What do we need to know about controllers?

1 What is a controller?

The controller, also known as the Body Control Module (BCM), is the central control unit for vehicle accessory control. It communicates through CAN/LIN bus or hardwired connections to control functions such as internal and external lighting, window operation, keyless entry and start system, anti-theft alarm control, and wiper control. Power and voltage requirements: Select an appropriate controller based on the power and voltage requirements of the electric bicycle. Power is typically measured in watts (W), and the voltage can be direct current (e.g., 36V, 48V)

2 categories

2.1 Sine wave controller

A sine wave controller is a type of motor controller used in AC motor drives. Its main function is to convert DC power from a DC power source (such as a battery) into AC power to drive an AC motor. Compared with traditional square wave controllers, sine wave controllers can control the speed and torque of the motor more precisely, and provide smoother and more efficient drive performance.

2.2 Dual-mode controller

A dual-mode controller is a motor controller for electric vehicles that combines two different control modes, usually a pedal-assist mode and an electric-only mode. In the pedal assist mode, the dual-mode controller can control the output power of the motor by sensing the stepping force of the pedal. When the rider starts to step on the pedals, the controller will detect the pedaling force, and correspondingly provide the output power of the motor to assist the rider's pedaling force, thus providing additional power. This mode can make riding easier and extend the range of the battery.

In pure electric mode, the dual-mode controller can directly control the output power of the motor through control devices such as handles or buttons. You can choose to rely entirely on the electric motor for power without pedaling, for pure electric drive. This mode is suitable for long-time driving or when the pedals are tired.

3 How to choose a controller

3.1Select the controller type that matches the motor type.

For example, brushed DC, brushless DC, square wave or sine wave, with Hall, without Hall, etc.

3.2Before choosing a controller, check whether the motor power marked on the motor is the rated power or the maximum power. 

If the marked power is the rated power, you can choose the matching motor controller according to 2~3 times the rated power. For example, if the nominal rated power of the motor is 650W and the voltage is 48V, select the motor controller with a rated voltage of 48V and a maximum output power of 1.3KW~2KW. If the motor is marked with the maximum working power, you can choose a motor with a slightly smaller power than the motor for matching.

3.3 Match the motor parameters.

Taking the brushless DC motor as an example, for the square wave controller, there is generally no need to match special parameters with and without Hall. If a Hall sine wave controller needs speed output, parameters such as the number of motor pole pairs and rotational speed are required. When performing program matching without a Hall sine wave, parameters such as motor phase inductance, phase resistance, number of pole pairs, and maximum motor speed need to be analyzed.

 If the power of the selected controller is too large, the output phase current of the motor will be greater than the maximum bearing capacity of the motor when the motor is working under heavy load. Short-term light load use generally does not cause damage to the motor, but if it is used for a long time with a large load, it will cause serious heating of the motor, damage the Hall sensor inside the motor, and even burn out the stator winding of the motor.