What is the operation principle of an electric bicycle

Electrical power generating system

1. Battery composition and type

Electric bicycles generally use rechargeable batteries as a power source, among which lithium batteries are widely used because of their advantages of high energy density, long life and low self-discharge rate. The lithium battery contains key components such as positive electrode, negative electrode, electrolyte and diaphragm, which can store and release electric energy through chemical reaction.
2.electric energy storage and release
Electrical energy storage: When the battery is charged, an external power source (such as a charger) delivers electrical energy to the battery through a specific charging circuit. The electrical energy is converted into chemical energy and stored in the positive and negative electrode materials of the battery, while the ions in the electrolyte also undergo corresponding migration and rearrangement to form a stable chemical structure.
Electrical energy release: When the battery is discharged, the chemical energy inside the battery begins to be converted into electrical energy. During the discharge process, the positive and negative electrode materials undergo a chemical reaction, releasing electrons and ions. Electrons flow to electrical equipment such as motors through external circuits to form current; Ions migrate through the electrolyte inside the battery, maintaining the charge balance. In this process, the voltage of the battery is gradually reduced until the discharge ends.

3. charging and protection mechanism
Charging process: When charging, the charger converts alternating current to direct current and connects to the battery through the charging interface. The control circuit inside the charger monitors the battery's voltage, current and temperature to ensure a safe and efficient charging process. When the battery is fully charged, the charger will automatically cut off the power to prevent the occurrence of overcharging.
Protection mechanism: In order to ensure the safety and service life of the battery, the Electric Bicycle power system is usually equipped with a variety of protection mechanisms. These mechanisms include overcharge protection, overdischarge protection, short circuit protection, temperature protection and so on. When the battery is abnormal, the protection mechanism will respond quickly and cut off the power or adjust the charging/discharging strategy to prevent the battery from being damaged or causing safety accidents.
4. Energy management and optimization
With the development of science and technology, modern electric bicycle power systems also have energy management and optimization functions. Through intelligent control algorithms and sensor technology, the power supply system can monitor the battery's electricity, voltage, current, temperature and other parameters in real time, and dynamically adjust the output power of the motor and the discharge rate of the battery according to the needs of the rider and road condition information. This can not only improve the endurance of the electric bicycle, but also extend the service life of the battery and reduce energy consumption.

Control system

Signal processing

Signal reception: The controller receives control signals from the handle (turn lever) or the pedal, which reflect the user's operation intention, such as acceleration, deceleration, braking, etc.
Signal analysis and processing: The controller analyzes and processes the received signal, determines the user's operation intention by measuring the strength and direction of the signal, and formulates the corresponding control strategy accordingly.

Current control
Current regulation: According to the result of signal processing, the controller controls the output current by adjusting the switching state of the switching element (such as the MOS tube) in the current controller. The purpose of this step is to provide the motor with the appropriate torque and power according to the different drive needs.

Motor drive

Motor control: Through the output current signal, the controller controls the phase and polarity of the motor to make the motor run normally. In general, the motor drive adopts the current feedback control mode, which is adjusted by measuring the voltage in the current loop to achieve accurate current control.

Protection function
Overcurrent protection: When the motor or load causes a sudden surge of current due to short circuit and other reasons, the controller will start the overcurrent protection mechanism to cut off the output drive signal to prevent the current from exceeding the rated value and damaging the motor or electronic control equipment.
Overvoltage protection and low voltage protection: The controller also has overvoltage protection and low voltage protection functions to prevent the motor or battery voltage from exceeding the normal operating range, causing damage or not working properly.
Temperature protection: The controller is usually equipped with a temperature protection mechanism, when the controller temperature is too high, it will automatically cut off the output to prevent damage due to overheating.

 Driving system

System composition
The drive system of an electric bicycle is mainly composed of a battery, a controller, an electric motor and a transmission device. The battery provides power as energy, the controller is responsible for processing the signal input by the user and controlling the current output, the motor converts electrical energy into mechanical energy to drive the wheels, and the transmission device is responsible for transmitting the power of the motor to the wheels.

Working principle

Battery powered:
Electric bicycles typically use rechargeable batteries as a power source, such as lithium-ion or lead-acid batteries. The battery pack is mounted on the frame and connected to the controller via wires.
When the battery is powered on, the chemical energy in the battery pack is converted into electrical energy to power the entire drive system.
Controller control:
The controller is one of the core components of the electric bicycle, which receives the control signal from the speed control handle (rotating lever) or the pedal.
These signals are processed by the controller and converted into electrical signals that control the speed and direction of the motor.
The controller contains complex circuits and microprocessors, which can achieve accurate control of current and voltage, and has a variety of protection functions (such as overcurrent protection, undervoltage protection, etc.).
Motor drive:
The electric motor of an electric bicycle usually uses a DC motor or an AC motor (converted into a DC electric drive by an inverter). The motor is mounted on the central axle of the wheel and is directly connected to the wheel.
When the controller outputs an electrical signal, the coil inside the motor generates a rotating magnetic field, which interacts with the motor's permanent magnet to generate an electromagnetic force, thereby driving the motor to rotate.
The speed and torque of the motor can be adjusted by the electrical signal of the controller to meet the riding needs of the user.

Transmission device transfers power:
The transmission device (such as chain, gear, etc.) transmits the rotating power of the motor to the wheel, making the wheel turn to push the electric bicycle forward.
The transmission device should be designed to ensure the efficiency and stability of power transmission, reducing energy loss and mechanical wear.
User action and feedback:
The user controls the speed and power output of the electric bicycle through the speed control lever or the pedal. Speed control handle can simulate rotating motion to generate electrical signals, which are transmitted to the controller to adjust the speed of the motor.
The controller also has a variety of protection functions, such as automatically cutting off the power when the battery voltage is too low to prevent battery overdischarge; When the motor is overloaded, the output power is automatically reduced to protect the motor.
Electric bicycles are usually equipped with a display device such as a dashboard, which is used to display battery power, driving speed, riding mileage and other information for users' reference.