Electric power-assisted bicycle and brake control method thereof

Abstract

The invention relates to the field of vehicles, in particular to an electric power-assisted bicycle and a brake control method thereof.The electric power-assisted bicycle comprises a bicycle body and a power system; the bicycle body comprises a bicycle frame, a handlebar, a pedal crank assembly, a front wheel and a rear wheel. The power system comprises a front wheel power motor, a rear wheel power motor, a middle generator, a power source and a whole vehicle controller. The middle generator is integrated on the pedal crank assembly, and the vehicle control unit is electrically connected with all the power components. The pedal crank assembly can rotate in a first direction and a second direction opposite to the first direction, when the pedal crank assembly rotates in the first direction, the middle generator enters a power generation mode, and when the pedal crank assembly rotates in the second direction, the electric power-assisted bicycle enters a braking mode. The potential that a pedal crank assembly serves as a core interaction interface of a rider and a vehicle is fully utilized, power generation and braking are integrated in two-way rotation of the same component, and the rider can directly control the state of the vehicle through simple treading actions.

Description

Electric-assisted bicycles and their braking control methods Technical Field

[0001] This invention relates to the field of transportation vehicles, and more specifically, to an electric-assisted bicycle and its braking control method. Background Technology

[0002] Electric-assist bicycles (EMBs), as an environmentally friendly and convenient mode of transportation, effectively reduce riders' physical exertion thanks to the advantage of electric motor-assisted drive, and are widely used in daily commutes and short-distance trips. The core components of existing ESBs typically include the frame (frame, handlebars, pedal crank assembly, front and rear wheels) and the power system (drive motor, power supply, controller, etc.). The design of the power system directly affects the riding experience, operational safety, and functional practicality. During riding, the pedal crank assembly serves as the most direct and frequent interaction interface between the rider and the vehicle; its functional design directly impacts the intuitiveness and smoothness of operation. Similarly, the braking system, as a crucial component for safety, also significantly affects the riding experience through ease of operation. Therefore, the coordinated design of the pedal crank assembly and the braking system is a vital aspect of improving the overall performance of ESBs.

[0003] However, the braking system of existing e-bikes is usually independent of the pedal crank assembly, requiring braking via a mechanical brake lever or electronic brake button on the handlebars. This separate design forces riders to switch from pedaling to hand operation when braking is needed, increasing the number of steps and potentially affecting braking timeliness due to hand reaction delays, making the overall operating logic of the bike rather fragmented. Furthermore, current mainstream e-bikes typically only assign important functions to the forward rotation of the pedal crank assembly, such as propelling the bike forward or integrating a pedal-generated generator to power the mains and extend range. In the reverse rotation, it is usually designed as an ineffective action or only used for secondary functions such as shifting auxiliary gears. This reduces a potentially multifunctional operating component to a single function, failing to fully realize its operational value. Summary of the Invention

[0004] The present invention aims to overcome at least one of the defects (deficiencies) of the prior art and provide an electric-assisted bicycle and its braking control method, which solves the problems of the existing electric-assisted bicycle braking system and pedal crank assembly being independent of each other, resulting in operation separation and poor continuity, as well as the underutilization of the reverse rotation function of the pedal crank assembly and the waste of operating resources.

[0005] The technical solution adopted by this invention is an electric-assisted bicycle, including a bicycle frame and a power system; the frame includes a frame, handlebars, a pedal crank assembly, a seat, a front wheel, and a rear wheel; the handlebars are located on the upper part of the frame, the pedal crank assembly is located on the lower part of the frame, the seat is located on the frame, the front wheel is rotatably connected to the front part of the frame, and the rear wheel is rotatably connected to the rear part of the frame; the power system includes a front wheel motor, a rear wheel motor, a centrally located generator, a power supply, and a vehicle controller; the front wheel motor drives the front wheel to rotate, and the rear wheel motor drives the rear wheel to rotate. The rear wheel rotates, and the mid-mounted generator is integrated into the pedal crank assembly. It generates electricity by rotating the crank assembly through pedaling. The power supply is mounted on the frame to store electrical energy and power the front and rear wheel motors. The vehicle controller is electrically connected to the front wheel motor, the rear wheel motor, the mid-mounted generator, and the power supply. The pedal crank assembly can rotate in a first direction and a second direction opposite to the first direction. When rotating in the first direction, the mid-mounted generator enters the power generation mode; when rotating in the second direction, the electric-assist bicycle enters the braking mode.

[0006] First, this application enables riders to directly control the vehicle's status through simple pedaling actions by giving the pedal crank assembly bidirectional rotation functionality: forward (first direction) pedaling allows for normal riding or power generation, while reverse (second direction) pedaling directly enters braking mode. This design integrates braking and pedaling actions, allowing riders to decelerate or stop without moving their hands from the handlebars to the brake lever. The operation path is shorter and the response is faster, significantly improving riding smoothness and safety, especially in scenarios with frequent starts and stops, such as urban commuting. Second, this application fully utilizes the potential of the pedal crank assembly as the core interaction interface between the rider and the vehicle, integrating power generation and braking functions into the bidirectional rotation of the same component. Compared to existing technologies where the pedals are only used for driving and braking relies on separate components, this integrated solution makes the overall vehicle's operating logic more unified, thus improving the user experience.

[0007] When the pedal crank assembly rotates in the second direction, the electric-assisted bicycle enters braking mode. The braking force is directly proportional to the angle of rotation of the pedal crank assembly in the second direction; that is, the greater the angle of rotation, the greater the braking force. By establishing a direct proportionality between the braking force and the angle of rotation of the pedal crank assembly in the opposite direction (second direction), the rider can precisely control the braking intensity by changing the angle of the reverse pedaling: slight reverse pedaling generates only a small braking force for deceleration or speed control; large reverse pedaling generates a larger braking force for rapid stopping. This linear control method makes the braking process smoother and more natural, significantly improving riding comfort. Furthermore, the rider can precisely control the vehicle's deceleration by feeling the pedals, enhancing the interaction and coordination between rider and bicycle. This allows the rider to handle complex road conditions more easily, further improving riding safety.

[0008] In braking mode, this application switches the front wheel motor and / or the rear wheel motor to generator mode, converting the inertial kinetic energy of the vehicle during deceleration or downhill driving into electrical energy. The electrical energy output by the front wheel motor and / or the rear wheel motor is then stored in the power source via the vehicle controller. This energy recovery mechanism effectively improves energy utilization efficiency and extends the range of the electric-assist bicycle.

[0009] The controller of this electric-assist bicycle can control the operating modes of the front wheel motor, rear wheel motor, and mid-drive generator according to different riding conditions, and measure the back EMF voltage of the mid-drive generator in real time, adjusting the equivalent voltage applied to the generator accordingly. The damping torque of the mid-drive generator changes with the equivalent voltage, thus achieving a continuously variable transmission (CVT) effect. Riders can feel the different damping torque changes of the mid-drive generator. Specifically, when the electric-assist bicycle is going uphill, the equivalent voltage decreases, the damping torque decreases, and a higher pedaling speed is required; when the electric-assist bicycle is on a flat road, the equivalent voltage increases, the damping torque increases, and a lower pedaling speed is required. By linking the equivalent voltage and damping torque, combined with differentiated control for uphill and flat road conditions, the problem of "fixed pedal damping, unable to adapt to different road conditions" in existing electric-assist bicycles is solved. When going uphill, the equivalent voltage is reduced to decrease the damping torque, so the rider does not need to overcome excessive pedaling resistance, significantly reducing physical exertion when going uphill. On flat roads, the equivalent voltage is increased to increase the damping torque, avoiding the "free-riding" feeling caused by insufficient damping, making the pedaling action more solid and improving riding stability. Through this road condition adaptive damping adjustment, e-bikes can provide the optimal pedaling feel in different riding environments, enhancing the riding experience.

[0010] When the e-bike is going uphill and the rider is pedaling forward, the vehicle controller synchronizes the front and rear wheel motors to output driving force. This dual-motor synchronous drive mode allows both motors to work simultaneously, significantly improving the bike's climbing ability and acceleration performance. It effectively solves the problem of insufficient power in traditional single-motor driven models when climbing, allowing riders to pedal more easily on steep slopes. When the e-bike is going downhill or decelerating and the rider is pedaling in the opposite direction to enter braking mode, the vehicle controller asynchronously outputs braking force to the front and rear wheel motors. This asynchronous braking strategy avoids the risk of skidding caused by simultaneous wheel lock-up, and is especially suitable for slippery surfaces or emergency braking scenarios, significantly improving the vehicle's braking stability and riding safety. This design fully leverages the advantages of the dual-motor configuration, enabling the e-bike to perform optimally in various riding environments, ensuring both strong power output and reliable braking safety.

[0011] A braking control method for an electric-assist bicycle, the electric-assist bicycle comprising a frame and a power system, the frame comprising a frame, a pedal crank assembly, a front wheel and a rear wheel, the pedal crank assembly being rotatable in a first direction and in a second direction opposite to the first direction; the power system comprising a drive motor, a central generator, a power supply, a vehicle controller and a motion sensor module, the drive motor being disposed on the front wheel and / or the rear wheel, the central generator being integrated into the pedal crank assembly, the power supply being used to store electrical energy and supply power to the drive motor, the motion sensor module being disposed on the pedal crank assembly, and the vehicle controller being electrically connected to the drive motor, the central generator and the power supply respectively, and communicatively connected to the motion sensor module;

[0012] The braking control method includes the following steps: S1, the vehicle controller acquires motion parameters of the pedal crank assembly when it rotates in the second direction through the motion sensor module, and calculates the reverse rotation angle and / or reverse rotation rate; S2, the vehicle controller obtains the pedal crank assembly's pedal torque parameters, and combines them with the reverse rotation angle and / or reverse rotation rate to generate a quantized braking signal; S3, the vehicle controller adjusts the target value of the kinetic energy recovery braking current of the power motor according to the quantized braking signal to achieve adaptive control of braking intensity.

[0013] This method first uses a motion sensor module to collect motion parameters of the pedal crank assembly in real time as it rotates in the second direction, accurately calculating the reverse rotation angle and / or reverse rotation rate to precisely capture the user's braking intention. Simultaneously, it acquires the pedal crank assembly's pedal torque parameters, fusing the torque information reflecting braking force with the angle information reflecting braking stroke to generate a quantified braking signal that comprehensively characterizes the user's braking needs. This effectively avoids misjudgments that may arise from single-parameter detection, significantly improving the accuracy and reliability of braking intention recognition. Based on this, the vehicle controller adjusts the target value of the kinetic energy recovery braking current of the power motor according to the quantified braking signal, achieving adaptive control of braking intensity. This converts the kinetic energy of the vehicle during braking into electrical energy stored in the power supply, effectively extending the driving range. Users only need to pedal in the reverse direction to brake, allowing their hands to always hold the handlebars, which is intuitive for riding, improves safety, reduces wear on mechanical brake pads, and lowers maintenance costs. This control method is based on existing mid-mounted generators and motion sensor modules, requiring no additional hardware, and has significant advantages such as low cost, strong adaptability, and ease of industrialization.

[0014] In step S2, the vehicle controller collects the generator current parameters from the mid-mounted generator and converts them into the pedaling torque parameters using a preset torque conversion model. This solution cleverly utilizes the generator current naturally generated by the mid-mounted generator during reverse pedaling as the raw signal for torque detection, eliminating the need for additional torque sensor hardware and achieving indirect detection of pedaling torque, significantly reducing system cost and structural complexity. Since the generator current and pedaling torque are positively correlated, this detection method can accurately reflect the force of the user's reverse pedaling, providing a reliable data foundation for the accurate generation of braking signals.

[0015] In step S3, the magnitude of the braking signal is linearly proportional to the target value of the kinetic energy recovery braking current of the power motor. This linear proportionality establishes a clear and predictable correspondence between the braking signal and the braking current, enabling the braking intensity to increase synchronously with the increase of the user's reverse pedal angle and force, achieving a smooth transition of braking force. Users can intuitively obtain a matching deceleration effect by controlling the depth and force of the reverse pedal stroke. The braking process conforms to ergonomic expectations, greatly improving the naturalness and precision of riding control. The linear proportionality provides a simple and efficient calculation model for the vehicle controller software implementation, reducing the complexity of the control algorithm and the consumption of computing resources, and improving the system's real-time response capability. Simultaneously, this clear proportional relationship facilitates parameter calibration and debugging during the vehicle development stage, allowing for flexible adjustment of the proportional coefficient according to different vehicle models and user preferences, exhibiting good engineering adaptability. The stable linear mapping relationship also enables the actual braking current to more accurately follow changes in the target value, providing a favorable foundation for the precise implementation of subsequent closed-loop control.

[0016] In step S3, the vehicle controller determines the target value of the regenerative braking current based on the quantized braking signal. Combining this with the real-time voltage of the power supply, the back EMF voltage of the motor, the internal resistance of the motor, and the stator inductance, the controller calculates the target output voltage of the motor phase lines using a built-in control algorithm. The vehicle controller then adjusts this target output voltage to achieve closed-loop control of the braking current, bringing the actual braking current closer to the target value. This scheme, by introducing key electrical parameters such as the real-time voltage of the power supply, the back EMF voltage of the motor, the internal resistance of the motor, and the stator inductance, constructs a complete motor control model. This allows the calculation of the target output voltage to dynamically adapt to the current operating conditions, overcoming the shortcomings of single-parameter control in handling changes in operating conditions. The built-in control algorithm performs precise calculations based on these electrical parameters, ensuring that the output voltage matches the current state of the motor, significantly improving the adaptability and robustness of the control. Furthermore, the adoption of a "voltage regulation → current closed-loop" control path achieves indirect but precise regulation of the braking current. The vehicle controller uses a closed-loop control algorithm to provide real-time feedback on the deviation between the actual braking current and the target value, dynamically adjusting the output voltage to ensure the actual current stably approaches the target value, effectively eliminating current deviations caused by parameter fluctuations or external interference. By regulating the voltage parameters output to the phase lines of the drive motor, closed-loop precise control of the braking current is achieved, ensuring the kinetic energy recovery braking current stably matches the target value, avoiding braking jerks caused by current fluctuations, and guaranteeing a smooth and stable braking process. Furthermore, this closed-loop control mechanism maximizes kinetic energy recovery efficiency, enabling braking energy to be efficiently converted into electrical energy and stored in the power supply, further extending the vehicle's driving range.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: This application fully utilizes the potential of the pedal crank assembly as the core interaction interface between the rider and the vehicle, integrating power generation and braking functions into the bidirectional rotation of the same component (pedal crank assembly). This allows the rider to directly control the vehicle's state through simple pedaling actions. Forward (first direction) pedaling results in normal riding or power generation, while reverse (second direction) pedaling activates braking mode. This design combines braking operation with pedaling action, allowing the rider to decelerate or stop without moving their hands from the handlebars to the brake lever. The operation path is shorter, and the response is faster, improving riding smoothness and safety. Furthermore, compared to existing technologies where the pedals are only used for driving or power generation, and braking relies on separate components, this integrated solution makes the overall vehicle's operating logic more unified, enhancing the user experience. The braking force is proportional to the angle of reverse rotation of the pedal crank assembly, allowing the rider to precisely control the braking intensity by changing the angle of reverse pedaling. For example, slight reverse pedaling generates less braking force for deceleration or speed control; large reverse pedaling generates greater braking force for rapid stopping. This linear control method allows riders to precisely control vehicle deceleration through pedal feel, increasing the interaction and synergy between rider and bike. It also makes the braking process smoother and more natural, significantly improving riding comfort and safety. When the pedal crank assembly rotates in the opposite direction, the front wheel motor and / or rear wheel motor switch to generator mode, converting the inertial kinetic energy during vehicle deceleration or downhill driving into electrical energy, which is then stored in the power supply via the vehicle controller. This effectively improves energy efficiency and extends the range. The vehicle controller can adjust the equivalent voltage applied to the mid-mounted generator according to different riding conditions. The damping torque of the mid-mounted generator changes with the equivalent voltage, thus achieving a continuously variable transmission (CVT) effect. By linking the equivalent voltage and damping torque adjustment, combined with differentiated control for uphill and flat roads, the problem of fixed pedal damping in existing electric-assist bicycles, which cannot adapt to different road conditions, is solved. Specifically, when an e-bike is going uphill, the equivalent voltage decreases, and the damping torque decreases, so the rider doesn't need to overcome excessive pedaling resistance, significantly reducing energy expenditure when going uphill. On flat roads, the equivalent voltage increases, and the damping torque increases, avoiding the feeling of "loose pedaling" caused by insufficient damping, making the pedaling action more solid and improving riding stability. When the e-bike is going uphill and the rider is pedaling forward, the vehicle controller controls the front wheel motor and the rear wheel motor to output driving force synchronously, thereby significantly improving the vehicle's climbing ability and acceleration performance, effectively solving the problem of insufficient power when climbing in traditional single-motor driven models. When the e-bike is going downhill or decelerating and the rider is pedaling in the opposite direction to enter braking mode, the vehicle controller controls the front wheel motor and the rear wheel motor to output braking force asynchronously, which can avoid the risk of sideslip caused by the front and rear wheels locking up at the same time, improving the vehicle's braking stability and riding safety.The braking control method is based on an existing mid-mounted generator and motion sensor module, requiring no additional hardware, resulting in low cost and strong adaptability. Users only need to reverse-push the pedals of the crank assembly to brake, allowing them to maintain a constant grip on the handlebars, enhancing riding intuition, improving safety, and reducing wear on mechanical brake pads. This method fuses torque information reflecting braking force with angle information reflecting braking stroke to generate a quantified braking signal characterizing the user's braking needs. This effectively avoids misjudgments that may arise from single-parameter detection, significantly improving the accuracy and reliability of braking intent recognition. In step S2, the generator current naturally generated during reverse-push is cleverly used as the raw signal for torque detection, eliminating the need for additional torque sensor hardware and enabling indirect detection of pedaling torque. In step S3, the magnitude of the braking signal is linearly proportional to the target value of the kinetic energy recovery braking current from the power motor, establishing a clear and predictable correspondence between the braking signal and braking current. This allows the braking intensity to increase synchronously with the increase in the user's reverse-push angle and force, achieving a smooth transition of braking force. The vehicle controller combines the real-time voltage of the power supply, the back EMF voltage of the power motor, the internal resistance of the power motor, and the stator inductance electrical parameters, and uses a built-in control algorithm to perform precise calculations to obtain the target output voltage of the power motor phase line adapted to the current operating conditions. By adjusting the voltage parameters output to the power motor phase line, it achieves closed-loop precise control of the braking current, ensuring that the kinetic energy recovery braking current stably matches the target value, avoiding braking jerking caused by current fluctuations, ensuring a smooth and stable braking process, and maximizing the efficiency of kinetic energy recovery to achieve efficient energy recovery and reuse. Attached Figure Description

[0018] Figure 1 is a structural diagram of the present invention.

[0019] Figure 2 is a schematic diagram of the working principle of the whole vehicle according to the present invention.

[0020] Figure 3 is a schematic diagram of the working principle of the foot-operated power generation of the present invention.

[0021] Figure 4 is a schematic diagram of the working principle of the continuously variable transmission of the present invention.

[0022] 110. Frame; 120. Handlebars; 130. Pedal crank assembly; 140. Front wheel; 150. Rear wheel; 160. Seat; 210. Front wheel motor; 220. Rear wheel motor; 230. Mid-mounted generator; 240. Power supply; 250. Vehicle controller; 260. Control display screen; 270. IMU motion sensor module. Detailed Implementation

[0023] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate the following embodiments, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; it is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0024] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. These terms are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Example 1, as shown in Figure 1, describes an electric-assisted bicycle, including a bicycle frame and a power system. The frame includes a frame 110, handlebars 120, a pedal crank assembly 130, a seat 160, a front wheel 140, and a rear wheel 150. The handlebars 120 are located on the upper part of the frame 110 for directional control. The pedal crank assembly 130 is rotatably connected to the lower part of the frame 110 via bearings, allowing the rider to input power by pedaling. The seat 160 is mounted on the frame 110. The front wheel 140 is rotatably connected to the front of the frame 110, and the rear wheel 150 is rotatably connected to the rear of the frame 110. Both the front and rear wheels are equipped with mechanical braking assemblies, providing dual protection in conjunction with electronic braking.

[0026] The power system includes a front-wheel drive motor 210, a rear-wheel drive motor 220, a mid-mounted generator 230, a power supply 240, and a vehicle controller 250. The front-wheel drive motor 210 is located within the hub of the front wheel 140 and drives the front wheel 140 to rotate. The rear-wheel drive motor 220 is located within the hub of the rear wheel 150 and drives the rear wheel 150 to rotate. Both are hub motors, which allows for a compact structure, eliminates the need for additional transmission mechanisms, and improves transmission efficiency.

[0027] The mid-mounted generator 230 is integrated within the pedal crank assembly 130. When the rider pedals, the pedal crank assembly 130 rotates, which in turn drives the rotor of the mid-mounted generator 230 to rotate relative to the stator, generating electrical energy through electromagnetic induction. The electrical energy generated by the mid-mounted generator 230 can be processed by the vehicle controller 250 and then sent to the power supply 240 for storage, or directly supplied to the front wheel motor 210 and the rear wheel motor 220.

[0028] The power supply 240, mounted on the vehicle frame 110, is preferably a lithium battery pack. It stores electrical energy to power the front-wheel drive motor 210 and the rear-wheel drive motor 220, and provides operating power to the vehicle controller 250 and other electrical components. The power supply 240 includes a smart battery management system (BMS) for real-time monitoring of the battery pack's voltage, current, temperature, and state of charge, providing safety protection against overcharging, over-discharging, and over-temperature. The power supply 240 is equipped with a power button, a battery status indicator light, and a 100W PD fast charging circuit (TYPE-C interface). The BMS module also integrates an active balancing circuit, a discharge circuit, a temperature sampling circuit, and a voltage and current sampling circuit to ensure battery charging and discharging safety and performance stability.

[0029] The vehicle controller 250 (i.e., the main control board) is mounted on the frame 110 and serves as the core control unit of the vehicle. As shown in Figure 2, the vehicle controller 250 includes an MCU microcontroller unit, a motor drive circuit, a signal acquisition circuit, and a communication interface. The motor drive circuit includes a sensorless FOC circuit, a sensorless square wave circuit, and a three-phase full-bridge circuit. The signal acquisition circuit includes a Hall effect signal acquisition circuit and a voltage and current sampling circuit. The communication interface includes a serial port and a low-power Bluetooth module. The vehicle controller 250 is electrically connected to the front wheel motor 210, the rear wheel motor 220, the mid-mounted generator 230, and the power supply 240 to control the operating status of each component.

[0030] The vehicle controller 250 integrates a vehicle posture detection unit (not shown) for real-time detection of the vehicle's posture and motion state, including the vehicle's tilt angle, acceleration in the forward direction, and angular velocities along each axis. The vehicle controller 250 uses the data collected by the vehicle posture detection unit to determine the current riding condition, providing a basis for decision-making regarding electronic continuously variable transmission (CVT), dual-motor coordinated control, and braking control.

[0031] A control display screen 260 is installed on the handlebars 120 of the vehicle body, and the control display screen 260 is communicatively connected to the vehicle controller 250. The control display screen 260 is used to display real-time status information of the vehicle, including but not limited to current speed, battery level, riding mode, and assist level; at the same time, the control display screen can also serve as a human-machine interface, receiving input commands from the rider via touch or buttons to adjust parameters such as assist level, riding mode, and energy recovery intensity. The rider can select different riding modes according to actual road conditions, and the vehicle controller 250 automatically matches the output strategies of the front and rear wheel motors, the control strategy of the mid-mounted generator, and the electronic continuously variable transmission curve according to the selected mode, realizing intelligent coordinated control of the entire vehicle.

[0032] An IMU motion sensor module 270 is installed on the pedal crank assembly 130. The IMU motion sensor module 270 is wirelessly connected to the vehicle controller 250 via Bluetooth. It has an embedded high-precision IMU inertial measurement unit, which integrates an angular velocity sensor and an acceleration sensor. It can accurately detect motion parameters such as the rotational angular velocity and three-dimensional motion acceleration of the crank in real time, and transmit the collected raw motion data to the vehicle controller 250 in real time through a wireless communication module, providing a basis for vehicle control decisions.

[0033] The pedal crank assembly 130 can rotate in a first direction (forward pedaling) and a second direction opposite to the first direction (reverse pedaling). As shown in Figure 3, when the rider pedals in the first direction (forward pedaling), the centrally located generator 230 enters the power generation mode, converting the rider's pedaling mechanical energy into electrical energy. The generated AC power is converted into DC power by the internal rectifier circuit of the vehicle controller 250, which can be sent to the power supply 240 for storage or directly supplied to the front wheel motor 210 and / or the rear wheel motor 220, realizing real-time power replenishment during riding. When the rider pedals in the second direction (reverse pedaling), the vehicle controller 250 controls the electric-assisted bicycle to enter the braking mode. In the braking mode, the vehicle controller 250 dynamically adjusts the braking force according to the reverse rotation angle of the pedal crank assembly 130. The magnitude of the braking force is proportional to the rotation angle of the pedal crank assembly 130 in the second direction; that is, the larger the rotation angle, the greater the braking force, so as to achieve a linear and smooth braking effect.

[0034] In braking mode, the front wheel power motor 210 and / or the rear wheel power motor 220 are switched to generator mode by the vehicle controller 250 to convert the vehicle's inertial kinetic energy into electrical energy, which is then rectified and regulated before being fed back to the power source 240, thus realizing kinetic energy recovery.

[0035] This application uses the vehicle controller 250 to adjust the equivalent voltage of the mid-mounted generator 230 in real time, thereby changing the electromagnetic damping torque of the mid-mounted generator 230 and realizing the electronic continuously variable transmission function. This replaces the mechanical transmission structure of traditional bicycles, such as the chainring, derailleur, and freewheel, simplifying the overall vehicle structure and improving reliability. The principle is shown in Figure 4.

[0036] Specifically, when the electric-assist bicycle is in an uphill condition, the whole vehicle controller 250 reduces the equivalent voltage applied to the mid-mounted generator 230, thereby reducing its damping torque. The rider can easily pedal with a high cadence and low torque, reducing the riding load. When the electric-assist bicycle is in a high-speed condition on a flat road, the whole vehicle controller 250 increases the equivalent voltage applied to the mid-mounted generator 230, thereby increasing its damping torque. The rider can ride with a low cadence and high efficiency, achieving a smooth and jerky electronic continuously variable transmission experience.

[0037] To address the issues of insufficient power and slippage during braking in traditional single-wheel drive systems, this invention employs a front and rear dual-wheel coordinated drive and asynchronous braking strategy: When the vehicle is accelerating or going uphill and the rider is pedaling forward, the vehicle controller 250 controls the front wheel motor 210 and the rear wheel motor 220 to synchronously output driving force, significantly improving climbing and acceleration performance; when the vehicle is decelerating or going downhill and the rider is pedaling in the opposite direction, the vehicle controller 250 controls the front wheel motor 210 and the rear wheel motor 220 to asynchronously output braking force, preventing single-wheel lock-up and slippage, and significantly improving braking stability and driving safety.

[0038] Example 2 This example provides a braking control method for an electric-assisted bicycle. As shown in Figure 1, the electric-assisted bicycle includes a frame and a power system. The frame includes a frame 110, handlebars 120, pedal crank assembly 130, seat 160, front wheel 140, and rear wheel 150. The handlebars 120 are located on the upper part of the frame 110 for controlling the direction of the bicycle. The pedal crank assembly 130 is rotatably connected to the lower part of the frame 110 via bearings for the rider to pedal to input power. The seat 160 is located on the frame 110. The front wheel 140 is rotatably connected to the front of the frame 110, and the rear wheel 150 is rotatably connected to the rear of the frame 110.

[0039] The power system includes a drive motor, a mid-mounted generator 230, a power supply 240, a vehicle controller 250, and a motion sensor module. The drive motor is located on the front wheel 140 and / or the rear wheel 150, driving the front wheel 140 and / or the rear wheel 150 to rotate. In this embodiment, the drive motor includes a front wheel drive motor 210 and a rear wheel drive motor 220; the front wheel drive motor 210 is located within the hub of the front wheel 140, driving the front wheel 140 to rotate, and the rear wheel drive motor 220 is located within the hub of the rear wheel 150, driving the rear wheel 150 to rotate. The mid-mounted generator 230 is integrated into the pedal crank assembly 130; the power supply 240 is located on the frame 110, storing electrical energy and supplying power to the front wheel drive motor 210 and the rear wheel drive motor 220. The motion sensor module is specifically an IMU motion sensor module 270, which is mounted on the pedal crank assembly 130. The IMU motion sensor module 270 embeds a high-precision IMU inertial measurement unit, integrating an angular velocity sensor and an acceleration sensor. It can accurately detect motion parameters such as the rotational angular velocity and three-dimensional acceleration of the pedal crank assembly 130 in real time, and transmit the collected motion parameters to the vehicle controller 250 in real time via Bluetooth. The vehicle controller 250 (i.e., the main control board) is mounted on the handlebars 120 and is electrically connected to the front wheel motor 210, the rear wheel motor 220, the mid-mounted generator 230, and the power supply 240.

[0040] The braking control method includes the following steps: S1, the vehicle controller 250 collects motion parameters of the pedal crank assembly 130 when it rotates in the second direction (reverse) through the IMU motion sensor module 270, and calculates the reverse rotation angle and / or reverse rotation rate. Specifically, the IMU motion sensor module 270 embeds a high-precision inertial measurement unit to detect motion parameters such as the rotational angular velocity and three-dimensional motion acceleration of the pedal crank assembly 130 in reverse rotation in real time, and transmits them to the vehicle controller 250 in real time through a wireless communication module. After receiving the above raw motion data, the vehicle controller 250 calls a preset attitude calculation algorithm to filter, reduce noise, and calculate the raw motion data to eliminate interference factors such as road bumps and normal pedaling, and accurately calculate key attitude parameters such as the reverse rotation angle and / or reverse rotation rate, providing basic motion data for subsequent braking signal calculation.

[0041] S2. The vehicle controller 250 acquires the pedal torque parameters of the pedal crank assembly 130, and combines them with the reverse rotation angle and / or reverse rotation rate calculated in step S1 to generate a quantized braking signal.

[0042] In this embodiment, the pedaling torque parameter is indirectly detected by the mid-mounted generator 230: when the rider pedals in the opposite direction, the pedal crank assembly 130 rotates in the opposite direction, driving the rotor of the mid-mounted generator 230 to rotate. The phase line of the mid-mounted generator 230 generates a corresponding current, and this current value is positively correlated with the pedaling torque of the pedal crank assembly 130. The vehicle controller 250 collects the phase line current parameter of the mid-mounted generator 230 in real time and calls a preset torque conversion model to convert the current signal into a quantified pedaling torque value, thereby completing the accurate detection of the pedaling torque parameter.

[0043] The vehicle controller 250 fuses the reverse rotation angle and / or reverse rotation rate calculated in step S1 with the pedal torque parameters detected in step S2. Based on a preset braking signal mapping model, it generates a quantized braking signal strongly correlated with the reverse motion of the pedal crank assembly 130. This braking signal is a continuously adjustable numerical signal, the magnitude of which is determined by both the reverse rotation angle and the pedal torque. This effectively avoids errors caused by detecting a single parameter, improves the authenticity and reliability of the braking signal, and closely matches the rider's actual braking intentions.

[0044] In the braking control method of the present invention, the reverse rotation angle and the reverse rotation rate can be selected according to actual needs. Specifically: when only the reverse rotation angle is calculated, step S2 combines the angle with the pedaling torque to generate a braking signal; when only the reverse rotation rate is calculated, step S2 combines the rate with the pedaling torque to generate a braking signal; when both the reverse rotation angle and the reverse rotation rate are calculated simultaneously, step S2 combines both with the pedaling torque to generate a braking signal.

[0045] S3. The vehicle controller 250 adjusts the target value of the kinetic energy recovery braking current of the power motor according to the quantized braking signal generated in step S2, so as to realize adaptive control of braking intensity.

[0046] In this embodiment, the magnitude of the braking signal is linearly proportional to the target value of the kinetic energy recovery braking current of the power motor (taking the front wheel power motor 210 and the rear wheel power motor 220 as examples). That is, the larger the reverse angle of the pedal crank assembly 130 and the greater the pedal torque, the higher the braking signal value, the greater the corresponding braking current, and the stronger the kinetic energy recovery intensity and braking effect. This linear proportionality allows the braking intensity to increase synchronously with the increase of the user's reverse pedal angle and force, achieving a smooth transition of braking force. The user can intuitively obtain a matching deceleration effect by controlling the depth and force of the reverse pedal.

[0047] To achieve precise control, after determining the target value of the regenerative braking current, the vehicle controller 250 further combines key electrical parameters such as the real-time voltage of the power supply 240, the back EMF voltage of the motor, the internal resistance of the motor, and the stator inductance to perform precise calculations using a built-in control algorithm, deriving the target output voltage of the motor phase line adapted to the current operating conditions. The vehicle controller 250 achieves closed-loop precise control of the braking current by adjusting the voltage parameters output to the motor phase line, ensuring that the actual value of the regenerative braking current stably approaches the target value. This closed-loop control mechanism effectively eliminates current deviations caused by parameter fluctuations or external interference, avoids braking jerks caused by current fluctuations, ensures a smooth and stable braking process, and maximizes kinetic energy recovery efficiency, achieving efficient energy recovery and reuse.

[0048] It should be noted that the braking control method of the present invention is not limited to a dual-motor configuration. In this embodiment, the power motors are described using the front wheel power motor 210 and the rear wheel power motor 220 as examples. However, in other embodiments, only the front wheel power motor 210 or only the rear wheel power motor 220 may be provided. In this case, the kinetic energy recovery braking current regulated in step S3 is the braking current of the single power motor. A single-motor configuration can also realize the braking control method of the present invention, which falls within the protection scope of the present invention.

[0049] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. An electric-assisted bicycle, comprising a bicycle frame and a power system; the frame includes a frame, handlebars, a pedal crank assembly, a seat, a front wheel, and a rear wheel; the handlebars are disposed on the upper part of the frame, the pedal crank assembly is disposed on the lower part of the frame, the seat is disposed on the frame, the front wheel is rotatably connected to the front part of the frame, and the rear wheel is rotatably connected to the rear part of the frame; the power system includes a front wheel motor, a rear wheel motor, a centrally mounted generator, a power supply, and a vehicle controller; the front wheel motor drives the front wheel to rotate, the rear wheel motor drives the rear wheel to rotate, the centrally mounted generator is integrated into the pedal crank assembly and generates electricity by pedaling, the power supply is mounted on the frame and stores electrical energy to power the front wheel motor and the rear wheel motor, and the vehicle controller is electrically connected to the front wheel motor, the rear wheel motor, the centrally mounted generator, and the power supply; characterized in that... The pedal crank assembly can rotate in a first direction and a second direction opposite to the first direction. When rotating in the first direction, the centrally located generator enters the power generation mode; when rotating in the second direction, the electric-assisted bicycle enters the braking mode.

2. The electric-assisted bicycle according to claim 1, characterized in that, The braking force of the braking mode is proportional to the angle of rotation of the pedal crank assembly in the second direction.

3. The electric-assisted bicycle according to claim 1, characterized in that, When in braking mode, the front wheel motor and / or rear wheel motor switch to generator mode, and the electrical energy output by them is stored in the power source via the vehicle controller.

4. The electric-assisted bicycle according to claim 1, characterized in that, The vehicle controller can adjust the equivalent voltage applied to the mid-mounted generator, and the damping torque of the mid-mounted generator changes with the equivalent voltage.

5. The electric-assisted bicycle according to claim 4, characterized in that, When the electric-assisted bicycle is going uphill, the equivalent voltage decreases and the damping torque decreases; when the electric-assisted bicycle is on a flat road, the equivalent voltage increases and the damping torque increases.

6. The electric-assisted bicycle according to claim 1, characterized in that, When rotating in the first direction and the electric-assisted bicycle is going uphill, the front wheel motor and the rear wheel motor output driving force synchronously; when rotating in the second direction and the electric-assisted bicycle is going downhill or decelerating, the front wheel motor and the rear wheel motor output braking force asynchronously.

7. A braking control method for an electric-assisted bicycle, the electric-assisted bicycle comprising a frame and a power system, the frame comprising a frame, a pedal crank assembly, a front wheel and a rear wheel, the pedal crank assembly being rotatable in a first direction and in a second direction opposite to the first direction; the power system comprising a drive motor, a centrally mounted generator, a power supply, a vehicle controller and a motion sensor module, the drive motor being disposed on the front wheel and / or the rear wheel, the centrally mounted generator being integrated into the pedal crank assembly, the power supply being used to store electrical energy and supply power to the drive motor, the motion sensor module being disposed on the pedal crank assembly, the vehicle controller being electrically connected to the drive motor, the centrally mounted generator and the power supply respectively, and communicatively connected to the motion sensor module; characterized in that... The braking control method includes the following steps: S1, the vehicle controller acquires motion parameters of the pedal crank assembly when it rotates in the second direction through the motion sensor module, and calculates the reverse rotation angle and / or reverse rotation rate; S2, the vehicle controller obtains the pedal crank assembly's pedal torque parameters, and combines them with the reverse rotation angle and / or reverse rotation rate to generate a quantized braking signal; S3, the vehicle controller adjusts the target value of the kinetic energy recovery braking current of the power motor according to the quantized braking signal to achieve adaptive control of braking intensity.

8. The braking control method for an electric scooter according to claim 7, characterized in that, In step S2, the vehicle controller collects the power generation current parameters generated by the mid-mounted generator and converts them into the pedaling torque parameters through a preset torque conversion model.

9. The braking control method for an electric-assisted bicycle according to claim 7, characterized in that, In step S3, the magnitude of the braking signal is linearly proportional to the target value of the kinetic energy recovery braking current of the power motor.

10. The braking control method for an electric-assisted bicycle according to claim 7, characterized in that, In step S3, the vehicle controller determines the target value of the kinetic energy recovery braking current based on the quantized braking signal, and calculates the target output voltage of the power motor phase line through the built-in control algorithm by combining the real-time voltage of the power supply, the back EMF voltage of the power motor, the internal resistance of the power motor and the stator inductance electrical parameters. The vehicle controller achieves closed-loop control of the braking current by adjusting the target output voltage, so that the actual braking current approaches the target value.

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