A super capacitor bidirectional converter circuit for 48v electric fork truck

Abstract

This utility model discloses a supercapacitor bidirectional converter circuit for 48V electric forklifts, comprising: a main control communication module, a power input protection module, a power conversion drive module, a signal acquisition and processing module, and a passive equalization circuit module. The main control communication module is connected to the power conversion drive module, the signal acquisition and processing module, and the passive equalization circuit module, while the power input protection module is connected to the power conversion drive module. Energy recovery efficiency is improved by employing a four-switch Buck-Boost topology, selecting low-loss MOSFETs and drive circuits; the passive equalization circuit combined with a BW6103 chip solves the supercapacitor equalization problem; and a CAN bus is integrated to achieve real-time communication with the vehicle controller, enabling intelligent collaborative management of energy recovery and auxiliary power supply, comprehensively improving efficiency, reliability, integration, cost-effectiveness, and intelligence level in electric forklift applications.

Description

Technical Field

[0001] This utility model belongs to the field of bidirectional converter technology, and relates to a supercapacitor bidirectional converter circuit for 48V electric forklifts. Background Technology

[0002] In the field of electric forklifts, energy efficiency and driving range are crucial performance indicators. Electric forklifts generate significant braking energy and potential energy during frequent starts, stops, accelerations, decelerations, and cargo lifting operations. Traditional electric forklifts typically dissipate this energy as heat, resulting in energy waste, reduced driving range, and increased battery strain.

[0003] Existing hardware circuits for bidirectional Buck-Boost converters using supercapacitor energy recovery in electric forklifts still face several challenges in practical applications. For example, energy recovery efficiency needs significant improvement; current technologies typically achieve around 70%-80% efficiency (based on market product data), leaving considerable room for enhancement. Size and weight also need further reduction for easier integration; current market offerings are still relatively large, hindering integration within the limited space of electric forklifts. Cost reduction is also crucial for large-scale application; the cost of the energy recovery system still represents a significant proportion of the overall cost of an electric forklift, limiting its widespread adoption in price-sensitive markets. Furthermore, the frequent start-stop and rapid acceleration / deceleration of electric forklifts place higher demands on the power density and response speed of the energy recovery system, areas where current technologies still have room for improvement and fail to fully leverage the high power density and rapid charging / discharging advantages of supercapacitors.

[0004] More importantly, existing energy recovery systems still have shortcomings in terms of intelligence and system integration. Electric forklifts are complex systems, and the energy recovery system needs to work collaboratively with the vehicle controller, motor controller, and other components to achieve optimal energy management. Traditional energy recovery systems typically lack effective communication interfaces and intelligent control strategies, making deep integration with the vehicle system difficult. This limits further improvements in energy recovery efficiency and system performance. Therefore, achieving intelligent and integrated energy recovery systems is a crucial direction for current technological development. Summary of the Invention

[0005] To address the problems existing in the background technology, this utility model proposes a supercapacitor bidirectional converter circuit for 48V electric forklifts.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a supercapacitor bidirectional converter circuit for a 48V electric forklift, comprising: a main control communication module, a power input protection module, a power conversion drive module, a signal acquisition and processing module, and a passive equalization circuit module.

[0007] The main control communication module is connected to the power conversion drive module, the signal acquisition and processing module, and the passive equalization circuit module, while the power input protection module is connected to the power conversion drive module.

[0008] The main control communication module includes: STM control chip U1, resistors R1, R2, R3, R4, R5, capacitors C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, inductors L1 and L2, diodes D1 and D2, diode array D3, and CAN transceiver chip U2.

[0009] One end of resistor R1 is connected to the external power supply VCC_3V3, and the other end of resistor R1 is connected to pin RST of the STM control chip U1 and one end of capacitor C6. The other end of capacitor C6 is connected to ground. The external power supply VCC_3V3 is connected to pin VDD of the STM control chip U1 and one end of inductor L1. The other end of inductor L1 is connected to one end of capacitor C10, pin VREF+ of the STM control chip U1, and pin VDDA of the STM control chip U1. The other end of capacitor C10 is connected to ground and the STM control chip... The U1 pin VSSA is connected, the STM control chip U1 pin 31 VSS is connected, the external power supply VCC_3V3 is connected to the STM control chip U1 pin 32 VDD, the external power supply VCC_3V3 is connected to the STM control chip U1 pin 48 VDD, the external power supply VCC_3V3 is connected to the STM control chip U1 pin 64 VDD, one end of the resistor R4 is connected to the STM control chip U1 pin PB8-BOOT0, and the other end of the resistor R4 is connected to the STM control chip U1 pin 63 VSS and ground.

[0010] The external power supply VCC_5V is connected to one end of capacitor C1 and the VCC pin of CAN transceiver chip U2. The other end of capacitor C1 is connected to ground. One end of resistor R2 is connected to the TXD pin of CAN transceiver chip U2, and the other end of resistor R2 is connected to the PB6 pin of STM control chip U1. One end of resistor R5 is connected to the RXD pin of CAN transceiver chip U2, and the other end of resistor R5 is connected to the PB5 pin of STM control chip U1. One end of capacitor C7 is connected to ground and the GND pin of CAN transceiver chip U2. The other end of capacitor C7... The terminal is connected to the VREF pin of the CAN transceiver chip U2. The CANH pin of the CAN transceiver chip U2 is connected to one end of capacitor C8, one end of resistor R3, and the first end of inductor L2. The CANL pin of the CAN transceiver chip U2 is connected to one end of capacitor C9, the other end of resistor R3, and the second end of inductor L2. The third end of inductor L2 is connected to one end of diode D1. The fourth end of inductor L2 is connected to one end of diode D2. The other end of capacitor C8 is connected to the other end of capacitor C9, the other end of diode D1, the other end of diode D2, and ground.

[0011] The external power supply VCC_3V3 is connected to one end of capacitor C2, one end of capacitor C3, one end of capacitor C4, and one end of capacitor C5. The other end of capacitor C2 is connected to the other end of capacitor C3, the other end of capacitor C4, the other end of capacitor C5, and ground.

[0012] One end of diode array D3 is connected to the external power supply VCC_3V3, and the other end of diode array D3 is connected to ground. The remaining TML_MOSBH pin, TML_MOSBL pin, TML_MOSAH pin, and TML_MOSAL pin are connected to the signal circuits that need to be protected.

[0013] The power input protection module includes: TVS diode D4, capacitor C11, transformer L3, resistor R6, inductor L4, capacitor C12, and resistor R7.

[0014] The input power supply VCC_IN is connected to one end of TVS diode D4, one end of capacitor C11, and the first end of transformer L3. The other end of TVS diode D4 is connected to the other end of capacitor C11, the second end of transformer L3, the other end of resistor R6, and -48V1 ground. The other end of resistor R6 is connected to PGND. The fourth end of transformer L3 is connected to one end of inductor L4, one end of capacitor C12, one end of resistor R7, and +48V_1 power supply. The third end of transformer L3 is connected to the other end of capacitor C12, the other end of resistor R7, and -48V2 ground.

[0015] TVS diode D1 provides overvoltage protection for the input power supply VCC_IN, capacitor C11 filters out high-frequency noise from the input; transformer L3 provides electrical isolation between the input and output, resistor R6 participates in the processing related to transformer L3; inductor L4 and capacitor C12 form an LC filter circuit to filter out output ripple, resistor R7 serves as load matching for the output, and finally outputs a stable +48V_1 power supply.

[0016] The power conversion drive module includes: fuse F1, fuse F2, diodes D5, D6, D7, D8, D9, D10, D11, and D12; capacitors C13, C14, C15, C16, C17, and C18; MOSFETs Q1, Q2, Q3, and Q4; inductor L5; driver chip U3 and U4; resistors R8, R9, R10, R11, R12, R13, R14, and R15; and power chips PW1 and PW2.

[0017] The input power supply VCC_24V is connected to one end of fuse F1. The other end of fuse F1 is connected to the input power supply VCC_IN, one end of diode D5, one end of capacitor C13, and the drain of MOSFET Q1. The source of MOSFET Q1 is connected to one end of resistor R8, the drain of MOSFET Q3, and one end of inductor L5. The gate of MOSFET Q1 is connected to the other end of resistor R8, one end of resistor R12, and one end of diode D8. The gate of MOSFET Q3 is connected to one end of resistor R9, one end of resistor R13, and one end of diode D9. The input power supply VCC_CAP is connected to one end of fuse F2. The other end of fuse F2 is connected to the input power supply VCC_B... One end of diode D6, one end of capacitor C14, and the drain of MOSFET Q2 are connected. The source of MOSFET Q2 is connected to one end of resistor R10, the drain of MOSFET Q4, and the other end of inductor L3. The gate of MOSFET Q2 is connected to the other end of resistor R10, one end of resistor R14, and one end of diode D11. The gate of MOSFET Q4 is connected to one end of resistor R11, one end of resistor R15, and one end of diode D12. The other end of diode D5 is connected to the other end of capacitor C13, the other end of resistor R9, the source of transistor Q3, ground, the other end of resistor R11, the source of transistor Q4, the other end of capacitor C14, and the other end of diode D6.

[0018] The other end of resistor R12 is connected to the other end of diode D8 and the HO pin of driver chip U3; the other end of resistor R13 is connected to the other end of diode D9 and the LO pin of driver chip U3; the VB pin of driver chip U3 is connected to one end of capacitor C16, one end of diode D7, and the +Vo pin of power chip PW1; the VS pin of driver chip U3 is connected to the other end of capacitor C16, the other end of diode D7, and the oV pin of power chip PW1; the VCC pin of driver chip U3 is connected to the input power supply VCC_12V and one end of capacitor C15; the GND pin of driver chip U3 is connected to ground and the other end of capacitor C15; the HIN pin of driver chip U3 is connected to the PB15 pin of STM control chip U1; the LIN pin of driver chip U3 is connected to the PB14 pin of STM control chip U1; the VIN pin of power chip PW1 is connected to the input power supply VCC_12V; and the GND pin of power chip PW1 is connected to ground.

[0019] The other end of resistor R14 is connected to the other end of diode D11 and the HO pin of driver chip U4; the other end of resistor R15 is connected to the other end of diode D12 and the LO pin of driver chip U4; the VB pin of driver chip U4 is connected to one end of capacitor C18, one end of diode D10, and the +Vo pin of power chip PW2; the VS pin of driver chip U4 is connected to the other end of capacitor C18, the other end of diode D10, and the oV pin of power chip PW2; the VCC pin of driver chip U4 is connected to the input power supply VCC_12V and one end of capacitor C17; the GND pin of driver chip U3 is connected to ground and the other end of capacitor C17; the HIN pin of driver chip U3 is connected to the PC6 pin of STM control chip U1; the LIN pin of driver chip U3 is connected to the PC7 pin of STM control chip U1; the VIN pin of power chip PW2 is connected to the input power supply VCC_12V; and the GND pin of power chip PW2 is connected to ground.

[0020] The drive circuit uses the EG3112 driver chip, with a 350ns dead time to balance safety and losses, and the reliability and safety of the drive circuit are improved by using an isolated power supply.

[0021] The signal acquisition and processing module includes: capacitors C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, C30, C31, and C32; operational amplifiers U5, U6, U7, U8, U9, and U10; and resistors R16, R17, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, R29, and R30.

[0022] One end of capacitor C19 is connected to the GND pin of operational amplifier U5, one end of capacitor C20 is connected to ground, and the other end of capacitor C19 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U5. The other end of capacitor C20 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U5. One end of resistor R16 is connected to the OUT pin of operational amplifier U5, and the other end of resistor R16 is connected to one end of capacitor C21 and the PC0 pin of STM control chip U1. The IN- pin of operational amplifier U5 is connected to ground, and the other end of capacitor C21 is connected to ground.

[0023] One end of capacitor C22 is connected to the GND pin of operational amplifier U6, one end of capacitor C23 is connected to ground, and the other end of capacitor C22 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U6. The other end of capacitor C23 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U6. One end of resistor R17 is connected to the OUT pin of operational amplifier U6, and the other end of resistor R17 is connected to one end of capacitor C24 and the PC1 pin of STM control chip U1. The IN- pin of operational amplifier U6 is connected to ground, and the other end of capacitor C24 is connected to ground.

[0024] One end of capacitor C25 is connected to the GND pin of operational amplifier U7, one end of capacitor C26 is connected to ground, the other end of capacitor C25 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U7, the other end of capacitor C26 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U7, one end of resistor R18 is connected to the OUT pin of operational amplifier U7, the other end of resistor R16 is connected to one end of capacitor C27 and the PC2 pin of STM control chip U1, the IN- pin of operational amplifier U7 is connected to ground, and the other end of capacitor C21 is connected to ground.

[0025] One end of resistor R20 is connected to one end of resistor R19 and the inverting input of operational amplifier U8. One end of resistor R21 is connected to one end of resistor R22 and the non-inverting input of operational amplifier U8. The other end of resistor R22 is connected to ground. The other end of resistor R19 is connected to the output of operational amplifier U8 and one end of resistor R23. The positive power supply pin of operational amplifier U8 is connected to the power input A_3V3. The negative power supply pin of operational amplifier U8 is connected to ground. The other end of resistor R23 is connected to the PC3 pin of STM control chip U1.

[0026] One end of resistor R24 ​​is connected to one end of resistor R27 and the inverting input of operational amplifier U9; one end of resistor R25 is connected to one end of resistor R26 and the non-inverting input of operational amplifier U9; the other end of resistor R26 is connected to ground; the other end of resistor R27 is connected to the output of operational amplifier U9 and one end of resistor R28; and the other end of resistor R23 is connected to the PA1 pin of STM control chip U1.

[0027] One end of resistor R29 is connected to power input A_3V3. The other end of resistor R29 is connected to one end of resistor R30, one end of capacitor C28, and the +IN pin of operational amplifier U10. The other end of resistor R30 is connected to ground, the other end of capacitor C28, one end of capacitor C29, and the V- pin of operational amplifier U10. The other end of capacitor C29 is connected to power input A_1V65, the -IN pin of operational amplifier U10, and the OUT pin of operational amplifier U10. The V+ pin of operational amplifier U10 is connected to power input A_3V3.

[0028] One end of capacitor C30 is connected to one end of capacitor C31, one end of capacitor C32, and power input A_1V65. The other end of capacitor C30 is connected to the other end of capacitor C31, the other end of capacitor C32, and ground.

[0029] The passive equalization circuit module is composed of multiple passive equalization circuits connected in parallel. The passive equalization circuit includes: resistor R31, resistor R32, resistor R33, resistor R34, resistor R35, capacitor C33, and supercapacitor charging protection chip U11.

[0030] One end of resistor R31 is connected to the input power supply, one end of capacitor C33, resistor R35, and the VDD pin of the supercapacitor charging protection chip U11. The other end of resistor R31 is connected to one end of resistor R32. The other end of resistor R32 is connected to one end of resistor R33. The other end of resistor R33 is connected to the drain of transistor Q5. The gate of transistor Q5 is connected to the IOUT pin of the capacitor charging protection chip U11 and one end of resistor R34. The source of transistor Q5 is connected to the other end of resistor R34 and the other end of capacitor C33.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This hardware circuit design is optimized for electric forklifts. It improves energy recovery efficiency by adopting a four-switch Buck-Boost topology, selecting low-loss MOSFETs and drive circuits; enhances robustness under harsh operating conditions through structural protection, wide-temperature components, and EMC design; achieves integration using high-power-density devices and multi-layer PCBs; selects cost-effective or domestically produced components and optimizes process control to control costs; uses a passive balancing circuit with a BW6103 chip to solve the supercapacitor balancing problem; and integrates a CAN bus to achieve real-time communication with the vehicle controller, enabling intelligent collaborative management of energy recovery and auxiliary power supply, comprehensively improving efficiency, reliability, integration, cost-effectiveness, and intelligence in electric forklift applications. Attached Figure Description

[0033] Figure 1 This is a circuit diagram of a supercapacitor bidirectional converter for a 48V electric forklift.

[0034] Figure 2 This is a circuit block diagram of a supercapacitor bidirectional converter for a 48V electric forklift according to this utility model.

[0035] Figure 3 This is the circuit connection diagram of the main control communication module of this utility model;

[0036] Figure 4 This is the circuit connection diagram of the power input protection module of this utility model;

[0037] Figure 5 This is the circuit connection diagram of the power conversion drive module of this utility model;

[0038] Figure 6 This is the circuit connection diagram of the signal acquisition and processing module of this utility model;

[0039] Figure 7 This is a connection diagram of the passive equalization circuit module of this utility model. Detailed Implementation

[0040] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0041] like Figures 1-7As shown, the technical solution adopted by this utility model is as follows: a supercapacitor bidirectional converter circuit for a 48V electric forklift, comprising: a main control communication module, a power input protection module, a power conversion drive module, a signal acquisition and processing module, and a passive equalization circuit module.

[0042] The main control communication module is connected to the power conversion drive module, the signal acquisition and processing module, and the passive equalization circuit module, while the power input protection module is connected to the power conversion drive module.

[0043] The main control communication module includes: STM control chip U1, resistors R1, R2, R3, R4, R5, capacitors C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, inductors L1 and L2, diodes D1 and D2, diode array D3, and CAN transceiver chip U2.

[0044] One end of resistor R1 is connected to the external power supply VCC_3V3, and the other end of resistor R1 is connected to pin RST of the STM control chip U1 and one end of capacitor C6. The other end of capacitor C6 is connected to ground. The external power supply VCC_3V3 is connected to pin VDD of the STM control chip U1 and one end of inductor L1. The other end of inductor L1 is connected to one end of capacitor C10, pin VREF+ of the STM control chip U1, and pin VDDA of the STM control chip U1. The other end of capacitor C10 is connected to ground and the STM control chip... The U1 pin VSSA is connected to the STM control chip U1 pin 31 VSS. The external power supply VCC_3V3 is connected to the STM control chip U1 pin 32 VDD. The external power supply VCC_3V3 is connected to the STM control chip U1 pin 48 VDD. The external power supply VCC_3V3 is connected to the STM control chip U1 pin 64 VDD. One end of the resistor R4 is connected to the STM control chip U1 pin PB8-BOOT0. The other end of the resistor R4 is connected to the STM control chip U1 pin 63 VSS and ground.

[0045] The external power supply VCC_5V is connected to one end of capacitor C1 and the VCC pin of CAN transceiver chip U2. The other end of capacitor C1 is connected to ground. One end of resistor R2 is connected to the TXD pin of CAN transceiver chip U2, and the other end of resistor R2 is connected to the PB6 pin of STM control chip U1. One end of resistor R5 is connected to the RXD pin of CAN transceiver chip U2, and the other end of resistor R5 is connected to the PB5 pin of STM control chip U1. One end of capacitor C7 is connected to ground and the GND pin of CAN transceiver chip U2. The other end of capacitor C7... The terminal is connected to the VREF pin of the CAN transceiver chip U2. The CANH pin of the CAN transceiver chip U2 is connected to one end of capacitor C8, one end of resistor R3, and the first end of inductor L2. The CANL pin of the CAN transceiver chip U2 is connected to one end of capacitor C9, the other end of resistor R3, and the second end of inductor L2. The third end of inductor L2 is connected to one end of diode D1. The fourth end of inductor L2 is connected to one end of diode D2. The other end of capacitor C8 is connected to the other end of capacitor C9, the other end of diode D1, the other end of diode D2, and ground.

[0046] The external power supply VCC_3V3 is connected to one end of capacitor C2, one end of capacitor C3, one end of capacitor C4, and one end of capacitor C5. The other end of capacitor C2 is connected to the other end of capacitor C3, the other end of capacitor C4, the other end of capacitor C5, and ground.

[0047] One end of diode array D3 is connected to the external power supply VCC_3V3, and the other end of diode array D3 is connected to ground. The remaining TML_MOSBH pin, TML_MOSBL pin, TML_MOSAH pin, and TML_MOSAL pin are connected to the signal circuits that need to be protected.

[0048] This circuit uses the STM control chip U1 as its core. Input signals are obtained through buttons, and a CAN bus interface circuit is implemented using a CAN transceiver, inductor, and protection diode to realize data communication. The power supply is filtered by capacitors to power each module. At the same time, the STM control chip U1 connects to peripherals through pins to complete signal processing, data communication, and peripheral control functions.

[0049] This hardware circuit design innovatively integrates a CAN bus interface circuit, enabling real-time communication and data exchange between the energy management system and external systems such as the electric forklift's overall controller and motor controller. The CAN bus interface circuit mainly includes a CAN transceiver chip, protection devices, a common-mode inductor, and a CAN bus connector. The CAN transceiver chip is responsible for transmitting and receiving CAN bus physical layer signals; the protection devices protect the CAN bus interface circuit from damage caused by overvoltage, surges, etc.; and the CAN bus connector is used to connect to the CAN bus network.

[0050] The CAN communication protocol and data content adopt the CAN 2.0B communication protocol, and define a custom data frame format and communication protocol to meet the application requirements of electric forklift energy management. Through the CAN bus, this invention can receive the following electric forklift operating status information: motor speed, motor torque, braking signal, accelerator pedal signal, battery SOC, vehicle voltage, and vehicle current. This invention can also send the following information to the vehicle controller or motor controller via the CAN bus: supercapacitor voltage, current, temperature, energy management system status, and fault information.

[0051] Example of a CAN communication data frame:

[0052] Data frame ID: 0x101 (Energy Management System Status Information);

[0053] Data field 1: Supercapacitor bank voltage (2 bytes, unit: mV);

[0054] Data field 2: Supercapacitor bank current (2 bytes, unit: mA);

[0055] Data field 3: Operating mode (1 byte, 0x01: Energy recovery mode, 0x02: Auxiliary power supply mode, 0x00: Standby mode);

[0056] Data field 4: Fault code (1 byte, 0x00: no fault, 0x01: overvoltage fault, 0x02: overcurrent fault);

[0057] Data frame ID: 0x201 (vehicle controller instruction);

[0058] Data field 1: Control command (1 byte, 0x01: Start energy recovery, 0x02: Start auxiliary power supply, 0x00: No command).

[0059] Intelligent Energy Management Strategy: Based on CAN bus communication, this invention can implement an intelligent energy management strategy, for example:

[0060] Intelligent energy recovery control: When the system receives a braking signal via the CAN bus, it automatically activates the energy recovery mode, controlling the bidirectional Buck-Boost converter to operate in Boost mode, storing regenerated energy in the supercapacitor bank. The energy recovery intensity can be dynamically adjusted according to the braking signal intensity and the supercapacitor bank status to maximize the recovery of braking energy.

[0061] Intelligent auxiliary power supply control: When the system receives an auxiliary power supply request via the CAN bus or detects that the battery voltage is too low, it automatically activates the auxiliary power supply mode, controlling the bidirectional Buck-Boost converter to operate in Buck mode, releasing energy from the supercapacitor bank to provide auxiliary power to the motor. The auxiliary power supply power and duration can be dynamically adjusted according to power demand and the status of the supercapacitor bank, minimizing the burden on the battery.

[0062] Intelligent energy feedback battery control: When the supercapacitor bank is fully charged and the battery's SOC is low, the system can feed energy from the supercapacitor bank back to the battery via a bidirectional Buck-Boost converter to charge the battery, further improving energy utilization efficiency. The energy feedback power can be dynamically adjusted according to the battery's SOC and the system status.

[0063] System status monitoring and fault diagnosis: The system can report its own status information to the vehicle controller in real time via the CAN bus, facilitating monitoring and management of the entire vehicle system. When the system detects a fault, it can send a fault alarm message via the CAN bus and take corresponding protective measures to improve system safety.

[0064] The power input protection module includes: TVS diode D4, capacitor C11, transformer L3, resistor R6, inductor L4, capacitor C12, and resistor R7.

[0065] The input power supply VCC_IN is connected to one end of TVS diode D4, one end of capacitor C11, and the first end of transformer L3. The other end of TVS diode D4 is connected to the other end of capacitor C11, the second end of transformer L3, the other end of resistor R6, and -48V1 ground. The other end of resistor R6 is connected to PGND. The fourth end of transformer L3 is connected to one end of inductor L4, one end of capacitor C12, one end of resistor R7, and +48V_1 power supply. The third end of transformer L3 is connected to the other end of capacitor C12, the other end of resistor R7, and -48V2 ground.

[0066] TVS diode D1 provides overvoltage protection for the input power supply VCC_IN, capacitor C11 filters out high-frequency noise from the input; transformer L3 provides electrical isolation between the input and output, resistor R16 participates in winding-related processing; inductor L4 and capacitor C12 form an LC filter circuit to filter out output ripple, resistor R7 serves as load matching for the output, and finally outputs a stable +48V_1 power supply.

[0067] Using a 15uH molded inductor reduces leakage inductance, thus lowering EMI and switching losses. The molded inductor employs a magnetic adhesive encapsulation structure, with the core completely encased in magnetic adhesive, resulting in extremely low leakage flux and effectively reducing electromagnetic interference and switching losses caused by leakage inductance. A saturation current of 30.5A and a DC resistance of 6.5mΩ meet the power requirements of the electric forklift while minimizing inductor losses. The saturation current determines the maximum current the inductor can withstand; 30.5A meets the current requirements of the electric forklift's energy recovery system at rated power, preventing inductor saturation. The DC resistance determines the inductor's DC losses, which can be reduced by... Calculations show that a low DC resistance of 6.5mΩ can effectively reduce inductor losses under DC current and improve conversion efficiency. The 15uH molded inductor has advantages such as high saturation current, low DC resistance, low leakage inductance, and low EMI, making it ideal for use in high-current, high-efficiency DC-DC converters.

[0068] Because MLCC capacitors exhibit DC bias characteristics, their capacitance decreases under high voltage. The dielectric constant of the ceramic dielectric in MLCC capacitors decreases under high DC voltage, leading to a drop in capacitance, especially noticeable in high-voltage MLCC capacitors. Therefore, in high-voltage applications, the impact of DC bias on MLCC capacitor capacitance must be considered. Thus, aluminum electrolytic capacitors with stable capacitance and high voltage ratings are chosen for input and output filtering. Aluminum electrolytic capacitors are less affected by DC bias and have high voltage ratings and large capacitance values, making them suitable for input and output filtering in DC-DC converters, effectively suppressing voltage ripple and noise. Since the DC-DC converter operates symmetrically in both directions, a symmetrical capacitor design is also adopted to ensure consistent filtering performance in both directions. Based on the 2% ripple voltage design specification and calculations using actual circuit parameters, the minimum capacitance values ​​required for the input and output terminals can be calculated. To allow for a certain margin and considering the tolerance range of aluminum electrolytic capacitors, three 220uF / 63V aluminum electrolytic capacitors connected in parallel are ultimately selected for both the input and output terminals. The 63V rated aluminum electrolytic capacitor was chosen to ensure sufficient safety margin under a 48V system voltage, thus avoiding the risk of capacitor breakdown. The 220uF aluminum electrolytic capacitor was selected based on ripple requirements and actual test results, which can meet filtering needs while controlling capacitor size and cost.

[0069] The power conversion drive module includes: fuses F1 and F2, diodes D5, D6, D7, D8, D9, D10, D11, and D12, capacitors C13, C14, C15, C16, C17, and C18, MOSFETs Q1, Q2, Q3, and Q4, inductor L5, driver chip U3 and U4, resistors R8, R9, R10, R11, R12, R13, R14, and R15, and power chips PW1 and PW2.

[0070] The input power supply VCC_24V is connected to one end of fuse F1. The other end of fuse F1 is connected to the input power supply VCC_IN, one end of diode D5, one end of capacitor C13, and the drain of MOSFET Q1. The source of MOSFET Q1 is connected to one end of resistor R8, the drain of MOSFET Q3, and one end of inductor L5. The gate of MOSFET Q1 is connected to the other end of resistor R8, one end of resistor R12, and one end of diode D8. The gate of MOSFET Q3 is connected to one end of resistor R9, one end of resistor R13, and one end of diode D9. The input power supply VCC_CAP is connected to one end of fuse F2. The other end of fuse F2 is connected to the input power supply VCC_B... One end of diode D6, one end of capacitor C14, and the drain of MOSFET Q2 are connected. The source of MOSFET Q2 is connected to one end of resistor R10, the drain of MOSFET Q4, and the other end of inductor L3. The gate of MOSFET Q2 is connected to the other end of resistor R10, one end of resistor R14, and one end of diode D11. The gate of MOSFET Q4 is connected to one end of resistor R11, one end of resistor R15, and one end of diode D12. The other end of diode D5 is connected to the other end of capacitor C13, the other end of resistor R9, the source of transistor Q3, ground, the other end of resistor R11, the source of transistor Q4, the other end of capacitor C14, and the other end of diode D6.

[0071] The other end of resistor R12 is connected to the other end of diode D8 and the HO pin of driver chip U3. The other end of resistor R13 is connected to the other end of diode D9 and the LO pin of driver chip U3. The VB pin of driver chip U3 is connected to one end of capacitor C16, one end of diode D7, and the +Vo pin of power supply chip PW1. The VS pin of driver chip U3 is connected to the other end of capacitor C16, the other end of diode D7, and the oV pin of power supply chip PW1. The VCC pin of driver chip U3 is connected to the input power supply VCC_12V and one end of capacitor C15. The GND pin of driver chip U3 is connected to ground and the other end of capacitor C15. The HIN pin of driver chip U3 is connected to the PB15 pin of STM control chip U1. The LIN pin of driver chip U3 is connected to the PB14 pin of STM control chip U1. The VIN pin of power supply chip PW1 is connected to the input power supply VCC_12V. The GND pin of power supply chip PW1 is connected to ground.

[0072] The other end of resistor R14 is connected to the other end of diode D11 and the HO pin of driver chip U4. The other end of resistor R15 is connected to the other end of diode D12 and the LO pin of driver chip U4. The VB pin of driver chip U4 is connected to one end of capacitor C18, one end of diode D10, and the +Vo pin of power chip PW2. The VS pin of driver chip U4 is connected to the other end of capacitor C18, the other end of diode D10, and the oV pin of power chip PW2. The VCC pin of driver chip U4 is connected to the input power supply VCC_12V and one end of capacitor C17. The GND pin of driver chip U3 is connected to ground and the other end of capacitor C17. The HIN pin of driver chip U3 is connected to the PC6 pin of STM control chip U1. The LIN pin of driver chip U3 is connected to the PC7 pin of STM control chip U1. The VIN pin of power chip PW2 is connected to the input power supply VCC_12V. The GND pin of power chip PW2 is connected to ground.

[0073] The MOSFET selected is a BSC070N10NS5-MOSFET, which has a 100V withstand voltage suitable for 48V systems, an 80A current rating to meet power requirements, and a 7mΩ on-resistance. It can be concluded that reducing conduction losses can be achieved by using Trench-MOSFET and Shielded-Gate technology to reduce both conduction and switching losses.

[0074] The drive circuit uses the EG3112 driver chip, which has a 600V withstand voltage and a 2.5A output to quickly drive the MOSFET, shortening the switching time to reduce switching losses. The switching waveform is optimized by adjusting the drive resistor and voltage. A 350ns dead time is set to balance safety and losses, and the reliability and safety of the drive circuit are improved by using an isolated power supply.

[0075] Power Device Selection: The BSC070N10NS5-MOSFET was chosen primarily because its 100V voltage rating meets the requirements of a 48V system, its 80A maximum current meets the power requirements of the electric forklift, and its low 7mΩ on-resistance helps reduce conduction losses and improve efficiency. This is because the on-resistance of a MOSFET is mainly determined by the on-resistance and the square of the current. Calculations show that lower on-resistance means lower conduction losses and higher efficiency at the same current. The TDSON-8-EP package facilitates heat dissipation because it uses PowerPAK packaging technology with exposed thermal pads that can directly contact the PCB board or heat sink, effectively dissipating the heat generated by the MOSFET, reducing the junction temperature of the MOSFET, and improving the reliability and lifespan of the device. The BSC070N10NS5-MOSFET is an advanced power MOSFET that uses Trench-MOSFET and Shielded-Gate technologies. It features extremely low on-resistance and extremely low gate charge, achieving extremely low conduction and switching losses. It maintains excellent efficiency in high-frequency switching applications and is very suitable for high-efficiency DC-DC converters, especially in applications with high efficiency requirements such as electric forklifts.

[0076] Driver circuit design: The EG3112 driver chip was chosen because its 600V voltage margin is sufficient, and its 2.5A output current capability can quickly drive the MOSFET. Fast MOSFET driving shortens the MOSFET's switching time, thereby reducing MOSFET switching losses. It can be calculated that improving conversion efficiency; the purpose of fine-tuning the drive waveform is to optimize the switching process, reduce switching losses and EMI. By adjusting the drive resistor and drive voltage, the switching waveform of the MOSFET can be optimized, for example, reducing voltage spikes and oscillations, and reducing switching losses and electromagnetic interference; the 350ns dead time is a trade-off between efficiency and safety. Too short a dead time may cause the upper and lower bridge arm MOSFETs to conduct simultaneously, resulting in a bridge arm short circuit risk. Too long a dead time will increase dead time losses and reduce efficiency. The 350ns dead time minimizes dead time losses as much as possible while ensuring safety; the purpose of isolated power supply is to improve the reliability and safety of the drive circuit. The isolated drive power supply can isolate the drive circuit from the main power circuit, preventing the failure of the main power circuit from affecting the drive circuit, and improving the system's anti-interference capability and safety. The EG3112 is a high-performance half-bridge gate driver with high drive capability, adjustable dead time, input-output isolation, etc. It can provide reliable and efficient drive for MOSFETs and has comprehensive protection functions, making it very suitable for use in high-efficiency and high-reliability DC-DC converters.

[0077] The signal acquisition and processing module includes: capacitors C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, C30, C31, and C32; operational amplifiers U5, U6, U7, U8, U9, and U10; and resistors R16, R17, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, R29, and R30.

[0078] One end of capacitor C19 is connected to the GND pin of operational amplifier U5, one end of capacitor C20 is connected to ground, and the other end of capacitor C19 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U5. The other end of capacitor C20 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U5. One end of resistor R16 is connected to the OUT pin of operational amplifier U5, and the other end of resistor R16 is connected to one end of capacitor C21 and the PC0 pin of STM control chip U1. The IN- pin of operational amplifier U5 is connected to ground, and the other end of capacitor C21 is connected to ground.

[0079] One end of capacitor C22 is connected to the GND pin of operational amplifier U6, one end of capacitor C23 is connected to ground, and the other end of capacitor C22 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U6. The other end of capacitor C23 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U6. One end of resistor R17 is connected to the OUT pin of operational amplifier U6, and the other end of resistor R17 is connected to one end of capacitor C24 and the PC1 pin of STM control chip U1. The IN- pin of operational amplifier U6 is connected to ground, and the other end of capacitor C24 is connected to ground.

[0080] One end of capacitor C25 is connected to the GND pin of operational amplifier U7, one end of capacitor C26 is connected to ground, and the other end of capacitor C25 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U7. The other end of capacitor C26 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U7. One end of resistor R18 is connected to the OUT pin of operational amplifier U7. The other end of resistor R16 is connected to one end of capacitor C27 and the PC2 pin of STM control chip U1. The IN- pin of operational amplifier U7 is connected to ground, and the other end of capacitor C21 is connected to ground.

[0081] One end of resistor R20 is connected to one end of resistor R19 and the inverting input of operational amplifier U8. One end of resistor R21 is connected to one end of resistor R22 and the non-inverting input of operational amplifier U8. The other end of resistor R22 is connected to ground. The other end of resistor R19 is connected to the output of operational amplifier U8 and one end of resistor R23. The positive power supply pin of operational amplifier U8 is connected to the power input A_3V3. The negative power supply pin of operational amplifier U8 is connected to ground. The other end of resistor R23 is connected to the PC3 pin of STM control chip U1.

[0082] One end of resistor R24 ​​is connected to one end of resistor R27 and the inverting input of operational amplifier U9. One end of resistor R25 is connected to one end of resistor R26 and the non-inverting input of operational amplifier U9. The other end of resistor R26 is connected to ground. The other end of resistor R27 is connected to the output of operational amplifier U9 and one end of resistor R28. The other end of resistor R23 is connected to the PA1 pin of STM control chip U1.

[0083] One end of resistor R29 is connected to power input A_3V3. The other end of resistor R29 is connected to one end of resistor R30, one end of capacitor C28, and the +IN pin of operational amplifier U10. The other end of resistor R30 is connected to ground, the other end of capacitor C28, one end of capacitor C29, and the V- pin of operational amplifier U10. The other end of capacitor C29 is connected to power input A_1V65, the -IN pin of operational amplifier U10, and the OUT pin of operational amplifier U10. The V+ pin of operational amplifier U10 is connected to power input A_3V3.

[0084] One end of capacitor C30 is connected to one end of capacitor C31, one end of capacitor C32, and power input A_1V65. The other end of capacitor C30 is connected to the other end of capacitor C31, the other end of capacitor C32, and ground.

[0085] This circuit performs differential acquisition and conditioning of the current signal through an amplifier. It uses an operational amplifier with resistors and capacitors to form an amplification and filtering circuit to divide, amplify, and filter the input voltage signal. Finally, it outputs the conditioned current and voltage signals to the ADC port to provide adaptation signals for subsequent data acquisition.

[0086] The passive equalization circuit module consists of multiple passive equalization circuits connected in parallel. The passive equalization circuit includes: resistors R31, R32, R33, R34, and R35, capacitor C33, and supercapacitor charging protection chip U11.

[0087] One end of resistor R31 is connected to the input power supply, one end of capacitor C33, resistor R35, and the VDD pin of the supercapacitor charging protection chip U11. The other end of resistor R31 is connected to one end of resistor R32. The other end of resistor R32 is connected to one end of resistor R33. The other end of resistor R33 is connected to the drain of transistor Q5. The gate of transistor Q5 is connected to the IOUT pin of the capacitor charging protection chip U11 and one end of resistor R34. The source of transistor Q5 is connected to the other end of resistor R34 and the other end of capacitor C33.

[0088] The equalization circuit topology adopts a passive equalization circuit topology based on bleed resistors. The principle of the passive equalization circuit is to slowly discharge the charge on the supercapacitor cell with higher voltage by connecting bleed resistors in parallel across each supercapacitor cell, thereby achieving voltage equalization.

[0089] A passive balancing circuit topology based on bleed resistors is adopted. The principle of the passive balancing circuit is to slowly discharge the charge on the higher-voltage supercapacitor cells by connecting bleed resistors in parallel across each cell, thereby achieving voltage equalization. The advantages are simple circuit structure and low cost. The passive balancing circuit requires only a few discrete components, making it very simple in structure, low in cost, and easy to implement. The principle is that for cells with higher voltage, a controllable MOSFET and series resistor are used to discharge the higher-voltage cells, aligning the voltage of the high-voltage cells with the low-voltage cells. The disadvantage is lower energy utilization. During the equalization process, the energy on the high-voltage cells is dissipated as heat, resulting in low energy utilization. It is suitable for applications where the voltage difference between supercapacitor cells is small and the equalization current is small.

[0090] Hardware Implementation of Equalization Control: The BW6103 supercapacitor charging protection chip is used as the core of the equalization control. The BW6103 is a dedicated charging protection chip for supercapacitor banks, integrating voltage detection and passive equalization control functions. It features individual overvoltage protection and passive equalization control, boasting high integration and simple peripheral circuitry, making it ideal for building low-cost passive equalization circuits. Compared to active equalization circuits or integrated equalization chip solutions, passive equalization circuits offer significant advantages such as extremely simple circuit structure, extremely low material costs, and high design flexibility, making them highly suitable for cost-sensitive electric forklift applications. Each supercapacitor cell is equipped with an independent overvoltage protection circuit based on the BW6103, enabling overvoltage protection for each cell and improving the safety of the supercapacitor bank. The BW6103 chip integrates basic passive equalization control functions, controlling external bleeder MOSFETs and bleeder resistors for passive equalization based on a set equalization threshold. This minimizes the cost and complexity of the equalization circuit while ensuring basic equalization performance. Although the equalization speed and accuracy of passive equalization circuits are relatively limited, for applications such as electric forklifts with relatively mild operating conditions and for market demands that are highly sensitive to cost, passive equalization circuit solutions based on BW6103 and discrete components are still a very economical and practical choice.

[0091] To fully leverage the advantages of synchronous rectification technology, this solution employs a higher switching frequency. Increasing the switching frequency shortens the switching cycle, resulting in a higher effective conduction time proportion for the synchronous rectification MOSFET within the same dead time. This leads to better synchronous rectification and a more significant efficiency improvement. Synchronous rectification technology replaces the freewheeling diode with a MOSFET, utilizing the MOSFET's low on-resistance to reduce the conduction losses of the freewheeling device and improve conversion efficiency. This is particularly evident in applications with low output voltage and high current, where the efficiency improvement is even more pronounced. Increasing the switching frequency also reduces the size of the inductor and capacitor, increasing power density, while simultaneously shortening the switching cycle, providing a longer conduction time for the synchronous rectification MOSFET and fully utilizing its advantages. The bidirectional BUCK-BOOST topology itself has high efficiency; combined with synchronous rectification technology and a high switching frequency, it can further enhance conversion efficiency. This is especially crucial in applications with extremely high efficiency requirements, such as energy recovery in electric forklifts.

[0092] Energy recovery mode workflow: When the electric forklift is braking, decelerating, or going downhill, the motor operates as a generator, producing regenerative energy. The vehicle controller sends a braking signal to this energy management system via the CAN bus. Upon receiving the braking signal, this system controls the bidirectional Buck-Boost converter to operate in Boost mode, transferring the regenerative energy generated by the motor from the DC bus side to the supercapacitor bank side for storage. The energy flow path is: Motor → Bidirectional Inverter / Rectifier → DC Bus → Bidirectional Buck-Boost Converter → Supercapacitor Bank. This maximizes energy recovery efficiency and stores the recovered energy in the supercapacitors, preparing for subsequent auxiliary power supply or energy feedback batteries.

[0093] Auxiliary power supply mode workflow: When the electric forklift is in operation such as starting, accelerating, or heavy-load climbing, requiring high power output, or when the battery voltage is too low, the vehicle controller sends an auxiliary power supply request to this energy management system via the CAN bus. Upon receiving the auxiliary power supply request, this system controls the bidirectional Buck-Boost converter to operate in Buck mode, releasing the energy stored in the supercapacitor bank and transmitting it to the DC bus side. This energy is then connected in parallel with the battery to provide auxiliary power to the motor, sharing the battery's peak power demand. The energy flow path is: supercapacitor bank → bidirectional Buck-Boost converter → DC bus → bidirectional inverter / rectifier → motor. The auxiliary power supply power and duration can be dynamically adjusted according to actual needs and the supercapacitor bank status, minimizing battery load, extending battery life, and improving system dynamic performance.

[0094] All components, including capacitors, resistors, and connectors, are automotive-grade. Compared to industrial and consumer-grade components, automotive-grade components offer a wider operating temperature range, higher reliability, and longer lifespan, enabling them to meet the operational needs of electric forklifts in various harsh environments. For example, automotive-grade capacitors typically use special electrolytes and encapsulation materials to ensure the stability of capacitance and ESR under high and low temperature conditions; automotive-grade resistors typically use high-precision resistive films and protective layers to ensure the stability and reliability of resistance under temperature changes and vibration shocks; and automotive-grade connectors typically use high-quality metal and insulating materials to ensure reliable connections and sealing in harsh environments.

[0095] The PCB board is secured with four screws, providing a reliable mechanical connection and preventing loosening and detachment under vibration and impact. Thermally conductive silicone padding at the bottom effectively absorbs vibration. This silicone has excellent elasticity and damping properties, absorbing and buffering vibration and impact energy, reducing the force exerted on the PCB board. It also has thermal conductivity, aiding in heat dissipation. Automotive-grade vibration-resistant connectors are used, employing a special locking mechanism and contact structure to ensure reliable connections under vibration and impact, preventing signal and power interruptions. Cables are secured with cable clips and protected by corrugated tubing. Cable clips secure the cables to the housing or bracket, preventing movement and wear under vibration and impact. Corrugated tubing provides additional mechanical protection, preventing external mechanical damage and environmental corrosion. This vibration-resistant structural design effectively improves the reliability and stability of the hardware circuitry under the vibration and impact of electric forklifts, reducing the failure rate caused by vibration.

[0096] The layout of power devices and drive circuits primarily aims to minimize the loop area of ​​the drive and power circuits. This is achieved through methods such as using a common ground plane, optimizing device placement, and shortening trace lengths. Reducing the loop area of ​​the drive and power circuits decreases the inductance of the circuits, thereby reducing switching noise and EMI. Analog and digital circuits are isolated using ferrite beads, which effectively suppress high-frequency noise and prevent noise from digital circuits from interfering with sensitive analog circuits. Zero-ohm resistors are used to connect different analog and digital grounds. These resistors connect the analog and digital grounds together on DC, ensuring a consistent reference potential, and also provide some isolation on AC, reducing ground loops. To minimize noise, sensitive signal lines are kept away from noise sources. This reduces noise coupling and improves signal quality. The loop areas of power loops, control loops, and high-frequency current loops are minimized. Reducing loop area decreases loop inductance, lowering switching noise and EMI. Critical signal lines use differential routing, which effectively suppresses common-mode noise and improves signal immunity. The EMC filter circuit design meets system electromagnetic compatibility requirements, effectively suppressing conducted and radiated EMI and meeting automotive-grade CISPR25 EMC standards. These low-EMI hardware circuit designs effectively suppress electromagnetic interference generated by the hardware circuits, improving system electromagnetic compatibility and meeting the electromagnetic environment requirements of electric forklifts.

[0097] For environments with dust and humidity, such as those encountered by electric forklifts, the PCB is completely immersed in nano-level conformal coating. This nano-level coating possesses excellent insulation, moisture resistance, mildew resistance, salt spray resistance, corrosion resistance, and temperature resistance. It completely seals the PCB, isolating it from external environmental corrosion and forming a protective film that achieves IP6X standard protection against fine dust. IP6X dustproof rating means complete protection against dust ingress, achieving an IP67 protection level. IP67 waterproof rating means it can be immersed in water for a certain period or under water pressure without damage. It passes the ASTM B117 salt spray test, which simulates the corrosive effects of salt spray on materials and products, verifying the product's resistance to salt spray corrosion. The outer shell, sealing ring, and waterproof connectors achieve an IP68 waterproof rating. IP68 waterproof rating means it can be immersed in water under certain pressure for an extended period without damage. This protective design effectively protects the hardware circuitry for reliable operation in harsh environments such as those encountered by electric forklifts, including dust, humidity, and salt spray, improving the system's environmental adaptability and lifespan.

[0098] The heat sink uses an extruded aluminum heat sink, which has excellent thermal conductivity and heat dissipation performance. Heat can be dissipated through natural convection and forced air cooling. Thermal grease is used between the heat sink and the power PCB. This grease fills the tiny gaps between the heat sink and the power devices, reducing contact thermal resistance and improving heat transfer efficiency. A combination of natural and forced air cooling is employed. Natural cooling is suitable for low power density and low ambient temperature applications, while forced air cooling is suitable for high power density and high ambient temperature applications. This combination balances heat dissipation performance and power consumption. The heat dissipation design ensures that the temperature rise of the hardware circuitry is controlled within a safe range under the most severe operating conditions of the electric forklift and the ambient temperature, and that the junction temperature of the power devices does not exceed the rated value. A reasonable heat dissipation design is crucial for ensuring the reliable operation of the hardware circuitry under harsh conditions. Through the above heat dissipation structure design, the heat generated by the hardware circuitry can be effectively dissipated, keeping the temperature rise of the control devices within a safe range and ensuring the long-term reliable operation of the system.

[0099] Increasing the switching frequency can reduce the size of inductors and capacitors. In DC-DC converters, the size of inductors and capacitors is inversely proportional to the switching frequency. Increasing the switching frequency reduces the inductance and capacitance values, thereby reducing device size and increasing power density. Using a special PCB board with a surface copper thickness of 2oz can improve the PCB's current carrying capacity, reduce PCB trace resistance, lower losses, and enhance heat dissipation. A thicker copper layer can carry a larger current, reducing PCB trace resistance and power loss. Simultaneously, a thicker copper layer also has better thermal conductivity, aiding in heat dissipation. Special PCB materials may use high thermal conductivity substrates or employ special structures such as embedded copper or heat spreaders to improve PCB heat dissipation performance and further increase power density. Optimizing component layout involves distributing and modularizing heat sources, separating and stacking the power board and main control board. Distributing heat sources prevents heat concentration and improves heat dissipation efficiency; modularization groups similar components together for easier wiring and debugging; and separating and stacking the power board and main control board reduces PCB area, improves space utilization, and reduces overall size. This significantly reduces circuit board area and volume, increases power density, and facilitates integration within the limited space of electric forklifts. Through this high-power-density circuit design, the size and weight of hardware circuitry can be effectively reduced while maintaining performance, increasing power density and meeting the miniaturization and lightweight requirements of electric forklifts.

[0100] The main control board, power board, and supercapacitor equalization board feature a modular design that breaks down complex functions into multiple independent modules. Each module performs a specific function, and the modules connect via standardized interfaces. This improves design flexibility and maintainability, enhances product reusability, and allows different products to share the same modules, reducing redundant design and increasing product versatility and scalability. Module interfaces utilize pin connections and connectors, which offer advantages such as reliable connection, easy disassembly, and convenient maintenance. This facilitates production and maintenance, improves reliability, and allows for easy integration with other electric forklift components. The modular integration solution simplifies hardware circuit design and production, improves product reliability and maintainability, facilitates integration with other electric forklift components, and reduces costs.

[0101] Lightweight aluminum alloy heat sinks are selected. Aluminum alloy has excellent thermal conductivity and low density, which reduces weight compared to copper heat sinks. The optimized lightweight design of structural components reduces unnecessary structural parts, minimizing weight while maintaining structural strength and functionality. Miniaturized components and packaging, along with integrated design, reduce the number of components and connectors. Miniaturized components and packaging reduce the size and weight of components; integrated design reduces the number of components and connectors, thus reducing overall weight by 10%. Through these lightweight design measures, the weight of hardware circuitry can be effectively reduced while maintaining performance and reliability, meeting the lightweight requirements of electric forklifts and improving vehicle handling and energy efficiency.

[0102] While meeting performance and reliability requirements, priority should be given to selecting lower-priced device models and actively replacing imported devices with domestically produced ones. Domestically produced devices are continuously improving in performance and quality, with some already comparable to or even surpassing imported devices in certain aspects, while typically being cheaper. Using domestically produced devices can effectively reduce costs and enhance product competitiveness, such as the EG3112 half-bridge driver. For example, in MOSFET selection, products from domestic MOSFET manufacturers such as CR Microelectronics and Silan Microelectronics can be prioritized, as their products have advantages in both performance and price. Similarly, in capacitor and resistor selection, products from domestic capacitor and resistor manufacturers such as Fenghua Advanced Technology and Yuyang Technology can be prioritized, as their products are also competitive in terms of quality and price.

[0103] While ensuring efficiency and power density meet the application requirements of electric forklifts, this solution innovatively adopts a four-switch Buck-Boost topology. Compared to the traditional full-bridge topology, the four-switch Buck-Boost topology achieves a better balance between component count and control complexity, ensuring high efficiency while effectively reducing cost and size. It employs mature and reliable circuit solutions to reduce design risks and R&D costs, optimizes control circuit design to simplify control logic and hardware implementation, and uses standardized circuit modules and interfaces to improve versatility and reduce customization costs. Using mature and reliable circuit solutions reduces design verification and debugging time, lowering R&D risks; optimizing control circuit design simplifies controller hardware and software implementation, reducing controller costs; and using standardized circuit modules and interfaces improves product versatility and interchangeability, reducing customization and maintenance costs.

[0104] Modular design can improve the versatility and standardization of components, enabling large-scale production and reducing procurement and manufacturing costs. It can also simplify product design and production processes, shorten R&D and production cycles, and lower R&D and production costs. Furthermore, modular design facilitates product upgrades and maintenance, reducing maintenance and lifecycle costs. Finally, it can improve product quality and reliability, and lower after-sales service costs. The cost advantages of modular design are multifaceted, reducing costs across multiple stages, including component procurement, manufacturing, R&D, and after-sales maintenance, thereby enhancing product market competitiveness.

[0105] In terms of supercapacitor bank equalization management, this solution innovatively adopts a passive equalization circuit based on the BW6103 chip and discrete components. Compared with active equalization circuits or integrated equalization chip solutions, passive equalization circuits have significant advantages such as extremely simple circuit structure, extremely low material cost, and high design flexibility. While ensuring basic equalization effect and supercapacitor bank safety, it minimizes the cost and complexity of the equalization circuit, making it very suitable for cost-sensitive electric forklift applications, further reducing the overall cost of the energy recovery system.

[0106] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A supercapacitor bidirectional converter circuit for a 48V electric forklift, characterized in that, It includes: main control communication module, power input protection module, power conversion drive module, signal acquisition and processing module, and passive equalization circuit module; The main control communication module is connected to the power conversion drive module, the signal acquisition and processing module, and the passive equalization circuit module; the power input protection module is connected to the power conversion drive module. The power conversion drive module includes: fuse F1, fuse F2, diodes D5, D6, D7, D8, D9, D10, D11, and D12; capacitors C13, C14, C15, C16, C17, and C18; MOSFETs Q1, Q2, Q3, and Q4; inductor L5; driver chip U3 and U4; resistors R8, R9, R10, R11, R12, R13, R14, and R15; and power chips PW1 and PW2. The input power supply VCC_24V is connected to one end of fuse F1. The other end of fuse F1 is connected to the input power supply VCC_IN, one end of diode D5, one end of capacitor C13, and the drain of MOSFET Q1. The source of MOSFET Q1 is connected to one end of resistor R8, the drain of MOSFET Q3, and one end of inductor L5. The gate of MOSFET Q1 is connected to the other end of resistor R8, one end of resistor R12, and one end of diode D8. The gate of MOSFET Q3 is connected to one end of resistor R9, one end of resistor R13, and one end of diode D9. The input power supply VCC_CAP is connected to one end of fuse F2. The other end of fuse F2 is connected to the input power supply VCC_B... One end of diode D6, one end of capacitor C14, and the drain of MOSFET Q2 are connected. The source of MOSFET Q2 is connected to one end of resistor R10, the drain of MOSFET Q4, and the other end of inductor L3. The gate of MOSFET Q2 is connected to the other end of resistor R10, one end of resistor R14, and one end of diode D11. The gate of MOSFET Q4 is connected to one end of resistor R11, one end of resistor R15, and one end of diode D12. The other end of diode D5 is connected to the other end of capacitor C13, the other end of resistor R9, the source of transistor Q3, ground, the other end of resistor R11, the source of transistor Q4, the other end of capacitor C14, and the other end of diode D6. The other end of resistor R12 is connected to the other end of diode D8 and the HO pin of driver chip U3; the other end of resistor R13 is connected to the other end of diode D9 and the LO pin of driver chip U3; the VB pin of driver chip U3 is connected to one end of capacitor C16, one end of diode D7, and the +Vo pin of power chip PW1; the VS pin of driver chip U3 is connected to the other end of capacitor C16, the other end of diode D7, and the oV pin of power chip PW1; the VCC pin of driver chip U3 is connected to the input power supply VCC_12V and one end of capacitor C15; the GND pin of driver chip U3 is connected to ground and the other end of capacitor C15; the HIN pin of driver chip U3 is connected to the PB15 pin of STM control chip U1; the LIN pin of driver chip U3 is connected to the PB14 pin of STM control chip U1; the VIN pin of power chip PW1 is connected to the input power supply VCC_12V; and the GND pin of power chip PW1 is connected to ground. The other end of resistor R14 is connected to the other end of diode D11 and the HO pin of driver chip U4; the other end of resistor R15 is connected to the other end of diode D12 and the LO pin of driver chip U4; the VB pin of driver chip U4 is connected to one end of capacitor C18, one end of diode D10, and the +Vo pin of power chip PW2; the VS pin of driver chip U4 is connected to the other end of capacitor C18, the other end of diode D10, and the oV pin of power chip PW2; the VCC pin of driver chip U4 is connected to the input power supply VCC_12V and one end of capacitor C17; the GND pin of driver chip U3 is connected to ground and the other end of capacitor C17; the HIN pin of driver chip U3 is connected to the PC6 pin of STM control chip U1; the LIN pin of driver chip U3 is connected to the PC7 pin of STM control chip U1; the VIN pin of power chip PW2 is connected to the input power supply VCC_12V; and the GND pin of power chip PW2 is connected to ground. The drive circuit uses the EG3112 driver chip, with a 350ns dead time to balance safety and losses, and the reliability and safety of the drive circuit are improved by using an isolated power supply.

2. The supercapacitor bidirectional converter circuit for a 48V electric forklift according to claim 1, characterized in that, The main control communication module includes: STM control chip U1, resistors R1, R2, R3, R4, R5, capacitors C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, inductors L1 and L2, diodes D1 and D2, diode array D3, and CAN transceiver chip U2. One end of resistor R1 is connected to the external power supply VCC_3V3, and the other end of resistor R1 is connected to pin RST of the STM control chip U1 and one end of capacitor C6. The other end of capacitor C6 is connected to ground. The external power supply VCC_3V3 is connected to pin VDD of the STM control chip U1 and one end of inductor L1. The other end of inductor L1 is connected to one end of capacitor C10, pin VREF+ of the STM control chip U1, and pin VDDA of the STM control chip U1. The other end of capacitor C10 is connected to ground and the STM control chip... The U1 pin VSSA is connected, the STM control chip U1 pin 31 VSS is connected, the external power supply VCC_3V3 is connected to the STM control chip U1 pin 32 VDD, the external power supply VCC_3V3 is connected to the STM control chip U1 pin 48 VDD, the external power supply VCC_3V3 is connected to the STM control chip U1 pin 64 VDD, one end of the resistor R4 is connected to the STM control chip U1 pin PB8-BOOT0, and the other end of the resistor R4 is connected to the STM control chip U1 pin 63 VSS and ground. The external power supply VCC_5V is connected to one end of capacitor C1 and the VCC pin of CAN transceiver chip U2. The other end of capacitor C1 is connected to ground. One end of resistor R2 is connected to the TXD pin of CAN transceiver chip U2, and the other end of resistor R2 is connected to the PB6 pin of STM control chip U1. One end of resistor R5 is connected to the RXD pin of CAN transceiver chip U2, and the other end of resistor R5 is connected to the PB5 pin of STM control chip U1. One end of capacitor C7 is connected to ground and the GND pin of CAN transceiver chip U2. The other end of capacitor C7... The terminal is connected to the VREF pin of the CAN transceiver chip U2. The CANH pin of the CAN transceiver chip U2 is connected to one end of capacitor C8, one end of resistor R3, and the first end of inductor L2. The CANL pin of the CAN transceiver chip U2 is connected to one end of capacitor C9, the other end of resistor R3, and the second end of inductor L2. The third end of inductor L2 is connected to one end of diode D1. The fourth end of inductor L2 is connected to one end of diode D2. The other end of capacitor C8 is connected to the other end of capacitor C9, the other end of diode D1, the other end of diode D2, and ground. The external power supply VCC_3V3 is connected to one end of capacitor C2, one end of capacitor C3, one end of capacitor C4, and one end of capacitor C5. The other end of capacitor C2 is connected to the other end of capacitor C3, the other end of capacitor C4, the other end of capacitor C5, and ground. One end of diode array D3 is connected to the external power supply VCC_3V3, and the other end of diode array D3 is connected to ground. The remaining TML_MOSBH pin, TML_MOSBL pin, TML_MOSAH pin, and TML_MOSAL pin are connected to the signal circuits that need to be protected.

3. The supercapacitor bidirectional converter circuit for a 48V electric forklift according to claim 1, characterized in that, The power input protection module includes: TVS diode D4, capacitor C11, transformer L3, resistor R6, inductor L4, capacitor C12, and resistor R7. The input power supply VCC_IN is connected to one end of TVS diode D4, one end of capacitor C11, and the first end of transformer L3. The other end of TVS diode D4 is connected to the other end of capacitor C11, the second end of transformer L3, the other end of resistor R6, and -48V1 ground. The other end of resistor R6 is connected to PGND. The fourth end of transformer L3 is connected to one end of inductor L4, one end of capacitor C12, one end of resistor R7, and +48V_1 power supply. The third end of transformer L3 is connected to the other end of capacitor C12, the other end of resistor R7, and -48V2 ground. TVS diode D1 provides overvoltage protection for the input power supply VCC_IN, capacitor C11 filters out high-frequency noise from the input; transformer L3 provides electrical isolation between the input and output, resistor R6 participates in the processing related to transformer L3; inductor L4 and capacitor C12 form an LC filter circuit to filter out output ripple, resistor R7 serves as load matching for the output, and finally outputs a stable +48V_1 power supply.

4. The supercapacitor bidirectional converter circuit for a 48V electric forklift according to claim 1, characterized in that, The signal acquisition and processing module includes: capacitors C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, C30, C31, and C32; operational amplifiers U5, U6, U7, U8, U9, and U10; and resistors R16, R17, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, R29, and R30. One end of capacitor C19 is connected to the GND pin of operational amplifier U5, one end of capacitor C20 is connected to ground, and the other end of capacitor C19 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U5. The other end of capacitor C20 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U5. One end of resistor R16 is connected to the OUT pin of operational amplifier U5, and the other end of resistor R16 is connected to one end of capacitor C21 and the PC0 pin of STM control chip U1. The IN- pin of operational amplifier U5 is connected to ground, and the other end of capacitor C21 is connected to ground. One end of capacitor C22 is connected to the GND pin of operational amplifier U6, one end of capacitor C23 is connected to ground, and the other end of capacitor C22 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U6. The other end of capacitor C23 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U6. One end of resistor R17 is connected to the OUT pin of operational amplifier U6, and the other end of resistor R17 is connected to one end of capacitor C24 and the PC1 pin of STM control chip U1. The IN- pin of operational amplifier U6 is connected to ground, and the other end of capacitor C24 is connected to ground. One end of capacitor C25 is connected to the GND pin of operational amplifier U7, one end of capacitor C26 is connected to ground, the other end of capacitor C25 is connected to the input power supply A_1V65 and the REF pin of operational amplifier U7, the other end of capacitor C26 is connected to the input power supply A_3V3 and the V+ pin of operational amplifier U7, one end of resistor R18 is connected to the OUT pin of operational amplifier U7, the other end of resistor R16 is connected to one end of capacitor C27 and the PC2 pin of STM control chip U1, the IN- pin of operational amplifier U7 is connected to ground, and the other end of capacitor C21 is connected to ground. One end of resistor R20 is connected to one end of resistor R19 and the inverting input of operational amplifier U8. One end of resistor R21 is connected to one end of resistor R22 and the non-inverting input of operational amplifier U8. The other end of resistor R22 is connected to ground. The other end of resistor R19 is connected to the output of operational amplifier U8 and one end of resistor R23. The positive power supply pin of operational amplifier U8 is connected to the power input A_3V3. The negative power supply pin of operational amplifier U8 is connected to ground. The other end of resistor R23 is connected to the PC3 pin of STM control chip U1. One end of resistor R24 ​​is connected to one end of resistor R27 and the inverting input of operational amplifier U9; one end of resistor R25 is connected to one end of resistor R26 and the non-inverting input of operational amplifier U9; the other end of resistor R26 is connected to ground; the other end of resistor R27 is connected to the output of operational amplifier U9 and one end of resistor R28; and the other end of resistor R23 is connected to the PA1 pin of STM control chip U1. One end of resistor R29 is connected to power input A_3V3. The other end of resistor R29 is connected to one end of resistor R30, one end of capacitor C28, and the +IN pin of operational amplifier U10. The other end of resistor R30 is connected to ground, the other end of capacitor C28, one end of capacitor C29, and the V- pin of operational amplifier U10. The other end of capacitor C29 is connected to power input A_1V65, the -IN pin of operational amplifier U10, and the OUT pin of operational amplifier U10. The V+ pin of operational amplifier U10 is connected to power input A_3V3. One end of capacitor C30 is connected to one end of capacitor C31, one end of capacitor C32, and power input A_1V65. The other end of capacitor C30 is connected to the other end of capacitor C31, the other end of capacitor C32, and ground.

5. A supercapacitor bidirectional converter circuit for a 48V electric forklift according to claim 1, characterized in that, The passive equalization circuit module is composed of multiple passive equalization circuits connected in parallel. The passive equalization circuit includes: resistor R31, resistor R32, resistor R33, resistor R34, resistor R35, capacitor C33, and supercapacitor charging protection chip U11. One end of resistor R31 is connected to the input power supply, one end of capacitor C33, resistor R35, and the VDD pin of the supercapacitor charging protection chip U11. The other end of resistor R31 is connected to one end of resistor R32. The other end of resistor R32 is connected to one end of resistor R33. The other end of resistor R33 is connected to the drain of transistor Q5. The gate of transistor Q5 is connected to the IOUT pin of the capacitor charging protection chip U11 and one end of resistor R34. The source of transistor Q5 is connected to the other end of resistor R34 and the other end of capacitor C33.

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