What is a speed controller and what does it do? Beginner’s guide to choose the suitable controller for your electric-skateboard/electric surfboard

24 april 2020

What is a speed controller and what does it do? Beginner’s guide to choose the suitable controller for your electric-skateboard/electric surfboard

1. What is ESC (electronic speed control )?

An electronic speed control or ESC is an electronic circuit that controls and regulates the speed of an electric motor. It may also provide reversing of the motor and dynamic braking. Miniature electronic speed controls are used in electrically powered radio controlled models.

An electronic speed control follows a speed reference signal (derived from a throttle lever, joystick, or other manual input) and varies the switching rate of a network of field effect transistors (FETs) . By adjusting the duty cycle or switching frequency of the transistors, the speed of the motor is changed. The rapid switching of the transistors is what causes the motor itself to emit its characteristic high-pitched whine, especially noticeable at lower speeds.

For esk8 and efoil&esurf, ESC converts the PWM signal from remote receiver, and drives the brushless motor by providing the appropriate level of electrical power.

Different types of speed controls are required for brushed DC motors and brushless DC motors. A brushed motor can have its speed controlled by varying the voltage on its armature. (Industrially, motors with electromagnet field windings instead of permanent magnets can also have their speed controlled by adjusting the strength of the motor field current.) A brushless motor requires a different operating principle. The speed of the motor is varied by adjusting the timing of pulses of current delivered to the several windings of the motor.

Brushless ESC systems basically create three-phase AC power, like a VFD variable frequency drive, to run brushless motors. Brushless motors are popular with radio controlled airplane hobbyists because of their efficiency, power, longevity and light weight in comparison to traditional brushed motors. Brushless DC motor controllers are much more complicated than brushed motor controllers.

The correct phase varies with the motor rotation, which is to be taken into account by the ESC: Usually, back EMF from the motor is used to detect this rotation, but variations exist that use magnetic (Hall effect) or optical detectors. Computer-programmable speed controls generally have user-specified options which allow setting low voltage cut-off limits, timing, acceleration, braking and direction of rotation. Reversing the motor's direction may also be accomplished by switching any two of the three leads from the ESC to the motor.

2. What is BEC/UBEC?

BEC stands for Battery Elimination Circuit. It’s just a fancy name for voltage regulator, which converts main LiPo battery pack voltage to a lower voltage (e.g. 3S 11.1V or 4S 14.8V or more higher 12s/14s/20s to 5V or other lower voltage). BEC is usually built into ESC, and as the name suggests, it eliminates the need for a separate battery to power the 5V or other low voltage electronic devices (such as receiver of remote).

UBEC stands for universal BEC or sometimes ultimate BEC. It’s used when ESC doesn’t have built-in BEC, or standalone power system is required. They generally are more efficient, more reliable and able to provide more current than BEC. The UBEC is connected directly to the main battery.

For example,

- VESC based controllers in our shop are with built-in 5V/1.5A BEC:

-300A fully waterproof and watercooled ESC is also with built-in UBEC in the waterproof case

-300A watercooled and splash proof ESC doesn’t have BEC. So it needs a UBEC when use with the remote receiver

3. For electric skateboard, how to choose suitable ESC for your motor?

Most recommened ESC for electric skateboard is VESC based controller. Why? Please refer to FAQ1 (frequently asked questions) about VESC controller

Usually the most used motors for esk8 are 50mm-80mm motors.

Motor size	Most suitable ESCs
5055/5065 and smaller motors	MTVESC50A/SUPERFOC6.8; If you’re looking for higher grade ESCs, MTVESC100A/MTSVESC6.0/MTSVESC6.12 are also ok for these motors.
6355/6365/6374/6880 Motor	MTVESC100A/MTSVESC6.0/MTSVESC6.12 ; If you have limit budget, MTVESC50A /SUPERFOC6.8 can also work.
6396 motor	MTVESC100A/MTSVESC6.0/MTSVESC6.12
8085 motor	MTSVESC6.0/MTSVESC6.12