LLC conversion circuit, control method of LLC conversion circuit and energy storage system

Abstract

The invention discloses an LLC conversion circuit, a control method of the LLC conversion circuit and an energy storage system. The LLC conversion circuit comprises a transformer, a first voltage side, a second voltage side and a control module. Wherein the control module responds to a first control instruction, sequentially conducts a first target switch tube on a second voltage side and a second target switch tube on a first voltage side, charges the energy storage power supply, and sequentially closes the second target switch tube and the first target switch tube when each switching period of charging is finished; wherein the control module responds to a second control instruction, sequentially conducts a second target switch tube on the first voltage side and a first target switch tube on the second voltage side, discharges the energy storage power supply, and sequentially closes the first target switch tube and the second target switch tube when each switch period of discharging is finished. By improving the switching logic of the switching tubes at the first voltage side and the second voltage side of the LLC conversion circuit, the noise and the switching loss when the switching tubes are turned on are reduced.

Description

Technical Field

[0001] The present application relates to the field of electronic circuits, and in particular to an LLC conversion circuit, a control method for an LLC conversion circuit, and an energy storage system. Background Art

[0002] Today's outdoor energy storage inverters generally use LLC (inductance leakage inductance capacitance) resonant converters in the hope of reducing losses through ZVS (Zero Voltage Switch) soft switching; reducing noise through zero voltage switching and as small a shutdown current as possible, so as to achieve better EMC (Electromagnetic Compatibility) effects. The switch tube of the traditional LLC resonant converter turns on and off simultaneously, that is, during synchronous rectification, the switch tubes on the primary and secondary sides of the transformer are synchronized and have the same duty cycle, without dead zones.

[0003] The above-mentioned method of switching the primary and secondary sides simultaneously will result in a relatively poor EMC effect, and will also cause the switching loss of the switch tube to increase, resulting in significant heating of the switch tube, affecting the working state of the circuit. Summary of the invention

[0004] To solve the above problems, the present application provides an LLC conversion circuit, a control method for the LLC conversion circuit and an energy storage system, which can ensure that the LLC conversion circuit switch tube can be turned on at zero voltage, thereby reducing noise and switching losses when the switch tube is turned on.

[0005] A technical solution adopted in the present application is: to provide an LLC conversion circuit, which includes: a transformer; a first voltage side, a first end of the first voltage side is coupled to an energy storage power supply; wherein the first voltage side includes at least two switch tubes; a second voltage side, a first end of the second voltage side is coupled to the second end of the first voltage side through a transformer, and the second end of the second voltage side is coupled to a bus; wherein the second voltage side includes at least one switch tube; a control module, coupled to the first voltage side and the second voltage side; wherein the control module, in response to a first control instruction, sequentially turns on a first target switch tube on the second voltage side and a second target switch tube on the first voltage side to charge the energy storage power supply, and at the end of each switching cycle of charging, sequentially turns off the second target switch tube and the first target switch tube; wherein the control module, in response to a second control instruction, sequentially turns on the second target switch tube on the first voltage side and the first target switch tube on the second voltage side to discharge the energy storage power supply, and at the end of each switching cycle of discharging, sequentially turns off the first target switch tube and the second target switch tube.

[0006] In one embodiment, the control module is configured to: in response to a first control instruction, control the first target switch tube to turn on; and after the first target switch tube is turned on, control the second target switch tube to turn on, and the LLC conversion circuit works in reverse to charge the energy storage power supply.

[0007] In one embodiment, the control module is further configured to: control the second target switch tube to be turned off at the end of each switching cycle of charging; and control the first target switch tube to be turned off after the second target switch tube is turned off.

[0008] In one embodiment, the control module is configured to: in response to the second control instruction, control the second target switch tube to turn on; and after the second target switch tube is turned on, control the first target switch tube to turn on, and the LLC conversion circuit works forward to discharge the energy storage power supply.

[0009] In one embodiment, the control module is further configured to: control the first target switch tube to be turned off at the end of each switching cycle of discharge; and control the second target switch tube to be turned off after the first target switch tube is turned off.

[0010] In one embodiment, the second voltage side includes: a first switch tube, a first end of the first switch tube is coupled to the positive end of the bus, a second end of the first switch tube is coupled to the resonant inductor connected in series with the first end of the primary winding of the transformer, and a control end of the first switch tube is coupled to the control module; a second switch tube, a first end of the second switch tube is coupled to the second end of the first switch tube, a second end of the second switch tube is coupled to the negative end of the bus, and a control end of the second switch tube is coupled to the control module.

[0011] In one embodiment, the first voltage side includes: a third switch tube, a first end of the third switch tube is coupled to the positive end of the energy storage power supply, a second end of the third switch tube is coupled to the second end of the secondary winding of the transformer, and a control end of the third switch tube is coupled to the control module; a fourth switch tube, a first end of the fourth switch tube is coupled to the second end of the third switch tube, a second end of the fourth switch tube is coupled to the negative end of the energy storage power supply, and a control end of the fourth switch tube is coupled to the control module; a fifth switch tube, a first end of the fifth switch tube is coupled to the positive end of the energy storage power supply, a second end of the fifth switch tube is coupled to the first end of the secondary winding of the transformer, and a control end of the fifth switch tube is coupled to the control module; a sixth switch tube, a first end of the sixth switch tube is coupled to the second end of the fifth switch tube, a second end of the sixth switch tube is coupled to the negative end of the energy storage power supply, and a control end of the sixth switch tube is coupled to the control module.

[0012] In one embodiment, the control module is configured to: in response to a first control instruction, sequentially turn on the first switch tube on the second voltage side and the fourth switch tube and the fifth switch tube on the first voltage side to charge the energy storage power supply, and at the end of each switching cycle of charging, sequentially turn off the fourth switch tube, the fifth switch tube and the first switch tube; in response to a second control instruction, sequentially turn on the fourth switch tube, the fifth switch tube on the first voltage side and the first switch tube on the second voltage side to discharge the energy storage power supply, and at the end of each switching cycle of discharging, sequentially turn off the first switch tube and the fourth switch tube and the fifth switch tube; wherein the third switch tube and the sixth switch tube on the first voltage side are turned on and turned off at the same time.

[0013] In one embodiment, the control module is configured to: in response to a first control instruction, sequentially turn on the second switch tube on the second voltage side and the third switch tube and the sixth switch tube on the first voltage side to charge the energy storage power supply, and at the end of each switching cycle of charging, sequentially turn off the third switch tube, the sixth switch tube and the second switch tube; in response to a second control instruction, sequentially turn on the third switch tube and the sixth switch tube on the first voltage side and the second switch tube on the second voltage side to discharge the energy storage power supply, and at the end of each switching cycle of discharging, sequentially turn off the second switch tube and the third switch tube and the sixth switch tube; wherein the third switch tube and the sixth switch tube on the first voltage side are turned on and off at the same time.

[0014] The present application also provides a control method for an LLC conversion circuit, the LLC conversion circuit comprising a transformer, a first voltage side, a second voltage side and a control module, the first end of the first voltage side is coupled to an energy storage power supply; wherein the first voltage side comprises at least two switching tubes; the first end of the second voltage side is coupled to the second end of the first voltage side through a transformer, and the second end of the second voltage side is coupled to a bus; wherein the second voltage side comprises at least one switching tube; the control module couples the first voltage side and the second voltage side, the method comprising: in response to a first control instruction, sequentially turning on a first target switching tube on the second voltage side and a second target switching tube on the first voltage side to charge the energy storage power supply, and at the end of each switching cycle of charging, sequentially turning off the second target switching tube and the first target switching tube; in response to a second control instruction, sequentially turning on the second target switching tube on the first voltage side and the first target switching tube on the second voltage side to discharge the energy storage power supply, and at the end of each switching cycle of discharging, sequentially turning off the first target switching tube and the second target switching tube.

[0015] The present application also provides an energy storage system, which includes the LLC conversion circuit as described above, or adopts the control method as described above.

[0016] The present application provides an LLC conversion circuit, a control method for the LLC conversion circuit, and an energy storage system. The LLC conversion circuit includes: a transformer; a first voltage side, a first end of the first voltage side is coupled to an energy storage power supply; wherein the first voltage side includes at least two switch tubes; a second voltage side, a first end of the second voltage side is coupled to a second end of the first voltage side through a transformer, and a second end of the second voltage side is coupled to a bus; wherein the second voltage side includes at least one switch tube; a control module, coupled to the first voltage side and the second voltage side; wherein the control module, in response to a first control instruction, sequentially turns on a first target switch tube on the second voltage side and a second target switch tube on the first voltage side to charge the energy storage power supply, and at the end of each switching cycle of charging, sequentially turns off the second target switch tube and the first target switch tube; wherein the control module, in response to a second control instruction, sequentially turns on the second target switch tube on the first voltage side and the first target switch tube on the second voltage side to discharge the energy storage power supply, and at the end of each switching cycle of discharging, sequentially turns off the first target switch tube and the second target switch tube. By improving the switching logic of the switch tubes on the first voltage side and the second voltage side of the LLC conversion circuit, it is ensured that the switch tube on the first voltage side can be turned on at zero voltage, thereby reducing the noise and switching loss when the switch tube is turned on, thereby effectively reducing the heat generated by the switch tube and improving the efficiency of the circuit; at the same time, it effectively avoids the oscillation caused by the characteristics of the switch tube, which has a significant effect on reducing EMC noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] in:

[0019] Figure 1 It is a structural schematic diagram of the first embodiment of the LLC conversion circuit provided by the present application;

[0020] Figure 2 It is a timing diagram of the target switch tube when the LLC conversion circuit provided by the present application is charged;

[0021] Figure 3 It is a timing diagram of the target switch tube when the LLC conversion circuit provided by the present application is discharged;

[0022] Figure 4 is a structural schematic diagram of a second embodiment of an LLC conversion circuit provided by the present application;

[0023] Figure 5 It is a timing diagram of the switch tube when the LLC conversion circuit provided by the present application is discharged;

[0024] Figure 6 It is a flow chart of an embodiment of an LLC conversion circuit control method provided by the present application;

[0025] Figure 7 It is a structural schematic diagram of an embodiment of an energy storage system provided in the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It will be appreciated that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some but not all structures related to the present application are shown in the drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present application.

[0027] The terms "first", "second", etc. in this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] See also Figure 1 , Figure 1 1 is a schematic diagram of the structure of the first embodiment of the LLC conversion circuit provided by the present application. The LLC conversion circuit 100 comprises: a transformer T; a first voltage side 10 , a second voltage side 20 and a control module 30 .

[0030] Among them, the first end of the first voltage side 10 is coupled to the energy storage power supply; the first voltage side 10 includes at least two switching tubes; the first end of the second voltage side 20 is coupled to the second end of the first voltage side 10 through the transformer T, and the second end of the second voltage side 20 is coupled to the bus; the second voltage side 20 includes at least one switching tube.

[0031] Among them, the control module 30 is coupled to the first voltage side 10 and the second voltage side 20; the control module 30 responds to the first control instruction, sequentially turns on the first target switch tube M1 of the second voltage side 20 and the second target switch tube M2 of the first voltage side 10 to charge the energy storage power supply, and at the end of each charging switching cycle, sequentially turns off the second target switch tube M2 and the first target switch tube M1; the control module 30 responds to the second control instruction, sequentially turns on the second target switch tube M2 of the first voltage side 10 and the first target switch tube M1 of the second voltage side 20 to discharge the energy storage power supply, and at the end of each discharging switching cycle, sequentially turns off the first target switch tube M1 and the second target switch tube M2.

[0032] Exemplarily, the LLC conversion circuit 100 is a highly efficient power conversion circuit that achieves a constant output voltage by controlling the switching frequency; in the LLC conversion circuit 100, the first voltage side 10 and the second voltage side 20 are coupled through a transformer T, and the function of the transformer T is to achieve voltage up and down conversion between the first voltage side 10 and the second voltage side 20 through electromagnetic induction. Due to the coupling effect of the transformer T, resonant oscillation can be generated between the primary coil and the secondary coil, thereby achieving efficient energy conversion between the two voltage sides.

[0033] In one embodiment, the first voltage side 10 is a low voltage side, and the second voltage side 20 is a high voltage side. When the energy storage power supply is charged, energy flows from the high voltage side to the low voltage side; when the energy storage power supply is discharged, energy flows from the low voltage side to the high voltage side.

[0034] In one embodiment, the switch tube on the first voltage side 10 and the switch tube on the second voltage side 20 may be MOS tubes, and the oscillation and output in the LLC conversion circuit 100 are controlled by controlling the on and off states of the switch tubes. An important feature of the LLC conversion circuit 100 is that it can realize soft switching, that is, when the switch tube is turned on and off, the voltage and current are almost zero, which greatly reduces the switching loss and improves the conversion efficiency of the circuit. By utilizing the body diode characteristics of the MOS tube, the switch tube on the first voltage side 10 can be turned on at zero voltage, reducing the oscillation of the switch tube drive signal and the noise caused by the Miller platform when the switch tube is turned on; at the same time, the smaller turn-off current when the body diode is turned off is conducive to reducing the switching loss of the switch tube.

[0035] Exemplarily, the time interval from the switch tube being turned off to being turned on again is a switching cycle, and the switch tubes on the two voltage sides of the LLC conversion circuit 100 will be turned on and off multiple times according to the preset switching cycle, so as to charge and discharge the energy storage power supply; when charging and discharging the energy storage power supply, the first target switch tube M1 and the second target switch tube M2 are turned on and off in sequence, so the switching cycles of the two are not the same, and the smaller switching cycle is the charging switching cycle or the discharging switching cycle of the LLC conversion circuit 100. For example, when charging the energy storage power supply, after the first target switch tube M1 and the second target switch tube M2 are turned on in sequence, at the end of each switching cycle of the second target switch tube M2, the second target switch tube M2 and the first target switch tube M1 are turned off in sequence; when discharging the energy storage power supply, after the second target switch tube M2 and the first target switch tube M1 are turned on in sequence, at the end of each switching cycle of the first target switch tube M1, the first target switch tube M1 and the second target switch tube M2 are turned off in sequence.

[0036] In one embodiment, the control module 30 may be an MCU (Microcontroller Unit). When the control module 30 responds to the first control instruction, when charging the energy storage power supply, the first target switch tube M1 of the second voltage side 20 is turned on before the second target switch tube M2 of the first voltage side 10, and energy flows from the second voltage side 20 to the first voltage side 10, and the energy of the busbar flows into the energy storage power supply; when charging is finished, the first target switch tube M1 is turned off after the second target switch tube M2; the turn-on time of the first target switch tube M1 is greater than the turn-on time of the second target switch tube M2. When the control module 30 responds to the second control instruction, when discharging the energy storage power supply, the first target switch tube M1 is turned on after the second target switch tube M2, and energy flows from the first voltage side 10 to the second voltage side 20, and the energy of the energy storage power supply flows into the busbar; when discharging is finished, the first target switch tube M1 is turned off before the second target switch tube M2; the turn-on time of the first target switch tube M1 is less than the turn-on time of the second target switch tube M2. In the above process, the switch tube on the first voltage side 10 and the switch tube on the second voltage side 20 are not turned on and off at the same time, and there is a dead zone. This switching logic is beneficial for the switch tube on the first voltage side 10 to be turned on at zero voltage, reducing the noise and switching loss when the switch tube is turned on, thereby effectively reducing the heat generated by the switch tube and improving the efficiency of the circuit.

[0037] In this embodiment, by improving the switching logic of the switch tubes on the first voltage side 10 and the second voltage side 20, the switch tubes on the two voltage sides are asynchronous and have different duty cycles, thereby making full use of the excitation current of the LLC resonant circuit and the MOS tube body diode characteristics, which is beneficial for the switch tube on the first voltage side 10 to be turned on at zero voltage, reducing the noise and switching loss when the switch tube is turned on, thereby effectively reducing the heat generated by the switch tube and improving the efficiency of the circuit.

[0038] See also Figure 2 , Figure 2 It is a timing diagram of the target switch tube when the LLC conversion circuit provided by the present application is charged.

[0039] In some embodiments, the control module 30 is configured to: in response to a first control instruction, control the first target switch tube M1 to turn on; and after the first target switch tube M1 is turned on, control the second target switch tube M2 to turn on, and the LLC conversion circuit 100 works in reverse to charge the energy storage power supply.

[0040] Exemplarily, when charging the energy storage, the energy of the second voltage side 20 flows into the first voltage side 10, and when the first target switch tube M1 starts to turn on, after a period of rising time, the level of the control end of the first target switch tube M1 becomes a high level, and the first target switch tube M1 is fully turned on. At this time, the second target switch tube M2 is controlled to start turning on, after a period of rising time, the level of the control end of the second target switch tube M2 becomes a high level, and the second target switch tube M2 is fully turned on, so that the loop between the first voltage side 10 and the second voltage side 20 is turned on, the loop between the bus and the energy storage power supply is turned on, and the LLC conversion circuit 100 works in reverse to transfer the energy of the bus to the energy storage power supply.

[0041] In some embodiments, the control module 30 is further configured to: control the second target switch tube M2 to turn off at the end of each switching cycle of charging; and control the first target switch tube M1 to turn off after the second target switch tube is turned off.

[0042] Exemplarily, after the second target switch tube M2 is turned on for a period of time, the second target switch tube M2 is controlled to start turning off, and after a period of falling time, the level of the control end of the second target switch tube M2 becomes a low level, and the second target switch tube M2 is completely turned off. At this time, the first target switch tube M1 is controlled to start turning off, and after a period of falling time, the level of the control end of the first target switch tube M1 becomes a low level, and the first target switch tube M1 is completely turned off, so that the loop between the bus and the energy storage power supply is closed, and charging ends.

[0043] See also Figure 3 , Figure 3 It is a timing diagram of the target switch tube when the LLC conversion circuit provided by the present application is discharged.

[0044] In some embodiments, the control module 30 is configured to: in response to the second control instruction, control the second target switch tube M2 to turn on; and after the second target switch tube M2 is turned on, control the first target switch tube M1 to turn on, and the LLC conversion circuit 100 works forward to discharge the energy storage power supply.

[0045] Exemplarily, when the second target switch tube M2 starts to turn on, after a period of rising time, the level of the control terminal of the second target switch tube M2 becomes a high level, and the second target switch tube M2 is fully turned on. At this time, the first target switch tube M1 is controlled to start turning on, after a period of rising time, the level of the control terminal of the second target switch tube M2 becomes a high level, and the first target switch tube M1 is fully turned on, so that the loop between the first voltage side 10 and the second voltage side 20 is turned on, the loop between the bus and the energy storage power supply is turned on, and the LLC conversion circuit 100 works in the forward direction to transfer the energy of the energy storage power supply to the bus.

[0046] In some embodiments, the control module 30 is further configured to: control the first target switch tube M1 to turn off at the end of each switching cycle of discharge; and control the second target switch tube M2 to turn off after the first target switch tube M1 is turned off.

[0047] Exemplarily, after the first target switch tube M1 is turned on for a period of time, the first target switch tube M1 is controlled to start turning off, and after a period of falling time, the level of the control end of the first target switch tube M1 becomes a low level, and the first target switch tube M1 is completely turned off. At this time, the second target switch tube M2 is controlled to start turning off, and after a period of falling time, the level of the control end of the second target switch tube M2 becomes a low level, and the second target switch tube M2 is completely turned off, so that the loop between the bus and the energy storage power supply is closed, and charging ends.

[0048] See also Figure 4 , Figure 4 1 is a schematic diagram of the structure of the second embodiment of the LLC conversion circuit provided by the present application. The LLC conversion circuit 100 comprises: a transformer T; a first voltage side 10 , a second voltage side 20 and a control module 30 .

[0049] Among them, the first end of the first voltage side 10 is coupled to the energy storage power supply; the first voltage side 10 includes at least two switching tubes; the first end of the second voltage side 20 is coupled to the second end of the first voltage side 10 through the transformer T, and the second end of the second voltage side 20 is coupled to the bus; the second voltage side 20 includes at least one switching tube.

[0050] Among them, the control module 30 is coupled to the first voltage side 10 and the second voltage side 20; the control module 30 responds to the first control instruction, sequentially turns on the first target switch tube M1 of the second voltage side 20 and the second target switch tube M2 of the first voltage side 10 to charge the energy storage power supply, and at the end of each charging switching cycle, sequentially turns off the second target switch tube M2 and the first target switch tube M1; the control module 30 responds to the second control instruction, sequentially turns on the second target switch tube M2 of the first voltage side 10 and the first target switch tube M1 of the second voltage side 20 to discharge the energy storage power supply, and at the end of each discharging switching cycle, sequentially turns off the first target switch tube M1 and the second target switch tube M2.

[0051] In some embodiments, the second voltage side 20 includes: a first switch tube Q1 and a second switch tube Q2. The first end of the first switch tube Q1 is coupled to the positive end Vbus+ of the bus, the second end of the first switch tube Q1 is coupled to the resonant inductor L connected in series with the first end of the primary winding of the transformer T, and the control end of the first switch tube Q1 is coupled to the control module 30; the first end of the second switch tube Q2 is coupled to the second end of the first switch tube Q1, the second end of the second switch tube Q2 is coupled to the negative end Vbus- of the bus, and the control end of the second switch tube Q2 is coupled to the control module 30.

[0052] In some embodiments, the second voltage side 20 further includes: a first capacitor C1, a second capacitor, and a third capacitor C3. The two ends of the first capacitor C1 are respectively connected to the positive end Vbus+ and the negative end Vbus- of the bus, the first end of the second capacitor C2 is connected to the first end of the first switch tube Q1; the first end of the third capacitor C3 is connected to the second end of the second capacitor C2, and the second end of the third capacitor C3 is connected to the second end of the second switch tube Q2.

[0053] In some embodiments, the first voltage side 10 includes: a third switch tube Q3, a fourth switch tube Q4, a fifth switch tube Q5, and a sixth switch tube Q6. A first end of the third switch tube Q3 is coupled to the positive end BAT+ of the energy storage power supply, a second end of the third switch tube Q3 is coupled to the second end of the secondary winding of the transformer T, and a control end of the third switch tube Q3 is coupled to the control module 30; a first end of the fourth switch tube Q4 is coupled to the second end of the third switch tube Q3, a second end of the fourth switch tube Q4 is coupled to the negative end BAT- of the energy storage power supply, and a control end of the fourth switch tube Q4 is coupled to the control module 30; a first end of the fifth switch tube Q5 is coupled to the positive end BAT+ of the energy storage power supply, a second end of the fifth switch tube Q5 is coupled to the first end of the secondary winding of the transformer T, and a control end of the fifth switch tube Q5 is coupled to the control module 30; a first end of the sixth switch tube Q6 is coupled to the second end of the fifth switch tube Q5, a second end of the sixth switch tube Q6 is coupled to the negative end BAT- of the energy storage power supply, and a control end of the sixth switch tube Q6 is coupled to the control module 30.

[0054] In some embodiments, the first voltage side 10 also includes: a fourth capacitor C4 and a fifth capacitor C5, the first end of the fourth capacitor C4 is connected to the positive terminal BAT+ of the energy storage power supply, and the second end of the fourth capacitor C4 is connected to the negative terminal BAT- of the energy storage power supply; the first end of the fifth capacitor C5 is connected to the positive terminal BAT+ of the energy storage power supply, and the second end of the fifth capacitor C5 is connected to the negative terminal BAT- of the energy storage power supply.

[0055] Exemplarily, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube, the fifth switch tube Q5 and the sixth switch tube Q6 can be MOS transistors, specifically NMOS transistors, whose working state is controlled by the gate (i.e., control terminal) voltage signal of the NMOS transistor. When the gate voltage signal is at a high level, the NMOS transistor is in an on state, and when the gate voltage signal is at a low level, the NMOS transistor is in an off state. In other embodiments, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube, the fifth switch tube Q5 and the sixth switch tube Q6 can also be semiconductor devices such as PMOS tubes and triodes, which are not listed here one by one.

[0056] Exemplarily, the inductor L is a resonant inductor, the first capacitor C1, the fourth capacitor C4 and the fifth capacitor C5 are used to filter out high-frequency noise and ripple in the signal and protect the circuit, the second capacitor C2, the third capacitor C3, the inductor L and the primary winding of the transformer T together constitute a resonant cavity, which determines the resonant frequency of the LLC conversion circuit 100. At the resonant frequency, the inductor and capacitor in the circuit interact with each other to form a stable energy exchange process, thereby achieving efficient energy transmission.

[0057] like Figure 5 As shown, Figure 5 It is a timing diagram of the switch tube when the LLC conversion circuit provided by the present application is discharged.

[0058] In some embodiments, the control module 30 is configured to: in response to a first control instruction, sequentially turn on the first switch tube Q1 of the second voltage side 20 and the fourth switch tube Q4 and the fifth switch tube Q5 of the first voltage side 10 to charge the energy storage power supply, and at the end of each switching cycle of charging, sequentially turn off the fourth switch tube Q4, the fifth switch tube Q5 and the first switch tube Q1; in response to a second control instruction, sequentially turn on the fourth switch tube Q4, the fifth switch tube Q5 of the first voltage side 10 and the first switch tube Q1 of the second voltage side 20 to discharge the energy storage power supply, and at the end of each switching cycle of discharging, sequentially turn off the first switch tube Q1, the fourth switch tube Q4 and the fifth switch tube Q5; wherein the fourth switch tube Q4 and the fifth switch tube Q5 of the first voltage side 10 are turned on and turned off at the same time.

[0059] In some embodiments, the control module 30 is configured to: in response to a first control instruction, sequentially turn on the second switch tube Q2 of the second voltage side 20 and the third switch tube Q3 and the sixth switch tube Q6 of the first voltage side 10 to charge the energy storage power supply, and sequentially turn off the third switch tube Q3, the sixth switch tube Q6 and the second switch tube Q2 at the end of each switching cycle of charging; in response to a second control instruction, sequentially turn on the third switch tube Q3, the sixth switch tube Q6 of the first voltage side 10 and the second switch tube Q2 of the second voltage side 20 to discharge the energy storage power supply, and sequentially turn off the second switch tube Q2 and the third switch tube Q3 and the sixth switch tube Q6 at the end of each switching cycle of discharging; wherein the third switch tube Q3 and the sixth switch tube Q6 of the first voltage side 10 are turned on and turned off at the same time.

[0060] Exemplarily, the first control instruction indicates charging the energy storage power supply. In response to the first control instruction, the first switch tube Q1 is turned on, and after the first switch tube Q1 is turned on, the fourth switch tube Q4 and the fifth switch tube Q5 are turned on at the same time. The current flows from the positive end Vbus+ of the bus through the first switch tube Q1, the primary winding of the transformer T and the third capacitor C3 back to the negative end Vbus- of the bus, thereby charging the third capacitor C3; at this time, the second capacitor is discharged, and the transformer T transfers energy from the high voltage side (i.e., the second voltage side 20) to the low voltage side (i.e., the first voltage side 10) until the voltage of the transformer T winding on the high voltage side can no longer maintain the energy transferred to the low voltage side, and at the same time, the fourth switch tube Q4 and the fifth switch tube Q5 are turned off before the first switch tube Q1 is turned off.

[0061] When the fourth switch tube Q4 and the fifth switch tube Q5 are turned off, the second switch tube Q2 is turned on. After the second switch tube Q2 is turned on, the third switch tube Q3 and the sixth switch tube Q6 are turned on at the same time. The current flows from the positive end Vbus+ of the bus through the second capacitor, the primary winding of the transformer T and the second switch tube Q2 back to the negative end of the bus, thereby charging the second capacitor. At this time, the third capacitor C3 is discharged, and the transformer T transfers energy from the high voltage side to the low voltage side until the voltage of the transformer T winding on the high voltage side cannot maintain the energy transferred to the low voltage side. At the same time, the third switch tube Q3 and the sixth switch tube Q6 are turned off, and then the second switch tube Q2 is turned off. The above-mentioned first switch on and the second switch on are repeated periodically, and energy is transferred from the high voltage side to the low voltage side.

[0062] Exemplarily, the second control instruction indicates discharging the energy storage power supply. In response to the second control instruction, the fourth switch tube Q4 and the fifth switch tube Q5 are turned on at the same time, and the first switch tube Q1 is turned on after the fourth switch tube Q4 is turned on. The current flows from the positive terminal BAT+ of the energy storage power supply through the fifth switch tube Q5, the secondary winding of the transformer T and the fourth switch tube Q4 back to the negative terminal BAT- of the energy storage power supply. The transformer T transfers energy from the low voltage side (i.e., the first voltage side 10) to the high voltage side (i.e., the second voltage side 20) until the voltage of the transformer T winding on the low voltage side cannot maintain the energy transferred to the high voltage side. After the first switch tube Q1 is turned off, the fourth switch tube Q4 and the fifth switch tube Q5 are turned off at the same time.

[0063] When the first switch tube Q1 is turned off, the third switch tube Q3 and the sixth switch tube Q6 are turned on at the same time. After the third switch tube Q3 is turned on, the second switch tube Q2 is turned on. The current flows from the positive terminal BAT+ of the energy storage power supply through the third switch tube Q3, the secondary winding of the transformer T and the sixth switch tube Q6 back to the negative terminal BAT- of the energy storage power supply. The transformer T transmits energy from the low voltage side to the high voltage side until the voltage of the transformer T winding on the low voltage side cannot maintain the energy transmitted to the high voltage side. After the second switch tube Q2 is turned off, the third switch tube Q3 and the sixth switch tube Q6 are turned off at the same time. The above-mentioned fourth switch tube Q4 and the fifth switch tube Q5 and the third switch tube Q3 and the sixth switch tube Q6 are turned on periodically and repeatedly, and the energy is transferred from the low voltage side to the high voltage side.

[0064] See also Figure 6 , Figure 6 It is a flow chart of an embodiment of an LLC conversion circuit control method provided by the present application.

[0065] The LLC conversion circuit includes a transformer, a first voltage side, a second voltage side and a control module, wherein the first end of the first voltage side is coupled to an energy storage power supply; wherein the first voltage side includes at least two switching tubes; the first end of the second voltage side is coupled to the second end of the first voltage side through a transformer T, and the second end of the second voltage side is coupled to a bus; wherein the second voltage side includes at least one switching tube; and the control module is coupled to the first voltage side and the second voltage side.

[0066] The control method includes:

[0067] Step S61: In response to the first control instruction, the first target switch tube on the second voltage side and the second target switch tube on the first voltage side are turned on in sequence to charge the energy storage power supply, and at the end of each charging switching cycle, the second target switch tube and the first target switch tube are turned off in sequence.

[0068] Step S62: In response to the second control instruction, the second target switch tube on the first voltage side and the first target switch tube on the second voltage side are turned on in sequence to discharge the energy storage power supply, and at the end of each switching cycle of the discharge, the first target switch tube and the second target switch tube are turned off in sequence.

[0069] See also Figure 7 , Figure 7 It is a structural diagram of an embodiment of an energy storage system provided in the present application. The energy storage system 1000 includes the LLC conversion circuit 100 as described above, or adopts the control method as described above.

[0070] The present application provides an LLC conversion circuit, a control method for the LLC conversion circuit, and an energy storage system. The LLC conversion circuit includes: a transformer; a first voltage side, a first end of the first voltage side is coupled to an energy storage power supply; wherein the first voltage side includes at least two switch tubes; a second voltage side, a first end of the second voltage side is coupled to a second end of the first voltage side through a transformer, and a second end of the second voltage side is coupled to a bus; wherein the second voltage side includes at least one switch tube; a control module, coupled to the first voltage side and the second voltage side; wherein the control module, in response to a first control instruction, sequentially turns on a first target switch tube on the second voltage side and a second target switch tube on the first voltage side to charge the energy storage power supply, and at the end of each switching cycle of charging, sequentially turns off the second target switch tube and the first target switch tube; wherein the control module, in response to a second control instruction, sequentially turns on the second target switch tube on the first voltage side and the first target switch tube on the second voltage side to discharge the energy storage power supply, and at the end of each switching cycle of discharging, sequentially turns off the first target switch tube and the second target switch tube. By improving the switching logic of the switch tubes on the first voltage side and the second voltage side of the LLC conversion circuit, it is ensured that the switch tube on the first voltage side can be turned on at zero voltage, thereby reducing the noise and switching loss when the switch tube is turned on, thereby effectively reducing the heat generated by the switch tube and improving the efficiency of the circuit; at the same time, it effectively avoids the oscillation caused by the characteristics of the switch tube, which has a significant effect on reducing EMC noise.

[0071] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device implementation described above is only illustrative, for example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0072] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0073] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0074] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An LLC conversion circuit, characterized in that: The LLC conversion circuit comprises: transformer; A first voltage side, wherein a first end of the first voltage side is coupled to an energy storage power supply; wherein the first voltage side includes at least two switch tubes; A second voltage side, wherein a first end of the second voltage side is coupled to a second end of the first voltage side through the transformer, and a second end of the second voltage side is coupled to a bus; wherein the second voltage side includes at least one switch tube; A control module, coupled to the first voltage side and the second voltage side; Wherein, in response to the first control instruction, the control module sequentially turns on the first target switch tube on the second voltage side and the second target switch tube on the first voltage side to charge the energy storage power supply, and sequentially turns off the second target switch tube and the first target switch tube at the end of each charging switching cycle; Among them, the control module responds to the second control instruction, sequentially turns on the second target switch tube on the first voltage side and the first target switch tube on the second voltage side to discharge the energy storage power supply, and at the end of each switching cycle of discharge, sequentially turns off the first target switch tube and the second target switch tube.

2. The LLC conversion circuit according to claim 1, characterized in that: The control module is configured to: In response to the first control instruction, controlling the first target switch tube to be turned on; After the first target switch tube is turned on, the second target switch tube is controlled to be turned on, and the LLC conversion circuit works in reverse to charge the energy storage power supply.

3. The LLC conversion circuit according to claim 2, characterized in that: The control module is further configured to: At the end of each charging switching cycle, controlling the second target switch tube to turn off; And after the second target switch tube is turned off, the first target switch tube is controlled to be turned off.

4. The LLC conversion circuit according to claim 1, characterized in that: The control module is configured to: In response to the second control instruction, controlling the second target switch tube to be turned on; After the second target switch tube is turned on, the first target switch tube is controlled to be turned on, and the LLC conversion circuit works in a forward direction to discharge the energy storage power supply.

5. The LLC conversion circuit according to claim 4, characterized in that: The control module is further configured to: At the end of each switching cycle of discharge, controlling the first target switch tube to turn off; After the first target switch tube is turned off, the second target switch tube is controlled to be turned off.

6. The LLC conversion circuit according to claim 1, characterized in that: The second voltage side comprises: a first switch tube, wherein a first end of the first switch tube is coupled to the positive end of the bus, a second end of the first switch tube is coupled to a resonant inductor connected in series with a first end of a primary winding of a transformer, and a control end of the first switch tube is coupled to the control module; A second switch tube, wherein a first end of the second switch tube is coupled to a second end of the first switch tube, a second end of the second switch tube is coupled to a negative end of the bus, and a control end of the second switch tube is coupled to the control module; The first voltage side comprises: a third switch tube, wherein a first end of the third switch tube is coupled to the positive end of the energy storage power supply, a second end of the third switch tube is coupled to the second end of the secondary winding of the transformer, and a control end of the third switch tube is coupled to the control module; a fourth switch tube, wherein a first end of the fourth switch tube is coupled to a second end of the third switch tube, a second end of the fourth switch tube is coupled to a negative end of the energy storage power supply, and a control end of the fourth switch tube is coupled to the control module; a fifth switch tube, wherein a first end of the fifth switch tube is coupled to the positive end of the energy storage power supply, a second end of the fifth switch tube is coupled to the first end of the secondary winding of the transformer, and a control end of the fifth switch tube is coupled to the control module; A sixth switch tube, wherein a first end of the sixth switch tube is coupled to a second end of the fifth switch tube, a second end of the sixth switch tube is coupled to a negative end of the energy storage power supply, and a control end of the sixth switch tube is coupled to the control module.

7. The LLC conversion circuit according to claim 6, characterized in that: The control module is configured to: In response to the first control instruction, the first switch tube on the second voltage side and the fourth switch tube and the fifth switch tube on the first voltage side are sequentially turned on to charge the energy storage power supply, and at the end of each switching cycle of charging, the fourth switch tube, the fifth switch tube and the first switch tube are sequentially turned off; In response to the second control instruction, the fourth switch tube and the fifth switch tube on the first voltage side and the first switch tube on the second voltage side are sequentially turned on to discharge the energy storage power supply, and at the end of each switching cycle of the discharge, the first switch tube, the fourth switch tube and the fifth switch tube are sequentially turned off; The fourth switch tube and the fifth switch tube on the first voltage side are turned on and turned off at the same time.

8. The LLC conversion circuit according to claim 6, characterized in that: The control module is configured to: In response to the first control instruction, the second switch tube on the second voltage side and the third switch tube and the sixth switch tube on the first voltage side are sequentially turned on to charge the energy storage power supply, and at the end of each switching cycle of charging, the third switch tube, the sixth switch tube and the second switch tube are sequentially turned off; In response to the second control instruction, the third switch tube and the sixth switch tube on the first voltage side and the second switch tube on the second voltage side are sequentially turned on to discharge the energy storage power supply, and at the end of each switching cycle of the discharge, the second switch tube, the third switch tube and the sixth switch tube are sequentially turned off; The third switch tube and the sixth switch tube on the first voltage side are turned on and off at the same time.

9. A control method for an LLC conversion circuit, characterized in that: The LLC conversion circuit includes a transformer, a first voltage side, a second voltage side and a control module, wherein the first end of the first voltage side is coupled to an energy storage power supply; wherein the first voltage side includes at least two switch tubes; the first end of the second voltage side is coupled to the second end of the first voltage side through the transformer, and the second end of the second voltage side is coupled to a bus; wherein the second voltage side includes at least one switch tube; the control module is coupled to the first voltage side and the second voltage side, and the method includes: In response to a first control instruction, the first target switch tube on the second voltage side and the second target switch tube on the first voltage side are sequentially turned on to charge the energy storage power supply, and at the end of each charging switching cycle, the second target switch tube and the first target switch tube are sequentially turned off; In response to a second control instruction, the second target switch tube on the first voltage side and the first target switch tube on the second voltage side are turned on in sequence to discharge the energy storage power supply, and at the end of each switching cycle of discharge, the first target switch tube and the second target switch tube are turned off in sequence.

10. An energy storage system, characterized in that: The energy storage system includes the LLC conversion circuit as described in any one of claims 1-8, or adopts the control method as described in claim 9.

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