Bidirectional fast charging method and system based on high-power bidirectional inverter

Abstract

The invention discloses a bidirectional fast charging method and system based on a high-power bidirectional inverter, and relates to the technical field of charging and discharging, the high-power bidirectional inverter comprises a step-up and step-down switching module and an inversion rectification module, and the step-up and step-down switching module is connected with a battery pack and performs mode switching between a discharging mode and a charging mode; the method comprises the steps that in a discharging mode, direct current output by the battery pack is boosted to a preset voltage value through the boost and buck switching module, and the boosted direct current is converted into alternating current supplied to an external load through the inverter rectifier module; the inversion rectification module is an inversion circuit in the discharge mode; in the charging mode, alternating current input by an external power supply is rectified into direct current by the inversion and rectification module, the rectified direct current is reduced to a voltage value supplied to the battery pack through the boost and buck switching module, and the inversion and rectification module is a rectification circuit in the charging mode. The circuit design of the bidirectional inverter is simplified, the size of the bidirectional inverter is reduced, and the energy conversion efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of charging and discharging technology, and in particular to a bidirectional fast charging method and system based on a high-power bidirectional inverter. Background Art

[0002] In recent years, with the widespread application of portable energy storage products in outdoor activities, home emergencies and other scenarios, the demand for efficient, fast and reliable charging and discharging has increased. Traditional bidirectional inverters usually use independently designed charging circuits and discharging circuits to achieve these functions, that is, when charging, a dedicated charging module is used to convert the mains power into DC power to charge the battery pack, and when discharging, a separate discharge module is used to convert the DC power of the battery pack into AC power for external loads.

[0003] However, in the existing technical solutions, the charging circuit and the discharging circuit are two independent modules, which not only increases the complexity of the overall circuit and the number of components, but also makes the bidirectional charging circuit with the charging module and the discharging module larger in scale and occupies a large amount of physical space; in addition, since the two modules are respectively configured with their own rectification circuit and inverter circuit, the circuit is bulky and the cost is increased; at the same time, the switching between the charging and discharging modes is not flexible enough, especially when outward discharge is prohibited or restricted during the charging process. Even if it is allowed, it will significantly extend the charging time and affect the user experience.

[0004] Therefore, how to simplify the circuit design of the bidirectional inverter, reduce its size, and improve the energy conversion efficiency has become an urgent problem to be solved. Summary of the invention

[0005] In order to simplify the circuit design of the bidirectional inverter, reduce the volume of the bidirectional inverter, and improve the energy conversion efficiency, the present application provides a bidirectional fast charging method and system based on a high-power bidirectional inverter.

[0006] In the first aspect, the invention objective of the present application is achieved by adopting the following technical solutions: A bidirectional fast charging method based on a high-power bidirectional inverter, wherein the high-power bidirectional inverter comprises a boost-buck switching module and an inverter rectifier module, wherein the boost-buck switching module is connected to a battery pack and has boost and buck functions as well as mode switching between a discharge mode and a charging mode; the method comprises: In the discharge mode, the DC power output by the battery pack is boosted to a preset voltage value by the boost-buck switching module, and the boosted DC power is then converted into AC power for supplying an external load by the inverter rectifier module; the inverter rectifier module is used as an inverter circuit in the discharge mode; In the charging mode, the AC power input from the external power supply is rectified into DC power by the inverter rectifier module, and the rectified DC power is then stepped down to a voltage value supplied to the battery pack by the boost-buck switching module. The inverter rectifier module is used as a rectifier circuit in the charging mode.

[0007] By adopting the above technical scheme, the battery pack is a chargeable and dischargeable battery pack; the present application provides a bidirectional fast charging technology based on a high-power bidirectional inverter, which integrates the functions of a boost-buck switching module and an inverter rectifier module, which is different from the requirement of the prior art that both the charging function and the discharging function require independent rectifier circuits and inverter circuits, thereby greatly simplifying the circuit design of the bidirectional inverter, reducing the number of components, and reducing the volume of the bidirectional inverter, that is, saving space and improving the integration of the bidirectional inverter; by using a boost-buck switching module, during charging, AC power can be directly converted into DC power that is compatible with the battery pack, and during discharging, the DC power of the battery pack can be increased to a voltage level suitable for use by the external load. The energy conversion in the whole process is more direct and effective, which reduces energy loss and improves the charging and discharging efficiency of the system.

[0008] In a preferred example of the present application: the boost-buck conversion module includes a first-stage circuit for boosting the input voltage of the battery pack according to a fixed ratio and a second-stage circuit for adjusting the bus voltage to a preset stable value, and the inverter rectifier module includes a third-stage PFC inverter circuit for stabilizing the output of alternating current; In the discharge mode, the first-stage circuit performs an initial boost on the battery pack voltage, the second-stage circuit performs a secondary boost on the battery pack voltage and stabilizes the bus voltage to a preset voltage value, and the third-stage PFC inverter circuit completes the conversion of DC power to AC power; In the charging mode, the external power supply first passes through the third-stage PFC inverter circuit to perform PEFC rectification and boost processing, the second-stage circuit adjusts the charging voltage to a preset charging value, and the first-stage circuit steps down the voltage to charge the battery pack; the boost-buck conversion module switches to execute different charging modes based on the real-time voltage value of the battery pack.

[0009] By adopting the above technical solution and the combination of three-stage circuit design, efficient voltage conversion from battery pack to AC output or from external power supply to battery pack charging is achieved. In the discharge mode, the first and second stage circuits work together to ensure that the bus voltage reaches the preset value, which is beneficial to improve the efficiency of energy transmission; in the charging mode, the third stage circuit performs PFC rectification and boost processing, and the second stage circuit adjusts to the preset charging value, and then the first stage circuit steps down the voltage to charge the battery pack. The phased voltage processing method can avoid overcharging or undercharging, thereby protecting the battery life. Furthermore, the boost-buck conversion module switches to execute different charging modes based on the real-time voltage value of the battery pack, so that the bidirectional fast charging system can adaptively adjust to the optimal working state, thereby optimizing the charging and discharging process and maintaining efficient performance.

[0010] In a preferred example of the present application: the first-stage circuit includes a full-bridge LLC isolation boost circuit, the second-stage circuit includes a Boost-Buck bidirectional circuit, and the third-stage PFC inverter circuit is a totem-type PFC inverter circuit; The input side of the full-bridge LLC isolation boost circuit is also connected to a charging relay, which is used to output a rectified charging signal to the full-bridge LLC isolation boost circuit in a charging mode when the charger relay is closed; The output side of the third-stage PFC inverter circuit is also connected to a discharge relay. In the discharge mode, when the bus voltage is stabilized to a preset voltage value, the discharge relay is controlled to close to supply power to the external load.

[0011] By adopting the above technical scheme, the present invention introduces a three-stage circuit design, namely, the first-stage primary boost, the second-stage secondary boost and stable bus voltage, and the third-stage PFC inverter circuit, so as to more efficiently realize the conversion from DC to AC and the voltage adjustment during the charging process. In particular, the application of the Boost-Buck bidirectional circuit is introduced, so that the high-power bidirectional inverter can flexibly adjust the voltage while maintaining output stability, ensuring high efficiency in different working modes; the first-stage circuit adopts a full-bridge LLC isolation boost circuit to improve the voltage conversion efficiency and provide electrical isolation. In addition, the use of charging relays and dischargers can help to accurately control the signal transmission path, cut off unnecessary current paths when necessary, and eliminate potential charging and discharging safety risks; the application of totem PFC inverter circuit also further improves the response speed and flexibility of the two-way fast charging system.

[0012] In a preferred example of the present application, in the discharge mode, the full-bridge LLC isolation boost circuit is further connected to a feedforward pre-charging circuit, and the feedforward pre-charging circuit adopts a full-wave rectification operation mode when the battery pack voltage reaches a preset discharge interval; Real-time monitoring of the high-voltage DC bus voltage Vdc as a feedforward signal, during the rapid switching between heavy load and light load, the output voltage effective value Vrms fluctuation range of the high-power bidirectional inverter is controlled within ±5%; Real-time detection of instantaneous current and instantaneous voltage, calculation of instantaneous power and active power, and output to the preset user terminal; DCDC part: based on the resonance of the full-bridge LLC isolation boost circuit, the battery pack voltage is open-loop boosted to the high-voltage DC bus voltage Vdc according to a fixed boost ratio, wherein the high-voltage DC bus voltage Vdc is the smallest when the battery pack voltage is the lowest, and the high-voltage DC bus voltage Vdc reaches the maximum value when the battery voltage is the highest; DCAC part: Use SPWM algorithm to output PWM waveform to the third-stage PFC inverter circuit. The third-stage PFC inverter circuit inverts the high-voltage DC bus voltage Vdc into a sinusoidal AC voltage with an effective value of Vrms. Use PID algorithm to perform closed-loop control of the high-voltage DC bus voltage Vdc and the output voltage, so that the effective value of the output sinusoidal AC voltage is stable.

[0013] By adopting the above technical solution, when the battery pack voltage reaches the preset discharge range (for example, 40-50V), full-wave rectification is adopted to ensure a smooth transition when the system starts; by real-time monitoring of the high-voltage DC bus voltage Vdc and using it as a feedforward signal, during the rapid switching between heavy load and light load, the output voltage effective value Vrms fluctuation range of the high-power bidirectional inverter can be controlled within a very small fluctuation range, such as a fluctuation range of less than ±5%, and the dynamic response speed and stability of the system are improved through precise voltage control; and by detecting the instantaneous current and instantaneous voltage in the circuit, it is beneficial for users to perform more sophisticated energy management and fault diagnosis. The DCDC part performs resonant boost based on the resonance of the full-bridge LLC isolation boost circuit, ensuring the efficiency and stability of the boost process.

[0014] In a preferred example of the present application, in the charging mode, specifically includes: ACDC part: detects the grid-side input voltage in real time, and uses a phase-locked loop algorithm to detect the grid voltage phase and frequency; the third-level PFC inverter circuit rectifies and boosts the grid-side voltage to a high-voltage DC bus voltage Vdc based on the PFC algorithm and the grid voltage phase, and adjusts the grid-side current to be in the same frequency and phase as the grid-side voltage through a PID algorithm, thereby achieving a power factor close to 1; DCDC part: The high-voltage DC bus voltage Vdc is stepped down to the battery voltage through the resonance of the full-bridge LLC isolation boost circuit, and the voltage loop PID algorithm and the current loop PID algorithm are used for closed-loop control to charge the battery pack with constant current and constant voltage; The battery voltage is detected in real time, and the high-voltage DC bus voltage Vdc is adjusted according to a fixed ratio, so that the full-bridge LLC isolation boost circuit of the DCDC part is always in a resonant state.

[0015] By adopting the above technical solution, the grid-side input voltage is detected in real time and the phase and frequency of the grid voltage are detected by the phase-locked loop (PLL) algorithm, ensuring the precise synchronization of the inverter output with the grid. The third-level PFC inverter circuit rectifies and boosts the grid-side voltage to the high-voltage DC bus voltage Vdc based on the PFC algorithm and the grid voltage phase, and adjusts the grid-side current to be in the same frequency and phase as the grid-side voltage through the PID algorithm, achieving a power factor close to 1, which is beneficial to reducing reactive power loss. In the DCDC part, the high-voltage DC bus voltage Vdc is stepped down to the battery voltage through the resonant characteristics of the full-bridge LLC isolation boost circuit, and the voltage loop PID algorithm and the current loop PID algorithm are used for closed-loop control to realize constant current and constant voltage charging of the battery pack, and then the battery voltage is detected in real time, and the high-voltage DC bus voltage Vdc is adjusted according to a fixed ratio, so that the full-bridge LLC isolation boost circuit of the DCDC part is always in a resonant state, thereby ensuring that the system can maintain the best working state even when the battery voltage changes.

[0016] In a preferred example of the present application: the method further includes: Acquire real-time power interaction data between the target charging device and the power grid, wherein the real-time power interaction data includes power flow information; According to the power flow information, dynamically adjust the working mode of the bidirectional inverter to adapt to different charging or discharging requirements; Setting multiple power interaction threshold intervals to distinguish different levels of power input conditions or power output conditions; According to the current power interaction data and the corresponding power interaction threshold range, the optimization control of the fast charging or discharging process is achieved by adjusting the parameters of the bidirectional inverter.

[0017] By adopting the above technical solution, the working mode of the bidirectional inverter is dynamically adjusted based on the power flow information to quickly respond to changes in power demand. By setting multiple power interaction threshold intervals, different levels of power input conditions and power output conditions can be distinguished in different charging modes or different discharging modes, so as to make the most appropriate parameter adjustment according to the actual power interaction situation, which is beneficial to improving energy conversion efficiency.

[0018] In a preferred example of the present application, the dynamically adjusting the working mode of the bidirectional inverter includes: According to the power flow direction information, identifying the first significant power change point as the adjustment starting point; Determine a subsequent power adjustment period according to the preset response time and the first significant power change point; the maximum duration of the power adjustment period does not exceed the preset maximum time limit, and one or more working mode adjustments can be completed within the power adjustment period; Based on the changes in the power interaction data monitored in real time, determine whether a new power adjustment period needs to be started and select an appropriate working mode adjustment strategy.

[0019] By adopting the above technical solution, introducing significant power change points as adjustment starting points, preset response time and power adjustment period, multiple working mode conversions and a judgment mechanism based on real-time data, the response speed and flexibility of the two-way fast charging system are significantly improved; the working mode is adjusted according to real-time power interaction data to better adapt to the fluctuations in the power market and the complex environment of distributed energy systems. At the same time, each adjustment is based on significant power change points and real-time data, reducing the number of unnecessary adjustments, thereby reducing the wear and potential failure risks of the two-way fast charging system caused by frequent switching.

[0020] In a preferred example of the present application: the method further includes: When determining multiple power interaction threshold intervals, recording the setting time of each power interaction threshold interval; Monitor and determine whether the set time of each power interaction threshold interval exceeds the preset time limit; If the setting time of a certain power interaction threshold interval exceeds the preset time limit, the operating parameters within the power interaction threshold interval are optimized and adjusted, and optimization adjustment prompt information is output.

[0021] By adopting the above technical scheme, the power interaction threshold intervals are set correspondingly to the different charging mode intervals in the charging mode. For example, the different charging mode intervals of the battery pack include four stages: constant current charging stage, constant voltage charging stage, full charging stage and floating charging stage. The different discharge mode intervals of the battery pack include four stages: open circuit voltage stage, platform stage, polarization stage and discharge end stage. At least one power interaction threshold interval is set in the same charging mode interval or the same discharge mode interval. At the same time, it can also monitor and judge in real time whether each power interaction threshold interval has been running for too long in the working mode of the current power demand and is no longer applicable to the monitoring standard of the current optimal working state. Therefore, when the setting time of a certain power interaction threshold interval exceeds the preset time limit, the two-way fast charging system will automatically optimize and adjust the operating parameters within the interval. The dynamic adjustment mechanism enables the system to recalibrate to the optimal working state after a long period of operation. At the same time, by timely identifying and processing the timed power interaction threshold interval, the two-way fast charging system can avoid the delay problem caused by long-term non-update and maintain the continuity and stability of operation.

[0022] In a preferred example of the present application: the method further includes: According to the power flow direction information in the current real-time power interaction data, determining whether the current real-time power interaction data meets multiple set power interaction threshold intervals; If the current real-time power interaction data meets multiple set power interaction threshold intervals; then calculate the time difference between the minimum response time and the maximum response time of the multiple set power interaction threshold intervals; When the time difference of a certain set power interaction threshold interval meets the preset integration condition, the control strategy corresponding to the current real-time power interaction data is integrated into the power interaction threshold interval.

[0023] By adopting the above technical solution, introducing a multi-interval matching mechanism, a time difference calculation of the minimum and maximum response times, and an intelligent integration strategy based on preset integration conditions, the matching accuracy of the two-way fast charging system is significantly improved. Specifically, first, according to the power flow information in the current real-time power interaction data, it is judged whether the data meets multiple set power interaction threshold intervals, and the system can achieve accurate matching of the current power conditions; when the current real-time power interaction data meets multiple set power interaction threshold intervals, the time difference between the minimum response time and the maximum response time of these intervals is calculated, which not only considers the response speed, but also comprehensively evaluates the adaptability of different intervals; when the time difference of a certain set power interaction threshold interval meets the preset integration conditions, the control strategy corresponding to the current real-time power interaction data is integrated into the interval, and the two-way fast charging system can dynamically adjust its operating mode through the intelligent integration strategy to adapt to the changing power demand. At the same time, through the above multi-interval matching, time difference calculation and intelligent integration strategy, the system can more flexibly respond to various different power demands and environmental changes, enhancing the system's adaptability; the intelligent integration strategy is conducive to reducing the number of unnecessary working mode switching.

[0024] In the second aspect, the invention objective of the present application is achieved by adopting the following technical solutions: A bidirectional fast charging system based on a high-power bidirectional inverter is used to execute a bidirectional fast charging method based on a high-power bidirectional inverter as described above, and the system includes: The step-up and step-down switching module is connected to the battery pack and has the functions of step-up and step-down as well as the mode switching between discharge mode and charging mode; The inverter rectifier module is connected to the step-up / step-down switching module and is used as an inverter circuit in the discharge mode to convert the boosted DC power into AC power for supplying the external load; and is used as a rectifier circuit in the charging mode to rectify the AC power input from the external power supply into DC power; The system is configured to: In the discharge mode, the DC power output by the battery pack is boosted to a preset voltage value by the boost-buck switching module, and the boosted DC power is then converted into AC power for supplying an external load by the inverter rectifier module; In the charging mode, the AC power input from the external power supply is rectified into DC power by the inverter rectifier module, and the rectified DC power is then stepped down by the step-up and step-down switching module to a voltage value supplied to the battery pack.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. The bidirectional function integration, precise voltage control, stable power transmission, and optimized user experience and service quality of the boost and buck switching module and the inverter rectifier module significantly improve the energy conversion efficiency of the bidirectional fast charging system; 2. The introduction of mechanisms such as setting time record of power interaction threshold interval, timeout monitoring and judgment, automatic optimization adjustment, and optimization adjustment prompt information output significantly improves the response speed of the two-way fast charging system; 3. The introduction of a multi-interval matching mechanism, the time difference calculation of the minimum and maximum response times, and an intelligent integration strategy based on preset integration conditions significantly improves the matching accuracy, flexibility, adaptability, stability and reliability of the two-way fast charging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a connection diagram of a bidirectional inverter in a bidirectional fast charging method based on a high-power bidirectional inverter in an embodiment of the present application; Figure 2 It is a control flow chart of a discharge mode in a bidirectional fast charging method based on a high-power bidirectional inverter in one embodiment of the present application; Figure 3 This is a working flow chart of the DCAC part of the discharge mode in a bidirectional fast charging method based on a high-power bidirectional inverter in one embodiment of the present application; Figure 4 It is a control flow chart of a charging mode in a bidirectional fast charging method based on a high-power bidirectional inverter in one embodiment of the present application; Figure 5 This is a working flow chart of the ACDC part of the charging mode in a bidirectional fast charging method based on a high-power bidirectional inverter in one embodiment of the present application; Figure 6 This is a flow chart of a bidirectional fast charging method based on a high-power bidirectional inverter in one embodiment of the present application. DETAILED DESCRIPTION

[0027] The present application is further described in detail below in conjunction with the accompanying drawings.

[0028] In one embodiment, if Figure 1 As shown, the present application discloses a bidirectional fast charging method based on a high-power bidirectional inverter, wherein the high-power bidirectional inverter includes a main control module, a boost and buck switching module, an inverter rectifier module and a switch module; wherein the main control module includes a protective shell and a user touch control module for inputting control signals such as opening, closing, and emergency stop, and can be set as an intelligent terminal with a display screen; wherein the switch module includes a discharge relay and a charging relay. In this embodiment, the boost and buck switching module is connected to the battery pack and has boost and buck functions as well as mode switching between a discharge mode and a charging mode; specifically, the following steps are included: S1: In the discharge mode, the DC power output by the battery pack is boosted to a preset voltage value by the boost-buck switching module, and the boosted DC power is then converted into AC power for supplying an external load by the inverter rectifier module; the inverter rectifier module is used as an inverter circuit in the discharge mode.

[0029] In this embodiment, the boost-buck conversion module includes a first-stage circuit for boosting the battery pack input voltage at a fixed ratio and a second-stage circuit for adjusting the bus voltage to a preset stable value, and the inverter rectifier module includes a third-stage PFC inverter circuit for stabilizing the output of AC power.

[0030] Specifically, the first-stage circuit includes a full-bridge LLC isolated boost circuit, the second-stage circuit includes a Boost-Buck bidirectional circuit, and the third-stage PFC inverter circuit is a totem-type PFC inverter circuit; a charging relay is also connected to the input side of the full-bridge LLC isolated boost circuit, and when the charger relay is closed, it is used to output a rectified charging signal to the full-bridge LLC isolated boost circuit in the charging mode.

[0031] Furthermore, if Figure 2 As shown, it is a control flow chart of the discharge mode, which is also called the inverter discharge mode. In the discharge mode, it specifically includes: the full-bridge LLC isolation boost circuit is also connected to a feedforward pre-charging circuit, and the feedforward pre-charging circuit adopts a full-wave rectification operation mode when the battery pack voltage reaches a preset discharge interval (for example, 40-50V); because during the inverter output, the bus capacitor has a charge of 0 in the initial state, which is a short-circuit state. At this time, when the LLC reverse discharge is started, there is a large voltage spike on the low-voltage side MOS tube. To solve this problem, a feedforward pre-charging circuit is introduced, which greatly reduces the voltage spike at startup. When the battery voltage is 40-50V, this embodiment further adopts a full-wave rectification method. Compared with the full-bridge rectification circuit method that is more commonly used in the prior art, it greatly reduces the heating of the MOS tube (switch tube) and improves the efficiency of the bidirectional inverter.

[0032] The high-voltage DC bus voltage Vdc is monitored in real time as a feedforward signal. During the rapid switching between heavy load and light load, the output voltage effective value Vrms of the high-power bidirectional inverter is controlled within a fluctuation range of ±5%. The instantaneous current and instantaneous voltage are detected in real time, and the instantaneous power and active power are calculated and output to the preset user terminal for display and user control. Among them, Vrms is also called the inverter output effective value.

[0033] DCDC part: Based on the resonance of the full-bridge LLC isolation boost circuit, the battery pack voltage is boosted to the high-voltage DC bus voltage Vdc in an open loop according to a fixed boost ratio. When the battery pack voltage is the lowest, the high-voltage DC bus voltage Vdc is the smallest (the minimum value is Vrms*√2), and when the battery voltage is the highest, the high-voltage DC bus voltage Vdc reaches the maximum value (such as 250V); the fixed boost ratio is 1:4; DCAC part: Figure 3 As shown, the SPWM algorithm is used to output a PWM waveform to the third-stage PFC inverter circuit. The third-stage PFC inverter circuit inverts the high-voltage DC bus voltage Vdc into a sinusoidal AC voltage with an effective value of Vrms. The PID algorithm is used to perform closed-loop control on the high-voltage DC bus voltage Vdc and the output voltage, so that the effective value of the output sinusoidal AC voltage is stable.

[0034] S2: In charging mode, the AC power input from the external power supply is rectified into DC power by the inverter rectifier module, and the rectified DC power is then stepped down to the voltage value supplied to the battery pack by the boost-buck switching module. The inverter rectifier module is used as a rectifier circuit in charging mode.

[0035] In this embodiment, a discharge relay is further connected to the output side of the third-stage PFC inverter circuit. In the discharge mode, when the bus voltage is stabilized to a preset voltage value, the discharge relay is controlled to close to supply power to the external load.

[0036] Specifically, in the charging mode, the external power supply first passes through the third-stage PFC inverter circuit for PEFC rectification and boost processing, the second-stage circuit adjusts the charging voltage to a preset charging value, and the first-stage circuit steps down the voltage to charge the battery pack; the boost-buck conversion module switches to execute different charging modes based on the real-time voltage value of the battery pack.

[0037] Furthermore, if Figure 4 As shown, Figure 4 This is the control flow chart of the rectifier charging mode. In the charging mode, it specifically includes: ACDC section: Figure 5As shown, the grid-side input voltage is detected in real time, and the grid voltage phase and frequency are detected using a phase-locked loop algorithm; the third-level PFC inverter circuit rectifies and boosts the grid-side voltage to a high-voltage DC bus voltage Vdc based on the PFC algorithm and the grid voltage phase, and adjusts the grid-side current to have the same frequency and phase as the grid-side voltage through a PID algorithm to achieve a power factor close to 1.

[0038] DCDC part: The high-voltage DC bus voltage Vdc is stepped down to the battery voltage through the resonance of the full-bridge LLC isolation boost circuit, and the voltage loop PID algorithm and the current loop PID algorithm are used for closed-loop control to charge the battery pack with constant current and constant voltage.

[0039] The battery voltage is detected in real time, and the high-voltage DC bus voltage Vdc is adjusted according to a fixed ratio, so that the full-bridge LLC isolation boost circuit of the DCDC part is always in a resonant state.

[0040] Furthermore, the two-way fast charging system also includes a UPS part: If the grid fails during charging, the discharge mode will be activated immediately due to a phase-locked loop failure, and the switching time is less than or equal to half an AC cycle.

[0041] When the grid receives power in the discharge state, the phase-locked loop returns to normal, the bypass relay is opened, the inverter output is closed, and the grid relay is turned on to start the charging mode.

[0042] In one embodiment, if Figure 6 As shown, a bidirectional fast charging method based on a high-power bidirectional inverter also includes: S101: Acquire real-time power interaction data between a target charging device and a power grid, where the real-time power interaction data includes power flow information.

[0043] In this embodiment, the power flow information includes the current direction and voltage level; the real-time power interaction data includes but is not limited to power flow information, frequency, phase and other electrical parameters. The real-time power interaction data reflects the actual working status of the current power system and the actual changes in charging and discharging demand.

[0044] Specifically, high-precision sensors are integrated in the bidirectional inverter to monitor various electrical parameters on the grid side and the battery side in real time; the collected data is transmitted to the main control module (CPU) using a communication interface (such as CAN bus, Ethernet).

[0045] Furthermore, in scenarios where users need high-power output, multiple inverters can be connected in parallel to increase power output. The parallel communication method uses a Bluetooth interface to reduce the difficulty of connection for customers. In scenarios where users need large-capacity batteries, stacking can be implemented to increase battery capacity, that is, multiple battery packs are connected using stacking parallel technology. After the battery packs are stacked in parallel, the host (i.e., the main control module) will control each battery pack module to optimize the charging and discharging behavior. The charging and discharging modes after parallel connection are as follows: After the battery packs are stacked and connected in parallel, the charging mode is: after parallel connection, when the power difference between the two battery packs is relatively large, without connecting to an external charger, the two battery packs will be charged evenly, the battery pack with high power will charge the battery pack with low power, the battery pack with low power will turn on the internal DCDC module, and when connected to the grid for charging, it will give priority to charging the battery pack with low power, and when the voltages of the two battery packs are close. Multiple modules can be charged at the same time, and two or more battery packs can be charged at the same time. The voltage difference should be as small as possible, and according to the internal resistance of the battery cell, no overcurrent value can occur, generally within 1 volt.

[0046] After the battery packs are stacked and connected in parallel, the charging mode is: after parallel connection, when the power levels (voltage difference) of the two battery packs are relatively close, they can be discharged at the same time; when the power levels of the two battery packs are relatively high, the higher power level is discharged first, and when the power levels (voltage difference) are relatively close, they can be discharged at the same time; the voltage difference between two or more battery packs that can be discharged simultaneously is as small as possible, and according to the internal resistance of the battery cells, no overcurrent value can occur, generally within 1 volt.

[0047] S102: Dynamically adjust the working mode of the bidirectional inverter according to the power flow information to adapt to different charging or discharging requirements.

[0048] In this embodiment, after multiple battery packs are connected in parallel and multiple bidirectional inverters are connected in parallel, the working mode of the bidirectional inverter is appropriately adjusted based on charge balancing or discharge balancing technology to adapt to the charging or discharging requirements in different application scenarios: first, the power flow information is used to determine whether the system is in charging mode or discharging mode, as well as the specific power level. By analyzing the power flow, the bidirectional fast charging system can intelligently switch the working mode to adapt to different power requirements.

[0049] Specifically, the control unit determines the current operating status of the system (charging or discharging) according to the analyzed power flow information. Based on the judgment result, the control system sends instructions to the bidirectional inverter to adjust its operating mode (for example, switching from charging mode to discharging mode). At the same time, the preset safety restrictions are taken into account during the adjustment process, such as the maximum allowable current, voltage range, etc.

[0050] S103: Setting a plurality of power interaction threshold intervals to distinguish different levels of power input conditions or power output conditions.

[0051] In this embodiment, each battery pack is provided with a plurality of different power interaction threshold intervals, and for the same charging stage interval or the same discharging stage interval, a plurality of power interaction threshold intervals can be pre-set, such as the first power interaction threshold interval in the low power zone of the constant voltage charging stage, the second power interaction threshold interval in the medium power zone, and the second power interaction threshold interval in the high power zone; different power reference values ​​can be set for different charging and discharging stage intervals to divide the current interaction threshold intervals. Each interval represents a power level within a certain range; by setting a plurality of power interaction threshold intervals, refined management of the power interaction process can be achieved.

[0052] S104: According to the current power interaction data and the corresponding power interaction threshold range, the optimization control of the fast charging or discharging process is achieved by adjusting the parameters of the bidirectional inverter.

[0053] In this embodiment, according to the current power interaction data and the threshold interval to which it belongs, the key parameters of the bidirectional inverter (such as frequency, phase, duty cycle, etc.) are dynamically adjusted to achieve a fast and efficient charging or discharging process. After the current power interaction data is identified as belonging to a certain power interaction threshold interval, the control system calls the corresponding operation strategy. According to the selected operation strategy, the control system adjusts the key parameters of the bidirectional inverter, such as the frequency and duty cycle of the PWM waveform, the output voltage of the inverter, etc.

[0054] Furthermore, for setting the power interaction threshold interval, this embodiment also includes: S111: When determining a plurality of power interaction threshold intervals, recording a setting time of each power interaction threshold interval.

[0055] Specifically, in order to analyze and monitor the battery health of each battery pack, and observe its performance during the charging and discharging processes, and promptly discover abnormal charging and abnormal discharging behaviors, the present application sets a time limit for each power interaction threshold interval of the same battery pack in the same working mode, that is, records the setting time of each power interaction threshold interval, ensures that the system can track the validity period and usage of each interval, and facilitates subsequent time management and optimization adjustments; establishes a database for storing power interaction threshold intervals in the control system, assigns a unique identifier to each power interaction threshold interval, and whenever a new power interaction threshold interval is created, adds the current timestamp to its corresponding record as the setting time of the interval.

[0056] By comparing the power parameters and the change process in each power interaction threshold interval, it is convenient to set an optimal charging balance control parameter group and discharging balance control parameter group based on the subsequent power interaction data changes in each power interaction threshold interval.

[0057] Furthermore, with the long-term use of the battery pack, in order to make the setting of the power interaction threshold interval more in line with the battery health of the current battery pack and track the charging and discharging performance of the battery pack, the setting timestamp of the power interaction threshold interval can also be adaptively modified. When a power interaction threshold interval is modified, the corresponding timestamp is updated to reflect the latest setting time.

[0058] S112: Monitor and determine whether the set time of each power interaction threshold interval exceeds a preset time limit.

[0059] Specifically, the maximum allowed duration of each power interaction threshold interval is pre-set (for example, 15 minutes), and a periodic task is set (such as once every hour). The control system automatically traverses the records of all power interaction threshold intervals to check whether their set time exceeds the preset time limit.

[0060] S113: If the setting time of a certain power interaction threshold interval exceeds the preset time limit, the operating parameters within the power interaction threshold interval are optimized and adjusted, and optimization adjustment prompt information is output.

[0061] Specifically, a set of parameter optimization algorithms is set to evaluate and adjust key operating parameters within the power interaction threshold interval, such as voltage level, current limit, frequency, etc. When it is detected that the setting time of a power interaction threshold interval exceeds the preset time limit, the optimization algorithm is started to calculate the new optimal parameter configuration, and these configurations are applied to the corresponding power interaction threshold interval, and optimization adjustment prompt information is created, including the affected battery pack, the corresponding power interaction threshold interval, the comparison of parameters before and after adjustment, the expected performance improvement, etc. The optimization adjustment prompt information is output to users or administrators through multiple channels (such as display screens).

[0062] In one embodiment, in step S102, dynamically adjusting the working mode of the bidirectional inverter specifically includes: S1021: According to the power flow direction information, identify the first significant power change point as an adjustment starting point.

[0063] Specifically, a significant power change threshold is associated with each power interaction threshold interval, and when the power change in a certain power flow information exceeds the corresponding significant power change threshold, the point is recorded as a significant power change point.

[0064] S1022: Determine a subsequent power adjustment period based on the preset response time and the first significant power change point; the maximum duration of the power adjustment period does not exceed the preset maximum time limit, and one or more working mode adjustments can be completed within the power adjustment period.

[0065] Specifically, the response time refers to the time required from identifying a significant power change point to starting to adjust the working mode; based on the preset response time and significant power change point, one or more power adjustment periods are determined, and the maximum duration of each power adjustment period is subject to the preset maximum time limit. While ensuring the efficiency of the adjustment process, the performance of the power adjustment is fed back to the user, and the changes in charging parameters after the power adjustment are observed in a timely manner; if multiple adjustments are required, subsequent power adjustment periods can be determined according to actual needs, and multiple power adjustment periods can be set. At the same time, parameter monitoring based on a time interval can be established to avoid short-term excessive current or voltage from causing misdetection of the control strategy, thereby improving the accuracy of data monitoring. The maximum duration of each period shall not exceed the preset maximum time limit.

[0066] S1023: Based on the changes in the power interaction data monitored in real time, determine whether a new power adjustment period needs to be started and select an appropriate working mode adjustment strategy.

[0067] In this embodiment, within the duration of a power interaction threshold interval, the changes in power interaction data are monitored in real time to evaluate whether the current working mode is still suitable for the current power demand. If further adjustment is found to be needed, a new power adjustment period is started and the most appropriate working mode adjustment strategy is selected.

[0068] In one embodiment, a bidirectional fast charging method based on a high-power bidirectional inverter further includes: S121: judging whether the current real-time power interaction data conforms to a plurality of set power interaction threshold intervals according to the power flow direction information in the current real-time power interaction data.

[0069] In this embodiment, the current power interaction data, including power flow information, is collected and analyzed in real time, and the real-time power interaction data is compared with multiple preset power interaction threshold intervals to check whether it falls within the range of a certain power interaction threshold interval. If the real-time power interaction data satisfies multiple power interaction threshold intervals at the same time, these intervals and their corresponding parameters are recorded.

[0070] S122: If the current real-time power interaction data satisfies multiple set power interaction threshold intervals, calculate the time difference between the minimum response time and the maximum response time of the multiple set power interaction threshold intervals.

[0071] In this embodiment, when the real-time power interaction data satisfies multiple power interaction threshold intervals at the same time, the time difference between the minimum response time and the maximum response time between the current real-time power interaction data and the multiple power interaction threshold intervals is calculated; each power interaction threshold interval includes a minimum time value and a maximum time value to time limit the power interaction threshold interval.

[0072] Specifically, the time difference between the minimum response time and the maximum response time of each interval is calculated. By calculating the time difference, the system can more accurately evaluate the adaptability of different intervals to the current power demand and select the most appropriate operation strategy. In this embodiment, each power interaction threshold interval is associated with a preset operation strategy.

[0073] S123: When the time difference of a certain set power interaction threshold interval meets a preset integration condition, the control strategy corresponding to the current real-time power interaction data is integrated into the power interaction threshold interval.

[0074] In this embodiment, the pre-set integration conditions include the time difference being less than a certain threshold, the shortest response time, etc.; it is checked whether the calculated time difference meets the preset integration conditions. If the integration conditions are met, the control strategy corresponding to the current real-time power interaction data is integrated into the corresponding power interaction threshold interval. According to the integrated strategy, the relevant configuration in the control system is updated to ensure that the new operation mode takes effect immediately.

[0075] For example, in a smart charging station, a high-power bidirectional inverter is used to connect the power grid and multiple electric vehicle (EV) charging piles. The charging station is equipped with an advanced power management system that can monitor power interaction data in real time and dynamically adjust the working mode according to different power demands; assuming that three power interaction threshold intervals are preset: Low power zone: 0-50kW, suitable for charging a small number of vehicles or during low load periods at night.

[0076] Medium power area: 50-150kW, suitable for regular peak hours.

[0077] High power zone: above 150kW, suitable for fast charging needs or during special events.

[0078] At 3 p.m. on a weekday, the control system detects that there are three electric vehicles currently charging with a total power of 80 kW. At this time, the control system determines that the current real-time power interaction data falls in the "medium power zone".

[0079] For each qualified power interaction threshold interval, determine its minimum response time and maximum response time, for example: Low power zone: minimum response time is 5 seconds, maximum response time is 30 seconds.

[0080] Medium power zone: minimum response time is 2 seconds, maximum response time is 10 seconds.

[0081] High power area: minimum response time is 1 second, maximum response time is 5 seconds.

[0082] Time difference calculation: Calculate the time difference between the minimum response time and the maximum response time of each power interaction threshold interval: Low power zone: 30 seconds - 5 seconds = 25 seconds.

[0083] Medium power zone: 10 seconds - 2 seconds = 8 seconds.

[0084] High power area: 5 seconds - 1 second = 4 seconds.

[0085] The control system finds that the current real-time power interaction data meets the "low power zone" and "medium power zone", but does not meet the "high power zone". Therefore, it calculates the time difference between the minimum and maximum response times of these two intervals to be 25 seconds and 8 seconds respectively; pre-set integration conditions, such as the time difference is less than a certain threshold (such as 10 seconds), then the control strategy corresponding to the current real-time power interaction data is integrated into the corresponding power interaction threshold interval, and the calculated time difference is checked to see if it meets the preset integration conditions. In this case, the time difference in the "medium power zone" is 8 seconds, which meets the integration conditions, and the control strategy corresponding to the current real-time power interaction data is integrated into the "medium power zone", and the relevant configuration in the control system is updated; generate and output integration prompt information to notify staff about parameter adjustments, for example: "The system has automatically switched to the medium power zone to optimize the current charging efficiency." In the above case, since the time difference in the "medium power zone" meets the integration conditions, the control system decides to use the operating parameters of the "medium power zone" for adjustment to ensure that the system is in the optimal working state.

[0086] It should be understood that the serial numbers of the steps in the above embodiments do not imply a sequence of execution. The execution sequence of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0087] In one embodiment, a bidirectional fast charging system based on a high-power bidirectional inverter is provided, and the bidirectional fast charging system based on the high-power bidirectional inverter corresponds to a bidirectional fast charging method based on a high-power bidirectional inverter in the above-mentioned embodiment.

[0088] A bidirectional fast charging system based on a high-power bidirectional inverter includes a step-up and step-down switching module and an inverter rectifier module. The detailed description of each functional module is as follows: The step-up and step-down switching module is connected to the battery pack and has the functions of step-up and step-down as well as the mode switching between discharge mode and charging mode; The inverter rectifier module is connected to the step-up and step-down switching module and is used as an inverter circuit in the discharge mode to convert the boosted DC power into AC power for supplying the external load; it is used as a rectifier circuit in the charging mode to rectify the AC power input from the external power supply into DC power; The system is configured as: In the discharge mode, the DC power output by the battery pack is boosted to a preset voltage value by the boost-buck switching module, and the boosted DC power is then converted into AC power for supplying external loads by the inverter rectifier module; In charging mode, the AC power input from the external power supply is rectified into DC power by the inverter rectifier module, and the rectified DC power is then stepped down to the voltage value supplied to the battery pack by the boost and buck switching module.

[0089] Optionally, a bidirectional fast charging system based on a high-power bidirectional inverter also includes a main control module and a switch module; the main control module includes a protective shell and a user touch control module for inputting control signals such as start, stop, and emergency stop, and can be set as an intelligent terminal with a display screen; the switch module includes a discharge relay and a charging relay.

[0090] For the specific definition of a bidirectional fast charging system based on a high-power bidirectional inverter, please refer to the definition of a bidirectional fast charging method based on a high-power bidirectional inverter in the above text, which will not be repeated here; each module in the above-mentioned bidirectional fast charging system based on a high-power bidirectional inverter can be fully or partially implemented by software, hardware and a combination thereof; each of the above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the corresponding operations of each of the above modules.

[0091] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0092] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments may still be modified, or some of the features thereof may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A bidirectional fast charging method based on a high-power bidirectional inverter, characterized in that: The high-power bidirectional inverter includes a boost-buck switching module and an inverter rectifier module. The boost-buck switching module is connected to a battery pack and has boost and buck functions as well as mode switching between a discharge mode and a charging mode. The method includes: In the discharge mode, the DC power output by the battery pack is boosted to a preset voltage value by the boost-buck switching module, and the boosted DC power is then converted into AC power for supplying an external load by the inverter rectifier module; the inverter rectifier module is used as an inverter circuit in the discharge mode; In the charging mode, the AC power input from the external power supply is rectified into DC power by the inverter rectifier module, and the rectified DC power is then stepped down to a voltage value supplied to the battery pack by the boost-buck switching module. The inverter rectifier module is used as a rectifier circuit in the charging mode.

2. According to claim 1, a bidirectional fast charging method based on a high-power bidirectional inverter is characterized in that: The step-up / step-down conversion module includes a first-stage circuit for stepping up the input voltage of the battery pack according to a fixed ratio and a second-stage circuit for adjusting the bus voltage to a preset stable value, and the inverter rectifier module includes a third-stage PFC inverter circuit for stabilizing the output of alternating current; In the discharge mode, the first-stage circuit performs an initial boost on the battery pack voltage, the second-stage circuit performs a secondary boost on the battery pack voltage and stabilizes the bus voltage to a preset voltage value, and the third-stage PFC inverter circuit completes the conversion of DC power to AC power; In the charging mode, the external power supply first passes through the third-stage PFC inverter circuit to perform PEFC rectification and boost processing, the second-stage circuit adjusts the charging voltage to a preset charging value, and the first-stage circuit steps down the voltage to charge the battery pack; the boost-buck conversion module switches to execute different charging modes based on the real-time voltage value of the battery pack.

3. According to claim 2, a bidirectional fast charging method based on a high-power bidirectional inverter is characterized in that: The first-stage circuit includes a full-bridge LLC isolation boost circuit, the second-stage circuit includes a Boost-Buck bidirectional circuit, and the third-stage PFC inverter circuit is a totem-type PFC inverter circuit; The input side of the full-bridge LLC isolation boost circuit is also connected to a charging relay, which is used to output a rectified charging signal to the full-bridge LLC isolation boost circuit in a charging mode when the charger relay is closed; The output side of the third-stage PFC inverter circuit is also connected to a discharge relay. In the discharge mode, when the bus voltage is stabilized to a preset voltage value, the discharge relay is controlled to close to supply power to the external load.

4. According to claim 3, a bidirectional fast charging method based on a high-power bidirectional inverter is characterized in that: In the discharge mode, specifically, the full-bridge LLC isolation boost circuit is further connected to a feedforward pre-charging circuit, and the feedforward pre-charging circuit adopts a full-wave rectification operation mode when the battery pack voltage reaches a preset discharge interval; Real-time monitoring of the high-voltage DC bus voltage Vdc as a feedforward signal, during the rapid switching between heavy load and light load, the output voltage effective value Vrms fluctuation range of the high-power bidirectional inverter is controlled within ±5%; Real-time detection of instantaneous current and instantaneous voltage, calculation of instantaneous power and active power, and output to the preset user terminal; DCDC part: based on the resonance of the full-bridge LLC isolation boost circuit, the battery pack voltage is open-loop boosted to the high-voltage DC bus voltage Vdc according to a fixed boost ratio, wherein the high-voltage DC bus voltage Vdc is the smallest when the battery pack voltage is the lowest, and the high-voltage DC bus voltage Vdc reaches the maximum value when the battery voltage is the highest; DCAC part: Use SPWM algorithm to output PWM waveform to the third-stage PFC inverter circuit. The third-stage PFC inverter circuit inverts the high-voltage DC bus voltage Vdc into a sinusoidal AC voltage with an effective value of Vrms. Use PID algorithm to perform closed-loop control of the high-voltage DC bus voltage Vdc and the output voltage, so that the effective value of the output sinusoidal AC voltage is stable.

5. A bidirectional fast charging method based on a high-power bidirectional inverter according to claim 3 or 4, characterized in that: In charging mode, it specifically includes: ACDC part: detects the grid-side input voltage in real time, and uses a phase-locked loop algorithm to detect the grid voltage phase and frequency; the third-level PFC inverter circuit rectifies and boosts the grid-side voltage to a high-voltage DC bus voltage Vdc based on the PFC algorithm and the grid voltage phase, and adjusts the grid-side current to be in the same frequency and phase as the grid-side voltage through a PID algorithm, thereby achieving a power factor close to 1; DCDC part: The high-voltage DC bus voltage Vdc is stepped down to the battery voltage through the resonance of the full-bridge LLC isolation boost circuit, and the voltage loop PID algorithm and the current loop PID algorithm are used for closed-loop control to charge the battery pack with constant current and constant voltage; The battery voltage is detected in real time, and the high-voltage DC bus voltage Vdc is adjusted according to a fixed ratio, so that the full-bridge LLC isolation boost circuit of the DCDC part is always in a resonant state.

6. According to claim 1, a bidirectional fast charging method based on a high-power bidirectional inverter is characterized in that: The method further comprises: Acquire real-time power interaction data between the target charging device and the power grid, wherein the real-time power interaction data includes power flow information; According to the power flow information, dynamically adjust the working mode of the bidirectional inverter to adapt to different charging or discharging requirements; Setting multiple power interaction threshold intervals to distinguish different levels of power input conditions or power output conditions; According to the current power interaction data and the corresponding power interaction threshold range, the optimization control of the fast charging or discharging process is achieved by adjusting the parameters of the bidirectional inverter.

7. A bidirectional fast charging method based on a high-power bidirectional inverter according to claim 6, characterized in that: The dynamically adjusting the working mode of the bidirectional inverter includes: According to the power flow direction information, identifying the first significant power change point as the adjustment starting point; Determine a subsequent power adjustment period according to the preset response time and the first significant power change point; the maximum duration of the power adjustment period does not exceed the preset maximum time limit, and one or more working mode adjustments can be completed within the power adjustment period; Based on the changes in the power interaction data monitored in real time, determine whether a new power adjustment period needs to be started and select an appropriate working mode adjustment strategy.

8. The bidirectional fast charging method based on a high-power bidirectional inverter according to claim 6 is characterized in that: The method further comprises: When determining multiple power interaction threshold intervals, recording the setting time of each power interaction threshold interval; Monitor and determine whether the set time of each power interaction threshold interval exceeds the preset time limit; If the setting time of a certain power interaction threshold interval exceeds the preset time limit, the operating parameters within the power interaction threshold interval are optimized and adjusted, and optimization adjustment prompt information is output.

9. The bidirectional fast charging method based on a high-power bidirectional inverter according to claim 6 is characterized in that: The method further comprises: According to the power flow direction information in the current real-time power interaction data, determining whether the current real-time power interaction data meets multiple set power interaction threshold intervals; If the current real-time power interaction data meets multiple set power interaction threshold intervals; then calculate the time difference between the minimum response time and the maximum response time of the multiple set power interaction threshold intervals; When the time difference of a certain set power interaction threshold interval meets the preset integration condition, the control strategy corresponding to the current real-time power interaction data is integrated into the power interaction threshold interval.

10. A bidirectional fast charging system based on a high-power bidirectional inverter, characterized in that: Used to execute a bidirectional fast charging method based on a high-power bidirectional inverter as described in any one of claims 1 to 9, the system comprises: The step-up and step-down switching module is connected to the battery pack and has the functions of step-up and step-down as well as the mode switching between discharge mode and charging mode; The inverter rectifier module is connected to the step-up / step-down switching module and is used as an inverter circuit in the discharge mode to convert the boosted DC power into AC power for supplying the external load; and is used as a rectifier circuit in the charging mode to rectify the AC power input from the external power supply into DC power; The system is configured to: In the discharge mode, the DC power output by the battery pack is boosted to a preset voltage value by the boost-buck switching module, and the boosted DC power is then converted into AC power for supplying an external load by the inverter rectifier module; In the charging mode, the AC power input from the external power supply is rectified into DC power by the inverter rectifier module, and the rectified DC power is then stepped down by the step-up and step-down switching module to a voltage value supplied to the battery pack.

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