Under the nation's continuous strengthening of energy conservation and emission reduction policies, high efficiency, quiet operation, and intelligence have become key trends in industrial or household electronic products. In response, Fortior has introduced FU68 series MCUs (including FU6811, FU6812, FU6813, FU6831, FU6832, FU6818, and FU6861), which feature a "dual-core" architecture integrating an 8051 core and ME core. 8051 core is used for parameter configuration and routine processing. ME core implements motor control in real time. These chips integrates high-speed operational amplifiers, high-speed ADC, and high-voltage LDO, enabling efficient FOC (Field-Oriented Control) motor drive with minimal peripheral circuitry. The sensorless FOC drive of FU6811 is primarily used in various fans and water pumps, with typical applications including indoor and outdoor units of air conditioners, range hoods, washing pumps, ceiling fans, and standing fans.

This application case mainly introduces the features and control methods of FU68 series sensorless FOC drive solution and the control features and functions of example programs.

FU68 series application features：

■ FOC solidification and fast operation: All computations for FOC are hardware-implemented, saving software runtime. With a maximum PWM frequency of 40 kHz, the chip can be applied to ultra-high-speed motors (>25000RPM);

■ High control accuracy and efficiency: FOC uses Q15 format, mapping the 360° electrical angle to 2^15, which achieves an angular resolution of 0.01° for high-precision motor control. The optimized position estimation algorithm further enables high-efficiency operation;

■ Low noise: FOC algorithm accurately controls drive current waveform as smooth sinusoidal waveform, reduces torque ripple, and also implements ultra-mute operation;

■ Smooth and fast startup: This solution adjusts the startup torque and startup mode based on load torque variations, ensuring reliable and smooth startup. Startup time is 50% shorter than that of normal startup mode;

■ Simple hardware circuit: The chip integrates high-speed operational amplifier, high-voltage LDO, and minimal peripheral circuitry to lower the product cost and improve the reliability of the system.

Applications:

To facilitate customer development, Fortior has developed a sample program for FOC drive solution for FU68 series, which features the following characteristics:

1. Startup Control

(1) Detect motor initial state and realize dynamic startup (including tailwind and headwind detection)

(2) Adjust startup torque according to changes in load torque to improve startup reliability

(3) Select startup mode and time as required

(4) Set the max. startup current

2. Control Mode

(1) The current closed-loop serves as the inner loop, while various control options such as constant airflow control, constant torque control, constant speed control, and constant power control can be selected as the outer loop

(2) Speed regulation interface: SREF/PWM/UART

3. State Display

LED indicates the system's operational status (Normal/Fault).

4. Protection Control

The chip supports various protection features to meet different application scenarios.

(1) Over-voltage protection: The over-voltage protection is triggered when the voltage is higher than the over-voltage threshold and the system restarts when the voltage is lower than the restore threshold

(2) Under-voltage protection: The under-voltage protection is triggered when the voltage is lower than the under-voltage threshold and the system restarts when the voltage is higher than the restore threshold

(3) Over-current protection: The over-current protection is triggered when the current is higher than the over-current threshold and you can set restart times

(4) FO protection: The hardware over-current protection is impulsed by large current and the system stops

(5) Motor lock protection: Motor lock restart time and the number of motor lock restart attempts can be configured

(6) Phase-loss protection: Phase-loss protection works in the event of poor motor wire contact. Restart time and the number of attempts can be configured

(7) Over-temperature protection: The over-temperature protection is triggered when the temperature is higher than the over-temperature threshold and the system restarts when the temperature is lower than the restore threshold

5. User Interface

The chip provides a variety of interfaces for control requirements.

(1) Key interface: Define key interface and transfer Key command. You can define Key commands, like ONOFF control command

(2) SREF interface: Provide potentiometer value for ADC sampling and give SREF commands. You can define SREF commands, like closed-loop Speed reference value

(3) PWM interface: Capture PWM signal, gain PWMDuty, and give PWM command. You can define PWM commands, like closed-loop Speed reference value

(4) UART interface: Provide UART command after receiving UART data. You can define UART commands, like ONOFF control command, FR control command, closed-loop Speed reference value

(5) Buzzer interface: Define buzzer interface and receive control command, realizing alarm or warning. You can define Buzzer commands, like key warning control, gear tone control

6. Debugging Interface

Under the default functional settings, the program provides the Customer.h document as your debugging interface. You can only modify the corresponding parameters to achieve general motor control functions.

FU68 series evaluation boards：

Low-voltage application evaluation board (FU6831, FU6832), supports power 50W and voltage DC7-36V;

Middle-voltage application evaluation board (FU6818, FU6861), supports power 200W and voltage DC12-80V;

High-voltage application evaluation board (FU6811, FU6812, FU6813) is divided into low-power universal demo board, supporting 100W power and ceiling fan dedicated demo board supporting 50W power and AC220V voltage; middle-power universal demo board and range hoods dedicated demo board, supporting 250W power and AC220V voltage; high-power universal demo board and food processor demo board, supporting 2000W power.

Low-power evaluation board FU6811 includes:

1. FU6811 high-voltage drive board

2. FU68XX emulator

3. FOC Application Debugging Note

Figure 1 FU6811 High-voltage Driver Board

Schematic Diagram: