Analysis of Electric Vehicle Controller Functions, Design, and Protection

Functions and Impact of Electric Vehicle Controllers

As a core component of the vehicle, the composition and performance of electric vehicle controllers profoundly influence the entire vehicle. The controller integrates numerous functional components, such as actuators and sensors, which work in concert to ensure the vehicle's proper operation. The microcontroller, serving as the controller's core, incorporates memory, decoders, sawtooth wave generators, and pulse width modulation (PWM) circuits. By precisely controlling the power transistors in the switching circuit, it enables accurate regulation of the motor's rotational speed.

The design quality, characteristics, and functionality of the microprocessor used in the controller directly affect the vehicle's overall performance and operational status. Simultaneously, the controller's own performance and efficiency are influenced by its layout and the power switching device circuitry. Even for the same electric vehicle equipped with batteries in identical charge/discharge states, using controllers of differing quality can result in significant variations in range capability.

Separate vs. Integrated Design
Separate design refers to isolating the controller's main unit from its display section. The display is typically mounted on the handlebars, while the controller's main body remains concealed within the vehicle's body compartment or electric box, not directly exposed. This approach effectively shortens the wiring distance between the controller, power source, and motor, resulting in a cleaner vehicle appearance.

The integrated design combines the control and display functions into a single unit housed within a specially designed plastic enclosure. This enclosure is usually mounted at the center of the handlebars. Its panel features several small holes, approximately 4-5mm in diameter, covered by a transparent waterproof membrane. Corresponding LED indicators are positioned within these holes to display speed, power status, and remaining battery charge.

Protective Functions of Gaobiao Technology Electric Bike Controllers

Next, we will explore the protective functions of Gaobiao Technology electric bike controllers.

Brake Power-Off Function
On electric bicycles, both caliper brake levers are equipped with contact switches. When the rider applies the brakes, these switches are pushed to close or open, altering their original state. This change generates a signal transmitted to the control circuit. Following a preset program, the circuit immediately cuts off the base drive current, terminating power supply and stopping operation. This design not only protects the power transistors themselves but also safeguards the motor, preventing unnecessary power waste.

Undervoltage Protection
When the power supply voltage approaches the "discharge termination voltage" during the final discharge phase, the controller panel or instrument display will indicate low battery level, alerting the rider to plan their journey. Once the power supply voltage reaches the termination point, the voltage sampling resistor shunts information to the comparator. The protection circuit then cuts off the current according to the preset program, safeguarding electronic components and the power supply.

Overcurrent Protection Function
To prevent damage or even burnout of the motor and circuit components caused by excessive current, the control circuit must incorporate overcurrent protection. Upon detecting overcurrent, the circuit will cut off the current after a certain delay to ensure safety.

Overload Protection Function
Overload protection operates similarly to overcurrent protection, as excessive load inevitably leads to excessive current. Although electric bicycle manuals specify load capacity, riders may sometimes overlook or intentionally exceed these limits. Without overload protection, damage may occur in critical components, particularly the switching power transistors. If the brushless controller's power transistors burn out, the motor's operation becomes weak, and the rider immediately feels abnormal pulsations. Therefore, overcurrent caused by overload is extremely dangerous. However, with overcurrent protection, the circuit automatically cuts off power once the load exceeds limits, preventing a series of potential consequences.

Speed Limiter Function
Pedal-assist electric bicycles feature a unique speed-limiting control program. When the vehicle exceeds a predetermined speed, the circuit ceases power supply to restrict assistance. For electric-only bicycles, the speed is uniformly capped at 20 km/h. The vehicle's motor is engineered with a fixed rated speed and control circuit. Consequently, the electric bicycle can only operate at speeds not exceeding this limit.