How to choose ESC of the drone motors?

The function of the electronic speed controller (ESC for short) is equivalent to the throttle of the drone. It can send instructions to the motor through the logic circuit board. The ESC converts the signal from the lithium polymer battery into an alternating square wave. Generally speaking, brushless motors are three-phase, and the instantaneous value of each phase changes. There are high potential, low potential and intermediate potential at any moment. It can send instructions to the motor through the logic circuit board. The ESC converts the signal from the lithium polymer battery into an alternating square wave.

Next, let's take a look at the various parameters on the ESC and their meanings, we use below ESC as example

1. Current, 30A marked on the ESC is the current, and the value usually marked on the ESC refers to the continuous output current of the ESC. In addition to this current parameter, some ESCs will also indicate the instantaneous current in the manual or parameter table.

2. 2S-3S LiPo. The string of characters on the ESC indicates how big the battery can be used, and the type of battery, which is telling what the voltage range supported by the ESC

3. In some ESCs, you will see words such as BEC written on it. This BEC Chinese translation is called a battery-free circuit. That is, there is a separate circuit module in the ESC. This circuit module can convert the battery voltage into a voltage of 5-6V to supply power to the receiver or flight controller. The advantage of this function is that it will not decrease with the voltage of the power battery. And fell. Some ESCs do not have the word BEC or No BEC on it means that the ESC does not have this function. This is why some ESCs have 7 wires and some have 8 wires. As shown in the figure below.

So how do we choose the ESC after knowing these parameters?