An electric bicycle controller is a component that links all the electrical pieces on a bike together. It links parts such as the battery, motor, throttle, display, pedal assist and various sensors. An e-bike controller is a small computer acting as the heart of the bicycle. It manages the overall function of the bike.
Generally, e-bike controllers are housed in a sealed protective case. The controller can be placed open on the bike; but, some designs are mounted inside the frame and concealed.
As the computer of the e-rickshaw, the controller has sensors and firmware inside the circuit board. It manages all the inputs and outputs for controlling the key functions of your rickshaw. It accepts input from the user and takes power from the battery and distributes it to essential functions like turning on the LCD screen, throttling, switching lights, and powering the motor for pedal assist levels.
The main function of the controller is to accept inputs from all e-bike components, such as throttle, battery, speed sensor, display, motor, etc., and determine the signals to be returned. Different controllers are designed with various protection measures.
Low voltage protection - A controller keeps monitoring the battery voltage and every time the voltage reaches its cutoff level, it shuts down the motor. It protects the battery from over-discharge.
Over-voltage protection - The controller also detects the charging level of the battery voltage. It shuts down when the battery voltage reaches complete charge.
Over-temperature protection - The controller monitors the temperature of the FETs (Field Effect Transistors). Any time they become overheated, it will shut down the motor.
Over-current protection - The controller cuts the current flow to the motor if the motor needs more current. This protects the motor windings and FET power transistors.
Brake protection -This controller gives more priority to the brake signal than other controllers. For example, if you press the brake and throttle at the same time, it will execute the brake function.
The most popular type of motor and controller in electric bicycles would be the BLDC (Brushless DC motor). This is a brushless motor with permanent magnets.
They are pretty reliable, efficient and relatively simple to design and operate.
BLDC controllers typically come in 3 stages, controlled by a set of keys with at least 2 transistors per phase (keys/MOSFETs). Thus, there are 6, 12 and 18 keys (multiples of 6).
Brushed motors have permanent magnets and a collector. Their design is much simpler, indeed, it is just a set of keys which change the current supplied to the engine.
This kind of controller is mainly used for small electric vehicles, such as scooters, electric bicycles, pedal bikes, e-bikes and other light electric vehicles.
Most 36V controllers may have protection circuitry that limits the voltage, which means most of the time this won't be a problem; but you should never use a controller that is rated for less than the battery pack voltage and motor operating voltage, as this will potentially over-current and overheat, causing damage to the controller. In addition, your motor may not reach its rated output.
The e-bike controller connects all the electrical components together. Once you pull the throttle or start pedalling the pedal assist model, you will connect an electrical switch to create a complete circuit where the current can flow.