Reverse boost control circuit according to LLC

Abstract

The utility model belongs to the technical field of inverters, and discloses an LLC (logical link control) reverse boost control circuit, which comprises a switching power supply LLC reverse push-pull circuit, an inverter circuit, an LLC boost circuit, a battery end sampling circuit and a load end sampling circuit, when the loading capacity is larger than a certain limit value, the bus voltage is raised through LLC boosting, the loading capacity is improved, the secondary side MCU samples the battery end voltage, the battery end voltage is processed and then transmitted to the primary side MCU, the primary side MCU samples the load end power, and after the requirement is met, control boosting is conducted on a switching tube of the LLC circuit. The beneficial effects of the utility model are that a wider DC input range is provided, when the DC input voltage is low, the reverse boost function of the LLC is automatically turned on, the bus voltage is improved, the output voltage clipping is relieved, and the loading capability is enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of inverters, in particular to an LLC reverse boost control circuit. Background Art

[0002] The bidirectional energy storage inverter charges the battery with AC-DC and discharges with DC-AC. For higher power energy storage inverters, the bidirectional inverter is generally designed as a totem pole without PFC + full-bridge LLC soft switch + SR synchronous rectification. The DC input range is required to be wider and wider, and LLC reverse boost needs to be designed to adapt to a wider voltage range.

[0003] Therefore, it is necessary to provide a reverse boost control circuit based on LLC, provide a wider DC input range, autonomously open the reverse boost function of LLC when the DC input voltage is low, increase the bus voltage, alleviate output voltage clipping and enhance load capacity. Utility Model Content

[0004] The utility model discloses a control method for a wide range DC input of a bidirectional energy storage inverter based on an LLC reverse boost control circuit, which relates to a switch power supply control circuit and can effectively solve the technical problems involved in the background technology.

[0005] To achieve the above purpose, the technical solution of the utility model is:

[0006] A reverse boost control circuit according to LLC, comprising AC input ports LIN and NIN, DC ports +DC and -DC, a primary MCU, a secondary MCU, a DC voltage sampling unit and an AC voltage sampling unit, wherein the primary MCU is connected to the AC input ports LIN and NIN through the AC voltage sampling unit, the secondary MCU is connected to the DC ports +DC and -DC through the DC voltage sampling unit, and the primary MCU is connected to the secondary MCU;

[0007] The port LIN is connected to one end of the capacitor C3 and one end of the inductor L13, the other end of the inductor L13 is connected to the source of the MOS transistor Q13 and the drain of the MOS transistor Q14, the port NIN is connected to the other end of the capacitor C3, the source of the MOS transistor Q16 and the drain of the MOS transistor Q15, the drain of the MOS transistor Q13 is connected to the drain of the MOS transistor Q16, one end of the capacitor C1, the drain of the MOS transistor Q8 and the drain of the MOS transistor Q11, the source of the MOS transistor Q14 is connected to the drain of the MOS transistor Q15, and the drain of the MOS transistor Q13 is connected to the drain of the MOS transistor Q16, one end of the capacitor C1, the drain of the MOS transistor Q8 and the drain of the MOS transistor Q11. The source of the MOS transistor Q15, the other end of the capacitor C1, the source of the MOS transistor Q9, the source of the MOS transistor Q10 and the port GND are connected; the source of the MOS transistor Q8 is connected to the drain of the MOS transistor Q9 and the pin 3 of the transformer TX2; the source of the MOS transistor Q11 is connected to the drain of the MOS transistor Q10 and one end of the inductor L1; the other end of the inductor L1 is connected to one end of the capacitor C76; the other end of the capacitor C76 is connected to the pin 4 of the transformer TX2;

[0008] The port +DC is connected to one end of the capacitor C2, the drain of the MOS transistor Q4 and the drain of the MOS transistor Q1, the source of the MOS transistor Q1 is connected to the pin 1 of the transformer TX2 and the drain of the MOS transistor Q2, the source of the MOS transistor Q4 is connected to the pin 2 of the transformer TX2 and the drain of the MOS transistor Q3, and the port -DC is connected to the other end of the capacitor C2, the source of the MOS transistor Q3 and the source of the MOS transistor Q2.

[0009] The utility model is suitable for a bidirectional energy storage inverter with a totem pole bridgeless PFC+full-bridge LLC soft switch+SR synchronous rectification design, which can provide a wider DC input range, and automatically open the LLC reverse boost function when the DC input voltage is low, thereby increasing the bus voltage, alleviating the output voltage clipping and enhancing the load capacity. The circuit can be divided into a switching power supply LLC reverse push-pull circuit, an inverter circuit, an LLC boost circuit, and a battery end and a load end sampling circuit. The push-pull circuit is connected to the battery, and by sampling the battery end voltage, when the input voltage is lower than a certain limit value and the load capacity is greater than a certain limit value, the bus voltage is raised by LLC boosting to improve the load capacity. The secondary side MCU samples the battery end voltage, and transmits it to the primary side MCU after processing. The primary side MCU samples the load end power, and controls the LLC circuit switch tube to boost after meeting the requirements. The LLC reverse push-pull circuit is used to boost the battery end voltage. The LLC circuit does not work under normal circumstances during inversion and is used for bus boosting. The inverter circuit inverts the bus voltage and outputs a sine wave. Battery terminal voltage sampling and load terminal power sampling are used as the basis for LLC reverse boost.

[0010] As a preferred improvement of the present invention: Pin 1 and Pin 2 of the transformer TX2 share one coil, and Pin 3 and Pin 4 share one coil.

[0011] As a preferred improvement of the utility model: the LLC reverse boost control circuit further includes AC output ports LOUT and NOUT, the port LOUT is connected to the port LIN through a relay, and the port NOUT is connected to the port NIN through a relay.

[0012] As a preferred improvement of the present invention: the gates of the MOS transistor Q1 , the MOS transistor Q2 , the MOS transistor Q3 and the MOS transistor Q4 are all connected to the secondary side MCU.

[0013] As a preferred improvement of the present invention: the gates of the MOS transistor Q8, the MOS transistor Q9, the MOS transistor Q10 and the MOS transistor Q11 are all connected to the primary side MCU.

[0014] As a preferred improvement of the present invention: the gates of the MOS transistor Q13, the MOS transistor Q14, the MOS transistor Q15 and the MOS transistor Q16 are all connected to the primary side MCU.

[0015] As a preferred improvement of the present invention: the primary side MCU and the secondary side MCU are of TMS320F280023PMSR model.

[0016] The beneficial effects of the utility model are as follows:

[0017] The secondary-side MCU samples the input battery voltage information and transmits it to the primary-side. The primary-side MCU samples the load-end power information. The primary-side MCU performs LLC reverse boost if the judgment requirements are met based on the load-end power and the battery voltage transmitted by the secondary-side MCU. Otherwise, the LLC does not operate. The circuit is simple and can provide a wider DC input range. When the DC input voltage is low, the LLC reverse boost function is automatically activated to increase the bus voltage, alleviate output voltage clipping and enhance load capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0019] Figure 1 This is a schematic diagram of an LLC reverse boost control circuit according to the utility model;

[0020] Figure 2 This is an enlarged schematic diagram of the circuit of the utility model;

[0021] Figure 3 It is a schematic diagram of LLC reverse energy storage operation with the transformer's same-name end in positive phase;

[0022] Figure 4 It is the schematic diagram of LLC reverse boost operation with the transformer's same-name end in positive phase;

[0023] Figure 5 It is a schematic diagram of LLC reverse energy storage operation with the transformer's same-name end being the negative phase;

[0024] Figure 6 It is the LLC reverse boost operation schematic diagram with the transformer's same-name end as the negative phase;

[0025] Figure 7 This is a duty cycle diagram for LLC reverse boost Q9\10 drive. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] See also Figure 1-Figure 2 As shown, the utility model provides a reverse boost control circuit according to LLC, including AC input ports LIN and NIN, DC ports +DC and -DC, a primary MCU, a secondary MCU, a DC voltage sampling unit (battery end) and an AC voltage sampling unit (load end), wherein the primary MCU is connected to the AC input ports LIN and NIN through the AC voltage sampling unit, the secondary MCU is connected to the DC ports +DC and -DC through the DC voltage sampling unit, the primary MCU is connected to the secondary MCU, the LLC reverse boost control circuit also includes AC output ports LOUT and NOUT, the port LOUT is connected to the port LIN through a relay, the port NOUT is connected to the port NIN through a relay, and the primary MCU and the secondary MCU are TMS320F280023PMSR models.

[0032] The port LIN is connected to one end of the capacitor C3 and one end of the inductor L13, the other end of the inductor L13 is connected to the source of the MOS transistor Q13 and the drain of the MOS transistor Q14, the port NIN is connected to the other end of the capacitor C3, the source of the MOS transistor Q16 and the drain of the MOS transistor Q15, the drain of the MOS transistor Q13 is connected to the drain of the MOS transistor Q16, one end of the capacitor C1, the drain of the MOS transistor Q8 and the drain of the MOS transistor Q11, the source of the MOS transistor Q14 is connected to the source of the MOS transistor Q15, the The other end of the capacitor C1, the source of the MOS transistor Q9, the source of the MOS transistor Q10 and the port GND, the source of the MOS transistor Q8 is connected to the drain of the MOS transistor Q9 and the pin 3 of the transformer TX2, the source of the MOS transistor Q11 is connected to the drain of the MOS transistor Q10 and one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C76, the other end of the capacitor C76 is connected to the pin 4 of the transformer TX2, the pins 1 and 2 of the transformer TX2 share a coil, and the pins 3 and 4 share a coil. The gates of the MOS transistors Q8, Q9, Q10 and Q11 are all connected to the primary MCU, and the gates of the MOS transistors Q13, Q14, Q15 and Q16 are all connected to the primary MCU.

[0033] The LLC circuit generally does not work during inversion, and directly uses the body diode for rectification. The LLC circuit includes bus electrolytic capacitor C1, switch tube Q8\Q9\Q10\Q11, resonant inductor L1 and resonant capacitor C76A. Transformer TX2-B and bus electrolytic capacitor C1 are connected to the positive and negative sides of the bus. The drain of switch tube Q8\Q11 is connected to the positive side of the bus, the source of switch tube Q9\Q10 is connected to the negative side of the bus, the source of switch tube Q8\Q11 is connected to the drain of switch tube Q9\Q10 respectively, the source of switch tube Q11 is connected to pin 1 of resonant inductor L1, and resonant capacitor C74A is connected to pin 2 of resonant inductor L1 and pin 4 of the same name end of transformer TX2-B respectively. The driver of switch tube Q8\Q9\Q10\Q11 is connected to the primary MCU through the driver isolation chip, and the load end power is also sampled through the primary MCU. The communication judgment of the primary and secondary MCU is required to perform LLC reverse boost. The inverter circuit includes switch tubes Q13\Q14\Q15\Q16, output film capacitor C3, and boost inductor L13. The drain of switch tubes Q13\Q16 is connected to the positive terminal of the bus, the source of switch tubes Q14\Q15 is connected to the negative terminal of the bus, the source of switch tubes Q13\Q16 is connected to the drain of switch tubes Q14\Q50 respectively, the output film capacitor C3 is directly connected to the L\N line, the 2nd pin of boost inductor L13 is connected to the source of switch tube Q13, and the 1st pin is connected to the L line. The secondary MCU samples the input battery voltage information and transmits it to the primary side. The primary MCU samples the load power information. The primary MCU performs LLC reverse boosting based on the load power and the battery voltage transmitted by the secondary MCU. If the judgment requirements are met, LLC will not work otherwise.

[0034] The port +DC is connected to one end of the capacitor C2, the drain of the MOS tube Q4 and the drain of the MOS tube Q1, the source of the MOS tube Q1 is connected to the pin 1 of the transformer TX2 and the drain of the MOS tube Q2, the source of the MOS tube Q4 is connected to the pin 2 of the transformer TX2 and the drain of the MOS tube Q3, the port -DC is connected to the other end of the capacitor C2, the source of the MOS tube Q3 and the source of the MOS tube Q2, and the gates of the MOS tubes Q1, Q2, Q3 and Q4 are all connected to the secondary side MCU. LLC reverse push-pull circuit, including battery end input electrolytic capacitor C2, push-pull boost switch tubes Q1\Q2\Q3\Q4, and transformer TX2. The battery input electrolytic capacitor C2 is connected between the positive and negative terminals of the battery, the drain of the switch tube Q1\Q4 is connected to the positive terminal of the battery, the source of the switch tube Q2\Q3 is connected to the negative terminal of the battery, the source of the switch tube Q1\Q4 is connected to the drain of the switch tube Q2\Q3 respectively, the source of the switch tube Q1 is connected to the same-name terminal 1 of the transformer TX2-A, and the source of the switch tube Q4 is connected to the 2nd pin of the transformer TX2-A. The driver of the switch tube Q1\Q2\Q3\Q4 is connected to the MCU on the secondary side through the driver isolation chip, and the battery terminal voltage is also sampled by the secondary side MCU.

[0035] Embodiment 1

[0036] The control method of LLC reverse boost is to sample the battery terminal voltage. When the input voltage is lower than a certain limit and the load capacity is greater than a certain limit, the bus voltage is raised through LLC boost to improve the load capacity. The secondary MCU samples the battery terminal voltage and transmits it to the primary MCU after processing. The primary MCU samples the load terminal power and controls the LLC circuit switch tube to boost the voltage only when the requirements are met. The working process is as follows:

[0037] Case 1: When the battery voltage does not meet the requirements, the load load does not meet the requirements, or neither of them meets the requirements. LLC reverse push-pull boost completes the boost of the battery voltage and rectifies it to the bus voltage through the LLC switch tube. LLC reverse boost does not work. When the LLC reverse push-pull boost switch tube Q1\Q3 is turned on, the secondary current goes from the positive side of the battery to the switch tube Q1, then from the transformer pin 1 to the pin 2, and finally returns to the negative side of the battery through the switch tube Q3. The voltage at the same end is positive. The secondary of the transformer goes from the transformer pin 4 through the resonant capacitor, resonant inductor, and switch tube Q11 to the positive side of the bus, and finally returns to the transformer pin 3 through the negative side of the bus through the switch tube Q9. When the LLC reverse push-pull boost switch tube Q2\Q4 is turned on, the secondary current goes from the positive side of the battery to the switch tube Q4, then from the transformer pin 2 to the pin 1, and finally returns to the negative side of the battery through the switch tube Q2. The voltage at the same end is negative. The secondary of the transformer goes from pin 3 of the transformer through the switch tube Q8 to the positive pole of the bus, and finally returns to pin 4 of the transformer through the negative pole of the bus through the switch tube Q10, the resonant inductor, and the resonant capacitor.

[0038] Case 2: When the battery voltage and load power meet the limit requirements, the LLC reverse push-pull boost completes the boost of the battery voltage, and maintains the bus voltage through LLC reverse boost. The LLC reverse boost is that when the LLC reverse push-pull boost switch tube Q1\Q3 is turned on, the secondary current flows from the positive side of the battery to the switch tube Q1, then from pin 1 to pin 2 of the transformer, and finally returns to the negative side of the battery through the switch tube Q3, and the voltage at the same end is positive. And when the switch tube Q1\Q3 is turned on, the LLC switch tube Q10 is turned on (generally, the turn-on time of the switch tube Q10 is 1 / 5 of the turn-on time of the switch tube Q1\Q3, for example, the duty cycle of the switch tube Q1\Q3 is 45%, that is, the duty cycle of the switch tube Q10 is 9%, such as Figure 7 When the switch tube Q10 is turned on, the current will return directly from the 4th pin of the transformer through the resonant capacitor and the resonant inductor from the switch tube Q10 to the negative bus, and then return to the 3rd pin of the transformer from the body diode of the switch tube Q9, as shown. Figure 3 As shown; when the switch tube Q10 is turned off, the current will still flow from the 4th pin of the transformer through the resonant capacitor, the resonant inductor, the switch tube Q11 to the positive of the bus, and finally the negative of the bus returns to the 3rd pin of the transformer through the switch tube Q9, forming a closed loop, as shown Figure 4 shown.

[0039] When the LLC reverse push-pull boost switch is turned on, the secondary current flows from the positive electrode of the battery to the switch Q4, then from the transformer pin 2 to the pin 1, and finally returns to the negative electrode of the battery through the switch Q2. The voltage at the same end is negative. When the switch Q4\Q2 is turned on, the switch Q9 is turned on (generally, the turn-on time of the switch Q9 is 1 / 5 of the turn-on time of the switch Q4\Q2. For example, the duty cycle of the switch Q4\Q2 is 45%, and the duty cycle of the switch Q9 is 9%. Figure 7 When the switch tube Q9 is turned on, the current will directly return to the negative busbar from the switch tube Q9 through the 3rd pin of the transformer, and then return to the 4th pin of the transformer from the body diode of the switch tube Q10 through the resonant inductor and the resonant capacitor, as shown in Figure 5 When the switch tube Q9 is turned off, the current will still flow from the 3rd pin of the transformer through the switch tube Q8 to the positive side of the bus, and finally the negative side of the bus will return to the 4th pin of the transformer through the switch tube Q10, the resonant inductor and the resonant capacitor, forming a closed loop, as shown in Figure 6 As shown, the Boost circuit can be understood that when the switch tube Q9\Q10 is turned on, the resonant inductor is equivalent to the inductor for energy storage, and when the switch tube Q9\Q10 is turned off, the energy is released.

[0040] Although the implementation scheme of the utility model has been disclosed as above, it is not limited to the applications listed in the specification and the implementation scheme. It can be fully applied to various fields suitable for the utility model. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A reverse boost control circuit according to LLC, characterized in that: It includes AC input ports LIN and NIN, DC ports +DC and -DC, a primary MCU, a secondary MCU, a DC voltage sampling unit and an AC voltage sampling unit, wherein the primary MCU is connected to the AC input ports LIN and NIN through the AC voltage sampling unit, the secondary MCU is connected to the DC ports +DC and -DC through the DC voltage sampling unit, and the primary MCU is connected to the secondary MCU; The port LIN is connected to one end of the capacitor C3 and one end of the inductor L13, the other end of the inductor L13 is connected to the source of the MOS transistor Q13 and the drain of the MOS transistor Q14, the port NIN is connected to the other end of the capacitor C3, the source of the MOS transistor Q16 and the drain of the MOS transistor Q15, the drain of the MOS transistor Q13 is connected to the drain of the MOS transistor Q16, one end of the capacitor C1, the drain of the MOS transistor Q8 and the drain of the MOS transistor Q11, the source of the MOS transistor Q14 is connected to the drain of the MOS transistor Q15, and the drain of the MOS transistor Q13 is connected to the drain of the MOS transistor Q16, one end of the capacitor C1, the drain of the MOS transistor Q8 and the drain of the MOS transistor Q11. The source of the MOS transistor Q15, the other end of the capacitor C1, the source of the MOS transistor Q9, the source of the MOS transistor Q10 and the port GND are connected; the source of the MOS transistor Q8 is connected to the drain of the MOS transistor Q9 and the pin 3 of the transformer TX2; the source of the MOS transistor Q11 is connected to the drain of the MOS transistor Q10 and one end of the inductor L1; the other end of the inductor L1 is connected to one end of the capacitor C76; the other end of the capacitor C76 is connected to the pin 4 of the transformer TX2; The port +DC is connected to one end of the capacitor C2, the drain of the MOS transistor Q4 and the drain of the MOS transistor Q1, the source of the MOS transistor Q1 is connected to the pin 1 of the transformer TX2 and the drain of the MOS transistor Q2, the source of the MOS transistor Q4 is connected to the pin 2 of the transformer TX2 and the drain of the MOS transistor Q3, and the port -DC is connected to the other end of the capacitor C2, the source of the MOS transistor Q3 and the source of the MOS transistor Q2.

2. The LLC reverse boost control circuit according to claim 1, characterized in that: Pins 1 and 2 of the transformer TX2 share one coil, and pins 3 and 4 share one coil.

3. The LLC reverse boost control circuit according to claim 1, characterized in that: The LLC reverse boost control circuit further includes AC output ports LOUT and NOUT, wherein the port LOUT is connected to the port LIN via a relay, and the port NOUT is connected to the port NIN via a relay.

4. The LLC reverse boost control circuit according to claim 1, characterized in that: The gates of the MOS transistor Q1 , the MOS transistor Q2 , the MOS transistor Q3 , and the MOS transistor Q4 are all connected to the secondary-side MCU.

5. The LLC reverse boost control circuit according to claim 1, characterized in that: The gates of the MOS transistor Q8 , the MOS transistor Q9 , the MOS transistor Q10 , and the MOS transistor Q11 are all connected to the primary MCU.

6. The LLC reverse boost control circuit according to claim 1, characterized in that: The gates of the MOS transistor Q13, the MOS transistor Q14, the MOS transistor Q15 and the MOS transistor Q16 are all connected to the primary MCU.

7. The LLC reverse boost control circuit according to claim 1, characterized in that: The primary side MCU and the secondary side MCU are of TMS320F280023PMSR model.

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