Active equalization control system

Abstract

The invention provides an active equalization control system which comprises a plurality of active equalization boards, and each active equalization board is connected to an active equalization board power supply small board through a power supply line. The active equalization board power supply small board comprises a power failure detection circuit and a switching circuit and is used for controlling the power supply of the active equalization board; the BCU board comprises an MCU (Microprogrammed Control Unit) and is used for receiving a signal from the power failure detection circuit and controlling the power supply of the active equalization board; and the AC / DC converter is connected to the commercial power and provides a stable DC power supply for the system. According to the invention, real-time monitoring and accurate control of the power supply state of the active equalization board can be realized, safe shutdown and sequential restart of the bidirectional DC-DC converter are ensured, equipment damage caused by direct power failure is prevented, stable operation of the system is guaranteed, and the reliability and safety of the active equalization system are improved.

Description

Technical Field

[0001] The present invention relates to the field of battery management systems, and more particularly, to an active balancing control system. Background Art

[0002] In an active balancing circuit based on a bidirectional DC-DC, a bidirectional DC-DC converter is used to transfer high energy from a single cell to a single cell with low energy. To ensure the safe and stable operation of the bidirectional DC-DC converter, it is necessary to manage the bidirectional flow of energy through appropriate control strategies and circuit designs, rather than simply powering off directly. For example, the bidirectional DC-DC of Mornsun clearly indicates in the specification that it is necessary to power on and off in a specific order to avoid product damage. Therefore, in an active balancing circuit based on a bidirectional DC-DC, it is necessary to detect the power failure of the power supply and control it in a timely manner.

[0003] In the process of implementing the embodiments of the present invention, the inventors found that there are at least the following problems or defects in the prior art: The prior art lacks an effective power failure detection and control mechanism, and it is unable to detect voltage changes in a timely and accurate manner and take corresponding control measures when the power supply fails, so as to protect the bidirectional DC-DC converter from damage. At the same time, when the system resumes power supply, it is also unable to ensure that the bidirectional DC-DC converter is restarted in the correct order, which seriously affects the stability and reliability of the active balancing system. Summary of the Invention

[0004] The present invention provides an active balancing control system, including:

[0005] A plurality of active balancing boards, each of which is connected to the power supply small board of the active balancing board through a power supply line;

[0006] The power supply small board of the active balancing board, including a power failure detection circuit and a switching circuit, for controlling the power supply of the active balancing board;

[0007] The BCU board, including an MCU, for receiving signals from the power failure detection circuit and controlling the power supply of the active balancing board;

[0008] An AC / DC converter, connected to the mains power, to provide a stable DC power supply for the system.

[0009] Furthermore, the connection relationship between the power failure detection circuit and the switching circuit of the power supply small board of the active balancing board and the BCU board is as follows:

[0010] The power failure detection circuit is connected to the MCU of the BCU board through an optocoupler U2, and is used to transmit the voltage status signal of VCC24V_OUT;

[0011] The switch circuit is connected to the MCU of the BCU board through the optocoupler U3, and is used to receive the control signal of the MCU and control the power supply of the active equalization board.

[0012] Further, the power-off detection circuit includes:

[0013] A voltage comparator U1 (TL431), whose cathode is connected to a voltage-dividing circuit composed of resistors R1 and R2, the anode is connected to VCC24V_OUT, and the reference terminal (R) is grounded through resistors R3 and R4;

[0014] A PNP-type triode Q1, whose base is connected to the output terminal of U1, the collector is connected to resistors R5 and the zener diode ZD1, and the emitter is grounded;

[0015] A PMOS Q2, whose source is connected to VCC24V_OUT, the drain is connected to the primary side light-emitting diode of the optocoupler U2, and the gate is connected to the collector of Q1;

[0016] An optocoupler U2, whose secondary side photosensitive triode is connected to VCC_5V and GND_BCU, and the output terminal is connected to MCU_DETECT_ON / OFF.

[0017] Further, the switch circuit includes:

[0018] A PMOS Q3, whose source is connected to VCC24V_IN, the drain is connected to VCC24V_OUT, and the gate is connected to the secondary side photosensitive triode of the optocoupler U3;

[0019] An optocoupler U3, whose primary side light-emitting diode is connected to the IO port of the MCU, and the secondary side photosensitive triode is connected to the gate of Q3;

[0020] A super capacitor C1, whose positive pole is connected to VCC24V_BALANCE, and the negative pole is connected to GND_BALANCE, and is used to provide short-term power support for the active equalization board during power-off;

[0021] A diode D1, connected between VCC24V_BALANCE and the positive pole of C1, is used to prevent reverse current.

[0022] Further, the power-off detection circuit further includes:

[0023] A resistor R6, connected between the drain of Q2 and the ground, is used for current limiting.

[0024] Further, the switch circuit further includes:

[0025] Resistors R7 and R8, connected between VCC_5V and MCU_DETECT_ON / OFF, are used for current limiting and voltage division;

[0026] Resistors R9 and R10 are connected between VCC24V_IN and GND_BALANCE for current limiting and voltage division.

[0027] Resistor R11 is connected between the output of U3 and ground for current limiting.

[0028] Furthermore, the AC / DC converter converts the commercial power into VCC24V_OUT to supply power to the power supply small board of the active equalization board.

[0029] Furthermore, the MCU of the BCU board communicates with the active equalization board through the CAN communication protocol to send control instructions and receive status information.

[0030] Furthermore, when power-off is detected, the CAN communication protocol is used for the BCU to send control instructions to the active equalization board to ensure the safe shutdown of the bidirectional DC-DC.

[0031] Furthermore, the control instructions include immediately shutting down the bidirectional DC-DC converter and, when the system resumes power supply, restarting the bidirectional DC-DC converter in the correct order.

[0032] According to the above embodiments of the present invention, there are at least the following beneficial effects: The active equalization control system of the present invention can realize the real-time monitoring of the power supply state of the active equalization board. The power-off detection circuit can timely sense the change of the VCC24V_OUT voltage. When it is detected that the voltage changes from high to low or from low to high and lasts for a period of time, the MCU in the BCU board can quickly respond. At the moment of power-off, the supercapacitor C1 is used to provide short-term power support for the active equalization board. At the same time, the BCU sends control instructions to the active equalization board through the CAN communication protocol to ensure that the bidirectional DC-DC converter can be safely shut down in the correct order, avoiding equipment damage caused by direct power-off and ensuring the stable operation of the system.

[0033] In addition, when active equalization is not required, the system can also cut off the power supply of the active equalization board through the control switch circuit, thereby saving power consumption; when the active equalization board has an abnormality, it can also cut off the power supply to the active equalization board by controlling the power supply, further enhancing the reliability and safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, wherein:

[0035] Figure 1 is a schematic structural diagram of the active equalization control system provided by an embodiment of the present invention;

[0036] Figure 2 The structural schematic diagram of the power-down detection circuit provided by an embodiment of the present invention;

[0037] Figure 3 The structural schematic diagram of the switch circuit provided by an embodiment of the present invention. Detailed implementation manners

[0038] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and then implement the present invention, and do not limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to be able to fully convey the scope of the present invention to those skilled in the art.

[0039] Those skilled in the art know that the embodiments of the present invention can be implemented as a system, a device, an equipment, a method or a computer program product. Therefore, the present invention can be specifically implemented in the following forms: completely hardware, completely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0040] It should be noted that any number of elements in the drawings is for illustration rather than limitation, and any naming is only for distinction and does not have any limiting meaning.

[0041] The following refers to Figure 1 , Figure 1 The structural schematic diagram of the active balancing control system provided by an embodiment of the present invention. As Figure 1 shown, an active balancing control system includes:

[0042] A plurality of active balancing boards, each of which is connected to the active balancing board power supply small board through a power supply line;

[0043] The active balancing board power supply small board, including a power-down detection circuit and a switch circuit, for controlling the power supply of the active balancing board;

[0044] The BCU board, including an MCU, for receiving signals from the power-down detection circuit and controlling the power supply of the active balancing board;

[0045] The AC / DC converter, connected to the commercial power, to provide a stable DC power supply for the system.

[0046] It should be noted that this active equalization control system is a device for battery pack energy management, aiming to achieve balanced charging and discharging of the battery pack by precisely controlling the energy flow between battery cells. The core components of the system include multiple active equalization boards, a power supply board for the active equalization boards, a BCU board, and an AC / DC converter. The active equalization boards are responsible for transferring energy between battery cells, the power supply board provides a stable power supply for these equalization boards, and the BCU board serves as the control center, receiving signals from the power supply board through its built-in MCU (microcontroller unit) and controlling the power supply of the equalization boards. The role of the AC / DC converter is to convert the mains power into the DC power required by the system to ensure the stable operation of the entire system.

[0047] Specifically, the number and configuration of the active equalization boards should be determined according to the scale and equalization requirements of the battery pack. For example, in a battery pack composed of 24 battery cells, 12 active equalization boards may be required, with each board responsible for equalizing two battery cells. The power-off detection circuit and switch circuit on the power supply board for the active equalization boards need to be precisely set with parameters to ensure stable power supply when the mains power is normal and to cut off the power supply in a timely manner and trigger the protection mechanism when the mains power is abnormal. For example, the threshold of the power-off detection circuit can be set to trigger when the mains voltage drops to 85% of the rated voltage, and the switch circuit should cut off the power supply within 10 milliseconds after detecting the power-off signal. The MCU of the BCU board should have sufficient processing power and communication interfaces to achieve real-time monitoring and control of multiple equalization boards. The output voltage of the AC / DC converter should match the input voltage requirements of the power supply board for the active equalization boards, for example, output a stable 24V DC power supply, and the conversion efficiency should be higher than 90% to reduce energy loss.

[0048] Preferably, in order to improve the reliability and anti-interference ability of the system, isolation communication technology such as opto-isolation can be adopted between the power supply board for the active equalization boards and the BCU board to prevent interference on the power supply side from affecting the transmission of control signals. In addition, a filtering circuit can be added at the output end of the AC / DC converter to reduce voltage ripple and improve the power quality. In actual applications, the active equalization strategy can also be optimized according to the usage environment and working conditions of the battery pack. For example, in a low-temperature environment, the equalization current can be appropriately reduced to reduce the internal heat generation of the battery; after the battery pack ages, the equalization threshold can be adjusted to adapt to the change in battery performance. At the same time, in order to improve the convenience of system maintenance, a user interface can be designed on the BCU board to display the status information of the battery pack and the system operation parameters, facilitating users to monitor and adjust.

[0049] As Figure 2 shown, the schematic structural diagram of an active equalization control system provided by some embodiments, and the connection relationship between the power-off detection circuit and the switch circuit of the power supply board for the active equalization boards and the BCU board is as follows:

[0050] The power-off detection circuit is connected to the MCU of the BCU board through the optocoupler U2 and is used to transmit the voltage status signal of VCC24V_OUT;

[0051] The switch circuit is connected to the MCU of the BCU board through the optocoupler U3 and is used to receive the control signal of the MCU to control the power supply of the active equalization board.

[0052] It should be noted that the connection relationship between the power-off detection circuit and the switch circuit of the power supply small board of the active equalization board and the BCU board is one of the key technical points of this system. The power-off detection circuit is connected to the MCU of the BCU board through the optocoupler U2 and is used to transmit the voltage status signal of VCC24V_OUT, which can ensure that the BCU board can monitor the power supply status in real time. The switch circuit is connected to the MCU of the BCU board through the optocoupler U3 and is used to receive the control signal of the MCU, so as to accurately control the power supply of the active equalization board.

[0053] Specifically, the selection of optocouplers U2 and U3 is crucial. Optocoupler U2 is used for the transmission of voltage status signals, and its current transfer ratio should be selected between 100% and 200% to ensure the stability and accuracy of the signals. For example, if the normal operating voltage of VCC24V_OUT is 24V and the forward voltage drop of the primary side light-emitting diode of optocoupler U2 is 1.2V, then the resistance value of the primary side resistor can be calculated to ensure that the current of the light-emitting diode is within the safe operating range under 24V voltage. For optocoupler U3, the on and off states of the secondary side photosensitive triode directly control the gate of PMOS Q3, thereby realizing the control of the power supply of the active equalization board. The breakdown voltage value of PMOS Q3 should be higher than the highest voltage of VCC24V_IN. For example, if VCC24V_IN is 24V, a PMOS transistor with a breakdown voltage value of more than 30V should be selected.

[0054] Preferably, in order to improve the anti-interference ability and response speed of the system, filter circuits can be added to the primary side and secondary side of optocouplers U2 and U3 respectively. For example, an inductor is connected in series on the power supply line of the primary side light-emitting diode, and a capacitor is connected in parallel at the output end of the secondary side photosensitive triode, which can effectively filter out high-frequency noise.

[0055] Furthermore, in order to ensure that the power supply can be quickly cut off at the moment of power-off, a fast-response protection circuit can be added to the switch circuit, such as using a high-speed comparator to monitor the voltage of VCC24V_OUT. Once the voltage is lower than the set threshold, the protection mechanism is immediately triggered to cut off the power supply of PMOS Q3. In practical applications, the parameters of the optocoupler and the design of the protection circuit can also be optimized according to the specific requirements of the system to adapt to different working environments and performance requirements.

[0056] In some embodiments, the power-down detection circuit includes:

[0057] A voltage comparator U1 (TL431), whose cathode is connected to a voltage-dividing circuit composed of resistors R1 and R2, the anode is connected to VCC24V_OUT, and the reference terminal (R) is grounded through resistors R3 and R4;

[0058] A PNP-type triode Q1, whose base is connected to the output terminal of U1, the collector is connected to resistors R5 and a Zener diode ZD1, and the emitter is grounded;

[0059] A PMOS Q2, whose source is connected to VCC24V_OUT, the drain is connected to the primary side light-emitting diode of the optocoupler U2, and the gate is connected to the collector of Q1;

[0060] An optocoupler U2, whose secondary side photosensitive triode is connected to VCC_5V and GND_BCU, and the output terminal is connected to MCU_DETECT_ON / OFF.

[0061] It should be noted that the design of the power-down detection circuit is to accurately monitor the voltage state of VCC24V_OUT and transmit this state to the MCU of the BCU board through the optocoupler U2. This circuit uses the voltage comparator U1 (TL431) to detect voltage changes, and the switching circuit composed of the PNP-type triode Q1 and the PMOS Q2 controls the conduction state of the optocoupler U2 according to the output of TL431. TL431 is an adjustable precision voltage regulator, which is used as a voltage comparator here and can provide high-precision voltage detection. The combination of the PNP-type triode Q1 and the PMOS Q2 ensures that the circuit can quickly respond when detecting voltage changes, control the light-emitting diode of the optocoupler U2, and then affect the output of the secondary side photosensitive triode, and finally transmit it to the MCU_DETECT_ON / OFF pin of the MCU to realize real-time monitoring of the power-down state.

[0062] Specifically, the reference terminal voltage of TL431 is set to 2.5V, which is achieved by the voltage division of resistors R3 and R4. When the voltage generated at the reference terminal of TL431 by VCC24V_OUT through resistors R1 and R2 is higher than 2.5V, TL431 conducts, and the PNP transistor Q1 enters the saturation region, resulting in insufficient voltage difference between the source and gate of PMOS Q2, so it is cut off between the source and drain. There is not enough current in the primary light-emitting diode of optocoupler U2, causing the secondary photosensitive transistor to be cut off, and MCU_DETECT_ON / OFF continuously outputs a high level. Conversely, when the voltage of VCC24V_OUT decreases, TL431 is cut off, the PNP transistor Q1 enters the cut-off region, there is enough voltage difference between the source and gate of PMOS Q2, it conducts between the source and drain, there is enough current in the primary light-emitting diode of optocoupler U2, the secondary photosensitive transistor conducts, and MCU_DETECT_ON / OFF continuously outputs a low level. The resistance values of resistors R1, R2, R3, and R4 need to be accurately calculated according to the voltage range of VCC24V_OUT and the characteristics of TL431 to ensure the accuracy of voltage comparison.

[0063] Preferably, in order to improve the stability and anti-interference ability of the power-down detection circuit, a low-pass filter can be added to the reference terminal of TL431, such as connecting a 10μF electrolytic capacitor in parallel, to reduce the influence of voltage fluctuations on the detection results. In addition, in order to protect the PNP transistor Q1 and PMOS Q2, a transient voltage suppression diode (TVS) can be connected in parallel to their collector and drain respectively to prevent damage caused by overvoltage.

[0064] Furthermore, in practical applications, the parameters of resistors R1 to R5 can also be fine-tuned according to specific power supply voltages and load requirements to optimize the performance of the circuit. For example, if the load current is large, it may be necessary to appropriately reduce the resistance value of R5 to ensure that there is enough current passing through the Zener diode ZD1, so as to ensure the stable operation of the PNP transistor Q1. At the same time, in order to improve the response speed of the circuit, fast-switching PNP transistors and PMOS transistors can be selected, such as 2N3906 and IRF9Z34N.

[0065] As Figure 3 shown, a schematic structural diagram of an active balancing control system provided by some embodiments, the switching circuit includes:

[0066] PMOS Q3, whose source is connected to VCC24V_IN, drain is connected to VCC24V_OUT, and gate is connected to the secondary photosensitive transistor of optocoupler U3;

[0067] Optocoupler U3, whose primary light-emitting diode is connected to the IO port of the MCU, and secondary photosensitive transistor is connected to the gate of Q3;

[0068] A super capacitor C1, whose positive electrode is connected to VCC24V_BALANCE and negative electrode is connected to GND_BALANCE, is used to provide short-term power support for the active equalization board during power-off;

[0069] A diode D1, connected between VCC24V_BALANCE and the positive electrode of C1, is used to prevent reverse current.

[0070] It should be noted that the design of the switch circuit is to precisely control the power supply of the active equalization board to ensure that the power can be cut off or connected in time when needed. PMOS Q3 serves as a switching element, with its source electrode connected to VCC24V_IN, drain electrode connected to VCC24V_OUT, and gate receiving control signals from the MCU through the secondary side photosensitive triode of the optocoupler U3. The optocoupler U3 plays a role in signal isolation, preventing the control signals of the MCU from being interfered by the power supply side. The super capacitor C1 is used to provide short-term power support for the active equalization board at the moment of power-off to ensure the stable shutdown of the system. The diode D1 prevents the reverse flow of current during the discharge process of the super capacitor C1, protecting the safety of the circuit.

[0071] Specifically, the selection of PMOS Q3 should be based on its breakdown voltage and on-resistance. The breakdown voltage should be higher than the highest voltage of VCC24V_IN. For example, if VCC24V_IN is 24V, a PMOS transistor with a breakdown voltage of over 30V should be selected. The on-resistance should be as small as possible to reduce the energy consumption during power on and off. The current transfer ratio of the optocoupler U3 should be high enough to ensure stable signal transmission. Generally, an optocoupler with a current transfer ratio of 100% to 200% is selected. The capacitance of the super capacitor C1 needs to be determined according to the time that the active equalization board needs to maintain operation after power-off. For example, if it is necessary to maintain operation for 10 milliseconds, a super capacitor with a capacitance of 1000 μF can be selected. The diode D1 should be a fast-recovery diode to reduce the reverse recovery time. For example, a 1N4148 diode can be selected.

[0072] Preferably, to improve the reliability and security of the system, a transient voltage suppression diode (TVS) can be connected in parallel between the source and drain of PMOS Q3 to protect PMOS Q3 from transient high voltage damage. For example, a TVS diode with a clamping voltage of 27V can be selected. In addition, to improve the charge and discharge efficiency of the supercapacitor C1, a capacitor with a low ESR (equivalent series resistance), such as a 10 μF ceramic capacitor, can be connected in parallel between its positive and negative terminals. In practical applications, the parameters of PMOS Q3 and optocoupler U3 can also be optimized according to the specific power supply voltage and load current. For example, if the load current is large, a PMOS Q3 with a larger current capacity may need to be selected, and the drive current of optocoupler U3 can be appropriately increased to ensure stable signal transmission. At the same time, to improve the response speed of the circuit, fast-switching PMOS transistors and optocouplers can be selected.

[0073] In some embodiments, the power-down detection circuit further includes:

[0074] A resistor R6, connected between the drain of Q2 and the ground, for current limiting.

[0075] It should be noted that adding resistor R6 in the power-down detection circuit is to limit the current flowing through the drain of PMOS Q2 and protect the primary light-emitting diode of optocoupler U2 from damage caused by excessive current. The addition of resistor R6 ensures the stability and reliability of the circuit under various operating conditions, especially during voltage fluctuations or transient processes, and can effectively prevent component damage caused by excessive current.

[0076] Specifically, the resistance value of resistor R6 should be selected based on the maximum allowable current and expected operating current of the primary light-emitting diode of optocoupler U2. For example, if the maximum allowable current of the primary light-emitting diode of optocoupler U2 is 20 mA, the expected operating current is 10 mA, VCC24V_OUT is 24V, and the forward voltage drop of the light-emitting diode is 1.2V, then the resistance value of R6 can be calculated by Ohm's law: R6 = (24V - 1.2V) / 10 mA = 2.28 kΩ. Usually, a resistor with a standard resistance value of 2.2 kΩ can be selected. In addition, the power of resistor R6 also needs to be considered, and a resistor that can withstand the maximum power consumption should be selected. For example, the maximum power consumption is (24V - 1.2V) * 10 mA = 0.228W, and a resistor with a power of 0.25W or higher can be selected.

[0077] Preferably, in order to further improve the stability and anti-interference ability of the circuit, a capacitor, such as a 0.1 μF ceramic capacitor, can be connected in parallel between the resistor R6 and the ground to filter out possible high-frequency noise and reduce the interference to the primary light-emitting diode of the optocoupler U2. In addition, if the circuit works in a high-noise environment, a small-value resistor, such as 100 Ω, can also be connected in parallel between the gate and the source of Q2 to reduce the parasitic capacitance effect of the gate and improve the anti-interference ability of the circuit.

[0078] Furthermore, in practical applications, the resistance value of the resistor R6 can also be finely adjusted according to the specific circuit operating conditions and the characteristics of the optocoupler. For example, in a low-temperature environment, the forward voltage drop of the light-emitting diode may change slightly. At this time, it may be necessary to appropriately adjust the resistance value of R6 to ensure that the current of the light-emitting diode remains within the optimal operating range. At the same time, in order to improve the reliability of the circuit, a resistor with a higher power rating can be selected to cope with possible transient overcurrent situations.

[0079] In some embodiments, the switching circuit further includes:

[0080] Resistors R7 and R8, connected between VCC_5V and MCU_DETECT_ON / OFF, for current limiting and voltage division;

[0081] Resistors R9 and R10, connected between VCC24V_IN and GND_BALANCE, for current limiting and voltage division;

[0082] Resistor R11, connected between the output of U3 and the ground, for current limiting.

[0083] It should be noted that the added resistors R7, R8, R9, R10, and R11 in the switching circuit are to optimize the performance of the circuit and protect related components. Resistors R7 and R8 are connected between VCC_5V and MCU_DETECT_ON / OFF for current limiting and voltage division to ensure that the signal voltage received by the detection pin of the MCU is within a safe range. Resistors R9 and R10 are connected between VCC24V_IN and GND_BALANCE for current limiting and voltage division to protect the stability of the circuit under different operating states. Resistor R11 is connected between the output of U3 and the ground for current limiting to protect the secondary photosensitive triode of the optocoupler U3 from excessive current.

[0084] Specifically, the resistance values of resistors R7 and R8 should be selected based on the voltage requirements of the MCU_DETECT_ON / OFF pin and the voltage value of VCC_5V. For example, if the high-level threshold of the MCU_DETECT_ON / OFF pin is 3.3V and VCC_5V is 5V, the resistance values of R7 and R8 can be calculated using the voltage division formula. Assuming R7 is 1kΩ, then the resistance value of R8 can be calculated as (5V - 3.3V) / 3.3V * 1kΩ = 0.515kΩ, and usually, a standard resistance value of 0.51kΩ or 0.56kΩ can be selected. The resistance values of resistors R9 and R10 should be determined according to the voltage of VCC24V_IN and the current requirement of the circuit. For example, if VCC24V_IN is 24V and the circuit operating current is 1A, R9 can be selected as 24Ω and R10 as 1Ω to achieve appropriate current limiting and voltage division. The resistance value of resistor R11 should be selected according to the maximum allowable current of the photosensitive triode on the secondary side of U3. For example, if the maximum allowable current is 20mA, R11 can be selected as 1.2kΩ to limit the current within a safe range.

[0085] Preferably, to improve the stability and anti-interference ability of the circuit, a capacitor, such as a 100nF ceramic capacitor, can be connected in parallel between resistors R7 and R8 to filter out high-frequency noise and reduce interference to the MCU_DETECT_ON / OFF pin. In addition, resistors R9 and R10 can be selected as metal film resistors with low temperature coefficients to reduce the impact of temperature changes on the circuit performance.

[0086] Furthermore, in practical applications, the resistance values of these resistors can also be fine-tuned according to the specific circuit operating conditions and the characteristics of the MCU. For example, if the circuit operates in a high-humidity environment, it may be necessary to appropriately increase the resistance values of resistors R7 and R8 to prevent signal accuracy from being affected by humidity-induced leakage. At the same time, to improve the reliability of the circuit, resistors with higher power ratings can be selected to handle possible transient overcurrent situations.

[0087] In some embodiments, the AC / DC converter converts the mains power into VCC24V_OUT to supply power to the power supply small board of the active equalization board.

[0088] It should be noted that the role of the AC / DC converter in this system is to convert the mains power into a stable DC power supply VCC24V_OUT to provide the necessary power for the power supply small board of the active equalization board. The AC / DC converter is a device in power electronics technology that can convert alternating current (such as household or industrial electricity) into direct current to meet the power supply requirements of electronic devices. In this system, the output voltage VCC24V_OUT of the AC / DC converter is specifically designed for the power supply small board to ensure that the active equalization board can obtain stable and continuous power supply.

[0089] Specifically, the design of the AC / DC converter needs to consider multiple key parameters, including the input voltage range, output voltage accuracy, output current capacity, conversion efficiency, and electromagnetic compatibility, etc. The input voltage range should cover the normal fluctuation range of the mains power, such as 180V to 260V, to adapt to different grid conditions. The output voltage accuracy should be controlled within ±5% to ensure the stable operation of the active equalization board. The output current capacity should be determined according to the maximum power consumption of the active equalization board. For example, if the maximum power consumption of the active equalization board is 100W, then the output current capacity should be at least 100W / 24V≈4.17A. The conversion efficiency should be as high as possible, generally higher than 85%, to reduce energy loss. The electromagnetic compatibility should meet the relevant international and national standards to reduce electromagnetic interference to surrounding devices.

[0090] Preferably, the AC / DC converter can adopt high-frequency switching technology, such as PWM (Pulse Width Modulation) control, to improve the conversion efficiency and reduce the device volume. For example, a PWM controller with a switching frequency of 100kHz to 500kHz can be used. In addition, to improve the stability and response speed of the output voltage, a voltage stabilizing circuit can be added at the output end, such as using a linear voltage regulator or an LDO (Low Dropout Linear Regulator).

[0091] Furthermore, in practical applications, the AC / DC converter can also be customized according to the specific usage environment and performance requirements. For example, if the system needs to be used outdoors, waterproof and dustproof protection measures should be considered; if the requirement for the ripple of the output voltage is high, the capacitance of the output filter capacitor can be increased or a multi-stage filtering circuit can be adopted. At the same time, to improve the reliability and safety of the system, overvoltage and overcurrent protection circuits can be added at the output end of the AC / DC converter to prevent abnormal conditions from damaging the active equalization board.

[0092] In some embodiments, the MCU of the BCU board communicates with the active equalization board through the CAN communication protocol, which is used to send control instructions and receive status information.

[0093] It should be noted that the MCU of the BCU board communicates with the active equalization board through the CAN communication protocol. This design enables the system to send control instructions and receive status information efficiently and reliably. The BCU board is the battery control unit board, and the MCU is the microcontroller unit, which is responsible for processing various signals and executing control logic. The CAN communication protocol is a serial communication protocol widely used in the automotive and industrial control fields. It allows multiple nodes to perform efficient and reliable data communication on the same bus. In this system, the MCU communicates with the active equalization board through the CAN communication protocol to achieve precise control and status monitoring of the active equalization board.

[0094] Specifically, the parameter settings of the CAN communication protocol include baud rate, data frame format, error detection mechanism, etc. For example, the baud rate can be selected as 250 kbps or 500 kbps, which depends on the requirements of the system for communication speed and reliability. The data frame format usually includes standard frames and extended frames. The identifier length of the standard frame is 11 bits, and the identifier length of the extended frame is 29 bits. The error detection mechanism includes bit error, stuffing error, CRC error, etc., and these mechanisms can ensure the accuracy of data transmission. In terms of hardware connection, the MCU of the BCU board needs to be connected to the CAN bus through a CAN transceiver, and the CAN transceiver converts the logic level of the MCU into the differential level signal of the CAN bus. For example, a CAN transceiver of the model TJA1050 can be used.

[0095] Preferably, in order to improve the reliability and anti-interference ability of communication, a terminal resistor can be added to the CAN bus, usually 120 Ω, to reduce signal reflection. In addition, a CAN transceiver with higher anti-interference ability can be selected, such as TJA1050, etc. In terms of software, an interrupt handling mechanism of the CAN communication protocol can be implemented in the MCU, so that when the status information of the active equalization board is received or a control instruction needs to be sent, it can respond in a timely manner. For example, the interrupt priority can be set to ensure that in emergency situations such as power-off detection, the MCU can give priority to processing related communication tasks.

[0096] Furthermore, in practical applications, the parameters of the CAN communication protocol can also be optimized according to the specific requirements of the system. For example, if the number of nodes in the system is large, the extended frame format can be selected to provide more identifier space; if the system has high requirements for real-time performance, the baud rate can be appropriately increased, but it should be noted that increasing the baud rate may reduce the reliability of communication. At the same time, in order to improve the flexibility and scalability of the system, a function of dynamically configuring CAN communication parameters can be implemented in the MCU, allowing users to customize parameters such as baud rate and data frame format according to different application scenarios.

[0097] In some embodiments, the CAN communication protocol is used to send a control instruction from the BCU to the active equalization board when power-off is detected, so as to ensure the safe shutdown of the bidirectional DC-DC.

[0098] It should be noted that the application of the CAN communication protocol in this system is to ensure that when a power failure is detected, the BCU can timely send control instructions to the active equalization board, thereby ensuring the safe shutdown of the bidirectional DC-DC converter. The power failure here refers to the situation where the system power supply voltage drops to a level insufficient to maintain normal operation. The BCU (Battery Control Unit) serves as the control center of the system. Through its built-in MCU (Micro Controller Unit), it monitors the power supply status and, when a power failure is detected, uses the CAN bus to send specific control instructions to the active equalization board. The bidirectional DC-DC converter is a power electronic device capable of realizing bidirectional energy conversion and is used for energy equalization among different battery cells in the battery pack. Its safe shutdown is crucial for protecting the battery and the converter itself.

[0099] Specifically, the parameter settings of the CAN communication protocol include baud rate, data frame format, error detection mechanism, etc. For example, the baud rate can be selected as 250 kbps or 500 kbps, which depends on the requirements of the system for communication speed and reliability. The data frame format usually includes standard frames and extended frames. The identifier length of the standard frame is 11 bits, and the identifier length of the extended frame is 29 bits. The error detection mechanism includes bit error, stuffing error, CRC error, etc., which can ensure the accuracy of data transmission.

[0100] More specifically, in terms of hardware connection, the MCU of the BCU board needs to be connected to the CAN bus through a CAN transceiver, and the CAN transceiver converts the logic level of the MCU into the differential level signal of the CAN bus. For example, CAN transceivers of models such as TJA1050 can be used. In addition, the setting of the power failure detection threshold needs to be determined according to the characteristics of the system power supply and the minimum operating voltage of the active equalization board. For example, if the system power supply cannot guarantee the normal operation of the active equalization board when the voltage drops to 20 V, then the power failure detection threshold can be set to 21 V.

[0101] Preferably, in order to improve the reliability and anti-interference ability of communication, a terminal resistor, usually 120 Ω, can be added to the CAN bus to reduce signal reflection. In addition, a CAN transceiver with higher anti-interference ability, such as TJA1050, can be selected. In terms of software, an interrupt handling mechanism for the CAN communication protocol can be implemented in the MCU. When the status information of the active equalization board is received or control instructions need to be sent, it can respond in a timely manner. For example, the interrupt priority can be set to ensure that the MCU can give priority to processing relevant communication tasks in emergency situations such as power failure detection.

[0102] Furthermore, in practical applications, the parameters of the CAN communication protocol can also be optimized according to the specific requirements of the system. For example, if there are a large number of nodes in the system, an extended frame format can be selected to provide more identifier space; if the system has high requirements for real-time performance, the baud rate can be appropriately increased, but it should be noted that increasing the baud rate may reduce the communication reliability. At the same time, to improve the flexibility and scalability of the system, the function of dynamically configuring CAN communication parameters can be implemented in the MCU, allowing users to customize parameters such as the baud rate and data frame format according to different application scenarios.

[0103] Furthermore, to ensure the safety of the system in extreme cases, an independent hardware watchdog circuit can be set on the active balancing board. If no control instruction or heartbeat signal from the MCU is received within a specified time, the hardware watchdog circuit will automatically trigger the safety shutdown procedure of the bidirectional DC-DC converter.

[0104] In some embodiments, the control instruction includes immediately shutting down the bidirectional DC-DC converter and, when the system resumes power supply, restarting the bidirectional DC-DC converter in the correct order.

[0105] It should be noted that the design of the control instruction is to ensure that in the case of power failure, the bidirectional DC-DC converter can be shut down according to a predetermined safety procedure and restarted in the correct order when the system resumes power supply. Here, the control instruction refers to a specific signal sent by the MCU of the BCU board to guide the operation of the bidirectional DC-DC converter on the active balancing board. The bidirectional DC-DC converter is a power electronic device that can realize bidirectional energy conversion and is used for energy balancing between different battery cells in the battery pack. In the case of power failure, immediately shutting down the converter is to prevent damage to the device, and restarting in the correct order is to ensure the safe and stable operation of the system after the power supply is restored.

[0106] Specifically, the sending and execution of the control instruction require precise timing control. The instruction to immediately shut down the bidirectional DC-DC converter can be sent within a few milliseconds after detecting the power failure signal. For example, the shutdown operation can be completed within 10 milliseconds to reduce the impact of power fluctuations caused by power failure on the converter. When the system resumes power supply, the order of restarting the bidirectional DC-DC converter needs to be determined according to the current state of the battery pack and the balancing requirements. For example, if the battery pack was in the charging balance state before the power failure, the DC-DC converter in the charging mode should be started first after the power supply is restored, and then other converters should be started gradually according to the battery voltage difference. In addition, the parameter settings of the control instruction include the priority of the instruction, the execution time window, etc., and these parameters need to be optimized according to the specific requirements of the system. For example, a specific instruction code, such as 0x01, can be defined to represent the immediate safe shutdown of the bidirectional DC-DC.

[0107] Preferably, to improve the reliability and security of the system, an error detection and correction mechanism, such as CRC (Cyclic Redundancy Check) code, can be added to the control instruction to ensure that the instruction is not tampered with or damaged during transmission. At the same time, an independent monitoring circuit can be set on the active equalization board to automatically turn off or start the bidirectional DC-DC converter according to the preset security policy in the case of MCU failure or communication interruption.

[0108] Furthermore, in practical applications, the execution logic of the control instruction can also be adjusted according to the operating environment of the system and the characteristics of the battery pack. For example, in high-temperature or low-temperature environments, the start-up and shutdown conditions of the bidirectional DC-DC converter may need to be adjusted to adapt to different working states. In addition, to improve the flexibility of the system, a configurable control instruction format can be designed to allow users to customize the specific content and execution order of the instruction according to different application scenarios. For example, different operation modes, such as fast start mode, energy-saving mode, etc., can be set through a software interface to meet the needs of different users.

[0109] The above-mentioned various embodiments of the present invention have the following beneficial effects: The active equalization control system can achieve energy equalization management of single cells in the battery pack. Through the connection of multiple active equalization boards and power supply small boards, as well as the collaborative work of the BCU board and the AC / DC converter, the performance consistency and security of the battery pack during charge and discharge are ensured. Specifically, the design of the power-off detection circuit and the switch circuit enables the system to detect and respond in a timely manner in the case of power supply anomalies. Through opto-isolation technology, the anti-interference ability and reliability of the system are improved. The addition of the super capacitor can provide short-term power support for the active equalization board at the moment of power-off, ensuring the safe shutdown of the bidirectional DC-DC converter and preventing equipment damage caused by sudden power-off. In addition, the application of the CAN communication protocol realizes efficient and reliable communication between the BCU board and the active equalization board, enabling control instructions to be transmitted timely and accurately, further improving the response speed and control accuracy of the system. When the system resumes power supply, restarting the bidirectional DC-DC converter in the correct order can ensure the stable operation of the system and extend the service life of the battery pack. At the same time, the system can also cut off the power supply of the active equalization board by controlling the switch circuit when active equalization is not required, thereby saving power consumption; when an abnormality occurs in the active equalization board, it can also cut off the power supply to the active equalization board by controlling the power supply, enhancing the reliability and security of the system.

[0110] Further, the storage medium according to the embodiments of the present application stores program instructions capable of implementing all of the above methods. Among them, the program instructions can be stored in the above storage medium in the form of a software product, including several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: various media that can store program codes such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc, or a terminal device such as a computer, a server, a mobile phone, or a tablet.

[0111] The above description is only some preferred embodiments of the present invention and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present invention is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features having similar functions disclosed in the embodiments of the present invention.

Claims

1. An active balancing control system, characterized in that, Including: Multiple active equalization boards, each active equalization board is connected to the active equalization board power supply small board through a power supply line; The active equalization board power supply small board includes a power-off detection circuit and a switch circuit for controlling the power supply of the active equalization board; The BCU board includes an MCU for receiving signals from the power-off detection circuit and controlling the power supply of the active equalization board; The AC / DC converter is connected to the mains power to provide a stable DC power supply for the system.

2. The active balancing control system according to claim 1, characterized in that The power-off detection circuit is connected to the MCU of the BCU board through the optocoupler U2 for transmitting the voltage status signal of VCC24V_OUT; The switch circuit is connected to the MCU of the BCU board through the optocoupler U3 for receiving the control signal of the MCU and controlling the power supply of the active equalization board.

3. The active balancing control system according to claim 2, wherein The power-off detection circuit includes: The voltage comparator U1 (TL431), its cathode is connected to the voltage dividing circuit composed of the resistors R1 and R2, the anode is connected to VCC24V_OUT, and the reference terminal (R) is grounded through the resistors R3 and R4; The PNP type triode Q1, its base is connected to the output terminal of U1, the collector is connected to the resistors R5 and the zener diode ZD1, and the emitter is grounded; The PMOS Q2, its source is connected to VCC24V_OUT, the drain is connected to the primary side light-emitting diode of the optocoupler U2, and the gate is connected to the collector of Q1; The optocoupler U2, its secondary side photosensitive triode is connected to VCC_5V and GND_BCU, and the output terminal is connected to MCU_DETECT_ON / OFF.

4. The active balancing control system according to claim 2, wherein The switch circuit includes: The PMOS Q3, its source is connected to VCC24V_IN, the drain is connected to VCC24V_OUT, and the gate is connected to the secondary side photosensitive triode of the optocoupler U3; The optocoupler U3, its primary side light-emitting diode is connected to the IO port of the MCU, and the secondary side photosensitive triode is connected to the gate of Q3; The super capacitor C1, its positive electrode is connected to VCC24V_BALANCE, and the negative electrode is connected to GND_BALANCE, for providing short-term power support for the active equalization board during power-off; The diode D1 is connected between VCC24V_BALANCE and the positive electrode of C1 for preventing reverse current.

5. The active balancing control system according to claim 3, characterized in that The power-off detection circuit further includes: The resistor R6 is connected between the drain of Q2 and the ground for current limiting.

6. The active balancing control system according to claim 4, characterized in that, The switch circuit further includes: The resistors R7 and R8 are connected between VCC_5V and MCU_DETECT_ON / OFF for current limiting and voltage dividing; The resistors R9 and R10 are connected between VCC24V_IN and GND_BALANCE for current limiting and voltage dividing; The resistor R11 is connected between the output of U3 and the ground for current limiting.

7. The active balancing control system according to claim 1, characterized in that The AC / DC converter converts the mains power into VCC24V_OUT to provide power for the active equalization board power supply small board.

8. The active balancing control system according to claim 1, wherein The MCU of the BCU board communicates with the active equalization board through the CAN communication protocol for sending control instructions and receiving status information.

9. The active balancing control system according to claim 8, wherein, The CAN communication protocol is used to send control instructions from the BCU to the active equalization board when power-off is detected to ensure the safe shutdown of the bidirectional DC-DC.

10. The active balancing control system according to claim 9, characterized in that, The control instructions include immediately turning off the bidirectional DC-DC converter and, when the system resumes power supply, restarting the bidirectional DC-DC converter in the correct order.

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