CN219843538U

CN219843538U - Voltage equalizing circuit

Info

Publication number: CN219843538U
Application number: CN202321368411.7U
Authority: CN
Inventors: 马超; 李海锋; 史耀庭; 刘士军
Original assignee: Shandong Longertek Technology Co Ltd
Current assignee: Shandong Longertek Technology Co Ltd
Priority date: 2023-05-30
Filing date: 2023-05-30
Publication date: 2023-10-17
Anticipated expiration: 2033-05-30

Abstract

The utility model provides a voltage equalizing circuit, which comprises a first input capacitor and a second input capacitor which are connected in series, wherein two ends of the first input capacitor are connected with a first LLC switch circuit, the first LLC switch circuit is connected with a primary side of a first transformer, two ends of the second input capacitor are connected with a second LLC switch circuit, the second LLC switch circuit is connected with a primary side of a second transformer, secondary sides of the first transformer and the second transformer are connected with a rectifying circuit, and the rectifying circuit is connected with two ends of an output capacitor; the upper bridge arm of the first LLC switch circuit and the upper bridge arm of the second LLC switch circuit are simultaneously turned on or turned off, and the lower bridge arm of the first LLC switch circuit and the lower bridge arm of the second LLC switch circuit are simultaneously turned on or turned off. The utility model adjusts the gains of the first LLC switch circuit and the second LLC switch circuit by changing the on-off frequency, thereby realizing voltage equalizing.

Description

Voltage equalizing circuit

Technical Field

The utility model relates to the technical field of power supplies, in particular to a voltage equalizing circuit.

Background

With the rapid development of high-frequency power electronics in recent years, high-frequency conversion technology is adopted in more and more high-voltage application occasions. LLC converters are widely used in various occasions due to the characteristics of simple topological structure, high efficiency and the like. When LLC converters are used in a high voltage application in a multi-stage series, the parameters of the actual lines or components may not be completely identical, which may cause the voltages across the power transistors of each converter to be different, which may affect the safe operation of the converter.

The present utility model has been made in view of this.

Disclosure of Invention

The utility model aims to solve the technical problem of overcoming the defects of the prior art and providing a voltage equalizing circuit, wherein an upper bridge arm and a lower bridge arm of a first LLC switch circuit and a second LLC switch circuit are both turned on or off at the same time, and gains of the upper bridge arm and the lower bridge arm are adjusted by adjusting the on and off frequencies of the upper bridge arm and the lower bridge arm, so that voltage equalizing is realized.

In order to solve the technical problems, the utility model adopts the basic conception of the technical scheme that:

the voltage equalizing circuit comprises a first input capacitor and a second input capacitor which are connected in series, wherein two ends of the first input capacitor are connected with a first LLC switch circuit, the first LLC switch circuit is connected with a primary side of a first transformer, two ends of the second input capacitor are connected with a second LLC switch circuit, the second LLC switch circuit is connected with a primary side of a second transformer, secondary sides of the first transformer and the second transformer are connected with a rectifying circuit, and the rectifying circuit is connected with two ends of an output capacitor;

the upper bridge arm of the first LLC switch circuit and the upper bridge arm of the second LLC switch circuit are simultaneously turned on or turned off, and the lower bridge arm of the first LLC switch circuit and the lower bridge arm of the second LLC switch circuit are simultaneously turned on or turned off.

Further, two ends of the first input capacitor are further connected with a first voltage sampling circuit, an output end of the first voltage sampling circuit is connected with an input end of a first comparator, and the first comparator is used for comparing a first sampling voltage of the first input capacitor acquired by the first voltage sampling circuit with a reference voltage.

Further, two ends of the second input capacitor are also connected with a second voltage sampling circuit, an output end of the second voltage sampling circuit is connected with an input end of a second comparator, and the second comparator is used for comparing a second sampling voltage of the second input capacitor acquired by the second voltage sampling circuit with a reference voltage.

Further, the topology structures of the first LLC switching circuit and the second LLC switching circuit are the same.

Further, the first LLC switching circuit comprises a first full-bridge circuit and a first resonant network;

the first full-bridge circuit comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube which are respectively connected in series, wherein the first switching tube and the third switching tube are communicated through a first resonant network.

Further, the first resonant network comprises a first resonant inductor, a first exciting inductor and a first resonant capacitor which are connected in series, and the primary side of the first transformer is connected with the first exciting inductor in parallel.

Further, the second LLC switching circuit comprises a second full bridge circuit and a second resonant network;

the second full-bridge circuit comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which are respectively connected in series, wherein the fifth switching tube and the seventh switching tube are communicated through a second resonance network.

Further, the second resonant network comprises a second resonant inductor, a second excitation inductor and a second resonant capacitor which are connected in series, and the primary side of the second transformer is connected with the second excitation inductor in parallel.

Further, the first switching tube, the third switching tube, the fifth switching tube and the seventh switching tube are simultaneously turned on or turned off;

the second switching tube, the fourth switching tube, the sixth switching tube and the eighth switching tube are simultaneously turned on or turned off.

Further, the parameters of the first transformer and the second transformer are the same;

the parameters include primary side turns, secondary side turns, inductance and leakage inductance values.

After the technical scheme is adopted, compared with the prior art, the utility model has the following beneficial effects:

1. in the utility model, the upper bridge arm and the lower bridge arm of the first LLC switch circuit and the second LLC switch circuit are both turned on or off at the same time, and the gain of the first LLC switch circuit and the second LLC switch circuit can be changed by changing the frequency of turning on or off of the first LLC switch circuit, so that the voltage difference between the first input capacitor and the second input capacitor is reduced, and the voltage equalizing is realized.

2. The voltage equalizing circuit is also provided with a first voltage sampling circuit, and if the first sampling voltage of the first input capacitor is larger than the reference voltage, the driving signal for driving the first LLC switching circuit is closed, so that the reliability of the voltage equalizing circuit is ensured.

3. The voltage equalizing circuit is also provided with a second voltage sampling circuit, and if the second sampling voltage of the second input capacitor is larger than the reference voltage, the driving signal for driving the second LLC switching circuit is closed, so that the reliability of the voltage equalizing circuit is ensured.

The following describes the embodiments of the present utility model in further detail with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the utility model. It is evident that the drawings in the following description are only examples, from which other drawings can be obtained by a person skilled in the art without the inventive effort. In the drawings:

FIG. 1 is a schematic circuit diagram of a voltage equalizing circuit of the present utility model;

FIG. 2 is a schematic diagram of the connection of a first sampling circuit and a second sampling circuit according to the present utility model;

fig. 3 is a topology diagram of the voltage equalizing circuit of the present utility model.

The main elements in the figure are as follows: 1. a first input capacitance; 2. a second input capacitance; 3. a first LLC switching circuit; 301. a first switching tube; 302. a second switching tube; 303. a third switching tube; 304. a fourth switching tube; 305. a first resonant inductor; 306. a first excitation inductance; 307. a first resonant capacitor; 4. a second LLC switching circuit; 401. a fifth switching tube; 402. a sixth switching tube; 403. a seventh switching tube; 404. an eighth switching tube; 405. a second resonant inductor; 406. a second excitation inductance; 407. a second resonance capacitor; 5. a first transformer; 6. a second transformer; 7. a rectifying circuit; 8. an output capacitance; 9. a first voltage sampling circuit; 10. a first comparator; 11. a second voltage sampling circuit; 12. and a second comparator.

It should be noted that the drawings and the written description are not intended to limit the scope of the inventive concept in any way, but to illustrate the inventive concept to those skilled in the art by referring to the specific embodiments.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions in the embodiments will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present utility model, and the following embodiments are used to illustrate the present utility model, but are not intended to limit the scope of the present utility model.

In the description of the present utility model, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Along with the rapid development of high-frequency power electronic technology in the prior art, more and more high-voltage application occasions adopt LLC converters to carry out high-frequency conversion, but when the LLC converters are connected in series in multiple stages, the voltage on each LLC converter power tube can be different due to the fact that parameters of actual circuits or components cannot be completely consistent, and the situation can influence the working performance of the LLC converters, so that voltage equalization is needed.

As shown in fig. 1-3, the utility model provides a voltage equalizing circuit, which comprises a first input capacitor 1 and a second input capacitor 2 connected in series, wherein two ends of the first input capacitor 1 are connected with a first LLC switch circuit 3, the first LLC switch circuit is connected with a primary side of a first transformer 5, two ends of the second input capacitor 2 are connected with a second LLC switch circuit 4, and the second LLC switch circuit 4 is connected with a primary side of a second transformer 6.

The secondary sides of the first transformer 5 and the second transformer 6 are connected with a rectifying circuit 7, the rectifying circuit 7 is connected with two ends of an output capacitor 8, and the rectifying circuit 7 is used for converting alternating current into direct current.

The upper bridge arm of the first LLC switch circuit 3 and the upper bridge arm of the second LLC switch circuit 4 are simultaneously turned on or turned off, and the lower bridge arm of the first LLC switch circuit 3 and the lower bridge arm of the second LLC switch circuit 4 are simultaneously turned on or turned off.

Furthermore, the utility model can drive the upper bridge arm of the first LLC switch circuit 3 and the upper bridge arm of the second LLC switch circuit 4 through the first PWM driving signal, and drive the lower bridge arm of the first LLC switch circuit 3 and the lower bridge arm of the second LLC switch circuit 4 through the second PWM driving signal. At this time, the on/off frequency of the upper bridge arm and the lower bridge arm is the frequency of the PWM driving signal driving the first LLC switch circuit 3 and the second LLC switch circuit 4, and the gains of the first LLC switch circuit 3 and the second LLC switch circuit 4 are increased with the decrease of the frequency.

In one embodiment of the present utility model, when the voltage equalizing circuit is in an intermittent mode, i.e. in an idle mode, the output voltage is gradually accumulated, and in order to avoid that the safety of the circuit is affected by the excessive output voltage, the PWM driving signal is turned off when the output voltage is accumulated to a first set value; when the output voltage is reduced to the second set value, the PWM driving signal is turned on again, and each turn-on of the PWM driving signal is turned on at the maximum frequency.

When the voltage difference between the first input voltage 1 and the second input capacitor 2 is greater than the set difference, the gain can be increased by reducing the frequency of the first PWM driving signal and the second PWM driving signal, so that the voltage difference between the first input voltage 1 and the second input voltage 2 is reduced, and when the voltage difference is less than or equal to the set difference, the current frequency of the first PWM driving signal and the second PWM driving signal is maintained, and the circuit realizes voltage equalizing.

In this embodiment, the first PWM driving signal and the second PWM driving signal are complementary, that is, when the first PWM driving signal is at a high level, the second PWM driving signal is at a low level, and at this time, the upper bridge arms of the first LLC switch circuit 3 and the second LLC switch circuit 4 are in an on state, and the lower bridge arms of the first LLC switch circuit 3 and the second LLC switch circuit 4 are in an off state; when the first PWM driving signal is at a low level, the second PWM driving signal is at a high level, and at this time, the upper bridge arms of the first LLC switch circuit 3 and the second LLC switch circuit 4 are in an off state, and the lower bridge arms of the first LLC switch circuit 3 and the second LLC switch circuit 4 are in an on state. The soft switching of the first LLC driving circuit 3 and the second LLC driving circuit 4 can be achieved by the complementation of the first PWM driving signal and the second PWM driving signal.

In one embodiment of the present utility model, in order to ensure reliability of the voltage equalizing circuit and avoid the voltage of the first input capacitor 1 from being too high, a first voltage sampling circuit 9 is further connected to two ends of the first input capacitor 1, the first voltage sampling circuit 9 is used for sampling the voltage of the first input capacitor 1, an output end of the first voltage sampling circuit 9 is connected to an input end of the first comparator 10, the first comparator 10 compares the first sampled voltage of the first input capacitor 1 with a reference voltage, and if the first sampled voltage is greater than the reference voltage, the driving signal is turned off.

In yet another embodiment of the present utility model, the second voltage sampling circuit 11 is further connected to two ends of the second input capacitor 2, the second voltage sampling circuit 11 is configured to sample the voltage of the second input capacitor 2, an output end of the second voltage sampling circuit 11 is connected to an input end of the second comparator 12, the second comparator 12 compares the second sampled voltage of the second input capacitor 2 with the reference voltage, and if the second sampled voltage is greater than the reference voltage, the driving signal is turned off.

The topology of the first LLC switch circuit 3 and the second LLC switch circuit 4 are identical, in particular:

the first LLC switching circuit 3 includes a first full-bridge circuit and a first resonant network, the first full-bridge circuit includes a first switching tube 301, a second switching tube 302, a third switching tube 303, and a fourth switching tube 304 connected in series, respectively, the first switching tube 301 and the third switching tube 303, and the second switching tube 302 and the fourth switching tube 304 are all connected through the first resonant network. Compared with the second switching tube 302 and the fourth switching tube 304 which are turned on, the directions of currents in the circuits when the first switching tube 301 and the third switching tube 303 are turned on are opposite, so that the direct current on the first input capacitor 1 is converted into alternating current.

The first resonant network includes a first resonant inductor 305, a first excitation inductor 306 and a first resonant capacitor 307 connected in series, and the primary side of the first transformer 5 is connected in parallel with the first excitation inductor 306, and the secondary side thereof is connected with the rectifying circuit 7.

The second LLC switching circuit includes a second full-bridge circuit and a second resonant network, the second full-bridge circuit includes a fifth switching tube 401, a sixth switching tube 402, a seventh switching tube 403, and an eighth switching tube 404 connected in series, respectively, wherein the fifth switching tube 401 and the seventh switching tube 403, the sixth switching tube 402 and the eighth switching tube 404 are all connected through the second resonant network, and compared with when the sixth switching tube 402 and the eighth switching tube 404 are turned on, the current directions in the circuits when the fifth switching tube 401 and the seventh switching tube 403 are turned on are opposite, so that the direct current of the second input capacitor 2 is converted into alternating current.

The second resonant network includes a second resonant inductor 405, a second exciting inductor 406 and a second resonant capacitor 407 connected in series, and the primary side of the second transformer 6 is connected in parallel with the second exciting inductor 406, and the secondary side thereof is connected with the rectifying circuit 7.

The upper bridge arm of the first LLC switch circuit 3 and the upper bridge arm of the second LLC switch circuit 4 are turned on or off simultaneously, specifically, the first switch tube 301, the third switch tube 303, the fifth switch tube 401, and the seventh switch tube 403 are turned on or off simultaneously.

The lower bridge arm of the first LLC switch circuit 3 and the lower bridge arm of the second LLC switch circuit 4 are turned on or off simultaneously, specifically, the second switch tube 302, the fourth switch tube 304, the sixth switch tube 402, and the eighth switch tube 404 are turned on or off simultaneously.

In the utility model, the parameters of the first transformer 5 and the second transformer 6 are the same, and the parameters comprise primary winding number, secondary winding number, inductance and leakage inductance.

The voltage equalizing circuit of the utility model has the specific working procedures that:

when the voltage equalizing circuit is in the intermittent mode, if the output voltage of the voltage equalizing circuit is smaller than the second set value, the PWM driving signal is turned on at the maximum frequency to drive the first LLC switch circuit 3 and the second LLC switch circuit 4 to operate.

If the voltage difference between the first input capacitor 1 and the second input capacitor 2 is greater than the set difference, the frequency of the PWM driving signal is reduced, and the gains of the first LLC switch circuit 3 and the second LLC switch circuit 4 are increased accordingly until the voltage difference between the first input capacitor 1 and the second input capacitor 2 is less than or equal to the set difference, and then the current frequency of the PWM driving signal is maintained.

Specifically, the first switching tube 301, the third switching tube 303, the fifth switching tube 401, and the seventh switching tube 403 are simultaneously driven by the first PWM driving signal with a 50% duty ratio; the second switching tube 302, the fourth switching tube 304, the sixth switching tube 402, and the eighth switching tube 404 are simultaneously driven by the second PWM driving signal with a 50% duty ratio. And the first PWM drive signal and the second PWM drive signal are complementary to realize soft switching of the first LLC switch circuit 3 and the second LLC switch circuit 4.

Since the output voltage of the voltage equalizing circuit is accumulated in the intermittent mode, in order to avoid the output voltage from being too high, when the output voltage reaches the first set value, the PWM driving signal is turned off.

When the output voltage of the voltage equalizing circuit falls to the second set value again, the PWM driving signal is started again, and the flow is repeated again.

The foregoing description is only a preferred embodiment of the present utility model, and the present utility model is not limited to the above-mentioned embodiment, but is not limited to the above-mentioned embodiment, and any simple modification, equivalent change and modification made by the technical matter of the present utility model can be further combined or replaced by equivalent embodiments within the scope of the technical proposal of the present utility model without departing from the scope of the technical proposal of the present utility model.

Claims

1. The voltage equalizing circuit is characterized by comprising a first input capacitor and a second input capacitor which are connected in series, wherein two ends of the first input capacitor are connected with a first LLC switching circuit, the first LLC switching circuit is connected with a primary side of a first transformer, two ends of the second input capacitor are connected with a second LLC switching circuit, the second LLC switching circuit is connected with a primary side of a second transformer, secondary sides of the first transformer and the second transformer are connected with a rectifying circuit, and the rectifying circuit is connected with two ends of an output capacitor;

2. The voltage equalizing circuit according to claim 1, wherein the two ends of the first input capacitor are further connected with a first voltage sampling circuit, the output end of the first voltage sampling circuit is connected with the input end of a first comparator, and the first comparator is used for comparing the first sampling voltage of the first input capacitor collected by the first voltage sampling circuit with a reference voltage.

3. The voltage equalizing circuit according to claim 1, wherein the two ends of the second input capacitor are further connected with a second voltage sampling circuit, the output end of the second voltage sampling circuit is connected with the input end of a second comparator, and the second comparator is used for comparing the second sampling voltage of the second input capacitor collected by the second voltage sampling circuit with the reference voltage.

4. The voltage divider circuit of claim 1, wherein the first LLC switching circuit and the second LLC switching circuit are identical in topology.

5. The voltage grading circuit according to claim 4, wherein the first LLC switching circuit comprises a first full bridge circuit and a first resonant network;

6. The voltage grading circuit according to claim 5, wherein the first resonant network comprises a first resonant inductor, a first excitation inductor and a first resonant capacitor in series, and wherein the primary side of the first transformer is connected in parallel with the first excitation inductor.

7. The voltage divider circuit of claim 5, wherein the second LLC switching circuit comprises a second full bridge circuit and a second resonant network;

8. The voltage grading circuit according to claim 7, wherein the second resonant network comprises a second resonant inductor, a second excitation inductor and a second resonant capacitor in series, and the primary side of the second transformer is connected in parallel with the second excitation inductor.

9. The voltage equalizing circuit according to claim 7, wherein the first switching tube, the third switching tube, the fifth switching tube and the seventh switching tube are simultaneously turned on or off;

10. A voltage equalizing circuit according to any one of claims 1-9, wherein the parameters of said first transformer and second transformer are identical;