Driver mode
Term motor mode denotes the low-level control strategy of a motor. Contrary to closed-loop approach, these modes are implemented in the fundamental level, thus, enabling the highest possible dynamics without increasing the order of the dynamic system. Principle of Motor modes are shown on example of DC motor (even though the AC motor is driven in real) because its characteristics are easy to understand: DC motor current is proportional to torque and DC motor voltage is proportional to rpm. Motor modes are designed to make AC motor react in the same way, as DC motor would react.
- For easy explanation, the following modes are described for the brushed DC motor.
- This is shared for all families and all algorithms.
| Schematic for DC motor | mode | name | Description |
|---|---|---|---|
 | 0 | freewheel (FRW) | Motor freewheels, preferably by disconnecting from the drive. A current can be present due to automatic field weakening, but, the torque is never generated. Motor neither accelerates, nor brakes. |
 | 1 | voltage (VLT) | By setting the specified voltage, a stable speed of the shaft is usually achieved. The torque (and required current) is determined by the load. Torque (current) can be only limited (not controlled) by the user. Motor can accelerate and brake. |
 | 2 | current (CRT) | By setting the specified current, a stable torque of the motor is usually achieved. The speed is determined by the load and could be only limited (not controlled). Motor can accelerate and brake. |
 | 3 | voltage + freewheel (VLF) | By setting the specified voltage, a stable speed of the motor is usually achieved. The torque (and required current) is determined by the load. Torque (current) can be only limited (not controlled) by the user. Motor can accelerate but can not brake, unless the sign of the required voltage is changed. |
 | 4 | voltage brake (VLB) | This mode is the inversion of the mode 3. The motor freewheels from zero RPM until it reaches the specified voltage. After that, currents starts to flow into the battery and motor starts to brake. Motor can not a accelerate in this mode, only brake. |
 | 5 | stator current (SCR) | Similar to mode 2, but the total amplitude of stator current is demanded (not only the Qcomponent as if mode 2). (in BLDC, this mode reduces to mode 2) |
 | 6 | torque (TRQ) | This mode is similar to mode 2, but the driver attempts to control the real torque (with regards to variable flux with d-axis control). (in BLDC, this mode reduces to mode 2) |
 | 8 | brake (BRK) | Brake with constant current. Similar to mode 2, but current has always the direction to generate brake torque. The motor in this mode never accelerates. |
 | 9 | brake torque (BRT) | Similar to mode 8, but real torque is calculated from motor parameters. Real torque (not current) is regulated as in mode 6. (in BLDC, this mode reduces to mode 8) |
 | 10 | brake + freewheel (BRF) | Unidirectional brake with constant torque. For one direction is same as mode 8, for other direction, the motor freewheels. |
 | 15 | brake short (BRS) | Speed-dependent brake. Brake torque is proportional to motor speed. The higher speed, the higher brake torque. The motor in this mode never accelerates. |
*If you set non-existing mode, the driver will set freewheel mode.
- The torque mode (6) and brake torque mode (9) tries to linearize the torque curve and can reduce the maximal current if the
fwcordxcis set (it simply reserves some available current for the d-axis). So if you want to achieve the maximal torque use the current mode (2).
Extended modes
You can add these bits to previous standard modes to enable extended modes. This will engage the PID loop on top.
| Bit | Name |
|---|---|
| 4 | Speed loop |
| 5 | Position loop |
Due to memory constraints, extended modes are not always available. If you do not see folder /driver/pid_speed or /driver/pid_position, the extended modes are not present in your firmware.