the embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (5)
1. An LLC digital control system, characterized by: the transformer Lm low-voltage power supply comprises an input capacitor Cin, wherein the positive electrode of the input capacitor Cin is connected with the D end of a first primary side switching tube Q1, the negative electrode of the input capacitor Cin is connected with the S end of a second primary side switching tube Q2, the S end of a first primary side switching tube Q1 and the D end of a second primary side switching tube Q2 are connected with one end of a resonant inductor Lr, the other end of the resonant inductor Lr is connected with one end of the input end of a transformer Lm, the other end of the input end of the transformer Lm is connected with one end of a resonant capacitor Cr, and the other end of the resonant capacitor Cr is connected with the S end of the second primary side switching tube Q2.
2. The LLC digital control system of claim 1, wherein: the center tap of the output end of the resonant inductor Lr is connected with one end of an output capacitor Cout, and the other end of the output capacitor Cout is connected with one end of a third rectifier switch tube Q3 and one end of a fourth rectifier switch tube Q4.
3. An LLC digital control system as claimed in claim 2, wherein: the third rectifying switch tube Q3 and the fourth rectifying switch tube Q4 are connected in parallel.
4. An LLC digital control system according to claim 3, wherein: the other end of the third rectifying switch tube Q3 is connected with one end of the output end of the transformer Lm, and the other end of the fourth rectifying switch tube Q4 is connected with the other end of the output end of the transformer Lm.
5. The LLC digital control system of claim 1, wherein: still include DSC master control circuit and output voltage sampling circuit, output voltage sampling circuit inputs LLC main power circuit's voltage sampling value DSC master control circuit, DSC master control circuit receives voltage sampling value, controls LLC main power circuit's output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021122494.8U CN211981753U (en) | 2020-06-17 | 2020-06-17 | LLC digital control system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021122494.8U CN211981753U (en) | 2020-06-17 | 2020-06-17 | LLC digital control system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211981753U true CN211981753U (en) | 2020-11-20 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021122494.8U Active CN211981753U (en) | 2020-06-17 | 2020-06-17 | LLC digital control system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN211981753U (en) |
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2020
- 2020-06-17 CN CN202021122494.8U patent/CN211981753U/en active Active
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