ESC is the acronym of electric Speed Controller, it is used in Sensorless BLDC Motor driver application, like as Plane Model, Mobile Model and Boat Model. These BLDC motors drive the propeller to rotate and push the air/water flow, then create the power to drive the model running. ESC can drive the motor to different speed so that to create different power, to control the model status.
ESC includes one processor and several power driver circuits, it has many different kinds based on different power output and different control mode.
Traditional ESC solution for drones uses a 8-bit MCU to drive six MOSFETs to drive the three phases of the BLDC motor, so as to drive the motor rotation. It uses PWM square wave drive as the control mode, which includes 6 tempos in each cycle, 6 MOSFETs switches as pairs in accordance with the sequence of the 6 tempos. The output phase current & line current are 3-level trapezoidal wave. This control method is simple and limited, which outputs a big torque and very high speed up to 30000rpm.
However, since the modulated phase current & line current are discontinuous and the current control is in open mode, it causes the motor torque to be in pulsation status, which will generate noise during motor rotation. Meanwhile, since the current frequency range is very wide, those unwanted frequency components will be converted into heat, which causes the motor to overheat and reduces the energy efficiency. Furthermore, due to the open-loop current, the processor cannot detect the motor status, such as open, short or other faults, so that the reliability is reduced.
To solve these problems, the common study in this industry is how to use FOC Field Oriented Control Principle to control the BLDC motor, to convert the phase current & line current waveform to sine wave, so as to reduce power consumption and motor noise. Since FOC control mode requires the processor to perform various transforms and calculations of the magnetic field coordinates, in order to ensure the stator and the rotor to be always orthogonal, to maximize the output efficiency of the motor torque, thus it put forward higher requirements to the processing capability of the processor. At the same time, closed-loop current control mode must be used. As a result, the calculation load is so much increased that a 8-bit processor cannot even undertake. The current popular way to solve this is to use an ARM core processor, such as Cortex_M0, M3 and M4 core processor. The biggest difference is the cost is increased relatively, and the performance and cost are two contradictions that must find a proper balance.
The ESC solution by Future Electronics is an excellent solution especially designed for multi-rotor drones. By combining ST’s M4 processor and Infineon’s new pre-driver products and MOSFET, it enables small size, light weight, powerful functions, and better heat dissipation. It uses FOC field oriented control mode directly to drive sensorless BLDC motor, which significantly improves the overall performance, and provides an excellent overall solution which increases the energy efficiency and reliability, as well as reduces the motor noise and other issues. EVT-105 mainly targets at 20A ESC market currently, and applies to various 2212-type motors with speed up to 15000rpm, which is the main market of consumer drones. With good ventilation, EVT-105 can work at 20A current continuously and at 35A shortly (10 seconds), which can fully meet the basic needs of the customers.
EVT-105 also has a range of upper computer control functions, you can use the traditional PWM interface mode with the frequency range of 50Hz to 400Hz, or CAN interface mode to enable bidirectional communication, so the flight control system can realize the real- time monitoring of the motor running status, which increases the overall reliability of the drone system. High power ESC can be easily achieved by replacing the corresponding MOSFET and pre-driver in our solution.
In order to transform our EVT-105 into reliable products which can be mass produced, customers need to do secondary development. The main task is the development of upper layer application software, such as power-on self-test, motor parameter setting, adaptive algorithms, upper computer communication, fault detection and processing software. Since we provides the underlying software, it can reduce the development time and enable faster time to market for customer’s products.
The FOC control algorithm in Future’s ESC solution is the core and most essential part of this solution. It is based on Future’s proprietary library function, which improves some precise control sections of ST’s current algorithm library, makes the FOC control algorithm more proven and stable. Our algorithm can be accessed by our partners in the form of library functions, which will simplify customer’s design, enable customer’s engineers to understand the FOC control theory more easily and quickly, to complete their own product design for faster time to market and economic benefits.
Since we use Cortex-M4 processor in our ESC solution, the cost is higher than traditional ESC solutions, which is of great concern to customers. We are proactively consulting with the supplier to reduce the cost for customers and make the FOC control solution more popular in the entire market. We believe the processor cost will be reduced once it is widely used.
Key Components of Future ESC with FOC mode:
The Specialty of Future ESC with FOC mode:
- 20A/12V driver power output;
- Driver Sensorless BLDC motor;
- SINE_FOC control;
- Max Speed: 70% of Motor highest speed;
- Feedback energy to charge battery at braking;
- Single Resistor Sampling,Current_Closed_Loop Topo One AMP internal in MCU,Save external AMP cost;
- Over current protection;
- Configurable CAN Interface;
- Small Size,30X40mm;
- Low Cost for FOC ESC.
The Advantage of Future ESC with FOC mode:
- FOC control mode;
- Reduce the running noise from motor;
- Reduce the heat from driver circuit;
- Improve the battery power efficiency 10%;
- High_end drone by CAN;
- Small Size and acceptable Cost;