An integrated equalization system based on bidirectional LLC resonant converter

Abstract

The application discloses an integrated equalization system based on a bidirectional LLC resonant converter, and relates to the technical field of power electronics. The system comprises the following steps: a storage unit string is connected in series between the positive and negative poles of the output side of the bidirectional LLC resonant converter, every two adjacent storage units are connected to the same secondary winding through a diode, and every two adjacent secondary windings are coupled with a primary winding; the same name end of all the primary windings is connected to the same name end of a secondary equalization winding, and the different name end is connected to the different name end of the secondary equalization winding; and the secondary equalization winding is coupled with a transmitting coil of the bidirectional LLC resonant converter. In the system, every secondary winding equalizes two adjacent storage units, the number of related components is reduced, the volume of the energy storage system is significantly reduced, and the system has higher scalability; meanwhile, the energy storage system can realize full-condition equalization in the charging, discharging and idle states, and overcomes the technical defects that the traditional integrated equalizer cannot work in the idle state of the energy storage system.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to an integrated equalization system based on a bidirectional LLC resonant converter. Background Technology

[0002] Supercapacitors play a crucial role in urban rail transit, power grid frequency regulation, and high-power pulse applications due to their high power density, fast response, and long cycle life. In practical applications, energy storage units are typically connected in series to meet high voltage requirements. Due to differences in manufacturing processes, operating environments, and aging processes, voltage imbalance inevitably occurs between series-connected energy storage units. Voltage imbalance severely reduces the usable capacity and energy utilization efficiency of the energy storage system, accelerates unit aging, and can even trigger significant safety hazards such as thermal runaway. Therefore, introducing voltage balancing circuits to improve the voltage consistency between individual energy storage units is essential.

[0003] Existing integrated equalizer topologies generally suffer from two limitations. First, when applied to large-scale energy storage systems, the number of key equalization components in existing architectures is proportional to the number of energy storage units, leading to a significant increase in system size, weight, and cost as the scale expands, resulting in poor scalability. Second, most existing equalizers can only operate during active charging and discharging of the energy storage system, and cannot perform voltage equalization when the energy storage system is idle, limiting the operating modes and the timeliness of equalization. Summary of the Invention

[0004] To address the aforementioned technical problems in the prior art, this invention aims to provide an integrated equalization system based on a bidirectional LLC resonant converter. This system solves the technical problems of existing integrated equalizers when applied to large-scale energy storage systems, which result in poor scalability, a large number of components, high cost, and the inability to achieve equalization in the idle state of the energy storage system due to the linear relationship between the number of magnetic components and the number of energy storage units.

[0005] Specifically, the technical solution is as follows: An integrated equalization system based on a bidirectional LLC resonant converter, comprising:

[0006] n Energy storage unit group Series-connected in the same direction constitutes an energy storage unit string, and an energy storage unit group. Includes four energy storage units connected in series. to , ;

[0007] The positive terminal of the output side of the bidirectional LLC resonant converter is connected to the energy storage unit. The positive and negative terminals are connected to the energy storage unit. The negative electrode;

[0008] Energy storage unit group In the middle, energy storage unit The positive terminal is connected to the diode. The negative electrode is connected to the energy storage unit. positive and secondary windings heteronym, diode The positive terminal is connected to the secondary winding. The same terminal and diode The negative electrode, energy storage unit The negative terminal is connected to the energy storage unit. Positive electrode, diode positive electrode and diode The negative electrode, energy storage unit The negative terminal is connected to the energy storage unit. positive and secondary windings heteronym, diode The positive terminal is connected to the secondary winding. Same-name terminal and diode The negative electrode, energy storage unit The negative terminal is connected to the diode. The positive electrode;

[0009] Secondary winding Secondary winding and primary winding Winded on the same magnetic core;

[0010] n Primary winding The terminals with the same name are connected to each other, and the terminals with different names are connected to each other; primary winding The same-named terminal is connected to the secondary equalization winding. The same-named terminal, primary winding The opposite-named terminal is connected to the secondary equalization winding. Synonyms;

[0011] Secondary equalization winding With the transmitting coil of the bidirectional LLC resonant converter coupling.

[0012] Compared to existing technologies, the technical solution provided by this invention utilizes the symmetrical resonant current waveform of a bidirectional LLC resonant converter and the "dual-unit per winding" equalization structure, enabling each secondary winding to equalize two adjacent energy storage units. This halves the required number of secondary windings, thereby reducing the number of magnetic components, diodes, and connecting wires. It can significantly reduce the size of traditional energy storage systems, reduce the number of components and costs, and has higher scalability. At the same time, it can achieve full-condition equalization of the energy storage system in charging, discharging, and idle states, overcoming the technical defect that traditional integrated equalizers cannot work in the idle state of the energy storage system. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the circuit structure of an integrated equalization system in one embodiment of the present invention.

[0014] Figure 2 This is a schematic diagram of the key steady-state waveform of a bidirectional LLC resonant converter in charging mode according to an embodiment of the present invention.

[0015] Figure 3 This is a schematic diagram of the integrated equalization system in the positive half-cycle mode 1 of the charging equalization mode in one embodiment of the present invention.

[0016] Figure 4 This is a schematic diagram of the integrated equalization system in the positive half-cycle mode 2 of the charging equalization mode in one embodiment of the present invention.

[0017] Figure 5 This is a schematic diagram of the integrated equalization system in the positive half-cycle mode 3 of the charging equalization mode in one embodiment of the present invention.

[0018] Figure 6 This is a schematic diagram of the integrated equalization system in the positive half-cycle mode 4 of the charging equalization mode in one embodiment of the present invention.

[0019] Figure 7 This is a schematic diagram of the main operating modes of the integrated equalization system in the positive half-cycle of the discharge equalization mode in one embodiment of the present invention.

[0020] Figure 8 This is a diagram showing the main operating modes of the integrated equalization system in the negative half-cycle of the discharge equalization mode in one embodiment of the present invention.

[0021] Figure 9 This is a diagram of the main operating modes of the integrated equalization system in the positive half-cycle of the self-equalization mode in one embodiment of the present invention.

[0022] Figure 10 This is a diagram showing the main operating modes of the integrated equalization system in the negative half-cycle of the self-equalization mode in one embodiment of the present invention.

[0023] Figure 11This is an experimental curve showing the voltage change of the energy storage unit in charging equalization mode according to one embodiment of the present invention.

[0024] Figure 12 This is an experimental curve showing the voltage change of the energy storage unit in discharge equalization mode according to one embodiment of the present invention.

[0025] Figure 13 This is an experimental curve showing the voltage change of the energy storage unit in self-balancing mode according to one embodiment of the present invention.

[0026] Figure 14 This is a charging equalization efficiency curve of an integrated equalization system in one embodiment of the present invention.

[0027] Figure 15 This is a discharge equalization efficiency curve of an integrated equalization system in one embodiment of the present invention.

[0028] Figure 16 This is a self-balancing efficiency curve of the integrated equalization system in one embodiment of the present invention. Detailed Implementation

[0029] The technical solutions provided by the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0030] like Figure 1 As shown, this embodiment provides an integrated equalization system based on a bidirectional LLC resonant converter for voltage equalization of multiple series-connected energy storage units. The integrated equalization system includes a bidirectional DC-DC charging / discharging module and a parallel voltage equalization module. The bidirectional DC-DC charging / discharging module is based on a bidirectional LLC resonant converter topology and is used to implement a DC source. Efficient bidirectional energy transfer between energy storage unit strings (forming an energy storage system).

[0031] The bidirectional DC-DC charging and discharging module includes a switching transistor. To the switching transistor The primary-side full bridge and a switch transistor are composed of a primary-side full bridge and a switch transistor. To the switching transistor The secondary-side full bridge is composed of switching transistors. To the switching transistor Various types of switching transistors can be selected. Preferably, a MOSFET that can be controlled to turn on and off is selected, with built-in diodes and capacitors for easy soft switching. Optionally, the energy storage unit can be a supercapacitor or lithium battery, etc., connected in series to form a supercapacitor string or lithium battery string energy storage structure.

[0032] The bidirectional DC-DC charging and discharging module also includes: a multi-winding main transformer. It has a primary winding (Transmitting coil), a primary and secondary winding for main power transmission (Receiving coil) and a secondary equalization winding for equalization. Both are with the primary winding Coupling, primary and secondary windings Connected to the secondary side of the full bridge. An LLC resonant cavity, consisting of a resonant inductor. Resonant capacitor and main transformer excitation inductor Together they constitute the excitation inductor. and main transformer primary winding They are in parallel, resonant inductors and resonant capacitor After being connected in series, it is then connected in series with both; primary and secondary windings Secondary balancing winding With the primary winding respectively coupling.

[0033] The parallel voltage equalization module includes at least one multi-winding equalization transformer. ( Figure 1 The example in the middle is a balancing transformer. and equalization transformer All balancing transformers The primary windings are all connected in parallel to the main transformer. Secondary equalization winding And driven by the high-frequency symmetrical AC voltage induced in it. Each equalization transformer It has two secondary windings, such as a balancing transformer. With secondary winding and secondary winding Each secondary winding (with secondary winding as the unit) (For example) all are achieved through diodes and diodes Connected to the energy storage unit respectively and energy storage units .

[0034] Its connection method is configured as follows: in the secondary winding During the positive half-cycle of the AC voltage, the secondary winding Top positive, bottom negative, diode It is forward biased and conducts, utilizing the energy of the positive half-cycle as an energy storage unit. Provide equalizing current; in the secondary winding During the negative half-cycle of the AC voltage, the secondary winding Polarity reversal is positive at the bottom and negative at the top for diodes. It is forward biased and turned on, using the energy of the negative half-cycle as an energy storage unit. Provides balanced current.

[0035] In summary, the structure of the integrated equalization system provided in this embodiment is as follows:

[0036] n Energy storage unit group Series-connected in the same direction constitutes an energy storage unit string, and an energy storage unit group. Includes four energy storage units connected in series. to , The positive terminal of the output side of the bidirectional LLC resonant converter is connected to the energy storage unit. The positive and negative terminals are connected to the energy storage unit. The negative electrode; energy storage unit group In the middle, energy storage unit The positive terminal is connected to the diode. The negative electrode is connected to the energy storage unit. positive and secondary windings heteronym, diode The positive terminal is connected to the secondary winding. Same-name terminal and diode The negative electrode, energy storage unit The negative terminal is connected to the energy storage unit. Positive electrode, diode positive electrode and diode The negative electrode, energy storage unit The negative terminal is connected to the energy storage unit. positive and secondary windings heteronym, diode The positive terminal is connected to the secondary winding. Same-name terminal and diode The negative electrode, energy storage unit The negative terminal is connected to the diode. Positive terminal; secondary winding Secondary winding and primary winding Winded on the same magnetic core; Primary winding The terminals with the same name are connected to each other, and the terminals with different names are connected to each other; primary winding The same-named terminal is connected to the secondary equalization winding. The same-named terminal, primary winding The opposite-named terminal is connected to the secondary equalization winding. The variant of the term.

[0037] The bidirectional LLC resonant converter includes: capacitance With DC source Parallel connection, DC source The positive terminal is connected to the switching transistor. Drain and switching transistor The drain and negative terminal are connected to the switching transistor. source and switch The source; the switch transistor The source is connected to the switching transistor. The drain of the circuit is connected to the resonant inductor. Connected to the transmitting coil The same terminal; switching transistor The source is connected to the switching transistor. The drain, and through the resonant capacitor Connected to the transmitting coil Equivalent terminal; Magnetizing inductor With transmitting coil Parallel connection; receiving coil With transmitting coil Coupling; Receiving coil The same terminal is connected to the switching transistor. source and switch The drain of the transistor is connected to the switching transistor at a different terminal. source and switch Drain; Switching transistor Drain and switching transistor The drain is connected to the energy storage unit. The positive terminal of the switching transistor source and switch The source is connected to the energy storage unit. The negative terminal of the capacitor; C out Connected in series and parallel with the energy storage unit.

[0038] By utilizing the "dual-unit per winding (one winding, two energy storage units)" structure described above, this embodiment fully leverages the inherent symmetrical AC waveform of the bidirectional LLC converter, enabling each secondary winding of the balancing transformer to balance two adjacent energy storage units. This halves the required number of secondary windings in the balancing transformer, significantly reducing the number of magnetic components and diodes, lowering the cost and size of the energy storage system, and improving its scalability.

[0039] The following provides a detailed explanation of the balancing principle of the integrated balancing system provided in this embodiment under three different working modes.

[0040] 1. For example Figures 2 to 6 As shown, charging balancing mode: In this mode, the control voltage... To control voltage One-to-one control switch transistor To the switching transistor Integrated equalization system from DC source Energy is harvested. The primary-side full-bridge converter operates as an inverter, while the secondary-side full-bridge converter operates as a rectifier, charging the entire energy storage unit string. Simultaneously, the main transformer... Secondary equalization winding The system senses a high-frequency AC voltage, which drives the parallel voltage balancing module to operate. Figure 2 This demonstrates the key steady-state waveforms of the bidirectional LLC resonant converter in this mode, including the voltages at the midpoints of the primary arms (midpoint A and midpoint B). Resonant current Excitation current and primary current .

[0041] Figures 3 to 6 The four typical operating modes of the positive half-cycle in the charging equalization mode are shown in detail, and the operating principle of the negative half-cycle is symmetrical to this.

[0042] like Figure 3 As shown, The integrated equalization system operates in mode 1 of the positive half-cycle of the charging equalization mode, with the switching transistor... and switching transistor On, switching transistor and switching transistor When the circuit is turned on, a resonant current is generated on the secondary side. Resonant current Greater than the excitation current Energy flows from the input side to the output side. Simultaneously, the secondary balancing winding... Induced voltage drives the equalization transformer During the positive half-cycle, the secondary winding... and secondary winding Both are positive at the top and negative at the bottom, making the diode and diodes Turning on, for energy storage units with lower voltage and energy storage units Perform equalization charging.

[0043] like Figure 4 As shown, The integrated equalization system operates in mode 2 of the positive half-cycle of the charging equalization mode, with resonant current. Reduce to equal to the excitation current transformer primary current Drops to zero. The secondary-side switching transistors used for rectification. and switching transistor Natural shutdown. At this time, the resonant cavity consists only of the resonant inductor. Resonant capacitor And excitation inductance Resonance occurs during which energy is exchanged within the resonant cavity. The parallel voltage equalization module ceases operation at this stage.

[0044] like Figure 5 As shown, The integrated equalization system operates in mode 3 of the positive half-cycle of the charging equalization mode. At any moment, the switching transistor and switching transistor Turn off, entering the dead zone. Because the resonant cavity is inductive, the resonant current... Lagging behind voltage, it begins to affect the switching transistor. and switching transistor The parasitic capacitance discharges and affects the switching transistor. and switching transistor The parasitic capacitance is charged.

[0045] like Figure 6 As shown, The integrated equalization system operates in mode 3 of the positive half-cycle of the charging equalization mode. Switching transistor... and switching transistor The parasitic capacitance is discharged to zero, and the resonant current... Flow through the switching transistor and switching transistor The body diode is used to clamp the voltage across it to zero. The zero-voltage switch (ZVS) being turned on at a given moment creates the conditions.

[0046] 2. For example Figure 7 and Figure 8 As shown, the discharge balancing mode illustrates the main operating modes of the positive and negative half-cycles (for simplicity, only the main energy flow is shown in the figure, omitting detailed dead zone and freewheeling modes). In this mode, the energy storage unit string acts as the power source, the secondary-side full-bridge operates as an inverter, and the primary-side full-bridge operates as a rectifier, feeding energy back to the DC source. Side (load).

[0047] like Figure 7 As shown, during the positive half-cycle (switching transistor) and switching transistor (Conduction), switching transistor and switching transistor The inverter operation causes the main transformer receiving coil and secondary equalization winding An AC voltage is induced at the top (e.g., positive at the top, negative at the bottom). Secondary balancing winding. Drive the parallel voltage equalization module to make the diode and diodes Conducting and balancing energy storage units and energy storage units 。 (See the image.) R load This represents the line resistance.

[0048] like Figure 8 As shown, in the negative half-cycle (switching transistor) and switching transistor (Conduction), switching transistor and switching transistor The inverter operation causes the main transformer receiving coil and secondary equalization winding A reverse AC voltage is induced at the top (e.g., positive at the bottom and negative at the top). Secondary balancing winding. Drive the parallel voltage equalization module to make the diode and diodes Conducting and balancing energy storage units and energy storage units .

[0049] 3. For example Figure 9 and Figure 10 As shown, the self-balancing mode (i.e., idle / quiet mode) is the main operating mode of the positive and negative half-cycles under self-balancing mode. Self-balancing mode overcomes the limitation of traditional integrated equalizers that cannot operate during idle periods. At this time, the DC source... When disconnected, the primary-side full-bridge circuit ceases operation. The control system then drives only the secondary-side full-bridge circuit as an inverter, drawing a small amount of energy from the entire energy storage unit string.

[0050] like Figure 9 As shown, during the positive half-cycle, the switching transistor... and switching transistor When the circuit is turned on, energy flows from the energy storage unit through the receiving coil. Flow into the main transformer Secondary equalization winding The induced voltage (e.g., positive at the top and negative at the bottom) drives the parallel voltage equalization module, causing the diode to... and diodes Turning on the circuit transfers energy (primarily from the cells with higher voltage in the string) to the energy storage unit. and energy storage units .

[0051] like Figure 10 As shown, during the negative half-cycle, the switching transistor... and switching transistor When the circuit is turned on, energy flows from the energy storage unit into the main transformer. Secondary equalization winding The induced reverse voltage (e.g., positive at the bottom and negative at the top) drives the equalization module, causing the diode to... and diodes The circuit is activated, transferring energy to the energy storage unit. and energy storage units .

[0052] In summary, the integrated equalization system provided in this embodiment can achieve effective voltage equalization under three operating conditions: charging, discharging, and idle.

[0053] The switching transistors of the primary-side full-bridge in the above bidirectional LLC resonant converter To the switching transistor Controlled by a pair of complementary PWM (Pulse Width Modulation) signals, the switching frequency is... The bidirectional LLC resonant converter exhibits two resonant frequencies, depending on the magnetizing inductance. Whether it participates in resonance. The two frequencies are the main resonant frequencies. and secondary resonant frequency Main resonant frequency By resonant inductor and resonant capacitor The decision is made using the following formula:

[0054] ;

[0055] Secondary resonant frequency Except for resonant inductors and resonant capacitor In addition, it also involves the excitation inductor. The formula is as follows:

[0056] ;

[0057] To ensure high efficiency, the LLC resonant slot in the bidirectional LLC resonant converter is designed to exhibit inductive impedance, satisfying the secondary resonant frequency. Less than the main resonant frequency The main resonant frequency Less than the switching frequency This causes the inverter's output current to lag behind its output voltage. During the dead time, the resonant current... It discharges the parasitic output capacitance of the switch that is about to be turned on, forcing its drain-source voltage to drop to zero before it is turned on, thereby achieving zero-voltage switching.

[0058] main transformer In the middle, the transmitting coil The number of turns is Secondary equalization winding The number of turns is Equalization transformer In the middle, primary winding The number of turns is Secondary winding The number of turns is The voltage gain of the bidirectional LLC resonant converter is Secondary winding The voltage across the two ends is The formula is as follows:

[0059] ;

[0060] in, This is the serial number of the secondary winding. , The total voltage transfer coefficient represents the voltage transfer from the DC source. The total voltage ratio to the secondary side of the balancing transformer. The total voltage transfer coefficient under steady-state operating conditions. It can be considered a constant. In each switching cycle... Inside, when voltage Voltage exceeding that of a single energy storage unit With the forward voltage drop of the diode When the sum is equal, the diode Turn on, balance current The flow begins. At this point, the parallel voltage equalization module can be equivalent to a series RL circuit driven by a constant voltage source. According to Kirchhoff's Voltage Laws (KVL), the following differential equation can be derived:

[0061] ;

[0062] In the formula, The leakage inductance of the secondary winding of the equalization transformer The total equivalent series resistance includes the winding copper resistance, diode on-resistance, and capacitor ESR (Equivalent Series Resistance).

[0063] One switching cycle Inside, the voltage of the energy storage unit The changes are negligible. Let the initial conduction time be... Current at time Solving the equation, we get the following formula:

[0064] ;

[0065] In the formula, Let be the time constant, and the formula is as follows:

[0066] .

[0067] As can be seen from the above equation, the balanced current... It increases exponentially, and its steady-state value is affected by the total equivalent series resistance. The rate of ascent is limited by the time constant. Decision made. The conduction time ends, i.e., the termination time is reached. Balanced current Reaching peak The formula is as follows:

[0068] ;

[0069] Average balance current flowing into the energy storage unit It is a balanced current Throughout the cycle The average value within the range. For the equilibrium current. exist Integrate over the time period to calculate the average balance current. The formula is as follows:

[0070] ;

[0071] Average balance current With voltage difference Proportional. When the voltage of a single energy storage unit... At lower voltage levels, a larger voltage difference results in a larger balancing current; conversely, a larger voltage difference results in a smaller balancing current. When all cells reach equilibrium, the average balancing current... As the voltage approaches zero, the voltages of each individual cell will converge, as shown in the following formula:

[0072] ;

[0073] The above results demonstrate that the final equilibrium voltage of all individual energy storage units is determined solely by the balancing transformer. Secondary winding voltage at both ends and the forward voltage drop of the diode This decision enables automatic voltage balancing of the entire parallel voltage balancing module.

[0074] As can be seen from the above, in order to ensure that the trigger parallel voltage equalization module enters the operating state, it is necessary to adjust the ratio of the number of turns in the secondary equalization winding to the number of turns in the transmitting coil to meet the effective voltage induced by the equalization transformer (i.e., the secondary winding). voltage at both ends It must be greater than the forward voltage drop of the diode. Voltage of a single energy storage unit The sum of these is equivalent to the output current of the secondary winding (average equalization current). The value is greater than 0, specifically, it satisfies the following formula:

[0075] .

[0076] To verify the full-condition balancing capability, this embodiment uses two energy storage unit groups (including the energy storage unit groups). and energy storage unit group Under the conditions of charging, discharging, and self-balancing, the integrated equalization system was subjected to charging, discharging, and self-balancing experiments, and the results are as follows: Figures 11 to 13 As shown. Among them, to They are energy storage unit groups Medium energy storage unit To energy storage unit The voltage at both ends, to They are energy storage unit groups Medium energy storage unit To energy storage unit The voltage at both ends.

[0077] like Figure 11 As shown, in charging balancing mode, the initial voltages of the eight energy storage units are distributed between 3.1030V and 3.9005V, with an initial maximum voltage difference of 0.7975V. Approximately 30 seconds after charging balancing begins, the voltages of all energy storage units converge to between 3.8330V and 3.8585V, and the maximum voltage difference is rapidly reduced to 0.0255V.

[0078] like Figure 12 As shown, in discharge equalization mode, the initial voltage distribution is between 3.3040V and 4.1290V, with an initial maximum voltage difference of 0.8250V. Approximately 15 seconds after discharge equalization begins, the voltage converges to between 3.7360V and 3.7605V, and the maximum voltage difference decreases to 0.0245V.

[0079] like Figure 13 As shown, in self-balancing mode, the initial voltage distribution is between 3.2470V and 4.1190V, with an initial maximum voltage difference of 0.8720V. After approximately 15 seconds of self-balancing, the voltage converges to between 3.8510V and 3.8765V, and the maximum voltage difference decreases to 0.0255V.

[0080] The experimental results show that the integrated equalization system proposed in this embodiment can achieve fast and effective voltage equalization under three operating conditions: charging, discharging, and idle.

[0081] The efficiency curves of the integrated equalization system in charging, discharging, and self-balancing modes are shown in the following figures. Figures 14 to 16 As shown. Figure 14 and Figure 15As shown, within the main power transmission range of 10W to 30W, the peak efficiency of charging equalization reaches 95.5%, and the peak efficiency of discharging equalization reaches 95.7%, verifying the high efficiency of the system's main energy path. Figure 16 As shown, in self-balancing mode, the balancing power ranges from 2.0W to 4.5W, and the system efficiency remains between 87% and 89%, indicating that high-efficiency energy transfer can be maintained even in idle mode.

[0082] As can be seen from the above embodiments and accompanying drawings, compared with the prior art, the technical solution provided by the present invention utilizes the symmetrical resonant current waveform of the bidirectional LLC resonant converter and the "dual-unit per winding" equalization structure, so that each secondary winding can equalize two adjacent energy storage units, thereby halving the number of secondary windings required, thus reducing the number of magnetic components, diodes and connecting wires, significantly reducing the volume of traditional energy storage systems, reducing the number of components and costs, and possessing higher scalability; at the same time, it can realize full-condition equalization of the energy storage system in charging, discharging and idle states, overcoming the technical defect that traditional integrated equalizers cannot work in the idle state of the energy storage system.

Claims

1. An integrated equalization system based on a bidirectional LLC resonant converter, characterized in that, include: Energy storage unit group Series-connected in the same direction constitutes an energy storage unit string, and an energy storage unit group. Includes four energy storage units connected in series. to , ; The positive terminal of the output side of the bidirectional LLC resonant converter is connected to the energy storage unit. The positive and negative terminals are connected to the energy storage unit. The negative electrode; Energy storage unit group In the middle, energy storage unit The positive terminal is connected to the diode. The negative electrode is connected to the energy storage unit. positive and secondary windings heteronym, diode The positive terminal is connected to the secondary winding. Same-name terminal and diode The negative electrode, energy storage unit The negative terminal is connected to the energy storage unit. Positive electrode, diode positive electrode and diode The negative electrode, energy storage unit The negative terminal is connected to the energy storage unit. positive and secondary windings heteronym, diode The positive terminal is connected to the secondary winding. Same-name terminal and diode The negative electrode, energy storage unit The negative terminal is connected to the diode. The positive electrode; Secondary winding Secondary winding and primary winding Winded on the same magnetic core; n Primary winding The terminals with the same name are connected to each other, and the terminals with different names are connected to each other; primary winding The same-named terminal is connected to the secondary equalization winding. The same-named terminal, primary winding The opposite-named terminal is connected to the secondary equalization winding. Synonyms; Secondary equalization winding With the transmitting coil of the bidirectional LLC resonant converter coupling.

2. The integrated equalization system based on a bidirectional LLC resonant converter according to claim 1, characterized in that, The bidirectional LLC resonant converter includes: capacitance With DC source Parallel connection, DC source The positive terminal is connected to the switching transistor. Drain and switching transistor The drain and negative terminal are connected to the switching transistor. source and switch The source pole; Switching transistor The source is connected to the switching transistor. The drain of the circuit is connected to the resonant inductor. Connected to the transmitting coil The same terminal; switching transistor The source is connected to the switching transistor. The drain, and through the resonant capacitor Connected to the transmitting coil Equivalent terminal; Magnetizing inductor With transmitting coil in parallel; receiving coil With transmitting coil Coupling; Receiving coil The same terminal is connected to the switching transistor. source and switch The drain of the transistor is connected to the switching transistor at a different terminal. source and switch The drain electrode; Switching transistor Drain and switching transistor The drain is connected to the energy storage unit. The positive terminal of the switching transistor source and switch The source is connected to the energy storage unit. The negative terminal of the capacitor; C out Connected in series and parallel with the energy storage unit.

3. The integrated equalization system based on a bidirectional LLC resonant converter according to claim 2, characterized in that, Switching transistor To the switching transistor All are MOSFETs.

4. The integrated equalization system based on a bidirectional LLC resonant converter according to claim 2, characterized in that, The energy storage unit is a supercapacitor or a lithium battery.

5. An integrated equalization system based on a bidirectional LLC resonant converter according to claim 2, characterized in that, The LLC resonant tank in a bidirectional LLC resonant converter exhibits inductive impedance, as shown in the following formula: ； ； In the formula, The main resonant frequency, For switching transistors To the switching transistor The switching frequency, This is the secondary resonant frequency.

6. The integrated equalization system based on a bidirectional LLC resonant converter according to claim 2, characterized in that, Secondary winding voltage at both ends The voltage of a single energy storage unit is greater than that of a single energy storage unit. With the forward voltage drop of the diode The sum, the formula is as follows: ； ； In the formula, The total equivalent series resistance is... For secondary winding The serial number, For secondary winding Number of turns, For primary winding Number of turns, For secondary equalization winding Number of turns, For transmitting coil Number of turns, This represents the voltage gain of the bidirectional LLC resonant converter.

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