A control method and device of a bidirectional DC-DC converter and a medium

Abstract

The application discloses a control method and device of a bidirectional DC-DC converter and a medium, relates to the technical field of power conversion, and comprises the following steps: first, calculating the output voltage loop PI value P1 and the current loop PI value P2 of two full-bridge LLC circuits in the primary side, taking the minimum value of the two, and standardizing the minimum value through Q12 to obtain a final PI output value P3; judging the load state of the circuit according to P3 and a preset criterion, and then adjusting the switching tube of the full-bridge LLC circuit in the primary side, so as to realize flexible switching of the full-bridge LLC topology and the half-bridge LLC topology; and simultaneously controlling the switching of the switching device to switch the series-parallel connection state of the primary and secondary side transformer windings, so as to realize high-low voltage switching of the output voltage. The scheme effectively solves the hard switching problem of the full-bridge LLC circuit under high-voltage no-load / light-load conditions, avoids damage caused by the misdirect through of the switching tube, reduces switching loss and voltage ripple, widens the output voltage range, adapts to the wide-voltage requirement of an electric vehicle battery, and improves the applicability, efficiency and reliability of the converter in scenarios such as charging piles.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power conversion, in particular to a control method and device of a bidirectional DC-DC converter and a medium. BACKGROUND

[0002] With the development of power electronics technology, bidirectional DC-DC converters are increasingly widely used in new energy electric vehicle charging piles and other scenarios to realize bidirectional energy transmission. Full-bridge LLC circuits have excellent soft switching characteristics, high efficiency and high power density, and have become the focus of research in the power supply industry.

[0003] However, in high-power and wide-voltage-range application scenarios, the full-bridge LLC circuit has obvious defects. When the output is high-voltage no-load or light-load, the primary-side switch tube has a small duty ratio and bears high voltage, and is prone to hard switching. Hard switching interference can cause the upper and lower switch tubes to be misdirected, thereby damaging the switch tubes and causing serious safety hazards. At the same time, the existing control method cannot meet the needs of the expanding voltage range of electric vehicle batteries, and cannot realize stable output in a wider voltage range. SUMMARY

[0004] The purpose of the present application is to provide a control method and device of a bidirectional DC-DC converter and a medium, which can reduce switching loss and voltage ripple and widen the output voltage range.

[0005] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0006] In a first aspect, the application provides a control method of a bidirectional DC-DC converter, the bidirectional DC-DC converter comprising a single bidirectional DC-DC conversion circuit or multiple parallel bidirectional DC-DC conversion circuits, when multiple bidirectional DC-DC conversion circuits are in parallel, the primary sides of each bidirectional DC-DC conversion circuit in forward and reverse directions adopt staggered phase control, and the secondary sides of each bidirectional DC-DC conversion circuit in forward and reverse directions adopt synchronous rectification control; the bidirectional DC-DC conversion circuit comprises a first full-bridge LLC circuit, a second full-bridge LLC circuit, a third full-bridge LLC circuit and a fourth full-bridge LLC circuit, each full-bridge LLC circuit comprises two bridge arms, and each bridge arm comprises two switching tubes; a first switching device K1 is arranged between the second bridge arm of the first full-bridge LLC circuit and the first bridge arm of the second full-bridge LLC circuit, and a second switching device K2 is arranged between the second bridge arm of the third full-bridge LLC circuit and the first bridge arm of the fourth full-bridge LLC circuit; when the bidirectional DC-DC conversion circuit works in forward direction, the first full-bridge LLC circuit and the second full-bridge LLC circuit serve as the primary side, and the third full-bridge LLC circuit and the fourth full-bridge LLC circuit serve as the secondary side; when the bidirectional DC-DC conversion circuit works in reverse direction, the fourth full-bridge LLC circuit and the third full-bridge LLC circuit serve as the primary side, and the second full-bridge LLC circuit and the first full-bridge LLC circuit serve as the secondary side; the control method of the bidirectional DC-DC converter comprises the following steps:

[0007] The output value P1 of an output voltage loop PI and the output value P2 of an output current loop PI of the two full-bridge LLC circuits in the primary side are calculated.

[0008] According to the output value P1 of the output voltage loop PI and the output value P2 of the output current loop PI, the final PI loop output value P3 is determined; the final PI loop output value P3 is the result of the minimum value of the output value P1 of the output voltage loop PI and the output value P2 of the output current loop PI after Q12 format normalization processing.

[0009] According to the final PI loop output value P3 and a preset output load judgment criterion, the output load state of the bidirectional DC-DC conversion circuit is determined; the output load state comprises no load, light load and heavy load.

[0010] According to the output load state, the output voltage and the output current of the bidirectional DC-DC conversion circuit are controlled by adjusting the switching tubes in the two full-bridge LLC circuits in the primary side.

[0011] The primary side and the secondary side transformer windings are switched in series and parallel by controlling the switching action of the first switching device K1 or the second switching device K2, so as to realize high and low voltage switching of the output voltage.

[0012] In a second aspect, the present application provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the control method of the two-stage bidirectional DC-DC converter.

[0013] In a third aspect, the present application provides a computer-readable storage medium having stored thereon a computer program, which, when executed by a processor, implements the steps of the control method of the bidirectional DC-DC converter according to any one of the preceding aspects.

[0014] According to the specific embodiments provided by the present application, the following technical effects are disclosed:

[0015] The present application provides a control method, device and medium of a bidirectional DC-DC converter, which comprises the following steps: first, through the cooperative collection of voltage and current feedback signals by dual-loop competition, the foundation is laid for subsequent accurate judgment of the load state and cooperative control, avoiding the problems of unstable voltage or current overload caused by single-loop control; then, the minimum value of the output value P1 of the output voltage loop PI and the output value P2 of the output current loop PI is confirmed, and it is normalized in the format of Q12, which unifies the dimensions of the output values of the voltage loop and the current loop, making the dual-loop competition logic more concise and efficient. After that, three load states are accurately distinguished by the preset output load judgment criterion, and the control strategy is selected accordingly, such as switching to half-bridge mode when the load is empty or light, which can significantly reduce the switching loss of the switching tube and the output voltage ripple, and effectively solve the problem of damage caused by the misdirected driving of the upper and lower switching tubes due to hard switching interference; when the load is heavy, switching to full-bridge mode can ensure the output power, and the efficiency and stability under different load states are considered, avoiding the hard switching phenomenon caused by blind control; in addition, by controlling the switching action of the switching device, the primary and secondary transformer windings are switched in series and parallel, which can greatly widen the output voltage range, adapt to the expanding voltage demand of electric vehicles, solve the defect that the existing control method cannot cover wide voltage output, and improve the applicability of the converter in new energy electric vehicle charging piles and other scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 A schematic diagram of a corresponding bidirectional DC-DC converter circuit in a control method of a bidirectional DC-DC converter provided by an embodiment of the present application.

[0018] Figure 2 A flow chart of a control method of a bidirectional DC-DC converter according to an embodiment of the present application.

[0019] Figure 3 A switching wave diagram of the primary two full-bridge LLC circuits of four switching periods in a control method of a bidirectional DC-DC converter according to an embodiment of the present application.

[0020] Figure 4 A curve diagram between the PFM gain and the switching frequency of a full-bridge LLC circuit drawn in a control method of a bidirectional DC-DC converter according to an embodiment of the present application. G fs

[0021] Figure 5 A circuit diagram when the first switching device K1 is open and the second switching device K2 is closed in a control method of a bidirectional DC-DC converter according to an embodiment of the present application.

[0022] Figure 6 A circuit diagram when the first switching device K1 and the second switching device K2 are both closed in a control method of a bidirectional DC-DC converter according to an embodiment of the present application.

[0023] Figure 7 A circuit diagram when the first switching device K1 is closed and the second switching device K2 is open in a control method of a bidirectional DC-DC converter according to an embodiment of the present application.

[0024] Figure 8 A structural diagram of a computer device according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0026] ​​Full-bridge LLC circuit can achieve soft switching in full load range near resonant switching frequency, and has excellent soft switching characteristics, high efficiency and high power density, and has become the focus of power supply industry. With the increasing demand for full-bridge LLC high-power switching power supply, the popularity of high-power application occasions, and the expansion of the demand for output voltage range, when the output is high-voltage idle or light load, the primary switch tube has small duty ratio and is easy to produce hard switching under high voltage. The phenomenon of damage to the switch tube caused by the interference of the upper and lower switch tubes driven by the hard switching is very serious, which will bring serious safety hazards and become a difficult problem that needs to be solved urgently in the industry.

[0027] In view of the continuous expansion of the voltage range of the battery of the electric vehicle, in the working condition of insulation detection or battery voltage fast charging, the full-bridge LLC circuit outputs in the idle or light load state. How to effectively control the hard switching, switching loss and output voltage ripple of the full-bridge LLC circuit when the idle or light load is hit, so as to realize the stable output of the idle and light load in a wider voltage range, is crucial to improve the performance and reliability of the converter.

[0028] Based on this, the application provides a control method of a bidirectional DC-DC converter. In the forward or reverse working state, through the combination control of the two full-bridge LLC circuits in the primary side, the switching control of the primary full-bridge and half-bridge LLC circuits and the series-parallel switching control of the primary transformer can be realized. Both the hard switching interference problem of the idle state and the output in a wider voltage range can be solved.

[0029] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below in combination with the drawings and specific embodiments.

[0030] The control method of the bidirectional DC-DC converter provided by the embodiment of the application includes a single or multiple parallel bidirectional DC-DC conversion circuits. In a exemplary embodiment, when multiple bidirectional DC-DC conversion circuits are connected in parallel, the primary sides of the forward and reverse bidirectional DC-DC conversion circuits are controlled by staggered phase control, and the secondary sides of the forward and reverse bidirectional DC-DC conversion circuits are controlled by synchronous rectification control. Figure 1As shown, the bidirectional DC-DC conversion circuit includes a first full-bridge LLC circuit, a second full-bridge LLC circuit, a third full-bridge LLC circuit and a fourth full-bridge LLC circuit, each of which includes two bridge arms, each of which includes two switching tubes; a first switching device K1 is arranged between the second bridge arm of the first full-bridge LLC circuit and the first bridge arm of the second full-bridge LLC circuit, and a second switching device K2 is arranged between the second bridge arm of the third full-bridge LLC circuit and the first bridge arm of the fourth full-bridge LLC circuit. The first switching device K1 and the second switching device K2 are one of full-controlled semiconductor devices, MOS tubes, IGBTs and relays.

[0031] Specifically, the first bridge arm of the first full-bridge LLC circuit includes a first switching tube Q1 and a second switching tube Q2, and the second bridge arm of the first full-bridge LLC circuit includes a third switching tube Q3 and a fourth switching tube Q4; the first bridge arm of the second full-bridge LLC circuit includes a fifth switching tube Q5 and a sixth switching tube Q6, and the second bridge arm of the second full-bridge LLC circuit includes a seventh switching tube Q7 and an eighth switching tube Q8; the first bridge arm of the third full-bridge LLC circuit includes a ninth switching tube Q9 and a tenth switching tube Q10, and the second bridge arm of the third full-bridge LLC circuit includes an eleventh switching tube Q11 and a twelfth switching tube Q12; the first bridge arm of the fourth full-bridge LLC circuit includes a thirteenth switching tube Q13 and a fourteenth switching tube Q14, and the second bridge arm of the fourth full-bridge LLC circuit includes a fifteenth switching tube Q15 and a sixteenth switching tube Q16.

[0032] Figure 1In the formula, V1 is the voltage difference of (input voltage positive Vin+ and input voltage negative Vin-), V2 is the voltage difference of (output voltage positive Vout+ and output voltage negative Vout-), C1 is the input electrolytic capacitor when working in the forward direction, and the output electrolytic capacitor when working in the reverse direction; C2 is the output electrolytic capacitor when working in the forward direction, and the input electrolytic capacitor when working in the reverse direction; Cr1 is the resonance capacitor of the first full-bridge LLC circuit, Cr2 is the resonance capacitor of the fourth full-bridge LLC circuit, Cr3 is the resonance capacitor of the second full-bridge LLC circuit, and Cr4 is the resonance capacitor of the third full-bridge LLC circuit; Lr1 is the resonance inductance of the first full-bridge LLC circuit, Lr2 is the resonance inductance of the fourth full-bridge LLC circuit, Lr3 is the resonance inductance of the second full-bridge LLC circuit, and Lr4 is the resonance inductance of the third full-bridge LLC circuit; T1-1 is the primary side of the transformer of the first full-bridge LLC circuit when working in the forward direction, and is the secondary side of the transformer of the first full-bridge LLC circuit when working in the reverse direction; T1-2 is the secondary side of the transformer of the fourth full-bridge LLC circuit when working in the forward direction, and is the primary side of the transformer of the fourth full-bridge LLC circuit when working in the reverse direction; T2-1 is the primary side of the transformer of the second full-bridge LLC circuit when working in the forward direction, and is the secondary side of the transformer of the second full-bridge LLC circuit when working in the reverse direction; and T2-2 is the secondary side of the transformer of the third full-bridge LLC circuit when working in the forward direction, and is the primary side of the transformer of the third full-bridge LLC circuit when working in the reverse direction.

[0033] When the bidirectional DC-DC conversion circuit works in the forward direction, the first full-bridge LLC circuit and the second full-bridge LLC circuit serve as the primary side, and the third full-bridge LLC circuit and the fourth full-bridge LLC circuit serve as the secondary side. Specifically, when working in the forward direction, the first full-bridge LLC circuit serves as the primary side first full-bridge LLC circuit, the second full-bridge LLC circuit serves as the primary side second full-bridge LLC circuit, the third full-bridge LLC circuit serves as the secondary side first full-bridge LLC circuit, and the fourth full-bridge LLC circuit serves as the secondary side second full-bridge LLC circuit. When the bidirectional DC-DC conversion circuit works in the reverse direction, the fourth full-bridge LLC circuit and the third full-bridge LLC circuit serve as the primary side, and the second full-bridge LLC circuit and the first full-bridge LLC circuit serve as the secondary side. Specifically, when working in the reverse direction, the fourth full-bridge LLC circuit serves as the primary side first full-bridge LLC circuit, the third full-bridge LLC circuit serves as the primary side second full-bridge LLC circuit, the second full-bridge LLC circuit serves as the secondary side first full-bridge LLC circuit, and the first full-bridge LLC circuit serves as the secondary side second full-bridge LLC circuit.

[0034] As shown in Figure 2 The control method of the bidirectional DC-DC converter includes the following steps:

[0035] A1. Calculate the output values ​​P1 and P2 of the output voltage loop PI controlled by the two full-bridge LLC circuits on the primary side. In this embodiment, the output value P1 of the output voltage loop PI controlled by the two full-bridge LLC circuits on the primary side is calculated according to the following formula:

[0036] .

[0037] in, Kp 1 is the voltage loop Kp value, Ki 1 is the voltage loop Ki value, e 1( t )for t The error value at time is the difference between the given voltage value and the actual voltage sample value.

[0038] Calculate the output value P2 of the output current loop PI controlled by the two full-bridge LLC circuits on the primary side according to the following formula:

[0039] .

[0040] in, Kp 2 is the output current loop Kp value, Ki 2 is the output current loop Ki value, e 2( t )for t The error value at time is the difference between the given current value and the actual current sample value.

[0041] A2. Determine the final PI loop output value P3 based on the output value P1 of the output voltage loop PI and the output value P2 of the output current loop PI. The final PI loop output value P3 is the result of normalizing the minimum value of the output value P1 of the output voltage loop PI and the output value P2 of the output current loop PI according to the Q12 format, with the maximum value limited to 4096 and the minimum value limited to 0.

[0042] A3, determining the output load state of the bidirectional DC-DC conversion circuit according to the final PI loop output value P3 and the preset output load judgment criterion; the output load state includes no load, light load and heavy load. In this embodiment, the preset output load judgment criterion is: judging whether the final PI loop output value P3 is between [0, 500], if yes, determining that the output load state of the bidirectional DC-DC conversion circuit is the no load state; if no, judging whether the final PI loop output value P3 is between (500, 1024], if yes, determining that the output load state of the bidirectional DC-DC conversion circuit is the light load state; if no, judging whether the final PI loop output value P3 is between (1024, 4096], if yes, determining that the output load state of the bidirectional DC-DC conversion circuit is the heavy load state.

[0043] A4, controlling the output voltage and the output current of the bidirectional DC-DC conversion circuit by adjusting the switching tubes of the primary side two full-bridge LLC circuits according to the output load state. In short, when in the no load or light load state, the primary side full-bridge LLC circuit is converted into a half-bridge LLC circuit for control; when the no load or light load state is converted into the heavy load state, the primary side half-bridge LLC circuit is gradually converted into the full-bridge LLC circuit for control; when the heavy load state is converted into the no load or light load state, the primary side full-bridge LLC circuit is gradually converted into the half-bridge LLC circuit for control; when the no load state is converted into the light load state, only the duty cycle of the primary side half-bridge LLC circuit needs to be adjusted. In this embodiment, the switching tube firing wave diagram of the primary side two full-bridge LLC circuits in four switching cycles is shown in FIG. 4. Specifically, step A4 includes the following steps: Figure 3

[0044] A41, when the output load state is the no load or light load state, the first bridge arm and the second bridge arm of the primary side two full-bridge LLC circuits are alternately used as the upper and lower complementary switching tubes of the half-bridge LLC circuit in the switching cycle of the switching tube, so as to realize the conversion of the full-bridge LLC circuit into the half-bridge LLC circuit for control, and the output voltage and the output current are controlled by adjusting the duty cycle of the upper and lower complementary switching tubes of the half-bridge LLC circuit.

[0045] In an exemplary embodiment, when the output load state is the no load or light load state, the full-bridge LLC circuit is converted into the half-bridge LLC circuit for control by controlling the primary side switching tubes of the primary side two full-bridge LLC topologies, the first bridge arm and the second bridge arm of the primary side two full-bridge LLC circuits are alternately used as the upper and lower switching tubes of the half-bridge LLC circuit for control, the switching frequency of the full-bridge LLC circuit switching tube is kept as the maximum value 300 KHZ, and the output voltage and the output current are controlled by adjusting the duty cycle of the switching tube. The duty cycle adjustment range of the switching tube is 0 ~ 50%, and the duty cycle adjustment method of the switching tube adopts the intermittent control of the intermittent. ​

[0046] Specifically, in the no-load or light-load state, in the first switching cycle of the switching tube, the upper tube Q1 and the lower tube Q2 of the first bridge arm of the first full-bridge LLC circuit respectively serve as the upper and lower complementary switching tubes of the half-bridge LLC, the upper tube Q3 of the second bridge arm keeps in the closed state, the lower tube Q4 of the second bridge arm keeps in the conducting state, and the switching tubes Q5, Q6, Q7 and Q8 of the second full-bridge LLC circuit keep in the closed state; in the second switching cycle of the switching tube, the upper tube Q3 and the lower tube Q4 of the second bridge arm of the first full-bridge LLC circuit respectively serve as the upper and lower complementary switching tubes of the half-bridge LLC, the upper tube Q1 of the first bridge arm keeps in the closed state, the lower tube Q2 of the first bridge arm keeps in the conducting state, and the switching tubes Q5, Q6, Q7 and Q8 of the second full-bridge LLC circuit keep in the closed state; in the third switching cycle of the switching tube, the upper tube Q5 and the lower tube Q6 of the first bridge arm of the second full-bridge LLC circuit respectively serve as the upper and lower complementary switching tubes of the half-bridge LLC, the upper tube Q7 of the second bridge arm keeps in the closed state, the lower tube Q8 of the second bridge arm keeps in the conducting state, and the switching tubes Q1, Q2, Q3 and Q4 of the first full-bridge LLC circuit keep in the closed state; in the fourth switching cycle of the switching tube, the upper tube Q7 and the lower tube Q8 of the second bridge arm of the second full-bridge LLC circuit respectively serve as the upper and lower complementary switching tubes of the half-bridge LLC, the upper tube Q5 of the first bridge arm keeps in the closed state, the lower tube Q6 of the first bridge arm keeps in the conducting state, and the switching tubes Q1, Q2, Q3 and Q4 of the first full-bridge LLC circuit keep in the closed state.

[0047] In the reverse working state of the no-load or light load, in the first switching cycle of the switching tube, the upper tube Q15 and the lower tube Q16 of the second bridge arm of the fourth full-bridge LLC circuit are respectively used as the upper and lower complementary switching tubes of the half-bridge LLC circuit, the upper tube Q13 of the first bridge arm keeps the closed state, the lower tube Q14 of the first bridge arm keeps the conducting state, and the switching tubes Q9, Q10, Q11 and Q12 of the third full-bridge LLC circuit keep the closed state; in the second switching cycle of the switching tube, the upper tube Q13 and the lower tube Q14 of the first bridge arm of the fourth full-bridge LLC circuit are respectively used as the upper and lower complementary switching tubes of the half-bridge LLC, the upper tube Q15 of the second bridge arm keeps the closed state, the lower tube Q16 of the second bridge arm keeps the conducting state, and the switching tubes Q9, Q10, Q11 and Q12 of the third full-bridge LLC circuit keep the closed state; in the third switching cycle of the switching tube, the upper tube Q11 and the lower tube Q12 of the second bridge arm of the third full-bridge LLC circuit are respectively used as the upper and lower complementary switching tubes of the half-bridge LLC, the upper tube Q9 of the first bridge arm keeps the closed state, the lower tube Q10 of the first bridge arm keeps the conducting state, and the switching tubes Q13, Q14, Q15 and Q16 of the fourth full-bridge LLC circuit keep the closed state; in the fourth switching cycle of the switching tube, the upper tube Q9 and the lower tube Q10 of the first bridge arm of the third full-bridge LLC circuit are respectively used as the upper and lower complementary switching tubes of the half-bridge LLC, the upper tube Q11 of the second bridge arm keeps the closed state, the lower tube Q12 of the second bridge arm keeps the conducting state, and the switching tubes Q13, Q14, Q15 and Q16 of the fourth full-bridge LLC circuit keep the closed state.

[0048] Specifically, in the output load state of the bidirectional DC-DC conversion circuit, when the load is no-load or light load, the first bridge arm and the second bridge arm of the two full-bridge LLC circuits in the primary side are alternately used as the upper and lower complementary switching tubes of the half-bridge LLC circuit in the switching cycle of the switching tube, and in each switching cycle, the switching loss of the 4 switching tubes of one full-bridge LLC circuit and the 2 switching tubes of one bridge arm can be reduced; in one complete switching cycle of the full-bridge LLC circuit, the voltage applied to the resonant cavity is a square wave switching between +Vin and -Vin, and the voltage amplitude is equal to the input voltage Vin; after the full-bridge LLC circuit is converted into the half-bridge LLC circuit, in one complete switching cycle of the half-bridge LLC circuit, the voltage applied to the resonant cavity is a square wave switching between +Vin / 2 and -Vin / 2, and the voltage amplitude is equal to half of the input voltage Vin, i.e. Vin / 2; the voltage amplitude applied to the resonant cavity by the full-bridge LLC circuit is Vin, and the voltage amplitude applied to the resonant cavity by the half-bridge LLC circuit is Vin / 2; the full-bridge LLC circuit is converted into the half-bridge LLC circuit for control, so that the voltage applied to the switching tube is halved, which can greatly reduce the loss of the switching tube and the output voltage ripple, and effectively solve the problem of switching tube damage caused by the upper and lower tube misdirected by the hard switching interference.

[0049] A42、in the output band load state is converted from no load or light load to heavy load, the half bridge LLC circuit is gradually transformed into full bridge LLC circuit by controlling the switch tube of the original two full bridge LLC circuits, the PFM gain is adjusted by adjusting the resonant cavity switching frequency of the full bridge LLC circuit, so as to control the output power.

[0050] For example, when the output band load state is converted from no load or light load to heavy load, and when the forward work is carried out, in the first switching period or the third switching period of the switch tube, the switching frequency of the first bridge arm switch tube of the first full bridge LLC circuit is maintained at the maximum value of 300 KHZ, and the duty ratio of the upper tube Q1 and the lower tube Q2 of the first bridge arm is adjusted to the maximum of 50%; The switching frequency of the upper tube Q3 and the lower tube Q4 of the second bridge arm is maintained at the maximum value of 300 KHZ, the upper tube Q3 starts to emit wave duty ratio to 50%, and the lower tube Q4 duty ratio is adjusted to duty ratio 50% from straight through; The switching frequency of the first bridge arm switch tube of the second full bridge LLC circuit is maintained at the maximum value of 300 KHZ, and the duty ratio of the upper tube Q5 and the lower tube Q6 of the first bridge arm is adjusted to the maximum of 50%; The switching frequency of the upper tube Q7 and the lower tube Q8 of the second bridge arm is maintained at the maximum value of 300 KHZ, the upper tube Q7 starts to emit wave duty ratio to 50%, and the lower tube Q8 duty ratio is adjusted to duty ratio 50% from straight through. In the second switching period or the fourth switching period of the switch tube, the switching frequency of the second bridge arm switch tube of the first full bridge LLC circuit is maintained at the maximum value of 300 KHZ, and the duty ratio of the upper tube Q3 and the lower tube Q4 of the second bridge arm is adjusted to the maximum of 50%; The switching frequency of the upper tube Q1 and the lower tube Q2 of the first bridge arm is maintained at the maximum value of 300 KHZ, the upper tube Q1 starts to emit wave duty ratio to 50%, and the lower tube Q2 duty ratio is adjusted to duty ratio 50% from straight through; The switching frequency of the second bridge arm switch tube of the second full bridge LLC circuit is maintained at the maximum value of 300 KHZ, and the duty ratio of the upper tube Q7 and the lower tube Q8 of the second bridge arm is adjusted to the maximum of 50%; The switching frequency of the upper tube Q5 and the lower tube Q6 of the first bridge arm is maintained at the maximum value of 300 KHZ, the upper tube Q5 starts to emit wave duty ratio to 50%, and the lower tube Q6 duty ratio is adjusted to duty ratio 50% from straight through.

[0051] When the output band load state is converted from no load or light load to heavy load, and in the reverse work, in the first switching cycle or the third switching cycle of the switching tube, the switching frequency of the second bridge arm switching tube of the fourth full bridge LLC circuit maintains the maximum value of 300 KHZ, and the duty cycle of the upper tube Q15 and the lower tube Q16 of the second bridge arm is adjusted to the maximum of 50%; the switching frequency of the upper tube Q13 and the lower tube Q14 of the first bridge arm maintains the maximum value of 300 KHZ, the upper tube Q13 starts to emit wave duty cycle to 50%, and the lower tube Q14 duty cycle is adjusted from through to duty cycle 50%; the switching frequency of the second bridge arm switching tube of the third full bridge LLC circuit maintains the maximum value of 300 KHZ, and the duty cycle of the upper tube Q11 and the lower tube Q12 of the second bridge arm is adjusted to the maximum of 50%; the switching frequency of the upper tube Q9 and the lower tube Q10 of the first bridge arm maintains the maximum value of 300 KHZ, the upper tube Q9 starts to emit wave duty cycle to 50%, and the lower tube Q10 duty cycle is adjusted from through to duty cycle 50%. In the second switching cycle or the fourth switching cycle of the switching tube, the switching frequency of the first bridge arm switching tube of the fourth full bridge LLC circuit maintains the maximum value of 300 KHZ, and the duty cycle of the upper tube Q13 and the lower tube Q14 of the first bridge arm is adjusted to the maximum of 50%; the switching frequency of the upper tube Q15 and the lower tube Q16 of the second bridge arm maintains the maximum value of 300 KHZ, the upper tube Q15 starts to emit wave duty cycle to 50%, and the lower tube Q16 duty cycle is adjusted from through to duty cycle 50%; the switching frequency of the first bridge arm switching tube of the third full bridge LLC circuit maintains the maximum value of 300 KHZ, and the duty cycle of the upper tube Q9 and the lower tube Q10 of the first bridge arm is adjusted to the maximum of 50%; the switching frequency of the upper tube Q11 and the lower tube Q12 of the second bridge arm maintains the maximum value of 300 KHZ, the upper tube Q11 starts to emit wave duty cycle to 50%, and the lower tube Q12 duty cycle is adjusted from through to duty cycle 50%.

[0052] In an exemplary embodiment, when the output band load state is converted from no load or light load to heavy load, in the first switching cycle, the second switching cycle, the third switching cycle or the fourth switching cycle of the switching tube, after the duty cycle of all switching tubes is adjusted to 50%, the half bridge LLC circuit is gradually transformed into the full bridge LLC circuit for control, the duty cycle of the fixed switching tube is adjusted to the maximum of 50%, and then the PFM gain is adjusted by adjusting the resonant cavity switching frequency of the full bridge LLC circuit, so as to control the output power; the switching frequency control range of the full bridge LLC circuit is 60 KHZ~300 KHZ, and the gain range is 0~1.2 times.

[0053] Specifically, the adjustment of the PFM gain of the full bridge LLC circuit is realized according to the following formula:

[0054] .

[0055] Wherein, G ( Q , K ,fs ) represents the PFM gain of the full-bridge LLC circuit. Q For quality factor, , Lr For the resonant inductance, Cr The capacitance of the resonant capacitor. Rac The equivalent resistance reflected from the output load resistance to the primary side. , N This represents the turns ratio of the primary and secondary sides of the transformer. R 0 represents the equivalent resistance of the output load. fs This refers to the switching frequency of the primary-side switching transistor in a full-bridge LLC circuit. fr This is the resonant frequency of the primary-side switching transistor in the full-bridge LLC circuit. K It is the ratio of the inductance of the primary excitation inductance to the inductance of the resonant inductance. , Lm For the magnetizing inductance, Lr The inductance is the resonant inductance; by adjusting the switching frequency of the full-bridge LLC circuit, the operating frequency of the full-bridge LLC circuit can be adjusted. fs Working at the resonant point fr This reduces circuit losses in the full-bridge LLC circuit and increases the circuit's transmission efficiency.

[0056] According to the above formula, for different... Q Values ​​and various different K PFM gain of the full-bridge LLC circuit. G and switching frequency fs The curves between them are as follows Figure 4 As shown, based on the principle of a full-bridge LLC circuit, the switching frequency range selected in the design is: fmin < fs < fmax ; fmax The operating frequency of a full-bridge LLC circuit is determined based on its losses and gains. By adjusting the switching frequency of the full-bridge LLC circuit, the operating frequency of the full-bridge LLC circuit can be adjusted. fs Working at the resonant point fr The PFM gain of the full-bridge LLC circuit is controlled within a certain range, thereby reducing circuit losses and increasing transmission efficiency. The PFM gain control range for the full-bridge LLC circuit is 0 to 1.2 times.

[0057] Specifically, the switching frequency of the switching transistors in a full-bridge LLC circuit fs The adjustment range is the minimum switching frequency of the primary-side switching transistor. fmin Up to maximum switching frequency fmax The relationship between the resonant frequency and the maximum / minimum switching frequency is as follows: fmin < fr < fmax ,in, fmin= 60 KHZ, fmax = 300 KHZ, fr = 90 KHZ.

[0058] A43, when the output load state is changed from heavy load to no load or light load, the full-bridge LLC circuit is gradually transformed into a half-bridge LLC circuit by controlling the switching tubes of the two full-bridge LLC circuits, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switching tubes of the half-bridge LLC circuit.

[0059] When the output load state is changed from heavy load to no load or light load, and when the forward operation is performed, in the first switching cycle or the third switching cycle of the switching tube, the switching frequency of the first bridge arm switching tube Q1 and Q2 of the first full-bridge LLC circuit is first adjusted to the maximum value of 300 KHZ, and the duty cycle of the upper tube Q1 and the lower tube Q2 is maintained at the maximum of 50%; the switching frequency of the second bridge arm switching tube Q3 and Q4 is adjusted to the maximum switching frequency of 300 KHZ, the upper tube Q3 starts to seal the PWM wave, and the duty cycle of the lower tube Q4 is adjusted from 50% to the through state; the switching frequency of the first bridge arm switching tube Q5 and Q6 of the second full-bridge LLC circuit is first adjusted to the maximum value of 300 KHZ, and the duty cycle of the upper tube Q5 and the lower tube Q6 is maintained at the maximum of 50%; the switching frequency of the second bridge arm switching tube Q7 and Q8 is adjusted to the maximum switching frequency of 300 KHZ, the upper tube Q7 starts to seal the PWM wave, and the duty cycle of the lower tube Q8 is adjusted from 50% to the through state; in the second switching cycle or the fourth switching cycle of the switching tube, the switching frequency of the second bridge arm switching tube Q3 and Q4 of the first full-bridge LLC circuit is first adjusted to the maximum value of 300 KHZ, and the duty cycle of the upper tube Q3 and the lower tube Q4 is maintained at the maximum of 50%; the switching frequency of the first bridge arm switching tube Q1 and Q2 is adjusted to the maximum switching frequency of 300 KHZ, the upper tube Q1 starts to seal the PWM wave, and the duty cycle of the lower tube Q2 is adjusted from 50% to the through state; the switching frequency of the second bridge arm switching tube Q7 and Q8 of the second full-bridge LLC circuit is first adjusted to the maximum value of 300 KHZ, and the duty cycle of the upper tube Q7 and the lower tube Q8 is maintained at the maximum of 50%; the switching frequency of the first bridge arm switching tube Q5 and Q6 is adjusted to the maximum switching frequency of 300 KHZ, the upper tube Q5 starts to seal the PWM wave, and the duty cycle of the lower tube Q6 is adjusted from 50% to the through state.

[0060] When the output band load state is converted from heavy load to no load or light load, and when the reverse work is performed, in the first switching cycle or the third switching cycle of the switching tube, the switching frequency of the second bridge arm switching tube Q15 and Q16 of the fourth full-bridge LLC circuit is first adjusted to the maximum value 300KHZ, and the duty cycle of the upper tube Q15 and the lower tube Q16 switching tube is maintained at the maximum 50%; the switching frequency of the first bridge arm switching tube Q13 and Q14 is adjusted to the maximum switching frequency 300KHZ, the upper tube Q13 starts to seal the PWM wave, and the duty cycle of the lower tube Q14 is adjusted from 50% to the straight-through state; the switching frequency of the second bridge arm switching tube Q11 and Q12 of the third full-bridge LLC circuit is first adjusted to the maximum value 300KHZ, and the duty cycle of the upper tube Q11 and the lower tube Q12 switching tube is maintained at the maximum 50%; the switching frequency of the first bridge arm switching tube Q9 and Q10 is adjusted to the maximum switching frequency 300KHZ, the upper tube Q9 starts to seal the PWM wave, and the duty cycle of the lower tube Q10 is adjusted from 50% to the straight-through state; in the second switching cycle or the fourth switching cycle of the switching tube, the switching frequency of the first bridge arm switching tube Q13 and Q14 of the fourth full-bridge LLC circuit is first adjusted to the maximum value 300KHZ, and the duty cycle of the upper tube Q13 and the lower tube Q14 switching tube is maintained at the maximum 50%; the switching frequency of the second bridge arm switching tube Q15 and Q16 is adjusted to the maximum switching frequency 300KHZ, the upper tube Q15 starts to seal the PWM wave, and the duty cycle of the lower tube Q16 is adjusted from 50% to the straight-through state; the switching frequency of the first bridge arm switching tube Q9 and Q10 of the third full-bridge LLC circuit is first adjusted to the maximum value 300KHZ, and the duty cycle of the upper tube Q9 and the lower tube Q10 switching tube is maintained at the maximum 50%; the switching frequency of the second bridge arm switching tube Q11 and Q12 is adjusted to the maximum switching frequency 300KHZ, the upper tube Q11 starts to seal the PWM wave, and the duty cycle of the lower tube Q12 is adjusted from 50% to the straight-through state.

[0061] In an exemplary embodiment, when the output band load state is converted from heavy load to no load or light load, in the first switching cycle, the second switching cycle, the third switching cycle or the fourth switching cycle of the switching tube, when the frequency of all switching tubes is adjusted to the maximum value 300KHZ, the duty cycle of the fixed switching tube is 50%, and then the output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switching tubes of the half-bridge LLC circuit; the control range of the switching tube duty cycle of the full-bridge LLC circuit is 0~50%.

[0062] A44, when the output band load state is converted from no load to light load or from light load to no load, the switching cycle of the switching tube is alternated, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switching tubes of the half-bridge LLC circuit.

[0063] When the output band load state is changed from no load to light load or from light load to no load, and in the forward working state, in the first switching cycle of the switching tube, the switching frequency of the first bridge arm switching tube Q1 and Q2 of the first full-bridge LLC circuit maintains the maximum value of 300 KHZ, the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q1 and Q2, the upper tube Q3 of the second bridge arm switching tube is always sealed PWM wave, the duty cycle of the lower tube Q4 maintains the straight-through state, and the switching tubes Q5, Q6, Q7 and Q8 of the second full-bridge LLC circuit maintain the closed state; in the second switching cycle of the switching tube, the switching frequency of the second bridge arm switching tube Q3 and Q4 of the first full-bridge LLC circuit maintains the maximum value of 300 KHZ, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q3 and Q4; the upper tube Q1 of the first bridge arm switching tube is always sealed PWM wave, the lower tube Q2 maintains the straight-through state, and the switching tubes Q5, Q6, Q7 and Q8 of the second full-bridge LLC circuit maintain the closed state. In the third switching cycle of the switching tube, the switching frequency of the first bridge arm switching tube Q5 and Q6 of the second full-bridge LLC circuit maintains the maximum value of 300 KHZ, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q5 and Q6; the upper tube of the second bridge arm switching tube Q7 is always sealed PWM wave, the duty cycle of the lower tube Q8 maintains the straight-through state, and the switching tubes Q1, Q2, Q3 and Q4 of the first full-bridge LLC circuit maintain the closed state; in the fourth switching cycle of the switching tube, the switching frequency of the second bridge arm switching tube Q7 and Q8 of the second full-bridge LLC circuit maintains the maximum value of 300 KHZ, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q7 and Q8; the upper tube Q5 of the first bridge arm switching tube is always sealed PWM wave, the lower tube Q6 maintains the straight-through state, and the switching tubes Q1, Q2, Q3 and Q4 of the first full-bridge LLC circuit maintain the closed state.

[0064] When the output band load state is converted from no load to light load or from light load to no load, and when the reverse work is performed, in the first switching cycle of the switching tube, the switching frequency of the second bridge arm switching tube Q15 and Q16 of the fourth full-bridge LLC circuit maintains the maximum value of 300 KHZ, the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q15 and Q16, the upper tube of the first bridge arm switching tube Q13 is always sealed PWM wave, the duty cycle of the lower tube Q14 maintains the straight-through state, and the switching tubes Q9, Q10, Q11 and Q12 of the third full-bridge LLC circuit maintain the closed state; in the second switching cycle of the switching tube, the switching frequency of the first bridge arm switching tube Q13 and Q14 of the fourth full-bridge LLC circuit maintains the maximum value of 300 KHZ, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q13 and Q14; the upper tube Q15 of the second bridge arm switching tube is always sealed PWM wave, the lower tube Q16 maintains the straight-through state, and the switching tubes Q9, Q10, Q11 and Q12 of the third full-bridge LLC circuit maintain the closed state. In the third switching cycle of the switching tube, the switching frequency of the second bridge arm switching tube Q11 and Q12 of the third full-bridge LLC circuit maintains the maximum value of 300 KHZ, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q11 and Q12; the upper tube of the first bridge arm switching tube Q9 is always sealed PWM wave, the duty cycle of the lower tube Q10 maintains the straight-through state, and the switching tubes Q13, Q14, Q15 and Q16 of the fourth full-bridge LLC circuit maintain the closed state; in the fourth switching cycle of the switching tube, the switching frequency of the first bridge arm switching tube Q9 and Q10 of the third full-bridge LLC circuit maintains the maximum value of 300 KHZ, and the output voltage and current are controlled by adjusting the duty cycle of the upper and lower switching tubes Q9 and Q10; the upper tube Q11 of the second bridge arm switching tube is always sealed PWM wave, the lower tube Q12 maintains the straight-through state, and the switching tubes Q13, Q14, Q15 and Q16 of the fourth full-bridge LLC circuit maintain the closed state.

[0065] In an exemplary embodiment, when the output band load state is converted from no load to light load or from light load to no load, in the first switching cycle, the second switching cycle, the third switching cycle or the fourth switching cycle of the switching tube, when the frequency of the upper and lower switching tubes of the half-bridge LLC circuit maintains the maximum value of 300 KHZ, the output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switching tubes of the half-bridge LLC circuit; the control range of the switching tube duty cycle of the full-bridge LLC circuit is 0-50%.

[0066] A5, by controlling the switching action of the first switching device K1 or the second switching device K2, the primary and secondary transformer windings are switched in series and parallel, the high and low voltage of the output voltage is switched, and a wider voltage range output is realized. In the embodiment, step A5 specifically includes the following several cases:

[0067] During forward operation, when both the first switching device K1 and the second switching device K2 are open, as follows: Figure 1 As shown, the primary transformer windings T1-1 and T2-1, and the secondary transformer windings T1-2 and T2-2 are all connected in parallel. All switches are operating. The input voltage V1 ranges from 0 to 500V, and the output voltage V2 ranges from 0 to 500V. When the first switching device K1 is open and the second switching device K2 is closed, as follows... Figure 5 As shown, the primary transformer windings T1-1 and T2-1 are connected in parallel, while the secondary transformer windings T1-2 and T2-2 are connected in series. The ninth, tenth, fifteenth, and sixteenth switches on the secondary side, Q9, Q10, Q15, and Q16, are operational, while the eleventh, twelfth, Q12, thirteenth, and fourteenth switches, Q14, remain closed. At this time, the eleventh, twelfth, thirteenth, and fourteenth switches, acting as secondary switches, are in an open-circuit state. The input voltage V1 ranges from 0 to 500V, and the output voltage V2 ranges from 0 to 1000V. When both the first switch K1 and the second switch K2 are closed, as follows... Figure 6 As shown, the primary transformer windings T1-1 and T2-1, and the secondary transformer windings T1-2 and T2-2 are all connected in series. The primary side switches Q1, Q2, Q7, and Q8 are operational, while the secondary side switches Q3, Q4, Q5, and Q6 remain closed. Therefore, the primary side switches Q3, Q4, Q5, and Q6 are in an open-circuit state. The secondary side switch Q1-1 is connected in series with the primary side switches Q7, Q8, Q9, Q1-1, Q1-2, Q1-2, and Q1-2. 9. The tenth switch Q10, the fifteenth switch Q15, and the sixteenth switch Q16 are working, while the eleventh switch Q11, the twelfth switch Q12, the thirteenth switch Q13, and the fourteenth switch Q14 remain in the off state. At this time, the eleventh switch Q11, the twelfth switch Q12, the thirteenth switch Q13, and the fourteenth switch Q14, which are secondary switches, are in the open circuit state. The range of input voltage V1 is 500-1000V, and the range of output voltage V2 is 500-1000V.

[0068] When operating in reverse, if both the second switching device K2 and the first switching device K1 are open, as follows: Figure 1 As shown, the primary transformer windings T1-2 and T2-2, and the secondary transformer windings T1-1 and T2-1 are all connected in parallel. All switches are operating. The input voltage V2 ranges from 0 to 500V, and the output voltage V1 ranges from 0 to 500V. When the second switching device K2 is open and the first switching device K1 is closed, as follows... Figure 7As shown, the primary transformer windings T1-2 and T2-2 are in parallel state, the secondary transformer windings T1-1 and T2-1 are in series state, the first switch tube Q1, the second switch tube Q2, the seventh switch tube Q7 and the eighth switch tube Q8 of the secondary side work, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5 and the sixth switch tube Q6 keep closed state, at this time, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5 and the sixth switch tube Q6 as the secondary switch tube are in open circuit state, the input voltage V2 is in the range of 0-500V, and the output voltage V1 is in the range of 0-1000V. Figure 6 As shown, the primary transformer windings T1-2 and T2-2, the secondary transformer windings T1-1 and T2-1 are in series state, the first switch tube Q1, the second switch tube Q2, the seventh switch tube Q7 and the eighth switch tube Q8 of the secondary side work, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5 and the sixth switch tube Q6 keep closed state, at this time, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5 and the sixth switch tube Q6 as the secondary switch tube are in open circuit state; the ninth switch tube Q9, the tenth switch tube Q10, the fifteenth switch tube Q15 and the sixteenth switch tube Q16 of the primary side work, the eleventh switch tube Q11, the twelfth switch tube Q12, the thirteenth switch tube Q13 and the fourteenth switch tube Q14 keep closed state, at this time, the eleventh switch tube Q11, the twelfth switch tube Q12, the thirteenth switch tube Q13 and the fourteenth switch tube Q14 as the primary switch tube are in open circuit state, the input voltage V2 is in the range of 500-1000V, and the output voltage V1 is in the range of 500-1000V.

[0069] In an exemplary embodiment, a computer device which can be a server or a terminal is provided, and an internal structure diagram of the computer device can be as shown in Figure 8The computer device shown in the figure includes a processor, a memory, an Input / Output (I / O) interface, and a communication interface. The processor, the memory, and the I / O interface are connected through a system bus, and the communication interface is connected to the system bus through the I / O interface. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The I / O interface of the computer device is configured to exchange information between the processor and external devices. The communication interface of the computer device is configured to communicate with external terminals through network connection. The computer program, when executed by the processor, can implement the control method of the bidirectional DC-DC converter provided in the foregoing embodiments.

[0070] Those skilled in the art can understand that, Figure 8 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. Specifically, the computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0071] In an exemplary embodiment, a computer device is also provided, including a memory and a processor, the memory storing a computer program, and the processor implementing the steps in the above method embodiments when executing the computer program.

[0072] In an exemplary embodiment, a computer readable storage medium is provided, storing a computer program, and the computer program implements the steps in the above method embodiments when executed by a processor.

[0073] In an exemplary embodiment, a computer program product is provided, including a computer program, and the computer program implements the steps in the above method embodiments when executed by a processor.

[0074] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or authorized by all parties, and the collection, use, and processing of related data need to comply with relevant regulations.

[0075] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to a memory, a database or other medium used in the embodiments provided in the present application can include at least one of a non-volatile and a volatile memory. The non-volatile memory can include a read-only memory (ROM), a magnetic tape, a floppy disk, a flash memory, an optical storage, a high-density embedded non-volatile memory, a resistive random access memory (ReRAM), a magnetoresistive random access memory (MRAM), a ferroelectric random access memory (FRAM), a phase change memory (PCM), a graphene memory, etc. The volatile memory can include a random access memory (RAM) or an external cache memory, etc. As an illustration but not limitation, the RAM can be in various forms, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), etc.

[0076] The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a blockchain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0077] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0078] The principles and implementation modes of the present application are described by applying specific examples in the present application. The above-mentioned embodiments are only used to help understand the method and its core idea of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range can be changed. In conclusion, the content of the present application should not be understood as a limitation.

Claims

1. A control method for a bidirectional DC-DC converter, wherein the bidirectional DC-DC converter includes one or more parallel bidirectional DC-DC converter circuits, wherein when multiple bidirectional DC-DC converter circuits are connected in parallel, the primary sides of each bidirectional DC-DC converter circuit in both forward and reverse directions are subjected to interleaved phase control, and the secondary sides of each bidirectional DC-DC converter circuit in both forward and reverse directions are subjected to synchronous rectification control; the bidirectional DC-DC converter circuit includes a first full-bridge LLC circuit, a second full-bridge LLC circuit, a third full-bridge LLC circuit, and a fourth full-bridge LLC circuit, each full-bridge LLC circuit including two bridge arms, each bridge arm including two switching transistors; the second bridge arm of the first full-bridge LLC circuit is connected to... A first switching device K1 is provided between the first bridge arms of the second full-bridge LLC circuit, and a second switching device K2 is provided between the second bridge arm of the third full-bridge LLC circuit and the first bridge arm of the fourth full-bridge LLC circuit; when the bidirectional DC-DC converter circuit operates in the forward direction, the first full-bridge LLC circuit and the second full-bridge LLC circuit serve as the primary side, and the third full-bridge LLC circuit and the fourth full-bridge LLC circuit serve as the secondary side; when the bidirectional DC-DC converter circuit operates in the reverse direction, the fourth full-bridge LLC circuit and the third full-bridge LLC circuit serve as the primary side, and the second full-bridge LLC circuit and the first full-bridge LLC circuit serve as the secondary side; characterized in that, The control method for the bidirectional DC-DC converter includes: Calculate the output values ​​P1 of the output voltage loop PI and P2 of the output current loop PI controlled by the two full-bridge LLC circuits on the primary side; Based on the output value P1 of the output voltage loop PI and the output value P2 of the output current loop PI, the final PI loop output value P3 is determined; the final PI loop output value P3 is the result of normalizing the minimum value of the output voltage loop PI P1 and the output current loop PI P2 according to the Q12 format. The output load state of the bidirectional DC-DC converter circuit is determined based on the final PI loop output value P3 and the preset output load judgment criteria; the output load state includes no load, light load and heavy load. Based on the output load state, the output voltage and output current of the bidirectional DC-DC converter circuit are controlled by adjusting the switching transistors in the two full-bridge LLC circuits on the primary side. By controlling the switching action of the first switching device K1 or the second switching device K2, the primary and secondary transformer windings are switched in series and in parallel to achieve high and low voltage switching of the output voltage.

2. The control method for the bidirectional DC-DC converter according to claim 1, characterized in that, The preset output load judgment criterion is as follows: determine whether the final PI loop output value P3 is between [0, 500]. If yes, the output load state of the bidirectional DC-DC converter circuit is determined to be unloaded; if no, determine whether the final PI loop output value P3 is between (500, 1024). If yes, the output load state of the bidirectional DC-DC converter circuit is determined to be lightly loaded; if no, determine whether the final PI loop output value P3 is between (1024, 4096). If yes, the output load state of the bidirectional DC-DC converter circuit is determined to be heavily loaded.

3. The control method for the bidirectional DC-DC converter according to claim 1, characterized in that, Calculate the output value P1 of the output voltage loop PI controlled by the two full-bridge LLC circuits on the primary side according to the following formula: ； in, Kp 1 is the voltage loop Kp value, Ki 1 is the voltage loop Ki value, e 1( t )for t The error value at any given time is the difference between the given voltage value and the actual voltage sample value. Calculate the output value P2 of the output current loop PI controlled by the two full-bridge LLC circuits on the primary side according to the following formula: ； in, Kp 2 is the output current loop Kp value, Ki 2 is the output current loop Ki value, e 2( t )for t The error value at time is the difference between the given current value and the actual current sample value.

4. The control method for the bidirectional DC-DC converter according to claim 1, characterized in that, Based on the output load state, the output voltage and output current of the bidirectional DC-DC converter circuit are controlled by adjusting the switching transistors in the two full-bridge LLC circuits on the primary side, specifically including: When the output load is no load or light load, the first and second bridge arms of the two full-bridge LLC circuits on the primary side are used as the upper and lower complementary switches of the half-bridge LLC circuit by alternating the switching cycle of the switching transistors. This transforms the full-bridge LLC circuit into a half-bridge LLC circuit for control. The output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switches of the half-bridge LLC circuit. When the output load state changes from no load or light load to heavy load, the half-bridge LLC circuit is gradually transformed into a full-bridge LLC circuit by controlling the switching transistors of the two full-bridge LLC circuits on the primary side. The PFM gain is adjusted by adjusting the resonant cavity switching frequency of the full-bridge LLC circuit, thereby controlling the output power. When the output load state changes from heavy load to no load or light load, the full-bridge LLC circuit is gradually transformed into a half-bridge LLC circuit by controlling the switching transistors of the two full-bridge LLC circuits on the primary side. The output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switching transistors of the half-bridge LLC circuit. When the output load changes from no load to light load or from light load to no load, the output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switching transistors of the half-bridge LLC circuit through the alternating switching cycles of the switching transistors.

5. The control method for a bidirectional DC-DC converter according to claim 4, wherein the first bridge arm of the first full-bridge LLC circuit includes a first switch Q1 and a second switch Q2, and the second bridge arm of the first full-bridge LLC circuit includes a third switch Q3 and a fourth switch Q4; the first bridge arm of the second full-bridge LLC circuit includes a fifth switch Q5 and a sixth switch Q6, and the second bridge arm of the second full-bridge LLC circuit includes a seventh switch Q7 and an eighth switch Q8; the first bridge arm of the third full-bridge LLC circuit includes a ninth switch Q9 and a tenth switch Q10, and the second bridge arm of the third full-bridge LLC circuit includes an eleventh switch Q11 and a twelfth switch Q12; the first bridge arm of the fourth full-bridge LLC circuit includes a thirteenth switch Q13 and a fourteenth switch Q14, and the second bridge arm of the fourth full-bridge LLC circuit includes a fifteenth switch Q15 and a sixteenth switch Q16; characterized in that, Based on the output load state, the output voltage and output current of the bidirectional DC-DC converter circuit are controlled by adjusting the switching transistors in the two full-bridge LLC circuits on the primary side, specifically including: When the output load is no-load or light-load, the full-bridge LLC circuit is transformed into a half-bridge LLC circuit by controlling the primary-side switches of the two full-bridge LLC circuits. The first and second arms of the two full-bridge LLC circuits are used as the upper and lower switches of the half-bridge LLC circuit by alternating switching cycles. The switching frequency of the full-bridge LLC circuit switches is maintained at the maximum value of 300kHz. The output voltage and current are controlled by adjusting the duty cycle of the switches. The duty cycle adjustment range of the switches is 0~50%, and the duty cycle adjustment method adopts hiccup intermittent control. When the output load changes from no load or light load to heavy load, during the first, second, third, or fourth switching cycles of the switching transistors, after all the switching transistors have adjusted their duty cycles to 50%, the half-bridge LLC circuit gradually switches to a full-bridge LLC circuit for control. The duty cycle of the switching transistors is fixed at a maximum of 50%, and then the PFM gain is adjusted by regulating the resonant cavity switching frequency of the full-bridge LLC circuit, thereby controlling the output power. The switching frequency control range of the full-bridge LLC circuit is 60kHz~300kHz, and the gain range is 0~1.2 times. When the output load changes from heavy load to no load or light load, during the first, second, third, or fourth switching cycle of the switching transistors, when the frequency of all switching transistors is adjusted to the maximum value of 300kHz, the duty cycle of the fixed switching transistors is set to a maximum of 50%. Then, the output voltage and current are controlled by adjusting the duty cycles of the upper and lower complementary switching transistors of the half-bridge LLC circuit. The duty cycle control range of the switching transistors in the full-bridge LLC circuit is 0~50%. When the output load changes from no load to light load or from light load to no load, during the first, second, third, or fourth switching cycle of the switching transistor, the frequency of the upper and lower switching transistors of the half-bridge LLC circuit is maintained at the maximum value of 300kHz. The output voltage and current are controlled by adjusting the duty cycle of the upper and lower complementary switching transistors of the half-bridge LLC circuit. The control range of the duty cycle of the switching transistors of the full-bridge LLC circuit is 0~50%.

6. The control method for the bidirectional DC-DC converter according to claim 1, characterized in that, When the output of the bidirectional DC-DC converter circuit is under no-load or light-load conditions and operates in both forward and reverse directions, the first and second arms of the two full-bridge LLC circuits on the primary side are controlled by alternating switching cycles of the switching transistors as the upper and lower complementary switching transistors of the half-bridge LLC circuit. In each switching cycle, the switching losses of the four switching transistors of the full-bridge LLC circuit and the two upper and lower switching transistors of one arm can be reduced. In a complete switching cycle of the full-bridge LLC circuit, the voltage applied to the resonant cavity is a square wave switching between +Vin and -Vin, and the voltage amplitude is equal to the input voltage Vin. After the full-bridge LLC circuit is transformed into a half-bridge LLC circuit, in a complete switching cycle of the half-bridge LLC circuit, the voltage applied to the resonant cavity is a square wave switching between +Vin / 2 and -Vin / 2, and the voltage amplitude is equal to half of the input voltage Vin, i.e., Vin / 2. The transformation of the full-bridge LLC circuit into a half-bridge LLC circuit halves the voltage applied to the switching transistors, reducing the switching transistor losses and output voltage ripple.

7. The control method for the bidirectional DC-DC converter according to claim 5, characterized in that, The PFM gain of the full-bridge LLC circuit can be adjusted according to the following formula: ； in, G ( Q , K , fs ) represents the PFM gain of the full-bridge LLC circuit. Q For quality factor, , Lr For the resonant inductance, Cr The capacitance of the resonant capacitor. Rac The equivalent resistance reflected from the output load resistance to the primary side. , N This represents the turns ratio of the primary and secondary sides of the transformer. R 0 represents the equivalent resistance of the output load. fs This refers to the switching frequency of the primary-side switching transistor in a full-bridge LLC circuit. fr This is the resonant frequency of the primary-side switching transistor in the full-bridge LLC circuit. K It is the ratio of the inductance of the primary excitation inductance to the inductance of the resonant inductance. , Lm For the magnetizing inductance, Lr The inductance is the resonant inductance; by adjusting the switching frequency of the full-bridge LLC circuit, the operating frequency of the full-bridge LLC circuit can be adjusted. fs Working at the resonant point fr This reduces circuit losses in the full-bridge LLC circuit and increases the circuit's transmission efficiency.

8. The control method for the bidirectional DC-DC converter according to claim 5, characterized in that, By controlling the switching action of the first switching device K1 or the second switching device K2, the primary and secondary transformer windings are switched in series and parallel to achieve high and low voltage switching of the output voltage, specifically including: During forward operation, when both the first switching device K1 and the second switching device K2 are open, the primary transformer windings T1-1 and T2-1 are in parallel, and the secondary transformer windings T1-2 and T2-2 are in parallel; all switching transistors are operational. When the first switching device K1 is open and the second switching device K2 is closed, the primary transformer windings T1-1 and T2-1 are in parallel, and the secondary transformer windings T1-2 and T2-2 are in series; the ninth, tenth, fifteenth, and sixteenth secondary switching transistors Q9, Q10, Q15, and Q16 are operational, while the eleventh, twelfth, Q12, thirteenth, and fourteenth switching transistors Q14 remain closed. In the closed state; when both the first switching device K1 and the second switching device K2 are closed, the primary transformer windings T1-1 and T2-1 are in series, and the secondary transformer windings T1-2 and T2-2 are in series. The primary switching transistors Q1, Q2, Q7, and Q8 are operational, while the secondary switching transistors Q3, Q4, Q5, and Q6 remain closed. The secondary switching transistors Q9, Q10, Q15, and Q16 are operational, while the secondary switching transistors Q11, Q12, Q13, and Q14 remain closed. In reverse operation, when both the second switch K2 and the first switch K1 are open, the primary transformer windings T1-2 and T2-2 are in parallel, and the secondary transformer windings T1-1 and T2-1 are in parallel; all switches are operational. When the second switch K2 is open and the first switch K1 is closed, the primary transformer windings T1-2 and T2-2 are in parallel, and the secondary transformer windings T1-1 and T2-1 are in series; the first, second, seventh, and eighth switches Q1, Q2, Q7, and Q8 on the secondary side are operational, while the third, fourth, fifth, and sixth switches Q3, Q4, Q5, and Q6 remain closed. When both switching devices K2 and K1 are closed, the primary transformer windings T1-2 and T2-2 are connected in series, and the secondary transformer windings T1-1 and T2-1 are connected in series. The secondary side switches Q1, Q2, Q7, and Q8 are operational, while the third, Q4, Q5, and Q6 remain closed. The primary side switches Q9, Q10, Q15, and Q16 are operational, while the eleventh, Q11, Q12, Q13, and Q14 remain closed.

9. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement a control method for a bidirectional DC-DC converter according to any one of claims 1-8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the control method for the bidirectional DC-DC converter according to any one of claims 1-8.

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