All you should know about sensors and controller for ebike
If the electric motor has become the “soul” of electric scooters after a century of development, then the sensors and controllers that work with the electric motor are undoubtedly the best assistants. Their application has freed electric powered bicycles from the controversy between throttle and pedal, truly embarking on the development of Pedelec.
As introduced in the previous article “Introduction to Electric Power Assistance”, the coordination work of the motor drive system is that when the rider steps on, the sensor is responsible for sensing the force and speed of the step, transmitting the monitored speed, step frequency, torque and other information to the controller. The controller sends instructions through calculation to control the motor operation.
Subdividing it further, the working principles of sensors and controller for ebike are also well understood and worth exploring by all car enthusiasts.
↑↑↑↑ SR PA310.32. ST sensor on the Octagonal official website
According to the EPAC (Electric Assisted Cycle) standard, electric powered bicycles must be started by stepping, and if stepping stops, the bicycle must also stop. The manufacturer needs to place a speed sensor on the pedal shaft, or add a sensor to measure the force (torque) that the rider places on the pedal.
Although most users of electric powered bicycles are able to independently change their riding speed, more often than not, bicycles rely on the pedal rhythm and force sensed by sensors to control their speed.
↑↑↑↑ Step frequency sensor vs torque sensor
(Image source: bikegrade. com)
Sensors can be divided into torque sensors and step frequency sensors.
As the name suggests, torque sensors obtain high-precision torque values by sensing the force of the rider’s foot pedal, thereby understanding the rider’s riding intention. The step frequency sensor is installed on the crankshaft assembly, consisting of sensing contacts and magnetic steel rings. By measuring the step frequency, the assistance demand is determined. The higher the step frequency, the stronger the assistance.
Like any system that needs to work together, the performance of an electric powered bicycle starts with the accuracy of the input signal. Generally speaking, sensors are equivalent to the sensory system of the human body, and the clearer the sensation, the better one’s judgment ability.
Compared to torque sensors, torque sensors are more complex and precise. By measuring torque, torque sensors provide more accurate input values for the controller’s operation.
A high-performance electric assisted bicycle usually uses more than just a single sensor, but a combination of pedal frequency and torque to comprehensively calculate the current riding status.
Taking Frey Evolve as an example, the M510 motor is equipped with high-precision torque and step frequency sensors, which can accurately transmit rider information based on step frequency and step force, helping the sensors determine and output assistance.
The sensor accurately transmits the input signal to the controller. After receiving torque, speed, and step frequency signals, the controller calculates the output signal to control the motor’s operating speed, start, stop, and other functions, guiding the motor on how to output power.
The controller, like a human brain, can connect all electronic components of an electric bicycle together, such as the battery, motor, accelerator, display, and various sensors. It is responsible for tracking the important functions of the electric bicycle, such as pedal activity, battery voltage, motor power, acceleration and deceleration.
(Image source: elecycles. com)
In addition, the controller also provides some simple protection functions, such as high-voltage and low-voltage protection of the battery to prevent overcharging or excessive discharge of the battery. It can also monitor the temperature and current of the motor and ensure the safety of riders through braking protection.
The controller also has the difference between sine wave and square wave, each with its own advantages and disadvantages, which will not be explained here. Many electric powered mountain bike players choose to manually replace the controller in order to pursue speed, but the wiring of the controller is complex and requires professional knowledge as assistance. It is best for Xiaobai not to try it easily.
↑↑↑↑ The complex connection lines of the Ebike controller
The algorithm of the controller is what we call the control program, also known as the “invisible hand of God” by our technical department.
For example, Evolve has Eco (most economical mode), Tour (comfortable mode), Sport (sport mode), Sport+(sport enhanced mode), Boost (maximum power mode), and Boost mode. The selection of the boost gear determines the power level during cycling, which all depend on the program’s function.
Greensky Power Co., Ltd. is a professional manufacturer engaged in the research, development, production, sale of Ebike controller.
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