Compensation method and compensation system of bidirectional power supply

Abstract

The embodiment of the invention discloses a compensation method and system for a bidirectional power supply, and the method comprises the steps: A, collecting the working data of a main battery and an auxiliary battery in real time, transmitting the working data to a controller, and enabling the controller to judge a current to-be-executed working mode according to the calculated power and the electric quantity of the batteries; b, when the forward mode is started, the controller controls the DAB converter to adjust the phase shift angle according to the calculated forward phase shift compensation amount, and after a corresponding transmission path is switched, the main battery supplies power to the auxiliary battery; c, when the reverse mode is started, the controller controls the DAB converter to adjust the phase shift angle according to the calculated reverse phase shift angle, and after the corresponding transmission path is switched, the auxiliary battery supplies power to the main battery; and step D, when the standby mode is started, the controller sets the phase shift angle of the DAB converter to be 0 degree, and the step A is returned after waiting for a preset time. The problem of insufficient output power caused by limitation of an existing single power battery is solved.

Description

Technical Field

[0001] This invention relates to the field of charging technology, and in particular to a bidirectional power supply compensation method and system. Background Technology

[0002] In the field of new energy vehicles, the power battery system is a key component that provides core electrical energy for the vehicle's drive system. Its performance directly determines the vehicle's power output, driving experience, and applicable scenarios. Existing power battery systems generally adopt a single power battery configuration. This structure can basically meet the power supply needs of the drive system under normal auxiliary battery conditions such as constant speed driving.

[0003] However, existing single-battery systems, in order to balance energy density and economic efficiency under normal operating conditions, often struggle to meet the instantaneous power demands of large auxiliary battery scenarios. Simply increasing the power density of the battery leads to increased battery costs and decreased energy utilization; maintaining the current configuration fails to overcome the power bottleneck in large auxiliary battery scenarios. This contradiction between "economic efficiency under normal operating conditions" and "power performance in large auxiliary battery scenarios" lacks an effective solution and has become a core technical pain point restricting the overall performance upgrade and expansion of applicable scenarios for new energy vehicles. A power battery system optimization solution that can specifically address this contradiction is urgently needed.

[0004] Furthermore, in actual use, vehicles often face scenarios requiring significant auxiliary battery output, such as acceleration for overtaking, hill climbing, and full-load driving. In these situations, a single power battery, limited by its own power density and instantaneous discharge capacity, is prone to insufficient output power. To balance energy density and economy under normal operating conditions, a single power battery system often struggles to meet the instantaneous power demands of scenarios requiring a large auxiliary battery. This not only results in insufficient drive power for the vehicle's drive system but also causes sluggish power response, reduced acceleration performance, and even limits the vehicle's auxiliary battery capacity and adaptability to complex road conditions. The inability to balance economy under normal operating conditions with power performance under large auxiliary battery scenarios becomes a significant factor restricting the overall performance improvement of new energy vehicles.

[0005] Therefore, the existing technology still needs to be improved and enhanced. Summary of the Invention

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a bidirectional power supply compensation method and system to solve the problem of insufficient output power caused by the limitation of existing single power batteries.

[0007] This invention provides a bidirectional power supply compensation method, comprising: Step A: Collect the working data of the main battery and the auxiliary battery in real time and transmit it to the controller. The controller determines the current working mode to be executed based on the calculated power and battery level. Step B: When starting the forward mode, the controller controls the DAB converter to adjust the phase shift angle according to the calculated forward phase shift compensation amount, and then switches the corresponding transmission path to supply power from the main battery to the auxiliary battery. Step C: When starting the reverse mode, the controller controls the DAB converter to adjust the phase shift angle according to the calculated reverse phase shift angle, and after switching the corresponding transmission path, the auxiliary battery supplies power to the main battery. Step D: When starting standby mode, the controller sets the phase shift angle of the DAB converter to 0°, waits for a preset time, and then returns to step A.

[0008] Optionally, the bidirectional power supply compensation method further includes step A0 before step A: starting the initialization mode, performing hardware self-test and initial parameter configuration.

[0009] Optionally, in the bidirectional power supply compensation method, in step A1, the hardware self-test includes: self-testing the status of each sensor, drive module, DAB converter, and each relay upon power-on; and battery and parameter initialization.

[0010] Optionally, in the bidirectional power supply compensation method, in step A, the controller calculates the main power of the main battery based on the voltage and current of the main battery, calculates the power of the secondary battery based on the voltage and current of the secondary battery, and calculates the current battery capacity of the secondary battery through ampere-hour integration and open-circuit voltage correction.

[0011] Optionally, in the bidirectional power supply compensation method, step A, the step of determining the compensation mode to be executed specifically includes: Step A1: Determine whether the main power of the main battery is greater than or equal to the power of the secondary battery, and whether the battery capacity of the main battery is greater than or equal to the lower threshold. If yes, start the forward mode; otherwise, proceed to step A2. Step A2: Determine whether the power of the secondary battery is greater than the main power of the primary battery, and whether the battery capacity of the secondary battery is greater than or equal to the lower threshold. If yes, start the reverse mode; otherwise, proceed to step D.

[0012] Optionally, in the bidirectional power supply compensation method, step B specifically includes: Step B1: When starting the forward mode, calculate the forward phase shift compensation amount; Step B2: The drive module outputs a corresponding trigger signal based on the positive phase shift compensation amount to control the DAB converter to adjust the phase shift angle so that the main battery supplies power to the auxiliary battery. Step B3: Determine whether the power change is less than or equal to zero or the main battery's charge is less than the lower threshold. If so, exit the positive mode.

[0013] Optionally, in the bidirectional power supply compensation method, step C specifically includes: Step C1: Start reverse mode, read the target current for reverse charging, and calculate the reverse phase shift angle; Step C2: The drive module outputs a corresponding reverse trigger signal according to the reverse phase shift angle, controls the DAB converter to adjust the phase shift angle, so that the auxiliary battery supplies power to the main battery; Step C3: Determine whether the secondary battery's charge level is below the lower threshold or if there is an abnormal charging power. If so, exit the reverse mode.

[0014] A second aspect of the invention provides a compensation system for implementing the bidirectional power supply compensation method, comprising a main battery and a secondary battery, and further comprising a controller, a DAB converter, a data acquisition switch circuit and an interface circuit. The acquisition switch circuit collects the working data of the main battery and the auxiliary battery in real time and transmits it to the controller. The controller determines the current operating mode to be executed based on the calculated power and battery level. When the forward mode is started, the controller controls the DAB converter to adjust the phase shift angle according to the calculated forward phase shift compensation amount, and the acquisition switching circuit switches the corresponding transmission path to enable the main battery to supply power to the auxiliary battery. When the reverse mode is activated, the controller controls the DAB converter to adjust the phase shift angle according to the calculated reverse phase shift angle, and the acquisition switching circuit switches the corresponding transmission path to enable the auxiliary battery to supply power to the main battery. When the standby mode is started, the controller sets the phase shift angle of the DAB converter to 0° and waits for a preset time before returning to the working mode for judgment.

[0015] Optionally, in the compensation system, the acquisition switch circuit includes several sensors for detecting corresponding current and voltage, several relays for switching transmission paths, a drive module for amplifying the drive signal output by the controller, and a voltage detection module for acquiring the voltages of the main battery and the auxiliary battery.

[0016] Optionally, in the compensation system, the DAB converter is used for DC-to-DC boost and buck conversion, and consists of two interleaved primary-side full-bridge and secondary-side full-bridge. The trigger signal output by the drive module controls the phase difference between the primary-side full-bridge and the secondary-side full-bridge.

[0017] The technical solution provided in this invention includes a bidirectional power supply compensation method comprising: Step A, real-time acquisition of operating data from the main battery and auxiliary battery and transmission to the controller, which determines the current operating mode to be executed based on the calculated power and battery charge; Step B, when starting the forward mode, the controller controls the DAB converter to adjust the phase shift angle based on the calculated forward phase shift compensation amount, switches the corresponding transmission path, and then supplies power from the main battery to the auxiliary battery; Step C, when starting the reverse mode, the controller controls the DAB converter to adjust the phase shift angle based on the calculated reverse phase shift angle, switches the corresponding transmission path, and then supplies power from the auxiliary battery to the main battery; Step D, when starting the standby mode, the controller sets the phase shift angle of the DAB converter to 0°, waits for a preset time, and then returns to Step A. This solves the problem of insufficient output power caused by the limitation of a single power battery in existing systems. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the circuit structure of the compensation system in an embodiment of the present invention.

[0019] Figure 2 This is a flowchart of the bidirectional power supply compensation method in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It is readily understood that relational terms such as "first" and "second" are used merely to distinguish one entity, operation, or direction from another, without requiring or implying any actual relationship or order between these entities, operations, or directions. The directional terms such as "up," "down," "left," "right," "front," "back," "front," "back," "top," and "bottom," mentioned or possibly used in this specification, are defined relative to the constructions shown in the accompanying drawings. They are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be construed as restrictive. In the following description, various parameters and components are described for embodiments of different constructions. These specific parameters and components are merely examples and do not limit the embodiments of this application.

[0022] Please see Figure 1This invention provides a compensation system for implementing a bidirectional power supply compensation method. The compensation system includes a controller 10, a DAB converter, a main battery (MP), a secondary battery (AP), a data acquisition switch circuit, and an interface circuit 20. The controller 10 is connected to the DAB converter and the data acquisition switch circuit, and the DAB converter is connected to the main battery (MP), the secondary battery (AP), and the data acquisition switch circuit. The interface circuit 20 is connected to the data acquisition switch circuit and the secondary battery. The data acquisition switch circuit collects the operating data of the main battery (MP) and the secondary battery (AP) in real time and transmits it to the controller 10. The controller 10 determines the current operating mode to be executed based on the calculated power and battery charge. When the forward mode is started, the controller controls the DAB converter to adjust the phase shift angle according to the calculated forward phase shift compensation amount, and the data acquisition switch circuit switches the corresponding transmission path to supply power from the main battery to the secondary battery. When the reverse mode is started, the controller controls the DAB converter to adjust the phase shift angle according to the calculated reverse phase shift angle, and the data acquisition switch circuit switches the corresponding transmission path to supply power from the secondary battery to the main battery. When the standby mode is started, the controller sets the phase shift angle of the DAB converter to 0°, waits for a preset time, and then returns to the operating mode determination.

[0023] The dual-battery configuration provided in this embodiment can select the appropriate operating mode based on the current battery charge and power. By adjusting the phase shift angle of the DAB converter, the charging power transmission path is changed, enabling the main battery to supply power to the auxiliary battery in a forward direction. When the main battery cannot meet the power output requirements of the auxiliary battery, the auxiliary battery supplies power to the main battery to satisfy the power output needs of the auxiliary battery. This solves the problem that a single power battery is limited by its own power density limit, instantaneous high-current discharge capacity, and thermal management constraints, making it difficult to quickly output the peak power required by the drive system and easily resulting in insufficient output power.

[0024] In this embodiment, the acquisition switch circuit includes several sensors for detecting corresponding current and voltage, several relays for switching transmission paths, a drive module 30 for amplifying the drive signal output by the controller, and a voltage detection module for acquiring the voltage of the main battery and the auxiliary battery.

[0025] The sensors include: a main current sensor HM (Hall_main) for collecting the main-side current at the main battery output; an auxiliary current sensor HA (Hall_auxiliary) for collecting the auxiliary-side current in the loop from the main battery MP to the DAB converter; and a secondary battery current sensor HT (Hall_total) for collecting the secondary battery current. The DAB converter acts as an isolation mechanism; HA does not directly collect the secondary battery current. The secondary battery current collection is hidden, and is essentially represented by the sum of the currents collected by HA and HM.

[0026] Each relay functions as a switch, including: negative DC relay DCR- (D_Charge-Relay), positive DC relay DCR+ (D_Charge+Relay), auxiliary relay AR (auxiliary relay), pre-charge relay PCR (Pre-Chr Relay) at the secondary battery terminal, main relay MRA+ (Main+ Relay A) at the secondary battery terminal, pre-charge relay PCRy (Pre-Chr Relay), and positive main current relay MR+ (Main+ Relay).

[0027] The interface circuit 20 includes a DC charging interface DCC (D_Charge Connect), an electric drive system power supply interface RMC (R_MCU Connect), and an auxiliary power supply interface FMC (F_MCU Connect).

[0028] One end of the main current sensor HM is connected to the negative terminal of the main battery MP, and one end of the auxiliary current sensor HA is connected to the DAB converter. The other end of the main current sensor HM is connected to the other end of the auxiliary current sensor HA and one end of the secondary battery current sensor HT. The other end of the secondary battery current sensor HT is connected to one end of the negative DC relay DCR- and the negative terminal of the DC charging interface DCC through the negative main current relay MR-. The other end of the negative DC relay DCR- is connected to the negative terminal of the DC charging interface DCC. A voltage detection module (not shown in the figure, which can be externally connected via a connector or built into the power module) is connected in parallel to the battery terminal and the DC side of the DAB converter, that is, in parallel to the positive and negative terminals of the main battery MP and the secondary battery AP. One end of the positive DC relay DCR+ is connected to the positive terminal of the power supply interface RMC of the electric drive system, the positive terminal of the auxiliary power supply interface FMC, and the other end of the positive main current relay MR+. One end of the positive main current relay MR+ is connected to one end of the precharge relay PCRy, the other end of the auxiliary relay AR, and the positive terminal of the main battery MP. The other end of the precharge relay PCRy is connected to the other end of the positive main current relay MR+. One end of the auxiliary relay AR is connected to the DAB converter and the other end of the main relay MRA+. One end of the precharge relay PCR is connected to one end of the main relay MRA+ and the positive terminal of the auxiliary battery AP. The other end of the precharge relay PCR is connected to the other end of the main relay MRA+ and the DAB converter. The drive module is connected to the gate of each switching transistor in the DAB converter.

[0029] Preferably, the acquisition switch circuit may also include a total fuse FT (Fuse_total) and a pyro fuse PF (Pyro_fuse); one end of the total fuse FT is connected to one end of the pyro fuse PF and the other end of the auxiliary relay AR, the other end of the total fuse FT is connected to one end of the positive main current relay MR+, and the other end of the pyro fuse PF is connected to the positive terminal of the main battery MP.

[0030] Preferably, the acquisition switch circuit may further include a pre-charge resistor PCRA (Pre-Chr Res) at the auxiliary battery terminal and a pre-charge resistor PCRes at the interface terminal. The pre-charge resistor PCRA is connected between the other end of the pre-charge relay PCR and the other end of the main relay MRA+, and the pre-charge resistor PCRes is connected between the other end of the pre-charge relay PCRy and the other end of the positive main current relay MR+. The thick lines on the right side of the controller indicate the control terminals connected to each relay.

[0031] A DAB converter, short for Dual Active Bridge DC-DC converter, has bidirectional energy flow capability and can simultaneously achieve DC-DC boost and buck conversion; for example... Figure 2 As shown, it consists of two interleaved primary-side full-bridges and secondary-side full-bridges. Each full-bridge is composed of four switching devices (such as IGBTs or MOSFETs). The upper and lower switches on the same bridge arm use complementary conduction (high level to turn on, low level to turn off, to avoid bridge arm shoot-through). The trigger signal of the switch output by the drive module controls the phase difference (phase shift angle) between the primary-side and secondary-side full-bridges. The magnitude and direction of the phase difference determine the magnitude and direction of power transmission: the larger the phase difference, the greater the transmitted power; the direction of the phase difference (primary side leading / lagging secondary side) determines whether the power is from the main battery to the secondary battery (forward) or in reverse.

[0032] Please refer to the following: Figure 2 In conjunction with the specific structure of the above-described compensation system, this embodiment of the invention also provides a bidirectional power supply compensation method, comprising the following steps: S100: Real-time acquisition of operating data from the main battery and auxiliary battery and transmission to the controller. The controller determines the current operating mode to be executed based on the calculated power and battery charge. S200 When starting the forward mode, the controller controls the DAB converter to adjust the phase shift angle according to the calculated forward phase shift compensation amount, and then switches the corresponding transmission path to supply power from the main battery to the auxiliary battery. S300 When starting reverse mode, the controller controls the DAB converter to adjust the phase shift angle according to the calculated reverse phase shift angle, and then switches the corresponding transmission path to supply power to the main battery from the auxiliary battery. S400 When starting standby mode, the controller sets the phase shift angle of the DAB converter to 0°, waits for a preset time, and then returns to step S100.

[0033] To improve the accuracy of system operation, before step S100, the system further includes: starting the initialization mode, performing hardware self-tests and initial parameter configurations to prepare for system operation. The hardware self-test includes two points: First, upon power-on, it checks the status of each sensor, drive module, DAB converter, and relay. Specifically, the controller (through interfaces such as F_MICUConnector) checks whether the main current sensor (Hall_main) and auxiliary current sensor (Hall_auxiliary) can output current signals normally. The controller determines whether the received current signal is within a reasonable range (matching the actual current, without jumps or exceeding limits). The controller checks whether the voltage collected by the voltage detection module is consistent with the actual voltage of the two batteries. The controller checks whether the drive module (such as the gate driver chip) of the DAB converter's switching transistors can output pulse trigger signals normally. Test pulses can be sent for verification. The trigger signal output by the drive module based on the test pulses must meet the requirements for voltage amplitude, frequency, and timing. The DAB switching frequency is typically tens of kHz, and the timing requires complementary conduction of the upper and lower transistors on the same bridge arm. The controller detects the bridge arm switching transistors (IGBT / SiC MOSFET) inside the DAB converter based on the trigger signal during testing, whether there are short circuits or open circuits (normal turn-on and turn-off), and whether there are inter-turn short circuits in the transformer (no-load test voltage ratio; when the primary side is energized under no-load conditions, the secondary side voltage conforms to the ratio). Taking the pre-charge relay PCRy (Pre-ChrRelay) in the pre-charge circuit as an example, the controller detects whether its activation and deactivation feedback signals are normal.

[0034] Second, battery and parameter initialization is performed. Specifically, the controller collects the initial voltage and initial charge of the main battery (MP) and the secondary battery (AP, also called the auxiliary battery). The phase shift angle of the DAB converter is initialized to 0° (no power transmission state), and the SOC (power) algorithm is initialized. When the system is in standby mode, the phase shift angle is initialized to 0°. At this time, the PWM of the primary and secondary full-bridge circuits are in phase, and the DAB converter has no power transmission. If initial power transmission is required, a small phase shift angle can be set according to the needs.

[0035] In step S100, key electrical parameters of the system operation can be collected every 1ms to provide a basis for mode judgment; real-time data updates are necessary to improve the accuracy of mode judgment. Specifically, the main current sensor HM collects the main-side current at the output of the main battery, the auxiliary current sensor HA collects the current in the circuit from the main battery to the DAB converter, the secondary battery current sensor HT collects the secondary battery current, and the voltage detection module collects the voltages of the main battery and the secondary battery.

[0036] The controller calculates the power P of both batteries based on "voltage × current". The main battery's power... , This indicates the current voltage of the main battery, and I represents the main-side current currently measured by the main current sensor HM. The charging interface connects to the external electric drive system and on-board charging components. The auxiliary battery power is the power consumed by the auxiliary battery. , This indicates the voltage currently collected by the voltage detection module on the secondary battery side (i.e., the voltage between the positive and negative terminals of the charging interface). This indicates the current of the secondary battery currently collected by the secondary battery current sensor HT.

[0037] The current state of charge (SOC) of the auxiliary battery is calculated using the ampere-hour integration method (current integration) and open-circuit voltage correction, and the data is updated in real time. The correction trigger condition is: when the auxiliary battery is in an open-circuit state (i.e., the auxiliary battery is disconnected, there is no charging or discharging current, I(t)=0) and has been left to rest for a sufficient time (usually 5~30 minutes to ensure that the internal polarization effect of the battery is eliminated), the voltage measured at this time is the open-circuit voltage OCV. Then, the corrected SOC of the auxiliary battery is obtained through the open-circuit voltage OCV: based on the measured OCV value, the pre-calibrated OCV is looked up. The SOC curve yields the corrected SOC value at that moment, denoted as . ( (The calibration time is t, where t is the current time). Finally, reset the initial value of the integral to the calibration time. As a new starting point, the initial SOC in the ampere-hour integral formula is updated to... The specific formula is as follows: ; Where SOC(t) represents the state of charge of the secondary battery at time t, that is, the percentage of the battery's remaining charge; Indicates the time of correction The state of charge of the secondary battery after correction is obtained by the open-circuit voltage (OCV) method. The nominal capacity of the auxiliary battery is expressed in ampere-hours (Ah), representing the total amount of charge that the auxiliary battery can release under standard conditions; η(t) represents the charge-discharge efficiency, which is a function of time t. The charging efficiency is less than 1 (because of energy loss), and is usually approximately 1 during discharge. It represents the battery current, which is a function of time t. The current is positive when charging and negative when discharging (or can be adjusted according to different rules of sign definition; the core is to reflect the inflow / outflow of charge). Indicates from the correction time At time t, the integral of the amount of charge added or released by the secondary battery after considering the charging and discharging efficiency.

[0038] Determining the current compensation mode to be executed specifically includes: Step 110: Determine whether the main power of the main battery is greater than or equal to the power of the secondary battery, and whether the battery capacity of the main battery is greater than or equal to the lower threshold. If yes, start the forward mode; otherwise, proceed to step 120.

[0039] In this step, condition 1 is and When the lower limit threshold is set to the preferred value, it indicates that the secondary battery consumes little energy and the main battery has sufficient power. Step S200 can be executed to start the forward mode, that is, the main battery supplies power to the secondary battery (transfers energy, which is also power transfer).

[0040] Step 120: Determine whether the power of the secondary battery is greater than the main power of the primary battery, and whether the battery capacity of the secondary battery is greater than or equal to the lower threshold; if yes, start the reverse mode, otherwise execute step S400.

[0041] In this step, condition 2 is and If the main battery is consuming too much power and cannot support the power consumption of the secondary battery, but the secondary battery has sufficient charge, then step S300 can be executed to start the reverse mode, i.e., the secondary battery charges the main battery. If neither condition is met, it falls under other cases, and step S400 is executed directly to enter standby mode.

[0042] Step S200 specifically includes: Step 210: When starting the forward mode, calculate the forward phase shift compensation amount.

[0043] The positive phase shift angle compensation amount The controller is responsible for adjusting the transmission power of the DAB converter so that the sum of the main power and the DAB transmission power matches the power demand of the auxiliary battery to make up for the power gap of the auxiliary battery. .

[0044] Step 220: The drive module outputs a corresponding trigger signal based on the positive phase shift compensation amount to control the DAB converter to adjust the phase shift angle so that the main battery supplies power to the auxiliary battery.

[0045] The controller is based on the calculation A drive signal with a corresponding phase shift (a high-frequency PWM signal, typically 20~100KHz) is generated. After being amplified by the drive module (gate drive chip), a corresponding trigger signal is output. The trigger signal drives the full-bridge switches on the primary and secondary sides of the DAB converter. When the power of the main battery is greater than the power of the secondary battery, the phase shift angle is adjusted. At the same time, the controller controls MR+ and MR- to open and close, while AR and MRA+ remain closed (without disconnecting the connection between the secondary battery and the DAB converter). DCR-, DCR+, and PCRy are disconnected, allowing the main battery to connect to the external load, realizing the forward power transmission path of main battery → DAB converter → secondary battery. At this time, the main battery supplies power to the secondary battery.

[0046] Step 230: Determine whether the power change is less than or equal to zero or the main battery's charge is less than the lower limit threshold. If so, exit the positive mode.

[0047] This step is used to determine whether to exit the forward mode by monitoring the system status. At a given time t relative to the initial time... The change in power is: This indicates that the main battery's output power is insufficient and the main battery's charge level is low. This indicates that the battery power is low. At this time, the main battery cannot continue to supply power to the auxiliary battery. It is necessary to exit the positive mode and return to step S100 to re-determine.

[0048] Step S300 specifically includes: Step 310: Start reverse mode, read the target current for reverse charging, and calculate the reverse phase shift angle.

[0049] The target current The target current is read directly from its internal Flash memory by the controller. Determined by battery specifications, such as the maximum allowable charging current of the main battery. Threshold parameters related to reverse charging, such as target current, constant voltage (CV), or constant current (CC), are pre-written into the Flash memory.

[0050] The controller adjusts based on the current main battery voltage. and the voltage of the secondary battery Calculate the reverse transmission power P of the DAB converter (single phase shift control). ; Where n is the transformer turns ratio, f is the switching frequency, and L is the inductance value of the auxiliary inductance or leakage inductance. This represents the reverse phase shift angle. n, f, and L are all hardware design values, pre-stored in the controller's Flash memory.

[0051] make By combining the formula above, the reverse phase shift angle can be derived. , .

[0052] Step 320: The drive module outputs a corresponding reverse trigger signal according to the reverse phase shift angle, controls the DAB converter to adjust the phase shift angle, so that the auxiliary battery supplies power to the main battery.

[0053] When the main battery power is less than the external load power, or when the main battery power is less than the auxiliary battery power, the controller calculates the reverse phase shift angle. A reverse drive signal with a reverse phase shift is generated, amplified by the drive module (gate drive chip), and outputs a corresponding reverse trigger signal. The reverse trigger signal drives the full-bridge switches on the primary and secondary sides of the DAB converter to adjust the phase shift angle. At the same time, the controller controls AR, MRA+, and PCR to close; and controls MR-, DCR-, DCR+, MR+, and PCRy to close, so that the main battery is connected to the secondary battery through the DAB converter, realizing the reverse power transmission path of secondary battery → DAB converter → main battery; at this time, the secondary battery supplies power to the main battery.

[0054] Step 330: Determine whether the battery charge of the secondary battery is less than the lower limit threshold or whether there is an abnormal charging power. If so, exit the reverse mode.

[0055] This step is used to determine whether to exit reverse mode by monitoring the system status. The secondary battery's battery level is also considered. This indicates that the secondary battery has insufficient power, or that the charging power is abnormal, such as the actual current being much lower than the rated current. At this point, the secondary battery can no longer supply power to the main battery, and it is necessary to exit the reverse mode and return to step S100 to re-evaluate.

[0056] If the conditions for forward or reverse modes are not met, it falls under other cases, namely the standby mode in step S400, where the system is in a low-power standby state and its status needs to be monitored periodically. In step S400, the controller directly sets the phase shift angle of the DAB converter to 0° (primary and secondary full-bridge are in phase, with no power transmission) and controls unnecessary relays MAR+, PCR, AR, PCRy, MR+, and MR- to disconnect, while DCR+ and DCR- are turned on, keeping only the basic circuit conducting to reduce power consumption. After waiting for a preset time (e.g., 10ms), the system returns to step S100, re-collects the corresponding data, and performs mode judgment. If it still enters standby mode, it waits for another preset time (e.g., 10ms) and then returns to step S100, repeating this cycle until step S100 determines whether to enter forward or reverse mode. Returning to the judgment every 10ms ensures real-time response to system changes (such as an increase in battery SOC or a sudden change in secondary battery power). It should be understood that the loop exits when the system is powered off.

[0057] In summary, the bidirectional power supply compensation method and system provided by this invention can determine the current operating mode based on the calculated power and battery charge. In forward mode, the DAB converter is controlled to adjust the phase shift angle based on the calculated forward phase shift compensation amount to supply power from the main battery to the auxiliary battery. In reverse mode, the DAB converter is controlled to adjust the phase shift angle based on the calculated reverse phase shift angle to supply power from the auxiliary battery to the main battery. In standby mode, the phase shift angle of the DAB converter is set to 0°. By adjusting the phase shift angle of the DAB converter, the charging power transmission path is changed, enabling forward power supply from the main battery to the auxiliary battery. When the main battery cannot meet the power output requirements of the auxiliary battery, the auxiliary battery supplies power to the main battery to meet the power output requirements of the auxiliary battery.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A compensation method for a bidirectional power supply, characterized in that, include: Step A: Collect the working data of the main battery and the auxiliary battery in real time and transmit it to the controller. The controller determines the current working mode to be executed based on the calculated power and battery level. Step B: When starting the forward mode, the controller controls the DAB converter to adjust the phase shift angle according to the calculated forward phase shift compensation amount, and then switches the corresponding transmission path to supply power from the main battery to the auxiliary battery. Step C: When starting the reverse mode, the controller controls the DAB converter to adjust the phase shift angle according to the calculated reverse phase shift angle, and after switching the corresponding transmission path, the auxiliary battery supplies power to the main battery. Step D: When starting standby mode, the controller sets the phase shift angle of the DAB converter to 0°, waits for a preset time, and then returns to step A.

2. The bidirectional power supply compensation method according to claim 1, characterized in that, Before step A, there is also step A0: starting the initialization mode, performing hardware self-test and initial parameter configuration.

3. The bidirectional power supply compensation method according to claim 2, characterized in that, In step A1, the hardware self-test includes: self-testing the status of each sensor, drive module, DAB converter, and relay upon power-on; and initializing the battery and parameters.

4. The bidirectional power supply compensation method according to claim 2, characterized in that, In step A, the controller calculates the main power of the main battery based on the voltage and current of the main battery, calculates the power of the secondary battery based on the voltage and current of the secondary battery, and calculates the current battery capacity of the secondary battery using the ampere-hour integration method and open-circuit voltage correction.

5. The bidirectional power supply compensation method according to claim 4, characterized in that, In step A, the step of determining the compensation mode to be executed specifically includes: Step A1: Determine whether the main power of the main battery is greater than or equal to the power of the secondary battery, and whether the battery capacity of the main battery is greater than or equal to the lower threshold. If yes, start the forward mode; otherwise, proceed to step A2. Step A2: Determine whether the power of the secondary battery is greater than the main power of the primary battery, and whether the battery capacity of the secondary battery is greater than or equal to the lower threshold. If yes, start the reverse mode; otherwise, proceed to step D.

6. The bidirectional power supply compensation method according to claim 1 or 5, characterized in that, Step B specifically includes: Step B1: When starting the forward mode, calculate the forward phase shift compensation amount; Step B2: The drive module outputs a corresponding trigger signal based on the positive phase shift compensation amount to control the DAB converter to adjust the phase shift angle so that the main battery supplies power to the auxiliary battery. Step B3: Determine whether the power change is less than or equal to zero or the main battery's charge is less than the lower threshold. If so, exit the positive mode.

7. The bidirectional power supply compensation method according to claim 6, characterized in that, Step C specifically includes: Step C1: Start reverse mode, read the target current for reverse charging, and calculate the reverse phase shift angle; Step C2: The drive module outputs a corresponding reverse trigger signal according to the reverse phase shift angle, controls the DAB converter to adjust the phase shift angle, so that the auxiliary battery supplies power to the main battery; Step C3: Determine whether the secondary battery's charge level is below the lower threshold or if there is an abnormal charging power. If so, exit the reverse mode.

8. A compensation system for implementing the bidirectional power supply compensation method of claim 1, comprising a main battery and a secondary battery, characterized in that, It also includes a controller, a DAB converter, a data acquisition switch circuit, and an interface circuit; The acquisition switch circuit collects the working data of the main battery and the auxiliary battery in real time and transmits it to the controller. The controller determines the current operating mode to be executed based on the calculated power and battery level. When the forward mode is started, the controller controls the DAB converter to adjust the phase shift angle according to the calculated forward phase shift compensation amount, and the acquisition switching circuit switches the corresponding transmission path to enable the main battery to supply power to the auxiliary battery. When the reverse mode is activated, the controller controls the DAB converter to adjust the phase shift angle according to the calculated reverse phase shift angle, and the acquisition switching circuit switches the corresponding transmission path to enable the auxiliary battery to supply power to the main battery. When the standby mode is started, the controller sets the phase shift angle of the DAB converter to 0° and waits for a preset time before returning to the working mode for judgment.

9. The compensation system according to claim 8, characterized in that, The acquisition switch circuit includes several sensors for detecting corresponding current and voltage, several relays for switching transmission paths, a drive module for amplifying the drive signal output by the controller, and a voltage detection module for acquiring the voltage of the main battery and the auxiliary battery.

10. The compensation system according to claim 8, characterized in that, The DAB converter is used for DC-to-DC boost and buck conversion. It consists of two interleaved primary-side full-bridge and secondary-side full-bridge. The trigger signal output by the drive module controls the phase difference between the primary-side and secondary-side full-bridge.

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