Non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converter and control method of non-isolated three-level soft-switching bidirectional DC / DC converter

Abstract

The invention discloses a non-isolated three-level soft switching bidirectional DC / DC converter suitable for an energy storage converter and a control method thereof. Comprising a DC input voltage source, a first N-channel MOS tube, a second N-channel MOS tube, a third N-channel MOS tube, a fourth N-channel MOS tube, a first main inductor, a second main inductor, a first filter capacitor, a second filter capacitor, a third filter capacitor and a battery. The resonant network 1 is composed of a first resonant capacitor, a second resonant capacitor, a first buffer capacitor, a second buffer capacitor and a first resonant inductor; the resonant network 2 is composed of a third resonant capacitor, a fourth resonant capacitor, a third buffer capacitor, a fourth buffer capacitor and a second resonant inductor. The whole circuit is simple in structure, compact in size and low in cost, switching loss is eliminated through the passive resonance network, and zero-voltage switching-on / switching-off of the switch within the wide duty ratio range of the battery is achieved.

Description

Technical Field

[0001] This invention relates to the field of power electronic converter research technology, and in particular to a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters and its control method. Background Technology

[0002] To actively address global climate change and promote sustainable energy development, vigorously developing renewable energy and advancing energy system transformation has become an inevitable trend. Against this backdrop, developing distributed renewable energy sources, such as wind power, photovoltaics, and fuel cells, is a crucial pathway to building a new energy system. However, renewable energy sources like wind and photovoltaics exhibit significant volatility, intermittency, and randomness. Large-scale direct grid connection would severely threaten the stable operation of the main power grid and power quality. To address these issues, DC microgrids have received widespread attention. They can effectively aggregate distributed renewable energy and achieve supply and demand balance between power sources and loads within the grid through comprehensive management. This not only helps mitigate the impact of distributed generation on the main power grid but also allows it to function as an independent and controllable power source or load, providing peak shaving and valley filling support for the main power grid.

[0003] However, with the widespread integration of new energy sources such as wind and solar power into DC microgrids, their output exhibits volatility, intermittency, and randomness due to weather and environmental factors, severely impacting the stability and power quality of low-inertia microgrid systems. To overcome this problem, energy storage systems need to be configured in microgrids to smooth out power imbalances between power sources and loads, stabilize the DC bus voltage, and thus ensure the stable operation of the microgrid. Large-scale energy storage systems, acting as "power sponges," play an irreplaceable role in smoothing fluctuations, peak shaving, valley filling, and improving grid stability. Among these, electrochemical energy storage technologies (such as lithium-ion batteries and flow batteries) have become the mainstream solution due to their advantages of flexible deployment and rapid response.

[0004] Electrochemical energy storage devices face a key common challenge in practical operation: their DC bus voltage fluctuates over a wide range depending on the charge and discharge state. This requires the power conversion unit to possess wide voltage adaptability and efficient bidirectional energy flow characteristics. Non-isolated bidirectional DC / DC converters, due to their simple structure and low cost, have become the preferred topology for interfacing battery energy storage systems with DC buses or inverters. However, traditional solutions have revealed a series of bottleneck problems in practical applications.

[0005] In traditional two-level buck-boost topologies, the voltage stress on switching devices increases exponentially with the voltage gain. In high-voltage applications (such as 1500V DC photovoltaic systems), devices must be used in series or high-voltage IGBTs must be selected. The former introduces complex dynamic voltage equalization circuits, while the latter leads to a surge in switching losses due to the tail current characteristics of IGBTs (especially at frequencies >20kHz). This severely restricts the increase in switching frequency, forcing the system to use bulky magnetic components, which runs counter to the trend of high power density in energy storage systems. To alleviate device stress, researchers have introduced three-level (TL) topologies, successfully reducing the voltage withstand requirement of the switching transistors to half of the input voltage. However, this structure still has significant drawbacks in hard-switching mode: during high-frequency switching, the turn-on losses, turn-off losses, and diode reverse recovery losses of power devices cannot be ignored. Although scholars have proposed many soft-switching topologies and control schemes to reduce switching losses, existing soft-switching schemes have various shortcomings: (1) Although existing resonant soft-switching schemes can reduce losses, they generally introduce resonant overvoltage and resonant overcurrent, which means that the main switch and passive devices not only need to withstand overvoltage, but also need to withstand the high peak current and high effective current caused by overcurrent, increasing the cost of device selection and bringing thermal safety issues. (2) Multiple sets of LC resonant networks and large-volume resonant inductors are often required, which seriously restricts the improvement of power density. (3) Although pure control schemes (such as triangular current mode TCM) can achieve soft switching, they force the main inductor current to work in the reverse increase mode after zero crossing, resulting in a sharp increase in the peak value of the main inductor current ripple. This greatly increases the iron loss and copper loss of magnetic components and leads to a significant increase in the power device loss, offsetting some of the benefits brought by soft switching. In addition, pure control schemes require the addition of current detection circuits and complex control, which not only puts forward higher performance requirements for control chips, but also reduces the reliability of the system. (4) Most auxiliary resonant schemes only achieve soft switching within a specific duty cycle or load range, making it difficult to cover the wide voltage variation requirements within the full state of charge range of the battery. (5) They generally rely on additional auxiliary switching transistors and matching isolation drive circuits. This not only significantly increases hardware costs and layout complexity, but also may cause stability issues due to control "delay" problems. Summary of the Invention

[0006] In view of the aforementioned existing problems, the present invention is proposed.

[0007] Therefore, this invention provides a non-isolated three-level soft-switching bidirectional DC / DC converter and its control method suitable for energy storage converters, solving the problems of high switching losses, low efficiency, resonant overvoltage / overcurrent risk, limited power density, and insufficient adaptability to wide voltage range in traditional non-isolated bidirectional DC / DC converters in high voltage and high frequency applications.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters, comprising:

[0010] The first group of MOSFETs and the second group of MOSFETs are controlled to work in coordination with a first phase difference;

[0011] The two MOSFETs in each group adopt a complementary conduction mechanism and set a dead time;

[0012] Through the resonance effect of resonant network 1 and resonant network 2, the resonant current is ensured to complete the commutation within the dead time, so as to realize zero-voltage turn-on and zero-voltage turn-off of the switching transistor.

[0013] As a preferred embodiment of the control method for a non-isolated three-level soft-switching bidirectional DC / DC converter applicable to energy storage converters according to the present invention, the implementation of the zero-voltage turn-off includes:

[0014] When the MOSFET is turned off, the drain-source voltage of the MOSFET rises or falls slowly through the resonance effect of the buffer capacitor and the resonant inductor, ensuring that the zero-voltage turn-off condition is met.

[0015] As a preferred embodiment of the control method for a non-isolated three-level soft-switching bidirectional DC / DC converter applicable to energy storage converters according to the present invention, the implementation of zero-voltage turn-on includes:

[0016] Before the MOSFET is turned on, the conduction status of the body diode is detected. If the body diode is already conducting, a drive signal is applied to achieve zero-voltage turn-on.

[0017] As a preferred embodiment of the control method for the non-isolated three-level soft-switching bidirectional DC / DC converter applicable to energy storage converters described in this invention, the method ensures that zero-voltage switching conditions are maintained within a wide voltage input range by adjusting the current direction of the first main inductor and the second main inductor and the current waveforms of resonant network 1 and resonant network 2.

[0018] As a preferred embodiment of the control method for the non-isolated three-level soft-switching bidirectional DC / DC converter applicable to energy storage converters described in this invention, wherein: when switching between boost mode and buck mode, the first phase difference and complementary conduction mechanism are kept unchanged, and the duty cycle of the drive signal is adjusted according to the input and output voltage relationship to maintain bidirectional energy flow.

[0019] In a second aspect, the present invention provides a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters, including a three-level bidirectional buck-boost power circuit, a resonant network 1 and a resonant network 2;

[0020] The three-level bidirectional buck-boost power circuit consists of a DC input voltage source, a first N-channel MOSFET, a second N-channel MOSFET, a third N-channel MOSFET, a fourth N-channel MOSFET, a first main inductor, a second main inductor, a first filter capacitor, a second filter capacitor, a third filter capacitor, and a battery.

[0021] The resonant network 1 is composed of a first resonant capacitor, a second resonant capacitor, a first buffer capacitor, a second buffer capacitor, and a first resonant inductor;

[0022] The resonant network 2 is composed of a third resonant capacitor, a fourth resonant capacitor, a third buffer capacitor, a fourth buffer capacitor, and a second resonant inductor.

[0023] As a preferred embodiment of the non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters described in this invention, the specific connection method includes:

[0024] The positive terminal of the DC input voltage source is connected to the positive terminal of the first filter capacitor, the drain of the first N-channel MOS transistor, the positive terminal of the first buffer capacitor, and the positive terminal of the first resonant capacitor, respectively.

[0025] The negative terminal of the DC input voltage source is connected to the negative terminal of the second filter capacitor, the source of the fourth N-channel MOS transistor, the negative terminal of the fourth buffer capacitor, and the negative terminal of the fourth resonant capacitor, respectively.

[0026] The negative terminal of the first filter capacitor is connected to the positive terminal of the second filter capacitor, the source of the second N-channel MOS transistor, the drain of the third N-channel MOS transistor, the negative terminal of the second buffer capacitor, and the positive terminal of the third buffer capacitor, respectively.

[0027] The source of the first N-channel MOSFET is connected to the negative terminal of the first buffer capacitor, the drain of the second N-channel MOSFET, the positive terminal of the second buffer capacitor, one end of the first resonant inductor, and one end of the first main inductor, respectively.

[0028] The source of the third N-channel MOS transistor is connected to the negative terminal of the third buffer capacitor, the drain of the fourth N-channel MOS transistor, the positive terminal of the fourth buffer capacitor, one end of the second resonant inductor, and one end of the second main inductor.

[0029] As a preferred embodiment of the non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters described in this invention, the specific connection method further includes:

[0030] The negative terminal of the first resonant capacitor is connected to the positive terminal of the second resonant capacitor and the other end of the first resonant inductor, respectively.

[0031] The negative terminal of the second resonant capacitor is connected to the other end of the first main inductor, one end of the battery, and the positive terminal of the third filter capacitor, respectively.

[0032] The positive terminal of the third resonant capacitor is connected to the other end of the second main inductor, the other end of the battery, and the negative terminal of the third filter capacitor, respectively.

[0033] The negative terminal of the third resonant capacitor is connected to the positive terminal of the fourth resonant capacitor and the other end of the second resonant inductor.

[0034] Thirdly, the present invention provides an electronic device, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor, when executing the computer-executable instructions, implements the steps of a control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for an energy storage converter.

[0035] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of a control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for an energy storage converter.

[0036] Compared with existing technologies, the advantages of this invention are as follows: This invention provides a non-isolated three-level soft-switching bidirectional DC / DC converter and its control method suitable for energy storage converters. By eliminating resonant overvoltage and resonant overcurrent, it avoids the difficulty of device selection and the thermal safety problems caused by resonant overcurrent, thereby reducing costs. Furthermore, it uses only two low-inductance resonant inductors, effectively controlling the increase in size. This invention avoids the introduction of high current ripple by the main inductor current and the need for additional current detection circuitry, while maintaining the same controller performance requirements. It achieves zero-voltage turn-on and zero-voltage turn-off of the main power switching devices over a wide voltage input range, greatly reducing switching losses and improving efficiency, thus breaking through the bottleneck of switching losses for the high-frequency development of devices. In addition, the circuit structure provided by this invention is simple and reliable, requiring no additional auxiliary switching transistors and their driving circuits, reducing complexity and failure risks, and keeping costs and size controllable. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 The circuit diagram shows a non-isolated three-level soft-switching bidirectional DC / DC converter topology provided in one embodiment of the present invention.

[0039] Figure 2 Provided for one embodiment of the present invention Figure 1 The circuit diagram shown is a diagram of the main operating modes during one switching cycle in Buck mode.

[0040] Figure 3 This is a schematic diagram of the waveforms of the main electrical quantities in charging and discharging modes within a switching cycle, as well as the gate drive signal control strategy of the main switch, provided for an embodiment of the present invention.

[0041] Figure 4 The diagram shows the simulation results of relevant variables of the circuit provided in one embodiment of the present invention in charging mode and discharging mode.

[0042] Figure 5 This is a prototype efficiency comparison curve provided for one embodiment of the present invention. Detailed Implementation

[0043] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0044] Example 1, referring to Figure 1 As one embodiment of the present invention, a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters is provided, such as... Figure 1 Specifically, it includes a three-level bidirectional buck-boost power circuit, resonant network 1, and resonant network 2;

[0045] Specifically, the three-level bidirectional buck-boost power circuit consists of a DC input voltage source (V in ), First N-channel MOSFET (Q1), Second N-channel MOSFET (Q2), Third N-channel MOSFET (Q3), Fourth N-channel MOSFET (Q4), First main inductor (L1), Second main inductor (L2), First filter capacitor (C)f1 ), second filter capacitor (C) f2 ), third filter capacitor (C) f3 ) and battery (V bat )constitute;

[0046] Specifically, the resonant network 1 consists of a first resonant capacitor (C r1 ), second resonant capacitor (C) r2 ), first buffer capacitor (C) s1 ), second buffer capacitor (C) s2 ) and the first resonant inductor (L r1 )constitute;

[0047] Specifically, resonant network 2 consists of a third resonant capacitor (C r3 ), fourth resonant capacitor (C) r4 ), third buffer capacitor (C) s3 ), fourth buffer capacitor (C) s4 ) and the second resonant inductor (L r2 )constitute.

[0048] In this embodiment of the invention, a novel non-isolated three-level soft-switching bidirectional DC / DC converter topology suitable for energy storage converters is constructed by a novel topology connection method together with a three-level bidirectional buck-boost power circuit. Combined with the main switch control scheme and parameter design, passive resonant network 1 and passive resonant network 2 can generate bidirectional triangular wave currents, creating zero-voltage turn-off conditions for the MOSFET switches (Q1-Q4) in the power circuit, and further achieving zero-voltage turn-on and zero-voltage turn-off of all main switching devices through coordinated control of the switch conduction timing.

[0049] In this embodiment of the invention, the specific connection method of the circuit is as follows:

[0050] DC input voltage source (V in The positive terminal of ) is connected to the first filter capacitor (C) respectively. f1 The positive terminal of the first N-channel MOSFET (Q1), the drain of the first N-channel MOSFET (Q1), and the first buffer capacitor (C) s1 The positive terminal of ) and the first resonant capacitor (C) r1 The positive terminal connection;

[0051] First filter capacitor (C) f1 The negative terminals of the capacitors are respectively connected to the second filter capacitor (C). f2 The positive terminal of the first N-channel MOSFET (Q1), the source terminal of the second N-channel MOSFET (Q2), the drain terminal of the third N-channel MOSFET (Q3), and the second buffer capacitor (C). s2 The negative terminal of ) and the third buffer capacitor (C) s3 The positive terminal connection;

[0052] DC input voltage source (Vin The negative terminals of the capacitors are respectively connected to the second filter capacitor (C). f2 The negative terminal of the fourth N-channel MOSFET (Q4), the source terminal of the fourth buffer capacitor (C) s4 The negative terminal of ) and the fourth resonant capacitor (C) r4 The negative terminal connection;

[0053] The source of the first N-channel MOSFET (Q1) is connected to the first buffer capacitor (C). s1 The negative terminal of the first N-channel MOSFET (Q2), the drain of the second N-channel MOSFET (Q2), and the second buffer capacitor (C) s2 The positive terminal of ) and the first resonant inductor (L) r1 One end of the first main inductor (L1) is connected to the other end of the main inductor (L2).

[0054] The source of the third N-channel MOSFET (Q3) is connected to the triple buffer capacitor (C) s3 The negative terminal of the fourth N-channel MOSFET (Q4), the drain of the fourth buffer capacitor (C) s4 The positive terminal of ) and the second resonant inductor (L) r2 Connect one end of the first main inductor (L1) and one end of the second main inductor (L2);

[0055] First resonant capacitor (C) r1 The negative terminals of the capacitors are respectively connected to the second resonant capacitor (C). r2 The positive terminal of ) and the first resonant inductor (L) r1 Connect the other end;

[0056] Second resonant capacitor (C) r2 The negative terminal of the battery is connected to the other end of the first main inductor (L1) and the battery (V). bat One end of the third filter capacitor (C) f3 The positive terminal connection;

[0057] Third resonant capacitor (C) r3 The positive terminal of the first inductor is connected to the other end of the second main inductor (L2) and the battery (V). bat The other end of the third filter capacitor (C) f3 The negative terminal connection;

[0058] Third resonant capacitor (C) r3 The negative terminals of the capacitors are respectively connected to the fourth resonant capacitor (C). r4 The positive terminal of ) and the second resonant inductor (L) r2 Connect the other end of the )

[0059] As described above, this invention eliminates resonant overvoltage and resonant overcurrent, avoiding the difficulty of device selection and the thermal safety issues caused by resonant overcurrent, thereby reducing costs. Furthermore, it effectively controls the increase in size by using only two low-inductance resonant inductors. This invention avoids the introduction of high current ripple by the main inductor current and the need for additional current detection circuitry, while maintaining the same performance requirements for the controller. It achieves zero-voltage turn-on and zero-voltage turn-off of the main power switching device over a wide voltage input range, significantly reducing switching losses and improving efficiency, thus breaking through the bottleneck of switching losses for the high-frequency development of devices. In addition, the circuit structure provided by this invention is simple and reliable, requiring no additional auxiliary switching transistors and their driving circuits, reducing complexity and failure risks, and keeping costs and size controllable.

[0060] Example 2, based on the previous example, referring to Figures 2-5 A control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters is provided, specifically including:

[0061] The first group of MOSFETs and the second group of MOSFETs are controlled to work in coordination with a first phase difference;

[0062] The two MOSFETs in each group adopt a complementary conduction mechanism and set a dead time;

[0063] Through the resonance effect of resonant network 1 and resonant network 2, the resonant current is ensured to complete the commutation within the dead time, so as to realize zero-voltage turn-on and zero-voltage turn-off of the switching transistor.

[0064] Specifically, the implementation of zero-voltage turn-off includes: when the MOSFET is turned off, the drain-source voltage of the MOSFET rises or falls slowly through the resonance effect of the buffer capacitor and the resonant inductor, ensuring that the zero-voltage turn-off condition is met.

[0065] Specifically, the implementation of zero-voltage turn-on includes: detecting whether the body diode is conducting before the MOSFET is turned on; if the body diode is conducting, then applying a drive signal to achieve zero-voltage turn-on.

[0066] Specifically, by adjusting the current direction of the first and second main inductors and the current waveforms of resonant network 1 and resonant network 2, zero-voltage switching conditions are maintained over a wide voltage input range.

[0067] Specifically, when switching between boost mode and buck mode, the first phase difference and complementary conduction mechanism remain unchanged, and the duty cycle of the drive signal is adjusted according to the input and output voltage relationship to maintain bidirectional energy flow.

[0068] In this embodiment of the invention, for ease of verification, all components in the circuit structure are considered ideal components. Let the current of the first main inductor L1 be i. L1 The current of the second main inductor L2 is i L2 vLr1 It is L r1 voltage, v Lr2 It is L r2 The voltage. i1-i4 represent the drain-source current of each N-channel MOSFET. cs1 -v cs4 Characterize each buffer capacitance C s1 -C s4 The voltage. V h This is the high-voltage side voltage, V l This is the low-voltage side voltage.

[0069] As Figure 2 (a) to Figure 2 As shown in (l), this non-isolated three-level soft-switching bidirectional DC / DC converter has 12 main operating modes within one switching cycle. The solid red arrows in the figure indicate the actual direction of the current in that branch of the converter, while the dashed blue arrows indicate that the actual direction of the current in that branch changes from the red arrow direction to the blue arrow direction in that mode. The key voltage and current waveforms in charging and discharging modes, as well as the start and end times of each mode, are shown below. Figure 3 As shown. Figure 3 In the middle, v g1 -v g4 These correspond to the gate drive signals of N-channel MOSFETs Q1-Q4, respectively. Q1 -v Q4 Characterizes the drain-source voltage of each N-channel MOSFET.

[0070] Combination Figure 3 right Figure 2 The 12 operating modes within one switching cycle are described as follows:

[0071] Working mode 1 [t0-t1, Figure 2 [(a)]: MOSFET Q3 is turned on, and MOSFETs Q4 and Q2 are turned off. At the beginning of this mode, t = t0, the gate drive signal v g1 The voltage level changes from high to low. Then C... s1 C s2 and L r1 Resonance begins to occur between them. C s2 Discharge begins, its voltage v Q2 It begins to descend at a constant speed. C s1 Charging begins, its voltage v Q1 It begins to rise at a constant speed. Due to C s1 The charging current provides freewheeling current to the main inductor L1, so i1 drops rapidly to 0, and at the same time, its voltage v Q1 As the voltage rises at a constant speed, Q1 achieves zero-voltage turn-off.

[0072] Under this operating mode, the relevant electrical parameters are related as follows:

[0073]

[0074] Working mode 2 [t1-t2, Figure 2 (b) : MOSFET Q3 is turned on, and MOSFETs Q4 and Q1 are turned off. At the beginning of this mode, v Cs1 Increase to 0.5V h Therefore, charging is complete. Meanwhile, v Cs2 When the voltage drops to zero, the body diode of Q2 turns on. Furthermore, L... r1 The voltage is clamped at V cr1 -0.5V h Its current i Lr1 It began to descend at a constant speed.

[0075] Under this operating mode, the relevant electrical parameters are related as follows:

[0076]

[0077] Working mode 3 [t2-t3, Figure 2 (c) : MOSFET Q3 is turned on, and MOSFETs Q4 and Q1 are turned off. At time t2, the gate drive signal v g2 When the voltage level changes from low to high, the body diode of Q2 will change the voltage level. Q2 With the clamp at zero volts, Q2 achieves zero-voltage turn-on.

[0078] Under this operating mode, the relevant electrical parameters are related as follows:

[0079]

[0080] Working mode 4 [t3-t4, Figure 2 (d) MOSFET Q2 is turned on, while MOSFETs Q4 and Q1 are turned off. At time t3, the gate drive signal v g3 From high level to low level, then C s3 C s4 and L r2 A similar resonance to that in the first stage also occurred, namely C s3 Charging, while C s4 Discharge. i3 rapidly drops to 0, voltage v Q3 The voltage rises slowly. Therefore, Q3 achieves zero-voltage shutdown.

[0081] Under this operating mode, the relevant electrical parameters are related as follows:

[0082]

[0083] Working mode 5 [t4-t5, Figure 2(e)]: MOSFET Q2 is turned on, and MOSFETs Q3 and Q1 are turned off. At time t5, v Cs3 Increase to 0.5V h Therefore, charging is complete. Meanwhile, v Cs4 When the voltage drops to zero, the body diode of Q4 turns on.

[0084] Under this operating mode, the relevant electrical parameters are related as follows:

[0085]

[0086] Working mode 6 [t5-t6, Figure 2 (f) : MOSFET Q2 is turned on, and MOSFETs Q3 and Q1 are turned off. At time t5, the gate drive signal v g4 When the voltage level changes from low to high, the body diode of Q4 will... Q4 With the clamp at zero volts, Q4 achieves zero-voltage turn-on. For example... Figure 3 As shown in (a), the current i4 during the time interval t in operating mode 6 c1 The current changes from negative to positive (as shown by the blue dashed arrow), and then continues to increase positively. When i4 becomes a positive current, MOSFET Q4 meets the zero-voltage turn-off condition. Next, L... r1 and L r2 The positive current at t c2 Change direction constantly (as shown by the blue dashed arrow). Then, at t... c3 At that moment, the current i2 also changes from negative to positive (as shown by the blue dashed arrow), which means that the MOSFET Q2 also has the zero-voltage turn-off condition.

[0087] Under this operating mode, the relevant electrical parameters are related as follows:

[0088]

[0089] Working mode 7 [t6-t7, Figure 2 (g) : MOSFET Q2 is turned on, and MOSFETs Q3 and Q1 are turned off. At time t6, the gate drive signal v g4 From high level to low level, then C s3 C s4 and L r2 Resonance occurs, i.e., C s4 Charging, while C s3 Discharge. As i4 rapidly drops to 0, its voltage v... Q4 The voltage rises slowly, and Q4 achieves zero-voltage shutdown.

[0090] Under this operating mode, the relevant electrical parameters are related as follows:

[0091]

[0092] Working mode 8 [t7-t8, Figure 2 [h]: MOSFET Q2 is turned on, and MOSFETs Q4 and Q1 are turned off. At time t7, v Cs4 Increase to 0.5V h Charging is complete. Meanwhile, v Cs3 When the voltage drops to zero, the body diode of Q3 turns on. Furthermore, L... r2 The voltage is clamped at 0.5V. h -V cr2 .

[0093] Under this operating mode, the relevant electrical parameters are related as follows:

[0094]

[0095] Working mode 9 [t8-t9, Figure 2 [i]: MOSFET Q2 is turned on, and MOSFETs Q4 and Q1 are turned off. At time t8, the gate drive signal v g3 When the voltage level changes from low to high, the body diode of MOSFET Q3 will change the voltage level. Q3 With the clamp at zero volts, Q3 achieves zero-voltage turn-on.

[0096] Under this operating mode, the relevant electrical parameters are related as follows:

[0097]

[0098] Working mode 10[t9-t 10 , Figure 2 [j]: MOSFET Q3 is turned on, and MOSFETs Q4 and Q1 are turned off. At time t9, the gate drive signal v g2 From high level to low level, then C s1 C s2 and L r1 Resonance occurred, i.e., C s2 Charging, while C s1 Discharge. Q2 The voltage drops rapidly to 0, v Q2 The voltage rises slowly. Therefore, Q2 achieves zero-voltage turn-off.

[0099] Under this operating mode, the relevant electrical parameters are related as follows:

[0100]

[0101] Working mode 11[t 10 -t 11 , Figure 2 [k]: MOSFET Q3 is turned on, while MOSFETs Q4 and Q2 are turned off. At t10 At time, v Cs2 Increase to 0.5V h Charging is complete. Meanwhile, v Cs1 When the voltage drops to zero, the body diode of Q1 turns on.

[0102] Under this operating mode, the relevant electrical parameters are related as follows:

[0103]

[0104] Working mode 12[t 11 -t0+T, Figure 2 (l)]: MOSFET Q3 is turned on, while MOSFETs Q4 and Q2 are turned off. At t 11 At time v, the gate drive signal g1 When the voltage level changes from low to high, the body diode of Q1 will change the voltage level. Q1 With the clamp at zero volts, Q1 achieves zero-voltage turn-on. For example... Figure 3 As shown in (a), the current i1 during the time interval t in operating mode 12 c4 As the voltage changes from negative to positive (as shown by the blue dashed arrow), MOSFET Q1 achieves zero-voltage turn-off. Next, L... r1 and L r2 The positive current at t c5 Change direction constantly (as shown by the blue dashed arrow). Then, at t... c6 At that moment, the current i3 also changes from negative to positive (as shown by the blue dashed arrow), which means that the MOSFET Q3 also has the zero-voltage turn-off condition.

[0105] Under this operating mode, the relevant electrical parameters are related as follows:

[0106]

[0107] Furthermore, in this embodiment Figure 3 (a) and Figure 3 (b) The waveforms of the main electrical quantities in charging and discharging modes within one switching cycle and the gate drive signal control strategy of the main switches are shown respectively. As can be seen from the waveform diagrams, the four main switches, N-channel MOSFETs Q1-Q4, work in two groups in coordination. The devices in the groups maintain a 180° phase difference to work together, and the two main switches in the group adopt a complementary conduction mechanism with dead time.

[0108] Figure 4 With high voltage side voltage V h =150V, low-voltage side voltage V l =60V, DC component of main inductor current I L =10A, peak-to-peak value of resonant inductor current I Lrpp1Using a 25A circuit as an example, simulation results of relevant variables in the circuit of this invention are given. Taking Q1 as an example, its successful zero-voltage switching / turn-off operation is illustrated: when the gate drive signal v of Q1... g1 When the signal is turned off (from high to low), i1 immediately drops to zero, and then v... Q1 Linear rise to 75V (0.5V) h This achieves zero-voltage shutdown. At v g1 When Q1 is turned on (from low to high level), the body diode of Q1 has already been turned on, i1 is negative, and Q1 achieves zero-voltage turn-on.

[0109] Figure 5 This is a comparison curve of the efficiency of the converter of the present invention and the prototype of a traditional non-isolated hard-switching bidirectional DC / DC converter. Figure 5 The efficiency test results fully confirm its efficiency improvement advantage: when the output power is 0.5P... max At that time, the soft-switching topology improves efficiency by 1.36% compared to the hard-switching topology; while at full load output power P max At that time, the efficiency improvement increased to 2.03%, and the efficiency gain increased with the increase of output current.

[0110] Therefore, this invention proposes an innovative solution to the problems of the prior art: a control method for a novel non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters. This method is of great significance for promoting the evolution of energy storage system converters towards higher efficiency, higher power density, and higher reliability.

[0111] Example 3, based on the previous example, provides an electronic device including a processor, memory, communication interface, display screen, and input device connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface communicates with external terminals via wired or wireless means; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements the method provided in this example. The display screen can be a liquid crystal display (LCD) or an e-ink display. The input device can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the device's casing, or an external keyboard, touchpad, or mouse.

[0112] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method proposed in the above embodiments.

[0113] The storage medium proposed in this embodiment belongs to the same inventive concept as the method proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0114] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause an electronic device (which may be a personal computer, server, or network device, etc.) to execute the method of the embodiments of the present invention.

[0115] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters, characterized in that, include: The first group of MOSFETs and the second group of MOSFETs are controlled to work in coordination with a first phase difference; The two MOSFETs in each group adopt a complementary conduction mechanism and set a dead time; Through the resonance effect of resonant network 1 and resonant network 2, the resonant current is ensured to complete the commutation within the dead time, so as to realize zero-voltage turn-on and zero-voltage turn-off of the switching transistor.

2. The control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters as described in claim 1, characterized in that, The implementation of the zero-voltage turn-off includes: When the MOSFET is turned off, the drain-source voltage of the MOSFET rises or falls slowly through the resonance effect of the buffer capacitor and the resonant inductor, ensuring that the zero-voltage turn-off condition is met.

3. The control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters as described in claim 2, characterized in that, The implementation of zero-voltage turn-on includes: Before the MOSFET is turned on, the conduction status of the body diode is detected. If the body diode is already conducting, a drive signal is applied to achieve zero-voltage turn-on.

4. The control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters as described in claim 3, characterized in that, By adjusting the current direction of the first and second main inductors and the current waveforms of resonant network 1 and resonant network 2, zero-voltage switching conditions are maintained over a wide voltage input range.

5. The control method for a non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters as described in claim 4, characterized in that, When switching between boost mode and buck mode, the first phase difference and complementary conduction mechanism remain unchanged, and the duty cycle of the drive signal is adjusted according to the input and output voltage relationship to maintain bidirectional energy flow.

6. A non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters, characterized in that, Includes a three-level bidirectional buck-boost power circuit, resonant network 1, and resonant network 2; The three-level bidirectional buck-boost power circuit consists of a DC input voltage source, a first N-channel MOSFET, a second N-channel MOSFET, a third N-channel MOSFET, a fourth N-channel MOSFET, a first main inductor, a second main inductor, a first filter capacitor, a second filter capacitor, a third filter capacitor, and a battery. The resonant network 1 is composed of a first resonant capacitor, a second resonant capacitor, a first buffer capacitor, a second buffer capacitor, and a first resonant inductor; The resonant network 2 is composed of a third resonant capacitor, a fourth resonant capacitor, a third buffer capacitor, a fourth buffer capacitor, and a second resonant inductor.

7. The non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters as described in claim 6, characterized in that, Specific connection methods include: The positive terminal of the DC input voltage source is connected to the positive terminal of the first filter capacitor, the drain of the first N-channel MOS transistor, the positive terminal of the first buffer capacitor, and the positive terminal of the first resonant capacitor, respectively. The negative terminal of the DC input voltage source is connected to the negative terminal of the second filter capacitor, the source of the fourth N-channel MOS transistor, the negative terminal of the fourth buffer capacitor, and the negative terminal of the fourth resonant capacitor, respectively. The negative terminal of the first filter capacitor is connected to the positive terminal of the second filter capacitor, the source of the second N-channel MOS transistor, the drain of the third N-channel MOS transistor, the negative terminal of the second buffer capacitor, and the positive terminal of the third buffer capacitor, respectively. The source of the first N-channel MOSFET is connected to the negative terminal of the first buffer capacitor, the drain of the second N-channel MOSFET, the positive terminal of the second buffer capacitor, one end of the first resonant inductor, and one end of the first main inductor, respectively. The source of the third N-channel MOS transistor is connected to the negative terminal of the third buffer capacitor, the drain of the fourth N-channel MOS transistor, the positive terminal of the fourth buffer capacitor, one end of the second resonant inductor, and one end of the second main inductor.

8. The non-isolated three-level soft-switching bidirectional DC / DC converter suitable for energy storage converters as described in claim 7, characterized in that, Specific connection methods also include: The negative terminal of the first resonant capacitor is connected to the positive terminal of the second resonant capacitor and the other end of the first resonant inductor, respectively. The negative terminal of the second resonant capacitor is connected to the other end of the first main inductor, one end of the battery, and the positive terminal of the third filter capacitor, respectively. The positive terminal of the third resonant capacitor is connected to the other end of the second main inductor, the other end of the battery, and the negative terminal of the third filter capacitor, respectively. The negative terminal of the third resonant capacitor is connected to the positive terminal of the fourth resonant capacitor and the other end of the second resonant inductor.

9. An electronic device comprising a memory and a processor, characterized in that: The memory is used to store computer-executable instructions, and when the processor executes the computer-executable instructions, it implements the steps of the control method for a non-isolated three-level soft-switching bidirectional DC / DC converter applicable to an energy storage converter as described in any one of claims 1 to 5.

10. A computer-readable storage medium having computer-executable instructions stored thereon, characterized in that: When the computer-executable instructions are executed by the processor, they implement the steps of the control method for a non-isolated three-level soft-switching bidirectional DC / DC converter applicable to an energy storage converter as described in any one of claims 1 to 5.

Images