Definition
Speed controllers - in the English-speaking community are called - Electric Speed Controller (electronic speed controller) or abbreviated - ESC. The main task of the ESC is to transfer energy from the battery to the brushless motor. The need for their use arose due to some features of the BC - motor. In short, the battery supplies direct current, while the brushless motor accepts three-phase alternating current.
Operating principle
Communication with other components of the multicopter.
The ESC input is supplied with voltage from the battery and signals from the flight controller, and the output is the control voltage for the drive. Accordingly, the regulator must provide:
- Compatibility with the flight controller.
- Maximum motor current (calculated from motor and propeller specifications) plus 20 - 30%.
- The current consumption is less than the current delivered by the battery divided by the number of ESCs.
* The simplest connection diagram.
What kind of regulators are there?
BEC and UBEC
In addition to the main function, ESCs can also transmit power to other parts of the drone: flight controller, servos, and so on. This is achieved by introducing a Battery Eliminator Circuit (hereinafter referred to as BEC) into the regulator.
The use of BEC greatly simplifies the design of the drone, however, such a scheme has a number of disadvantages. The battery exclusion unit can overheat under high voltage fluctuations and heavy loads. In addition, ESCs with BEC tend to be more expensive than ESCs without a block.
Agree, it would be more logical and cheaper to make a separate ESC and one BEC separately. There is such a solution and it is called the Universal Battery Eliminator Circuit (hereinafter referred to as UBEC).
UBEC Benefits
UBEC - connects directly to the battery and powers the desired drone assembly. The advantages of this approach are very significant:
- Speed controllers will overheat less, since BEC will be excluded from them
- UBECs have a high efficiency
- Therefore, from the previous two paragraphs UBEC is capable of delivering more current with less risk
- No overpayment for a few extra BECs located in an ESC. For some flight controllers, it is highly discouraged to connect more than one ESC BEC
- Lighter weight of the controls
Types of BECs and their advantages
BECs are of two types: linear (LBEC) and pulse (SBEC).
- Linear converts energy into heat, and turns off when overheated. This can lead to unpleasant results: at best, the copter will not be able to take off, and at worst, an uncontrolled fall. In this connection, it began to be used in an assembly with servo drives, which, in turn, do not consume much current, preventing the unit from overheating.
- Pulse regulates the voltage by quickly turning the power on and off, this approach eliminated overheating, increased the output power, and allowed to reach 90% efficiency, as well as pulse BECs outperform linear ones in weight. Interference arising in the circuit, which adversely affects the operation of radio equipment, is eliminated by the addition of an LC filter.
Considering that many manufacturers install filters on their UBECLC (and if there is still no filter, then it can be bought cheap and easy to install), professionals use SBEC regulators in their drones.
Software ESC
Since the speed controller performs some conversions at a high frequency and can be configured for different modes of operation, a separate software called firmware is written for it. This allows you to correct past errors in control algorithms, create more advanced firmware (and thereby, for example, reduce battery consumption on average gas) and make flexible settings. In drones from well-known companies such as DJI, the controller software is changed automatically using the flight controller.
Attention! Overwriting the software for speed controllers may result in various breakdowns of the drone, as well as cancellation of warranty service! Remember that you are doing this at your own peril and risk!
How do I change the software?
There are several ways to change the controller software:
- Using the dedicated control board
- Using the flight controller
- Using the ASP programmer
The third option is simpler and is currently being actively implemented in new models.
Choice of governor
Based on all of the above, there are special criteria for choosing a governor for drone:
- Compatible with flight controller. The flight controller must support BEC and ESC firmware.
- Compatible with motor and battery specifications.
- The presence or absence of BEС and its type (LBEC or SBEC).
- Heat dissipation and tightness.
