Assistance control system of electric bicycle

Abstract

The invention belongs to the technical field of electric bicycles, and particularly relates to a power-assisted control system of an electric bicycle, which comprises a pedal monitoring module used for monitoring whether pedals are subjected to treading pressure of a rider; the assistance judging module judges whether the rider needs assistance or not on the basis of whether the pedals are stressed or not, specifically, the pressure borne by the pedals is obtained through the pedal monitoring module, and if the pedals are subjected to the treading pressure of the rider, the assistance judging module judges that the rider needs assistance; if the pedal is not subjected to the treading pressure of the rider, the assistance judgment module judges that the rider does not need assistance; the speed monitoring module is used for monitoring the riding speed of the electric bicycle in the power assisting state; the power-assisted control module selects a power-assisted control mode based on the riding speed of the electric bicycle in the power-assisted state, and the power-assisted control mode comprises forward power-assisted control and reverse power-assisted control.

Description

Technical Field

[0001] The invention belongs to the technical field of electric bicycles, in particular to a power-assist control system of an electric bicycle. Background Art

[0002] The intelligent power-assist technology for electric bicycles is mainly aimed at high-end power-assist bicycles (such as mountain bikes and road bikes). Its core task is to achieve an effective combination of manpower and electricity, improve rider comfort, reduce motor wear and increase motor service life.

[0003] Traditional electric bicycle power-assist control systems usually use strain gauge torque sensors or magnetic induction torque sensors; the power-assist system includes a motor, a battery and a controller. When the bicycle is heading against the wind, going uphill or loaded, the power-assist system can provide power to the bicycle to reduce the difficulty of riding.

[0004] However, existing electric bicycle power-assist systems mostly use simple power-assist methods and are unable to intelligently adjust the power-assist according to the rider's actual situation and riding environment, resulting in a poor riding experience and energy waste; existing power-assist technologies will generate instantaneous large current discharge when directly switching circuits, which will shorten the battery life and range.

[0005] To this end, the present invention provides a power-assist control system for an electric bicycle. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a power-assist control system of an electric bicycle described in the present invention comprises:

[0008] Pedal monitoring module: The pedal monitoring module is used to monitor whether the pedal is subjected to pedaling pressure from the rider;

[0009] Power assist judgment module: The power assist judgment module determines whether the rider needs power assist based on whether the pedal is under force, specifically:

[0010] The pedal pressure is obtained through the pedal monitoring module. If the pedal is subjected to the pedal pressure of the rider, the power assist judgment module determines that the rider needs power assist.

[0011] If the pedal is not subjected to pedaling pressure from the rider, the power assistance determination module determines that the rider does not need power assistance;

[0012] Speed ​​monitoring module: The speed monitoring module is used to monitor the riding speed of the electric bicycle in the power-assisted state;

[0013] Power-assist control module: The power-assist control module selects a power-assist control mode based on the riding speed of the electric bicycle in the power-assist state. The power-assist control mode includes forward power-assist control and reverse power-assist control, specifically:

[0014] If the pedal is under pressure from the rider, and the power assist judgment module determines that the rider needs power assist, the current speed V of the electric bicycle is obtained. a ;

[0015] If V a ≤V b , the power-assistance control module outputs a positive power-assistance control signal;

[0016] If V a >V b , the power-assistance control module outputs a reverse power-assistance control signal;

[0017] Among them, V b is the speed threshold of the electric bicycle; the speed threshold of the electric bicycle V b It is determined by traffic driving rules and ensuring smooth driving. b The possible value is 15km / h.

[0018] Preferably, the speed monitoring module is also used to detect the current driving state of the electric bicycle, specifically:

[0019] The driving states of electric bicycles are divided into two categories: stable driving and loaded driving.

[0020] The power assist control module further adjusts the output torque type of the motor based on the current driving state of the electric bicycle and the power assist state, and the output torque type of the motor includes increasing torque and reducing torque;

[0021] If the electric bicycle is currently traveling with a load, the power-assist control system outputs a signal for the motor to increase torque;

[0022] If the electric bicycle is currently running smoothly, the power-assist control system outputs a signal for the motor to reduce torque;

[0023] It should be noted that steady running refers to a running state when the speed and acceleration of the electric bicycle are relatively stable, while loaded running refers to a running state when the speed and acceleration of the electric bicycle are relatively unstable.

[0024] Preferably, the driving state of the electric bicycle is load driving, which includes: climbing driving, load driving and headwind driving;

[0025] The driving state of the electric bicycle is stable driving, which includes: downhill driving, flat road driving and reverse deceleration driving.

[0026] Preferably, the power assist control module further adjusts the motor voltage or current based on the output torque type of the motor;

[0027] If the current motor receives a torque increase signal and the current motor signal value μ1 is positive, the power assist control module outputs an increase in voltage or current, so that the output torque and speed of the motor increase;

[0028] If the current motor receives a torque reduction signal and the signal value μ1 of the current motor is a negative value, the power assist control module outputs a reduced voltage or current, so that the output torque and speed of the motor increase.

[0029] Preferably, the signal value μ1 of the motor is calculated based on the total driving force of the electric bicycle;

[0030] The total driving force of the electric bicycle includes the sum of the driving force provided by the motor and the driving force provided by the rider through pedaling;

[0031] Get the driving force F1 provided by the motor and the torque T applied by the rider on the pedal r , the driving force F1 provided by the motor and the torque T applied by the rider on the pedal r The actual driving force of the electric bicycle is F2 after adding them together;

[0032] Get the expected driving force F of the electric bicycle g ;

[0033] The expected driving force F of the electric bicycle g The difference between the actual driving force of the electric bicycle F2 is calculated to obtain the error value e(t)

[0034] e(t)=F g -F2;

[0035] Establish a PID control model; transmit the obtained error value e(t) to the PID control model, and calculate the signal value μ1 of the motor through the PID control model;

[0036] The voltage or current of the motor is adjusted according to the signal value μ1 of the motor, thereby adjusting the output torque and speed of the motor.

[0037] Preferably, the signal value μ1 of the motor is calculated by the PID control model in the following manner:

[0038] Motor signal value

[0039] Where K p is the proportional gain; K i is the integral gain; K d is the differential gain;

[0040] ∫e(t)dt is the error product; is the error change rate;

[0041] Among them, the proportional gain K p The product K of the error e(t) p *e(t) represents the linear relationship between the controller output and the error. When the error e(t) is positive and large, the proportional control part will output a large positive value, which will cause the motor signal value μ1 to increase, thereby increasing the motor input current to reduce the error and push the motor closer to the desired state;

[0042] Integral gain K i The product of the error accumulation ∫e(t)dt represents the relationship between the controller output and all past error accumulations. If the system error persists, the integral part will continue to increase, causing μ1 to increase, and will also trigger a signal to increase current or voltage to eliminate static errors.

[0043] Differential gain K d and error rate of change The product of represents the relationship between the controller output and the error change trend. If the error change rate suddenly increases, the differential control part will output a large positive value, causing μ1 to increase to suppress the rapid change of the error.

[0044] Among them, the proportional gain K directly affects the speed of response, and the initial value usually starts from a smaller value, such as 1; the integral gain K i Used to eliminate steady-state errors, the value can be 0.1, the differential gain K d There is a foot bath to reduce the overshoot of the system and improve stability, and the value can be 0.05;

[0045] If the motor signal value μ1>0, the power assist control module outputs a signal to increase the motor voltage or current;

[0046] If the motor signal value μ1<0, the power assist control module outputs a signal to reduce the motor voltage or current;

[0047] Specifically, when μ1>0, that is, a positive value, it usually means that the actual output of the system is lower than the expected output (e(t) is a negative value). The system needs to increase the input voltage or current of the motor to increase the output torque and speed of the motor so that the actual output of the system is closer to the expected output;

[0048] When μ1<0, that is, it is a negative value, it usually means that the actual output of the system is higher than the expected output (e(t is a positive value); the system needs to reduce the input voltage or current of the motor to reduce the output torque and speed of the motor so that the actual output of the system is close to the expected output; ensure that the output torque and speed of the motor can adapt to changes in riding conditions, such as speed, load, slope, etc., to achieve the best riding experience and energy efficiency.

[0049] Improve riding experience: The intelligent control system can automatically adjust the power assistance according to the rider's pedaling force and speed, providing a smoother and more natural power assistance experience. This "human power + electric power" hybrid drive mode makes the riding feel closer to that of a traditional bicycle while reducing the burden on the rider.

[0050] Preferably, the torque T applied by the rider on the pedal is r The calculation is as follows:

[0051] The pedal monitoring module is also used to obtain the force applied by the rider on the pedal and the pedaling frequency D1, where the pedaling frequency is the number of revolutions per minute; wherein the torque sensor can obtain the force applied by the rider on the pedal and transmit it to the controller;

[0052] The power P of an electric bike is calculated by multiplying the force applied by the rider on the pedals by the length of the crank and the cadence;

[0053] The torque applied by the rider on the pedals

[0054] Where ω is the angular velocity of the driving wheel;

[0055] Among them, the number of revolutions can be converted into angular velocity through the pedaling frequency D1 of the electric bicycle, that is, the number of revolutions per minute; D1 is the cadence.

[0056] Preferably, the desired driving force F of the electric bicycle is g It includes: the sum of rolling resistance F5, air resistance F6 during driving, acceleration resistance F7 and gravity component F8 caused by slope;

[0057] F g =F5+F6+F7+F8;

[0058] The rolling resistance F5 is the rolling resistance of the electric vehicle during driving, which is calculated by multiplying the rolling resistance coefficient (generally between 0.01 and 0.02), the total weight of the electric bicycle and the rider, and the acceleration of gravity;

[0059] The air resistance F6 during driving is obtained based on the air resistance sensor;

[0060] The acceleration resistance F7 is calculated by multiplying the acceleration of the electric bicycle during acceleration by the total weight of the electric bicycle and the rider.

[0061] Preferably, it is characterized in that: the driving force F1 provided by the motor is specifically calculated as follows:

[0062] where Y m is the output torque of the motor, x1 is the output speed of the motor, and γ is the wheel radius;

[0063] By monitoring the motor status in real time, the risk of failure can be determined in advance, and corresponding protective measures can be taken to ensure the safety of the electric bicycle. In intense driving situations, the optimized control strategy can also ensure the stability of the vehicle and effectively prevent accidents.

[0064] Preferably, the power-assist control system includes a torque sensor, a speed sensor, an acceleration sensor and a pressure sensor.

[0065] The beneficial effects of the present invention are as follows:

[0066] The power-assist control system of an electric bicycle described in the present invention can reduce the torque output of the motor when the speed and acceleration of the electric bicycle are relatively stable, because the rider can achieve stable riding by relying on his own pedaling force; when the speed and acceleration of the electric bicycle are relatively unstable, the motor needs to increase the torque to provide sufficient power support under a large load; by intelligently adjusting the motor output signal, it can adapt to different riding conditions and improve riding comfort and efficiency; and through the torque sensor component, the pedaling torque received by the central axis is converted into axial displacement deformation; the purpose of jointly driving by motor power assistance and human pedaling is achieved, making the riding process labor-saving and energy-saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The present invention will be further described below in conjunction with the accompanying drawings.

[0068] Figure 1 It is a perspective view of the present invention. DETAILED DESCRIPTION

[0069] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0070] like Figure 1 As shown, a power-assist control system of an electric bicycle according to an embodiment of the present invention comprises a pedal monitoring module, a power-assist judgment module, a speed monitoring module and a power-assist control module;

[0071] Existing electric bicycle power-assist systems mostly use simple power-assist methods and cannot intelligently adjust the power-assist according to the actual situation of the rider and the riding environment, resulting in a poor riding experience and energy waste;

[0072] Pedal monitoring module: The pedal monitoring module is used to monitor whether the pedal is subjected to pedaling pressure from the rider;

[0073] Power assist judgment module: The power assist judgment module determines whether the rider needs power assist based on whether the pedal is under force, specifically:

[0074] The pedal pressure is obtained through the pedal monitoring module. If the pedal is subjected to the pedal pressure of the rider, the power assist judgment module determines that the rider needs power assist.

[0075] If the pedal is not subjected to pedaling pressure from the rider, the power assistance determination module determines that the rider does not need power assistance;

[0076] Based on the force of the rider's pedaling, when the rider starts pedaling, the torque sensor will detect this action and transmit it to the controller, which will then control the auxiliary force of the motor based on this information to achieve assisted riding. When the rider does not pedal, it means that the rider only needs electricity to ride, and does not need power-assisted riding. The rider only needs to control the speed by himself.

[0077] Speed ​​monitoring module: The speed monitoring module is used to monitor the riding speed of the electric bicycle in the power-assisted state;

[0078] Power-assist control module: The power-assist control module selects a power-assist control mode based on the riding speed of the electric bicycle in the power-assist state. The power-assist control mode includes forward power-assist control and reverse power-assist control, specifically:

[0079] If the pedal is under pressure from the rider, and the power assist judgment module determines that the rider needs power assist, the current speed V of the electric bicycle is obtained. a ;

[0080] If V a ≤V b , the power-assistance control module outputs a positive power-assistance control signal;

[0081] If V a >V b , the power-assistance control module outputs a reverse power-assistance control signal;

[0082] Among them, V b is the speed threshold of the electric bicycle; the speed threshold of the electric bicycle V b It is determined by traffic driving rules and ensuring smooth driving. b The possible value is 15km / h.

[0083] It can intelligently adjust the power assistance according to the rider's pedaling torque, cadence and vehicle speed, improving riding comfort and safety while also improving energy efficiency;

[0084] Among them: In electric bicycles, positive power control usually refers to the motor providing auxiliary force to help the rider when the rider's pedaling force is small or when additional power is needed at starting, uphill, etc. This control strategy makes the rider feel relaxed when more power is needed, because the motor will provide corresponding auxiliary force according to the rider's pedaling force and speed. Positive power control can detect the rider's pedaling force and pedaling frequency through sensors, and then adjust the motor output based on these data to provide appropriate auxiliary force. This control strategy helps improve riding efficiency and comfort.

[0085] Reverse power control may refer to reducing the motor's assist when the e-bike is riding at high speeds, or even providing slight resistance in some cases, to improve riding safety and control. This control strategy helps prevent instability or loss of control due to excessive motor assist when riding at high speeds. When riding at high speeds, the rider needs to have more precise control over the bicycle, so reducing the motor's assist can give the rider more control and also help save energy;

[0086] The speed monitoring module is also used to detect the current driving state of the electric bicycle, specifically:

[0087] The driving states of electric bicycles are divided into two categories: stable driving and loaded driving.

[0088] The power assist control module further adjusts the output torque type of the motor based on the current driving state of the electric bicycle and the power assist state, and the output torque type of the motor includes increasing torque and reducing torque;

[0089] If the electric bicycle is currently traveling with a load, the power-assist control system outputs a signal for the motor to increase torque;

[0090] If the electric bicycle is currently running smoothly, the power-assist control system outputs a signal for the motor to reduce torque;

[0091] It should be noted that steady running refers to a running state when the speed and acceleration of the electric bicycle are relatively stable, while loaded running refers to a running state when the speed and acceleration of the electric bicycle are relatively unstable;

[0092] When the speed and acceleration of the electric bicycle are relatively stable, the torque output of the motor can be reduced, because the rider can achieve stable riding by relying on his own pedaling force; when the speed and acceleration of the electric bicycle are relatively unstable, the motor needs to increase the torque to provide sufficient power support under heavy load; by intelligently adjusting the motor output signal, it can adapt to different riding conditions and improve riding comfort and efficiency; and the pedaling torque received by the middle axis is converted into axial displacement deformation through the torque sensor component; the purpose of joint driving by motor assistance and human pedaling is achieved, making the riding process labor-saving and energy-saving;

[0093] Based on the driving state of the electric bicycle, the load driving includes: climbing driving, load driving and driving against the wind;

[0094] Among them, when climbing a slope, the acceleration of the electric bicycle will decrease because it needs to overcome gravity. The acceleration sensor can be used to detect the acceleration change of the vehicle. When the acceleration is detected to be lower than the normal level, it can be determined that the vehicle is climbing a slope;

[0095] Load detection:

[0096] An increase in load will cause an increase in the load on the suspension system and wheels of the electric bicycle. A pressure sensor can be installed on the tire or suspension system to detect changes in load. When the pressure detected by the sensor exceeds a preset threshold, it can be determined that the vehicle load has increased.

[0097] Headwind Detection:

[0098] Headwind will increase riding resistance and cause the speed of the electric bicycle to decrease. The wind speed and the speed of the electric bicycle can be detected by a speed sensor and anemometer. When the speed decreases and the wind speed increases, it can be determined that the vehicle is in a headwind state;

[0099] Based on the fact that the driving state of the electric bicycle is stable driving, it includes: downhill driving, flat road driving and reverse deceleration driving;

[0100] Downhill detection:

[0101] When going downhill, the gravity component of the electric bicycle increases, causing the speed to naturally increase. Downhill can be detected by the speed sensor and the acceleration sensor. When the speed continues to increase and the acceleration sensor detects downward acceleration, it can be judged that the vehicle is going downhill.

[0102] Flat road detection:

[0103] On a flat road, the speed and acceleration of an electric bicycle are relatively stable. The changes in speed and acceleration can be monitored by speed sensors and acceleration sensors. If both speed and acceleration remain at a relatively stable level, it can be determined that the vehicle is traveling on a flat road.

[0104] Deceleration detection:

[0105] When decelerating, the speed of the electric bicycle will decrease, and the speed change can be detected by the speed sensor. When the speed continues to decrease, it can be judged that the vehicle is decelerating. In addition, if the use of the brakes is detected (via the brake sensor), it can also be used as a signal for deceleration.

[0106] The power assist control module further adjusts the motor voltage or current based on the output torque type of the motor;

[0107] If the current motor receives a torque increase signal and the current motor signal value μ1 is positive, the power assist control module outputs an increase in voltage or current, so that the output torque and speed of the motor increase;

[0108] If the current motor receives a torque reduction signal and the current motor signal value μ1 is negative, the power assist control module outputs a reduced voltage or current, so that the output torque and speed of the motor increase;

[0109] Increasing the current will directly result in an increase in the motor's output torque, since output torque is proportional to current and vice versa;

[0110] Increasing the voltage will increase the back electromotive force of the motor, thereby increasing the output speed of the motor, and vice versa; the torque sensor detects the pedaling force, and the speed sensor detects the pedaling speed. The two signals are transmitted to the controller through the communication interface. The controller analyzes and processes the two signals to determine the output torque and speed of the motor, thereby achieving the purpose of joint drive by motor assistance and human pedaling.

[0111] Calculate the signal value μ1 of the motor based on the total driving force of the electric bicycle;

[0112] The total driving force of the electric bicycle includes the sum of the driving force provided by the motor and the driving force provided by the rider through pedaling;

[0113] Get the driving force F1 provided by the motor and the torque T applied by the rider on the pedal r , the actual driving force of the electric bicycle is F2 obtained by adding the driving force F1 provided by the motor and the torque Tx applied by the rider on the pedal;

[0114] Get the expected driving force F of the electric bicycle g ;

[0115] The expected driving force F of the electric bicycle g The difference between the actual driving force of the electric bicycle F2 is calculated to obtain the error value e(t);

[0116] e(t)=F g -F2;

[0117] Establish a PID control model; transmit the obtained error value e(t) to the PID control model, and calculate the signal value μ1 of the motor through the PID control model;

[0118] The voltage or current of the motor is adjusted according to the signal value μ1 of the motor, thereby adjusting the output torque and speed of the motor.

[0119] Specifically, by real-time monitoring of the motor control signal μ1, the problem of side slip or rollover caused by excessive steering torque of the electric bicycle can be solved, and driving safety can be improved. Because when the steering torque of the electric bicycle is too large, the torque that the rider needs to apply exceeds the torque required for normal driving, which may cause steering to be too sensitive or difficult, thereby increasing the risk of side slip or rollover and affecting driving safety.

[0120] And it can adapt to different riding conditions: electric bicycles can dynamically adjust the power ratio according to actual riding conditions (such as slope, wind speed, etc.) to improve steering stability and driving safety. For example, it can increase torque output when going uphill or against the wind to provide sufficient power support.

[0121] The power assist ratio is the proportional relationship between the motor output torque and the rider's pedaling torque; the power assist ratio k can also be determined by the vehicle speed. It should be noted that the purpose of the PID control model is to reduce or eliminate the error value e(t) between the actual output and the expected output, where P is the proportional part, which responds to the current error, I is the integral part, which accumulates past errors, and D is the differential part, which predicts the future trend of the error. The parameters of the PID control model are generally determined by mathematical optimization techniques, such as genetic algorithms or particle swarm optimization, to find the optimal PID parameters. By establishing the PID control model, the system can be controlled to respond to increase or decrease the input voltage or current of the motor.

[0122] The signal value μ1 of the motor is specifically calculated by the PID control model as follows:

[0123] Motor signal value

[0124] Where K p is the proportional gain; K i is the integral gain; K d is the differential gain;

[0125] ∫e(t)dt is the error product; is the error change rate;

[0126] Among them, the proportional gain K p The product K of the error e(t) p *e(t) represents the linear relationship between the controller output and the error. When the error e(t) is positive and large, the proportional control part will output a large positive value, which will cause the motor signal value μ1 to increase, thereby increasing the motor input current to reduce the error and push the motor closer to the desired state;

[0127] Integral gain K i The product of the error accumulation ∫e(t)dt represents the relationship between the controller output and all past error accumulations. If the system error persists, the integral part will continue to increase, causing μ1 to increase, and will also trigger a signal to increase current or voltage to eliminate static errors.

[0128] Differential gain K d and error rate of change The product of represents the relationship between the controller output and the error change trend. If the error change rate suddenly increases, the differential control part will output a large positive value, causing μ1 to increase to suppress the rapid change of the error.

[0129] Among them, the proportional gain K p Directly affects the speed of response. Generally, the initial value starts from a smaller value, such as 1; integral gain K i Used to eliminate steady-state errors, the value can be 0.1, the differential gain K d There is a foot bath to reduce the overshoot of the system and improve stability, and the value can be 0.05;

[0130] If the motor signal value μ1>0, the power assist control module outputs a signal to increase the motor voltage or current;

[0131] If the motor signal value μ1<0, the power assist control module outputs a signal to reduce the motor voltage or current;

[0132] Specifically, when μ1>0, that is, a positive value, it usually means that the actual output of the system is lower than the expected output (e(t) is a negative value). The system needs to increase the input voltage or current of the motor to increase the output torque and speed of the motor so that the actual output of the system is closer to the expected output;

[0133] When μ1<0, that is, it is a negative value, it usually means that the actual output of the system is higher than the expected output (e(t is a positive value); the system needs to reduce the input voltage or current of the motor to reduce the output torque and speed of the motor so that the actual output of the system is close to the expected output; ensure that the output torque and speed of the motor can adapt to changes in riding conditions, such as speed, load, slope, etc., to achieve the best riding experience and energy efficiency.

[0134] Improve riding experience: The intelligent control system can automatically adjust the power assistance according to the rider's pedaling force and speed, providing a smoother and more natural power assistance experience. This "human power + electric power" hybrid drive mode makes the riding feel closer to that of a traditional bicycle while reducing the burden on the rider.

[0135] The torque T applied by the rider on the pedals r The calculation is as follows:

[0136] The pedal monitoring module is also used to obtain the force applied by the rider on the pedal and the pedaling frequency D1, where the pedaling frequency is the number of revolutions per minute; wherein the torque sensor can obtain the force applied by the rider on the pedal and transmit it to the controller;

[0137] The power P of an electric bike is calculated by multiplying the force applied by the rider on the pedals by the length of the crank and the cadence;

[0138] The torque applied by the rider on the pedals

[0139] Where ω is the angular velocity of the driving wheel;

[0140] Among them, the number of revolutions can be converted into angular velocity through the pedaling frequency D1 of the electric bicycle, that is, the number of revolutions per minute; D1 is the cadence;

[0141] The pedal torque T calculated by r , used to control the auxiliary force of the motor and realize power-assisted control; by controlling the output torque of the motor, the energy efficiency and endurance can be improved: by precisely controlling the torque and speed of the motor, energy consumption can be reduced, the energy efficiency and endurance of the electric bicycle can be improved, and reducing the torque output when driving on flat roads or at low speeds can save electricity and extend battery life.

[0142] The desired driving force F of the electric bicycle g It includes: the sum of rolling resistance F5, air resistance F6 during driving, acceleration resistance F7 and gravity component F8 caused by slope;

[0143] F g =F5+F6+F7+F8;

[0144] The rolling resistance F5 is the rolling resistance of the electric vehicle during driving, which is calculated by multiplying the rolling resistance coefficient (generally between 0.01 and 0.02), the total weight of the electric bicycle and the rider, and the acceleration of gravity;

[0145] The air resistance F6 during driving is obtained based on the air resistance sensor;

[0146] The acceleration resistance F7 is calculated by multiplying the acceleration of the electric bicycle during acceleration by the total weight of the electric bicycle and the rider.

[0147] The specific calculation method of the driving force F1 provided by the motor is:

[0148] where Y m is the output torque of the motor, x1 is the output speed of the motor, and γ is the wheel radius;

[0149] By monitoring the motor status in real time, the risk of failure can be determined in advance, and corresponding protective measures can be taken to ensure the safety of the electric bicycle. In intense driving situations, the optimized control strategy can also ensure the stability of the vehicle and effectively prevent accidents.

[0150] The power assist control system includes a torque sensor, a speed sensor, an acceleration sensor and a pressure sensor.

[0151] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A power-assist control system for an electric bicycle, characterized in that: include: Pedal monitoring module: The pedal monitoring module is used to monitor whether the pedal is subjected to pedaling pressure from the rider; Power assist judgment module: The power assist judgment module determines whether the rider needs power assist based on whether the pedal is under force, specifically: The pedal pressure is obtained through the pedal monitoring module. If the pedal is subjected to the pedal pressure of the rider, the power assist judgment module determines that the rider needs power assist. If the pedal is not subjected to pedaling pressure from the rider, the power assistance determination module determines that the rider does not need power assistance; Speed ​​monitoring module: The speed monitoring module is used to monitor the riding speed of the electric bicycle in the power-assisted state; Power-assist control module: The power-assist control module selects a power-assist control mode based on the riding speed of the electric bicycle in the power-assist state. The power-assist control mode includes forward power-assist control and reverse power-assist control, specifically: If the pedal is under pressure from the rider, and the power assist judgment module determines that the rider needs power assist, the current speed V of the electric bicycle is obtained. a ; If V a ≤V b , the power-assistance control module outputs a positive power-assistance control signal; If V a >V b , the power-assistance control module outputs a reverse power-assistance control signal; Among them, V b is the speed threshold for electric bicycles.

2. The power-assist control system of an electric bicycle according to claim 1, characterized in that: The speed monitoring module is also used to detect the current driving state of the electric bicycle, specifically: The driving states of electric bicycles are divided into two categories: stable driving and loaded driving. The power assist control module further adjusts the output torque type of the motor based on the current driving state of the electric bicycle and the power assist state, and the output torque type of the motor includes increasing torque and reducing torque; If the electric bicycle is currently traveling with a load, the power-assist control system outputs a signal for the motor to increase torque; If the electric bicycle is currently running steadily, the power-assist control system outputs a signal for the motor to reduce torque.

3. The power-assist control system of an electric bicycle according to claim 2, characterized in that: Said Based on the driving state of the electric bicycle, the load driving includes: climbing driving, load driving and driving against the wind; The driving state of the electric bicycle is stable driving, which includes: downhill driving, flat road driving and reverse deceleration driving.

4. The power-assist control system of an electric bicycle according to claim 2, characterized in that: The power assist control module further adjusts the motor voltage or current based on the output torque type of the motor; If the current motor receives a torque increase signal and the current motor signal value μ1 is positive, the power assist control module outputs an increase in voltage or current; If the current motor receives a torque reduction signal and the signal value μ1 of the current motor is negative, the power assist control module outputs a reduced voltage or current.

5. The power-assist control system of an electric bicycle according to claim 4, characterized in that: Calculate the signal value μ1 of the motor based on the total driving force of the electric bicycle; The total driving force of the electric bicycle includes the sum of the driving force provided by the motor and the driving force provided by the rider through pedaling; Get the driving force F1 provided by the motor and the torque T applied by the rider on the pedal r , the driving force F1 provided by the motor and the torque T applied by the rider on the pedal r The actual driving force of the electric bicycle is F2 after adding them together; Get the expected driving force F of the electric bicycle g ; The expected driving force F of the electric bicycle g The difference between the actual driving force of the electric bicycle F2 is calculated to obtain the error value e(t); e(t)=F g -F2; Establish a PID control model; transmit the obtained error value e(t) to the PID control model, and calculate the signal value μ1 of the motor through the PID control model; The voltage or current of the motor is adjusted according to the signal value μ1 of the motor, thereby adjusting the output torque and speed of the motor.

6. The power-assist control system of an electric bicycle according to claim 5, characterized in that: The signal value μ1 of the motor is specifically calculated by the PID control model as follows: Motor signal value Where K p is the proportional gain; K i is the integral gain; K d is the differential gain; ∫e(t)dt is the error product; is the error change rate; If the motor signal value μ1>0, the power assist control module outputs a signal to increase the motor voltage or current; If the motor signal value μ1 is less than 0, the power assist control module outputs a signal to reduce the motor voltage or current.

7. The power-assist control system of an electric bicycle according to claim 6, characterized in that: The torque T applied by the rider on the pedals r The calculation is as follows: The pedal monitoring module is also used to obtain the force applied by the rider on the pedal and the pedaling frequency D1, where the pedaling frequency is the number of revolutions per minute; The power P of an electric bike is calculated by multiplying the force applied by the rider on the pedals by the length of the crank and the cadence; The torque applied by the rider on the pedals Where ω is the angular velocity of the driving wheel; Among them, the number of revolutions can be converted into angular velocity through the pedaling frequency D1 of the electric bicycle, that is, the number of revolutions per minute; D1 is the cadence.

8. The power-assist control system of an electric bicycle according to claim 7, characterized in that: The desired driving force F of the electric bicycle g It includes: the sum of rolling resistance F5, air resistance F6 during driving, acceleration resistance F7 and gravity component F8 caused by slope; F g =F5+F6+F7+F8。 9. The power-assist control system of an electric bicycle according to claim 7, characterized in that: The specific calculation method of the driving force F1 provided by the motor is: where Y m is the output torque of the motor, x1 is the output speed of the motor, and γ is the wheel radius.

10. The power-assist control system of an electric bicycle according to claim 1, characterized in that: The power assist control system includes a torque sensor, a speed sensor, an acceleration sensor and a pressure sensor.

Images